Impact of heparanase and the tumor microenvironment on cancer metastasis and angiogenesis: basic aspects and clinical applications

A Marine λ-Oligocarrageenan Inhibits Migratory and Invasive Ability of MDA-MB-231 Human Breast Cancer Cells through Actions on Heparanase Metabolism and MMP-14/MMP-2 Axis

Sugar-based molecules such as heparins or natural heparan sulfate polysaccharides have been developed and widely studied for controlling heparanase (HPSE) enzymatic activity, a key player in extracellular matrix remodelling during cancer pathogenesis. However, non-enzymatic functions of HPSE have also been described in tumour mechanisms. Given their versatile properties, we hypothesized that sugar-based inhibitors may interfere with enzymatic but also non-enzymatic HPSE activities. In this work, we assessed the effects of an original marine λ-carrageenan derived oligosaccharide (λ-CO) we previously described, along with those of its native counterpart and heparins, on cell viability, proliferation, migration, and invasion of MDA-MB-231 breast cancer cells but also of sh-MDA-MB-231 cells, in which the expression of HPSE was selectively downregulated. We observed no cytotoxic and no anti-proliferative effects of our compounds but surprisingly λ-CO was the most efficient to reduce cell migration and invasion compared with heparins, and in a HPSE-dependent manner. We provided evidence that λ-CO tightly controlled a HPSE/MMP-14/MMP-2 axis, leading to reduced MMP-2 activity. Altogether, this study highlights λ-CO as a potent HPSE “modulator” capable of reducing not only the enzymatic activity of HPSE but also the functions controlled by the HPSE levels.

Heparanase overexpression impedes perivascular clearance of amyloid-β from murine brain: relevance to Alzheimer's disease

Defective amyloid-β (Aβ) clearance from the brain is a major contributing factor to the pathophysiology of Alzheimer's disease (AD). Aβ clearance is mediated by macrophages, enzymatic degradation, perivascular drainage along the vascular basement membrane (VBM) and transcytosis across the blood-brain barrier (BBB). AD pathology is typically associated with cerebral amyloid angiopathy due to perivascular accumulation of Aβ. Heparan sulfate (HS) is an important component of the VBM, thought to fulfill multiple roles in AD pathology. We previously showed that macrophage-mediated clearance of intracortically injected Aβ was impaired in the brains of transgenic mice overexpressing heparanase (Hpa-tg). This study revealed that perivascular drainage was impeded in the Hpa-tg brain, evidenced by perivascular accumulation of the injected Aβ in the thalamus of Hpa-tg mice. Furthermore, endogenous Aβ accumulated at the perivasculature of Hpa-tg thalamus, but not in control thalamus. This perivascular clearance defect was confirmed following intracortical injection of dextran that was largely retained in the perivasculature of Hpa-tg brains, compared to control brains. Hpa-tg brains presented with thicker VBMs and swollen perivascular astrocyte endfeet, as well as elevated expression of the BBB-associated water-pump protein aquaporin 4 (AQP4). Elevated levels of both heparanase and AQP4 were also detected in human AD brain. These findings indicate that elevated heparanase levels alter the organization and composition of the BBB, likely through increased fragmentation of BBB-associated HS, resulting in defective perivascular drainage. This defect contributes to perivascular accumulation of Aβ in the Hpa-tg brain, highlighting a potential role for heparanase in the pathogenesis of AD.

Development of Molecules Antagonizing Heparan Sulfate Proteoglycans

Heparan sulfate proteoglycans (HSPGs) occur in almost every tissue of the human body and consist of a protein core, with covalently attached glycosaminoglycan polysaccharide chains. These glycosaminoglycans are characterized by their polyanionic nature, due to sulfate and carboxyl groups, which are distributed along the chain. These chains can be modified by different enzymes at varying positions, which leads to huge diversity of possible structures with the complexity further increased by varying chain lengths. According to their location, HSPGs are divided into different families, the membrane bound, the secreted extracellular matrix, and the secretory vesicle family. As members of the extracellular matrix, they take part in cell-cell communication processes on many levels and with different degrees of involvement. Of particular therapeutic interest is their role in cancer and inflammation as well as in infectious diseases. In this review, we give an overview of the current status of medical approaches to antagonize HSPG function in pathology.

