Abstract 3144: PDZ-RhoGEF/β-arrestin-1 interaction mediates endothelin A receptor-induced RhoA activation and cell motility in ovarian tumor cells

Abstract

Abstract β-arrestins (β-arrs), consisting of β-arr1 and β-arr2, are involved in G-protein-coupled receptor signaling, and guide the receptor signals in chemotaxis and cytoskeletal reorganization. Among them, receptor A for endothelin-1 (ET-1), namely ETAR, is overexpressed in epithelial ovarian cancer (EOC) and promote metastatic spread. We have recently reported that β-arr1 regulates ETAR-mediated β-catenin signaling to promote EOC cell invasion. Here we evaluated the effects of ET-1 on polarized cell migration correlating with the regulation of Rho-GTPase activity and its subsequent organization of the actin structures supporting migration and the involvement of β-arr1 in these effects. We show that, in EOC cells cultured on collagen type I, ET-1 promotes actin-based dynamic protrusion resembling to pseudopodia, containing β-arr-1. Furthermore, in a β-arr1/ETAR-dependent manner, ET-1 activates RhoA GTPase and downstream the dephosphorylation/activation of cofilin, as shown by pull down assay and immunoblotting analysis. The inhibitory effect of the Rho pathway inhibitor I, Y-27632, demontrates that RhoA GTPase is involved in ET-1-induced cell migration. By screening members of a Rho-guanine nucleotide exchange factor (Rho-GEF) family involved in RhoA activation, we found that PDZ-RhoGEF mRNA levels are highly expressed in EOC cells. Moreover, PDZ-RhoGEF is responsible for ET-1-induced RhoA activation through interaction with β-arr1, that in turn, promotes PDZ-RhoGEF tyrosine phosphorylation and activation. Depletion of PDZ-RhoGEF expression significantly impaired ET-1-stimulated migration of EOC cells, demonstrating that PDZ-RhoGEF/β-arrestin-1 interaction mediates ETAR-driven ovarian tumor cell motility through regulation of RhoA. Analysis of EOC human tissues revealed that PDZ-RhoGEF is overexpressed in human EOC tissues. Collectively, our data establish a novel role for β-arr1 and PDZ-RhoGEF as regulator of ET-1-induced EOC cell migration, unraveling new components required for tumor progression. Supported by AIRC. Citation Format: Piera Tocci, Roberta Cianfrocca, Elisa Semprucci, Valeriana Di Castro, Anna Bagnato, Laura Rosanò. PDZ-RhoGEF/β-arrestin-1 interaction mediates endothelin A receptor-induced RhoA activation and cell motility in ovarian tumor cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3144. doi:10.1158/1538-7445.AM2014-3144