Tumor Cell-associated Tissue Factor Research Articles

Immune Checkpoint Blockade Promotes Thrombosis Via T-Cell and Neutrophil Activation, and Tumor-Cell Associated Tissue Factor (TF) in a Murine Model of Colorectal Cancer

Background: Immune checkpoint blockade (ICB) is a paradigm shift in cancer therapy. Despite clinical benefit, various adverse events are associated with ICB using immune checkpoint inhibitors (ICI). Venous thrombosis is an emerging clinical problem in cancer patients receiving ICI. Little is known about how ICI promotes thrombosis in cancer. To define the underlying mechanisms of ICI-associated thrombosis (IAT), we assessed the ICI impact on blood hypercoagulability and tumor TF expression using a mouse thrombosis model of colorectal cancer. Methods: We developed a CT26 mouse thrombosis model with ICI (aPD-1+aCTLA4) administration. Systemic hypercoagulability was assessed by measurement of circulating nucleosomes (Nu.Q H3.1 Immunoassay), neutrophil extracellular traps (NETs) (CitH3 immunofluorescence), circulating neutrophil-platelet aggregates (immunophenotyping), and levels of thrombin-antithrombin (TAT) complexes in ICI-treated mice. Tumor-associated TF and TF activity in circulating extracellular vesicles (EV) were assessed by western blotting and Factor Xa generation assays. To gain mechanistic insights into TF induction by ICI, tumor cytokines were also profiled (proteome profiler array). The role of cancer cell-derived TF in IAT was determined using mice implanted with CRISPR/Cas9-mediated TF knockout (TFKO) CT26 tumor cells. Results: ICI treated tumor-bearing mice developed larger thrombi than control mice and demonstrated elevated levels of circulating nucleosomes (114 vs 82 ng/ml), NET (15.8 vs 6.8%), platelet-neutrophil aggregates (44.8 vs 22.3%), and TAT complexes (12.6 vs 7.9 ng/ml) compared to IgG-treated mice. Tumor TF expression was increased in tumor extracts. Cytokine profiling suggested enhanced production of IFNɣ (2-fold) and TNFα (5-fold), as well as CXCL11 (6.8-fold), an effector T cell-recruiting chemokine. IFNɣ-increased TF expression in cultured CT26 cells, suggesting that T-cell derived IFNɣ may play a role in enhancing tumor TF expression in vivo. Circulating EV TF antigen and procoagulant activity were increased by ICI. CRISPR/Cas9-mediated TF KO in CT26 cells resulted in complete loss of TF expression, and mice bearing these cells showed reduced tumor and EV-associated TF (Fig. A), associated with a significant decrease in thrombus formation after ICI treatment (24.2 vs 20.5 mg, Fig. B). There was no significant difference in growth of wild-type and TF KO CT26 tumors. Conclusions: Our findings provide insights into cellular and molecular mechanisms associated with ICI-induced thrombosis, and suggest a role for neutrophil and granulocyte activation, and tumor-associated TF. Additional studies are ongoing to further define these pathways in the murine model and in patients.

