Effects of the chemotherapeutic agent doxorubicin on the protein C anticoagulant pathway

Coagulation factor V in breast cancer: a p53-regulated tumor suppressor and predictive marker for treatment response to chemotherapy

BACKGROUND

Patients with cancer are at an increased risk of developing coagulation complications, and chemotherapy treatment increases the risk. Tumor progression is closely linked to the hemostatic system. Breast cancer tumors express coagulation factor V (FV), an essential factor in blood coagulation. The functional role of FV during treatment with chemotherapy is poorly understood and was explored in this study.

OBJECTIVES

We aimed to investigate the role of FV in breast cancer progression by exploring associations with treatment response, gene regulation, and the functional effects of FV.

METHODS

The receiver operating characteristic plotter was used to explore the predictive value of FV mRNA (F5) expression for treatment with FEC (5-fluorouracil, anthracycline, and cyclophosphamide). Breast cancer cohorts were analyzed to study treatment response to FEC. The effect of chemotherapy on F5 expression, the regulation of F5, and the functional effects of FV dependent and independent of chemotherapy were studied in breast cancer cell lines.

RESULTS

F5 tumor expression was significantly higher in responders to FEC than in nonresponders. In vitro experiments revealed that anthracycline treatment increased the expression of F5. Inhibition and knockdown of p53 reduced the anthracycline-induced F5 expression. Mutation of a p53 half-site (c.158+1541/158+1564) in a luciferase plasmid reduced luciferase activity, suggesting that p53 plays a role in regulating F5. FV overexpression increased apoptosis and reduced proliferation slightly during anthracycline treatment.

CONCLUSION

Our study identified F5 as a p53-regulated tumor suppressor candidate and a promising marker for response to chemotherapy. FV may have functional effects that are therapeutically relevant in breast cancer.

Arterial Stiffness Changes in Adult Cancer Patients Receiving Anticancer Chemotherapy: A Real-World Bicentric Experience

Background Chemotherapy correlates to acute and long-term cardiotoxicity, is reflected clinically by myocardial and vascular endothelial dysfunction, and can cause cardiovascular complications. Thus, early diagnosis of cardiovascular disease in cancer patients undergoing anti-cancer treatment is necessary to enhance long-term survival. Our principal objective in this study was to discern the impact of specific anti-cancer chemotherapeutics and biologics on arterial stiffness alterations before and after the administration. Methods Conducted at Mustafa Bacha University Hospital, Algeria, the study focused on arterial stiffness in anti-cancer chemotherapy patients. Assessments included blood pressure, diabetes, and dyslipidemia, with precise measurements using validated systems, particularly pulse wave velocity (PWV). Various chemotherapy protocols were applied, and statistical analysis with R software (R Foundation for Statistical Computing, Vienna, Austria) maintained a significance level of p=0.05. Key outcomes centered on carotid-femoral PWV and secondary endpoints such as central and peripheral pressures and pulse pressure (PP). Univariate and bivariate analyses were conducted using appropriate statistical tests.  Results A comparative prospective observational study was completed on 58 patients (34 women and 24 men; mean age: 52.64 +/- 12.12 years) treated with anti-cancer chemotherapy agents. Our evaluation included a complete clinical exam, electrocardiogram, Doppler echocardiography, and applanation tonometry with arterial stiffness measurement using PWV. Patients presented significantly higher levels of carotid-femoral PWV, regardless of the chosen chemotherapy protocol, with no return to the initial level after one year of stopping treatment (p-value < 0.01). Moreover, this increase was more significant in patients with diabetes and hypertension and patients treated with monoclonal antibodies or intercalants.  Conclusion This prospective study shows that chemotherapy patients have elevated arterial stiffness, emphasizing the need to assess PWV and monitor cardiovascular risk factors. PP measurement with PWV could improve risk management.

Antithrombin Therapy: Current State and Future Outlook

Antithrombin (AT) is a natural anticoagulant pivotal in inactivating serine protease enzymes in the coagulation cascade, making it a potent inhibitor of blood clot formation. AT also possesses anti-inflammatory properties by influencing anticoagulation and directly interacting with endothelial cells. Hereditary AT deficiency is one of the most severe inherited thrombophilias, with up to 85% lifetime risk of venous thromboembolism. Acquired AT deficiency arises during heparin therapy or states of hypercoagulability like sepsis and premature infancy. Optimization of AT levels in individuals with AT deficiency is an important treatment consideration, particularly during high-risk situations such as surgery, trauma, pregnancy, and postpartum. Here, we integrate the existing evidence surrounding the approved uses of AT therapy, as well as potential additional patient populations where AT therapy has been considered by the medical community, including any available consensus statements and guidelines. We also describe current knowledge regarding cost-effectiveness of AT concentrate in different contexts. Future work should seek to identify specific patient populations for whom targeted AT therapy is likely to provide the strongest clinical benefit.

Metformin inhibits multiple myeloma serum-induced endothelial cell thrombosis by down-regulating miR-532

OBJECTIVES

Thrombotic complications in multiple myeloma (MM) impairs the quality of life of patients. Metformin has a certain effect on anti-thrombosis, but its role and mechanism in MM-induced thrombosis are still uncovered. Therefore, this study evaluated the effect of metformin on MM-induced thrombosis.

METHODS

Human umbilical vein endothelial cells (HUVECs) were exposed to normal serum (15%), MM serum (15%), metformin (0.01 mmol/L), or MM serum and metformin simultaneously. The expression of tissue factor (TF) in HUVECs was detected by flow cytometry and quantitative real-time PCR (qRT-PCR). QRT-PCR was also used to determine the expressions of endothelial protein C receptor (EPCR) and miR-532. The generation of thrombin and activated protein C was measured by thrombin generation and protein C activation assays. And EPCR, extracellular signal-regulated kinase (ERK) 1/2, p38 mitogen activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathway related protein expressions were detected by western blot.

RESULT

MM serum increased the expressions of TF, EPCR and miR-532, and induced thrombin generation and protein C activation in HUVECs. Based on the MM serum treatment, metformin decreased these expressions and inhibited the thrombin generation and protein C activation in HUVECs. However, miR-532 mimic reversed the effect of metformin and promoted the levels of thrombosis related indicators in HUVECs. Moreover, metformin activated the EPCR, ERK 1/2, p38 MAPK and NF-κB pathways but miR-532 mimic suppressed the activation of pathways.

CONCLUSION

Metformin played an inhibitory effect on MM serum-induced HUVEC thrombosis, suggesting that metformin could serve as a novel antithrombotic approach for MM patients.

