Fibrin formation on vessel walls in hyperplastic and malignant prostate tissue

Imbalance in Coagulation/Fibrinolysis Inhibitors Resulting in Extravascular Thrombin Generation in Gliomas of Varying Levels of Malignancy

Neoplastic processes are integrally related to disturbances in the mechanisms regulating hemostatic processes. Brain tumors, including gliomas, are neoplasms associated with a significantly increased risk of thromboembolic complications, affecting 20-30% of patients. As gliomas proliferate, they cause damage to the brain tissue and vascular structures, which leads to the release of procoagulant factors into the systemic circulation, and hence systemic activation of the blood coagulation system. Hypercoagulability in cancer patients may be, at least in part, a result of the inadequate activity of coagulation inhibitors. The aim of the study was to evaluate the expression of the inhibitors of the coagulation and fibrinolysis systems (tissue factor pathway inhibitor, TFPI; tissue factor pathway inhibitor-2 TFPI-2; protein C, PC; protein S, PS, thrombomodulin, TM; plasminogen activators inhibitor, PAI-1) in gliomas of varying degrees of malignancy. Immunohistochemical studies were performed on 40 gliomas, namely on 13 lower-grade (G2) gliomas (8 astrocytomas, 5 oligodendrogliomas) and 27 high-grade gliomas (G3-12 anaplastic astrocytomas, 4 anaplastic oligodendrogliomas; G4-11 glioblastomas). A strong expression of TFPI-2, PS, TM, PAI-1 was observed in lower-grade gliomas, while an intensive color immunohistochemical (IHC) reaction for the presence of TFPI antigens was detected in higher-grade gliomas. The presence of PC antigens was found in all gliomas. Prothrombin fragment 1+2 was observed in lower- and higher-grade gliomas reflecting local activation of blood coagulation. Differences in the expression of coagulation/fibrinolysis inhibitors in the tissues of gliomas with varying degrees of malignancy may be indicative of their altered role in gliomas, going beyond that of their functions in the hemostatic system.

Subventricular zone involvement in Glioblastoma - A proteomic evaluation and clinicoradiological correlation

Glioblastoma multiforme (GBM), the most malignant of all gliomas is characterized by a high degree of heterogeneity and poor response to treatment. The sub-ventricular zone (SVZ) is the major site of neurogenesis in the brain and is rich in neural stem cells. Based on the proximity of the GBM tumors to the SVZ, the tumors can be further classified into SVZ+ and SVZ−. The tumors located in close contact with the SVZ are classified as SVZ+, while the tumors located distantly from the SVZ are classified as SVZ−. To gain an insight into the increased aggressiveness of SVZ+ over SVZ− tumors, we have used proteomics techniques like 2D-DIGE and LC-MS/MS to investigate any possible proteomic differences between the two subtypes. Serum proteomic analysis revealed significant alterations of various acute phase proteins and lipid carrying proteins, while tissue proteomic analysis revealed significant alterations in cytoskeletal, lipid binding, chaperone and cell cycle regulating proteins, which are already known to be associated with disease pathobiology. These findings provide cues to molecular basis behind increased aggressiveness of SVZ+ GBM tumors over SVZ− GBM tumors and plausible therapeutic targets to improve treatment modalities for these highly invasive tumors.

Thrombin expression in prostate: a novel finding

INTRODUCTION

A variable repertoire of coagulation protein expression is observed in different cancers. We evaluated expression of thrombin in prostate tissue.

METHODS

Detection of thrombin was performed using quantitative real-time PCR in fresh tissue and in situ hybridization (ISH) in archival prostate tissue and by immunohistochemistry of prostate tissue microarrays.

RESULTS

(Pro)thrombin mRNA expression was detected in cancer tissue and localized to prostatic epithelium and stroma by ISH. Thrombin protein was detected in stroma of benign and malignant epithelium (p <.05).

CONCLUSIONS

Prostate tissue is a rich reservoir of thrombin. This may have potential for developing antithrombin-based cancer therapy.

Expression of protein C (PC), protein S (PS) and thrombomodulin (TM) in human colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is often complicated by thromboembolic episodes. It has been recognized that blood coagulation proteins play a role in cancer progression. An important inhibitory mechanism is provided by the protein C (PC) system consisting of PC, protein S (PS) and thrombomodulin (TM). Recently, novel biological activities have been ascribed to the PC system that do not relate to their hemostatic functions, eg. in angiogenesis, apoptosis and inflammation.

