Inhibitor Plasminogen Activator Research Articles

Cytokeratin 8 ectoplasmic domain binds urokinase-type plasminogen activator to breast tumor cells and modulates their adhesion, growth and invasiveness

BackgroundGeneration of plasmin is a characteristic of tumor cells, promoting the degradation of extracellular matrix, tumor progression and metastasis. The process is accelerated if plasminogen and plasminogen activator are bound to their cell surface receptors.ResultsIn this study we show that the monoclonal antibody that recognizes an epitope on the cytokeratin 8 (CK8) ectoplasmic domain (anti-CK MAb) inhibits plasminogen activation mediated by urokinase-type plasminogen activator (uPA) in MCF-7 and MCF-10A neoT cells. The ectoplasmic domain of CK8 acts as a binding site for plasminogen, however, by using confocal microscopy, we demonstrated that it is also co-localized with uPA. CK8, therefore, function also as a receptor for uPA on the cell surface, and the presence of anti-CK MAb may prevent the binding of uPA to a designated CK8 motif. The consequent inhibition of plasmin generation resulted in changed cell morphology, enhanced cell adhesion to fibronectin, reduced invasion potential, and an enhanced G1/S transition. Moreover, surface plasmon resonance analysis showed that the synthetic dodecapeptide corresponding to the epitope sequence (VKIALEVEIATY), binds uPA in the nanomolar range.ConclusionThese novel findings suggest a model in which CK8, together with uPA, plasminogen and fibronectin, constitutes a signaling platform capable of modulating cell adhesion/growth-dependent signal transduction in breast tumor cells. Anti-CK MAb, which competes for the binding site for uPA, could be used as an agent to reduce the invasive potential of breast tumor cells.

Lactobacillus casei modulates the inflammation-coagulation interaction in a pneumococcal pneumonia experimental model

BackgroundWe have previously demonstrated that Lactobacillus casei CRL 431 administration improved the resistance to pneumococcal infection in a mouse model.MethodsThis study examined the effects of the oral administration of Lactobacillus casei CRL 431 (L. casei) on the activation of coagulation and fibrinolytic systems as well as their inhibitors during a Streptococcus pneumoniae infection in mice.ResultsThe alveolo-capillary membrane was damaged and the coagulation system was also activated by the infection. As a consequence, we could see fibrin(ogen) deposits in lung histological slices, increased levels of thrombin-antithrombin complex (TATc) in bronchoalveolar lavage (BAL) and plasma, decrease in prothrombin activity (PT) and prolonged activated partial thromboplastin time test (APTT) values. Factor VII (FVII) and factor X (FX) were decreased in plasma, whereas fibrinogen (F) and factor VIII (FVIII) were increased. The low levels of protein C (PC) in BAL and plasma proved damage on inhibitory activity. The infected animals showed reduced fibrinolytic activity, evidenced by an increase in plasminogen activation inhibitor-1 (PAI-1) in BAL and plasma. The pathogen induced an increase of TNF-α, IL-1β and IL-6 in BAL and serum a few hours after challenge followed by a significant decrease until the end of the assayed period. IL-4 and IL-10 in BAL and serum were also augmented, especially at the end of the experiment. The animals treated with L. casei showed an improvement of alveolo-capillary membrane, lower fibrin(ogen) deposits in lung and decrease in TATc. APTT test and PT, FVII and FX activity were normalized. L. casei group showed lower F levels than control during whole experiment. In the present study no effect of L. casei on the recovery of the inhibitory activity was detected. However, L. casei was effective in reducing PAI-1 levels in BAL and in increasing anti-inflammatory ILs concentration.ConclusionL. casei proved effective to regulate coagulation activation and fibrinolysis inhibition during infection, leading to a decrease in fibrin deposits in lung. This protective effect of L. casei would be mediated by the induction of higher levels of IL-4 and IL-10 which could regulate the anti-inflammatory, procoagulant and antifibrinolytic effects of TNF-α, IL-1β and IL-6.

