title: Ochratoxin A induces CYP3A4, 2B6, 3A5, 2C9, 1A1, and CYP1A2 gene expression in primary cultured human hepatocytes: a possible activation of nuclear receptors.
abstract: Ochratoxin A (OTA) is a mycotoxin produced by fungi of two genera: Penicillium and Aspergillus. OTA has been shown to be nephrotoxic, hepatotoxic, teratogenic, and immunotoxic to several species of animals and to cause kidney and liver tumors in mice and rats. Biotransformation of OTA has not been entirely elucidated. Several metabolites have been characterized in vitro and/or in vivo, whereas other metabolites remain to be characterized. At present, data available regarding OTA metabolism and cytochrome inductions concern only rodents or in vitro systems. The aim of the present study was to explore the effect of OTA on mRNA expression of some cytochromes known to be regulated by pregnane X receptor (PXR), constitutive androstane receptor (CAR), and aryl hydrocarbon receptor (AhR), using primary cultures of human hepatocytes. Our results showed that OTA reduced hepatocyte viability in a dose-dependent manner. Using quantitative real-time reverse-transcription polymerase chain reaction, our study showed that treatment of primary cultured human hepatocytes with noncytotoxic increasing concentrations of OTA for 24 hours caused a significant upregulation of CYP3A4, CYP2B6, and, to a lesser extent, CYP3A5 and CYP2C9. PXR mRNA expression increased in only 1 treated liver, whereas CAR mRNA expression was not affected. OTA was found also to induce an overexpression of CYP1A1 and CYP1A2 genes accompanied by an increase in AhR mRNA expression. These findings suggest that OTA could activate PXR and AhR; however, further investigations are needed to confirm nuclear-receptor activation by OTA.
authors.affiliation: Laboratory of Research on Biologically Compatible Compounds, Faculty of Dentistry, Monastir, Tunisia.
authors.forename: Imen
authors.initials: I
authors.lastname: Ayed-Boussema
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Pascussi
authors.forename: Chiraz
authors.initials: C
authors.lastname: Zaied
authors.forename: Patrick
authors.initials: P
authors.lastname: Maurel
authors.forename: Hassen
authors.initials: H
authors.lastname: Bacha
authors.forename: Wafa
authors.initials: W
authors.lastname: Hassen
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D009793:Ochratoxins / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D000077297:Pregnane X Receptor; D012333:RNA, Messenger / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000187:drug effects / Q000378:metabolism; D011987:Receptors, Steroid / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D009793:Ochratoxins; D000077297:Pregnane X Receptor; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D011987:Receptors, Steroid; C025589:ochratoxin A; D003577:Cytochrome P-450 Enzyme System