Tissue Factor Pathway Inhibitor mRNA Research Articles

The RNA-binding protein sorbin and SH3 domain-containing 2 are transcriptionally regulated by specificity protein 1 and function as tumor suppressors in bladder cancer by stabilizing tissue factor pathway inhibitor.

Sorbin and SH3 domain-containing 2 (SORBS2) is anRNA-binding protein and has been implicated in the development of some cancers. However, its role in bladder cancer (BC) is yet to be established. The expression of SORBS2 in BC tissues was determined from the Gene Expression Omnibusand Gene Expression Profiling Interactive Analysisdatabases and collected paired tumor/normal samples. The effects of SORBS2 on BC cells were detected by CCK-8, colony formation, Transwell, dual-luciferase, RNA immunoprecipitation, chromatin immunoprecipitation, and DNA pull-down assays. In vivo, BC cell growth and metastasis were studied by a xenograft subcutaneous model and a tail-vein metastasis model. The results showed that SORBS2 expression was significantly decreased in BC tissues and cells. SORBS2 overexpression inhibited cell proliferation, migration, invasion, and epithelial-mesenchymal transitionin vitro and tumor growth and metastasis in vivo, while silencing SORBS2 produced the opposite effect. Mechanistically, we found that SORBS2 enhanced the stability of tissue factor pathway inhibitor (TFPI) mRNA via direct binding to its 3' UTR. Restoration of TFPI expression reversed SORBS2 knockdown-induced malignant phenotypes of BC cells. In addition, SORBS2 expression was negatively regulated by the transcription factor specificity protein 1 (SP1). Conversely, SORBS2 can be transcriptionally regulated by SP1 and inhibit BC cell growth and metastasis via stabilization of TFPI mRNA, indicating SORBS2 may be a promising therapeutic target for BC.

Effects of andrographolide on the expression of procoagulant and fibrinolytic inhibition factors in rat type II alveolar epithelial cells stimulated by lipopolysaccharide

To determine the effect of andrographolide (AD) on the expression of procoagulant and fibrinolytic inhibitory factors in rat type II alveolar epithelial cells (AEC II) stimulated by lipopolysaccharide (LPS). The AEC II cells RLE-6TN in the logarithmic growth phase were divided into 5 groups: the normal control (NC) group, the LPS group, and the 6.25, 12.5, and 25 mg/L AD groups (AD 6.25 group, AD 12.5 group, AD 25 group). The NC group was cultured with RPMI 1640 conventional medium. In the LPS group, 5 mg/L LPS was added to the RPMI 1640 conventional medium for stimulation. Cells in the AD groups were treated with 6.25, 12.5, and 25 mg/L AD in advance for 1 hour and then given LPS to stimulate the culture. The cells and cell culture supernatant were collected 24 hours after LPS stimulation. The protein and mRNA expressions of tissue factor (TF), tissue factor pathway inhibitor (TFPI), and plasminogen activator inhibition-1 (PAI-1) in cells were detected by Western blotting and real-time fluorescent quantitative polymerase chain reaction (RT-qPCR). The levels of procollagen III peptide (PIIIP), thrombin-antithrombin complex (TAT), antithrombin III (AT-III) and activated protein C (APC) in the cell supernatant were detected by enzyme linked immunosorbent assay (ELISA). Compared with the NC group, the protein and mRNA expressions of TF and PAI-1 in the LPS group were significantly increased, and the protein and mRNA expressions of TFPI were significantly reduced. At the same time, the levels of PIIIP and TAT in the cell supernatant were significantly increased, the levels of AT-III, APC were significantly reduced. Compared with the LPS group, the protein and mRNA expressions of TF and PAI-1 in AD 6.25 group, AD 12.5 group, AD 25 group were significantly reduced [TF/GAPDH: 0.86±0.08, 0.45±0.04, 0.44±0.04 vs. 1.32±0.10, TF mRNA (2-ΔΔCt): 2.59±0.25, 2.27±0.05, 1.95±0.04 vs. 4.60±0.26, PAI-1/GAPDH: 2.11±0.07, 1.45±0.04, 0.86±0.09 vs. 2.56±0.09, PAI-1 mRNA (2-ΔΔCt): 3.50±0.22, 2.23±0.29, 1.84±0.09 vs. 6.60±0.27, all P < 0.05], while the protein and mRNA expressions of TFPI were significantly increased [TFPI/GAPDH: 0.78±0.05, 0.81±0.03, 0.84±0.07 vs. 0.36±0.02, TFPI mRNA (2-ΔΔCt): 0.46±0.09, 0.69±0.07, 0.91±0.08 vs. 0.44±0.06, all P < 0.05]. Also the levels of PIIIP and TAT in the cell supernatant were significantly reduced, and the levels of AT-III and APC were significantly increased [PIIIP (μg/L): 13.59±0.23, 12.66±0.23, 10.59±0.30 vs. 15.82±0.29, TAT (ng/L): 211.57±6.41, 205.69±4.04, 200.56±9.85 vs. 288.67±9.84, AT-III (μg/L): 102.95±3.86, 123.92±2.63, 128.67±1.67 vs. 92.93±3.36, APC (μg/L): 1 188.95±14.99, 1 366.12±39.93, 1 451.15±29.69 vs. 1 145.55±21.07, all P < 0.05]. With the increase of the dose of AD, the above-mentioned promotion and inhibition effects became more obvious. In the AD 25 group, TF, PAI-1 protein and mRNA expressions decreased, TFPI mRNA expression increased, PIIIP level in the supernatant decreased and AT-III, APC levels increased compared with AD 6.25 group, the difference was statistically significant, and the decrease of PAI-1 protein expression and PIIIP level in the supernatant were also statistically significant compared with AD 12.5 group. Andrographolide in the dose range of 6.25-25 mg/L can dose-dependently inhibit the expression and secretion of procoagulant and fibrinolytic inhibitor-related factors in AEC II cells RLE-6TN stimulated by LPS, and promote the secretion of anticoagulant factors. 25 mg/L has the most obvious effect.

