Heparanase promotes bone destruction and invasiveness in prostate cancer

Heparanase is an endoglycosidase that plays an important role in angiogenesis and metastasis of cancer. Herein we evaluate the effect of heparanase overexpression on invasiveness and bone destruction in prostate cancer bone metastases. The human prostate cancer cell line PC-3 was stably transfected with a plasmid containing the cDNA for human heparanase or with the vector alone as a control. Overexpression of heparanase did not affect the growth of PC-3 cells, but did promote invasiveness of the cells in an in vitro assay. Both cell types were injected into the tibias of nude mice. Four weeks later, the mice were examined radiologically prior to sacrifice and samples of leg tissue were taken to investigate bone destruction and metastasis. Mice injected with PC-3 cells overexpressing heparanase had more severe bone destruction and larger, more invasive, tumors. These results demonstrate that heparanase overexpression can facilitate tumor invasion and accelerate bone destruction caused by prostate cancer bone metastasis.     

The role of platelet activation in tumor metastasis

Platelets are highly reactive components of the circulatory system, which exert not only haemostatic activity but also contribute to the modulation of various pathological conditions including inflammation, atherosclerosis and cancer metastasis through the release of cytokines, chemokines and the presentation of several adhesion molecules. During cancer metastasis, the formation of platelet–tumor cell aggregates in the circulation facilitates immune evasion and the microvascular arrest of tumor cells at distant sites. Several adhesion molecules, such as integrins and glycoproteins, were shown to be involved in this process. Recent findings indicate that P-selectin is another main mediator of platelet–tumor cell interactions. Other effects of activated platelets on cancer progression are associated with a release of platelet-derived factors stimulating tumor growth and angiogenesis. Any interference in platelet–tumor cell interactions resulted in attenuation of cancer metastasis. The well recognized, albeit not fully characterized function of platelets during cancer progression defines platelets as potential targets for cancer therapy. Specifically, the rapid expression of P-selectin on the cell surface of activated platelets and its strong association with metastasis provide a rationale for P-selectin inhibition as an antimetastatic treatment.     

The role of platelet activation in tumor metastasis

Platelets are highly reactive components of the circulatory system, which exert not only haemostatic activity but also contribute to the modulation of various pathological conditions including inflammation, atherosclerosis and cancer metastasis through the release of cytokines, chemokines and the presentation of several adhesion molecules. During cancer metastasis, the formation of platelet-tumor cell aggregates in the circulation facilitates immune evasion and the microvascular arrest of tumor cells at distant sites. Several adhesion molecules, such as integrins and glycoproteins, were shown to be involved in this process. Recent findings indicate that P-selectin is another main mediator of platelet-tumor cell interactions. Other effects of activated platelets on cancer progression are associated with a release of platelet-derived factors stimulating tumor growth and angiogenesis. Any interference in platelet-tumor cell interactions resulted in attenuation of cancer metastasis. The well recognized, albeit not fully characterized function of platelets during cancer progression defines platelets as potential targets for cancer therapy. Specifically, the rapid expression of P-selectin on the cell surface of activated platelets and its strong association with metastasis provide a rationale for P-selectin inhibition as an antimetastatic treatment.     

