Abstract 5796: Inhibition of oxidative phosphorylation leads to immunogenic cell death in ovarian cancer

Abstract Developing new therapies that are effective against localized and disseminated epithelial ovarian cancer (EOC) is imperative. Oxidative phosphorylation (OXPHOS) has been linked to chemoresistance and stemness in EOC, making it an interesting treatment target for this disease. Our laboratory has previously demonstrated that the OXPHOS inhibitor atovaquone has antitumorigenic effects against EOC. However, the precise mechanisms underlying these effects have not been fully elucidated. We adopted an RNA sequencing approach to characterize the transcriptional changes induced by atovaquone in EOC cells. Our findings revealed that atovaquone not only disrupts pathways associated with cellular homeostasis and metabolism but also activates stress responses and primes immune recognition. We show that atovaquone leads to the activation of the Protein Kinase RNA-Like ER Kinase (PERK) branch of the ER stress response, which has been linked to immunogenic cell death. During ER stress, the ER protein calreticulin is translocated to the plasma membrane where it functions as a Damage-Associated Molecular Pattern (DAMP). DAMPs are intracellular molecules that have been translocated to the plasma membrane or released into the extracellular environment where they activate a cascade of immune responses. Our findings suggest that calreticulin is upregulated in the plasma membrane of EOC cells treated with atovaquone. In parallel, we also found an increase of other DAMPs, including High Mobility Group Box 1 (HMGB1) and Mitochondrial Transcription Factor A (TFAM), in the supernatant of atovaquone-treated cells, suggesting that these injured cells are releasing immunogenic molecules. Moreover, we demonstrate that natural killer cells co-cultured with atovaquone-treated EOC cells have increased activity when compared to those co-cultured with vehicle-treated EOC cells. Altogether, we show that the disruption of the OXPHOS converges with the activation of ER stress to promote immunogenic cell death and activate innate immune responses. Atovaquone’s potential to boost cellular immunotherapies opens a new avenue for its use as a combination agent for the treatment of EOC. Citation Format: Mayra A. Betancourt Ponce, Nicha Boonpattrawong, Alex J. Fagan, Manish Patankar, Lisa Barroilhet. Inhibition of oxidative phosphorylation leads to immunogenic cell death in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5796.