Heparanase-1 expression is associated with the metastatic potential of breast cancer

Proteoglycans in health and disease: new concepts for heparanase function in tumor progression and metastasis

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.

Heparanase procoagulant effects and inhibition by heparins

Heparanase is an endo-beta-D-glucuronidase capable of cleaving heparan sulfate (HS) side chains of heparan sulfate proteoglycans (HSPG) on cell surfaces and the extracellular matrix, activity that is strongly implicated in tumor metastasis and angiogenesis. Evidence was provided that heparanase over-expression in cancer cells results in a marked increase in tissue factor (TF) levels. Likewise, TF was induced by exogenous addition of recombinant heparanase to tumor cells and primary endothelial cells, induction that was mediated by p38 phosphorylation and correlated with enhanced procoagulant activity. TF induction was further confirmed in heparanase over-expressing transgenic mice and correlated with heparanase expression levels in leukemia patients. Heparanase was also found to be involved in the regulation of tissue factor pathway inhibitor (TFPI). A physical interaction between heparanase and TFPI was demonstrated, suggesting a mechanism by which secreted heparanase interacts with TFPI on the cell surface, leading to dissociation of TFPI from the cell membrane and increased coagulation activity, thus further supporting the local pro-thrombotic function of heparanase. Data indicate a possible involvement of heparanase in early miscarriages and point to a regulatory effect on TFPI and TFPI-2 in trophoblasts. As heparins are strong inhibitor of heparanase, in view of the effect of heparanase on TF, the role of heparins anticoagulant-activity may potentially be expanded. Taking into account the pro-metastatic and pro-angiogenic functions of heparanase, its over-expression in human malignancies and abundance in platelets, its involvement in the coagulation machinery is an intriguing novel arena for further research.

Tumorigenic and adhesive properties of heparanase

Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains presumably at sites of low sulfation, activity that is strongly implicated with cell invasion associated with cancer metastasis, a consequence of structural modification that loosens the extracellular matrix barrier. In addition, heparanase exerts pro-adhesive properties, mediated by clustering of membrane heparan sulfate proteoglycans (i.e., syndecans) and activation of signaling molecules such as Akt, Src, EGFR, and Rac in a heparan sulfate-dependent and -independent manner. Activation of signaling cascades by enzymatically inactive heparanase and by a peptide corresponding to its substrate binding domain not only increases cell adhesion but also facilitates cancer cell growth. This notion is supported by preclinical and clinical settings, encouraging the development of anti-heparanase therapeutics. Here, we summarize recent progress in heparanase research emphasizing the molecular mechanisms that govern its pro-tumorigenic and pro-adhesive properties. Pro-adhesive properties of the heparanase homolog, heparanase 2 (Hpa2), are also discussed. Enzymatic activity-independent function of proteases (i.e., matrix metalloproteinases) is discussed in the context of cell adhesion and tumor progression. Collectively, these examples suggest that enzyme function exceeds beyond the enzymatic aspect, thus significantly expanding the scope of the functional proteome. Cross-talk with matrix metalloproteinases and the role of heparanase in pathological settings other than cancer are also described.

Effects of distant metastasis and peripheral CA 15-3 on the induction of spontaneous T cell responses in breast cancer patients

Tumor-specific memory T cells are detectable in the bone marrow (BM) of a majority of breast cancer patients. In vitro they can be reactivated to IFN-gamma producing, cytotoxic effector cells and reject autologous, xenotransplanted tumors in NOD/SCID mice after specific restimulation with autologous dendritic cells (DC). In this study, we demonstrate the presence of specific tumor-reactive BM memory T cells in altogether 56 out of 129 primarily operated breast cancer patients by short-term IFN-gamma EliSpot assays with unstimulated T cells and tumor antigen presenting, autologous DCs. We observed tumor-reactive BM memory T cells predominantly in patients with primarily metastatic disease (P = 0.011) or with increased concentrations of tumor marker CA 15-3 in the peripheral blood (P = 0.004), respectively. Memory T cell reactivity against HLA-A(*0201)-restricted peptides from the tumor-associated antigens MUC1, Hpa(16-24) and Hpa(183-191) was also detected particularly in patients with elevated peripheral CA 15-3 concentrations (P < 0.05). Altogether these data indicate that the systemic presence of tumor-derived antigens promotes an induction of tumor-specific cellular immune responses in the human BM.

Advances in Immunotherapy of Multiple Myeloma: From the Discovery of Tumor-Associated Antigens to Clinical Trials

Tumors aberrantly express tumor-associated antigens that can be specifically recognized by T-cells, thereby providing a scientific rationale for the design and clinical testing of immunotherapeutic strategies targeting these antigens. Multiple myeloma is a fatal hematologic malignancy. Here, we review techniques to discover new tumor-associated antigens in multiple myeloma and the latest immunotherapeutic strategies employed in this disease.

Heparanase coagulation and cancer progression

Heparanase is an endo-beta-D-glucuronidase capable of cleaving heparan sulphate (HS) side chains of heparan sulphate proteoglycans on cell surfaces and the extracellular matrix; activity that is strongly implicated in tumour metastasis and angiogenesis. It has been shown that heparanase overexpression in human leukaemia, glioma and breast carcinoma cells results in a marked increase in tissue factor (TF) levels. In addition, TF was induced by exogenous addition of recombinant heparanase to tumour cells and primary endothelial cells; induction that was mediated by p38 phosphorylation and correlated with enhanced procoagulant activity. TF induction was further confirmed in transgenic mice overexpressing heparanase, and correlated with heparanase expression levels in leukaemia patients. Heparanase was also found to be involved in the regulation of tissue factor pathway inhibitor (TFPI). It has been shown that heparanase overexpression or exogenous addition induces a two- to three-fold increase in TFPI expression. Similarly, heparanase stimulated accumulation of TFPI in the cell culture medium. However, extracellular accumulation exceeded the observed increase in TFPI at the protein level, and appeared to be independent of HS and heparanase enzymatic activity. Instead, a physical interaction between heparanase and TFPI was demonstrated, suggesting a mechanism by which secreted heparanase interacts with TFPI on the cell surface, leading to dissociation of TFPI from the cell membrane and increased coagulation activity, thus further supporting the local prothrombotic function of heparanase. As heparins are strong inhibitors of heparanase, in view of the effect of heparanase on the TF/TFPI pathway, the role of anticoagulant activity of heparin may potentially be expanded. Taking into account the prometastatic and pro-angiogenic functions of heparanase, its overexpression in human malignancies and abundance in platelets, its involvement in the coagulation machinery is an intriguing novel arena for further research.

Cell surface heparan sulfate released by heparanase promotes melanoma cell migration and angiogenesis

Heparan sulfate (HS) proteoglycans are essential components of the cell-surface and extracellular matrix (ECM) which provide structural integrity and act as storage depots for growth factors and chemokines, through their HS side chains. Heparanase (HPSE) is the only mammalian endoglycosidase known that cleaves HS, thus contributing to matrix degradation and cell invasion. The enzyme acts as an endo-beta-D-glucuronidase resulting in HS fragments of discrete molecular weight size. Cell-surface HS is known to inhibit or stimulate tumorigenesis depending upon size and composition. We hypothesized that HPSE contributes to melanoma metastasis by generating bioactive HS from the cell-surface to facilitate biological activities of tumor cells as well as tumor microenvironment. We removed cell-surface HS from melanoma (B16B15b) by HPSE treatment and resulting fragments were isolated. Purified cell-surface HS stimulated in vitro B16B15b cell migration but not proliferation, and importantly, enhanced in vivo angiogenesis. Furthermore, melanoma cell-surface HS did not affect in vitro endothelioma cell (b.End3) migration. Our results provide direct evidence that, in addition to remodeling ECM and releasing growth factors and chemokines, HPSE contributes to aggressive phenotype of melanoma by releasing bioactive cell-surface HS fragments which can stimulate melanoma cell migration in vitro and angiogenesis in vivo.

