Low and high affinity receptors mediate cellular uptake of heparanase

Chemical toolbox to interrogate Heparanase-1 activity

The development of a robust chemical toolbox to interrogate the activity of heparanase-1 (HPSE-1), an endo-β-d-glucuronidase and the only known enzyme that cleaves heparan sulfate (HS), has become critically important. The primary function of HPSE-1, cleaving HS side chains from heparan sulfate proteoglycans (HSPGs), regulates the integrity of the extracellular matrix (ECM) and the bioavailability of active, heparan sulfate-binding partners such as enzymes, growth factors, chemokines, and cytokines. HPSE-1 enzymatic activity is strictly regulated and has been found to play fundamental roles in pathophysiological processes. HPSE-1 is significantly overexpressed under various conditions including cancer, metastasis, angiogenesis, and inflammation, making HPSE-1 a promising therapeutic and diagnostic target. Chemical tools that can detect and image HPSE-1 activity in vitro and/or in vivo can help drive the discovery of novel and efficacious anti-HPSE-1 drugs, investigate the basic biology of HPSE-1, and help serve as a diagnostic tool in clinical applications. Here, we will give an overview of the common chemical tools to detect HPSE-1 activity and highlight the novel heparanase probes recently developed in our lab.

A Fluorogenic Green Merocyanine-Based Probe to Detect Heparanase-1 Activity

Heparanase-1 (HPSE-1), an endo-β-D-glucuronidase, is an extracellular matrix (ECM) remodeling enzyme that degrades heparan sulfate (HS) chains of heparan sulfate proteoglycans (HSPGs). HPSE-1 functions to remodel the ECM and thereby disseminate cells, liberate HS-bound bioactive molecules, and release biologically active HS fragments. Being the only known enzyme for the cleavage of HS, HPSE-1 regulates a number of fundamental cellular processes including cell migration, cytokine regulation, angiogenesis, and wound healing. Overexpression of HPSE-1 has been discovered in most cancers, inflammatory diseases, viral infections, among others. As an emerging therapeutic target, the biological role of HPSE-1 remains to be explored but is hampered by a lack of research tools. To expand the chemical tool-kit of fluorogenic probes to interrogate HPSE-1 activity, we design and synthesized a fluorogenic green disaccharide-based HPSE-1 probe using our design strategy of tuning the electronic effect of the aryl aglycon. The novel probe exhibits a highly sensitive 278-fold fluorescence turn-on response in the presence of recombinant human HPSE-1, while emitting green light at 560 nm, enabling the fluorescence imaging of HPSE-1 activity in cells.

Heparanase as active player in endothelial glycocalyx remodeling

The surface of all animal cells is coated with a layer of carbohydrates linked in various ways to the outer side of the plasma membrane. These carbohydrates are mainly bound to proteins in the form of glycoproteins and proteoglycans and together with the glycolipids constitute the so-called glycocalyx. In particular, the endothelial glycocalyx that covers the luminal layer of the endothelium is composed of glycosaminoglycans (heparan sulphate -HS and hyaluronic acid -HA), proteoglycans (syndecans and glypicans) and adsorbed plasma proteins. Thanks to its ability to absorb water, this structure contributes to making the surface of the vessels slippery but at the same time acts by modulating the mechano-transduction of the vessels, the vascular permeability and the adhesion of leukocytes in thus regulating several physiological and pathological events. Among the various enzymes involved in the degradation of the glycocalyx, heparanase (HPSE) has been shown to be particularly involved. This enzyme is responsible for the cutting of heparan sulfate (HS) chains at the level of the proteoglycans of the endothelial glycocalyx whose dysfunction appears to have a role in organ fibrosis, sepsis and viral infection. In this mini-review, we describe the mechanisms by which HPSE contributes to glycocalyx remodeling and then examine the role of glycocalyx degradation in the development of pathological conditions and pharmacological strategies to preserve glycocalyx during disease pathogenesis.

