Search

Heparanase is an endo-β-D-glucuronidase capable of cleaving heparan sulfate side chains at a limited number of sites, yielding heparan sulfate fragments of still appreciable size. Importantly, heparanase activity correlates with the metastatic potential of tumor-derived cells, attributed to enhanced cell dissemination as a consequence of heparan sulfate cleavage and remodeling of the extracellular matrix and basement membrane underlying epithelial and endothelial cells. Similarly, heparanase activity is implicated in neovascularization, inflammation and autoimmunity, involving the migration of vascular endothelial cells and activated cells of the immune system. The cloning of a single human heparanase cDNA 10 years ago enabled researchers to critically approve the notion that heparan sulfate cleavage by heparanase is required for structural remodeling of the extracellular matrix, thereby facilitating cell invasion. Progress in the field has expanded the scope of heparanase function and its significance in tumor progression and other pathologies. Notably, although heparanase inhibitors attenuated tumor progression and metastasis in several experimental systems, other studies revealed that heparanase also functions in an enzymatic activity-independent manner. Thus, inactive heparanase was noted to facilitate adhesion and migration of primary endothelial cells and to promote phosphorylation of signaling molecules such as Akt and Src, facilitating gene transcription (i.e. vascular endothelial growth factor) and phosphorylation of selected Src substrates (i.e. endothelial growth factor receptor). The concept of enzymatic activity-independent function of heparanase gained substantial support by the recent identification of the heparanase C-terminus domain as the molecular determinant behind its signaling capacity. Identification and characterization of a human heparanase splice variant (T5) devoid of enzymatic activity and endowed with protumorigenic characteristics, elucidation of cross-talk between heparanase and other extracellular matrix-degrading enzymes, and identification of single nucleotide polymorphism associated with heparanase expression and increased risk of graft versus host disease add other layers of complexity to heparanase function in health and disease., (© 2010 The Authors Journal compilation © 2010 FEBS.)

Heparanase is an endoglycosidase that cleaves heparan sulfate side chains of proteoglycans, resulting in disassembly of the extracellular matrix underlying endothelial and epithelial cells and associating with enhanced cell invasion and metastasis. Heparanase expression is induced in carcinomas and sarcomas, often associating with enhanced tumor metastasis and poor prognosis. In contrast, the function of heparanase in hematological malignancies (except myeloma) was not investigated in depth. Here, we provide evidence that heparanase is expressed by human follicular and diffused non-Hodgkin's B-lymphomas, and that heparanase inhibitors restrain the growth of tumor xenografts produced by lymphoma cell lines. Furthermore, we describe, for the first time to our knowledge, the development and characterization of heparanaseneutralizing monoclonal antibodies that inhibit cell invasion and tumor metastasis, the hallmark of heparanase activity. Using luciferase-labeled Raji lymphoma cells, we show that the heparanase-neutralizing monoclonal antibodies profoundly inhibit tumor load in the mouse bones, associating with reduced cell proliferation and angiogenesis. Notably, we found that Raji cells lack intrinsic heparanase activity, but tumor xenografts produced by this cell line exhibit typical heparanase activity, likely contributed by host cells composing the tumor microenvironment. Thus, the neutralizing monoclonal antibodies attenuate lymphoma growth by targeting heparanase in the tumor microenvironment. [ABSTRACT FROM AUTHOR]