Thrombin and Factor XII Drive Prostate Tumor Growth In Vivo

Several hemostatic factors are known to strongly influence the metastatic process by promoting the survival of early metastases. Despite this consistent phenomenon observed across multiple tumor cell types and multiple procoagulant components of the hemostatic system, the role of hemostasis in the establishment and growth of primary tumors is highly context dependent. One clinically relevant context where coagulation appears to be important for tumor development/outgrowth is prostate cancer. Men on long-term anticoagulation appear to be at significantly lower risk for developing prostate cancer compared to men on short-term anticoagulation or those not on anticoagulation. Here, we report that multiple hemostatic proteases drive prostate tumor growth in vivo. To test the hypothesis that the central hemostatic protease, thrombin, promotes prostate tumor growth, mice with a life-long genetically-imposed diminution in circulating prothrombin levels (fIILox/-), or mice administered a prothrombin-specific antisense oligonucleotide (ASO) gapmer that limits prothrombin expression, were inoculated subcutaneously with the murine-derived prostatic adenocarcinoma cell line TRAMP-C2Re3 in parallel with appropriate controls. Genetically or pharmacologically lowering prothrombin expression significantly impeded prostate tumor growth. In complementary experiments, treatment with the prothrombin-specific ASO gapmer significantly impeded the growth of human-derived prostate cancer cells (PC3) in immunodeficient mice. Detailed histological analysis revealed that tumors harvested from mice with diminished prothrombin expression had significantly lower mitotic indices, suggesting that thrombin promotes tumor proliferation in vivo. Lowering prothrombin levels did not affect apoptosis, vascular density, or the presence of tumor-associated macrophages. Previous studies have indicated that tumor cell-associated tissue factor expression is one important mechanism by which cancer cells can locally generate thrombin. However, the relative importance of the contact pathway of coagulation system activation in cancer progression is less defined. In order to determine whether fXII plays a role in prostate cancer growth, mice challenged with prostate cancer were treated with a fXII-specific ASO gapmer or a control oligonucleotide with no homology in the murine genome in parallel. Remarkably, tumors from anti-fXII ASO gapmer treated mice were ~3-fold smaller than those harvested from control animals at the end of the ~3 week experiment. To our knowledge, this finding is the first demonstration that the contact system protease fXII plays a significant role in tumor growth. In sum, these data show that thrombin promotes the growth of prostate cancer, and suggest that contact activation of the coagulation cascade may be a critical factor in prostate cancer growth. DisclosuresMonia:Isis Pharmaceuticals: Employment, Other: Shareholder. Revenko:SIS Pharmaceuticals Inc.: Employment.

Hemostatic factors, innate immunity and malignancy

Genetics-based studies have established the critical importance of tumor cell-associated tissue factor, circulating and endothelial cell-associated regulators of thrombin function and multiple thrombin substrates in metastasis. There appear to be multiple pathways by which procoagulants influence tumor biology, but the capacity of hemostatic factors to regulate innate immune function is at least one emerging theme. Several reports have shown that the platelet/fibrin(ogen) axis supports metastasis by limiting natural killer cellmediated lysis of newly-localized micrometastases. Furthermore, there is increasingly compelling evidence that hemostatic and innate immune system interactions also support very early events in cancer development. Analyses of the role of fibrin(ogen) in inflammation-driven colon cancer established a major role for this provisional matrix protein in early tumor development. A seminal property of fibrin(ogen) driving tumor formation in this context is the capacity to support local leukocyte activation events through engagement of the leukocyte integrin αMβ2. More recent studies have also suggested that hemostatic factors can, in at least some settings, program the malignant phenotype in tumor cells. Platelet-derived TGF-β1 and other platelet products were reported to trigger a more invasive and prometastatic epithelial-mesenchymal-like transition in embolic tumor cells. These findings support the intriguing concept that tumor cell functional properties can continue to evolve, even beyond the primary tumor site, in response to tumor cell-hemostatic factor interactions in the bloodstream. Taken together, there is strong evidence that the hemostatic system plays a multifaceted role in cancer pathogenesis and that therapies targeting selected hemostatic factors may present a powerful means to impede tumor development and metastasis.