Heparanome-Mediated Rescue of Oligodendrocyte Progenitor Quiescence following Inflammatory Demyelination

The proinflammatory cytokine IFN-γ, which is chronically elevated in multiple sclerosis, induces pathologic quiescence in human oligodendrocyte progenitor cells (OPCs) via upregulation of the transcription factor PRRX1. In this study using animals of both sexes, we investigated the role of heparan sulfate proteoglycans in the modulation of IFN-γ signaling following demyelination. We found that IFN-γ profoundly impaired OPC proliferation and recruitment following adult spinal cord demyelination. IFN-γ-induced quiescence was mediated by direct signaling in OPCs as conditional genetic ablation of IFNγR1 (Ifngr1) in adult NG2⁺ OPCs completely abrogated these inhibitory effects. Intriguingly, OPC-specific IFN-γ signaling contributed to failed oligodendrocyte differentiation, which was associated with hyperactive Wnt/Bmp target gene expression in OPCs. We found that PI-88, a heparan sulfate mimetic, directly antagonized IFN-γ to rescue human OPC proliferation and differentiation in vitro and blocked the IFN-γ-mediated inhibitory effects on OPC recruitment in vivo Importantly, heparanase modulation by PI-88 or OGT2155 in demyelinated lesions rescued IFN-γ-mediated axonal damage and demyelination. In addition to OPC-specific effects, IFN-γ-augmented lesions were characterized by increased size, reactive astrogliosis, and proinflammatory microglial/macrophage activation along with exacerbated axonal injury and cell death. Heparanase inhibitor treatment rescued many of the negative IFN-γ-induced sequelae suggesting a profound modulation of the lesion environment. Together, these results suggest that the modulation of the heparanome represents a rational approach to mitigate the negative effects of proinflammatory signaling and rescuing pathologic quiescence in the inflamed and demyelinated human brain.SIGNIFICANCE STATEMENT The failure of remyelination in multiple sclerosis contributes to neurologic dysfunction and neurodegeneration. The activation and proliferation of oligodendrocyte progenitor cells (OPCs) is a necessary step in the recruitment phase of remyelination. Here, we show that the proinflammatory cytokine interferon-γ directly acts on OPCs to induce pathologic quiescence and thereby limit recruitment following demyelination. Heparan sulfate is a highly structured sulfated carbohydrate polymer that is present on the cell surface and regulates several aspects of the signaling microenvironment. We find that pathologic interferon-γ can be blocked by modulation of the heparanome following demyelination using either a heparan mimetic or by treatment with heparanase inhibitor. These studies establish the potential for modulation of heparanome as a regenerative approach in demyelinating disease.

miRNAs in Health and Disease: A Focus on the Breast Cancer Metastatic Cascade towards the Brain

MicroRNAs (miRNAs) are small non-coding RNAs that mainly act by binding to target genes to regulate their expression. Due to the multitude of genes regulated by miRNAs they have been subject of extensive research in the past few years. This state-of-the-art review summarizes the current knowledge about miRNAs and illustrates their role as powerful regulators of physiological processes. Moreover, it highlights their aberrant expression in disease, including specific cancer types and the differential hosting-metastases preferences that influence several steps of tumorigenesis. Considering the incidence of breast cancer and that the metastatic disease is presently the major cause of death in women, emphasis is put in the role of miRNAs in breast cancer and in the regulation of the different steps of the metastatic cascade. Furthermore, we depict their involvement in the cascade of events underlying breast cancer brain metastasis formation and development. Collectively, this review shall contribute to a better understanding of the uniqueness of the biologic roles of miRNAs in these processes, to the awareness of miRNAs as new and reliable biomarkers and/or of therapeutic targets, which can change the landscape of a poor prognosis and low survival rates condition of advanced breast cancer patients.

The Tumor Microenvironment: Focus on Extracellular Matrix

The extracellular matrix (ECM) regulates the development and maintains tissue homeostasis. The ECM is composed of a complex network of molecules presenting distinct biochemical properties to regulate cell growth, survival, motility, and differentiation. Among their components, proteoglycans (PGs) are considered one of the main components of ECM. Its composition, biomechanics, and anisotropy are exquisitely tuned to reflect the physiological state of the tissue. The loss of ECM's homeostasis is seen as one of the hallmarks of cancer and, typically, defines transitional events in tumor progression and metastasis. In this chapter, we discuss the types of proteoglycans and their roles in cancer. It has been observed that the amount of some ECM components is increased, while others are decreased, depending on the type of tumor. However, both conditions corroborate with tumor progression and malignancy. Therefore, ECM components have an increasingly important role in carcinogenesis and this leads us to believe that their understanding may be a key in the discovery of new anti-tumor therapies. In this book, the main ECM components will be discussed in more detail in each chapter.

