Post-transcriptional regulation of heparanase gene expression by a 3' AU-rich element

Chemoradiotherapy Increases Intratumor Heterogeneity of HPSE Expression in the Relapsed Glioblastoma Tumors

Adjuvant chemoradiotherapy is a standard treatment option for glioblastoma multiforme (GBM). Despite intensive care, recurrent tumors developed during the first year are fatal for the patients. Possibly contributing to this effect, among other causes, is that therapy induces changes of polysaccharide heparan sulfate (HS) chains in the cancer cells and/or tumor microenvironment. The aim of this study was to perform a comparative analysis of heparanase (HPSE) expression and HS content in different normal and GBM brain tissues. Immunohistochemical analysis revealed a significant decrease of HPSE protein content in the tumor (12-15-fold) and paratumorous (2.5-3-fold) GBM tissues compared with normal brain tissue, both in cellular and extracellular compartments. The relapsed GBM tumors demonstrated significantly higher intertumor and/or intratumor heterogeneity of HPSE and HS content and distribution compared with the matched primary ones (from the same patient) (n = 8), although overall expression levels did not show significant differences, suggesting local deterioration of HPSE expression with reference to the control system or by the treatment. Double immunofluorescence staining of various glioblastoma cell lines (U87, U343, LN18, LN71, T406) demonstrated a complex pattern of HPSE expression and HS content with a tendency towards a negative association of these parameters. Taken together, the results demonstrate the increase of intratumor heterogeneity of HPSE protein in relapsed GBM tumors and suggest misbalance of HPSE expression regulation by the adjuvant anti-GBM chemoradiotherapy.

Forty Years of Basic and Translational Heparanase Research

This review summarizes key developments in the heparanase field obtained 20 years prior to cloning of the HPSE gene and nearly 20 years after its cloning. Of the numerous publications and review articles focusing on heparanase, we have selected those that best reflect the progression in the field as well as those we regard important accomplishments with preference to studies performed by scientists and groups that contributed to this book. Apart from a general 'introduction' and 'concluding remarks', the abstracts of these studies are presented essentially as published along the years. We apologize for not being objective and not being able to include some of the most relevant abstracts and references, due to space limitation. Heparanase research can be divided into two eras. The first, initiated around 1975, dealt with identifying the enzyme, establishing the relevant assay systems and investigating its biological activities and significance in cancer and other pathologies. Studies performed during the first area are briefly introduced in a layman style followed by the relevant abstracts presented chronologically, essentially as appears in PubMed. The second era started in 1999 when the heparanase gene was independently cloned by 4 research groups [1-4]. As expected, cloning of the heparanase gene boosted heparanase research by virtue of the readily available recombinant enzyme, molecular probes, and anti-heparanase antibodies. Studies performed during the second area are briefly introduced followed by selected abstracts of key findings, arranged according to specific topics.

Heparanase Inhibition by Pixatimod (PG545): Basic Aspects and Future Perspectives

Pixatimod is an inhibitor of heparanase, a protein which promotes cancer via its regulation of the extracellular environment by enzymatic cleavage of heparan sulfate (HS) and non-enzymatic signaling. Through its inhibition of heparanase and other HS-binding signaling proteins, pixatimod blocks a number of pro-cancerous processes including cell proliferation, invasion, metastasis, angiogenesis and epithelial-mesenchymal transition. Several laboratories have found that these activities have translated into potent activity using a range of different mouse cancer models, including approximately 30 xenograft and 20 syngeneic models. Analyses of biological samples from these studies have confirmed the heparanase targeting of this agent in vivo and the broad spectrum of anti-cancer effects that heparanase blockade achieves. Pixatimod has been tested in combination with a number of approved anti-cancer drugs demonstrating its clinical potential, including with gemcitabine, paclitaxel, sorafenib, platinum agents and an anti-PD-1 antibody. Clinical testing has shown pixatimod to be well tolerated as a monotherapy, and it is currently being investigated in combination with the anti-PD-1 drug nivolumab in a pancreatic cancer phase I trial.