Thrombin Control Mechanisms and Thrombin Targets in Cancer Biology

Abstract SCI-17 A link between hemostasis and cancer has been recognized for more than a century, but the last decade has seen substantial strides in understanding the mechanisms by which hemostatic system components actively contribute to the malignant phenotype. The expression of procoagulants, such as tissue factor (TF), by tumor cells has been shown to be a poor prognostic factor in clinical studies and a crucial determinant of metastasis in animal models. While TF expressed by tumor cells likely plays a multifaceted role in cancer biology, a substantial body of evidence indicates that tumor cell-associated and circulating hemostatic system components (e.g., prothrombin, fibrinogen, platelets) play a cooperative role in supporting metastasis. The capacity of tumor cells to generate thrombin has been proposed to support metastasis through several mechanisms, including tumor cell proliferation, stable adhesion, regulation of apoptosis, and escape from innate immune surveillance mechanisms. More recently, the fundamental importance of endothelial regulators of thrombin activity in metastasis was established through studies of tumor dissemination in mice expressing mutant forms of thrombomodulin (TM). Mice expressing a TM derivative with reduced thrombin affinity (TMPro) exhibited a profoundly prometastatic phenotype relative to wild-type (WT) mice. The TMPro mutation was shown to support metastasis by promoting the survival of tumor cell emboli newly localized to the lung. The impact of the TMPro mutation on metastasis was dependent on tumor cell-associated tissue factor, prothrombin, thrombin function, and platelets. In contrast, mice expressing a mutant form of TM lacking the lectin-like domain (TMLed) that were shown previously to have altered immune function but normal thrombin affinity, exhibited metastatic potential comparable to wild-type mice. These studies further highlight the importance of the hemostatic system in metastasis and demonstrate that apart from tumor cell-associated and circulating procoagulants, TM-mediated regulation of hemostatic function strongly influences tumor cell metastatic success. In addition, recent studies of inflammation-driven cancer have revealed that the role of hemostatic factors in tumor biology is not limited to later phases of malignant progression, such as metastasis. Fibrin(ogen)-mediated regulation of leukocyte function was shown to support tumor development and tumor proliferation in a murine model of inflammation-driven colon cancer. Recent advances in our understanding of the role of hemostatic factors in cancer biology demonstrate that this system of proteins can be important in multiple phases of malignant progression, and underscore the potential utility of targeting selected coagulation factors as a novel adjunct therapy in the treatment of cancer. Disclosures: Palumbo: Novo Nordisk Corporation: Research Funding.

Thrombomodulin is a determinant of metastasis through a mechanism linked to the thrombin binding domain but not the lectin-like domain

AbstractThrombomodulin (TM) is a predominantly endothelial transmembrane glycoprotein that modulates hemostatic function through a domain that controls thrombin-mediated proteolysis and an N-terminal lectin-like domain that controls inflammatory processes. To test the hypothesis that TM is a determinant of malignancy and dissect the importance of these functional domains in cancer biology, metastatic potential was evaluated in TMPro mice expressing a mutant form of TM with reduced thrombin affinity and TMLeD mice lacking the N-terminal lectin-like domain. Studies of TMPro mice revealed that TM is a powerful determinant of hematogenous metastasis. TMPro mice exhibited a strongly prometastatic phenotype relative to control mice that was found to result from increased survival of tumor cells newly localized to the lung rather than any alteration in tumor growth. The impact of the TMPro mutation on metastasis was dependent on both tumor cell-associated tissue factor and thrombin procoagulant function. In contrast, expression of a mutant form of TM lacking the lectin-like domain had no significant impact on metastasis. These studies directly demonstrate for the first time that TM-mediated regulation of tumor cell-driven procoagulant function strongly influences metastatic potential and suggest that endothelial cell-associated modulators of hemostasis may represent novel therapeutic targets in limiting tumor dissemination.

Plasma fibrinogen as a biomarker in gynecologic cancers.

