RHOV Is a Detachment-Responsive Rho GTPase Necessary for Ovarian Cancer Peritoneal Metastasis.

UNLABELLED: A defining feature of epithelial ovarian cancer, irrespective of histologic subtype, is its predominant spread through transcoelomic metastasis, in which tumor cells disseminate into the peritoneal fluid, resist anoikis, and form multicellular aggregates that invade the peritoneum. This tumor progression represents the main driver of mortality for patients with ovarian cancer. Identification of the earliest adaptations necessary for metastasizing ovarian cancer cells to survive matrix detachment could help develop strategies to prevent the initiation of transcoelomic metastasis. In this study, we identified a conserved detachment-sensitive gene signature activated shortly after matrix detachment across multiple ascites-derived ovarian cancer cell lines. Within this signature, RHOV, an atypical and fast-cycling Rho GTPase, emerged as a top transcript that was confirmed to be highly induced in patient ascites-derived cells. Loss of RHOV impaired anoikis resistance, multicellular aggregate compaction, migration, and invasion in vitro, and it completely abolished metastasis in vivo. Mechanistically, RHOV enhanced c-Jun signaling and cytoskeletal remodeling to support prometastatic signaling. Rescue experiments showed that both GTP binding and membrane localization were required for the prometastatic function of RHOV. Together, these findings define RHOV as a unique detachment-sensitive Rho GTPase and establish RHOV as a critical and necessary mediator of early adaptations that prime ovarian cancer cells for peritoneal metastatic progression. This work provides key insights into the molecular vulnerabilities of disseminating tumor cells, establishes the targeting of early molecular adaptations following matrix detachment as a potential therapeutic strategy for metastatic disease, and uncovers functions of an understudied member of the Rho GTPase family.

SIGNIFICANCE: Identification of a detachment-sensitive transcriptional signature in ovarian cancer uncovers RHOV as an essential mediator of transcoelomic metastasis, establishing these early adaptations as crucial regulators of peritoneal metastasis and potential therapeutic targets.