Cellular localization of enzymatically active thrombin in intact human tissues by hirudin binding.

Cellular sites of coagulation activation within complex, intact tissues have been studied by immunohistochemical techniques. Hirudin, a specific and high affinity inhibitor of the active site of thrombin, together with antibody to hirudin were applied to sections of AMeX-fixed specimens of normal lung, kidney, placenta, freshly incised skin and unperturbed skin obtained at fresh autopsy; to rheumatoid synovial tissue; and to malignant tissue from a variety of tumor types. Staining for thrombin was observed selectively on pulmonary alveolar, rheumatoid synovial, and placental macrophages that express an intact extrinsic coagulation pathway. Staining was also observed restricted to the endothelium of capillaries in freshly incised skin but not in either unperturbed skin or in aged incisions. Staining of tumor cell bodies was observed in small cell carcinoma of the lung, renal cell carcinoma, and malignant melanoma tissues that we found previously to show tumor cell-associated procoagulant activity. This staining occurred commonly on cells within the tumor mass that were distant from stromal fibrinogen/fibrin. By contrast, tumor-associated macrophage but not tumor cell staining was seen in adenocarcinoma and squamous cell carcinoma of the lung, and little or no staining was seen colon cancer tissue. Negative controls in which either the hirudin probe or its antibody were omitted failed to show staining. These results are in accord with previous findings and suggest that such techniques may be useful for studying the cellular sites of thrombin generation in intact tissues. We postulate that administration of potent and specific thrombin antagonists, such as hirudin, to patients with relevant tumor types might be followed by homing of hirudin to tumor cells in vivo so that effects of local thrombin generation on malignant progression can be determined.

Studies of possible mechanisms for the effect of urokinase therapy in small cell carcinoma of the lung.

Urokinase-type plasminogen activator has been administered by other investigators to patients with small cell carcinoma of the lung (SCCL) in an attempt to induce lysis of fibrin that is known to exist in the connective tissue stroma of this tumour type and that may support tumour growth. To study the fate of infused urokinase in this disease, a biopsy of a scalp metastasis was obtained from a patient with SCCL (entered on a phase I clinical trial of urokinase plus combination chemotherapy) immediately following urokinase infusion during the fourth course of therapy a time when this tumour mass had decreased to approximately 25% of its original size. Immunohistochemical procedures revealed abundant stromal fibrin in accord with previous observations from this laboratory. By contrast, urokinase, that is not a feature of small cell tumour cells, was present on the tumour cells in this specimen. Urokinase infusion was associated with a rapid increase in the amount of this enzyme associated with isolated peripheral blood monocytes. These results are consistent with uptake of infused urokinase onto monocytes and possibly tumour cells. It is postulated that substantial tumour fibrinolysis may not accompany such therapy and that urokinase, or its amino terminal fragment that bears the growth factor domain of this molecule, may bind to and alter the growth of the tumour cells.

Tumor cell procoagulant and urokinase expression in carcinoma of the ovary.