Heparan Sulfate Mimetics in Cancer Therapy: The Challenge to Define Structural Determinants and the Relevance of Targets for Optimal Activity

Beyond anticoagulation, the therapeutic potential of heparin derivatives and heparan sulfate (HS) mimetics (functionally defined HS mimetics) in oncology is related to their ability to bind and modulate the function of a vast array of HS-binding proteins with pivotal roles in cancer growth and progression. The definition of structural/functional determinants and the introduction of chemical modifications enabled heparin derivatives to be identified with greatly reduced or absent anticoagulant activity, but conserved/enhanced anticancer activity. These studies paved the way for the disclosure of structural requirements for the inhibitory effects of HS mimetics on heparanase, selectins, and growth factor receptor signaling, as well as for the limitation of side effects. Actually, HS mimetics affect the tumor biological behavior via a multi-target mechanism of action based on their effects on tumor cells and various components of the tumor microenvironment. Emerging evidence indicates that immunomodulation can participate in the antitumor activity of these agents. Significant ability to enhance the antitumor effects of combination treatments with standard therapies was shown in several tumor models. While the first HS mimetics are undergoing early clinical evaluation, an improved understanding of the molecular contexts favoring the antitumor action in certain malignancies or subgroups is needed to fully exploit their potential.

Elevated heparanase expression is associated with poor prognosis in breast cancer: a study based on systematic review and TCGA data

Heparanase promotes tumorigenesis, angiogenesis, and metastasis. Here, we conducted a study based on systematic review and the Cancer Genome Atlas (TCGA) data that examined heparanase expression in clinical samples to determine its prognostic value. According to the meta-analysis and TCGA data, we found that heparanase expression was up-regulated in most breast cancer specimens, and elevated heparanase expression was associated with increased lymph node metastasis, larger tumor size, higher histological grade, and poor survival. These results suggest that targeting heparanase might improve treatments for breast cancer patients.

Antitumor efficacy of the heparan sulfate mimic roneparstat (SST0001) against sarcoma models involves multi-target inhibition of receptor tyrosine kinases

The heparan sulfate (HS) mimic/heparanase inhibitor roneparstat (SST0001) shows antitumor activity in preclinical sarcoma models. We hypothesized that this 100% N-acetylated and glycol-split heparin could interfere with the functions of several receptor tyrosine kinases (RTK) coexpressed in sarcomas and activated by heparin-binding growth factors. Using a phospho-proteomic approach, we investigated the drug effects on RTK activation in human cell lines representative of different sarcoma subtypes. Inhibition of FGF, IGF, ERBB and PDGF receptors by the drug was biochemically and functionally validated. Roneparstat counteracted the autocrine loop induced by the COL1A1/PDGFB fusion oncogene, expressed in a human dermatofibrosarcoma protuberans primary culture and in NIH3T3^COL1A1/PDGFB transfectants, inhibiting cell anchorage-independent growth and invasion. In addition, roneparstat inhibited the activation of cell surface PDGFR and PDGFR-associated FAK, likely contributing to the reversion of NIH3T3^COL1A1/PDGFB cell transformed and pro-invasive phenotype. Biochemical and histological/immunohistochemical ex vivo analyses confirmed a reduced activation of ERBB4, EGFR, INSR, IGF1R, associated with apoptosis induction and angiogenesis inhibition in a drug-treated Ewing's sarcoma family tumor xenograft. The combination of roneparstat with irinotecan significantly improved the antitumor effect against A204 rhabdoid xenografts resulting in a high rate of complete responses and cures. These findings reveal that roneparstat exerts a multi-target inhibition of RTKs relevant in the pathobiology of different sarcoma subtypes. These effects, likely cooperating with heparanase inhibition, contribute to the antitumor efficacy of the drug. The study supports heparanase/HS axis targeting as a valuable approach in combination therapies of different sarcoma subtypes providing a preclinical rationale for clinical investigation.