Zwitterionic choline phosphate conjugated folate-poly (ethylene glycol): a general decoration of erythrocyte membrane-coated nanoparticles for enhanced tumor-targeting drug delivery

Erythrocyte membrane nanosystems have become one of the important research directions of disease treatment, especially for tumor treatment, and can enhance the long circulation time of anti-cancer drugs in vivo, and penetrate and accumulate in the tumor site effectively. However, erythrocyte membranes lack targeting properties and it is necessary to provide tumor-targeting function by modifying erythrocyte membranes. In this study, we report on a novel modification method of an erythrocyte membrane nanosystem to target tumors. Specifically, the tumor-targeting molecule folate-poly (ethylene glycol) (FA-PEG) was modified with a zwitterionic 2-(methyl acryloyoxy) ethyl choline phosphate (MCP) by the Michael addition reaction to obtain MCP-modified FA-PEG (MCP-PEG-FA). Based on the strong "N-P" tetravalent electrostatic interaction between MCP and phosphatidyl choline on the erythrocyte membranes, MCP-PEG-FA can be modified on the erythrocyte membrane encapsulated doxorubicin (DOX) loaded poly(lactic-co-glycolic acid) (PLGA) nanosystem to form a tumor-targeting erythrocyte membrane nanosystem (FA-RBC@PLGA-DOX). The results show that MCP-PEG-FA was synthesized and successfully bonded to the erythrocyte membrane nanosystem, and the FA-RBC@PLGA-DOX nanosystem had a better tumor-targeting function and tumor killing effect compared with those of the nanosystems without FA ligand modification. The universal modification method of erythrocyte membranes is successfully provided and can be applied to the treatment of various diseases.

Novel Mechanisms of Anthracycline-Induced Cardiovascular Toxicity: A Focus on Thrombosis, Cardiac Atrophy, and Programmed Cell Death

Anthracycline antineoplastic agents such as doxorubicin are widely used and highly effective component of adjuvant chemotherapy for breast cancer and curative regimens for lymphomas, leukemias, and sarcomas. The primary dose-limiting adverse effect of anthracyclines is cardiotoxicity that typically manifests as cardiomyopathy and can progress to the potentially fatal clinical syndrome of heart failure. Decades of pre-clinical research have explicated the complex and multifaceted mechanisms of anthracycline-induced cardiotoxicity. It is well-established that oxidative stress contributes to the pathobiology and recent work has elucidated important central roles for direct mitochondrial injury and iron overload. Here we focus instead on emerging aspects of anthracycline-induced cardiotoxicity that may have received less attention in other recent reviews: thrombosis, myocardial atrophy, and non-apoptotic programmed cell death.

Updates on Anticancer Therapy-Mediated Vascular Toxicity and New Horizons in Therapeutic Strategies

Vascular toxicity is a frequent adverse effect of current anticancer chemotherapies and often results from endothelial dysfunction. Vascular endothelial growth factor inhibitors (VEGFi), anthracyclines, plant alkaloids, alkylating agents, antimetabolites, and radiation therapy evoke vascular toxicity. These anticancer treatments not only affect tumor vascularization in a beneficial manner, they also damage ECs in the heart. Cardiac ECs have a vital role in cardiovascular functions including hemostasis, inflammatory and coagulation responses, vasculogenesis, and angiogenesis. EC damage can be resulted from capturing angiogenic factors, inhibiting EC proliferation, survival and signal transduction, or altering vascular tone. EC dysfunction accounts for the pathogenesis of myocardial infarction, atherothrombosis, microangiopathies, and hypertension. In this review, we provide a comprehensive overview of the effects of chemotherapeutic agents on vascular toxicity leading to hypertension, microvascular rarefaction thrombosis and atherosclerosis, and affecting drug delivery. We also describe the potential therapeutic approaches such as vascular endothelial growth factor (VEGF)-B and prokineticin receptor-1 agonists to maintain endothelial function during or following treatments with chemotherapeutic agents, without affecting anti-tumor effectiveness.

Cancer Therapy-Associated Thrombosis

[Figure: see text].

Procoagulant activity in high grade serous ovarian cancer patients following neoadjuvant chemotherapy-The role of the activated protein C pathway

INTRODUCTION

Ovarian cancer patients are at high risk of thrombosis particularly during chemotherapy treatment however the mechanism is not understood. The aim of this study is to investigate the role of the activated protein C (aPC) pathway in the procoagulant activity observed in ovarian cancer patients undergoing neoadjuvant chemotherapy.

PATIENTS AND METHODS

Thrombin generation was determined before and after addition of thrombomodulin (TM) in high grade serous ovarian cancer (HGSOC) patients treated with neoadjuvant chemotherapy (n = 29) compared with HGSOC patients who were chemo naïve (n = 23) and patients with benign tumours (n = 29). Plasma expression of proteins from the aPC pathway was analysed. mRNA expression was determined in endothelial (EA.hy926) and ovarian (OAW42) cell lines following addition of carboplatin and paclitaxel.

RESULTS

Lower levels of ETP (p < 0.007; p < 0.003) and peak thrombin (p < 0.0008; p < 0.0018) were found in the neoadjuvant group compared with both chemo naïve and benign groups. Following addition of TM, ETP (p < 0.0005) and peak thrombin (p < 0.0049) were higher in the neoadjuvant group compared with the benign controls indicating an increase in aPC resistance. Increased TM and lower levels of protein S were found in the neoadjuvant group compared with benign controls (p < 0.05; p < 0.003). Factor V levels were increased in the neoadjuvant group compared with the chemo naïve group (p < 0.05). Carboplatin and paclitaxel altered the expression of EPCR and thrombomodulin in OAW42 cells with a modest effect on EA.hy926 cells.

CONCLUSION

Chemotherapy induced procoagulant activity in HGSOC is associated with an alteration in expression of key members of the aPC pathway. This acquired aPC resistance may explain the procoagulant phenotype associated with ovarian cancer patients undergoing chemotherapy.

Magnetic nanofibers based bandage for skin cancer treatment: a non-invasive hyperthermia therapy

BACKGROUND

The treatment of non-melanoma skin cancer and deadliest malignant melanoma skin cancer are the fifth and ninth most expensive treatments in Medicare, respectively. Moreover, the recurrence of cancer after currently available therapies, that is, surgery or radiotherapy, reduces the patient's life expectancy.

AIMS

In view of this, we fabricated magnetic nanofibrous mat-based bandage to treat skin cancer non-invasively using an external alternating current (AC) magnetic field induced hyperthermia.

METHODS

The Fe₃ O₄ nanoparticles incorporated polycaprolactone (PCL) fibers based bandages were fabricated using the electrospinning technique. The efficacy of the bandage was investigated in vitro using parental/doxorubicin hydrochloride (Dox)-resistant HeLa cells and in vivo using BALB/c mouse model in the presence of an external AC magnetic field (AMF).

