Human plasminogen activator inhibitor-1 gene. Promoter and structural gene nucleotide sequences

L, K. N, Murali S, Agarwal P, Rani E, F. AM. The Role of the Plasminogen Activator Inhibitor 1 ( PAI1 ) in Ovarian Cancer: Mechanisms and Therapeutic Implications

Ovarian cancer (OC) is one among most significantly fatal gynecological cancers, with late-stage detection and an inadequate prognosis. Plasminogen activator inhibitor-1 ( PAI1 ) gene anticipates negative outcomes in many different kinds of malignancies. Several research investigations are currently being done to examine the biological role of PAI1 in OC and the possible benefits of targeted pharmacotherapies. The PAI1 gene has been linked to the emergence and development of cancer in the ovary. PAI1 , an inhibitor of serine protease, influences the fibrinolysis and extracellular matrix remodeling, both of which are crucial for tumor expansion and metastatic growth. PAI1 levels have been discovered to be subsequently more elevated in malignant ovarian tissues than in usual ovarian tissue, demonstrating a potential connection among PAI1 overexpression and OC development. PAI1 promotes tumor cell proliferation, movement, and an invasion by influencing the urokinase-plasminogen activators and through interactions with cell surface receptors. In addition, PAI1 gene contributes to angiogenesis and apoptotic cell death, which contribute to the more hostile phenotypes of OC. The prognostic and therapeutic consequences of focusing on PAI1 in OC are explored, demonstrating PAI1 's potential to be a biomarker and emphasizing for novel treatment approaches. The PAI1 gene possesses several functions in OC, affecting tumor development, an invasion, and metastatic growth. Comprehending the complicated interactions and mechanisms that regulate PAI1 in OC may lead to more efficient evaluation and treatment strategies and ultimately enhance patient outcomes.

The Role of Plasminogen Activator Inhibitor Type 1 (PAI-1) in Placenta-Mediated Pregnancy Complications: A Systematic Review

Plasminogen activator inhibitor type 1 (PAI-1) is a main inhibitor of fibrinolysis. The PAI-1 gene (SERPINE1) harbors genetic variants with the potential of modifying plasma levels of PAI-1. A delicate balance exists between the coagulation and fibrinolytic system, and changes in PAI-1 have been suggested to compromise establishment of a successful pregnancy. Therefore, this systematic review investigated the association between genetic variants and/or plasma levels of PAI-1 and placenta-mediated pregnancy complications. An extensive literature search was conducted in PubMed, Embase, and Web of Science on the 29^th of April 2021. All studies underwent quality rating according to The Study Quality Assessment Tools checklist provided by National Heart, Lung and Blood Institute. A total of 71 studies were included, among which 60 studies investigated PAI-1 genotypes and 11 studies measured PAI-1 plasma levels. In 32 out of 59 studies, no association was found between the PAI-1 4G/5G polymorphism (rs1799768) and placenta-mediated pregnancy complications, which was stated as no significant difference in the genotype distribution comparing women with and without placenta-mediated pregnancy complications or no significantly increased odds of placenta-mediated pregnancy complications carrying the 4G/4G or 4G/5G genotype. Eight out of 11 studies reported significantly higher PAI-1 plasma levels in preeclamptic women than in women without preeclampsia. In conclusion, no clear evidence indicates that PAI-1 polymorphisms are associated with placenta-mediated pregnancy complications, and the possible association between high PAI-1 plasma levels and preeclampsia needs further investigations. Thus, investigation of PAI-1 genotypes and PAI-1 plasma levels does not currently seem to have a place in daily clinical practice managing placenta-mediated pregnancy complications.