Heparanase is an endo-β-glucuronidase that enzymatically cleaves heparan sulfates (HS) and heparan sulfate proteoglycan (HSPG) structures. Heparanase expression levels by tumors were correlated with cell invasion, angiogenic activity, and poor prognosis. Heparanase can also possess pro-tumorigenic effects independent of its enzymatic activity. Using human melanoma MV3 cells, we demonstrate that latent heparanase activates in a tightly temporary-regulated manner the binding function of the integrin very late antigen-4 (VLA-4), an important component in the metastatic spread of melanoma cells. shRNA-mediated knockdown of syndecan-4 (SDC-4) indicated that this proteoglycan is the key element to convey heparanase binding via focal adhesion complex formation, detected by vinculin staining, to an upregulated VLA-4 binding function. This inside-out signaling pathway of VLA-4 involved activated FAK and Akt, but apparently not PKCα/δ. VLA-4, however, appears representative of other integrins which together impact the heparanase/integrin activation axis in tumorigenicity. Biosensor measurements provided an insight as to how heparin can interfere with this activation process. While low-molecular-weight heparin (LMWH) cannot replace heparanase bound to SDC-4, LMWH can compete with SDC-4 binding of heparanase. Since blockade of heparanase by LMWH has functional consequences for reduced VLA-4 binding, latent heparanase appears as a novel, so far unnoticed target of heparin, underlying its antimetastatic activity. [ABSTRACT FROM AUTHOR]

Background Heparanase is an endo-β-D-glucuronidase that cleaves heparan sulfate chains of proteoglycans, resulting in the disassembly of the extracellular matrix. Heparanase has a central role in the development of various tumors, and its expression has been associated with increased tumor growth, angiogenesis and metastasis, but there is insufficient information about the function of heparanase in sarcomas. Study aims 1) To evaluate heparanase levels in adult soft tissue sarcomas (STS); 2) To examine the correlation between heparanase levels and pathological and clinical parameters and treatment outcome. Methods Pathological specimens of primary or metastatic STS were subjected to immunohistochemical analysis applying an anti-heparanase antibody. The clinical and the pathological data, together with the data of heparanase levels, were evaluated in a logistic regression model for tumor recurrence and survival. Results One hundred and one samples were examined, 55 from primary tumors and 46 from metastatic sites. A high expression of heparanase was observed in 29 (52.7%) and 22 specimens (47.8%), respectively. There was no statistically significant difference between heparanase expressions in the primary vs. metastatic sites of tumors. Moreover, no correlation was observed between heparanase staining and tumor aggressiveness, tumor recurrence or patient survival in various groups of patients. Conclusion Expression of heparanase was observed in 50% of the STS, in various histological subtypes. A larger study with homogenous groups of specific sub-types of STS or stages of disease is required to validate over-expression of heparanase as a marker of disease aggressiveness. [ABSTRACT FROM AUTHOR]

Mutation of the melanocortin-receptor 4 (MC4R) is the most frequent cause of severe obesity in humans. Binding of agoutirelated peptide (AgRP) to MC4R involves the co-receptor syndecan-3, a heparan sulfate proteoglycan. The proteoglycan can be structurally modified by the enzyme heparanase. Here we tested the hypothesis that heparanase plays a role in food intake behaviour and energy balance regulation by analysing body weight, body composition and food intake in genetically modified mice that either lack or overexpress heparanase. We also assessed food intake and body weight following acute central intracerebroventricular administration of heparanase; such treatment reduced food intake in wildtype mice, an effect that was abolished in mice lacking MC4R. By contrast, heparanase knockout mice on a high-fat diet showed increased food intake and maturity-onset obesity, with up to a 40% increase in body fat. Mice overexpressing heparanase displayed essentially the opposite phenotypes, with a reduced fat mass. These results implicate heparanase in energy balance control via the central melanocortin system. Our data indicate that heparanase acts as a negative modulator of AgRP signaling at MC4R, through cleavage of heparan sulfate chains presumably linked to syndecan-3. [ABSTRACT FROM AUTHOR]

