title: Mechanism of metal-mediated DNA damage induced by a metabolite of carcinogenic acetamide.
abstract: Acetamide is carcinogenic in rats and mice. To clarify the mechanism of carcinogenesis by acetamide, we investigated DNA damage by and acetamide metabolite, acetohydroxamic acid (AHA), using 32P-5'-end-labeled DNA fragments. AHA treated with amidase induced DNA damage in the presence of Cu(II) and displayed a similar DNA cleavage pattern of hydroxylamine. DNA damage was inhibited by both catalase and bathocuproine, suggesting that H2O2 and Cu(I) are involved. Carboxy-PTIO, a specific scavenger of nitric oxide (NO), partially inhibited DNA damage. The amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) by amidase-treated AHA was similar to that by hydroxylamine. ESR spectrometry revealed that amidase-treated AHA as well as hydroxylamine generated NO in the presence of Cu(II). From these results, it has been suggested that AHA might be converted into hydroxylamine by amidase. These results suggest that metal-mediated DNA damage mediated by amidase-catalyzed hydroxylamine generation plays an important role in the carcinogenicity of acetamide.
authors.affiliation: Department of Environmental and Molecular Medicine, Mie University School of Medicine, Edobashi, Tsu, Japan.
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Sakano
authors.forename: Shinji
authors.initials: S
authors.lastname: Oikawa
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hiraku
authors.forename: Shosuke
authors.initials: S
authors.lastname: Kawanishi
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000081:Acetamides / Q000378:metabolism*; D000581:Amidohydrolases / Q000494:pharmacology; D000818:Animals; D002273:Carcinogens / Q000378:metabolism*; D002374:Catalase / Q000494:pharmacology; D003300:Copper / Q000378:metabolism*; D004247:DNA / Q000187:drug effects; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D006877:Hydroxamic Acids / Q000633:toxicity*; D010618:Phenanthrolines / Q000494:pharmacology; D051381:Rats
chemical_list: D000081:Acetamides; D002273:Carcinogens; D016166:Free Radical Scavengers; D006877:Hydroxamic Acids; D010618:Phenanthrolines; C006358:acetohydroxamic acid; D003300:Copper; D000080242:8-Hydroxy-2'-Deoxyguanosine; C030686:acetamide; D004247:DNA; C002478:bathocuproine; D002374:Catalase; D000581:Amidohydrolases; C019665:amidase; D003849:Deoxyguanosine