Zdeněk Dvořák

2011

• A. Novotna, P. Petr, and Z. Dvorak, “Novel Stably Transfected Gene Reporter Human Hepatoma Cell Line for
  Assessment of Aryl Hydrocarbon Receptor Transcriptional Activity:
  Construction and Characterization,” ENVIRONMENTAL SCIENCE & TECHNOLOGY, vol. 45, iss. 23, pp. 10133-10139, 2011.
  [Bibtex]

  @article ISI:000297382700045,
  Author = Novotna, Arleta and Petr, Pavek and Dvorak, Zdenek,
  Title = Novel Stably Transfected Gene Reporter Human Hepatoma Cell Line for
     Assessment of Aryl Hydrocarbon Receptor Transcriptional Activity:
     Construction and Characterization,
  Journal = ENVIRONMENTAL SCIENCE \& TECHNOLOGY,
  Year = 2011,
  Volume = 45,
  Number = 23,
  Pages = 10133-10139,
  Month = DEC 1,
  Abstract = We constructed stably transfected gene reporter cell line AZ-AHR,
     allowing measurement of aryl hydrocarbon receptor (AhR) transcriptional
     activity. Human hepatoma HepG2 cells were transfected with a construct
     containing several AhR binding sites upstream of luciferase reporter
     gene. We prepared 12 clones and we characterized the best five in
     responsiveness to TCDD. Dose response analyses were performed for
     various AhR ligands, including TCDD, 3-methylcholanthrene, indirubin,
     resveratrol, omeprazole, and SP600125. The EC(50) values were similar in
     all tested clones. Induction of luciferase was time-dependent, and
     treatment for 6 h with 5 nM TCDD was sufficient to evaluate AhR
     transcriptional activity in 96-well plate format (8-24 fold induction).
     Response to AhR ligands of cryopreserved cells after thawing was not
     significantly different from that of fresh cells. Cell line remained
     fully responsive to AhR ligands over 15 passages and 30 days in culture
     without significant alterations. Overall, we have developed novel human
     luciferase reporter cell line AZ-AHR for monitoring AhR transcriptional
     activity. The sensitivity of the assay allows high throughput format
     (96-well plate) and evaluation of luciferase activity as soon as after 6
     h of incubation, which has potential implication for studies of
     cytotoxic compounds.,
  DOI = 10.1021/es2029334,
  ISSN = 0013-936X,
  Unique-ID = ISI:000297382700045,
  

• L. Krausova, L. Stejskaova, H. Wang, R. Vrzal, Z. Dvorak, S. Mani, and P. Pavek, “Metformin suppresses pregnane X receptor (PXR)-regulated transactivation
  of CYP3A4 gene,” BIOCHEMICAL PHARMACOLOGY, vol. 82, iss. 11, pp. 1771-1780, 2011.
  [Bibtex]

  @article ISI:000296931400026,
  Author = Krausova, Lucie and Stejskaova, Lucie and Wang, Hongwei and Vrzal, Radim
     and Dvorak, Zdenek and Mani, Sridhar and Pavek, Petr,
  Title = Metformin suppresses pregnane X receptor (PXR)-regulated transactivation
     of CYP3A4 gene,
  Journal = BIOCHEMICAL PHARMACOLOGY,
  Year = 2011,
  Volume = 82,
  Number = 11,
  Pages = 1771-1780,
  Month = DEC 1,
  Abstract = Metformin is widely used in the treatment of type-2 diabetes. The
     pleotropic effects of metformin on glucose and lipid metabolism have
     been proposed to be mediated by the activation of AMP-activated protein
     kinase (AMPK) and the subsequent up-regulation of small heterodimer
     partner (SHP). SHP suppresses the functions of several nuclear receptors
     involved in the regulation of hepatic metabolism, including pregnane X
     receptor (PXR), which is referred to as a ``master regulator'' of
     drug/xenobiotic metabolism.
     In this study, we hypothesize that metformin suppresses the expression
     of CYP3A4, a main detoxification enzyme and a target gene of PXR, due to
     SHP up-regulation.
     We employed various gene reporter assays in cell lines and qRT-PCR in
     human hepatocytes and in Pxr(-/-) mice.
     We show that metformin dramatically suppresses PXR-mediated expression
     of CYP3A4 in hepatocytes. Consistently, metformin significantly
     suppressed the up-regulation of Cyp3a11 mRNA in the liver and intestine
     of wild-type mice, but not in Pxr-/- mice. A mechanistic investigation
     of the phenomenon showed that metformin does not significantly
     up-regulate SHP in human hepatocytes. We further demonstrate that AMPK
     activation is not involved in this process. We show that metformin
     disrupts PXR's interaction with steroid receptor coactivator-1 (SRC1) in
     a two-hybrid assay independently of the PXR ligand binding pocket.
     Metformin also inhibited vitamin D receptor-, glucocorticoid receptor-
     and constitutive androstane receptor (CAR)-mediated induction of CYP3A4
     mRNA in human hepatocytes.
     We show, therefore, a suppressive effect of metformin on PXR and other
     ligand-activated nuclear receptors in transactivation of the main
     detoxification enzyme CYP3A4 in human hepatocytes. (C) 2011 Elsevier
     Inc. All rights reserved.,
  DOI = 10.1016/j.bcp.2011.08.023,
  ISSN = 0006-2952,
  Unique-ID = ISI:000296931400026,
  

• A. Novotna, A. Doricakova, R. Vrzal, P. Pavek, and Z. Dvorak, “Construction and characterization of hepatocyte nuclear factor
  HNF4alpha1 over-expressing cell line derived from human hepatoma HepG2
  cells,” EUROPEAN JOURNAL OF PHARMACOLOGY, vol. 669, iss. 1-3, pp. 45-50, 2011.
  [Bibtex]

  @article ISI:000296989500007,
  Author = Novotna, Aneta and Doricakova, Aneta and Vrzal, Radim and Pavek, Petr
     and Dvorak, Zdenek,
  Title = Construction and characterization of hepatocyte nuclear factor
     HNF4alpha1 over-expressing cell line derived from human hepatoma HepG2
     cells,
  Journal = EUROPEAN JOURNAL OF PHARMACOLOGY,
  Year = 2011,
  Volume = 669,
  Number = 1-3,
  Pages = 45-50,
  Month = NOV 1,
  Abstract = Cancer cell lines derived from hepatocytes have an altered phenotype and
     they lack hepatocyte-specific functions. It is at least partly due to
     the under-expression of transcription factors such as hepatocyte nuclear
     factor 4 alpha (HNF4 alpha), steroid receptor co-activator 1 (SRC1) etc.
     Recently, a strategy of transient transfection of human hepatic cells
     with HNF4 alpha revealed improved hepatospecific functions, including
     the expression of drug-metabolizing enzymes. In the current study we
     established a human cell line derived from HepG2 cells stably
     transfected with human HNF4 alpha, and we examined this line for
     hepatospecific markers. Of the 9 clones analyzed, we found an increased
     secretion of fibrinogen (9 clones), albumin (5 clones) and plasminogen
     (3 clones), while secretion of alpha1-antitrypsin was not changed. The
     expression of pregnane X receptor (PXR) and aryl hydrocarbon receptor
     (AhR) proteins but not mRNAs was slightly increased. TCDD-dependent
     induction of CYP1A1 mRNA and protein was augmented in 50\% of clones,
     but there was no correlation between the CYP1A1 inducibility and
     expression levels of AhR and HNF4 alpha. Induction of CYP3A4 mRNA by
     rifampicin was about 1.5-2.5 fold (clones 2, 4, 6,7) and it was not
     significantly different from CYP3A4 mRNA induction in parent HepG2. The
     basal expression of CYP3A4 protein was increased in all clones, but
     rifampicin-induced expression of CYP3A4 protein was in all clones lower
     than in parent HepG2. Overall, the stable over-expression of HNF4 alpha
     in HepG2 cells restores some of the hepatospecific functions, but it has
     a minor effect on the expression of xenobiotic-metabolizing enzymes and
     their regulators. (C) 2011 Elsevier B.V. All rights reserved.,
  DOI = 10.1016/j.ejphar.2011.07.049,
  ISSN = 0014-2999,
  Unique-ID = ISI:000296989500007,
  

• L. Stejskalova, L. Vecerova, L. M. Perez, R. Vrzal, Z. Dvorak, P. Nachtigal, and P. Pavek, “Aryl Hydrocarbon Receptor and Aryl Hydrocarbon Nuclear Translocator
  Expression in Human and Rat Placentas and Transcription Activity in
  Human Trophoblast Cultures,” TOXICOLOGICAL SCIENCES, vol. 123, iss. 1, pp. 26-36, 2011.
  [Bibtex]

  @article ISI:000294557500003,
  Author = Stejskalova, Lucie and Vecerova, Lenka and Perez, Laura Mesa and Vrzal,
     Radim and Dvorak, Zdenek and Nachtigal, Petr and Pavek, Petr,
  Title = Aryl Hydrocarbon Receptor and Aryl Hydrocarbon Nuclear Translocator
     Expression in Human and Rat Placentas and Transcription Activity in
     Human Trophoblast Cultures,
  Journal = TOXICOLOGICAL SCIENCES,
  Year = 2011,
  Volume = 123,
  Number = 1,
  Pages = 26-36,
  Month = SEP,
  Abstract = Aryl hydrocarbon receptor (AHR) and its heterodimer aryl hydrocarbon
     nuclear translocator (ARNT) form a ligand-activated transcription
     complex that regulates expression of the AHR battery of target genes
     that includes the most important placental biotransformation enzyme
     cytochrome CYP1A1. Expression, placental localization, and ontogeny of
     AHR/Ahr and ARNT/Arnt have not been systematically studied in either
     human or rat placentas. Moreover, induction of such AHR target genes as
     CYP1A1, CYP1A2, CYP1B1, UGT1A1, and breast cancer resistance protein
     (BCRP), as well as of AHR, ARNT, and aryl hydrocarbon receptor repressor
     (AHRR) genes, after exposure to AHR ligands have not been studied in
     human placental trophoblast cultures. In this article, we show that only
     CYP1A1 messenger RNA (mRNA), but not CYP1A2, CYP1B1, UGT1A1, BCRP, AHR,
     ARNT, and AHRR mRNAs, is significantly induced in human term placental
     trophoblast cultures after exposure to prototype AHR ligands/activators
     2,3,7,8-tetrachlorodibenzo-p-dioxin, 3-methylcholanthrene, omeprazole,
     and beta-naphthoflavone. We localized AHR/Ahr and ARNT/Arnt in rat
     placental trophoblasts throughout gestation and in first trimester and
     term human placental trophoblast, which comprise the crucial component
     of the maternal-fetal barrier. We demonstrate that rat Ahr and Cyp1a1
     reached highest expression during gestation days 15 and 18, which might
     indicate different response to Ahr ligands in placental Cyp1a1 induction
     during rat gestation. We also propose the JEG3 choriocarcinoma cell line
     as a cellular model for human trophoblast induction studies through AHR.
     In conclusion, we describe expression and ontogeny of AHR/Ahr and
     ARNT/Arnt and systematically characterize induction of major AHR target
     genes in human placental trophoblast forming the placental
     maternal-fetal morphological and metabolic barrier.,
  DOI = 10.1093/toxsci/kfr150,
  ISSN = 1096-6080,
  Unique-ID = ISI:000294557500003,
  

• Z. Dvorak, A. Kamenickova, and R. Vrzal, “Examination of extracts from iced-teas on regulatory pathways of
  drug-metabolizing enzymes in human hepatocytes and cell lines,” TOXICOLOGY LETTERS, vol. 205, iss. 1, pp. S140, 2011.
  [Bibtex]

  @article ISI:000293814500447,
  Author = Dvorak, Z. and Kamenickova, A. and Vrzal, R.,
  Title = Examination of extracts from iced-teas on regulatory pathways of
     drug-metabolizing enzymes in human hepatocytes and cell lines,
  Journal = TOXICOLOGY LETTERS,
  Year = 2011,
  Volume = 205,
  Number = 1,
  Pages = S140,
  Month = AUG 28,
  Note = 47th Congress of the European-Societies-of-Toxicology, Paris, FRANCE,
     AUG 28-31, 2011,
  Organization = European Soc Toxicol,
  DOI = 10.1016/j.toxlet.2011.05.497,
  ISSN = 0378-4274,
  Unique-ID = ISI:000293814500447,
  

• M. Bitman, Z. Dvorak, R. Vrzal, L. Stejskalova, and P. Pavek, “The cross-talk of extracellular signal-regulated protein kinase (ERK)
  and pregnane X receptor (PXR) and its effect on expression of CYP3A4 and
  MDR1 genes in primary human hepatocytes and hepatoma cell lines,” TOXICOLOGY LETTERS, vol. 205, iss. 1, pp. S293, 2011.
  [Bibtex]

  @article ISI:000293814500938,
  Author = Bitman, M. and Dvorak, Z. and Vrzal, R. and Stejskalova, L. and Pavek,
     P.,
  Title = The cross-talk of extracellular signal-regulated protein kinase (ERK)
     and pregnane X receptor (PXR) and its effect on expression of CYP3A4 and
     MDR1 genes in primary human hepatocytes and hepatoma cell lines,
  Journal = TOXICOLOGY LETTERS,
  Year = 2011,
  Volume = 205,
  Number = 1,
  Pages = S293,
  Month = AUG 28,
  Note = 47th Congress of the European-Societies-of-Toxicology, Paris, FRANCE,
     AUG 28-31, 2011,
  Organization = European Soc Toxicol,
  DOI = 10.1016/j.toxlet.2011.05.990,
  ISSN = 0378-4274,
  Unique-ID = ISI:000293814500938,
  

• L. Stejskalova, L. Vecerova, R. Vrzal, Z. Dvorak, P. Nachtigal, and P. Pavek, “AHR and ARNT expression in the human and rat placentas and their
  transcription activity in human trophoblast cultures in transactivation
  AHR battery genes,” TOXICOLOGY LETTERS, vol. 205, iss. 1, pp. S300, 2011.
  [Bibtex]

  @article ISI:000293814500961,
  Author = Stejskalova, L. and Vecerova, L. and Vrzal, R. and Dvorak, Z. and
     Nachtigal, P. and Pavek, P.,
  Title = AHR and ARNT expression in the human and rat placentas and their
     transcription activity in human trophoblast cultures in transactivation
     AHR battery genes,
  Journal = TOXICOLOGY LETTERS,
  Year = 2011,
  Volume = 205,
  Number = 1,
  Pages = S300,
  Month = AUG 28,
  Note = 47th Congress of the European-Societies-of-Toxicology, Paris, FRANCE,
     AUG 28-31, 2011,
  Organization = European Soc Toxicol,
  DOI = 10.1016/j.toxlet.2011.05.1013,
  ISSN = 0378-4274,
  Unique-ID = ISI:000293814500961,
  

• B. Cvek and Z. Dvorak, “The Ubiquitin-Proteasome System (UPS) and the Mechanism of Action of
  Bortezomib,” CURRENT PHARMACEUTICAL DESIGN, vol. 17, iss. 15, pp. 1483-1499, 2011.
  [Bibtex]

  @article ISI:000295455800010,
  Author = Cvek, Boris and Dvorak, Zdenek,
  Title = The Ubiquitin-Proteasome System (UPS) and the Mechanism of Action of
     Bortezomib,
  Journal = CURRENT PHARMACEUTICAL DESIGN,
  Year = 2011,
  Volume = 17,
  Number = 15,
  Pages = 1483-1499,
  Month = MAY,
  Abstract = Proteasome inhibition is a modern and surprisingly successful approach
     how to cancer treatment. Bortezomib(Velcade (R)) is a first-in-class
     proteasome inhibitor and has been approved for first-line treatment of
     multiple myeloma and second-line treatment of mantle cell lymphoma.
     There have been almost 200 clinical trials with bortezomib, both as a
     single agent and in combination with other drugs, for various cancers,
     as listed in the US National Cancer Institute database. However,
     bortezomib's mechanism of action remains elusive despite enormous
     progress in our knowledge of the cell biology of the
     ubiquitin-proteasome system (UPS) and bortezomib-induced signaling
     events in cancer cells. This review maps a rapidly growing and open body
     of research in both areas.,
  ISSN = 1381-6128,
  Unique-ID = ISI:000295455800010,
  

• K. Wlcek, M. Svoboda, J. Riha, S. Zakaria, U. Olszewski, Z. Dvorak, F. Sellner, I. Ellinger, W. Jaeger, and T. Thalhammer, “The analysis of organic anion transporting polypeptide (OATP) mRNA and
  protein patterns in primary and metastatic liver cancer,” CANCER BIOLOGY & THERAPY, vol. 11, iss. 9, pp. 801-811, 2011.
  [Bibtex]

  @article ISI:000290088100003,
  Author = Wlcek, Katrin and Svoboda, Martin and Riha, Juliane and Zakaria, Susanna
     and Olszewski, Ulrike and Dvorak, Zdenek and Sellner, Franz and
     Ellinger, Isabella and Jaeger, Walter and Thalhammer, Theresia,
  Title = The analysis of organic anion transporting polypeptide (OATP) mRNA and
     protein patterns in primary and metastatic liver cancer,
  Journal = CANCER BIOLOGY \& THERAPY,
  Year = 2011,
  Volume = 11,
  Number = 9,
  Pages = 801-811,
  Month = MAY 1,
  Abstract = Organic anion transporting polypeptides (OATP, SLCO genes) mediate the
     uptake of endobiotics and drugs. Thus, their expression levels and
     pattern could be of relevance for cancer therapy. This prompted us to
     investigate the expression of poorly characterized OATPs, namely
     OATP2A1, OATP3A1, OATP4A1 and OATP5A1 in hepatic cancer of different
     origin. First, mRNA levels of all eleven OATPs were determined in paired
     (cancerous and adjacent non-cancerous) specimens from 43 patients with
     primary liver cancer (hepatocellular carcinoma, HCC; cholangiocellular
     carcinoma, CCC) and liver metastases from colon tumors (MLT). Real-time
     RT-PCR analysis revealed that all OATPs, except OATP1C1 and OATP6A1, are
     extensively expressed in nearly all samples. In contrast to
     downregulated OATP1B1, OATP1B3, OATP1A2 and OATP2B1 in cancerous vs.
     non-cancerous samples, an increase in OATP2A1, OATP3A1, OATP4A1 and
     OATP5A1 mRNA levels was seen in tumors (up to 40-fold for OATP5A1 in the
     MLT group). Therefore, OATP2A1, OATP3A1, OATP4A1 and OATP5A1 were
     further investigated by immunofluorescence microscopy on
     paraffin-embedded cancerous and non-cancerous sections (seven per
     group). OATP-derived immunoreactivity was observed in plasma membranes
     and cytosol of hepatic tumor cells, and additionally, in various
     cytokeratin 19 positive bile ducts. An increased percentage of
     immunoreactive cells and a higher staining intensity in cancerous vs.
     non-cancerous paraffin sections paralleled higher mRNA levels of
     OATP2A1, OATP3A1, OATP4A1 and OATP5A1 in cancerous tissues of HCC, CCC
     and MLT patients. The extensive expression of OATP2A1, OATP3A1, OATP4A1
     and OATP5A1 in hepatic tumors of different origin suggests that these
     transporters might be further exploited for the discovery of novel
     anticancer agents.,
  DOI = 10.4161/cbt.11.9.15176,
  ISSN = 1538-4047,
  Unique-ID = ISI:000290088100003,
  

• Z. Dvorak, “Drug-drug interactions by azole antifungals: Beyond a dogma of CYP3A4
  enzyme activity inhibition,” TOXICOLOGY LETTERS, vol. 202, iss. 2, pp. 129-132, 2011.
  [Bibtex]

  @article ISI:000289708000007,
  Author = Dvorak, Zdenek,
  Title = Drug-drug interactions by azole antifungals: Beyond a dogma of CYP3A4
     enzyme activity inhibition,
  Journal = TOXICOLOGY LETTERS,
  Year = 2011,
  Volume = 202,
  Number = 2,
  Pages = 129-132,
  Month = APR 25,
  Abstract = Azoles antifungals are widespread used drugs for various medicinal
     indications. These drugs are well known for their numerous drug-drug
     interactions, which are believed to occur via inhibition of CYP3A4
     enzymatic activity and consequently altering pharmacokinetic of
     co-administered drugs. In the current communication a complex view on
     the molecular interactions between azoles antimycotics and CYP3A4 is
     presented. Beside inhibition of CYP3A4 catalytic activity, azoles
     influence transcriptional activity of pregnane X receptor (PXR) and
     consequently expression of drug-metabolizing enzymes, including CYP3A4.
     Interactions between azoles and PXR occur by multiple mechanisms,
     including modulation of ligand-dependent activation of PXR (agonism,
     antagonism) or affecting recruitment of PXR co-activators SRC-1 (steroid
     receptorco-activator 1)and HNF4 alpha (hepatocyte nuclear factor 4
     alpha). Miconazole and ketoconazole are antagonists of glucocorticoid
     receptor (GR), therefore these drugs inhibit GR-mediated expression of
     PXR and drug metabolizing cytochromes P450. In addition, PXR and GB are
     key regulators of intermediary metabolism (e.g. carbohydrate, lipids or
     bile acids homeostasis) and many other cellular functions (e.g. immune
     response), hence, the interactions between azoles and PXR/GR are of
     broader physiological importance. In conclusion, while inhibition of
     CYP3A4 enzymatic activity by azoles is considered as primary cause of
     azoles drug-drug interactions, the effects of azoles on PXR and GR
     should be taken in account. Apart from CYP3A4, azoles influence the
     expression and activity of others drug-metabolizing cytochromes P450.
     (C) 2011 Published by Elsevier Ireland Ltd.,
  DOI = 10.1016/j.toxlet.2011.01.027,
  ISSN = 0378-4274,
  Unique-ID = ISI:000289708000007,
  

• Z. Dvorak, P. Starha, and Z. Travnicek, “Evaluation of in vitro cytotoxicity of 6-benzylaminopurine carboplatin
  derivatives against human cancer cell lines and primary human
  hepatocytes,” TOXICOLOGY IN VITRO, vol. 25, iss. 3, pp. 652-656, 2011.
  [Bibtex]

  @article ISI:000288933100008,
  Author = Dvorak, Zdenek and Starha, Pavel and Travnicek, Zdenek,
  Title = Evaluation of in vitro cytotoxicity of 6-benzylaminopurine carboplatin
     derivatives against human cancer cell lines and primary human
     hepatocytes,
  Journal = TOXICOLOGY IN VITRO,
  Year = 2011,
  Volume = 25,
  Number = 3,
  Pages = 652-656,
  Month = APR,
  Abstract = A series of seven platinum(II) cyclobutane-1,1-dicarboxylato (cbdc)
     complexes \[Pt(cbdc)(L(n))(2)], 1-7\, derived from carboplatin by a
     substitution of two NH(3) molecules for two 2,6,9-trisubstituted
     6-benzyl-aminopurinc-based N-donor ligands (L(n)), was studied by the
     MTT assay for their in vitro cytotoxic activity against seven human
     cancer cell lines, i.e. lung carcinoma (A549), cervix epithelioid
     carcinoma (HeLa), osteosarcoma (HOS), malignant melanoma (G361), breast
     adenocarcinoma (MCP), ovarian carcinoma (A2780) and its
     cisplatin-resistant analogue (A2780cis), and against two primary
     cultures of human hepatocytes (LH31 and LH32). The prepared complexes
     were cytotoxic against several cancer cells, in some cases even more
     than cisplatin. The best results were achieved for complexes 1 (IC(50) =
     17.4 +/- 2.0 mu M) and 2 (IC(50) = 14.8 +/- 2.1 mu M) against HOS cells,
     1 (IC(50) = 15.1 +/- 6.8 mu M), 2 (IC(50) = 13.6 +/- 5.2 mu M) and 6
     (IC(50) = 19.0 +/- 6.6 mu M) against MCF7, 6 (IC(50) = 6.4 +/- 0.1 mu M)
     against A2780, and 1-6 (IC(50) = 15.6 +/- 4.0, 12.9 +/- 3.7, 15.8 +/-
     3.8, 16.6 +/- 5.5, 22.1 +/- 2.5, and 5.6 +/- 1.7 mu M, respectively)
     against A2780cis. Viability of human hepatocytes was not declined by the
     tested complexes up to the concentration of 50 mu M (for 1, 3-7) and 20
     mu M (for 2; caused by lower solubility of this complex). (c) 2011
     Elsevier Ltd. All rights reserved.,
  DOI = 10.1016/j.tiv.2011.01.002,
  ISSN = 0887-2333,
  Unique-ID = ISI:000288933100008,
  