A guide to the composition and functions of the extracellular matrix

Extracellular matrix (ECM) is a dynamic 3-dimensional network of macromolecules that provides structural support for the cells and tissues. Accumulated knowledge clearly demonstrated over the last decade that ECM plays key regulatory roles since it orchestrates cell signaling, functions, properties and morphology. Extracellularly secreted as well as cell-bound factors are among the major members of the ECM family. Proteins/glycoproteins, such as collagens, elastin, laminins and tenascins, proteoglycans and glycosaminoglycans, hyaluronan, and their cell receptors such as CD44 and integrins, responsible for cell adhesion, comprise a well-organized functional network with significant roles in health and disease. On the other hand, enzymes such as matrix metalloproteinases and specific glycosidases including heparanase and hyaluronidases contribute to matrix remodeling and affect human health. Several cell processes and functions, among them cell proliferation and survival, migration, differentiation, autophagy, angiogenesis, and immunity regulation are affected by certain matrix components. Structural alterations have been also well associated with disease progression. This guide on the composition and functions of the ECM gives a broad overview of the matrisome, the major ECM macromolecules, and their interaction networks within the ECM and with the cell surface, summarizes their main structural features and their roles in tissue organization and cell functions, and emphasizes the importance of specific ECM constituents in disease development and progression as well as the advances in molecular targeting of ECM to design new therapeutic strategies.

Biology of the Heparanase-Heparan Sulfate Axis and Its Role in Disease Pathogenesis

Cell surface proteoglycans are important constituents of the glycocalyx and participate in cell-cell and cell-extracellular matrix (ECM) interactions, enzyme activation and inhibition, and multiple signaling routes, thereby regulating cell proliferation, survival, adhesion, migration, and differentiation. Heparanase, the sole mammalian heparan sulfate degrading endoglycosidase, acts as an "activator" of HS proteoglycans, thus regulating tissue hemostasis. Heparanase is a multifaceted enzyme that together with heparan sulfate, primarily syndecan-1, drives signal transduction, immune cell activation, exosome formation, autophagy, and gene transcription via enzymatic and nonenzymatic activities. An important feature is the ability of heparanase to stimulate syndecan-1 shedding, thereby impacting cell behavior both locally and distally from its cell of origin. Heparanase releases a myriad of HS-bound growth factors, cytokines, and chemokines that are sequestered by heparan sulfate in the glycocalyx and ECM. Collectively, the heparan sulfate-heparanase axis plays pivotal roles in creating a permissive environment for cell proliferation, differentiation, and function, often resulting in the pathogenesis of diseases such as cancer, inflammation, endotheliitis, kidney dysfunction, tissue fibrosis, and viral infection.

Role of heparanase in tumor progression: Molecular aspects and therapeutic options

Heparanase (HPSE) is an endoglycosidase that catalyses the cutting of the side chains of heparan-sulphate proteoglycans (HS), thus determining the remodelling of the extracellular matrix and basement membranes, as well as promoting the release of different HS-related molecules as growth factors, cytokines and enzymes. Ever since the HPSE was identified in the late 1980s, several experimental studies have shown that its overexpression was instrumental in increasing tumor growth, metastatic dissemination, angiogenesis and inflammation. More recently, HPSE involvment has also been demonstrated in mediating tumor-host crosstalk, in inducing gene transcription, in the activation of signaling pathways and in the formation of exosomes and in autophagy. All of these activities (enzymatic and non-enzymatic) together make heparanase a multifunctional molecule that increases the aggressiveness and chemo-resistance of tumor cells. Conversely, heparanase gene-silencing or tumor treatment with compounds that inhibit heparanase activity have been shown to significantly attenuate tumor progression in different animal models of tumorigenesis, further emphasizing the therapeutic potential of anti-heparanase therapy for several types of neoplasms. This review focuses on present knowledge and recent development in the study of heparanase in cancer progression as well as on novel mechanisms by which heparanase regulates tumor metastasis and chemo-resistance. Moreover, recent advances in strategies for its inhibition as a potential therapeutic option will be discussed.

Helicobacter pylori infection enhances heparanase leading to cell proliferation via mitogen‑activated protein kinase signalling in human gastric cancer cells