Green tea polyphenols inhibit plasminogen activator inhibitor-1 expression and secretion in endothelial cells

Compelling epidemiological evidence suggests that the consumption of green tea is associated with beneficial effects in prevention of cardiovascular diseases. Plasminogen activator inhibitor-1 (PAI-1) is known to play a pivotal role in cardiovascular diseases including arteriosclerosis and hypertension. Increased PAI-1 was found in atherosclerotic lesions, and high PAI-1 plasma levels were associated with coronary heart disease. To determine the effect and molecular mechanism of green tea polyphenols (GTPs) on the regulation of PAI-1 expression in endothelial cells, bovine aortic endothelial cells were incubated with GTPs, and PAI-1 expressions were measured by western blot and enzyme-linked immunosorbent assay, respectively. GTPs significantly reduced PAI-1 expression and secretion in a time-dependent and dose-dependent manner. Inhibition of phosphatidylinositol 3-kinase (PI3K) with wortmannin markedly reversed GTPs repression of PAI-1 expression. In addition, the GTP-induced inhibitory effect was associated with an increased of activation of the protein kinase Akt. These results suggest that GTPs inhibit PAI-1 expression and its release from endothelial cells through the PI3K/Akt pathway, which may contribute to cardiovascular protection.

Inhibitory effect of angiostatins on activity of the plasminogen/plasminogen activator system

Angiostatins, kringle-containing fragments of plasminogen, are potent inhibitors of angiogenesis. Effects of three angiostatin forms, K1-3, K1-4, and K1-4.5 (0-2 microM), on the rate of native Glu-plasminogen activation by its physiological activators in the absence or presence of soluble fibrin were investigated in vitro. Angiostatins did not affect the intrinsic amidolytic activities of plasmin and plasminogen activators of tissue type (tPA) and urokinase type (single-chain scuPA and two-chain tcuPA), but inhibited conversion of plasminogen to plasmin in a dose-dependent manner. All three angiostatins suppressed Glu-plasminogen activation by tcuPA independently of the presence of fibrin, and the inhibitory effect increased in the order: K1-3 < K1-4 < K1-4.5. The inhibitory effects of angiostatins on the scuPA activator activity were lower and further decreased in the presence of fibrin. Angiostatin K1-3 (up to 2 microM) had no effect, while 2 microM angiostatins K1-4 and K1-4.5 inhibited the fibrin-stimulated Glu-plasminogen activation by tPA by 50 and 100%, respectively. The difference in effects of the three angiostatins on the Glu-plasminogen activation by scuPA, tcuPA, and tPA in the absence or presence of fibrin is due to the differences in angiostatin structures, mechanisms of action, and fibrin-specificity of plasminogen activators, as well as due to the influence of fibrin on the Glu-plasminogen conformation. Angiostatins in vivo, which mimic plasminogen-binding activity, can inhibit plasminogen activation stimulated by various proteins (including fibrin) of extracellular matrix, thereby blocking cell migration and angiogenesis. The data of this work indicate that the inhibition of Glu-plasminogen activation under the action of physiological plasminogen activators by angiostatins can be implicated in the complex mechanism of their antiangiogenic and antitumor action.

Knockout of plasminogen activator inhibitor 1 gene reduces amyloid beta peptide burden in a mouse model of Alzheimer's disease

Accumulation of amyloid beta peptide (Aβ) in the brain is a pathological hallmark of Alzheimer's disease (AD); the underlying mechanism, however, is not well understood. In this study, we show that expression of plasminogen activator inhibitor 1 (PAI-1), a physiological inhibitor of tissue type and urokinase type plasminogen activators (tPA and uPA), increases with age in the brain of wild type and Aβ precursor protein-presenilin 1 (APP/PS1) transgenic mice as well as in AD patients. Most importantly, we show that knocking out the PAI-1 gene dramatically reduces Aβ burden in the brain of APP/PS1 mice but has no effect on the levels of full-length APP, alpha or beta C-terminal fragments. Furthermore, we show that knocking out the PAI-1 gene leads to increases in the activities of tPA and plasmin, and the plasmin activity inversely correlates with the amounts of SDS insoluble Aβ40 and Aβ42. Together, these data suggest that increased PAI-1 expression/activity contributes importantly to Aβ accumulation during aging and in AD probably by inhibiting plasminogen activation and thus Aβ degradation.