• R. Vrzal, A. Doricakova, A. Novotna, P. Bachleda, M. Bitman, P. Pavek, and Z. Dvorak, “Valproic acid augments vitamin D receptor-mediated induction of CYP24 by
  vitamin D3: A possible cause of valproic acid-induced osteomalacia?,” TOXICOLOGY LETTERS, vol. 200, iss. 3, pp. 146-153, 2011.
  [Bibtex]

  @article ISI:000287216900003,
  Author = Vrzal, Radim and Doricakova, Aneta and Novotna, Aneta and Bachleda, Petr
     and Bitman, Michal and Pavek, Petr and Dvorak, Zdenek,
  Title = Valproic acid augments vitamin D receptor-mediated induction of CYP24 by
     vitamin D3: A possible cause of valproic acid-induced osteomalacia?,
  Journal = TOXICOLOGY LETTERS,
  Year = 2011,
  Volume = 200,
  Number = 3,
  Pages = 146-153,
  Month = FEB 5,
  Abstract = Valproic acid (VPA) is a wide spread anticonvulsant and mood-stabilizing
     agent, the use of which is associated with hepatotoxicity, bone marrow
     suppression and osteomalacia. In the current paper we propose a possible
     mechanism of VPA-induced osteomalacia involving accelerated catabolism
     of 1 alpha,25(OH)(2)-vitamin D3 (VD3) due to increased expression of
     CYP24. We demonstrate that VPA strongly potentiates CYP24 mRNA
     expression by VD3 in human hepatocytes (HH) and in human embryonic
     kidney cells (HEK293). By the method of gene reporter assay we found
     that VPA increases basal and VD3-inducible activity of CYP24 promoter
     (pCYP24-luc) in human liver adenocarcinoma (HepG2) and in HEK293 cells
     in dose-dependent manner. In order to delineate the role of inhibitory
     effects of VPA on histone deacetylase 1 (HDAC1), we compared the effects
     of VPA with trichostatin A (TSA) on basal and inducible levels of CYP24
     mRNA and pCYP24-luc transactivation. Transactivation of CYP24 promoter
     by VD3 was enhanced in the presence of both TSA and VPA. In contrast,
     VD3-inducible expression of CYP24 mRNA was enhanced by VPA but not by
     TSA, implying that HDAC1 inhibition is not the major reason for VPA
     effects on CYP24. We examined the effects of VPA on mitogen-activated
     protein kinases as the important transcriptional regulators of VDR. VPA
     activated extracellular signal-regulated kinase (ERK) but not
     c-Jun-N-terminal kinase (JNK) and p38 MAPKs. In conclusion, VPA enhances
     transcriptional activity of VDR and increases expression of CYP24 mRNA
     in the presence of VD3 in physiological concentrations. The mechanism
     involves activation of ERR and partly the inhibition of HDAC1. (C) 2010
     Elsevier Ireland Ltd. All rights reserved.,
  DOI = 10.1016/j.toxlet.2010.11.008,
  ISSN = 0378-4274,
  Unique-ID = ISI:000287216900003,
  

• K. Monostory and Z. Dvorak, “Steroid Regulation of Drug-Metabolizing Cytochromes P450,” CURRENT DRUG METABOLISM, vol. 12, iss. 2, pp. 154-172, 2011.
  [Bibtex]

  @article ISI:000289085500007,
  Author = Monostory, Katalin and Dvorak, Zdenek,
  Title = Steroid Regulation of Drug-Metabolizing Cytochromes P450,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2011,
  Volume = 12,
  Number = 2,
  Pages = 154-172,
  Month = FEB,
  Abstract = Cytochrome P450 (P450) monooxygenases are capable of catalyzing
     metabolism of various endogenous and exogenous compounds, such as bile
     acids, fatty acids, retinoids, steroids, drugs and other xenobiotics.
     The enzymes, belonging to CYP1, CYP2 and CYP3 families are primarily
     involved in the metabolism of drugs and xenobiotics. P450-mediated
     defense mechanism protects organisms from the potentially toxic effects
     of xenobiotics to which they are exposed. The adaptive transcriptional
     induction of P450s by xenobiotics is mediated by aromatic hydrocarbon
     receptor of Per-ARNT-Sim family, and nuclear hormone receptors,
     including pregnane X receptor, constitutive androstane receptor and
     glucocorticoid receptor. In addition to the receptor-mediated induction,
     endogenous factors (developmental, sex or hormonal factors) can also
     modulate P450 expression. Steroid hormones are biologically active
     compounds, controlling many physiological processes via endocrine
     signaling pathways and contributing to the transcriptional regulation of
     drug-metabolizing P450s. Any change in P450 activities influences the
     rate of activation or inactivation of drugs. Exposure to xenobiotics
     (drugs, environmental pollutants) can exert changes in endocrine
     function both directly as hormone agonists/antagonists or indirectly
     altering the rates of hormone metabolism and consequently the
     circulating levels of hormones. Modulation of P450 expression by
     xenobiotics can affect the subsequent metabolism of not only foreign
     chemicals, but also steroid hormones. Perturbation in hormone metabolism
     leads to the imbalance in sexual and reproductive development, and in
     glucose, lipid and salt/water homeostasis. The purpose of this review is
     to highlight the interplay between drug-metabolizing P450s and steroid
     hormones as well as the interactions of xenosensor with steroid
     signaling pathways.,
  ISSN = 1389-2002,
  Unique-ID = ISI:000289085500007,
  

• L. Stejskalova, Z. Dvorak, and P. Pavek, “Endogenous and Exogenous Ligands of Aryl Hydrocarbon Receptor: Current
  State of Art,” CURRENT DRUG METABOLISM, vol. 12, iss. 2, pp. 198-212, 2011.
  [Bibtex]

  @article ISI:000289085500010,
  Author = Stejskalova, Lucie and Dvorak, Zdenek and Pavek, Petr,
  Title = Endogenous and Exogenous Ligands of Aryl Hydrocarbon Receptor: Current
     State of Art,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2011,
  Volume = 12,
  Number = 2,
  Pages = 198-212,
  Month = FEB,
  Abstract = Aryl hydrocarbon receptor (AhR) is an important transcriptional
     regulator of drug metabolizing enzymes that dominantly controls the
     expression of cytochrome P450 CYP1 family genes and some phase II
     enzymes. AhR also has many endogenous functions including cell cycle
     control, immune response, and cell differentiation. In addition, AhR is
     well-known to be involved in chemically-induced carcinogenesis. AhR is
     activated by a variety of endogenous and exogenous ligands. While
     exogenous activation of AhR has deleterious effects on human organism,
     sustained activation of AhR by endogenous ligands is indispensable for
     proper cell functions. Therefore, the effects of exogenous and
     endogenous ligands on AhR resemble the Dr. Jekyll and Mr. Hyde story.
     The aim of the current paper is to summarize and update the knowledge on
     exogenous and endogenous AhR ligands.,
  ISSN = 1389-2002,
  Unique-ID = ISI:000289085500010,
  

• Z. Dvorak, “Hot Topic: Cross-Talk Between Endogenous Compounds and Regulatory
  Pathways of Drug Metabolism,” CURRENT DRUG METABOLISM, vol. 12, iss. 2, pp. 70, 2011.
  [Bibtex]

  @article ISI:000289085500001,
  Author = Dvorak, Zdenek,
  Title = Hot Topic: Cross-Talk Between Endogenous Compounds and Regulatory
     Pathways of Drug Metabolism,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2011,
  Volume = 12,
  Number = 2,
  Pages = 70,
  Month = FEB,
  ISSN = 1389-2002,
  Unique-ID = ISI:000289085500001,
  

• J. Brtko and Z. Dvorak, “Role of Retinoids, Rexinoids and Thyroid Hormone in the Expression of
  Cytochrome P450 Enzymes,” CURRENT DRUG METABOLISM, vol. 12, iss. 2, pp. 71-88, 2011.
  [Bibtex]

  @article ISI:000289085500002,
  Author = Brtko, Julius and Dvorak, Zdenek,
  Title = Role of Retinoids, Rexinoids and Thyroid Hormone in the Expression of
     Cytochrome P450 Enzymes,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2011,
  Volume = 12,
  Number = 2,
  Pages = 71-88,
  Month = FEB,
  Abstract = Retinoic acid receptors (RARs), retinoid X receptors (RXRs) and thyroid
     hormone receptors (TRs) are nuclear receptors that are crucial
     transcriptional regulators of many cellular processes such as
     differentiation, development, apoptosis, carbohydrate and lipid
     metabolism, homeostasis etc. In addition, RXRs are common
     heterodimerization partners for several receptors including vitamin D
     receptor, pregnane X receptor (PXR), constitutive androstane receptor
     (CAR) etc. In the course of 90s', PXR and CAR were discovered as key
     xenosensors regulating drug-metabolizing enzymes. Since there exist
     various cross-talks between cell signaling pathways, this was not
     surprising that RXRs, RARs and TRs were identified as regulators of
     human drug-metabolizing cytochromes P450 and cytochromes P450 involved
     in metabolism of endogenous compounds. Hence, a link between regulation
     of xenobiotic metabolizing enzymes and regulatory pathways of
     intermediary metabolism was established. Additionally, several
     drug-metabolizing enzymes are involved in metabolism of retinoids,
     rexinoids and thyroid hormones. In the current paper, we summarize the
     knowledge on the role of RARs, RXRs and TRs in the regulation of drug
     metabolizing cytochromes P450, and vice versa on the role of P450s in
     homeostasis of retinoids, rexinoids and thyroid hormone.,
  ISSN = 1389-2002,
  Unique-ID = ISI:000289085500002,
  

• Z. Dvorak and R. Vrzal, “Berberine reduces insulin resistance: the roles for glucocorticoid
  receptor and aryl hydrocarbon receptor,” FERTILITY AND STERILITY, vol. 95, iss. 2, pp. E7, 2011.
  [Bibtex]

  @article ISI:000286419000001,
  Author = Dvorak, Zdenek and Vrzal, Radim,
  Title = Berberine reduces insulin resistance: the roles for glucocorticoid
     receptor and aryl hydrocarbon receptor,
  Journal = FERTILITY AND STERILITY,
  Year = 2011,
  Volume = 95,
  Number = 2,
  Pages = E7,
  Month = FEB,
  DOI = 10.1016/j.fertnstert.2010.11.014,
  ISSN = 0015-0282,
  Unique-ID = ISI:000286419000001,
  

• R. Buchtik, Z. Travnicek, J. Vanco, R. Herchel, and Z. Dvorak, “Synthesis, characterization, DNA interaction and cleavage, and in vitro
  cytotoxicity of copper(II) mixed-ligand complexes with
  2-phenyl-3-hydroxy-4(1H)-quinolinone,” DALTON TRANSACTIONS, vol. 40, iss. 37, pp. 9404-9412, 2011.
  [Bibtex]

  @article ISI:000294666700010,
  Author = Buchtik, Roman and Travnicek, Zdenek and Vanco, Jan and Herchel, Radovan
     and Dvorak, Zdenek,
  Title = Synthesis, characterization, DNA interaction and cleavage, and in vitro
     cytotoxicity of copper(II) mixed-ligand complexes with
     2-phenyl-3-hydroxy-4(1H)-quinolinone,
  Journal = DALTON TRANSACTIONS,
  Year = 2011,
  Volume = 40,
  Number = 37,
  Pages = 9404-9412,
  Abstract = A series of mixed-ligand complexes [Cu(qui)(L)]NO(3)center dot xH(2)O
     (1-6), where Hqui = 2-phenyl-3-hydroxy-4(1H)-quinolinone, L =
     2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2),
     bis(2-pyridyl)amine (ambpy) (3), 5-methyl-1,10-phenanthroline (mphen)
     (4), 5-nitro-1,10-phenanthroline (nphen) (5) and bathophenanthroline
     (bphen) (6), have been synthesized and fully characterized. The X-ray
     structures of [Cu(qui)(phen)]NO(3)center dot H(2)O (2) and
     [Cu(qui)(ambpy)]NO(3) (3a) show a slightly distorted square-planar
     geometry in the vicinity of the central copper(II) atom. An in vitro
     cytotoxicity study of the complexes found significant activity against
     human osteosarcoma (HOS) and human breast adenocarcinoma (MCF7) cell
     lines, with the best results for complex 6, where IC(50) equals to 2.1
     +/- 0.2 mu M, and 2.2 +/- 0.4 mu M, respectively. The strong
     interactions of the complexes with calf thymus DNA (CT-DNA) and high
     ability to cleave pUC19 DNA plasmid were found. A correlation has been
     found between the in vitro cytotoxicity and DNA cleavage studies of the
     complexes.,
  DOI = 10.1039/c1dt10674k,
  ISSN = 1477-9226,
  Unique-ID = ISI:000294666700010,
  

2010

• A. Rulcova, I. Prokopova, L. Krausova, M. Bitman, R. Vrzal, Z. Dvorak, J. Blahos, and P. Pavek, “Stereoselective interactions of warfarin enantiomers with the pregnane X
  nuclear receptor in gene regulation of major drug-metabolizing
  cytochrome P450 enzymes,” JOURNAL OF THROMBOSIS AND HAEMOSTASIS, vol. 8, iss. 12, pp. 2708-2717, 2010.
  [Bibtex]

  @article ISI:000285110700016,
  Author = Rulcova, A. and Prokopova, I. and Krausova, L. and Bitman, M. and Vrzal,
     R. and Dvorak, Z. and Blahos, J. and Pavek, P.,
  Title = Stereoselective interactions of warfarin enantiomers with the pregnane X
     nuclear receptor in gene regulation of major drug-metabolizing
     cytochrome P450 enzymes,
  Journal = JOURNAL OF THROMBOSIS AND HAEMOSTASIS,
  Year = 2010,
  Volume = 8,
  Number = 12,
  Pages = 2708-2717,
  Month = DEC,
  Abstract = Background: Warfarin, an antagonist of vitamin K, is an oral coumarin
     anticoagulant widely used to control and prevent thromboembolic
     disorders. Warfarin is clinically available as a racemic mixture of R-
     and S-warfarin. The S-enantiomer has three to five times greater
     anticoagulation potency than its optical congener. Recently, vitamin
     K(2) function has been proposed via the pregnane X receptor (PXR) in
     osteocytes. PXR acts as a xenobiotic sensor that controls expression of
     many genes involved in drug/xenobiotic metabolic clearance. Objective:
     The aim was to examine whether enantiomers of warfarin stereoselectively
     interact with PXR to up-regulate main drug/ xenobiotic-metabolizing
     enzymes of the cytochrome P450 superfamily. Methods: Interactions of
     warfarin enantiomers with PXR were tested by gene reporter assays and
     time-resolved fluorescence resonance energy transfer technology
     (TR-FRET) ligand binding assay. Up-regulation of PXR-target gene mRNAs
     by warfarin enantiomers was studied using semi-quantitative reverse
     transcription-polymerase chain reaction(RT-PCR) in primary human
     hepatocytes. Results: We found that R-warfarin interacts with the PXR
     nuclear receptor. Consistently, R-warfarin significantly induced CYP3A4
     and CYP2C9 mRNAs in cultures of primary human hepatocytes or in LS174T
     intestinal cells. On the other hand, S-warfarin is a less potent inducer
     of PXR-target genes in human hepatocytes and activates PXR only at
     supraphysiological concentrations. In addition, we showed that racemic
     10- and 4'-hydroxywarfarins are also highly potent PXR ligands and
     inducers of CYP3A4 and CYP2C9 mRNA in human hepatocytes. Conclusion: We
     showed that R-warfarin can significantly up-regulate major
     drug-metabolizing enzymes CYP3A4 and CYP2C9 in the liver and thus may
     cause drug-drug interactions (DDI) with co-administered drugs. The
     results warrant reconsideration of racemic warfarin usage in clinics.,
  DOI = 10.1111/j.1538-7836.2010.04036.x,
  ISSN = 1538-7933,
  Unique-ID = ISI:000285110700016,
  

• Z. Dvorak and P. Pavek, “Regulation of drug-metabolizing cytochrome P450 enzymes by
  glucocorticoids,” DRUG METABOLISM REVIEWS, vol. 42, iss. 4, pp. 621-635, 2010.
  [Bibtex]

  @article ISI:000284506600004,
  Author = Dvorak, Zdenek and Pavek, Peotr,
  Title = Regulation of drug-metabolizing cytochrome P450 enzymes by
     glucocorticoids,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2010,
  Volume = 42,
  Number = 4,
  Pages = 621-635,
  Month = NOV,
  Abstract = The regulation of drug-metabolizing cytochrome P450 enzymes (CYP) is a
     complex process involving multiple mechanisms. Among them,
     transcriptional regulation through ligand-activated nuclear receptors is
     the crucial mechanism involved in hormone-controlled and
     xenobiotic-induced expression of drug-metabolizing CYPs. In this
     article, we focus, in detail, on the role of the glucocorticoid receptor
     (GR) in the transcriptional regulation of human drug-metabolizing CYP
     enzymes and the mechanisms of the regulation. There are at least three
     distinct transcriptional mechanisms by which GR controls the expression
     of CYPs: 1) direct binding of GR to a specific gene-promoter sequence
     called the glucocorticoid responsive element (GRE); 2) indirect binding
     of GR in the form of a multiprotein complex to gene promoters without a
     direct contact between GR and promoter DNA; and 3) up- or downregulation
     of other CYP transcriptional regulators or nuclear receptors (i.e.,
     transcriptional regulatory cross-talk). However, due to the general
     effect of glucocorticoids on numerous cellular pathways and functions,
     the net transcriptional effect of glucocorticoids on drug-metabolizing
     enzymes is usually a combination of several mechanisms. Since synthetic
     glucocorticoids are widely prescribed in human pharmacotherapy for the
     treatment of many diseases, comprehensive understanding of the
     transcriptional regulation of drug-metabolizing CYPs via GR with respect
     to glucocorticoid therapy or glucocorticoid hormonal status will aid in
     the development of efficient individualized pharmacotherapy without
     drug-drug interactions.,
  DOI = 10.3109/03602532.2010.484462,
  ISSN = 0360-2532,
  Unique-ID = ISI:000284506600004,
  

• P. Bachleda, R. Vrzal, and Z. Dvorak, “Resveratrol Enhances NK Cell Cytotoxicity: Possible Role for Aryl
  Hydrocarbon Receptor,” JOURNAL OF CELLULAR PHYSIOLOGY, vol. 225, iss. 2, pp. 289-290, 2010.
  [Bibtex]

  @article ISI:000283003400001,
  Author = Bachleda, Petr and Vrzal, Radim and Dvorak, Zdenek,
  Title = Resveratrol Enhances NK Cell Cytotoxicity: Possible Role for Aryl
     Hydrocarbon Receptor,
  Journal = JOURNAL OF CELLULAR PHYSIOLOGY,
  Year = 2010,
  Volume = 225,
  Number = 2,
  Pages = 289-290,
  Month = NOV,
  DOI = 10.1002/jcp.22233,
  ISSN = 0021-9541,
  Unique-ID = ISI:000283003400001,
  

• A. Novotna, A. Doricakova, R. Vrzal, P. Maurel, P. Pavek, and Z. Dvorak, “Investigation of Orlistat effects on PXR activation and CYP3A4
  expression in primary human hepatocytes and human intestinal LS174T
  cells,” EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES, vol. 41, iss. 2, pp. 276-280, 2010.
  [Bibtex]

  @article ISI:000281995200010,
  Author = Novotna, Aneta and Doricakova, Aneta and Vrzal, Radim and Maurel,
     Patrick and Pavek, Petr and Dvorak, Zdenek,
  Title = Investigation of Orlistat effects on PXR activation and CYP3A4
     expression in primary human hepatocytes and human intestinal LS174T
     cells,
  Journal = EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES,
  Year = 2010,
  Volume = 41,
  Number = 2,
  Pages = 276-280,
  Month = OCT 9,
  Abstract = Drugs for weight loss have been in use for nearly hundred years.
     Orlistat (Xenical) is a non-centrally acting anti-obesity drug that
     inactivates gastric and intestinal lipases, thus, preventing absorption
     of dietary triglycerides. There are reports indicating that Orlistat
     reduces bioavailability of Cyclosporin to a clinically relevant degree.
     Since Cyclosporin is metabolized by cytochrome P450 CYP3A4, we examined
     whether interaction between Orlistat and Cyclosporin involves induction
     of CYP3A4. Human Caucasian colon adenocarcinoma cells LS174T and primary
     cultures of human hepatocytes were used, as in vitro models of
     intestinal and hepatic cells, respectively. Treatment of LS174T cells
     for 24 h with Orlistat (1-100 mg/L) did not cause induction of CYP3A4
     mRNA levels as compared to control cells while Orlistat (100 mg/L)
     slightly induced CYP3A4 mRNA in human hepatocytes. Rifampicin, a model
     CYP3A4 inducer, significantly induced CYP3A4 mRNA in both types of
     cells. The level of CYP3A4 protein in human hepatocytes was increased by
     Orlistat after 48 h, while rifampicin strongly induced CYP3A4 protein
     level. In addition, Orlistat moderately dose-independently activated
     pregnane X receptor (PXR) in LS174T cells transiently transfected with
     p3A4-luc reporter construct containing the basal promoter (-362/+53)
     with proximal PXR response element and the distal xenobiotic responsive
     enhancer module (-7836/-7208) of the CYP3A4 gene 5'-flanking region. In
     conclusion, we report here that Orlistat is weak PXR activator and
     CYP3A4 inducer in human hepatocytes, but it has no effect on CYP3A4 in
     intestinal cells, implying no role of CYP3A4 induction in the
     interaction between Orlistat and Cyclosporin in absorption process. (C)
     2010 Elsevier B.V. All rights reserved.,
  DOI = 10.1016/j.ejps.2010.06.019,
  ISSN = 0928-0987,
  Unique-ID = ISI:000281995200010,
  

• Z. Travnicek, P. Starha, I. Popa, R. Vrzal, and Z. Dvorak, “Roscovitine-based CDK inhibitors acting as N-donor ligands in the
  platinum(II) oxalato complexes: Preparation, characterization and in
  vitro cytotoxicity,” EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY, vol. 45, iss. 10, pp. 4609-4614, 2010.
  [Bibtex]

  @article ISI:000282112700024,
  Author = Travnicek, Zdenek and Starha, Pavel and Popa, Igor and Vrzal, Radim and
     Dvorak, Zdenek,
  Title = Roscovitine-based CDK inhibitors acting as N-donor ligands in the
     platinum(II) oxalato complexes: Preparation, characterization and in
     vitro cytotoxicity,
  Journal = EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY,
  Year = 2010,
  Volume = 45,
  Number = 10,
  Pages = 4609-4614,
  Month = OCT,
  Abstract = The reactions of potassium bis(oxalato)platinate dihydrate with two
     molar equivalents of the potent adenine-based cyclin-dependent kinase
     inhibitor 2-(1-ethyl-2-hydroxyethylamino)-N6-(benzyl)-9-isopropyladenine
     (Roscovitine: Ros) and its benzyl-substituted analogues, i.e
     2-(1-ethy1-2-hydroxyethylamino)-N6-(2-methoxybenzyl)-9-isopropyladenine
     (2OMeRos),
     2-(1-ethy1-2-hydroxyethylamino)-N6-(3-methoxybenzyl)-9-isopropyladenine
     (3OMeRos) and
     2-(1-ethy1-2-hydroxyethylamino)-N6-(4-methoxybenzyl)-9-isopropyladenine
     (4OMeRos), were performed and the [Pt(oxXRos)(2)] 3/4 H(2)O (1),
     [Pt(ox)(2OMeRos)(2)] H(2)O (2), (Pt(ox)(3OMeR-os)(2)] 1/2H(2)O (3) and
     [Pt(ox)(4OMeRos)(2)] 3/4 H(2)O (4) platinum(II) oxalato complexes were
     obtained. The methods of the elemental analysis, IR. Raman and NMR
     spectroscopy, ESI + mass spectrometry, molar conductivity measurement
     and TG/DTA thermal analysis were performed to characterize the obtained
     products. The complexes 1-4 Involve tetracoordinated central Pt(11) atom
     with one bidentate-coordinated oxalate dianion (ox) and two monodentate
     adenine-based molecules (nRos), thus giving the square-planar geometry
     around the metal centre with a PtN(2)O(2) donor set. In vitro cytotoxic
     activity of the complexes against ovarian carcinoma (A2780), cisplatin
     resistant ovarian carcinoma (A2780cis). malignant melanoma (G-361), lung
     carcinoma (A549). cervix epitheloid carcinoma (HeLa). breast
     adenocarcinoma (MCF7) and osteosarcoma (HOS) human cancer cell lines was
     evaluated. All the tested complexes exceeded the in vitro cytotoxicity
     of cisplatin and oxaliplatin against HeLa. A2780cis and, except for 2,
     also against HOS cancer cells The complex 1 was also tested for its
     cytotoxicity in primary cultures of human hepatocytes and it was not
     found to be hepatotoxic up to the concentration of 50.0 mu M. (C) 2010
     Elsevier Masson SAS. All rights reserved.,
  DOI = 10.1016/j.ejmech.2010.07.025,
  ISSN = 0223-5234,
  Unique-ID = ISI:000282112700024,
  

