Abstract 1149: Interaction with NHERF1 enhances protein stability of G protein-coupled estrogen receptor

G Protein-Coupled Estrogen Receptor (GPER), also called GPR30, has been demonstrated to play important roles in a variety of physiological and pathological responses, especially in cancer cells proliferation, migration and invasion. Despite increasing evidences have showed clinical correlations between GPER expression level and poor prognosis in human cancer specimens, little is known regarding the regulation of GPER expression level, especially in protein level. Our previous studies have shown that PDZ protein NHERF1 can interact with ACTN4 (FASEB J. 2015) or PTEN (Endocrinology. 2011) and prevent their degradation. In this study, NHERF1 was demonstrated to interact with GPER in HEK293 cells and breast cancer cells MCF7 and T47D. GST Pull-down, Co-IP and immunocytochemistry analysis revealed that this interaction was mediated by the PDZ2 domain of NHERF1 and the carboxyl terminal of GPER. Mutation of the last c-terminal amino acid of GPER V375A could abolish the interaction of NHERF1 with GPER. Change of NHERF1 expression level by overexpression or knockdown affects the overall protein level of GPER. NHERF1 overexpression improved the GPER protein stability by inhibiting the receptor degradation via ubiquitin-proteasome pathway in an interaction dependent manner. Further analysis of public TCGA data revealed that NHERF1 expression level positively associated with activation of GPER downstream genes in invasive breast cancer, in which GPER mRNA level was similar with that of normal breast tissue. Our findings identify NHERF1 as a novel binding partner for GPER and uncover a novel role of NHERF1 in promoting GPER protein stability by inhibiting ubiquitin-proteasome degradation of the receptor. Considering the importance of GPER in breast cancer progression, these findings may help elucidate mechanisms associated with breast cancer invasion and metastasis. Citation Format: Ran Meng, Ying Xiong, Yuan Zhao, Yan Wang, Tao Tao, Qiqi Wang, Hua Liu, Songlin Wang, Qiong Qin, Junfang Zheng, Junqi He. Interaction with NHERF1 enhances protein stability of G protein-coupled estrogen receptor. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1149.