Abstract 4860: Exon capture analysis of G-protein coupled receptors reveals activating mutations in GRM3 in melanoma

Abstract

Abstract An important feature of cellular signaling involves the activation of plasma membrane-bound receptor complexes via endogenous ligands. G protein-coupled receptors (GPCRs), the largest human gene family, are known to be activated by ligands such as, thrombin, chemokines or glutamate, and have been shown to be important regulators of signaling pathways. Dysregulation via overexpression of diverse GPCRs has been well documented in primary and metastatic tumors cells such as breast, lung, prostate and gastric tumors, head and neck squamous cell carcinoma, and melanoma (1), however, knowledge of their genetic alterations is limited especially in malignant melanoma. Thus, further analysis of this gene family is warranted to determine if GPCR proteins play a role in melanomagenesis. In our current study, we used exon capture and illumina sequencing methods to analyze the mutational status of all the GPCRs in melanoma. This investigation revealed that one family member, GRM3 was frequently mutated in melanoma and that one of its mutations clustered within one position (Glu870Lys). Biochemical analysis of GRM3 alterations revealed that mutant GRM3 selectively regulated the phosphorylation of MEK leading to increased anchorage-independent growth and migration. In vivo studies revealed that overexpression of mutant forms of GRM3 result in increased lung macrometastases; whereas depletion of GRM3 in cells expressing mutant forms of GRM3 resulted in reduced xenograft tumor formation compared to equivalently treated wild type GRM3 cells. Furthermore, melanoma cells expressing mutant forms of GRM3 had reduced cell growth and reduced cellular migration after shRNA-mediated knockdown of GRM3 or treatment with a selective MEK inhibitor, AZD-6244, which is currently being used in phase II clinical trials. Our study yields a comprehensive map of genetic alterations in the GPCR gene family and suggests a potential novel therapeutic target for melanoma patients. 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 4860. doi:1538-7445.AM2012-4860