• R. Vrzal, P. Starha, Z. Dvorak, and Z. Travnicek, “Evaluation of in vitro cytotoxicity and hepatotoxicity of platinum(II)
  and palladium(II) oxalato complexes with adenine derivatives as carrier
  ligands,” JOURNAL OF INORGANIC BIOCHEMISTRY, vol. 104, iss. 10, pp. 1130-1132, 2010.
  [Bibtex]

  @article ISI:000281525200017,
  Author = Vrzal, Radim and Starha, Pavel and Dvorak, Zdenek and Travnicek, Zdenek,
  Title = Evaluation of in vitro cytotoxicity and hepatotoxicity of platinum(II)
     and palladium(II) oxalato complexes with adenine derivatives as carrier
     ligands,
  Journal = JOURNAL OF INORGANIC BIOCHEMISTRY,
  Year = 2010,
  Volume = 104,
  Number = 10,
  Pages = 1130-1132,
  Month = OCT,
  Abstract = In vitro antitumour activity of the [Pt(ox)(L(n))(2)] (1-7) and
     [Pd(ox)(L(n))(2)] (8-14) oxalato (ox) complexes involving
     N6-benzyl-9-isopropyladenine-based N-donor carrier ligands (L(n))
     against ovarian carcinoma (A2780), cisplatin resistant ovarian carcinoma
     (A2780cis), malignant melanoma (G-361), lung carcinoma (A549), cervix
     epitheloid carcinoma (HeLa), breast adenocarcinoma (MCF7) and
     osteosarcoma (HOS) human cancer cell lines was studied. Some of the
     tested complexes were even several times more cytotoxic as compared with
     cisplatin employed as a positive control. The improved cytotoxic effect
     was demonstrated for the platinum(II) complexes 3 (IC(50) = 3.2 +/- 1.0
     mu M and 3.2 +/- 0.6 mu M) and 5 (IC(50) = 4.0 +/- 1.0 mu M and 4.1 +/-
     1.4 mu M) against A2780 and A2780cis, as compared with 11.5 +/- 1.6 mu
     M, and 30.3 +/- 6.1 mu M determined for cisplatin, respectively. The
     significant in vitro cytotoxicity against MCF7 (IC(50) = 8.2 +/- 3.8 mu
     M for 12) and A2780 (IC(50) = 5.4 +/- 1.2 mu M for 14) was evaluated for
     the palladium(II) oxalato complexes, which again exceeded cisplatin,
     whose IC(50) equalled 19.6 +/- 4.3 mu M against the MCF7 cells. Selected
     complexes were also screened for their in vitro cytotoxic effect in
     primary cultures of human hepatocytes and they were found to be
     non-hepatotoxic. (c) 2010 Elsevier Inc. All rights reserved.,
  DOI = 10.1016/j.jinorgbio.2010.07.002,
  ISSN = 0162-0134,
  Unique-ID = ISI:000281525200017,
  

• Z. Dvorak, “Berberine: A multipotent remedy with unknown cellular target?,” POULTRY SCIENCE, vol. 89, iss. 9, pp. 1787, 2010.
  [Bibtex]

  @article ISI:000280895400001,
  Author = Dvorak, Z.,
  Title = Berberine: A multipotent remedy with unknown cellular target?,
  Journal = POULTRY SCIENCE,
  Year = 2010,
  Volume = 89,
  Number = 9,
  Pages = 1787,
  Month = SEP 1,
  DOI = 10.3382/ps.2010-00701,
  ISSN = 0032-5791,
  Unique-ID = ISI:000280895400001,
  

• L. Stejskalova, L. Vecerova, L. M. Perez, L. Hahnova, P. Nachtigal, R. Vrzal, Z. Dvorak, and P. Pavek, “Activity of Aryl hydrocarbon receptor (AhR) in the placental trophoblast
  and expression of AhR and its translocator ARNT expression in rat and
  human placentas during pregnancy,” DRUG METABOLISM REVIEWS, vol. 42, iss. 1, pp. 155, 2010.
  [Bibtex]

  @article ISI:000281147700274,
  Author = Stejskalova, Lucie and Vecerova, Lenka and Perez, Laura Messa and
     Hahnova, Lenka and Nachtigal, Petr and Vrzal, Radim and Dvorak, Zdenek
     and Pavek, Petr,
  Title = Activity of Aryl hydrocarbon receptor (AhR) in the placental trophoblast
     and expression of AhR and its translocator ARNT expression in rat and
     human placentas during pregnancy,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2010,
  Volume = 42,
  Number = 1,
  Pages = 155,
  Month = AUG,
  Note = 9th International Meeting of the
     International-Society-for-the-Study-of-Xenobiotics(ISSX), Istanbul,
     TURKEY, SEP 04-08, 2010,
  Organization = Int Soc Study Xenobiot,
  ISSN = 0360-2532,
  Unique-ID = ISI:000281147700274,
  

• M. Bitman, R. Vrzal, Z. Dvorak, L. Stejskalova, and P. Pavek, “The Influence of Extracellular Signal-Regulated Protein Kinase (ERK) on
  Pregnane X Receptor-Mediated Expression of CYP3A4 and MDR1 Genes in
  Hepatocellular Carcinoma Cell Lines and in Primary Human Hepatocytes,” DRUG METABOLISM REVIEWS, vol. 42, iss. 1, pp. 159, 2010.
  [Bibtex]

  @article ISI:000281147700281,
  Author = Bitman, Michal and Vrzal, Radim and Dvorak, Zdenek and Stejskalova,
     Lucie and Pavek, Petr,
  Title = The Influence of Extracellular Signal-Regulated Protein Kinase (ERK) on
     Pregnane X Receptor-Mediated Expression of CYP3A4 and MDR1 Genes in
     Hepatocellular Carcinoma Cell Lines and in Primary Human Hepatocytes,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2010,
  Volume = 42,
  Number = 1,
  Pages = 159,
  Month = AUG,
  Note = 9th International Meeting of the
     International-Society-for-the-Study-of-Xenobiotics(ISSX), Istanbul,
     TURKEY, SEP 04-08, 2010,
  Organization = Int Soc Study Xenobiot,
  ISSN = 0360-2532,
  Unique-ID = ISI:000281147700281,
  

• M. Stiborova, V. Martinek, M. Svobodova, J. Sistkova, Z. Dvorak, J. Ulrichova, V. Simanek, E. Frei, H. H. Schmeiser, D. H. Phillips, and V. M. Arlt, “Mechanisms of the Different DNA Adduct Forming Potentials of the Urban
  Air Pollutants 2-Nitrobenzanthrone and Carcinogenic 3-Nitrobenzanthrone,” CHEMICAL RESEARCH IN TOXICOLOGY, vol. 23, iss. 7, pp. 1192-1201, 2010.
  [Bibtex]

  @article ISI:000279928000007,
  Author = Stiborova, Marie and Martinek, Vaclav and Svobodova, Martina and
     Sistkova, Jana and Dvorak, Zdenek and Ulrichova, Jitka and Simanek,
     Vilim and Frei, Eva and Schmeiser, Heinz H. and Phillips, David H. and
     Arlt, Volker M.,
  Title = Mechanisms of the Different DNA Adduct Forming Potentials of the Urban
     Air Pollutants 2-Nitrobenzanthrone and Carcinogenic 3-Nitrobenzanthrone,
  Journal = CHEMICAL RESEARCH IN TOXICOLOGY,
  Year = 2010,
  Volume = 23,
  Number = 7,
  Pages = 1192-1201,
  Month = JUL,
  Abstract = 2-Nitrobenzanthrone (2-NBA) has recently been detected in ambient air
     particulate matter. Its isomer 3-nitrobenzanthrone (3-NBA) is a potent
     mutagen and suspected human carcinogen identified in diesel exhaust. We
     compared the efficiencies of human enzymatic systems [hepatic
     microsomes and cytosols, NAD(P)H:quinone oxidoreductase I (NQO1),
     xanthine oxidase, NADPH:cytochrome 0450 reductase,
     N,O-acetyltransferases, and sulfotransferases-1 and human primary
     hepatocytes to activate 2-NBA and its isomer 3-NBA to species forming
     DNA adducts. In contrast to 3-NBA, 2-NBA was not metabolized at
     detectable levels by the tested human enzymatic systems and enzymes
     expressed in human hepatocytes, and no DNA adducts detectable by
     (32)P-postlabeling were generated by 2-NBA. Even NQO1, the most
     efficient human enzyme to bioactive 3-NBA, did not activate 2-NBA.
     Molecular docking of 2-NBA and 3-NBA to the active site of NQO1 showed
     similar binding affinities; however, the binding orientation of 2-NBA
     does not favor the reduction of the nitro group. This was in line with
     the inhibition of 3-NBA DNA adduct formation by 2-NBA, indicating that
     2-NBA can compete with 3-NBA for binding to NQO1, thereby decreasing the
     metabolic activation of 3-NBA. In addition, the predicted equilibrium
     conditions favor a 3 orders of magnitude higher dissociation of
     N-OH-3-ABA in comparison to N-OH-2-ABA. These findings explain the very
     different genotoxicity, mutagenicity, and DNA adduct forming potential
     of the two compounds. Collectively, our results suggest that 2-NBA
     possesses a relatively lower risk to humans than 3-NBA.,
  DOI = 10.1021/tx100052d,
  ISSN = 0893-228X,
  Unique-ID = ISI:000279928000007,
  

• R. Vrzal, A. Novotna, A. Doricakova, M. Bitmann, P. Pavek, and Z. Dvorak, "Valproic acid potentiates vitamin D receptor-mediated induction of CYP24
  gene - A consequence for drug-induced osteomalacia," FEBS JOURNAL, vol. 277, iss. 1, pp. 153, 2010.
  [Bibtex]

  @article ISI:000278565100539,
  Author = Vrzal, R. and Novotna, A. and Doricakova, A. and Bitmann, M. and Pavek,
     P. and Dvorak, Z.,
  Title = Valproic acid potentiates vitamin D receptor-mediated induction of CYP24
     gene - A consequence for drug-induced osteomalacia,
  Journal = FEBS JOURNAL,
  Year = 2010,
  Volume = 277,
  Number = 1,
  Pages = 153,
  Month = JUN,
  Note = 35th Congress of the Federation-of-European-Biochemical-Societies,
     Gothenburg, SWEDEN, JUN 26-JUL 01, 2010,
  ISSN = 1742-464X,
  Unique-ID = ISI:000278565100539,
  

• R. Vrzal, P. Pavek, and Z. Dvorak, "Investigation of benzodiazepines and zolpidem effects on the expression
  of cychromes P450 CYP1A1, CYP1A2 and CYP3A4 in primary cultures of human
  hepatocytes," FEBS JOURNAL, vol. 277, iss. 1, pp. 153, 2010.
  [Bibtex]

  @article ISI:000278565100538,
  Author = Vrzal, R. and Pavek, P. and Dvorak, Z.,
  Title = Investigation of benzodiazepines and zolpidem effects on the expression
     of cychromes P450 CYP1A1, CYP1A2 and CYP3A4 in primary cultures of human
     hepatocytes,
  Journal = FEBS JOURNAL,
  Year = 2010,
  Volume = 277,
  Number = 1,
  Pages = 153,
  Month = JUN,
  Note = 35th Congress of the Federation-of-European-Biochemical-Societies,
     Gothenburg, SWEDEN, JUN 26-JUL 01, 2010,
  ISSN = 1742-464X,
  Unique-ID = ISI:000278565100538,
  

• R. Vrzal, S. Gerbal-Chaloin, P. Maurel, and Z. Dvorak, "Comparative Effects of Microtubules Disruption on Glucocorticoid
  Receptor Functions in Proliferating and Quiescent Cells," INTERNATIONAL JOURNAL OF TOXICOLOGY, vol. 29, iss. 3, pp. 326-335, 2010.
  [Bibtex]

  @article ISI:000278124800011,
  Author = Vrzal, Radim and Gerbal-Chaloin, Sabine and Maurel, Patrick and Dvorak,
     Zdenek,
  Title = Comparative Effects of Microtubules Disruption on Glucocorticoid
     Receptor Functions in Proliferating and Quiescent Cells,
  Journal = INTERNATIONAL JOURNAL OF TOXICOLOGY,
  Year = 2010,
  Volume = 29,
  Number = 3,
  Pages = 326-335,
  Month = MAY,
  Abstract = We have recently demonstrated that the alkaloid colchicine (COL)
     inhibits glucocorticoid receptor (GR) transcriptional activity. In
     addition, we described proteasome-mediated degradation of GR in
     COL-treated HeLa cells. While these effects were previously attributed
     to cell cycle arrest in G2/M phase, this explanation is not applicable
     for nonproliferating cells such as human hepatocytes (HH). In the
     current study, we compared COL-mediated microtubule disruption and cell
     cycle arrest with selected GR functions in HeLa cells and HH as models
     of proliferating and quiescent cells, respectively. Microtubule
     disruption led to irreversible decrease in GR binding capacity and
     protein level in HeLa cells. None of the parameters was restored 24
     hours after COL withdrawal. In contrast, dexamethasone (DEX) binding was
     increased in HH at the beginning of the treatment, with following
     transient activation of extracellular signal-regulated kinase (ERK). The
     findings of these investigations emphasize the GR-signaling differences
     between primary and transformed cells.,
  DOI = 10.1177/1091581810366486,
  ISSN = 1091-5818,
  Unique-ID = ISI:000278124800011,
  

• R. Vrzal, K. Kubesova, P. Pavek, and Z. Dvorak, "Benzodiazepines medazepam and midazolam are activators of pregnane X
  receptor and weak inducers of CYP3A4: Investigation in primary cultures
  of human hepatocytes and hepatocarcinoma cell lines," TOXICOLOGY LETTERS, vol. 193, iss. 2, pp. 183-188, 2010.
  [Bibtex]

  @article ISI:000276175200009,
  Author = Vrzal, Radim and Kubesova, Katerina and Pavek, Petr and Dvorak, Zdenek,
  Title = Benzodiazepines medazepam and midazolam are activators of pregnane X
     receptor and weak inducers of CYP3A4: Investigation in primary cultures
     of human hepatocytes and hepatocarcinoma cell lines,
  Journal = TOXICOLOGY LETTERS,
  Year = 2010,
  Volume = 193,
  Number = 2,
  Pages = 183-188,
  Month = MAR 15,
  Abstract = Benzodiazepines have wide-spread used in pharmacotherapy for their
     anxiolytic, myorelaxant, hypnotic, amnesic and anticonvulsive
     properties. Despite benzodiazepines are used in clinics over 50 years,
     they have not been surprisingly tested for capability to induce major
     drug-metabolizing cytochromes P450. In the current study, we have
     examined the potency of Alprazolam, Bromazepam, Chlordiazepoxide,
     Clonazepam, Diazepam, Lorazepam, Medazepam, Midazolam, Nitrazepam,
     Oxazepam, Tetrazepam and Triazolam to induce CYP1A2 and CYP3A4 in
     primary cultures of human hepatocytes. Benzodiazepines were tested in
     therapeutic concentrations and in concentrations corresponding to their
     plasma levels in intoxicated patients. We found weak but significant
     induction of CYP3A4 mRNA by Midazolam and Medazepam, while other
     benzodiazepines did not induce CYP3A4 expression. None of the tested
     compounds induced CYP1A2 mRNA in three independent human hepatocytes
     cultures. In addition, employing gene reporter assays with transiently
     transfected hepatocarcinoma cells, we found that tested benzodiazepines
     did not activate aryl hydrocarbon receptor (AhR), whereas Midazolam and
     Medazepam slightly activated pregnane X receptor (PXR). Consistently,
     two-hybrid mammalian assay using hybrid fusion plasmids GAL4-PXR
     ligand-binding domain (LBD) and VP16-SRC-1-receptor-interacting domain
     (RID) confirmed PXR activation by Midazolam and Medazepam. In
     conclusion, Alprazolam, Bromazepam, Chlordiazepoxide, Clonazepam,
     Diazepam, Lorazepam, Nitrazepam, Oxazepam, Tetrazepam and Triazolam can
     be considered as safe drugs in term of their inability to induce PXR-
     and AhR-dependent cytochrome P450 enzymes CYP1A2 and CYP3A4. Medazepam
     and Midazolam slightly activated pregnane X receptor and displayed weak
     potency to induce CYP3A4 mRNA in human hepatocytes. (C) 2010 Elsevier
     Ireland Ltd. All rights reserved.,
  DOI = 10.1016/j.toxlet.2010.01.004,
  ISSN = 0378-4274,
  Unique-ID = ISI:000276175200009,
  

• Z. Dvorak, R. Vrzal, P. Starha, A. Klanicova, and Z. Travnicek, "Effects of dinuclear copper(II) complexes with 6-(benzylamino)purine
  derivatives on AhR and PXR dependent expression of cytochromes P450
  CYP1A2 and CYP3A4 genes in primary cultures of human hepatocytes," TOXICOLOGY IN VITRO, vol. 24, iss. 2, pp. 425-429, 2010.
  [Bibtex]

  @article ISI:000275991700011,
  Author = Dvorak, Zdenek and Vrzal, Radim and Starha, Pavel and Klanicova, Alena
     and Travnicek, Zdenek,
  Title = Effects of dinuclear copper(II) complexes with 6-(benzylamino)purine
     derivatives on AhR and PXR dependent expression of cytochromes P450
     CYP1A2 and CYP3A4 genes in primary cultures of human hepatocytes,
  Journal = TOXICOLOGY IN VITRO,
  Year = 2010,
  Volume = 24,
  Number = 2,
  Pages = 425-429,
  Month = MAR,
  Abstract = A series of dinuclear copper(II) complexes of the compositions
     [Cu(2)(mu-L(n))(2)(mu-Cl)(2)Cl(2)] (1, 2),
     [Cu(2)(mu-L(n))(4)Cl(2)]Cl(2)center dot 2H(2)O (3, 4) and
     [Cu(2)(mu-L(n))(4)(ClO(4))(2)](ClO(4))(2)center dot xSolv (5, 6; xSolv
     = 4MeOH for 5 and 2EtOH for 6), involving 6-(benzylamino)purine
     derivatives (L(n)), have been evaluated with the aim to determine their
     possible drug interactions and their capability to induce the expression
     of major drug-metabolizing cytochromes P450. The above-mentioned
     complexes have been chosen based on the fact that substantial both in
     vitro (cytotoxicity, SOD-mimic) and in vivo (antidiabetic) biological
     activity has been found for them. As models, primary cultures of human
     hepatocytes and human hepatoma cells HepG2 transiently transfected with
     a plasmid containing dioxin-responsive element fused to the luciferase
     reporter gene (DRE-LUC) have been chosen. It has been found that the
     tested complexes 1-6 did not significantly induce the expression of
     CYP1A2 and CYP3A4 mRNAs in the concentration range of 0.1-10.0 mu M, in
     three different primary human hepatocyte cultures after 24 h of the
     treatment. On the other hand, the model inducers, i.e. 2,3,7,8-
     tetrachlorodibenzo-p-dioxin (TCDD) and rifampicin, significantly
     increased the levels of CYP1A2 and CYP3A4 mRNAs in all cultures. In
     addition, compounds 1-6 did not transactivate DRE-LUC in transiently
     transfected HepG2, while TCDD strongly induced luciferase activity after
     24 h of incubation. Based on the obtained results, it may be concluded
     that the studied dinuclear copper(II) complexes 1-6 possess very low
     toxicological potential to cause drug interactions in terms of
     transcriptional activation of the major human cytochromes P450. (C) 2009
     Elsevier Ltd. All rights reserved.,
  DOI = 10.1016/j.tiv.2009.10.012,
  ISSN = 0887-2333,
  Unique-ID = ISI:000275991700011,
  

• P. Pavek, K. Pospechova, L. Svecova, Z. Syrova, L. Stejskalova, J. Blazkova, Z. Dvorak, and J. Blahos, "Intestinal cell-specific vitamin D receptor (VDR)-mediated
  transcriptional regulation of CYP3A4 gene," BIOCHEMICAL PHARMACOLOGY, vol. 79, iss. 2, pp. 277-287, 2010.
  [Bibtex]

  @article ISI:000273506900022,
  Author = Pavek, Petr and Pospechova, Katerina and Svecova, Lucie and Syrova,
     Zdenka and Stejskalova, Lucie and Blazkova, Jana and Dvorak, Zdenek and
     Blahos, Jaroslav,
  Title = Intestinal cell-specific vitamin D receptor (VDR)-mediated
     transcriptional regulation of CYP3A4 gene,
  Journal = BIOCHEMICAL PHARMACOLOGY,
  Year = 2010,
  Volume = 79,
  Number = 2,
  Pages = 277-287,
  Month = JAN 15,
  Abstract = CYP3A4 is the most important drug-metabolizing enzyme that is involved
     in biotransformation of more than 50\% of drugs. Pregnane X receptor
     (PXR) dominantly controls CYP3A4 inducibility in the liver, whereas
     vitamin D receptor (VDR) transactivates CYP3A4 in the intestine by
     secondary bile acids. Four major functional PXR-binding response
     elements of CYP3A4 have been discovered and their cooperation was found
     to be crucial for maximal up-regulation of the gene in hepatocytes. VDR
     and PXR recognize similar response element motifs and share DR3(XREM)
     and proximal ER6 (prER6) response elements of the CYP3A4 gene.
     In this work, we tested whether the recently discovered PXR response
     elements DR4(eNR3A4) in the XREM module and the distal ER6 element in
     the CLEM4 module (CLEM4-ER6) bind VDR/RXR alpha heterodimer, whether the
     elements are involved in the intestinal transactivation, and whether
     their cooperation with other elements is essential for maximal
     intestinal expression of CYP3A4.
     Employing a series of gene reporter plasmids with various combinations
     of response element mutations transiently transfected into four
     intestinal cell lines, electrophoretic mobility shift assay (EMSA) and
     chromatin immunoprecipitation assay (ChIP), we found that the CLEM4-ER6
     motif interacts with VDR/RXR alpha heterodimer and partially cooperates
     with DR3(XREM) and prER6 in both basal and VDR-mediated inducible CYP3A4
     regulation in intestinal cells. In contrast, eNR3A4 is involved only in
     the basal transactivation in intestinal cells and in the PXR-mediated
     rifampicin-induced transactivation of CYP3A4 in LS174T intestinal cells.
     We thus describe a specific ligand-induced VDR-mediated transactivation
     of the CYP3A4 gene in intestinal cells that differs from PXR-mediated
     CYP3A4 regulation in hepatocytes. (C) 2009 Elsevier Inc. All rights
     reserved.,
  DOI = 10.1016/j.bcp.2009.08.017,
  ISSN = 0006-2952,
  Unique-ID = ISI:000273506900022,
  

2009

• P. Bachleda, R. Vrzal, J. Pivnicka, B. Cvek, and Z. Dvorak, "Examination of Zolpidem effects on AhR- and PXR-dependent expression of
  drug-metabolizing cytochromes P450 in primary cultures of human
  hepatocytes," TOXICOLOGY LETTERS, vol. 191, iss. 1, pp. 74-78, 2009.
  [Bibtex]

  @article ISI:000272276700011,
  Author = Bachleda, Petr and Vrzal, Radim and Pivnicka, Jakub and Cvek, Boris and
     Dvorak, Zdenek,
  Title = Examination of Zolpidem effects on AhR- and PXR-dependent expression of
     drug-metabolizing cytochromes P450 in primary cultures of human
     hepatocytes,
  Journal = TOXICOLOGY LETTERS,
  Year = 2009,
  Volume = 191,
  Number = 1,
  Pages = 74-78,
  Month = DEC 1,
  Abstract = A hypnotic drug Zolpidem is used in clinical practice for more than 25
     years. Surprisingly, the effects of Zolpidem on the expression of
     drug-metabolizing cytochromes P450 (CYPs) were not examined yet.
     Recently, the unexpected capacity of several ``old drugs'', such as
     valproic acid orazoles, to induce CYPs was reported. Therefore, we
     tested whether Zolpidem induces the expression of important CYPs in
     primary cultures of human hepatocytes. Cells were treated for 24 h with
     Zolpidem in therapeutic (0.1 mg/L) and toxic(l mg/L) concentrations. The
     levels of CYP1A1, CYP1A2,CY2C9 and CYP3A4 mRNAs were not altered by
     Zolpidem, whereas model inducers dioxin and rifampicin significantly
     induced CYP1A and CYP2/3 gene expression, respectively. Consistently,
     Zolpidem did not activate aryl hydrocarbon receptor (AhR) and pregnane X
     receptor (PXR), the key regulators of cytochromes P450s, as revealed by
     transient transfection gene reporter assays using HepG2 cells. We
     conclude Zolpidem be considered a safe drug with respect to the possible
     interactions through AhR- and PXR-dependent induction of
     drug-metabolizing CYPs. (C) 2009 Elsevier Ireland Ltd. All rights
     reserved.,
  DOI = 10.1016/j.toxlet.2009.08.009,
  ISSN = 0378-4274,
  Unique-ID = ISI:000272276700011,
  