Transcription factor FOXP3: A repressor of the TFPI gene?

Single nucleotide polymorphisms (SNPs) may play an important role in the risk of certain diseases. We have previously shown that the -287T/C SNP of the tissue factor pathway inhibitor (TFPI) gene promoter region exerts differential impact on TFPI mRNA expression; the C allele being associated with higher TFPI expression, which in turn is associated with reduced risk of thrombosis. In the present study, we aimed to reveal the underlying molecular mechanisms using human embryonic kidney 293 (HEK293) and Michigan Cancer Foundation-7 (MCF7) cells that both express TFPI. Transfecting the cells with luciferase reporter gene constructs containing the TFPI promoter with either the T or the C allele of -287T/C resulted in increased luciferase activity with the C allele relative to the T allele. Three potential candidate transcription factors for binding to the two -287 alleles were predicted using the ALGGEN PROMO software, and results from electrophoretic mobility shift assays indicated that forkhead box protein 3 (FOXP3), initially identified as a functional marker of T regulator cells, bound more specifically to the T allele compared with the C allele. By chromatin immunoprecipitation assays analysis it was confirmed that FOXP3 was able to bind to the DNA region that contains the SNP. Knockdown or overexpression of FOXP3 resulted in increased or decreased TFPI levels, respectively, in both cell types. In conclusion, this study indicates that FOXP3 most likely is involved in the increased levels of TFPI observed with the -287C allele and also that FOXP3 might be a repressor for TFPI expression.

A novel hypoxia response element regulates oxygen-related repression of tissue factor pathway inhibitor in the breast cancer cell line MCF-7

BackgroundHypoxia is one of the most pervasive physiological stresses in solid tumors. We have previously demonstrated that tissue factor (TF) pathway inhibitor (TFPI) expression was transcriptionally repressed by the activation of hypoxia inducible factor (HIF)-1α under hypoxic conditions. However, the role of HIF-2α, also known as endothelial PAS domain-containing protein 1 (EPAS1), on TFPI expression remains unclear. AimTo explore the role of HIF-2α/EPAS1 in the regulation of TFPI expression under hypoxia in breast cancer cells. Methods and resultsQuantitative RT-PCR showed that total TFPI mRNA and protein levels were decreased by the overexpression of HIF-2α/EPAS1 in MCF7 cells. Luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay indicated a HIF-2α/EPAS1 responsive region located in the TFPI promoter region at −170 to +21 relative to the transcriptional start site. Subsequent mutagenesis demonstrated a functional hypoxia response element (HRE) 5′-AAACAGGA-3′ for HIF-2α/EPAS1 within the TFPI promoter located at −45 to −38. In breast cancer patients, a positive correlation between HIF-2α/EPAS1 and total TFPI mRNA expression was observed by using gene expression analysis. ConclusionsThis study provides evidence that HIF-2α/EPAS1 is involved in the regulation of TFPI gene expression in breast cancer cells, suggesting that the activation of coagulation and the increased risk of thrombosis observed in breast cancer patients may correlate with local hypoxic regulation of coagulation factors and their inhibitors.

Tissue factor pathway inhibitor attenuates ER stress-induced inflammation in human M2-polarized macrophages

Endoplasmic reticulum (ER) stress has been shown to play a key role during the initiation and clinical progression of the cardiovascular diseases, such as atherosclerosis. We have recently shown that expression of tissue factor pathway inhibitor (TFPI) in human monocyte-derived macrophages (MDMs) was induced by cholesterol crystals (CC). In the present study we aimed to determine the role of TFPI under ER stress conditions using human MDMs. qRT-PCR and immunohistochemistry analysis were performed to determine the presence of the ER stress marker CCAAT/enhancer binding protein homologous protein (CHOP) and TFPI in human carotid plaque material and also in human MDMs polarized into pro-inflammatory M1 or anti-inflammatory M2 populations. CHOP mRNA levels were upregulated in the plaques compared to healthy vessels, and CHOP protein was localized in the same area as TFPI in the plaques. Both CHOP and TFPI mRNA levels were upregulated after CC treatment, especially in the M2 phenotype, and the ER stress inhibitor 4-phenylbutyric acid (PBA) reversed this effect. Furthermore, CC treatment increased the levels of the pro-inflammatory cytokines TNF-α, IL-6, and IL-8, which for TNF-α and IL-8 was inhibited by PBA, and reduced the levels of the anti-inflammatory cytokine IL-10 in M2-polarized macrophages. Knockdown of TFPI prior to CC treatment exacerbated TNF-α and IL-6 levels, but reduced IL-8 and IL-10 levels. Our results show that CC induce TFPI and cytokine expression in M2-polarized macrophages through activation of the ER stress pathway and that TFPI has a protective effect against TNF-α and IL-6 mediated inflammation. These mechanisms may have implications for the pathogenesis of atherosclerosis.

