Responses of smooth muscle cells to platelet-derived growth factor are inhibited by herbimycin-A tyrosine kinase inhibitor.

Platelet-derived growth factor (PDGF) plays important roles in proliferation of smooth muscle cells (SMCs). PDGF is also known to induce the cytoskeletal reorganization as a chemoattractant. In this communication, we demonstrate that the tyrosine kinase inhibitor herbimycin-A (HM-A) inhibited the effects of PDGF on SMCs in proliferation, phenotypic modulation, and reorganization of F-actin. Another tyrosine kinase inhibitor genistein also inhibited reorganization of F-actin. Since both tyrosine kinase inhibitors reduced PDGF-dependent tyrosine phosphorylation, tyrosine kinase activities may be involved not only in proliferation but also in reorganization of F-actin.