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Analytical Biochemistry Jan 2010The role that heparanase plays during metastasis and angiogenesis in tumors makes it an attractive target for cancer therapeutics. Despite this enzyme's significance,...
The role that heparanase plays during metastasis and angiogenesis in tumors makes it an attractive target for cancer therapeutics. Despite this enzyme's significance, most of the assays developed to measure its activity are complex. Moreover, they usually rely on labeling variable preparations of the natural substrate heparan sulfate, making comparisons across studies precarious. To overcome these problems, we have developed a convenient assay based on the cleavage of the synthetic heparin oligosaccharide fondaparinux. The assay measures the appearance of the disaccharide product of heparanase-catalyzed fondaparinux cleavage colorimetrically using the tetrazolium salt WST-1. Because this assay has a homogeneous substrate with a single point of cleavage, the kinetics of the enzyme can be reliably characterized, giving a K(m) of 46 microM and a k(cat) of 3.5 s(-1) with fondaparinux as substrate. The inhibition of heparanase by the published inhibitor, PI-88, was also studied, and a K(i) of 7.9 nM was determined. The simplicity and robustness of this method, should, not only greatly assist routine assay of heparanase activity but also could be adapted for high-throughput screening of compound libraries, with the data generated being directly comparable across studies.
Topics: Colorimetry; Enzyme Assays; Enzyme Inhibitors; Fondaparinux; Glucuronidase; Humans; Kinetics; Oligosaccharides; Polysaccharides; Reducing Agents; Time Factors
PubMed: 19748475
DOI: 10.1016/j.ab.2009.09.007 -
Antiviral Research Jul 2004Although a number of sulfated polysaccharides have been shown to inhibit infection of cells by herpes simplex virus (HSV), little is known about their effects on the...
Although a number of sulfated polysaccharides have been shown to inhibit infection of cells by herpes simplex virus (HSV), little is known about their effects on the cell-to-cell spread of the virus. These compounds act by inhibiting the virus binding to cells, and their antiviral potencies usually increase with increasing molecular weight and sulfation density. We report that the low molecular weight HS-mimetic, PI-88, which is a mixture of highly sulfated mannose-containing di- to hexa-saccharides, inhibited HSV infection of cells and cell-to-cell spread of HSV-1 and HSV-2. Compared to a relatively large heparin polysaccharide, PI-88 demonstrated weaker inhibition of HSV infectivity but more efficient reduction of cell-to-cell spread of HSV. A tetrasaccharide fraction of PI-88 was the minimum fragment necessary to inhibit HSV-1 infectivity, while a trisaccharide was sufficient to reduce cell-to-cell spread. A reduction in HSV lateral spread was also observed in cells incubated with another low molecular weight compound, pentosan polysulfate but not with much larger polysaccharide chondroitin sulfate E. Some differences as regards the effects of PI-88, heparin, protamine, poly-L-lysine and sodium chlorate on intercellular spread of HSV-1 and HSV-2 were found. We conclude that structurally different sulfated oligosaccharides are preferred for inhibition of HSV infectivity and the cell-to-cell spread. The latter was efficiently inhibited by a relatively small but densely sulfated PI-88 oligosaccharide, very likely due to the capability of the compound to access the narrow intercellular space.
Topics: Alphaherpesvirinae; Antiviral Agents; Cell Line; Heparitin Sulfate; Molecular Weight; Oligosaccharides; Sulfates
PubMed: 15196816
DOI: 10.1016/j.antiviral.2004.01.001 -
Glycobiology Feb 2010Heparan sulfates (HS) bind a diversity of protein ligands on the cell surface and in the extracellular matrix and thus can modulate cell signaling. The state of...