• A. Belic, M. Temesvari, K. Kohalmy, R. Vrzal, Z. Dvorak, D. Rozman, and K. Monostory, "Investigation of the CYP2C9 Induction Profile in Human Hepatocytes by
  Combining Experimental and Modelling Approaches," CURRENT DRUG METABOLISM, vol. 10, iss. 10, pp. 1066-1074, 2009.
  [Bibtex]

  @article ISI:000275149900001,
  Author = Belic, Ales and Temesvari, Manna and Kohalmy, Krisztina and Vrzal, Radim
     and Dvorak, Zdenek and Rozman, Damjana and Monostory, Katalin,
  Title = Investigation of the CYP2C9 Induction Profile in Human Hepatocytes by
     Combining Experimental and Modelling Approaches,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2009,
  Volume = 10,
  Number = 10,
  Pages = 1066-1074,
  Month = DEC,
  Abstract = The goal of the present review is to characterise the induction profile
     of CYP2C9, a member of the cytochrome P450 superfamily. Since the
     mechanism of CYP2C9 induction is fairly complex, with parallel processes
     triggered by various inducers, an evaluation of the experimental results
     is often a great challenge. At least three nuclear receptors, the
     glucocrticoid receptor (GR), the pregnane X receptor (PXR) and the
     constitutive androstane receptor (CAR), are known to mediate the CYP2C9
     gene induction in man. However, mathematical modelling and simulation
     can provide an appropriate tool for the interpretation of CYP2C9
     regulatory mechanisms. As an example, we present modelling and
     simulation approaches of the CYP2C9 gene expression in human hepatocytes
     treated with well-known CYP2C9 inducers: the steroid hormone precursor
     dehydroepiandrosterone (DHEA) and the synthetic glucocorticoid
     dexamethasone (DXM). The results of the analysis suggest that in
     addition to the potent function of GR and the further involvement of PXR
     and CAR activated by DXM or DHEA, an additional factor might play a role
     in CYP2C9 regulation by DHEA. The novel potential candidate for DHEA
     action in CYP2C9 induction is likely to be the estrogen receptor.
     Additionally, the balance of DHEA sulphation-desulphation processes
     should also be considered in any description of DHEA-induced CYP2C9
     profiles.,
  ISSN = 1389-2002,
  Unique-ID = ISI:000275149900001,
  

• K. Monostory, J. Pascussi, L. Kobori, and Z. Dvorak, "Hormonal regulation of CYP1A expression," DRUG METABOLISM REVIEWS, vol. 41, iss. 4, pp. 547-572, 2009.
  [Bibtex]

  @article ISI:000280164500001,
  Author = Monostory, Katalin and Pascussi, Jean-Marc and Kobori, Laszlo and
     Dvorak, Zdenek,
  Title = Hormonal regulation of CYP1A expression,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2009,
  Volume = 41,
  Number = 4,
  Pages = 547-572,
  Month = NOV,
  Abstract = Aryl hydrocarbon receptor (AhR) is primarily involved in the
     transcriptional regulation of CYP1A enzymes, which are the main
     catalysts of the metabolic activation or inactivation of numerous
     procarcinogens, carcinogens, environmental toxicants, or therapeutic
     agents. Several endogenous factors, including hormones, can modify CYP1A
     induction, directly influencing CYP1A gene expression or AhR function or
     indirectly via crosstalks with other transcription factors. In this
     article, we summarize the current knowledge about the role of hormones
     (i.e., glucocorticoids, estrogens, progesterone, androgens, insulin, and
     glucagon) and hormone receptors as well as other essential factors
     (e.g., vitamin D, retinoids) in the modulation of CYP1A expression.,
  DOI = 10.3109/03602530903112284,
  ISSN = 0360-2532,
  Unique-ID = ISI:000280164500001,
  

• P. Bachleda, R. Vrzal, and Z. Dvorak, "Activation of MAPKs influences the expression of drug-metabolizing
  enzymes in primary human hepatocytes," GENERAL PHYSIOLOGY AND BIOPHYSICS, vol. 28, iss. 3, pp. 316-320, 2009.
  [Bibtex]

  @article ISI:000272335700013,
  Author = Bachleda, Petr and Vrzal, Radim and Dvorak, Zdenek,
  Title = Activation of MAPKs influences the expression of drug-metabolizing
     enzymes in primary human hepatocytes,
  Journal = GENERAL PHYSIOLOGY AND BIOPHYSICS,
  Year = 2009,
  Volume = 28,
  Number = 3,
  Pages = 316-320,
  Month = SEP,
  Abstract = We examined the effects of model activators of mitogen-activated protein
     kinases (MAPKs) on basal and rifampicin, phenobarbital- and
     dioxin-inducible expression of phase I and phase II biotransformation
     enzymes in primary human hepatocytes. Cells were treated for 24 h with
     sorbitol (SOR), anisomycin (ANI) and epidermal growth factor (EGF) in
     the presence or absence of inducers. The levels of CYP1A1, CYP1A2,
     CYP2B6, CYP3A4, UGT1A1, UGT2B17, SULT1A1, SULT2A1, SULT1B2, GSTA1, GSTA2
     mRNAs were determined. SOR and EGF inhibited the expression of the
     tested genes, while ANI had no effect. We conclude that MAPKs play
     important role in the transcriptional regulation of drug-metabolizing
     enzymes.,
  DOI = 10.4149/gpb\_2009\_03\_316,
  ISSN = 0231-5882,
  Unique-ID = ISI:000272335700013,
  

• R. Vrzal, L. Stejskalova, K. Monostory, P. Maurel, P. Bachleda, P. Pavek, and Z. Dvorak, "Dexamethasone controls aryl hydrocarbon receptor (AhR)-mediated CYP1A1
  and CYP1A2 expression and activity in primary cultures of human
  hepatocytes," CHEMICO-BIOLOGICAL INTERACTIONS, vol. 179, iss. 2-3, pp. 288-296, 2009.
  [Bibtex]

  @article ISI:000265364600028,
  Author = Vrzal, Radim and Stejskalova, Lucie and Monostory, Katalin and Maurel,
     Patrick and Bachleda, Petr and Pavek, Petr and Dvorak, Zdenek,
  Title = Dexamethasone controls aryl hydrocarbon receptor (AhR)-mediated CYP1A1
     and CYP1A2 expression and activity in primary cultures of human
     hepatocytes,
  Journal = CHEMICO-BIOLOGICAL INTERACTIONS,
  Year = 2009,
  Volume = 179,
  Number = 2-3,
  Pages = 288-296,
  Month = MAY 15,
  Abstract = CYP1A1 and CYP1A2 genes encode members of the cytochrome P450
     superfamily of enzymes primarily involved in xenobiotic and drug
     metabolism. In this paper we examined the effects of synthetic
     glucocorticoid dexamethasone (DEX) on aryl hydrocarbon receptor
     (AhR)-mediated regulation of CYP1A1 and CYP1A2 genes and their enzymatic
     activity in primary cultures of human hepatocytes obtained from 17
     donors and prepared in 3 countries.
     Dexamethasone significantly reduced both basal and inducible CYP1A1/2
     ethoxyresorufin-O-deethylase (EROD) activities by more than 75 and 50\%,
     respectively. Glucocorticoid receptor (GR) antagonist RU486 abolished
     this effect suggesting the involvement of GR in the process. In
     contrast, dexamethasone significantly augmented transcriptional
     activation of CYP1A2 mRNA but not CYP1A1 gene by prototype AhR ligands
     2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 3-methylcholanthrene
     (3MC). Dexamethasone had no effect on basal and TCDD-inducible levels of
     CYP1As proteins; however, it reduced the levels of AhR and GR alpha
     mRNAs and AhR protein levels. In addition, using RT(2) Profiler (TM) PCR
     Array, we found the effect of dexamethasone on the expression of several
     co-activators of AhR and GR nuclear receptors in the primary human
     hepatocytes.
     We conclude that dexamethasone controls CYP1A1 and CYP1A2 expression and
     activity in human hepatocytes via multiple mechanisms, which remain to
     be elucidated. (C) 2008 Elsevier Ireland Ltd. All rights reserved.,
  DOI = 10.1016/j.cbi.2008.10.035,
  ISSN = 0009-2797,
  Unique-ID = ISI:000265364600028,
  

• M. Bitman, R. Vrzal, K. Pospechova, L. Svecova, L. Cygalova, Z. Dvorak, and P. Pavek, "Effect of Valproic Acid on Extracellular Mitogen-activated Protein
  Kinase Pathways and Major Transcriptional Factors in Hepatoma Cell Lines
  and Primary Human Hepatocytes," DRUG METABOLISM REVIEWS, vol. 41, iss. 1, pp. 54, 2009.
  [Bibtex]

  @article ISI:000280164800041,
  Author = Bitman, Michal and Vrzal, Radim and Pospechova, Katerina and Svecova,
     Lucie and Cygalova, Lenka and Dvorak, Zdenek and Pavek, Petr,
  Title = Effect of Valproic Acid on Extracellular Mitogen-activated Protein
     Kinase Pathways and Major Transcriptional Factors in Hepatoma Cell Lines
     and Primary Human Hepatocytes,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2009,
  Volume = 41,
  Number = 1,
  Pages = 54,
  Month = MAY,
  Note = 11th European Regional ISSX Meeting, Lisbon, PORTUGAL, MAY 17-20, 2009,
  ISSN = 0360-2532,
  Unique-ID = ISI:000280164800041,
  

• K. Pospechova, V. Rozehnal, L. Stejskalova, R. Vrzal, N. Pospisilova, G. Jamborova, K. May, W. Siegmund, Z. Dvorak, P. Nachtigal, V. Semecky, and P. Pavek, "Expression and activity of vitamin D receptor in the human placenta and
  in choriocarcinoma BeWo and JEG-3 cell lines," MOLECULAR AND CELLULAR ENDOCRINOLOGY, vol. 299, iss. 2, pp. 178-187, 2009.
  [Bibtex]

  @article ISI:000263662500006,
  Author = Pospechova, Katerina and Rozehnal, Veronika and Stejskalova, Lucie and
     Vrzal, Radim and Pospisilova, Nada and Jamborova, Gabriela and May,
     Karen and Siegmund, Werner and Dvorak, Zdenek and Nachtigal, Petr and
     Semecky, Vladimir and Pavek, Petr,
  Title = Expression and activity of vitamin D receptor in the human placenta and
     in choriocarcinoma BeWo and JEG-3 cell lines,
  Journal = MOLECULAR AND CELLULAR ENDOCRINOLOGY,
  Year = 2009,
  Volume = 299,
  Number = 2,
  Pages = 178-187,
  Month = FEB 27,
  Abstract = Vitamin D receptor (VDR) regulates the expression of many genes involved
     in mineral metabolism, cellular proliferation, differentiation and drug
     biotransformation.
     We studied the expression and activity of VDR and its heterodimerization
     partner retinoid X receptor-a (RXR alpha) in choriocarcinoma trophoblast
     cell lines BeWo and JEG-3, in comparison with human isolated placental
     cytotrophoblasts and human full term placenta.
     We found that VDR and RXR alpha are localised in the human term placenta
     trophoblast and expressed in isolated cytotrophoblasts. However, we
     found low expression and no transcriptional activity of VDR in used
     choriocarcinoma cell lines. The inhibitor of DNA methylation,
     5-deoxy-3'-azacytidine, and histone deacetylase inhibitor sodium
     butyrate partially restored the expression of VDR, suggesting an
     epigenetic suppression of the gene inchoriocarcinoma cells.
     Differentiation of BeWocells resulted in up-regulation of VDR mRNA.
     Finally, we observed a non-genomic effect of 1,25(OH)(2)D(3) in the
     activation of the extracellular signal-regulated kinase (ERK) signalling
     pathway in JEG-3 cells. In conclusion, our results suggest an epigenetic
     repression of VDR gene expression and activity in choriocarcinoma cell
     lines, and a non-genomic effect of 1,25(OH)(2)D(3) in JEG-3 cells. (c)
     2008 Elsevier Ireland Ltd. All rights reserved.,
  DOI = 10.1016/j.mce.2008.12.003,
  ISSN = 0303-7207,
  Unique-ID = ISI:000263662500006,
  

2008

• P. Henklova, R. Vrzal, B. Papouskova, P. Bednar, P. Jancova, E. Anzenbacherova, J. Ulrichova, P. Maurel, P. Pavek, and Z. Dvorak, "SB203580, a pharmacological inhibitor of p38 MAP kinase transduction
  pathway activates ERK and JNK MAP kinases in primary cultures of human
  hepatocytes," EUROPEAN JOURNAL OF PHARMACOLOGY, vol. 593, iss. 1-3, pp. 16-23, 2008.
  [Bibtex]

  @article ISI:000259508100003,
  Author = Henklova, Pavla and Vrzal, Radim and Papouskova, Barbora and Bednar,
     Petr and Jancova, Petra and Anzenbacherova, Eva and Ulrichova, Jitka and
     Maurel, Patrick and Pavek, Petr and Dvorak, Zdenek,
  Title = SB203580, a pharmacological inhibitor of p38 MAP kinase transduction
     pathway activates ERK and JNK MAP kinases in primary cultures of human
     hepatocytes,
  Journal = EUROPEAN JOURNAL OF PHARMACOLOGY,
  Year = 2008,
  Volume = 593,
  Number = 1-3,
  Pages = 16-23,
  Month = SEP 28,
  Abstract = Mitogen-activated protein kinases (MAPKs) were extensively studied in
     cancer-derived cell lines; however, studies in non-transformed human
     cells are scarce. In the current paper, we studied the effect of
     SB203580, a pharmacological inhibitor of p38 MAPK, on activation and
     inhibition of p38 MAPK transduction partway in primary human hepatocytes
     (in vitro model of differentiated cells) in comparison with several
     tumor cell lines (proliferating non-differentiated in vitro model). In
     addition, we analyzed the effect of SB203580 on extracellular-regulated
     protein kinase (ERK) and c-jun-N-terminal kinase (JNK) pathways both in
     primary human hepatocytes and tumor cell lines employing primary
     antibodies detecting phosphorylated kinases. We show that SB203580
     activates ERK and JNK in primary cultures of human hepatocytes. The
     levels of ERK-P(Thr202/Tyr204),JNK-P(Thr183/Tyr185) and
     c-Jun-P(Ser63/73), a target down-stream protein of JNK, were increased
     by SB203580. In contrast, SB203580 activated ERK but not JNK in HepG2,
     HL-60, Saos-2 and HaCaT human cancer cell lines. We tested, whether the
     effects of SB203580 are due to metabolism. Using liquid
     chromatography/mass spectrometry, we found one minor metabolite in human
     liver microsomes but not in HepG2 cells. These data imply that
     biotransformation could be responsible for the effects of SB203580 in
     human hepatocytes. This study is the first report on the effects of MAPK
     activators (sorbitol, anisomycin, EGF) and MAPK inhibitors in primary
     human hepatocytes. We observed differential effects of these compounds
     in primary human hepatocytes and in cancer cells, implying the cell-type
     specificity and the essential differences between the role and function
     of MAPKs in normal and cancer cells. (C) 2008 Elsevier B.V. All rights
     reserved.,
  DOI = 10.1016/j.ejphar.2008.07.007,
  ISSN = 0014-2999,
  Unique-ID = ISI:000259508100003,
  

• Z. Dvorak and P. Pavek, "Comment on ``The role of redox-sensitive transcription factors NF-kappa
  B and AP-1 in the modulation of the Cyp1A1 gene by mercury, lead, and
  copper''," FREE RADICAL BIOLOGY AND MEDICINE, vol. 45, iss. 6, pp. 939, 2008.
  [Bibtex]

  @article ISI:000259357300024,
  Author = Dvorak, Zdenek and Pavek, Petr,
  Title = Comment on ``The role of redox-sensitive transcription factors NF-kappa
     B and AP-1 in the modulation of the Cyp1A1 gene by mercury, lead, and
     copper'',
  Journal = FREE RADICAL BIOLOGY AND MEDICINE,
  Year = 2008,
  Volume = 45,
  Number = 6,
  Pages = 939,
  Month = SEP 15,
  DOI = 10.1016/j.freeradbiomed.2008.06.002,
  ISSN = 0891-5849,
  Unique-ID = ISI:000259357300024,
  

• B. Cvek and Z. Dvorak, "The value of proteasome inhibition in cancer," DRUG DISCOVERY TODAY, vol. 13, iss. 15-16, pp. 716-722, 2008.
  [Bibtex]

  @article ISI:000258801100012,
  Author = Cvek, Boris and Dvorak, Zdenek,
  Title = The value of proteasome inhibition in cancer,
  Journal = DRUG DISCOVERY TODAY,
  Year = 2008,
  Volume = 13,
  Number = 15-16,
  Pages = 716-722,
  Month = AUG,
  Abstract = The major approach to the development of anticancer drugs involves
     searching for new compounds, efficient against malignancies, which are
     not, as yet, used clinically. This strategy is time-consuming and
     expensive. Recent studies have disclosed a surprising, but
     mechanistically consistent, anticancer activity of disulfiram
     (antabuse), a drug used for about 50 years in the treatment of
     alcoholism. Disulfiram has been successfully used to suppress hepatic
     metastases originating from ocular melanoma. The pharmacokinetics of
     disulfiram and its pharmacological profile in cancer cell lines and in
     cancer cells obtained from patients is well known. Disulfiram is a
     readily available and inexpensive substance whose adverse effects are
     negligible, compared to classical cancerostatics. In addition, the
     inhibitory potency of disulfiram against the proteasome conforms to
     current anticancer strategies and represents a new, promising approach
     to proteasome inhibition.,
  DOI = 10.1016/j.drudis.2008.05.003,
  ISSN = 1359-6446,
  Unique-ID = ISI:000258801100012,
  

• E. Vrublova, J. Vostalova, R. Vecera, B. Klejdus, D. Stejskaj, P. Kosina, A. Zdarilova, A. Svobodova, V. Lichnovsky, P. Anzenbacher, Z. Dvorak, J. Vicar, V. Simanek, and J. Ulrichova, "The toxicity and pharmacokinetics of dihydrosanguinarine in rat: A pilot
  study," FOOD AND CHEMICAL TOXICOLOGY, vol. 46, iss. 7, pp. 2546-2553, 2008.
  [Bibtex]

  @article ISI:000257480200036,
  Author = Vrublova, Eva and Vostalova, Jitka and Vecera, Rostislav and Klejdus,
     Borivoj and Stejskaj, David and Kosina, Pavel and Zdarilova, Adela and
     Svobodova, Alena and Lichnovsky, Vaclav and Anzenbacher, Pavel and
     Dvorak, Zdenek and Vicar, Jaroslav and Simanek, Vilim and Ulrichova,
     Jitka,
  Title = The toxicity and pharmacokinetics of dihydrosanguinarine in rat: A pilot
     study,
  Journal = FOOD AND CHEMICAL TOXICOLOGY,
  Year = 2008,
  Volume = 46,
  Number = 7,
  Pages = 2546-2553,
  Month = JUL,
  Abstract = The quaternary benzo[c]phenanthridine alkaloid sanguinarine (SG) is
     the main component of Sangrovit (R), a natural livestock feed additive.
     Dihydrosanguinarine (DHSG) has recently been identified as a SG
     metabolite in rat. The conversion of SG to DHSG is a likely elimination
     pathway of SG in mammals. This study was conducted to evaluate the
     toxicity of DHSG in male Wistar rats at concentrations of 100 and 500
     ppm DHSG in feed for 90 days (average doses of 14 and 58 mg DHSG/kg body
     weight/day). No significant alterations in body or organ weights,
     macroscopic details of organs, histopathology of liver, ileum, kidneys,
     tongue, heart or gingiva, clinical chemistry or hematology markers in
     blood in the DHSG-treated animals were found compared to controls. No
     lymphocyte DNA damage by Comet assay, formation of DNA adducts in liver
     by P-32-postlabeling, modulation of cytochrome P450 1A1/2 or changes in
     oxidative stress parameters were found. Thus, repeated dosing of DHSG
     for 90 days at up to 500 ppm in the diet (i.e. approximately 58
     mg/kg/day) showed no evidence of toxicity in contrast to results
     published in the literature. In parallel, DHSG pharmacokinetics was
     studied in rat after oral doses 9.1 or 91 mg/kg body weight. The results
     showed that DHSG undergoes enterohepatic cycling with maximum
     concentration in plasma at the first or second hour following
     application. DHSG is cleared from the body relatively quickly (its
     plasma levels drop to zero after 12 or 18 h, respectively). (C) 2008
     Elsevier Ltd. All rights reserved.,
  DOI = 10.1016/j.fct.2008.04.013,
  ISSN = 0278-6915,
  Unique-ID = ISI:000257480200036,
  

• P. Bachleda and Z. Dvorak, "Pharmacological inhibitors of JNK and ERK kinases SP600125 and U0126 are
  not appropriate tools for studies of drug metabolism because they
  activate aryl hydrocarbon receptor," GENERAL PHYSIOLOGY AND BIOPHYSICS, vol. 27, iss. 2, pp. 143-145, 2008.
  [Bibtex]

  @article ISI:000258040300009,
  Author = Bachleda, P. and Dvorak, Z.,
  Title = Pharmacological inhibitors of JNK and ERK kinases SP600125 and U0126 are
     not appropriate tools for studies of drug metabolism because they
     activate aryl hydrocarbon receptor,
  Journal = GENERAL PHYSIOLOGY AND BIOPHYSICS,
  Year = 2008,
  Volume = 27,
  Number = 2,
  Pages = 143-145,
  Month = JUN,
  Abstract = Mitogen-activated protein kinases (MAPKs) are important regulators of
     aryl hydrocarbon receptor (AhR). An immense progress in MAPKs'
     biochemistry was attained with the discovery of their specific
     pharmacological inhibitors. Unfortunately, the inhibitors of JNK and ERK
     MAPKs, i.e. SP600125 and U0126, respectively, affect AhR-CYPIA signaling
     pathway because they are partial agonists of AhR and induce CYP1A genes.
     This implies that SP600125 and U0126 are inappropriate tools for studies
     of the role of MAPKs in AhR regulation. The results from studies using
     SP600125 or U 126, past or future, should be interpreted with prudence
     regarding their stimulatory effects on AhR-CYP1A pathway.,
  ISSN = 0231-5882,
  Unique-ID = ISI:000258040300009,
  

• P. Henklova, R. Vrzal, J. Ulrichova, and Z. Dvorak, "Role of mitogen-activated protein kinases in aryl hydrocarbon receptor
  signaling," CHEMICO-BIOLOGICAL INTERACTIONS, vol. 172, iss. 2, pp. 93-104, 2008.
  [Bibtex]

  @article ISI:000255100000001,
  Author = Henklova, Pavla and Vrzal, Radim and Ulrichova, Jitka and Dvorak, Zdenk,
  Title = Role of mitogen-activated protein kinases in aryl hydrocarbon receptor
     signaling,
  Journal = CHEMICO-BIOLOGICAL INTERACTIONS,
  Year = 2008,
  Volume = 172,
  Number = 2,
  Pages = 93-104,
  Month = MAR 27,
  Abstract = Human populations are increasingly exposed to a number of environmental
     pollutants such as polycyclic aromatic hydrocarbons, polychlorinated
     biphenyls and dioxins. These compounds are activators of the aryl
     hydrocarbon receptor (AhR) that controls the expression of many genes
     including those for detoxification enzymes. The regulatory mechanisms of
     AhR are multi-factorial and include phosphorylation by various protein
     kinases. Significant progress in the research of mitogen-activated
     protein kinases (MAPKs) has been achieved in the last decade. Isolated
     reports have been published on the role of MAPKs in AhR functions and
     vice versa, with activation of MAPKs by AhR ligands.
     This mini-review summarizes current knowledge on the mutual interactions
     between MAPKs and AhR. The majority of studies has been done on
     cancer-derived cell lines that have impaired cell cycle regulation and
     lacks the complete detoxilication apparatus. We emphasize the importance
     of the future studies that should be done on non-transformed cells to
     distinguish the role of MAPKs in cancer and normal cells. Primary
     cultures of human or rodent hepatocytes that are equipped with a fully
     functional biotransformation battery or xenobiotics-metabolizing
     extra-hepatic tissues should be the models of choice, as the results in
     our experiments confirm. 9 2007 Elsevier Ireland Ltd. All rights
     reserved.,
  DOI = 10.1016/j.cbi.2007.12.005,
  ISSN = 0009-2797,
  Unique-ID = ISI:000255100000001,
  