Personalized MedicineVol. 8, No. 5 EditorialPlasma fibrinogen as a biomarker in gynecologic cancersClemens B TempferClemens B TempferDepartment of Obstetrics & Gynecology, Marienhospital Herne, Ruhr University Bochum, Bochum, Hölkeskampring 40, D-44625 Herne, Germany. Search for more papers by this authorEmail the corresponding author at clemens.tempfer@marienhospital-herne.dePublished Online:9 Sep 2011https://doi.org/10.2217/pme.11.47AboutSectionsView ArticleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInRedditEmail View article"Plasma fibrinogen as a biomarker in gynecologic cancers." , 8(5), pp. 501–502Keywords: cancercoagulationfibrinogenhypercoagulabilitymetastasispredictionprognosisBibliography1 Lawrence SO, Simpson-Haidaris PJ. Regulated de novo biosynthesis of fibrinogen in extrahepatic epithelial cells in response to inflammation. Thromb. Haemost.92,234–243 (2004).Crossref, Medline, CAS, Google Scholar2 Sahni A, Francis CW. Vascular endothelial growth factor binds to fibrinogen and fibrin and stimulates endothelial cell proliferation. Blood96,3772–3778 (2000).Crossref, Medline, CAS, Google Scholar3 Sahni A, Khoranaa A, Baggs RB, Peng H, Francis CW. FGF-2 binding to fibrin(ogen) is required for augmented angiogenesis. Blood107,126–131 (2006).Crossref, Medline, CAS, Google Scholar4 Simpson-Haidaris PJ, Rybarczyk B. Tumors and fibrinogen. The role of fibrinogen as an extracellular matrix protein. Ann. NY Acad. Sci.936,406–425 (2001).Crossref, Medline, CAS, Google Scholar5 Palumbo JS, Kombrinck KW, Drew AF et al. Fibrinogen is an important determinant of the metastatic potential of circulating tumor cells. Blood96(10),3302–3309 (2000).Crossref, Medline, CAS, Google Scholar6 Palumbo JS, Potter JM, Kaplan LS, Talmage K, Jackson DG, Degen JL. Spontaneous hematogenous and lymphatic metastasis, but not primary tumor growth or angiogenesis, is diminished in fibrinogen-deficient mice. Cancer Res.62(23),6966–6972 (2002).Medline, CAS, Google Scholar7 Palumbo JS, Talmage KE, Massari JV et al. Tumor cell-associated tissue factor and circulating hemostatic factors cooperate to increase metastatic potential through natural killer cell-dependent and-independent mechanisms. Blood110(1),133–141 (2007).Crossref, Medline, CAS, Google Scholar8 Fibrinogen Studies Collaboration, Danesh J, Lewington S et al. Plasma fibrinogen level and the risk of major cardiovascular diseases and nonvascular mortality: an individual participant meta-analysis. JAMA294,1799–1809 (2005).Crossref, Medline, CAS, Google Scholar9 Woods A, Brull DJ, Humphries SE et al. Genetics of inflammation and risk of coronary artery disease: the central role of interleukin-6. Eur. Heart J.21,1574–1583 (2000).Crossref, Medline, CAS, Google Scholar10 Takeuchi H, Ikeuchi S, Kitagawa Y et al. Pretreatment plasma fibrinogen level correlates with tumor progression and metastasis in patients with squamous cell carcinoma of the esophagus. J. Gastroenterol. Hepatol.22,2222–2227 (2007).Crossref, Medline, CAS, Google Scholar11 Yamashita H, Kitayama J, Kanno N et al. Hyperfibrinogenemia is associated with lymphatic as well as hematogenous metastasis and worse clinical outcome in T2 gastric cancer. BMC Cancer6,147 (2006).Crossref, Medline, Google Scholar12 Wojtukiewicz MZ, Zacharski LR, Moritz TE et al. Prognostic significance of blood coagulation tests in carcinoma of the lung and colon. Blood Coagul. Fibrinolysis3,429–437 (1992).Crossref, Medline, CAS, Google Scholar13 Polterauer S, Grimm C, Seebacher V et al. Plasma fibrinogen levels and prognosis in patients with ovarian cancer: a multicenter study. Oncologist14(10),979–985 (2009).Crossref, Medline, Google Scholar14 Seebacher V, Polterauer S, Grimm C, Husslein H, Leipold H, Hefler-Frischmuth K. The prognostic value of plasma fibrinogen levels in patients with endometrial cancer: a multi-centre trial. Br. J. Cancer102(6),952–956 (2010).Crossref, Medline, CAS, Google ScholarFiguresReferencesRelatedDetailsCited ByCurrent World LiteratureCurrent Opinion in Obstetrics & Gynecology, Vol. 25, No. 1 Vol. 8, No. 5 Follow us on social media for the latest updates Metrics Downloaded 114 times History Published online 9 September 2011 Published in print September 2011 Information© Future Medicine LtdKeywordscancercoagulationfibrinogenhypercoagulabilitymetastasispredictionprognosisFinancial & competing interests disclosureThe author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.No writing assistance was utilized in the production of this manuscript.PDF download