Involvement of Heparanase in the Pathogenesis of Mesothelioma: Basic Aspects and Clinical Applications

Background

Mammalian cells express a single functional heparanase, an endoglycosidase that cleaves heparan sulfate and thereby promotes tumor metastasis, angiogenesis, and inflammation. Malignant mesothelioma is highly aggressive and has a poor prognosis because of the lack of markers for early diagnosis and resistance to conventional therapies. The purpose of this study was to elucidate the mode of action and biological significance of heparanase in mesothelioma and test the efficacy of heparanase inhibitors in the treatment of this malignancy.

Methods

The involvement of heparanase in mesothelioma was investigated by applying mouse models of mesothelioma and testing the effect of heparanase gene silencing (n = 18 mice per experiment; two different models) and heparanase inhibitors (ie, PG545, defibrotide; n = 18 per experiment; six different models). Synchronous pleural effusion and plasma samples from patients with mesothelioma (n = 35), other malignancies (12 non-small cell lung cancer, two small cell lung carcinoma, four breast cancer, three gastrointestinal cancers, two lymphomas), and benign effusions (five patients) were collected and analyzed for heparanase content (enzyme-linked immunosorbent assay). Eighty-one mesothelioma biopsies were analyzed by H-Score for the prognostic impact of heparanase using immunohistochemistry. All statistical tests were two-sided.

Results

Mesothelioma tumor growth, measured by bioluminescence or tumor weight at termination, was markedly attenuated by heparanase gene silencing (P = .02) and by heparanase inhibitors (PG545 and defibrotide; P < .001 and P = .01, respectively). A marked increase in survival of the mesothelioma-bearing mice (P < .001) was recorded. Heparanase inhibitors were more potent in vivo than conventional chemotherapy. Clinically, heparanase levels in patients' pleural effusions could distinguish between malignant and benign effusions, and a heparanase H-score above 90 was associated with reduced patient survival (hazard ratio = 1.89, 95% confidence interval = 1.09 to 3.27, P = .03).

Conclusions

Our results imply that heparanase is clinically relevant in mesothelioma development. Given these preclinical and clinical data, heparanase appears to be an important mediator of mesothelioma, and heparanase inhibitors are worthy of investigation as a new therapeutic modality in mesothelioma clinical trials.

Heparanase promotes glioma progression via enhancing CD24 expression

Heparanase is an endo-β-d-glucuronidase that cleaves heparan sulfate (HS) side chains of heparan sulfate proteoglycans. Compelling evidence tie heparanase levels with all steps of tumor formation including tumor initiation, growth, metastasis and chemo-resistance, likely involving augmentation of signaling pathways and gene transcription. In order to reveal the molecular mechanism(s) underlying the protumorigenic properties of heparanase, we established an inducible (Tet-on) system in U87 human glioma cells and applied gene array methodology in order to identify genes associated with heparanase induction. We found that CD24, a mucin-like cell adhesion protein, is consistently upregulated by heparanase and by heparanase splice variant devoid of enzymatic activity, whereas heparanase gene silencing was associated with decreased CD24 expression. This finding was further substantiated by a similar pattern of heparanase and CD24 immunostaining in glioma patients (Pearson's correlation; R = 0.66, p = 0.00001). Noteworthy, overexpression of CD24 stimulated glioma cell migration, invasion, colony formation in soft agar and tumor growth in mice suggesting that CD24 functions promote tumor growth. Likewise, anti-CD24 neutralizing monoclonal antibody attenuated glioma tumor growth, and a similar inhibition was observed in mice treated with a neutralizing mAb directed against L1 cell adhesion molecule (L1CAM), a ligand for CD24. Importantly, significant shorter patient survival was found in heparanase-high/CD24-high tumors vs. heparanase-high/CD24-low tumors for both high-grade and low-grade glioma (p = 0.02). Our results thus uncover a novel heparanase-CD24-L1CAM axis that plays a significant role in glioma tumorigenesis.

