title: Role of exposure/recovery schedule in micronuclei induction by several promutagens in V79-derived cells expressing human CYP2E1 and SULT1A1.
abstract: The standard procedure for the micronucleus test in cell lines requires a short exposure (≤0.5 cell cycle) to the test compounds followed by a long recovery (≥1.5 cell cycle), and in case of negative or equivocal results, a second test with extended exposure (≥2 cell cycles) without or with a recovery time. In general the two procedures are advantageous for detecting clastogens and aneugens, respectively. However, whether the recommended procedures apply to micronucleus tests with promutagens in cell lines genetically engineered for expressing biotransformation enzymes has not been identified. In this study, several promutagens dependent on cytochrome P450 (CYP) 2E1 and/or sulfotransferase (SULT) 1A1 were used in the micronucleus test in a Chinese hamster V79-derived cell line expressing human CYP2E1 and SULT1A1 (V79-hCYP2E1-hSULT1A1), with varying exposure/recovery schedules: 3h/21h, 6h/18h, 12h/12h, 18h/6h, and 24h/0h, in comparison with known clastogens and aneugens in V79 control cells. The results showed peaked micronuclei induction by mitomycin C and bleomycin (clastogens) at the 12h/12h schedule, while colchicine and vinblastine (aneugens) showed the strongest effect at 24h/0h. Catechol and trihydroxybenzene (activated by CYP2E1) induced micronuclei most strongly at 6h/18h, whereas somewhat longer exposures were optimal for hydroquinone, another compound activated by CYP2E1. 1-Hydroxymethylpyrene (activated by SULT1A1) and 1-methylpyrene (activated sequentially by CYP2E1 and SULT1A1) produced the highest response with the 18h/6h treatment regimen. Moreover, mitotic arrest by 1-hydroxymethylpyrene was observed in V79-hCYP2E1-hSULT1A1 cells but not in V79 cells, and 1-methylpyrene arrested mitosis in V79-hCYP2E1-hSULT1A1 more strongly than in V79 cells. Our study suggests that intracellular bioactivation of promutagens may not delay the induction of micronuclei in the present model, and 1-methylpyrene and 1-hydroxymethylpyrene may be activated to mitosis-arresting metabolites.
authors.affiliation: Department of Toxicology, School of Public Health, Southern Medical University, 1023 South Shatai Road, Guangzhou 510515, China.
authors.forename: Hansi
authors.initials: H
authors.lastname: Jia
authors.affiliation: Department of Toxicology, School of Public Health, Southern Medical University, 1023 South Shatai Road, Guangzhou 510515, China.
authors.forename: Chiteng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Nutritional Toxicology, German Institute of Human Nutrition (DIfE), Arthur-Scheunert-Allee 114-116, D-14558 Nuthetal, Germany; Department of Food Safety, Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, D-10589 Berlin, Germany.
authors.forename: Hansruedi
authors.initials: H
authors.lastname: Glatt
authors.affiliation: Department of Toxicology, School of Public Health, Southern Medical University, 1023 South Shatai Road, Guangzhou 510515, China. Electronic address: yungliu@126.com.
authors.forename: Yungang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D015239:Arylsulfotransferase / Q000235:genetics / Q000378:metabolism*; D002396:Catechols / Q000494:pharmacology; D002460:Cell Line; D003412:Cricetulus; D000072467:Cytochrome P450 Family 2 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D008658:Inactivation, Metabolic; D015162:Micronucleus Tests / Q000379:methods*; D008938:Mitosis / Q000187:drug effects; D009153:Mutagens / Q000008:administration & dosage* / Q000633:toxicity; D011721:Pyrenes / Q000494:pharmacology
chemical_list: D002396:Catechols; D006873:Hydroquinones; D009153:Mutagens; D011721:Pyrenes; C013038:hydroxyhydroquinone; C053035:1-methylpyrene; C065833:1-hydroxymethylpyrene; C110332:CYP2F1 protein, human; D000072467:Cytochrome P450 Family 2; D015239:Arylsulfotransferase; C117544:SULT1A1 protein, human; C034221:catechol; C031927:hydroquinone
keywords: Aneugen; CYP2E1; Clastogen; Exposure/recovery schedule; Micronucleus; Sulfotransferase (SULT)