Key Molecular Events in PM_2.5-Induced Lung Injury: Autophagy and Ferroptosis Mediated by the miR-212-5p/RASSF1 Axis

Fine particulate matter (PM_2.5) can directly impact pulmonary epithelial cells, resulting in lung injury. While it is known that PM_2.5 can alter the expression profile of microRNAs in the lung, its specific role in damaging pulmonary epithelial cells remains unclear. This study, therefore, employed RT-qPCR, Western blotting, and dual luciferase reporter assays to investigate the regulatory role of microRNAs in PM_2.5-induced cellular damage. PM_2.5 exposure induces oxidative stress, autophagy, and ferroptosis in rat lung alveolar epithelial cells (RLE-6TN). Further functional rescue experiments confirm that the ferroptosis-specific inhibitor Fer-1 can block PM_2.5-induced ferroptosis. Bioinformatics analysis and validation indicate that miR-212-5p plays a crucial role by negatively regulating RASSF1 through targeted inhibition. Overexpression of miR-212-5p activates the PI3K/AKT signaling pathway, thereby promoting autophagy and ferroptosis. However, when the expression of both miR-212-5p and RASSF1 is suppressed, PM_2.5-induced autophagy and ferroptosis are significantly alleviated by inhibiting the PI3K/AKT/mTOR signaling pathway. Rescue validation experiments demonstrated that, under PM_2.5 exposure combined with RASSF1 overexpression, miR-212-5p exacerbates the aforementioned cellular damage process. This study reveals that miR-212-5p regulates autophagy and ferroptosis by targeting RASSF1. These findings provide a multi-target intervention strategy for PM_2.5-related lung diseases.