RESUMEN
<p><b>OBJECTIVE</b>To elucidate the effect of hydroxysafflor yellow A ( HYSA) on the proliferation of vascular smooth muscle cells (VSMCs) and the related mechanism.</p><p><b>METHODS</b>VSMCs derived from SD rats were treated with DMEC culture medium (Control), 10 ng/ml PDGF (PDGF group), pretreatment with HYSA at different doses (1, 5, 10, 20, 40, 60 µmol/L) for 24 h then cotreatment with PDGF. After 24 h, MTT assay, Western blot and immunohistochemical staining were performed to evaluate the inhibitory effects of HYSA on VSMCs proliferation.</p><p><b>RESULTS</b>HYSA inhibited PDGF induced VSMCs proliferation in a dose-dependent manner, dowregulated proliferating cell nuclear antigen (PCNA) expression and blocked PDGF activated PDGFR-MEK-ERK1/2 signaling pathway.</p><p><b>CONCLUSIONS</b>HYSA inhibits VSMCs proliferation possibly via downregulating the expression of PCNA and blocking MEK-ERK1/2 signal transduction in VSMCs.</p>