Abstract 13974: Loss of Endothelial Primary Cilia Promotes Thrombus Formation in Mice

Introduction: Recent evidence suggest that endothelial cilia may suppress anti-inflammatory signaling and protect against atherosclerosis. Given that atherosclerosis predisposes to thrombosis, we hypothesized that endothelial cilia may also play a fundamental role in thrombogenesis. Hypothesis: We hypothesize that endothelial cilia is important for protection against thrombosis, and that loss of endothelial cilia promotes thrombus formation in mice. Methods: We focused on the intraflagellar transport 88 (IFT88) gene since endothelial deletion of IFT88 has been associated with decreased atherosclerotic lesions in a murine model of atherosclerosis. Key thrombosis-associated molecules were evaluated in IFT88-silenced human umbilical vein endothelial cells (HUVECs). Thrombi formation were monitored in the laser-injured cremasteric arteries of 8 week old male endothelial cell (EC) specific IFT88 knockout (EC-IFT88 -/- ) mice. Results: Compared to scrambled siRNA-treated HUVECs, those exposed to siIFT88 exhibited lower mRNA and protein levels of tissue factor pathway inhibitor (TFPI) and thrombomodulin, two key regulators of blood coagulation (-27% and -20%, respectively; N=3; p &lt; 0.05). We next examined the effect of IFT88 loss on thrombosis in mice. Upon laser-induced injury, we determined, via mean fluorescence intensity, that although the thrombi formed in the cremasteric arteries of EC-IFT88 -/- mice were similar in size to those produced in the wild type (WT) mice (2.2 ± 0.6 and 2.0 ± 0.3 AU, respectively; x10 6 ; N=32 thrombi; p=0.8), the average rate at which thrombi developed was significantly faster in the EC-IFT88 -/- mice relative to that in WT mice (97 ± 11 and 57 ± 3 AU/s, respectively; N=32 thrombi; p&lt;0.001). Conclusions: Loss of endothelial IFT88 results in decreased TFPI mRNA and protein expression in HUVECs. EC-IFT88 -/- mice exhibited earlier thrombi formation in our laser injury model of thrombosis. These results collectively suggest that endothelial cilia intricately regulates thrombus formation in a TFPI-dependent manner and represents a previously unrecognized target to modulate thrombosis susceptibility.

The role of microRNA‐27a/b and microRNA‐494 in estrogen‐mediated downregulation of tissue factor pathway inhibitor α

Essentials Estrogens are known to influence the expression of microRNAs in breast cancer cells. We looked at microRNAs in estrogenic regulation of tissue factor pathway inhibitor α (TFPIα). Estrogen upregulated microRNA-27a/b and microRNA-494 through the estrogen receptor α. MicroRNA-27a/b and microRNA-494 are partly involved in estrogenic downregulation of TFPIα. Background Tissue factor pathway inhibitor (TFPI) has been linked to breast cancer pathogenesis. We have recently reported TFPI mRNA levels to be downregulated by estrogens in a breast cancer cell line (MCF7) through the estrogen receptor α (ERα). Accumulating evidence also indicates that activation of ERα signaling by estrogens may modulate the expression of target genes indirectly through microRNAs (miRNAs). Objectives To examine if miRNAs are involved in the estrogenic downregulation of TFPIα. Methods Computational analysis of the TFPI 3'-untranslated region (UTR) identified potential binding sites for miR-19a/b, miR-27a/b, miR-494, and miR-24. Transient overexpression or inhibition of the respective miRNAs was achieved by transfection of miRNA mimics or inhibitors. Direct targeting of TFPI 3'-UTR by miR-27a/b and miR-494 was determined by luciferase reporter assay in HEK293T cells. Effects of 17α-ethinylestradiol (EE2) and fulvestrant on relative miR-27a/b, miR-494, and TFPI mRNA levels in MCF7 cells were determined by qRT-PCR and secreted TFPIα protein by ELISA. Transient knockdown of ERα was achieved by siRNA transfection. Results EE2 treatment lead to a significant increase in miR-19a, miR-27a/b, miR-494, and miR-24 mRNA levels in MCF7 cells through ERα. miR-27a/b and miR-494 mimics lead to reduced TFPI mRNA and protein levels. Luciferase assay showed direct targeting of miR-27a/b and miR-494 on TFPI mRNA. Impaired estrogen-mediated downregulation of TFPI mRNA was detected in anti-miR-27a/b and anti-miR-494 transfected cells. Conclusions Our results provide evidence that miR-27a/b and miR-494 regulate TFPIα expression and suggest a possible role of these miRNAs in the estrogen-mediated downregulation of TFPIα.

Oestrogens Downregulate Tissue Factor Pathway Inhibitor through Oestrogen Response Elements in the 5'-Flanking Region.

