Anti-heparanase monoclonal antibody enhances heparanase enzymatic activity and facilitates wound healing

Elucidating the Consequences of Heparan Sulfate Binding by Heparanase 2

Unlike the intense research effort devoted to exploring the significance of heparanase in human diseases, very little attention was given to its close homolog, heparanase 2 (Hpa2). The emerging role of Hpa2 in a rare autosomal recessive congenital disease called urofacial syndrome (UFS), clearly indicates that Hpa2 is not a pseudogene but rather a gene coding for an important protein. Hpa2 lacks the heparan sulfate (HS)-degrading activity typical of heparanase, yet exhibits high affinity to HS, affinity that is 10-fold higher than that of heparanase. The consequences of this high-affinity interaction of Hpa2 with plasma membrane HSPG has not been explored yet. Here, we used highly purified Hpa2 protein to examine this aspect. We provide evidence that cells adhere to and spread on dishes coated with Hpa2. We also show that cell migration is attenuated markedly by exogenous addition of Hpa2 to primary and transformed cells, a function that agrees with the anti-cancer properties of Hpa2. Interestingly, we found that exogenous addition of Hpa2 also disrupts the morphology of cell colonies, resulting in cell scattering. This implies that under certain conditions and experimental settings, Hpa2 may exhibit pro-tumorigenic properties. We further developed a panel of anti-Hpa2 monoclonal antibodies (mAb) and show that these properties of Hpa2 are prevented by some of the newly-developed mAb, thus providing new molecular tools to better appreciate the significance of Hpa2 in health and disease.

Heparanase Inhibitors Facilitate the Assembly of the Basement Membrane in Artificial Skin

Recent research suggests that the basement membrane at the dermal-epidermal junction of the skin plays an important role in maintaining a healthy epidermis and dermis, and repeated damage to the skin can destabilize the skin and accelerate the aging process. Skin-equivalent models are suitable for studying the reconstruction of the basement membrane and its contribution to epidermal homeostasis because they lack the basement membrane and show abnormal expression of epidermal differentiation markers. By using these models, it has been shown that reconstruction of the basement membrane is enhanced not only by supplying basement membrane components, but also by inhibiting proteinases such as urokinase and matrix metalloproteinase. Although matrix metalloproteinase inhibitors assist in the reconstruction of the basement membrane structure, their action is not sufficient to promote its functional recovery. However, heparanase inhibitors stabilize the heparan sulfate chains of perlecan (a heparan sulfate proteoglycan) and promote the regulation of heparan sulfate binding growth factors in the basement membrane. Heparan sulfate promotes effective protein-protein interactions, thereby facilitating the assembly of type VII collagen anchoring fibrils and elastin-associated microfibrils. Using both matrix metalloproteinase inhibitors and heparanase inhibitors, the basement membrane in a skin-equivalent model comes close to recapitulating the structure and function of an in vivo basement membrane. Therefore, by using an appropriate dermis model and suitable protease inhibitors, it may be possible to produce skin-equivalent models that are more similar to natural skin

Heparanase-neutralizing antibodies attenuate lymphoma tumor growth and metastasis

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 heparanase-neutralizing 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.

Clinical significance of heparanase splice variant (t5) in renal cell carcinoma: evaluation by a novel t5-specific monoclonal antibody

T5 is a novel splice variant of heparanase, an endo-β-D-glucuronidase capable of cleaving heparan sulfate side chains at a limited number of sites. T5 splice variant is endowed with pro-tumorigenic properties, enhancing cell proliferation, anchorage independent growth and tumor xenograft development despite lack of heparan sulfate-degrading activity typical of heparanase. T5 is over expressed in the majority of human renal cell carcinoma biopsies examined, suggesting that this splice variant is clinically relevant. T5 is thought to assume a distinct three-dimensional conformation compared with the wild type heparanase protein. We sought to exploit this presumed feature by generating monoclonal antibodies that will recognize the unique structure of T5 without, or with minimal recognition of heparanase, thus enabling more accurate assessment of the clinical relevance of T5. We provide evidence that such a monoclonal antibody, 9c9, preferentially recognizes T5 compared with heparanase by ELISA, immunoblotting and immunohistochemistry. In order to uncover the clinical significance of T5, a cohort of renal cell carcinoma specimens was subjected to immunostaining applying the 9c9 antibody. Notably, T5 staining intensity was significantly associated with tumor size (p = 0.004) and tumor grade (p = 0.02). Our results suggest that T5 is a functional, pro-tumorigenic entity.

