Mutagenic specificity of N-acetoxy-3-aminobenzanthrone, a major metabolically activated form of 3-nitrobenzanthrone, in shuttle vector plasmids propagated in human cells.
3-Nitrobenzanthrone (3-NBA) is a potent environmental mutagen and a potential human carcinogen present in diesel exhaust and airborne particulates. N-acetoxy-3-aminobenzanthrone (N-Aco-ABA) has been shown to be a major reactive metabolite of 3-NBA, which mainly produces adducts with guanine and adenine in cellular DNA. Here we analyzed mutations induced by N-Aco-ABA using supF shuttle vector plasmids to elucidate the mutagenic specificity of 3-NBA in human cells. Base sequence analysis of more than 100 plasmids with supF mutations induced in wildtype and DNA repair-deficient XP cells revealed that the major mutation was base substitutions of which the majority (42 and 38%, respectively) were G:C to T:A transversions. The next major mutation was G:C to A:T and A:T to G:C base substitutions in wildtype and XP cells, respectively. The DNA polymerase stop assay using N-Aco-ABA-treated plasmids as a template showed that most stop signals, i.e., adducted sites, appeared at G:C sites. These results suggest that N-Aco-ABA binds preferably to guanine rather than adenine, and adducted adenine is repaired more efficiently by the nucleotide excision repair. Error-prone DNA polymerases could insert adenine at sites opposite to N-Aco-ABA-adducted guanine, which leads to G:C to T:A transversion. These findings could be very important to evaluate the human lung cancer risk of environmental 3-NBA.
Nishida
Hiroshi
H
Environmental Genetics Laboratory, Frontier Science Innovation Center and Department of Biology, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570, Japan.
Kawanishi
Masanobu
M
Takamura-Enya
Takeji
T
Yagi
Takashi
T
D000393:Air Pollutants / Q000378:metabolism / Q000633:toxicity*; D001483:Base Sequence; D001551:Benz(a)Anthracenes / Q000378:metabolism / Q000633:toxicity*; D002460:Cell Line; D018736:DNA Adducts; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D016153:Genes, Suppressor; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics; D013539:Simian virus 40 / Q000235:genetics
D000393:Air Pollutants; D001551:Benz(a)Anthracenes; D018736:DNA Adducts; D009153:Mutagens; C531348:N-acetoxy-3-aminobenzanthrone; C096275:supF tRNA; D012343:RNA, Transfer; C117220:3-nitrobenzanthrone