Heparanase induces VEGF C and facilitates tumor lymphangiogenesis

Heparanase is an endoglycosidase that specifically cleaves heparan sulfate side chains, a class of glycosaminoglycans abundantly present in the extracellular matrix and on the cell surface. Heparanase activity is strongly implicated in tumor angiogenesis and metastasis attributed to remodeling of the subepithelial and subendothelial basement membranes. We hypothesized that similar to its proangiogenic capacity, heparanase is also engaged in lymphangiogenesis and utilized the D2-40 monoclonal antibody to study lymphangiogenesis in tumor specimens obtained from 65 head and neck carcinoma patients. Lymphatic density was analyzed for association with clinical parameters and heparanase staining. We provide evidence that lymphatic vessel density (LVD) correlates with head and neck lymph node metastasis (N-stage, p = 0.007) and inversely correlates with tumor cell differentiation (p = 0.007). Notably, heparanase staining correlated with LVD (p = 0.04) and, moreover, with VEGF C levels (p = 0.01). We further demonstrate that heparanase overexpression by epidermoid, breast, melanoma and prostate carcinoma cells induces a 3- to 5-fold elevation in VEGF C expression in vitro and facilitates tumor xenograft lymphangiogenesis in vivo, whereas heparanase gene silencing was associated with decreased VEGF C levels. These findings suggest that heparanase plays a unique dual role in tumor metastasis, facilitating tumor cell invasiveness and inducing VEGF C expression, thereby increasing the density of lymphatic vessels that mobilize metastatic cells.     

Expression of heparanase by platelets and circulating cells of the immune system: possible involvement in diapedesis and extravasation.

Interaction of T and B lymphocytes, platelets, granulocytes, macrophages and mast cells with the subendothelial extracellular matrix (ECM) is associated with degradation of heparan sulfate (HS) by a specific endoglycosidase (heparanase) activity. The enzyme is released from intracellular compartments (i.e., lysosomes, specific granules) in response to various activation signals (i.e., thrombin, calcium ionophore, immune complexes, antigens, mitogens), suggesting its regulated involvement in inflammation and cellular immunity. In contrast, various tumor cells appear to express and secrete heparanase in a constitutive manner, in correlation with their metastatic potential. Heparanase enzymes produced by different cell types may exhibit different molecular properties and substrate cleavage specificities. The platelet enzyme appears also in a latent form. It can be activated by tumor cells and thereby facilitate their extravasation in the process of metastasis. Degradation of ECM-HS by all cell types was facilitated by a proteolytic activity residing in the ECM and/or expressed by the invading cells. This proteolytic activity produced a more accessible substrate for the heparanase enzymes. Heparanase-inhibiting, nonanticoagulant species of heparin markedly reduced the incidence of lung metastasis in experimental animals. These species of heparin also significantly impaired the traffic of T lymphocytes and suppressed cellular immune reactivity and experimental autoimmune diseases. Heparanase activity expressed by intact cells (i.e., platelets, mast cells, neutrophils, lymphoma cells) was found to release active HS-bound basic fibroblast growth factor from ECM and basement membranes. Heparanase may thus elicit an indirect neovascular response in processes such as wound repair, inflammation and tumor development. The significant anticancerous effect of heparanase-inhibiting molecules may therefore be attributed to their potential inhibition of both tumor invasion and angiogenesis. Both normal leukocytic cells and metastatic tumor cells can enter the bloodstream, travel to distant sites and extravasate to the parenchyma at these sites. We suggest that heparanase is utilized for this purpose by both types of cells. Other functions (i.e., enzyme activities, adhesive interactions, chemotactic and proliferative responses) of metastatic tumor cells seem to mimic the equivalent functions of leukocytes as they migrate across blood vessels to gain access to sites of inflammation.     

Heparan sulfate endoglycosidase and metastatic potential in murine fibrosarcoma and melanoma

Several fibroblast and melanoma cell lines were studied with respect to their ability to degrade heparan sulfate (HS). The optimum pH for HS degradation by HS endoglycosidase (heparanase) for all cell lines is about 5.6, but the activity of the enzyme is still present at physiological pH. The gel permeation analysis of degradation products revealed that heparanase cuts HS in fragments about one-seventh of their original size. Since the optimum pH of HS endoglycosidase activity and the terminal molecular weight of degraded HS are the same in both cell lines, it is likely that fibrosarcoma and melanoma heparanases are identical enzymes. Cell extracts and intact cells of metastatic sublines degrade HS faster than do their nonmetastatic counterparts. The degradative activity of intact cells parallels those of cell extracts, but at a much lower level; moreover, conditioned media do not appreciably degrade HS, suggesting that heparanase is scarcely released into the medium; thus, considering the differences in degradative activity between cell extracts and intact cells or conditioned medium and the occurrence of cell lysis in a tumor in vivo, we suggest that the measure of degradative activity of intact cells in vitro is not indicative of a relationship to metastasis. The total cellular content of lytic enzymes could represent the real metastatic potential of proliferating cells, but it is also necessary to find an in vitro model better representing the behavior of neoplastic cells in vivo.     