BACKGROUND: An association between cancer and increased blood coagulation has been observed for many years. Generally, there is an equilibrium between the coagulation system (fibrin deposition) and the fibrinolytic system (degradation of fibrin by enzymes). However, in malignant disease such as ovarian carcinoma, this equilibrium is disrupted, resulting in the abnormal activation of coagulation or hypercoagulability. Also, evidence indicates that various components of these pathways may contribute to the disorderly characteristics of malignancy, such as proliferation, invasion, and metastasis. PURPOSE: Our purpose was to define the mode of interaction of tumor cells in ovarian carcinoma with both the coagulation (procoagulant-initiated) and fibrinolysis (urokinase-type plasminogen activator-initiated) (u-PA) pathways. METHODS: Studies were performed on acetone-methylbenzoate-xylene-fixed tissue prepared from fresh resected primary tumor specimens from 15 patients with cystic epithelial ovarian carcinoma. None of the patients had received prior treatment. Antibodies were tested on control and tumor tissues in concentrations that provided maximum staining intensity with minimum background staining. Laboratory immunohistochemical techniques used purified, monospecific antibodies to detect coagulant antigens. Tests were performed utilizing antibodies to recombinant human tissue factor; factor VII; factor X; factor XIIIA; high-molecular-weight and low-molecular-weight forms of u-PA; tissue-type plasminogen activator; plasminogen; and the plasminogen activator inhibitors 1, 2, and 3. Monoclonal antibodies used for specific antigen detection included 1-8C6 (fibrinogen), T2G1 (fibrin), and EBM-11 (macrophage-specific). RESULTS: The ovarian tumor cells expressed urokinase-type plasminogen activator in a pattern that was variable in intensity and distribution. Tumor cell plasminogen was not detected. Tumor cells also expressed tissue factor and coagulation pathway intermediates that resulted in local thrombin generation as evidenced by the conversion of fibrinogen (present in tumor connective tissue) to fibrin that was found to hug the surfaces of tumor nodules and individual tumor cells. Detected fibrin could not be accounted for on the basis of necrosis or a local inflammatory cell infiltrate. CONCLUSIONS: These results are consistent with the existence of a dominant tumor cell-associated procoagulant pathway that leads to thrombin generation and hypercoagulability in carcinoma of the ovary. IMPLICATIONS: In ovarian carcinoma the procoagulant pathway may contribute to tumor progression. Clinical trials of therapeutic drugs capable of limiting local coagulability (anticoagulants, protease inhibitors) are indicated in this tumor type.

Distribution of tissue factor pathway inhibitor in normal and malignant human tissues.

Specific antibodies to tissue factor pathway inhibitor (TFPI) were used in immunohistochemical procedures to determine the distribution of TFPI in normal and neoplastic human tissues. TFPI was restricted to megakaryocytes and the endothelium of the microvasculature in normal and abnormal tissues, but was not found in the endothelium of larger vessels or in hepatocytes. TFPI was also detected in macrophages in the villi of term placenta. Tumor-associated macrophages in several types of malignancy that we have shown previously to express a complete tissue factor-initiated pathway of coagulation and thrombin generation also manifested TFPI. By contrast, malignant cells in small cell carcinoma of the lung, renal cell carcinoma, and malignant melanoma that we have shown previously to express coagulation factors together with tumor cell-associated fibrin formation failed to stain for TFPI. We postulate that TFPI may be lacking from the latter malignancies because of the absence of the appropriately configured tissue factor-factor VIIa-factor Xa complex required for TFPI binding.

Pathways of coagulation activation in situ in rheumatoid synovial tissue.

Immunohistochemical techniques were applied to rheumatoid synovium in order to detect components of coagulation and fibrinolysis pathways within these tissues. These techniques revealed an intact coagulation pathway and plasminogen activator inhibitor-2 associated with macrophage-like cells that were present throughout these tissues, especially in subsurface areas. Cell-associated thrombin generation appeared to account for conversion of abundant fibrinogen to fibrin. Occasional macrophage-like cells also stained for urokinase but tissue-type plasminogen activator and plasminogen activator inhibitor-1 were restricted to vascular endothelium. Intense synovial fibrin deposition (with the limited evidence for associated fibrinolysis) may contribute to local inflammation and explain certain clinical features of rheumatoid arthritis. These findings suggest novel treatment hypotheses for this disease.

Fibrinogen deposition and macrophage-associated fibrin formation in malignant and nonmalignant lymphoid tissue.

Nonmalignant lymphoid tissue and tissue from patients with nodular sclerosis, Hodgkin's disease, and large cell lymphocytic lymphoma was examined by immunohistochemical techniques for the occurrence in situ of components of coagulation and fibrinolysis reaction pathways. Staining for material interpreted as fibrinogen was observed in abundance in both malignant and reactive lymphoid tissue. Fibrin also occurred to a variable extent but focally in all tissues. Components of coagulation pathways, including tissue factor, factor VII, factor X, and factor XIII ("a" subunit), were restricted to tissue macrophages. Double-labeling techniques revealed fibrin in direct apposition to tissue macrophages. We conclude that fibrinogen and fibrin occur in both benign and malignant lymphoid tissue and that the transformation of fibrinogen to fibrin is attributable to macrophage-initiated thrombin formation. We postulate that both systemic and local hypercoagulability associated with these disorders may be attributable to macrophage activation resulting in expression of procoagulant activity.