The prognostic significance of circulating serum amyloid A and CXC chemokine ligand 4 in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common pediatric bone cancer.  Despite advances in treatment regimens, the survival rate remains 60-70%.  There is an urgent need to identify prognostic biomarkers, so that targeted therapies can be developed to improve the outcome.

PROCEDURE

Our laboratory has previously identified that circulating serum amyloid A (SAA) and CXC chemokine ligand 4 (CXCL4) are upregulated in patients with OS.  In this study, we tested if they could be used as prognostic biomarkers.  We used enzyme-linked immunosorbent assays to measure their concentrations in serum samples (n = 233) and immunohistochemistry to examine their expressions in primary tumors (n = 37).  Prognostic significance of the serum concentrations and tumor expressions of the biomarkers was then evaluated.

RESULTS

Patients with "high SAA" and "low CXCL4" circulating levels at diagnosis significantly correlated with a worse outcome (HR = 1.68, P = 0.014), which was independent of the metastatic status.  These patients also exhibited a significantly higher rate of poor histologic response to chemotherapy.  Furthermore, low tumor expression of CXCL4 correlated with poor survival (HR = 3.57, P = 0.005).

CONCLUSIONS

Our results demonstrate that circulating SAA and CXCL4 may serve as prognostic biomarkers in OS.  Targeting CXCL4 has been reported, suggesting that it may be exploited as a therapeutic target in OS.

Gubenyiliu II Inhibits Breast Tumor Growth and Metastasis Associated with Decreased Heparanase Expression and Phosphorylation of ERK and AKT Pathways

Gubenyiliu II (GYII), a Traditional Chinese Medicine (TCM) formula used in our hospital, has shown beneficial effects in cancer patients. In this study, we investigated the molecular mechanisms underlying the beneficial effects of GYII on murine breast cancer models. GYII showed significant inhibitory effects on tumor growth and metastasis in the murine breast cancer model. Additionally, GYII suppressed the proliferation of 4T1 and MCF-7 cells in a dose-dependent manner. A better inhibitory effect on 4T1 cell proliferation and migration was found in the decomposed recipes (DR) of GYII. Moreover, heparanase expression and the degree of angiogenesis were reduced in tumor tissues. Western blot analysis showed decreased expression of heparanase and growth factors in the cells treated with GYII and its decomposed recipes (DR2 and DR3), and thereby a reduction in the phosphorylation of extracellular signal-regulated kinase (ERK) and serine-threonine kinase (AKT). These results suggest that GYII exerts anti-tumor growth and anti-metastatic effects in the murine breast cancer model. The anti-tumor activity of GYII and its decomposed recipes is, at least partly, associated with decreased heparanase and growth factor expression, which subsequently suppressed the activation of the ERK and AKT pathways.

New Applications of Heparin and Other Glycosaminoglycans

Heparin, the widely used pharmaceutical anticoagulant, has been in clinical use for well over half a century. Its introduction reduced clotting risks substantially and subsequent developments, including the introduction of low-molecular-weight heparin, made possible many major surgical interventions that today make heparin an indispensable drug. There has been a recent burgeoning of interest in heparin and related glycosaminoglycan (GAG) polysaccharides, such as chondroitin sulfates, heparan sulfate, and hyaluronate, as potential agents in various applications. This ability arises mainly from the ability of GAGs to interact with, and alter the activity of, a wide range of proteins. Here, we review new developments (since 2010) in the application of heparin and related GAGs across diverse fields ranging from thrombosis and neurodegenerative disorders to microbiology and biotechnology.

Leptomeningeal metastasis of poorly differentiated uterine cervical adenosquamous carcinoma following reirradiation to metastatic vertebrae: A case report

RATIONALE

Leptomeningeal metastasis from cervical adenosquamous carcinoma is extremely rare especially after radiotherapy for vertebral metastasis.

PATIENT CONCERNS

A 52-year-old woman with International Federation of Gynecology and Obstetrics (FIGO) stage IIB adenosquamous carcinoma of cervix presented with bilateral lower limbs weakening after 2 courses radiotherapy to thoracic vertebral metastases.

DIAGNOSES

Initial spine magnetic resonance imaging (MRI) showed no obvious nerve compression, and radiation myelopathy was suspected by the clinician. Progressive multifocal neurological signs developed one month after completion of spine re-irradiation. She was diagnosed with leptomeningeal metastasis by MRI and cerebrospinal fluid (CSF) study.

