Tissue factor expression, angiogenesis, and thrombosis in pancreatic cancer

Intratumoral tissue factor expression and risk of venous thromboembolism in brain tumor patients

BACKGROUND

Brain tumor patients have an increased risk of venous thromboembolism (VTE). An important role in cancer-related VTE has been suggested for tissue factor (TF), the main initiator of the coagulation cascade. We conducted a prospective cohort study to determine whether expression levels of TF in brain tumors are associated with future VTE.

PATIENTS AND METHODS

We immunohistochemically determined TF-expression in brain tumor specimens of 96 adult patients (8 low-grade and 82 high-grade gliomas, 6 embryonal tumors) that were included in the Vienna Cancer and Thrombosis Study (CATS). Each patient was prospectively followed until the occurrence of VTE and/or death within a period of two years or loss of follow-up.

RESULTS

Fifteen brain tumor patients (15.6%) developed VTE during follow-up. Seventy-seven brain tumors (80.2%) stained positive for TF. Staining was strong in 13 (13.5%), moderate in 64 (66.7%) and negative in 19 (19.8%) tumors. No statistically significant association between TF-expression (negative, focal, widespread) and the occurrence of VTE was found. The hazard ratio (HR) for VTE was 1.30 (95% confidence interval [CI]: 054 - 3.14, p=0.567) when patients with negative-, focal- and widespread TF expression were compared and not statistically significant. Also when tumors were categorized into two groups (focal/widespread versus negative TF-expression), the HR for future VTE was not statistically significant (HR: 1.45, 95% CI: 0.44 - 7.37; p=0.578). An association can still not be definitely excluded, as this study was underpowered.

CONCLUSIONS

Our data indicate that TF-expression levels in brain tumors are not strongly associated with future VTE.

Tissue factor regulates tumor angiogenesis of retinoblastoma via the extracellular signal-regulated kinase pathway

Retinoblastoma, a well-vascularized tumor that is dependent on a very robust angiogenic response, is the most common intraocular malignancy in children. Tissue factor (TF) is known to regulate tumor progression and in the present study we demonstrated that TF regulates tumor angiogenesis of retinoblastoma. In an orthotopic transplantation model of retinoblastoma, TF was selectively expressed in the proliferative area of retinoblastoma including tumor vessels as well as tumor cells, where TF expression was co-localized with endothelial cells of tumor vessels. TF expression progressively increased with fibroblast growth factor-2 (FGF-2)-induced proliferation of human umbilical vein endothelial cells (HUVECs), which was effectively inhibited by blockade of the TF pathway by TF pathway inhibitor (TFPI). In addition, FGF-2-induced angiogenic processes of migration and tube formation of vascular endothelial cells were also effectively suppressed by TFPI, which would be mediated by inhibition of extracellular signal-regulated kinase activation. Therefore, further to our previous report that TF is involved in tumor cell proliferation of retinoblastoma, our current data suggest that blockade of the TF pathway by TFPI could effectively inhibit tumor growth by suppressing tumor cell proliferation and tumor angiogenesis at the same time.

Pancreatic cancer cell and microparticle procoagulant surface characterization: involvement of membrane-expressed tissue factor, phosphatidylserine and phosphatidylethanolamine

Advanced pancreatic cancer is associated with a high risk of patients developing venous thromboembolism. This increased risk is thought to be tumour-driven and associated with tissue factor (TF) and microparticles. The aim of this study was to investigate the role of TF and phospholipid expression in the procoagulant properties of pancreatic cell lines and microparticles. Pancreatic cancer cell lines (MIA-PaCa-2, ASPC-1 and CFPAC-1) were assessed for expression of TF and microparticle release. Procoagulant potential was determined by a prothrombin time assay. Cell surface expression of TF was highest in CFPAC-1, with low expression on ASPC-1 and little/no expression on MIA-PaCa-2. Clotting time (CT) was cell number and TF-dependent (P < 0.001). Blocking of TF resulted in slower CT for CFPAC-1 and ASPC1 and prevented clotting in MIA-PaCa-2. Microparticles were shown to be procoagulant and the majority of procoagulant potential could be removed by passing cell-free media through a 0.1 μm filter. A dose-dependent CT was observed in both ASPC-1 and CFPAC-1 cell-free media. Furthermore, addition of duramycin prevented microparticle-supported coagulation. The data presented suggest a key role for cell and microparticle surface-expressed TF and phospholipids in coagulation and highlight duramycin-mediated disruption of clotting.

The tick-derived inhibitor Ixolaris prevents tissue factor signaling on tumor cells

BACKGROUND

Tissue factor (TF) is frequently overexpressed in cancer cells and correlated with more aggressive tumor phenotypes and poor prognosis. In addition to promoting coagulation-dependent metastasis and cancer-associated thrombosis, tumor cell-expressed TF mediates direct cell signaling involving the protease-activated receptor (PAR) 2. Ixolaris is a tick-derived inhibitor of the TF-factor (F)VIIa-Xa coagulation initiation complex which blocks primary tumor growth and angiogenesis in glioblastoma and melanoma models.

METHODS

In this study we address the anti-tumor effects of Ixolaris in TF-VIIa-PAR2 signaling-dependent breast cancer models, a xenograft model of highly aggressive human MDA-MB-231 mfp cells and a syngeneic model of PAR2-deficient and replete PyMT mouse mammary carcinoma cells.

RESULTS

Ixolaris potently inhibited the procoagulant activity of human MDA-MB-231mfp or murine PyMT breast cancer cells. Ixolaris blocked signaling by the ternary TF-FVIIa-FXa complex, and, surprisingly, at higher concentrations also the binary TF-FVIIa complex on MDA-MB-231 cells. We show that Ixolaris interacts with certain residues in the human VIIa protease domain that are involved in PAR2 cleavage. In contrast to human VIIa, Ixolaris was a poor inhibitor of murine TF-FVIIa signaling and did not attenuate PAR2-dependent tumor growth in a syngeneic mouse model of breast cancer progression.

