Microparticle-associated tissue factor activity in patients with metastatic pancreatic cancer and its effect on fibrin clot formation

Low-Grade Activation of the Extrinsic Coagulation Pathway in Patients with Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) increases the risk for venous thromboembolism. Tissue factor (TF) initiates the extrinsic coagulation pathway (ECP).

AIMS

To investigate the correlation of UC severity with latent ECP activation and TF expression in primary colonic stromal cells (PCSC).

METHODS

In plasma of 38 UC patients (31 males, disease duration 151 ± 25 months) and 28 healthy controls, exosomes and microparticles (EM) were counted. Moreover, TF protein concentration, activities of EM-bound TF (EM-TFa) and coagulation factor VII (FVIIa) were assessed. In PCSC in culture, TF mRNA (F3) from 12 patients with active UC and 7 controls was evaluated.

RESULTS

UC patients had 4- and 3.7- times more exosomes and microparticles, respectively, than controls. TF protein in UC was correlated with several disease severity indices, such as partial Mayo score (pMs; r 0.443), albumin (- 0.362), ESR (0.353), PLT (0.575), and endoscopic Ms (eMs 0.468). EM-TFa was also significantly higher in UC and was correlated to SIBDQ (- 0.64), albumin (- 0.624), disease extent and eMs (0.422). Refractory-to-treatment patients had significantly higher TF protein, EM-TFa and FVIIa. Even within responders, the need for steroids or biologics correlated with a 2.2-times higher EM-TFa. PCSC from active UC maintained higher F3 than controls, which was correlated to pMs (0.56), albumin (- 0.543) and eMs. Treatment with cytokines further upregulated F3. P for all comparisons was < 0.05.

CONCLUSION

Low-grade activation of the ECP associates with clinical, endoscopic UC activity and response to treatment. TF in PCSC mirrors its systemic activity and points to them as a source.

Fibrin Clot Properties in Cancer: Impact on Cancer-Associated Thrombosis

Cancer is associated with a high risk of venous thromboembolism (VTE) and its recurrence. There is evidence that the prothrombotic fibrin clot phenotype, involving the formation of denser and stiffer clots relatively resistant to lysis, occurs in cancer patients, which is in part related to enhanced inflammation, oxidative stress, and coagulation activation, along with the release of neutrophil extracellular traps, indicating that fibrin-related mechanisms might contribute to cancer-associated thrombosis (CAT). Multiple myeloma and its therapy have been most widely explored in terms of altered fibrin characteristics, but prothrombotic fibrin clot features have also been reported in patients with active solid cancer, including lung cancer and gastrointestinal cancer. Patient-related factors such as advanced age, smoking, and comorbidities might also affect fibrin clot characteristics and the risk of CAT. Prothrombotic fibrin clot features have been shown to predict the detection of cancer in patients following VTE during follow-up. Cancer-specific therapies and anticoagulation can favorably modify the phenotype of a fibrin clot, which may alter the course of CAT. It is unclear whether the fibrin clot phenotype might help identify patients with CAT who are more likely to experience recurrent events. This narrative review summarizes the current knowledge on the role of fibrin clot structure and function in cancer patients in the context of CAT.

Incidence and risk factors for venous thromboembolism in the Cancer-VTE Registry pancreatic cancer subcohort

BACKGROUND

This substudy of the Cancer-VTE Registry estimated venous thromboembolism (VTE) incidence and risk factors in pancreatic cancer patients.

METHODS

The Cancer-VTE Registry was an observational study that collected VTE data from patients with solid tumors across Japan. We measured baseline VTE prevalence, and at 1-year follow-up, the cumulative incidence of symptomatic and composite VTE (symptomatic VTE and incidental VTE requiring treatment), bleeding, cerebral infarction/transient ischemic attack (TIA)/systemic embolic event (SEE), and all-cause death.

RESULTS

Of 1006 pancreatic cancer patients, 86 (8.5%) had VTE at baseline, and seven (0.7%) had symptomatic VTE. Significant risk factors of baseline VTE were Eastern Cooperative Oncology Group performance status (ECOG PS) of 1, body mass index (BMI) ≥ 25 kg/m2, history of VTE, D-dimer > 1.2 µg/mL, and hemoglobin < 10 g/dL. At 1-year follow-up, the cumulative incidence of events was higher for pancreatic cancer vs other cancers. Pancreatic cancer patients with VTE vs those without VTE had significantly higher incidences of bleeding, cerebral infarction/TIA/SEE, and all-cause death. No significant risk factors for composite VTE were identified.

CONCLUSIONS

The cumulative incidence of composite VTE during cancer treatment was higher in pancreatic cancer than in other cancer types. Some risk factors for VTE prevalence at cancer diagnosis were identified. Although VTE prevalence at cancer diagnosis did not predict the subsequent 1-year incidence of composite VTE, it was a significant predictor of other events such as all-cause death in pancreatic cancer patients.

TRIAL REGISTRATION

UMIN Clinical Trials Registry; UMIN000024942.

Circulating microvesicles correlate with radiation proctitis complication after radiotherapy

In a large retrospective study, we assessed the putative use of circulating microvesicles (MVs), as innovative biomarkers of radiation toxicity in a cohort of 208 patients with prostate adenocarcinoma overexposed to radiation. The level of platelet (P)-, monocyte (M)- and endothelial (E)-derived MVs were assessed by flow cytometry. Rectal bleeding toxicity scores were collected at the time of blood sampling and during the routine follow-up and were tested for association with MVs using a multivariate logistic regression. MVs dosimetric correlation was investigated using dose volume histograms information available for a subset of 36 patients. The number of PMVs was significantly increased in patients with highest toxicity grades compared to lower grades. Risk prediction analysis revealed that increased numbers of PMVs, and an increased amount of MMVs relative to EMVs, were associated with worst rectal bleeding grade compared to the time of blood sampling. Moreover, a significant correlation was found between PMV and MMV numbers, with the range of doses up to the median exposure (40 Gy) of bladder/rectum and anterior rectal wall, respectively. MVs could be considered as new biomarkers to improve the identification of patients with high toxicity grade and may be instrumental for the prognosis of radiation therapy complications.

