Androgen receptor dampens tissue factor expression via nuclear factor-κB and early growth response protein 1.

Essentials Androgen deprivation increases the rate of venous thromboembolism in prostate cancer patients. We characterized androgen receptor-mediated tissue factor regulation in prostate epithelial cells. Androgen receptor is dampening tissue factor expression in prostate epithelial cells. Androgen deprivation could enhance tissue factor expression and raise venous thromboembolism rates. SUMMARY: Background Prostate cancer is one of the leading causes of cancer death in men. Advanced prostate cancer is usually treated by androgen deprivation therapy (ADT), which is aimed at reducing circulating testosterone levels to reduce cancer growth. There is growing evidence that ADT can increase the rate of venous thromboembolism (VTE) in prostate cancer patients. The tissue factor (TF) gene is one of the most important mediators of coagulation and VTE, but, so far, there are limited data on androgen receptor (AR)-mediated TF gene expression. Objectives To characterize AR-mediated TF regulation in vitro and in vivo. Methods We used the androgen-dependent prostate cancer cell lines LNCaP and MyC-CaP to test whether TF expression is regulated by AR. Furthermore, we cloned the TF gene promoter into a luciferase reporter vector to identify the transcription factor-binding sites that mediate TF regulation downstream of AR. Finally, we used castration experiments in mice to characterize AR-mediated TF regulation in vivo. Results TF is directly regulated by AR. In LNCaP cells, nuclear factor-κB signaling and EGR1 mediate TF expression. By using castration experiments in mice, we could detect upregulation of TF and early growth response protein 1 mRNA and protein expression in prostate epithelial cells. Conclusion AR is crucial for dampening TF expression, which could be important for increased TF expression and TF-positive microvesicle release in androgen-deprived prostate cancer patients.

Citrullinated histone H3, a biomarker of neutrophil extracellular trap formation, predicts the risk of venous thromboembolism in cancer patients.

Essentials Neutrophil extracellular traps (NETs) might play a role in cancer-related coagulopathy. We determined NET biomarkers and followed cancer patients for venous thromboembolism (VTE). We found a constant association with VTE for citrullinated histone H3. Biomarkers of NET formation could reflect a novel pathomechanism of cancer-related VTE. SUMMARY: Background Neutrophil extracellular traps (NETs) are decondensed chromatin fibers that might play a role in the prothrombotic state of cancer patients. Objectives To investigate whether the levels of citrullinated histone H3 (H3Cit), a biomarker for NET formation, cell-free DNA (cfDNA) and nucleosomes predict venous thromboembolism (VTE) in cancer patients. Patients/Methods Nine-hundred and forty-six patients with newly diagnosed cancer or progression after remission were enrolled in this prospective observational cohort study. H3Cit, cfDNA and nucleosome levels were determined at study inclusion, and patients were followed for 2 years. VTE occurred in 89 patients; the cumulative 3-month, 6-month, 12-month and 24-month incidence rates of VTE were 3.7%, 6.0%, 8.1%, and 10.0%, respectively. Results Patients with elevated H3Cit levels (> 75th percentile of its distribution, n = 236) experienced a higher cumulative incidence of VTE (2-year risk of 14.5%) than patients with levels below this cut-off (2-year risk of 8.5%, n = 710). In a competing-risk regression analysis, a 100 ng mL-1 increase in H3Cit level was associated with a 13% relative increase in VTE risk (subdistribution hazard ratio [SHR] 1.13, 95% confidence interval [CI] 1.04-1.22). This association remained after adjustment for high VTE risk and very high VTE risk tumor sites, D-dimer level, and soluble P-selectin level (SHR 1.13, 95% CI 1.04-1.22). The association of elevated nucleosome and cfDNA levels with VTE risk was time-dependent, with associations with a higher risk of VTE only during the first 3-6 months. Conclusion These data suggest that biomarkers of NET formation are associated with the occurrence of VTE in cancer patients, indicating a role of NETs in the pathogenesis of cancer-associated thrombosis.

Myeloid but not epithelial tissue factor exerts protective anti-inflammatory effects in acid aspiration-induced acute lung injury.