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.     

Inhibition of heparanase activity and tumor metastasis by laminarin sulfate and synthetic phosphorothioate oligodeoxynucleotides.

Heparanase activity correlates with the metastatic potential of tumor cells. Moreover, the anti-metastatic effect of non-anti-coagulant species of heparin and certain sulfated polysaccharides was attributed to their heparanase-inhibiting activity. We investigated the effect of a chemically sulfated polysaccharide (laminarin), consisting primarily of beta-1,3 glucan (sodium laminarin), and of synthetic phosphorothioate oligodeoxynucleotides, primarily phosphorothioate homopolymer of cytidine (SdC28), on heparanase activity and tumor metastasis. Investigation of the ability of tumor cells to degrade heparan sulfate in intact extracellular matrix revealed that heparanase activity expressed by B16-BL6 mouse melanoma cells and 13762 MAT rat mammary adenocarcinoma cells was effectively inhibited by LS (50% inhibition at 0.2-1 microgram/ml), but there was no inhibition by sodium laminarin up to a concentration of 50 microgram/ml. Complete inhibition of the melanoma heparanase was obtained in the presence of 0.1 microM SdC28. A single i.p. injection of laminarin sulfate, but not of sodium laminarin, before i.v. inoculation of the melanoma or breast-carcinoma cells inhibited the extent of lung colonization by the tumor cells by 80 to 90%. Similar inhibition was exerted by 0.1 microM SdC28. At the effective concentrations, both compounds had a small effect on proliferation of the tumor cells and on growth of the primary tumors in vivo. These results further emphasize the involvement of heparanase in tumor metastasis and the potential clinical application of diverse heparanase-inhibiting molecules such as sulfated polysaccharides and synthetic polyanionic molecules.     

Cell detachment and metastasis

Cancer cell detachment in three distinct and critical parts of the metastatic cascade is discussed. The detachment of cancer cells from their parent tumors is an initial early event in metastasis. The site of detachment with respect to proximity to blood vessels may determine the initial dissemination route. Many factors affect cell detachment; we specifically consider the effects of growth-rate, necrosis, enzyme activity, and stress on cell release in terms of metastasis-promoting mechanisms. Detachment is also discussed in relation to active cancer cell locomotion, where localized detachment from the substratum is a prerequisite for translatory movement. The importance of active cell movement in tissue invasion has only recently been assessed, and, in the case of at least some human malignant melanomas, a zone of actively moving cancer cells is believed to precede the growing body of the tumor. The secondary release of cancer cells from temporary arrest sites at the vascular endothelium consequent upon intravascular dissemination is also a major area of investigation. Circulating cancer cells arrest at vascular endothelium or are impacted in small vessels, however, most are released into the circulation and subsequently perish. The blood stream is a hostile environment, and it is probable that cancer cells are sufficiently damaged in translocation by hemodynamic trauma and humoral factors such that they easily detach or are 'sheared-off' the vascular endothelium by blood flow. Another possibility is that in some cases they are processed by 'first organ encounters' and perish before or shortly after arriving in a second organ. Animal studies have shown that, following intravenous injection, 60-100% of the injected dose of viable cancer cells are initially arrested in the lungs, but very few remain after 24 hr. As it is only those retained cells which produce tumors, the mechanisms involved in this secondary release, which occurs in all organs so far examined, are critical to any understanding of the metastatic cascade and metastatic inefficiency. The arrest of cancer cells at the vascular endothelium and their subsequent release have been associated with the presence of platelets, and the deposition of fibrin and manipulation of platelet-aggregating mechanisms and fibrinolysis are discussed in terms of their antimetastatic effects. The role of the reticuloendothelial system, natural killer cells, and polymorphs is discussed in relation to cancer cell clearance from blood vessels and also to inherent cancer cell properties which may act to inhibit their metastasis. Although detachment of cancer cells from a primary tumor may be regarded as metastasis promoting, secondary release of cancer cells may be associated with inhibition of metastasis.     