Removal of cell surface heparan sulfate increases TACE activity and cleavage of ErbB4 receptor

Background

Nuclear localization of proteolytically formed intracellular fragment of ErbB4 receptor tyrosine kinase has been shown to promote cell survival, and nuclear localization of ErbB4 receptor has been described in human breast cancer. Tumor necrosis factor alpha converting enzyme (TACE) initiates the proteolytic cascade leading to ErbB4 intracellular domain formation. Interactions between matrix metalloproteases and heparan sulfate have been described, but the effect of cell surface heparan sulfate on TACE activity has not been previously described.

Results

As indicated by immunodetection of increased ErbB4 intracellular domain formation and direct enzyme activity analysis, TACE activity was substantially amplified by enzymatic removal of cell surface heparan sulfate but not chondroitin sulfate.

Conclusion

In this communication, we suggest a novel role for cell surface heparan sulfate. Removal of cell surface heparan sulfate led to increased formation of ErbB4 intracellular domain. As ErbB4 intracellular domain has previously been shown to promote cell survival this finding may indicate a novel mechanism how HS degradation active in tumor tissue may favor cell survival.

Heparanase-2, syndecan-1, and extracellular matrix remodeling in colorectal carcinoma

AIM

To propose a quantitative method to detect heparanase-2 (HPA2) and syndecan-1 (Syn-1) using immunohistochemistry in colorectal (colon and rectal) carcinomas compared with nonneoplastic tissues and evaluate the possible role of these molecules in tumor development and extracellular remodeling.

METHODS

Cytoplasmic staining of HPA2 and Syn-1 was obtained by standard immunohistochemical reactions in 50 colorectal carcinoma and 20 nonneoplastic large bowels tissues. An image system was used to quantify the immunoexpression by digital computer-assisted method (Matos et al. 2006). The cutoff point for the immunohistochemistry variable was defined by sensibility and specificity curves. Statistical analysis was performed using SPSS version 13.0.

RESULTS

HPA2 was over-expressed in colorectal cancer (131.1+/-24.9 o.u./microm) when compared with nonneoplastic tissues (27.9+/-12.2 o.u./microm) (P<0.0001). However, an opposite correlation was observed between Syn-1 and tumor presence, where colorectal tissues expressed lower Syn-1 proteoglycan compared with nonneoplastic tissues, respectively (39.2+/-17.8 o.u./microm) and (102.2+/-25.2 o.u./microm) (P<0.0001).

CONCLUSION

A methodology with high sensitivity and specificity is proposed with a cutoff value for HPA2 and Syn-1 in the immunohistochemistry assay to define the presence of tumor. It was demonstrated for the first time in the literature that HPA2 is over-expressed in colorectal carcinoma tissues compared with nonneoplastic tissues. HPA2 over-expression could be possibly related to Syn-1 shedding despite the fact that HPA2 does not present enzymatic activity as HPA1.

The effects of low molecular weight heparins on venous thromboembolism and survival in patients with cancer

Monotherapy with low molecular weight heparin (LMWH) is superior to vitamin K antagonists in preventing recurrent venous thromboembolism (VTE) in patients with cancer and may improve the survival of patients with less advanced malignancies. These agents are also the preferred anticoagulants for primary prophylaxis in medical and surgical patients in hospital. Despite their limitations, LMWHs have improved the quality of care and quality of life in patients with VTE. Recent research has also explored the role of LMWH as anticancer agents. Evidence from experimental studies have demonstrated inhibitory effects of LMWH on various processes that are necessary for tumour growth and progression while results from clinical trials have shown a reduction in overall mortality in patients treated with LMWH. However, because of limitations and differences in study designs as well as small sample sizes, it remains uncertain whether the reduction in mortality is real and whether LMWH achieve this effect through inhibition of coagulation, non-anticoagulant mechanisms or both. Multiple anticancer mechanisms, including inhibition of tumour angiogenesis, interference with tumour cell adhesion, and suppression of tumour cell invasion, have been demonstrated in experimental models with LMWH, but none have been confirmed in vivo in humans. This review will briefly summarize the data on the treatment of VTE in cancer patients with LMWH and discuss the experimental and clinical data on its possible anticancer effects.

Heparanase up-regulation in tongue cancer: tissue and saliva analysis

BACKGROUND

Heparanase up-regulation has been correlated with reduced postoperative survival in various cancers.

METHODS

Heparanase expression was analyzed in 60 consenting tongue (mobile) cancer patients by means of immunohistochemistry. Heparanase levels were also analyzed in the saliva of both healthy controls and tongue cancer patients using a novel heparanase enzyme-linked immunosorbent assay method.

RESULTS

Heparanase staining was positive (>0) in 92% and negative (=0) in 8% of the tumors and staining intensity correlated with tumor size and tumor stage. Moreover, the survival probability of patients negative for heparanase (=0) at 60 months was 100%, compared with only 41% for patients positive for heparanase (>0), suggesting that heparanase may serve as a prognostic factor for this malignancy and an attractive target for anticancer drug development. Heparanase was detected in the saliva of healthy controls and the mean concentration was determined as 119 +/- 37 pg/mL. Importantly, a nearly 3-fold increase of heparanase levels was detected in saliva collected from tongue cancer patients (334 +/- 69 pg/mL), a difference that is statistically highly significant (P = .004).

CONCLUSIONS

These findings support heparanase up-regulation in tongue cancer and raise the possibility of using this simple test as a diagnostic tool to monitor tongue cancer progression and response to treatment.

Heparanase expression increases throughout the endometrial hyperplasia-cancer sequence

OBJECTIVE

To assess the expression of heparanase in the different stages leading to endometrial cancer.

METHODS

The 38 examined specimens included adenocarcinoma, hyperplasia, and normal endometrium specimens. Heparanase, estrogen, and progesterone receptor expressions were analyzed immunohistochemically and the intensity was scored.

RESULTS

Secretory normal endometrium and simple hyperplasia specimens expressed the lowest mean values of expression (1.00 and 0.63, respectively); the complex hyperplasia specimens and G2 endometrioid adenocarcinoma showed the highest values of expression (2.33 and 2.71, respectively). A linear trend (P=0.005) of heparanase expression was observed when comparing the normal endometrium and simple hyperplasia group with the complex hyperplasia+G1 carcinoma group and the G2+G3 carcinoma group. Evaluation of atrophic and inactive endometrium compared with papillary serous carcinomas yielded no significant differences. We found no significant correlation between heparanase expression and estrogen receptor or progesterone receptor expression.

CONCLUSION

Heparanase expression was tightly regulated in endometrial tumorigenesis.

Heparanase expression in B16 melanoma cells and peripheral blood neutrophils before and after extravasation detected by novel anti-mouse heparanase monoclonal antibodies

Degradation of extracellular matrix is associated with extravasation of metastatic tumor cells and inflammatory cells. Heparanase, the heparan sulfate-specific endo-beta-glucuronidase, is a key enzyme for the matrix degradation, yet its involvement in extravasation and invasion during pathological processes was not fully clarified in vivo. In the present study, we examined heparanase expression in mouse experimental models, lung metastasis of melanoma and skin infiltration of neutrophils. Sixteen novel monoclonal antibodies specific for mouse heparanase were established by enzyme-linked immunosorbent assay with a recombinant mouse proheparanase, immunocytochemical staining of B16F10 melanoma cells cultured in vitro, and immunoprecipitation of the lysate of heparanase transfectant cells. Heparanase expression in metastatic nodules of B16F10 melanoma cells and in neutrophils localized in the inflamed skin was immunohistochemically detected using a monoclonal antibody RIO-1 that recognized the C-terminus of mouse heparanase. Homogeneous and strong heparanase staining was observed in 46% of the lung micrometastases of B16F10 melanoma cells. The staining was intensely positive on the invasive front of larger established metastasis nodules, but it was weak or heterogeneous inside the nodules. Heparanase expression in skin-infiltrating neutrophils was examined after inducing local inflammation with croton oil. The monoclonal antibody stained a significant portion of neutrophils inside and along the blood vessels, whereas it did not stain dermal neutrophils located distant from the vasculatures. The present study strongly suggests that both melanoma cells and neutrophils transiently express heparanase before and during the invasive process in vivo.

