Identification of Detachment-Responsive Transcripts in Ovarian Cancer

Transcoelomic dissemination is the predominant route of ovarian cancer metastasis and a major driver of patient mortality. In our pursuit to identify novel tumor cell adaptations necessary for metastatic spread, we identified a conserved transcriptomic signature activated shortly after matrix-detachment across multiple ascites-derived cell lines and patient specimens. Within this signature, RHOV, an atypical and constitutively active Rho GTPase, emerged as the top upregulated gene. We show that RHOV is essential for anoikis resistance, cellular aggregation in anchorage-independence, migration, invasion, in vivo metastatic colonization, and is elevated in patient omental metastases. Mechanistically, RHOV integrates c-Jun dependent cytoskeletal remodeling with early endosomal trafficking to support pro-metastatic signaling, which is dependent on both RHOV's GTPase activity and membrane localization. For the first time this study identifies RHOV as a necessary mediator of ovarian cancer metastasis, and highlights the potential of immediate early detachment-responsive transcriptional changes as promising therapeutic targets in metastatic disease. Overall design: To define the transcriptomic adaptations acquired by metastasizing ovarian cancer cells following matrix detachment, we performed high-depth RNA-sequencing of three ascites-derived ovarian cancer cell lines (OVCA433, OVCAR3 and SKOV3) in attached conditions (2D), at 2 hrs post-detachment (3D 2h) and at 24 hrs post-detachment (3D 24h).