Targeting PAI-1 in Cardiovascular Disease: Structural Insights Into PAI-1 Functionality and Inhibition

Plasminogen activator inhibitor-1 (PAI-1), a member of the serine protease inhibitor (serpin) superfamily with antiprotease activity, is the main physiological inhibitor of tissue-type (tPA) and urokinase-type (uPA) plasminogen activators (PAs). Apart from being crucially involved in fibrinolysis and wound healing, PAI-1 plays a pivotal role in various acute and chronic pathophysiological processes, including cardiovascular disease, tissue fibrosis, cancer, and age-related diseases. In the prospect of treating the broad range of PAI-1-related pathologies, many efforts have been devoted to developing PAI-1 inhibitors. The use of these inhibitors, including low molecular weight molecules, peptides, antibodies, and antibody fragments, in various animal disease models has provided ample evidence of their beneficial effect in vivo and moved forward some of these inhibitors in clinical trials. However, none of these inhibitors is currently approved for therapeutic use in humans, mainly due to selectivity and toxicity issues. Furthermore, the conformational plasticity of PAI-1, which is unique among serpins, poses a real challenge in the identification and development of PAI-1 inhibitors. This review will provide an overview of the structural insights into PAI-1 functionality and modulation thereof and will highlight diverse approaches to inhibit PAI-1 activity.

Is There a Genetic Predisposition to Postoperative Adhesion Development?

Adhesions are permanent fibrovascular bands between peritoneal surfaces, which develop following virtually all body cavity surgeries. The susceptibility to develop, and the severity, of adhesions following intra-abdominal surgery varies within and between individuals, suggesting that heritable factors influence adhesion development. In this manuscript, we discuss the pathophysiology of adhesion development from the perspective of genetic susceptibility. We restrict our discussion to genes and single-nucleotide polymorphisms (SNPs) that are specifically involved in, or that cause modification of, the adhesion development process. We performed a literature search using the PubMed database for all relevant English language articles up to March 2020 (n = 186). We identified and carefully reviewed all relevant articles addressing genetic mutations or single-nucleotide polymorphisms (SNPs) that impact the risk for adhesion development. We also reviewed references from these articles for additional information. We found several reported SNPs, genetic mutations, and upregulation of messenger RNAs that directly or indirectly increase the propensity for postoperative adhesion development, namely in genes for transforming growth factor beta, vascular endothelial growth factor, interferon-gamma, matrix metalloproteinase, plasminogen activator inhibitor-1, and the interleukins. An understanding of genetic variants could provide insight into the pathophysiology of adhesion development. The information presented in this review contributes to a greater understanding of adhesion development at the genetic level and may allow modification of these genetic risks, which may subsequently guide management in preventing and treating this challenging complication of abdominal surgery. In particular, the information could help identify patients at greater risk for adhesion development, which would make them candidates for anti-adhesion prophylaxis. Currently, agents to reduce postoperative adhesion development exist, and in the future, development of agents, which specifically target individual genetic profile, would be more specific in preventing intraperitoneal adhesion development.

Plasminogen Activator Inhibitor Type-1 as a Regulator of Fibrosis

Fibrosis is known as a frequent and irreversible pathological condition which is associated with organ failure. Tissue fibrosis is a central process in a variety of chronic progressive diseases such as diabetes, hypertension, and persistent inflammation. This state could contribute to chronic injury and the initiation of tissue repair. Fibrotic disorders represent abnormal wound healing with defective matrix turnover and clearance that lead to excessive accumulation of extracellular matrix components. A variety of identified growth factors, cytokines, and persistently activated myofibroblasts have critical roles in the pathogenesis of fibrosis. Irrespective of etiology, the transforming growth factor-β pathway is the major driver of fibrotic response. Plasminogen activator inhibitor-1 (PAI-1) is a crucial downstream target of this pathway. Transforming growth factor-β positively regulates PAI-1 gene expression via two main pathways including Smad-mediated canonical and non-canonical pathways. Overexpression of PAI-1 reduces extracellular matrix degradation via perturbing the plasminogen activation system. Indeed, elevated PAI-1 levels inhibit proteolytic activity of tissue plasminogen activator and urokinase plasminogen activator which could contribute to a variety of inflammatory elements in the injury site and to excessive matrix deposition. This review summarizes the current knowledge of critical pathways that regulate PAI-1 gene expression and suggests effective approaches for the treatment of fibrotic disease. J. Cell. Biochem. 119: 17-27, 2018. © 2017 Wiley Periodicals, Inc.