Heparanase is an endoglycosidase that specifically cleaves heparan sulphate side chains of heparan sulphate proteoglycans, activity that is strongly implicated in cell migration and invasion associated with tumour metastasis, angiogenesis and inflammation. Heparanase up-regulation was documented in an increasing number of human carcinomas, correlating with reduced post-operative survival rate and enhanced tumour angiogenesis. Expression and significance of heparanase in human sarcomas has not been so far reported. Here, we applied the Ewing's sarcoma cell line TC71 and demonstrated a potent inhibition of cell invasion in vitro and tumour xenograft growth in vivo upon treatment with a specific inhibitor of heparanase enzymatic activity (compound SST0001, non-anticoagulant N-acetylated, glycol split heparin). Next, we examined heparanase expression and cellular localization by immunostaining of a cohort of 69 patients diagnosed with Ewing's sarcoma. Heparanase staining was noted in all patients. Notably, heparanase staining intensity correlated with increased tumour size ( P = 0.04) and with patients' age ( P = 0.03), two prognostic factors associated with a worse outcome. Our study indicates that heparanase expression is induced in Ewing's sarcoma and associates with poor prognosis. Moreover, it encourages the inclusion of heparanase inhibitors ( i.e. SST0001) in newly developed therapeutic modalities directed against Ewing's sarcoma and likely other malignancies. [ABSTRACT FROM AUTHOR]

Background: Heparanase modulates the level of heparan sulfate proteoglycans (HSPGs) which have an important role in multiple cellular processes. Recent studies indicate that HSPGs have an important function in hepatic lipoprotein handling and processes involving removal of lipoprotein particles. Principal Findings: To determine the effects of decreased HSPGs chain length on lipoprotein metabolism and atherosclerosis, transgenic mice over-expressing the human heparanase gene were studied. Hepatic lipid uptake in hpa- Tg mice were evaluated by giving transgenic mice oral fat loads and labeled retinol. Sections of aorta from mice overexpressing heparanase (hpa-Tg) and controls (C57/BL6) fed an atherogenic diet were examined for evidence of atherosclerosis. Heparanase over-expression results in reduced hepatic clearance of postprandial lipoproteins and higher levels of fasting and postprandial serum triglycerides. Heparanase over-expression also induces formation of fatty streaks in the aorta. The mean lesion cross-sectional area in heparanase over-expressing mice was almost 6 times higher when compared to control mice (23,984 μm2±5,922 vs. 4,189 μm2±,130, p<0.001). Conclusions: Over-expression of heparanase demonstrates the importance of HSPGs for the uptake of intestinal derived lipoproteins and its role in the formation of fatty streaks. [ABSTRACT FROM AUTHOR]

The article discusses the role of heparan sulfate proteoglycans (HSPGs) in controlling arterial structure, mechanics and remodeling. Heparanase expression in endothelial cells serves as a negative regulator of endothelial inhibition of vascular smooth muscle cells proliferation. It was also found that increased neointimal formation and macrophage recruitment occurs in transgenic mice overexpressing heparanase.

Heparanase is a heparan sulfate (HS) degrading endoglycosidase participating in extracellular matrix degradation and remodeling. Apart of its well characterized enzymatic activity, heparanase was noted to exert also enzymatic-independent functions. Non-enzymatic activities of heparanase include enhanced adhesion of tumor-derived cells and primary T-cells. Attempting to identify functional domains of heparanase that would serve as targets for drug development, we have identified heparin binding domains of heparanase. A corresponding peptide (residues Lys158-Asp171, termed KKDC) was demonstrated to physically associate with heparin and HS, and to inhibit heparanase enzymatic activity. We hypothesized that the pro-adhesive properties of heparanase are mediated by its interaction with cell surface HS proteoglycans, and utilized the KKDC peptide to examine this possibility. We provide evidence that the KKDC peptide interacts with cell membrane HS, resulting in clustering of syndecan-1 and syndecan-4. We applied classical analysis of cell morphology, fluorescent and time-lapse microscopy and demonstrated that the KKDC peptide efficiently stimulates the adhesion and spreading of various cell types, mediated by PKC, Src, and the small GTPase Rac1. These results support, and further substantiate the notion that heparanase function is not limited to its enzymatic activity. [ABSTRACT FROM AUTHOR]