Heparan sulfates (HS) bind a diversity of protein ligands on the cell surface and in the extracellular matrix and thus can modulate cell signaling. The state of sulfation in glucosamines and uronic acids within the chains strongly influences their binding. We have previously cloned and characterized two human extracellular endoglucosamine 6-sulfatases, HSulf-1 and HSulf-2, which selectively liberate the 6-O sulfate groups on glucosamines present in N, 6-O, and 2-O trisulfated disaccharides of intact HS and heparins. These enzymes serve important roles in development and are upregulated in a number of cancers. To determine whether the Sulfs act on the trisulfated disaccharides that exist on the cell surface, we expressed HSulfs in cultured cells and performed a flow cytometric analysis with the RB4CD12, an anti-HS antibody that recognizes N- and O-sulfated HS saccharides. The endogenously expressed level of the cell surface RB4CD12 epitope was greatly diminished in CHO, HEK293, and HeLa cells transfected with HSulf-1 or HSulf-2 cDNA. In correspondence with the RB4CD12 finding, the N, 6-O, and 2-O trisulfated disaccharides of the HS isolated from the cell surface/extracellular matrix were dramatically reduced in the Sulf-expressed HEK293 cells. We then developed an ELISA and confirmed that the RB4CD12 epitope in immobilized heparin was degraded by purified recombinant HSulf-1 and HSulf-2, and conditioned medium (CM) of MCF-7 breast carcinoma cells, which contain a native form of HSulf-2. Furthermore, HSulf-1 and HSulf-2 exerted activity against the epitope expressed on microvessels of mouse brains. Both HSulf activities were potently inhibited by PI-88, a sulfated heparin mimetic with anti-cancer activities. These findings provide new strategies for monitoring the extracellular remodeling of HS by Sulfs during normal and pathophysiological processes.
Topics: Animals; Brain; Cells, Cultured; Cloning, Molecular; Cricetinae; Cricetulus; Enzyme Inhibitors; Epitopes; Heparitin Sulfate; Humans; Mice; Microvessels; Oligosaccharides; Recombinant Proteins; Structure-Activity Relationship; Sulfatases; Sulfotransferases
PubMed: 19822709
DOI: 10.1093/glycob/cwp159 -
Antiviral Research Jan 2006Many viruses, including flaviviruses, display affinity for cell surface heparan sulfate (HS) proteoglycans with biological relevance in virus attachment/entry. This... (Comparative Study)
Comparative Study
Many viruses, including flaviviruses, display affinity for cell surface heparan sulfate (HS) proteoglycans with biological relevance in virus attachment/entry. This raises the possibility of the application of HS mimetics in antiviral therapy. We have evaluated the antiviral effect of the sulfated polysaccharides, suramin, pentosan polysulfate (PPS) and PI-88, which are currently approved or in trial for clinical use, against dengue virus (DEN) and the encephalitic flaviviruses, Japanese encephalitis virus, West Nile virus, and Murray Valley encephalitis virus. A flow cytometry-based method for the measurement of inhibition of virus infectivity was developed, which showed the in vitro antiviral activity of the three compounds, albeit with differences in efficiency which were virus-dependent. The 50% effective concentration (EC(50)) values for DEN inhibition were in the order: PPS
Topics: Animals; Antiviral Agents; Cell Line; Dengue; Dengue Virus; Disease Models, Animal; Drug Evaluation, Preclinical; Encephalitis Viruses, Japanese; Encephalitis, Arbovirus; Female; Flavivirus Infections; Heparitin Sulfate; Injections, Intraperitoneal; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oligosaccharides; Pentosan Sulfuric Polyester; Suramin; Treatment Outcome
PubMed: 16309754
DOI: 10.1016/j.antiviral.2005.08.006 -
Tumour Biology : the Journal of the... Mar 2016Phosphomannopentaose sulfate (PI-88), an effective inhibitor of heparanase (HPSE), exhibited anti-recurrence and anti-metastasis activity in preliminary clinical trials...