Two Families of Synthetic Peptides That Enhance Fibrin Turbidity and Delay Fibrinolysis by Different Mechanisms

When fibrin clots are formed in vitro in the presence of certain positively charged peptides, the turbidity is enhanced and fibrinolysis is delayed. Here we show that these two phenomena are not always linked and that different families of peptides bring about the delay of lysis in different ways. In the case of intrinsically adhesive peptides corresponding to certain regions of the fibrinogen gammaC and betaC domains, even though these peptides bind to fibrin(ogen) and enhance turbidity, the delay in lysis is mainly due to direct inhibition of plasminogen activation. In contrast, for certain pentapeptides patterned on fibrin B knobs, the delay in lysis is a consequence of how fibrin units assemble. On their own, these B knob surrogates can induce the gelation of fibrinogen molecules. The likely cause of enhanced clot turbidity and delay in fibrinolysis was revealed by a crystal structure of the D-dimer from human fibrinogen cocrystallized with GHRPYam, the packing of which showed the direct involvement of the ligand tyrosines in antiparallel betaC-betaC interactions.

Antimetastatic Potential of PAI-1–Specific RNA Aptamers

The serine protease inhibitor plasminogen activator inhibitor-1 (PAI-1) is increased in several cancers, including breast, where it is associated with a poor outcome. Metastatic breast cancer has a dismal prognosis, as evidenced by treatment goals that are no longer curative but are largely palliative in nature. PAI-1 competes with integrins and the urokinase plasminogen activator receptor on the surface of breast cancer cells for binding to vitronectin. This results in the detachment of tumor cells from the extracellular matrix, which is critical to the metastatic process. For this reason, we sought to isolate RNA aptamers that disrupt the interaction between PAI-1 and vitronectin. Through utilization of combinatorial chemistry techniques, aptamers have been selected that bind to PAI-1 with high affinity and specificity. We identified two aptamers, WT-15 and SM-20, that disrupt the interactions between PAI-1 and heparin, as well as PAI-1 and vitronectin, without affecting the antiprotease activity of PAI-1. Furthermore, SM-20 prevented the detachment of breast cancer cells (MDA-MB-231) from vitronectin in the presence of PAI-1, resulting in an increase in cellular adhesion. Therefore, the PAI-1 aptamer SM-20 demonstrates therapeutic potential as an antimetastatic agent and could possibly be used as an adjuvant to traditional chemotherapy for breast cancer.

Plasminogen activator inhibitor-1 (PAI-1) facilitates retinal angiogenesis in a model of oxygen-induced retinopathy.

Angiogenesis, or the formation of new retinal blood vessels, is a key feature of many proliferative retinal diseases including diabetic retinopathy, retinal vein occlusion, and retinopathy of prematurity. The aim of the present study was to investigate the role of the serine proteinase inhibitor plasminogen activator inhibitor -1 (PAI-1) in facilitating retinal angiogenesis. The temporal expression of PAI-1 was examined by real-time PCR, Western blot analysis, and immunohistochemistry in retinal tissues from mice with oxygen-induced retinopathy. The requirement for PAI-1 in facilitating the retinal angiogenic response in this model was examined by quantitating the angiogenic response with wild-type and PAI-1 null mice. The mechanism by which PAI-1 mediates angiogenesis was further investigated with isolated human retinal vascular endothelial cells. PAI-1 expression was upregulated in the retinas of mice with oxygen-induced retinopathy, which coincided with a significant increase in the expression of vitronectin in the retina of the experimental mice. There was significant reduction in the angiogenic response of PAI-1(-/-) mice compared with wild-type mice. PAI-1 promotes endothelial cell migration in vitro and facilitates the migration of cells on a vitronectin substrate by regulating alpha v integrin cell surface expression. These observations suggest a role for PAI-1 during retinal angiogenesis and point to a potential new therapeutic target in the prevention or treatment of retinal neovascularization seen in many ocular diseases.

Angiotensin II Induces Renal Plasminogen Activator Inhibitor-1 and Cyclooxygenase-2 Expression Post-Transcriptionally via Activation of the mRNA-Stabilizing Factor Human-Antigen R