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.

Fibrin formation on vessel walls in hyperplastic and malignant prostate tissue.

To explore mechanisms of coagulation activation in adenocarcinoma of the prostate, the occurrence and distribution of components of coagulation and fibrinolysis pathways in situ were studied by means of immunohistochemical techniques applied to frozen sections of fresh malignant and benign hyperplastic prostatic tissue obtained at transurethral resection. Fibrinogen was distributed throughout the perivascular and tumor connective tissue in both malignant and benign disease but was not present in adjacent areas of normal prostate. Antibodies specific for fibrin and D-dimer crosslink sites stained vascular endothelium focally in both malignant and benign tissues. Both neoplastic cells and benign hyperplastic glandular epithelial cells stained weakly and in a patchy distribution for tissue factor and focally for low-molecular-weight urokinase-type plasminogen activator. Focal staining of vascular endothelium was also observed for tissue plasminogen activator and plasmin-antiplasmin complex neoantigen. By contrast, no tissue staining was observed for factor VII, factor X, factor XIII "a" subunit, high-molecular-weight urokinase-type plasminogen activator, plasminogen activator inhibitors 1 to 3, protein C, and protein S. Thus, the similarity in findings between benign hyperplastic and neoplastic prostate tissue, the lack of either an intact tumor cell-associated coagulation pathway or fibrin formation, and the presence of fibrin on vascular endothelium are consistent with the concept that coagulation activation in prostatic cancer may not be due to a direct effect of the tumor cells on the clotting mechanism. Rather, such activation may be induced by a soluble tumor product that activates procoagulant activity on certain host (for example, vascular endothelial) cells. These findings, together with the lack of effect of warfarin anticoagulation on the clinical course of patients with prostatic cancer, contrast with findings in certain other tumor types and suggest that coagulation activation may not contribute to progression of adenocarcinoma of the prostate.

Fibrinogen deposition without thrombin generation in primary human breast cancer tissue.

The occurrence and distribution of components of coagulation pathways in situ were determined using immunohistochemical techniques applied to 10 cases of primary carcinoma of the breast, normal breast tissue obtained from two patients undergoing reductive mammoplasty, and three patients with benign breast tumors. Tumor cells stained for factor X and thrombomodulin but not for tissue factor, factor V, factor VII, or factor XIII. Rare nonneoplastic duct epithelial cells stained for thrombomodulin, but these tissues did not otherwise stain for any of these antigens. Macrophages within the tumor stroma stained for tissue factor, factor VII, and factor XIII but not for factor V or factor X. These features of macrophages were the same in malignant and nonmalignant breast tissue. Fibrinogen was present in abundance throughout the connective tissue in breast cancer but not in nonmalignant tissues. By contrast, no staining was observed using fibrin-specific antibodies. These results suggest that an intact coagulation pathway does not exist in breast cancer tissue and that thrombin capable of transforming fibrinogen to fibrin is not generated in significant amounts in this tumor type. While fibrin is not a feature of the connective tissue stroma in breast cancer, it is conceivable that the abundant fibrinogen present in the tumor connective tissue (and factor XIII present in connective tissue macrophages) might contribute to the structural integrity of breast tumor tissues.

Occurrence of components of fibrinolysis pathways in situ in neoplastic and nonneoplastic human breast tissue.

The occurrence and distribution of components of fibrinolysis pathways were determined using immunohistochemical techniques applied to 10 cases of primary carcinoma of the breast, normal breast tissue obtained from two patients undergoing reductive mammoplasty, and three cases of benign breast tumors. Tumor cells stained for urokinase- and tissue-type plasminogen activators, plasminogen activation inhibitor-1, plasminogen, and plasmin-antiplasmin complex neoantigen. The tumor connective tissue stained for fibrinogen and its D fragment plasmin digestion product. By contrast, only occasional nonneoplastic duct epithelial cells stained for urokinase- and tissue-type plasminogen activators and there was little or no staining for the other antigens tested. These results are consistent with the existence of local amplification of expression of enzymatically active plasminogen activators, and particularly of urokinase-type plasminogen activator, in situ in primary breast cancer tissue. These features distinguish malignant from benign breast tissue and may modulate neoplastic progression through an effect on tumor cell proliferation, invasion, and metastatic dissemination.

