E2F2 confers cisplatin resistance in lung squamous cell carcinoma via HUWE1/H2AX-mediated DNA damage repair

Cisplatin (DDP) is a first-line chemotherapeutic agent for lung squamous cell carcinoma (LUSC). However, the development of DDP resistance driven by enhanced DNA damage repair (DDR) remains a major clinical hurdle that leads to therapeutic failure and tumor relapse. While the transcription factor E2F2 is implicated in tumor progression, its specific contribution to DDP resistance and the underlying molecular networks in LUSC remain poorly understood. E2F2 expression in LUSC tissues was analyzed using TCGA datasets and verified at both clinical and cellular levels. The biological role of E2F2 in DDP resistance was comprehensively evaluated in vitro using CCK-8, Transwell, immunofluorescence, and flow cytometry assays.and in vivo using a murine xenograft model. Mechanistic investigations, integrating bioinformatics, chromatin immunoprecipitation (ChIP), Co-IP, and ubiquitination assays, were conducted to delineate the E2F2-driven transcriptional network and its downstream impact on DDR. E2F2 was significantly upregulated in both LUSC tissues and DDP-resistant models. Functionally, silencing E2F2 not only significantly reduced the DDP IC 50 and impaired the viability and migratory capacity of DDP-resistant LUSC cells, but also markedly sensitized them to DDP-induced apoptosis. Furthermore, E2F2 knockdown exacerbated DDP-induced DNA damage in vitro and profoundly suppressed tumor growth in vivo. Mechanistically, E2F2 directly bound to the promoter of HUWE1, thereby activating its transcription. The resulting E2F2-driven upregulation of HUWE1 in turn promoted H2AX ubiquitination and proteasomal degradation through protein-protein interactions, thereby accelerating DNA damage repair. In the in vivo experiments, E2F2 knockdown markedly suppressed tumor growth and reduced the phosphorylation levels of key DNA damage repair-related proteins in tumor tissues, whereas concomitant overexpression of HUWE1 effectively reversed these effects. This E2F2-driven HUWE1 upregulation subsequently promotes the ubiquitination and degradation of H2AX, thereby accelerating DDR and ultimately conferring robust DDP resistance in LUSC cells. E2F2 drives cisplatin resistance in LUSC by orchestrating the HUWE1/H2AX-mediated DDR cascade. Our findings highlight the E2F2/HUWE1 axis as a promising therapeutic vulnerability to overcome chemoresistance in LUSC.