• R. Vrzal, M. Daujat-Chavanieu, J. Pascussi, J. Ulrichova, P. Maurel, and Z. Dvorak, "Microtubules-interfering agents restrict aryl hydrocarbon
  receptor-mediated CYP1A2 induction in primary cultures of human
  hepatocytes via c-jun-N-terminal kinase and glucocorticoid receptor," EUROPEAN JOURNAL OF PHARMACOLOGY, vol. 581, iss. 3, pp. 244-254, 2008.
  [Bibtex]

  @article ISI:000253752600002,
  Author = Vrzal, Radim and Daujat-Chavanieu, Martine and Pascussi, Jean-Marc and
     Ulrichova, Jitka and Maurel, Patrick and Dvorak, Zdenek,
  Title = Microtubules-interfering agents restrict aryl hydrocarbon
     receptor-mediated CYP1A2 induction in primary cultures of human
     hepatocytes via c-jun-N-terminal kinase and glucocorticoid receptor,
  Journal = EUROPEAN JOURNAL OF PHARMACOLOGY,
  Year = 2008,
  Volume = 581,
  Number = 3,
  Pages = 244-254,
  Month = MAR 10,
  Abstract = Disruption of microtubules has been shown to cause suppression of
     inducibility of major cytochromes P450 (CYP) through several nuclear
     receptors. Here we tested the effects of structurally different
     clinically used microtubules-interfering agents (MIAs), such as
     colchicine, vincristine, vinblastine, nocodazole and taxol on aryl
     hydrocarbon receptor signaling pathway in human hepatocytes. We show
     that tested MIAs inhibit 2,3,7,8-tetrachlorodibenzo-p-dioxin
     (TCDD)-inducible expression of CYP1A2 mRNA and restrict TCDD-dependent
     nuclear translocation of aryl hydrocarbon receptor. On the other hand,
     these MIAs increased the content of aryl hydrocarbon receptor protein
     and mRNA by transcriptional mechanism. We show that the MIAs activate
     c-Jun -N-terminal kinase (JNK), partly p38 but not
     extracellular-regulated protein kinase (ERK). Consistently, sorbitol, a
     model activator of JNK, inhibited TCDD-mediated induction of CYP1A2 mRNA
     and down-regulated tyrosine aminotransferase mRNA - a target gene of
     glucocorticoid receptor. Dexamethasone had the opposite effect on aryl
     hydrocarbon receptor signaling and decreased aryl hydrocarbon receptor
     mRNA and augmented the inducibility of CYP1A2 by TCDD. We conclude that
     the effects of tested MIAs on aryl hydrocarbon receptor-CYP1A2 signaling
     pathway are dual, i.e. they inhibit transcriptional activity and nuclear
     translocation of aryl hydrocarbon receptor but in parallel increase aryl
     hydrocarbon receptor protein and mRNA level. Microtubules destabilizers
     have the same effects as stabilizer taxol. This implies that aryl
     hydrocarbon receptor functions depend on microtubules dynamics but not
     integrity. Perturbation of aryl hydrocarbon receptor-CYP1A2 signaling by
     MIAs comprises glucocorticoid receptor-JNK and probably aryl hydrocarbon
     receptor-JNK/glucocorticoid receptor interactions. We also demonstrate
     that the effects of MIAs in human hepatocytes do not proceed via
     arresting cell cycle as confirmed by flow cytometry (FACS) analyses. (C)
     2007 Elsevier B.V. All rights reserved.,
  DOI = 10.1016/j.ejphar.2007.11.059,
  ISSN = 0014-2999,
  Unique-ID = ISI:000253752600002,
  

• P. Pavek and Z. Dvorak, "Xenobiotic-induced transcriptional regulation of xenobiotic metabolizing
  enzymes of the cytochrome P450 superfamily in human extrahepatic tissues," CURRENT DRUG METABOLISM, vol. 9, iss. 2, pp. 129-143, 2008.
  [Bibtex]

  @article ISI:000253936700004,
  Author = Pavek, Petr and Dvorak, Zdenek,
  Title = Xenobiotic-induced transcriptional regulation of xenobiotic metabolizing
     enzymes of the cytochrome P450 superfamily in human extrahepatic tissues,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2008,
  Volume = 9,
  Number = 2,
  Pages = 129-143,
  Month = FEB,
  Abstract = Numerous members of the cytochrome P450 (CYP) superfamily are induced
     after exposure to a variety of xenobiotics in human liver. We have
     gained considerable mechanistic insights into these processes in
     hepatocytes and multiple ligand-activated transcription factors have
     been identified over the past two decades. Families CYP1, CYP2 and CYP3
     involved in xenobiotic metabolism are also expressed in a range of
     extrahepatic tissues (e. g. intestine, brain, kidney, placenta, lung,
     adrenal gland, pancreas, skin, mammary gland, uterus, ovary, testes and
     prostate). Since the expression of the majority of the isoforms appears
     to be very low in the extrahepatic tissues in comparison with
     predominant expression in adult liver, the role of the enzymes in
     overall biotransformation and total body clearance is minor. However,
     basal expression and up-regulation of extrahepatic CYP enzymes can
     significantly affect local disposition of xenobiotics or endogenous
     compounds in peripheral tissues and thus modify their
     pharmacological/toxicological effects or affect absorption of
     xenobiotics into systemic circulation.
     The goal of this review is to critically examine our current
     understanding of molecular mechanisms involved in induction of
     xenobiotic metabolizing CYP genes of human families CYP1, CYP2 and CYP3
     by exogenous chemicals in extrahepatic tissues. We concentrate on organs
     such as the intestine, kidney, lung, placenta and skin, which are
     involved in drug distribution and clearance or are in direct contact
     with environmental xenobiotics. We also discuss single nucleotide
     polymorphisms (SNPs) of key CYPs, which at the level of transcription
     affect expression of the genes in the extrahepatic tissues or are
     associated with some pathophysiological stages or disorders in the
     organs.,
  DOI = 10.2174/138920008783571774,
  ISSN = 1389-2002,
  Unique-ID = ISI:000253936700004,
  

• T. Onica, K. Nichols, M. Larin, L. Ng, A. Maslen, Z. Dvorak, J. Pascussi, M. Vilarem, P. Maurel, and G. M. Kirby, "Dexamethasone-mediated up-regulation of human CYP2A6 involves the
  glucocorticoid receptor and increased binding of hepatic nuclear factor
  4 alpha to the proximal promoter," MOLECULAR PHARMACOLOGY, vol. 73, iss. 2, pp. 451-460, 2008.
  [Bibtex]

  @article ISI:000252597300019,
  Author = Onica, Tania and Nichols, Kathleen and Larin, Meghan and Ng, Lorraine
     and Maslen, Ann and Dvorak, Zdenek and Pascussi, Jean-Marc and Vilarem,
     Marie-Josee and Maurel, Patrick and Kirby, Gordon M.,
  Title = Dexamethasone-mediated up-regulation of human CYP2A6 involves the
     glucocorticoid receptor and increased binding of hepatic nuclear factor
     4 alpha to the proximal promoter,
  Journal = MOLECULAR PHARMACOLOGY,
  Year = 2008,
  Volume = 73,
  Number = 2,
  Pages = 451-460,
  Month = FEB,
  Abstract = Human cytochrome P450 2A6 (CYP2A6) metabolizes various clinically
     relevant compounds, including nicotine-and tobacco-specific
     procarcinogens; however, transcriptional regulation of this gene is
     poorly understood. We investigated the role of the glucocorticoid
     receptor (GR) in transcriptional regulation of CYP2A6. Dexamethasone
     (DEX) increased CYP2A6 mRNA and protein levels in human hepatocytes in
     primary culture. This effect was attenuated by the GR receptor
     antagonist mifepristone (RU486; 17 beta-hydroxy-11
     beta-[4-dimethylamino phenyl]-17
     alpha-[1-propynyl]estra-4,9-dien-3-one), suggesting that induction of
     CYP2A6 by DEX was mediated by the GR. In gene reporter assays, DEX
     caused dose-dependent increases in luciferase activity that was also
     prevented by RU486 and progressive truncations of the CYP2A6 promoter
     delineated DEX-responsiveness to a -95 to +12 region containing an
     hepatic nuclear factor 4 (HNF4) alpha response element (HNF4-RE).
     Mutation of the HNF4-RE abrogated HNF4 alpha-and DEX-mediated
     transactivation of CYP2A6. In addition, overexpression of HNF4 alpha
     increased CYP2A6 transcriptional activity by 3-fold. DEX increased HNF4
     alpha mRNA levels by 4-fold; however, the amount of HNF4 alpha nuclear
     protein was unaltered. Electrophoretic mobility shift, chromatin
     immunoprecipitation (ChIP), and streptavidin DNA binding assays revealed
     that DEX increased binding of HNF4 alpha to the HNF4-RE and that an
     interaction of GR and HNF4 alpha occurred at this site. Moreover, ChIP
     assays indicated that histone H4 acetylation of the CYP2A6 proximal
     promoter chromatin was increased by DEX that may allow for increased
     binding of HNF4 alpha to the HNF4-RE in human hepatocytes. These
     findings indicate that increased expression of CYP2A6 by DEX is mediated
     by the GR via a nonconventional transcriptional mechanism involving
     interaction of HNF4 alpha with an HNF4-RE rather than a glucocorticoid
     response element.,
  DOI = 10.1124/mol.107.039354,
  ISSN = 0026-895X,
  Unique-ID = ISI:000252597300019,
  

• L. Svecova, R. Vrzal, L. Burysek, E. Anzenbacherova, L. Cerveny, J. Grim, F. Trejtnar, J. Kunes, M. Pour, F. Staud, P. Anzenbacher, Z. Dvorak, and P. Pavek, "Azole antimycotics differentially affect rifampicin-induced pregnane x
  receptor-mediated CYP3A4 gene expression," DRUG METABOLISM AND DISPOSITION, vol. 36, iss. 2, pp. 339-348, 2008.
  [Bibtex]

  @article ISI:000252634900016,
  Author = Svecova, Lucie and Vrzal, Radim and Burysek, Ladislav and
     Anzenbacherova, Eva and Cerveny, Lukas and Grim, Jiri and Trejtnar,
     Frantisek and Kunes, Jiri and Pour, Milan and Staud, Frantisek and
     Anzenbacher, Pavel and Dvorak, Zdenek and Pavek, Petr,
  Title = Azole antimycotics differentially affect rifampicin-induced pregnane x
     receptor-mediated CYP3A4 gene expression,
  Journal = DRUG METABOLISM AND DISPOSITION,
  Year = 2008,
  Volume = 36,
  Number = 2,
  Pages = 339-348,
  Month = FEB,
  Abstract = Azole antifungal drug ketoconazole has recently been demonstrated as an
     inhibitor of a ligand-induced pregnane X receptor (PXR)-mediated
     transcriptional regulation of the CYP3A4 gene through disruption of PXR
     interaction with steroid receptor coactivator (SRC)-1. In contrast,
     other clotrimazole-derived antifungal agents are known as potent
     inducers of CYP3A4 through PXR. In the present study, we examined
     effects of azole antimycotics clotrimazole, ketoconazole, econazole,
     oxiconazole, miconazole, fluconazole, and itraconazole on PXR-mediated
     expression of CYP3A4. We investigated individual effects of the tested
     azoles as well as their action on rifampicin-induced PXR-mediated
     transactivation and expression of CYP3A4 in LS174T cell line and primary
     human hepatocytes, their interactions with PXR ligand-binding domain,
     and azole-mediated recruitment of SRC-1 to PXR. In addition, applying
     the pharmacodynamic approach and dose-response analysis, we aimed to
     describe the nature of potential interactions of tested azole
     antimycotics coadministered with a prototypical PXR ligand rifampicin in
     transactivation of CYP3A4 gene. We describe additive and antagonistic
     interactions of partial and full agonists of PXR nuclear receptor in the
     therapeutic group of azole antimycotics in rifampicin-mediated
     transactivation of CYP3A4. We show that oxiconazole is a highly
     efficacious activator of CYP3A4 transactivation, which could be
     antagonized by rifampicin in a competitive manner. In addition, we show
     that activation of the CYP3A4 promoter is a complex process, which is
     not exclusively determined by azole-PXR interactions, and we suggest
     that the ability of some azoles to affect recruitment of SRC-1 to PXR
     modulates their net effects in transactivation of CYP3A4 both in the
     absence or presence of rifampicin.,
  DOI = 10.1124/dmd.107.018341,
  ISSN = 0090-9556,
  Unique-ID = ISI:000252634900016,
  

• Z. Dvorak, R. Vrzal, P. Henklova, P. Jancova, E. Anzenbacheroua, P. Maurel, L. Svecova, P. Pavek, J. Ehrmann, R. Havlik, P. Bednar, K. Lemr, and J. Ulrichova, "JNK inhibitor SP600125 is a partial agonist of human aryl hydrocarbon
  receptor and induces CYP1A1 and CYP1A2 genes in primary human
  hepatocytes," BIOCHEMICAL PHARMACOLOGY, vol. 75, iss. 2, pp. 580-588, 2008.
  [Bibtex]

  @article ISI:000252842300024,
  Author = Dvorak, Zdenek and Vrzal, Radim and Henklova, Paula and Jancova, Petra
     and Anzenbacheroua, Eva and Maurel, Patrick and Svecova, Lucie and
     Pavek, Petr and Ehrmann, Jiri and Havlik, Roman and Bednar, Petr and
     Lemr, Karel and Ulrichova, Jitka,
  Title = JNK inhibitor SP600125 is a partial agonist of human aryl hydrocarbon
     receptor and induces CYP1A1 and CYP1A2 genes in primary human
     hepatocytes,
  Journal = BIOCHEMICAL PHARMACOLOGY,
  Year = 2008,
  Volume = 75,
  Number = 2,
  Pages = 580-588,
  Month = JAN 15,
  Abstract = SP600125, a specific inhibitor of c-Jun-N-Terminal kinase (JNK), was
     reported as a ligand and antagonist of aryl hydrocarbon receptor (AhR)
     [Joiakim A, Mathieu PA, Palermo C, Gasiewicz TA, Reiners Jr JJ. The
     Jun N terminal kinase inhibitor SP600125 is a ligand and antagonist of
     the aryl hydrocarbon receptor. Drug Metab Dispos 2003;31(11):1279-82].
     Here we show that SP600125 is not an antagonist but a partial agonist of
     human AhR.
     SP600125 significantly induced CYP1A1 and CYP1A2 mRNAs in primary human
     hepatocytes and CYP1A1 mRNA in human hepatoma cells HepG2. This effect
     was abolished by resveratrol, an antagonist of AhR. Consistent with the
     recent report, SP600125 dose-dependently inhibited CYP1A1 and CYPIA2
     genes induction by a prototype AhR ligand 2,3,7,8-tetrachlorodibenzo-p
     -dioxin (TCDD) in human hepatocytes. Moreover, SP600125 displayed
     typical behavior of a partial agonist in HepG2 cells transiently
     transfected with a reporter plasmid containing two inverted repeats of
     the dioxin responsive element or with a plasmid containing 5'-flanking
     region of human CYP1A1 gene. SP600125 transactivated the reporter
     plasmids with EC50 of 0.005 and 1.89 mu M, respectively. On the other
     hand, TCDD-dependent transactivation of the reporter plasmids was
     inhibited by SP600125 with IC50 values of 1.54 and 2.63 mu M,
     respectively. We also tested, whether the effects of SP600125 are due to
     metabolism. Using liquid chromatography/mass spectrometry approach, we
     observed formation of two minor monohydroxylated metabolites of SP600125
     in human hepatocytes, human liver microsomes but not in HepG2 cells.
     These data imply that biotransformation is not responsible for the
     effects of SP600125 on AhR signaling.
     In conclusion, we demonstrate that SP600125 is a partial agonist of
     human AhR, which induces CYP1A genes. (c) 2007 Elsevier Inc. All rights
     reserved.,
  DOI = 10.1016/j.bcp.2007.09.013,
  ISSN = 0006-2952,
  Unique-ID = ISI:000252842300024,
  

• Z. Dvorak, R. Vrzal, P. Pavek, and J. Ulrichova, "An evidence for regulatory cross-talk between aryl hydrocarbon receptor
  and glucocorticoid receptor in HepG2 cells," PHYSIOLOGICAL RESEARCH, vol. 57, iss. 3, pp. 427-435, 2008.
  [Bibtex]

  @article ISI:000257270900014,
  Author = Dvorak, Z. and Vrzal, R. and Pavek, P. and Ulrichova, J.,
  Title = An evidence for regulatory cross-talk between aryl hydrocarbon receptor
     and glucocorticoid receptor in HepG2 cells,
  Journal = PHYSIOLOGICAL RESEARCH,
  Year = 2008,
  Volume = 57,
  Number = 3,
  Pages = 427-435,
  Abstract = Aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR) play
     crucial role in the regulation of drug metabolizing enzymes and in many
     essential physiological processes. Cellular signaling by these receptors
     shares several functional and regulatory features. Here we investigated
     regulatory cross-talk between these two receptors. Human hepatoma cells
     (HepG2) were the model of choice. We analyzed the effects of
     dexamethasone (DEX) and dioxin ( TCDD) on i) expression of AhR and GR
     alpha mRNAs; ii) levels of AhR and GR proteins; iii) transcriptional
     activities of AhR and GR in reporter assays; iv)
     7-ethoxyresorufin-O-deethylase activity ( EROD). We found that both DEX
     and TCDD affected AhR and GR mRNAs expression, proteins levels and
     transcriptional activities in HepG2 cells. These effects on cellular
     signaling by AhR and GR comprised up-/down- regulation of gene
     expression and ligand-dependent protein degradation. We conclude that
     interactive regulatory cross-talk between GR and AhR receptors in HepG2
     cells defines possible implications in physiology and drug metabolism.
     Future research should be focused on the investigation of AhR-GR
     cross-talk in various normal human cells and tissues both in vitro and
     in vivo.,
  ISSN = 0862-8408,
  Unique-ID = ISI:000257270900014,
  

• Z. Dvorak, R. Vrzal, P. Henklova, P. Jancova, E. Anzenbacherova, P. Maurel, P. Pavek, P. Bednar, and J. Ulrichova, "JNK PHARMACOLOGICAL INHIBITOR SP600125 IS A PARTIAL AGONIST OF HUMAN
  ARYL HYDROCARBON RECEPTOR AND INDUCES CYP1A1 AND CYP1A2 GENES IN PRIMARY
  HUMAN HEPATOCYTES," DRUG METABOLISM REVIEWS, vol. 40, pp. 147, 2008.
  [Bibtex]

  @article ISI:000265257400128,
  Author = Dvorak, Zdenek and Vrzal, Radim and Henklova, Pavla and Jancova, Petra
     and Anzenbacherova, Eva and Maurel, Patrick and Pavek, Petr and Bednar,
     Petr and Ulrichova, Jitka,
  Title = JNK PHARMACOLOGICAL INHIBITOR SP600125 IS A PARTIAL AGONIST OF HUMAN
     ARYL HYDROCARBON RECEPTOR AND INDUCES CYP1A1 AND CYP1A2 GENES IN PRIMARY
     HUMAN HEPATOCYTES,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2008,
  Volume = 40,
  Pages = 147,
  Note = 10th European Regional Meeting of the
     International-Society-for-the-Study-of-Xenobiotics, Vienna, AUSTRIA, MAY
     18-21, 2008,
  Organization = Int Soc Study Xenobiot,
  ISSN = 0360-2532,
  Unique-ID = ISI:000265257400128,
  

• J. Vrba, Z. Dvorak, J. Ulrichova, and M. Modriansky, "Conventional protein kinase C isoenzymes undergo dephosphorylation in
  neutrophil-like HL-60 cells treated by chelerythrine or sanguinarine," CELL BIOLOGY AND TOXICOLOGY, vol. 24, iss. 1, pp. 39-53, 2008.
  [Bibtex]

  @article ISI:000251969500005,
  Author = Vrba, J. and Dvorak, Z. and Ulrichova, J. and Modriansky, M.,
  Title = Conventional protein kinase C isoenzymes undergo dephosphorylation in
     neutrophil-like HL-60 cells treated by chelerythrine or sanguinarine,
  Journal = CELL BIOLOGY AND TOXICOLOGY,
  Year = 2008,
  Volume = 24,
  Number = 1,
  Pages = 39-53,
  Month = JAN,
  Abstract = The quaternary benzo[c]phenanthridine alkaloid chelerythrine is widely
     used as an inhibitor of protein kinase C (PKC). However, in biological
     systems chelerythrine interacts with an array of proteins. In this
     study, we examined the effects of chelerythrine and sanguinarine on
     conventional PKCs (cPKCs) and PKC upstream kinase,
     phosphoinositide-dependent protein kinase 1 (PDK1), under complete
     inhibition conditions of PKC-dependent oxidative burst. In
     neutrophil-like HL-60 cells, sanguinarine and chelerythrine inhibited
     N-formyl-Met-Leu-Phe, phorbol 12-myristate 13-acetate (PMA)-, and
     A23187-induced oxidative burst with IC50 values not exceeding 4.6 mu
     mol/L, but the inhibition of PMA-stimulated cPKC activity in intact
     cells required at least fivefold higher alkaloid concentrations. At
     concentrations below 10 mu mol/L, sanguinarine and chelerythrine
     prevented phosphorylation of similar to 80 kDa protein and sequestered
     similar to 60 kDa phosphoprotein in cytosol. Moreover, neither
     sanguinarine nor chelerythrine impaired PMA-stimulated translocation of
     autophosphorylated PKC alpha/beta II isoenzymes, but both alkaloids
     induced dephosphorylation of the turn motif in PKC alpha/beta II. The
     dephosphorylation did not occur in unstimulated cells and it was not
     accompanied by PKC degradation. Furthermore, cell treatment with
     sanguinarine or chelerythrine resulted in phosphorylation of similar to
     70 kDa protein by PDK1. We conclude that PKC-dependent cellular events
     are affected by chelerythrine primarily by multiple protein interactions
     rather than by inhibition of PKC activity.,
  DOI = 10.1007/s10565-007-9014-1,
  ISSN = 0742-2091,
  Unique-ID = ISI:000251969500005,
  

• R. Vrzal, P. Henklova, B. Papoukova, P. Bednar, P. Jancova, E. Anzenbacherova, J. Ulrichova, P. Maurel, P. Pavek, and Z. Dvorak, "AN INHIBITOR OF P38 MAP KINASE ACTIVATES ERK AND JNK MAP KINASES IN
  PRIMARY CULTURES OF HUMAN HEPATOCYTES," DRUG METABOLISM REVIEWS, vol. 40, pp. 146, 2008.
  [Bibtex]

  @article ISI:000265257400127,
  Author = Vrzal, Radim and Henklova, Pavla and Papoukova, Barbora and Bednar, Petr
     and Jancova, Petra and Anzenbacherova, Eva and Ulrichova, Jitka and
     Maurel, Patrick and Pavek, Petr and Dvorak, Zdenek,
  Title = AN INHIBITOR OF P38 MAP KINASE ACTIVATES ERK AND JNK MAP KINASES IN
     PRIMARY CULTURES OF HUMAN HEPATOCYTES,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2008,
  Volume = 40,
  Pages = 146,
  Note = 10th European Regional Meeting of the
     International-Society-for-the-Study-of-Xenobiotics, Vienna, AUSTRIA, MAY
     18-21, 2008,
  Organization = Int Soc Study Xenobiot,
  ISSN = 0360-2532,
  Unique-ID = ISI:000265257400127,
  

2007

• P. Pavek, L. Cerveny, L. Svecova, M. Brysch, A. Libra, R. Vrzal, P. Nachtigal, F. Staud, J. Ulrichova, Z. Fendrich, and Z. Dvorak, "Examination of glucocorticoid receptor alpha-mediated transcriptional
  regulation of P-glycoprotein, CYP3A4, and CYP2C9 genes in placental
  trophoblast cell lines," PLACENTA, vol. 28, iss. 10, pp. 1004-1011, 2007.
  [Bibtex]