OBJECTIVES

The purpose of the study was to elucidate the solid phase interactions between CRC tissue and components of the PC system that may contribute to tumor progression.

MATERIAL AND METHODS

CRC tissues were obtained at surgical resection during treatment of 66 patients. Immunohistochemical studies were performed using polyclonal antibodies against PC, PS and TM. A semiquantitative analysis of the protein expression was also performed.

RESULTS

Weak expression of PC was observed in cancer cells of two-thirds of the specimens examined, while in 3/66 cases there was no staining for PC in cancer cells. One fourth of CRCs exhibited strong expression of PC. The presence of PS was demonstrated in 64/66 cases of CRC. However, its expression was irregular in terms of intensity of staining and percentage of cancer cells exhibiting protein expression. Weak expression of TM was demonstrated in two thirds of the cases examined, while a strong TM staining was revealed in one third of colon cancers.

CONCLUSION

Heterogeneous expression of the PC system components in CRC tissue may point to their biological activity modulating tumor growth.

Human kallikrein 4: enzymatic activity, inhibition, and degradation of extracellular matrix proteins

Human kallikrein 4 (hK4) is a member of the expanded family of human kallikreins, a group of 15 secreted proteases. While this protein has been associated with ovarian and prostate cancer prognosis, only limited functional information exists. Therefore, we have undertaken an investigation of its enzymatic properties regarding substrate preference, degradation of extracellular matrix proteins, and its inhibition by various inhibitors. We successfully expressed and purified active recombinant hK4 from supernatants of the Pichia pastoris expression system. This enzyme seems to cleave more efficiently after Arg compared to Lys at the P1 position and exhibits modest specificity for amino acids at positions P2 and P3. hK4 forms complexes with alpha1-antitrypsin, alpha2-antiplasmin and alpha2-macroglobulin. The protease mediates limited degradation of extracellular matrix proteins such as collagen I and IV, and more efficient degradation of the alpha-chain of fibrinogen. The cleavage of extracellular matrix proteins by hK4 suggests that this enzyme may play a role in tissue remodeling and cancer metastasis.

Circulating D-dimer levels are better predictors of overall survival and disease progression than carcinoembryonic antigen levels in patients with metastatic colorectal carcinoma

BACKGROUND

Fibrin formation is required for tumor angiogenesis, metastasis, and invasion. D-dimer, a fibrin degradation product, is produced when crosslinked fibrin is degraded by plasmin. The current study prospectively examined D-dimer levels in patients with metastatic colorectal carcinoma treated in a Phase II randomized trial comparing bevacizumab (Avastin, Genentech, South San Francisco, CA) plus 5-fluorouracil/leucovorin (5-FU/LV) with 5-FU/LV alone.

METHODS

At least one circulating D-dimer level was evaluable in 98 of the 104 previously untreated patients with metastatic colorectal carcinoma in the current trial. Plasma D-dimer levels were determined using a quantitative immunoassay kit at enrollment, before each treatment, and at the time of trial completion or disease progression.

RESULTS

At trial enrollment, 86 of 104 patients (88%) had elevated D-dimer levels (> 20 ng/mL), and 86 of 102 patients (84%) had elevated carcinoembryonic antigen (CEA) levels (> 3 ng/mL). Baseline D-dimer levels were correlated with the following baseline characteristics: CEA (Pearson coefficient, 0.31; P = 0.002), albumin levels (Pearson coefficient, -0.32; P = 0.002), tumor burden (Pearson coefficient, 0.30; P = 0.003), and number of metastatic sites (Pearson coefficient, 0.21; P = 0.04). At the time of progression, plasma D-dimer levels reached a maximum postbaseline value in 51 of 61 patients (84%), whereas the CEA level was at its maximum postbaseline value in 39 of 55 patients (71%). Baseline D-dimer levels were a strong predictor of overall survival on univariate analysis (P = 0.008) and multivariate analysis (P = 0.03). Overall, treatment with bevacizumab (5 mg/kg) and baseline D-dimer levels were the only predictors of overall survival (P < 0.05).

CONCLUSIONS

The current study indicates that fibrin remodeling is an important prognostic feature in metastatic colorectal carcinoma. D-dimer levels should be incorporated into prognostic models, and D-dimer may represent a useful biomarker for patients treated with antiangiogenic agents.