Overexpression of heparanase multiple antigenic peptide 2 is associated with poor prognosis in gastric cancer: Potential for therapy

Tumor-associated antigens (TAAs) trigger a TAA-specific immune response, thus they are the crux of antitumor immunosurveillance. A major advance in tumor immunology in the last 20 years was marked by the verification that CTL or B-cell epitopes rather than integral TAAs induce immunoreactivity. Previous studies on the correlation between heparanase (Hpa) expression and clinical or pathological features have generally used commercial antibodies against full-length Hpa protein rather than the functional epitopes, and the antigen determinants of such antibodies have not yet been defined. In our investigation of Hpa peptide expression in gastric cancer tissues and its association with tumor invasion, metastasis and prognosis, we analyzed Hpa expression in the tissues of 132 patients with gastric cancer using tissue microarray (TMA) technology and immunohistochemical staining. Three self-developed rabbit polyclonal antibodies against Hpa multiple antigenic peptides (MAP) and one commercial polyclonal rabbit antibody against the 50-8 kDa Hpa heterodimer were used. Clinical and pathological significance was evaluated using the Chi-square test and Kaplan-Meier survival curve analysis. The results demonstrated that the positivity rates using the antibody against MAP2 and the commercial antibody were 60.6% (80/132) and 65.2% (86/132), respectively. No expression of either MAP1 or MAP3 was noted in the cancer tissues of the 132 cases. MAP2 behaved in a similar manner to the commercial antibody in that a higher Hpa expression was observed in the cancer tissues with vessel invasion, serosal involvement, distant metastasis, poor differentiation and TNM stages III and IV. Moreover, the patients with a positive Hpa expression had a far poorer prognosis, with lower one-year and five-year survival rates. Our results demonstrate that in a similar manner to full-length Hpa proteins, MAP2 expression is closely associated with the invasion, metastasis and prognosis of gastric cancer. This finding may be of potential use in clinical therapy and in estimating the prognosis of a tumor.

Activation of heparanase by ultraviolet B irradiation leads to functional loss of basement membrane at the dermal-epidermal junction in human skin

Recently, we reported that heparanase plays important roles in barrier-disrupted skin, leading to increased interaction of growth factors between epidermis and dermis and facilitating various cutaneous changes, including epidermal hyperplasia and wrinkle formation. However, the role of heparanase in sun-exposed skin remains unknown. Here, we show that heparanase in human keratinocytes is activated by ultraviolet B (UVB) exposure and that heparan sulfate of perlecan is markedly degraded in UVB-irradiated human skin. The degradation of heparan sulfate resulted in a marked reduction of binding activity of the basement membrane for vascular endothelial growth factor, fibroblast growth factor-2 and -7 at the dermal-epidermal junction. Degradation of heparan sulfate was observed not only in acutely UVB-irradiated skin, but also in skin chronically exposed to sun. Interestingly, heparan sulfate was found to be degraded in sun-exposed skin, but not in sun-protected skin. These findings suggest that chronic UVB exposure activates heparanase, leading to degradation of heparan sulfate in the basement membrane and increased growth factor interaction between epidermis and dermis. These changes may facilitate photo-aging.

Heparanase 2 interacts with heparan sulfate with high affinity and inhibits heparanase activity

Heparanase activity is highly implicated in cell dissemination associated with tumor metastasis, angiogenesis, and inflammation. Heparanase expression is induced in many hematological and solid tumors, associated with poor prognosis. Heparanase homolog, termed heparanase 2 (Hpa2), was cloned based on sequence homology. Detailed characterization of Hpa2 at the biochemical, cellular, and clinical levels has not been so far reported, and its role in normal physiology and pathological disorders is obscure. We provide evidence that unlike heparanase, Hpa2 is not subjected to proteolytic processing and exhibits no enzymatic activity typical of heparanase. Notably, the full-length Hpa2c protein inhibits heparanase enzymatic activity, likely due to its high affinity to heparin and heparan sulfate and its ability to associate physically with heparanase. Hpa2 expression was markedly elevated in head and neck carcinoma patients, correlating with prolonged time to disease recurrence (follow-up to failure; p = 0.006) and inversely correlating with tumor cell dissemination to regional lymph nodes (N-stage; p = 0.03). Hpa2 appears to restrain tumor metastasis, likely by attenuating heparanase enzymatic activity, conferring a favorable outcome of head and neck cancer patients.

