Tumor metastasis-associated heparanase (heparan sulfate endoglycosidase) activity in human melanoma cells

Abstract

We discovered previously a tumor metastasis-associated heparan sulfate (HS)-degrading endoglycosidase in mouse melanoma cells that is a unique endo-β-glucuronidase (heparanase) capable of specifically cleaving HS at intrachain sites (Nakajima et al., J. Biol. Chem., 259 (1984) 2283. Using unmodified- and chemically modified-HS and heparin substrates we demonstrate that human Hs939 and mouse B16 melanoma cells possess a HS-degrading endoglycosidase of similar specificity. Melanoma heparanase showed high activity against N-desulfated N-acetylated HS, and we therefore synthesized a solid-phase heparanase substrate crosslinking partially N-desulfated N-[ 14C] acetylated HS to agarose gel beads via one covalent linkage. Using this solid-phase substrate 15 human malignant melanoma cell lines were assayed for heparanase activity. All of the melanoma cells tested had heparanase activity, and almost all possessed activities comparable or greater than that of the murine B16-F1 melanoma line. Human A375 melanoma variants of high lung metastatic potential in athymic nude mice had significantly higher heparanase activities than did A375 parental cells of low metastatic potential.