RESULTS

The PCL-Fe₃ O₄ fibrous mat-based bandages dissipate heat energy locally on the application of an external AMF and increase the surrounding temperature in a controlled way up to 45°C in a few mins. The in vitro study confirms the elevated temperature could kill parental and Dox-resistant HeLa cells significantly. As the activity of Dox enhanced at a higher temperatures, more than 85% of parental HeLa cells were dead when cells incubated with Dox contained fibrous mat in the presence of AMF for 10 minutes. Further, we confirm the full recovery of chemically induced skin tumors on BALB/c mice within a month after five hyperthermic doses for 15 minutes. Also, there was no sign of inflammation and recurrence of cancer post-therapy.

CONCLUSION

The present study confirms the PCL-Fe₃ O₄ nanofibrous based bandages are unique and compelling to treat skin cancer.

Cardiotoxic Profile and Arterial Stiffness of Adjuvant Chemotherapy for Colorectal Cancer

Background and Purpose

Even though new cancer therapies have improved the overall survival, in some cases they have been associated with adverse effects, including increased cardiotoxicity. The purpose of the present study was to assess the cardiovascular effects of adjuvant chemotherapy for colorectal cancer and mainly the impact on arterial stiffness indices.

Material and Methods

A total of 70 patients with non-metastatic colorectal cancer who were treated either with FOLFOX (n=16) or with XELOX (n=54) adjuvant chemotherapy were included in the study. All patients were subjected to full cardiovascular evaluation at the beginning and the end of chemotherapy. Arterial stiffness was assessed by means of pulse wave velocity (PWV) and augmentation index (Aix) and full laboratory examinations were conducted prior to, and soon after, the termination of chemotherapy.

Results

Patients exhibited significantly higher levels of carotid-radial PWV, carotid femoral RWV and Aix post-chemotherapy (p<0.001); these findings remained significant when examined separately in each treatment subgroup (FOLFOX, XELOX). The observed changes were independent of treatment regimen and baseline patient characteristics. Univariate regression analyses showed that baseline PWVc-r and PWVc-f were the only factors associated with PWVc-r and PWVc-f change, while Aix change was independent of its baseline value.

Conclusion

There is a clear burden in arterial stiffness indices post-adjuvant chemotherapy for colorectal cancer in both chemotherapy groups. This is a finding of important clinical significance, however more prospective studies are required in order to encode the possible mechanisms involved.

Endothelial Protein C Receptor (EPCR), Protease Activated Receptor-1 (PAR-1) and Their Interplay in Cancer Growth and Metastatic Dissemination

Endothelial protein C receptor (EPCR) and protease activated receptor 1 (PAR-1) by themselves play important role in cancer growth and dissemination. Moreover, interactions between the two receptors are essential for tumor progression. EPCR is a cell surface transmembrane glycoprotein localized predominantly on endothelial cells (ECs). It is a vital component of the activated protein C (APC)—mediated anticoagulant and cytoprotective signaling cascade. PAR-1, which belongs to a family of G protein–coupled cell surface receptors, is also widely distributed on endothelial and blood cells, where it plays a critical role in hemostasis. Both EPCR and PAR-1, generally considered coagulation-related receptors, are implicated in carcinogenesis and dissemination of diverse tumor types, and their expression correlates with clinical outcome of cancer patients. Existing data explain some mechanisms by which EPCR/PAR-1 affects cancer growth and metastasis; however, the exact molecular basis of cancer invasion associated with the signaling is still obscure. Here, we discuss the role of EPCR and PAR-1 reciprocal interactions in cancer progression as well as potential therapeutic options targeted specifically to interact with EPCR/PAR-1-induced signaling in cancer patients.

Venous thromboembolism in cancer patients - magnitude of problem, approach, and management

Cancer is hypercoagulable state. Patients with cancer are at high risk to develop venous thromboembolism (VTE). Relative risk of developing VTE is approximately seven times higher in patients with active cancer. The incidence of occult malignancy is 7%-12% in patients with idiopathic deep vein thrombosis (DVT). However, little research has been focused on cancer with thromboembolism. Lowmolecularweight heparin most frequently used pharmacologic agents as recommended by established guidelines. The aim was to evaluate the magnitude of problem in cancer patients and treatment option as per established guidelines. EMBASE, MEDLINE, and PubMed search of the literature were done to evaluate the association of DVT with various malignancy, magnitude of problem, approach, and various guidelines for the management of DVT. References of all publication were also searched to enrich this article for recent update. Thromboprophylaxis in cancer patient is gray zone area. This need lot of investigational work to find highrisk patients who would benefit from primary thromboprophylaxis.

Arterial stiffness in hematologic malignancies

Malignant and cardiovascular disorders are the top causes of mortality worldwide. This article reviews the main literature data and mechanisms linking hematologic malignancies and arterial stiffness, focusing on recent experimental and clinical results. Several links were found in hematologic malignancies between complete blood count and arterial stiffness. Chemotherapy, especially anthracyclines, cyclophosphamide and tyrosine kinase inhibitors, as well as radiotherapy and hematopoietic stem cell transplantation are the main known causes of arterial stiffness increase in hematologic malignancies. The mechanisms of arterial stiffness elevation in hematologic malignancies include an increased oxidative stress, impaired vascular wall homeostasis, endothelial dysfunction and apoptosis of endothelial cells, overexpression of inflammatory cytokines, accelerated atherosclerosis, increased blood viscosity and unstable platelet aggregates. Guidelines regarding cardiovascular health screening and cardiovascular risk scores are necessary for hematologic cancer survivors in order to improve prognosis and quality of life of the patients.

The combined effect of thermal and chemotherapy on HeLa cells using magnetically actuated smart textured fibrous system

Thermal therapy combined with chemotherapy is one of the advanced and efficient methods to eradicate cancer. In this work, we fabricated magnetically actuated smart textured (MAST) fibrous systems and studied their candidacy for cancer treatment. The polycaprolactone-Fe₃ O₄ based MAST fibers were fabricated using electrospinning technique. These MAST fibrous systems contained carbogenic quantum dots as a tracking agent and doxorubicin hydrochloride anticancer drug. Additionally, as fabricated MAST fibrous systems were able to deliver anticancer drug and heat energy simultaneously to kill HeLa cells in a 10 min period in vitro. After treatment, the metabolic activity and morphology of HeLa cells were analyzed. In addition, the mechanism of cell death was studied using flow cytometry. Interestingly, the navigation of these systems in the fluid can be controlled with the application of gradient magnetic field. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 40-51, 2018.