INTERVENTIONS

She received whole brain irradiation with a dose of 30 Gy in 10 fractions. Systemic chemotherapy with cisplatin (50 mg/m) and topotecan (0.75 mg/m) was administered sequentially.

OUTCOMES

She died with progressive disease two months after the diagnosis of leptomeningeal metastases.

LESSONS

Poorly differentiated advanced-stage cervical adenosquamous carcinoma is an aggressive neoplasm with a worse outcome. Leptomeningeal metastasis should be included in the differential diagnosis for patients with multifocal craniospinal neurological signs. A combination of detailed neurological examinations, MRI and CSF study allowed us to establish a correct diagnosis of leptomeningeal metastasis and initiate treatment in a timely manner.

Significance of heparanase in metastatic lymph nodes of cervical squamous cell cancer

The aim of this study was to explore the expression of heparanase (HPA) in metastatic lymph nodes (LNs) of cervical cancer and to evaluate HPA as a marker of micro-metastasis of LNs. Immunohistochemistry was performed to detect the expression of HPA in 53 cases with metastasis of LNs (group A) and 49 cases without (group B). Scoring was determined based on the intensity of immunostaining and the size of the staining area. Three points or higher score was considered as positive. Among all cases, the positive rate of HPA was 76.5% in primary lesions and 84.9% in both primary lesions and metastatic LNs in group A. In group B, the rates were 67.3% in primary lesions and 8.2% in metastatic LNs. The expression of HPA in group A was significantly higher than that in group B (P<0.05). Compared with stage IA-IB and well-differentiated and non-metastatic LNs, the LNs of stage IIA and moderately/poorly differentiated and metastatic LNs expressed higher HPA (P<0.05). The overall 5-year survival rate was 73.3% and the median overall survival time (MOS) was 49.0 months. The MOS of the two groups was 36.0 and 58.5 months, respectively (P=0.023); the MOS of patients with positive HPA expression was distinctly lower than that of negative patients (P=0.040). Clinical staging, degree of differentiation, lymph node metastasis and expression of HPA notably affected patient prognosis; lymph node metastasis and expression of HPA were independent risk factors affecting patient prognosis (P<0.05). Our study demonstrated that high-level expression of HPA in cervical cancer was involved in LN metastasis, further impacting on patients' long-term survival. The clinical value of HPA requires further in-depth study.

Normal Wound Healing and Tumor Angiogenesis as a Game of Competitive Inhibition

Both normal wound healing and tumor angiogenesis are mitigated by the sequential, carefully orchestrated release of growth stimulators and inhibitors. These regulators are released from platelet clots formed at the sites of activated endothelium in a temporally and spatially controlled manner, and the order of their release depends on their affinity to glycosaminoglycans (GAG) such as heparan sulfate (HS) within the extracellular matrix, and platelet open canallicular system. The formation of vessel sprouts, triggered by angiogenesis regulating factors with lowest affinities for heparan sulfate (e.g. VEGF), is followed by vessel-stabilizing PDGF-B or bFGF with medium affinity for HS, and by inhibitors such as PF-4 and TSP-1 with the highest affinities for HS. The invasive wound-like edge of growing tumors has an overabundance of angiogenesis stimulators, and we propose that their abundance out-competes angiogenesis inhibitors, effectively preventing inhibition of angiogenesis and vessel maturation. We evaluate this hypothesis using an experimentally motivated agent-based model, and propose a general theoretical framework for understanding mechanistic similarities and differences between the processes of normal wound healing and pathological angiogenesis from the point of view of competitive inhibition.

Pharmacology of Heparin and Related Drugs

Heparin has been recognized as a valuable anticoagulant and antithrombotic for several decades and is still widely used in clinical practice for a variety of indications. The anticoagulant activity of heparin is mainly attributable to the action of a specific pentasaccharide sequence that acts in concert with antithrombin, a plasma coagulation factor inhibitor. This observation has led to the development of synthetic heparin mimetics for clinical use. However, it is increasingly recognized that heparin has many other pharmacological properties, including but not limited to antiviral, anti-inflammatory, and antimetastatic actions. Many of these activities are independent of its anticoagulant activity, although the mechanisms of these other activities are currently less well defined. Nonetheless, heparin is being exploited for clinical uses beyond anticoagulation and developed for a wide range of clinical disorders. This article provides a "state of the art" review of our current understanding of the pharmacology of heparin and related drugs and an overview of the status of development of such drugs.

