Abstract 5426: Identification of Selective Small Molecule Inhibitors of Vascular Endothelial Growth Factor (VEGF) and Bone Morphogenetic Protein (BMP) Signaling Using Zebrafish-based in vivo Structure Activity Relationship Studies

Abstract

Angiogenesis, a physiological process of forming new blood vessels from pre-existing ones, plays a vital role in organogenesis, tissue response to ischemia, and malignant tumor growth. Angiogenesis is a complex process, requiring a finely tuned balance between various stimulatory and inhibitory signals. Vascular endothelial growth factors (VEGFs) are a major class of proangiogenic mediators that fuction by binding and activating the VEGF receptor tyrosine kinases, including VEGFR2/KDR/Flk-1. Additionally, bone morphogenetic proteins (BMPs) play a critical role in modulating angiogenesis via cross talks between the BMP and VEGF signaling at variety of levels. We recently identified dorsomorphin, the first known small molecule BMP signaling inhibitor, based on its ability to perturb zebrafish embryonic dorsoventral axis, which is normally established by a BMP signaling gradient. Here we show that dorsomorphin can also disrupt angiogenic intersomitic vessel (ISV) formation and has significant off-target activity against the type-2 VEGF receptor (Flk1/KDR). To determine whether dorsomorphin’s anti-angiogenic effects in vivo are due to its effects on BMP, VEGF, or both signals, we conducted a structure activity relationship (SAR) studies of over 70 dorsomorphin analogs purely based on their in vivo effects on zebrafish embryos. We found that dorsomorphin analogs which caused embryonic dorsalization, but had no effect on ISV formation were potent BMP inhibitors but not VEGF/PDGF inhibitors. Conversely, analogs that disrupt angiogenesis but not dorsoventral axis were found to be potent VEGF inibitors, but not BMP inhibitors. These results show that BMP signaling is not required for ISV formation in zebrafish. Moreover, this effort has led to the identification of exquisitely selective BMP and KDR inhibitors with superior in vivo bioavailability and efficacy. To our knowledge, this is the first large-scale SAR study performed in whole animals, and demonstrate the potential of zebrafish chemical embryogenesis for drug development.