Tamoxifen induces heparanase expression in estrogen receptor-positive breast cancer

PURPOSE

Mammalian heparanase degrades heparan sulfate, the main polysaccharide of the basement membrane. Heparanase is an important determinant in cancer progression, acting via the breakdown of extracellular barriers for invasion, as well as release of heparan sulfate-bound angiogenic and growth-promoting factors. The present study was undertaken to elucidate molecular mechanisms responsible for heparanase overexpression in breast cancer.

EXPERIMENTAL DESIGN

To characterize heparanase regulation by estrogen and tamoxifen and its clinical relevance for breast tumorigenesis, we applied immunohistochemical analysis of tissue microarray combined with chromatin immunoprecipitation assay, reverse transcription-PCR, and Western blot analysis.

RESULTS

A highly significant correlation (P<0.0001) between estrogen receptor (ER) positivity and heparanase overexpression was found in breast cancer. Binding of ER to heparanase promoter accompanied estrogen-induced increase in heparanase expression by breast carcinoma cells. Surprisingly, heparanase transcription was also stimulated by tamoxifen, conferring a proliferation advantage to breast carcinoma cells grown on a naturally produced extracellular matrix. Heparanase overexpression was invariably detected in ER-positive second primary breast tumors, developed in patients receiving tamoxifen for the initial breast carcinoma. The molecular mechanism of the estrogenlike effect of tamoxifen on heparanase expression involves recruitment of transcription coactivator AIB1 to the heparanase promoter.

CONCLUSIONS

Heparanase induction by ligand-bound ER represents an important pathway in breast tumorigenesis and may be responsible, at least in part, for the failure of tamoxifen therapy in some patients. Our study provides new insights on breast cancer progression and endocrine therapy resistance, offering future strategies for delaying or reversing this process.

Cancer and thrombosis: from molecular mechanisms to clinical presentations

Although the bidirectional association between cancer and venous thromboembolism (VTE) has been known for almost two centuries, recent advances in our understanding of the clinical, laboratory, and epidemiologic aspects of this association have created a renewed interest in this topic. This review consists of two parts. The first part discusses the occurrence, determinants and significance of VTE in those with cancer, as well as the risk of developing and the possible need to detect cancer in those presenting with VTE. The second part reviews the role of hemostatic constituents (coagulation and fibrinolytic proteins and platelets) in promoting growth and progression of cancer, as well as the effects and possible mechanisms of the low molecular weight heparins (LMWH) in this process.

Immunohistochemical detection of heparanase-1 expression in eutopic and ectopic endometrium from women with endometriosis

OBJECTIVE

To investigate the expression of heparanase-1, an endoglycosidase that degrades heparan sulfate proteoglycans, in eutopic and ectopic endometrial tissues from women with endometriosis.

DESIGN

An immunohistochemical study.

SETTING

Academic research laboratory and a private infertility clinic affiliated with a university medical center.

PATIENT(S)

Premenopausal women undergoing laparoscopy for endometriosis.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Expression of heparanase-1 analyzed by immunohistochemical staining in 91 eutopic and 14 ectopic endometrial specimens.

RESULT(S)

We found that 17% (4/24) of the eutopic endometrial specimens in the early proliferative phase and 32% (9/28) of the samples in the midproliferative phase were heparanase-1 positive. However, >or=80% of eutopic endometrial specimens at late proliferate phase and at luteal phase were heparanase-1 positive. Twelve of 14 ectopic endometriotic specimens stained heparanase-1 positive. Comparison of heparanase-1 expression in paired eutopic and ectopic endometrial tissues revealed that 5 of 6 ectopic specimens in the early proliferative phase were heparanase-1 positive, whereas only 1 eutopic specimen was heparanase-1 positive. In comparison with our recent study of heparanase-1 expression in normal endometrium, we found that there was no significant difference in heparanase-1 expression in the eutopic endometrium from women with or without endometriosis.

CONCLUSION(S)

Heparanase-1 was differentially expressed in the eutopic endometrium in the different menstrual phases. Heparanase-1 was highly expressed in the ectopic endometriotic lesions regardless of their menstrual phases, suggesting that the local environment is responsible for increased heparanase-1 expression.

Translocation of heparanase into nucleus results in cell differentiation

We recently reported that heparanase, one of the extracellular matrix-degrading enzymes, which plays a critical role in cancer progression, is located not only in the cytoplasm but also in the nucleus. Here we identified nuclear translocation of heparanase as a key step in cell differentiation. We applied an in vitro differentiation model of HL-60 cells with 12-0-tetradecanoylphorbol-13-acetate (TPA), in which nuclear translocation of heparanase was observed using immunohistochemical analysis. In this system, nuclear translocation of heparanase was abolished by inhibitors of heat shock protein 90 (HSP90), suggesting the involvement of HSP90 in translocation of heparanase. We further confirmed that overexpression of active form of heparanase induced differentiation of HL-60 cells, although the catalytic negative form of heparanase did not. Therefore we speculate that nuclear translocation of enzymatically active heparanase may be involved in cellular differentiation. Our results suggest that a novel function of heparanase upon cell differentiation would raise a potential new strategy for cancer therapy of promyeloid leukemia and other types of cancer.

Heparanase: a target for drug discovery in cancer and inflammation

The remodelling of the extracellular matrix (ECM) has been shown to be highly upregulated in cancer and inflammation and is critically linked to the processes of invasion and metastasis. One of the key enzymes involved in specifically degrading the heparan sulphate (HS) component of the ECM is the endo-beta-glucuronidase enzyme heparanase. Processing of HS by heparanase releases both a host of bioactive growth factors anchored within the mesh of the ECM as well as defined fragments of HS capable of promoting cellular proliferation. The finding that heparanase is elevated in a wide variety of tumor types and is subsequently linked to the development of pathological processes has led to an explosion of therapeutic strategies to inhibit its enzyme activity. So far only one compound, the sulphated oligosaccharide PI88, which both inhibits heparanase activity and has effects on growth factor binding has reached clinical trials where it has shown to have promising efficacy. The scene has clearly been set however for a new generation of compounds, either specific to the enzyme or with dual roles, to emerge from the lab and enter the clinic. The aim of this review is to describe the current drug discovery status of small molecule, sugar and neutralising antibody inhibitors of heparanase enzyme activity. Potential strategies will also be discussed on the selection of suitable biomarker strategies for specific monitoring of in vivo heparanase inhibition which will be crucial for both animal model and clinical trial testing.

Heparanase expression correlates with poor survival in metastatic ovarian carcinoma

OBJECTIVE

To analyze the expression of Heparanase, an enzyme involved in cancer metastasis and angiogenesis, in ovarian and breast carcinoma cells in effusions.

METHODS

Heparanase protein expression was analyzed in malignant effusions from ovarian (=200) and breast (=41) carcinoma patients using immunocytochemistry. The levels of secreted heparanase were analyzed in 45 effusion supernatants using a newly established ELISA test. Heparanase expression levels were analyzed for clinical significance.

