title: Characterization of mechanisms involved in secretion of active heparanase.
abstract: Heparanase is an endo-beta-D-glucuronidase involved in extracellular matrix remodeling and degradation and implicated in tumor metastasis, angiogenesis, inflammation, and autoimmunity. The enzyme is synthesized as a latent 65-kDa protein and is processed in the lysosomal compartment to an active 58-kDa heterodimer, where it is stored in a stable form. In contrast, its heparan sulfate substrate is localized extracellularly, suggesting the existence of mechanisms that trigger heparanase secretion. Here we show that secretion of the active enzyme is mediated by the protein kinase A and C pathways. Moreover, secretion of active heparanase was observed upon cell stimulation with physiological concentrations of adenosine, ADP, and ATP, as well as by the noncleavable ATP analogue adenosine 5'-O-(thiotriphosphate). Indeed, heparanase secretion was noted upon cell stimulation with a specific P2Y1 receptor agonist and was inhibited by P2Y receptor antagonists. The kinetics of heparanase secretion resembled the secretion of cathepsin D, a lysosomal enzyme, indicating that the secreted heparanase is of lysosomal origin. We suggest that secretion of active heparanase is initiated by extracellular cues activating the protein kinase A and C signaling pathways. The secreted enzyme(s) then facilitate cell invasion associated with cancer metastasis, angiogenesis, and inflammation.
authors.affiliation: Cancer and Vascular Biology Research Center, the Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel.
authors.forename: Itay
authors.initials: I
authors.lastname: Shafat
authors.forename: Israel
authors.initials: I
authors.lastname: Vlodavsky
authors.forename: Neta
authors.initials: N
authors.lastname: Ilan
mesh_terms: D000244:Adenosine Diphosphate / Q000502:physiology; D000255:Adenosine Triphosphate / Q000502:physiology; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D005966:Glucuronidase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D008247:Lysosomes / Q000201:enzymology / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism / Q000502:physiology; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000502:physiology; D058472:Receptors, Purinergic P2Y1; D015398:Signal Transduction / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D000099175:Heparanase
chemical_list: D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D005576:Colforsin; D017868:Cyclic AMP-Dependent Protein Kinases; D005966:Glucuronidase; D011493:Protein Kinase C; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D013755:Tetradecanoylphorbol Acetate; D000099175:Heparanase; C546382:P2RY1 protein, human