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At least 19 recordsLinked to original sources

PubMed2003

Inhibition of heparanase activity and heparanase-induced angiogenesis by suramin analogues.

Heparanase, a heparan sulfate-specific endo-beta-D-glucuronidase, plays an important role in tumor cell metastasis through the degradation of extracellular matrix heparan sulfate proteoglycans (ECM HSPG). Heparanase activity correlates with the metastatic propensity of tumor cells. Suramin, a polysulfonated naphthylurea, is an inhibitor of heparanase with suramin analogues shown to possess antiangiogenic and antiproliferative properties. We investigated the effects of selected suramin analogues (NF 127, NF 145 and NF 171) on heparanase activity and heparanase-driven angiogenesis. Studies of the ability of cellular extracts and purified heparanase from human, highly invasive and brain-metastatic melanoma (70W) cells revealed that heparanase expressed by these cells was effectively inhibited by suramin analogues in a dose-dependent manner. These analogues possessed more potent heparanase inhibitory activities than suramin: The concentrations required for 50% heparanase inhibition (IC(50)) were 20-30 microM, or at least 2 times lower than that for suramin. One hundred percent inhibition was observed at concentrations of 100 microM and higher. Of relevance, these compounds significantly decreased (i) the invasive capacity of human 70W cells by chemoinvasion assays performed with filters coated with purified HSPG or Matrigel trade mark, and (ii) blood vessel formation by in vivo angiogenic assays, thus linking their antiangiogenic properties with impedance of heparanase-induced angiogenesis. Specifically, inhibition of invasion by NF 127, NF 145 and NF 171 was found at 10 microM concentrations of compounds with a significant decrease of invasive values at concentrations as low as 1.5 microM. In addition, NF 127, NF 145 and NF 171 promoted nearly complete inhibition of heparanase-induced angiogenesis at values ranging from 236 microM (for NF 145) to 362 microM (for NF 127). These results further emphasize the importance of heparanase in invasive and angiogenic mechanisms and the potential clinical application of heparanase inhibitors such as suramin analogues in cancers and angiogenesis-dependent diseases.

Antineoplastic Agents↗

PubMed1998

Partial purification of heparanase activities in Chinese hamster ovary cells: evidence for multiple intracellular heparanases.

Heparanases are mammalian endoglycosidases that cleave heparan sulphate glycosaminoglycans from proteoglycan core proteins and degrade them into shorter chains. The enzymes have been proposed to act in a variety of cellular processes, including proteoglycan catabolism, remodelling of basement membranes and release of heparan sulphate-binding ligands from their extracellular storage sites. Additional functions for heparanases may be to generate short heparan sulphate chains that stabilize or activate other proteins. While heparanase activities have been described in a number of tissues and cell lines, it is not known how many different enzymes are responsible for these activities. Our recent studies characterizing the short glycosaminoglycans produced in Chinese hamster ovary (CHO) cells suggested that multiple heparanases are necessary for the formation of the short heparan sulphate chains [Bame and Robson (1997) J. Biol. Chem. 272, 2245-2251]. We examined whether this is the case by purifying heparanase activity from CHO cell homogenates. Based on their ability to bind ion-exchange resins and their elution from gel-filtration columns, four separate heparanase activities were partially purified. All four activities cleave free glycosaminoglycans over a broad pH range of 3.5-6.0 or 6. 5, suggesting that they act in the endosomal/lysosomal pathway. The sizes of the short heparan sulphate chains generated by the partially purified heparanases ranged from 6 to 9 kDa, and for two of the activities the product size is pH-dependent. Three of the four activities degrade proteoglycans as well as the free glycosaminoglycan chain. Interestingly, all four enzymes generate short glycosaminoglycans with a sulphate-rich, modified domain at the non-reducing end of the newly formed chain. Since our previous studies showed that in CHO cells there is also a population of short heparan sulphates with a modified domain at the reducing end of the chain, this suggests that there may be another heparanase in CHO cells that was not purified. Alternatively, our findings suggest that the formation of short heparan sulphate glycosaminoglycans inside CHO cells may be a result of the concerted action of multiple heparanases, and may depend on the proportions of the different enzymes and the environment in which the chains are degraded.