Patients on chronic hemodialysis (HD) are at high risk for developing atherosclerosis and cardiovascular complications. Heparanase, an endoglycosidase that cleaves heparan sulfate (HS) side chains of proteoglycans, is involved in extracellular matrix degradation and, as such, may be involved in the atherosclerotic lesion progression. We hypothesize that heparanase is elevated in HD patients, partly due to its release from primed circulating polymorphonuclear leukocytes (PMNLs), undergoing degranulation. Priming of PMNLs was assessed by levels of CD11b and the rate of superoxide release. Heparanase mRNA expression in PMNLs was determined by RT-PCR. PMNL and plasma levels of heparanase were determined by immunoblotting, immunofluorescence, and flow cytometry analyses. The levels of soluble HS in plasma were measured by a competition ELISA. This study shows that PMNLs isolated from HD patients have higher mRNA and protein levels of heparanase compared with normal control (NC) subjects and that heparanase levels correlate positively with PMNL priming. Plasma levels of heparanase were higher in HD patients than in NC subjects and were further elevated after the dialysis session. In addition, heparanase expression inversely correlates with plasma HS levels. A pronounced expression of heparanase was found in human atherosclerotic lesions. The increased heparanase activity in the blood of HD patients results at least in part from the degranulation of primed PMNLs and may contribute to the acceleration of the atherosclerotic process. Our findings highlight primed PMNLs as a possible source for the increased heparanase in HD patients, posing heparanase as a new risk factor for cardiovascular complications and atherosclerosis. [ABSTRACT FROM AUTHOR]

Heparan sulfate proteoglycans (HSPGs) interact with numerous proteins of importance in animal development and homeostasis. Heparanase, which is expressed in normal tissues and upregulated in angiogenesis, cancer and inflammation, selectively cleaves β-glucuronidic linkages in HS chains. In a previous study, we transgenically overexpressed heparanase in mice to assess the overall effects of heparanase on HS metabolism. Metabolic labeling confirmed extensive fragmentation of HS in vivo. In the current study we found that in liver showing excessive heparanase overexpression, HSPG turnover is accelerated along with upregulation of HS N- and O-sulfation, thus yielding heparin-like chains without the domain structure typical of HS. Heparanase overexpression in other mouse organs and in human tumors correlated with increased 6-O-sulfation of HS, whereas the domain structure was conserved. The heavily sulfated HS fragments strongly promoted formation of ternary complexes with fibroblast growth factor 1 (FGF1) or FGF2 and FGF receptor 1. Heparanase thus contributes to regulation of HS biosynthesis in a way that may promote growth factor action in tumor angiogenesis and metastasis. [ABSTRACT FROM AUTHOR]