Clinical and Biological Data in Patients with Pancreatic Cancer vs. Chronic Pancreatitis-A Single Center Comparative Analysis

INTRODUCTION

In some patients with chronic pancreatitis, the diagnosis of pancreatic cancer can be missed. The objective of the study was to identify clinical and paraclinical data with statistical significance in the differential diagnosis between chronic pancreatitis and pancreatic cancer.

MATERIALS AND METHODS

We conducted a retrospective, observational study on a cohort of 120 patients hospitalized over 3 years. The patients were equally distributed in two groups: group A, with 60 patients with pancreatic cancer, and group B, with 60 patients with chronic pancreatitis. The statistical analysis was carried out by using the R program.

RESULTS

The comparative analysis of pancreatic cancer vs. chronic pancreatitis revealed a stronger link between pancreatic cancer, female gender (p = 0.001) and age over 60 years (p < 0.001). Patients with pancreatic cancer had higher serum values of aspartate aminotransferase (p 0.005), alanine aminotransferase (p 0.006), total bilirubin (p < 0.001), direct bilirubin (p < 0.001), alkaline phosphatase (p 0.030), C-reactive protein (p = 0.049) and uric acid (p 0.001), while patients with chronic pancreatitis presented slightly higher values of amylase (p 0.020) and lipase (p 0.029).

CONCLUSIONS

Female gender, advanced age, elevated aminotransferases, cholestasis markers and uric acid were associated with a higher probability of pancreatic cancer.

Tissue factor: a neglected role in cancer biology

Tissue factor (TF), an initiator of extrinsic coagulation pathway, is positively correlated with venous thromboembolism (VTE) of tumor patients. Beyond thrombosis, TF plays a vital role in tumor progression. TF is highly expressed in cancer tissues and circulating tumor cell (CTC), and activates factor VIIa (FVIIa), which increases tumor cells proliferation, angiogenesis, epithelial-mesenchymal transition (EMT) and cancer stem cells(CSCs) activity. Furthermore, TF and TF-positive microvesicles (TF⁺MVs) activate the coagulation system to promote the clots formation with non-tumor cell components (e.g., platelets, leukocytes, fibrin), which makes tumor cells adhere to clots to form CTC clusters. Then, tumor cells utilize clots to cause its reducing fluid shear stress (FSS), anoikis resistance, immune escape, adhesion, extravasation and colonization. Herein, we review in detail that how TF signaling promotes tumor metastasis, and how TF-targeted therapeutic strategies are being in the preclinical and clinical trials.

Disseminated intravascular coagulation: epidemiology, biomarkers, and management

Disseminated intravascular coagulation (DIC) is a systemic activation of the coagulation system, which results in microvascular thrombosis and, simultaneously, potentially life-threatening haemorrhage attributed to consumption of platelets and coagulation factors. Underlying conditions, e.g. infection, cancer, or obstetrical complications are responsible for the initiation and propagation of the DIC process. This review provides insights into the epidemiology of DIC and the current understanding of its pathophysiology. It details the use of diagnostic biomarkers, current diagnostic recommendations from international medical societies, and it provides an overview of emerging diagnostic and prognostic biomarkers. Last, it provides guidance on management. It is concluded that timely and accurate diagnosis of DIC and its underlying condition is essential for the prognosis. Treatment should primarily focus on the underlying cause of DIC and supportive treatment should be individualised according to the underlying aetiology, patient's symptoms and laboratory records.

Phosphatidylserine-exposing blood cells, microparticles and neutrophil extracellular traps increase procoagulant activity in patients with pancreatic cancer

Patients with pancreatic cancer (PC) are at increased risk of venous thrombosis, but the precise mechanisms of hypercoagulable state in PC remain unclear. We aimed to identify how phosphatidylserine positive (PS⁺) blood cells (BCs), PS⁺ microparticles (MPs) and neutrophil extracellular traps (NETs) regulate procoagulant activity (PCA) in PC, and to assess the relationship between PCA and PC staging. A total of 83 PC patients with different stages of disease were compared to 30 healthy controls, with confocal microscopy and flow cytometry used to assess MP and cellular PS exposure. MP and cell PCA was determined using both fibrin production assays and procoagulant enzyme complex analyses, and coagulation time was further measured. Patients with stage I PC and healthy controls exhibited significantly lower frequencies of PS⁺ MPs and BCs relative to those with more advanced disease, which may partly due to the increased levels of inflammation cytokines in advanced disease. Functional coagulation assays indicated that PS⁺ MPs and BCs derived from patients with stage II/III/IV PC directly contribute to elevated FXa, thrombin, and fibrin formation, and to more rapid coagulation relative to healthy control samples. In inhibition assays, lactadherin, which antagonizes PS, led to a roughly 80% inhibition of PCA. We further used isolated NETs to stimulate endothelial cells, revealing that this led to morphological changes including retraction from cell-cell junctions and a more pro-coagulative phenotype, with DNase I and activated protein C treatment reversing these changes. In patients with stage III PC, curative resection surgery significantly reduced PCA, whereas non-curative surgery did not have a marked impact based on studies of pre- and post-operative samples. These results highlight the pathogenic activity of PS⁺ cells, MPs, and NETs in promoting a prothrombotic environment within individuals suffering from advanced PC. Targeting PS and NETs in these patients may thus be a viable means of preventing pathological thrombosis.

Down-regulation of tissue factor inhibits invasion and metastasis of non-small cell lung cancer

Objective: Tissue factor (TF) is clinically identified as a marker for the detection of various types of cancer as well as the prediction of prognosis for cancer patients. This present study aims to explore the possibility and feasibility to use plasma TF as a biomarker for the prediction of prognosis of patients with non-small cell lung cancer (NSCLC).