乙酰肝素酶在乳腺癌侵袭转移中的作用及调控机制*

乙酰肝素酶（Heparanase ,HPSE）是目前发现的哺乳动物细胞中唯一能降解细胞外基质和基底膜中硫酸肝素蛋白多糖侧链—硫酸乙酰肝素的内源性糖苷酶,是目前抗肿瘤转移的理想靶点。HPSE在乳腺癌中常有高表达,并与肿瘤大小和淋巴结转移等密切相关。体外研究表明,乳腺癌细胞中HPSE启动子活性增高,转染HPSE的乳腺癌细胞在体内成瘤后,其肿瘤体积、重量、微血管密度以及癌细胞存活时间均明显高于阴性对照组。应用反义核酸技术或RNA干扰技术封闭或沉默HPSE基因表达后,乳腺癌细胞黏附和侵袭能力显著降低,表明HPSE在乳腺癌侵袭转移中发挥极其重要的作用。HPSE在乳腺癌侵袭转移中受多种机制调控,主要有:雌激素与其受体结合后作用于HPSE基因特定区域,从而提高HPSE转录活性,增强其基因和蛋白的表达;HPSE可使破骨细胞刺激因子产生增加,从而导致骨质溶解破坏,为乳腺癌骨转移奠定基础;HPSE诱导循环淋巴细胞产生刺激因子,从而促进乳腺癌的侵袭转移。此外,HPSE基因还受p53基因、ETS 基因、EGR 1 基因、PI-88因子、COX-2 等的调控。本文就HPSE在乳腺癌中的表达状况、在侵袭转移中的作用及调控机制进行综述。      

肝素酶基因表达与肺癌转移活性的初步研究

目的：探讨肝素酶基因表达与肺癌转移的关系。方法：应用肝素酶基因引物、逆转录聚合酶链反应技术（RT－PCR）检测肺巨细胞癌株和56例原发性肺癌及正常肺组织中肝素酶基因表达,结果：低转移和高转移的肺巨细胞癌株均为肝素酶基因表达阳性;已有淋巴转移的肺癌阳性率为80％（20／25）,而无淋巴结转移的肺癌阳性率为6．5％（2／31）,两组间差异有显著性（P＜0．001）。提示伴有淋巴结转移的病例肝素酶基因表达阳性率明显高于不伴转移者。肝素酶基因表达多见于鳞癌（P＜0．05）和低分化癌（P＜0．01）,亦提示肝素酶基因表达可能与组织学分型及分化程度有关。结论：初步结果显示肝素酶基因表达可能为肺癌细胞获得转移活性的可靠标志之一,其检测可用于辅助判断肺癌患者预后。     

The role of heparanase in gastrointestinal cancer (Review)

Heparanase is endoglycosidase that degrades heparan sulfate, the main polysaccharide constituent of the extracellular matrix and basement membrane. Heparanase has been thought to have an important role in the process of cancer invasion and metastasis. Recent studies have revealed that heparanase has multifunctional modulatory effects in the progression of cancer cells and the cell-to-extracellular matrix interaction. Our recent research has shown the important roles of heparanase in the progression of esophagus, stomach and colon cancer, and heparanase expression was closely related to the prognosis of gastrointestinal cancer. Therapies targeting heparanase may result in promising tactics in cancer therapies. Heparanase gene silencing and inhibiton of enzymatic activities have potential use as targets for anticancer drug development. Here, we reviewed the role of heparanase in gastrointestinal tract tumors.     