Áinle F. Plasma Thrombin Generation and Sensitivity to Activated Protein C Among Patients With Myeloma and Monoclonal Gammopathy of Undetermined Significance

The etiology of the prothrombotic state in myeloma has yet to be definitively characterized. Similarly, while recent evidence suggests that patients with monoclonal gammopathy of undetermined significance (MGUS) may also be at increased risk of thrombosis, the magnitude and the etiology of this risk have also yet to be defined. The present study aims to characterize patterns of plasma thrombin generation and sensitivity to the anticoagulant activity of activated protein C (APC) at the time of initial diagnosis of myeloma and in response to therapy in comparison to that observed among patients with MGUS and matched, healthy volunteers. Patients presenting with newly diagnosed/newly relapsed myeloma (n = 8), MGUS (n = 8), and matched healthy volunteers (n = 8) were recruited. Plasma thrombin generation was determined by calibrated automated thrombography. Peak thrombin generation was significantly higher in patients with myeloma (383.4 ± 33.4 nmol/L) and MGUS (353.4 ± 16.5 nmol/L) compared to healthy volunteers (276.7 ± 20.8 nmol/L; P < .05). In the presence of APC, endogenous thrombin potential was significantly lower in control plasma (228.6 ± 44.5 nmol/L × min) than in either myeloma (866.2 ± 241.3 nmol/L × min, P = .01) or MGUS plasma (627 ± 91.5 nmol/L × min, P = .003). Within the myeloma cohort, peak thrombin generation was significantly higher at diagnosis (353.2 ± 15.9 nmol/L) than following completion of the third cycle of therapy (282.1 ± 15.2 nmol/L; P < .005). Moreover, sensitivity to APC increased progressively with each cycle of chemotherapy. Further study of the etiology and evolving patterns of hypercoagulability among patients with these conditions is warranted and may have future implications for thromboprophylaxis strategies.

Procoagulant activity in gynaecological cancer patients; the effect of surgery and chemotherapy

BACKGROUND

Gynaecological cancers are associated with high rates of venous thromboembolism (VTE). Studies on ambulatory cancer patients do not support thromboprophylaxis during chemotherapy. Approximately 6-7% of gynaecological cancer patients suffer a postoperative VTE despite Low Molecular Weight Heparin prophylaxis (LMWH). Large cancer studies have shown that Calibrated Automated Thrombogram (CAT) and Microparticles (MP) assays may be useful in predicting VTE but data on gynaecological cancer patients is scarce.

OBJECTIVE

Our objective was to identify whether the CAT assay and MP functional assays have potential as biomarkers predictive of VTE in gynaecological cancer patients.

PATIENTS AND METHODS

Gynaecological cancer patients were investigated before surgery (n=146) and at 5, 14 and 42days post-surgery (n=78). Fourteen additional patients were investigated before chemotherapy and after 3 and 6 cycles of therapy. Thrombin generation was measured before and after addition of thrombomodulin.

RESULTS

Patients with clear cell cancer (CCC) of the ovary and patients with endometrial cancer had higher ETP and peak thrombin compared with patients with benign disease. Patients who developed VTE (n=8) following surgery had enhanced thrombin generation prior to surgery which persisted during the post-operative period despite LMWH prophylaxis. Both neoadjuvant and adjuvant chemotherapy showed increased thrombin generation following addition of thrombomodulin. There were no differences in MP levels during the study.

CONCLUSIONS

CAT assay shows potential as a promising biomarker for the prediction of VTE in gynaecological cancer patients. The identification of high risk patients combined with individualised LMWH prophylaxis might reduce VTE in this high risk group.

Activation of protein C and thrombin activable fibrinolysis inhibitor on cultured human endothelial cells

ESSENTIALS: It is unknown if thrombin activatable fibrinolysis inhibitor (TAFI) and protein C compete on cells. TAFI and protein C activation on endothelial cells was simultaneously quantified. TAFI and protein C do not compete for activation on endothelial cells. TAFI and protein C are independently recognized by the thrombin-thrombomodulin complex.

BACKGROUND

When bound to thrombomodulin (TM), thrombin is a potent activator of protein C (PC) and thrombin activable fibrinolysis inhibitor (TAFI). By binding PC and presenting it to the thrombin-TM complex, endothelial cell PC receptor (EPCR) enhances PC activation. It is unknown whether PC and TAFI compete for the thrombin-TM complex on endothelial cells.

OBJECTIVE

To compare PC and TAFI activation on the surface of cultured human endothelial cells in the absence or presence of JRK1535 and/or CTM1009, inhibitory antibodies directed against EPCR and TM, respectively, and to determine whether PC and TAFI compete with each other for activation.

METHODS

PC and TAFI activation on endothelial cells were compared, and the effect of PC on TAFI activation and TAFI on PC activation was determined in the absence or presence of JRK1535 and/or CTM1009.

RESULTS

In the absence of antibodies, activation of PC was four-fold faster than that of TAFI. Blocking EPCR with JRK1535 resulted in a 53-fold decrease in PC activation and no effect on TAFI activation. Blocking TM with CTM1009 inhibited both TAFI and PC activation. Neither TAFI nor PC competed with each other in the absence or presence of JRK1535.

CONCLUSIONS

PC and TAFI are concurrently activated in a TM-dependent manner and do not compete for the thrombin-TM complex, raising the possibility that they interact with distinct activation complexes. EPCR selectively enhances PC activation so that PC and TAFI activation kinetics become comparable on endothelial cells.

Venous thromboembolism (VTE) and glioblastoma

The risk of venous thromboembolism (VTE) is high for patients with brain tumors (11-20 %). Glioblastoma (GBM) patients, in particular, have the highest risk of VTE (24-30 %). The Khorana scale is the most commonly used clinical scale to evaluate the risk of VTE in cancer patients but its efficacy in patients with GBM remains unclear. The aim of this study is to estimate the frequency of VTE in GBM patients and identify potential risk factors for the development of VTE during adjuvant chemotherapy. Furthermore, we intend to examine whether the Khorana scale accurately predicts the risk of VTE in GBM patients. We retrospectively reviewed the medical records of GBM patients treated at MD Anderson during the years 2005-2011. The study cohort included 440 patients of which 64 (14.5 %) developed VTE after the start of adjuvant treatment. The median time to develop VTE was 6.5 months from the start of adjuvant treatment. On multivariate analysis male sex, BMI ≥ 35, KPS ≤ 80, history of VTE and steroid therapy were significantly associated with the development of VTE. The Khorana scale was found to be an invalid VTE predictive model in GBM patients due to poor specificity. Of the 64 patients who developed a VTE, 36 were treated with anticoagulation, 2 with an IVC filter, and 21 with both. Complications (intracranial hemorrhage, bleeding in other organs and thrombocytopenia) secondary to anticoagulation were reported in 16 % (n = 10). VTE is common in patients with GBM. Our results did not validate the Khorana scale in GBM patients. Additional studies identifying which GBM patients are at highest risk for VTE are needed to enable further evaluation of VTE preventive measures in this selected group.

Thalidomide and multiple myeloma serum synergistically induce a hemostatic imbalance in endothelial cells in vitro

BACKGROUND

Thalidomide (Thal) treatment of patients with multiple myeloma (MM) is associated with vascular thrombosis, but the underlying mechanism is unknown.

OBJECTIVES

To evaluate the hypothesis that Thal, dexamethasone (Dex) and MM serum perturb the hemostatic balance on human umbilical vein endothelial cells (HUVECs).

