Fibroblast growth factor-2 antagonist activity and angiostatic capacity ofsulfated Escherichia coli K5 polysaccharide derivatives

The angiogenic basic fibroblast growth factor (FGF2) interacts with tyrosin e kinase receptors (FGFRs) and heparan sulfate proteoglycans (HSPGs) in end othelial cells. Here, we report the FGF2 antagonist and antiangiogenic acti vity of novel sulfated derivatives of the Escherichia coli K5 polysaccharid e. K5 polysaccharide was chemically sulfated in N- and/or O-position after N-deacetylation. O-Sulfated and N,O-sulfated K5 derivatives with a low degr ee and a high degree of sulfation compete with heparin for binding to I-125 -FGF2 with different potency. Accordingly, they abrogate the formation of t he HSPG.FGF2.FGFR ternary complex, as evidenced by their capacity to preven t FGF2-mediated cell-cell attachment of FGFR1-overexpressing HSPG-deficient Chinese hamster ovary (CHO) cells to wildtype CHO cells. They also inhibit ed I-125-FGF2 binding to FGFR1-overexpressing HSPG-bearing CHO cells and ad ult bovine aortic endothelial cells. K5 derivatives also inhibited FGF2-med iated cell proliferation in endothelial GM 7373 cells and in human umbilica l vein endothelial (HUVE) cells. In all these assays, the N-sulfated K5 der ivative and unmodified K5 were poorly effective. Also, highly O-sulfated an d N,O-sulfated K5 derivatives prevented the sprouting of FGF2-transfected e ndothelial FGF2-T-MAE cells in fibrin gel and spontaneous angiogenesis in v itro on Matrigel of FGF2-T-MAE and HUVE cells. Finally, the highly N,O-sulf ated K5 derivative exerted a potent antiangiogenic activity on the chick em bryo chorioallantoic membrane. These data demonstrate the possibility of ge nerating FGF2 antagonists endowed with antiangiogenic activity by specific chemical sulfation of bacterial K5 polysaccharide. In particular, the highl y N,O-sulfated K5 derivative may provide the basis for the design of novel angiostatic compounds.