fibrin and Mesothelioma

Malignant pleural mesothelioma (MPM) is a lethal neoplasm for which current therapy is unsatisfactory. The urokinase plasminogen activator receptor (uPAR) is associated with increased virulence of many solid neoplasms, but its role in the pathogenesis of MPM is currently unclear. We found that REN human pleural MPM cells expressed 4- to 10-fold more uPAR than MS-1 or M9K MPM cells or MeT5A human pleural mesothelial cells. In a new orthotopic murine model of MPM, we found that the kinetics of REN cell tumorigenesis is accelerated versus MS-1 or M9K cells, and that REN instillates generated larger tumors expressing increased uPAR, were more invasive, and caused earlier mortality. While REN, MS-1, and M9K tumors were all associated with prominent extravascular fibrin deposition, excised REN tumor homogenates were characterized by markedly increased uPAR at both the mRNA and protein levels. REN cells exhibited increased thymidine incorporation, which was attenuated in uPAR-silenced cells (P < 0.01). REN cells traversed three-dimensional fibrin gels while MS-1, M9K, and MeT5A cells did not. uPAR siRNA or uPAR blocking antibodies decreased REN cell migration and invasion, while uPA and fetal bovine serum augmented the effects. Transfection of relatively low uPAR expressing MS-1 cells with uPAR cDNA increased proliferation and migration in vitro and tumor formation in vivo. These observations link overexpression of uPAR to the pathogenesis of MPM, demonstrate that this receptor contributes to accelerated tumor growth in part through interactions with uPA, and suggest that uPAR may be a promising target for therapeutic intervention.

Topics: Animals; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Transformation, Neoplastic; Fibrin; Gene Expression Regulation, Neoplastic; Humans; Mesothelioma; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Invasiveness; Pleural Neoplasms; Receptors, Urokinase Plasminogen Activator; RNA Interference; RNA, Messenger; Time Factors; Transfection; Tumor Burden; Up-Regulation; Urokinase-Type Plasminogen Activator

The mesothelial lining of the pleura and malignant mesothelioma promote fibrin deposition in pleural injury or neoplasia via expression of tissue factor (TF). It was hypothesized that these cells might also regulate intrapleural coagulation by elaborating TF pathway inhibitor (TFPI). TFPI activity and antigen in pleural fluids were assayed from patients with congestive heart failure (CHF), pneumonia, empyema, metastatic pleural cancer and malignant mesothelioma. The authors also assessed expression of TF and TFPI messenger ribonucleic acid (mRNA) as well as TFPI activity and antigen by human pleural mesothelial cells, malignant mesothelioma cells (MS-1 cell line) and human lung fibroblasts. Immunohistochemical analyses of normal, fibrotic, and neoplastic pleura were performed to determine whether TFPI antigen was expressed in vivo. The study revealed that TFPI was present in transudates from patients with CHF and exudative pleural effusions from patients with pneumonia, empyema or pleural carcinoma. TFPI mRNA, activity and antigen were expressed by pleural mesothelial cells, MS-1 cells and lung fibroblasts. Cytokines and serum stimulated a significant early increase in TF mRNA levels with minimal enhancement of TFPI mRNA, activity and antigen levels. TFPI antigen was found in normal, fibrotic and neoplastic pleural tissues. The current observations indicate that tissue factor pathway inhibitor is locally expressed in pleural disease, but that it does not prevent the development of a prothrombotic environment favouring local fibrin deposition in pleural inflammation or cancer.