METHODS

Drugs with or without the serum of MM patients or healthy controls were incubated with HUVECs. Analyses of phosphatidylserine (PS), tissue factor (TF), endothelial protein C receptor (EPCR) and thrombomodulin (TM) were performed using flow cytometry. The production of thrombin and activated protein C (APC) were measured by chromogenic assay. The roles of IL-6 and TNFα in regulating these indicators were also investigated.

RESULTS

We found that Thal or Dex alone could not increase TF and PS expression in HUVECs. However, when pretreated with MM serum, their expression was significantly increased by either Thal or Dex. Concurrent changes were also detected in thrombin generation. In contrast, Thal and Dex had a direct inhibitory effect on the expression of EPCR and TM, and this inhibitory effect was especially significant when MM serum was added. The generation of APC paralleled the expression of EPCR and TM. All of the above outcomes were reversed to a variable extent by anti-IL-6R and anti-TNFα antibodies.

CONCLUSIONS

These findings suggest Thal may act as a procoagulant by altering the balance between procoagulant and anticoagulant proteins on the surface of HUVECs, thereby contributing to thrombogenesis. MM serum plays a synergistic role in this process.

Activation of Protein C in Human Trophoblasts in Culture and Downregulation of Trophoblast Endothelial Protein C Receptor by TNF-α

In mice, trophoblasts are equipped with a potent anticoagulant mechanism, the protein C pathway. In human placenta, no functional studies of the protein C pathway are available. Human first-trimester trophoblasts (CK(++) HLA-G(+/-) Vim(-)) were isolated and kept in culture for a maximum of 48 hours. Activation of protein C on trophoblasts was at least as efficient as in endothelial cells (4.43 × 10 (-) (7) nmol/L/min/cell). Endothelial protein C receptor (EPCR) was expressed in syncytiotrophoblasts and extravillous trophoblasts. Downregulation of the messenger RNA of trophoblast EPCR occurred when trophoblasts were challenged with tumor necrosis factor α, and it could be prevented by unfractionated heparin but not by low-molecular-weight heparin at therapeutic doses. In conclusion, there is a functional protein C pathway on human first-trimester trophoblasts which can be modulated by inflammation. This finding has implications for the pathogenesis and prevention of placenta-mediated obstetric complications.

Three-dimensional microenvironment confers enhanced sensitivity to doxorubicin by reducing p53-dependent induction of autophagy

Preclinical studies of anticancer drugs are typically performed using cancer cell lines maintained in two-dimensional (2D) cultures, ignoring the influences of the extracellular matrix (ECM) and three-dimensional (3D) microenvironment. In this study, we evaluated the microenvironmental control of human breast cancer cells responses to doxorubicin (DOXO) using the 3D laminin-rich ECM (3D lrECM) cell culture model. Under 3D culture conditions, MCF-7 cells displayed drastic morphological alterations, a decrease in proliferation and elevated sensitivity to DOXO. Interestingly, the chemotherapy-mediated activation of autophagy was compromised in the 3D matrix, suggesting an association between the increased cytotoxicity of DOXO and hindered autophagy induction. Indeed, while chloroquine or ATG5 knockdown potentiated DOXO-induced cell death under the 2D culture conditions, the autophagy inducer rapamycin improved the resistance of 3D-cultured cells to this drug. Moreover, in the monolayer-cultured cells, DOXO treatment led to increases in p53 and DRAM-1 expression, which is a p53-dependent activator of autophagy that functions in response to DNA damage. Conversely, p53 and DRAM-1 expression was impaired in 3D-cultured cells. The knockdown of p53 by shRNA blocked DRAM-1 activation, impaired autophagy induction and sensitized only those cells maintained under 2D conditions to DOXO. In addition, 2D-cultured MDA-MB-231 cells (a p53-mutated breast cancer cell line) not only showed increased sensitivity to DOXO compared with MCF-7 cells but also failed to induce DRAM-1 expression or autophagy. Similar to p53 silencing, DRAM-1 knockdown potentiated DOXO cytotoxicity only in 2D-cultured cells. These results suggest that the 3D tissue microenvironment controls tumor cell sensitivity to DOXO treatment by preventing p53-DRAM-autophagy axis activation.

Urotensin II inhibits doxorubicin-induced human umbilical vein endothelial cell death by modulating ATF expression and via the ERK and Akt pathway

Background and Purpose

Regulation of the homeostasis of vascular endothelium is critical for the processes of vascular remodeling and angiogenesis under physiological and pathological conditions. Urotensin II (U-II), a potent vasoactive peptide, participates in vascular and myocardial remodeling after injury. We investigated the protective effect of U-II on doxorubicin (DOX)-induced apoptosis in cultured human umbilical vein endothelial cells (HUVECs) and the potential mechanisms involved in this process.

Experimental Approach

Cultured HUVECs were treated with vehicle, DOX (1 µM), U-II, or U-II plus DOX. Apoptosis was evaluated by DNA strand break level with TdT-mediated dUTP nick-end labeling (TUNEL) staining. Western blot analysis was employed to determine the related protein expression and flow cytometry assay was used to determine the TUNEL positive cells.

Key Results

U-II reduced the quantity of cleaved caspase-3 and cytosol cytochrome c and increased Bcl-2 expression, which results in protecting HUVECs from DOX-induced apoptosis. U-II induced Activating transcription factor 3 (ATF3) at both mRNA and protein levels in U-II-treated cells. Knockdown of ATF3 with ATF3 siRNA significantly reduced ATF3 protein levels and U-II protective effect under DOX-treated condition. U-II downregulated p53 expression in DOX-induced HUVECs apoptosis, and it rapidly activated extracellular signal-regulated protein kinase (ERK) and Akt. The DOX induced change of p53 was not affected by U-II antagonist (urantide) under ATF-3 knockdown. The inhibitory effect of U-II on DOX-increased apoptosis was attenuated by inhibitors of ERK (U0126) and PI3K/Akt (LY294002).

Conclusion and Implications

Our observations provide evidence that U-II protects HUVECs from DOX-induced apoptosis. ERK-Akt phosphorylation, ATF3 activation, and p53 downregulation may play a signal-transduction role in this process.

Doxorubicin-induced vascular toxicity--targeting potential pathways may reduce procoagulant activity

INTRODUCTION

Previous study in mice using real-time intravital imaging revealed an acute deleterious effect of doxorubicin (DXR) on the gonadal vasculature, as a prototype of an end-organ, manifested by a reduction in blood flow and disintegration of the vessel wall. We hypothesized that this pattern may represent the formation of microthrombi. We aimed to further characterize the effect of DXR on platelets' activity and interaction with endothelial cells (EC) and to examine potential protectants to reduce DXR acute effect on the blood flow.

METHODS

The effect of DXR on platelet adhesion and aggregation were studied in vitro. For in vivo studies, mice were injected with either low molecular weight heparin (LMWH; Enoxaparin) or with eptifibatide (Integrilin(©)) prior to DXR treatment. Testicular arterial blood flow was examined in real-time by pulse wave Doppler ultrasound.