RESULTS

Heparanase was expressed at the cell membrane in 106/200 (53%) ovarian and 22/41 (54%) breast carcinomas. Cytoplasmic expression was found in 180/200 (90%) ovarian and 26/41 (63%) breast carcinomas. Reactive mesothelial cells showed frequent cytoplasmic, but not membrane expression. ELISA showed secreted heparanase in all 45 analyzed effusions. Higher levels were detected in peritoneal compared to pleural effusions (p=0.031). In univariate survival analysis of ovarian carcinoma patients with post-chemotherapy effusions, membrane expression in >5% of tumor cells correlated with shorter overall survival (OS, p=0.013). FIGO stage (p=0.03 for all patients, p=0.045 for those with post-chemotherapy specimens) and response to first-line chemotherapy (p<0.0001 for all patients, p=0.049 for those with post-chemotherapy specimens) were the clinical parameters related to OS. In Cox analysis of this subset of patients, heparanase expression (p=0.02) and response to chemotherapy (p=0.049) were independent predictors of poor OS. Heparanase expression did not correlate with survival in breast carcinoma.

CONCLUSIONS

Our data show that heparanase is frequently expressed in metastatic gynecologic adenocarcinomas, and that it is secreted into the effusion fluid in body cavities. The correlation between heparanase expression and poor survival in ovarian carcinoma suggests a role for this molecule in ovarian cancer metastasis and supports its role as a marker of aggressive clinical behavior at disease recurrence.

Regulation of mouseHeparanasegene expression in T lymphocytes and tumor cells

Heparanase (HPSE) is an endoglycosidase that cleaves heparan sulfate (HS) and plays an important role in tumor metastasis, angiogenesis and inflammation. The regulation of HPSE expression and function is tightly controlled and the increasing use of the mouse as an animal model to define the role of HPSE in many physiological and pathological settings, makes understanding the regulatory mechanisms of HPSE in this species of fundamental importance. However, the expression distribution of the mouse Hpse gene and the mechanisms that regulate its transcription are poorly defined. In this study, the mouse Hpse gene was determined to encode for two mRNA transcripts of 1.9 and 3.2 kb in length with identical open reading frames that showed similar tissue expression distribution to the human HPSE. The mouse Hpse promoter was cloned and a 478-bp minimal promoter was identified that contained regulatory elements responsible for both basal promoter activity in mouse tumor cells as well as inducible activity in T cells. Mutagenesis and transactivation studies identified a functional site in the minimal promoter region for the transcription factor Early growth response gene 1 (Egr1). Interestingly, Egr1 acted differentially in mouse tumor cells, functioning in an activating or repressive manner in breast carcinoma or melanoma cells, respectively. Furthermore, the proximal region of the promoter, identified as important in the regulation of Hpse transcription, was shown to become accessible in T cells upon cell activation. Significantly, the maximal accessibility of the promoter occurred at 16 h post-stimulation, which correlated with the induction kinetics of Hpse mRNA expression. In summary, this study demonstrates that mouse Hpse is expressed and regulated in a similar manner to human HPSE and also provides some novel insights into mechanisms of Hpse gene regulation that are likely to be relevant to control of the human gene.

Therapeutic value of glycosaminoglycans in cancer

Glycosaminoglycans are unbranched polysaccharides composed of repeating units of alternating uronic acids and amino sugars. Most glycosaminoglycans are covalently attached to core proteins to form proteoglycans. Posttranslational modifications result in specific motifs that bind to a large variety of ligands, thus regulating growth factor signaling, cellular behavior, inflammation, angiogenesis, and the proteolytic environment. Dysregulated expression of glycosaminoglycans is present in cancer and reported to correlate with clinical prognosis in several malignant neoplasms. Recent knowledge on the biological roles of these molecules in cancer biology, tumor angiogenesis, and metastasis has promoted the development of drugs targeting them. Pharmaceutical approaches include the use of chemically modified heparins and glycosaminoglycans with defined structures, combination of inhibitors of glycosaminoglycan biosynthesis and polyamine depletion, and biologically active glycosaminoglycan-binding peptides. In addition, glycosaminoglycans are used as tumor-specific delivery and targeting vehicles for toxins and chemotherapeutics. Encouraging results in animal studies and clinical trials show the clinical relevance of glycosaminoglycan-based drugs and the use of glycosaminoglycans as therapeutic targets.

A phase I biological and pharmacologic study of the heparanase inhibitor PI-88 in patients with advanced solid tumors

PURPOSE

PI-88 is a mixture of highly sulfated oligosaccharides that inhibits heparanase, an extracellular matrix endoglycosidase, and the binding of angiogenic growth factors to heparan sulfate. This agent showed potent inhibition of placental blood vessel angiogenesis as well as growth inhibition in multiple xenograft models, thus forming the basis for this study.

EXPERIMENTAL DESIGN

This study evaluated the toxicity and pharmacokinetics of PI-88 (80-315 mg) when administered s.c. daily for 4 consecutive days bimonthly (part 1) or weekly (part 2).

RESULTS

Forty-two patients [median age, 53 years (range, 19-78 years); median performance status, 1] with a range of advanced solid tumors received a total of 232 courses. The maximum tolerated dose was 250 mg/d. Dose-limiting toxicity consisted of thrombocytopenia and pulmonary embolism. Other toxicity was generally mild and included prolongation of the activated partial thromboplastin time and injection site echymosis. The pharmacokinetics were linear with dose. Intrapatient variability was low and interpatient variability was moderate. Both AUC and C(max) correlated with the percent increase in activated partial thromboplastin time, showing that this pharmacodynamic end point can be used as a surrogate for drug exposure. No association between PI-88 administration and vascular endothelial growth factor or basic fibroblast growth factor levels was observed. One patient with melanoma had a partial response, which was maintained for >50 months, and 9 patients had stable disease for >or=6 months.

CONCLUSION

The recommended dose of PI-88 administered for 4 consecutive days bimonthly or weekly is 250 mg/d. PI-88 was generally well tolerated. Evidence of efficacy in melanoma supports further evaluation of PI-88 in phase II trials.

Heparanase expression in malignant salivary gland tumors inversely correlates with long-term survival

BACKGROUND

Upregulation of the endo-beta-D-glucuronidase, heparanase, was noted in an increasing number of human malignancies. Heparanase expression correlated with enhanced local and distant metastatic spread, increased vascular density, and reduced postoperative survival.

PATIENTS AND METHODS

We analyzed heparanase expression in 60 patients (aged 59 +/- 17 years) with malignant salivary tumors (39 males and 21 females) using immunohistochemistry. We applied antiheparanase antibody 733, which has previously been shown to preferentially recognize a 50-kDa active heparanase subunit over a 65-kDa latent enzyme. Thus, immunostaining can directly be correlated with enzymatic activity.

RESULTS

Heparanase staining was positive (> 0) in 70% of tumors (42 of 60 patients) and was negative (0) in the remaining 30% (18 patients). The cumulative survival of patients diagnosed as heparanase-negative (n = 18) at 300 months was 70% (95% confidence interval = 35-88). In contrast, the cumulative survival of patients diagnosed as heparanase-positive (n = 42) at 300 months was 0% (statistically significant difference, P = .035).

CONCLUSIONS

Heparanase expression levels inversely correlate with the survival rates of salivary gland cancer patients, clearly indicating that heparanase is a reliable prognostic factor for this malignancy and an attractive target for anticancer drug development.