Heparan sulfate proteoglycans (HSPGs) are ubiquitous macromolecules. In bone, they are associated with cell surfaces and the extracellular matrix (ECM). The heparan sulfate (HS) chains of HSPGs bind a multitude of bioactive molecules, thereby controlling normal and pathologic processes. The HS-degrading endoglycosidase, heparanase, has been implicated in processes such as inflammation, vascularization associated with wound healing and malignancies, and cancer metastasis. Here we show progressive mRNA expression of the hpa gene (encoding heparanase) in murine bone marrow stromal cells undergoing osteoblastic (bone forming) differentiation and in primary calvarial osteoblasts. Bone marrow stromal cells derived from transgenic mice expressing recombinant human heparanase (rh-heparanase) and MC3T3 E1 osteoblastic cells exposed to soluble rh-heparanase spontaneously undergo osteogenic differentiation. In addition, the transgenic bone marrow stromal cells degrade HS chains. In wild-type (WT) and hpa-transgenic (hpa-tg) mice, heparanase is weakly expressed throughout the bone marrow with a substantial increase in osteoblasts and osteocytes, especially in the hpa-tg mice. Heparanase expression was absent in osteoclasts. Micro-computed tomographic and histomorphometric skeletal analyses in male and female hpa-tg versus WT mice show markedly increased trabecular bone mass, cortical thickness, and bone formation rate, but no difference in osteoclast number. Collectively, our data suggest that proteoglycans tonically suppress osteoblast function and that this inhibition is alleviated by HS degradation with heparanase. J. Cell. Physiol. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Heparan sulfate (HS) proteoglycans play a key role in the self-assembly, insolubility and barrier properties of the extracellular matrix (ECM). Cleavage of HS therefore affects the integrity of tissues and hence normal and pathological phenomena involving cell migration and response to changes in the ECM. Mammalian heparanase. HS-degrading endoglycosidase, is synthesized as a latent 65 kDa precursor that undergoes proteolytic cleavage, yielding 8 kDa and 50 kDa subunits that heterodimerize to form a highly active enzyme. Heparanase is preferentially expressed in human tumors and its over-expression in tumor cells confers an invasive phenotype in experimental animals. Heparanase also releases angiogenic factors from the ECM and tumor microenvironment and thereby induces an angiogenic response in vivo. Enhanced heparanase expression correlates with metastatic potential, tumor vascularity and reduced postoperative survival of cancer patients. Heparanase also promotes cell adhesion, survival and signaling events, independent of its enzymatic activity. These observations, the anti-cancerous effect of heparanase gene silencing and of heparanase- inhibiting molecules as well as the unexpected identification of a predominant functional heparanase. suggest that the enzyme is a promising target for anti-cancer drug development. Here, we summarize recent progress in molecular and cellular aspects of heparanase, emphasizing its causal involvement in cancer metastasis and angiogenesis, and discuss the development of heparin-like heparanase inhibitors. [ABSTRACT FROM AUTHOR]

Heparan sulfate (HS) side chains of HS proteoglycans bind to and assemble extracellular matrix proteins and play important roles in cell-cell and cell-extracellular matrix interactions. HS chains bind a multitude of bioactive molecules and thereby function in the control of multiple normal and pathological processes. Enzymatic degradation of HS by heparanase, a mammalian endoglycosidase, affects the integrity and functional state of tissues and is involved in, among other processes, inflammation, angiogenesis, and cancer metastasis. Here, we report the cloning of heparanase from four Israeli species of the blind subterranean mole rat (Spalax ehrenbergi superspecies), 85% homologous to the human enzyme. Unlike its limited expression in human tissues, heparanase is highly expressed in diverse Spalax tissues. Moreover, we have identified a unique splice variant of the Spalax enzyme lacking 16 aa encoded by exon 7. This deletion resulted in a major defect in trafficking and processing of the heparanase protein, leading to a loss of its enzymatic activity. Interspecies variation was noted in the sequence and in the expression of the splice variant of the heparanase gene in blind mole rats living under different ecogeographical stresses, indicating a possible role in adaptation to stress in Spalax evolution. [ABSTRACT FROM AUTHOR]

Mammalian heparanase (endo-ß-glucuronidase) degrades heparan sulfate proteoglycans and is an important modulator of the extracellular matrix and associated factors. The enzyme is preferentially expressed in neoplastic tissues and contributes to tumour metastasis and angiogenesis. To investigate the epigenetic regulation of the heparanase locus, methylation-specific and bisulfite PCR were performed on a panel of 22 human cancer cell lines. Cytosine methylation of the heparanase promoter was associated with inactivation of the affected allele. Despite lack of sequence homology, extensively methylated CpG islands were found both in human choriocarcinoma (JAR) and rat glioma (C-6) cells which lack heparanase activity. Treatment of these cells with demethylating agents (5-azacytidine, 5-aza-2'-deoxycytidine) resulted in stable dose- and time-dependant promoter hypomethylation accompanied by reappearance of heparanase mRNA, protein and enzymatic activity. An inhibitor of histone deacetylase, Trichostatin A, failed to induce either of these effects. Upregulation of heparanase expression and activity by demethylating drugs was associated with a marked increase in lung colonization by pretreated C-6 rat glioma cells. The increased metastatic potential in vivo was inhibited in mice treated with laminaran sulfate, a potent inhibitor of heparanase activity. We propose a model wherein expression of mammalian heparanase gene is modulated by the interplay between trans-activating genetic and cis-inhibitory epigenetic elements in its promoter.Oncogene (2003) 22, 7737-7749. doi:10.1038/sj.onc.1207056 [ABSTRACT FROM AUTHOR]

