Cisplatin (DDP) remains a primary chemotherapeutic agent for treating non-small cell lung cancer (NSCLC), but the development of drug resistance limits its clinical efficacy. This study aimed to explore the role of RASSF1A in modulating DDP resistance in NSCLC and to elucidate the underlying molecular mechanisms. Expression levels of RASSF1A and microtubule-associated protein 1S (MAP1S) were assessed using qRT-PCR and Western blotting, while their interaction was verified by co-immunoprecipitation (Co-IP). The half-maximal inhibitory concentration (IC50) of DDP was determined for A549 and DDP-resistant A549/DDP cells. A549/DDP cells were transfected with pCDNA3.1-RASSF1A, pCDNA3.1-MAP1S, or si-RASSF1A and subsequently treated with DDP. Cell viability was evaluated using CCK-8 and 5-ethynyl-2ΚΉ-deoxyuridine (EDU) assays. Autophagy-related protein levels, including p62, LC3I, and LC3II, were measured via Western blot, and GFP-LC3 puncta formation was examined using immunofluorescence. Additionally, a xenograft mouse model was established using A549/DDP cells to validate in vivo effects. Both RASSF1A and MAP1S were downregulated in NSCLC tissues and displayed a positive correlation. Overexpression of RASSF1A or MAP1S in A549 and A549/DDP cells enhanced DDP-induced cytotoxicity and increased autophagic activity. Mechanistic studies revealed that RASSF1A regulates MAP1S to inhibit the Keap1-Nrf2 pathway, thereby promoting autophagy and improving chemosensitivity. These effects were further corroborated in the in vivo xenograft model. RASSF1A enhances the sensitivity of NSCLC cells to cisplatin by promoting autophagy through MAP1S-mediated inhibition of the Keap1-Nrf2 pathway, offering potential insights for overcoming chemotherapy resistance.