Helicobacter pylori (H. pylori) infection is the most important factor in the development of gastric cancer. Heparanase (HPA) is involved in tissue remodelling and cell migration, which leads to inflammation and tumour metastasis. The current study aimed was to explore whether a H. pylori infection leads to an increase in the level of HPA in gastric cancer and to investigate the specific mechanism underlying this association. Reverse transcription‑polymerase chain reaction and western blotting were used to detect HPA mRNA and protein expression, respectively, in MKN‑45 cells infected by H. pylori, MKN‑45 cells treated with the mitogen‑activated protein kinase (MAPK) inhibitor SB203580 and MKN‑45 cells transfected with small interfering RNA against HPA. MAPK and nuclear factor (NF)‑κB expression were determined by western blotting in the different cells group. Cell Counting Kit‑8, Transwell method, and Scratch and Clone tests were conducted to detect proliferation, invasion, migration and clone formation ability of gastric cancer cells. It was demonstrated that HPA mRNA expression was highest at 6 h post‑infection, while the expression of the HPA protein was highest at 24 h post‑infection in H. pylori‑infected gastric cancer cells. Furthermore, it was demonstrated that H. pylori infection significantly enhanced the expression of MAPK and NF‑κB in MKN‑45 cells at the mRNA and protein levels. SB203580 significantly decreased the expression of NF‑κB in MKN‑45 cells infected with H. pylori. Exposure to SB203580 also significantly decreased the expression of HPA. In the present study, the inhibition of HPA significantly lowered H. pylori‑induced cell proliferation, suggesting that H. pylori infection induces the proliferation of gastric cancer cells through the upregulation of HPA. Taken together, the results of the present study demonstrated that HPA serves a critical role in the development of gastric cancer in H. pylori‑infected cells, which may be an important mechanism through which H. pylori infection leads to gastric cancer. In addition, H. pylori infection promotes the proliferation, invasion and metastasis of gastric cancer cells through the upregulation of HPA expression, and this is likely mediated via the MAPK and NF‑κB signalling pathways. These data suggest that HPA can be used as a therapeutic target in gastric cancer, particularly in cases induced by H. pylori infection.

High glucose facilitated endothelial heparanase transfer to the cardiomyocyte modifies its cell death signature

AIMS

The secretion of enzymatically active heparanase (Hep^A) has been implicated as an essential metabolic adaptation in the heart following diabetes. However, the regulation and function of the enzymatically inactive heparanase (Hep^L) remain poorly understood. We hypothesized that in response to high glucose (HG) and secretion of Hep^L from the endothelial cell (EC), Hep^L uptake and function can protect the cardiomyocyte by modifying its cell death signature.

METHODS AND RESULTS

HG promoted both Hep^L and Hep^A secretion from microvascular (rat heart micro vessel endothelial cells, RHMEC) and macrovascular (rat aortic endothelial cells, RAOEC) EC. However, only RAOEC were capable of Hep^L reuptake. This occurred through a low-density lipoprotein receptor-related protein 1 (LRP1) dependent mechanism, as LRP1 inhibition using small interfering RNA (siRNA), receptor-associated protein, or an LRP1 neutralizing antibody significantly reduced uptake. In cardiomyocytes, which have a negligible amount of heparanase gene expression, LRP1 also participated in the uptake of Hep^L. Exogenous addition of Hep^L to rat cardiomyocytes produced a dramatically altered expression of apoptosis-related genes, and protection against HG and H₂O₂ induced cell death. Cardiomyocytes from acutely diabetic rats demonstrated a robust increase in LRP1 expression and levels of heparanase, a pro-survival gene signature, and limited evidence of cell death, observations that were not apparent following chronic and progressive diabetes.

CONCLUSION

Our results highlight EC-to-cardiomyocyte transfer of heparanase to modulate the cardiomyocyte cell death signature. This mechanism was observed in the acutely diabetic heart, and its interruption following chronic diabetes may contribute towards the development of diabetic cardiomyopathy.

Heparanase: From basic research to therapeutic applications in cancer and inflammation

