title: Involvement of cytoskeleton in AhR-dependent CYP1A1 expression.
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 CYP 1A1 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 [(3)H]-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.
authors.affiliation: Institute of Medical Chemistry and Biochemistry, Medical Faculty, Palacky University Olomouc, Hnevotínská 3, 775 15 Olomouc, Czech Republic.
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Dvorák
authors.forename: Radim
authors.initials: R
authors.lastname: Vrzal
authors.forename: Jitka
authors.initials: J
authors.lastname: Ulrichová
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Pascussi
authors.forename: Patrick
authors.initials: P
authors.lastname: Maurel
authors.forename: Martin
authors.initials: M
authors.lastname: Modriansky
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000201:enzymology; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D003599:Cytoskeleton / Q000502:physiology*; D005434:Flow Cytometry; D016195:G2 Phase / Q000187:drug effects; D022781:Hepatocytes / Q000201:enzymology; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology; D008870:Microtubules / Q000187:drug effects / Q000648:ultrastructure; D015739:Nocodazole / Q000494:pharmacology; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D018336:Receptors, Aryl Hydrocarbon / Q000502:physiology*; D013723:Teratogens / Q000494:pharmacology
chemical_list: D000072317:Polychlorinated Dibenzodioxins; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D013723:Teratogens; D019363:Cytochrome P-450 CYP1A1; D015739:Nocodazole; D003078:Colchicine