YAP Overexpression in Breast Cancer Cells Promotes Angiogenesis Through Activating Yap Signaling in Vascular Endothelial Cells

Abstract Background:The YAP signaling pathway is altered and implicated as oncogenic in human mammary cancers.However, roles of YAP signaling that regulate the breast tumor angiogenesis have remained elusive. Tumor angiogenesis is coordinated by the activation of both cancer cells and vascular endothelial cells. Whether the YAP signalingpathway can regulate the intercellular interaction between cancer cells and endothelial cellsis essentially unknown.Results: We showed here that conditioned media from YAP overexpressed breast cancer cells (CM-YAP+) could promote angiogenesis, accompanied byincreased tube formation, migration, and proliferation of human umbilical vein endothelial cells (HUVECs). Down regulation of YAP in HUVECs reversed CM-YAP+ induced angiogenesis.CM-YAP+ time-dependently activated YAP inHUVECs by dephosphorylating YAP and increasing nuclear translocation.We also identified that both G13-RhoA and PI3K/Akt signaling pathway were necessary for CM-YAP+ induced activation of YAP.Besides, connective tissue growth factor (CTGF) and angiopoietin-2 (ANG-2)actedas down-stream of YAP in HUVECs to promote angiogenesis.In addition, subcutaneous tumors nude mice model demonstrated that tumors overexpressed YAP revealed moreneovascularization in vivo.Conclusions: YAP-YAP interaction between breastcancer cells and endothelial cellscould promote tumor angiogenesis, supporting that YAP is a potential marker and target fordeveloping novel therapeutic strategies against breast cancer.