Methods: A total of 100 patients with NSCLC at stage I to IV was included in the study, in whom the expression of plasma TF was detected. The Cox proportional-hazards regression model was then used to analyze the collected information, attempting to identify how patients' overall survival (OS) was associated with the expression of plasma TF. To verify the function of TF in invasion and metastasis, the expression of plasma TF was downregulated by SiRNA both in vivo and in vitro.

Results: The expression of plasma TF in NSCLC patients was related to the diagnosis age of the patient. It was noted that patients with high TF expression levels tended to have worse OS performance, which implied that TF could be used as a marker for patients with stage I-IV NSCLC (HR = 2.030, 95% CI = 1.21-3.398, P = 0.007). TF down-regulation inhibited the growth of tumor in vitro as well as the metastasis and invasion of NSCLC cells in vivo.

Conclusion: Both in vivo and in vitro, the invasion and migration of NSCLC cells are suppressed by TF knockdown. TF has the potential to become an effective biomarker for the prediction of prognosis of patients with stage I-IV NSCLC.

Analysis of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microparticles of children with acute lymphoblastic leukemia during induction therapy

OBJECTIVES

Thromboembolism is one of the most common complications during induction therapy of pediatric acute lymphoblastic leukemia (ALL). Procoagulant microparticles in the circulation may cause thromboembolic events. The aim of our study was to determine the levels of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microparticles of children with ALL at diagnosis and during induction therapy.

METHODS

Sixteen precursor B-cell ALL cases and 30 healthy children between 1 and 18 years of age were included. Microparticle levels were analyzed from peripheral blood samples at initial diagnosis, on days 12 and 13 (before and after the first L-asparaginase administration), and on day 33 of ALL-BFM 2000 treatment protocol. Microparticle levels were analyzed by using flow cytometry.

RESULTS

At initial diagnosis, platelet, endothelial-derived, and tissue factor-positive microparticle levels were significantly high in children with ALL. They increased significantly after prednisone and L-asparaginase administration. Apoptotic microparticle levels were not elevated at diagnosis, but remained high during all induction therapy period. None of the patients had evidence of thromboembolism during induction therapy.

CONCLUSION

Our study demonstrated that children with ALL have increased levels of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microprticles during induction therapy. Further studies are needed in larger groups of patients in order to evaluate the risk of elevated microprticles for development of thromboembolism during induction therapy period in children with ALL.

The Ratio of Factor VIIa:Tissue Factor Content within Microvesicles Determines the Differential Influence on Endothelial Cells

Tissue factor (TF)-positive microvesicles from various sources can promote cellular proliferation or alternatively induce apoptosis, but the determining factors are unknown. In this study the hypothesis that the ratio of fVIIa:TF within microvesicles determines this outcome was examined. Microvesicles were isolated from HepG2, BxPC-3, 786-O, MDA-MB-231, and MCF-7 cell lines and microvesicle-associated fVIIa and TF antigen and activity levels were measured. Human coronary artery endothelial cells (HCAECs) were incubated with these purified microvesicles, or with combinations of fVIIa-recombinant TF, and cell proliferation/apoptosis was measured. Additionally, by expressing mCherry-PAR2 on HCAEC surface, PAR2 activation was quantified. Finally, the activation of PAR2 on HCAEC or the activities of TF and fVIIa in microvesicles were blocked prior to addition of microvesicles to cells. The purified microvesicles exhibited a range of fVIIa:TF ratios with HepG2 and 786-O cells having the highest (54:1) and lowest (10:1) ratios, respectively. The reversal from proapoptotic to proliferative was estimated to occur at a fVIIa:TF molar ratio of 15:1, but HCAEC could not be rescued at higher TF concentrations. The purified microvesicles induced HCAEC proliferation or apoptosis according to this ruling. Blocking PAR2 activation on HCAEC, or inhibiting fVIIa or TF-procoagulant function on microvesicles prevented the influence on HCAEC. Finally, incubation of HCAEC with recombinant TF resulted in increased surface exposure of fVII. The induction of cell proliferation or apoptosis by TF-positive microvesicles is dependent on the ratio of fVIIa:TF and involves the activation of PAR2. At lower TF concentrations, fVIIa can counteract the proapoptotic stimulus and induce proliferation.

Altered fibrin clot properties in advanced lung cancer: strong impact of cigarette smoking

BACKGROUND

Dense fibrin networks resistant to lysis have been reported in patients at high risk of thromboembolism. Little is known about fibrin clot properties in cancer. We investigated fibrin clot properties and their determinants in patients with inoperable lung cancer.

METHODS

We enrolled 150 patients with advanced lung cancer prior to therapy and 90 control subjects matched by age, sex, cardiovascular disease, and diabetes. Plasma clot permeability (K_s), turbidimetric analysis of clot formation, clot lysis time (CLT), microparticle-associated tissue factor (MP-TF) activity, thrombin generation, and serum cotinine levels were determined.

RESULTS

Lung cancer patients, compared with controls, formed at a faster rate (- 8.1% lag phase) denser plasma fibrin networks (- 27.2% K_s) that displayed impaired lysis (+ 26.5% CLT), along with 19.5% higher MP-TF activity and 100% higher peak thrombin generated, also after adjustment for potential confounders. Cotinine levels were associated with fibrin maximum absorbance (r = 0.20, p = 0.016) and K_s (r = - 0.50, p < 0.0001) in cancer patients. On multivariate regression analysis, an increase in cotinine levels was a predictor of low K_s (the lower quartile, < 5.8 × 10^-9 cm²; odds ratio = 1.21 per 10 ng/ml, 95% confidence interval 1.02-1.46), but not CLT.

CONCLUSION

Advanced lung cancer is associated with the prothrombotic plasma clot phenotype largely driven by smoking.

