TSPAN8-mediated Epithelial-mesenchymal Transition Drives Acquired Radioresistance in Cervical Cancer

Acquired radioresistance remains a major obstacle to effective radiotherapy for cervical cancer, often driven by epithelial-mesenchymal transition (EMT). This study reveals TSPAN8 as a novel regulator of EMT-mediated radioresistance, offering new insights for overcoming treatment failure. Radioresistant subclones of HeLa-R25 and SiHa-R25 cells were established by repeated 2 Gy fractions. Radioresistance, apoptosis, EMT, and stemness were assessed by clonogenic survival, flow cytometry, immunoblotting, and immunofluorescence. Differentially expressed genes were identified by microarray, validated by protein-protein interaction analysis and co-immunoprecipitation, and functionally examined via TSPAN8 overexpression/knockdown, xenograft models, and immunohistochemistry of primary, metastatic, and recurrent post-radiotherapy specimens. Prognostic relevance was analyzed in the TCGA-CESC cohort. Fractionated irradiation induced EMT and radioresistance, with significantly higher clonogenic survival in R25 cells (P < 0.05), characterized by E-cadherin loss, N-cadherin/Vimentin upregulation, and increased CD44/Oct4. TSPAN8 was the most upregulated gene and directly interacted with E-cadherin. Overexpression enhanced EMT, invasion, and resistance to apoptosis, while knockdown reversed these effects and restored radiosensitivity in vivo. TSPAN8 knockdown in radioresistant xenografts significantly suppressed tumor growth (P < 0.05), and combined knockdown with irradiation further reduced tumor volume (P < 0.05). In patient samples, post-radiotherapy recurrences and metastases exhibited high TSPAN8 and vimentin with reduced E-cadherin. TCGA data confirmed that elevated TSPAN8 was associated with worse outcomes, including shorter disease-specific survival (HR = 2.02, 95% CI 1.01-3.71, P = 0.02) and progression-free survival (HR = 3.09, 95% CI 1.80-5.30, P < 0.001). These data suggest that TSPAN8 drives EMT-mediated radioresistance in cervical cancer, is associated with recurrence and poor survival, and represents a potential biomarker and therapeutic target. Targeting TSPAN8 may enhance radiosensitivity and improve personalized radiotherapy outcomes.