title: Differential responsiveness of myc- and ras-transfected cells to growth factors: selective stimulation of myc-transfected cells by epidermal growth factor.
abstract: To identify functional relationships between oncogenes and growth factors, we compared the effects of transfected myc and ras oncogenes on the responsiveness of Fischer rat 3T3 cells to three growth factors: epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and transforming growth factor-beta (TGF-beta). Control cells did not grow in soft agar under any conditions. ras-Transfected cells grew in soft agar under all conditions tested and were insensitive to the stimulatory effects of exogenous growth factors. These cells secreted elevated levels of both EGF-like factors and TGF-beta, suggesting that the lack of responsiveness of these cells to exogenous growth factors arose from autocrine stimulation. myc-Transfected cells displayed conditional anchorage-independent growth: they formed numerous colonies in soft agar in the presence of EGF but relatively few colonies in the presence of PDGF or TGF-beta. Secretion of EGF-like factors and TGF-beta by these cells was not elevated above that of control cells. These results suggest a model for the mechanism of cooperation between myc and ras oncogenes in which ras-like genes induce growth factor production, while myc-like genes increase the responsiveness of cells to these factors.
mesh_terms: D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor / Q000235:genetics; D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005796:Genes; D005814:Genes, Viral; D006133:Growth Substances / Q000494:pharmacology*; D009856:Oncogene Proteins, Viral / Q000235:genetics; D009857:Oncogenes / Q000187:drug effects*; D010455:Peptides / Q000494:pharmacology*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011120:Polyomavirus / Q000235:genetics; D051381:Rats; D011916:Rats, Inbred F344; D014162:Transfection; D015291:Transforming Growth Factors
chemical_list: D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor; D006133:Growth Substances; D009856:Oncogene Proteins, Viral; D010455:Peptides; D010982:Platelet-Derived Growth Factor; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors