Inhibitory Effects of Brazilin on the Vascular Smooth Muscle Cell Proliferation and Migration Induced by PDGF-BB

Abnormal vascular smooth muscle cell (VSMC) proliferation and migration contribute to the pathogenesis of vascular diseases including atherosclerosis and restenosis. Brazilin isolated from the heartwood of Caesalpinia sappan L. has been reported to exhibit various biological activities, such as anti-platelet aggregation, anti-inflammation, vasorelaxation and pro-apoptosis. However, the functional effects of Brazilin on VSMCs remain unexplored. The present study investigated the potential effects of Brazilin on platelet-derived growth factor (PDGF)-BB induced VSMC proliferation and migration as well as the underlying mechanism of action. VSMC proliferation and migration were measured by Crystal Violet Staining, wound-healing and Boyden chamber assays, respectively. Cell cycle was analyzed by flow cytometry. Enzymatic action of matrix metalloproteinase-9 (MMP-9) was carried out by gelatin zymography. Expression of adhesion molecules, cell cycle regulatory proteins, the phosphorylated levels of PDGF receptor beta (PDGF-R beta), Src, extra-cellular signal regulated kinase (ERK) and Akt were tested by immunoblotting. The present study demonstrated that pretreatment with Brazilin dose-dependently inhibited PDGF-BB stimulated VSMC proliferation and migration, which were associated with a cell-cycle arrest at G0/G1 phase, a reduction in the adhesion molecule expression and MMP-9 activation in VSMCs. Furthermore, the increase in PDGF-R beta, Src, ERK1/2 and Akt phosphorylation induced by PDGF-BB were suppressed by Brazilin. These findings indicate that Brazilin inhibits PDGF-BB induced VSMC proliferation and migration, and the inhibitory effects of Brazilin may be associated with the blockade of PDGF-R beta - ERK1/2 and Akt signaling pathways. In conclusion, the present study implicates that Brazilin may be useful as an anti-proliferative agent for the treatment of vascular diseases.