Overexpression of the c-src protein does not induce transformation of NIH 3T3 cells.
NIH 3T3 mouse cells were transfected with plasmids that induce efficient expression of either (i) the Rous sarcoma virus v-src gene, (ii) the chicken c-src gene, or (iii) a recombinant gene combining the 5' portion of c-src with the 3' end of v-src. Focus formation in tissue culture and formation of large colonies in soft agar did not occur in cells transfected with c-src. Cells transfected with c-src expression plasmids did not form foci but were isolated using a coselectable biological marker. They display morphological and substrate-independent growth characteristics intermediate between those of normal and v-src-transformed mouse cells, and lysates from these cells have enhanced in vitro tyrosine kinase activity. Transfection with the c-src-v-src recombinant induced focus formation with an efficiency similar to that obtained with a v-src expression plasmid. These results imply that v-src-induced transformation does not result just from overexpression of an essentially normal cellular protein but, at least in part, depends on the mutations distinguishing the cellular and viral proteins.
D000595:Amino Acid Sequence; D000818:Animals; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D005796:Genes; D051379:Mice; D009857:Oncogenes; D013329:Structure-Activity Relationship; D014162:Transfection