Gambogic acid impairs tumor angiogenesis by targeting YAP/STAT3 signaling axis.

Angiogenesis is central to a wide range of physiological and pathological processes including wound healing, macular degeneration, and cancer. Excessive or inappropriate vascular supply of tumors is one of the main targets for cancer therapy. Recently, critical and selective transcriptional factors such as yes-associated protein (YAP) that control the expression of angiogenesis factors have gained increasing attention in antiangiogenic therapy. In this study, we have identified and characterized a novel inhibitor of YAP, gambogic acid (GA), which exerted striking antiangiogenic effects both in vitro and in vivo. We demonstrated that GA remarkably inhibited a variety of vascular endothelial growth factor-induced angiogenesis processes including proliferation, migration, sprouting, and tube formation of endothelial cells in vitro. In addition, GA resulted in decreased neo-vessel formation in Matrigel plugs of mice and chick chorioallantoic membrane. More importantly, we showed that GA limited tumor growth via preventing tumor angiogenesis and vascular maturation. Further mechanistic studies illustrated that GA directly targeted YAP/STAT3 signaling axis, which is critical for the transcriptional regulation of a series of angiogenic factors. Taken together, these preclinical findings suggest that GA significantly repressed tumor angiogenesis and may serve as a promising drug candidate against cancer.