Synergistic action of angiotensin II, insulin-like growth factor-I, and transforming growth factor-beta on platelet-derived growth factor-BB, basic fibroblastic growth factor, and epidermal growth factor-induced DNA synthesis in vascular smooth muscle cells.

The effect of angiotensin II (AII), transforming growth factor-beta (TGF-beta), and insulin-like growth factor-I (IGF-I) on platelet-derived growth factor (PDGF)-BB-, basic fibroblastic growth factor (bFGF)-, and epidermal growth factor (EGF)-induced DNA synthesis in vascular smooth muscle cells (VSMCs) was investigated. TGF-beta, AII, IGF-I increased concentration-dependent cell protein. No increase in [3H]thymidine incorporation could be detected. TGF-beta, AII, and IGF-I enhanced PDGF-BB-, bFGF-, and EGF-induced DNA synthesis. Our results suggest that growth factors that possess a weak mitogenic effect on vascular smooth muscle cells such as TGF-beta, AII, and IGF-I may enhance the mitogenicity of PDGF-BB, bFGF, and EGF.