Modulation of the human Harvey-ras oncogene expression by DNA methylation.
A clone of the human transforming Ha-ras oncogene (pT24-C3) was methylated "in vitro" at its HpaII and HhaI sites and co-transfected with a selectable marker into NIH/3T3 cells. In the resulting colonies the normal or transformed morphology correlated respectively with a methylated or unmethylated status of the Ha-ras 1 promoter. A transfected, morphologically normal NIH/3T3 colony treated with 5'-azacytidine acquired a transformed phenotype growing in agar and in nude mice and showed demethylation of the promoter region of Ha-ras 1 gene. The cells of the reactivated colony produced human Ha-ras 1 mRNA and p21, and their DNA displayed transforming activity for NIH/3T3 recipient cells that was due to the original human Ha-ras 1 oncogene. We conclude that the methylation status of the promoter region of the human Ha-ras 1 modulates the expression and consequently the transforming activity of the oncogene.
Borrello
M G
MG
Division of Experimental Oncology, Istituto Nazionale Tumori, Milan, Italy.
Pierotti
M A
MA
Donghi
R
R
Bongarzone
I
I
Cattadori
M R
MR
Traversari
C
C
Mondellini
P
P
Della Porta
G
G
D000818:Animals; D001374:Azacitidine / Q000494:pharmacology; D015152:Blotting, Northern; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D011905:Genes, ras; D006801:Humans; D008745:Methylation; D051379:Mice; D015183:Restriction Mapping; D014162:Transfection
D004247:DNA; D001374:Azacitidine