CIRC_0068655 SILENCING AMELIORATES HYPOXIA-INDUCED HUMAN CARDIOMYOCYTE INJURY BY REGULATING APOPTOTIC AND INFLAMMATORY RESPONSES

Background: There is growing evidence suggesting that the dysregulation of circular RNAs (circRNAs) plays a significant role in various myocardial disorders, including myocardial ischemia. This study aimed to explore the function of hsa_circ_0068655 (circ_0068655) in hypoxia-induced cardiomyocyte injury. Methods: Human AC16 cardiomyocyte cells were cultured under anaerobic condition to induce an in vitro model of myocardial ischemia. Cell apoptosis was assessed by Annexin V-fluorescein isothiocyanate staining and caspase-3 and caspase-9 activity assays. Cell proliferation was analyzed by 5-ethynyl-2'-deoxyuridine incorporation assay. Inflammation was evaluated by enzyme-linked immunosorbent assays. Circ_0068655, miR-370-3p, and BCL-2-like 11 (BCL2L11) expression were detected by real-time quantitative polymerase chain reaction or western blotting. The target interactions among circ_0068655, miR-370-3p, and BCL2L11 were predicted using bioinformatics tools and validated using dual-luciferase reporter assays and RNA immunoprecipitation assays. Results: Hypoxia treatment led to upregulated expression of circ_0068655 and BCL2L11, and downregulated expression of miR-370-3p in AC16 cells. This treatment also resulted in reduced cell viability, increased apoptosis rate, elevated caspase-9/3 activities and cleavage, and enhanced production of TNF-α, IL-6, and IL-1β. Notably, knockdown of circ_0068655 alleviated these detrimental effects. In addition, circ_0068655 silencing-mediated effects were restored by decreasing miR-370-3p expression in hypoxia-treated AC16 cells. Moreover, ectopic BCL2L11 expression remitted the effects of miR-370-3p overexpression on hypoxia-treated AC16 cells. Mechanistically, circ_0068655 was found to act as a sponge for miR-370-3p, thereby regulating BCL2L11 expression. Conclusion: Circ_0068655 silencing ameliorated hypoxia-induced human cardiomyocyte injury through the miR-370-3p/BCL2L11 axis.