Cleavage of heparan sulphate proteoglycans (HSPGs) affects the integrity and functional state of tissues and thereby fundamental normal and pathological phenomena involving cell migration and response to changes in the extracellular microenvironment. Heparanase, degrading heparan sulphate (HS) at specific intrachain sites, is synthesized as a latent ∼65 kDa protein that is processed at the N-terminus into a highly active ∼50 kDa form. The heparanase enzyme is preferentially expressed in human tumours and its overexpression in low-metastatic tumour cells confers a highly invasive phenotype in experimental animals. Heparanase also releases angiogenic factors and accessory fragments of HS from the tumour microenvironment and induces an angiogenic response in vivo. Heparanase may thus facilitate tumour cell invasion, vascularization and survival in a given microenvironment, all critical events in cancer progression. These observations, the anticancerous effect of heparanase-inhibiting molecules, and the unexpected identification of a single predominant functional heparanase suggest that the enzyme is a promising target for drug development. [Copyright &y& Elsevier]

Tumor extracellular matrix (ECM) operates in a coordinated mode with cancer and stroma cells to evoke the multistep process of metastatic potential. The remodeled tumor-associated matrix provides a point for direct or complementary therapeutic targeting. Here, we cover and critically address the importance of ECM networks and their macromolecules in cancer. We focus on the roles of key structural and functional ECM components, and their degradation enzymes and extracellular vesicles, aiming at improving our understanding of the mechanisms contributing to tumor initiation, growth, and dissemination, and discuss potential new approaches for ECM-based therapeutic targeting and diagnosis. Modified extracellular matrix in the tumor microenvironment dictates cancer cell properties, metastatic potential, and formation of premetastatic niches. Proteoglycans and hyaluronan in provisional matrix modulate the bioavailability of matrix-bound effectors, cancer cell signaling, angiogenesis, and tumor spread. The outside-in interactions of integrins with tumor matrix, the migratory tracks for cancer cells created by fibrillar collagen fiber alignment, and the intense trafficking of extracellular vesicles, impact tumor progression. Proteolytic (matrix metalloproteinases and cathepsins) and glycosidic (heparanase and hyaluronidases) enzymes mediate protumorigenic interactions and stemness, associated with therapeutic resistance. Heparanase promotes the aggressive phenotype of cancer, while heparanase-2 functions as a tumor suppressor. Interference with exosome biogenesis, miRNAs functions, provisional matrix and premetastatic niche formation, may drive future cancer therapeutics. [ABSTRACT FROM AUTHOR]

Heparan sulfate (HS) and HS proteoglycans (HSPGs) colocalize with amyloid-β (Aβ) deposits in Alzheimer disease brain and in Aβ precursor protein (AβPP) transgenic mouse models. Heparanase is an endoglycosidase that specifically degrades the unbranched glycosaminoglycan side chains of HSPGs. The aim of this study was to test the hypothesis that HS and HSPGs are active participators of Aβ pathogenesisin vivo. We therefore generated a double-transgenic mouse model overexpressing both human heparanase and human AβPP harboring the Swedish mutation (tgHpa*Swe). Overexpression of heparanase did not affect AβPP processing because the steady-state levels of Aβ1-40, Aβ1-42, and soluble AβPP β were the same in 2- to 3-month-old double-transgenic tgHpa*Swe and single-transgenic tgSwe mice. In contrast, the Congo red-positive amyloid burden was significantly lower in 15-month-old tgHpa*Swe brain than in tgSwe brain. Likewise, the Aβ burden, measured by Aβx-40 and Aβx-42 immunohistochemistry, was reduced significantly in tgHpa*Swe brain. The intensity of HS-stained plaques correlated with the Aβx-42 burden and was reduced in tgHpa*Swe mice. Moreover, the HS-like molecule heparin facilitated Aβ1-42-aggregation in an in vitro Thioflavin T assay. The findings suggest that HSPGs contribute to amyloid deposition in tgSwe mice by increasing Aβ fibril formation because heparanase-induced fragmentation of HS led to a reduced amyloid burden. Therefore, drugs interfering with Aβ-HSPG interactions might be a potential strategy for Alzheimer disease treatment. [ABSTRACT FROM AUTHOR]

