Abstract 471: Acute activation of beta2-adrenergic receptor inhibits in vitro renal carcinoma cell migration through betaArrestin2-mediated regulation of p115RhoGEF

Abstract

Abstract Metastatic renal cell carcinoma (RCC) is fatal with no current effective treatment. Molecular mechanisms underlying progression to metastatic RCC are not fully understood, and gene array studies have revealed increased expression of beta2-adrenergic receptors (beta2AR) and betaArrestin2 genes in RCC. We examined the regulation of RCC migration and invasion, two critical steps in the progression to the metastatic disease, following beta2AR activation using scratch assays and Boyden chamber assays in cultured RCC cell lines Caki-1, SN12C and RCC7. Acute treatment with the selective beta2AR agonist formoterol inhibited migration of the three cell lines by 40% to 70% with an IC50 of 2.5 nM or less. We further examined contribution of G protein and betaArrestin signaling. Using the betaAR-inverse agonist carvedilol that is biased for[[Unsupported Character - ]]betaArrestin signaling, combined with transient knockdown of Gs or betaArrestin2 by siRNA, or mouse embryonic fibroblasts from betaArrestin1 or betaArrestin2 knockout mice, we identified betaArrestin2 as a mediator of beta2AR-induced inhibition of cell migration. betaArrestin2 forms a complex with p115RhoGEF (guanine nucleotide exchange factor) that was previously shown to be regulated by Gq and G12/13. Activation of beta2AR promoted the translocation of p115RhoGEF to the plasma membrane, with consequent activation of RhoA which enhances formation of focal adhesions that restrain the cell migration. These results suggest that betaArrestin2 exerts cell compartment-specific effects on the cell migration. In the absence of acute beta2AR activation, betaArrestin2 sequesters p115RhoGEF in the cytosol, leading to relatively lower RhoA activity at the cell periphery and higher cell migration rate. Upon acute beta2AR activation, betaArrestin2 translocates to the plasma membrane with concomitant enrichment of p115RhoGEF at the plasma membrane, resulting in the activation of RhoA and decreased cell motility. Our results imply that betaArrestin2 and its effectors impact RCC metastasis and suggest its utility as a drug target to limit progression of the disease. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 471. doi:1538-7445.AM2012-471