Animals↗

PubMed1997

Neurotrophin stimulation of human melanoma cell invasion: selected enhancement of heparanase activity and heparanase degradation of specific heparan sulfate subpopulations.

Heparanase is an endo-beta-D-glucuronidase whose enzymatic targets are the glycosaminoglycan chains of heparan sulfate proteoglycans (50). Elevated levels of heparanase are associated with the metastatic potential of melanoma cells, and treatment of murine and human melanoma cells with the prototypic neurotrophin nerve growth factor (NGF) increases the production of heparanase by melanoma cells. We previously reported that physiological concentrations of NGF increased invasion of early passage human brain-metastatic 70W melanoma cells but not melanoma cells metastatic to other sites or nonmetastatic melanoma cells as measured in Matrigel invasion assays. Here we found that treatment of 70W melanoma cells with neurotrophin-3 (NT-3) increased Matrigel invasion, whereas treatment with neurotrophins other than NGF or NT-3 did not influence invasion. Mutants of NGF that do not bind to the neurotrophin receptor p75NTR or other nonneuronal growth factors were not able to enhance the invasion of 70W melanoma cells. When 70W cells were exposed to antisense oligonucleotides directed against p75NTR mRNA, there was a reduction in NGF and NT-3 binding, and the neurotrophins failed to enhance Matrigel invasion. To study the properties of heparanase in neurotrophin-regulated malignant melanoma invasive processes, we developed a sensitive heparanase assay consisting of purified [35S]HS subpopulations separated by agarose gel electrophoresis. Incubation of 70W cells with NGF or NT-3 but not brain-derived neurotrophic factor, neurotrophin-4/5 or mutant NGF resulted in increased release of heparanase activity that was capable of degrading a subpopulation of heparan sulfate molecules.

Electrophoresis, Agar Gel↗

PubMed1996

Neurotrophin stimulation of human melanoma cell invasion: selected enhancement of heparanase activity and heparanase degradation of specific heparan sulfate subpopulations.

Heparanase is an endo-beta-D-glucuronidase, the enzymatic targets of which are the glycosaminoglycan chains of heparan sulfate proteoglycans. Elevated levels of heparanase are associated with the metastatic potential of melanoma cells. Treatment of murine and human melanoma cells with the prototypic neurotrophin nerve growth factor (NGF) increases the production of heparanase by melanoma cells. We reported previously that physiological concentrations of NGF increased in vitro Matrigel invasion of early-passage human brain-metastatic 70W melanoma cells but not melanoma cells metastatic to other sites or nonmetastatic melanoma cells. Here we found that treatment of 70W melanoma cells with neurotrophin NT-3 increased Matrigel invasion, whereas treatment with neurotrophins other than NGF or NT-3 did not influence invasion. Mutants of NGF that do not bind to the neurotrophin receptor p75NTR or other nonneuronal growth factors were not able to enhance the invasion of 70W melanoma cells. When 70W cells were exposed to antisense oligonucleotides directed against p75NTR mRNA, there was a reduction in NGF and NT-3 binding, and the neurotrophins failed to enhance Matrigel invasion. To study the properties of heparanase in NT-regulated malignant melanoma invasive processes, we developed a sensitive heparanase assay consisting of purified [35S]heparan sulfate subpopulations separated by agarose gel electrophoresis. Incubation of 70W cells with NGF or NT-3, but not brain-derived NT factor, NT-4/5, or mutant NGF, resulted in increased release of heparanase activity that was capable of degrading a subpopulation of heparan sulfate molecules.

Base Sequence↗

PubMed1997

A rapid quantitative assay for the detection of mammalian heparanase activity.