Targeting Heparanase in Cancer: Inhibition by Synthetic, Chemically Modified, and Natural Compounds

Heparanase is an endoglycosidase involved in remodeling the extracellular matrix and thereby in regulating multiple cellular processes and biological activities. It cleaves heparan sulfate (HS) side chains of HS proteoglycans into smaller fragments and hence regulates tissue morphogenesis, differentiation, and homeostasis. Heparanase is overexpressed in various carcinomas, sarcomas, and hematological malignancies, and its upregulation correlates with increased tumor size, tumor angiogenesis, enhanced metastasis, and poor prognosis. In contrast, knockdown or inhibition of heparanase markedly attenuates tumor progression, further underscoring the potential of anti-heparanase therapy. Heparanase inhibitors were employed to interfere with tumor progression in preclinical studies, and selected heparin mimetics are being examined in clinical trials. However, despite tremendous efforts, the discovery of heparanase inhibitors with high clinical benefit and minimal adverse effects remains a therapeutic challenge. This review discusses the key roles of heparanase in cancer progression focusing on the status of natural, chemically modified, and synthetic heparanase inhibitors in various types of malignancies.

The heparanase inhibitor PG545 is a potent anti-lymphoma drug: Mode of action

It is now well recognized that heparanase, an endo-β-D-glucuronidase capable of cleaving heparan sulfate (HS) side chains at a limited number of sites, promotes tumorigenesis by diverse mechanisms. Compelling evidence strongly implies that heparanase is a viable target for cancer therapy, thus encouraging the development of heparanase inhibitors as anti-cancer therapeutics. Here, we examined the efficacy and mode of action of PG545, an HS-mimetic heparanase inhibitor, in human lymphoma. We found that PG545 exhibits a strong anti-lymphoma effect, eliciting lymphoma cell apoptosis. Notably, this anti-lymphoma effect involves ER stress response that was accompanied by increased autophagy. The persistent ER stress evoked by PG545 is held responsible for cell apoptosis because apoptotic cell death was attenuated by an inhibitor of PERK, a molecular effector of ER stress. Importantly, PG545 had no such apoptotic effect on naïve splenocytes, further encouraging the development of this compound as anti-lymphoma drug. Surprisingly, we found that PG545 also elicits apoptosis in lymphoma cells that are devoid of heparanase activity (i.e., Raji), indicating that the drug also exerts heparanase-independent function(s) that together underlie the high potency of PG545 in preclinical cancer models.

Heparan sulfate proteoglycans undergo differential expression alterations in left sided colorectal cancer, depending on their metastatic character

Background

Heparan sulfate proteoglycans (HSPGs) are complex molecules which play a role in the invasion and growth and metastatic properties of cancerous cells. In this work we analyze changes in the patterns of expression of HSPGs in left sided colorectal cancer (LSCRC), both metastatic and non-metastatic, and the results are also compared with those previously obtained for right sided tumors (RSCRCs).

Methods

Eighteen LSCRCs were studied using qPCR to analyze the expression of both the proteoglycan core proteins and the enzymes involved in heparan sulfate chain biosynthesis. Certain HSPGs also carry chondroitin sulfate chains and so we also studied the genes involved in its biosynthesis. The expression of certain genes that showed significant expression differences were also analysed using immunohistochemical techniques.

Results

Changes in proteoglycan core proteins were dependent on their location, and the main differences between metastatic and non-metastatic tumors affected cell-surface glypicans, while other molecules were quite similar. Glypicans were also responsible for the main differences between RS- and LS- malignances. Regarding the biosynthesis of heparan sulfate chains, differential alterations in transcription depending on the presence or not of metastasis affected genes involved in the modification of uronic acid (epimerization and 2-O sulfation), and some isoforms responsible for sulfation of glucosamine (NDST1, HS6ST1). Moreover, in RSCRCs differences were preferentially found in the expression of genes involved in C6 and C3 sulfation of glucosamine, but not in NDSTs or SULFs. Finally, synthesis of chondroitin sulfate showed some alterations, which affected various steps, including polimerization and the modification of chains, but the main variations dependent on the presence of metastases were epimerization and 6C sulfation; however, when compared with RSCRCs, the essential divergences affected polymerization of the chains and the 6C sulfation of the galactosamine residue.

Conclusions

We evidenced alterations in the expression of HSPGs, including the expression of cell surface core proteins, many glycosiltransferases and some enzymes that modify the GAG chains in LSCRCs, but this was dependent on the metastatic nature of the tumor. Some of these alterations are shared with RSCRCs, while others, focused on specific gene groups, are dependent on tumor localization.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4597-x) contains supplementary material, which is available to authorized users.