RESULTS

Platelet treatment with DXR did not affect platelet adhesion to a thrombogenic surface but significantly decreased ADP-induced platelet aggregation by up to 40% (p<0.001). However, there was a significant increase in GPIIbIIIa-mediated platelet adhesion to DXR-exposed endothelial cells (EC; 5.7-fold; p<0.001) reflecting the toxic effect of DXR on EC. The testicular arterial blood flow was preserved in mice pre-treated with LMWH or eptifibatide prior to DXR (P<0.01).

CONCLUSIONS

DXR-induced acute vascular toxicity may involve increased platelet-EC adhesion leading to EC-bound microthrombi formation resulting in compromised blood flow. Anti-platelet/anti-coagulant agents are effective in reducing the detrimental effect of DXR on the vasculature and thus may serve as potential protectants to lessen this critical toxicity.

The protein C pathway in cancer metastasis

Cancer is frequently associated with activation of blood coagulation, which in turn has been suggested to promote tumor growth and metastasis. Indeed, low molecular weight heparin treatment significantly prolongs the survival of a wide variety of patients with cancer. Based on this notion that anticoagulant treatment seems to benefit cancer patients, recent experiments aimed to elucidate the importance of the natural anticoagulant protein C pathways in cancer progression. Interestingly, these experiments showed that the repeated administration of exogenous activated protein C limits cancer cell extravasation in experimental animal models. In line, reducing endogenous activated protein C activity dramatically increased the number of experimental metastasis. These data thus strongly suggest that exogenous activated protein C administration may be a novel therapeutic avenue to limit cancer metastasis thereby prolonging overall survival of cancer patients. The current review provides an overview of recent data on the role of the protein C pathway in cancer metastasis. It discusses the potential of activated protein C as a novel target to reduce cancer progression, it points to several limitations of activated protein C administration in the setting of cancer cell metastasis and it suggest zymogen protein C as an attractive alternative.

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.

Endothelial protein C receptor 1651C/G polymorphism and soluble endothelial protein C receptor levels in women with idiopathic recurrent miscarriage

High levels of soluble endothelial protein C receptor (EPCR) induce coagulation dysfunction by inhibiting protein C activation, and activated protein C (APC) activity. We tested whether EPCR 1651C/G promoter variant and changes in plasma soluble EPCR levels are risk factors for idiopathic recurrent spontaneous miscarriage (RSM). A case-control study involving 283 RSM cases and 380 age and BMI-matched control women. EPCR 1651C/G genotyping was performed by PCR-RFLP method. Plasma-soluble EPCR levels were measured with ELISA. The 1651G allele frequency and C/G genotype were significantly higher in RSM cases than controls; none of the cases or control participants was a 1651G/G homozygote. Lower soluble EPCR levels were seen in RSM cases compared to controls, and higher soluble EPCR levels were seen in 1651C/G compared to 1651C/C carriers in cases and controls. Lower soluble EPCR levels were seen in cases, both in 1651C/C (P = 0.0046) and 1651C/G (P = 0.0032) genotype carriers. Multivariate analysis demonstrated strong association of EPCR 1651C/G [P = 0.011; adjusted odds ratio (aOR) (95% confidence interval [CI] = 3.13 (1.31-7.60)], but not soluble EPCR plasma levels [P = 0.067; aOR (95% CI) = 1.01 (1.00-1.10)], with increased RSM risk. In addition, smoking was independently associated with increased RSM risk [P = 0.002; aOR (95% CI) = 2.86 (1.48-5.52)]. EPCR 1651C/G polymorphism and elevated soluble EPCR levels but low soluble EPCR levels increase the risk of idiopathic RSM. Replication studies on other racial groups, and other EPCR gene variants, are warranted.

Breast cancer chemotherapy induces the release of cell-free DNA, a novel procoagulant stimulus

BACKGROUND

Thrombosis is a common complication for breast cancer patients receiving chemotherapy. However, the mechanisms by which breast cancer chemotherapeutic agents increase this risk are largely uncharacterized. Nucleic acids released by injured cells may enhance coagulation via the activation of the contact pathway.

OBJECTIVES

In this study, we examined the effects of breast cancer chemotherapy agents on the release of cell-free DNA (CFDNA) and its relationship to thrombin generation using in vitro and in vivo methods.

METHODS

CFDNA release and thrombin-antithrombin (TAT) levels were measured in plasma of breast cancer patients and healthy mice receiving chemotherapy. Venous whole blood and cultured cells were exposed to chemotherapy and CFDNA release and levels of DNA-histone complexes were measured. The procoagulant activity of isolated CFDNA was measured with calibrated, automated thrombin generation.

RESULTS

Breast cancer patients receiving chemotherapy had elevated levels of CFDNA 24 h post-chemotherapy, a time-point at which elevated thrombin-antithrombin levels have been previously reported. Treatment of healthy mice with doxorubicin, epirubicin and 5-fluorouracil increased CFDNA release, with a corresponding elevation in TAT complex formation. Venous whole blood and neutrophils incubated with chemotherapeutic agents had elevated CFDNA in plasma or cell supernatants. In addition, incubation of venous whole blood with chemotherapy decreased histone-DNA complex levels. CFDNA released from epirubicin-treated whole blood significantly elevated thrombin generation in a dose-dependent manner, and involved activation of the contact pathway.

CONCLUSIONS

Release of CFDNA from chemotherapy-injured cells may represent a novel mechanism by which thrombosis is triggered in cancer patients.

The chemotherapy metabolite acrolein upregulates thrombin generation and impairs the protein C anticoagulant pathway in animal-based and cell-based models

BACKGROUND

Thrombosis is a common complication in cancer patients receiving chemotherapy regimens that include cyclophosphamide. However, the mechanisms by which these agents increase this risk are largely uncharacterized.

OBJECTIVES

To examine the effects of cyclophosphamide and its metabolite acrolein on procoagulant and anticoagulant pathways in both cell-based and animal-based models.

METHODS

Thrombin and activated protein C (APC) generation were measured in defibrinated plasma exposed to acrolein-treated endothelial and smooth muscle cells. Tissue factor (TF) activity was measured on acrolein-treated cells. Cell surface levels of phosphatidylserine, TF, endothelial protein C receptor and thrombomodulin were measured. Healthy BALB/c mice received injections of saline (control), acrolein, or cyclophosphamide; blood was collected, and plasma thrombin-antithrombin (TAT) complex, protein C and APC levels were analyzed.

RESULTS

Exposure of acrolein-treated endothelial and smooth muscle cells to defibrinated plasma increased thrombin generation in the plasma. This was associated with enhanced phosphatidylserine exposure and/or increased TF activity on acrolein-treated cells. Despite elevated levels of thrombin generation, plasma APC levels were not elevated. In vivo, treatment of mice with cyclophosphamide and acrolein resulted in elevations of plasma TAT complex levels, whereas APC levels remained low.