CONCLUSION

These data show that Ixolaris inhibits PAR2 cleavage specifically by human TF signaling complexes and suggest that Ixolaris may block tumor growth of human cell models with ectopic FVIIa expression through inhibition of direct TF-FVIIa-PAR2 signaling as well as its anticoagulant activity.

Inhibition of tissue factor by ixolaris reduces primary tumor growth and experimental metastasis in a murine model of melanoma

Melanoma is a highly metastatic cancer and there is strong evidence that the clotting initiator protein, tissue factor (TF), contributes to its aggressive pattern. TF inhibitors may attenuate primary tumor growth and metastasis. In this study, we evaluated the effect of ixolaris, a TF inhibitor, on a murine model of melanoma B16F10 cells. Enzymatic assays performed with B16F10 and human U87-MG tumor cells as the TF source showed that ixolaris inhibits the generation of FX in either murine, human or hybrid FVIIa/TF complexes. The effect of ixolaris on the metastatic potential was further estimated by intravenous injection of B16F10 cells in C57BL/6 mice. Ixolaris (250 μg/kg) dramatically decreased the number of pulmonary tumor nodules (4 ± 1 compared to 47 ± 10 in the control group). Furthermore, a significant decrease in tumor weights was observed in primary tumor growth assays in animals treated with ixolaris (250 μg/kg) from days 3 to 18 after a subcutaneous inoculation of melanoma cells. Remarkably, immunohistochemical analyses showed that inhibition of melanoma growth by ixolaris is accompanied by a significant downregulation of both vascular endothelial growth factor (VEGF) expression and microvascular density in the tumor mass. Our data demonstrate that ixolaris targets B16F10 cell-derived TF, resulting in the reduction of both the primary tumor growth and the metastatic potential of melanoma, as well as the inhibition of tumor angiogenesis. Therefore TF may be a potential target for the treatment of this aggressive malignancy.

Venous Thromboembolism in Cancer Patients Undergoing Major Abdominal Surgery: Prevention and Management

Cancer is an important risk factor for venous thrombosis. Venous thromboembolism is one of the most common complications of cancer and the second leading cause of death in these patients. Recent research has given insight into mechanism and various risk factors in cancer patients which predispose to thromboembolism. The purpose of this review is to summarize the current knowledge on the prophylaxis, diagnosis, and management of venous thromboembolism in these patients.

Microparticle-associated tissue factor activity, venous thromboembolism and mortality in pancreatic, gastric, colorectal and brain cancer patients

BACKGROUND

Tissue factor (TF) expression by tumors contributes to tumor growth. Release of TF-positive microparticles (MPs) may contribute to venous thromboembolism (VTE).

OBJECTIVES

To conduct a prospective cohort study to determine whether elevated MP-associated TF (MP-TF) activity is predictive of VTE and mortality in four cancer types.

PATIENTS/METHODS

We determined MP-TF activity in pancreatic, gastric, colorectal and brain cancer patients. We used a chromogenic endpoint assay for all patients and also a chromogenic kinetic assay for patients with pancreatic and brain cancer.

RESULTS

During follow-up, 12/60 (20%) pancreatic, 6/43 (14%) gastric, 12/126 (10%) colorectal and 19/119 (16%) brain cancer patients developed VTE; 46/60 (77%), 30/43 (70%), 47/126 (37%) and 67/119 (56%), respectively, died. MP-TF activity levels were highest in pancreatic cancer. We did not find a statistically significant association of MP-TF activity with the risk of VTE in any of the four cancer types by using two statistical methods. An association of MP-TF activity with the risk of mortality was detected in pancreatic cancer with the endpoint assay (hazard ratio [HR] 1.8 and 95% confidence interval [CI] 1.4-2.3 per doubling of activity, P < 0.001) and the kinetic assay (HR 1.2, 95% CI 1.1-1.4, P < 0.001); adjustment for type of treatment was not performed. In pancreatic cancer, MP-TF activity correlated with D-dimer level (endpoint assay, r = 0.51; chromogenic assay, r = 0.48), and a correlation between assays (r = 0.61) was found.

CONCLUSION

MP-TF activity was not associated with future VTE in pancreatic, gastric, colorectal and brain cancer. However, we found a strong association of MP-TF activity with mortality in pancreatic cancer. MP-TF activity might be reflective of an aggressive pancreatic cancer phenotype.

Cancer and coagulation

Thromboembolism, including both venous and arterial events, occurs commonly amongst patients with cancer. The occurrence of thromboembolism has significant consequences for cancer patients, including direct and indirect associations with mortality, morbidity, requirement for long-term anticoagulant therapy and consumption of healthcare resources. Recent studies have resulted in a better understanding of clinical risk factors and biomarkers of cancer-associated thrombosis, and a risk assessment model incorporating both has now been validated in multiple settings. Thromboprophylaxis with either unfractionated heparin or low-molecular-weight heparins (LMWHs) has been shown to be safe and effective in high-risk settings such as hospitalization for medical illness and the postsurgical period. Emerging new data from randomized studies have focused on outpatient prophylaxis, suggesting potential benefits in this setting as well. Treatment of cancer-associated thrombosis requires long-term anticoagulation with LMWH. Results from ongoing and planned trials of novel anticoagulants in the cancer setting are awaited.

Tumor-derived tissue factor activates coagulation and enhances thrombosis in a mouse xenograft model of human pancreatic cancer

Cancer patients often have an activated clotting system and are at increased risk for venous thrombosis. In the present study, we analyzed tissue factor (TF) expression in 4 different human pancreatic tumor cell lines for the purpose of producing derivative tumors in vivo. We found that 2 of the lines expressed TF and released TF-positive microparticles (MPs) into the culture medium. The majority of TF protein in the culture medium was associated with MPs. Only TF-positive cell lines activated coagulation in nude mice, and this activation was abolished by an anti-human TF Ab. Of the 2 TF-positive lines, only one produced detectable levels of human MP TF activity in the plasma when grown orthotopically in nude mice. Surprisingly, < 5% of human TF protein in plasma from tumor-bearing mice was associated with MPs. Mice with TF-positive tumors and elevated levels of circulating TF-positive MPs had increased thrombosis in a saphenous vein model. In contrast, we observed no difference in thrombus weight between tumor-bearing and control mice in an inferior vena cava stenosis model. The results of the present study using a xenograft mouse model suggest that tumor TF activates coagulation, whereas TF on circulating MPs may trigger venous thrombosis.