Oestrogens influence the pathology and development of hormone-sensitive breast cancers. Tissue factor pathway inhibitor (TFPI) has been shown to be associated with breast cancer pathogenesis. Recently, we found TFPI mRNA levels to be significantly reduced by oestrogens in a breast cancer cell line (MCF7), a process mediated through the oestrogen receptor alpha (ERα). The aim of the present study was to investigate the mechanism(s) by which oestrogens may regulate TFPI at the transcriptional level. The TFPI 5’-flanking region contains three oestrogen response element (ERE) half-sites at positions -845, -769 and -50. Constructs containing the wild type or mutated ERE half-sites of the TFPI 5’-flanking region were generated in a luciferase reporter gene vector and transiently co-transfected with an ERα expression vector into HEK293 cells and subsequently treated with oestrogens. We found that luciferase activity was significantly downregulated after oestrogen stimulation in cells transfected with the wild type construct, an effect that was abolished by mutating either ERE half-sites. Electrophoretic mobility shift assay suggested direct and specific interaction of ERα with the ERE half-sites in the TFPI 5’-flanking region. Chromatin immunoprecipitation showed that ERα was recruited to the region -899 to -578 of the TFPI 5’-flanking region in vivo, where the ERE half-sites -845 and -769 are located. Our results indicate that ERα can interact with all three ERE half-sites in the TFPI 5’-flanking region and thus participate in the repression of oestrogen mediated TFPI transcription in breast cancer cells.

Effect of hypoxia on tissue factor pathway inhibitor expression in breast cancer

ESSENTIALS: A hypoxic microenvironment is a common feature of tumors that may influence activation of coagulation. MCF-7 and SK-BR-3 breast cancer cells and breast cancer tissue samples were used. The results showed transcriptional repression of tissue factor pathway inhibitor expression in hypoxia. Hypoxia-inducible factor 1α may be a target for the therapy of cancer-related coagulation and thrombosis. Activation of coagulation is a common finding in patients with cancer, and is associated with an increased risk of venous thrombosis. As a hypoxic microenvironment is a common feature of solid tumors, we investigated the role of hypoxia in the regulation of tissue factor (TF) pathway inhibitor (TFPI) expression in breast cancer. To explore the transcriptional regulation of TFPI by hypoxia-inducible factor (HIF)-1α in breast cancer cells and their correlation in breast cancer tissues. MCF-7 and SK-BR-3 breast cancer cells were cultured in 1% oxygen or treated with cobalt chloride (CoCl2 ) to mimic hypoxia. Time-dependent and dose-dependent downregulation of TFPI mRNA (quantitative RT-PCR) and of free TFPI protein (ELISA) were observed in hypoxia. Western blotting showed parallel increases in the levels of HIF-1α protein and TF. HIF-1α inhibitor abolished or attenuated the hypoxia-induced downregulation of TFPI. Luciferase reporter assay showed that both hypoxia and HIF-1α overexpression caused strong repression of TFPI promoter activity. Subsequent chromatin immunoprecipitation and mutagenesis analysis demonstrated a functional hypoxia response element within the TFPI promoter, located at -1065 to -1060 relative to the transcriptional start point. In breast cancer tissue samples, gene expression analyses showed a positive correlation between the mRNA expression of TFPI and that of HIF-1α. This study demonstrates that HIF-1α is involved in the transcriptional regulation of the TFPI gene, and suggests that a hypoxic microenvironment inside a breast tumor may induce a procoagulant state in breast cancer patients.

EPAS1/HIF-2 alpha-mediated downregulation of tissue factor pathway inhibitor leads to a pro-thrombotic potential in endothelial cells

Neovascularization and hemorrhaging are evident in advanced atherosclerotic plaques due to hypoxic conditions, and mediate the accumulation of metabolic substrates, inflammatory cells, lipids, and other blood born factors inside the plaque. Tissue factor (TF) pathway inhibitor (TFPI) is mainly expressed by endothelial cells and is the endogenous inhibitor of the coagulation activator TF, which together with the downstream product thrombin can drive plaque progression and atherogenesis. We aimed to investigate the effect of hypoxic conditions on endothelial cell expression and activity of TFPI and TF that are important in coagulation initiation.Hypoxia was induced in primary human umbilical vein endothelial cells using chemicals or 1% oxygen tension, and mRNA and protein expressions were measured using qRT-PCR, ELISA, and Western blot analysis. Microscopy of fluorescence-labeled cells was used to visualize cell-associated TFPI. Cell-surface factor Xa (FXa) activity was measured using a two-stage chromogenic substrate method. We found that hypoxia reduced the TFPI mRNA and protein levels and increased the TF mRNA expression in a dose-dependent manner. The effect on TFPI was apparent on all the protein pools of TFPI, i.e., secreted TFPI, cell-surface associated TFPI, and intracellular TFPI, and seemed to be dependent upon hypoxia inducible factor-2α (HIF-2α). An increase in FXa activity was also observed on the endothelial cell surface, reflecting an increase in pro-thrombotic potential of the cells.Our findings indicate that hypoxic conditions may enhance the pro-coagulant activity of endothelial cells, which may promote atherogenesis in addition to clinical events and thus the severity of atherosclerotic disorders.

