Silence of ClC‐3 chloride channel inhibits cell proliferation and the cell cycle via G₁/S phase arrest in rat basilar arterial smooth muscle cells

OBJECTIVES: Previously, we have found that the ClC-3 chloride channel is involved in endothelin-1 (ET-1)-induced rat aortic smooth muscle cell proliferation. The present study was to investigate the role of ClC-3 in cell cycle progression/distribution and the underlying mechanisms of proliferation. MATERIALS AND METHODS: Small interference RNA (siRNA) is used to silence ClC-3 expression. Cell proliferation, cell cycle distribution and protein expression were measured or detected with cell counting, bromodeoxyuridine (BrdU) incorporation, Western blot and flow cytometric assays respectively. RESULTS: ET-1-induced rat basilar vascular smooth muscle cell (BASMC) proliferation was parallel to a significant increase in endogenous expression of ClC-3 protein. Silence of ClC-3 by siRNA inhibited expression of ClC-3 protein, prevented an increase in BrdU incorporation and cell number induced by ET-1. Silence of ClC-3 also caused cell cycle arrest in G(0)/G(1) phase and prevented the cells' progression from G(1) to S phase. Knockdown of ClC-3 potently inhibited cyclin D1 and cyclin E expression and increased cyclin-dependent kinase inhibitors (CDKIs) p27(KIP) and p21(CIP) expression. Furthermore, ClC-3 knockdown significantly attenuated phosphorylation of Akt and glycogen synthase kinase-3beta (GSK-3beta) induced by ET-1. CONCLUSION: Silence of ClC-3 protein effectively suppressed phosphorylation of the Akt/GSK-3beta signal pathway, resulting in down-regulation of cyclin D1 and cyclin E, and up-regulation of p27(KIP) and p21(CIP). In these BASMCs, integrated effects lead to cell cycle G(1)/S arrest and inhibition of cell proliferation.