Hyperthermia synergizes with tissue factor knockdown to suppress the growth and hepatic metastasis of colorectal cancer in orthotopic tumor model

BACKGROUND

Tissue factor (TF) is a significant risk factor for tumor growth and hepatic metastasis in patients with colorectal cancer (CRC). This study aimed to investigate whether hyperthermia has synergistic anti-tumor effects with TF knockdown in suppressing CRC progression and metastasis in vitro and in vivo.

METHODS

Human colorectal cancer LOVO cells were treated by hyperthermia at 44°C for 2 hr or/and TF siRNA. Then the cells were subjected to colony formation assay. Apoptosis was analyzed by flow cytometry, confocal microscopy, and transmission electron microscopy. The cell migration and invasion abilities were analyzed by wound healing and matrigel assay. In addition, orthotopic nude mice model of CRC was established.

RESULTS

Hyperthermia synergized with TF knockdown to reduce colony formation ability, induce apoptosis, and suppress the migration and invasion of LOVO cells in vitro. Moreover, hyperthermia in combination with TF depletion inhibited the growth and hepatic metastasis of CRC in orthotopic nude mice model. Mechanistically, the synergistic effects were at least partly mediated by inducing JNK mediated apoptosis and suppressing matrix metalloproteinases (MMPs) mediated invasion.

CONCLUSIONS

Hyperthermia in combination with TF-targeted therapy could be a potential approach for CRC treatment.

Thrombosis: simplified

The devastating consequences of venous thromboembolism have forever provided the impetus to explore safe and effective treatment strategies. To date, the pathophysiology and mechanism of thrombosis have been extensively studied and details of new thrombophilic conditions are continually being discovered. Although there has been extensive research detailing various predispositions to thrombosis, uncertainties regarding their appropriate management continue. This review aims to highlight the various challenges involved in identifying those at risk; provide appropriate management options; and lastly present the current views on the development of new anticoagulants that are competing to replace the traditional agents.

Epigallocatechin-3-gallate inhibits proliferation and migration of human colon cancer SW620 cells in vitro

AIM

Epigallocatechin-3-gallate (EGCG) is the major polyphenolic constituent in green tea. The aim of this study is to investigate the effects of EGCG on proliferation and migration of the human colon cancer SW620 cells.

METHODS

Proliferation and migration of SW620 cells were induced by the protease-activated receptor 2-agonist peptide (PAR2-AP, 100 μmol/L) or factor VIIa (10 nmol/L), and analyzed using MTT and Transwell assays, respectively. The cellular cytoskeleton was stained with rhodamine-conjugated phalloidin and examined with a laser scanning confocal fluorescence microscope. The expression of caspase-7, tissue factor (TF) and matrix metalloproteinase (MMP)-9 in the cells was examined using QT-PCR, ELISA and Western blot assays. The activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and nuclear factor-kappa B (NF-κB) signaling pathways was analyzed with Western blot.

RESULTS

Both PAR2-AP and factor VIIa promoted SW620 cell proliferation and migration, and caused cytoskeleton reorganization (increased filopodia and pseudopodia). Pretreatment with EGCG (25, 50, 75, and 100 μg/mL) dose-dependently blocked the cell proliferation and migration induced by PAR2-AP or factor VIIa. EGCG (100 μg/mL) prevented the cytoskeleton changes induced by PAR2-AP or factor VIIa. EGCG (100 μg/mL) counteracted the down-regulation of caspase-7 expression and up-regulation of TF and MMP-9 expression in the cells treated with PAR2-AP or factor VIIa. Furthermore, it blocked the activation of ERK1/2 and NF-κB (p65/RelA) induced by PAR2-AP or factor VIIa.

CONCLUSION

EGCG blocks the proliferation and migration of SW620 cells induced by PAR2-AP and factor VIIa via inhibition of the ERK1/2 and NF-κB pathways. The compound may serve as a preventive and therapeutic agent for colon cancers.

The relationship between tissue factor and cancer progression: insights from bench and bedside

It is now widely recognized that a strong correlation exists between cancer and aberrant hemostasis. Patients with various types of cancers, including pancreatic, colorectal, and gastric cancer, often develop thrombosis, a phenomenon commonly referred to as Trousseau syndrome. Reciprocally, components from the coagulation cascade also influence cancer progression. The primary initiator of coagulation, the transmembrane receptor tissue factor (TF), has gained considerable attention as a determinant of tumor progression. On complex formation with its ligand, coagulation factor VIIa, TF influences protease-activated receptor-dependent tumor cell behavior, and regulates integrin function, which facilitate tumor angiogenesis both in vitro and in mouse models. Furthermore, evidence exists that an alternatively spliced isoform of TF also affects tumor growth and tumor angiogenesis. In patient material, TF expression and TF cytoplasmic domain phosphorylation correlate with disease outcome in many, but not in all, cancer subtypes, suggesting that TF-dependent signal transduction events are a potential target for therapeutic intervention in selected types of cancer. In this review, we summarize our current understanding of the role of TF in tumor growth and metastasis, and speculate on anticancer therapy by targeting TF.

Analysis of incidence and clinical outcomes in patients with thromboembolic events and invasive exocrine pancreatic cancer

BACKGROUND

Pancreatic adenocarcinoma is among the most common malignancies associated with thromboembolic events (TEs); however, reported incidence figures vary significantly and contain small patient cohorts. Pancreatic cancer-specific thrombosis studies examining the correlation between clinical variables, including thrombosis timing and the impact of thrombosis on survival, have not been reported.

METHODS

Survival analyses were performed relating to the development and timing of a TE in 1915 patients administered chemotherapy at Memorial Sloan-Kettering Cancer Center with invasive exocrine pancreatic cancer from January 1, 2000 to December 31, 2009. TE timing, relative to clinical parameters including laboratory data, erythropoietin-stimulating agent use, and body mass index (BMI), were also analyzed.

RESULTS

A thrombosis was identified in 690 (36%) patients. After adjusting for patients with pancreatic surgery and thrombosis (n = 127), developing a TE significantly increased the risk of death (hazard ratio [HR], 2.6; 95% confidence interval [CI], 2.3-2.8; P < .01). Patients with an early TE (within 1.5 months from pancreatic cancer diagnosis) had a significantly higher risk of death (HR, 2.1; 95% CI, 1.7-2.5; P < .01) compared with patients with late TE or no TE. Erythropoietin-stimulating agent use and an elevated international normalized ratio were associated with significantly shorter time to thrombosis. Low BMI was associated with significantly longer time to thrombosis.

CONCLUSIONS

TEs are common in exocrine pancreatic cancer, with coagulopathy, erythropoietin-stimulating agent use, and underweight BMI influencing thrombosis timing. TEs, particularly early ones, confer a significantly worse prognosis, suggesting a biological significance, underscoring the relevance of ongoing prophylaxis trials, and raising the question of whether early TEs should be considered a stratification factor for clinical trials.

Tissue factor, blood coagulation, and beyond: an overview

Emerging evidence shows a broad spectrum of biological functions of tissue factor (TF). TF classical role in initiating the extrinsic blood coagulation and its direct thrombotic action in close relation to cardiovascular risks have long been established. TF overexpression/hypercoagulability often observed in many clinical conditions certainly expands its role in proinflammation, diabetes, obesity, cardiovascular diseases, angiogenesis, tumor metastasis, wound repairs, embryonic development, cell adhesion/migration, innate immunity, infection, pregnancy loss, and many others. This paper broadly covers seminal observations to discuss TF pathogenic roles in relation to diverse disease development or manifestation. Biochemically, extracellular TF signaling interfaced through protease-activated receptors (PARs) elicits cellular activation and inflammatory responses. TF diverse biological roles are associated with either coagulation-dependent or noncoagulation-mediated actions. Apparently, TF hypercoagulability refuels a coagulation-inflammation-thrombosis circuit in “autocrine” or “paracrine” fashions, which triggers a wide spectrum of pathophysiology. Accordingly, TF suppression, anticoagulation, PAR blockade, or general anti-inflammation offers an array of therapeutical benefits for easing diverse pathological conditions.

Low molecular weight heparin downregulates tissue factor expression and activity by modulating growth factor receptor-mediated induction of nuclear factor-κB

Treatment of cancer patients with low molecular weight heparin (LMWH) appears to have beneficial effects. In this study, the influence of low molecular weight heparin (LMWH) on tissue factor (TF) expression and activity in five cell lines from various tissues was analysed and explored. Incubation of cells with LMWH (0-2000μg/ml) resulted in the downregulation of TF mRNA expression which was both LMWH concentration-dependent and time-dependent. Downregulation of TF was also measured as decreased cellular TF antigen and activity. Consistently, incubation of cells with LMWH suppressed the nuclear localisation and the transcriptional activity of NFκB. Decreased TF mRNA was largely achievable by incubating the cells with an NFκB inhibitor alone whilst incubation with betulinic acid to activate NFκB reversed the inhibitory influence of LMWH. Cells were also incubated with a range of concentrations of EGF (0-10ng/ml), bFGF (0-20ng/ml) or VEGF (0-4ng/ml) in the presence or absence of LMWH (200μg/ml) for 24h and TF antigen measured. Inclusion of LMWH reduced TF expression in response to EGF, bFGF or VEGF but TF expression was partially restored by increasing concentrations of the growth factors. We conclude that LMWH downregulates TF expression in vitro through a mechanism that involves interference with the function of growth factors which in turn is mediated through the downregulation of the transcriptional activity of NFκB. This mechanism may also explain some of the beneficial influences attributed to LMWH therapy in the treatment of cancer patients.

Venous thromboembolism in patients with pancreatic cancer: implications of circulating tissue factor

Among cancers, pancreatic cancer is known to be associated with a higher incidence of venous thromboembolism (VTE). The aim of the study was to determine the implication of circulating tissue factor (TF) in VTE related to active pancreatic cancer. One hundred and sixty-four consecutive patients who participated to the Etude des Determinants et Interactions de la Thrombose veineuse (EDITH) study between January 2005 and August 2007 for symptomatic VTE related to active pancreatic cancer (n = 8), active cancer of other location (n = 42) or classified as unprovoked (n = 114) were included. TF activity (TFa) was measured in a one-stage kinetic chromogenic method. There were no differences of median TFa levels between patients with VTE related to cancer of other type than pancreas [2.01 pmol/l range (0.05-43.92)] and patients with unprovoked VTE [1.78 pmol/l (range 0.05-63.72), P = 0.21]. Median TFa levels were higher in patients with VTE related to pancreatic cancer [12.67 pmol/l (range 0.05-112.04)] than in patients with VTE related to cancer of other type [2.01 pmol/l (range 0.05-43.92), P = 0.02]. Higher levels of circulating TFa during the course of pancreatic cancer may explain the higher incidence of VTE associated with this type of cancer.

The impact of thromboprophylaxis on cancer survival: focus on pancreatic cancer

Pancreatic cancer is still a clinical challenge due to its predominantly late diagnosis and the chemoresistance to cytotoxic and target drugs. One of the major complications of pancreatic cancer is venous thromboembolism (VTE). Both ambulatory and hospitalized pancreatic cancer patients are at higher risk of developing VTE. Among patients with unresectable pancreatic cancer, the occurrence of VTE may be associated with a poor prognosis. Furthermore, emerging clinical data strongly suggest that anticoagulant treatment may improve patient survival by decreasing thromboembolic complications as well as by anticancer activity. Given the clinical relevance for both physicians and basic scientists, this article focuses on the experimental and clinical evidence supporting the relation between the coagulation cascade and the invasive and metastatic potential of pancreatic cancer, and suggests that anticoagulant therapy may represent a useful strategy to improve the prognosis of pancreatic cancer patients.

Systematic review of immunohistochemical biomarkers to identify prognostic subgroups of patients with pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) carries a dismal prognosis. There is a need to identify prognostic subtypes of PDAC to predict clinical and therapeutic outcomes accurately, and define novel therapeutic targets. The purpose of this review was to provide a systematic summary and review of available data on immunohistochemical (IHC) prognostic and predictive markers in patients with PDAC.

METHODS

Relevant articles in English published between January 1990 and June 2010 were obtained from PubMed searches. Other articles identified from cross-checking references and additional sources were reviewed. The inclusion was limited to studies evaluating IHC markers in a multivariable setting.

RESULTS

Database searches identified 76 independent prognostic and predictive molecular markers implicated in pancreatic tumour growth, apoptosis, angiogenesis, invasion and resistance to chemotherapy. Of these, 11 markers (Ki-67, p27, p53, transforming growth factor β1, Bcl-2, survivin, vascular endothelial growth factor, cyclo-oxygenase 2, CD34, S100A4 and human equilibrative nucleoside transporter 1) provided independent prognostic or predictive information in two or more separate studies.

CONCLUSION

None of the molecular markers described can be recommended for routine clinical use as they were identified in small cohorts and there were inconsistencies between studies. Their prognostic and predictive values need to be validated further in prospective multicentre studies in larger patient populations. A panel of molecular markers may become useful in predicting individual patient outcome and directing novel types of intervention.

Role of tissue factor in venous thrombosis

Venous thromboembolism (VTE) is a leading cause of morbidity and mortality worldwide. However, the mechanisms by which clots are formed in the deep veins have not been determined. Tissue factor (TF) is the primary initiator of the coagulation cascade and is essential for hemostasis. Under pathological conditions, TF is released into the circulation on small-membrane vesicles termed microparticles (MPs). Recent studies suggest that elevated levels of MP TF may trigger thrombosis. This review provides an overview of the role of TF in VTE.

Tissue factor and cell signalling in cancer progression and thrombosis

The close link between coagulation activation and clinical cancer is well established and recent progress has defined underlying molecular pathways by which tumour cells interact with the haemostatic system to promote cancer progression. Tumour type-specific oncogenic transformations cause constitutive and hypoxia-dependent upregulation of tissue factor (TF) in cancer cells, but TF expressed by vascular, stromal and inflammatory cells also contributes to the procoagulant character of the tumour microenvironment. A growing body of genetic and pharmacological evidence implicates signalling by protease activated receptors (PARs) and specifically by tumour cell-expressed TF-VIIa-PAR2 in the induction of an array of proangiogenic and immune modulating cytokines, chemokines and growth factors. Specific inhibition of this pathway results in attenuated tumour growth and angiogenesis. PARs are increasingly recognised as targets for proteases outside the coagulation system and emerging evidence indicates that alternative protease signalling pathways synergise with the coagulation system to promote tumour growth, angiogenesis and metastasis. The elucidation of new therapeutic targets in tumour-promoting protease signalling pathways requires new diagnostic approaches to identify patients that will benefit from tailored therapy targeting procoagulant or signalling aspects of the TF pathway.

Phase II and coagulation cascade biomarker study of bevacizumab with or without docetaxel in patients with previously treated metastatic pancreatic adenocarcinoma

PURPOSE

Treatment options are limited for advanced pancreatic cancer progressive after gemcitabine therapy. The vascular endothelial growth factor pathway is biologically important in pancreatic cancer, and docetaxel has modest antitumor activity. We evaluated the role of the anti-vascular endothelial growth factor antibody bevacizumab as second-line treatment for patients with metastatic pancreatic cancer.

DESIGN

Patients with metastatic adenocarcinoma of the pancreas who had progressive disease on a gemcitabine-containing regimen were randomized to receive bevacizumab alone or bevacizumab in combination with docetaxel.

RESULTS

Thirty-two patients were enrolled; 16 to bevacizumab alone (Arm A) and 16 to bevacizumab plus docetaxel (Arm B). Toxicities were greater in Arm B with the most common grade 3/4 nonhematologic toxicities including fatigue, diarrhea, dehydration, and anorexia. No confirmed objective responses were observed. At 4 months, 2 of the 16 patients in Arm A and 3 of the 16 patients in Arm B were free from progression. The study was stopped according to the early stopping rule for futility. Median progression-free survival and overall survival were 43 days and 165 days in Arm A and 48 days and 125 days in Arm B. Elevated d-dimer levels and thrombin-antithrombin complexes were associated with decreased survival and increased toxicity.

CONCLUSION

Bevacizumab with or without docetaxel does not have antitumor activity in gemcitabine-refractory metastatic pancreatic cancer. Baseline and on-treatment d-dimer and thrombin-antithrombin complex levels are associated with increased toxicity and decreased survival.

Low molecular weight heparin suppresses tissue factor-mediated cancer cell invasion and migration in vitro

Elevated expression of tissue factor (TF) has been associated with an increased risk of thrombosis in the majority of cancers. Moreover, treatment of cancer patients with low molecular weight heparin (LMWH) appears to have beneficial effects that reach beyond controlling the immediate hypercoagulable state. In this study, we investigated the influence of the treatment of cancer cells with LMWH (0-2,000 μg/ml) on cell invasiveness and migration in cancer cell lines from five separate tissues; pancreatic, breast, colocarcinoma, ovarian and melanoma. The rate of cell invasion across collagen IV-coated membranes was suppressed in all cell lines tested on incubation with 2,000 μg/ml LMWH, but BxPC-3 and MDA-MB-231 cells also responded to the lowest concentration of 20 μg/ml LMWH. Furthermore, the rate of cell migration was reduced to varying extents in all of the cell lines tested on incubation with 20 μg/ml or higher concentrations of LMWH. The decrease in the rates of invasion and migration also strongly correlated with the reduction in TF protein expression and TF activity in these cells following incubation with LMWH. Moreover, the LMWH-mediated decreases in cellular invasion in the most affected cell lines (BxPC-3 and MDA-MB-231) were restored by transfection of the cells with the mammalian pCMV-XL5-TF expression vector allowing independent overexpression of TF. In conclusion, LMWH appears to suppress the rate of cancer cell invasion and migration in vitro, through a mechanism that is at least in part dependent on the TF protein expression and activity in cancer cells.

Tissue factor-bearing microparticles and thrombus formation

Blood microparticles are vesicular structures with a diameter of 100 to 1000 nm that are present in the blood of normal subjects and in patients with various diseases. These microparticles are derived from cells that circulate in the blood and cells associated with the blood vessel wall. Microparticle membranes retain the protein receptors of their parent cells and may retain RNAs and other cytosolic content. On the basis of surface protein expression, microparticles are known to be derived from platelets, granulocytes, monocytes, endothelial cells, smooth muscle cells, and tumor cells. Only a subpopulation of these microparticles expresses tissue factor.

Low molecular weight heparin administration in cancer patients with hypercoagulability-related complications and carrying brain metastases: A case series study

Background. Venous thromboembolism (VTE) and brain metastases (MTS) are significant clinical problems in the cancer patient population. Brain MTS and deep vein thrombosis are life-threatening conditions because of the risk of fatal endocranic hypertension and pulmonary embolism. Low molecular weight heparin (LMWH) is a major treatment for cancer patients suffering from VTE with regard to the management of the acute phase and subsequent secondary prophylaxis. Treatment with anticoagulants is feared because of the risk of triggering a massive intracranial hemorrhage.

Methods. The medical records of patients with hypercoagulability-related complications and carrying brain MTS treated with LMWH, in a 10-year period, were scrutinized. The authors aimed to focus on the occurrence of intracranial hemorrhage in anticoagulated patients; furthermore, data were collected with regard to the characteristics of the administered LMWHs along with the duration and dosing of the anticoagulative treatment.

Results. A total of 38 patients (pts) carrying an intracranial metastatic tumor were administered LMWHs: calcium nadroparin (32 pts); enoxaparin (2 pts); reviparin (2 pts); parnaparin (2 pts). Reason for LMWH therapy: deep vein thrombosis and/or pulmonary embolism (15 pts); superficial thrombophlebitis (15 pts); intracardiac thrombus (1 pt); mild DIC (5 pts); acute DIC (1 pt); Raynaud phenomenon (1 pt); atrial fibrillation (1 pt). Median duration of LMWH therapy: 13 weeks (range 1–52). None of the patients developed clinical and/or radiographic findings imputable to intracranial hemorrhage.

Conclusion. There is no standard medical approach for the management of patients who require anticoagulant treatment and are suffering from brain MTS. These patients as necessary, might be anticoagulated with LMWH and its dose reduction is to be considered.

The Hemostasis Apparatus in Pancreatic Cancer and Its Importance beyond Thrombosis

Laboratory evidence of aberrant coagulation is found in the majority of patients with advanced pancreatic cancer and a clinical consequence of this is the high incidence and prevalence of vascular thromboembolic events. Other sequelae are hypothesized to be the facilitation and acceleration of mechanisms that define the malignant phenotype, such as invasion, trafficking and anchoring, establishing the metastatic niche and inducing angiogenesis. We review the in vitro and preclinical evidence that supports the role of the coagulation apparatus in the metastatic process of pancreatic cancer, with a particular emphasis on interaction of this pathway with clinically-targeted growth factor receptor pathways. Links between hemostasis, angiogenesis and epidermal growth factor pathways and their significance as therapeutic targets are considered.

Venous thromboembolism and cancer: a systematic review

Venous thromboembolism (VTE) is a serious and potentially fatal disorder, which is often associated with a significant impact on the quality of life and on the clinical outcome of cancer patients. The pathophysiology of the association between thrombosis and cancer is complex: malignancy is associated with a baseline hypercoagulable state due to many factors including release of inflammatory cytokines, activation of the clotting system, expression of hemostatic proteins on tumor cells, inhibition of natural anticoagulants, and impaired fibrinolysis. Several risk factors, related to the patient, the disease, and the therapeutic interventions, have been identified as contributing to the occurrence of VTE. There is convincing evidence to recommend the use of heparins or fondaparinux for prevention of VTE in selected cancer patients, and, especially in some particular types of malignancies and cancer treatments. Management of VTE in patients with cancer is more challenging and bleeding complications associated with the use of anticoagulants are significantly higher in cancer patients than in those without malignancy. Important issues that need to be considered in all cases are interference with anticancer therapy, inconvenience of treatment, and impact on quality of life.

Modulation of the oncogene-dependent tissue factor expression by kinase suppressor of ras 1

INTRODUCTION

Tissue factor (TF) is the key trigger of the coagulation cascade and the membrane signalling receptor for coagulation protease, factor VIIa. In cancer, TF has been implicated in tumor cell survival, growth, and angiogenesis, and is upregulated as a result of oncogenic transformation.

MATERIALS AND METHODS

We assayed TF expression and tumourigenicity in mice in the case of human cancer cell lines expressing oncogenic receptor tyrosine kinases. These cells were also subjected to genetic modulation of the kinase suppressor of ras 1 (KSR1), and treated with oncoprotein inhibitors in vitro and in vivo.

RESULTS

Here we show that herceptin, AG1478 and CI-1033, inhibitors of two different members of the ErbB family of oncogenes (HER-2 and EGFR), reduce TF levels in epithelial cancer cells. In EGFR-driven A431 cells, TF upregulation is diminished upon genetic targeting of KSR1, the scaffolding protein involved in EGFR signalling. Conversely, upregulation of KSR1 in A431 cells increases their TF expression and tumourigenicity in mice. The latter property remains dependent on EGFR, as pan-Erb (EGFR) inhibitor, CI-1033, blocks TF promoter activity and inhibits tumour formation by the parental and KSR1 overexpressing A431 cells.

CONCLUSIONS

KSR1 emerges, as an important modulator of TF expression in EGFR-driven cancer cells, which also impacts their aggressiveness in vivo.

Emerging risk stratification approaches to cancer-associated thrombosis: risk factors, biomarkers and a risk score

Cancer patients are well-known to be at increased risk of venous thromboembolism (VTE). However, the risk varies widely between patients and over the natural history of malignancy. Recent data have identified multiple clinical risk factors as well as biomarkers predictive of VTE. Risk factors include patient-associated factors such as age, obesity and medical comorbidities, cancer-associated factors such as site and stage of cancer, and treatment-associated factors, particularly chemotherapy and anti-angiogenic therapy. Biomarkers associated with increased risk of cancer-associated VTE include leukocyte count, platelet count, and levels of tissue factor, P-selectin and D-dimer. This review focuses on the evidence for risk stratification of cancer patients, based on these risk factors and biomarkers, as well as a recently validated predictive model which can be used to identify patients at highest risk. Targeted thromboprophylaxis utilizing model-based and/or biomarker-based approaches may provide an optimal risk-benefit ratio and is currently the focus of ongoing clinical trials.

Immunolocalisation of tissue factor in esophageal cancer is correlated with intratumoral angiogenesis and prognosis of the patient

It has been demonstrated that tissue factor (TF) may be involved in the tumor-derived procoagulatory status and angiogenic modulation in certain solid tumors. In the present study, we examined immunohistochemical localisation of TF in esophageal squamous cell carcinomas (ESCC) from 103 patients. TF immunopositivity was found in 91.3% of all tumor sections, while normal esophageal tissues were immunonegative. Patients were divided into a low TF immunoreactivity group (9 cases of negative and 48 cases of weak positive) and a high TF immunoreactivity group (35 cases of moderate positive and 11 cases of strong positive). TF immunoreactivity was significantly correlated to the presence of distant metastasis (P=0.0014), while it was not correlated to patient's gender, age, tumor size, depth of tumor invasion or lymph node metastasis. Survival analysis revealed that the overall survival rate in the patients that had high TF immunoreactivity was significantly poorer than those with low TF immunoreactivity (P=0.0094). Univariate analysis demonstrated that tumor size (P=0.0095), depth of tumor invasion (P=0.0050), lymph node metastasis (P=0.0045) and distant metastasis (P<0.0001) were effective predictors of prognosis in patients. However, only distant metastasis could independently predict patients' outcomes by the analysis of multivariate proportional hazards regression (P=0.0043). Furthermore, the intratumoral microvessel density (MVD), evaluated by CD34 immunolabeling, indicated that MVD was positively correlated to the TF immunoreactivity (P=0.0056). It is concluded that TF immunopositivity in ESCC tissues is strongly correlated to the intratumoral angiogenesis and to poor patient prognosis.

Venous thromboembolism in malignant gliomas

Malignant gliomas are associated with a very high risk of venous thromboembolism (VTE). While many clinical risk factors have previously been described in brain tumor patients, the risk of VTE associated with newer anti-angiogenic therapies such as bevacizumab in these patients remains unclear. When VTE occurs in this patient population, concern regarding the potential for intracranial hemorrhage complicates management decisions regarding anticoagulation, and these patients have a worse prognosis than their VTE-free counterparts. Risk stratification models identifying patients at high risk of developing VTE along with predictive plasma biomarkers may guide the selection of eligible patients for primary prevention with pharmacologic thromboprophylaxis. Recent studies exploring disordered coagulation, such as increased expression of tissue factor (TF), and tumorigenic molecular signaling may help to explain the increased risk of VTE in patients with malignant gliomas.

Self-production of tissue factor-coagulation factor VII complex by ovarian cancer cells

BACKGROUND

Thromboembolic events are a major complication in ovarian cancer patients. Tissue factor (TF) is frequently overexpressed in ovarian cancer tissue and correlates with intravascular thrombosis. TF binds to coagulation factor VII (fVII), changing it to its active form, fVIIa. This leads to activation of the extrinsic coagulation cascade. fVII is produced by the liver and believed to be supplied from blood plasma at the site of coagulation. However, we recently showed that ovarian cancer cells express fVII transcripts under normoxia and that this transcription is inducible under hypoxia. These findings led us to hypothesise that ovarian cancer cells are intrinsically associated with TF-fVIIa coagulation activity, which could result in thrombosis.

METHODS

In this study, we examined whether ectopically expressed fVII could cause thrombosis by means of immunohistochemistry, RT-PCR, western blotting and flow cytometry.

RESULTS

Ectopic fVII expression occurs frequently in ovarian cancers, particularly in clear cell carcinoma. We further showed that ovarian cancer cells express TF-fVIIa on the cell surface under normoxia and that this procoagulant activity is enhanced by hypoxic stimuli. Moreover, we showed that ovarian cancer cells secrete microparticles (MPs) with TF-fVIIa activity. Production of this procoagulant secretion is enhanced under hypoxia.

CONCLUSION

These results raise the possibility that cancer cell-derived TF-fVIIa could cause thrombotic events in ovarian cancer patients.

