miR-320a enhances radiosensitivity in non-small cell lung cancer by targeting RAD51 and modulating ferroptosis via GPX4

Radiotherapy is an essential treatment for non-small cell lung cancer (NSCLC), but its effectiveness is often reduced by radioresistance. miR-320a has been shown to improve radiosensitivity in NSCLC, but the molecular mechanisms are not well understood. This study investigates how miR-320a regulates RAD51 to affect the radiosensitivity of NSCLC. miR-320a expression in NSCLC tissues and cell lines was evaluated using The Cancer Genome Atlas (TCGA) data and qRT-PCR. RAD51 was predicted as a miR-320a target using bioinformatic tools (TargetScan, miRDB, miRTarBase) and validated by dual-luciferase reporter assays. Functional experiments were conducted to examine the effects of miR-320a and RAD51 manipulation on NSCLC cell responses to varying radiation doses. Ferroptosis was examined by measuring lipid reactive oxygen species (ROS) and GPX4 expression levels. miR-320a expression was markedly reduced in NSCLC tissues and cell lines relative to normal controls and showed a positive association with clinical radiosensitivity. Functional experiments demonstrated that miR-320a overexpression increased radiosensitivity by inhibiting post-irradiation cell proliferation, colony formation, and migration. RAD51 was validated as a direct post-transcriptional target of miR-320a. Mechanistically, RAD51 expression inversely correlated with miR-320a (R = -0.16, P < 0.001) and was associated with reduced radiosensitivity both in vitro and in patient samples. Importantly, RAD51 knockdown reversed the radioresistance induced by miR-320a inhibition. Further analyses revealed that RAD51 positively regulated GPX4 expression, thereby suppressing ferroptosis. Inhibition of RAD51 or restoration of miR-320a led to enhanced lipid peroxidation, as evidenced by increased lipid ROS accumulation and reduced GPX4 expression, ultimately sensitizing NSCLC cells to radiotherapy. Our results indicate that miR-320a promotes NSCLC radiosensitivity through a negative regulation of RAD51. The miR-320a/RAD51/GPX4 axis may be used as a key pathway in regulating NSCLC radiosensitivity.