Fibrinogen-fibrin transformation in situ in renal cell carcinoma.

The mechanism of coagulation activation in renal cell carcinoma was investigated using immunohistochemical techniques applied to fresh frozen sections of resected primary tumors. Tissue factor antigen was detected in the endothelium of vascular channels within the tumors. Fibrinogen and factor V were distributed diffusely in the perivascular tumor connective tissue. Fibrin was readily detected in a linear pattern along the edges of nodules of viable tumor indicating that thrombin had formed from the interaction of coagulation factors demonstrated previously in renal cell carcinoma tissue. Tissue plasminogen activator was detected in the endothelium of blood vessels in the vicinity of the tumor and urokinase in areas of necrosis but neither were associated with viable tumor cells. These results indicate that thrombin is formed locally in renal cell carcinoma tissue that transforms fibrinogen to fibrin. There also appears to be a net deficit in fibrinolysis in situ in this tumor. We postulate that these conditions might contribute to stabilization and progression of renal cell carcinoma and that clinical trials of antithrombotic agents are justified in this tumor type.

Malignant melanoma. Interaction with coagulation and fibrinolysis pathways in situ.

Immunohistochemical techniques applied to fresh frozen sections of metastatic malignant melanoma tissue revealed abundant fibrinogen (or fibrin I) in perivascular areas throughout the tumor connective tissue stroma. Fibrin was readily detected in a focal distribution in the connective tissue around nodules of viable tumor. Staining for D-dimer of cross-linked fibrin (using an antibody that cross-reacted with fragment D of fibrinogen) coincided with staining for fibrin. Diffuse staining of tumor cell bodies was observed for Factor X, and Factor XIII ("a" subunit) was detected in scattered areas of connective tissue throughout the tumors. Factor VII was not detected, and only rare tumor cells stained for tissue factor. These results support the concept that a tumor cell-associated, thrombin-generating pathway exists in situ in malignant melanoma tissue that includes Factor X but neither tissue factor nor Factor VII. By contrast, tumor cell staining was observed rarely for urokinase and to a variable extent for tissue plasminogen activator.

Abnormal regulation of coagulation/fibrinolysis in small cell carcinoma of the lung.

Components of coagulation and fibrinolysis reactions were identified in situ by immunohistochemical staining in fresh frozen sections of small cell carcinoma of the lung tissue. Tumor cells stained positively for tissue factor, a protein that is capable of activating the extrinsic pathway of coagulation (the components of which have been seen within small cell carcinoma of the lung [SCCL] tissue), and for proteins C and S antigens. Fibrin was seen in a focal distribution at the host-tumor interface, indicating that thrombin had acted upon the fibrinogen found throughout the tumor stroma. Staining with a neoepitope-specific antibody, which does not discriminate between fibrinogen fragment D and fibrin fragment D-dimer, was similar to that of the fibrin antibody. High molecular weight urokinase-type and tissue-type plasminogen activators were seen in vascular endothelium, but neither existed within the tumor. Low molecular weight urokinase was found in rare isolated foci of tumor cells primarily adjacent to areas of necrosis. Plasminogen activator inhibitor-3 occurred in tumor cell cytoplasmic blebs and in necrotic tumor cells, but plasminogen activator inhibitors 1 and 2 were not seen. Our data suggest a mechanism for thrombin generation and fibrin formation within SCCL tissues that could support cell proliferation, stroma formation, and preservation. These features could be conductive to perpetuation of this tumor and conceivably could form the basis of the beneficial effects of antithrombotic therapy seen in SCCL.

Indirect activation of blood coagulation in colon cancer.

