Recent studies suggest that tissue factor (TF) plays an important role in biological processes other than blood coagulation, including inflammation, angiogenesis and tumor metastasis. How does TF, whose principal role is to support clotting factor Vila (Vila) in initiating the coagulation cascade, affect various pathophysiological processes? Recent studies from our laboratory and others show that Vila binding to TF not only initiates clotting but also induces cell signaling, independent of down-stream coagulation proteases, by activating G-protein-coupled protease activated receptors (PARs). Our studies show that Vila binding to TF on tumor cells induces matricellular proteins and chemokines via PAR2-mediated cell signaling. Our preliminary data of heterologous desensitization and analysis of PAR2 cleavage indicate that only a small fraction of PAR2 may be activated by TF-Vlla at the cell surface, yet TF-Vlla can induce robust cell signaling via PAR2. The central goal of this application is to understand how TF-Vlla induces the cell signaling efficiently and whether TF-VIla-induced cell signaling, as indicated in in vitro studies, contributes to tumor metastasis.
In Aim 1, we will determine TF-Vlla and TF-Vlla-Xa cleavage of PAR2 and PAR1, and how this relates to TF-VIla/TF-Vlla-Xa-induced cell signaling in tumor cells.
In Aim 2, we will test a novel hypothesis that compartmentalization of TF, PAR2 and the effector molecules in plasma membrane microdomains facilitates efficient TF-Vlla-induced cell signaling. Finally, in Aim 3, we will determine the role of TFVI la/PAR2-mediated cell signaling in tumor metastasis. We will utilize the state-of-the-art techniques, such as confocal and electron microscopy, and gene silencing to achieve the stated goals. Data from these studies will answer many important questions concerning the mode of TF-Vlla-induced cell signaling and its importance in pathophysiology. Relevance to public health: Tissue factor expression in cancer cells is responsible for the hypercoagulable state presented in many cancers, and contributes to the pathogenesis of cancer progression and tumor metastasis. The proposed studies will provide valuable information in understanding how TF contributes to tumorigenesis. These studies will also provide clues on potential therapeutic targets for prevention of cancer progression.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Special Emphasis Panel (ZRG1-HEME-C (02))
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Link, Rebecca P
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University of Texas Health Center at Tyler
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United States
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Keshava, Shiva; Sahoo, Sanghamitra; Tucker, Torry A et al. (2013) Endothelial cell protein C receptor opposes mesothelioma growth driven by tissue factor. Cancer Res 73:3963-73
Keshava, S; Kothari, H; Rao, L V M et al. (2013) Influence of endothelial cell protein C receptor on breast cancer development. J Thromb Haemost 11:2062-5
Kothari, Hema; Rao, L Vijaya Mohan; Vankayalapati, Ramakrishna et al. (2012) Mycobacterium tuberculosis infection and tissue factor expression in macrophages. PLoS One 7:e45700
Rao, L Vijaya Mohan; Kothari, Hema; Pendurthi, Usha R (2012) Tissue factor encryption and decryption: facts and controversies. Thromb Res 129 Suppl 2:S13-7
Rao, L V M; Pendurthi, U R (2012) Regulation of tissue factor coagulant activity on cell surfaces. J Thromb Haemost 10:2242-53
Rao, L Vijaya Mohan; Kothari, Hema; Pendurthi, Usha R (2012) Tissue factor: mechanisms of decryption. Front Biosci (Elite Ed) 4:1513-27
Sen, Prosenjit; Gopalakrishnan, Ramakrishnan; Kothari, Hema et al. (2011) Factor VIIa bound to endothelial cell protein C receptor activates protease activated receptor-1 and mediates cell signaling and barrier protection. Blood 117:3199-208
Sen, P; Komissarov, A A; Florova, G et al. (2011) Plasminogen activator inhibitor-1 inhibits factor VIIa bound to tissue factor. J Thromb Haemost 9:531-9
Kothari, H; Rao, L V M; Pendurthi, U R (2011) Glycosylation of tissue factor is not essential for its transport or functions. J Thromb Haemost 9:1511-20
Tucker, Torry A; Dean, Candice; Komissarov, Andrey A et al. (2010) The urokinase receptor supports tumorigenesis of human malignant pleural mesothelioma cells. Am J Respir Cell Mol Biol 42:685-96

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