CXCL12/CXCR7/β-arrestin1 Biased Signal Promotes Epithelial-to-Mesenchymal Transition of Colorectal Cancer by Repressing Mirnas Through YAP1 Nuclear Translocation

Abstract

Background: CXCR7 is an atypical chemokine receptor that transmits biased signal independent of G-protein activation. However, whether CXCL12/CXCR7 biased signal activation plays an essential role in colorectal cancer (CRC) progression and metastasis remains obscure. Methods: The functional role of CXCL12/CXCR7 biased signal in CRC was investigated by RNA-sequencing, Transwell assay and in vivo tumor xenografts. YAP1 nuclear translocation and molecular mechanisms were determined by cell transfection, luciferase activity assay, immunofluorescence, coimmunoprecipitation and immunohistochemistry and RT-qPCR analysis.Results: In this study, CXCR7 CXCL12/overexpression promotes Epithelial-to-mesenchymal transition (EMT) and upregulates the expression of stem marker doublecortin-like kinase 1 (DCLK1) in CRC cells with concurrent repression of miR-124-3p and miR-188-5p. Further luciferase assay prove that these miRNAs could regulate EMT by direct targeting vimentin and DCLK1. More importantly, CXCL12/CXCR7/β-arrestin1-mediated biased signal induces YAP1 nuclear translocation, which functions as a transcriptional repressor by interacting with Yin Yang 1 (YY1) and recruiting YY1 to the promoter of miR-124-3p and miR-188-5p. Pharmacological inhibitor of YAP1 recapitulates the anti-tumorigenesis and anti-metastasis effects of YAP1 depletion upon CXCR7 activation in tumor xenografts. Clinically, the expression of CXCR7 was positively correlated with nuclear YAP1 levels and EMT markers. Conclusions: Our findings revealed the novel role of YAP1 nuclear translocation in promoting EMT of CRC by repressing miR-124-3p and miR-188-5p through CXCL12/CXCR7/β-arrestin1 biased signal activation. These findings highlight the potential of targeting YAP1 nuclear translocation in hampering CXCL12/CXCR7 biased signal-induced metastasis of CRC.