Angiotensin (Ang) II-induced fibrosis of the kidney is characterized by the enhanced expression of profibrotic and proinflammatory genes, including the serine protease inhibitor plasminogen activator inhibitor-1 (PAI-1) and cyclooxygenase-2 (COX-2). In addition to transcriptional regulation, both genes are subject to post-transcriptional control by AU-rich destabilizing elements that reside within the 3' untranslated region of the mRNA. We demonstrated that the continuous infusion of AngII in rats induced fibrosis concomitant with a significant increase in glomerular PAI-1 and COX-2 expression levels. Using RNA pull-down assays and electromobility shift assays, we demonstrated the increased binding of the ubiquitous RNA-binding protein human-antigen R (HuR) to the mRNAs of both PAI-1 and COX-2 in the cytoplasmic fractions of renal homogenates from AngII-treated rats. Actinomycin D experiments in rat mesangial cells revealed that AngII stabilizes both mRNAs via HuR as proven by small interfering RNA. Mechanistically, AngII promotes an increase in nucleo-cytoplasmic HuR shuttling, which was blocked by the PKC inhibitor rottlerin and the type-I AngII (AT(1)) receptor antagonist valsartan but was unaffected by both AT(2) receptor antagonists PD123319 and CGP42112. Co-immunoprecipitation revealed that AngII treatment caused an increase in nuclear PKC-delta concomitant with binding to nuclear HuR both in vitro and in vivo. The post-transcriptional regulation of PAI-1 and COX-2 by PKC-delta-dependent HuR shuttling may contribute to the pathogenesis of hypertensive nephrosclerosis triggered by AngII.

Adipose tissue as an endocrine organ

The concept of adipose tissue as an inactive organ, which serves only for the accumulation and storage of energy substrates and triglycerides, has finally remained in the past. Studies of recent decades have shown that adipose tissue is very active in the metabolic aspect, and also produces many hormone-like substances, mediators, cytokines, chemokines that act at the local and systemic level, i.e., para- and endocrine. Regulatory substances produced in adipose tissue have received the general name adipokines or adipocytokines. Their study is the most actively developing area of ​​modern endocrinology. Adipokines made it possible to explain the pathophysiology of the long-known clinical phenomena of the close relationship between obesity, diabetes mellitus (DM), arteriosclerosis and insulin resistance. The list of adipokines produced in adipose tissue is very impressive and will undoubtedly be supplemented. By the beginning of 2008, the following adipokines were described: leptin, adiponectin, resistin, tumor necrosis factor a (TNF-a), interleukin-6 (IL-6), visfatin, apelin, omentine, vaspin, retinol-binding protein-4 (RBP-4) and other factors, including lipoprotein lipase, apolipoprotein E, complement factors, tissue factor, plasminogen activation inhibitor-1 (IAP-1), proteins of the renin angiotensin system (RAS). In addition, adipocytes express chemokines such as MCP-1 and RANTES.This review schematically presents the basic physiological and pathophysiological actions of known adipokines.

Tranexamic acid can inhibit tongue squamous cell carcinoma invasion in vitro

Tranexamic acid (TA) is an inhibitor of plasminogen activation commonly used in surgery. Plasmin, the end product of plasminogen activation, degrades fibrin in the thrombus, leading to thrombolysis. However, plasmin is also associated with progression of several cancers and with cancer-associated matrix metalloproteinase-9 (MMP-9) activation. As the gelatinases MMP-2 and -9 are involved in cancer progression, several antigelatinolytic drugs have been developed as potential anticancer therapeutics. We previously developed gelatinases targeting peptide CTT1 capable of inhibiting carcinoma growth. The effects of TA and CTT1 on tongue carcinoma aggressiveness were evaluated in an in vitro assay of human HSC-3 and SCC-25 cells. The cells were cultured with or without TA and CTT1 and their proMMP-9 production and activation were analysed with Western immunoblotting and gelatin zymography. Their effects on tongue carcinoma invasion were analysed in a Matrigel assay. Tranexamic acid alone and in combination with CTT1 can inhibit tongue SCC invasion in vitro, at least partially explained by its property of reducing the plasmin-mediated activation of proMMP-9. These data suggest that patients undergoing surgical therapy for large oral malignancies may cobenefit from prolonged TA therapy, because of its antithrombolytic and antitumour properties.

A potential serum panel for breast cancer diagnosis: ongoing clinical validation for its clinical implication.

