KLF11 interacts with MDM2 to stabilize E2F1 and promotes DNA damage repair to induce radioresistance in esophageal cancer cells.

This study aimed to investigate the function of KLF11 in regulating radiosensitivity (RT) in esophageal squamous cell carcinoma (ESCC) and to elucidate the underlying mechanisms. A nude mouse ESCC xenograft model was established by injecting KYSE150 cells into the left dorsal flank. Cell proliferation was assessed using cell counting kit-8 (CCK-8) and colony formation assays, while DNA damage was evaluated via a neutral comet assay. Key gene and protein expression levels were analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), Western blotting, and immunohistochemistry. Additionally, coimmunoprecipitation and immunofluorescence were employed to validate proteinprotein interactions. KLF11 expression was upregulated in both ESCC and RT-resistant tissues. At the cellular level, KLF11 expression was higher in ESCC cell lines than in the normal esophageal epithelial cell line HET-1A, with the most pronounced upregulation in KYSE150 cells and the least in TE1 cells. Notably, KLF11 knockdown under ionizing radiation exposure suppressed proliferation and colony formation, promoted apoptosis, and increased the expression of the DNA damage marker γ-H2AX as well as overall DNA damage levels in KYSE150 cells. Conversely, KLF11 overexpression in TE1 cells led to the opposite phenotype, suggesting that KLF11 confers RT resistance in ESCC by mitigating DNA damage. Further investigations revealed that KLF11 primarily repairs RT-induced DNA damage through the homologous recombination (HR) pathway rather than through nonhomologous end joining (NHEJ). Additionally, the expression of MDM2, E2F1, and RAD51 was significantly elevated in ESCC and RT-resistant ESCC tissues. Mechanistically, KLF11 promotes MDM2 expression, which inhibits E2F1 ubiquitination, thereby stabilizing E2F1 protein levels and enhancing RAD51-mediated HR repair, ultimately leading to RT resistance in ESCC. This study elucidates the critical role and molecular mechanism through which KLF11 drives radiotherapy resistance in ESCC by regulating the MDM2/E2F1 axis and enhancing HR repair, thereby providing a solid theoretical foundation and potential target for the development of KLF11-targeted radiosensitization therapies for ESCC.