Tissue factor, thrombin, and cancer

In addition to its primary role in hemostasis and blood coagulation, thrombin is a potent mitogen capable of inducing cellular functions. Therefore, it should come as no surprise that thrombin has proved to be of importance in the behavior of cancer. In this review, we focus on the ability of tissue factor (TF) and thrombin to influence tumor angiogenesis. Both exert their influence on angiogenesis through clotting-dependent and clotting-independent mechanisms: (1). directly affecting signaling pathways that mediate cell functions, and (2). mediating clot formation, thereby providing a growth media for tumor cells. Therefore, anticoagulant drugs may prove efficacious in cancer treatment due to their ability to reduce the characteristic hypercoagulability of cancer and alter the fundamental biology of cancer.

Tumors and fibrinogen. The role of fibrinogen as an extracellular matrix protein

The progression of a tumor from benign and localized to invasive and metastatic growth is the major cause of poor clinical outcome in cancer patients. Much like in a healing wound, the deposition of fibrin(ogen), along with other adhesive glycoproteins, into the extracellular matrix (ECM) serves as a scaffold to support binding of growth factors and to promote the cellular responses of adhesion, proliferation, and migration during angiogenesis and tumor cell growth. Inappropriate synthesis and deposition of ECM constituents is linked to altered regulation of cell proliferation, leading to tumor cell growth and malignant transformation. Fibrin deposition occurs within the stroma of a majority of tumor types. In contrast, abundant FBG, not fibrin, is present within the stroma of breast cancers. It is thought to originate from exudation of plasma FBG and subsequent deposition into the tumor stroma and not endogenous synthesis and secretion of FBG by breast tumor cells. However, we show that MCF-7 human breast cancer cells synthesize and secrete FBG polypeptides, suggesting that the origin of FBG in the stroma of breast carcinoma may be due to endogenous synthesis and deposition. Moreover, FBG assembles into ECM as conformationally altered FBG, not as fibrin. Studies in our laboratory demonstrate that FBG alters the ability of breast cancer cells to migrate. Together, the results of studies from our laboratory, as well as the laboratories of others, indicate that the presence of fibrin(ogen) within the tumor stroma likely affects the progression of tumor cell growth and metastasis. This review focuses on FBG within tumors and its relationship with other tumor constituents, ultimately focusing on the role of FBG in breast cancer.

Effects of cancer chemotherapy on the blood fibrinogen concentrations of cancer patients

Blood fibrinogen concentrations and glutamic-pyruvic transaminase activities of 66 adult cancer inpatients (aged 22 - 70 years) were determined both before and after one or two chemotherapy regimens. The percentage of hepatoma patients with abnormal blood fibrinogen levels (< 1.5 or > 6.0 g/l) was higher (64.3% of 14 patients) than that in other cancer categories (19.2% of 52 patients). The mean blood fibrinogen concentrations of male (3.5 g/l) and female (4.5 g/l) cancer patients were higher than those previously reported for healthy humans (2.8 and 2.9 g/l, respectively). After chemotherapy, blood fibrinogen concentrations decreased in patients whose primary tumours were surgically removed (from 4.8 to 3.2 g/l) but increased (from 3.0 to 4.8 g/l) in those who did not undergo surgery. Glutamic-pyruvic transaminase activities did not appear to be related to blood fibrinogen levels. We conclude that the increase in mean blood fibrinogen levels of cancer patients is probably related to tumour growth. Different mechanisms may operate in patients with hepatoma.

Development of an ELISA for the quantification of fibrin in canine tumours

Fibrin is found in most solid tumours, and there is speculation regarding its role in tumour invasion and metastasis. An assay to quantitate fibrin levels in tissues would be a useful preliminary tool in assessing the above. Such an assay to quantitatively detect levels of fibrin in various types of canine tumour was developed. This procedure involved an ELISA using a monoclonal antibody (MAb 1H10) for canine fibrin as a capture antibody and a polyclonal antibody to human fibrinogen conjugated to horseradish peroxidase as the detection antibody. The ELISA is calibrated against known concentrations of freeze-fractured fibrin derived from clotted dog plasma. The assay takes 3.5 hours, and concentrations as low as 0.1 microg fibrin per milliliter of solubilised tumour can be readily detected. ELISA dilution curves for fibrin from various types of canine tumour were found to be parallel to the standard canine fibrin calibration curve. The intraassay and interassay variabilities of the assay gave coefficients of variation in the range of 2.4-4.5% and 7.2-7.8%, respectively, for the calibrator standard, in a concentration range of 0.1-10 microg/ml. Using this assay, we reported the levels of fibrin in three different types of malignant canine tissue.