Intercellular Vesicular Transfer by Exosomes, Microparticles and Oncosomes - Implications for Cancer Biology and Treatments

Intercellular communication is a normal feature of most physiological interactions between cells in healthy organisms. While cells communicate directly through intimate physiology contact, other mechanisms of communication exist, such as through the influence of soluble mediators such as growth factors, cytokines and chemokines. There is, however, yet another mechanism of intercellular communication that permits the exchange of information between cells through extracellular vesicles (EVs). EVs are microscopic (50 nm−10 μM) phospholipid bilayer enclosed entities produced by virtually all eukaryotic cells. EVs are abundant in the intracellular space and are present at a cells' normal microenvironment. Irrespective of the EV “donor” cell type, or the mechanism of EV biogenesis and production, or the size and EV composition, cancer cells have the potential to utilize EVs in a manner that enhances their survival. For example, cancer cell EV overproduction confers benefits to tumor growth, and tumor metastasis, compared with neighboring healthy cells. Herein, we summarize the current status of knowledge on different populations of EVs. We review the situations that regulate EV release, and the factors that instruct differential packaging or sorting of EV content. We then highlight the functions of cancer-cell derived EVs as they impact on cancer outcomes, promoting tumor progression, metastases, and the mechanisms by which they facilitate the creation of a pre-metastatic niche. The review finishes by focusing on the beneficial (and challenging) features of tumor-derived EVs that can be adapted and utilized for cancer treatments, including those already being investigated in human clinical trials.

Thrombin Generation and Cancer: Contributors and Consequences

The high occurrence of cancer-associated thrombosis is associated with elevated thrombin generation. Tumour cells increase the potential for thrombin generation both directly, through the expression and release of procoagulant factors, and indirectly, through signals that activate other cell types (including platelets, leukocytes and erythrocytes). Furthermore, cancer treatments can worsen these effects. Coagulation factors, including tissue factor, and inhibitors of coagulation are altered and extracellular vesicles (EVs), which can promote and support thrombin generation, are released by tumour and other cells. Some phosphatidylserine-expressing platelet subsets and platelet-derived EVs provide the surface required for the assembly of coagulation factors essential for thrombin generation in vivo. This review will explore the causes of increased thrombin production in cancer, and the availability and utility of tests and biomarkers. Increased thrombin production not only increases blood coagulation, but also promotes tumour growth and metastasis and as a consequence, thrombin and its contributors present opportunities for treatment of cancer-associated thrombosis and cancer itself.

Altered fibrin clot properties in advanced lung cancer: impact of chemotherapy

Background

Faster formation of dense and poorly lyzable fibrin networks have been reported in patients at risk of thromboembolism, including cancer patients. We sought to investigate whether chemotherapy affects plasma fibrin clot properties and their determinants in lung cancer patients.

Methods

In this observational study we enrolled 83 consecutive patients with advanced inoperable lung cancer. Plasma fibrin clot permeability (K_s), turbidimetric analysis of clot formation, clot lysis time (CLT), microparticle-associated tissue factor (MP-TF) activity, and thrombin generation parameters were investigated at enrolment and 3-4 months after standard chemotherapy.

Results

Lung cancer patients after 4 (range, 4-5) cycles of chemotherapy had 35.6% higher D-dimer, 22.1% lower MP-TF activity, and unaltered fibrinogen compared with baseline. Chemotherapy resulted also in 7.5% increased K_s, 8.6% prolonged lag phase, and 5.4% shortened CLT, while thrombin generation was unchanged. Chemotherapy-related differences in clot structure were confirmed by scanning electron microscopy images. Fibrin clot properties after chemotherapy did not differ among histological types of lung cancer, cancer stages or chemotherapy regimens. Interestingly, never smoking (n=13, 16%) was associated with looser post-treatment fibrin structure as reflected by 12.3% higher K_s. Multiple linear regression showed that more advanced cancer stage, higher peak thrombin generation, and higher white blood cell count determined post-treatment change in K_s, while active smoking was associated with change in CLT.

Conclusions

Three-month chemotherapy in lung cancer patients improves clot properties despite unaffected thrombin generation, suggesting that anticancer treatment might quickly produce antithrombotic actions.

The hepatic pre-metastatic niche in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most aggressive malignancies to date, largely because it is associated with high metastatic risk. Pancreatic tumors have a characteristic tendency to metastasize preferentially to the liver. Over the past two decades, it has become evident that the otherwise hostile milieu of the liver is selectively preconditioned at an early stage to render it more conducive to the engraftment and growth of disseminated cancer cells, a concept defined as pre-metastatic niche (PMN) formation. Pancreatic cancer cells exploit components of the tumor microenvironment to facilitate their migration out of the primary tumor, which often involves conversion of pancreatic cancer cells from an epithelial to a mesenchymal phenotype via the epithelial-to-mesenchymal transition. Pancreatic stellate cells and matrix stiffness have been put forward as major drivers of invasiveness in PDAC. Even before the onset of pancreatic cancer cell dissemination, soluble factors and extracellular vesicles secreted by the primary tumor, and possibly even premalignant lesions, help shape a supportive niche in the liver by providing vascular docking sites for circulating tumor cells, enhancing vascular permeability, remodeling the extracellular matrix and recruiting immunosuppressive inflammatory cells. Emerging evidence suggests that some of these tumor-derived factors may represent powerful diagnostic or prognostic biomarkers. Though our understanding of the mechanisms driving PMN formation in PDAC has expanded considerably, many outstanding questions and challenges remain. Further studies dissecting the molecular and cellular events involved in hepatic PMN formation in PDAC will likely improve diagnosis and open new avenues from a therapeutic standpoint.

Fibrin-bearing microparticles: marker of thrombo-embolic events in pancreatic and colorectal cancers

Background

Microparticles (MPs) are plasma membrane-derived extracellular vesicles present in the bloodstream. We have described a specific signature of MPs, called microparticulosome, in colorectal (CRC) and pancreatic (PC) cancers. We observed that levels of fibrin-bearing MPs were significantly increased in patients suffering from PC and CRC in comparison with control groups. Here, we hypothesised that fibrin-MPs may constitute a relevant biomarker of thrombosis associated with cancer. The objective was to compare the microparticulosome signature between patients presenting with thrombo-embolic event and those without.

Methods

Patients with CRC and PC were prospectively included and divided in those with thrombo-embolic events (Group A) and those without (Group B).