CCL19/CCR7 upregulates heparanase via specificity protein-1 (Sp1) to promote invasion of cell in lung cancer

CCL19/chemokine receptor 7 (CCR7) has been found to be associated with tumor growth, angiogenesis, invasion, and lymph node metastasis. Our previous study demonstrated that CCR7 overexpressed in non-small cell lung cancer (NSCLC) and had close relationship with tumor invasion and lymph node metastasis. However, the molecular mechanism of CCR7 promoting invasion of human NSCLC cells is still unclear. In this study, we demonstrated that human lung adenocarcinoma A549 cells treated with recombinant human CCL19 could obviously upregulate the expression of Sp1 and heparanase at both the mRNA and protein levels. After blockage of CCR7, Sp1 and heparanase expressions were inhibited. Following inhibition of Sp1, heparanase expression was downregulated. The analysis showed the promoter region of heparanase gene containing a number of potential sp1 binding sites (5′-GGGGC-3′). Chromatin immunoprecipitation analysis demonstrated that Sp1 could bind to the heparanase promoter. Cell invasion assays showed that the invasion ability of A549 cells was increased with CCL19 incubation compared to the control cells. These results suggested that CCL19/CCR7 may upregulate the expression of heparanase via Sp1 and contribute to the invasion of A549 cells.     

CD44 on LS174T colon carcinoma cells possesses E-selectin ligand activity

Metastasis of circulating tumor cells requires a multistep cascade of events initiated by adhesion of tumor cells to the vascular endothelium of involved tissues. This process occurs under the forces of blood flow and is promoted by adhesion molecules specialized to interact under shear conditions. The endothelial molecule E-selectin is a major mediator of these adhesive events, and there is strong evidence that E-selectin receptor-ligand interactions contribute to the formation of metastasis. However, little is known about the identity of E-selectin ligand(s) expressed on cancer cells. To address this issue, we did SDS-PAGE analysis of membrane proteins, metabolic inhibition studies, and blot rolling assays of LS174T, a colon carcinoma cell line known to interact with E-selectin under physiologic flow conditions. Our studies show that LS174T cells express the hematopoietic cell E/L-selectin (HCELL) glycoform of CD44, which functions as a high-affinity E-selectin glycoprotein ligand on these cells. However, in contrast to the HCELL glycoform on human hematopoietic progenitor cells, which expresses carbohydrate-binding determinant(s) for E-selectin primarily on N-glycans of standard CD44, the relevant determinant(s) on LS174T cells is expressed on O-glycans and is predominantly found on variant isoforms of CD44 (CD44v). Our finding that tumor-associated CD44 splice variant(s) express E-selectin ligand activity provides novel perspectives on the biology of CD44 in cancer metastasis.     

乙酰肝素酶的外源性表达对大肠癌HT29细胞侵袭性的影响

背景与目的:乙酰肝素酶(heparanase,Hpa)基因表达与恶性肿瘤及肿瘤细胞的侵袭、转移和血管生成能力密切相关。本研究旨在通过增强肿瘤细胞中外源性Hpa基因的表达,探讨该基因对大肠癌细胞HT29转移侵袭能力的影响。方法:Hpa全长基因真核表达载体转染HT29细胞,MTT法检测转化细胞增殖能力,Boyden小室体外侵袭实验比较转染前后细胞侵袭能力的变化,通过转化细胞裸鼠异种接种成瘤和实体瘤回盲部原位种植转移模型建立,观察Hpa基因外源性表达对HT29细胞侵袭性的影响。结果:转染Hpa基因细胞HT29-Hpa较未转染细胞HT29和转染空载细胞HT29-KZ生长速度明显加快;Boyden小室体外侵袭实验显示,HT29-Hpa细胞穿膜数(45.5±0.5)较HT29细胞(29.3±0.1)和HT29-KZ细胞(30.1±0.2)增多,差异具有显著性(P<0.01)。转染细胞裸鼠皮下瘤生长速度明显加快,同期内HT29-Hpa细胞形成的皮下瘤(12mm×9mm×10mm)较HT29细胞皮下瘤(6mm×8mm×6mm)大,HT29-Hpa细胞皮下瘤回盲部原位种植致肝转移率(71.43%)较HT29细胞肝转移率(14.29%)增高,两者间有显著性差异(P<0.01)。结论:Hpa基因外源性的表达能促进肿瘤细胞的生长、侵袭和转移。     

