Effect of pioglitazone on the calcification of rat vascular smooth muscle cells through the downregulation of the Wnt/β-catenin signaling pathway

The aim of the present study was to investigate the effect and possible mechanism of pioglitazone (PIO) on the calcification of rat vascular smooth muscle cells (VSMCs) in vitro. beta-glycerophosphate (beta-GP; 10 mmol/l) was used to induce calcification of VSMCs treated with a range of concentrations (5, 10, 15 and 20 mu mol/l) of PIO for 12 days. Calcium deposits were revealed by Alizarin red staining. Extracellular calcium content was detected using a calcium assay kit. Western blotting was used to measure the expression of alpha-smooth muscle actin (alpha-SMA), runt-related transcription factor 2 (Runx2), bone morphogenetic protein-2 (BMP2), beta-catenin, glycogen synthase kinase-3 beta (GSK-3 beta), phosphorylated (p)-GSK-3 beta and cyclin-D1. A total of 10 mmol/l beta-GP, 20 mu mol/l PIO and 20 mu mol/l peroxisome proliferator-activated receptor gamma (PPAR gamma) antagonist GW9662, was added to the cell culture media. The changes of the above indexes were observed. The calcium content in the calcification group, treated with high phosphorus, increased significantly compared with the controls (P<0.05) and all different concentrations of PIO reduced extracellular calcium content (P<0.05). Alizarin red staining was positive in calcified VSMCs and PIO (20 mu mol/l) intervention group was almost negative. The expressions of Runx2, beta-catenin, p-GSK-3 beta, BMP2 and cyclin-D1 increased significantly in the calcification group, and treatment with 20 mu mol/l PIO downregulated the expression of all the above proteins, while upregulating the expression of alpha-SMA. The PPAR gamma antagonist GW9662 could partly inhibit the effect of PIO on calcified VSMCs. The results of the present study indicated that PIO can alleviate the calcification of rat aortic VSMCs induced by beta-GP via inhibiting the activity of the Wnt/beta-catenin signaling pathway.