MPs were analyzed by flow cytometer, combining the analysis of Annexin V-positive with characterization of their origin and determination of their procoagulant activities. D-dimer levels were measured in the same samples.

Results

We included 118 patients, divided in 19 patients with thrombo embolic event and 99 patients without. Fibrin-bearing MPs levels were significantly higher in presence of thrombo-embolic events, contrary to D-dimers levels. Fibrin-bearing MPs were more frequently produced by erythrocytes, endothelial cells or Ep-CAM+cells than platelets or leukocytes. Overall survival was shorter in case of thrombo-embolic events than without. The most frequent genes expressed by MPs derived from PC or CRC were implicated in metastatic diffusion of tumor cells, drug resistance, coagulation and inflammation.

Conclusion

Circulating MPs, particularly fibrin-bearing MPs, could be used as a new biomarker to predict cancer-associated thrombo-embolic events and poor survival.

Procoagulant microparticles derived from cancer cells have determinant role in the hypercoagulable state associated with cancer

Hypercoagulablity is a common alteration of blood coagulation in cancer patients. However, the procoagulant activity of cancer cells is not sufficient to induce hypercoagulability. The present study was aimed to identify the mechanism with which hypercoagulabilty is produced in the presence of cancer cells. We focused on the analysis of the procoagulant elements carried by cancer cell-derived microparticles (CaCe-dMP) and we evaluated the impact of microparticles associated with the cancer cells from which they stem on thrombin generation. CaCe-dMP from the cancer cells were isolated from the conditioned medium and analyzed for tissue factor (TF) and procoagulant phospholipid expression. Thrombin generation of normal plasma was assessed by the Thrombinoscope (CAT®) in the presence or absence of pancreas adeno-carcinoma cells (BXPC3) or breast cancer MCF7 cells supplemented with the respective CaCe-dMP. Both BXPC3 and MCF7 cells express abundant amounts of active TF. Phosphatidylserine was identified on the surface of CaCe-dMP, unlike the cancer cells themselves. The expression of TFa by the microparticles was significantly higher to that observed on the cancer cells. Culture of the cancer cells with their microparticles resulted in thrombin generation significantly higher as compared to the upper normal limit. In conclusion, cancer cells 'enrich' the microenvironment with procoagulant elements, especially procoagulant micro-particles which express TF and procoagulant phospholipids. The association of cancer cells with procoagulant microparticles is necessary for a state of hypercoagulability, at the level of the tumoral microenvironment. The intensity of the hypercoagulability depends on the histological type of the cancer cells.

The effect of corn trypsin inhibitor, anti-tissue factor pathway inhibitor antibodies and phospholipids on microvesicle-associated thrombin generation in patients with pancreatic cancer and healthy controls

Circulating microvesicles (MVs) are suggested to be important contributors to cancer-associated thrombosis due to the presence of surface-bound procoagulant molecules like tissue factor (TF) and phosphatidylserine (PS). Pancreatic cancer is considered to be one of the most prothrombotic malignancies. The aim of this study was to describe the impact of analytical variables on MV-associated thrombin generation in patients with pancreatic cancer and in healthy controls. MVs were isolated from citrated plasma and added to pooled normal plasma (PNP). Thrombin generation was measured by the calibrated automated thrombogram. The impact of corn trypsin inhibitor (CTI), anti-tissue factor pathway inhibitor (TFPI) antibodies and phospholipids was described. Antibodies against TF were used to assess TF-dependency, and MV-bound PS activity was measured with the Zymuphen MP-activity kit. MVs from the pancreatic cancer patients displayed higher thrombin generation and higher PS-activity than MVs from the healthy control group, while TF-dependency was observed in only 1 out of 13 patient samples. Adequate thrombin generation-curves were only achieved when CTI was omitted and anti-TFPI antibodies were added to PNP prepared in low contact-activating tubes. Addition of phospholipids reduced the significant differences between the two groups, and should be omitted. This modified thrombin generation assay could be useful for measurement of procoagulant circulating MVs, allowing the contribution from MVs affecting both the intrinsic and the extrinsic pathway to be measured.

Patterns of venous thromboembolism risk in patients with localized colorectal cancer undergoing adjuvant chemotherapy or active surveillance: an observational cohort study

BACKGROUND

Venous thromoboembolism (VTE) is a frequent and burdensome complication of metastatic colorectal cancer (CRC). However, the epidemiology of VTE in patients with localized CRC after surgery in curative intent is incompletely understood. In this single-center observational cohort study, we investigate patterns of VTE risk in localized CRC, and define its relationship with baseline risk factors, adjuvant chemotherapy and CRC recurrence.

METHODS

Five-hundred-sixteen patients with stage II/III CRC were included retrospectively at the time of surgery, and followed until the occurrence of VTE, CRC recurrence, or death (median age = 65.1 years, stage II and III: n = 151 (29.5%), n = 361 (70.5%); adjCTX: n = 339 (65.7%)).

RESULTS

During a median follow-up of 2.7 years, 15 VTEs (2.7%) and 116 recurrences (22.5%) occurred, and 46 patients (8.9%) died. Six-month, 1-year, and 5-year VTE risks were 1.6%, 2.0% and 3.2%, respectively. In competing risk time-to-VTE regression, adjCTX was not associated with an increased risk of VTE (Subdistribution hazard ratio = 0.98, 95% CI:0.33-2.88, p = 0.97). The occurrence of disease recurrence strongly increased the risk of VTE (Multi-state model: Transition hazard ratio (THR) = 13.03, 95% CI:4.39-38.74, p < 0.0001)). Conversely, the onset of VTE did not predict for recurrence (THR = 1.95, 95% CI: 0.62-6.16, p = 0.25).

CONCLUSION

VTE risk is very low in localized CRC and does not appear to be increased by adjuvant chemotherapy. Thus, primary thromboprophylaxis is unlikely to result in clinical benefit in this population. The strongest determinant of VTE risk appears to be disease recurrence.

