Specific Inhibition of Heparanase by a Glycopolymer with Well-Defined Sulfation Pattern Prevents Breast Cancer Metastasis in Mice

Heparanase, the heparan sulfate polysaccharide degrading endoglycosidase enzyme, has been correlated with tumor angiogenesis and metastasis and therefore has become a potential target for anticancer drug development. In this systematic study, the sulfation pattern of the pendant disaccharide moiety on synthetic glycopolymers was synthetically manipulated to achieve optimal heparanase inhibition. Upon evaluation, a glycopolymer with 12 repeating units was determined to be the most potent inhibitor of heparanase (IC50 = 0.10 +/- 0.36 nM). This glycopolymer was further examined for cross-bioactivity using a solution-based competitive biolayer interferometry assay with other HS-binding proteins (growth factors, P-selectin, and platelet factor 4), which are responsible for mediating angiogenic activity, cell metastasis, and antibody-induced thrombocytopenia. The synthetic glycopolymer has low affinity for these HS-binding proteins in comparison to natural heparin. In addition, the glycopolymer possessed no proliferative properties toward human umbilical endothelial cells (HUVECs) and a potent antimetastatic effect against 4T1 mammary carcinoma cells. Thus, our study not only establishes a specific inhibitor of heparanase with high affinity but also illustrates the high effectiveness of this multivalent heparanase inhibitor in inhibiting experimental metastasis in vivo.