Heparan sulphate (HS) is an important component of the extracellular matrix and the vasculature basal laminar which functions as a barrier to the extravasation of metastatic and inflammatory cells. Cleavage of HS by endoglycosidase or heparanase activity produced by invading cells may assist in the disassembly of the extracellular matrix and basal laminar, and thereby facilitate cell migration. Heparanase activity has previously been shown to be related to the metastatic potential of murine and human melanoma cell lines [Nakajima, Irimura and Nicolson (1988) J. Cell. Biochem. 36, 157-167]. To determine heparanase activity, porcine mucosal HS was partially de-N-acetylated and re-N-acetylated with [3H]acetic anhydride to yield a radiolabelled substrate. This procedure prevented the masking of, or possible formation of, new heparanase-sensitive cleavage sites as has been observed with previous methods of radiolabelling. Heparanase activity in a variety of tissues and cell homogenates including human platelets, colonic carcinoma cells, umbilical vein endothelial cells and rat mammary adenocarcinoma cells (both metastatic and non-metastatic variants) and liver homogenates all degraded the substrate in a stepwise fashion from 18.5 to approximately 13, 8 and finally to 4.5 kDa fragments, as assessed by gel-filtration analysis, confirming the substrate as suitable for the detection of heparanase activity present in a variety of cells and tissues. A rapid quantitative assay was developed with the HS substrate using a novel method for separating degradation products from the substrate by taking advantage of the decreased affinity of the heparanase-cleaved products for the HS-binding plasma protein chicken histidine-rich glycoprotein (cHRG). Incubation mixtures were applied to cHRG-Sepharose columns, with unbound material corresponding to heparanase-degradation products. Heparanase activity was determined for a variety of human, rat and murine cell and tissue homogenates. The highly metastatic rat mammary adenocarcinoma and murine lung carcinoma cell lines had four to ten times the heparanase activity of non-metastatic variants, confirming the correlation of heparanase activity with metastatic potential. Human cancer patients had twice the serum heparanase levels of normal healthy adults. The assay will be valuable for the determination of heparanase activity from a variety of tissue and cell sources, as a diagnostic tool for the determination of heparanase potential, and for the development of specific inhibitors of heparanase activity and metastasis.

Adult↗

PubMed2001

Increased expression of heparanase in puromycin aminonucleoside nephrosis.

BACKGROUND: The beta-D-endoglycosidase heparanase has been proposed as an important contributor to loss of glomerular charge in proteinuria. Expression of heparanase was, therefore, determined in acute puromycin aminonucleoside (PAN) nephrosis. METHODS: A rabbit polyclonal antibody was produced against a 17-amino acid peptide derived from the predicted amino acid sequence of heparanase. The antibody was validated by Western blot. Immunohistochemical staining and Western blotting were used to localize heparanase protein in normal kidneys and kidneys from rats with PAN nephrosis. Northern blot analysis was used to determine mRNA expression. RESULTS: Immunohistochemical staining showed that heparanase protein was localized to tubular cells in the distal convoluted tubules, thick ascending limb of the loop of Henle, and transitional cell epithelium in normal kidney. Minimal expression was noted in normal glomeruli. Western blot analysis of protein from isolated normal glomeruli showed minimal expression of the 65 kD proheparanase protein. A marked increase in the staining for heparanase was found at day 5 of the PAN nephrosis model, at approximately the time of onset of proteinuria, and at day 14. Expression was predominantly seen in podocytes. At day 5, only the 65 kD proheparanase species was identified, but at day 14, mature 58 kD heparanase also was present. Northern blot analysis of sieved glomeruli at day 14 confirmed an increase in heparanase mRNA. The human podocyte cell line 56/10A1 also produced both proheparanase and mature heparanase, suggesting that podocytes can activate heparanase without other cell types. CONCLUSION: The previously mentioned data confirm that the novel beta-D-endoglycosidase heparanase is up-regulated and activated in glomeruli from rats with proteinuria. Heparanase may be involved, therefore, in the loss of glomerular charge seen in proteinuria. Moreover, the presence of heparanase in normal tubules suggests that it may also be involved in cell migration or turnover.

