The EGR1/miR-139/NRF2 axis orchestrates radiosensitivity of non-small-cell lung cancer via ferroptosis.

Radiotherapy is one of the predominant treatment modalities for almost all kinds of malignant cancers, including non-small cell lung cancer (NSCLC). Increasing evidence shows that ionizing radiation (IR) induces reactive oxygen species (ROS) leading to lipid peroxidation and subsequently ferroptosis of cancer cells. However, cancer cells evolve multiple mechanisms against ROS biology resulting in resistance to ferroptosis and radiotherapy, of which NRF2 signaling is one of the most studied. In the current research, we identified that microRNA-139 (miR-139) could be a novel radiosensitizer for NSCLC by inhibiting NRF2 signaling. We found that miR-139 possessed great potential as a diagnostic biomarker for NSCLC and multiple other types of cancer. Overexpression of miR-139 increased radiosensitivity of NSCLC cells in vitro and in vivo. MiR-139 directly targeted cJUN and KPNA2 to impair NRF2 signaling resulting in enhanced IR-induced lipid peroxidation and cellular ferroptosis. We proved KPNA2 to be a binding partner of NRF2 that involved in nuclear translocation of NRF2. Moreover, we found that IR induced miR-139 expression through transcriptional factor EGR1. EGR1 bound to the promoter region and transactivated miR-139. Overall, our findings elucidated the effect of EGR1/miR-139/NRF2 in IR-induced ferroptosis of NSCLC cells and provided theoretical support for the potential diagnostic biomarkers and therapeutic targets for the disease.