Functional stability of plasminogen activator inhibitor-1

Plasminogen activator inhibitor-1 (PAI-1) is the main inhibitor of plasminogen activators, such as tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA), and a major regulator of the fibrinolytic system. PAI-1 plays a pivotal role in acute thrombotic events such as deep vein thrombosis (DVT) and myocardial infarction (MI). The biological effects of PAI-1 extend far beyond thrombosis including its critical role in fibrotic disorders, atherosclerosis, renal and pulmonary fibrosis, type-2 diabetes, and cancer. The conversion of PAI-1 from the active to the latent conformation appears to be unique among serpins in that it occurs spontaneously at a relatively rapid rate. Latency transition is believed to represent a regulatory mechanism, reducing the risk of thrombosis from a prolonged antifibrinolytic action of PAI-1. Thus, relying solely on plasma concentrations of PAI-1 without assessing its function may be misleading in interpreting the role of PAI-1 in many complex diseases. Environmental conditions, interaction with other proteins, mutations, and glycosylation are the main factors that have a significant impact on the stability of the PAI-1 structure. This review provides an overview on the current knowledge on PAI-1 especially importance of PAI-1 level and stability and highlights the potential use of PAI-1 inhibitors for treating cardiovascular disease.

Effects of selenomethionine in irradiated human thyroid epithelial cells and tumorigenicity studies

The objectives of the present study were to characterize γ-ray, 1 GeV/n proton, and 1 GeV/n iron ion radiation-induced adverse biological effects in terms of toxicity and transformation of HTori-3 human thyroid epithelial cells; to evaluate the ability of L-selenomethionine (SeM) to protect against radiation-induced transformation when present at different times during the assay period; and to evaluate the tumorigenicity of HTori-3 cells derived from anchorage-independent colonies following iron ion radiation exposure. Cell survival was determined by a clonogenic assay, transformation was measured by a soft agar colony formation assay, and the tumorigenic potential of the cells was determined by injecting them subcutaneously into athymic nude mice and monitoring tumor formation. The results demonstrate that exposure of HTori-3 cells to γ-ray, proton, or iron ion radiation resulted in decreased clonogenic survival, which persisted for weeks after the radiation exposure. Treatment with SeM initiated up to 7 days after the radiation exposure conferred significant protection against radiation-induced anchorage-independent growth. HTori-3 cells derived from all evaluated anchorage-independent colonies formed tumors when injected into athymic nude mice, indicating that these cells are tumorigenic and that anchorage-independent colony growth is a reliable surrogate endpoint biomarker for the radiation-induced malignant transformation of HTori-3 cells.

Evaluation of the association of urokinase plasminogen activator system gene polymorphisms with susceptibility and pathological development of hepatocellular carcinoma

BACKGROUND

The urokinase plasminogen activator (uPA) system is a serine proteinase system involved in extracellular matrix (ECM) degradation. The levels of uPA system components in tumor tissues are implicated as prognostic biomarkers in a wide range of malignancies. Although the contributions of uPA system components to the formation of many types of cancer are well known, their possible association with the prediction of risk and prognosis of hepatocellular carcinoma (HCC) remains poorly investigated.

METHODS

A total of 102 HCC patients and 344 controls were recruited. Genetic polymorphisms of uPA system genes, including uPA, uPA receptor (uPAR), and plasminogen activator inhibitor (PAI)-1, were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) genotyping analysis.