Mechanisms Coupling Thrombin-Mediated Proteolysis to Metastasis.

Multiple lines of evidence point to a link between coagulation factors and malignancy. Numerous clinical studies have demonstrated a strong correlation between tumor cell-associated tissue factor (TF) expression and poor outcome for many types of cancer. While TF expression by tumor cells could promote metastasis through several mechanisms, comparative analyses of TF-sufficient and TF-deficient tumor cell lines in mice with and without key circulating hemostatic factors point to thrombin as the premier downstream effector coupling TF to metastasis. Furthermore, it appears that thrombin supports metastasis through mechanism(s) that are highly dependent on the availability of fibrinogen, factor XIII, and platelet function. The metastatic potential of TF-expressing tumor cells has been shown to be strongly diminished in mice with genetic defects in either fibrin formation or stabilization (e.g., Fib−/−, fXIII−/−), or platelet disorders (e.g., NF-E2−/−, Gαq−/−, PAR-4−/−). Interestingly, one mechanism through which tumor-cell-associated TF, prothrombin, and the platelet/fibrinogen axis all appear to support metastasis is by impeding natural killer (NK) cell-mediated clearance of newly formed micrometastases. While these results demonstrate a novel link between the hemostatic and innate immune systems, limiting NK cell function is clearly not the only mechanism coupling thrombin to tumor cell metastasis. Signaling through protease activated receptors (PARs) on cells other than platelets has been suggested to support tumor stroma formation and angiogenesis. Furthermore, thrombin-mediated signaling via PARs expressed by tumor cells themselves has been shown to support metastatic potential. Finally, thrombin may support metastatic potential by acting in concert on multiple substrates (e.g., platelet and endothelial cell-associated PARs, fibrinogen, fXIII, etc.) to promote the sustained, stable adherence of circulating tumor cells in distant vascular beds. In summary, thrombinmediated proteolysis appears to influence both extracellular and intracellular events vital to tumor cell dissemination. Therapeutic strategies designed to block tumor cell-associated thrombin generation/activity could prove effective in preventing or eliminating metastatic disease.

Mechanisms Linking Tumor Cell–Associated Procoagulant Function to Tumor Dissemination

There is a persuasive body of evidence suggesting that tissue factor (TF) is a major determinant of tumor progression. In addition to its "traditional" function as the initiator of hemostasis, TF may support tumor progression through signaling mechanisms involving either direct signal transduction through the TF cytoplasmic domain or TF:F VIIa-mediated and TF/F VIIa/F Xa-mediated activation of protease-activated receptors. Whereas TF-mediated signaling events uncoupled from hemostasis may play an important role in tumor dissemination in some contexts, TF-mediated thrombin generation appears to be the major mechanism linking tumor cell-associated TF to metastasis. At least one mechanism coupling thrombin generation to metastatic potential involves the most distal components of the hemostatic system (i.e., platelets, fibrinogen, and factor XIII) and leads to a restriction in natural killer cell-mediated lysis of newly formed micrometastases. A detailed understanding of the mechanisms linking TF and circulating hemostatic system components to tumor progression may lead to novel therapeutic targets for cancer treatment.