Retinal heparanase expression in streptozotocin-induced diabetic rats

OBJECTIVE

Heparanase, an endoglycosidase, exhibits strong proangiogenic capacity that can induce vascular endothelial growth factor (VEGF) expression in tumour angiogenesis. The purpose of this study was to evaluate heparanase expression and its relationship with VEGF in streptozotocin (STZ)-induced diabetic rats' retinas.

DESIGN

Experimental study.

PARTICIPANTS

STZ-induced rats and non-diabetic control rats.

METHODS

Heparanase expression was initially evaluated in cultured human retinal microvascular endothelial cells (HRECs) under high-glucose conditions by Western blot. Diabetes was induced in Sprague-Dawley rats by STZ intraperitoneal injection. Retinal heparanase expression was assayed in rats by immunohistochemistry. Heparanase inhibitor (phosphomannopentaose sulfate) was administrated to high-glucose-treated HRECs and diabetic rats. VEGF levels were evaluated in HRECs and retinas using enzyme-linked immunosorbent assay.

RESULTS

Heparanase expression was increased in HRECs under high-glucose conditions compared with controls (p < 0.01). Immunohistochemical studies indicated that heparanase signals were intense in the retinal vascular endothelia of diabetic rats, but faint in those of nondiabetic control rats. Quantitative analysis showed that heparanase protein expression was increased by 3.2-fold in diabetic rats' retinas compared with nondiabetic rats' retinas (p < 0.01). VEGF level was increased, as was heparanase expression, in high-glucose-treated HRECs and in the retinas of diabetic rats, and these increases were significantly decreased by phosphomannopentaose sulfate administration (p < 0.01).

CONCLUSIONS

Heparanase expression was upregulated and associated with an increase of VEGF expression in STZ-induced diabetic rat retinas. The data suggest that heparanase may be involved in the development of diabetic retinopathy and represents a possible novel target for therapeutic intervention.

Screening and identification of novel B cell epitopes in human heparanase and their anti-invasion property for hepatocellular carcinoma

BACKGROUND

The aim of this study was to screen and identify novel B cell epitopes within the human heparanase protein and to investigate the impact of self-developed anti-heparanase polypeptide antibodies on growth and invasion of HCCLM6 human hepatocellular carcinoma cells in vitro.

METHODS

The flexible regions of secondary structure and the B cell epitopes of the human heparanase amino acid sequence were predicted by DNAStar and Bcepred software.The multiple antigenic peptides (MAP) of the epitopes were synthesized in eight-branched form. Rabbits were immunized with the eight-branched MAPs mixed with the universal T-helper epitope human IL-1beta peptide (VQGEESNDK, amino acid 163-171). The immunogenicity of the synthesized peptides was evaluated by ELISA, western blot and immunohistochemistry. The impact of the self-developed rabbit anti-heparanase polyclonal antibodies on growth and invasion ability of HCCMLM6 cells were analyzed in a cell culture model. The cells were first treated with one of the three antibodies, respectively, and then measured by using MTT, flow cytometry, plate clone formation, invasion assay and heparan sulfate degrading enzyme assay.

RESULTS

The three amino acid sequences 1-15 (MAP1), 279-293 (MAP2), and 175-189 (MAP3) in the large subunit of the human heparanase protein were predicted as its most potential epitopes. ELISA, western blot and immunohistochemistry analysis showed that all three MAPs were capable to induce high titer of serum antibodies. Antibodies induced by MAP1 and MAP2 were high specific. Furthermore, anti-MAP2 antibodies showed the strongest avidity towards liver cancer tissues. Under the treatment with the three anti-heparanase antibodies, respectively, the growth, cell cycle and clone formation of the cells remained unchanged when compared with a treatment with normal rabbit IgG. However, an inhibition of cell invasiveness and heparanase activity could be detected under the treatment with anti-MAP1- or anti-MAP2-antibody (with a terminal concentration of 100 mug/ml). The cell invasiveness was decreased by 54 and 38%, respectively, the heparanase activity by 43 and 39%, respectively.

