Catechin protects rat cardiomyocytes from hypoxia-induced injury by regulating microRNA-92a.

Background: Myocardial infarction (MI) is a serious condition, caused by acute, persistent ischemia or hypoxia of a coronary artery and responsible for heart failure and sudden death. This study aimed to investigate the effects of catechin, one of the main active components of green tea, on hypoxia-induced MI cell model, as well as the underlying possible mechanism. Methods: Cell viability, proliferation, apoptosis, and the expression of microRNA-92a (miR-92a) after hypoxia stimulation and/or catechin treatment were assessed using cell counting kit-8 (CCK-8) assay, western blotting, annexin V-FITC/PI staining and qRT-PCR, respectively. miRNA transfection was performed to change the expression of miR-92a. The effects of miR-92a on hypoxia and catechin-treated H9c2 cell viability, proliferation and apoptosis were evaluated. Finally, western blotting was conducted to measure the expression of core factors in the c-Jun N-terminal kinase (JNK) signaling pathway. Results: Hypoxia stimulation significantly inhibited H9c2 cell viability and proliferation, induced cell apoptosis and up-regulated miR-92a expression. Catechin markedly protected H9c2 cells from hypoxia-induced viability loss, proliferation inhibition, and apoptosis enhance, as well as miR-92a expression increase. Furthermore, suppression of miR-92a enhanced the protective effects of catechin on hypoxia-induced H9c2 cells. Overexpression of miR-92a had opposite effects. Catechin activated the JNK pathway in H9c2 cells by down-regulating miR-92a. Conclusion: Catechin protected H9c2 cells from hypoxia-induced injury by regulating miR-92a and JNK signaling pathway. Our findings facilitate the understanding of the protective activity of catechin in hypoxia-induced MI cell injury and provide a theoretical basis for further explore treatment of MI by using catechin.