RESULTS

When individuals were classified into male and female subgroups to estimate adjusted odds ratios (AORs) with their 95% confidence intervals (CIs) of each uPA system gene, the HCC risks of males and females with PAI-1 5G/5G genotype were 6.06-fold (95% CI = 1.39-26.36) and 0.04-fold (95% CI = 0.003-0.69), respectively, as compared with those with PAI-1 4G/4G genotype. High risk for hepatitis B surface antigen (HBsAg)-positive clinical status and significantly higher serum aspartate aminotransferase (AST) concentration were exhibited in HCC patients with PAI-1 4G/5G and 5G/5G genotypes as compared with 4G/4G homozygotes.

CONCLUSIONS

The results suggest that PAI-1 genotypes could be an important factor contributing to increased susceptibility and pathological development of HCC in Taiwanese population.

Increased expression of plasminogen activator inhibitor type-1 (PAI-1) in HEPG2 cells induced by insulin mediated by the 3'-untranslated region of the PAI-1 gene and its pharmacologic implications

OBJECTIVE

Insulin increases, through several molecular mechanisms, expression of plasminogen activator inhibitor-1 (PAI-1), the major physiologic inhibitor of fibrinolysis. This phenomenon has been implicated as a cause of accelerated coronary artery disease and the increased incidence of acute coronary syndromes associated with type 2 diabetes. We have previously reported that physiologic and pharmacologic concentrations of insulin induce PAI-1 synthesis in human HepG2 cells and that simvastatin can attenuate its effects. This study was performed to further elucidate mechanisms responsible for the insulin-induced PAI-1 production.

METHODS

Concentrations of PAI-1 mRNA were determined by real-time PCR, and PAI-1 protein was assayed by western blotting. PAI-1 promoter (-829 to +36 bp) activity was assayed with the use of luciferase reporter assays. The potential role of the 3'-untranslated region (UTR) in the PAI-1 gene was assayed with the use of luciferase constructs containing the 3'-UTR. Oxidative stress was measured by loading cells with carboxy-2,7 dichlorodihydrofluorescein.

RESULTS

Insulin increased PAI-1 promoter activity, PAI-1 mRNA, and accumulation of PAI-1 protein in the conditioned media. Insulin-inducible PAI-1 promoter activity was attenuated by simvastatin. Experiments performed with luciferase reporters containing the 3'-UTR showed that insulin increased luciferase activity through this region. Insulin also increased oxidative stress. Both insulin-inducible luciferase activity through the 3'-UTR and oxidative stress were attenuated by simvastatin.

CONCLUSION

Insulin can increase PAI-1 expression through multiple mechanisms including induction mediated by the 3'-UTR of the PAI-1 gene. Accordingly, beneficial pleiotropic effects of statins on coronary artery disease may be attributable, in part, to attenuation of overexpression of PAI-1 mediated by the 3'-UTR in syndromes of insulin resistance (such as the metabolic syndrome) and type 2 diabetes.

Adenoviral targeting of gene expression to tumors

Using biochemical, imaging and histological methods, we employed transcriptional targeting to increase the specificity of tumor gene expression in vivo for intravenously administered recombinant adenovirus vectors. Surprisingly, the relative specificity of tumor expression in comparison to other tissues was increased for a constitutively expressing recombinant adenovirus, AdCMVLuc, by simply reducing the viral dose. Even at lower doses, however, the high frequency of viral infection and transgene expression in the liver using constitutive promoters still represents a substantial problem. To further augment tumor specificity, we constructed a series of adenoviruses expressing luciferase from several other promoters and tested their ability to selectively transcribe genes in tumor cells both in vitro and in vivo. Constitutively active viral promoters (RSV, SRα) varied widely in their tumor selectivity, but hypoxia-responsive promoters (carbonic anhydrase 9, PAI-1, SOD2, and several chimeric constructs) demonstrated the most tumor-selective expression. Our results show that tumor targeting to HT1080 fibrosarcomas was readily achieved using transcriptional targeting mechanisms. We attribute the relatively high level of gene transfer and expression in HT1080 tumors in vivo to increased viral access to the tumor, presumably due to discontinuities in tumor vasculature and augmented expression from stress-responsive promoters in the hypoxic and inflammatory tumor microenvironment.