In vivo and in vitro degradation of heparan sulfate (HS) proteoglycans by HPR1 in pancreatic adenocarcinomas. Loss of cell surface HS suppresses fibroblast growth factor 2-mediated cell signaling and proliferation

Heparan sulfate proteoglycans (HSPGs) function as a co-receptor for heparin-binding growth factors, such as fibroblast growth factors (FGFs) and heparin-bound epidermal growth factor (HB-EGF). The HS side chain of HSPGs can be cleaved by HPR1 (heparanase-1), an endoglycosidase that is overexpressed in many types of malignancies. In the present study, we demonstrated that HPR1 expression in pancreatic adenocarcinomas inversely correlated with the presence of heparan sulfate (HS) in the basement membrane. In vitro cell culture study revealed that cell surface HS levels inversely correlated with HPR1 activity in five pancreatic cancer cell lysates and their conditioned media. Heparin and PI-88, two HPR1 inhibitors, were able to increase cell surface HS levels in PANC-1 cells in a dose-dependent manner. The ability of HPR1 to degrade cell surface HS was confirmed by showing that cell surface HS levels were increased in HT1080 cells stably transfected with the HPR1 antisense gene but was decreased in the cells overexpressing HPR1. Further studies showed that PI-88 and heparin were able to stimulate PANC-1 cell proliferation in the absence or presence of exogenous FGF2, whereas exogenous HPR1 was able to inhibit PANC-1 cell proliferation in a dose-dependent manner. Modulation of PANC-1 cell proliferation by HPR1 or HPR1 inhibitors corresponded with the inhibition or activation of the mitogen-activated protein kinase. Our results suggest that HPR1 expressed in pancreatic adenocarcinomas can suppress the proliferation of pancreatic tumor cells in response to the growth factors that require HSPGs as their co-receptors.

Heparanase induces tissue factor expression in vascular endothelial and cancer cells

BACKGROUND

Over-expression of tissue factor (TF) and activation of the coagulation system are common in cancer patients. Heparanase is an endo-beta-D-glucuronidase that cleaves heparan sulfate chains on cell surfaces and in the extracellular matrix, activity that closely correlates with cell invasion, angiogenesis and tumor metastasis. The study was undertaken to investigate the involvement of heparanase in TF expression.

METHODS

Tumor-derived cell lines were transfected with heparanase cDNA and TF expression was examined. The effect of exogenous addition of active and inactive heparanase on TF expression and activity was studied in tumor cell lines and primary human umbilical vein endothelial cells. TF expression was also explored in heparanase over-expressing transgenic (Tg) mice. Blast cells were collected from acute leukemia patients and TF and heparanase expression levels were analyzed.

RESULTS

Over-expression of heparanase in tumor-derived cell lines resulted in a 2-fold increase in TF expression levels, and a similar trend was observed in heparanase Tg mice in vivo. Likewise, exogenous addition of heparanase to endothelial or tumor-derived cells resulted in enhanced TF expression and activity. Interestingly, TF expression was also induced in response to enzymatically inactive heparanase, suggesting that this effect was independent of heparanase enzymatic activity. The regulatory effect of heparanase on TF expression involved activation of the p38 signaling pathway. A positive correlation between TF expression levels and heparanase activity was found in blasts collected from 22 acute leukemia patients.

CONCLUSIONS

Our results indicate that in addition to its well-known function as an enzyme paving a way for invading cells, heparanase also participates in the regulation of TF gene expression and its related coagulation pathways.

Heparanase, hyaluronan, and CD44 in cancers: a breast carcinoma perspective

Glycosaminoglycans are major constituents of the cancer cell surface and the tumor stroma. The heparan sulfate degrading enzyme heparanase, hyaluronan, and its receptor CD44 are up-regulated in breast cancer, generating a microenvironment that promotes tumor progression and metastasis. Recent experimental and clinical evidence shows that heparanase, hyaluronan, and CD44 regulate cancer cell proliferation, migration, and invasion, as well as tumor-associated angiogenesis and are correlated with patient survival. These findings suggest that they may be used as prognostic factors and targets for breast cancer treatment.

Mechanisms of heparin induced anti-cancer activity in experimental cancer models

BACKGROUND

Retrospective analyses of clinical trials and prospective clinical studies have suggested that heparins may have an effect on cancer survival. This putative anti-cancer activity of heparins is supported by data from studies in animal tumour models.

OBJECTIVE

To clarify the various potential mechanisms of heparin anti-cancer activity we evaluated the data from pre-clinical studies in which heparins have been tested as anti-cancer therapy.

METHODS

Pre-clinical studies, published between 1960 and 2005 were assessed. Data were collected on the type and dose of heparin used, duration of exposure to heparin, interval between heparin administration and cancer cell inoculation, and the animal tumour model used. In addition, a distinction was made in the analysis between heparin effects on the primary tumour or on established metastases and effects on the metastatic potential of infused cells.

RESULTS

Heparins seemed to affect the formation of metastasis rather than the growth of primary tumours. Chemically modified heparins with no or limited anticoagulant activity also showed anti-metastatic properties. Possible mechanisms to explain the effects on the process of metastases include inhibition of blood coagulation, inhibition of cancer cell-platelet and -endothelial interactions by selectin inhibition and inhibition of cell invasion and angiogenesis.

CONCLUSION

The anti-cancer activity of heparins depends more on inhibition of metastasis formation than on the effects on primary tumour growth. These effects are probably related to both coagulation and non-coagulation dependent factors. For a definitive proof of the anti-cancer activity of heparins in the clinic, prospective randomized trials especially in patients with early metastatic disease or in the adjuvant setting are urgently needed.

Heparanase: a new metastasis-associated antigen recognized in breast cancer patients by spontaneously induced memory T lymphocytes

Increased expression and secretion of heparanase (Hpa) by tumor cells promotes tumor invasion through extracellular matrices, tissue destruction, angiogenesis, and metastasis. Here, we show the existence in breast cancer patients of Hpa-specific T lymphocytes by fluorescence-activated cell sorting flow cytometry using Hpa peptide-MHC class I tetramers. We furthermore show memory T-cell responses in a high proportion of breast cancer patients to Hpa-derived HLA-A2-restricted peptides, leading to production of IFN-gamma and to generation of antitumor CTLs lysing breast cancer cells. Such CTLs recognized endogenously processed respective Hpa peptides on Hpa-transfected and Hpa-expressing untransfected breast carcinoma cells. According to these results and to the fact that such cells were not found in healthy people, Hpa seems to be an attractive new tumor-associated antigen and its HLA-A2-restricted peptides ought to be good candidates for peptide vaccination to reactivate memory immune responses to invasive and metastatic cancer cells.

Inhibitory effects of antisence haparanase gene on proliferation and invasion of human pancreatic cancer cell line SW1990 in vitro

AIM: To investigate the inhibitory effects of antisense heparanase gene on the proliferation and invasion of human pancreatic cancer cell line SW1990 in vitro.

METHODS: Human pancreatic cancer cell line SW1990 was transfected with the plasmid expressing antisense heparanase gene. Meanwhile, the empty vector and non-transfection group were designed. The cell cycle distribution was analyzed by flow cytometry; the protein expression of heparanase gene was detected by Western blot and immunohistochemistry, and the mRNA transcription level was assayed by reverse transcription-polymerase chain reaction (RT-PCR). The colony-forming unit assay was used to measure the ability of cell growth, and Transwell chamber model was employed to test the ability of cell invasion in vitro.

RESULTS: In comparison with the cells transfected with empty vector or without transfection, SW1990 cells transfected with antisense heparanase gene had a significant decrease in S-phase cell population (18.8% ± 2.5% vs 36.3% ± 2.2%, 33.2% ± 2.1%, both P < 0.01) and a marked increase in G1-phase cell population (66.0% ± 2.7% vs 30.7 ± 3.2%, 39.8% ± 4.9%, P < 0.01). The protein expression and mRNA transcription were decreased by 34.3% and 37.8% individually. The colony formation was largely decreased (12.2 ± 2.8 vs 30.8 ± 4.4, 28.3 ± 2.7, P < 0.01); and finally, the cells moved from the upper chamber into the lower one in Transwell chamber assay were less than those in the control groups (13.0 ± 3.5 vs 34.8 ± 5.8, 29.4 ± 5.6, P < 0.01).

