Endoglin, a TGF-b coreceptor predominantly expressed in endothelial cells, plays an important role in vascular development and tumor-Associated angiogenesis. However, the mechanism by which endoglin regulates angiogenesis, especially during tip cell formation, remains largely unknown. In this study, we report that endoglin promotedVEGF-induced tip cell formation.Mechanistically, endoglin interactedwithVEGF receptor (VEGFR)-2 in a VEGF-dependent manner, which sustained VEGFR2 on the cell surface and prevented its degradation. Endoglin mutants deficient in the ability to interactwithVEGFR2 failedto sustainVEGFR2 on the cell surface and topromote VEGF-induced tip cell formation. Further, an endoglin-Targeting monoclonal antibody (mAb), TRC105, cooperated with aVEGF-A targeting mAb, bevacizumab, to inhibitVEGF signaling and tip cell formation in vitro and to inhibit tumor growth, metastasis, and tumor-Associated angiogenesis in a murine tumor model. This study demonstrate a novelmechanism bywhich endoglin initiates and regulatesVEGF-driven angiogenesiswhile providing a rationale for combining anti-VEGF and anti-endoglin therapy in patients with cancer.
ASJC Scopus subject areas
- Molecular Biology