Animals↗

PubMed1997

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-beta-D-glucuronidase that degrades the glycosaminoglycan chains of heparan sulfate (HS) proteoglycans at specific sites. Elevated levels of heparanase are associated with the metastatic potential of melanoma and other types of tumor cells. We previously reported heparanase degradation of cell surface HS subpopulations of the human adenocarcinoma cell line RL95. In the present study, heparanase activity was examined on RL95 cell surface HS subpopulations in the presence of a synthetic peptide (CRPKAKAKAKAKDQTK) of heparin/heparan sulfate-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, 11817-11823). Heparanase digestion generated HS fragments from cell surface- or extracellular matrix-derived HS of approximately 25 and 9 kDa, respectively. In contrast, HS of various size classes isolated from proteoglycans secreted or released by RL95 and endothelial cells in culture were not susceptible to heparanase digestion. Incubation of heparanase-containing melanoma cellular extracts or partially purified heparanase preparations with cell surface- or ECM-derived HS and HIP peptide, but not a scrambled sequence of this peptide or other HS-binding proteins present in ECM, completely inhibited heparanase action. Conversely, predigestion of cell surface HS with either heparanase-containing 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 demonstrate that HIP peptide and heparanase recognize specific, common motifs within HS chains at cell surfaces and in ECM and may mutually modulate HS-dependent activities.

Amino Acid Sequence↗

PubMed2002

Involvement of human heparanase in the pathogenesis of diabetic nephropathy.

BACKGROUND: Decreased heparan sulfate proteoglycan content of the glomerular basement membrane has been described in proteinuric patients with diabetic nephropathy. Heparanase is an endo-beta-D-glucuronidase that cleaves negatively charged heparan sulfate side chains in the basement membrane and extracellular matrix. OBJECTIVES: To investigate whether urine from type I diabetic patients differs in heparanase activity from control subjects and whether resident glomerular cells could be the source of urinary heparanase. METHODS: Using soluble 35S-HSPG and sulfate-labeled extracellular matrix we assessed heparanase activity in human glomerular epithelial cells, rat mesangial cells, and urine from 73 type I diabetic patients. Heparanase activity resulted in the conversion of a high molecular weight sulfate-labeled HSPG into heparan sulfate degradation fragments as determined by gel filtration analysis. RESULTS: High heparanase activity was found in lysates of both epithelial and mesangial cells. Immunohistochemical staining localized the heparanase protein to both glomeruli capillaries and tubular epithelium. Heparanase activity was detected in the urine of 16% and 25% of the normoalbuminuric and microalbuminuric diabetic patients, respectively. Urine from 40 healthy individuals did not possess detectable heparanase. Urinary heparanase activity was associated with worse glycemic control. CONCLUSION: We suggest that heparanase enzyme participates in the tunover of glomerular HSPG. Hyperglycemia enhances heparanase activity and/or secretion in some diabetic patients, resulting in the loss of albumin permselective properties of the GBM.

Adult↗

PubMed2000

Expression of heparanase in normal, dysplastic, and neoplastic human colonic mucosa and stroma. Evidence for its role in colonic tumorigenesis.

The human heparanase gene, an endo-beta-glucuronidase that cleaves heparan sulfate at specific intrachain sites, has recently been cloned and shown to function in tumor progression and metastatic spread. Antisense digoxigenin-labeled heparanase RNA probe and monoclonal anti-human heparanase antibodies were used to examine the expression of the heparanase gene and protein in normal, dysplastic, and neoplastic human colonic mucosa. To our knowledge, this is the first systematic study of heparanase expression in human colon cancer. Both the heparanase gene and protein were expressed at early stages of neoplasia, already at the stage of adenoma, but were practically not detected in the adjacent normal-looking colon epithelium. Gradually increasing expression of heparanase was evident as the cells progressed from severe dysplasia through well-differentiated to poorly differentiated colon carcinoma. Deeply invading colon carcinoma cells showed the highest levels of the heparanase mRNA and protein associated with expression of both the gene and enzyme by adjacent desmoplastic stromal fibroblasts. A high expression was also found in colon carcinoma metastases to lung, liver, and lymph nodes, as well as in the accompanying stromal fibroblasts. Moreover, extracts derived from tumor tissue expressed much higher levels of the heparanase protein and activity as compared to the normal colon tissue. In all specimens, the heparanase gene and protein exhibited the same pattern of expression. These results suggest a role of heparanase in colon cancer progression and may have both prognostic and therapeutic applications.