Expression of heparanase and its clinical significance in human non-small cell lung cancer

Objective： To explore the expression and significance of heparanase in non-small cell lung cancer （NSCLC） regarding prognosis and clinicopathological parameters. Methods： The expression of heparanase was assessed using immunohistochemistry staining and Western blot in 122 paraffin-embedded specimens and 38 freshly taken tissues. The relationship between heparanase expression and the clinicopathological factors was analyzed by Chi-square test, multivariate analysis and Kaplan-Meier method. Results： In the immunoreactive cells, staining was mainly located in cytoplasma and membrane. Human heparanase was highly expressed in lung cancer tissue （78.7%, 96/122） while negative in epithelia of normal lung tissues. The level of heparanase was remarkably higher in NSCLC than that in normal tissue （P=0.043）. Expression of heparanase significantly correlated with TNM stage （P=0.025）, lymphatic metastasis （P=0.002） and vascular invasion （P=0.0003）. The patients with positive heparanase expression had a significantly shorter survival than those with negative heparanase expression （P=0.0006）. In multivariate analysis, only p-TNM stage, lymphatic metastasis and vascular invasion could be considered as prognostic factors. Conclusion： Elevated level of heparanase in human non-small cell lung cancer tissues correlates with the TNM stage, invasion, metastasis and prognosis. However, heparanase expression is not an independent prognostic factor.     

Molecular treatment strategies and surgical reconstruction for metastatic bone diseases

Molecular mechanism of bone metastasis development is extremely complex. It is determined by intrinsic properties of cancer cells or cancer stem cells (CSCs) and intricate bone microenvironment. Therefore, molecular treatment strategies have been suggested to directly induce cancer cells apoptosis and to target vascular and bone microenvironment as well, thus inhibiting vicious cycles established between osteoblasts/osteoclasts and metastatic cancer cells. Chemokine/chemokine receptor pathway, adhesion molecules, and proteinases are crucial for bone metastatic process, including migration, adhesion and invasion into bone, angiogenesis and cell proliferation, which could provide potential targets for prevention and treatment of bone metastasis. Restoration of metastasis suppressor genes and microRNAs inhibits bone metastasis. Furthermore, targeting the bone marrow endothelium around cancer cells by use of both antiangiogenic inhibitors and vascular disrupting agents is another promising and valid therapeutic approach. On the other hand, many antitumor drugs/small molecules are limited in reaching tumor site due to a very complex vasculature. Nanotechnology aids in the targeted delivery of antitumor drugs/small molecules. For severe bone lesion, multifunctional implants integrating with antitumor drugs/small molecules and bone forming factors could be effective to reconstruct bone defects and to improve the quality of life in patients with bone metastasis.     

Increased level of circulating adhesion molecules in the sera of breast cancer patients with distant metastases

The adhesion of circulating cancer cells to the vascular endothelium is an important at step in the hematogenous metastasis of cancer. E-selectin expressed on endothelial cells and carbohydrate ligands expressed on cancer cells mediate this adhesion. We investigated the clinical significance of such cell adhesion molecules in breast cancer. The cytosol concentration of sialyl Lewis(x) was found more elevated in cancerous tissue than that in adjacent non-cancerous tissue. In the serum, sialyl Lewis(x) and soluble E-selectin were seen elevated in patients with advanced and recurrent breast cancer, especially in those with distant metastases. From the above, we have concluded that sialyl Lewis(x) and soluble E-selectin could be used as tumor markers with a close relationship to the metastasis of breast cancer.