  @article ISI:000249650500005,
  Author = Pavek, P. and Cerveny, L. and Svecova, L. and Brysch, M. and Libra, A.
     and Vrzal, R. and Nachtigal, P. and Staud, F. and Ulrichova, J. and
     Fendrich, Z. and Dvorak, Z.,
  Title = Examination of glucocorticoid receptor alpha-mediated transcriptional
     regulation of P-glycoprotein, CYP3A4, and CYP2C9 genes in placental
     trophoblast cell lines,
  Journal = PLACENTA,
  Year = 2007,
  Volume = 28,
  Number = 10,
  Pages = 1004-1011,
  Month = OCT,
  Abstract = The placental trophoblast at different stages of pregnancy contains some
     drug transporters and xenobiotic-metabolising enzymes, as well as
     ligand-activated nuclear receptors, which control their inducible
     transcriptional regulation. Glucocorticoid receptor alpha (GR alpha) is
     expressed in both placental syncytiotrophoblast and cytotrophoblast. GRa
     was shown to control inducible expression of several enzymes of the
     cytochrome P-450 family (CYP) and the drug transporter P-glycoprotein in
     the liver. However, GR alpha-mediated transcriptional regulation of drug
     transporters and CYPs has not been studied in the placental trophoblast.
     In this study, we examined the expression and activity of GR alpha in
     the transcriptional regulation of P-glycoprotein, CYP3A4, and CYP2C9 in
     placental trophoblast cell lines. Employing RT-PCR, Western blotting,
     and luciferase gene reporter assay, we detected the expression and
     activity of GR alpha in JEG3 and BeWo cell lines. However, we observed
     that only MDR1 mRNA was up-regulated after treatment of placental cells
     with dexamethasone. Accordingly, only the promoter of the MDR1 gene was
     activated by dexamethasone in gene reporter assays in placental cells
     and the activation was abolished by RU486, an antagonist of GR alpha.
     CYP3A4 and CYP2C9 promoters were activated in placental cells only after
     co-transfection with hepatocyte nuclear factor 4 alpha (HNF4 alpha),
     which indicates the hepatocyte-specific character of GR alpha-mediated
     regulation of the genes. On the other hand, coexpression of HNF4 alpha
     had no effect on the activation of the MDR1 gene promoter, suggesting
     HNF4 alpha-independent regulation via GR alpha. We conclude that GR
     alpha may be involved in the transcriptional regulation of
     P-glycoprotein in the placental trophoblast. We also indicate that the
     CYP3A4 and CYP2C9 genes are not inducible through GR alpha in placental
     cell lines, due to the lack of HNF4 alpha expression and possibly some
     additional hepatocyte-specific transcriptional factors. (C) 2007
     Elsevier Ltd. All rights reserved.,
  DOI = 10.1016/j.placenta.2007.05.001,
  ISSN = 0143-4004,
  Unique-ID = ISI:000249650500005,
  

• Z. Dvorak, M. Modriansky, J. Vrba, J. Ulrichova, V. Krystof, J. Styskala, and P. Pavek, "Evaluation of novel microtubules interfering agents myoseverin,
  tubulyzine and E2GG in primary cultures of rat hepatocytes," GENERAL PHYSIOLOGY AND BIOPHYSICS, vol. 26, iss. 3, pp. 173-180, 2007.
  [Bibtex]

  @article ISI:000251272400003,
  Author = Dvorak, Z. and Modriansky, M. and Vrba, J. and Ulrichova, J. and
     Krystof, V. and Styskala, J. and Pavek, P.,
  Title = Evaluation of novel microtubules interfering agents myoseverin,
     tubulyzine and E2GG in primary cultures of rat hepatocytes,
  Journal = GENERAL PHYSIOLOGY AND BIOPHYSICS,
  Year = 2007,
  Volume = 26,
  Number = 3,
  Pages = 173-180,
  Month = SEP,
  Abstract = We investigated the effects of novel microtubules interfering agents
     (MIAs) in primary cultures of rat hepatocytes. Cells were treated for 24
     h with a known compound colchicine and newly synthesized derivatives
     myoseverin, tubulyzine, and E2GG. We examined the effects of MIAs on
     microtubules network integrity and on the polymerization capability of
     isolated tubulin. All tested MIAs inhibited microtubules assembly with
     the following IC50 values: tubulyzine (4.4 +/- 0.9 mu mol/1), myoseverin
     (7.0 +/- 0.8 mu mol/1), E2GG (16 +/- 2 mu mol/1), colchicine (2.0 +/-
     0.4 mu mol/1). The potency of MIAs to perturb microtubular network
     integrity (monitored by immune-histochemistry) increased in the order
     tubulyzine < myoseverin < E2GG < colchicine.
     We described recently deleterious effects of MIAs on the expression of
     drug metabolizing enzymes, including CYPIAI Here we observed inhibitory
     effects of novel MIAs on dioxin-inducible expression of CYP1A1 mRNA in
     rat hepatocytes. We conclude that novel MIAs exert analogical biological
     response as classical MIAs such as colchicine or nocodazole. This
     further supports the hypothesis that tubulin is the primordial target of
     MIAs within the cell and that perturbation of microtubules dynamics
     and/or integrity triggers the biological effects described here.,
  ISSN = 0231-5882,
  Unique-ID = ISI:000251272400003,
  

• D. Macejova, Z. Dvorak, R. Vrzal, J. Ulrichova, S. Ondkova, and J. Brtko, "The effect of all-trans retinoic acid and/or colchicine on expression of
  rexinoid and thyroid hormone nuclear receptors and their coregulators in
  primary rat hepatocytes," GENERAL PHYSIOLOGY AND BIOPHYSICS, vol. 26, iss. 3, pp. 240-242, 2007.
  [Bibtex]

  @article ISI:000251272400012,
  Author = Macejova, D. and Dvorak, Z. and Vrzal, R. and Ulrichova, J. and Ondkova,
     S. and Brtko, J.,
  Title = The effect of all-trans retinoic acid and/or colchicine on expression of
     rexinoid and thyroid hormone nuclear receptors and their coregulators in
     primary rat hepatocytes,
  Journal = GENERAL PHYSIOLOGY AND BIOPHYSICS,
  Year = 2007,
  Volume = 26,
  Number = 3,
  Pages = 240-242,
  Month = SEP,
  Abstract = In the present work, the effects of colchicine (COL) and/or all-trans
     retinoic acid (ATRA) on expression of rexinoid receptors (RXRs) (alpha,
     beta, gamma), thyroid hormone receptor a and coregulators N-CoR, SMRT
     and SRC-1 mRNA in primary rat hepatocytes as a model of no-proliferating
     cells were investigated. Treatment with these components, either alone
     or in combination, induced differences of the expression profiles
     between distinct treatment groups.,
  ISSN = 0231-5882,
  Unique-ID = ISI:000251272400012,
  

• L. Cerveny, L. Svecova, E. Anzenbacherova, R. Vrzal, F. Staud, Z. Dvorak, J. Ulrichova, P. Anzenbacher, and P. Pavek, "Valproic acid induces CYP3A4 and MDR1 gene expression by activation of
  constitutive androstane receptor and pregnane X receptor pathways," DRUG METABOLISM AND DISPOSITION, vol. 35, iss. 7, pp. 1032-1041, 2007.
  [Bibtex]

  @article ISI:000247373800004,
  Author = Cerveny, Lukas and Svecova, Lucie and Anzenbacherova, Eva and Vrzal,
     Radim and Staud, Frantisek and Dvorak, Zdenek and Ulrichova, Jitka and
     Anzenbacher, Pavel and Pavek, Petr,
  Title = Valproic acid induces CYP3A4 and MDR1 gene expression by activation of
     constitutive androstane receptor and pregnane X receptor pathways,
  Journal = DRUG METABOLISM AND DISPOSITION,
  Year = 2007,
  Volume = 35,
  Number = 7,
  Pages = 1032-1041,
  Month = JUL,
  Abstract = In our study, we tested the hypothesis whether valproic acid (VPA) in
     therapeutic concentrations has potential to affect expression of CYP3A4
     and MDR1 via constitutive androstane receptor (CAR) and pregnane X
     receptor (PXR) pathways. Interaction of VPA with CAR and PXR nuclear
     receptors was studied using luciferase reporter assays, real-time
     reverse transcriptase polymerase chain reaction (RT-PCR),
     electrophoretic mobility shift assay (EMSA), and analysis of CYP3A4
     catalytic activity. Using transient transfection reporter assays in
     HepG2 cells, VPA was recognized to activate CYP3A4 promoter via CAR and
     PXR pathways. By contrast, a significant effect of VPA on MDR1 promoter
     activation was observed only in CAR-cotransfected HepG2 cells. These
     data well correlated with up-regulation of CYP3A4 and MDR1 mRNAs
     analyzed by real-time RT-PCR in cells transfected with expression
     vectors encoding CAR or PXR and treated with VPA. In addition, VPA
     significantly up-regulated CYP3A4 mRNA in primary hepatocytes and
     augmented the effect of rifampicin. EMSA experiments showed VPA-mediated
     augmentation of CAR/retinoid X receptor alpha heterodimer binding to
     direct repeat 3 (DR3) and DR4 responsive elements of CYP3A4 and MDR1
     genes, respectively. Finally, analysis of specific CYP3A4 catalytic
     activity revealed its significant increase in VPA-treated LS174T cells
     transfected with PXR. In conclusion, we provide novel insight into the
     mechanism by which VPA affects gene expression of CYP3A4 and MDR1 genes.
     Our results demonstrate that VPA has potential to up-regulate CYP3A4 and
     MDR1 through direct activation of CAR and/or PXR pathways. Furthermore,
     we suggest that VPA synergistically augments the effect of rifampicin in
     transactivation of CYP3A4 in primary human hepatocytes.,
  DOI = 10.1124/dmd.106.014456,
  ISSN = 0090-9556,
  Unique-ID = ISI:000247373800004,
  

• Z. Dvorak, R. Vrzal, J. Ulrichova, D. Macejova, S. Ondkova, and J. Brtko, "Expression, protein stability and transcriptional activity of retinoic
  acid receptors are affected by microtubules interfering agents and
  all-traps-retinoic acid in primary rat hepatocytes," MOLECULAR AND CELLULAR ENDOCRINOLOGY, vol. 267, iss. 1-2, pp. 89-96, 2007.
  [Bibtex]

  @article ISI:000245429200011,
  Author = Dvorak, Zdenek and Vrzal, Radim and Ulrichova, Jitka and Macejova, Dana
     and Ondkova, Slavomira and Brtko, Julius,
  Title = Expression, protein stability and transcriptional activity of retinoic
     acid receptors are affected by microtubules interfering agents and
     all-traps-retinoic acid in primary rat hepatocytes,
  Journal = MOLECULAR AND CELLULAR ENDOCRINOLOGY,
  Year = 2007,
  Volume = 267,
  Number = 1-2,
  Pages = 89-96,
  Month = MAR 15,
  Abstract = Cellular signaling by glucocorticoid receptor and aryl hydrocarbon
     receptor is restricted by microtubules interfering agents (MIAs). This
     leads to down-regulation of drug metabolizing enzymes and drug
     interactions. Here we investigated the effects of all-traps-retinoic
     acid (ATRA) and MIAs, i.e. colchicine, nocodazole and taxol on the
     regulation of retinoic acid receptor (RAR) genes in primary cultures of
     rat hepatocytes. ATRA (1 mu M) down-regulated RAR alpha and RAR gamma
     mRNAs (decrease 23\% and 41\%, respectively) whereas it up-regulated
     RAR(3 mRNA (4.3-fold induction). All MIAs diminished the expression of
     RARs in dose-dependent manner; the potency of MIAs increased in order
     NOC < COL < TAX and the extent of inhibition increased in order RAR
     alpha < RAR gamma < RAR beta. The levels of RARa protein were decreased
     by both MIAs and ATRA. The effects of ATRA were reversed by proteasome
     inhibitor MG-132, implying ligand-dependent RARa degradation. In
     contrast, the effects of MIAs were proteasome-independent and decrease
     in RARa protein content was due to RARa gene down-regulation. We
     monitored transcriptional activity of RARa. For this purpose, we
     measured catalytic activity of traps-glutaminase-target gene of RAR
     alpha traps-Glutaminase activity was increased by ATRA (1.23-fold
     increase) and decreased by colchicine (decrease 51\%). Co-treatment with
     proteasome inhibitor MG-132 partly reversed inhibitory effect of
     colchicine, and it further augmented the increase of traps-glutaminase
     activity by ATRA. We have also observed decrease of RARa protein level
     and inhibition of RARs mRNAs expression in HeLa cells by MIAs. In
     conclusion, our data indicate that microtubules play the role in
     regulation of RARs activity and expression. Our data are the first
     report on the effects of ATRA and MIAs on RARs regulation in quiescent
     cells. (c) 2007 Elsevier Ireland Ltd. All rights reserved.,
  DOI = 10.1016/j.mce.2007.01.004,
  ISSN = 0303-7207,
  Unique-ID = ISI:000245429200011,
  

• Z. Dvorak, P. Maurel, M-J. Vilarem, J. Ulrichova, and M. Modriansky, "Expression and transcriptional activities of nuclear receptors involved
  in regulation of drug-metabolizing enzymes are not altered by
  colchiceine: Focus on PXR, CAR, and GR in primary human hepatocytes," CELL BIOLOGY AND TOXICOLOGY, vol. 23, iss. 2, pp. 63-73, 2007.
  [Bibtex]

  @article ISI:000243602400001,
  Author = Dvorak, Z. and Maurel, P. and Vilarem, M-J and Ulrichova, J. and
     Modriansky, M.,
  Title = Expression and transcriptional activities of nuclear receptors involved
     in regulation of drug-metabolizing enzymes are not altered by
     colchiceine: Focus on PXR, CAR, and GR in primary human hepatocytes,
  Journal = CELL BIOLOGY AND TOXICOLOGY,
  Year = 2007,
  Volume = 23,
  Number = 2,
  Pages = 63-73,
  Month = MAR,
  Abstract = Recent findings show that colchicine (COL) in submicromolar
     concentrations downregulates the expression of major drug-metabolizing
     P450 enzymes in human hepatocytes. Concomitantly, the expression of
     pregnane X receptor (PXR) and constitutive androstane receptor (CAR) was
     diminished by COL, whereas expression of glucocorticoid receptor (GR)
     remained unaltered. A tentative mechanism is perturbation of the
     GR-PXR/CAR-CYP2/3 signaling cascade, resulting in restricted
     transcriptional activity of GR receptor by colchicine. In this work we
     focused on 10-demethylcolchicine (colchiceine; EIN), a structural
     analogue and a putative metabolite of COL that lacks tubulin-binding
     activity. We investigated the effects of EIN on the expression of PXR,
     CAR, and GR receptors in primary cultures of human hepatocytes. In
     contrast with the effects of COL, EIN does not alter the expression of
     PXR, CAR, and/or GR receptors mRNAs. In addition, EIN had no effects on
     transcriptional activities of PXR, CAR, and GR receptors in reporter
     gene assays using transfected cell lines. Considering that COL and EIN
     are structurally very close and differ only in their tubulin-binding
     activity, the data presented imply that the deleterious effects of COL
     on the GR-PXR/CAR-CYP2/3 cascade are primarily due to perturbation of
     the microtubule network. Our data support the idea of replacing COL by
     EIN, which is less toxic and does not interact with xenoreceptors.,
  DOI = 10.1007/s10565-006-0127-8,
  ISSN = 0742-2091,
  Unique-ID = ISI:000243602400001,
  

• Z. Dvorak and V. Simanek, "Metabolism of sanguinarine: The facts and the myths," CURRENT DRUG METABOLISM, vol. 8, iss. 2, pp. 173-176, 2007.
  [Bibtex]

  @article ISI:000244702800006,
  Author = Dvorak, Z. and Simanek, V.,
  Title = Metabolism of sanguinarine: The facts and the myths,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2007,
  Volume = 8,
  Number = 2,
  Pages = 173-176,
  Month = FEB,
  Abstract = Sanguinarine, a quaternary benzo[c]phenanthridine alkaloid, exhibits
     antimicrobial and anti-inflammatory activities and for this reason it is
     used in dental hygiene products and feed additives. Its metabolism and
     disposition is the subject of constant scientific discourse. In this
     paper we summarize current knowledge on sanguinarine metabolism. We show
     in particular that: (i) Sanguinarine is not transformed to
     3,4-benzacridine and that the literature reporting this compound as a
     metabolite of sanguinarine is based on artifacts and misinterpretations
     that in course of time have created a dogma; (ii) Sanguinarine is
     converted to dihydrosanguinarine in vivo, the conversion being
     tentatively a detoxication pathway; (iii) Aryl hydrocarbon receptor
     metabolic signaling pathways modulate sanguinarine biological activity.,
  DOI = 10.2174/138920007779815959,
  ISSN = 1389-2002,
  Unique-ID = ISI:000244702800006,
  

• R. Vecera, B. Klejdus, P. Kosina, J. Orolin, M. Stiborova, S. Smrcek, J. Vicar, Z. Dvorak, J. Ulrichova, V. Kuba, P. Anzenbacher, and V. Simanek, "Disposition of sanguinarine in the rat," XENOBIOTICA, vol. 37, iss. 5, pp. 549-558, 2007.
  [Bibtex]

  @article ISI:000247065500007,
  Author = Vecera, R. and Klejdus, B. and Kosina, P. and Orolin, J. and Stiborova,
     M. and Smrcek, S. and Vicar, J. and Dvorak, Z. and Ulrichova, J. and
     Kuba, V. and Anzenbacher, P. and Simanek, V.,
  Title = Disposition of sanguinarine in the rat,
  Journal = XENOBIOTICA,
  Year = 2007,
  Volume = 37,
  Number = 5,
  Pages = 549-558,
  Abstract = Sanguinarine is an alkaloid with known antibiotic and anti-inflammatory
     activity and its pharmacokinetics have been studied in the rat after a
     single oral dose (10 mgkg(-1) body weight). Alkaloid determination in
     the plasma and liver was carried out by high- performance liquid
     chromatography - electrospray ionization mass spectrometry
     (HPLC/ESI-MS). The pharmacokinetic parameters (t(max), c(max), AUC(0 ->
     t) and AUC(0 -> 1)) were determined for sanguinarine and
     dihydrosanguinarine, the major components detected in plasma. The first
     step in sanguinarine metabolism in the rat was the reduction of the
     iminium bond resulting in formation of the less toxic
     dihydrosanguinarine. Both compounds were completely eliminated from the
     plasma and liver after 24 h and not detected in urine. After a single
     oral dose of H-3-sanguinarine, more than 42\% of the ingested
     radioactivity was present in gastrointestinal tract. Benz[c] acridine,
     up to date the only sanguinarine metabolite referred to in the
     literature, was not detected in the plasma, liver or urine.,
  DOI = 10.1080/00498250701230542,
  ISSN = 0049-8254,
  Unique-ID = ISI:000247065500007,
  

• B. Cvek and Z. Dvorak, "Targeting of nuclear Factor-kappa B and proteasome by dithiocarbamate
  complexes with metals," CURRENT PHARMACEUTICAL DESIGN, vol. 13, iss. 30, pp. 3155-3167, 2007.
  [Bibtex]

  @article ISI:000250570600010,
  Author = Cvek, B. and Dvorak, Z.,
  Title = Targeting of nuclear Factor-kappa B and proteasome by dithiocarbamate
     complexes with metals,
  Journal = CURRENT PHARMACEUTICAL DESIGN,
  Year = 2007,
  Volume = 13,
  Number = 30,
  Pages = 3155-3167,
  Abstract = Dithiocarbamates and their complexes with transition metals have been
     used as common pesticides, vulcanizing or analytical agents for decades.
     These compounds are one of the most reported inhibitors of nuclear
     factor-kappa B (NF-kappa B) signaling cascade. Recently, it has been
     found that dithiocarbamates are very potent inhibitors of proteasome.
     NF-kappa B plays a central role in the immune system and is described as
     major actor in many of human cancers mainly because of its protective
     effects against apoptosis. Molecular mechanisms involved in regulation
     and function of NF-kappa B pathway have been elucidated recently. In
     particular, pivotal zinc containing proteins that alter NF-kappa B
     signal transduction were recognized, Additionally, proteasome system was
     found to be a key player in NF-kappa B pathway and is an attractive
     target for anticancer drug development Collectively, the capability of
     dithiocarbamates to inhibit NF-kappa B and proteasome makes these
     compounds promising anticancer agents. This review focuses on the
     biological activity of dithiocarbamate coordination compounds with
     regard to their possible molecular targets in NF-kappa B signaling and
     proteasome (JAMM domain proteins). Future research should aim to find
     the most suitable dithiocarbamate coordination compounds for treatment
     of cancer and other diseases.,
  DOI = 10.2174/138161207782110390,
  ISSN = 1381-6128,
  Unique-ID = ISI:000250570600010,
  

2006

• Z. Dvorak, V. Kuban, B. Klejdus, J. Hlavac, J. Vicar, J. Ulrichova, and V. Simanek, "Quaternary benzo[c]phenanthridines sanguinarine and chelerythrine: A
  review of investigations from chemical and biological studies," HETEROCYCLES, vol. 68, iss. 11, pp. 2403-2422, 2006.
  [Bibtex]

  @article ISI:000242707500018,
  Author = Dvorak, Zdenek and Kuban, Vlastimil and Klejdus, Borivoj and Hlavac, Jan
     and Vicar, Jaroslav and Ulrichova, Jitka and Simanek, Vilim,
  Title = Quaternary benzo[c]phenanthridines sanguinarine and chelerythrine: A
     review of investigations from chemical and biological studies,
  Journal = HETEROCYCLES,
  Year = 2006,
  Volume = 68,
  Number = 11,
  Pages = 2403-2422,
  Month = NOV 1,
  Abstract = Sanguinarine and chelerythrine are intensively studied biologically
     active alkaloids for their potentially useful medicinal properties, such
     as antimicrobial, antiinflammatory, and antitumoral activities. This
     article aims to review critically recent literature published on the
     chemical behavior, synthesis, analytical methods and biotransformation
     of both alkaloids.,
  ISSN = 0385-5414,
  Unique-ID = ISI:000242707500018,
  

• M. Modriansky, J. Ulrichova, and Z. Dvorak, "Microtubules and commuting receptors," LETTERS IN DRUG DESIGN & DISCOVERY, vol. 3, iss. 8, pp. 567-568, 2006.
  [Bibtex]

  @article ISI:000240673200010,
  Author = Modriansky, M. and Ulrichova, J. and Dvorak, Z.,
  Title = Microtubules and commuting receptors,
  Journal = LETTERS IN DRUG DESIGN \& DISCOVERY,
  Year = 2006,
  Volume = 3,
  Number = 8,
  Pages = 567-568,
  Month = OCT,
  Abstract = Receptors that undergo nucleo-cytoplasmic shuttling require microtubules
     for proper physiologic function. Is it the collapse of microtubules
     network or simply the arrest of cell cycle in G2/M phase that changes
     receptors function? The terms of disengagement and the integrity versus
     dynamics of the microtubules shall guide the ideal drug design.,
  DOI = 10.2174/157018006778194718,
  ISSN = 1570-1808,
  Unique-ID = ISI:000240673200010,
  

• Z. Dvorak, A. Zdarilova, L. Sperlikova, E. Anzenbacherova, V. Simanek, and J. Ulrichova, "Cytotoxicity of sanguinarine in primary rat hepatocytes is attenuated by
  dioxin and phenobarbital," TOXICOLOGY LETTERS, vol. 165, iss. 3, pp. 282-288, 2006.
  [Bibtex]

