MicroRNA-16-5p Aggravates Myocardial Infarction Injury by Targeting the Expression of Insulin Receptor Substrates 1 and Mediating Myocardial Apoptosis and Angiogenesis

Purpose: Myocardial infarction is a common cardiovascular disease. MicroRNA-16-5p (miR-16-5p) was upregulated in heart and kidney hypoxia/reoxygenation (H/R) injury. However, the role of miR-16-5p in myocardial infarction injury is still unclear. Methods: Human adult ventricular cardiomyocytes (AC16) were treated with ischemia/reperfusion (H/R). The miR-16-5p level was evaluated through real-time PCR. The activity of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) was detected via LDH and CK-MB monitoring kits. Cell viability was examined with 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetra-zolium bromide (MTT) assay. Western blotting was used to analyze the protein levels. The luci-ferase report assay confirmed the relative luciferase activity. Results: miR-16-5p was elevated in H/R-treated AC16 cells. miR-16-5p overexpression and knockdown were carried out. miR-16-5p knockdown repressed cell apoptosis, attenuated LDH and CK-MB activities, and enhanced cell viability in H/R-treated AC16 cells. Moreover, miR-16-5p knockdown promoted angiogenesis in human microvascular endothelial cells (HMVEC), causing elevation of vascular endothelial growth factor (VEGF), insulin receptor substrates 1 (IRS1), minichromosome maintenance complex component 2 (MCM2) and proliferating cell nuclear antigen (PCNA) protein levels. Moreover, miR-16-5p was testified to target IRS1. IRS1 silencing alleviated miR-16-5p knockdown-mediated inhibition of apoptosis in AC16 cells. Conclusion: miR-16-5p knockdown increased cell viability and angiogenesis, as well as inhibited cell apoptosis by increasing IRS1. These findings indicated that miR-16-5p knockdown may be a new therapeutic target for myocardial infarction.