Patient derived xenografts (PDX) predict an effective heparanase-based therapy for lung cancer

Heparanase, the sole heparan sulfate (HS) degrading endoglycosidase, regulates multiple biological activities that enhance tumor growth, metastasis, angiogenesis, and inflammation. Heparanase accomplishes this by degrading HS and thereby facilitating cell invasion and regulating the bioavailability of heparin-binding proteins. HS mimicking compounds that inhibit heparanase enzymatic activity were examined in numerous preclinical cancer models. While these studies utilized established tumor cell lines, the current study utilized, for the first time, patient-derived xenografts (PDX) which better resemble the behavior and drug responsiveness of a given cancer patient. We have previously shown that heparanase levels are substantially elevated in lung cancer, correlating with reduced patients survival. Applying patient-derived lung cancer xenografts and a potent inhibitor of heparanase enzymatic activity (PG545) we investigated the significance of heparanase in the pathogenesis of lung cancer. PG545 was highly effective in lung cancer PDX, inhibiting tumor growth in >85% of the cases. Importantly, we show that PG545 was highly effective in PDX that did not respond to conventional chemotherapy (cisplatin) and vice versa. Moreover, we show that spontaneous metastasis to lymph nodes is markedly inhibited by PG545 but not by cisplatin. These results reflect the variability among patients and strongly imply that PG545 can be applied for lung cancer therapy in a personalized manner where conventional chemotherapy fails, thus highlighting the potential benefits of developing anti-heparanase treatment modalities for oncology.

Upregulated Expression of Heparanase and Heparanase 2 in the Brains of Alzheimer's Disease

BACKGROUND

Heparan sulfate proteoglycans (HSPGs) promote amyloid-β peptide and tau fibrillization in Alzheimer's disease (AD) and provide resistance against proteolytic breakdown. Heparanase (HPSE) is the only enzyme that cleaves heparan sulfate (HS). Heparanase 2 (HPSE2) lacks HS-degrading activity, although it is able to interact with HS with high affinity.

OBJECTIVE

To analyze HPSE and HPSE2 expressions at different stages of AD.

METHODS

RT-PCR was used to analyze transcription levels of both heparanases at different stages of AD, and immunohistochemistry was performed to localize each one in different parts of the brain.

RESULTS

Both proteins appeared overexpressed at different stages of AD. Immunohistochemistry indicated that the presence of the heparanases was related to AD pathology, with intracellular deposits found in degenerated neurons. At the extracellular level, HPSE was observed only in neuritic plaques with a fragmented core, while HPSE2 appeared in those with compact cores as well.

CONCLUSION

Given the involvement of HSPGs in AD pathology, there would seem to be a relationship between the regulation of heparanase expression, the features of the disease, and a possible therapeutic alternative.

The prognostic significance of heparanase expression in metastatic melanoma

BACKGROUND

Heparanase expression is induced in many types of cancers, including melanoma, and promotes tumor growth, angiogenesis and metastasis. However, there is insufficient data regarding heparanase expression in the metastatic lesions that are the prime target for anti-cancer therapeutics. To that end, we examined heparanase expression in metastatic melanoma and its correlation with clinical parameters.

RESULTS

Heparanase staining was detected in 88% of the samples, and was strong in 46%. For the entire cohort of metastatic melanoma patients, no apparent correlation was found between heparanase staining intensity and survival. However, in a sub group of 46 patients diagnosed as stage IVc melanoma, strong heparanase staining was associated with reduced survival rates [hazard ratio=2.1; 95%CI 1.1-4.1, p=0.025].

MATERIAL AND METHODS

Paraffin sections from 69 metastatic melanomas were subjected to immunohistochemical analysis, applying anti-heparanase antibody. The clinical and pathological data, together with heparanase staining intensity, were evaluated in a logistic regression model for site of metastasis and survival. Slides were also stained for the heparanase-homolog, heparanase-2 (Hpa2).

CONCLUSIONS

Heparanase is highly expressed in metastatic melanoma and predicts poor survival of stage IVc melanoma patients, justifying the development and implementation of heparanase inhibitors as anti-cancer therapeutics.