CONCLUSION: Transfection of antisense heparanase gene can inhibit the ability of cell proliferation and invasion in human pancreatic cancer cell lines SW1990 in vitro.

The Shaping of a Polyvalent and Highly Individual T-Cell Repertoire in the Bone Marrow of Breast Cancer Patients

We analyzed the T-cell repertoires from the bone marrow of 39 primary operated breast cancer patients and 11 healthy female donors for the presence and frequencies of spontaneously induced effector/memory T lymphocytes with peptide-HLA-A2-restricted reactivity against 10 breast tumor-associated antigens (TAA) and 3 normal breast tissue–associated antigens by short-term IFN-γ enzyme-linked immunospot (ELISpot) analysis. Sixty-seven percent of the patients recognized TAAs with a mean frequency of 144 TAA reactive cells per 106 T cells. These patients recognized simultaneously an average of 47% of the tested TAAs. The T-cell repertoire was highly polyvalent and exhibited pronounced interindividual differences in the pattern of TAAs recognized by each patient. Strong differences of reactivity were noticed between TAAs, ranging from 100% recognition of prostate-specific antigenp141-149 to only 25% recognition of MUC1p12-20 or Her-2/neup369-377. In comparison with TAAs, reactivity to normal breast tissue–associated antigens was lower with respect to the proportions of responding patients (30%) and recognized antigens (27%), with a mean frequency of only 85/106 T cells. Healthy individuals also contained TAA-reactive T cells but this repertoire was more restricted and the frequencies were in the same range as T cells reacting to normal breast tissue–associated antigens. Our data show a highly individual T-cell repertoire for recognition of TAAs in breast cancer patients. This has potential relevance for T-cell immune diagnostics, for tumor vaccine design, and for predicting immune responsiveness. (Cancer Res 2006; 66(16): 8258-65)

The close relationship between heparanase and cyclooxygenase-2 expressions in signet-ring cell carcinoma of the stomach

Signet-ring cell carcinoma (SRC) of the stomach exhibits diffuse growth and invasion without forming ducts. Destruction of the surrounding basal membrane and angiogenesis appear to be required for SRC to exhibit marked invasion and growth. We recently reported that heparanase (HPA) and cyclooxygenase-2 (COX-2) were strongly correlated with microvessel density, and that COX-2 expression is up-regulated by HPA in esophageal cancer. In this study, we examined the relationship between HPA expression and that of COX-2 in SRC of the stomach. We examined HPA and COX-2 expression in 3 cell lines derived from SRC of the stomach and in 50 SRC lesions of stomach by immunohistochemistry (IHC), in situ hybridization, and reverse transcriptase-polymerase chain reaction (RT-PCR). We also examined the relationships among HPA expression, COX-2 expression, and the clinicopathologic features of SRC, mean age, sex, invasion depth, regional lymph node metastasis, lymphatic invasion, and venous blood vessel invasion. Of the 3 cell lines, 2 exhibited both HPA and COX-2 mRNA expression on RT-PCR. Of the 3 cell lines, 1 exhibited only HPA mRNA expression on RT-PCR. Heparanase expression was confirmed in 23 (46%) of 50 tumor samples by IHC. COX-2 expression was confirmed in 25 (50%) of the 50 tumor samples by IHC. In situ hybridization revealed messenger RNA expression in the same area as in that revealed by IHC. A close correlation was noted between HPA and COX-2 expressions (P < .0001). The present study thus elucidated the biologic features of SRC of the stomach related to growth and angiogenesis.

Regulation, function and clinical significance of heparanase in cancer metastasis and angiogenesis

Heparanase is an endoglycosidase which cleaves heparan sulfate (HS) and hence participates in degradation and remodeling of the extracellular matrix (ECM). Heparanase is preferentially expressed in human tumors and its over-expression in tumor cells confers an invasive phenotype in experimental animals. The enzyme also releases angiogenic factors from the ECM and thereby induces an angiogenic response in vivo. Heparanase upregulation correlates with increased tumor vascularity and poor post-operative survival of cancer patients. Heparanase is synthesized as a 65 kDa inactive precursor that undergoes proteolytic cleavage, yielding 8 and 50 kDa protein subunits that heterodimerize to form an active enzyme. Human heparanase is localized primarily within late endosomes and lysosomes and occasionally on the cell surface and within the cell nucleus. Transcriptional activity of the heparanase promoter is stimulated by demethylation, early growth response 1 (EGR1) transcription factor, estrogen, inflammatory cytokines and inactivation of p53. N-acetylated glycol-split species of heparin as well as siRNA heparanase gene silencing inhibit tumor metastasis and angiogenesis in experimental models. These observations and the unexpected identification of a single functional heparanase, suggest that the enzyme is a promising target for anti-cancer and anti-inflammatory drug development. Heparanase exhibits also non-enzymatic activities, independent of its involvement in ECM degradation and changes in the extracellular microenvironment. For example, cell surface expression of heparanase elicits a firm cell adhesion, reflecting an involvement in cell-ECM interaction. Heparanase enhances Akt signaling and stimulates PI3K- and p38-dependent endothelial cell migration and invasion. It also promotes VEGF expression via the Src pathway. The enzyme may thus activate endothelial cells and elicits angiogenic and survival responses. Studies with heparanase over-expressing transgenic mice revealed that the enzyme functions in normal processes involving cell mobilization, HS turnover, tissue vascularization and remodeling. In this review, we summarize the current status of heparanase research, emphasizing molecular and cellular aspects of the enzyme, including its mode of processing and activation, control of heparanase gene expression, enzymatic and non-enzymatic functions, and causal involvement in cancer metastasis and angiogenesis. We also discuss clinical aspects and strategies for the development of heparanase inhibitors.

Spatial and temporal heparanase expression in colon mucosa throughout the adenoma-carcinoma sequence

Heparanase is a mammalian endo-beta-D-glucuronidase that cleaves heparan sulfate side chains at a limited number of sites. Such enzymatic activity is thought to participate in degradation and remodeling of the extracellular matrix and to facilitate cell invasion associated with tumor metastasis, angiogenesis and inflammation. Traditionally, heparanase activity was well correlated with the metastatic potential of a large number of tumor-derived cell types. More recently, heparanase upregulation has been documented in an increasing number of primary human tumors, correlating with poor postoperative survival and increased tumor vascularity. Here, we employed anti-heparanase 733 polyclonal antibody that preferentially recognizes the 50 kDa active heparanase subunit over the 65 kDa proenzyme, as well as anti-heparanase 92.4 monoclonal antibody that recognizes both the latent and the active enzyme, to follow heparanase expression, processing and localization throughout the adenoma-carcinoma transition of the colon epithelium. Normal (nondysplastic) mucosa of the large bowel near epithelial neoplasms, as well as areas of mild dysplasia in adenomas, exhibited a strong reactivity with antibody 733 that became even stronger in foci of moderate dysplasia. Interestingly, although reactivity with antibody 733 was markedly reduced in severe dysplasia and in colorectal carcinoma, response to antibody 92.4 exhibited the opposite trend and staining intensities increased in parallel with tumor stage, the highest being in carcinoma cells. Involvement of latent heparanase (detected by 92.4, but not by 733 antibody) in tumor progression was suggested by activation of the Akt/PKB signal transduction pathway upon heparanase overexpression or exogenous addition to HT29 human colon carcinoma cells. These results suggest that heparanase expression is induced during colon carcinogenesis, and that its processing, conformation and localization are tightly regulated during the course of colon adenoma-carcinoma progression.

