Abstract
The aim of the present study was to investigate the expression of microRNA (miRNA/miR)-214 in the sera of elderly patients with acute myocardial infarction (AMI) and the mechanism of how its expression affects cardiomyocyte apoptosis in these patients. The expression levels of miRNA-214 in elderly patients with AMI, unstable angina (UA) and healthy elderly subjects were detected by reverse transcription-quantitative polymerase chain reaction, and the correlation between the relative expressions of sera miRNA-214 and myocardial enzymes in elderly patients with AMI was examined by Pearson's analysis. Human cardiomyocyte (HCM) cell lines with a high expression miRNA-214 were established. The apoptotic rates of the different groups of cells were detected by flow cytometry and TUNEL assay. The expression of miRNA-214 target genes in the different groups of cells was detected by western blot assay. The relative expression levels of sera miR-214 in elderly AMI patients, UA patients and healthy subjects (as determined by physical examination) were 15.79±4.66, 4.60±2.51 and 2.07±0.99, respectively. The differences between each group were statistically significant (P<0.05). The relative expression of sera miRNA-214 in elderly AMI patients was positively correlated with sera aspartate aminotransferase (r=0.361, P=0.0174), lactate dehydrogenase (r=0.425, P=0.0045), creatine kinase-MB (r=0.835, P<0.001) and cardiac troponin (r=0.770, P<0.001). When compared with normal HCMs, the expressions of p53-upregulated modulator of apoptosis (PUMA), phosphatase and tensin homolog (PTEN), B-cell lymphoma-2-associated X protein (Bax) and caspase 7 proteins was decreased in HCMs overexpressing miRNA-214 following H2O2 induction, and the rate of apoptosis decreased by 63.64, 21.95, 46.67 and 50.05%, respectively. miRNA-214 was highly expressed in the sera of elderly patients with AMI, which may inhibit myocardial cell apoptosis by inhibiting the expression of miR-214 target genes including PUMA, PTEN, Bax and caspase 7.