Anchorage-independent growth of v-myc-transformed Balb/c 3T3 cells is promoted by platelet-derived growth factor or co-transformation by other oncogenes.
Murine fibroblasts transformed by the myc oncogene have a reduced growth factor dependence for both anchorage-dependent and anchorage-independent proliferation. Here we show that v-myc-transformed Balb/c 3T3 cells require, in addition to insulin, only platelet-derived growth factor (PDGF) or epidermal growth factor (EGF) for anchorage-dependent growth in serum-free media. PDGF, however, cannot efficiently be substituted by EGF for anchorage-independent growth. The results suggest that constitutive v-myc expression reduces cellular growth factor requirements by non-autocrine mechanisms for proliferation in monolayer cultures. In contrast, v-myc-transformed cells require plasma components and growth factors of the 'competence' type for anchorage-independent growth. We also demonstrate that the requirement for PDGF by the myc-transformed cells can be abrogated by v-K-ras, v-src and v-fos but not the v-raf oncogene. The results demonstrate that oncogenes can cooperate in the expression of the transformed phenotype by also drastically reducing cellular growth factor requirements.
Vennström
B
B
Differentiation Programme, European Molecular Biology Laboratory, Heidelberg, FGR.
Bravo
R
R
D000818:Animals; D002455:Cell Division; D002472:Cell Transformation, Viral; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006133:Growth Substances / Q000502:physiology*; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D009857:Oncogenes; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*
D006133:Growth Substances; D007328:Insulin; D010982:Platelet-Derived Growth Factor; D004815:Epidermal Growth Factor