HEPARANASE AND A SYNTHETIC PEPTIDE OF HEPARAN SULFATE-INTERACTING PROTEIN RECOGNIZE COMMON SITES ON CELL-SURFACE AND EXTRACELLULAR-MATRIX HEPARAN-SULFATE

Heparanase is an endo-P-D-glucuronidase that de grades the glycosamino glycan chains of heparan sulfate (HS) proteoglycans at specific sites, Elevated levels of heparanase are associated with the metastatic pote ntial of melanoma and other types of tumor cells, We previously report ed heparanase degradation of cell surface HS subpopulations of the hum an adenocarcinoma cell line RL95, In the present study, heparanase act ivity was examined on RL95 cell surface HS subpopulations in the prese nce of a synthetic peptide (CRPKAKAKAKAKDQTK) of heparin/heparan sulfa te-interacting protein (HIP; Liu, S., Smith, S, E,, Julian, J,, Rohde, L, H., Karin, N. J., and Carson, D, D, (1996) J, Biol, Chem, 271, 118 17-11823), Heparanase digestion generated HS fragments from cell surfa ce- or extracellular matrix-derived HS of approximately 25 and 9 kDa, respectively, In contrast, HS of various size classes isolated from pr oteoglycans secreted or released by RL95 and endothelial cells in cult ure were not susceptible to heparanase digestion, Incubation of hepara nase-containing melanoma cellular extracts or partially purified hepar anase preparations with cell! surface- or ECM-derived HS and HIP pepti de, but not a scrambled sequence of this peptide or other HS-binding p roteins present in ECM, completely inhibited heparanase action, Conver sely, predigestion of cell surface HS with either heparanase-containin g cellular extracts or with secreted or partially purified heparanase destroyed binding to HIP peptide, Preincubation of HS with HIP peptide prevented subsequent heparanase digestion. Collectively, these data d emonstrate that HIP peptide and heparanase recognize specific, common motifs within HS chains at cell surfaces and in ECM add may mutually m odulate HS-dependent activities.