[miRNA-26a reduces vascular smooth muscle cell calcification by regulating connective tissue growth factor].

Objective: To investigate the regulatory role of miRNA-26a in vascular smooth muscle cell (VSMC) calcification by regulating connective tissue growth factor (CTGF).
Methods: Rat thoracic aorta VSMCs (A7r5 cells) with induced calcification were treated with AR234960 agonist or transfected with miR-26a mimic, or with both treatments. Alizarin red staining was used to determine calcium deposition, and phosphatase (ALP) activity in the cells was measured. The mRNA and protein expressions of miR-26a, OPG, OPN, BMP-2 and collagen Ⅱ were detected using qPCR and Western blotting. The binding of miR-26a to CTGF was verified using dual luciferase reporter gene assay.
Results: After induced calcification, A7r5 cells showed gradually decreased miR-26a expression ( P < 0.05) and progressively increased CTGF expression ( P < 0.05) with the extension of induction time. Treatment of the cells with AR234960 obviously increased calcification in the cells, while transfection with miR-26a mimic significantly reduced cell calcification. The calcifying cells showed significantly increased ALP activity and expressions of OPN, BMP-2 and collagen Ⅱ ( P < 0.05) and lowered OPG expression ( P < 0.05), and treatment with AR234960 did not produce obvious effects on these changes ( P > 0.05). Transfection with miR-26a mimic resulted in significantly decreased ALP activity and expressions OPN, BMP-2 and collagen Ⅱ expression ( P < 0.05) and increased OPG expression ( P < 0.05) in the calcifying cells. These effects of miR-26a mimic was significantly attenuated by treatment of the cells with AR234960 ( P < 0.05). The result of luciferase reporter gene assay confirmed the binding of miR-26a to CTGF.
Conclusion: miRNA-26a can effectively alleviate vascular calcification by lowering the level of CTGF, reducing ALP activity and the expressions of OPN, BMP-2 and collagen Ⅱ, and increasing the expression of OPG.