Malignant transformation of human fibroblast strain MSU-1.1 by v-fes requires an additional genetic change.
To determine whether the v-fes oncogene can malignantly transform human fibroblasts that have acquired an infinite life span and are partially growth-factor-independent, we transfected cell strain MSU-1.1 with a plasmid containing the v-fes oncogene and a bacterial histidinol dehydrogenase gene. Of the 60 independent histidinol-resistant clones isolated and assayed for v-fes expression using a fes-specific monoclonal antibody, 6 were found to express the v-fes protein at a detectable level. When progeny cells from these 6 clones were further characterized, 3 of the 6 clonal populations exhibited a significant increase in the ability to form medium-sized colonies in agarose, but none were tumorigenic in athymic mice. However, when the 6 populations were propagated for many generations, the same 3 populations acquired the ability to form very large colonies in agarose ( > or = 100 microM in diameter) at a frequency of 2% to 17%, and formed malignant tumors in athymic mice. This suggests that an additional genetic change required for malignant transformation had been spontaneously acquired in 3 of the v-fes -transformed cell strains. To determine whether the change or changes were the equivalent of an activated sis or ras proto-oncogene, we transfected the v-fes oncogene into derivative strains of MSU-1.1 that express a transfected v-sis, c-H-ras or c-N-ras oncogene, but that do not form tumors, and assayed the v-fes-expressing transfectants for tumorigenicity. The results showed that when complemented either by a ras oncogene expressed at a somewhat enhanced level or by the v-sis oncogene, v-fes can supply the additional change required for malignant transformation.
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Carcinogenesis Laboratory, Department of Microbiology, Michigan State University, East Lansing 48824, USA.
Maher
V M
VM
McCormick
J J
JJ
D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002478:Cells, Cultured; D005347:Fibroblasts; D015681:Fusion Proteins, gag-onc / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009857:Oncogenes; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000235:genetics; D014162:Transfection
D015681:Fusion Proteins, gag-onc; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger