Inhibition of experimental lung metastases of Lewis lung carcinoma cells by chemically modified heparin with reduced anticoagulant activity

Towards an emerging role for anticoagulants in cancer therapy: a systematic review and meta-analysis

Background

Anticoagulants, renowned for their role in preventing blood clot formation, have captivated researchers' attention for the exploitation of their potential to inhibit cancer in pre-clinical models.

Objectives

To undertake a systematic review and meta-analysis of the effects of anticoagulants in murine cancer research models. Further, to present a reference tool for anticoagulant therapeutic modalities relating to future animal pre-clinical models of cancer and their translation into the clinic.

Methods

Four databases were utilized including Medline (Ovid), Embase (Ovid), Web of science, and Scopus databases. We included studies relating to any cancer conducted in murine models that assessed the effect of traditional anticoagulants (heparin and its derivatives and warfarin) and newer oral anticoagulants on cancer.

Results

A total of 6,158 articles were identified in an initial multi-database search. A total of 157 records were finally included for data extraction. Studies on heparin species and warfarin demonstrated statistically significant results in favour of tumour growth and metastasis inhibition.

Conclusion

Our findings constitute a valuable reference guide for the application of anticoagulants in cancer research and explore the promising utilization of non-anticoagulants heparin in preclinical cancer research.

Systematic Review Registration

PROSPERO [CRD42024555603].

Harnessing the potential of de-sulfated heparin for targeted drug delivery: A three-component approach exemplified by conjugation with galactose and paclitaxel

Heparin, an anticoagulant with a century-long history of use, has been investigated over the past decade as a potential drug delivery vehicle. Despite its safety and efficacy, its interactions with many proteins through specific sulfate patterns can complicate drug delivery by mediating diverse biological functions. Here, we present the synthesis of a three-component drug delivery system comprising de-sulfated heparin as the carrier, galactose as the targeting moiety, and paclitaxel as the therapeutic drug. Removal of sulfates eliminated most of its anticoagulant effects in all intermediates. Through coupling with galactose and paclitaxel, the system improved the solubility of the drug and achieved selective targeting and efficient drug delivery to HepG2 cells, a liver carcinoma cell line with high galactose receptor expression. While the three-component system exhibited a slightly higher IC50 value than native paclitaxel, demonstrating its efficacy as a drug carrier, the IC50 value for the normal human liver cell line QSG7701 was significantly higher, indicating its selectivity and safety. Our study introduces a novel approach utilizing desulfated heparin as a carrier, warranting further investigation to unlock its potential in targeted drug delivery strategies.

A review on multifaceted biomedical applications of heparin nanocomposites: Progress and prospects

Advances in polymer-based nanocomposites have revolutionized biomedical applications over the last two decades. Heparin (HP), being a highly bioactive polymer of biological origin, provides strong biotic competence to the nanocomposites, broadening the horizon of their applicability. The efficiency, biocompatibility, and biodegradability properties of nanomaterials significantly improve upon the incorporation of heparin. Further, inclusion of structural/chemical derivatives, fractionates, and mimetics of heparin enable fabrication of versatile nanocomposites. Modern nanotechnological interventions have exploited the inherent biofunctionalities of heparin by formulating various nanomaterials, including inorganic/polymeric nanoparticles, nanofibers, quantum dots, micelles, liposomes, and nanogels ensuing novel functionalities targeting diverse clinical applications involving drug delivery, wound healing, tissue engineering, biocompatible coatings, nanosensors and so on. On this note, the present review explicitly summarises the recent HP-oriented nanotechnological developments, with a special emphasis on the reported successful engagement of HP and its derivatives/mimetics in nanocomposites for extensive applications in the laboratory and health-care facility. Further, the advantages and limitations/challenges specifically associated with HP in nanocomposites, undertaken in this current review are quintessential for future innovations/discoveries pertaining to HP-based nanocomposites.

A low-anticoagulant heparin suppresses metastatic dissemination through the inhibition of tumor cell-platelets association

Metastasis is the leading cause of cancer-related deaths. Despite this relevance, there is no specific therapy targeting metastasis. The interaction of the tumor cell with platelets, forming microemboli is crucial for successful hematogenous dissemination. Heparin disrupts it by a P-selectin-mediated event. However, its clinical use for this purpose is hindered by the requirement of high doses, leading to anticoagulant-related side effects. In this study, we obtained a low-anticoagulant heparin through the fractionation of a pharmaceutical bovine heparin. This derivative was referred to as LA-hep and we investigated its efficacy in inhibiting metastases and explored its capacity of suppressing the interaction between tumor cells and platelets. Our data revealed that LA-hep is as efficient as porcine unfractionated heparin in attenuating lung metastases from melanoma and colon adenocarcinoma cells in an assay with a single intravenous administration. It also prevents platelet arrest shortly after cell injection in wild-type mice and suppresses melanoma-platelets interaction in vitro. Moreover, LA-hep blocks P-selectin's direct binding to tumor cells and platelet aggregation, providing further evidence for the role of P-selectin as a molecular target. Even in P-selectin-depleted mice which developed a reduced number of metastatic foci, both porcine heparin and LA-hep further inhibited metastasis burden. This suggests evidence of an additional mechanism of antimetastatic action. Therefore, our results indicate a dissociation between the heparin anticoagulant and antimetastatic effects. Considering the simple and highly reproducible methodology used to purify LA-hep along with the data presented here, LA-hep emerges as a promising drug for future use in preventing metastasis in cancer patients.

The Tumorigenicity of Breast Cancer Cells Is Reduced upon Treatment with Small Extracellular Vesicles Isolated from Heparin Treated Cell Cultures

As a member of the HPSG family, heparin is often used as a specific probe of their role in cell physiology; indeed, we have previously shown a reduction in the tumorigenicity of breast cancer cells when cultured in its presence. However, a partial reversal of the anti-tumorigenic effect occurred when the treated cells were cultured in fresh medium without heparin, which led us to consider whether a more persistent effect could be achieved by treatment of the cells with small extracellular vesicles (sEV) from heparin-treated cells. The tumorigenicity was analyzed using sEV isolated from the culture medium of heparin-treated MCF-7 and MDA-MB231 breast cancer cells (sEV-HT) or from conditioned medium following the termination of treatment (heparin discontinued, sEV-HD). Tumorigenicity was reduced in cells cultured in the presence of sEV-HT compared to that of cells cultured in the presence of sEV from untreated cells (sEV-Ctrl). sEV-HD were also observed to exert an anti-tumorigenic effect on the expression of pro-tumorigenic and cell cycle regulatory proteins, as well as signaling activities when added to fresh cultures of MCF-7 and MDA-MB231 cells. The anti-tumorigenic activity of the heparin-derived sEV may arise from observed changes in the miRNA content or from heparin, which was observed to be bound to the sEV. sEV may constitute a relatively stable reservoir of circulating heparin, allowing heparin activity to persist in the circulation even after therapy has been discontinued. These findings can be considered as a special additional pharmacological characteristic of heparin clinical therapy.

The anti-cancer properties of heparin and its derivatives: a review and prospect

Heparin, including unfractionated heparin (UFH), low-molecular-weight heparin (LMWH) and heparin derivatives, are commonly used in venous thromboembolism treatment and reportedly have beneficial effects on cancer survival. Heparin can affect the proliferation, adhesion, angiogenesis, migration and invasion of cancer cells via multiple mechanisms. The main mechanisms involve inhibition of heparanase, P-/L-selectin, angiogenesis, and interference with the CXCL12-CXCR4 axis. Here we summarize the current experimental evidence regarding the anti-cancer role of heparin and its derivatives, and conclude that there is evidence to support heparin’s role in inhibiting cancer progression, making it a promising anti-cancer agent.

Aberrant Factors of Fibrinolysis and Coagulation in Pancreatic Cancer

Aberrant factors associated with fibrinolysis and thrombosis are found in many cancer patients, which can promote metastasis and are associated with poor prognosis. The relationship between tumor-associated fibrinolysis and thrombosis is poorly understood in pancreatic cancer. This review provides a brief highlight of existing studies that the fibrinolysis and coagulation systems were activated in pancreatic cancer patients, along with aberrant high concentrations of tissue plasminogen activator (t-PA), urine plasminogen activator (u-PA), D-dimer, fibrinogen, or platelets. These factors cooperate with each other, propelling tumor cell shedding, localization, adhesion to distant metastasis. The relationship between thrombosis or fibrinolysis and cancer immune escape is also investigated. In addition, the potential prevention and therapy strategies of pancreatic cancer targeting factors in fibrinolysis and coagulation systems are also been discussed, in which we highlight two effective agents aspirin and low-molecular weight heparin (LMWH). Summarily, this review provides new directions for the research and treatment of pancreatic cancer.

Pulsed Low-Frequency Magnetic Fields Induce Tumor Membrane Disruption and Altered Cell Viability

Tumor cells express a unique cell surface glycocalyx with upregulation of sulfated glycosaminoglycans and charged glycoproteins. Little is known about how electromagnetic fields interact with this layer, particularly with regard to harnessing unique properties for therapeutic benefit. We applied a pulsed 20-millitesla (mT) magnetic field with rate of rise (dB/dt) in the msec range to cultured tumor cells to assess whether this affects membrane integrity as measured using cytolytic assays. A 10-min exposure of A549 human lung cancer cells to sequential 50- and 385-Hz oscillating magnetic fields was sufficient to induce intracellular protease release, suggesting altered membrane integrity after the field exposure. Heparinase treatment, which digests anionic sulfated glycan polymers, before exposure rendered cells insensitive to this effect. We further examined a non-neoplastic human primary cell line (lung lymphatic endothelial cells) as a typical normal host cell from the lung cancer microenvironment and found no effect of field exposure on membrane integrity. The field exposure was also sufficient to alter proliferation of tumor cells in culture, but not that of normal lymphatic cells. Pulsed magnetic field exposure of human breast cancer cells that express a sialic-acid rich glycocalyx also induced protease release, and this was partially abrogated by sialidase pretreatment, which removes cell surface anionic sialic acid. Scanning electron microscopy showed that field exposure may induce unique membrane “rippling” along with nanoscale pores on A549 cells. These effects were caused by a short exposure to pulsed 20-mT magnetic fields, and future work may examine greater magnitude effects. The proof of concept herein points to a mechanistic basis for possible applications of pulsed magnetic fields in novel anticancer strategies.

The Challenge of Modulating Heparan Sulfate Turnover by Multitarget Heparin Derivatives

This review comes as a part of the special issue "Emerging frontiers in GAGs and mimetics". Our interest is in the manipulation of heparan sulfate (HS) turnover by employing HS mimetics/heparin derivatives that exert pleiotropic effects and are interesting for interfering at multiple levels with pathways in which HS is implicated. Due to the important role of heparanase in HS post-biosynthetic modification and catabolism, we focus on the possibility to target heparanase, at both extracellular and intracellular levels, a strategy that can be applied to many conditions, from inflammation to cancer and neurodegeneration.

Non-Anticoagulant Heparins as Heparanase Inhibitors

The chapter will review early and more recent seminal contributions to the discovery and characterization of heparanase and non-anticoagulant heparins inhibiting its peculiar enzymatic activity. Indeed, heparanase displays a unique versatility in degrading heparan sulfate chains of several proteoglycans expressed in all mammalian cells. This endo-β-D-glucuronidase is overexpressed in cancer, inflammation, diabetes, atherosclerosis, nephropathies and other pathologies. Starting from known low- or non-anticoagulant heparins, the search for heparanase inhibitors evolved focusing on structure-activity relationship studies and taking advantage of new chemical-physical analytical methods which have allowed characterization and sequencing of polysaccharide chains. New methods to screen heparanase inhibitors and to evaluate their mechanism of action and in vivo activity in experimental models prompted their development. New non-anticoagulant heparin derivatives endowed with anti-heparanase activity are reported. Some leads are under clinical evaluation in the oncology field (e.g., acute myeloid leukemia, multiple myeloma, pancreatic carcinoma) and in other pathological conditions (e.g., sickle cell disease, malaria, labor arrest).

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.

PCL and PCL-based materials in biomedical applications

Biodegradable polymers have met with an increasing demand in medical usage over the last decades. One of such polymers is poly(ε-caprolactone) (PCL), which is a polyester that has been widely used in tissue engineering field for its availability, relatively inexpensive price and suitability for modification. Its chemical and biological properties, physicochemical state, degradability and mechanical strength can be adjusted, and therefore, it can be used under harsh mechanical, physical and chemical conditions without significant loss of its properties. Degradation time of PCL is quite long, thus it is used mainly in the replacement of hard tissues in the body where healing also takes an extended period of time. It is also used at load-bearing tissues of the body by enhancing its stiffness. However, due to its tailorability, use of PCL is not restricted to one type of tissue and it can be extended to engineering of soft tissues by decreasing its molecular weight and degradation time. This review outlines the basic properties of PCL, its composites, blends and copolymers. We report on various techniques for the production of different forms, and provide examples of medical applications such as tissue engineering and drug delivery systems covering the studies performed in the last decades.

Old and new applications of non-anticoagulant heparin

The aim of this chapter is to provide an overview of non-anticoagulant effects of heparins and their potential use in new therapeutic applications. Heparin and heparin derivatives have been tested in inflammatory, pulmonary and reproductive diseases, in cardiovascular, nephro- and neuro-tissue protection and repair, but also as agents against angiogenesis, atheroschlerosis, metastasis, protozoa and viruses. Targeting and inhibition of specific mediators involved in the inflammatory process, promoting some of the above mentioned pathologies, are reported along with recent studies of heparin conjugates and oral delivery systems. Some reports from the institute of the authors, such as those devoted to glycol-split heparins are also included. Among the members and derivatives of this class, several are undergoing clinical trials as antimetastatic and antimalarial agents and for the treatment of labour pain and severe hereditary anaemia. Other heparins, whose therapeutic targets are non-anticoagulant such as nephropathies, retinopathies and cystic fibrosis are also under investigation.

Heparin modification enhances the delivery and tumor targeting of paclitaxel-loaded N-octyl-N-trimethyl chitosan micelles

Polycations have been widely used as efficient drug and gene carriers. However, the further application of polycation nanocarriers is greatly hampered by the serious cytotoxicity caused by exposed positive charges. Despite recent progress towards the therapeutic delivery of nucleic acids, there remains a compelling need for development of novel delivery systems for various types of drug. Here, we created mixed micelles based on N-octyl-N-trimethyl chitosan (OTMC) and coated them with an anionic polymer for delivery of paclitaxel (PTX). OTMC/PEG-100 stearate (S-100) micelles (PTX-SN) were firstly prepared by a dialysis method with a high drug loading efficiency and positive charge. PTX-SN micelles were then coated with two anionic polymers, heparin sodium (PTX-HSN) and sodium carboxymethyl cellulose (PTX-CSN) to shield positive charges. Both PTX-HSN and PTX-CSN micelles showed decreased cytotoxicity and hemolysis while retaining high uptake efficiency. PTX-HSN micelles were taken up more effectively than PTX-CSN by HeLa cells, which over-express heparanase. PTX-HSN micelles persisted longer in the circulation of rats than free drug in pharmacokinetic studies. DIR-HSN micelles accumulated strongly in tumors, and PTX-HSN micelles significantly inhibited tumor growth in tumor-bearing mice. Overall, the results validate heparin-coated OTMC micelles as safe and effective tumor-targeting carriers that are suitable for anti-tumor drug delivery.

1-methylnicotinamide and its structural analog 1,4-dimethylpyridine for the prevention of cancer metastasis

Background

1-methylnicotinamide (1-MNA), an endogenous metabolite of nicotinamide, has recently gained interest due to its anti-inflammatory and anti-thrombotic activities linked to the COX-2/PGI₂ pathway. Given the previously reported anti-metastatic activity of prostacyclin (PGI₂), we aimed to assess the effects of 1-MNA and its structurally related analog, 1,4-dimethylpyridine (1,4-DMP), in the prevention of cancer metastasis.

Methods

All the studies on the anti-tumor and anti-metastatic activity of 1-MNA and 1,4-DMP were conducted using the model of murine mammary gland cancer (4T1) transplanted either orthotopically or intravenously into female BALB/c mouse. Additionally, the effect of the investigated molecules on cancer cell-induced angiogenesis was estimated using the matrigel plug assay utilizing 4T1 cells as a source of pro-angiogenic factors.

Results

Neither 1-MNA nor 1,4-DMP, when given in a monotherapy of metastatic cancer, influenced the growth of 4T1 primary tumors transplanted orthotopically; however, both compounds tended to inhibit 4T1 metastases formation in lungs of mice that were orthotopically or intravenously inoculated with 4T1 or 4T1-luc2-tdTomato cells, respectively. Additionally, while 1-MNA enhanced tumor vasculature formation and markedly increased PGI₂ generation, 1,4-DMP did not have such an effect. The anti-metastatic activity of 1-MNA and 1,4-DMP was further confirmed when both agents were applied with a cytostatic drug in a combined treatment of 4T1 murine mammary gland cancer what resulted in up to 80 % diminution of lung metastases formation.

Conclusions

The results of the studies presented below indicate that 1-MNA and its structural analog 1,4-DMP prevent metastasis and might be beneficially implemented into the treatment of metastatic breast cancer to ensure a comprehensive strategy of metastasis control.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0389-9) contains supplementary material, which is available to authorized users.

Heparin-appended polycaprolactone core/corona nanoparticles for site specific delivery of 5-fluorouracil

The aim of the present work is to formulate heparin-modified-polycaprolactone (HEP) core shell nanoparticles (NPs) of 5-fluorouracil (5-FU). These NPs were characterized for various in vitro parameters like particle size, zeta potential, etc. HEP NPs were found to maintain comparatively slower drug release pattern (98.9% in 96 h) than PCL NPs. Cytotoxicity studies demonstrated a massive cytotoxic potential of 5-FU-loaded HEP NPs in A549, MDA-MD-435, and SK-OV-3 cancer cell lines. Pharmacokinetic parameters were also determined in blood after IV administration of HEP NPs: AUC, C_max, MRT, and T_max values are 6096.075 ± 5.90 μg h/mL, 144.38 ± 1.52 μg/L, 58.71 ± 0.25 h, 96 ± 0.50 h, respectively and 117.92 ± 1.78, 45.35 ± 3.00, 1.2 ± 0.25, 0.5 ± 0.02 in plain 5-FU solution.

In vivo evaluation of an anticancer drug delivery system based on heparinized mesoporous silica nanoparticles

MSNs-HP loaded with only a low amount of a drug (DOX0.3) achieve a similar antitumor efficacy to that of large doses of the drug (DOX2.0, 7-fold higher in dosage than DOX0.3).

Rationale for clinical trials of coagulation: reactive drugs in hepatocellular carcinoma

Evidence for the regulation of cancer growth by components of the blood coagulation mechanism provides abundant opportunity for the development of novel hypotheses for the experimental treatment of malignancy. Information available on the heterogeneity in mechanisms of interaction between various cancer cell types, and procoagulant and fibrinolytic pathways, platelets, glycosaminoglycan-regulated growth factors and cell-adhesion molecules indicates that insightful clinical trial design may allow targeting of individual cancer cell types with agents capable of intercepting mechanisms of growth control that are relevant to specific tumor types. This paper reviews the evidence that the common anticoagulant, heparin, inhibits hepatocellular carcinoma cell proliferation and hepatocellular carcinoma tumor dissemination in experimental animals. Clinical trials of heparin performed to date have shown increased tumor response rates and survival in other tumor types. Expression of urokinase-type plasminogen activator by hepatocellular carcinoma cells enhances tumor cell proliferation, motility, invasiveness and metastatic dissemination. Inhibition of the urokinase-type plasminogen activator/plasmin system by protease inhibitors such as aprotinin (Trasylol, Bayer) have shown improvement in the clinical course of certain tumor types. These data suggest that drugs that are well-known in the field of vascular medicine may find a role in the treatment of hepatocellular carcinoma, a common tumor type that has resisted containment by other means.

Application of polysaccharides for surface modification of nanomedicines

Polysaccharides have been used in various biomedical applications due to availability and biocompatibility. In particular, polysaccharides have gained increasing interest in the development of functional nanomedicines as a component to provide a stealth function, improve interactions with target tissues or enable environment-responsive drug release. This review discusses recent advances in nanomedicine engineering based on polysaccharides with a specific emphasis on the rationale, applications and the remaining challenges.

Inhibitory effect of non-anticoagulant heparin (S-NACH) on pancreatic cancer cell adhesion and metastasis in human umbilical cord vessel segment and in mouse model

Metastasis is the most devastating aspect of cancer and it is the main cause of morbidity and mortality in cancer patients. Tumor cell adhesion to the vascular endothelial cell lining is an important step in metastatic progression and is prompted by platelets. Mucin 1 is over-expressed and aberrantly glycosylated in more than 60% of pancreatic ductal adeno-carcinomas, which mediate adhesion of pancreatic cancer cells to platelets via P-selectin. The anticoagulant low molecular weight heparins (LMWHs), which are commonly used in venous Thromboprophylaxis and treatment, appear to have an effect on cancer survival. The aim of this study is to investigate the effect of platelets on human pancreatic cancer MPanc96 cell adhesion to the endothelial cell vessel wall, and to examine the effect of heparin derivatives on MPanc96 adhesion using a novel, in vitro model of human umbilical cord vein. The modified heparin S-NACH (sulfated non-anticoagulant heparin), which is devoid of antithrombin (AT) binding and devoid of inhibition of systemic AT-dependent coagulation factors such as factor Xa and IIa, and the LMWH tinzaparin both potently reduced adhesion and invasion of fluorescence-labeled MPanc96 cancer cells to the endothelial layer of umbilical cord vein in a dose-dependent manner. S-NACH effectively inhibited P-selectin mediated MPanc96 cell adhesion, and inhibited cell adhesion and invasion similar to tinzaparin, indicating that systemic anticoagulation is not a necessary component for heparin attenuation of cancer cell adhesion, invasion, and metastasis. Also, S-NACH and tinzaparin versus unfractionated heparin, heparin derivatives enoxaparin, deltaparin, fraxiparin, and fondaparinux were evaluated for their effect on platelet-cancer cell adhesion. An in vivo anti-metastatic S-NACH-treated nude mouse model of MPanc96 pancreatic cancer cell metastasis demonstrated potent anti-metastasis efficacy as evidenced by IVIS imaging and histological staining.

Heparin promotes suspension adaptation process of CHO-TS28 cells by eliminating cell aggregation

While heparin has been shown to eliminate cell aggregation in suspension adaptations of insect and HEK293 cells for virus-based cell cultures, the role of heparin in long period serum-free suspension adaptation of the anchorage-dependent Chinese hamster ovary (CHO) cell lines remains inconclusive. In this paper, we explore the potential application of heparin in suspension adaptation of CHO cell line which produces an anti-human chimeric antibody cHAb18. Heparin showed a concentration-dependent inhibition of CHO-TS28 cell-to-cell adhesion, with a significant inhibitory effect occurring when the concentration exceeded 250 μg/ml (P < 0.001). Heparin also exhibited a cell aggregation elimination role at all concentrations (P < 0.001). Furthermore, heparin promoted cell growth and antibody secretion, with the highest cell density ((99.83 ± 12.21) × 10(4) cells/ml, P = 0.034) and maximum antibody yield ((9.46 ± 0.94) mg/l, P < 0.001) both occurring at 250 μg/ml heparin. When agitated, cell aggregates were effectively dispersed by 250 μg/ml heparin and a single-cell suspension culture process was promoted. In suspension adapted CHO-TS28 cells, cell growth rates and specific antibody productivity were maintained; while antigen-binding activity improved slightly. Together, our results show that heparin may promote suspension adaptation of anchorage-depended CHO cells by resisting cell aggregation without reducing cell growth, antibody secretion, and antigen-binding activity.

High antiangiogenic and low anticoagulant efficacy of orally active low molecular weight heparin derivatives

Heparin, an anticoagulant that is widely used clinically, is also known to bind to several kinds of proteins through electrostatic interactions because of its polyanionic character. These interactions are mediated by the physicochemical properties of heparin such as sequence composition, sulfation patterns, charge distribution, overall charge density, and molecular size. Although this electrostatic character mediates its binding to many proteins related with tumor progression, thereby providing its antiangiogenic property, the administration of heparin for treating cancer is limited in clinical applications due to several drawbacks, such as its low oral absorption, unsatisfactory therapeutic effects, and strong anticoagulant activity which induces hemorrhaging. Here, we evaluated novel, orally active, low molecular weight heparin (LMWH) derivatives (LHD) conjugated with deoxycholic acid (DOCA) that show reduced anticoagulant activity and enhanced antiangiogenic activity. The chemical conjugate of LMWH and DOCA was synthesized by conjugating the amine group of N-deoxycholylethylamine (EtDOCA) with the carboxylic groups of heparin at various DOCA conjugation ratios. The LMWH-DOCA conjugate series (LHD1, LHD1.5, LHD2, and LHD4) were further formulated with poloxamer 407 as a solubilizer for oral administration. An in vitro endothelial tubular formation and in vivo Matrigel plug assay were performed to verify the antiangiogenic potential of LHD. Finally, we evaluated tumor growth inhibition of oral LHD administration in a SCC7 model as well as in A549 human cancer cell lines in a mouse xenograft model. Increasing DOCA conjugation ratios showed decreased anticoagulant activity, eventually to zero. LHD could block angiogenesis in the tubular formation assay and the Matrigel plug assay. In particular, oral administration of LHD4, which has 4 molecules of DOCA per mole of LMWH, inhibited tumor growth in SCC7 mice model as well as A549 mice xenograft model. LHD4 was orally absorbable, showed minimal anticoagulant activity and inhibits tumor growth via antiangiogenesis. These findings demonstrate the therapeutic potential of LHD4 as a new oral anti-cancer drug.

Heparin-paclitaxel conjugates as drug delivery system: synthesis, self-assembly property, drug release, and antitumor activity

We have synthesized a series of novel prodrugs consisting of amphiphilic heparin-paclitaxel conjugates. Each prodrug in the series consists of a succinylated-heparin carrier conjugated to paclitaxel via a single amino acid spacer, either valine, leucine, or phenylalanine (prodrug1, prodrug2, and prodrug3, respectively). Unlike physically encapsulated drugs, these prodrugs can self-assemble to form nanoparticles in aqueous solution while still maintaining structural integrity for loading parent drug due to the dual hydrophilic/hydrophobic nature of the carrier and drug compound. The structure of prodrugs has been characterized by 1H NMR, FT-IR, and GPC. Their morphology has been investigated by SEM. Our results show that these self-assembled nanoparticles have a narrow size distribution (140-180 nm) and form an approximately spherical shape composed of a paclitaxel core and carrier shell. The anticoagulant activity of all the prodrugs is sharply decreased compared to that of heparin, as measured by activated partial thromboplastin time (aPTT), thereby reducing the risk of severe hemorrhagic complication during systemic administration. Furthermore, the prodrugs exhibit better in vitro cell inhibition for MCF-7 cells than free paclitaxel. Flow cytometric analyses (FCM) have shown that MCF-7 cells treated with prodrugs are arrested in the G(2)/M phase of the cell cycle. Meanwhile, these three prodrugs each exhibit unique hydrolysis properties under various physiological or plasma conditions. In particular, prodrug2 with leucine spacer may result in favorable hydrolysis of the ester bond between the amino acid and paclitaxel under physiological conditions. In mice, prodrug2 shows a similar ovarian tumor growth inhibition as paclitaxel and induces no obvious body weight loss. Hence, the prepared nanoscale prodrugs are expected not only to render structural integrity to the parent drug, but also enhance targeting capacity to solid tumors.

Heparin as an inhibitor of cancer progression

Heparin is frequently used in the treatment of cancer-associated thromboembolism. Accumulating clinical evidence indicates that cancer patients treated with unfractionated and low-molecular weight heparin (LMWH) survive longer than patients treated by other anticoagulants, especially patients in the early stage of the disease. Experimental analysis from a number of animal models constantly provides evidence for the ability of heparin to attenuate metastasis. The non-anticoagulant activity of heparin on metastasis includes the ability to inhibit cell-cell-interaction through blocking of P- and L-selectin, to inhibit extracellular matrix protease heparanase, and to inhibit angiogenesis. This chapter summarizes current experimental evidence on the biology of heparin during cancer progression, with the focus on potential mechanism of heparin antimetastatic activity.

Synthesis of Aminooxy End-functionalized pNIPAAm by RAFT Polymerization for Protein and Polysaccharide Conjugation

A Boc-protected aminooxy end-functionalized poly(N-isopropylacrylamide) (pNIPAAm) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The monomer was polymerized in the presence of a Boc-protected aminooxy trithiocarbonate chain transfer agent (CTA) utilizing 2,2'-azobis(2-isobutyronitrile) (AIBN) as the initiator in DMF at 70 °C. The final polymer had a number-average molecular weight (M(n)) of 4,200 Da as determined by (1)H NMR spectroscopy and a narrow polydispersity index (1.14) by gel permeation chromatography (GPC). The Boc group was removed, and the polymer was then incubated with N(ε)-levulinyl lysine-modified bovine serum albumin (BSA). Gel electrophoresis confirmed that the conjugation was successful. The aminooxy end-functionalized pNIPAAm was also immobilized on a gold surface after reduction of the trithiocarbonate end-group. The pNIPAAm surface was then incubated with an aldehyde-modified heparin to yield the polysaccharide-functionalized surface. All surface modifications were monitored by FT-IR spectroscopy.

Involvement of highly sulfated chondroitin sulfate in the metastasis of the Lewis lung carcinoma cells

The altered expression of cell surface chondroitin sulfate (CS) and dermatan sulfate (DS) in cancer cells has been demonstrated to play a key role in malignant transformation and tumor metastasis. However, the functional highly sulfated structures in CS/DS chains and their involvement in the process have not been well documented. In the present study, a structural analysis of CS/DS from two mouse Lewis lung carcinoma (3LL)-derived cell lines with different metastatic potentials revealed a higher proportion of Delta(4,5)HexUA-GalNAc(4,6-O-disulfate) generated from E-units (GlcUA-GalNAc(4, 6-O-disulfate)) in highly metastatic LM66-H11 cells than in low metastatic P29 cells, although much less CS/DS is expressed by LM66-H11 than P29 cells. This key finding prompted us to study the role of CS-E-like structures in experimental lung metastasis. The metastasis of LM66-H11 cells to lungs was effectively inhibited by enzymatic removal of tumor cell surface CS or by preadministration of CS-E rich in E-units in a dose-dependent manner. In addition, immunocytochemical analysis showed that LM66-H11 rather than P29 cells expressed more strongly the CS-E epitope, which was specifically recognized by the phage display antibody GD3G7. More importantly, this antibody and a CS-E decasaccharide fraction, the minimal structure recognized by GD3G7, strongly inhibited the metastasis of LM66-H11 cells probably by modifying the proliferative and invading behavior of the metastatic tumor cells. These results suggest that the E-unit-containing epitopes are involved in the metastatic process and a potential target for the diagnosis and treatment of malignant tumors.

In vivoHeparan Sulfate Treatment Alters the Immune Response of Normal and LLC-Bearing Mice

Despite the large amount of research dedicated to the understanding and treatment of tumor growth, the majority of cancers continue to lack effective therapeutic options. As in the case of most solid tumors, growth requires evasion of the host immune system. Our previous work using the Lewis Lung Carcinoma (LLC) model of tumor bearing (TB)-mice has shown several tumor-induced immune suppressing effects to be present. These effects include a decreased T-cell proliferative response to Con A and altered cytokine secretion patterns that favor neither a Th1 nor a Th2 response. To address these immune alterations, immune modulating approaches have been a central area of study. Of the many potential immune modulating compounds, we believe promising therapeutic potential lies in the heparin family. Heparan sulfate (HS), in particular, has been shown to increase T-cell proliferative response in non TB-mouse splenocytes as well as promotion of a beneficial Th1 response. In this paper, we studied the potential of HS to decrease tumor burden via in vivo treatment of TB-mice. Results showed both normal and TB-mice splenocytes had a dose response change in proliferation as a result of HS treatment. Furthermore, splenocytes from HS treated TB-mice showed a potentially beneficial decrease in basal level proliferation. On gross examination, HS treatment produced a decrease in tumor surface necrosis with a visible (2 +/- 1.8%) surface necrotic area in treated mice as opposed to a (43 +/- 16%) surface necrotic area in untreated mice. HS treatment decreased TB-mice splenomegaly when comparing mice spleen weights in treated (0.3 +/- 0.05 g) vs. untreated (0.14 +/- 0.02 g) groups. These results show a potential role of HS as an immune modulating agent with antitumor properties.

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

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

A Novel Function of Syndecan-2, Suppression of Matrix Metalloproteinase-2 Activation, Which Causes Suppression of Metastasis

The syndecans comprise a family of cell surface heparan sulfate proteoglycans exhibiting complex biological functions involving the interaction of heparan sulfate side chains with a variety of soluble and insoluble heparin-binding extracellular ligands. Here we demonstrate an inverse correlation between the expression level of syndecan-2 and the metastatic potential of three clones derived from Lewis lung carcinoma 3LL. This correlation was proved to be a causal relationship, because transfection of syndecan-2 into the higher metastatic clone resulted in the suppression of both spontaneous and experimental metastases to the lung. Although the expression levels of matrix metalloproteinase-2 (MMP-2) and its cell surface activators, such as membrane-type 1 matrix metalloproteinase and tissue inhibitor of metalloproteinase-2, were similar regardless of the metastatic potentials of the clones, elevated activation of MMP-2 was observed in the higher metastatic clone. Removal of heparan sulfate from the cell surface of low metastatic cells by treatment with heparitinase-I promoted MMP-2 activation, and transfection of syndecan-2 into highly metastatic cells suppressed MMP-2 activation. Furthermore, transfection of mutated syndecan-2 lacking glycosaminoglycan attachment sites into highly metastatic cells did not have any suppressive effect on MMP-2 activation, suggesting that this suppression was mediated by the heparan sulfate side chains of syndecan-2. Actually, MMP-2 was found to exhibit a strong binding ability to heparin, the dissociation constant value being 62 nM. These results indicate a novel function of syndecan-2, which acts as a suppressor for MMP-2 activation, causing suppression of metastasis in at least the metastatic system used in the present study.

In vitro heparan sulfate modulates the immune responses of normal and tumor-bearing mice

Tumor-bearing (TB) patients and TB animal models show a wide array of immunologic deficits. Heparan sulfate (HS) has been shown to both improve immune cell proliferative responses and to induce Th1 cytokine responses in normal animals. These HS effects, if harnessed, would be of great benefit to TB patients. The present study focused on replicating previous HS-induced Th1 and proliferative response results as well as extrapolating the beneficial immunomodulatory effects to an experimental model derived from TB animals of Lewis lung cell carcinoma. Lewis Lung Carcinoma (LLC)-TB and control mouse splenocytes were assessed for proliferation and cytokine response to concanavalin A (Con A) with 1 and 3 days' exposure to HS. Our results found HS treatment stimulated splenocyte proliferation to Con A in control mice splenocytes after 1 and 3 days of treatment, although HS proliferative effects were not seen in unfractionated TB cultures. Furthermore, cytokine studies revealed normal splenocytes treated with HS had increased levels of both Th1 and Th2 cytokines. Surprisingly, HS treated TB-splenocytes showed suppressed cytokine levels. Of particular interest was the decreased levels of the Th2 cytokine IL-4 in TB-derived samples. In conclusion, we found that HS did show immune-modulator properties in both normal and TB environments. Our studies reinforced the possibility that HS could one day be used as an immune-modulating therapeutic agent.

P-selectin- and heparanase-dependent antimetastatic activity of non-anticoagulant heparins

Vascular cell adhesion molecules, P- and L-selectins, facilitate metastasis of cancer cells in mice by mediating interactions with platelets, endothelium, and leukocytes. Heparanase is an endoglycosidase that degrades heparan sulfate of extracellular matrix, thereby promoting tumor invasion and metastasis. Heparin is known to efficiently attenuate metastasis in different tumor models. Here we identified modified, nonanticoagulant species of heparin that specifically inhibit selectin-mediated cell-cell interactions, heparanase enzymatic activity, or both. We show that selective inhibition of selectin interactions or heparanase with specific heparin derivatives in mouse models of MC-38 colon carcinoma and B16-BL6 melanoma attenuates metastasis. Selectin-specific heparin derivatives attenuated metastasis of MC-38 carcinoma, but heparanase-specific derivatives had no effect, in accordance with the virtual absence of heparanase activity in these cells. Heparin derivatives had no further effect on metastasis in mice deficient in P- and L-selectin, indicating that selectins are the primary targets of heparin antimetastatic activity. Selectin-specific and heparanase-specific derivatives attenuated metastasis of B16-BL6 melanomas to a similar extent. When mice were injected with a derivative containing both heparanase and selectin inhibitory activity, no additional attenuation of metastasis could be observed. Thus, selectin-specific heparin derivatives efficiently attenuated metastasis of both tumor cell types whereas inhibition of heparanase led to reduction of metastasis only in tumor cells producing heparanase.

The attenuation of experimental lung metastasis by a bile acid acylated-heparin derivative

The inhibitory efficacies of new bile acid acylated-heparin derivative (heparin-DOCA) were evaluated on experimental lung metastasis. We evaluated the effect of heparin-DOCA on intercellular interactions including those between B16F10 and thrombin-activated platelets and TNF-alpha-activated HUVECs, and between B16F10 and immobilized mouse P-selectin. In addition, the inhibitory effects of heparin-DOCA on adhesion and invasion of B16F10 to Matrigel were studied. In an animal mouse study, the blood clot formation and the retention of red fluorescence protein (RFP)-B16F10 in lungs were assessed after heparin-DOCA and RFP-B16F10 intravenous administration. Furthermore, we investigated the anti-metastatic effect of heparin-DOCA against lung metastasis induced by B16F10 and SCC7. Heparin-DOCA inhibited intercellular interactions between B16F10 and activated platelets or activated HUVECs by blocking P- and E-selectin-mediated interactions. Moreover, it reduced adhesion and invasion of B16F10 to ECM, thereby affecting the reduction of early retention of B16F10 in the lung. Heparin-DOCA attenuated lung colony formation on the surfaces and in interior of the lung, and attenuated metastasis by B16F10 and SCC7. These results suggest that heparin-DOCA may have potentials as therapeutic agent that prevents tumor metastasis and progression.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Heparin–deoxycholic acid chemical conjugate as an anticancer drug carrier and its antitumor activity

A chemically modified heparin-DOCA (HD) conjugate was developed as a drug carrier for cancer therapy. HD conjugate was found to have markedly low anticoagulant activity and to form self-assembled nanoparticles in aqueous condition. We observed that HD conjugate prevented squamous cell carcinoma (SCC) and human umbilical vascular endothelial cell (HUVEC) proliferation during BrdU incorporation assays. Here, we prepared doxorubicin-loaded heparin nanoparticles by entrapping doxorubicin into the amphiphilic HD conjugate by physical interaction and characterized the properties of these nanoparticles using Dynamic Light Scattering (DLS) and Atomic Force Microscope (AFM). In this study, doxorubicin-loaded heparin nanoparticles were designed to improve the antitumor effects of nano-sized particles (range of 180 to 210 nm) at high drug-loading efficiencies in the range 64% to 96%. These doxorubicin-loaded heparin nanoparticles displayed sustained drug release patterns. It was confirmed in vivo toxicity studies that HD conjugate did not induce unexpected side effects and that DHN 20 was safer than free DOX. An in vivo study showed that HD conjugate, doxorubicin and DHN 20 (one of doxorubicin-loaded heparin nanoparticles) induced tumor volume reductions of 43%, 56% and 74%, respectively, relative to the saline treated control. These results suggest that the drug-entrapped with heparin nanoparticles might provide a novel therapy for SCC.

The heparins and cancer: review of clinical trials and biological properties

The association between cancer and thromboembolic disease is a well-known phenomenon and can contribute significantly to the morbidity and mortality of cancer patients. The spectrum of thromboembolic manifestations in cancer patients includes deep vein thrombosis, pulmonary embolism, but also intravascular disseminated coagulation and abnormalities in the clotting system in the absence of clinical manifestations. Unfractionated heparin (UFH) and particularly low molecular weight heparins (LMWH-s) are widely used for the prevention and treatment of thromboembolic manifestations that commonly accompany malignancies. Malignant growth has also been linked to the activity of heparin-like glycosaminoglycans, to neoangiogenesis, to protease activity, to immune function and gene expression. All these factors contribute in the proliferation and dissemination of malignancies. Heparins may play a role in tumour cell growth and in cancer dissemination. The aims of the study are to review the efficiency of heparins in the prevention and treatment of cancer-related thromboembolic complications, and review the biological effects of heparins. Heparins are effective in reducing the frequency of thromboembolic complications in cancer patients. Meta-analyses comparing unfractionated heparins and LMWH-s for the treatment of deep vein thrombosis have shown better outcome with a reduction of major bleeding complications in patients treated with LMWH-s. LMWH have antitumour effects in animal models of malignancy: heparin oligosaccharides containing less than 10 saccharide residues have been found to inhibit the biological activity of basic fibroblast growth factor (bFGF), whereas heparin fragments with less than 18 saccharide residues have been reported to inhibit the binding of vascular endothelial growth factor (VEGF) to its receptors on endothelial cells. It has been shown that LMWH, in contrast with UFH, can hinder the binding of growth factors to their high-affinity receptors as a result of its smaller size. In vitro heparin fragments of less than 18 saccharide residues reduce the activity of VEGF, and fragments of less than 10 saccharide residues inhibit the activity of bFGF. Small molecular heparin fractions have also been shown to inhibit VEGF- and bFGF-mediated angiogenesis in vivo, in contrast with UFH. Moreover, heparin may influence malignant cell growth through other different interrelated mechanisms: inhibition of (1) heparin-binding growth factors that drive malignant cell growth; (2) tumour cell heparinases that mediate tumour cell invasion and metastasis; (3) cell surface selectin-mediated tumour cell metastasis and blood coagulation. The above evidence, together with favourable pharmaco-properties and with a reduction in major bleeding complications, suggests an important role for LMWH-s in thromboprophylaxis and in the therapy of venous thromboembolism in cancer patients. There is sufficient experimental data to suggest that heparins may interfere with various aspects of cancer proliferation, angiogenesis, and metastasis formation. Large-scale clinical trials are required to determine the clinical impact of the above activities on the natural history of the disease.

Low-molecular-weight heparins and angiogenesis

The involvement of the vascular system in malignancy encompasses not only angiogenesis, but also systemic hypercoagulability and a pro-thrombotic state, and there is increasing evidence that pathways of blood coagulation and angiogenesis are reciprocally linked. In fact, cancer atients often display hypercoagulability resulting in markedly increased thromboembolism, which requires anti-coagulant treatment using heparins, for example. Clinical trials reveal that treatment with various low-molecular-weight heparins (LMWHs) improves the survival time in cancer patients receiving chemotherapy compared with those receiving unfractionated standard heparin (UFH) or no heparin treatment, as well as in cancer patients receiving LMWH as thrombosis prophylaxis during primary surgery. This anti-tumor effect of the heparins appears to be unrelated to their anti-coagulant activity, but the mechanisms involved are not fully understood. Tumor growth and spread are dependent on angiogenesis and it is noteworthy that the most potent endogenous pro- and anti-angiogenic factors are heparin-binding proteins that may be affected by systemic treatment with heparins. Heparin and other glycosaminoglycans play a role in vascular endothelial cell function, as they are able to modulate the activities of angiogenic growth factors by facilitating the interaction with their receptor and promoting receptor activation. To date, preclinical studies have demonstrated that only LMWH fragments produced by the heparinase digestion of UFH, i.e. tinzaparin, exert anti-angiogenic effects in any type of tissue in vivo. These effects are fragment-mass-specific and angiogenesis-type-specific. Data on the effect of various LMWHs and UFH on endothelial cell capillary tube formation and proliferation in vitro are also presented. We hope that this paper will stimulate and facilitate future research designed to elucidate whether the anti-angiogenic or anti-tumor effects of commercial LMWHs in their own right are agent specific and whether anti-angiogenic properties increase the anti-tumor properties of the LMWHs in the clinic.

Chemically modified heparin inhibits the in vitro adhesion of nonsmall cell lung cancer cells to P-selectin

PURPOSE

Several independent studies have indicated that tumor metastasis can be inhibited by chemically modified heparin with low anticoagulant activity in the different tumor models. The mechanism of inhibition by the heparin derivatives in part accounts for the interference of tumor cell-platelet interaction mediated by P-selectin.

METHODS

In the present study, we demonstrated that both heparin and chemically modified heparins inhibited the adhesion of nonsmall cell lung cancer (NSCLC) cells to P-selectin under static or flow conditions in vitro.

RESULTS

Flow cytometric analysis with the heparan sulfate-specific monoclonal antibody revealed that both NSCLC cells express heparan sulfate-like proteoglycans. Furthermore, heparinase treatment impaired P-selectin binding, indicating that heparan sulfate-like proteoglycans on the tumor cell surface are implicated in the adhesion of NSCLC cells to P-selectin.

CONCLUSIONS

These findings suggest that some chemically modified heparins with low anticoagulant activity may deserve further testing in the experimental NSCLC treatment protocols.

Mechanisms of disease: the impact of antithrombotic therapy in cancer patients

Venous thromboembolism is a common complication in patients with malignant disease. It is associated with a systemic hypercoagulable state that is secondary to tumor elaboration of tissue factor (the physiological initiator of blood coagulation), activation of other procoagulant mechanisms and downregulation of anticoagulant mechanisms. The consequent generation of activated coagulation serine protease in the peritumoral environment influences tumor growth, invasion, metastasis and angiogenesis. The use of antithrombotic agents, such as the low-molecular-weight heparins, might influence survival in cancer patients through several mechanisms. These mechanisms include a reduction in the frequency of overt and silent fatal thromboembolic events, interference with the activation of blood coagulation and generation of coagulation serine proteases that affect the tumor phenotype, and direct cellular effects of heparin on both epithelial and endothelial tumor elements.

GLB prevents tumor metastasis of Lewis lung carcinoma by inhibiting tumor adhesion actions

AIM

To investigate the inhibitory effect of a new compound of GLB on tumor metastasis in vivo and analyze its actions on tumor cell adhesion to clarify its mechanism.

METHODS

The effect of GLB on tumor metastasis was analyzed by Lewis lung carcinoma model. The pathological morphology of lung alveolar was evaluated by hematoxylin-eosin staining. The effect of GLB on the proliferation of human prostate cancer cell (PC-3M, with a high metastatic characteristic) was studied using the MTT method, and its actions on PC-3M cell adhesion to human umbilical vein endothelial cells (HUVEC) and laminin were analyzed in vitro.

RESULTS

GLB (100 mg/kg/d for 28 d, ig) reduced the number of lung colonies of Lewis lung carcinoma metastasis significantly (P<0.05). Simultaneously, GLB could mitigate the damage of lung alveolar caused by metastasic tumor deposits. In vitro, GLB inhibited dramatically the adhesion of PC-3M cells to HUVEC (P< 0.01) and laminin (P<0.05), without cytotoxic or anti-proliferative action on PC-3M cells.

CONCLUSION

GLB has anti-tumor metastatic activity, which partly depends on its inhibition of tumor adhesion.