Heparanase promotes growth, angiogenesis and survival of primary breast tumors

Despite great strides toward diagnosis and therapy, breast cancer remains a most threatening disease in its incidence, morbidity and mortality; therefore, additional knowledge regarding the molecular mechanisms contributing to breast cancer progression, as well as new targets for drug discovery are highly needed. Heparanase is the predominant enzyme involved in cleavage of heparan sulfate, the main polysaccharide component of the extracellular matrix. Experimental and clinical data indicate that heparanase plays important roles in cancer metastasis and angiogenesis. In breast carcinoma patients, heparanase expression correlates with the metastatic potential of the tumor. The present study was undertaken to investigate the role of heparanase in local growth and angiogenesis of primary breast tumors. MCF-7 breast carcinoma cells were stable transfected with the human heparanase (H-hpa) cDNA, or empty vector (mock), and injected into the mammary pad of nude mice. MRI was applied to monitor progression of tumor growth and angiogenesis. We demonstrate that tumors produced by cells overexpressing heparanase grew faster and were 7-fold larger than tumors produced by mock transfected cells. This enhanced growth was accompanied by increased tumor vascularization and a higher degree of vessel maturation. Histological examination ascribed the differences in tumor growth to heparanase-stimulated cell proliferation and survival. In-vitro experiments reinforced heparanase role as a survival factor under stress conditions. Moreover, H-hpa tumor cells infiltrate into the adjacent stroma, promoting formation of highly vascularized fibrous bands. Our results emphasize the significance and clarify the involvement of heparanase in primary breast cancer progression by generating a supportive microenvironment that promotes tumor growth, angiogenesis and survival.

An ELISA method for the detection and quantification of human heparanase

Heparanase is a mammalian endo-beta-D-glucuronidase that cleaves heparan sulfate side chains at a limited number of sites. Heparanase enzymatic activity is thought to participate in degradation and remodeling of the extracellular matrix and to facilitate cell invasion associated with tumor metastasis, angiogenesis, and inflammation. Traditionally, heparanase activity was well correlated with the metastatic potential of a large number of tumor-derived cell types. More recently, heparanase upregulation was detected in an increasing number of primary human tumors, correlating, in some cases, with poor postoperative survival and increased tumor vascularity. The present study was undertaken to develop a highly sensitive ELISA suitable for the determination and quantification of human heparanase in tissue extracts and body fluids. The assay preferentially detects the 8+50 kDa active heparanase heterodimer vs. the latent 65 kDa proenzyme and correlates with immunoblot analysis of heparanase containing samples. It detects heparanase at concentrations as low as 200 pg/ml and is suitable for quantification of heparanase in tissue extracts and urine.

Heparanase induces vascular endothelial growth factor expression: correlation with p38 phosphorylation levels and Src activation

Heparanase is an endo-beta-D-glucuronidase involved in cleavage of heparan sulfate moieties and hence participates in extracellular matrix (ECM) degradation and remodeling. Traditionally, heparanase activity was correlated with the metastatic potential of a variety of tumor-derived cell types. Cloning of the heparanase gene indicated that heparanase expression is up-regulated in a variety of primary human tumors. In some cases, heparanase up-regulation correlated with increased tumor vascularity, an angiogenic feature that could be recapitulated in a number of in vitro and in vivo models. The mechanism by which heparanase enhances angiogenic responses is not entirely clear but is thought to be mediated primarily by release of ECM-resident angiogenic growth factors such as basic fibroblast growth factor and vascular endothelial growth factor (VEGF). Here, we examined the possibility that heparanase directly participates in VEGF gene regulation. We provide evidence that heparanase overexpression in human embryonic kidney 293, MDA-MB-435 human breast carcinoma, and rat C6 glioma cells resulted in a 3- to 6-fold increase in VEGF protein and mRNA levels, which correlated with elevation of p38 phosphorylation. Moreover, heparanase down-regulation in B16 mouse melanoma cells by a specific siRNA vector was accompanied by a decrease in VEGF and p38 phosphorylation levels, suggesting that VEGF gene expression is regulated by endogenous heparanase. Interestingly, a specific p38 inhibitor did not attenuate VEGF up-regulation by heparanase whereas Src inhibitors completely abrogated this effect. These results indicate, for the first time, that heparanase is actively involved in the regulation of VEGF gene expression, mediated by activation of Src family members.

Role of endothelial heparanase in delayed-type hypersensitivity

Heparanase is an endoglycosidase that cleaves heparan sulfate (HS), the main polysaccharide of the basement membrane (BM). HS is responsible for BM integrity and barrier function. Hence, enzymatic degradation of HS in the vascular subendothelial BM is a prerequisite for extravasation of immune cells and plasma components during inflammation. Here, we demonstrate a highly coordinated local heparanase induction upon elicitation of delayed-type hypersensitivity (DTH) reaction in the mouse ear. By monitoring in vivo activation of luciferase gene driven by the heparanase promoter, we demonstrate activation of heparanase transcription at an early stage of DTH. We report that heparanase is produced locally by the endothelium at the site of DTH-associated inflammation. Key DTH mediators, tumor necrosis factor-alpha and interferon-gamma, were found to induce heparanase in cultured endothelial cells. Endothelium emerges as an essential cellular source of heparanase enzymatic activity that, in turn, allows for remodeling of the vascular BM, increased vessel permeability, and extravasation of leukocytes and plasma proteins. In vivo administration of antiheparanase siRNA or an inhibitor of heparanase enzymatic activity effectively halted DTH inflammatory response. Collectively, our results highlight the decisive role of endothelial heparanase in DTH inflammation and its potential as a promising target for anti-inflammatory drug development.

A new targeting approach for breast cancer gene therapy using the heparanase promoter

Gene therapy with adenoviral (Ad) vectors is a promising new approach in the treatment of cancer. Strategies to restrict adenoviral-mediated transgene expression are important to avoid gene transfer into normal cells. Heparanase (HPR) is overexpressed in breast cancer but downregulated in differentiated normal tissue. Expression of the HPR gene was evaluated in breast cancer cells. Biodistribution and liver tropism was evaluated in a mouse model. HPR is highly expressed in breast cancer tissue. The HPR promoter retained its fidelity in an adenovirus context and was activated in breast cancer cells but showed low activity in normal breast cells and the murine liver. We conclude that the HPR pathway is a promising target for the development of breast cancer directed gene therapy strategies.

High-throughput methods for measuring heparanase activity and screening potential antimetastatic and anti-inflammatory agents

Heparanase plays an important role in the degradation of the extracellular matrix. It is implicated in inflammation, tumor angiogenesis and metastasis. We have developed two high-throughput methods for measuring heparanase activity and screening potential inhibitors. The first method involves coating fibroblast growth factor (FGF) on microtiter plates and capturing fluorescein isothiocyanate (FITC)-labeled heparin sulfate (HS), which is used as a substrate for heparanase digestion. Labeled HS fragments are released into the medium and quantitated by fluorescence intensity measurement. We have implemented this assay method into a Zeiss uHTS system and screened compound libraries for heparanase inhibitors. The second method involves labeling HS with biotin followed by FITC to generate a dual-labeled HS. The labeled material is bound to streptavidin-coated plates and used as a substrate for heparanase digestion. Both methods are sensitive and easily applicable to robotic systems. In addition, we have labeled both HS and biotin-HS with Eu-chelate, a fluorophore that exhibits long decay fluorescence. Assays using Eu-labeled HS and Eu-labeled biotin-HS have been developed and show higher sensitivity than those using FITC-labeled material. Furthermore, assays using Eu-chelate HS (or biotin-HS) should eliminate the interference of fluorescence compounds.

