title: Metabolism-mediated Ochratoxin A genotoxicity in the single-cell gel electrophoresis (Comet) assay.
abstract: The mycotoxin Ochratoxin A (OTA) is a contaminant of food and feed commodities in many countries. Long-term exposure to OTA in humans has been associated with an increased incidence of a progressive nephropathy (BEN). Bio-activation of OTA has been implicated in the OTA-mediated toxicity, although inconsistent results have been reported. The aim of the present study was to investigate the genotoxic potency of OTA and its metabolites in NIH/3T3 cells stably expressing the human cytochrome P450 iso-enzymes CYP2C9 and CYP3A4, by using the single-cell gel electrophoresis (SCGE/Comet) assay, which detects single strand DNA breaks. The obtained results confirm the hypothesis that biotransformation processes mediate OTA toxicity, and differences in response were observed in CYP2C9-hOR and CYP3A4-hOR expressing cells, respectively. Results showed that biotransformation of OTA increased the genotoxicity. Measurement of reactive oxygen species (ROS) production showed that the OTA-induced ROS production corresponded to the OTA-induced genotoxicity in the used NIH/3T3 cell lines.
authors.affiliation: Department of Veterinary Pharmacology, Pharmacy and Toxicology, Utrecht University, Yalelaan 16, 3508 TD Utrecht, The Netherlands. y.simarro@xs4all.nl
authors.forename: Y
authors.initials: Y
authors.lastname: Simarro Doorten
authors.forename: S
authors.initials: S
authors.lastname: Nijmeijer
authors.forename: L
authors.initials: L
authors.lastname: de Nijs-Tjon
authors.forename: J
authors.initials: J
authors.lastname: Fink-Gremmels
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001711:Biotransformation; D020552:Comet Assay; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004008:Diclofenac / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D006900:Hydroxylation; D051379:Mice; D009499:Neutral Red; D009793:Ochratoxins / Q000378:metabolism* / Q000633:toxicity*; D016877:Oxidants / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D017382:Reactive Oxygen Species; D013723:Teratogens / Q000378:metabolism* / Q000633:toxicity*; D013778:Tetrazolium Salts; D013844:Thiazoles; D014466:Ultraviolet Rays
chemical_list: D018076:DNA, Complementary; D009793:Ochratoxins; D016877:Oxidants; D017382:Reactive Oxygen Species; D013723:Teratogens; D013778:Tetrazolium Salts; D013844:Thiazoles; D004008:Diclofenac; C025589:ochratoxin A; D009499:Neutral Red; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide; C408695:Cyp3a41a protein, mouse; D010088:Oxidoreductases; C022616:thiazolyl blue