A-G-4G haplotype of PAI-1 gene polymorphisms -844 G/A, HindIII G/C, and -675 4G/5G is associated with increased risk of ischemic stroke caused by small vessel disease

BACKGROUND

Plasminogen activator inhibitor type 1 (PAI-1) is the major inhibitor of fibrinolysis. It was reported that PAI-1 gene polymorphisms affected PAI-1 level and might therefore influence the risk of vascular diseases, including stroke. We studied the association of three common polymorphisms in PAI-1 gene (-844 G/A, -675 4G/5G, and HindIII G/C) with the odds of different causes of ischemic stroke.

METHODS

We studied 390 patients with ischemic stroke due to large vessel disease (n = 117), small vessel disease (n = 121), and cardioembolism (n = 152) as well as 291 controls. The etiology of ischemic stroke was established using TOAST criteria. PAI-1 polymorphisms were genotyped with restriction fragment length polymorphism and single strand conformation polymorphism method.

RESULTS

A-G-4G haplotype of PAI-1 gene was found more frequently in stroke patients with small vessel disease than in control subjects (44.9% vs 35.7%; P = 0.02). No association was found between investigated genotype or allele frequencies and distinct causes of ischemic stroke.

CONCLUSIONS

Our results demonstrate that A-G-4G PAI-1 gene haplotype is associated with increased risk of small vessel disease stroke, but this study does not support an association of -844 G/A, -675 4G/5G, and HindIII G/C PAI-1 gene polymorphisms with particular etiology of ischemic stroke.

The role of plasminogen activator inhibitor 1 in renal and cardiovascular diseases

The 50 kDa glycoprotein plasminogen activator inhibitor 1 (PAI-1) is the major physiological inhibitor of tissue-type and urokinase-type plasminogen activator. These two molecules convert inactive plasminogen into its fibrin-degrading form, plasmin. Plasma and tissue concentrations of PAI-1 are extremely low under normal circumstances but increase under pathologic conditions. This increase is mediated by many factors, including reactive oxygen species. Increased PAI-1 activity is associated with an increased risk of ischemic cardiovascular events and tissue fibrosis. Whereas the antifibrinolytic property of PAI-1 derives mainly from its inhibition of serine proteases, its profibrotic actions seem to derive from a capacity to stimulate interstitial macrophage recruitment and increase transcription of profibrotic genes, as well as from inhibition of serine proteases. Despite studies in mice that lack or overexpress PAI-1, the biological effects of this molecule in humans remain incompletely understood because of the complexity of the PAI-1-plasminogen-activator-plasmin system. The cardioprotective and renoprotective properties of some currently available drugs might be attributable in part to inhibition of PAI-1. The development of an orally active, high-affinity PAI-1 inhibitor will provide a potentially important pharmacological tool for further investigation of the role of PAI-1 and might offer a novel therapeutic strategy in renal and cardiovascular diseases.

Fibrinolysis, inflammation, and regulation of the plasminogen activating system

The maintenance of a given physiological process demands a coordinated and spatially regulated pattern of gene regulation. This applies to genes encoding components of enzyme cascades, including those of the plasminogen activating system. This family of proteases is vital to fibrinolysis and dysregulation of the expression pattern of one or more of these proteins in response to inflammatory events can impact on hemostasis. Gene regulation occurs on many levels, and it is apparent that the genes encoding the plasminogen activator (fibrinolytic) proteins are subject to both direct transcriptional control and significant post-transcriptional mechanisms. It is now clear that perturbation of these genes at either of these levels can dramatically alter expression levels and have a direct impact on the host's response to a variety of physiological and pharmacological challenges. Inflammatory processes are well known to impact on the fibrinolytic system and to promote thrombosis, cancer and diabetes. This review discusses how inflammatory and other signals affect the transcriptional and post-transcriptional expression patterns of this system, and how this modulates fibrinolysis in vivo.