Phosphomannopentaose sulfate (PI-88), an effective inhibitor of heparanase (HPSE), exhibited anti-recurrence and anti-metastasis activity in preliminary clinical trials of hepatocellular carcinoma (HCC); however, the underlying mechanisms remain uncertain. Our aim was to reveal the mechanism by which PI-88 inhibits recurrence and intrahepatic metastasis. A tissue microarray containing samples from 352 HCC patients was used to determine HPSE expression. We performed enzyme-linked immunosorbent assay (ELISA) to detect plasma levels of HPSE in 40 HCC patients. We also used quantitative polymerase chain reaction, western blot analysis, and immunohistochemical staining to assess HPSE expression of HCC cell lines and tissues. The in vitro effects of PI-88 were examined by cell proliferation and migration assays. In vivo PI-88 activity was assessed using murine orthotopic HCC models. Intratumoral HPSE was an independent prognostic marker for postsurgical overall survival (P = 0.001) and time to recurrence (P < 0.001) of HCC patients with hepatectomy. Elevated levels of HPSE were detected both in postsurgical plasma of HCC patients and an orthotopic mouse model after hepatectomy. PI-88 inhibited tumor recurrence and metastasis after liver resection in the mouse model. In vitro expression of HPSE was up-regulated by overexpression of early growth response 1 (EGR1), which is induced after hepatectomy. Up-regulation of HPSE enhanced the sensitivity of HCC cells to PI-88 and the inhibitive effect of PI-88 on cell proliferation and migration. Our data show that PI-88 effectively inhibits postoperative recurrence and intrahepatic metastasis of HCC, providing an experimental basis for the clinical application of PI-88 in HCC patients who have undergone hepatectomy.
Topics: Animals; Carcinoma, Hepatocellular; Cell Movement; Glucuronidase; Hepatectomy; Liver Neoplasms; MAP Kinase Signaling System; Male; Mice; Mice, Inbred BALB C; Neoplasm Recurrence, Local; Oligosaccharides
PubMed: 26415733
DOI: 10.1007/s13277-015-4085-8 -
Matrix Biology : Journal of the... Jun 2012Heparin and its derivatives are known to regulate a variety of pathophysiological events related to vascular biology. In the present manuscript we examine a variety of...
Heparin and its derivatives are known to regulate a variety of pathophysiological events related to vascular biology. In the present manuscript we examine a variety of heparinomimetics biochemically (electrophoretic behavior and enzymatic degradation) and pharmacologically (in vitro anticoagulant activity and in vivo hemorrhagic and antithrombotic tests) as well as their interactions with cells from the vessel wall using a time resolved fluorometric method and confocal microscopy. Data were determined for unfractionated heparin (UFH), enoxaparin, synthetic heparin pentasaccharide, C3 heparin derived oligosaccharides and phosphosulfomannan (PI-88). While being structurally distinct from UFH, all compounds exhibited anticoagulant, antithrombotic and hemorrhagic activities. In addition, besides the pentasaccharide, they all stimulated the synthesis of an antithrombotic heparan sulfate present at the cell surface and secreted by endothelial cells. Also, like UFH, they interacted with both endothelial and smooth muscle cells and dislodged UFH from its binding sites in a dose dependent manner but, with distinct saturable curves showing that the binding of polymeric structures to extracellular matrix (ECM) proteins does not depend on a glycosaminoglycan backbone. The data also suggest a common pathway, which does not depend on the presence of the conventionally accepted antithrombin binding pentasaccharide, for ECM dependent activity of the heparinomimetic stimulated synthesis of antithrombotic heparan sulfate. Notably, although of similar molecular weight as well as polymeric backbone, the synthetic heparin pentasaccharide showed significant hemorrhagic action and negligible antithrombotic activity in a venous thrombosis model, contrasting with C3, that displayed negligible hemorrhagic effect and potent antithrombotic action. These results provide evidence that structurally unrelated polymers can elicit similar hemostatic activities and show that polymeric sequence is not always crucial for certain activities. The results also suggest that non-GAG structures may provide an alternative route for the pharmaceutical control of hemostasis.
Topics: Animals; Anticoagulants; Binding Sites; Dose-Response Relationship, Drug; Endothelial Cells; Extracellular Matrix; Fibrinolytic Agents; Hemostasis; Heparin; Heparin Lyase; Molecular Weight; Myocytes, Smooth Muscle; Oligosaccharides; Protein Binding; Proteolysis; Rabbits; Rats; Substrate Specificity
PubMed: 22504459
DOI: 10.1016/j.matbio.2012.03.001 -
Annals of Oncology : Official Journal... May 2002The novel molecule PI-88 is a highly sulfonated oligosaccharide which inhibits heparanase activity and competes with heparan sulfate binding of growth factors such as... (Clinical Trial)
Clinical Trial Comparative Study
BACKGROUND
The novel molecule PI-88 is a highly sulfonated oligosaccharide which inhibits heparanase activity and competes with heparan sulfate binding of growth factors such as FGF and VEGF. Preclinical data demonstrates that PI-88 inhibits angiogenesis and has anti-metastatic effects. The aim of this phase I study was to determine the recommended dose and toxicity profile of PI-88.
