Abstract 5896: Downregulation of calcium-sensing receptor enhances MET-mediated prostate cancer chemosensitivity

Abstract Chemoresistance, in various types of cancer including prostate cancer (PCa), is one of the major challenges in cancer therapy. Others and our lab have reported that the epithelial-to-mesenchymal transition (EMT) plays critical roles in development of chemoresistance and metastasis. The calcium-sensing receptor (CaSR) plays important roles in maintenance of calcium homeostasis and altered CaSR expression, and functional changes are involved in certain diseases, including tumorigenesis and its development. However, the mechanism of CaSR in PCa chemoresistance remains unclear. In current study, the CaSR expression level was detected in parental PC3 and DU145 cells and their chemoresistant PC3-TxR and DU145-TxR cells. We found the CaSR was highly expressed in chemoresistant PC3-TxR and DU145-TxR cells. Then by using siRNA technique, CaSR expression was transiently knocked down in chemoresistant cells. The tumor cell migration, invasion, and colony formation were evaluated by wound healing, transwell, and colony formation assays, respectively. The drug sensitivity was evaluated using MTS assay. We observed that the abilities of tumor cell migration and invasion were significantly diminished in CaSR knockdown PC3-TxR and DU145-TxR cells. The ability of colony formation was also reduced. Interestingly, the sensitivity to paclitaxel was reactivated in CaSR knockdown PC3-TxR and DU145-TxR cells. We finally observed that E-cadherin expression was increased in CaSR knockdown chemoresistant cells, and Snail, Vimentin and β-catenin were decreased; these results are consistent with EMT phenotypic alterations. Taken together, we conclude that downregulation of CaSR enhances MET-mediated prostate cancer chemosensitivity. Supported by NSFC Key Project 81130046; NSFC projects 81773146,81272415; JCYJ20170412152943794, JCYJ20170412154619484, JCYJ20170307105128101, JCYJ2017030711041760; Guangxi Key Projects 2013GXNSFEA053004. Citation Format: Luying Huang, Fuhao Wang, Haibo Tong, Atsushi Mizokami, Evan T. Keller, Yi Lu, Jian Zhang. Downregulation of calcium-sensing receptor enhances MET-mediated prostate cancer chemosensitivity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5896.