Angiostatic actions of capsicodendrin through selective inhibition of VEGFR2-mediated AKT signaling and disregulated autophagy

// Christopher C. Pan 1 , Nirav Shah 1 , Sanjay Kumar 1 , Sarah E. Wheeler 1 , Jason Cinti 1 , Dale G. Hoyt 1 , Christine E. Beattie 6 , Min An 6 , Karthikeyan Mythreye 2 , L. Harinantenaina Rakotondraibe 3 and Nam Y. Lee 1,4,5 1 Division of Pharmacology, College of Pharmacy, The Ohio State University, OH, USA 2 Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA 3 Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, OH, USA 4 Davis Heart Lung Research Institute, The Ohio State University, OH, USA 5 Comprehensive Cancer Center, The Ohio State University, OH, USA 6 Department of Neuroscience, The Ohio State University, OH, USA Correspondence to: Nam Y. Lee, email: // Keywords : autophagy, AKT, VEGF, angiogenesis, endothelium Received : April 15, 2016 Accepted : April 29, 2016 Published : May 11, 2016 Abstract Angiogenesis is the formation of new blood vessels from existing vasculature critical for embryonic development and vascular remodeling. Its dysregulation underlies numerous pathologic states ranging from ischemia to tumor growth and as such identifying new targeted- therapies is of significant interest for angiogenesis-based medicine. Here we evaluated the potential angiostatic properties of capsicodendrin (CPCD), a natural compound isolated from Cinnamosma macrocarpa , a plant belonging to the Malagasy Cinnamosma. CPCD potently inhibits endothelial proliferation, migration and capillary tube formation at nanomolar to low micromolar concentrations without inducing cytotoxic effects. We show that CPCD directly inactivates VEGFR2 and downstream AKT signaling, thereby strongly inducing autophagy as determined by increased expression of beclin1, autophagy-related gene (Atg) 3, Atg5 and LC3 cleavage. Ectopic AKT overexpression counteracts the inhibitory effects of CPCD on proliferation and capillary tubule formation. Importantly, CPCD treatment in vivo inhibits sprouting angiogenesis as evidenced by strongly reduced intersegmental vessel (ISV) sprouting and subintestinal vessel (SIV) formation during zebrafish embryonic development, and correlates with increased presence of LC3II along the ISVs despite overall reduced vasculature. These findings demonstrate CPCD as a potent inhibitor of the VEGFR2/AKT pathway at nanomolar concentrations and inducer of autophagy-related angiostatic effects.