Tumor cell–associated tissue factor and circulating hemostatic factors cooperate to increase metastatic potential through natural killer cell–dependent and–independent mechanisms

Tumor cell-associated tissue factor (TF) is a powerful determinant of metastatic potential. TF may increase metastasis by supporting thrombin-mediated proteolysis, through intracellular signaling events mediated by the TF cytoplasmic domain, through TF/fVIIa/fXa-mediated activation of protease-activated receptors, or through a combination of these processes. To better define the relationship between tumor cell-associated TF and circulating hemostatic factors in malignancy, we generated a set of C57Bl/6-derived tumor lines genetically lacking TF, expressing wild-type murine TF, or expressing a mutant TF lacking the cytoplasmic domain. Comparison of the metastatic potential of these cells in immunocompetent mice with genetic deficits in prothrombin, platelet function, or fibrinogen revealed that TF supports metastasis through mechanisms independent of the cytoplasmic domain, but dependent on each of these distal hemostatic factors. TF was neither required for primary tumor growth nor necessary for initial localization of embolized tumor cells within the lungs. Rather, tumor cell fate studies indicated TF supports metastasis by increasing the survival of micrometastases. One mechanism linking TF to metastasis is through a fibrin(ogen)-dependent and platelet-dependent restriction in natural killer cell-mediated clearance of micrometastases. However, TF also supported the early success of micrometastases through an additional mechanism independent of natural killer cells, but coupled to circulating prothrombin.

Tumor Cell-Associated Tissue Factor Supports Metastatic Potential through Both NK Cell-Dependent and -Independent Mechanisms.

Multiple lines of evidence indicate that the hemostatic system contributes to cancer dissemination. Previous studies have shown that tumor cell-associated tissue factor (TF) expression is a crucial determinant of metastatic potential. Furthermore, we have shown that tumor cell-associated TF supports metastatic potential through mechanism(s) dependent on multiple circulating hemostatic system components, including prothrombin, platelets, fibrinogen and, more recently, fXIII. At least two of these circulating hemostatic factors (platelets and fibrinogen) have been shown to support metastatic potential by impeding the clearance of recently embolized tumor cells by natural killer (NK) cells. It is reasonable to hypothesize that tumor cell-associated TF expression also supports metastatic potential by a mechanism coupled to NK cell function. Here, we used C57BL/6-derived, Ras-transformed tumor cell lines expressing wildtype murine tissue factor (TFWT), a mutant TF lacking the intracytoplasmic portion (TFΔTail), or no tissue factor (TFO) to directly examine the interplay between tumor cell-associated TF and NK cell function in determining metastatic potential. Each of these cell lines was capable of robust, comparable tumor growth in wildtype C57BL/6 mice. Loss of either platelet function or fibrinogen significantly diminished the metastatic potential of TFWT cells, but this effect was entirely abrogated by the concomitant loss of NK cells. Similar results were obtained with TFΔTail cells, indicating that the cytoplasmic portion of TF is not critical to these interactions. To determine if the increase in metastatic potential conferred by tumor cell-associated TF expression is entirely linked to NK cell function, we compared the metastatic potential and early survival of TFWT and TFO cells in mice with and without NK cells. TFOcells rarely formed any visible metastatic foci in mice with intact NK cell function, while TFWT cells were aggressively metastatic. Importantly, TF expression remained a significant determinant of metastatic potential even in mice lacking NK cells. Comparisons of the early fate of TFWT and TFO cells revealed that TF expression was not a determinant of initial tumor cell localization within the lungs. Rather, TF expression supported the sustained adherence and/or survival of tumor cells. Taken together, these data indicate that one mechanism linking tumor cell-associated TF expression to metastatic potential is coupled to circulating hemostatic factors and results in impaired NK cell-mediated clearance of recently established micrometastatic foci. However, TF expression also supports metastasis by at least one additional mechanism that is independent of natural killer cell function.