Systemic activation of the coagulation mechanism is known to exist in patients with colon cancer. The mechanism of such activation was investigated using immunohistochemical techniques applied to fresh frozen sections of resected primary colon cancer specimens. Tumor cells stained for tissue factor, factor V, and urokinase-type plasminogen activator. Perivascular and intercellular areas stained for fibrinogen and the "a" subunit of factor XIII. Staining was minimal or absent for protein C, protein S, plasminogen activator inhibitors 1-3, factor VII, factor X, and fibrin (the antigenic site on the amino-terminal portion of B beta chain that is exposed following thrombin cleavage of fibrinopeptide B was not detected). The lack of an intact thrombin-generating pathway in situ associated with viable colon cancer cells is consistent with the findings of others that coagulation activation in colon cancer may be triggered by a soluble tumor product that exerts its effect at sites distant from the tumor. These results may explain the absence of clinical responsiveness of colon cancer to antithrombotic drug therapy and may clarify therapeutic strategies for this common tumor.

Thrombin-specific sites of fibrinogen in small cell carcinoma of the lung.

Thrombin-generated cleavage sites of human fibrinogen have been identified adjacent to viable tumor cells in fresh frozen sections of small cell carcinoma of the lung (SCCL) by means of immunohistochemical techniques using mouse monoclonal antibodies to the N-terminal peptides of the fibrinogen alpha and beta chains. These results indicate that thrombin is generated in situ in this tumor type. Based on previous evidence for the existence of an initiator of coagulation together with coagulation factor intermediates associated with viable SCCL tumor cells in situ, and also for the favorable effects of anticoagulant therapy with warfarin in SCCL, we postulate that local tumor cell-induced thrombin formation may contribute to self-regulated progression of SCCL through deposition of fibrin and stimulation of cell proliferation. These results suggest novel treatment strategies for this particular tumor type and justify efforts to identify other tumor types in which similar mechanisms exist.

Occurrence of blood coagulation factors in situ in small cell carcinoma of the lung.

Through immunohistochemical techniques, blood coagulation factors were identified in situ in fresh frozen sections of small cell carcinoma of the lung. Prothrombin/thrombin, factor VII, factor X, and antithrombin III were present in intercellular spaces and associated with tumor cells. Factor IX, factor XI, prekallikrein, and high molecular weight kininogen were identified as being associated with tumor cells but did not exist in intercellular spaces. Variable connective tissue staining but no tumor-related staining was observed for factor V, factor VIII-related antigen, factor XII, the B subunit of factor XIII, alpha 1-antitrypsin, alpha 2-macroglobulin, or alpha 2-antiplasmin. Neither consecutive tissue nor the tumor manifested platelet Ib and IIbIIIa surface glycoproteins. These divergent staining patterns suggested that the detected clotting factors had not merely diffused from permeabilized blood vessels, but were selectively localized in situ. While conditions may exist within tumor tissue that both retard and promote thrombin generation, we propose that interactions between the observed coagulation factors ultimately lead to local thrombin formation, which is responsible for the conspicuous fibrin deposits already described in small cell carcinoma of the lung. Thrombin formed locally might contribute to progression of this tumor. Inhibition of local thrombin formation by warfarin therapy could explain the beneficial effects of warfarin therapy in treating small cell carcinoma of the lung.

Coagulation-cancer interaction in situ in renal cell carcinoma.

Fibrin was detected by immunospecific techniques associated with both intravascular and extravascular tumor deposits in renal cell carcinoma. In addition, coagulation factors VII and X were demonstrated in intercellular spaces within tumor tissue and adjacent to the surface of tumor cells. Scant accumulation of platelets on intravascular tumor masses was observed. These data suggest that tumor cells in renal cell carcinoma may induce fibrin formation locally by a factor VII-mediated (and thus tissue factor-initiated) pathway of blood coagulation. This mechanism may also account for the hypercoagulable state that exists with this tumor type. We postulate that local fibrin formation may contribute to the growth and spread of this particular type of cancer and that the course of renal cell carcinoma may be ameliorated by anticoagulant therapy.