Cancer-associated venous thromboembolism: Burden, mechanisms, and management

Venous thromboembolism (VTE) is a significant health problem in the general population but especially in cancer patients. In this review, we discuss the epidemiology and burden of the disease, the pathophysiology of cancer-associated VTE, and the clinical treatment options for both primary prevention and acute treatment. Overall, the development of VTE in cancer patients is related to increases in morbidity, mortality, and medical costs. However, the incidence of cancer-associated VTE varies due to patient-related factors (e.g. thrombophilia, comorbidities, performance status, history of venous diseases), tumour-related factors (e.g. cancer site, stage, grade), and treatment-related factors (e.g. surgery, chemotherapy, anti-angiogenesis treatment, hormonal and supportive treatment). Furthermore, blood count parameters (e.g. platelets and leukocytes) and biomarkers (e.g. soluble P-selectin and D-dimer) are predictive markers for the risk of VTE in cancer patients and have been used to enhance risk stratification. Evidence suggests that cancer itself is associated with a state of hypercoagulability, driven in part by the release of procoagulant factors, such as tissue factor, from malignant tissue as well as by inflammation-driven activation of endothelial cells, platelets, and leukocytes. In general, low-molecular-weight heparin (LWMH) monotherapy is the standard of care for the management of cancer-associated VTE, as vitamin K antagonists are less effective in cancer patients. Direct oral anticoagulants (DOACs) offer a potentially promising treatment option for cancer patients with VTE, but recommendations concerning the routine use of DOACs should await head-to-head studies with LMWH.

Oligoubiquitination of tissue factor on Lys255 promotes Ser253-dephosphorylation and terminates TF release

Restriction of tissue factor (TF) activity at the cell surface and TF release are critical for prevention of excessive coagulation. This study examined the regulation of TF dephosphorylation and its release through ubiquitination. A plasmid containing the sequence to express the tandem protein TF-tGFP was mutated to include an arginine-substitution at Lys255 within TF. MDA-MB-231 cell line, and HCAEC endothelial cells were transfected and subsequently activated with PAR2-agonist peptide. The wild-type and mutant TF-tGFP were immunoprecipitated from the cell lysates and the ubiquitination and phosphorylation state of TF examined. Analysis of the proteins showed that arginine-substitution of Lys255 within TF prevented its ubiquitination while the wild-type TF-tGFP was oligoubiquitinated. The TF-associated oligoubiquitin chain was estimated to contain up to 4 ubiquitin units, with the linkage formed between Lys63 of one ubiquitin unit, and the C-terminus of the next unit. The Lys255→Arg substitution of TF-tGFP prolonged the phosphorylation of Ser253 within TF, compared to the wild-type TF-tGFP, lengthened the presence of TF-tGFP at the cell surface and extended the duration of TF-tGFP release from cells following PAR2 activation. A biotinylated 19-mer peptide corresponding to the C-terminus of TF (TFc) was used as substrate to show that the ubiquitination of TF was mediated by the Ube2D family of E2-enzymes and involved Mdm2. Moreover, double-phosphorylation of TFc was prerequisite for ubiquitination, with subsequent dephosphorylation of Ser253 by phosphatase PP2A. In conclusion, oligoubiquitination of Lys255 within TF permits PP2A to bind and dephosphorylate Ser253 and occurs to terminate TF release and contain its activity.

Extracellular vesicles from malignant effusions induce tumor cell migration: inhibitory effect of LMWH tinzaparin

Elevated levels of extracellular vesicles (EVs) have been correlated with inflammatory diseases as well as progressive and metastatic cancer. By presenting tissue factor (TF) on their membrane surface, cellular microparticles (MPs) activate both the coagulation system and cell-signaling pathways such as the PAR/ERK pathway. We have shown before that malignant effusions are a rich source of tumor cell-derived EVs. Here, we used EVs from malignant effusions from three different patients after serial low-speed centrifugation steps as recommended by the ISTH (lsEV). Significant migration of human pancreatic carcinoma cells could be induced by lsEVs and was effectively inhibited by pre-incubation with tinzaparin, a low-molecular-weight heparin. Tinzaparin induced tissue factor pathway inhibitor (TFPI) release from tumor cells, and recombinant TFPI inhibited EV-induced tumor cell migration. EVs also induced ERK phosphorylation, whereas inhibitors of PAR2 and ERK suppressed EV-induced tumor cell migration. LsEVs have been characterized by high-resolution flow cytometry and, after elimination of smaller vesicles including exosomes, by further high-speed centrifugation (hsEV). The remaining population consisting primarily of MPs is indeed the main migration-inducing population with tenase activity. Compared to other LMWHs, tinzaparin is suggested to have high potency to induce TFPI release from epithelial cells. The migration-inhibitory effect of TFPI and the interruption of tumor cell migration by inhibitors of PAR2 and ERK suggest that lsEVs induce tumor cell migration by activating the PAR2 signaling pathway. Tinzaparin might inhibit this process at least partly by inducing the release of TFPI from tumor cells, which blocks PAR-activating TF complexes. The clinical relevance of the results is discussed.

Measurement of extracellular vesicles as biomarkers of consequences or cause complications of pathological states, and prognosis of both evolution and therapeutic safety/efficacy

Utility of EVs, as biomarkers of cause or consequence of various pathological complications, and prognosis of blood components' therapy in terms of safety/efficacy and their potential associated hazards, primed by EVs involvements in pro-inflammatory, immunomodulatory and activations of both pro/anti-coagulatory and others associated pathways, as well as various cellular cross talks, are highlighted as the fundamental. Today EVs are becoming the "buzz" words of the current diagnosis, development and research [DDR] strategies, with the aim of ensuring safer therapeutic approaches in the current clinical practices, also incorporating their potential in long term cost effectiveness in health care systems. The main focus of this manuscript is to review the current opinions in some fundamental areas of EVs involvements in health and diseases. Firstly, our goal is highlighting what are EVs/MVs/MPs and how are they generated in physiology, pathology or blood products; classification and significance of EVs generated in vivo; followed by consequences and physiological/pathological induced effects of EVs generation in vivo. Secondly, specific cell origin EVs and association with malignancy; focus on EVs carrying TF and annexin V as a protective protein for harmful effects of EVs, and associations with LA; and incidence of anti-annexin V antibodies are also discussed. Thirdly, utility of EVs is presented: as diagnostic tools of disease markers; prognosis and follow-up of clinical states; evaluation of therapy efficacy; quality and risk assessment of blood products; followed by the laboratory tools for exploring, characterizing and measuring EVs, and/or their associated activity, using our own experiences of capture based assays. Finally, in perspective, the upcoming low volume sampling, fast, reliable and reproducibility and friendly use laboratory tools and the standardization of measurement methods are highlighted with the beneficial effects that we are witnessing in both wound healing and tissue remodeling, with an expected blockbuster status EVs as future therapeutic directions.