Lethality of Mouse Tissue Factor Pathway Inhibitor Gene Disruption Is Rescued By Transgenic Human Tissue Factor Pathway Inhibitor Knock in

Background: Tissue factor pathway inhibitor (TFPI) is a key regulator of the extrinsic coagulation pathway. It inhibits FXa generation by forming a quaternary complex containing factor VIIa (FVIIa), tissue factor (TF), factor Xa (FXa), and TFPI. Two TFPI isoforms, TFPI alpha (TFPI a) and TFPI beta (TFPI b), have been identified, which differ in their C-terminal part due to alternative mRNA splicing events. TFPI a consists of three Kunitz domains (KD), while TFPI b contains two KDs and a C terminal GPI anchor linking the protein to endothelial cell surface. Deletion of the first Kunitz domain of TFPI, which is present in TFPI a and TFPI b in mice is known to be incompatible with viability due to intrauterine lethality (Huang et al., 1997).Aim: To generate transgenic humanized TFPI mice in which mouse (m)-TFPI is entirely replaced by human (hu)-TFPI, in order to facilitate analysis of specific anti hu-TFPI antagonists without interference from m-TFPI.Methods: Integration of the targeting vector, consisting of the m TFPI signal sequence, followed by the human TFPI cDNA and subsequent breeding analysis, was followed by genomic PCR. A sophisticated breeding strategy was used to entirely delete m-TFPI exon 4, which encodes KD1, in humanized transgenic mice. Expression of hu-/m-TFPI a and b mRNAs was analyzed by reverse transcription, cloning, and sequencing of the obtained DNA fragments. Protein levels of hu- and m-TFPI in plasma of transgenic and wild-type (wt) mice were analyzed using species specific ELISAs. Immunoprecipitation experiments in plasma and various mouse tissues are being performed to obtain more information on the presence and distribution of the hu-TFPI protein in transgenic mice.Results: Homozygous humanized TFPI mice were viable and exhibited no obvious abnormalities. Animals showed normal litter size with equal numbers of female and male pups. Genomic PCRs revealed proper integration of the targeting vector into the mouse chromosome and the homozygous status with the expected deletion of m-TFPI exon 4. Expression analyses of humanized TFPI mice on mRNA level demonstrated the absence of full length m-TFPI a and the presence of the humanized TFPI mRNA. Alternative spliced m-TFPI b messages lacking exons three and four were identified, likely leading to a nonfunctional protein. Full length hu-TFPI a mRNA was detected in various tissues in the humanized TFPI mice. The TFPI protein level in plasma from humanized mice was below the detection limit of the ELISA and at least ~300 fold below that for wt mice.Conclusion: Low levels of hu-TFPI may compensate the function of m-TFPI in vivo and circumvent embryonic lethality. Furthermore, we established a new mouse model which allows the regulation of physiologic and pathologic pathways to be assessed at TFPI plasma concentrations below the limit of detection. DisclosuresHoellriegl:Baxalta Innovations GmbH: Employment. Scheiflinger:Baxalta Innovations GmbH: Employment.

Reactive oxygen species induce a procoagulant state in endothelial cells by inhibiting tissue factor pathway inhibitor.

Tissue factor pathway inhibitor (TFPI) is a serine-protease inhibitor, which modulates coagulation tissue factor-dependent (TF). It binds directly and inhibits the TF-FVII/FVIIa complex as well as FXa. Time to reperfusion of acute ischemic myocardium is essential for tissue salvage. However, reperfusion also results in a unique form of myocardial damage, such as contractile dysfunction, decreased coronary flow and altered vascular reactivity. Oxidants and reactive oxygen species (ROS) formation is increased in the post-ischemic heart and is responsible of post-ischemic injury. It has been reported that ROS promote a procoagulant state via TF expression while no data are available on the effect on TFPI. Endothelial cells were incubated with two different ROS generating systems, xanthine (X)/xanthine oxidase (XO) for 5 min, or H2O2 (500 μM) for 24 h. TFPI activity was measured in supernatants by chromogenic assay and TFPI-mRNA analyzed by RT-PCR 2 h after ROS exposure. Unstimulated cells and cells exposed to either X or XO served as controls. Western blot and ligand dot blot was performed to evaluate ROS effect on TFPI structure and binding to FXa. ROS generated by X/XO as well as H2O2 system resulted in decreased TFPI activity compared to unstimulated cells while X or XO alone had no effect. No differences in TFPI mRNA levels versus controls was observed. A significant degradation of TFPI was induced by ROS exposure, resulting in a decreased ability to bind FXa. ROS induce a procoagulant state in endothelial cells by altering TFPI structure, resulting in inhibition of TFPI binding to Factor Xa and loss of activity. This phenomenon might have important consequences during reperfusion of post-ischemic myocardium.

Fluvastatin Upregulates the Expression of Tissue Factor Pathway Inhibitor in Human Umbilical Vein Endothelial Cells.

