ERRα promotes gallbladder cancer development via activating PI3K/AKT signaling pathway mediated by Nectin-4

Abstract Background: Gallbladder cancer (GBC) is the most common malignant tumour of the bile duct with a poor prognosis. The estrogen-related receptor alpha (ERRα) is a nuclear receptor that has been associated with metabolic processes and cancer progression. Increased ERRα has been shown in endocrine-related cancer and non-endocrine-related cancer. Nevertheless, its role in GBC remains unknown. Methods: ERRα expression was analyzed by immunohistochemistry in 59 GBC samples. Its association with clinicopathologic characteristics was evaluated. The effect of ERRα on GBC cell proliferation and invasion was evaluated by loss- or gain-of-function assays in vitro and in vivo. The influence of ERRα on EMT biomarkers, Nectin-4 and PI3K/AKT signaling pathway was detected by western blotting. Inhibition of Nectin-4 was conducted to explore the potential mechanism of ERRα in GBC. Results: Our study reveals increased ERRα expression in GBC tissues vs. non-tumour adjacent tissues. ERRα expression is significantly positively correlated with high TNM stage, high invasion depth and lymph node metastasis, while negatively associated with prognosis. Targeted depletion of ERRα by lentivirus-mediated shRNA decreased cell proliferation in vitro and in vivo. ERRα promoted cancer cell migration and epithelial-mesenchymal transition by regulating the expression of EMT relevant genes. Ectopic expression of ERRα promoted GBC cell growth and invasion in vitro, while inhibiton of Nectin-4 attenuated cell growth and invasion induced by ERRα. Moreover, ERRα overexpression activated the PI3K/AKT signaling pathway while this effect can be blocked by Nectin-4 depletion. Nectin-4 was involved in the oncogenic function of ERRα to activate PI3K/AKT signaling pathway in GBC. Conclusions: ERRα promotes GBC progression via activating PI3K/AKT signaling pathway mediated by Nectin-4. ERRα may be a potential prognostic factor and molecular therapeutic target for GBC.