Procoagulant microparticles promote coagulation in a factor XI-dependent manner in human endotoxemia

Essentials The procoagulant effects of microparticles (MPs) on coagulation in endotoxemia are not known. MPs from endotoxemia volunteers were evaluated for procoagulant activity in a plasma milieu. MPs from endotoxemia volunteers shortened clotting times and enhanced thrombin generation. MP procoagulant effects were mediated in a factor XI-dependent manner.

SUMMARY

Background Human endotoxemia is characterized by acute inflammation and activation of coagulation, as well as increased numbers of circulating microparticles (MPs). Whether these MPs directly promote coagulation and through which pathway their actions are mediated, however, has not been fully explored. Objectives In this study, we aimed to further characterize endotoxin-induced MPs and their procoagulant properties using several approaches. Methods Enumeration and characterization of MPs were performed using a new-generation flow cytometer. Relative contributions of the extrinsic and intrinsic pathways in MP-mediated procoagulant activity were assessed using plasmas deficient in factor (F) VII or FXI or with blocking antibodies to tissue factor (TF) or FXIa. Results Total MPs and platelet MPs were significantly elevated in plasma at 6 h after infusion of endotoxin in healthy human subjects. MPs isolated from plasma following endotoxin infusion also demonstrated increased TF activity in a reconstituted buffer system. When added to recalcified platelet-poor plasma, these MPs also promoted coagulation, as judged by a decreased clotting time with shortening of the lag time and time to peak thrombin using calibrated automated thrombography (CAT). However, the use of FVII-deficient plasma or blocking antibody to TF did not inhibit these procoagulant effects. In contrast, plasma clotting time was prolonged in FXI-deficient plasma and a blocking antibody to FXIa inhibited all MP-mediated parameters in the CAT assay. Conclusions The initiation of coagulation by cellular TF in endotoxemia is in contrast to (and presumably complemented by) the intrinsic pathway-mediated procoagulant effects of circulating MPs.

Analysis of the potential of cancer cell lines to release tissue factor-containing microvesicles: correlation with tissue factor and PAR2 expression

BACKGROUND

Despite the association of cancer-derived circulating tissue factor (TF)-containing microvesicles and hypercoagulable state, correlations with the incidence of thrombosis remain unclear.

METHODS

In this study the upregulation of TF release upon activation of various cancer cell lines, and the correlation with TF and PAR2 expression and/or activity was examined. Microvesicle release was induced by PAR2 activation in seventeen cell lines and released microvesicle density, microvesicle-associated TF activity, and phoshpatidylserine-mediated activity were measured. The time-course for TF release was monitored over 90 min in each cell line. In addition, TF mRNA expression, cellular TF protein and cell-surface TF activities were quantified. Moreover, the relative expression of PAR2 mRNA and cellular protein were analysed. Any correlations between the above parameters were examined by determining the Pearson's correlation coefficients.

RESULTS

TF release as microvesicles peaked between 30-60 min post-activation in the majority of cell lines tested. The magnitude of the maximal TF release positively correlated with TF mRNA (c = 0.717; p < 0.001) and PAR2 mRNA (c = 0.770; p < 0.001) expressions while the percentage increase correlated with PAR2 mRNA (c = 0.601; p = 0.011) and protein (c = 0.714; p < 0.001). There was only a weak correlation between resting TF release, and microvesicle release. However, TF release in resting cells did not significantly correlate with any of the parameters examined. Furthermore, TF mRNA expression correlated with PAR2 mRNA expression (c = 0.745; p < 0.001).

DISCUSSION AND CONCLUSIONS

In conclusion, our data suggest that TF and PAR2 mRNA, and PAR2 protein are better indicators of the ability of cancer cells to release TF and may constitute more accurate predictors of risk of thrombosis.

Microparticles as Biomarkers of Blood Coagulation in Cancer

Cancer is associated with hypercoagulopathy and increased risk of thrombosis. This negatively influences patient morbidity and mortality. Cancer is also frequently complicated by the development of venous thromboembolism (VTE). Tumor-derived tissue factor (TF)-bearing microparticles (MPs) are associated with VTE events in malignancy. MPs are small membrane vesicles released from many different cell types by exocytic budding of the plasma membrane in response to cellular activation or apoptosis. MPs may also be involved in clinical diseases through expression of procoagulative phospholipids. The detection of TF-expressing MPs in cancer patients may be clinically useful. In lung and breast cancer patients, MPs induce metastasis and angiogenesis and may be indicators of vascular complications. Additionally, MPs in patients with various types of cancer possess adhesion proteins and bind target cells to promoting cancer progression or metastasis. Overexpression of TF by cancer cells is closely associated with tumor progression, and shedding of TF-expressing MPs by cancer cells correlates with the genetic status of cancer. Consequently, TF-expressing MPs represent important markers to consider in the prevention of and therapy for VTE complications in cancer patients.

