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Activation of the c‐Ha‐ ras ‐1 proto‐oncogene by methylation in vitro with α‐acetoxy‐ N ‐nitrosodimethylamine
Author(s) -
HiraniHojatti Samin,
Milligan Jamie R.,
Kovnat Asya,
Brown Ken,
Archer Michael C.
Publication year - 1989
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.2940020209
Subject(s) - biology , transfection , oncogene , microbiology and biotechnology , n nitrosodimethylamine , guanine , plasmid , in vitro , dna , methylation , gene , mutation , carcinogen , genetics , nucleotide , cell cycle
α‐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.