title: Cytotoxic and genotoxic profiles of benzo[a]pyrene and N-nitrosodimethylamine demonstrated using DNA repair deficient DT40 cells with metabolic activation.
abstract: Benzo[a]pyrene and N-nitrosodimethylamine are major genotoxic compounds present in cigarette smoke, food and oil. To examine the type(s) of DNA damage induced by these compounds, we used a panel of DNA-repair-pathway-deficient mutants generated from chicken DT40 cells and achieved metabolic activation of the test compounds by including rat liver S9 mix. Consistent with expections, benzo[a]pyrene and N-nitrosodimethylamine require metabolicactivation to become genotoxic. The REV3(-/-) mutant cell line exhibited the highest sensitivity, in terms of increased cytotoxicity, to the both compounds after metabolic activation consistent with the known ability of these two compounds to induce DNA adducts. Strikingly, we found that the RAD54(-/-)/KU70(-/-) cell line, a mutant defective in the repair of double-strand breaks, is sensitive to benzo[a]pyrene, suggesting that this compound also induces strand breaks in these cells. In this study we combined a previously employed method, metabolic activation by S9 mix, with the use of a DNA-repair mutant panel, thereby broadening the range of compounds that can be screened for potential genotoxicity.
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Ooka
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Takazawa
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan. Electronic address: khirota@tmu.ac.jp.
authors.forename: Kouji
authors.initials: K
authors.lastname: Hirota
mesh_terms: D065767:Activation, Metabolic / Q000187:drug effects; D000818:Animals; D001564:Benzo(a)pyrene / Q000378:metabolism* / Q000633:toxicity*; D002460:Cell Line; D002645:Chickens; D003603:Cytotoxins / Q000378:metabolism / Q000633:toxicity; D018736:DNA Adducts / Q000378:metabolism; D053960:DNA Breaks / Q000187:drug effects; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects*; D004128:Dimethylnitrosamine / Q000378:metabolism* / Q000633:toxicity*; D009153:Mutagens / Q000378:metabolism / Q000633:toxicity; D051381:Rats
chemical_list: D003603:Cytotoxins; D018736:DNA Adducts; D009153:Mutagens; D001564:Benzo(a)pyrene; D004128:Dimethylnitrosamine
keywords: DNA repair; DT40; Genotoxicity test; Homologous recombination (HR); Translesion synthesis (TLS)