The genetic heterogeneity of uterine leiomyomata

Research investigating the genetics of UL has already been successful in gathering epidemiologic evidence for heritability, establishing the clonal and mosaic nature of these tumors, correlating genotypic and phenotypic characteristics, defining cytogenetic subgroups, and identifying specific genes involved in tumorigenesis. Although UL are known to be benign tumors, the impact they have on the lives of so many women can only be described as "malignant". For this reason, continuing the quest to ascertain the genes, functions, and mechanisms integral to UL development is absolutely imperative. Genetic tests for personalized medical management of women with fibroids is at the threshold for providing the most appropriate treatments (Fig. 3), and combined with developing less invasive therapies portends a brighter future for a major health problem for women.

Identification of a peroxisome proliferator responsive element (PPRE)-like cis-element in mouse plasminogen activator inhibitor-1 gene promoter

PAI-1 is expressed and secreted by adipose tissue which may mediate the pathogenesis of obesity-associated cardiovascular complications. Evidence is presented in this report that PAI-1 is not expressed by preadipocyte, but significantly induced during 3T3-L1 adipocyte differentiation and the PAI-1 expression correlates with the induction of peroxisome proliferator-activated receptor gamma (PPARgamma). A peroxisome proliferator responsive element (PPRE)-like cis-element (-206TCCCCCATGCCCT-194) is identified in the mouse PAI-1 gene promoter by electrophoretic mobility shift assay (EMSA) combined with transient transfection experiments; the PPRE-like cis-element forms a specific DNA-protein complex only with adipocyte nuclear extracts, not with preadipocyte nuclear extracts; the DNA-protein complex can be totally competed away by non-labeled consensus PPRE, and can be supershifted with PPARgamma antibody. Mutation of this PPRE-like cis-element can abolish the transactivation of mouse PAI-1 promoter mediated by PPARgamma. Specific PPARgamma ligand Pioglitazone can significantly induce the PAI-1 expression, and stimulate the secretion of PAI-1 into medium.

Activation of peroxisome proliferator-activated receptor-gamma decreases pancreatic cancer cell invasion through modulation of the plasminogen activator system

Cancer cell invasion and metastasis require the concerted action of several proteases that degrade extracellular matrix proteins and basement membranes. Recent reports suggest the plasminogen activator system plays a critical role in pancreatic cancer biology. In the present study, we determined the contribution of the plasminogen activator system to pancreatic cancer cell invasion in vitro. Moreover, the effect of peroxisome proliferator-activated receptor (PPAR)-gamma ligands, which are currently in clinical use as antidiabetic drugs and interestingly seem to display antitumor activities, on pancreatic cancer cell invasion and the plasminogen activator system was assessed. Expression of components of the plasminogen activator system [i.e., urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor-1, and uPA receptor] was detected in six human pancreatic cancer cell lines. Inhibition of urokinase activity by specific synthetic compounds reduced baseline pancreatic cancer cell invasion. The PPAR-gamma ligands 15-deoxy-Delta12,14-prostaglandin J2 and ciglitazone also attenuated pancreatic cancer cell invasion. This effect was abrogated by dominant-negative PPAR-gamma receptors and pharmacologic PPAR-gamma inhibitors. Moreover, activation of PPAR-gamma by ligands increased plasminogen activator inhibitor-1 and decreased uPA levels in pancreatic cancer cells, and this was accompanied by a reduction in total urokinase activity. The present study shows that the plasminogen activator system plays an integral role in pancreatic cancer cell invasion in vitro. Activation of the nuclear receptor PPAR-gamma by ligands reduced pancreatic cancer cell invasion, which was largely mediated by modulation of the plasminogen activator system. These findings further underscore the potential role of PPAR-gamma ligands as therapeutic agents in pancreatic cancer.

Plasminogen Activator Inhibitor-1 Promoter Polymorphism is Not Associated With the Aggressiveness of Disease in Prostate Cancer

AIMS

PAI-1 (plasminogen activator inhibitors-1) regulates plasminogen activation, and is related to tumour development. This study aims to test whether the promoter polymorphism in the PAI-1 gene is related to the aggressiveness of disease in prostate cancer.

