Abstract B026: Cystathionine beta-synthase: A metabolic enzyme regulating ovarian cancer metastasis

Abstract Background: Ovarian cancer (OvCa) is the most lethal gynecologic malignancy, driven by early metastasis, high recurrence rates, and therapy resistance. High-grade serous ovarian cancer (HGSOC), the most common and aggressive subtype, accounts for ∼70% of epithelial OvCa cases. A key feature of OvCa metastasis is the ability of tumor cells to resist anoikis—a form of programmed cell death triggered by detachment—allowing them to survive as spheroids in the peritoneal cavity. This anoikis resistance (AR) contributes to both metastatic spread and therapeutic failure. Identifying molecular regulators of AR is critical for developing new treatments to prevent metastasis and improve patient outcomes. Hypothesis: Our previous work has identified cystathionine beta-synthase (CBS), a hydrogen sulfide (H2S)-producing enzyme, as a potential driver of OvCa progression. CBS enhances lipogenesis, mitochondrial fusion, and is associated with poor survival in late-stage OvCa. We hypothesize that CBS promotes AR in OvCa, and that targeting CBS could suppress metastasis and drug resistance. Methods and Results: We investigated the role of CBS in AR using ovarian cancer cell lines (COV318, OVCAR8, and A2780_CP20). CBS was silenced via siRNA, and cellular phenotypes were evaluated in both 2D monolayer and 3D spheroid cultures. Our results revealed that: (i) CBS knockdown induces anoikis across all three cell lines; (ii) loss of CBS disrupts integrin-mediated focal adhesion kinase (FAK) signaling and alters spheroid morphology; (iii) CBS expression is positively associated with markers of stemness and epithelial-to-mesenchymal transition (EMT); and (iv) CBS is essential for metastatic spheroid adhesion to secondary sites, as demonstrated by fibronectin adhesion, mesothelial clearance assays, and an in vivo homing model. Notably, supplementation with H2S—a product of CBS activity via the transsulfuration pathway—rescued the phenotypic effects of CBS silencing in both in vitro and in vivo models, supporting a key functional role for H2S in CBS-mediated regulation of AR. Conclusion: CBS is a key regulator of AR in OvCa and represents a promising therapeutic target to inhibit metastasis and enhance chemotherapy response. Citation Format: Geeta Rao, Pallab Shaw, Shailendra Dwivedi, Resham Bhattacharya, Priyabatra Mukherjee. Cystathionine beta-synthase: A metabolic enzyme regulating ovarian cancer metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr B026.