Abstract: Heparanase is a heparan sulfate (HS) degrading endoglucuronidase that has been implicated in cell migration and inflammatory conditions. Here we used mice deficient of heparanase (Hpse −/−) to study the impact of heparanase on airway leukocytes. Normal numbers of macrophages and lymphocytes were present in bronchoalveolar lavage fluid of Hpse −/− mice, indicating that heparanase is not essential for proper homing of leukocytes to airways. While lymphocytes from Hpse −/− mice displayed normal morphology, Hpse −/− alveolar macrophages showed a striking, age-dependent appearance of granule-like structures in the cytoplasm. Transmission electron microscopy revealed that these structures corresponded to membrane-enclosed crystalline bodies that closely resembled the intracellular crystals known to be formed by the HS-binding protein Ym1, suggesting that heparanase deficiency is associated with intracellular Ym1 deposition. Indeed, applying immunocytochemistry, we found markedly higher levels of intracellular Ym1 protein in Hpse −/− versus WT alveolar macrophages, and there was a significant correlation between levels of Ym1 protein detected by immunoblotting and amounts of crystalline material in BAL cells. Biosynthetic radio-labeling of the macrophages revealed accumulation of non-degraded HS chains in Hpse −/− macrophages. Together, these findings implicate heparanase in normal processing of HS in macrophages, and indicate that heparanase regulates intracellular Ym1 accumulation and crystal formation in airways. [Copyright &y& Elsevier]

Heparanase is an endoglycosidase that specifically cleaves heparan sulfate (HS) side chains of HS proteoglycans, the major proteoglycans in the extracellular matrix and cell surfaces. Traditionally, heparanase activity was implicated in cellular invasion associated with angiogenesis, inflammation, and cancer metastasis. More recently, heparanase upregulation was documented in an increasing number of primary human tumors, correlating with reduced postoperative survival rate and enhanced tumor angiogenesis. In the present study, we examined the expression of heparanase in squamous cell carcinoma of the head and neck by means of immunostaining, and we correlated expression levels with patient outcome. The intensity and extent of heparanase staining correlated with tumor stage (P = .049 and P = .027, respectively), and the extent of staining further correlated with tumor grade (P = .047). Moreover, heparanase expression inversely correlated with patient status at the end of the study (P = .012). Notably, heparanase localization was found to be an important parameter for patient status. Thus, 63% of patients with nuclear staining, compared to 19% of patients with cytoplasmic staining (P = .0043), were alive, indicating that nuclear localization of the enzyme predicts a favorable outcome. [ABSTRACT FROM AUTHOR]