Aged↗

PubMed2002

Heparanase expression in human leukemias is restricted to acute myeloid leukemias.

OBJECTIVE: Matrix metalloproteinases and an endo-beta-D-glucuronidase (heparanase) are enzymes that degrade the protein and carbohydrate constituents of basement membranes, thereby facilitating transendothelial migration of blood-borne cells. Heparanase activity was found to correlate with the metastatic potential of solid tumors. We evaluated heparanase expression, at the levels of gene and protein expression and activity in a variety of leukemias, and compared it with normal hematopoietic cells. MATERIALS AND METHODS: Heparanase expression was evaluated in leukocytes isolated from peripheral blood of 71 patients with myeloid and lymphoid leukemias, or non-Hodgkin's lymphoma. Analysis was performed at two levels: heparanase RNA was determined by reverse transcriptase polymerase chain reaction, and heparanase protein was evaluated by immunocytochemistry and flow cytometry. RESULTS: In eight peripheral blood samples from normal donors, heparanase RNA was detected, and protein was found within the cytoplasm of granulocytes. In mononuclear cells derived from various leukemias, heparanase RNA was expressed in 14 of 15 acute myeloid leukemia (AML) samples. In contrast, cells derived from all 33 chronic lymphoblastic leukemia, all 7 non-Hodgkin's lymphoma, 7 of 8 chronic myeloid leukemia, and 6 of 8 acute lymphoblastic leukemia patients showed no detectable expression of the heparanase RNA. Heparanase protein was detected primarily within the cytoplasm of AML cells, indicating that the enzyme is produced and stored within the cytoplasm of myeloid cells, with limited expression on the cell surface. CONCLUSION: We propose that heparanase expression is associated with the myeloid lineage and may serve as an independent marker to support the identification of AMLs.

Acute Disease↗

PubMed2001

Expression pattern and secretion of human and chicken heparanase are determined by their signal peptide sequence.

Cleavage of heparan sulfate (HS) proteoglycans affects the integrity and function of tissues and thereby fundamental phenomena, involving cell migration and response to changes in the extracellular microenvironment. The role of HS-degrading enzymes, commonly referred to as heparanases, in normal development has not been identified. The present study focuses on cloning, expression, and properties of a chicken heparanase and its distribution in the developing chicken embryo. We have identified a chicken EST, homologous to the recently cloned human heparanase, to clone and express a functional chicken heparanase, 60% homologous to the human enzyme. The full-length chicken heparanase cDNA encodes a 60-kDa proenzyme that is processed at the N terminus into a 45-kDa highly active enzyme. The most prominent difference between the chicken and human enzymes resides in the predicted signal peptide sequence, apparently accounting for the chicken heparanase being readily secreted and localized in close proximity to the cell surface. In contrast, the human enzyme is mostly intracellular, localized in perinuclear granules. Cells transfected with a chimeric construct composed of the chicken signal peptide preceding the human heparanase exhibited cell surface localization and secretion of heparanase, similar to cells transfected with the full-length chicken enzyme. We examined the distribution pattern of the heparanase enzyme in the developing chicken embryo. Both the chicken heparanase mRNA and protein were expressed, as early as 12 h post fertilization, in cells migrating from the epiblast and forming the hypoblast layer. Later on (72 h), the enzyme is preferentially expressed in cells of the developing vascular and nervous systems. Cloning and characterization of heparanase, the first and single functional vertebrate HS-degrading enzyme, may lead to identification of other glycosaminoglycan degrading enzymes, toward elucidation of their significance in normal and pathological processes.

Amino Acid Sequence↗

PubMed2000

Mammalian heparanase as mediator of tumor metastasis and angiogenesis.