  @article ISI:000239496200010,
  Author = Dvorak, Zdenek and Zdarilova, Adela and Sperlikova, Lucie and
     Anzenbacherova, Eva and Simanek, Vilim and Ulrichova, Jitka,
  Title = Cytotoxicity of sanguinarine in primary rat hepatocytes is attenuated by
     dioxin and phenobarbital,
  Journal = TOXICOLOGY LETTERS,
  Year = 2006,
  Volume = 165,
  Number = 3,
  Pages = 282-288,
  Month = SEP 10,
  Abstract = Putative interactions between quaternary benzo[c]phenanthridine
     alkaloid sanguinarine (SA) and aryl hydrocarbon receptor/cytochrome P450
     CYP1A (AhR/CYP1A) regulatory pathway are the subject of perpetual
     disputations. The role of CYP1A enzymes and AhR receptor in SA
     cytotoxicity was anticipated. In this paper, we tested, whether selected
     inducers of CYP enzymes modulate cytotoxicity of SA in primary cultures
     of rat hepatocytes. Cells were challenged 48 h with dioxin (TCDD; 5 nM),
     phenobarbital (PB; 500 mu M) or DMSO prior to the treatment with SA. SA
     itself displayed time- and dose-dependent cytotoxicity as revealed by
     lactate dehydrogenase leakage into the medium and MTT test.
     Pre-treatment of hepatocytes with TCDD and/or PB significantly
     attenuated SA cytotoxicity, the effects being more pronounced at lower
     concentrations of SA and shorter periods of incubation. We assumed
     involvement of CYP1A enzymes in diminution of SA cytotoxicity.
     Surprisingly, co-treatment with SA and furafylline, an inhibitor of
     CYP1A enzymes, further attenuated SA cytotoxicity instead of expected
     reversal of this effect. We conclude that TCDD- and PB-inducible genes
     attenuate cytotoxicity of SA in rat hepatocytes. CYP1A enzymes are not
     involved in this attenuation, but they rather augment SA cytotoxicity.
     Future research should focus on analyses of the involvement of other
     CYPs in SA cytotoxicity and on identification of TCDD-/PB-controlled
     genes responsible for observed phenomenon. (c) 2006 Elsevier Ireland
     Ltd. All rights reserved.,
  DOI = 10.1016/j.toxlet.2006.05.002,
  ISSN = 0378-4274,
  Unique-ID = ISI:000239496200010,
  

• Z. Dvorak, I. Sovadinova, L. Blaha, J. P. Giesy, and J. Ulrichova, "Quaternary benzo[c]phenathridine alkaloids sanguinarine and
  chelerythrine do not affect transcriptional activity of aryl hydrocarbon
  receptor: Analyses in rat hepatoma cell line H4IIE.luc," FOOD AND CHEMICAL TOXICOLOGY, vol. 44, iss. 9, pp. 1466-1473, 2006.
  [Bibtex]

  @article ISI:000240247100004,
  Author = Dvorak, Zdenek and Sovadinova, Iva and Blaha, Ludek and Giesy, John P.
     and Ulrichova, Jitka,
  Title = Quaternary benzo[c]phenathridine alkaloids sanguinarine and
     chelerythrine do not affect transcriptional activity of aryl hydrocarbon
     receptor: Analyses in rat hepatoma cell line H4IIE.luc,
  Journal = FOOD AND CHEMICAL TOXICOLOGY,
  Year = 2006,
  Volume = 44,
  Number = 9,
  Pages = 1466-1473,
  Month = SEP,
  Abstract = Quaternary benzo[c]phenanthridine alkaloids (QBAs) sanguinarine and
     chelerythrine exert a plethora of biological activities. Nevertheless,
     the specific cellular target for these alkaloids within the cell was not
     identified as far. Several literary data indicate that biological
     effects of QBAs could be associated with aryl hydrocarbon receptor (AhR)
     signaling pathway, including cytochrome P450 CYP1A, however, available
     information are controversial. In this work we analyzed the effects of
     sanguinarine and chelerythrine on AhR activity in rat hepatoma cells
     HII4E.luc stably transfected with dioxin responsive element fused to
     luciferase gene (DRE-LUC). Studied QBAs were tested in submicromolar
     concentration range (0.0001-1 mu M) and in incubation times 6, 24 and 48
     h. Transcriptional activity of AhR was monitored by chemiluminiscence
     measurement of luciferase catalytic activity. Sanguinarine and
     chelerythrine did not activated AhR in any time or dose tested.
     Chelerythrine (1 mu M) but not sanguinarine caused moderate inhibition
     of AhR activation by 10 picomolar dioxin (exponential phase of receptor
     activation). In contrast, AhR activation by 2.5 nM dioxin (saturated
     receptor) was not affected by either alkaloid tested. In conclusion, the
     findings presented here favor rather for inactivity or modest inhibitory
     effect of QBAs on AhR signaling pathways in vitro than for the
     activation of the receptor. Regarding the concentrations of QBAs
     occurring in vivo, the use of products containing sanguinarine and/or
     chelerythrine has low toxicological potential in terms of the
     interactions with AhR signaling pathways. (c) 2006 Elsevier Ltd. All
     rights reserved.,
  DOI = 10.1016/j.fct.2006.04.016,
  ISSN = 0278-6915,
  Unique-ID = ISI:000240247100004,
  

• Z. Dvorak, R. Vrzal, J. Ulrichova, J. Pascussi, P. Maurel, and M. Modriansky, "Involvement of cytoskeleton in AhR-dependent CYP1A1 expression," CURRENT DRUG METABOLISM, vol. 7, iss. 3, pp. 301-313, 2006.
  [Bibtex]

  @article ISI:000236692000007,
  Author = Dvorak, Z and Vrzal, R and Ulrichova, J and Pascussi, JM and Maurel, P
     and Modriansky, M,
  Title = Involvement of cytoskeleton in AhR-dependent CYP1A1 expression,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2006,
  Volume = 7,
  Number = 3,
  Pages = 301-313,
  Month = APR,
  Abstract = Cytochrome P450 (CYP) 1A1 attracts attention mainly because of its role
     in production of carcinogenic reactive metabolites from polycyclic
     aromatic hydrocarbons such as benzo[a]pyrene, but recent developments
     indicate its apparent role in cell cycle progression. Expression of the
     enzyme is subject to regulation by aryl hydrocarbon receptor (AhR). It
     has been shown that induction of CYP1A1ak4 in HepG2 cells and primary
     rat hepatocytes by tetrachloro-p-dibenzodioxin (TCDD) is diminished by
     colchicine and nocodazole. Both compounds decrease CYP1A1 mRNA, protein,
     and activity levels in HepG2 cells and mRNA level in primary rat
     hepatocytes. Neither compound significantly affected [H-3]-TCDD
     binding to AhR, thus their effect on AhR transcriptional activity
     proceeds via indirect means. For colchicine and nocodazole are
     well-known microtubule interfering agents, we also assessed their effect
     on microtubule integrity in both cell types under investigation. Both
     compounds disrupt cytoskeleton integrity with differential potency
     depending on cell type. The observed suppression of AhR transcriptional
     activity by colchicine and nocodazole can be associated with G2/M cell
     cycle arrest in HepG2 cells, as demonstrated by Myt1 protein
     hyperphosphorylation and FACS analysis. However, in primary rat
     hepatocytes, cytoskeleton disruption is independent of cell cycle while
     displaying the same influence on AhR-dependent gene transcription. In
     our view, this is evidence in favor of modulatory role of cytoskeleton
     in AhR-dependent expression.,
  DOI = 10.2174/138920006776359310,
  ISSN = 1389-2002,
  Unique-ID = ISI:000236692000007,
  

• Z. Dvorak, R. Vrzal, and J. Ulrichova, "Silybin and dehydrosilybin inhibit cytochrome P450 1A1 catalytic
  activity: A study in human keratinocytes and human hepatoma cells," CELL BIOLOGY AND TOXICOLOGY, vol. 22, iss. 2, pp. 81-90, 2006.
  [Bibtex]

  @article ISI:000235928200002,
  Author = Dvorak, Z and Vrzal, R and Ulrichova, J,
  Title = Silybin and dehydrosilybin inhibit cytochrome P450 1A1 catalytic
     activity: A study in human keratinocytes and human hepatoma cells,
  Journal = CELL BIOLOGY AND TOXICOLOGY,
  Year = 2006,
  Volume = 22,
  Number = 2,
  Pages = 81-90,
  Month = MAR,
  Abstract = The flavonolignan silybin and its derivative dehydrosilybin have been
     proposed as candidate UV-protective agents in skin care products. This
     study addressed the effect of silybin and dehydrosilybin on the activity
     of cytochrome P450 isoform CYP1A1 in human keratinocytes (HaCaT) and
     human hepatoma cells (HepG2). CYP1A1 catalytic activity was assessed as
     O-deethylation of 7-ethoxyresorufin using fluorescence detection.
     Silybin and dehydrosylibin inhibited basal and dioxin-inducible CYP1A1
     catalytic activity in both cell lines used. The inhibitory effect of
     tested compounds was more pronounced in HaCaT cells than in HepG2 cells,
     and dehydrosilybin was a much stronger inhibitor than silybin. Analyses
     on CYP1A1 human recombinant protein yielded IC50 values of 22.9 +/- 4.7
     mu mol/L and 0.43 +/- 0.04 mu mol/L for silybin and dehydrosilybin,
     respectively. Since CYP1A enzymes are some of the most prominent actors
     in the process of chemically induced carcinogenesis, the inhibitory
     activity of the flavonolignans tested against CYP1A1 favors their use as
     cytoprotective agents in terms of skin and hepatic metabolism. In
     addition, the capability of dehydrosilybin to inhibit CYP1A1 in
     submicromolar concentrations makes this compound a potential biological
     probe in CYP1A1 analyses.,
  DOI = 10.1007/s10565-006-0017-0,
  ISSN = 0742-2091,
  Unique-ID = ISI:000235928200002,
  

• A. Zdarilova, R. Vrzal, M. Rypka, J. Ulrichova, and Z. Dvorak, "Investigation of sanguinarine and chelerythrine effects on CYP1A1
  expression and activity in human hepatoma cells," FOOD AND CHEMICAL TOXICOLOGY, vol. 44, iss. 2, pp. 242-249, 2006.
  [Bibtex]

  @article ISI:000235599800011,
  Author = Zdarilova, A and Vrzal, R and Rypka, M and Ulrichova, J and Dvorak, Z,
  Title = Investigation of sanguinarine and chelerythrine effects on CYP1A1
     expression and activity in human hepatoma cells,
  Journal = FOOD AND CHEMICAL TOXICOLOGY,
  Year = 2006,
  Volume = 44,
  Number = 2,
  Pages = 242-249,
  Month = FEB,
  Abstract = Quaternary benzo[c]phenanthridine alkaloids (QBA) sanguinarine and
     chelerythrine exhibit a wide spectrum of biological activities whence
     they are used in dental care products. Recent studies indicated that
     cytochrome P450 CYP1A attenuates sanguinarine toxicity both in vivo
     [Williams, M.K., Dalvi, S., Dalvi, R.R., 2000. Influence of
     3-methylcholanthrene pretreatment on sanguinarine toxicity in mice. Vet.
     Hum. Toxicol. 42, 196-198] and in vitro [Vrba, J., Kosina, P.,
     Ulrichov, J., Modriansk, M., 2004. Involvement of cytochrome P450 1A in
     sanguinarine detoxication. Toxicol. Lett. 151, 375-387]. However, CYP1A
     converts sanguinarine to the products that form DNA adducts
     [Stiborova, M., Simanek, V., Frei, E., Hobza, P., Ulrichova, J., 2002.
     DNA adduct formation from quaternary benzo[e]phenanthridine alkaloids
     sanguinarine and chelerythrine as revealed by the 32P-postlabeling
     technique. Chem. Biol. Interact. 140, 231-242]. In our work we examined
     the effects of sanguinarine and chelerythrine on CYP1A1 expression and
     catalytic activity in human hepatoma cells-HepG2. Sanguinarine and
     chelerythrine did not affect basal and dioxin-inducible expression of
     CYP1A1 mRNA and protein in HepG2 cells. The enzymatic activity of CYP1A1
     was assessed by the fluorescent measurement of
     7-ethyxoresorufin-O-deethylase (EROD) activity. We observed a slight
     decrease of dioxin-induced EROD activity in HepG2 cells by sanguinarine
     and chelerythrine. This decrease was attributed to the inhibition of
     CYP1A1 catalytic activity, as revealed by enzyme kinetic studies on
     recombinant CYP1A1 protein. The IC50 values for the inhibition of CYP1A1
     by sanguinarine and chelerythrine were 2.1 and 1.9 mu M, respectively.
     In conclusion, albeit the CYP1A1 modulates QBA cytotoxicity and
     genotoxicity, the QBA themselves do not affect CYP1A1 expression. The
     data indicate that studied alkaloids do not have specific cellular
     target and their biological effects are rather pleiotropic. (c) 2005
     Elsevier Ltd. All rights reserved.,
  DOI = 10.1016/j.fct.2005.07.006,
  ISSN = 0278-6915,
  Unique-ID = ISI:000235599800011,
  

• Z. Dvorak, R. Vrzal, P. Maurel, and J. Ulrichova, "Differential effects of selected natural compounds with
  anti-inflammatory activity on the glucocorticoid receptor and NF-kappa B
  in HeLa cells," CHEMICO-BIOLOGICAL INTERACTIONS, vol. 159, iss. 2, pp. 117-128, 2006.
  [Bibtex]

  @article ISI:000235016900004,
  Author = Dvorak, Z and Vrzal, R and Maurel, P and Ulrichova, J,
  Title = Differential effects of selected natural compounds with
     anti-inflammatory activity on the glucocorticoid receptor and NF-kappa B
     in HeLa cells,
  Journal = CHEMICO-BIOLOGICAL INTERACTIONS,
  Year = 2006,
  Volume = 159,
  Number = 2,
  Pages = 117-128,
  Month = FEB 1,
  Abstract = Natural compounds have been used in the treatment of various diseases
     for centuries. Herein, we investigated the effects of structurally
     diverse alkaloids with anti-inflammatory activity (berberine,
     sanguinarine, chelerythrine, and colchicine) on two important
     anti-inflammatory and pro-inflammatory players, i.e. glucocorticoid
     receptor (GR) and nuclear factor kappa B (NF-kappa B), respectively.
     Sanguinarine and chelerythrine elicited nuclear translocation of the p65
     subunit of NF-kappa B. The nuclear import of p65 was strongly augmented
     by these akaloids in non-stimulated cells as well as in cells challenged
     with tumor necrosis factor alpha (TNF alpha). Colchicine and berberine
     had no effect on p65 nuclear translocation regardless of the presence or
     absence of TNF alpha. Colchicine caused rapid degradation of the GR
     protein, whereas berberine had no effect on GR content or cellular
     localization. Sanguinarine and chelerythrine induced accumulation of GR
     in the nucleus with concomitant diminution of cytosolic GR. Analyses on
     the. transcriptional activity of GR and NF-kappa B monitored by reporter
     assays using HeLa cells transiently transfected with glucocorticoid
     response element (pGRE-LUC) and/or NF-kappa B elements fused to
     luciferase gene (pNF-kappaB-luc) showed that none of the compounds
     tested had the capability to trigger GR and/or NF-kappa B
     transcriptional activities, respectively. The ligand binding assay
     showed that colchicine and berberine are not GR ligands whereas
     sanguinarine and chelerythrine significantly decreased binding of
     H-3-labelled dexamethasone to GR. In conclusion, structurally diverse
     natural antiflogistics displayed differential effects on GR and NF-kappa
     B in HeLa cells. (c) 2005 Elsevier Ireland Ltd. All rights reserved.,
  DOI = 10.1016/j.cbi.2005.10.105,
  ISSN = 0009-2797,
  Unique-ID = ISI:000235016900004,
  

• A. Zdarilova, J. Malikova, Z. Dvorak, J. Ulrichova, and V. Simanek, "Quaternary isoquinoline alkaloids sanguinarine and chelerythrine. In
  vitro and in vivo effects," CHEMICKE LISTY, vol. 100, iss. 1, pp. 30-41, 2006.
  [Bibtex]

  @article ISI:000234992900006,
  Author = Zdarilova, A and Malikova, J and Dvorak, Z and Ulrichova, J and Simanek,
     V,
  Title = Quaternary isoquinoline alkaloids sanguinarine and chelerythrine. In
     vitro and in vivo effects,
  Journal = CHEMICKE LISTY,
  Year = 2006,
  Volume = 100,
  Number = 1,
  Pages = 30-41,
  Abstract = Quaternary benzo[c]phenanthridine alkaloids (QBA) sanguinarine (SA)
     and chelerythrine (CHE) are found within the families Fumariaceae,
     Papaveraceae, Ranunculaceae and Rutaceae. These alkaloids originate from
     aromatic amino acids tyrosine and phenylalanine. Important intermediates
     in their biosynthesis are protopines; its last step is the oxidation of
     dihydro-QBA to QBA with benzo [c]phenanthridine oxidase. The strong
     antimicrobial activity of QBA suggests their function as plant defense
     secondary metabolites or phytoalexins. If these alkaloids are
     administered to living organisms such as insects, fish, and mammalian
     species, they can be absorbed, distributed, retained and/or metabolized
     as quaternary ammonium compounds, 6-hydroxy dihydro derivatives
     (pseudobases) and/or dihydro derivatives. In blood and organs, the
     equilibrium between these forms depends mainly on pH, ionic strength and
     oxidative capacity of the medium. Their resulting mode of action
     reflects the sum of reactions of all three chemical structures with
     cellular components. The formation of dihydro-QBA might be the first
     step of their detoxication in organism and their subsequent elimination.
     Benzo[c]acridine is not a metabolite of QBA in mammals. This review
     presents the resulting biological effects of QBA on cells and animals.,
  ISSN = 0009-2770,
  Unique-ID = ISI:000234992900006,
  

2005

• Z. Dvorak, J. Ulrichova, and M. Modriansky, "Role of microtubules network in CYP genes expression," CURRENT DRUG METABOLISM, vol. 6, iss. 6, pp. 545-552, 2005.
  [Bibtex]

  @article ISI:000233385100003,
  Author = Dvorak, Z and Ulrichova, J and Modriansky, M,
  Title = Role of microtubules network in CYP genes expression,
  Journal = CURRENT DRUG METABOLISM,
  Year = 2005,
  Volume = 6,
  Number = 6,
  Pages = 545-552,
  Month = DEC,
  Abstract = Superfamily of cytochrome P450 enzymes (CYPs), a distinctive enzyme
     system by which human body defends itself against toxic compounds, is
     the subject of a complex regulation process involving various
     mechanisms, on the levels of expression and activity. Apart from
     physiological factors, several patho-physiological ones such as
     inflammation, infection, and stress affect CYP expression. The aim of
     this review is to summarize the current knowledge on the role of
     microtubules network in the regulation of drug metabolizing CYPs.
     Experiments on human and animal cell models revealed that microtubules
     disruption severely impaired basal and inducible expression of human CYP
     1A1, 2B6, 2C8, 2C9, 2C19, and 3A4, and rat CYP 1A2, 2B1, 2B2, and 3A23.
     Inhibition of aryl hydrocarbon receptor (AhR) and glucocorticoid
     receptor (GR) transcriptional activity by microtubules disarray was
     found to be responsible for the suppressed CYP enzymes expression.
     However the mechanism by which microtubules interfering agents (MIAs)
     inhibit GR and AhR transcriptional activities is not fully understood
     yet. Several lines of evidence indicate that: i) the cell cycle, G2/M
     phase in particular, has an influence on AhR and GR transcriptional
     activity, and ii) MIAs negatively modulate GR transcriptional activity
     via the activation of c-Jun-N-terminal kinase. In conclusion,
     down-regulation of major CYP enzymes by microtubules disarray is
     intriguing from the mechanistic point of view and in relation to the
     cell differentiation.,
  DOI = 10.2174/138920005774832623,
  ISSN = 1389-2002,
  Unique-ID = ISI:000233385100003,
  

• R. Vrzal, A. Zdarilova, J. Ulrichova, L. Blaha, J. Giesy, and Z. Dvorak, "Activation of the aryl hydrocarbon receptor by berberine in HepG2 and
  H4IIE cells: Biphasic effect on CYP1A1," BIOCHEMICAL PHARMACOLOGY, vol. 70, iss. 6, pp. 925-936, 2005.
  [Bibtex]

  @article ISI:000231663100013,
  Author = Vrzal, R and Zdarilova, A and Ulrichova, J and Blaha, L and Giesy, JP
     and Dvorak, Z,
  Title = Activation of the aryl hydrocarbon receptor by berberine in HepG2 and
     H4IIE cells: Biphasic effect on CYP1A1,
  Journal = BIOCHEMICAL PHARMACOLOGY,
  Year = 2005,
  Volume = 70,
  Number = 6,
  Pages = 925-936,
  Month = SEP 15,
  Abstract = Berberine has long been considered a candidate for an antimalarial drug.
     It exerts a plethora of biological activities and has been used in the
     treatment of diarrhea and gastro-enteritis for centuries. Here we
     provide evidence that berberine activates the aryl hydrocarbon receptor
     (AhR) in human hepatoma (HepG2) and rat hepatoma cells stably
     transfected with a dioxin responsive element fused to the luciferase
     gene (H4IIE.luc). AhR was activated by high doses of berberine (10-50 mu
     M) after 6 and 24 h of incubation as revealed by CYP1A1 mRNA expression
     (HepG2) and AhR-dependent luciferase activity (H411E.luc). Berberine
     induced nuclear translocation of AhR-GFP chimera transiently transfected
     to Hcpa1c1c7 cells. In contrast, low doses of berberine (< 1 mu M) and
     prolonged times of the treatments (48 h) failed to produce any
     activation of AhR in H4IIE.luc cell line. HPLC analysis ruled out the
     hypothesis that the loss of berberine capacity to activate AhR in
     H411E.luc cells is due to metabolic inactivation of the alkaloid. We
     demonstrate that berberine is a potent inhibitor (IC50 = 2.5 mu M) of
     CYP1A1 catalytic activity (EROD) in HepG2 cell culture and in
     recombinant CYP1A1 protein. Collectively, our results imply that while
     berberine activates the Ah receptor, it is accompanied by inactivation
     of the catalytic activity of CYP1A1 and occurs at concentrations that
     exceed those predicted to occur in vivo. Given these data, it appears
     that activation of the AhR pathway by berberine has a low toxicological
     potential. (c) 2005 Published by Elsevier Inc.,
  DOI = 10.1016/j.bcp.2005.06.016,
  ISSN = 0006-2952,
  Unique-ID = ISI:000231663100013,
  

• Z. Dvorak, M. Modriansky, V. Simanek, J. Ulrichova, J. Vicar, J. Vrba, and D. Walterova, "Sanguinarine activates polycyclic aromatic hydrocarbon associated
  metabolic pathways in human oral keratinocytes and tissues," TOXICOLOGY LETTERS, vol. 158, iss. 2, pp. 164-165, 2005.
  [Bibtex]

  @article ISI:000231343300010,
  Author = Dvorak, Z and Modriansky, M and Simanek, V and Ulrichova, J and Vicar, J
     and Vrba, J and Walterova, D,
  Title = Sanguinarine activates polycyclic aromatic hydrocarbon associated
     metabolic pathways in human oral keratinocytes and tissues,
  Journal = TOXICOLOGY LETTERS,
  Year = 2005,
  Volume = 158,
  Number = 2,
  Pages = 164-165,
  Month = AUG 14,
  DOI = 10.1016/j.toxlet.2005.05.010,
  ISSN = 0378-4274,
  Unique-ID = ISI:000231343300010,
  

• Z. Dvorak, M. Modriansky, J. Ulrichova, P. Maurel, M. Vilarem, and J. Pascussi, "Disruption of microtubules leads to glucocorticoid receptor degradation
  in HeLa cell line," CELLULAR SIGNALLING, vol. 17, iss. 2, pp. 187-196, 2005.
  [Bibtex]

  @article ISI:000224930000006,
  Author = Dvorak, Z and Modriansky, M and Ulrichova, J and Maurel, P and Vilarem,
     MP and Pascussi, JM,
  Title = Disruption of microtubules leads to glucocorticoid receptor degradation
     in HeLa cell line,
  Journal = CELLULAR SIGNALLING,
  Year = 2005,
  Volume = 17,
  Number = 2,
  Pages = 187-196,
  Month = FEB,
  Abstract = The role of microtubules (MTs) in steroid hormone-dependent human
     glucocorticoid receptor (hGR) activation/translocation is controversial.
     It was demonstrated recently that colchicine (COL) down-regulates
     hGR-driven genes in primary human hepatocytes by a mechanism involving
     inhibition of hGR translocation to the nucleus. To investigate whether
     inhibition of hGR translocation is the sole reason for its inactivation,
     we used human cervical carcinoma cells (HeLa) as a model. Herein we
     present evidence that perturbation of microtubules in HeLa cells leads
     to rapid time-and dose-dependent degradation of hGR protein. Degradation
     is proteasome mediated as revealed by its reversibility, by proteasome
     inhibitor MG132. Moreover, degradation was observed for neither wt-hGR
     nor hGR mutants S226A and K419A in transiently transfected COS-I cells.
     On the other hand, c-jun N-terminal kinase (JNK) seems not to be
     involved in the process because JNK inhibitor 1,9-Pyrazoloanthrone
     (SP600125) does not reverse hGR degradation. Similarly, another hGR
     functional antagonist, nuclear factor kappa beta (NFkappaB), did not
     play any role in the degradation process. (C) 2004 Elsevier Inc. All
     rights reserved.,
  DOI = 10.1016/j.cellsig.2004.06.010,
  ISSN = 0898-6568,
  Unique-ID = ISI:000224930000006,
  