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are cholesterol-lowering drugs with a variety of pleiotropic effects including antithrombotic properties. Tissue factor pathway inhibitor (TFPI), which is produced predominantly in endothelial cells and platelets, inhibits the initiating phase of clot formation. We investigated the effect of fluvastatin on TFPI expression in cultured endothelial cells. Human umbilical vein endothelial cells (HUVECs) were treated with fluvastatin (0-10μM). The expression of TFPI mRNA and antigen were detected by RT-PCR and western blotting, respectively. The effects of mevalonate intermediates, small GTP-binding inhibitors, and signal transduction inhibitors were also evaluated to identify which pathway was involved. A luciferase reporter assay was performed to evaluate the effect of fluvastatin on TFPI transcription. The stability of TFPI mRNA was estimated by quantitating its levels after actinomycin D treatment. Fluvastatin increased TFPI mRNA expression and antigen in HUVECs. Fluvastatin-induced TFPI expression was reversed by co-treatment with mevalonate or geranylgeranylpyrophosphate (GGPP). NSC23766 and Y-27632 had no effect on TFPI expression. SB203580, GF109203, and LY294002 reduced fluvastatin-induced TFPI upregulation. Moreover, fluvastatin did not significantly affect TFPI promoter activity. TFPI mRNA degradation in the presence of actinomycin D was delayed by fluvastatin treatment. Fluvastatin increases endothelial TFPI expression through inhibition of mevalonate-, GGPP-, and Cdc42-dependent signaling pathways, and activation of the p38 MAPK, PI3K, and PKC pathways. This study revealed unknown mechanisms of the anticoagulant effect of statins and gave a new insight to its therapeutic potential for the prevention of thrombotic diseases.

Thrombin Down-Regulates Tissue Factor Pathway Inhibitor Expression in a PI3K/Nuclear Factor-κB–Dependent Manner in Human Pleural Mesothelial Cells

Tissue factor pathway inhibitor (TFPI) is the primary inhibitor of the extrinsic coagulation cascade, and its expression is reported to be relatively stable. Various pathophysiologic agents have been shown to influence TFPI activity by regulating its expression or by modifying the protein. It is not clear how TFPI activity is regulated in normal physiology or in injury. Because thrombin and TFPI are locally elaborated in pleural injury, we sought to determine if thrombin could regulate TFPI in human pleural mesothelial cells (HPMCs). Thrombin significantly decreased TFPI mRNA and protein levels by > 70%. Thrombin-mediated down-regulation of TFPI promoted factor X activation by HPMCs. The ability of thrombin to significantly decrease TFPI mRNA and protein levels was maintained at nanomolar concentrations. Protease-activated receptor (PAR)-1, a mediator of thrombin signaling, is detectable in the mesothelium in human and murine pleural injury. PAR-1 silencing blocked thrombin-mediated decrements of TFPI in HPMCs. Thrombin activates PI3K/Akt and nuclear factor κB (NF-κB) signaling in HPMCs. Inhibition of PI3K (by PX-866) and NF-κB (by SN50) prevented thrombin-mediated TFPI mRNA and protein down-regulation. These are the first studies to demonstrate that thrombin decreases TFPI expression in HPMCs. Our findings demonstrate a novel mechanism by which thrombin regulates TFPI expression in HPMCs and promotes an unrestricted procoagulant response, and suggest that interactions between PI3K and NF-κB signaling pathways are linked in HPMCs and control TFPI expression. These findings raise the possibility that targeting this pathway could limit the ability of the mesothelium to support extravascular fibrin deposition and organization associated with pleural injury.

Effect of α-melanocyte stimulating hormone and its novel analogue on the production of tissue factor pathway inhibitor in mice with endotoxemia

To evaluate the effect of α-melanocyte stimulating hormone (α-MSH) and its novel analogue STY39 on the production of tissue factor pathway inhibitor (TFPI) in mice with endotoxemia. Female BALB/c mice were randomly divided into eight groups with 9 mice in each group. Endotoxemia was reproduced by intraperitoneal injection of lipopolysaccharide (LPS, 25 μg/kg) and D-galactosamine (D-Gal, 100 mg/kg). The animals of the control group were given phosphate buffered solution (PBS) instead. In the experimental groups, the mice were injected intraperitoneally with 2.5 mg/kg α-MSH or STY39 at 1, 2 or 3 hours following LPS injection. The orbital blood was collected at different time points, and tissues of lung, liver, and kidney were collected 8 hours after the administration of LPS. The plasma TFPI levels were determined by enzyme linked immunosorbent assay (ELISA), and the expression of TFPI mRNA in different tissues was determined with reverse transcription-polymerase chain reaction (RT-PCR). The plasma TFPI levels began to increase (11.84±1.55 μg/L) in the endotoxemia mice 4 hours after LPS challenge and reached the peak (23.49 ± 1.12 μg/L) at 8 hours. α-MSH or STY39 treatment at 1, 2 or 3 hours after LPS challenge could significantly increase the TFPI content, with the best drug effect at 1 hour after LPS challenge (the blood was collected 8 hours after LPS challenge, α-MSH group: 58.79±2.67 μg/L vs. 28.49±1.69 μg/L, STY39 group: 71.08±2.13 μg/L vs. 28.49±1.69 μg/L, both P<0.01), and the effect of STY39 was better than that of α-MSH (P<0.01). A small amount of TFPI mRNA expression was observed in each tissue of the healthy mice. After LPS challenge, TFPI mRNA expression was increased in all the tissues, especially in the lung, liver and kidney. α-MSH or STY39 treatment at 1 hour after LPS challenge could significantly up-regulate the expression of TFPI mRNA in the lung and liver (A value, α-MSH in lung: 51.10±2.89 vs. 32.43±2.51, STY39 in lung: 72.11±3.48 vs. 32.43±2.51; α-MSH in liver: 43.21±2.12 vs. 29.29±2.06, STY39 in liver: 66.82±1.76 vs. 29.29±2.06, both P<0.01). The treatment with STY39 at 1 hour after LPS challenge could significantly up-regulate the expression of TFPI mRNA in the kidney (A value: 45.21±1.80 vs. 30.44±2.23, P<0.01), but the treatment with α-MSH had no obvious effect (A value: 24.61±1.98 vs. 30.44±2.23, P>0.05). The enhancing effect of early administration of STY39 on TFPI mRNA expression in the lung, liver and kidney tissues of endotoxemia mice was more powerful than that of α-MSH (all P<0.01). The early administration of α-MSH or STY39 may up-regulate TFPI production in the mice with endotoxemia, and the effect of STY39 is superior to α-MSH.