Heparanase, the sole heparan sulfate degrading endoglycosidase, regulates multiple biological activities that enhance tumor growth, angiogenesis and metastasis. Heparanase expression is enhanced in almost all cancers examined including various carcinomas, sarcomas and hematological malignancies. Numerous clinical association studies have consistently demonstrated that upregulation of heparanase expression correlates with increased tumor size, tumor angiogenesis, enhanced metastasis and poor prognosis. In contrast, knockdown of heparanase or treatments of tumor-bearing mice with heparanase-inhibiting compounds, markedly attenuate tumor progression further underscoring the potential of anti-heparanase therapy for multiple types of cancer. Heparanase neutralizing monoclonal antibodies block myeloma and lymphoma tumor growth and dissemination; this is attributable to a combined effect on the tumor cells and/or cells of the tumor microenvironment. In fact, much of the impact of heparanase on tumor progression is related to its function in mediating tumor-host crosstalk, priming the tumor microenvironment to better support tumor growth, metastasis and chemoresistance. The repertoire of the physio-pathological activities of heparanase is expanding. Specifically, heparanase regulates gene expression, activates cells of the innate immune system, promotes the formation of exosomes and autophagosomes, and stimulates signal transduction pathways via enzymatic and non-enzymatic activities. These effects dynamically impact multiple regulatory pathways that together drive inflammatory responses, tumor survival, growth, dissemination and drug resistance; but in the same time, may fulfill some normal functions associated, for example, with vesicular traffic, lysosomal-based secretion, stress response, and heparan sulfate turnover. Heparanase is upregulated in response to chemotherapy in cancer patients and the surviving cells acquire chemoresistance, attributed, at least in part, to autophagy. Consequently, heparanase inhibitors used in tandem with chemotherapeutic drugs overcome initial chemoresistance, providing a strong rationale for applying anti-heparanase therapy in combination with conventional anti-cancer drugs. Heparin-like compounds that inhibit heparanase activity are being evaluated in clinical trials for various types of cancer. Heparanase neutralizing monoclonal antibodies are being evaluated in pre-clinical studies, and heparanase-inhibiting small molecules are being developed based on the recently resolved crystal structure of the heparanase protein. Collectively, the emerging premise is that heparanase expressed by tumor cells, innate immune cells, activated endothelial cells as well as other cells of the tumor microenvironment is a master regulator of the aggressive phenotype of cancer, an important contributor to the poor outcome of cancer patients and a prime target for therapy.

Heparanase augments inflammatory chemokine production from colorectal carcinoma cell lines

To explore possible roles of heparanase in cancer-host crosstalk, we examined whether heparanase influences expression of inflammatory chemokines in colorectal cancer cells. Murine colorectal carcinoma cells incubated with heparanase upregulated MCP-1, KC, and RANTES genes and released MCP-1 and KC proteins. Heparanase-dependent production of IL-8 was detected in two human colorectal carcinoma cell lines. Addition of a heparanase inhibitor Heparastatin (SF4) did not influence MCP-1 production, while both latent and mature forms of heparanase augmented MCP-1 release, suggesting that heparanase catalytic activity was dispensable for MCP-1 production. In contrast, addition of heparin to the medium suppressed MCP-1 release in a dose-dependent manner. Similarly, targeted suppression of Ext1 by RNAi significantly suppressed cell surface expression of heparan sulfate and MCP-1 production in colon 26 cells. Taken together, it is concluded that colon 26 cells transduce the heparanase-mediated signal through heparan sulfate binding. We propose a novel function for heparanase independent of its endoglycosidase activity, namely as a stimulant for chemokine production.

Heparanase interacts with resistin and augments its activity

In an attempt to isolate a heparanase receptor, postulated to mediate non-enzymatic functions of the heparanase protein, we utilized human urine collected from healthy volunteers. Affinity chromatography of this rich protein source on immobilized heparanase revealed resistin as a heparanase binding protein. Co-immunoprecipitation and ELISA further confirmed the interaction between heparanase and resistin. Importantly, we found that heparanase potentiates the bioactivity of resistin in its standard bioassay in which monocytic human leukemia cell line, THP1, differentiates into adherent macrophage-like foam cells. It is thus conceivable that this newly identified complex of heparanase and resistin exerts a stimulatory effect also in various inflammatory conditions known to be affected by the two proteins.

The heparanase system and tumor metastasis: is heparanase the seed and soil?

Tumor metastasis, the leading cause of cancer patients' death, is still insufficiently understood. While concepts and mechanisms of tumor metastasis are evolving, it is widely accepted that cancer metastasis is accompanied by orchestrated proteolytic activity executed by array of proteases. While matrix metalloproteinases (MMPs) attracted much attention, other proteases constitute the tumor milieu, of which a large family consists of cysteine proteases named cathepsins. Like MMPs, some cathepsins are often upregulated in cancer and, once secreted or localized to the cell surface, can degrade components of the extracellular matrix. In addition, cathepsin L is held responsible for processing and activation of heparanase, an endo-β-glucuronidase capable of cleaving heparan sulfate side chains of heparan sulfate proteoglycans, activity that is strongly implicated in cell dissemination associated with tumor metastasis, angiogenesis, and inflammation. In this review, we discuss recent progress in heparanase research focusing on heparanase-related molecules namely, cathepsin L and heparanase 2 (Hpa2), a heparanase homolog.

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.