"Soluble Tissue Factor" in the 21st Century: Definitions, Biochemistry, and Pathophysiological Role in Thrombus Formation

Tissue factor (TF), the main trigger of blood coagulation, is essential for normal hemostasis. Over the past 20 years, heightened intravascular levels and activity of TF have been increasingly perceived as an entity that significantly contributes to venous as well as arterial thrombosis. Various forms of the TF protein in the circulation have been described and proposed to be thrombogenic. Aside from cell and vessel wall-associated TF, several forms of non-cell-associated TF circulate in plasma and may serve as a causative factor in thrombosis. At the present time, no firm consensus exists regarding the extent, the vascular setting(s), and/or the mechanisms by which such TF forms contribute to thrombus initiation and propagation. Here, we summarize the existing paradigms and recent, sometimes paradigm-shifting findings elucidating the structural, mechanistic, and pathophysiological characteristics of plasma-borne TF.

Flamethrowers: blood cells and cancer thrombosis risk

Cancer patients are at an increased risk of venous thromboembolism. The clotting system is activated in most cancer patients, which is reflected by specific parameters such as an increased thrombin generation and elevated D-dimer levels. Blood cells, especially WBCs and platelets, play an important role in this activation process. Neutrophils and monocytes are subpopulations of WBCs that increase the thrombotic potential by different mechanisms. Neutrophils are activated by tumor cells and can release DNA, generating highly thrombogenic neutrophil extracellular traps. Monocytes are able to synthesize and express significant quantities of procoagulant tissue factor on their surfaces upon activation. An increased risk of VTE has been found in patients with solid tumors and elevated platelet count and in those with high-grade gliomas and low platelet count. Small circulating membrane vesicles, also called microparticles (MPs), which largely derive from platelets, contribute to the procoagulant potential. Specifically, procoagulant MPs could play a role in tumor-associated thrombosis in pancreatic cancer. Interventional studies are under way that are investigating the benefits of thromboprophylaxis in patients identified to be at high risk of VTE through risk-scoring models that include blood count parameters. The “flames” thrown by blood cells, such as neutrophil extracellular traps and MPs, although exciting, still have to be investigated for their usefulness in the clinical setting.

Flamethrowers: blood cells and cancer thrombosis risk

Cancer patients are at an increased risk of venous thromboembolism. The clotting system is activated in most cancer patients, which is reflected by specific parameters such as an increased thrombin generation and elevated D-dimer levels. Blood cells, especially WBCs and platelets, play an important role in this activation process. Neutrophils and monocytes are subpopulations of WBCs that increase the thrombotic potential by different mechanisms. Neutrophils are activated by tumor cells and can release DNA, generating highly thrombogenic neutrophil extracellular traps. Monocytes are able to synthesize and express significant quantities of procoagulant tissue factor on their surfaces upon activation. An increased risk of VTE has been found in patients with solid tumors and elevated platelet count and in those with high-grade gliomas and low platelet count. Small circulating membrane vesicles, also called microparticles (MPs), which largely derive from platelets, contribute to the procoagulant potential. Specifically, procoagulant MPs could play a role in tumor-associated thrombosis in pancreatic cancer. Interventional studies are under way that are investigating the benefits of thromboprophylaxis in patients identified to be at high risk of VTE through risk-scoring models that include blood count parameters. The "flames" thrown by blood cells, such as neutrophil extracellular traps and MPs, although exciting, still have to be investigated for their usefulness in the clinical setting.

Preparation and characterization of anti-tissue factor single-chain variable fragment antibody for cancer diagnosis

Tissue factor (TF), which serves as the initiator of the extrinsic blood coagulation cascade, has been found to be overexpressed in various solid tumors, especially brain tumors, pancreatic cancer, and gastric cancer. Overexpression of TF is considered to contribute to the high incidence of thrombotic complications and poor prognosis in patients with such cancers. Therefore, detection or targeting of TF may be a promising approach for the diagnosis and treatment of solid tumors that are known to overexpress the protein. Here, we used the recombinant DNA technology to develop an anti-TF single-chain Fv (scFv) of small size and high affinity for its target. The biochemical characteristics of the anti-TF scFv were evaluated using surface plasmon resonance (SPR) sensing and flow cytometry. The data obtained showed that the affinity of the anti-TF scFv was 2.04 × 10⁻⁸ (KD), and that the protein showed significant binding to the cancer cells. Then, Alexa 647-labeled anti-TF scFv and anti-TF IgG were administered to mice bearing chemically induced spontaneous tumors. The maximum tumor to background ratios of anti-TF scFv and anti-TF IgG were obtained 3 and 24 h after the injections, respectively. This study indicates anti-TF scFv may be suitable as an imaging probe for the diagnosis of solid tumors.

Effect of resection of localized pancreaticobiliary adenocarcinoma on angiogenic markers and tissue factor related pro-thrombotic and pro-angiogenic activity

In this study, 52 patients were studied to elucidate the relative impact of resection of localized pancreaticobiliary adenocarcinoma (PBC) on circulating factors of tumour-associated angiogenesis e.g. tissue factor bearing microparticles (TFMP) and vascular endothelial growth factor (VEGF) and their clinicopathological significance to angiogenesis markers in cancer tissue from PBC patients. Angiogenesis array analysis on serum samples revealed that surgical resection of tumour lesion in PBC patients affects the levels of a panel of angiogenesis-related molecules, including VEGF that was verified by ELISA to significantly reduce (median & IQR: 1003(369-2000) vs. 457(159-834) pg/ml; p<0.05). Correspondingly, a significant decrease in the angiogenic activity (decreased capillary tube formation; p<0.05) of serum samples after the surgery was also found. Despite a decrease in number of circulating TFMP after surgery, this did not reach statistical significance; there was a significant reduction in pro-coagulant activity (prolonged prothrombin time, p<0.001) post-operatively. In addition, the activity of total microparticles (MP activity assay, p<0.05) was decreased significantly. Immunohistochemical staining of tumour tissue revealed a strong correlation between the microvessel density (MVD) and VEGF expression. Also, higher levels of circulating TFMP or TF related activity (prothrombin time) correlated significantly with TF expression and MVD on tumour tissues from PBC patients. These findings suggest that in pancreaticobiliary adenocarcinoma TF related angiogenesis drivers are equally significant to VEGF ones, raising the clinical question of whether the effectiveness of angiogenesis targeting studies could be improved through the 'dual' targeting of these pathways in PBC.