LncRNA CRYBG3 Regulates Adaptive Radioresistance in Non-Small Cell Lung Cancer Cells through the p53/HSF1/TRAP1 Axis

Objectives: Fractionated radiotherapy represents a standardized and widely adopted treatment modality for cancer management, with approximately 40% of non-small cell lung cancer (NSCLC) patients receiving it. However, repeated irradiation may induce radioresistance in cancer cells, reducing treatment effectiveness and raising recurrence risk. The long noncoding RNA CRYBG3 (lncRNA CRYBG3), which is upregulated in lung cancer cells after X-ray irradiation, contributes to the radioresistance of NSCLC cells by promoting wild-type p53 protein degradation. This study aims to elucidate the mechanism of fractionated irradiation-induced radioresistance, in which lncRNA CRYBG3 regulates radiation-induced mitochondrial damage and reactive oxygen species (ROS) generation through the p53 downstream signaling pathway. Methods: To investigate the critical roles of lncRNA CRYBG3 in mediating radioresistance induced by fractionated irradiation in NSCLC, we established radioresistant NSCLC cells by irradiating the A549 and H460 cell lines with 60 Gy of X-rays in 12 fractions, and named the radioresistant cells A549R and H460R, respectively. Lentiviral vectors were used to deliver short hairpin RNA (shRNA) into cells to knock down lncRNA CRYBG3, thereby investigating its contribution to adaptive radioresistance in A549R and H460R cells. All cells were irradiated with 4 Gy of X-rays, and subsequent analyses were conducted to evaluate mitochondrial damage, ROS generation, apoptosis, and the expression of oxidative stress-related proteins. Results: Increased expression levels of lncRNA CRYBG3 were positively associated with the acquisition of radioresistance in NSCLC cells. Additionally, suppressing lncRNA CRYBG3 increased mitochondrial damage and promoted radiation-induced apoptosis in radioresistant NSCLC cells. Mechanistically, the downregulation of lncRNA CRYBG3 led to increased p53 levels, resulting in decreased expression of heat shock factor 1 (HSF1) and tumor necrosis factor receptor-associated protein 1 (TRAP1), as well as enhanced radiation-induced mitochondrial oxidative damage and apoptosis. Conclusion: The results indicate that lncRNA CRYBG3 plays a regulatory role in adaptive radioresistance in NSCLC cells through the p53/HSF1/TRAP1 axis. Therefore, targeting lncRNA CRYBG3 could potentially improve the efficacy of fractionated radiotherapy in NSCLC.