Ixolaris, a tissue factor inhibitor, blocks primary tumor growth and angiogenesis in a glioblastoma model

BACKGROUND

The expression levels of the clotting initiator protein Tissue Factor (TF) correlate with vessel density and the histological malignancy grade of glioma patients. Increased procoagulant tonus in high grade tumors (glioblastomas) also indicates a potential role for TF in progression of this disease, and suggests that anticoagulants could be used as adjuvants for its treatment.

OBJECTIVES

We hypothesized that blocking of TF activity with the tick anticoagulant Ixolaris might interfere with glioblastoma progression.

METHODS AND RESULTS

TF was identified in U87-MG cells by flow-cytometric and functional assays (extrinsic tenase). In addition, flow-cytometric analysis demonstrated the exposure of phosphatidylserine in the surface of U87-MG cells, which supported the assembly of intrinsic tenase (FIXa/FVIIIa/FX) and prothrombinase (FVa/FXa/prothrombin) complexes, accounting for the production of FXa and thrombin, respectively. Ixolaris effectively blocked the in vitro TF-dependent procoagulant activity of the U87-MG human glioblastoma cell line and attenuated multimolecular coagulation complexes assembly. Notably, Ixolaris inhibited the in vivo tumorigenic potential of U87-MG cells in nude mice, without observable bleeding. This inhibitory effect of Ixolaris on tumor growth was associated with downregulation of VEGF and reduced tumor vascularization.

CONCLUSION

Our results suggest that Ixolaris might be a promising agent for anti-tumor therapy in humans.

Tumor-derived tissue factor-bearing microparticles are associated with venous thromboembolic events in malignancy

PURPOSE

Despite the strong association between malignant disease and thromboembolic disorders, the molecular and cellular basis of this relationship remains uncertain. We evaluated the hypothesis that tumor-derived tissue factor-bearing microparticles in plasma contribute to cancer-associated thrombosis.

EXPERIMENTAL DESIGN

We developed impedance-based flow cytometry to detect, quantitate, and size microparticles in platelet-poor plasma. We evaluated the number of tissue factor-bearing microparticles in a cohort of cancer patients of different histologies (N = 96) and conducted a case-control study of 30 cancer patients diagnosed with an acute venous thromboembolic event (VTE) compared with 60 cancer patients of similar age, stage, sex, and diagnosis without known VTE, as well as 22 patients with an idiopathic VTE.

RESULTS

Tissue factor-bearing microparticles were detected in patients with advanced malignancy, including two thirds of patients with pancreatic carcinoma. Elevated levels of tissue factor-bearing microparticles were associated VTE in cancer patients (adjusted odds ratio, 3.72; 95% confidence interval, 1.18-11.76; P = 0.01). In cancer patients without VTE, a retrospective analysis revealed a 1-year cumulative incidence of VTE of 34.8% in patients with tissue factor-bearing microparticles versus 0% in those without detectable tissue factor-bearing microparticles (Gray test P = 0.002).The median number of tissue factor-bearing microparticles in the cancer VTE cohort (7.1 x 10(4) microparticles/microL) was significantly greater than both the idiopathic VTE and cancer-no VTE groups (P = 0.002 and P = 0.03, respectively). Pancreatectomy in three patients eliminated or nearly eliminated these microparticles which coexpressed the epithelial tumor antigen, MUC-1.

CONCLUSION

We conclude that tumor-derived tissue factor-bearing microparticles are associated with VTE in cancer patients and may be central to the pathogenesis of cancer-associated thrombosis.

Assessing risk of venous thromboembolism in the patient with cancer

PURPOSE

Patients with cancer are increasingly at risk for venous thromboembolism (VTE). Rates of VTE, however, vary markedly among patients with cancer.

DESIGN

This review focuses on recent data derived from population-based, hospital-based, and outpatient cohort studies of patients with cancer that have identified multiple clinical risk factors as well as candidate laboratory biomarkers predictive of VTE.

RESULTS

Clinical risk factors for cancer-associated VTE include primary tumor site, stage, initial period after diagnosis, presence and number of comorbidities, and treatment modalities including systemic chemotherapy, antiangiogenic therapy, and hospitalization. Candidate predictive biomarkers include elevated platelet or leukocyte counts, tissue factor, soluble P-selectin, and D-dimer. A recently validated risk model, incorporating some of these factors, can help differentiate patients at high or low risk for developing VTE while receiving chemotherapy.

CONCLUSION

Identifying patients with cancer who are most at risk for VTE is essential to better target thromboprophylaxis, with the eventual goal of reducing the burden as well as the consequences of VTE for patients with cancer.

Impact of venous thromboembolism and anticoagulation on cancer and cancer survival

Changes in the hemostatic system and chronic hemostatic activation are frequently observed in patients with cancer, even in the absence of venous thromboembolism (VTE). VTE is a leading cause of death among patients with cancer and contributes to long-term mortality in patients with early as well as advanced-stage cancer. Mounting evidence suggests that components of the clotting cascade and associated vascular factors play an integral part in tumor progression, invasion, angiogenesis, and metastasis formation. Furthermore, there are intriguing in vitro and animal findings that anticoagulants, in particular the low molecular weight heparins (LMWHs), exert an antineoplastic effect through multiple mechanisms, including interference with tumor cell adhesion, invasion, metastasis formation, angiogenesis, and the immune system. Several relatively small randomized controlled clinical trials of anticoagulation as cancer therapy in patients without a VTE diagnosis have been completed. These comprise studies with LMWH, unfractionated heparin, and vitamin K antagonists, with overall encouraging but nonconclusive results and some limitations. Meta-analyses performed for the American Society of Clinical Oncology VTE Guidelines Committee and the Cochrane Collaboration suggest overall favorable effects of anticoagulation on survival of patients with cancer, mainly with LMWH. However, definitive clinical trials have been elusive and questions remain regarding the importance of tumor type and stage on treatment efficacy, the impact of fatal thromboembolic events, optimal anticoagulation therapy, and safety with differing chemotherapy regimens. Although the LMWHs and related agents hold promise for improving outcomes in patients with cancer, additional studies of their efficacy and safety in this setting are needed.