Objective: To improve mouse embryonic implantation by recombinant heparanase supplementation. Heparanase, an endoglycosidase-degrading heparan sulfate proteoglycan, may have a role in embryonic implantation because of its enzymatic, angiogenic, and adhesive properties. Increasing endometrial receptivity could improve one of the most difficult pathologies in human fertility. Design: Comparison between mouse blastocysts obtained after 24-hour incubation of morulae with or without heparanase. Setting: Experimental laboratory in a medical center. Animal(s): Mice. Intervention(s): Morulae were flushed from CB6F1 female mice and incubated for 24 hours at 37°C in M16 medium supplemented with 0.1 mg/mL heparanase (n = 203), with albumin (n = 60), or with medium alone (n = 258). Main outcome measure(s): Blastocysts were evaluated by heparanase immunostaining (n = 10), activity assay (n = 283), and transfer to foster mice uterine horns (n = 228). The number of implantation sites was compared. Result(s): Immunostaining demonstrated that heparanase is constitutively expressed in mouse morulae and blastocyts. Heparanase supplementation resulted in increased staining and enzymatic activity in blastocyts. Implantation rates for the heparanase, M16 medium, and albumin groups, were 36.9%, 17.8%, and 20%, respectively (P<.01). Conclusion(s): Heparanase was found to be constitutively expressed by blastocyst-stage embryos. Moreover, the amount of heparanase was markedly increased by incubation of morulae with recombinant heparanase, evaluated by immunostaining and enzymatic activity. Heparanase supplementation resulted in approximately a twofold increase in embryo implantation rate in vivo. Taken together, these data suggest that heparanase is actively involved in embryo implantation. [Copyright &y& Elsevier]

Heparanase is a mammalian endoglycosidase that degrades heparan sulfate (HS) at specific intrachain sites, an activity that is strongly implicated in cell dissemination associated with metastasis and inflammation. In addition to its structural role in extracellular matrix assembly and integrity, HS sequesters a multitude of polypeptides that reside in the extracellular matrix as a reservoir. A variety of growth factors, cytokines, chemokines, and enzymes can be released by heparanase activity and profoundly affect cell and tissue function. Thus, heparanase bioavailability, accessibility, and activity should be kept tightly regulated. We provide evidence that HS is not only a substrate for, but also a regulator of, heparanase. Addition of heparin or xylosides to cell cultures resulted in a pronounced accumulation of, heparanase in the culture medium, whereas sodium chlorate had no such effect. Moreover, cellular uptake of heparanase was markedly reduced in HS-deficient CHO-745 mutant cells, heparan sulfate proteoglycan-deficient HT-29 colon cancer cells, and heparinase. treated cells. We also studied the heparanase biosynthetic route and found that the half-life of the active enzyme is ∼30 h. This and previous localization studies suggest that heparanase resides in the endosomal/lysosomal compartment for a relatively long period of time and is likely to play a role in the normal turnover of HS. Co-localization studies and cell fractionation following heparanase addition have identified syndecan family members as candidate molecules responsible for heparanase uptake, providing an efficient mechanism that limits extracellular accumulation and function of heparanase. [ABSTRACT FROM AUTHOR]

Heparanase is an endo-glucuronidase expressed in a variety of tissues and cells that selectively cleaves extracellular and cell-surface heparan sulfate. Here we propose that this enzyme is involved also in the processing of serglycin heparin proteoglycan in mouse mast cells. In this process, newly synthesized heparin chains (60-100 kDa) are degraded to fragments (10-20 kDa) similar in size to commercially available heparin (Jacobsson, K. G., and Lindahl, U. (1987) Biochem. J. 246, 409-415). A fraction of these fragments contains the specific pentasaccharide sequence required for high affinity binding to antithrombin implicated with anticoagulant activity. Rat skin heparin, which escapes processing in vivo, was used as a substrate in reaction with recombinant human heparanase. An incubation product of commercial heparin size retained the specific pentasaccharide sequence, although oligosaccharides (3-4 kDa) containing this sequence could be degraded by the same enzyme. Commercial heparin was found to be a powerful inhibitor (I[sub 50] ∼20 nM expressed as disaccharide unit, ∼0.7 nM polysaccharide) of heparanase action toward antithrombin-binding oligosaccharides. Cells derived from a serglycin-processing mouse mastocytoma expressed a protein highly similar to other mammalian heparanases. These findings strongly suggest that the intracellular processing of the heparin proteoglycan polysaccharide chains is catalyzed by heparanase, which primarily cleaves target structures distinct from the antithrombin-binding sequence. [ABSTRACT FROM AUTHOR]