Inhibition of metastases by anticoagulants

Metastasis involves several distinct steps, including one in which the tumor cell, after entry into the bloodstream, comes to rest in a capillary located at the distant site where a metastatic tumor will ultimately form. Components of the blood-clotting pathway may contribute to metastasis by trapping cells in capillaries or by facilitating adherence of cells to capillary walls. Conceivably, anticoagulants could interfere with this step in the metastatic process. In this review, we have summarized current knowledge on the interaction of malignant cells, clotting factors, and anticoagulants. We used computerized (MEDLINE) and manual searches to identify studies done in humans, in animals, and in in vitro systems that were published in English between 1952 and 1998. We found many reports that the formation of metastatic tumors could be inhibited by heparin, a vitamin K antagonist (warfarin), and inhibitors of platelet aggregation (prostacyclin and dipyridamole). Despite these encouraging preliminary results and a compelling biochemical rationale, only limited information exists on the clinical use of anticoagulants for the prevention or treatment of metastatic cancer because there have been so few controlled and prospectively randomized studies on this topic. In view of the preliminary results, anticoagulants may hold promise for the prevention and treatment of metastases. We believe that larger controlled investigations are strongly warranted to evaluate the clinical potential of anticoagulants for the prevention and treatment of metastases in humans.

Detection of fibrin in canine neoplasia

A murine monoclonal antibody, designated 1H10, produced using a human fibrin-related immunogen, was shown to bind avidly to dog fibrin, but not to dog fibrinogen. Using immunofluorescence, fibrin was detected in canine gastric adenocarcinoma and in mixed tissue from a mammary tumour. No fibrin could be detected in bronchogenic carcinoma tissue.

The Department of Veterans Affairs' unique clinical cancer research effort

Without organized clinical trials, we are doomed to repeat our mistakes endlessly. There are many genuine conflicts of interest intrinsic to clinical research. Some of these arise from the necessity of admitting that we as physicians do not know the best way to treat every disease or each patient and that all treatments currently available for this patient's disease are suboptimal. With humility and honesty, these conflicts of interest can be overcome. Surmounting other more palpable ones, however, is equally challenging. Supporting the participation of our patients in clinical trials requires a practical reconfiguration of practice patterns, different and more record keeping, and the surrender of autonomy. Each of these facts has economic implications. Practitioners who are paid according to the specific services they provide risk both significant income loss and cost increase by participating in clinical trials. The Department of Veterans Affairs is a charter member of the cancer clinical trials establishment and the originator of a long string of important firsts in cancer research. The nature of the VA system eliminates or diminishes the impact of many of the conflicts of interest that hinder clinical trial participation. This globally budgeted comprehensive system, which theoretically is responsible for the care of more citizens than is the entire Canadian national health service, is an unique clinical research resource. Some of the high points of the VA contributions to cancer treatment development are listed in this paper. Hopefully, this overview makes the point that the VA clinical research enterprise is a treasure that can ask critical questions that, because of irresolvable economic conflicts of interest, can be asked neither in the fee-for-service nor the prepaid health maintenance settings. This clinical cancer research resource must be nurtured and supported, and it must continue to address critical questions that it alone can answer.

Procoagulant properties of benign and malignant prostatic tissue

OBJECTIVE

To determine the factor-X activating procoagulant activity (FXAA) of prostatic tissue removed at transurethral resection in a specific chromogenic assay.

PATIENTS AND METHODS

FXAA was extracted from transurethrally resected prostatic tissue using a cryofragmentation technique. Tissue from 50 patients with prostate cancer was analysed and compared with that from 36 control patients with benign prostatic-hypertrophy. Enzyme activities were assayed in a two stage chromogenic assay and correlated with conventional markers of tumour aggressiveness.

RESULTS

FXAA was found to be significantly lower (P < 0.001) in tissue from malignant prostates compared with benign prostatic hypertrophy tissue. Loss of FXAA was also related to Gleason grade (P < 0.03), percentage of chips involved by tumour (P < 0.04) and bone scan status (P < 0.02). Using antibody inhibition tests this procoagulant was characterized as being a factor VII/tissue factor complex.

