Abstract

Objective: Acute myocardial infarction (AMI) is the main cause of sudden death in the world. The aim of this paper was to explore the role of microRNA-18-5p (miR-18-5p) in myocardial infarction (MI) and its potential mechanism. Materials and methods: The expression of miRNA and protein was detected using quantitative reverse-transcription polymerase chain reaction (RT-PCR) analysis and Western blot. The level of oxidative stress of cardiomyocytes was evaluated by detecting the contents of Superoxide dismutase (SOD), Reactive oxygen species (ROS) and Malondialdehyde (MDA). Caspase-3 activity assay, flow cytometry and TUNEL staining were employed to evaluate apoptosis of myocardium. Dual-Luciferase reporter gene assay was used to prove whether miR-18-5p targeted RUNX1. Results: MiR-18-5p was down-regulated in hypoxia-treated H9c2 cells. Hypoxia treatment induced oxidative stress and apoptosis of H9c2 cells. The oxidative stress of H9c2 was manifested by the decrease of SOD activity, the increase of ROS and MDA levels, and the apoptosis of H9c2 was shown by the increase of caspase-3 activity and apoptosis rate. MiR-18-5p mimic was transfected into H9c2 cells and successfully up-regulated miR-18-5p. And overexpression of miR-18-5p markedly inhibited the oxidative stress and apoptosis caused by hypoxia in H9c2 cells. Through bioinformatics analysis and Dual-Luciferase reporter gene assay, RUNX1 was proved to have binding sites for miR-18-5p. Furthermore, knocking down RUNX1 using small interfering RNA-RUNX1 (siR-RUNX1) significantly protected H9c2 cells from oxidative stress and apoptosis. Conclusions: MiR-18-5p expression was decreased in hypoxia-treated H9c2 cells. Overexpression of miR-18-5p alleviated hypoxia-induced oxidative stress and apoptosis in H9c2 cells via targeting RUNX1.