• R. Vrzal, A. Zdarilova, J. Ulrichova, and Z. Dvorak, "Short term effect of berberine on AhR transcriptional activity," DRUG METABOLISM REVIEWS, vol. 37, iss. 1, pp. 159, 2005.
  [Bibtex]

  @article ISI:000232535400159,
  Author = Vrzal, R and Zdarilova, A and Ulrichova, J and Dvorak, Z,
  Title = Short term effect of berberine on AhR transcriptional activity,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2005,
  Volume = 37,
  Number = 1,
  Pages = 159,
  Note = 9th European ISSX Meeting, Nice, FRANCE, JUN 12-17, 2005,
  ISSN = 0360-2532,
  Unique-ID = ISI:000232535400159,
  

• P. Kosina, P. Maurel, J. Ulrichova, and Z. Dvorak, "Effect of silybin and its glycosides on the expression of cytochromes
  p450 1A2 and 3A4 in primary cultures of human hepatocytes," JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, vol. 19, iss. 3, pp. 149-153, 2005.
  [Bibtex]

  @article ISI:000230354300002,
  Author = Kosina, P and Maurel, P and Ulrichova, J and Dvorak, Z,
  Title = Effect of silybin and its glycosides on the expression of cytochromes
     p450 1A2 and 3A4 in primary cultures of human hepatocytes,
  Journal = JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY,
  Year = 2005,
  Volume = 19,
  Number = 3,
  Pages = 149-153,
  Abstract = Four beta-glycosides of flavonoligan silybin, i.e. silybin
     beta-galactoside, silybin beta-glucoside, silybin beta-maltoside, and
     silybin beta-lactoside were synthesized in order to improve silybin
     water solubility and bioavailability (Kren et al., J Chem Soc, Perkin
     Trans 1, 2467-2474,1997). The presented paper deals with the effect of
     silybin and its synthetic beta-glycosides on the expression of two major
     cytochrome P450 isoforms, CYP1A2 and CYP3A4. Primary cultures of human
     hepatocytes were the model of choice. mRNAs were analyzed using Northern
     blot and P-32-radiolabelled probes. CYP protein content was determined
     by immunoblotting using specific antibodies. Silybin and its
     beta-glycosides do not induce expression of CYP1A2 and CYP3A4. Tested
     compounds did not affect inducible expression of CYP1A2 and CYP3A4 by
     dioxin and rifampicin, respectively, as evaluated at the level of mRNAs
     and proteins. Silybin and its P-glycosides do not interfere with the
     expression of CYP1A2 and CYP3A4, and are not likely to produce drug-drug
     interactions in terms of the inducibility of two important cytochromes
     P450. (c) 2005 Wiley Periodicals, Inc.,
  DOI = 10.1002/jbt.20066,
  ISSN = 1095-6670,
  Unique-ID = ISI:000230354300002,
  

2004

• Z. Dvorak, M. Modriansky, J. Ulrichova, and P. Maurel, "Speculations on the role of the microtubule network in glucocorticoid
  receptor signaling," CELL BIOLOGY AND TOXICOLOGY, vol. 20, iss. 6, pp. 333-343, 2004.
  [Bibtex]

  @article ISI:000228876200002,
  Author = Dvorak, Z and Modriansky, M and Ulrichova, J and Maurel, P,
  Title = Speculations on the role of the microtubule network in glucocorticoid
     receptor signaling,
  Journal = CELL BIOLOGY AND TOXICOLOGY,
  Year = 2004,
  Volume = 20,
  Number = 6,
  Pages = 333-343,
  Month = NOV,
  Abstract = The glucocorticoid receptor (GR) is an important player in the life of a
     cell. This is underlined by a cohort of protein and nucleic acid
     structures interacting with the GR. Among many issues surrounding GR
     activity that are under active investigation, the role of microtubules
     (MTs) is still unclear. This article aims to evaluate the ayes and noes
     in favor of microtubule importance and then form a hypothesis on their
     function in GR activity.,
  DOI = 10.1007/s10565-004-0088-8,
  ISSN = 0742-2091,
  Unique-ID = ISI:000228876200002,
  

• Z. Dvorak, M. Modriansky, P. Maurel, J. Pascussi, and J. Ulrichova, "Anti-glucocorticoid behavior of anti-inflammatory drug colchicine: a
  paradoxical phenomenon at molecular level," TOXICOLOGY AND APPLIED PHARMACOLOGY, vol. 197, iss. 3, pp. 887, 2004.
  [Bibtex]

  @article ISI:000222348900819,
  Author = Dvorak, Z and Modriansky, M and Maurel, P and Pascussi, JM and
     Ulrichova, J,
  Title = Anti-glucocorticoid behavior of anti-inflammatory drug colchicine: a
     paradoxical phenomenon at molecular level,
  Journal = TOXICOLOGY AND APPLIED PHARMACOLOGY,
  Year = 2004,
  Volume = 197,
  Number = 3,
  Pages = 887,
  Month = JUN 15,
  Note = 10th International Congress of Toxicology, Tampere, FINLAND, JUL 11-15,
     2004,
  ISSN = 0041-008X,
  Unique-ID = ISI:000222348900819,
  

2003

• Z. Dvorak, M. Modriansky, L. Pichard-Garcia, P. Balaguer, M. Vilarem, J. Ulrichova, P. Maurel, and J. Pascussi, "Colchicine down-regulates cytochrome P4502B6, 2C8, 2C9, and 3A4 in human
  hepatocytes by affecting their glucocorticoid receptor-mediated
  regulation," MOLECULAR PHARMACOLOGY, vol. 64, iss. 1, pp. 160-169, 2003.
  [Bibtex]

  @article ISI:000183613100019,
  Author = Dvorak, Z and Modriansky, M and Pichard-Garcia, L and Balaguer, P and
     Vilarem, MJ and Ulrichova, J and Maurel, P and Pascussi, JM,
  Title = Colchicine down-regulates cytochrome P4502B6, 2C8, 2C9, and 3A4 in human
     hepatocytes by affecting their glucocorticoid receptor-mediated
     regulation,
  Journal = MOLECULAR PHARMACOLOGY,
  Year = 2003,
  Volume = 64,
  Number = 1,
  Pages = 160-169,
  Month = JUL,
  Abstract = The xenobiotic-mediated induction of three major human liver cytochrome
     P450 genes, CYP2B6, CYP2C9, and CYP3A4, is known to be regulated by the
     constitutive androstane receptor ( CAR) and the pregnane X receptor
     (PXR). CAR and PXR are regulated, at least in part, by the
     glucocorticoid receptor (GR) and the hypothesis of a signal transduction
     cascade GR-[CAR/PXR]P450 has been proposed. This study was aimed at
     testing this hypothesis in primary human hepatocytes by using the
     tubulin network disrupting agent colchicine. Colchicine ( COL) decreased
     both basal and rifampicin- and phenobarbital-inducible expression of
     CYP2B6, CYP2C8/9, and CYP3A4. A parallel down-regulation of mRNA
     expression of CAR, PXR, and tyrosine aminotransferase, a prototypic gene
     directly regulated by GR, was observed. COL affected neither the level
     of GR mRNA nor ligand binding to GR. To evaluate the effect of
     colchicine on GR-mediated gene transactivation, HeLa cells stably or
     transiently transfected with a GR-responsive element-dependent
     luciferase reporter gene were used. COL decreased the dexamethasone-
     induced luciferase expression in stably transfected cell line by 50\%,
     whereas GR transactivation in transiently transfected cells was not
     affected by COL. In contrast, ligand-dependent GR translocation in the
     human embryonic kidney 293 cell line transiently transfected with GFP-GR
     was inhibited by COL. We conclude that alteration of the signal
     transduction mediated through the GR-[CAR/PXR]-P450 cascade by
     colchicine is responsible for the down-regulation of CYP2C9 and CYP3A4,
     implicating cytoskeleton as necessary for correct functioning of this
     cascade under physiological conditions.,
  DOI = 10.1124/mol.64.1.160,
  ISSN = 0026-895X,
  Unique-ID = ISI:000183613100019,
  

• Z. Dvorak, P. Kosina, D. Walterova, V. Simanek, P. Bachleda, and J. Ulrichova, "Primary cultures of human hepatocytes as a tool in cytotoxicity studies:
  cell protection against model toxins by flavonolignans obtained from
  Silybum marianum," TOXICOLOGY LETTERS, vol. 137, iss. 3, pp. 201-212, 2003.
  [Bibtex]

  @article ISI:000180833600009,
  Author = Dvorak, Z and Kosina, P and Walterova, D and Simanek, V and Bachleda, P
     and Ulrichova, J,
  Title = Primary cultures of human hepatocytes as a tool in cytotoxicity studies:
     cell protection against model toxins by flavonolignans obtained from
     Silybum marianum,
  Journal = TOXICOLOGY LETTERS,
  Year = 2003,
  Volume = 137,
  Number = 3,
  Pages = 201-212,
  Month = FEB 3,
  Abstract = The aim of this study was to evaluate the cytoprotective effects upon
     primary human hepatocytes of silymarin extract and its main
     flavonolignans following exposure to the cytotoxic actions of model
     toxins. The conditions for the hepatocyte intoxication were optimised
     for allyl alcohol, carbon tetrachloride, D-galactosamine and
     paracetamol. Silymarin extract, silychristin and silydianin did not
     exert cytotoxicity (10-100 muM), whereas silybin and isosilybin at
     higher concentrations and after longer incubation periods were
     cytotoxic. All main flavonolignans of silymarin tested displayed
     concentration-dependent cytoprotection against the toxic effects of both
     allyl alcohol and carbon tetrachloride but neither paracetamol nor
     galactosamine. The best protection was achieved by silydianin and
     silychristin and to a lesser degree by silymarin, while silybin and
     isosilybin were less effective. It is concluded that these differing
     outcomes result from the varying abilities of the Silybum marianum
     substances tested to stabilize the cell membrane, exert antioxidant
     properties and exhibit intrinsic toxicity. (C) 2002 Elsevier Science
     Ireland Ltd. All rights reserved.,
  ISSN = 0378-4274,
  Unique-ID = ISI:000180833600009,
  

• Z. Dvorak, M. Modriansky, J. Pascussi, P. Balaguer, J. Ulrichova, and P. Maurel, "Cytoskeleton dependency of glucocorticoid receptor regulated cytochrome
  P450 expression: Differential effect of colchicine and nocodazole," DRUG METABOLISM REVIEWS, vol. 35, iss. 1, pp. 294, 2003.
  [Bibtex]

  @article ISI:000182128400291,
  Author = Dvorak, Z and Modriansky, M and Pascussi, JM and Balaguer, P and
     Ulrichova, J and Maurel, P,
  Title = Cytoskeleton dependency of glucocorticoid receptor regulated cytochrome
     P450 expression: Differential effect of colchicine and nocodazole,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2003,
  Volume = 35,
  Number = 1,
  Pages = 294,
  Note = 8th European Meeting of the
     International-Society-for-the-Study-of-Xenobiotics (ISSX), DIJON,
     FRANCE, APR 27-MAY 01, 2003,
  Organization = Int Soc Study Xenobiotics,
  ISSN = 0360-2532,
  Unique-ID = ISI:000182128400291,
  

• J. Pascussi, Z. Dvorak, S. Gerbal-Chaloin, E. Assenat, P. Maurel, and M. Vilarem, "Pathophysiological factors affecting CAR gene expression," DRUG METABOLISM REVIEWS, vol. 35, iss. 4, pp. 255-268, 2003.
  [Bibtex]

  @article ISI:000187608800001,
  Author = Pascussi, JM and Dvorak, Z and Gerbal-Chaloin, S and Assenat, E and
     Maurel, P and Vilarem, MJ,
  Title = Pathophysiological factors affecting CAR gene expression,
  Journal = DRUG METABOLISM REVIEWS,
  Year = 2003,
  Volume = 35,
  Number = 4,
  Pages = 255-268,
  Note = 8th European ISSX Meeting, DIJON, FRANCE, APR 27-MAY 01, 2003,
  Abstract = The body defends itself against potentially harmful compounds, such as
     drugs and toxic endogenous compounds and their metabolites, by inducing
     the expression of enzymes and transporters involved in their metabolism
     and elimination. The orphan nuclear receptor CAR (NR113 controls phase I
     (CYP2B, CYP2C, CYP3A), phase 11 (UGT1A1), and transporter (SLC21A6,
     MRP2) genes involved in drug metabolism and bilirubin clearance.
     Constitutive androstane receptor (CAR) is activated by xenobiotics, such
     as phenobarbital, but also by toxic endogenous compounds such as
     bilirubin metabolite(s). To better understand the inter- and
     intravariability in drug detoxification, we studied the molecular
     mechanisms involved in CAR gene expression in human hepatocytes. We
     clearly identified CAR as a glucocorticoid receptor (GR) target gene,
     and we proposed the hypothesis of a signal transduction where the
     activation of GR plays a critical function in CAR-mediated cellular
     response. According to our model, chemicals or pathophysiological
     factors that affect GR function should decrease CAR function. To test
     this hypothesis, we recently investigated the effect of microtubule
     disrupting agents (MIAs) or proinflammatory cytokines. These compounds
     are well-known inhibitors of GR transactivation property. MIAs activate
     c-Jun N-terminal kinase (JNK), which phosphorylates and inactivates GR,
     whereas proinflammatory cytokines, such as IL-6 or IL1beta, induce AP-1
     or NF-kB activation, respectively, leading to GR inhibition. As
     expected, we observed that these molecules inhibit both CAR gene
     expression and phenobarbital-mediated CYP gene expression in human
     hepatocytes.,
  DOI = 10.1081/DMR-120026394,
  ISSN = 0360-2532,
  Unique-ID = ISI:000187608800001,
  

2002

• R. Zuber, M. Modriansky, Z. Dvorak, P. Rohovsky, J. Ulrichova, V. Simanek, and P. Anzenbacher, "Effect of silybin and its congeners on human liver microsomal cytochrome
  P450 activities," PHYTOTHERAPY RESEARCH, vol. 16, iss. 7, pp. 632-638, 2002.
  [Bibtex]

  @article ISI:000179225800005,
  Author = Zuber, R and Modriansky, M and Dvorak, Z and Rohovsky, P and Ulrichova,
     J and Simanek, V and Anzenbacher, P,
  Title = Effect of silybin and its congeners on human liver microsomal cytochrome
     P450 activities,
  Journal = PHYTOTHERAPY RESEARCH,
  Year = 2002,
  Volume = 16,
  Number = 7,
  Pages = 632-638,
  Month = NOV,
  Abstract = Silybin and related flavonolignans form a major part of the Silybum
     marianum extract, silymarin, which has been used to treat liver diseases
     for hundreds of years. Although regarded as safe, many of the extract
     constituents remain thus far untested for their possible effects on
     liver biotransformation enzymes. Cytochromes P450 (CYP) are very
     important in this regard. We tested the effect of four flavonolignans:
     silybin, its hemisynthetic derivative dehydrosilybin, silydianin, and
     silycristin on three specific CYP activities: bufuralol 1'-hydroxylation
     (CYP2D6),p-nitrophenol hydroxylation (CYP2E1), and nifedipine oxidation
     (CYP3A4). All flavonolignans displayed dose-dependent inhibition of
     these activities with IC50 values in the micromolar range. The
     inhibition was competitive or mixed as revealed by double reciprocal
     plots of kinetic experiments. However, the inhibition is not considered
     to be relevant for therapy because physiological concentrations of the
     individual flavonolignans do not exceed 0.5 mum. The data support the
     use of the extract as a dietary supplement. Copyright (C) 2002 John
     Wiley Sons, Ltd.,
  DOI = 10.1002/ptr.1000,
  ISSN = 0951-418X,
  Unique-ID = ISI:000179225800005,
  

• Z. Dvorak, J. Ulrichova, L. Pichard-Garcia, M. Modriansky, and P. Maurel, "Comparative effect of colchicine and colchiceine on cytotoxicity and CYP
  gene expression in primary human hepatocytes," TOXICOLOGY IN VITRO, vol. 16, iss. 3, pp. 219-227, 2002.
  [Bibtex]

  @article ISI:000176538700002,
  Author = Dvorak, Z and Ulrichova, J and Pichard-Garcia, L and Modriansky, M and
     Maurel, P,
  Title = Comparative effect of colchicine and colchiceine on cytotoxicity and CYP
     gene expression in primary human hepatocytes,
  Journal = TOXICOLOGY IN VITRO,
  Year = 2002,
  Volume = 16,
  Number = 3,
  Pages = 219-227,
  Month = JUN,
  Abstract = The aims of the present study were (1) to determine the cytotoxicity of
     colchiceine (EIN) in comparison with that of colchicine (COL); (2) to
     evaluate the effect of EIN on cytochrome P450 (CYP) expression and
     activity, Primary human hepatocytes were the model of choice for
     cytotoxicity and CYP expression experiments. LDH leakage and albumin
     secretion served as cytotoxicity parameters. EIN was less toxic than COL
     based on both parameters within the concentration range 1-100 mum. 10
     mum concentration of EIN did not induce the expression of CYP1A2,
     CYP2A6, CYP2C9, CYP2C19, CYP2E1 and CYP3A4 isoforms, which were
     evaluated at the levels of mRNAs, proteins and specific activities in
     culture. EIN in concentrations up to 200 Pm had no effect on marker
     activities of CYP1A2, 2C9, 2E1 and 3A4 in human liver microsomes. It was
     concluded that ElN in concentrations up to 10 muM is not cytotoxic in
     primary human hepatocytes as revealed by albumin secretion and LDH
     leakage. Possible drug-drug interactions of EIN due to effects on
     cytochromes P4501A2, 2C9, 2E1 and 3A4 isoforms are unlikely because
     inhibition/induction studies show any lack of such effects. As EIN was
     shown to have better antifibrotic properties than COL (European Journal
     of Clinical Investigation 1997, 2, 77), it can be used as a COL
     substitute with anticipated fewer side-effects. (C), 2002 Elsevier
     Science Ltd. All rights reserved.,
  DOI = 10.1016/S0887-2333(02)00004-8,
  ISSN = 0887-2333,
  Unique-ID = ISI:000176538700002,
  

2001

• J. Ulrichova, Z. Dvorak, J. Vicar, J. Lata, J. Smrzova, A. Sedo, and V. Simanek, "Cytotoxicity of natural compounds in hepatocyte cell culture models -
  The case of quaternary benzo[c]phenanthridine alkaloids," TOXICOLOGY LETTERS, vol. 125, iss. 1-3, pp. 125-132, 2001.
  [Bibtex]

  @article ISI:000172529800015,
  Author = Ulrichova, J and Dvorak, Z and Vicar, J and Lata, J and Smrzova, J and
     Sedo, A and Simanek, V,
  Title = Cytotoxicity of natural compounds in hepatocyte cell culture models -
     The case of quaternary benzo[c]phenanthridine alkaloids,
  Journal = TOXICOLOGY LETTERS,
  Year = 2001,
  Volume = 125,
  Number = 1-3,
  Pages = 125-132,
  Month = DEC 15,
  Abstract = The quaternary benzo[c]phenanthridine alkaloids (QBA) produce a
     plethora of species- and tissue-specific effects but the molecular basis
     of their biological activities remain mysterious. The objective of the
     present study was to investigate the cytotoxicity of QBA alkaloids,
     sanguinarine (SA), chelerythrine (CHE), fagaronine (FA), and the extract
     from Macleaya cordata in primary cultures of human and porcine
     hepatocytes. The cellular damage was assessed by the MTT assay, lactate
     dehydrogenase (LDH) leakage and the determination of intracellular
     glutathione (GSH) levels. The results are summarised as follows: (i) The
     alkaloids tested in doses 0.1 and 10 muM did not display statistically
     significant cytotoxicity for 0-3 h incubation; (ii) SA and CHE showed
     the dose- and time-dependent toxicity within the range 25-100 muM
     whereas FA was not toxic; (iii) the LDH leakage into the medium was
     higher for SA than for CHE, thus revealing a potent potential of SA to
     disturb cell-membrane integrity; (iv) after 3 h incubation with 100 muM
     SA/CHE, mitochondrial dehydrogenase activity (MTT assay) and the
     cellular GSH levels decreased to residual values of about 40\%
     suggesting that mitochondria are unlikely to be a primary target for
     SA/CHE in the cell; (v) no differences were found in the response to QBA
     application in human vs porcine hepatocyte. (C) 2001 Elsevier Science
     Ireland Ltd. All rights reserved.,
  DOI = 10.1016/S0378-4274(01)00430-1,
  ISSN = 0378-4274,
  Unique-ID = ISI:000172529800015,
  

• J. Smrzova, Z. Dvorak, J. Lata, P. Dite, M. Machala, L. Blaha, V. Simanek, and J. Ulrichova, "Optimisation of porcine hepatocyte cryopreservation by comparison of
  viability and enzymatic activity of fresh and cryopreserved cells," ACTA VETERINARIA BRNO, vol. 70, iss. 2, pp. 141-147, 2001.
  [Bibtex]

  @article ISI:000170118200004,
  Author = Smrzova, J and Dvorak, Z and Lata, J and Dite, P and Machala, M and
     Blaha, L and Simanek, V and Ulrichova, J,
  Title = Optimisation of porcine hepatocyte cryopreservation by comparison of
     viability and enzymatic activity of fresh and cryopreserved cells,
  Journal = ACTA VETERINARIA BRNO,
  Year = 2001,
  Volume = 70,
  Number = 2,
  Pages = 141-147,
  Month = JUN,
  Abstract = Cryopreservation of porcine hepatocytes would ensure the accessibility
     of cells for laboratory use, permit the standardisation of experiments
     and save lives of animals. Therefore, in this study, we sought the
     optimal procedure for cryopreservation of porcine hepatocytes for both
     laboratory and clinical purposes.
     Hepatocytes were isolated from the liver lobe of a mini-pig by two-step
     collagenase perfusion. The cells were frozen with 20\% foetal calf serum
     and 15\% DMSO in two different media in four different concentrations
     ranging from 1 x 10(6) cells/ml to 5 x 106 cells/ml. For this purpose,
     1.8 ml cryotubes and 120 ml Baxter bags were used. Cells were
     cryopreserved either in a controlled freezer Sylab or step by step in a
     styro-foam box and stored at -196 degreesC.
     The quality of fresh and cryopreserved hepatocytes was assessed by
     trypan blue exclusion test and by the evaluation of cytochrome P450
     isoenzymes and glutathione-S-transferase activities; primary cultures
     were evaluated morphologically and by MTT test. Cryopreserved
     hepatocytes did not form the typical monolayer of polygonal cells in
     primary cultures and remained round, unlike fresh hepatocytes. Lifetime
     of viable culture was shortened from 7-8 days to 4 days in cryopreserved
     cells. Viability of fresh cells was 88 +/- 2\% and decreased to 36-63\%
     in cryopreserved hepatocytes. Enzyme activities of cryopreserved cells
     were reduced to 60\% when compared with fresh hepatocytes.
     Concentrations of 3 x 10(6) cells/ml and 5 x 10(6) cells/ml and
     controlled freezing cave the best results. The use of Baxter bags was
     more convenient due to easier manipulation. Freezing media appeared to
     have no influence.,
  DOI = 10.2754/avb200170020141,
  ISSN = 0001-7213,
  Unique-ID = ISI:000170118200004,
  

1998

• P. Kosina, Z. Dvorak, and D. Walterova, "Expression of cytochromes P450 1A2 and 3A4: effect of silybin and its
  beta-glycosides," CHEMICAL PAPERS, vol. 52, iss. SI, pp. 564, 1998.
  [Bibtex]

  @article ISI:000076671700257,
  Author = Kosina, P and Dvorak, Z and Walterova, D,
  Title = Expression of cytochromes P450 1A2 and 3A4: effect of silybin and its
     beta-glycosides,
  Journal = CHEMICAL PAPERS,
  Year = 1998,
  Volume = 52,
  Number = SI,
  Pages = 564,
  Note = XVI Biochemical Congress of the
     Slovak-and-Czech-Society-of-Biochemistry-and-Molecular-Biology, STARA
     LESNA, SLOVAKIA, OCT 12-15, 1998,
  Organization = Slovak \& Czech Soc Biochem \& Molec Biol,
  ISSN = 0366-6352,
  Unique-ID = ISI:000076671700257,