Opposing Functions of Heparanase-1 and Heparanase-2 in Cancer Progression

Heparanase, the sole heparan sulfate (HS)-degrading endoglycosidase, regulates multiple biological activities that enhance tumor growth, metastasis, angiogenesis, and inflammation. Heparanase accomplishes this by degrading HS and thereby regulating the bioavailability of heparin-binding proteins; priming the tumor microenvironment; mediating tumor-host crosstalk; and inducing gene transcription, signaling pathways, exosome formation, and autophagy that together promote tumor cell performance and chemoresistance. By contrast, heparanase-2, a close homolog of heparanase, lacks enzymatic activity, inhibits heparanase activity, and regulates selected genes that promote normal differentiation, endoplasmic reticulum stress, tumor fibrosis, and apoptosis, together resulting in tumor suppression. The emerging premise is that heparanase is a master regulator of the aggressive phenotype of cancer, while heparanase-2 functions as a tumor suppressor.

The Heparanase Inhibitor PG545 Attenuates Colon Cancer Initiation and Growth, Associating with Increased p21 Expression

Heparanase activity is highly implicated in cellular invasion and tumor metastasis, a consequence of cleavage of heparan sulfate and remodeling of the extracellular matrix underlying epithelial and endothelial cells. Heparanase expression is rare in normal epithelia, but is often induced in tumors, associated with increased tumor metastasis and poor prognosis. In addition, heparanase induction promotes tumor growth, but the molecular mechanism that underlines tumor expansion by heparanase is still incompletely understood. Here, we provide evidence that heparanase down regulates the expression of p21 (WAF1/CIP1), a cyclin-dependent kinase inhibitor that attenuates the cell cycle. Notably, a reciprocal effect was noted for PG545, a potent heparanase inhibitor. This compound efficiently reduced cell proliferation, colony formation, and tumor xenograft growth, associating with a marked increase in p21 expression. Utilizing the APC Min^+/− mouse model, we show that heparanase expression and activity are increased in small bowel polyps, whereas polyp initiation and growth were significantly inhibited by PG545, again accompanied by a prominent induction of p21 levels. Down-regulation of p21 expression adds a novel feature for the emerging pro-tumorigenic properties of heparanase, while the potent p21 induction and anti-tumor effect of PG545 lends optimism that it would prove an efficacious therapeutic in colon carcinoma patients.

Heparanase regulation of cancer, autophagy and inflammation: new mechanisms and targets for therapy

Because of its impact on multiple biological pathways, heparanase has emerged as a major regulator of cancer, inflammation and other disease processes. Heparanase accomplishes this by degrading heparan sulfate which regulates the abundance and location of heparin-binding growth factors thereby influencing multiple signaling pathways that control gene expression, syndecan shedding and cell behavior. In addition, heparanase can act via nonenzymatic mechanisms that directly activate signaling at the cell surface. Clinical trials testing heparanase inhibitors as anticancer therapeutics are showing early signs of efficacy in patients further emphasizing the biological importance of this enzyme. This review focuses on recent developments in the field of heparanase regulation of cancer and inflammation, including the impact of heparanase on exosomes and autophagy, and novel mechanisms whereby heparanase regulates tumor metastasis, angiogenesis and chemoresistance. In addition, the ongoing development of heparanase inhibitors and their potential for treating cancer and inflammation are discussed.

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-neutralizing antibodies attenuate lymphoma tumor growth and metastasis

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

Heparan sulfate proteoglycans undergo differential expression alterations in right sided colorectal cancer, depending on their metastatic character

Background

Heparan sulfate proteoglycans (HSPGs) are complex molecules involved in the growth, invasion and metastatic properties of cancerous cells. This study analyses the alterations in the expression patterns of these molecules in right sided colorectal cancer (CRC), both metastatic and non-metastatic.

Methods

Twenty right sided CRCs were studied. A transcriptomic approach was used, employing qPCR to analyze both the expression of the enzymes involved in heparan sulfate (HS) chains biosynthesis, as well as the proteoglycan core proteins. Since some of these proteoglycans can also carry chondroitin sulfate (CS) chains, we include the study of the genes involved in the biosynthesis of these glycosaminoglycans. Immunohistochemical techniques were also used to analyze tissue expression of particular genes showing significant expression differences, of potential interest.