Interplay between Tumor Cell-Associated and Circulating Coagulation Factors in Establishing Metastatic Potential.

Tumor cell-associated tissue factor (TF) is an established determinant of metastatic potential. In order to explore the interplay between tumor cell-associated TF and circulating hemostatic system components in malignancy, we established a line of hRas-transformed tumor cells from C57Bl/6-derived TF−/− embryonic fibroblasts. These cells were subsequently transfected with expression vectors encoding wildtype murine TF (TFWT), a mutant form of murine TF lacking the cytoplasmic tail (TFΔTail), or no transgene product (TFO). Stable transfectants expressing TFWT and TFΔTail were selected by fluorescence-activated cell sorting using ICON protein (a chimeric derivative of murine fVIIa linked to the Fc portion of human IgG). All three tumor cell lines supported similar and robust tumor growth following subcutaneous transplantation into immunocompetent C57Bl/6-inbred mice. However, consistent with previous reports, TFWT cells were dramatically more metastatic than TFO cells. Loss of the cytoplasmic tail significantly reduced metastases relative to TFWT cells, but TFΔTail cells were far more metastatic than TFO cells, indicating that the TF cytoplasmic tail is important, but not strictly-required to support metastasis. Imposing genetic deficits in either platelet function (i.e., Gαq deficiency) or coagulation function (i.e., fibrinogen deficiency) significantly diminished the metastatic potential of TF-expressing tumor cells. The low metastatic potential of TFΔTail cells was further diminished in mice with impaired platelet activation, indicating that loss of the cytoplasmic tail does not uncouple metastatic potential from circulating hemostatic system components. Studies of the early fate/survival of [125I]-iododeoxyuridine radiolabeled TFWT and TFO cells revealed that neither fibrinogen nor tumor-associated tissue factor were required for initial tumor cell adhesion within the pulmonary vasculature. However, the combination of tumor cell TF and circulating fibrinogen was shown to enhance the longer-term survival of tumor cells within the lungs. Based on the earlier finding that both platelets and fibrinogen support metastasis in part by impeding natural killer cell mediated clearance of embolic tumor cells, a favored working hypothesis is that circulating hemostatic factors couple tumor cell-associated TF to evasion of innate anti-tumor immune surveillance mechanisms.

Occurrence of components of fibrinolytic pathways in situ in laryngeal cancer.

Malignancy is characterized by the occurrence of components of coagulation reaction pathways in situ within tumor tissues detectable immunohistochemically. However, tumors vary in the details of this coagulation-cancer interaction. We have previously described tumor cell-associated tissue factor (TF), factor (F) VII, and F X in laryngeal carcinoma tissues. Fibrinogen and F XIIIa were found in the tumor connective tissue. Tissue factor pathway inhibitor (TFPI) occurred in the tumor connective tissue and on microvascular endothelial cells and normal squamous epithelial cells but not in the tumor cells. Fibrin (thrombin-cleaved fibrinogen) existed at the host-tumor interface and the margins of tumor nodules consistent with an active tumor cell-associated clotting pathway in this tumor type. Studies were extended here to detect components of fibrinolytic pathways. Plasminogen and tissue plasminogen activator (t-PA) were detected on laryngeal tumor cells, particularly in more well-differentiated cases. Low-molecular-weight urokinase plasminogen activator (LMW u-PA) was primarily a feature of more undifferentiated laryngeal carcinoma cells. Staining to a lesser extent was found for high-molecular-weight u-PA (HMW u-PA) on tumor cells and various normal cell types in the tumor tissue. Relatively weak and variable tumor cell staining was found for plasminogen activator inhibitors (PAI) 1, 2, and 3. Trace staining was found for u-PA receptor (u-PAR) in differentiated tumor cells. The significance of coagulation and fibrinolytic pathways present in situ to the economy of laryngeal carcinoma remains to be determined.