Abstract 1374: Synthetic heparan sulfate oligosaccharides inhibit endothelial cell functions essential for angiogenesis

Abstract

Abstract Heparan sulfate (HS), a linear glycosaminoglycan, is an essential structural component required for the activity of numerous angiogenic cytokine-receptor signalling complexes. To exploit the potential of inhibiting HS-dependent signalling complexes we synthesized a series of heparan sulfate oligosaccharides containing up to 12 saccharide residues with variable but defined sulfation patterns. The ability of oligosaccharides to compete with HS in FGF2, VEGF and IL-8 binding significantly increased with the length of oligosaccharides and especially with additional sulfate groups incorporated at specific positions in the hexuronic acid and glucosamine. In this competition assay, oligosaccharides exhibited higher levels of inhibition of FGF2 binding to HS than of VEGF and IL-8 binding to HS. Correspondingly, the inhibitory potential of oligosaccharides against FGF2-, VEGF- and IL-8-mediated endothelial cell responses was greater in longer species of oligosaccharides that bore more sulfate residues. Oligosaccharides inhibited cytokine-induced endothelial cell migration to the same extent as kinase inhibitors targeting FGF receptors or VEGF receptor 2 (VEGFR2). In contrast, FGF2-induced endothelial cell proliferation was only inhibited when cells were treated with an oligosaccharide composed of 12 saccharide residues at a concentration that significantly exceeded that of the FGFR inhibitor suggesting that oligosaccharides mainly interfere with the migration, but not proliferation of endothelial cells. The ability of oligosaccharides to target endothelial cell migration correlated with their ability to ablate FGF2- or VEGF-induced accumulation of activated peripheral FAK-pY397 and actin polymerization at the cell periphery. More importantly, there was a strong correlation between oligosaccharide structure and the level of inhibition of endothelial tube formation. Correlating with the biological activity of oligosaccharides, FGF2- and VEGF-induced downstream signalling events were sensitive to the treatment with biologically active oligosaccharides that specifically reduced FRS2, VEGFR2, ERK1/2 and AKT phosphorylation. In conclusion, we have determined the critical number of HS saccharide residues and sulfation pattern required to inhibit endothelial cell responses to key angiogenic cytokines. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1374.