Abstract 3112: Targeting chemoresistance in ovarian cancer

Abstract Introduction: Ovarian cancer (OvCa) is a highly aggressive malignancy characterized by frequent relapse and metastasis, both of which contribute to its high mortality rate. Although most patients initially respond to platinum-based chemotherapy, up to 80% eventually develop resistance, rendering OvCa largely incurable. Therefore, there is an urgent need to identify new therapeutic targets and develop strategies to overcome chemoresistance. This study identifies integrin β4 (ITGB4) as a key molecular driver associated with cisplatin resistance and explores its potential as a therapeutic target in ovarian cancer. Methods: Transcriptomic profiling of cisplatin-sensitive (WT) and cisplatin-resistant (CPR) OVCAR8 OvCa spheroids was performed using RNA sequencing to identify differentially expressed genes associated with chemoresistance. Selected candidates were validated by qRT-PCR, and western blotting. The clinical significance of ITGB4 was assessed using publicly available datasets (GSE133859, TCGA-OV) and immunofluorescence analysis of tissue microarray from primary and recurrent OvCa patient samples. Functional roles of ITGB4 were examined using genetic manipulations (overexpression and CRISPR-mediated knockout) followed by migration, invasion, and cisplatin sensitivity assays. Co-immunoprecipitation (Co-IP) was performed to examine the interaction between ITGB4 and TGFβ receptor 2 (TGFβR2). Results: Transcriptomic profiling revealed ITGB4 overexpression and SERPINB2 downregulation in CPR spheroids, findings that were consistent with GEO, TCGA-OV datasets as well as TMA analysis of patient samples. High ITGB4 expression in platinum-resistant OvCa patients was significantly associated with worse overall and progression-free survival. Functionally, ITGB4 overexpression enhanced cell invasion, migration, and cisplatin resistance, while ITGB4 knockout resensitized resistant cells to cisplatin and suppressed their invasive phenotype. Mechanistically, ITGB4 activated FAK and TGFβ/SMAD signaling pathways, both of which are known mediators of EMT and chemoresistance. CO-IP assays demonstrated a direct interaction between ITGB4 and TGFβR, supporting a cooperative role in promoting SMAD3 activation. Conclusion: This study identifies ITGB4 as a central regulator of cisplatin resistance and aggressiveness in ovarian cancer and highlights ITGB4 as a promising therapeutic target to overcome chemoresistance and improve treatment outcomes in OvCa patients. Acknowledgment of Funding: The work is supported by COBRE P20GM135009, SCC CT Pilot Grant, PHF-Seed and PHF CTGA Grant Program. Citation Format: Dhanamjai Penta, Vishal Chandra, Lauren Dockery, Rajani Rai. Targeting chemoresistance in ovarian cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3112.