PATIENTS AND METHODS
PI-88 was given intravenously in increasing duration of administration (0.57 mg/kg for 2 h, 0.57 mg/kg/day for 1 day, 4, 7 and 14 consecutive days) and then increasing dose for 14 consecutive days (1.14 mg/kg/day and 2.28 mg/kg/day) in patients with advanced malignancies until dose-limiting toxicity (DLT) was observed. Fourteen assessable patients with advanced malignancies received PI-88 intravenously.
RESULTS
DLT was thrombocytopenia. The thrombocytopenia appeared to be immunologically mediated with the development of anti-heparin platelet factor 4 complex antibodies. There were no other significant toxicities. At the final dose and schedule (2.28 mg/kg/day for 14 days), there was limited evidence of biological activity as measured by the surrogate marker activated partial thromboplastin time (APTT), although two patients had stabilisation of disease.
CONCLUSIONS
In conclusion, PI-88 at a dose of 2.28 mg/kg/day for 14 days resulted in dose-limiting thrombocytopenia which appeared to be immune related. Limited evidence of biological activity was noted. Alternate scheduling and routes of administration are now being explored.
Topics: Adult; Aged; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Follow-Up Studies; Humans; Incidence; Infusions, Intravenous; Male; Maximum Tolerated Dose; Middle Aged; Neoplasm Staging; Neoplasms; Oligosaccharides; Risk Assessment; Survival Analysis; Thrombocytopenia; Treatment Outcome
PubMed: 12075747
DOI: 10.1093/annonc/mdf117 -
Clinical and Applied... Jan 2001Ecarin clotting time (ECT) is currently developed for the specific monitoring of antithrombin drugs, such as hirudin, argatroban, and hirulog. Aqueous reagent and dry... (Comparative Study)
Comparative Study
Ecarin clotting time (ECT) is currently developed for the specific monitoring of antithrombin drugs, such as hirudin, argatroban, and hirulog. Aqueous reagent and dry chemistry technology have become available for ECT monitoring of antithrombin agents. Currently, many heparinoids and heparinomimetic drugs are being developed. These agents activate heparin cofactor II (HCII) and primarily mediate their effects by inhibiting thrombin. Although the test is specific for antithrombin agents, heparin cofactor II-mediated thrombin inhibitors are capable of prolonging the ECT. In order to study the relative effects of some of these agents, ECT was measured in human plasma supplemented with Pl-88 (a sulfated pentomanose; Progen Industries Limited, Sydney, Australia), aprosulate, pentosan polysulfate, dermatan sulfate, unfractionated heparin (UFH), and recombinant hirudin (r-hirudin). All agents were supplemented to the citrated-pooled plasma prepared from 10 healthy volunteers at a graded dosage of 0 to 100 microg/ml. These techniques gave comparable results for all of the agents used (PI-88, r2 = 0.99; r-hirudin, r2 = 0.98; UFH, r2 = 0.98; dermatan sulfate, r2 = 0.95; aprosulate, r2 = 0.95; pentosan polysulfate, r2 = 0.94). The relative anticoagulant effects of various agents used on ECT varied widely, exhibiting their potency in the following order: r-hirudin = pentosan polysulfate > dermatan sulfate > PI-88 > aprosulate > UFH. The sensitivity of ECT was adjusted by varying the concentration of the ecarin reagent. The results suggest that HCII-mediated inhibition of thrombin can be detected by using ECT reagents.
Topics: Anti-Inflammatory Agents, Non-Steroidal; Anticoagulants; Antineoplastic Agents; Blood Coagulation; Blood Coagulation Tests; Dermatan Sulfate; Disaccharides; Dose-Response Relationship, Drug; Drug Monitoring; Endopeptidases; Enzyme Inhibitors; Fibrinolytic Agents; Heparinoids; Hirudins; Humans; Oligosaccharides; Pentosan Sulfuric Polyester; Sensitivity and Specificity; Thrombin
PubMed: 11190903
DOI: 10.1177/107602960100700109 -
Molecular Vision 2012Vascular endothelial growth factor (VEGF) is the most potent angiogenic mitogen, and has been associated with angiogenesis. Heparanase is an endoglycosidase that...
