The Molecular Mechanism Of YAP1-AGK Positive Feedback Loop In Promoting Gastric Cancer Progression

Background:Acylglycerol kinase(AGK)uses adenosine triphosphate(ATP)and acylglycerol to generate adenosine diphosphate(ADP)and acyl-sn-glycerol 3-phosphate in cells.Recent evidence has demonstrated that dysregulated AGK expression is associated with the development of various human cancers.This study investigated the effects of AGK on gastric cancer cell proliferation and carcinogenesis and explored the underlying molecular events.Methods:Immunohistochemistry and western blotting were performed to analysis AGK expression in gastric cancer patient tissues and cell lines.The relationship between AGK expression and the clinicopathological features of gastric cancer was investigated based on immunohistochemical results.The detection of the epithelial-mesenchymal transition markers as well as CCK-8,colony formation,transwell invasion and migration assays,and xenograft models were used to determine the biological function of AGK in gastric cancer.The association between AGK and YAP1 were first analyzed in gastric cancer cells and tissues,and further investigated by luciferase reporter assay,chromatin immunoprecipitation,immunofluorescence and qRT-PCR in vitro.Results:AGK expression was upregulated in gastric cancer cell lines and tissue samples and was associated with poor overall survival in gastric cancer patients.AGK overexpression increased gastric cancer proliferation,invasion capacity,and the expression of the epithelial-mesenchymal transition markers in vitro.Conversely,the knockdown of AGK expression reduced gastric cancer cell proliferation in vitro and in nude mouse tumor cell xenografts.Importantly,AGK expression was associated with the YAP1 expression in gastric cancer cells and tissues.YAP1 expression also transcriptionally induced AGK expression through the binding of TEAD to the AGKgene promoter.However,AGK expression inhibited the activation of the Hippo pathway proteins and induced YAP1 nuclear localization to enhance the transcription activity of YAP1/TEADs.Conclusion:The study demonstrates that AGK is not only a novel target of the Hippo-YAP1 pathway,but that it also positively regulates YAP1 expression,a YAP1-AGK positive feedback loop.Furthermore,this novel YAP1-AGK loop contributes to gastric tumorigenesis,suggesting dual targeting AGK and YAP1 may become a novel therapeutic strategy for the future treatment of GC.