Increased activation of FAK and Rho GTPase regulatory pathways is associated with shorter survival in patients with high-grade serous ovarian carcinoma (HGSOC). However, the key mediators of these signaling events in HGSOC remain unknown. We have previously shown that the Rho guanine nucleotide exchange factor Rgnef (also named p190RhoGEF or Arhgef28) activates FAK as well as RhoA GTPase in mouse fibroblasts. Here we find that Rgnef protein expression is elevated in Stage 3-4 HGSOC and that Rgnef knockout prevents ovarian tumor spheroid growth in vitro and in vivo. We isolated ascites-associated murine ID8 cells to generate a more aggressive cell line, termed ID8-IP. ID8-IP cells exhibit higher Rgnef and FAK expression than parental ID8 cells. CRISPR/Cas9-induced knockout of Rgnef in ID8-IP cells does not alter 2D growth as compared to Rgnef-KO cells re-expressing GFP-Rgnef. However, Rgnef loss significantly decreased growth as spheroids in a 3D Matrigel-on-Top assay. At five weeks following intraperitoneal injection into syngeneic C57Bl/6 mice, ID8-IP Rgnef-KO cells form significantly fewer ascites-associated cells, as well as fewer metastatic lesions on the peritoneal wall. Notably, ID8-IP Rgnef-KO cells display lower FAK and ERK1/2 phosphorylation. These studies demonstrate that Rgnef loss impedes metastatic growth in the peritoneal cavity, and suggest that an integrin-mediated Rgnef-FAK linkage facilitates ovarian tumor metastasis.

Citation Format: Elizabeth G. Kleinschmidt, Isabelle Tancioni, Kristin Taylor, Carlos Osterman-Diaz, Nichol L. G. Miller, Shulin Jiang, David D. Schlaepfer. Rgnef (p190RhoGEF/Arhgef28) loss impairs ovarian tumor metastatic growth. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B47.

©2018 American Association for Cancer Research.
2018
American Association for Cancer Research.