Abstract 4855: Cystathionine beta-synthase drives transcoelomic metastasis in ovarian cancer

Abstract Ovarian cancer (OvCa) disseminates predominantly by transcoelomic metastasis, where exfoliated tumor cells survive as multicellular spheroids, adhere to the omentum, and establish peritoneal invasion. This process is largely dependent on spheroid viability (anoikis resistance) and efficient omental adhesion. We investigated whether the cystathionine β-synthase (CBS), which has been previously associated with other aspects of OvCa progression, can also functionally drive intraperitoneal metastasis. We integrated (i) publicly available multi-cohort patient data with survival analyses, (ii) an in-house HGSOC tissue microarray (TMA; n=109) scored for CBS with clinicopathologic correlation to peritoneal/omental metastasis, and (iii) mechanistic assays involving OvCa 2D monolayer and 3D spheroid models, including proteomics, to identify key players of CBS-mediated metastasis. High CBS expression was found to be positively correlated with worse patient survival and with clinically observed peritoneal/omental metastasis in the TMA cohort. Functionally, CBS maintained spheroid viability and compact architecture by stabilizing SP1 and sustaining ITGB1, a key mediator of mesothelial adherence on omentum via its interaction with fibronectin engagement. CBS silencing deteriorated spheroid structure, reduced CD24+ subpopulations, downregulated EMT/stemness programs, and attenuated omental homing in vivo. Further, H2S supplementation restored SP1 along with ITGB1, causing promulgated fibronectin adhesion, and spheroid survival, supporting a causal CBS→H2S→SP1→ITGB1 pathway as the underlying mechanism of CBS-mediated OvCa transcoelomic metastasis. Therefore, the CBS-SP1-ITGB1 axis mechanistically facilitates the survival and omental adhesion of metastatic spheroids, underscoring CBS’s candidacy as a target for anti-metastatic therapy. Citation Format: Pallab Shaw, ARPAN DEY BHOWMIK, Akrit Pran Jaswal, Resham Bhattacharya, Priyabrata Mukherjee, Shailendra Kumar Dwivedi, Geeta Rao. Cystathionine beta-synthase drives transcoelomic metastasis 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 4855.