title: Relationship between chemically induced Ha-ras mutation and transformation of BALB/c 3T3 cells: evidence for chemical-specific activation and cell type-specific recruitment of oncogene in transformation.
abstract: BALB/c 3T3 cells were exposed to 7,12-dimethylbenz[a]anthracene (DMBA) and resultant transformed foci were analyzed for the presence of A182----T mutation at codon 61 of Ha-ras (a mutation found in many DMBA-induced animal tumors). None of the 30 independently cloned transformed cell lines contained such a mutation. In order to see whether DMBA is able to induce this mutation in BALB/c 3T3 cells, we developed a method sensitive enough to detect this specific mutation at the frequency of 10(-6). Employing this assay, we found time- and dose-dependent induction by DMBA of Ha-ras A182----T mutation in BALB/c 3T3 cells; for example, 2 wk after exposure to 100 micrograms/mL DMBA, 1.4 in 1 X 10(4) cells contained this specific mutation. On the other hand, other agents that also induce BALB/c 3T3 cell transformation, such as 3-methylcholanthrene (MCA), 12-O-tetradecanoylphorbol-13-acetate (TPA), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), or ultraviolet light, did not induce the mutation at detectable frequency (less than 10(-6)). These results suggest that DMBA efficiently induces Ha-ras mutation in BALB/c 3T3 cells but that this mutation is not recruited in the process of cell transformation. A hypothesis of carcinogen-specific mutation of Ha-ras gene and its tissue (cell type)-specific recruitment in carcinogenesis is proposed.
authors.affiliation: International Agency for Research on Cancer, Lyon, France.
authors.forename: H
authors.initials: H
authors.lastname: Nakazawa
authors.forename: A M
authors.initials: AM
authors.lastname: Aguelon
authors.forename: H
authors.initials: H
authors.lastname: Yamasaki
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity; D000818:Animals; D000951:Antigens, Neoplasm / Q000633:toxicity; D015295:Antigens, Tumor-Associated, Carbohydrate; D001483:Base Sequence; D002273:Carcinogens; D003062:Codon; D004247:DNA / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects*; D005787:Gene Frequency; D011905:Genes, ras; D008769:Methylnitronitrosoguanidine / Q000633:toxicity; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009154:Mutation; D014170:Transformation, Genetic; D014407:Tumor Cells, Cultured
chemical_list: D000951:Antigens, Neoplasm; D015295:Antigens, Tumor-Associated, Carbohydrate; D002273:Carcinogens; D003062:Codon; C057387:mucinous carcinoma-associated antigen; D008769:Methylnitronitrosoguanidine; D015127:9,10-Dimethyl-1,2-benzanthracene; D004247:DNA