Bioactivity screening of partially desulfated low-molecular-weight heparins: a structure/activity relationship study

A series of size-defined low-molecular-weight heparins were generated by regioselective chemical modifications and profiled for their in vitro and in vivo activities. The compounds displayed reduced anti-coagulant activity, demonstrated varying affinities toward angiogenic growth factors (fibroblast growth factor-2, vascular endothelial growth factor and stromal cell-derived factor-1α), inhibited the P-selectin/P-selectin glycoprotein ligand-1 interaction and, notably, exhibited anti-tumor efficacy in a murine melanoma experimental metastasis model. Our results demonstrate that modulating specific sequences, especially the N-domains (-NS or -NH(2) or -NHCOCH(3)) in these polysaccharide sequences, has a major impact on the participation in a diverse range of biological activities. These results also suggest that the 6-O-sulfates, but not the 2-O-sulfates, critically affect the binding of a desulfated derivative to certain angiogenic proteins as well as its ability to inhibit P-selectin-mediated B16F10 melanoma metastases. Furthermore, N-desulfation followed by N-acetylation regenerates the affinity/inhibition properties to different extents in all the compounds tested in the in vitro assays. This systematic study lays a conceptual foundation for detailed structure function elucidation and will facilitate the rational design of targeted heparan sulfate proteoglycan-based anti-metastatic therapeutic candidates.