Direct mutagenesis of Ha-ras-1 oncogenes by N-nitroso-N-methylurea during initiation of mammary carcinogenesis in rats.
Induction of mammary carcinomas in rats by a single exposure to a carcinogen during sexual development often involves malignant activation of the Ha-ras-1 locus. Each of the Ha-ras-1 oncogenes present in tumours induced by N-nitroso-N-methylurea, but not in those induced by 7,12-dimethylbenz(a)anthracene, became activated by the same G----A transition, the type of mutation induced by N-nitroso-N-methylurea. These results are consistent with the notion that Ha-ras-1 oncogenes are directly activated by the carcinogen during initiation of neoplasia.
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity; D000818:Animals; D001483:Base Sequence; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000235:genetics*; D008770:Methylnitrosourea / Q000633:toxicity*; D009154:Mutation / Q000187:drug effects*; D009607:Nitrosourea Compounds / Q000633:toxicity*; D009857:Oncogenes; D051381:Rats
D009607:Nitrosourea Compounds; D015127:9,10-Dimethyl-1,2-benzanthracene; D008770:Methylnitrosourea