Regulation of Hippo/YAP axis by CXCR7 in the tumorigenesis of gastric cancer

The Hippo pathway is crucial in organ size control and tumorigenesis. The dys-regulation of Hippo/YAP axis is vastly observed in gastric cancer, while the effective therapeutic targets for Hippo/YAP axis are still not clear. It is important and urgent to identify reliable drug targets and the underlying mechanisms, which could inhibit the activity of Hippo/YAP axis and gastric cancer progression. In our current study, we demonstrate the membrane receptor CXCR7 (C-X-C chemokine receptor 7) is an important modulator for Hippo/YAP axis. The activation of CXCR7 could stimulate gastric cancer cell progression through Hippo/YAP axis in vitro and in vivo, while pharmaceutical inhibition of CXCR7 via ACT-1004-1239 could block the tumorigenesis in gastric cancer. Molecular studies reveal that the activation of CXCR7 could dephosphorylate YAP, facilitate YAP nuclear accumulation and transcriptional activation in gastric cancer. CXCR7 functions via G-protein Gaq/11 and Rho GTPase to activate YAP activity. Interestingly, ChIP assay shows that YAP could bind to the promoter region of CXCR7 and facilitate its gene transcription, which indicates CXCR7 is both the upstream signaling and downstream target for Hippo/YAP axis in gastric cancer. In general, we identified a novel positive feedback loop between CXCR7 and Hippo/YAP axis, while blockade of CXCR7 could be a plausible strategy for gastric cancer. Overall design: gastric cancer cell mRNA samples were summarized in six samples, divided into two groups, siControl and siCXCR7