Early growth response gene 1 (EGR1) regulates heparanase gene transcription in tumor cells

Heparanase is an endoglycosidase that degrades heparan sulfate chains of heparan sulfate proteoglycans, a key component of extracellular matrix and basement membranes. Studies using heparanase inhibitors and gene silencing have provided evidence to support an important role for heparanase in tumor metastasis and angiogenesis. The expression of heparanase is normally very tightly controlled, however, it is commonly deregulated in tumor cells, which express elevated heparanase activity that correlates with high levels of heparanase mRNA. We recently identified the transcription factor early growth response gene 1, EGR1, as a key regulator of inducible heparanase transcription in T cells. In this study using chromatin immunoprecipitation, we demonstrate for the first time that EGR1 binds to the heparanase gene promoter in vivo. The important question of the role of EGR1 in regulating heparanase transcription in tumor cells was then assessed. Studies were carried out in four epithelial tumor lines of different tissue origin. Functional dissection of the heparanase promoter identified a 280-bp region that was critical for transcription of the heparanase gene. Transactivation studies using an EGR1 expression vector co-transfected with a reporter construct containing the 280-bp region showed EGR1-activated heparanase promoter activity in a dose-dependent manner in prostate or breast adenocarcinoma and colon carcinoma cell lines. In contrast, overexpression of EGR1 resulted in a dose-dependent repression of promoter activity in melanoma cells. Using site-directed mutagenesis the 280-bp region was found to contain two functional EGR1 sites and electrophoretic mobility shift assays showed binding of EGR1 to both of these sites upon activation of tumor cells. Furthermore, the heparanase promoter region containing the EGR1 sites was also inducible in tumor cells and induction corresponded to HPSE expression levels. These studies show that EGR1 regulates heparanase transcription in tumor cells and importantly, can have a repressive or activating role depending on the tumor type.

A functional heparan sulfate mimetic implicates both heparanase and heparan sulfate in tumor angiogenesis and invasion in a mouse model of multistage cancer

Heparan sulfate proteoglycans are integral components of the extracellular matrix that surrounds all mammalian cells. In addition to providing structural integrity, they act as a storage depot for a variety of heparan sulfate (HS)-binding proteins, including growth factors and chemokines. Heparanase is a matrix-degrading enzyme that cleaves heparan sulfate side chains from the core proteoglycans, thus liberating such HS-binding proteins, as well as potentially contributing to extracellular matrix degradation. Here, we report that heparanase mRNA and protein expression are increased in the neoplastic stages progressively unfolding in a mouse model of multistage pancreatic islet carcinogenesis. Notably, heparanase is delivered to the neoplastic lesions in large part by infiltrating Gr1+/Mac1+ innate immune cells. A sulfated oligosaccharide mimetic of heparan sulfate, PI-88, was used to inhibit simultaneously both heparanase activity and HS effector functions. PI-88 had significant effects at distinct stages of tumorigenesis, producing a reduction in the number of early progenitor lesions and an impairment of tumor growth at later stages. These responses were associated with decreased cell proliferation, increased apoptosis, impaired angiogenesis, and a substantive reduction in the number of invasive carcinomas. In addition, we show that the reduction in tumor angiogenesis is correlated with a reduced association of VEGF-A with its receptor VEGF-R2 on the tumor endothelium, implicating heparanase in the mobilization of matrix-associated VEGF. These data encourage clinical applications of inhibitors such as PI-88 for the many human cancers where heparanase expression is elevated or mobilization of HS-binding regulatory factors is implicated.

Expression of Heparanase by Primary Breast Tumors Promotes Bone Resorption in the Absence of Detectable Bone Metastases

Heparanase is an enzyme that cleaves heparan sulfate and through this activity promotes tumor growth, angiogenesis, invasion, and metastasis in several tumor types. In human breast cancer patients, heparanase expression is associated with sentinel lymph node metastases. However, the precise role of heparanase in the malignant progression of breast cancer is unknown. To examine this, a variant of MDA-MB-231 cells was transfected with the cDNA for human heparanase (HPSE cells) or with vector alone as a control (NEO cells). Transfection produced a 6-fold increase in heparanase activity in HPSE cells relative to NEO cells. When injected into the mammary fat pads of severe combined immunodeficient mice, the tumors formed by HPSE cells initially grow significantly faster than the tumors formed by NEO cells. The rapid growth is due in part to increased angiogenesis, as microvessel densities are substantially elevated in primary HPSE tumors compared with NEO tumors. Although metastases to bones are not detected, surprisingly vigorous bone resorption is stimulated in animals bearing tumors formed by the HPSE cells. These animals have high serum levels of the C-telopeptide derived from type I collagen as well as significant elevation of the active form of tartrate-resistant acid phosphatase (TRAP)-5b. In contrast, in animals having a high tumor burden of Neo cells, the serum levels of C-telopeptide and TRAP-5b never increase above the levels found before tumor injection. Consistent with these findings, histologic analysis for TRAP-expressing cells reveals extensive osteoclastogenesis in animals harboring HPSE tumors. In vitro osteoclastogenesis assays show that the osteoclastogenic activity of HPSE cell conditioned medium is significantly enhanced beyond that of NEO conditioned medium. This confirms that a soluble factor or factors that stimulate osteoclastogenesis are specifically produced when heparanase expression is elevated. These factors exert a distal effect resulting in resorption of bone and the accompanying enrichment of the bone microenvironment with growth-promoting factors that may nurture the growth of metastatic tumor cells. This novel role for heparanase as a promoter of osteolysis before tumor metastasis suggests that therapies designed to block heparanase function may disrupt the early progression of bone-homing tumors.

Heparanase-1 gene expression and regulation by high glucose in renal epithelial cells: a potential role in the pathogenesis of proteinuria in diabetic patients

The molecular mechanisms of heparan sulfate proteoglycan downregulation in the glomerular basement membrane (GBM) of the kidneys with diabetic nephropathy remain controversial. In the present study, we showed that the expression of heparanase-1 (HPR1), a heparan sulfate-degrading endoglycosidase, was upregulated in the renal epithelial cells in the kidney with diabetic nephropathy. Urinary HPR1 levels were elevated in patients with diabetic nephropathy. In vitro cell culture studies revealed that HPR1 promoter-driven luciferase reporter gene expression, HPR1 mRNA, and protein were upregulated in renal epithelial cells under high glucose conditions. Induction of HPR1 expression by high glucose led to decreased cell surface heparan sulfate expression. HPR1 inhibitors were able to restore cell surface heparan sulfate expression. Functional analysis revealed that renal epithelial cells grown under high glucose conditions resulted in an increase of basement membrane permeability to albumin. Our studies suggest that loss of heparan sulfate in the GBM with diabetic nephropathy is attributable to accelerated heparan sulfate degradation by increased HPR1 expression.

Emergence of nuclear heparanase induces differentiation of human mammary cancer cells

The study of epithelial differentiation touches upon many modern aspects of biology. The epithelium is in constant dialogue with the underlying mesenchyme to control stem cell activity, proliferation in transit-amplifying compartments, lineage commitment, terminal differentiation and, ultimately, cell death. There are spatially distinct compartments dedicated to each of these events. Recently we reported that heparanase is expressed in nucleus as well as in the cytoplasm and that nuclear heparanase seems to be related to cell differentiation. In this study, we investigated the role of nuclear heparanase in differentiation by transducing human mammary epithelial cancer cells with heparanase which was delivered specifically into nucleus. We observed that expression of nuclear heparanase allowed the cells to differentiate with the appearance of lipid droplets. This finding supports the idea that heparanase plays a novel role in epithelial cell differentiation apart from its known enzymatic function.