Malignant transformation of a human fibroblast cell strain by transfection of a v-fes oncogene but not by transfection of a gag-human c-fes construct.

To determine whether the human c-fes gene, a homologue of the feline v-fes oncogene, can play a role in the malignant transformation of human fibroblasts, we transfected a near-diploid, infinite life span, growth factor-independent, human fibroblast cell strain, MSU-1.2, with plasmids carrying a fes gene along with a selectable marker. The fes gene was either the v-fes oncogene from the Gardner-Arnstein strain of feline sarcoma virus or a chimeric construct in which 835 base pairs representing exons 10-19 from the human c-fes proto-oncogene had been substituted for the corresponding feline sequence in the v-fes oncogene. The transfected cells were selected in appropriate medium, and a number of drug-resistant clones were isolated, and the progeny cells were assayed for fes expression by immunoprecipitation analysis. Six independent clones that expressed the v-fes protein and four that expressed the gag-c-fes protein were further characterized. The former exhibited anchorage independence and formed progressively growing, invasive, spindle cell sarcomas in athymic mice after only a short latency period. The latter strains were not anchorage independent and did not form tumors in athymic mice. These results show that the v-fes oncogene can malignantly transform an infinite life span human fibroblast cell strain, but the human c-fes gene cannot.