CONCLUSIONS

Malignant change in the prostate is associated with a reduction in FXAA and this may be an important factor in prostatic tumour growth and dissemination.

Hemostatic changes in patients with brain tumors

Abnormal hemostasis is a functional property of cancer. Hemostatic abnormalities are common in patients with systemic malignant disease and brain tumors. However, the incidence of thromboembolism is higher in patients with brain tumors than in those with systemic disease. This raises the question of whether or not hemostatic abnormalities found in the blood of the two groups of patients differs, suggesting different pathogeneses. The purpose of this report is to review abnormalities in blood and clinical manifestations of abnormal hemostasis found in brain tumors and cancer patients in an attempt to answer this question. Normal hemostasis, as currently understood, will be considered with an emphasis on features unique to the central nervous system.

The role of fibrin in tumor metastasis

A volume of data that has accumulated for over a century has suggested that fibrin may facilitate the persistence and progression of malignancy. Techniques that have been developed recently have shown that fibrin is indeed a component of the connective tissue stroma in human malignancy but in only a few tumor types. However, therapeutic intervention studies with drugs that limit thrombin activity or enhance fibrinolysis have shown favorable clinical effects in at least one such tumor type. These favorable findings affirm the concept that cause-and-effect relationships do, in fact, exist between thrombin generation with fibrin formation and tumor progression, and suggest that a rational basis exists for the design of future drug intervention trials that target reactions relevant to specific tumor types. These findings also provide a basis for the design of experiments capable of defining further the role of fibrin in the integrity of these tumor types. Because fibrinogen is found much more commonly than fibrin in the connective tissue of a variety of human malignancies, attention might reassumably be directed to determining the possible contribution of this molecule as well as of fibrin to tumor progression.

Tissue factor as a tumor procoagulant

Tissue factor is a cell surface glycoprotein responsible for initiating the extrinsic pathway of coagulation. Many tumor cell homogenates and intact tumor cells have been shown to contain tissue factor activity. Immunohistochemical studies show that many tumors associated with Trousseau's syndrome express tissue factor on their cell surfaces. Tumor cells shed membrane fragments which carry tissue factor that can account for the activation of the clotting system. Tumor cells also produce soluble substances that can induce tissue factor expression on host cells, such as endothelium and monocytes, at sites distant from the tumor. Although, all the functional TF molecules are localized on the outer cell membrane in many tumor cells, the procoagulant activity on the intact cell surface is largely dormant and can be greatly enhanced upon cell injury or damage. Tissue factor procoagulant activity on the cell surface can be modulated by alterations in the plasma membrane without loss of cell viability. Tissue factor activity on cell surfaces is largely regulated by a plasma inhibitor, tissue factor pathway inhibitor. This inhibitor binds to both functional and non-functional tissue factor/VIIa complexes on the cell surface and prevents non-functional tissue factor/VIIa complexes from becoming functional after cell injury or lysis. Heparin, but not warfarin, therapy is effective in preventing the occurrence of devastating thrombotic events in patients with Trousseau's syndrome and the reason(s) for this are still unknown.

Coexisting macrophage-associated fibrin formation and tumor cell urokinase in squamous cell and adenocarcinoma of the lung tissues

Mechanisms of coagulation activation in situ were studied by means of immunohistochemical techniques applied to surgically resected primary adenocarcinomas and squamous cell carcinomas of the lung. Findings in these two histologic types were similar. Double-labeling techniques using macrophage-specific antibody together with antibody to either tissue factor, factor VII, factor X, or factor V revealed coincident staining for each of these coagulation factors on tumor-associated macrophages. Staining of tumor cells for these factors was rare and inconsistent. Both macrophages and fibroblasts in the tumor connective tissue stained for the a subunit of factor XIII. Fibrinogen was abundant throughout the tumor connective tissue, but staining for fibrin and D-dimer cross-linked sites of fibrin was restricted to areas adjacent to macrophages, indicating that thrombin was generated in association with tumor macrophages but not with tumor cells. By contrast, tumor cells stained diffusely for urokinase-type plasminogen activator and focally for thrombomodulin. These findings contrast with those reported previously for small cell carcinoma of the lung and suggest that coagulation activation in adenocarcinoma and squamous cell carcinoma of the lung may occur indirectly through activation of certain host cells such as macrophages. By contrast, tumor cell plasminogen activator may mediate certain aspects of the malignant phenotype in these tumor types.