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 (T GF-beta), and insulin-like growth factor-I (IGF-I) on platelet-derived growth factor (PDGF)-BB-, basic fibroblastic growth factor (bFGF)-, a nd epidermal growth factor (EGF)-induced DNA synthesis in vascular smo oth muscle cells (VSMCs) was investigated. TGF-beta, AII, IGF-I increa sed concentration-dependent cell protein. No increase in [H-3]thymidin e incorporation could be detected. TGF-beta, AII, and IGF-I enhanced P DGF-BB-, bFGF-, and EGF-induced DNA synthesis. Our results suggest tha t growth factors that possess a weak mitogenic effect on vascular smoo th muscle cells such as TGF-beta, AII and IGF-I may enhance the mitoge nicity of PDGF-BB, bFGF, and EGF.