The growth factors, platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) play major roles in enhanced smooth muscle cells growth in rodent blood vessels after vascular injury. Tyrosine kinase inhibition has been shown to be effective in blocking tyrosine phosphorylation at the PDGF and bFGF receptors in cultured fibroblast and vascular smooth muscle cells which in turn inhibits their proliferation[1]. CGP 53716 is a specific PDGFR tyrosine kinase inhibitor on SMC (smooth muscle cell) proliferation and migration in vitro and in neointimal formation in vivo[3]. CGP 53716 inhibited serum-induced cell growth in RASMC (rat aortic smooth muscle cells). And it completely blocked PDGF-BB tyrosine receptor autophosphorylation in RASMC and 3T3 cells, PDGF-BB-induced phosphorylation of mitogen-activated protein kinase at 1 μM in RASMC and inhibited PDGF-BB-induced c-Fos protein expression at 1 μM in RASMC; consistent with inhibition of PDGF-BB-induced DNA synthesis. Further, CGP 53716 inhibited PDGF-BB-, bFGF- and EGF-induced DNA synthesis in a concentration-dependent manner in each cell line. And it showed a 2- to 4-fold selectivity for PDGF-BB-stimulated DNA synthesis over bFGF or EGF in RASMC or 3T3 cells[1]. CGP 53716 inhibited dose dependently tyrosine phosphorylation of both the known PDGFRs: the PDGFR-α and PDGFR-β. After rat carotid artery ballooning injury in vivo, the migration of alpha-actin-positive cells on the luminal side of internal elastic lamina was decreased with 50 mg/kg/day of CGP 53716 from 38 ± 10 (control group) to 4 ± 2. Intima/media ratio was inhibited by 40% after 14 days in the CGP 53716-treated group (P=0.028) after rat aortic denudation[3].
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