Glycan and lectin microarrays for glycomics and medicinal applications

Three different array formats to study a challenging field of glycomics are presented here, based on the use of a panel of immobilized glycan or lectins, and on in silico computational approach. Glycan and lectin arrays are routinely used in combination with other analytical tools to decipher a complex nature of glycan-mediated recognition responsible for signal transduction of a broad range of biological processes. Fundamental aspects of the glycan and lectin array technology are discussed, with the focus on the choice and availability of the biorecognition elements, fabrication protocols, and detection platforms involved. Moreover, practical applications of both technologies especially in the field of clinical diagnostics are provided. The future potential of a complementary in silico array technology to reveal details of the protein-glycan-binding profiles is discussed here.

Heparanase upregulates Th2 cytokines, ameliorating experimental autoimmune encephalitis

Heparanase is an endo-beta-d-glucuronidase that cleaves heparan sulfate (HS) saccharide chains. The enzyme promotes cell adhesion, migration and invasion and plays a significant role in cancer metastasis, angiogenesis and inflammation. The present study focuses on the involvement of heparanase in autoimmunity, applying the murine experimental autoimmune encephalitis (EAE) model, a T-cell dependent disease often used to investigate the pathophysiology of multiple sclerosis (MS). Intraperitoneal administration of recombinant heparanase ameliorated, in a dose dependent manner, the clinical signs of the disease. In vitro and in vivo studies revealed that heparanase inhibited mitogen induced splenocyte proliferation and mixed lymphocyte reaction (MLR) through modulation of their repertoire of cytokines indicated by a marked increase in the levels of IL-4, IL-6 and IL-10, and a parallel decrease in IL-12 and TNF-alpha. Similar results were obtained with active, latent, or point mutated inactive heparanase, indicating that the observed inhibitory effect is attributed to a non-enzymatic activity of the heparanase protein. We suggest that heparanase induces upregulation of Th2 cytokines, resulting in inhibition of the inflammatory lesion of EAE.

Heparanase promotes engraftment and prevents graft versus host disease in stem cell transplantation

Background

Heparanase, endoglycosidase that cleaves heparan sulfate side chains of heparan sulfate proteoglycans, plays important roles in cancer metastasis, angiogenesis and inflammation.

Design and Methods

Applying a mouse model of bone marrow transplantation and transgenic mice over-expressing heparanase, we evaluated the effect of heparanase on the engraftment process and the development of graft-versus-host disease.

Results

Analysis of F1 mice undergoing allogeneic bone marrow transplantation from C57BL/6 mice demonstrated a better and faster engraftment in mice receiving cells from donors that were pretreated with heparanase. Moreover, heparanase treated recipient F1 mice showed only a mild appearance of graft-versus-host disease and died 27 days post transplantation while control mice rapidly developed signs of graft-versus-host disease (i.e., weight loss, hair loss, diarrhea) and died after 12 days, indicating a protective effect of heparanase against graft-versus-host disease. Similarly, we applied transgenic mice over-expressing heparanase in most tissues as the recipients of BMT from C57BL/6 mice. Monitoring clinical parameters of graft-versus-host disease, the transgenic mice showed 100% survival on day 40 post transplantation, compared to only 50% survival on day 14, in the control group. In vitro and in vivo studies revealed that heparanase inhibited T cell function and activation through modulation of their cytokine repertoire, indicated by a marked increase in the levels of Interleukin-4, Interleukin-6 and Interleukin-10, and a parallel decrease in Interleukin-12, tumor necrosis factor-alfa and interferon-gamma. Using point mutated inactive enzyme, we found that the shift in cytokine profile was independent of heparanase enzymatic activity.

Conclusions

Our results indicate a significant role of heparanase in bone marrow transplantation biology, facilitating engraftment and suppressing graft-versus-host disease, apparently through an effect on T cell activation and cytokine production pattern.

A novel human heparanase splice variant, T5, endowed with protumorigenic characteristics