Abstract 275: Hypoxic Conditions Regulate the Expression and Activity of Coagulation Factors Important in Atherothrombosis

Neovascularization is an important feature in advanced atherosclerosis. It is recognized by the formation of new blood vessels recruited from the adventitia that penetrate the plaque, presumably due to lack of oxygen (hypoxia) in the plaque core. These immature, leaky neovessels can cause intraplaque hemorrhages, and promote plaque vulnerability and rupture. Plaque rupture leads to activation of coagulation and the formation of a thrombus, which is the main contributor to acute manifestations, morbidity, and mortality in atherosclerotic disease. The extrinsic coagulation activator tissue factor (TF) and its inhibitor tissue factor pathway inhibitor (TFPI) have been detected in atherosclerotic lesions, and are expressed by macrophages, smooth muscle cells, and endothelial cells overlaying the plaques. We aimed to investigate how hypoxic conditions affected the endothelial expression and activity of coagulation factors important in the initiation of coagulation. Hypoxia was induced in primary human umbilical (HUVEC) and aortic (HAEC) endothelial cells with chemicals (DMOG/CoCl2) or 1% oxygen (O2) concentration, and mRNA and protein expressions were measured using qRT-PCR and ELISA, respectively. Microscopy of fluorescence labeled cells was used to visualize cell-associated TFPI. Cell-surface FXa activity was measured using a two-stage chromogenic substrate method. Results showed that hypoxia reduced the TFPI mRNA and protein levels in a dose-dependent manner. The effect was apparent on all the protein pools of TFPI; the secreted, the cell-surface associated, and the intracellularly stored, indicating that the regulation occurred at the transcriptional level. The TF mRNA expression was also affected in a dose-dependent way, where low doses of DMOG and CoCl2 resulted in an increased expression, while high dose of DMOG and 1% O2 reduced the TF mRNA levels. Activated endothelial cells showed a dose-dependent regulation of TF expression following hypoxic stimulation, which is identical to the regulation of the FXa activity in the cells. Our findings indicate that hypoxic conditions can influence the coagulant activity of endothelial cells, which may potentially promote clinical events and thus the severity of atherosclerotic disorders.

Oestrogen induced downregulation of TFPI expression is mediated by ERα

IntroductionOestrogens influence the pathophysiology and development of hormone-sensitive cancers, such as breast cancer. Tissue factor pathway inhibitor (TFPI) is a serine protease inhibitor of the extrinsic coagulation pathway and has recently been associated with breast cancer cell development. Moreover, reduced TFPI levels have been reported in plasma of healthy post-menopausal women receiving hormone replacement therapy, indicating a possible link between oestrogen and TFPI. In our study, we aimed to examine the effects of oestrogen and oestrogen analogues on TFPI expression in breast cancer cells and to identify underlying mechanism(s). MethodsOestrogen receptor alpha (ERα) positive MCF7 and negative MDA-MB-231 cells were treated with 17-β-oestradiol, 17-β-ethinyloestradiol, raloxifene and fulvestrant. TFPI mRNA and protein was measured using qRT-PCR and ELISA, respectively. Transient ERα knockdown was achieved using siRNA. ResultsIn ERα expressing MCF7 cells, but not in MDA-MB-231 cells, the TFPI mRNA and protein levels were significantly downregulated by more than 50% after four or six hours of incubation with 17-β-ethinyloestradiol and 17-β-oestradiol, respectively. Moreover, a significant increase in FXa generation was detected in response to oestrogens. Breast tissue ER antagonists, raloxifene and fulvestrant, did not affect TFPI mRNA, however, fulvestrant blocked oestrogen mediated reduction of TFPI mRNA. Transient knockdown of ERα abolished the oestrogenic effect on TFPI and co-treatment of MCF7 cells with the protein synthesis inhibitor cycloheximide and 17-β-oestradiol also led to reduction of TFPI mRNA. ConclusionOur data establish a direct and time dependent regulation of TFPI expression by oestrogens through the ERα at the transcriptional level.