Results

Changes in proteoglycan core proteins differ depending on their location; those located intracellularly or in the extracellular matrix show very similar alteration patterns, while those located on the cell surface vary greatly depending on the nature of the tumor: glypicans 1, 3, 6 and betaglycan are affected in the non-metastatic tumors, whereas in the metastatic, only glypican-1 and syndecan-1 are modified, the latter showing opposing alterations in levels of RNA and of protein, suggesting post-transcriptional regulation in these tumors. Furthermore, in non-metastatic tumors, polymerization of glycosaminoglycan chains is modified, particularly affecting the synthesis of the tetrasaccharide linker and the initiation and elongation of CS chains, HS chains being less affected. Regarding the enzymes responsible for the modificaton of the HS chains, alterations were only found in non-metastatic tumors, affecting N-sulfation and the isoforms HS6ST1, HS3ST3B and HS3ST5. In contrast, synthesis of the CS chains suggests changes in epimerization and sulfation of the C4 and C2 in both types of tumor.

Conclusions

Right sided CRCs show alterations in the expression of HSPGs, including the expression of the cell surface core proteins, many glycosiltransferases and some enzymes that modify the HS chains depending on the metastatic nature of the tumor, resulting more affected in non-metastatic ones. However, matrix proteoglycans and enzymes involved in CS fine structure synthesis are extensively modified independetly of the presence of lymph node metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1724-9) contains supplementary material, which is available to authorized users.

Heparanase Enhances Tumor Growth and Chemoresistance by Promoting Autophagy

Heparanase is the only enzyme in mammals capable of cleaving heparan sulfate, an activity implicated in tumor inflammation, angiogenesis, and metastasis. Heparanase is secreted as a latent enzyme that is internalized and subjected to proteolytic processing and activation in lysosomes. Its role under normal conditions has yet to be understood. Here, we provide evidence that heparanase resides within autophagosomes, where studies in heparanase-deficient or transgenic mice established its contributions to autophagy. The protumorigenic properties of heparanase were found to be mediated, in part, by its proautophagic function, as demonstrated in tumor xenograft models of human cancer and through use of inhibitors of the lysosome (chloroquine) and heparanase (PG545), both alone and in combination. Notably, heparanase-overexpressing cells were more resistant to stress and chemotherapy in a manner associated with increased autophagy, effects that were reversed by chloroquine treatment. Collectively, our results establish a role for heparanase in modulating autophagy in normal and malignant cells, thereby conferring growth advantages under stress as well as resistance to chemotherapy. Cancer Res; 75(18); 3946-57. ©2015 AACR.

Heparanase promotes tumor infiltration and antitumor activity of CAR-redirected T lymphocytes

Adoptive transfer of chimeric antigen receptor (CAR)-redirected T lymphocytes (CAR-T cells) has had less striking effects in solid tumors^1–3 than in lymphoid malignancies^{4, 5}. Although active tumor-mediated immunosuppression may play a role in limiting efficacy⁶, functional changes in T lymphocytes following their ex vivo manipulation may also account for cultured CAR-T cells’ reduced ability to penetrate stroma-rich solid tumors. We therefore studied the capacity of human in vitro-cultured CAR-T cells to degrade components of the extracellular matrix (ECM). In contrast to freshly isolated T lymphocytes, we found that in vitro-cultured T lymphocytes lack expression of the enzyme heparanase (HPSE) that degrades heparan sulphate proteoglycans, which are main components of ECM. We found that HPSE mRNA is down regulated in in vitro-expanded T cells, which may be a consequence of p53 binding to the HPSE gene promoter. We therefore engineered CAR-T cells to express HPSE and showed improved capacity to degrade ECM, which promoted tumor T-cell infiltration and antitumor activity. Employing this strategy may enhance the activity of CAR-T cells in individuals with stroma-rich solid tumors.

