ABSTRACTH. pylori infection is the strongest known risk factor for gastric carcinoma. The activation of the yes-associated protein 1 (YAP) and β-catenin pathways has been associated with multiple tumor types. In this study, we investigated the crosstalk between the YAP and β-catenin pathways in H. pylori-associated gastric tumorigenesis. Immunohistochemical analysis of YAP and β-catenin expression was performed in human gastric cancer tissues. The small molecules Super-TDU and KYA1797K, pharmacological inhibitors of YAP and β-catenin, respectively, were used to investigate the role of these signaling pathways in H. pylori-induced gastric carcinogenesis in murine models of infection. The common downstream targets of YAP and β-catenin signaling were evaluated by RNA sequencing (RNA-seq). Western blot, immunofluorescence, luciferase, RT-PCR, immunoprecipitation, cell counting kit-8 (CCK8), EdU and spheroid assays were used. H. pylori infection promoted YAP and β-catenin nuclear accumulation and transcriptional activity in gastric epithelial cells and transgenic insulin–gastrin (INS-GAS) mice, whereas silencing of both YAP and β-catenin synergistically inhibited H. pylori-induced cell proliferation and expansion. In addition, YAP was found to directly interact with β-catenin and knockdown of YAP suppressed H. pylori-induced nuclear translocation of β-catenin. Moreover, downstream genes caudal-type homeobox 2 (CDX2), leucine-rich repeat containing G protein-coupled receptor 5 (LGR5) and RuvB like AAA ATPase 1 (RUVBL1) were shared by both YAP and β-catenin signaling. Furthermore, treatment with the YAP inhibitor Super-TDU or β-catenin inhibitor KYA1797A significantly alleviated gastric inflammation and epithelial DNA damage in H. pylori-infected mice. Finally, the elevation of gastric YAP was positively correlated with β-catenin expression in human gastric cancer tissues. These findings indicate that YAP and β-catenin synergistically promote H. pylori-induced gastric carcinogenesis via their physical interaction and reveal that CDX2, LGR5 and RUVBL1 are the downstream genes shared by both the YAP and β-catenin signaling pathways, and potentially contribute to H. pylori pathogenesis.
