title: Relating aromatic hydrocarbon-induced DNA adducts and c-H-ras mutations in mouse skin papillomas: the role of apurinic sites.
abstract: Mouse skin tumors contain activated c-H-ras oncogenes, often caused by point mutations at codons 12 and 13 in exon 1 and codons 59 and 61 in exon 2. Mutagenesis by the noncoding apurinic sites can produce G-->T and A-->T transversions by DNA misreplication with more frequent insertion of deoxyadenosine opposite the apurinic site. Papillomas were induced in mouse skin by several aromatic hydrocarbons, and mutations in the c-H-ras gene were determined to elucidate the relationship among DNA adducts, apurinic sites, and ras oncogene mutations. Dibenzo[a,l]pyrene (DB[a,l]P), DB[a,l]P-11,12-dihydrodiol, anti-DB[a,l]P-11,12-diol-13,14-epoxide, DB[a,l]P-8,9-dihydrodiol, 7,12-dimethylbenz[a]anthracene (DMBA), and 1,2,3,4-tetrahydro-DMBA consistently induced a CAA-->CTA mutation in codon 61 of the c-H-ras oncogene. Benzo[a]pyrene induced a GGC-->GTC mutation in codon 13 in 54% of tumors and a CAA-->CTA mutation in codon 61 in 15%. The pattern of mutations induced by each hydrocarbon correlated with its profile of DNA adducts. For example, both DB[a,l]P and DMBA primarily form DNA adducts at the N-3 and/or N-7 of deoxyadenosine that are lost from the DNA by depurination, generating apurinic sites. Thus, these results support the hypothesis that misreplication of unrepaired apurinic sites generated by loss of hydrocarbon-DNA adducts is responsible for transforming mutations leading to papillomas in mouse skin.
mesh_terms: D000818:Animals; D001080:Apurinic Acid; D001483:Base Sequence; D001551:Benz(a)Anthracenes / Q000378:metabolism* / Q000633:toxicity; D002273:Carcinogens / Q000378:metabolism* / Q000633:toxicity; D003062:Codon / Q000235:genetics; D018736:DNA Adducts / Q000378:metabolism*; D017931:DNA Primers; D004261:DNA Replication; D005091:Exons; D005260:Female; D011905:Genes, ras; D051379:Mice; D018632:Mice, Inbred SENCAR; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010212:Papilloma / Q000139:chemically induced / Q000235:genetics*; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012867:Skin / Q000187:drug effects / Q000473:pathology*; D012878:Skin Neoplasms / Q000139:chemically induced / Q000235:genetics*; D013329:Structure-Activity Relationship
chemical_list: D001551:Benz(a)Anthracenes; D002273:Carcinogens; D003062:Codon; D018736:DNA Adducts; D017931:DNA Primers; D001080:Apurinic Acid