A Swiss 3T3 variant cell line resistant to the effects of tumor promoters cannot be transformed by src.
To study the relationship between oncogenesis by v-src and normal cellular signalling pathways, we determined the effects of v-src on 3T3-TNR9 cells, a Swiss 3T3 variant which does not respond mitogenically to tumor promoters such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We found that src was unable to transform these variant cells, whether the oncogene was introduced by infection with a murine retrovirus vector or by transfection with plasmid DNA. 3T3-TNR9 cells were not inherently resistant to transformation, since infection with similar recombinant retroviruses containing either v-ras or v-abl did induce transformation. Further analysis of Swiss 3T3 and 3T3-TNR9 cell populations infected with the v-src-containing retrovirus revealed that although the amount of v-src DNA in each was approximately the same, the level of the v-src message and protein and the overall level of phosphotyrosine expressed in the infected variants was much less than in infected parental cells. Cotransfection experiments using separate v-src and neo plasmids revealed a decrease in the number of G418-resistant colonies when transfections of TNR9 cells occurred in the presence of the src-containing plasmid, suggesting a growth inhibitory effect of v-src on 3T3-TNR9 cells, as has also been found for TPA itself. Since v-src cannot transform this variant cell line, which does not respond mitogenically to the protein kinase C agonist TPA, we suggest that src makes use of the protein kinase C pathway as part of its signalling activities.
Nori
M
M
Department of Microbiology, University of Virginia School of Medicine, Charlottesville 22908.
Shawver
L K
LK
Weber
M J
MJ
D000818:Animals; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D015342:DNA Probes; D004261:DNA Replication / Q000187:drug effects; D003847:Deoxyglucose / Q000378:metabolism; D004351:Drug Resistance / Q000235:genetics*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D051379:Mice; D015688:Oncogene Protein pp60(v-src) / Q000235:genetics*; D009857:Oncogenes; D010957:Plasmids; D012190:Retroviridae / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014162:Transfection
D015342:DNA Probes; D004815:Epidermal Growth Factor; D003847:Deoxyglucose; D015688:Oncogene Protein pp60(v-src); D013755:Tetradecanoylphorbol Acetate