Epigallocatechin-3-gallate inhibits proliferation of human aortic smooth muscle cells via up-regulating expression of mitofusin 2

Previous studies have shown that epigallocatechin-3-gallate (EGCG) inhibits the proliferation of vascular smooth muscle cells (VSMCs) via the extracellular-signal-regulated kinase (ERK1/2) and mitogen activated protein kinases (MAPKs) pathway. Mitofusin 2 (Mfn-2) also suppresses VSMC proliferation through Ras-Raf-ERK/MAPK, suggesting a possible link between EGCG, Mfn-2 and ERK/MAPK. However, the effect of EGCG on Mfn-2 remains unknown. In this study, we investigated the role of Mfn-2 in the regulation of VSMC proliferation by EGCG, and assessed the underlying mechanisms. The effects of EGCG on the proliferation of cultured human aortic smooth muscle cells (HASMCs) were observed by 5-ethyn1-2-deoxyuridine (EdU) incorporation assay. Mfn-2 gene and protein levels, and Ras, p-c-Raf and p-ERK1/2 protein levels were determined by quantitative real-time polymerase chain reaction and western blotting, respectively. Mfn-2 gene silencing was achieved by RNA interference. EGCG 50 mu mol/L profoundly inhibited the proliferation of HASMCs in culture, up-regulated Mfn-2, and down-regulated the expression of p-c-Raf and p-ERK1/2. Furthermore, RNA interference-mediated gene knockdown of Mfn-2 antagonized EGCG-induced anti-proliferation and down-regulation of Ras, p-c-Raf and p-ERK1/2. These results suggest that EGCG inhibits the proliferation of HASMCs in vitro largely via Mfn-2-mediated suppression of the Ras-Raf-ERK/MAPK signaling pathway. (C) 2014 Elsevier GmbH. All rights reserved.