MicroRNA-222 alleviates radiation-induced apoptosis by targeting BCL2L11 in cochlea hair cells.

Radiation-induced hair cell injury is detrimental for human health but the underlying mechanism is not clear. MicroRNAs (miRNAs) have critical roles in various types of cellular biological processes. The present study investigated the role of miR-222 in the regulation of ionizing radiation (IR)-induced cell injury in auditory cells and its underlying mechanism. Real time PCR was performed to identify the expression profile of miR-222 in the cochlea hair cell line HEI-OC1 after IR exposure. miRNA mimics or inhibitor-mediated upregulation or downregulation of indicated miRNA was applied to characterize the biological effects of miR-222 using MTT, apoptosis and DNA damage assay. Bioinformatic analyses and luciferase reporter assays were applied to identify a miRNA target gene. Our study confirmed that IR treatment significantly suppressed miR-222 levels in a dose-dependent manner. Upregulation of miR-222 enhances cell viability and alleviated IR-induced apoptosis and DNA damage in HEI-OC1 cells. In addition, BCL-2-like protein 11 (BCL2L11) was validated as a direct target of miR-222. Overexpression of BCL2L11 abolished the protective effects of miR-222 in IR-treated HEI-OC1 cells. Moreover, miR-222 alleviated IR-induced apoptosis and DNA damage by directly targeting BCL2L11.The present study demonstrates that miR-222 exhibits protective effects against irradiation‑induced cell injury by directly targeting BCL2L11 in cochlear cells.