title: Activation of the c-Ha-ras-1 proto-oncogene by methylation in vitro with alpha-acetoxy-N-nitrosodimethylamine.
abstract: alpha-Acetoxy-N-nitrosodimethylamine, an activated derivative of the carcinogen N-nitrosodimethylamine, methylated in vitro a plasmid containing the human c-Ha-ras-1 proto-oncogene, resulting in the generation of a transforming oncogene, assayed by transfection into NIH 3T3 cells. The resulting transformed cells were tumorigenic and metastatic in immune-deprived mice. Further transfection using tumor DNA led to the formation of three secondary NIH 3T3 transformants. DNA from these secondary transformants contained human ras gene sequences. Two of the three secondary transformants contained G----A mutations at guanine 35 in codon 12, and the third secondary transformant retained the wild-type sequence at codons 12, and 61. For the latter, the activating mutation was not determined. These results demonstrate that a simple methylating agent can activate a normal human ras proto-oncogene to a transforming oncogene.
authors.affiliation: Department of Medical Biophysics, University of Toronto, Ontario Cancer Institute, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Hirani-Hojatti
authors.forename: J R
authors.initials: JR
authors.lastname: Milligan
authors.forename: A
authors.initials: A
authors.lastname: Kovnat
authors.forename: K
authors.initials: K
authors.lastname: Brown
authors.forename: M C
authors.initials: MC
authors.lastname: Archer
mesh_terms: D000818:Animals; D015139:Blotting, Southern; D015197:Carcinogenicity Tests; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D004247:DNA / Q000378:metabolism; D004252:DNA Mutational Analysis; D004259:DNA-Directed DNA Polymerase; D004128:Dimethylnitrosamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005784:Gene Amplification; D005786:Gene Expression Regulation; D011905:Genes, ras / Q000187:drug effects*; D006801:Humans; D008297:Male; D008745:Methylation; D051379:Mice; D008808:Mice, Inbred CBA; D015345:Oligonucleotide Probes / Q000138:chemical synthesis / Q000235:genetics; D010957:Plasmids; D000090063:Proto-Oncogene Mas; D019914:Taq Polymerase; D014162:Transfection
chemical_list: C000715470:MAS1 protein, human; D015345:Oligonucleotide Probes; D000090063:Proto-Oncogene Mas; C014659:methyl(acetoxymethyl)nitrosamine; D004247:DNA; D019914:Taq Polymerase; D004259:DNA-Directed DNA Polymerase; D004128:Dimethylnitrosamine