CONCLUSIONS

This is the first study to examine thrombin generation and the APC pathway in chemotherapy-treated mice. Cyclophosphamide and acrolein appear to upregulate procoagulant pathways, while impairing endogenous anticoagulant pathways. This may explain, in part, the increased risk of thrombosis observed in cancer patients receiving cyclophosphamide-containing chemotherapy.

Impact of chemotherapy on thrombin generation and on the protein C pathway in breast cancer patients

Although thromboembolism is a problematic complication of chemotherapy, the pathogenic mechanisms by which chemotherapeutic agents exert prothrombotic effects in vivo are unclear.The objective of this study was to examine the effects of adjuvant chemotherapy on thrombin generation, the protein C anticoagulant pathway, and microparticle tissue factor (MP TF) activity in 26 breast cancer patients (stages I to III). The patients received cyclophosphamide, 5-fluorouracil, and methotrexate, epirubicin, or doxorubicin. Plasma samples were collected on day 1 (baseline), day 2, and day 8 for the first 2 cycles of chemotherapy. Levels of thrombin-antithrombin (TAT) complexes, MP TF activity, and components of the protein C anticoagulant pathway, including protein C, activated protein C (APC), soluble thrombomodulin (sTM), and soluble endothelial protein C receptor (sEPCR), were measured. Compared to prechemotherapy baseline levels, plasma TAT, protein C, and APC were significantly different following the administration of chemotherapy (p < 0.01 for each). Plasma TAT was higher in cycle 1, day 2, and cycle 2, day 8, compared to baseline. Plasma protein C levels were lower in cycle 2, day 8, whereas plasma APC levels were lower in cycle 2, day 1, and cycle 2, day 8. No significant changes were found in plasma sEPCR, sTM, or MP TF activity. This study suggests that adjuvant chemotherapy in women with breast cancer increases thrombin generation and impairs the endothelium-based protein C anticoagulant pathway.

Endogenous activated protein C is essential for immune-mediated cancer cell elimination from the circulation

Fibrinogen and platelets play an important role in cancer cell survival in the circulation by protecting cancer cells from the immune system. Moreover, endogenous activated protein C (APC) limits cancer cell extravasation due to sphingosine-1-phosphate receptor-1 (S(1)P(1)) and VE-cadherin-dependent vascular barrier enhancement. We aimed to study the relative contribution of these two mechanisms in secondary tumor formation in vivo. We show that fibrinogen depletion limits pulmonary tumor foci formation in an experimental metastasis model in C57Bl/6 mice but not in NOD-SCID mice lacking a functional immune system. Moreover, we show that in the absence of endogenous APC, fibrinogen depletion does not prevent cancer cell dissemination and secondary tumor formation in immune-competent mice. Overall, we thus show that endogenous APC is essential for immune-mediated cancer cell elimination.

Doxorubicin selectively suppresses mRNA expression and production of endothelin-1 in endothelial cells

Doxorubicin (DXR) is a widely used cytostatic agent, but its administration is limited by its cardiovascular side effects. The endothelium is one of the largest organs in the human body and due to its direct contact with blood; it is exposed to the toxic effects of DXR. The aim of this study was to investigate in endothelial cells the effects of DXR on the expression of genes involved in cardiovascular diseases. We used in vitro cultured human umbilical vein endothelial cells (HUVEC) as a model; gene expression was assessed by SuperArray and qPCR. Out of the 96 representative genes of cardiovascular importance, the expression of only the ET-1 gene changed significantly. ET-1 mRNA expression was 10.9% of the untreated control (p=0.0049). This result was confirmed by qPCR (2.41% of control, p=0.0022). DXR also suppressed ET-1 production at protein level (p=0.0116). Both the early decrease in endothelial ET-1 production in the presence of DXR and the high plasma level of DXR during chemotherapy may influence the toxic effects of the drug.

The role of activated protein C in cancer progression

Activated protein C (APC) is best known as a natural anticoagulant that also has direct cell signaling properties which (among others) enhance vascular barrier function. We recently established the relevance of APC-induced barrier enhancement by showing that endogenous APC limits cancer cell extravasation. In line with this concept, repeated administration of exogenous APC reduced the number of experimental metastasis. It is thus tempting to speculate that exogenous APC administration would be a novel therapeutic avenue to fight cancer metastasis. The current review summarizes recent data on the role of the protein C pathway in cancer metastasis. It discusses the APC pathway as a potential novel target to influence cancer progression, but it also points to several limitations of APC administration in the setting of cancer cell metastasis.

Plasma protein C levels in immunocompromised septic patients are significantly lower than immunocompetent septic patients: a prospective cohort study

Introduction

Activated Protein C [APC] improves outcome in immunocompetent patients with severe sepsis particularly in those who are perceived to have high mortality risk. Before embarking on a trial of APC administration in immunocompromised septic patients, a preliminary study on plasma levels of protein C in this cohort is essential.

Objective

To assess serum Protein C concentrations in immunocompromised patients as compared to immunocompetent patients during sepsis, severe sepsis, septic shock and recovery.

Methods

Prospective cohort study in a tertiary hospital. Patients satisfying inclusion criteria were enrolled after informed consent. Clinical variables were noted with sample collection when patients met criteria for sepsis, severe sepsis, septic shock and recovery. Protein C levels were measured using monoclonal antibody based fluorescence immunoassay.

Results

Thirty one patients participated in this study (22 immunocompromised, 9 immunocompetent). Protein C levels were found to be significantly lower in the immunocompromised group compared to the immunocompetent group, particularly observed in severe sepsis [2.27 (95% CI: 1.63-2.9) vs 4.19 (95% CI: 2.87-5.52) mcg/ml] (p = 0.01) and sepsis [2.59 (95% CI: 1.98-3.21) vs 3.64 (95% CI: 2.83-4.45) mcg/ml] (p = 0.03). SOFA scores were similar in both the groups across sepsis, severe sepsis and septic shock categories. Protein C levels improved significantly in recovery (p = 0.001) irrespective of immune status.

Conclusion

Protein C levels were significantly lower in immunocompromised patients when compared to immunocompetent patients in severe sepsis and sepsis categories. Our study suggests a plausible role for APC in severely septic immunocompromised patients which need further elucidation.

