GPER1 Induces The Proliferation,Migration And Invasion Of Gastric Cancer Cells Through PI3K/AKT–mediated EMT

Gastric cancer(GC)is one of the most common malignant tumors in China,with the highest morbidity and mortality.The epidemiology of gastric cancer shows that the incidence of gastric cancer in males and females is 1.2:1.The early symptoms of gastric cancer are not special,and most patients are already in the advanced stage when they are first diagnosed.The median progression-free survival in patients with advanced gastric cancer is 4 to 7 months,and the overall survival is 9 to 14 months.Therefore,there is an urgent need to find new therapeutic targets to provide more treatment options for patients with gastric cancer and improve the survival prognosis of patients with gastric cancer.GPER1 belongs to the seven-transmembrane G protein-coupled receptors family,which mediate fast signal responses and transcriptional events.GPER1 is a membrane estrogen receptor that regulates cell growth,migration,apoptotic cell death,and other cancer-related biological functions.However,there is contradictory evidence indicating that GPER1 act as either a tumor promoter or a tumor suppressor in different cancer contexts.GPER1 expression is associated with poorer prognosis in patients with gastric cancer,but the specific role of GPER1 in gastric cancer development and progression is not well understood.In terms of function,CCK-8 and Edu assays found that knockdown of GPER1 inhibited the proliferation of gastric cancer cells.Flow cytometry and western blot of CDK4 and Cyclin D1 also showed that GPER1 inhibited the proliferation of gastric cancer cells by inducing cell cycle arrest in G0/G1 period.Scratch-wound assays and transwell experiments were performed to demonstrate that knockdown of GPER1 inhibited the migration and invasion of gastric cancer cells.Then we employed gene set enrichment analysis and discovered that GPER1 expression was concomitant with EMT process and was positively correlated with activation of the PI3K/AKT pathway in GC.We used the rescur experiment to show that knockdown of GPER1 downregulated the mesenchymal markers N-cadherin and vimentin,upregulated E-cadherin,an epithelial marker,and suppressed expression of the Snail,Slug and Twist1 transcription factors,indicating that knockdown of GPER1 inhibited EMT,and 740Y-P,a PI3 K activator,reversed the effects of GPER1 knockdown on EMT processes.Then we used plasmid overexpressing GPER1 and PI3 K inhibitor,PI3K-IN-1,to further prove these findings.At last,we established xenograft and peritoneal dissemination model and further demonstrated that GPER1 could indeed affect tumor growth and metastasis of GC in vivo.In summary,these data demonstrate that GPER1 inhibition suppresses the proliferation,migration,and invasion of gastric cancer cells by inhibiting PI3K/AKTmediated EMT.Our study elucidated the function of GPER1 in gastric cancer,and we identified PI3K/AKT-mediated EMT as a novel mechanism by which GPER1 contributes to proliferation,migration,and invasion of gastric cancer.These data suggest that combining inhibition of GPER1 and PI3 K may be a potential therapeutic approach to inhibit gastric cancer metastasis.