Overexpression of GPER1 suppressed esophageal carcinoma growth via activating cAMP pathway.

G protein-coupled estrogen receptor 1 (GPER1) has extensively verified as a tumor regulator in various types of cancers. However, its role in esophageal cancer (EC) remains largely unclear. In this study, the expression and prognostic prediction value of GPER1 in EC was analyzed by using TCGA database and was verified in EC cells and fresh tissues. The results showed that GPER1 is decreased in EC cells and tissues, and lower GPER1 expression is associated with poor overall survival of EC patients. CCK-8 assay and flow apoptosis cytometry were applied to measure the ability of proliferation and apoptosis of EC cells with or without GPER1 overexpression. The levels of reactive oxygen species (ROS) and Fe2+ were determined by flow cytometry. Elisa and Western blotting were employed to measure the markers of ferroptosis and cyclic adenosine monophosphate (cAMP) pathway. The results of in vitro experiments indicated that overexpression of GPER1 caused decreased proliferation, increased cell apoptosis, ROS generation, Fe2+ content and acyl-CoA synthetase long-chain family member 4 (ACSL4) expression, while decreased glutathione peroxidase 4 (GPX4) expression. Notably, the cAMP/PKA inhibitor H89 significantly reversed the ferroptotic effects induced by GPER1, indicating the essential role of the cAMP pathway in this process. The weight and volumes of tumors were measured and Ki-67 and H&E staining were conducted to analyze the effect of GPER1 in vivo. The results of in vivo experiments indicated that overexpression of GPER1 resulted in restricted tumor growth, reduced Ki-67 expression and increased cell death. In conclusion, the expression of GPER1 is reduced in EC. Overexpression of GPER1 enhances ferroptosis in EC, primarily through activation of the cAMP signaling pathway.