Phosphomannopentaose sulfate (PI-88) suppresses angiogenesis by downregulating heparanase and vascular endothelial growth factor in an oxygen-induced retinal neovascularization animal model.
PURPOSE
Vascular endothelial growth factor (VEGF) is the most potent angiogenic mitogen, and has been associated with angiogenesis. Heparanase is an endoglycosidase that specifically cleaves heparan sulfate side chains, which can induce VEGF expression. The aims of the present study were to evaluate the heparanase expression and its relationship with VEGF in the retina of oxygen-induced retinopathy (OIR) mice, and to investigate the effect of the heparanase inhibitor phosphomannopentaose sulfate (PI-88) in the OIR retinas.
METHODS
Seventy-seven newborn C57BL/6 mice were involved in this study. On postnatal day 7 (P7), pups were exposed to a hyperoxia condition (75% oxygen) for 5 days, and on P12, the mice were returned to room air. Control mice were exposed to room air from birth until P17, with normally developing retinal vasculature. PI-88 was administered intraperitoneally to OIR mice at a dose of 35.7 mg/kg/day for 5 consecutive days. The expression level of heparanase and VEGF in the retinas was assayed using immunohistochemistry, Q-RT-PCR, and western blot.
RESULTS
The expression levels of heparanase and VEGF were increased in the OIR retinas compared with the control mice. The Q-RT-PCR results showed that the mRNA expression levels of heparanase and VEGF in OIR retina were increased 1.71 fold (p<0.0001) and 4.34 fold (p<0.0001), respectively. The western blot results showed that the protein expression levels of heparanase and VEGF were increased 1.49 fold (p<0.0001) and 1.72 fold (p<0.0001), respectively, in the OIR retinas compared with the normal retinas. The immunohistochemistry analysis revealed that the heparanase and VEGF signals were intense in the retinal vascular endothelia of the OIR mice but faint in those of the normal controls. The increased protein and mRNA expression levels of heparanase and VEGF in the mouse retinas were significantly decreased by PI-88 administration (p<0.0001).
CONCLUSIONS
Heparanase expression was upregulated and correlated with an increase in VEGF expression in the OIR mouse retinas, and might be involved in the progress of retinopathy of prematurity. Inhibition of heparanase expression by PI-88 could be used as a novel therapeutic method for retinopathy of prematurity.
Topics: Animals; Animals, Newborn; Disease Models, Animal; Down-Regulation; Glucuronidase; Humans; Infant, Newborn; Injections, Intraperitoneal; Mice; Mice, Inbred C57BL; Oligosaccharides; Oxygen; Retinal Neovascularization; Retinopathy of Prematurity; Vascular Endothelial Growth Factor A
PubMed: 22773903
DOI: No ID Found -
Bioorganic & Medicinal Chemistry Letters Jul 2012Tumor-associated angiogenesis is a complex process that involves the interplay among several molecular players such as cell-surface heparan sulfate proteoglycans,...
Tumor-associated angiogenesis is a complex process that involves the interplay among several molecular players such as cell-surface heparan sulfate proteoglycans, vascular endothelial growth factors and their cognate receptors. PI-88, a highly sulfonated oligosaccharide, has been shown to have potent anti-angiogenic activity and is currently in clinical trials. However, one of the major drawbacks of large oligosaccharides such as PI-88 is that their synthesis often requires numerous complex synthetic steps. In this study, several novel polysulfonated small molecule carbohydrate mimetics, which can easily be synthesized in fewer steps, are identified as promising inhibitors of angiogenesis in an in vitro tube formation assay.
Topics: Angiogenesis Inhibitors; Animals; Biomimetic Materials; Cattle; Drug Evaluation, Preclinical; Endothelial Cells; Microtubules; Oligosaccharides; Small Molecule Libraries; Sulfur
PubMed: 22627041
DOI: 10.1016/j.bmcl.2012.04.014