Acidic and basic fibroblast growth factors are survival factors with distinctive activity in quiescent BALB/c 3T3 murine fibroblasts.

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Abstract
Platelet-derived growth factor (PDGF), epidermal growth factor, and insulin-like growth factor have previously been identified as survival factors with distinctive activities for the density-inhibited quiescent BALB/c 3T3 murine fibroblasts. Fibroblast growth factor (FGF), like PDGF, renders quiescent BALB/c 3T3 cells competent to respond to epidermal growth factor and insulin-like growth factor, which mediate cell-cycle traverse through G1 into S phase [Stiles, C. D., Pledger, W. J., VanWyk, J. J., Antoniades, H. N. & Scher, C. D. (1979) Proc. Natl. Acad. Sci. USA 76, 1279-1283]. We now show that FGF possess marked cell survival-enhancing activity distinctive from that of PDGF. Both acidic FGF (aFGF) and basic FGF (bFGF) markedly enhance short-term (3-hr) survival of quiescent cells. bFGF is the more active of the two factors and shows marked long-term (20-hr) survival-promoting activity alone, whereas aFGF requires heparin for long-term activity. Protection by bFGF or aFGF plus heparin is not associated with cell-cycle traverse into S phase. Both the short-term (3-hr) and long-term (20-hr) protective actions of aFGF and bFGF critically depend on protein synthesis, whereas those of PDGF do not. The accumulated evidence shows that several growth factors can contribute to maintenance of the integrity of quiescent murine fibroblasts and that their action can involve protein kinase A- and C-mediated processes as well as protein synthesis. Different growth factors display distinctive modes of action.