Heparanase Activates Antithrombin through the Binding to Its Heparin Binding Site

Heparanase is an endoglycosidase that participates in morphogenesis, tissue repair, heparan sulphates turnover and immune response processes. It is over-expressed in tumor cells favoring the metastasis as it penetrates the endothelial layer that lines blood vessels and facilitates the metastasis by degradation of heparan sulphate proteoglycans of the extracellular matrix. Heparanase may also affect the hemostatic system in a non-enzymatic manner, up-regulating the expression of tissue factor, which is the initiator of blood coagulation, and dissociating tissue factor pathway inhibitor on the cell surface membrane of endothelial and tumor cells, thus resulting in a procoagulant state. Trying to check the effect of heparanase on heparin, a highly sulphated glycosaminoglycan, when it activates antithrombin, our results demonstrated that heparanase, but not proheparanase, interacted directly with antithrombin in a non-covalent manner. This interaction resulted in the activation of antithrombin, which is the most important endogenous anticoagulant. This activation mainly accelerated FXa inhibition, supporting an allosteric activation effect. Heparanase bound to the heparin binding site of antithrombin as the activation of Pro41Leu, Arg47Cys, Lys114Ala and Lys125Alaantithrombin mutants was impaired when it was compared to wild type antithrombin. Intrinsic fluorescence analysis showed that heparanase induced an activating conformational change in antithrombin similar to that induced by heparin and with a KD of 18.81 pM. In conclusion, under physiological pH and low levels of tissue factor, heparanase may exert a non-enzymatic function interacting and activating the inhibitory function of antithrombin.

FGF23 is elevated in multiple myeloma and increases heparanase expression by tumor cells

Multiply myeloma (MM) grows in and destroys bone, where osteocytes secrete FGF23, a hormone which affects phosphate homeostasis and aging. We report that multiple myeloma (MM) cells express receptors for and respond to FGF23. FGF23 increased mRNA for EGR1 and its target heparanase, a pro-osteolytic factor in MM. FGF23 signals through a complex of klotho and a classical FGF receptor (FGFR); both were expressed by MM cell lines and patient samples. Bone marrow plasma cells from 42 MM patients stained positively for klotho, while plasma cells from 8 patients with monoclonal gammopathy of undetermined significance (MGUS) and 6 controls were negative. Intact, active FGF23 was increased 2.9X in sera of MM patients compared to controls. FGF23 was not expressed by human MM cells, but co-culture with mouse bone increased its mRNA. The FGFR inhibitor NVP-BGJ398 blocked the heparanase response to FGF23. NVP-BGJ398 did not inhibit 8226 growth in vitro but significantly suppressed growth in bone and induction of the osteoclast regulator RANK ligand, while decreasing heparanase mRNA. The bone microenvironment provides resistance to some anti-tumor drugs but increased the activity of NVP-BGJ398 against 8226 cells. The FGF23/klotho/heparanase signaling axis may offer targets for treatment of MM in bone.

The Role of Heparanase and Sulfatases in the Modification of Heparan Sulfate Proteoglycans within the Tumor Microenvironment and Opportunities for Novel Cancer Therapeutics

Heparan sulfate proteoglycans (HSPGs) are an integral and dynamic part of normal tissue architecture at the cell surface and within the extracellular matrix. The modification of HSPGs in the tumor microenvironment is known to result not just in structural but also functional consequences, which significantly impact cancer progression. As substrates for the key enzymes sulfatases and heparanase, the modification of HSPGs is typically characterized by the degradation of heparan sulfate (HS) chains/sulfation patterns via the endo-6-O-sulfatases (Sulf1 and Sulf2) or by heparanase, an endo-glycosidase that cleaves the HS polymers releasing smaller fragments from HSPG complexes. Numerous studies have demonstrated how these enzymes actively influence cancer cell proliferation, signaling, invasion, and metastasis. The activity or expression of these enzymes has been reported to be modified in a variety of cancers. Such observations are consistent with the degradation of normal architecture and basement membranes, which are typically compromised in metastatic disease. Moreover, recent studies elucidating the requirements for these proteins in tumor initiation and progression exemplify their importance in the development and progression of cancer. Thus, as the influence of the tumor microenvironment in cancer progression becomes more apparent, the focus on targeting enzymes that degrade HSPGs highlights one approach to maintain normal tissue architecture, inhibit tumor progression, and block metastasis. This review discusses the role of these enzymes in the context of the tumor microenvironment and their promise as therapeutic targets for the treatment of cancer.