Abstract Abstract #5006 Although every effort has been made to discover single potent biomarkers in oncology, the promising single biomarker often loses its clinical potency in the course of clinical validations. We aimed to construct and verify a biomarker panel with multiple proteins for breast cancer diagnosis. Using Surface-Enhanced Laser Desorption/ Ionization Time-of-Flight mass spectrometry (SELDI-TOF-MS) and microbead array system, epidermal growth factor (EGF), vascular cell adhesion molecule-1 (VCAM-1), CD40L, vitronectin, plasminogen activation inhibitor-1 (PAI-1), vitamin-D binding protein (VDBP), C-reactive protein (CRP), kininogen, apolipoprotein A1 and proapolipoprotein A1 were identified and validated as useful biomarkers for detection of breast cancer. The multiplexing panel (MP) which was constructed by combining algorithm (random forest, support vector machine) with above biomarkers showed that the diagnostic accuracy approached 91% in 216 test samples. A following double blind test verified that the diagnostic accuracy of the MP was 68% with an additional validation set including sera from 49 patients with breast cancer and 51 healthy women (sensitivity=74%; 95% confidence interval (CI)=58.9–85.0%, specificity=62.7%; 95% CI=48.1–75.9%, positive predictive value=65.5%; 95% CI=55.7-75.3%, negative predictive value=71.7%; 95% CI=61.7-80.35%). We suggest that these results support the potential use of the MP as an early detector of breast cancer. In order to validate the role and potency of the MP in routine clinical practice, a large scale clinical validation in a cohort consisting of 500 patients with breast cancer and the same number of healthy women are underway and the results will be released in the near future. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5006.

Plasminogen activator inhibitor-1 regulates neutrophil influx during acute pyelonephritis

Acute pyelonephritis, frequently caused by Escherichia coli, is a substantial health problem. Plasminogen activator inhibitor type-1 (PAI-1) not only inhibits plasminogen activation but is also involved in cell migration. To determine if it has a role in host defense, we induced pyelonephritis in PAI-1 gene knockout and wild-type mice by intravesical inoculation with uropathogenic E. coli 1677. Bacterial growth was determined on blood agar plates in portions of the kidneys homogenized in sterile saline. Kidney levels of PAI-1 were increased in infected compared to control mice, suggesting a physiological role for PAI-1 during pyelonephritis. The knockout mice had significantly more bacterial outgrowth in kidney homogenates compared to the wild-type mice. Strikingly, higher colony-forming units were accompanied by increased levels of the cytokines TNF-alpha, IL-1beta, and IL-6 in the kidneys of knockout mice, but levels of the chemokines KC and MIP-2 were not different. Remarkably, plasma levels of KC were higher, but renal neutrophil influx was significantly lower, in the knockout than in the wild-type mice. Our study shows that PAI-1 is critically involved in host defense against E. coli-induced acute pyelonephritis, in part, by modulating neutrophil influx.

PAI-1 and kidney fibrosis.

Substantial evidence demonstrates a link of increased plasminogen activator inhibitor-1 (PAI-1) and glomerulosclerosis and kidney fibrosis, providing a novel therapeutic option for prevention and treatment of chronic kidney diseases. Several mechanisms contributing to increased PAI-1 will be addressed, including classic key profibrotic factors such as the renin-angiotensin-system (RAS) and transforming growth factor-beta (TGF-b???and novel molecules identified by proteomic analysis, such as thymosin- b4. The fibrotic sequelae caused by increased PAI-1 in kidney depend not only on its classic inhibition of tissue-type and urokinase-type plasminogen activators (tPA and uPA), but also its influence on cell migration.

Role of viral receptors TLR3, RIG-I and MDA5 in mesothelial tissue-type plasminogen activator and plasminogen activator inhibitor-1 synthesis

Tissue-type plasminogen activator (t-PA) and its specific inhibitor plasminogen activator inhibitor-1 (PAI-1) are key mediators in the regulation of fibrin generation and fibrinolysis. Mesothelial cells (MC) line the inner surface of serosal cavities and are a source of procoagulant and fibrinolytic system components. Viral inflammation and infection of MC are a major problem in several organ systems including pleura, pericardium and peritoneum. MC express the viral receptors Toll-like receptor 3 (TLR3), RIG-I and MDA5. TLRs recognise molecular patterns associated with microbial pathogens and induce an immune response. TLR3 recognises dsRNA of viral origin as exemplified by poly (I:C) RNA, a synthetic analogue of viral dsRNA. The helicases RIG-I and MDA5 may also act as sensors of viral infections. Activation of these receptors by poly (I:C) RNA leads to an time- and dose-dependent increase of mesothelial PAI-1 synthesis and a decrease of t-PA expression. To show the specific effect of viral receptors knockdown experiments with siRNA specific for TLR3, RIG-I and MDA5 were performed. This finding of viral induced changes of t-PA and PAI-1 synthesis may indicate a novel link between viral infections and formation of mesothelial fibrin deposits and progression of viral associated disease of the pleura, peritoneum and pericardium.

