Heparan sulfate containing unsubstituted glucosamine residues: biosynthesis and heparanase inhibitory activity [Enzymology]

April 21st, 2014 by Nadanaka, S., Purunomo, E., Takeda, N., Tamura, J.-i., Kitagawa, H.

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. As 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, GlcAβ1-4GlcNH3+(6-O-sulfate)α1-4GlcAβ1-4GlcNH3+(6-O-sulfate), inhibited heparanase activity and suppressed invasion of breast cancer cells in vitro. Bifunctional N-deacetylase/N-sulfotransferase-1 (NDST-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 exostosin-like 3 (EXTL3) controls N-sulfotransferase activity of NDST-1 by forming a complex with NDST-1 and contributes to generation of unsubstituted glucosamine residues.