A highly efficient retroviral vector allows detection of the transforming activity of the human c-fps/fes proto-oncogene.
We have constructed an efficient new retroviral vector containing strong promoting elements derived from the Friend murine leukemia virus (F-MuLV) long terminal repeat (LTR) and have used the vector to demonstrate that overexpression of human c-fps/fes can transform established mouse cells. When a c-fps/fes cDNA was cloned into the vector, this viral DNA and the recovered virus induced very high levels of the c-fps/fes product NCP92 and tumorigenic transformation of NIH 3T3 cells. Compared with an isogenic vector under control of a Moloney MuLV-derived LTR, the vector driven by the F-MuLV LTR induced 3- to 10-times-higher levels of expression of c-fps/fes, a higher level of phosphotyrosine in cellular proteins, and a virus whose transforming activity was 2 orders of magnitude greater. We conclude (i) that normal c-fps/fes can induce morphologic transformation and that its transforming activity is a function of the level of expression of NCP92 and (ii) that the vector based on the F-MuLV LTR is more efficient than the vector driven by a Moloney MuLV LTR in inducing high levels of expression and measurable biological activity.
Feldman
R A
RA
Laboratory of Cellular Oncology, National Cancer Institute, Bethesda, Maryland 20892.
Lowy
D R
DR
Vass
W C
WC
Velu
T J
TJ
D000818:Animals; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D005622:Friend murine leukemia virus / Q000235:genetics*; D015870:Gene Expression; D005822:Genetic Vectors; D006801:Humans; D051379:Mice; D010957:Plasmids; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011519:Proto-Oncogenes; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D014162:Transfection
C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; C052602:proto-oncogene protein c-fes-fps; D011505:Protein-Tyrosine Kinases