BASIC FGF AND TGF-BETA DIFFERENTIALLY MODULATE INTEGRIN EXPRESSION OF HUMAN MICROVASCULAR ENDOTHELIAL-CELLS

Basic fibroblast growth factor (bFGF) and transforming growth factor-β (TGF-β) are known to alter the migratory and proliferative capacity of endothelial cells in vitro and to stimulate angiogenesis in vivo. One mechanism by which these cytokines induce their effects may be through the regulation of integrin adhesion receptor expression and activity. We examined the ability of these growth factors to modulate the expression of specific integrins in human microvascular endothelial cells (MEC). Immunoprecipitation of metabolically labeled MEC showed that bFGF upregulated the biosynthesis of α2, α5, β1,and β3. bFGF induced an increase in the levels of mRNA for α2 and β1. TGF-β increased synthesis of α2, α5, and β1. These results suggest that bFGF and TGF-β selectively alter integrin profiles and influence interactions of MEC with the extracellular matrix during neovascularization. In particular, the upregulation of the collagen/laminin receptor, α2β1, by bFGF may provide activated endothelial cells with an enhanced capacity to migrate through both their underlying basement membrane and the interstitial matrix. © 1992.