NOP58 modulates radiosensitivity in non-small cell lung cancer via DDX18-mediated DNA damage repair.

Non-small cell lung cancer (NSCLC) constitutes 80-85% of lung cancers, with advanced cases showing a 20-30% 5-year survival rate. Radiation resistance limits radiotherapy efficacy, and the function of NOP58 in this process is unknown. This study investigated the mechanisms of NOP58 in NSCLC radioresistance. A radiation-resistant NSCLC cell line (H1299R) was established. Bioinformatic analysis of the Cancer Genome Atlas Program data revealed that high NOP58 expression correlates with poor patient prognosis. The expression levels of NOP58 and DDX18 expression were quantified via quantitative real-time polymerase chain reaction and Western blot. Radiosensitivity of H1299R cells and parental H1299 cells was assessed under irradiation (0, 2, 4, 6 and 8 Gy). Cell viability was assessed using cell counting kit-8 and colony formation assays. Apoptosis was detected by flow cytometry with Annexin V/PI staining. DNA damage was analyzed via γ-H2AX immunofluorescence and comet assays. NOP58 knockdown and DDX18 overexpression were performed for rescue experiments, and protein interaction was validated by pull-down assays. NOP58 and DDX18 were significantly upregulated in H1299R cells. H1299R cells exhibited higher cell viability, stronger colony-forming capacity, reduced apoptosis and less DNA damage under irradiation treatment. The depletion of NOP58 in H1299 and H1299R cells exacerbated radiation-induced DNA damage, reduced cell viability and promoted apoptosis, reversing radioresistance. Direct interaction between NOP58 and DDX18 was confirmed by pull-down assay. DDX18 overexpression reversed the radiosensitizing effects of NOP58 knockdown, including attenuated DNA damage and restored cell survival. Overexpression NOP58 converted radiosensitive cells to a resistant phenotype. NOP58 promotes NSCLC radioresistance by interacting with DDX18, regulating its expression and thereby suppressing radiation-induced DNA damage. The NOP58-DDX18 axis could be a promising therapeutic target for improving radiotherapy efficacy in NSCLC.