Endogenous activated protein C limits cancer cell extravasation through sphingosine-1-phosphate receptor 1-mediated vascular endothelial barrier enhancement

Activated protein C (APC) has both anticoagulant activity and direct cell-signaling properties. APC has been reported to promote cancer cell migration/invasion and to inhibit apoptosis and therefore may exacerbate metastasis. Opposing these activities, APC signaling protects the vascular endothelial barrier through sphingosine-1-phosphate receptor-1 (S(1)P(1))activation, which may counteract cancer cell extravasation. Here, we provide evidence that endogenous APC limits cancer cell extravasation, with in vivo use of monoclonal antibodies against APC. The protective effect of endogenous APC depends on its signaling properties. The MAPC1591 antibody that only blocks anticoagulant activity of APC does not affect cancer cell extravasation as opposed to MPC1609 that blocks anticoagulant and signaling properties of APC. Combined administration of anti-APC antibodies and S(1)P(1) agonist (SEW2871) resulted in a similar number of pulmonary foci in mice in presence and absence of APC, indicating that the protective effect of APC depends on the S(1)P(1) pathway. Moreover, endogenous APC prevents cancer cell-induced vascular leakage as assessed by the Evans Blue Dye assay, and SEW2871 treatment reversed MPC1609-dependent vascular leakage. Finally, we show that cancer cells combined with MPC1609 treatment diminished endothelial VE-cadherin expression. In conclusion, endogenous APC limits cancer cell extravasation because of S(1)P(1)-mediated VE-cadherin-dependent vascular barrier enhancement.

Regulation of endothelial protein C receptor shedding by cytokines is mediated through differential activation of MAP kinase signaling pathways

The endothelial protein C receptor (EPCR) plays a pivotal role in coagulation, inflammation, cell proliferation, and cancer, but its activity is markedly changed by ectodomain cleavage and release as the soluble protein (sEPCR). In this study we examined the mechanisms involved in the regulation of EPCR shedding in human umbilical endothelial cells (HUVEC). Interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), but not interferon-gamma and interleukin-6, suppressed EPCR mRNA transcription and cell-associated EPCR expression in HUVEC. The release of sEPCR induced by IL-1beta and TNF-alpha correlated with activation of p38 MAPK and c-Jun N-terminal kinase (JNK). EPCR shedding was also induced by phorbol 12-myristate 13-acetate, ionomycin, anisomycin, thiol oxidants or alkylators, thrombin, and disruptors of lipid rafts. Both basal and induced shedding of EPCR was blocked by the metalloproteinase inhibitors, TAPI-0 and GM6001, and by the reduced non-protein thiols, glutathione, dihydrolipoic acid, dithiothreitol, and N-acetyl-l-cysteine. Because other antioxidants and scavengers of reactive oxygen species failed to block the cleavage of EPCR, a direct suppression of metalloproteinase activity seems responsible for the observed effects of reduced thiols. In summary, the shedding of EPCR in HUVEC is effectively regulated by IL-1beta and TNF-alpha, and downstream by MAP kinase signaling pathways and metalloproteinases.

Chemotherapeutic agents doxorubicin and epirubicin induce a procoagulant phenotype on endothelial cells and blood monocytes

BACKGROUND

Although chemotherapy is associated with an increased risk of thrombosis, the pathogenic mechanisms by which chemotherapeutic agents exert prothrombotic effects are unclear.

OBJECTIVES

In this study we explored the possibility that chemotherapeutic agents doxorubicin, epirubicin, 5-fluorouracil and methotrexate induce a procoagulant phenotype on vascular endothelial cells and/or on blood monocytes.

METHODS

Thrombin generation was measured in defibrinated plasma exposed to chemotherapy-treated human umbilical vein endothelial cells (HUVECs). Tissue factor activity assays were performed on chemotherapy-treated HUVECs and blood monocytes. The effects of chemotherapy drugs on phosphatidylserine exposure and the protein C pathway were also measured.

RESULTS

Exposure of defibrinated plasma to either doxorubicin- or epirubicin-treated HUVECs resulted in an increase in plasma thrombin generation. The procoagulant activity of doxorubicin- and epirubicin-treated HUVECs reflects an increase in tissue factor activity and phosphatidylserine exposure. Doxorubicin-mediated increase in tissue factor activity is related to increased levels of phosphatidylserine rather than to protein disulfide isomerase activity, and is likely to involve reactive oxygen species generation. Unlike doxorubicin, epirubicin does not have an impact on the protein C anticoagulant pathway. Interestingly, neither methotrextate nor 5-fluorouracil altered endothelial or monocyte hemostatic properties.

CONCLUSIONS

These studies suggest that doxorubicin and epirubicin have the greatest 'prothrombotic potential' by virtue of their ability to alter endothelial and monocyte hemostatic properties.

New insights into cancer-associated thrombosis

Venous thromboembolism (VTE) is an increasingly frequent complication of anticancer therapy. The underlying mechanisms are not completely understood, but are related in part to oncogene activation and tissue factor (TF) expression. Several risk factors have been identified including site and stage of cancer, patient comorbidities, and specific therapeutic agents. Candidate biomarkers such as blood counts, TF, and P-selectin have recently been identified. A risk model predictive of chemotherapy-associated VTE has been validated. Thromboprophylaxis with low molecular weight heparin (LMWH), unfractionated heparin (UFH), or fondaparinux is recommended for hospitalized medical and surgical cancer patients. Long-term anticoagulation with LMWH is safe and effective in reducing recurrent VTE in cancer. The role of thromboprophylaxis in ambulatory cancer patients receiving chemotherapy is an area of active investigation.

Treatment of endothelium with the chemotherapy agent vincristine affects activated protein C generation to a greater degree in newborn plasma than in adult plasma

INTRODUCTION

Activated protein C (APC) is well-established as a physiologically important anticoagulant. During development, plasma concentrations of protein C and alpha(2)macroglobulin, factors involved in APC generation, differ from adult levels. Chemotherapy drugs can perturb endothelial expression of PC-activating receptors. This study examines the effect of chemotherapy treatment of endothelium on APC generation in newborn and adult plasma.

MATERIALS AND METHODS

APC generations were initiated on endothelial cells treated with vincristine or media by recalcifying defibrinated plasma with buffer containing thromboplastin. APC generation was terminated by mixing timed subsamples into FFRCMK-EDTA or heparin, followed by EDTA. APC-PCI and APC-alpha(1)AT were assayed by ELISA. APC-alpha(2)M was measured chromogenically. Since heparin converts free APC to APC-PCI, the difference between APC-PCI detected in heparin subsamples and APC-PCI detected in FFRCMK-EDTA subsamples gave the free APC. Cellular expression of EPCR and TM were measured by flow cytometry and Western blot.

RESULTS

Vincristine-treated endothelium decreased free APC generation in newborn plasma to a greater degree than in adult plasma. APC-PCI levels in both adult and newborn plasma were unaffected by chemotherapy. Vincristine treatment reduced levels of APC-alpha(1) AT and APC-alpha(2) M to a greater degree in newborn plasma versus adult plasma. Expression of EPCR was reduced in cells treated with vincristine. Conversely, TM was reduced on the cell surface, but increased in whole cell lysates.

CONCLUSIONS

The differential response of newborn and adult plasma PC components to chemotherapy-mediated changes in cell surface components may be a factor in the increased risk of thrombosis in children receiving chemotherapy.