Expression of heparan sulfate-degrading endoglycosidases, commonly referred to as heparanases, correlates with the metastatic potential of tumor cell lines, and treatment with heparanase inhibitors markedly reduces the incidence of metastasis in experimental animals. We purified a 50 kDa heparanase from human hepatoma and placenta and cloned a cDNA and gene encoding a protein of 543 amino acids. Only one heparanase sequence was identified, suggesting that this enzyme is the dominant endoglucuronidase in mammalian tissues. Expression of the cloned cDNA in insect and mammalian cells yielded 65 kDa and 50 kDa recombinant proteins. The 50 kDa enzyme represents an N-terminal processed enzyme that is at least 200-fold more active than the full-length 65 kDa form. Processing was demonstrated following incubation of the full-length recombinant enzyme with intact tumor cells. The heparanase mRNA and protein are preferentially expressed in metastatic cell lines and in specimens of human melanomas and carcinomas. In the colon, both the heparanase mRNA and protein are expressed already at the stage of tubulovillous adenoma, but not in the adjacent 'normal-looking' colon epithelium. Non-metastatic murine T lymphoma and melanoma cells transfected with the heparanase gene acquired a highly metastatic phenotype in vivo. Apart from its involvement in the egress of cells from the vasculature, heparanase is tightly involved in angiogenesis, both directly--by promoting invasion of endothelial cells (vascular sprouting), and indirectly--by releasing heparan sulfate-bound basic fibroblast growth factor, and generating HS degradation fragments that promote bFGF activity. The angiogenic potential of heparanase was demonstrated in vivo (Matrigel plug assay) by showing a three to fourfold increase in neovascularization induced by Eb T lymphoma cells following their transfection with the heparanase gene. The ability of heparanase to promote both tumor angiogenesis and metastasis makes it a promising target for cancer therapy.

Animals↗

PubMedDate not supplied

Lung colonization by and heparanase activity in in vitro transformed 3T3 cells rendered highly tumorigenic by an in vivo passage.

Cloned BALB/c 3T3 cells transformed in vitro with polyoma virus and maintained in culture (C cells) were compared with respect to their ability to form experimental metastases, with cells from the same clones that were passaged subcutaneously in vivo (CTC cells), thereby gaining a high tumorigenicity phenotype. No correlation was found between a high subcutaneous tumorigenicity potential or the progression state of these cells, and their capacity to form experimental metastases. Both cell types were also tested for their ability to release heparan sulfate degradation products from a naturally produced, sulfate-labeled extracellular matrix (ECM). Whereas the in vitro maintained C cells did not express an endo-beta-D-glucuronidase (heparanase) activity, some of the in vivo passaged CTC cells expressed such an activity. No strict correlation was found, however, between heparanase activity and the ability of CTC cells from individual tumors to form experimental metastases. However, A9 CTC 220 cells which produced a large number of lung metastases also expressed a high heparanase activity. Both heparanase and lung colonization by A9 CTC 220 cells were inhibited to a large extent by heparin, suggesting the involvement of heparanase in the extravasation of these highly metastatic cells. A9 CTC 220 cells were found to release basic fibroblast growth factor (bFGF) from ECM. This release was partially inhibited by carrageenan lambda which also completely inhibited the heparanase activity expressed by these cells. The in vivo acquisition of heparanase activity was not a result of cell fusion between heparanase expressing host-derived cells and heparanase-negative transformed cells. This conclusion was based on the fact that both the in vitro maintained, heparanase-negative as well as the in vitro passaged, heparanase-positive cells exhibited a similar membrane and molecular market profile.

3T3 Cells↗

PubMed1999

Degradation of basement membrane by prostate tumor heparanase.

