thromboplastin and Mesothelioma

The procoagulant protein tissue factor (F3) is a powerful growth promoter in many tumors, but its mechanism of action is not well understood. More generally, it is unknown whether hemostatic factors expressed on tumor cells influence tissue factor-mediated effects on cancer progression. In this study, we investigated the influence of tissue factor, endothelial cell protein C receptor (EPCR, PROCR), and protease activated receptor-1 (PAR1, F2R) on the growth of malignant pleural mesothelioma (MPM), using human MPM cells that lack or express tissue factor, EPCR or PAR1, and an orthotopic nude mouse model of MPM. Intrapleural administration of MPM cells expressing tissue factor and PAR1 but lacking EPCR and PAR2 (F2RL1) generated large tumors in the pleural cavity. Suppression of tissue factor or PAR1 expression in these cells markedly reduced tumor growth. In contrast, tissue factor overexpression in nonaggressive MPM cells that expressed EPCR and PAR1 with minimal levels of tissue factor did not increase their limited tumorigenicity. More importantly, ectopic expression of EPCR in aggressive MPM cells attenuated their growth potential, whereas EPCR silencing in nonaggressive MPM cells engineered to overexpress tissue factor increased their tumorigenicity. Immunohistochemical analyses revealed that EPCR expression in tumor cells reduced tumor cell proliferation and enhanced apoptosis. Overall, our results enlighten the mechanism by which tissue factor promotes tumor growth through PAR1, and they show how EPCR can attenuate the growth of tissue factor-expressing tumor cells.

Topics: Animals; Antigens, CD; Cell Line, Tumor; Cell Proliferation; Endothelial Protein C Receptor; Gene Expression; Gene Knockdown Techniques; Humans; Lipoproteins; Mesothelioma; Mice; Mice, Nude; Neoplasm Transplantation; Pleural Neoplasms; Receptor, PAR-1; Receptor, PAR-2; Receptors, Cell Surface; RNA, Small Interfering; Thrombomodulin; Thromboplastin; Tumor Burden

Malignancy often results in clotting abnormalities. The aetiology of haemostasis problems in cancer is complex, and is still not completely understood. We describe a case of a patient with malignant mesothelioma, who was found to have elevated activated partial thromboplastin time, due to lupus anticoagulant. We suggest that patients with malignancy should have their coagulation checked prior to any invasive procedures.

Topics: Aged; Blood Coagulation Disorders; Blood Coagulation Tests; Humans; Male; Mesothelioma; Radiography; Thromboplastin

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