Upregulated miR-17 Regulates Hypoxia-Mediated Human Pulmonary Artery Smooth Muscle Cell Proliferation and Apoptosis by Targeting Mitofusin 2.

BACKGROUND Pulmonary arterial hypertension (PAH) is a fatal disease characterized by impaired regulation of pulmonary artery vascular growth and remodeling. Aberrant expression of miR-17 has been shown to be involved in the pathogenesis of PAH, but its underlying molecular mechanism has not been elucidated. MATERIAL AND METHODS Mitofusin 2 (MFN2) expression was determined by qRT-PCR. The protein expression levels of MFN2, proliferating cell nuclear antigen (PCNA), and pro-apoptotic protein cleaved Caspase-3 were measured using Western blot analysis. Cell proliferation and apoptosis were assessed by CellTiter-Glo reagent and flow cytometry, respectively. Caspase-3/7 activity was measured using an Apo-ONE Homogeneous Caspase-3/7 assay kit. The regulation of miR-17 on MFN2 expression was assessed using luciferase reporter assay system. RESULTS miR-17 expression was upregulated in human pulmonary artery smooth muscle cells (hPASMCs) treated with hypoxia and lung tissues of PAH patients. Inhibition of miR-17 suppressed hypoxia-induced proliferation and promoted apoptosis in hPASMCs. miR-17 inhibited MFN2 expression by binding to its 3'-UTR. Decreased cell viability and increased apoptosis and Caspase-3 activity were observed in the anti-miR-17 + siNC group compared with the anti-miR-NC + siNC group. The expression of cleaved Caspase-3 was upregulated and the expression of PCNA was downregulated in the anti-miR-17 + siNC group. Moreover, these alterations were attenuated by knockdown of MFN2. CONCLUSIONS miR-17 regulates proliferation and apoptosis in hPASMCs through MFN2 modulation. We found that miR-17 acts as a potential regulator of proliferation and apoptosis of hPASMCs, and that it might be developed as a promising new strategy for the treatment of PAH.