BACKGROUND: The degradation of basement membrane (BM) by cancer is an important event that characterizes invasive biological behavior. A component of BM is heparan sulfate proteoglycan (HSPG). The glycanase(s) that degrade HSPG in BM are not yet isolated. We recently identified HSPG-degrading activity (PC-3M heparanase) in the conditioned media (CM) of malignant prostate carcinoma cells (PC-3M and LNCaP C4-2). Antibodies (Abs) to a recently isolated heparanase from human platelets (CTAP-III), cross-react with PC-3M heparanase although they differ in size; under reduced conditions PC-3M heparanase is 60 kDa whereas CTAP-III is 10 kDa by polyacrylamide gel electrophoresis. PC-3M heparanase therefore shares homology with CTAP-III. The purpose of this study was to test the inhibition of PC-3M heparanase by Abs specific to the N- and C-terminals of CTAP-III. MATERIALS AND METHODS: CM from PC-3M and LNCaP C4-2 cells were tested for heparanase activity. Each reaction contained substrate as [3H]glucosamine-labeled HSPG (>50 kDa) from the BM of the EHS tumor, CM from PC-3M or LNCaP C4-2 cells, and inhibitor or buffer (negative control). Protease inhibitors were present throughout. After incubation for 3-20 h at 37 degreesC and pH 5.8, the reaction was stopped with 0.2% SDS. Each reaction mixture was centrifuged in an Ultrafree-MC 30,000 NMWL filter unit (Millipore) and radioactivity in the filtrate counted by scintillation counting. Results. For both cell lines, there was a linear relationship between the amount (microgram) of CM and degradation of HSPG. Degradation was inhibited by 54.1% (mean) using carrageenan lambda (10 microgram/ml), a nonspecific glycanase inhibitor (P < 0.05 by ANOVA). Ab to the N-terminus of CTAP-III (anti-Hep A) reduced degradation by 10-50% (mean 31.1%) and to the C-terminus (anti-Hep C) by 38.8-64.3% (mean 51.1%) (P < 0.003 by ANOVA). CONCLUSIONS: The degradation of HSPG by malignant prostate cancer cell lines is inhibited by both a nonspecific glycanase inhibitor, and specific Abs to a homologous platelet heparanase. Based upon molecular weight, PC-3M heparanase is different from platelet heparanase and degrades BM.

Amino Acid Sequence↗

PubMed2003

Expression of heparanase in human tumor cell lines and human head and neck tumors.

Heparanase is an endo-beta-D-glucuronidase that can cleave heparan sulfate and has been implicated in tumor angiogenesis and metastasis. Recent studies have demonstrated that overexpression of heparanase in human tumors facilitates their invasion activity, thereby enhancing the metastatic potential of the tumors. We found that heparanase mRNA and heparanase protein were constitutively elevated in some human tumor cell lines and human head and neck tumors. Heparanase mRNA expression was increased in response to treatment with an inhibitor of DNA methylation in cells that normally express low levels of heparanase mRNA. Inhibition of DNA methylation did not enhance heparanase mRNA expression in the presence of cycloheximide. These results suggest that overexpression of heparanase mRNA in cancer cells might not be due to demethylation of the promoter region of the heparanase gene itself, rather the other gene(s), such as transcriptional factors that, in turn, regulate heparanase expression.

Blotting, Western↗

PubMed2002

Activation, processing and trafficking of extracellular heparanase by primary human fibroblasts.

Heparanase is a heparan-sulfate-degrading endoglycosidase that has important roles in various biological processes, including angiogenesis, wound healing and metastatsis. Human heparanase is synthesized as a 65 kDa latent precursor, which is proteolytically processed into a highly active 50 kDa form. Extracellular heparanase is found in various tissues and is utilized by both normal cells and metastatic cancer cells to degrade heparan sulfate moieties in basement membranes and extracellular matrices. This study characterizes the processing and trafficking events associated with cellular activation of extracellular heparanase. We show that primary human fibroblasts are capable of binding and converting the 65 kDa heparanase precursor into its highly active 50 kDa form, concomitantly with its cytoplasmic accumulation. Heparanase uptake depends on the actin cytoskeleton integrity, resulting in a prolonged storage of the enzyme, mainly in endosomal structures. Heparanase endocytosis and its proteolytic activation are independent processes, indicating that heparanase cleavage is a cell surface event. Heparin completely inhibits heparanase endocytosis but only partially inhibits its association with the cells, suggesting that cell surface heparan sulfate moieties play a specific role in its endocytosis. Cellular binding and uptake of extracellular heparanase control its activation, clearance rate and storage within the cells.