Essentials Tissue factor (TF) represents a central link between hemostasis and inflammation. We studied the roles of myeloid and airway epithelial TF in acid-caused acute lung injury (ALI). TF on myeloid cells displays a non-coagulatory role regulating the inflammatory response in ALI. Airway epithelial TF contributes to hemostatic functions, but is dispensable in ALI pathogenesis. SUMMARY: Introduction Acute lung injury (ALI) is a life-threatening condition characterized by damaged alveolar-capillary structures and activation of inflammatory and hemostatic processes. Tissue factor (TF) represents a crucial link between inflammation and coagulation, as inflammatory mediators induce myeloid TF expression, and TF initiates extrinsic coagulation. Objective As pulmonary inflammation stimulates TF expression and TF modulates immune responses, we aimed to elucidate its impact on ALI. In particular, we wanted to distinguish the contributions of TF expressed on airway epithelial cells and TF expressed on myeloid cells. Methods Mice with different cell type-specific TF deficiency and wild-type littermates were intratracheally treated with hydrochloric acid, and leukocyte recruitment, cytokine levels, thrombin-antithrombin (TAT) complexes and pulmonary protein-rich infiltrates were analyzed. Results Our data demonstrate that a lack of epithelial TF did not influence acute responses, as bronchoalveolar neutrophil accumulation 8 h after ALI induction was unaltered. However, it led to mild, prolonged inflammation, as pulmonary leukocyte and erythrocyte numbers were still increased after 24 h, whereas those in wild-type mice had returned to basal levels. In contrast, myeloid TF was primarily involved in regulating the acute phase of ALI without affecting local coagulation, as indicated by increased bronchoalveolar neutrophil infiltration, pulmonary interleukin-6 levels, and edema formation, but equal TAT complex formation, 8 h after ALI induction. This augmented inflammatory response associated with myeloid TF deficiency was confirmed in vitro, as lipopolysaccharide-stimulated TF-deficient alveolar macrophages released increased levels of chemokine (C-X-C motif) ligand 1 and tumor necrosis factor-α as compared with wild-type macrophages. Conclusion We conclude that myeloid TF dampens inflammation in acid-induced ALI.

OC-16 - Neutrophil extracellular traps and tissue factor-bearing microvesicles: a liaison dangereuse causing overt DIC in cancer patients?

INTRODUCTION: Overt disseminated intravascular coagulation (DIC) is a systemic process characterized by excessive coagulation activation and fibrinolysis that may occur in cancer patients. The underlying pathomechanisms are still poorly understood. Recent experimental studies found an important role for the interaction between procoagulant neutrophil extracellular traps (NETs) and tissue factor (TF) in the pathogenesis of thrombosis. AIM: To investigate whether NETs and TF-bearing microvesicles (MVs) play a central role in cancer-related overt DIC. MATERIALS AND METHODS: Twenty-eight cancer patients with overt DIC (ISTH score ≥5, 14 females, median age: 62 years [range: 21-80], 13 with solid tumors, 15 with acute leukemia) and 28 matched healthy controls were included. NET formation parameters (plasma DNA and nucleosomes), MVassociated TF activity, and routine coagulation parameters were determined at study inclusion. In 11 patients with acute myeloid leukemia (AML), follow-up measurements were also performed. RESULTS: Plasma DNA, nucleosomes, and MV-TF activity were highly elevated in patients with cancer-related DIC compared to healthy individuals (all p-values<0.001). Strong correlations were found between plasma DNA and nucleosomes (Spearman correlation-coefficient: r=0.68), nucleosomes and MV-TF activity (r=0.62), and DNA and MV-TF activity (r=0.57). In multivariate regression, altered routine coagulation parameters were highly associated with NET parameters and MV-TF activity. In detail, a doubling in plasma DNA was associated with a 7.6% decrease in fibrinogen (p=0.012), a 15.3% decrease in platelet count (p=0.002), a 3.9% decrease in prothrombin time (p=0.014), and a 41.0% increase in D-dimer (p<0.001). A 10% increase in nucleosomes was associated with a 3.1% decrease in fibrinogen (p<0.001), a 5.0% decrease in platelet count (p<0.001), a 1.0% decrease in prothrombin time (p<0.009), and a 112.7% increase in D-dimer (p<0.001). A 10% increase in MV-TF activity was associated with a 4.9% decrease in fibrinogen (p<0.001), a 7.1% decrease in platelet count (p<0.001), a 1.3% decrease in prothrombin time (p<0.001), and a 15.5% increase in D-dimer (p<0.001). After initiation of chemotherapy in AML patients, NET parameters and MV-TF activity decreased significantly (nucleosomes: 3.3-fold decrease and normalization after 1 week; DNA: 1.2-fold decrease after 1 week and 1.5-fold decrease after 1 month; MV-TF activity: 10-fold decease after 1 week and normalization after 1 month) (Figure 1), and routine coagulation parameters improved. CONCLUSIONS: Our results add to experimental studies that have investigated the interaction between NETs and TF. Taken together, evidence indicates the presence of a liaison dangereuse between NETs and TF-bearing MVs, which could be the underlying cause of cancer-related overt DIC.