ERK1/2 pathway is involved in the inhibitory effect of crocetin on angiotensin II-induced vascular smooth muscle cell proliferation

Angiotensin II (Ana II) induces vascular smooth muscle cells (VSMCs) proliferation, which plays an important role in the development and progression of atherosclerosis. Ana II-induced cellular events have been implicated, in part, in the activation of extracellular signal-regulated kinases 1/2 (ERK1/2). Crocetin is a natural carotenoid compound isolated from Gardenia jasminoids Ellis. In the present study, we investigated the effect of crocetin on the Ana II-induced VSMCs proliferation and ERK1/2 activation. 3-[4,5-dimetliylthiazol-2-yl]-2,5-dephenyl tetrazolium bromide (MTT) and [H-3]thymidine incorporation assay showed that the Ana II-induced VSMCs proliferation was inhibited significantly by crocetin. In-gel kinase assay indicated that Ana II elicited rapid and significant increase of ERK 1/2 activity in VSMCs, which was suppressed by crocetin markedly. Western blotting analysis and cell-based enzyme-linked immunosorbent assay (ELISA) demonstrated that crocetin significantly inhibited the phosphorylation and activation of ERK1/2 induced by Ana II. Using the indirect immunoflorescent technique, we also found that crocetin inhibited nuclear translocation of activated ERK1/2 induced by Ana II. These findings suggest that the suppression by crocetin of the Ana II-induced VSMCs proliferation can be attributed, at least in part, to its inhibitory effect on ERK1/2 pathway. (c) 2006 Elsevier B.V All rights reserved.