CONCLUSION

The multiple antigenic peptides MAP1 (AC 1-15) and MAP2 (AC 279-293) may be the dominant B cell epitopes in the human heparanase protein. The induced polypeptide antibodies can effectively inhibit the heparanase activity of HCCLM6 liver cancer cells and therefore influence their invasion ability, which provides a theoretic basis for the development of anti-heparanase antibodies and their clinical use as vaccine.

Trophoblast-derived heparanase is not required for invasion

To invade the decidua and myometrium, extravillous trophoblast must degrade an assortment of extracellular matrix (ECM) components. The uterine wall is rich in heparan sulphate proteoglycans (HSPG), which interact with collagen, laminin and fibronectin, and bind a variety of growth factors. HSPG are catabolised by heparanase, an enzyme that is highly expressed in the placenta. The aim of this study was to investigate the role of heparanase in first trimester trophoblast invasion. First trimester cytotrophoblasts (CTB) were isolated by trypsin digestion followed by centrifugation on a Percoll gradient. Cells were cultured on Matrigel to promote an extravillous phenotype. Heparanase expression was studied by immunohistochemistry and confocal microscopy. Trophoblast invasion was assessed using an in vitro transwell assay. A high level of heparanase was observed in isolated first trimester trophoblast; however, a function-blocking antibody did not inhibit invasion of primary CTB or the extravillous trophoblast cell line SGHPL-4 at 21% oxygen. In contrast to cancer cells, heparanase expression was not increased following culture at 3% oxygen, and trophoblast invasion was not retarded by the blocking antibody under these conditions. Heparanase expression was observed in stromal cells and vascular endothelium in first trimester parietal decidua. Expression was evident on the cell surface and in the nucleus of trophoblast and decidual cells. In conclusion, trophoblast heparanase is not required for invasion in vitro. Its abundant expression suggests another role during pregnancy, perhaps in controlling the availability of ECM-bound growth factors or acting as a transcription factor.

Heparanase: a novel target of tumor metastasis therapy

Heparanase plays a key role in promoting tumor angiogenesis, vasiveness and metastasis. This predominant enzyme is primarily responsible for cleaving heparin sulphate, the main polysaccharide constituent of extracellular matrix and basement membrane, thus having become a novel target of tumor therapy. It can prevent tumor growth and metastasis by inhibiting its expression and reducing its activity. This paper reviews the biological characteristics of heparanase as a target of tumor therapy, the significance in tumor progression and tumor therapies, and the prospect of its relating medicine in clinical applications.

Changes in heparan sulfate are associated with delayed wound repair, altered cell migration, adhesion and contractility in the galactosyltransferase I (beta4GalT-7) deficient form of Ehlers-Danlos syndrome

Reduced activity of beta4-galactosyltransferase 7 (beta4GalT-7), an enzyme involved in synthesizing the glycosaminoglycan linkage region of proteoglycans, is associated with the progeroid form of Ehlers-Danlos syndrome (EDS). In the invertebrates Drosophila melanogaster and Caenorhabditis elegans, mutations in beta4GalT-7 affect biosynthesis of heparan sulfate (HS), a modulator of several biological processes relevant to wound repair. We have analyzed structural alterations of HS and their functional consequences in human beta4GalT-7 Arg270Cys mutant EDS and control fibroblasts. HS disaccharide analysis by reversed phase ion-pairing chromatography revealed a reduced sulfation degree of HS paralleled by altered immunostaining patterns for the phage-display anti-HS antibodies HS4E4 and RB4EA12 in beta4GalT-7 mutant fibroblasts. Real-time PCR-analysis of 44 genes involved in glycosaminoglycan biosynthesis indicated that the structural alterations in HS were not caused by differential regulation at the transcriptional level. Scratch wound closure was delayed in beta4GalT-7-deficient cells, which could be mimicked by enzymatic removal of HS in control cells. siRNA-mediated knockdown of beta4GalT-7 expression induced morphological changes in control fibroblasts which suggested altered cell-matrix interactions. Adhesion of beta4GalT-7 deficient cells to fibronectin was increased while actin stress fiber formation was impaired relative to control cells. Also collagen gel contraction was delayed in the beta4GalT-7 mutants which showed a reduced formation of pseudopodia and filopodia, less efficient penetration of the collagen gels and a diminished formation of collagen suprastructures. Our study suggests an HS-dependent basic mechanism behind the altered wound repair phenotype of beta4GalT-7-deficient EDS patients.

Transgenic or tumor-induced expression of heparanase upregulates sulfation of heparan sulfate

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 beta-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.