SENCAR Mouse Skin Papillomas Induced by 6-Methylbenzo[a]pyrene Carry H-ras Codon 52 (CTA^Leu → CCA^Pro) and Codon 13 (GGC^Gly → GTC^Val) Mutations

Abstract

Organic smoke contains various methylated polycyclic aromatic hydrocarbon (PAH) carcinogens. Among these, 6-methylbenzo[a]pyrene (6-CH₃BP) is a moderate carcinogen. In vitro, it can form both stable and depurinating adducts. Of these, only two depurinating adducts [BP-6-CH₂-N7G and 6-CH₂BP-(1&3)-N7G] have been detected in mouse skin. We examined seven 6-CH₃BP-induced SENCAR mouse skin papillomas for the presence of oncogenic H-ras mutations. Two papillomas contained the codon 52 (CTA^Leu → CCA^Pro) and a third contained the codon 13 (GGC^Gly → GTC^Val) mutation. These results suggest that the H-ras codon 52 mutation is an oncogenic mutation.