Heparanase enhances myeloma progression via CXCL10 downregulation

In order to explore the mechanism(s) underlying the pro-tumorigenic capacity of heparanase, we established an inducible Tet-on system. Heparanase expression was markedly increased following addition of doxycycline (Dox) to the culture medium of CAG human myeloma cells infected with the inducible heparanase gene construct, resulting in increased colony number and size in soft agar. Moreover, tumor xenografts produced by CAG-heparanase cells were markedly increased in mice supplemented with Dox in their drinking water compared with control mice maintained without Dox. Consistently, we found that heparanase induction is associated with decreased levels of CXCL10, suggesting that this chemokine exerts tumor-suppressor properties in myeloma. Indeed, recombinant CXCL10 attenuated the proliferation of CAG, U266 and RPMI-8266 myeloma cells. Similarly, CXCL10 attenuated the proliferation of human umbilical vein endothelial cells, implying that CXCL10 exhibits anti-angiogenic capacity. Strikingly, development of tumor xenografts produced by CAG-heparanase cells overexpressing CXCL10 was markedly reduced compared with control cells. Moreover, tumor growth was significantly attenuated in mice inoculated with human or mouse myeloma cells and treated with CXCL10-Ig fusion protein, indicating that CXCL10 functions as a potent anti-myeloma cytokine.

Heparanase cooperates with Ras to drive breast and skin tumorigenesis

Heparanase has been implicated in cancer but its contribution to the early stages of cancer development is uncertain. In this study, we utilized nontransformed human MCF10A mammary epithelial cells and two genetic mouse models [Hpa-transgenic (Hpa-Tg) and knockout mice] to explore heparanase function at early stages of tumor development. Heparanase overexpression resulted in significantly enlarged asymmetrical acinar structures, indicating increased cell proliferation and decreased organization. This phenotype was enhanced by coexpression of heparanase variants with a mutant H-Ras gene, which was sufficient to enable growth of invasive carcinoma in vivo. These observations were extended in vivo by comparing the response of Hpa-Tg mice to a classical two-stage 12-dimethylbenz(a)anthracene (DMBA)/12-o-tetradecanoylphorbol-13-acetate (TPA) protocol for skin carcinogenesis. Hpa-Tg mice overexpressing heparanase were far more sensitive than control mice to DMBA/TPA treatment, exhibiting a 10-fold increase in the number and size of tumor lesions. Conversely, DMBA/TPA-induced tumor formation was greatly attenuated in Hpa-KO mice lacking heparanase, pointing to a critical role of heparanase in skin tumorigenesis. In support of these observations, the heparanase inhibitor PG545 potently suppressed tumor progression in this model system. Taken together, our findings establish that heparanase exerts protumorigenic properties at early stages of tumor initiation, cooperating with Ras to dramatically promote malignant development.

DNA methylation of heparanase promoter influences its expression and associated with the progression of human breast cancer

Heparanase promotes tumor invasion and metastasis in several malignancies including breast cancer. However, the roles and regulation mechanisms of heparanase during breast cancer progression are still not fully understood. The aim of this study is to determine the differential regulation of heparanase gene expression in specific stages of breast cancer by DNA methylation. We detected levels of heparanase expression and DNA methylation patterns of its promoter in breast cancer cell lines (MCF-7 and MDA-MB-435) and clinical tissues, respectively. It has been observed that heparanase is highly expressed in the invasive MDA-MB-435 cells with low methylation modification in the heparanase promoter. In contrast, lower expression of heparanase in MCF-7 cells is accompanied by higher methylation in the promoter. Treatment of MCF-7 cells with 5-aza-2'-deoxycytidine (5-aza-dC), a potent demethylating agent, results in induction of heparanase expression and higher invasion potential in vitro and leads to an advantage of tumor formation in vivo. In 54 tissue samples, cancer samples at late stages (stage IV) showed the highest heparanase expression accomplished by little DNA methylation. On the contrary, methylation prevalence is highest in normal tissue and inversely correlated with heparanase expression. A significant correlation between DNA methylation and clinical stage was demonstrated (p = 0.012). Collectively, these results demonstrate that DNA methylation play the regulation role in heparanase gene in different stages of breast cancer and present a direct effect on tumor progression.

