Abstract 2898: Rac1 as a driver and therapeutic target in ovarian cancer

Aberrant Rac1 signaling contributes to cancer growth and metastasis, therefore, we investigated the effect of altering Rac1 expression and activity to pinpoint which metastatic processes and tumor microenvironment immune factors are influenced by Rac1 signaling. We have identified that the R- enantiomer of ketorolac, a drug given for pain management, is a Rac1 and Cdc42 selective inhibitor. In a retrospective study, we found that treatment with racemic ketorolac significantly increased the survival probability of ovarian cancer patients. RNA seq analyses of ascites tumor cell samples from ovarian cancer patients in a prospective study receiving racemic ketorolac for clinically indicated use in pain relief, showed significant downregulation of genes involved in endocytosis, regulation of actin cytoskeleton, ER protein processing, TNF and NOD signaling. To further distinguish the activities most directly regulated by Rac1 and important in ovarian cancer, we tested the impact of manipulating the expression of Rac1 in ovarian cancer cells on adhesive and invasive cell behaviors, as well as the impacts of gene expression relative to ketorolac treatment. Using electric cell-substrate impedance sensing (ECIS), Rac1 overexpression resulted in increased cell-cell barrier formation and cell adhesion. Whereas, CRISPR-CAS9 mediated knockdown of Rac1 resulted in decreased cell adhesion. Using Matrigel invasion chambers and mesothelial clearance assays, Rac1 overexpression led to increased ovarian cancer cell invasion when compared to parental and Rac1 knockdown cell lines. Furthermore, intraperitoneal growth of ovarian cancer cells overexpression Rac1 relative to parental control lines increased tumor burden in vivo. Conversely, with knockdown of Rac1, tumor burden and omental adhesion was decreased, as quantified using IVIS bioluminescence imaging. RNA seq analyses of tumors manipulated for Rac1 as compared to R-ketorolac will be presented. The composite data indicate that targeting Rac1 in ovarian cancer with R-ketorolac or otherwise has therapeutic benefit in decreasing tumor cell dissemination and metastasis. Citation Format: Melanie Rivera, Martha M. Grimes, Laurie G. Hudson, Angela Wandinger-Ness. Rac1 as a driver and therapeutic target in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2898.