Inhalation of urokinase-type plasminogen activator reduces airway remodeling in a murine asthma model

The airway remodeling that occurs in asthma is characterized by an excess of extracellular matrix deposition in the submucosa, hyperplasia/hypertrophy of smooth muscle, goblet cell metaplasia, and accumulation of fibroblasts/myofibroblasts. The urokinase-type plasminogen activator (uPA)/plasmin system participates in pericellular proteolysis and is capable of directly degrading matrix components, activating latent proteinases, and activating growth factors. In a mouse ovalbumin (OVA) asthma model, we increased plasminogen activator activity in the lung by administering exogenous uPA or by using mice genetically deficient in the uPA inhibitor plasminogen activator inhibitor-1 (PAI-1) to assess the role of this system in asthma pathogenesis. After intraperitoneal OVA sensitization, mice inhaled OVA plus uPA (500 IU/mouse) or saline by ultrasonic nebulization for 3 wk. When studied 24 h after the final exposure, the groups with upregulated plasmin activity had significantly reduced subepithelial fibrosis within the airway walls and had decreased airway hyperresponsiveness (AHR) to methacholine. Morphometric analysis showed that subepithelial wall thickening of the bronchi (subepithelial area ratio) was also reduced, as were collagen and alpha-smooth muscle actin. Upregulation of plasmin activity also increased the level of hepatocyte growth factor activity in bronchoalveolar lavage fluid, whereas the release of transforming growth factor-beta was decreased. The administration of uPA 1 wk after the last OVA inhalation also significantly reduced lung hydroxyproline content and AHR. These results show that enhancing uPA/plasmin activity lessens the airway remodeling in a murine asthma model.

Prospective Biomarker Trials Chemo N0 and NNBC-3 Europe Validate the Clinical Utility of Invasion Markers uPA and PAI-1 in Node-Negative Breast Cancer

Urokinase-type plasminogen activator (uPA) and its inhibitor plasminogen activator inhibitor-1 (PAI-1) are key factors in tumour invasion and metastasis. Increased levels of uPA and/or PAI-1 in primary tumour tissues correlate with tumour aggressiveness and poor patient outcome [1, 2]. In primary breast cancer, Duffy et al. [3] in 1988 were the first to show that high enzymatic activity of uPA in primary breast cancer tissues was correlated with advanced tumour stage and poor clinical outcome. In 1989, Janicke et al. [4] demonstrated that high uPA antigen levels in primary tumour tissue measured by enzyme-linked immunosorbent assay (ELISA) also predicted poor prognosis. At the same time, it also became apparent that not only antigen levels of uPA but also those of PAI-1 are of prognostic importance in node-negative and node-positive breast cancer patients [4, 5]. Subsequently, many international, mostly European, researchers validated that primary breast cancer patients, and in particular node-negative patients with high tumour tissue antigen content of uPA and/or PAI-1, have a worse probability of disease-free survival (DFS) and overall survival (OS) than patients with low levels of either or both biomarkers [6,7,8,9]. For clinical utility, the combination of uPA/PAI-1 (both low versus either or both high) is superior to either factor taken alone regarding risk group assessment [10]. uPA and PAI-1 render prognostic information independent of established prognostic factors such as tumour size, tumour grade, steroid hormone receptor status, menopausal status [10] and even HER2 status [11,12,13]. Next to their prognostic impact, uPA/PAI-1 also provide predictive information in early breast cancer. Patients with high uPA/PAI-1 have an enhanced benefit from adjuvant chemotherapy compared to those with low levels. Regarding adjuvant endocrine therapy, no such interaction between benefit and uPA/PAI-1 levels could be found [14]. A large meta-analysis conducted by the European Organisation for Research and Treatment of Cancer (EORTC) Receptor and Biomarker Group, comprising 8377 breast cancer patients from 18 independent collectives, validated the prognostic [15] and predictive impact of uPA/PAI-1 [16], thus achieving the highest level of evidence (LOE-I) for clinical utility of a cancer-associated biomarker, according to the American Society of Clinical Oncology (ASCO) tumour marker utility grading system (TMUGS) [17].

Apolipoprotein(a) inhibits the conversion of Glu-plasminogen to Lys-plasminogen: a novel mechanism for lipoprotein(a)-mediated inhibition of plasminogen activation.