The motile breast cancer phenotype roles of proteoglycans/glycosaminoglycans

The consecutive stages of cancer growth and dissemination are obligatorily perpetrated through specific interactions of the tumor cells with their microenvironment. Importantly, cell-associated and tumor microenvironment glycosaminoglycans (GAGs)/proteoglycan (PG) content and distribution are markedly altered during tumor pathogenesis and progression. GAGs and PGs perform multiple functions in specific stages of the metastatic cascade due to their defined structure and ability to interact with both ligands and receptors regulating cancer pathogenesis. Thus, GAGs/PGs may modulate downstream signaling of key cellular mediators including insulin growth factor receptor (IGFR), epidermal growth factor receptor (EGFR), estrogen receptors (ERs), or Wnt members. In the present review we will focus on breast cancer motility in correlation with their GAG/PG content and critically discuss mechanisms involved. Furthermore, new approaches involving GAGs/PGs as potential prognostic/diagnostic markers or as therapeutic agents for cancer-related pathologies are being proposed.

Heparanase expression and localization in different types of human lung cancer

BACKGROUND

Heparanase is the only known mammalian glycosidase capable of cleaving heparan sulfate chains. The expression of this enzyme has been associated with tumor development because of its ability to degrade extracellular matrix and promote cell invasion.

METHODS

We analyzed heparanase expression in lung cancer samples to understand lung tumor progression and malignancy. Of the samples from 37 patients, there were 14 adenocarcinomas, 13 squamous cell carcinomas, 5 large cell carcinomas, and 5 small cell carcinomas. Immunohistochemistry was performed to ascertain the expression and localization of heparanase.

RESULTS

All of the tumor types expressed heparanase, which was predominantly localized within the cytoplasm and nucleus. Significant enzyme expression was also observed in cells within the tumor microenvironment, such as fibroblasts, epithelial cells, and inflammatory cells. Adenocarcinomas exhibited the strongest heparanase staining intensity and the most widespread heparanase distribution. Squamous cell carcinomas, large cell carcinomas, and small cell carcinomas had a similar subcellular distribution of heparanase to adenocarcinomas but the distribution was less widespread. Heparanase expression tended to correlate with tumor node metastasis (TNM) staging in non-small cell lung carcinoma.

CONCLUSION

In this study, we showed that heparanase was localized to the cytoplasm and nucleus of tumor cells and to cells within the microenvironment in different types of lung cancer. This enzyme exhibited a differential distribution based on the type of lung tumor. General significance Elucidating the heparanase expression patterns in different types of lung cancer increased our understanding of the crucial role of heparanase in lung cancer biology. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Heparan sulfate and heparanase as modulators of breast cancer progression

Breast cancer is defined as a cancer originating in tissues of the breast, frequently in ducts and lobules. During the last 30 years, studies to understand the biology and to treat breast tumor improved patients' survival rates. These studies have focused on genetic components involved in tumor progression and on tumor microenvironment. Heparan sulfate proteoglycans (HSPGs) are involved in cell signaling, adhesion, extracellular matrix assembly, and growth factors storage. As a central molecule, HSPG regulates cell behavior and tumor progression. HS accompanied by its glycosaminoglycan counterparts regulates tissue homeostasis and cancer development. These molecules present opposite effects according to tumor type or cancer model. Studies in this area may contribute to unveil glycosaminoglycan activities on cell dynamics during breast cancer exploring these polysaccharides as antitumor agents. Heparanase is a potent tumor modulator due to its protumorigenic, proangiogenic, and prometastatic activities. Several lines of evidence indicate that heparanase is upregulated in all human sarcomas and carcinomas. Heparanase seems to be related to several aspects regulating the potential of breast cancer metastasis. Due to its multiple roles, heparanase is seen as a target in cancer treatment. We will describe recent findings on the function of HSPGs and heparanase in breast cancer behavior and progression.