Paper Title
Boc2 (N-Tert-Butoxycarbonyl-Phe-Leu-Phe-Leu-Phe): A Novel Multitarget-Angiogenic Growth Factor Inhibitor

Abstract
Angiogenesis is a process by which new vascular networks develop from preexisting vessels. The angiogenesis process is a result of the simultaneous actions of different angiogenic growth factors, including the members of vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) families. The N-tert-butyloxycarbonyl-Phe-Leu-Phe-Leu-Phe (BOC2) peptide is a widely used antagonist of formyl peptide receptors (FPRs). Extensive investigations have been performed by using BOC2 as an FPR1/FPR2 antagonist to assess the role of FPRs in the regulation of inflammation and angiogenesis. Here we assessed the possibility that BOC2 may exert also a direct inhibitory effect on the angiogenic activity of heparin-binding growth factors independent of its FPR antagonist activity. Our data demonstrate that BOC2 inhibits the angiogenic activity of VEGF-A and FGF2. In endothelial cell-based bioassays, BOC2 prevents VEGF-A and FGF2-mediated sprouting of human umbilical vein endothelial cell spheroids embedded in a 3D fibrin gel and endothelial cell proliferation. Accordingly, BOC2 inhibits VEGFR2 and FGFR1 phosphorylation and activation of the downstream secondary signaling mediator AKT in endothelial cells. In keeping with these observations, BOC2 suppresses the angiogenic potential of the vitreous fluid obtained from patients affected by proliferative diabetic retinopathy and that exerted by highly metastatic human melanoma A2058 cells and human prostate cancer DU145 cells. Thus, BOC2 appears to act as a novel multitarget-angiogenic growth factor antagonist. These findings caution about the interpretation of FPR-focusing experimental data obtained with this compound and set the basis for the design of novel BOC2-derived, FPR independent multi-target angiogenesis inhibitors. Index Terms- BOC2, Angiogenesis, VEGF-A, FGF2, FPRs.