Elevated plasma concentrations of lipoprotein(a) [Lp(a)] are associated with an increased risk for thrombotic disorders. Lp(a) is a unique lipoprotein consisting of a low-density lipoprotein-like moiety covalently linked to apolipoprotein(a) [apo(a)], a homologue of the fibrinolytic proenzyme plasminogen. Several in vitro and in vivo studies have shown that Lp(a)/apo(a) can inhibit tissue-type plasminogen activator-mediated plasminogen activation on fibrin surfaces, although the mechanism of inhibition by apo(a) remains controversial. Essential to fibrin clot lysis are a number of plasmin-dependent positive feedback reactions that enhance the efficiency of plasminogen activation, including the plasmin-mediated conversion of Glu-plasminogen to Lys-plasminogen. Using acid-urea gel electrophoresis to resolve the two forms of radiolabeled plasminogen, we determined whether apo(a) is able to inhibit Glu-plasminogen to Lys-plasminogen conversion. The assays were performed in the absence or presence of different recombinant apo(a) species, including point mutants, deletion mutants and variants that represent greater than 90% of the known apo(a) isoform sizes. Apo(a) substantially suppressed Glu-plasminogen conversion. Critical roles were identified for the kringle IV types 5-9 and kringle V; contributory roles for sequences within the amino-terminal half of the molecule were also observed. Additionally, with the exception of the smallest naturally-occurring isoform of apo(a), isoform size was found not to contribute to the inhibitory capacity of apo(a). These findings underscore a novel contribution to the understanding of Lp(a)/apo(a)-mediated inhibition of plasminogen activation: the ability of the apo(a) component of Lp(a) to inhibit the key positive feedback step of plasmin-mediated Glu-plasminogen to Lys-plasminogen conversion.

Intravenous administration of Tranexamic acid to control of hemorrhagic in cattle

Intravenous administration of tranexamic acid to control of hemorrhagic in cattle Tranexamic acid inhibits plasminogen activation so prevents fibrinolysis . in medicine, it is used to treat various conditions in which there are bleeding or risk of bleeding . some of the more common causes of hemorrhay in cattle are :abomasal ulcer, laceration of arteries in the wall of the vagina as a result of dystocia, and ruptured middle uterine artery during prolapse or tortion of uterus . Tranexamic acid (1 gr/kg , in one liter of saline , Qid , for 3 days ) was administered intravenously because of abomasal ulcer in 10 cattles to control of hemorrhagic . We think that tranexamic acid can control hemorrhagic , effectively . some drugs are used to assist coagulation and arrest hemorrhagic in some cases , but there is limit information on their efficacy . We can find no reports of clinical administration of tranexamic acid in veterinary literature . Therefore , this can be the first published report of intravenous administration of tranexamic acid in cattel .

Vitronectin inhibits plasminogen activator inhibitor-1-induced signalling and chemotaxis by blocking plasminogen activator inhibitor-1 binding to the low-density lipoprotein receptor-related protein

We have previously reported that the serpin plasminogen activator inhibitor-1 activates the Janus kinase (Jak)/signal transducer and activator of transcription (Stat) signalling pathway and stimulates cell migration by binding to the low-density lipoprotein receptor-related protein. All the free forms (cleaved, latent or active) of this inhibitor were shown to be motogenic. However, the plasminogen activator inhibitor-1 can also interact with vitronectin which acts as a cofactor by increasing the half-life of the active form of the serpin. Since vitronectin influences most of the biological functions of the plasminogen activator inhibitor-1, we explored the effects of vitronectin on signalling and cell migration induced by this serpin. We found that the interaction between vitronectin and the plasminogen activator inhibitor-1 suppressed signalling and cell migration. In fact, a purified vitronectin1–97/plasminogen activator inhibitor-1 complex was not chemotactic. Vitronectin interaction with the plasminogen activator inhibitor-1 blocks the binding of this serpin to its motogenic receptor, the low-density lipoprotein receptor-related protein. Consequently, vitronectin inhibits the activation of the Janus kinase/signal transducer and activator of transcription signalling pathway by the plasminogen activator inhibitor-1 and subsequent cell migration. In conclusion, we have unveiled a new inhibitory role of vitronectin, which turns off the intracellular signalling and migration-promoting activity of the plasminogen activator inhibitor-1. Thus, the motogenic (cleaved, latent or active) and non-motogenic (in complex with vitronectin) forms of the plasminogen activator inhibitor-1 have different properties that may explain the rather contrasting physiological and pathological roles of this serpin.