Neuroendocrine tumors show altered expression of chondroitin sulfate, glypican 1, glypican 5, and syndecan 2 depending on their differentiation grade

Neuroendocrine tumors (NETs) are found throughout the body and are important as they give rise to distinct clinical syndromes. Glycosaminoglycans, in proteoglycan (PG) form or as free chains, play vital roles in every step of tumor progression. Analyzing tumor samples with different degrees of histological differentiation we determined the existence of important alterations in chondroitin sulfate (CS) chains. Analysis of the transcription of the genes responsible for the production of CS showed a decline in the expression of some genes in poorly differentiated compared to well-differentiated tumors. Using anti-CS antibodies, normal stroma was always negative whereas tumoral stroma always showed a positive staining, more intense in the highest grade carcinomas, while tumor cells were negative. Moreover, certain specific cell surface PGs experienced a drastic decrease in expression depending on tumor differentiation. Syndecan 2 levels were very low or undetectable in healthy tissues, increasing significantly in well-differentiated tumors, and decreasing in poorly differentiated NETs, and its expression levels showed a positive correlation with patient survival. Glypican 5 appeared overexpressed in high-grade tumors with epithelial differentiation, and not in those that displayed a neuroendocrine phenotype. In contrast, normal neuroendocrine cells were positive for glypican 1, displaying intense staining in cytoplasm and membrane. Low-grade NETs had increased expression of this PG, but this reduced as tumor grade increased, its expression correlating positively with patient survival. Whilst elevated glypican 1 expression has been documented in different tumors, the downregulation in high-grade tumors observed in this work suggests that this proteoglycan could be involved in cancer development in a more complex and context-dependent manner than previously thought.

Specific genes involved in synthesis and editing of heparan sulfate proteoglycans show altered expression patterns in breast cancer

BACKGROUND

The expression of a specific set of genes controls the different structures of heparan sulfate proteoglycans (HSPGs), which are involved in the growth, invasion and metastatic properties of cancerous cells. The purpose of this study is to increase knowledge of HSPG alterations in breast cancer.

METHODS

Twenty-three infiltrating ductal adenocarcinomas (IDCs), both metastatic and non-metastatic were studied. A transcriptomic approach to the structure of heparan sulfate (HS) chains was used, employing qPCR to analyze both the expression of the enzymes involved in their biosynthesis and editing, as well as the proteoglycan core proteins. Since some of these proteoglycans can also carry chondroitin sulfate chains, we extended the study to include the genes involved in the biosynthesis of these glycosaminoglycans. Histochemical techniques were also used to analyze tissular expression of particular genes showing significant expression differences, of potential interest.

RESULTS

No significant change in transcription was detected in approximately 70% of analyzed genes. However, 13 demonstrated changes in both tumor types (40% showing more intense deregulation in the metastatic), while 5 genes showed changes only in non-metastatic tumors. Changes were related to 3 core proteins: overexpression of syndecan-1 and underexpression of glypican-3 and perlecan. HS synthesis was affected by lower levels of some 3-O-sulfotransferase transcripts, the expression of NDST4 and, only in non metastatic tumors, higher levels of extracellular sulfatases. Furthermore, the expression of chondroitin sulfate also was considerably affected, involving both the synthesis of the saccharidic chains and sulfations at all locations. However, the pro-metastatic enzyme heparanase did not exhibit significant changes in mRNA expression, although in metastatic tumors it appeared related to increased levels of the most stable form of mRNA. Finally, the expression of heparanase 2, which displays anti-metastatic features, experienced a strong deregulation in all patients analyzed.

CONCLUSIONS

IDCs show alterations in the expression of HSPG genes; principally the expression and localization of proteoglycans and the sulfation patterns of glycosaminoglycan chains, depending on the metastatic nature of the tumor. In addition, the anti-proliferative molecule heparanase 2 experiences strong deregulation, thus highlighting it as a potentially interesting diagnostic factor.

Two promoters with distinct activities in different tissues drive the expression of heparanase in Xenopus

In Xenopus laevis embryos, heparanase, the enzyme that degrades heparan sulfate, is synthesized as a preproheparanase (XHpaL) and processed to become enzymatically active (XHpa active). A short nonenzymatic heparanase splice variant (XHpaS) is also expressed. Using immunohistochemistry, Western blot, and heparanase promoter analysis, we studied the dynamic developmental expression of the three heparanases. Our results indicate that (1) all three isoforms are maternally expressed; (2) XHpaS is a developmental variant; (3) in the early embryo, heparanase is localized to both the plasma membrane and the nucleus; (4) several tissues express heparanase, but expression in the developing nervous system is most evident; (5) two promoters with distinct activities in different tissues drive heparanase expression; (6) Oct binding transcription factors may modulate heparanase promoter activity in the early embryo. These data argue that heparanase is expressed widely during development, but localization and levels are finely regulated.

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.