TEAD4 Induced Positive Feedback Activation of E2R/YAP1 Axis and Promoted Epithelial-mesenchymal Transition through Up-regulating TWIST1 Directly in HCC

Abstract

Background: Great advance has been achieved in the investigation of Hippo signaling on mediating carcinogenesis. However, the underlying mechanism that YAP1/TEAD4 signaling regulated hepatocellular carcinoma (HCC) progression have not been completely determined. This investigation aimed to determine the mechanism of activation of YAP1/TEAD4 pathway and its regulatory effect on hepatocarcinogenesis.Methods: The TCGA database and immunohistochemical (IHC) analyses about HCC samples were carried out to analyze the expression of TEAD4 and its correlation with HCC prognosis. CCK-8, wound healing assay and transwell chamber with Matrigel were used to examine the role of TEAD4 on cell proliferation, migration and invasion capacities. In vivo imaging system was used to observe the tumor formation in SCID mouse model. The mechanistic investigation was conducted with functional studies, Western immunoblotting, Luciferase reporter assay, chromatin immunoprecipitation.Results: Analysis of HCC samples revealed that TEAD4 was up-regulated in HCC tissues compared to adjacent liver tissues, and its overexpression in HCC was significantly associated with worse prognosis, high serum AFP level, larger tumor size, PVTT, multiple tumor lesions, and microvascular invasion. Enforced expression of TEAD4 in HCC cell lines promoted the proliferation and growth of HCC cells in vitro and in vivo. The further functional studies showed that TEAD4 increased TWIST1 expression directly in the binding-promoter manner and then enhanced the migration and invasion of HCC cells via inducing epithelial-to-mesenchymal transition (EMT).TWIST1 was found to enhance E2R expression and consequently formed a positive feedback loop to activate the YAP1/TEAD4/TWIST1 axis.Conclusion: This investigation provided the functional and mechanistic basis for identifying the E2R/YAP1/TEAD4/TWIST axis as the oncogenic factor which inducing EMT and then accelerated HCC growth and invasion.