Blotting, Western↗

PubMed1999

Evidence that platelet and tumour heparanases are similar enzymes.

In order to enter tissues, blood-borne metastatic tumour cells and leucocytes need to extravasate through the vascular basal lamina (BL), a process which involves a battery of degradative enzymes. A key degradative enzyme is the endoglycosidase heparanase, which cleaves heparan sulphate (HS), an important structural component of the vascular BL. Previously, tumour-derived heparanase activity (which has been shown to be related to the metastatic potential of murine and human melanoma cell lines) was reported to cleave HS and be inhibited by heparin, as distinct from human platelet heparanase, which cleaved both substrates [Nakajima, Irimura and Nicolson (1988) J. Cell Biochem. 36, 157-167]. We recently reported the purification of human platelet heparanase and showed that the enzyme is a 50-kDa endoglucuronidase [Freeman and Parish (1998) Biochem. J. 330, 1341-1350]. We now report the purification and characterization of heparanase activity from highly metastatic rat 13762 MAT mammary adenocarcinoma and human HCT 116 colonic carcinoma cells and from rat liver using essentially the same procedure that was reported for purification of the human platelet enzyme. The rat 13762 MAT tumour enzyme, which has a native M(r) of 45 kDa when analysed by gel-filtration chromatography and by SDS/PAGE, was observed to be an endoglucuronidase that degraded heparin and HS to fragments of the same sizes as the human platelet enzyme does. N-deglycosylation of both the human platelet and rat 13762 MAT tumour enzymes gave, in each case, a 41-kDa band by SDS/PAGE analysis, demonstrating that the observed difference in M(r) between the platelet and tumour enzymes may have been due largely to differences in the relative amounts of N-glycosylation. Two peptides were isolated following Endoproteinase Lys-C digestion of both the human platelet and rat 13762 MAT tumour heparanases and were shown to be highly similar. Both the rat liver and human colonic carcinoma heparanases also degraded both heparin and HS to fragments of the same sizes as the human platelet enzyme does. Western-blot analysis of an SDS/PAGE gel using antibodies raised against human platelet heparanase demonstrated that human platelet, human tumour and rat tumour heparanases were immunochemically cross-reactive. In conclusion, because of the similarities in their sizes, substrate specificities, peptide sequences and immunoreactivities, we propose that heparanase activities present in human platelets, rat liver and in rat and human tumour cells are, in fact, mediated by a similar enzyme.

Amino Acid Sequence↗

PubMed1990

Immunochemical localization of heparanase in mouse and human melanomas.

Heparanase, an endo-beta-D-glucuronidase, has been associated with melanoma metastasis. Polyclonal antibodies directed against the murine N-terminal heparanase peptide detected a Mr approximately 97,000 protein on SDS-PAGE of mouse melanoma and human melanoma cell lysates. In an indirect immunocytochemical study, human A375-SM and mouse B 16-BL6 melanoma cells were stained with the anti-heparanase antibodies. Heparanase antigen was localized in the cytoplasm of permeabilized melanoma cells as well as at the cell surface of unpermeabilized cells. Immunohistochemical staining of frozen sections from syngeneic mouse lungs containing micrometastases of B16-BL6 melanoma demonstrated heparanase localized in metastatic melanoma cells. Similar studies using frozen sections of malignant melanomas resected from patients indicated that heparanase is localized in invading melanoma cells. Our studies suggest that (a) the N-terminus of the heparanase molecule in mouse and human is antigenically related; (b) heparanase antigens are localized at the cell surface and in the cytoplasm of metastatic human and mouse melanoma cells; and (c) heparanase antigens are enriched in invasive and metastatic murine and human melanomas in vivo.

Animals↗