Radioresistance in esophageal squamous cell carcinoma (ESCC) contributes to locoregional recurrence and radiotherapy failure. Radiotherapy has been demonstrated to induce Gasdermin E (GSDME)-mediated pyroptosis. This study aims to identify druggable targets and develop novel targeted radiosensitization strategies by focusing on GSDME. The activation of GSDME-mediated pyroptosis by X-ray irradiation in ESCC cells was confirmed by microscopic observation, inflammatory cytokine release assays, and western blot analysis. To delineate the functional roles of GSDME following its knockdown and reconstitution in ESCC cells, we evaluated proliferation using cell counting and EdU assays, migration using wound healing and Transwell assays, and radiosensitivity using a combination of colony formation, Cell Counting Kit-8 (CCK-8), and propidium iodide (PI) staining assays. Mechanistic downstream signaling pathways were identified by western blotting and RNA sequencing, and pharmacological inhibition validated these mechanisms both in vitro and in nude mouse models. X-ray irradiation induced GSDME-mediated pyroptosis in ESCC cells. Notably, GSDME downregulation promoted tumor cell proliferation, migration, and radioresistance. Conversely, GSDME reconstitution reversed these phenotypes and restored radiosensitivity. Mechanistically, GSDME knockdown decreased the expression of signaling lymphocytic activation molecule factor 7 (SLAMF7), which further upregulated tumor necrosis factor receptor–associated factor 6 (TRAF6) and ultimately activated the NF-κB signaling pathway. Pharmacological inhibition of NF-κB with BAY 11-7082 in GSDME-low ESCC cells suppressed proliferation and migration, and enhanced radiosensitivity both in vitro and in vivo. GSDME functions as a tumor suppressor by enhancing radiosensitivity and inhibiting proliferation and migration in ESCC, through the suppression of the NF-κB signaling pathway. These findings nominate GSDME as a promising biomarker and the NF-κB signaling pathway as a therapeutic target for overcoming radioresistance in ESCC.
Lei et al. (Tue,) studied this question.