Translation of Human Tissue Factor Pathway Inhibitor-β mRNA Is Controlled by Alternative Splicing Within the 5′ Untranslated Region

Tissue factor pathway inhibitor (TFPI) blocks the initiation of coagulation by inhibiting TF-activated factor VII, activated factor X, and early prothrombinase. Humans produce two 3' splice variants, TFPIα and TFPIβ, which are differentially expressed in endothelial cells and platelets and possess distinct structural features affecting their inhibitory function. TFPI also undergoes alternative splicing of exon 2 within its 5' untranslated region. The role of exon 2 splicing in translational regulation of human TFPI isoform expression is investigated. Exon 2 splicing occurs in TFPIα and TFPIβ transcripts. Human tissue mRNA analysis uncovered a wide variability of exon 2 expression. Polysome analysis revealed a repressive effect of exon 2 on TFPIβ translation but not on TFPIα. Luciferase reporter assays further exposed strong translational repression of TFPIβ (90%) but not TFPIα. Use of a Morpholino to remove exon 2 from TFPI mRNA increased cell surface expression of endogenous TFPIβ. Exon 2 also repressed luciferase production (80% to 90%) when paired with the β-actin 3' untranslated region, suggesting that it is a general translational negative element whose effects are overcome by the TFPIα 3' untranslated region. Exon 2 is a molecular switch that prevents translation of TFPIβ. This is the first demonstration of a 5' untranslated region alternative splicing event that alters translation of isoforms produced via independent 3' splicing events within the same gene. Therefore, it represents a previously unrecognized mechanism for translational control of protein expression. Differential expression of exon 2 denotes a mechanism to provide temporal and tissue-specific regulation of TFPIβ-mediated anticoagulant activity.

Tumour expresion of tissue factor and tissue factor pathway inhibitor in ovarian cancer- relationship with venous thrombosis risk

Ovarian cancer is known to display a particular association with venous thromboembolism (VTE) with reports up to 42% of patients developing thromboembolic complications. Tissue Factor (TF) and its inhibitor Tissue Factor Pathway Inhibitor (TFPI) have been implicated in VTE risk in cancer. The aim of this study was to measure tumour derived TF and TFPI and to investigate their potential role in VTE in ovarian cancer patients. TF and TFPI mRNA expression was measured using TaqMan real time PCR in 99 ovarian tumour samples. Nineteen cases complicated by VTE were matched to 19 cases without VTE. TF and TFPI protein levels were measured using ELISA and immunohistochemistry was used to localize TF expression. The role of TF expression on overall survival was also determined. TF mRNA and protein expression was increased in tumours from patients with clear cell carcinoma (p<0.001). TF protein expression was also increased in endometroid carcinoma (P<0.01) compared with benign tumours. TFPI mRNA expression was increased in clear cell carcinoma (P<0.01). TF mRNA and antigen level was increased in malignant tumours of patients who developed VTE compared with matched malignant õtumours of patients who remained thrombosis free (P<0.01). There was no difference in TFPI expression between the two groups. TF expression in ovarian cancer is significantly higher in patients who develop VTE. TF expression was increased in clear cell ovarian cancer and endometroid cancer and this may explain the higher risk of VTE in these subgroups. TF derived from these tumours may be the trigger for VTE in ovarian cancer.

Shiga toxin downregulates tissue factor pathway inhibitor, modulating an increase in the expression of functional tissue factor on endothelium

IntroductionEndothelial expression of tissue factor (TF) may play a major role in (Stx)-related hemolytic uremic syndrome. We examined human umbilical vein endothelial cell (HUVEC) monolayers to determine the interaction between TF and TF pathway inhibitor (TFPI), hypothesizing that changes in TFPI modulate TF expression. Materials and MethodsWe studied 1) cell surface expression of globotriasylceramide (Gb3, the receptor for Stx) with Stx-1 (10 pM), TNFα (20Ng/ml), or Stx-1 plus TNFα compared to control, 2) gene expression of TF and TFPI, 3) total cellular and cell surface antigenic TF and TFPI, 4) TFPI secretion into supernatant, and 5) factor Xa production. Results and ConclusionsGb3 expression, negligible with control and Stx-1 alone, increased significantly with TNFα and with Stx-1 plus TNFα. TF mRNA increased 1.25±0.32- fold (N=9; p=0.041) with Stx-1 alone vs. 2.82±0.92-fold (N=13; p<0.0005) with TNFα alone. However, Stx-1 plus TNFα yielded a 6.51±3.48-fold increase (N=17; p<0.0005). TFPI mRNA decreased with TNFα (p<0.001) and Stx-1 plus TNFα (p<0.0005). Total cellular and cell surface TF antigen increased significantly with TNFα, but no further with Stx-1 plus TNFα. Total TFPI cellular and cell surface antigen levels, and TFPI secretion decreased significantly with Stx-1 plus TNFα. Median factor Xa production for Stx-1 plus TNFα vs TNFα alone increased (p<0.001) 3.24-fold. Our results indicate that a subinhibitory concentration of Stx-1 plus TNFα impairs TFPI gene expression, synthesis, cell-surface association, and secretion, leading to augmented functional TF.