Topics: Blotting, Northern; Cells, Cultured; Enzyme-Linked Immunosorbent Assay; Female; Fibrin; Fibroblasts; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Lipoproteins; Male; Mesothelioma; Pleura; Pleural Neoplasms; Pulmonary Fibrosis; RNA, Messenger; Thromboplastin

Malignant mesothelioma (MM) is a locally aggressive tumor that spreads by poorly understood mechanisms. Because neoplastic spread has been linked to altered fibrin turnover, we used immunohistochemistry of nine MM and three fibrous tumors of the pleura to confirm in vivo fibrin deposition and expression of selected coagulation and fibrinolytic reactants in MM. Tumor-associated fibrin was readily detectable at site of tissue invasion. Little fibrin was distributed within the tumor, but tissue factor and tissue factor pathway inhibitor, urokinase, urokinase receptor, and plasminogen activator inhibitors 1 and 2 were all detected in either epithelioid or sarcomatous areas of MM. We used the MS-1 human pleural mesothelioma cell line to determine how expression of these reactants is regulated. Fibrinolytic activity of MS-1 is mainly due to urokinase and is responsive to cytokine stimulation. Functional extrinsic activation and prothrombinase complexes assemble at the cell surface. MM express procoagulants as well as fibrinolytic reactants in vivo and in vitro that promote local fibrin formation and remodeling. Fibrin deposition occurs primarily at areas of tissue invasion and could promote local extension of this neoplasm. Sparsity of fibrin within the central portions of the tumor stroma suggests that local resorption of transitional fibrin occurs at sites of established MM.

Topics: Blood Coagulation; Blood Coagulation Factors; Brain Neoplasms; Cytokines; Fibrin; Fibrinolysis; Humans; Mesothelioma; Plasminogen Inactivators; Pleural Neoplasms; Tumor Cells, Cultured

The mesothelium contains both procoagulant and fibrinolytic activities. An imbalance between these activities could account for the abnormal fibrin turnover and pleural fibrin deposition that is characteristic of pleural inflammation. Procoagulant activity of human pleural mesothelial cells (HPMC) is in part due to tissue factor, and the prothrombinase complex can also assemble at the HPMC surface. HPMC express tissue plasminogen activator (tPA) but no detectable fibrinolytic activity in a fibrin plate assay. Inhibition of HPMC fibrinolytic activity is due, in part, to elaboration of plasminogen activator inhibitors-1 and -2 (PAI-1 and PAI-2) as well as antiplasmins. Synthesis of PAI-1 and PAI-2 is inhibited by actinomycin D and cyclohexamide. HPMC PAI-1 is increased by transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha), as is tPA release, while PAI-1 mRNA is unchanged and tPA mRNA is increased. PAI-2 release is induced by TNF-alpha and TGF-beta. Because they are a rich source of PAI-1 and PAI-2, HPMC may contribute to the high levels of these inhibitors in pleural exudates. Stimulation of HPMC by TNF-alpha or TGF-beta in vitro did not alter HPMC procoagulant activity nor the balance of elevated PAI and antiplasmins relative to PA, changes that collectively favor formation and persistence of pericellular fibrin.

Topics: Base Sequence; Blood Coagulation Factors; Cells, Cultured; Cycloheximide; Dactinomycin; Epithelium; Fibrin; Fibrinolysis; Fibroblasts; Humans; Inflammation; Lung; Mesothelioma; Molecular Sequence Data; Oligonucleotide Probes; Plasminogen Activator Inhibitor 1; Plasminogen Activator Inhibitor 2; Pleural Effusion; Prothrombin; RNA, Messenger; Tissue Plasminogen Activator; Transforming Growth Factor beta; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha; Urokinase-Type Plasminogen Activator

Topics: Carcinoma, Bronchogenic; Diagnosis, Differential; Fibrin; Humans; Lung Neoplasms; Lymphoma; Mesothelioma; Neoplasm Metastasis; Pleural Diseases; Pleural Neoplasms; Radiography

Topics: Blood Coagulation; Empyema; Fibrin; Hemothorax; Humans; Mesothelioma; Pleura; Pleural Diseases; Pleural Neoplasms

Topics: Adult; Aged; Asbestosis; Calcinosis; Diagnosis, Differential; Female; Fibrin; Humans; Male; Mesothelioma; Middle Aged; Pleural Diseases; Pleural Neoplasms; Pneumothorax, Artificial; Radiography; Tissue Adhesions; Tuberculosis, Pulmonary