Heparan Sulfate Containing Unsubstituted Glucosamine Residues BIOSYNTHESIS AND HEPARANASE-INHIBITORY ACTIVITY

Background: The function and biosynthetic mechanism of GlcNH<sub arrange="stack">3<sup arrange="stack">+ in heparan sulfate remain unclear. Results: GlcNH<sub arrange="stack">3<sup arrange="stack">+-containing tetrasaccharides inhibited heparanase activity. Exostosin-like 3 regulated the expression of GlcNH<sub arrange="stack">3<sup arrange="stack">+ structures. Conclusion: GlcNH<sub arrange="stack">3<sup arrange="stack">+-containing tetrasaccharides suppressed cancer cell invasion in vitro. Production of GlcNH<sub arrange="stack">3<sup arrange="stack">+ was controlled by EXTL3 (exostosin-like 3) and NDST-1 (N-deacetylase/N-sulfotransferase-1). Significance: Tumor metastasis might be suppressed by utilizing GlcNH<sub arrange="stack">3<sup arrange="stack">+-containing oligosaccharides. Additionally, a biosynthetic mechanism of GlcNH<sub arrange="stack">3<sup arrange="stack">+-containing heparan sulfates was proposed. Degradation of heparan sulfate (HS) in the extracellular matrix by heparanase is linked to the processes of tumor invasion and metastasis. Thus, a heparanase inhibitor can be a potential anticancer drug. Because HS with unsubstituted glucosamine residues accumulates in heparanase-expressing breast cancer cells, we assumed that these HS structures are resistant to heparanase and can therefore be utilized as a heparanase inhibitor. As expected, chemically synthetic HS-tetrasaccharides containing unsubstituted glucosamine residues, GlcA1-4GlcNH<sub arrange="stack">3<sup arrange="stack">+(6-O-sulfate)1-4GlcA1-4GlcNH<sub arrange="stack">3<sup arrange="stack">+(6-O-sulfate), inhibited heparanase activity and suppressed invasion of breast cancer cells in vitro. Bifunctional NDST-1 (N-deacetylase/N-sulfotransferase-1) catalyzes the modification of N-acetylglucosamine residues within HS chains, and the balance of N-deacetylase and N-sulfotransferase activities of NDST-1 is thought to be a determinant of the generation of unsubstituted glucosamine. We also report here that EXTL3 (exostosin-like 3) controls N-sulfotransferase activity of NDST-1 by forming a complex with NDST-1 and contributes to generation of unsubstituted glucosamine residues.