Heparanase is a mammalian endo-beta-d-glucuronidase that can cleave heparan sulfate side chains, an activity strongly implicated in tumor cell dissemination. The current study aimed to identify and characterize heparanase splice variants. LEADS, Compugen's alternative splicing modeling platform (Compugen, Tel Aviv, Israel), was used to search for splice variants in silico; tumor-derived cell lines (i.e., CAG myeloma) and tumor biopsies were utilized to validate T5 expression in vivo; signaling (i.e., Src phosphorylation) was evaluated following T5 gene silencing or overexpression and correlated with cell proliferation, colony formation, and tumor xenograft development. A novel spliced form of human heparanase, termed T5, was identified. In this splice variant, 144 bp of intron 5 are joined with exon 4, which results in a truncated, enzymatically inactive protein. T5 overexpression resulted in increased cell proliferation and larger colonies in soft agar, mediated by Src activation. Furthermore, T5 overexpression markedly enhanced tumor xenograft development. T5 expression is up-regulated in 75% of human renal cell carcinoma biopsies examined, which suggests that this splice variant is clinically relevant. Controls included cells overexpressing wild-type heparanase or an empty plasmid and normal-looking tissue adjacent the carcinoma lesion. T5 is a novel functional splice variant of human heparanase endowed with protumorigenic characteristics.-Barash, U., Cohen-Kaplan, V., Arvatz, G., Gingis-Velitski, S., Levy-Adam, F., Nativ, O., Shemesh, R., Ayalon-Sofer, M., Ilan, N., Vlodavsky, I. A novel human heparanase splice variant, T5, endowed with protumorigenic characteristics.

Heparanase: busy at the cell surface

Heparanase activity is strongly implicated in structural remodeling of the extracellular matrix, a process which can lead to invasion by tumor cells. In addition, heparanase augments signaling cascades leading to enhanced phosphorylation of selected protein kinases and increased gene transcription associated with aggressive tumor progression. This function is apparently independent of heparan sulfate and enzyme activity, and is mediated by a novel protein domain localized at the heparanase C-terminus. Moreover, the functional repertoire of heparanase is expanded by its regulation of syndecan clustering, shedding, and mitogen binding. Recent reports indicate that modified glycol-split heparin, which inhibits heparanase activity, can profoundly inhibit the progression of tumor xenografts produced by myeloma and carcinoma cells, thus moving anti-heparanase therapy closer to reality.

Structure-function approach identifies a COOH-terminal domain that mediates heparanase signaling

Heparanase is an endo-beta-d-glucuronidase capable of cleaving heparan sulfate, activity that is strongly implicated in cellular invasion associated with tumor metastasis, angiogenesis, and inflammation. In addition, heparanase was noted to exert biological functions apparently independent of its enzymatic activity, enhancing the phosphorylation of selected protein kinases and inducing gene transcription. A predicted three-dimensional structure of constitutively active heparanase clearly delineates a TIM-barrel fold previously anticipated for the enzyme. Interestingly, the model also revealed the existence of a COOH-terminal domain (C-domain) that apparently is not an integral part of the TIM-barrel fold. We provide evidence that the C-domain is critical for heparanase enzymatic activity and secretion. Moreover, the C-domain was found to mediate nonenzymatic functions of heparanase, facilitating Akt phosphorylation, cell proliferation, and tumor xenograft progression. These findings support the notion that heparanase exerts enzymatic activity-independent functions, and identify, for the first time, a protein domain responsible for heparanase-mediated signaling. Inhibitors directed against the C-domain, combined with inhibitors of heparanase enzymatic activity, are expected to neutralize heparanase functions and to profoundly affect tumor growth, angiogenesis, and metastasis.

Clinical significance of urine heparanase in bladder cancer progression

Heparanase is an endo-beta-glucuronidase capable of cleaving heparan sulfate (HS), an activity implicated in tumor metastasis. Heparanase expression is upregulated in primary human tumors, correlating with reduced post operative survival and elevated microvessel density. An ELISA method was used to quantify heparanase in urine from 282 individuals. Urine was collected from healthy volunteers (n = 41), patients diagnosed with noncancerous pathologic disorders (n = 90), and bladder cancer patients (n = 92). Fifty-nine bladder carcinoma patients after transurethral resection (TUR) with no evidence of disease (NED) were also included. Heparanase levels were significantly elevated in urine from bladder cancer patients compared with healthy controls (P < .001) and with noncancerous urinary disorders (P < .05). Heparanase elevation strongly correlated with tumor grade (P < .001) and stage (P = .027). An optimal cutoff value of 154 pg/ml was determined. Of 199 individuals enrolled (59 patients after TUR and 24 patients with recurring disease were excluded), 65 had heparanase levels above 154 pg/ml. Only 3 of 65 (4.6%) were healthy individuals. In contrast, 52.3% (34 of 65) of individuals with heparanase levels above 154 pg/ml were bladder cancer patients. The results indicate that urine heparanase levels are elevated during bladder cancer progression, suggesting that the ELISA method may be applied for bladder cancer diagnosis.