MATERIALS AND METHODS

In the present study, Taqman SNP genotyping assay was used to detect PAI-1 4G/5G polymorphism in DNA from paraffin-embedded tissues of 98 Caucasian patients with prostate cancer.

RESULTS

The distribution of the genotypes is in Hardy-Weinberg equilibrium. The genotype had no statistically significant relationship with other prognostic factors. Similar risks for recurrence were seen in individuals with the 4G/4G and 4G/5G genotypes compared to those with 5G/5G genotype (odds ratio [OR] 2.65, 95% CI: 0.41-16.94, P = 0.30; OR = 2.19, 95% CI: 0.38-12.49, P = 0.38).

CONCLUSION

We concluded that PAI-1 promoter polymorphism is not associated with the aggressiveness of disease in prostate cancer.

Increased tissue-type plasminogen activator: a facade in the fibrinolytic system in type 2 diabetes

To determine whether the increased concentration in blood of total tissue-type plasminogen activator (t-PA), accompanying increased plasminogen activator inhibitor type-1 (PAI-1) seen with diabetes reflects increased free t-PA and hence activity or simply increased t-PA complexed with PAI-1, we measured each in 39 people with type 2 diabetes. The increased total t-PA occurred in the absence of an increase in t-PA activity detectable in venous blood samples despite the increase in the concentration of total t-PA protein.

BACKGROUND

Type 2 diabetes is known to be associated with increased concentrations in blood of total tissue-type plasminogen activator (t-PA) [free t-PA plus t-PA complexed with plasminogen activator inhibitor type-1 (PAI-1)] and PAI-1. This study was performed to determine whether the increased total t-PA is indicative of increased t-PA activity attributable to free t-PA or whether it is simply a manifestation of compensatory processes maintaining t-PA activity detectable in venous blood samples at normal or subnormal levels.

METHODS

Total t-PA, free t-PA, and PAI-1 antigen and activity were measured by enzyme-linked immunosorbent assay and immunofunctional chromogenic substrate kinetic assays in peripheral venous blood samples obtained under fasting conditions from 39 people with type 2 diabetes.

RESULTS

The results indicate that both PAI-1 and total t-PA antigen concentrations were increased in association with diabetes but the concentration of free t-PA and hence the t-PA activity was not. Thus, the increased total t-PA is a facade potentially masking the impaired fibrinolytic system activity associated with type 2 diabetes.

CONCLUSIONS

The results indicate that the increase in the concentration of total t-PA protein in blood of people with diabetes occurs in the absence of an increase in free t-PA. Hence t-PA activity detectable in peripheral venous blood samples does not increase and may even decline modestly.

A truncated plasminogen activator inhibitor-1 protein blocks the availability of heparin-binding vascular endothelial growth factor A isoforms

We have made deletions of the porcine plasminogen activator inhibitor-1 (PAI-1) gene to obtain recombinant truncated PAI-1 proteins to examine functions of the PAI-1 isoforms. We previously reported that one recombinant truncated protein, rPAI-1(23), induces the formation of angiostatin by cleaving plasmin. The rPAI-1(23) protein is also able to bind urokinase plasminogen activator and plasminogen and then reduce the amount of plasmin that is formed. We have now prepared three different truncated rPAI-1 proteins and demonstrate that PAI-1 conformations control the release of heparin-binding vascular endothelial growth factor (VEGF) isoforms. The rPAI-1(23) isoform can regulate the functional activity of heparan sulfate-binding VEGF-A isoforms by blocking the activation of VEGF from heparan sulfate. The rPAI-1(23) conformation induced extensive apoptosis in cultured endothelial cells and thus reduced the number of proliferating cells. The rPAI-1(23) isoform inhibited migration of VEGF-stimulated sprouting from chick aortic rings by 65%, thus displaying a role in anti-angiogenic mechanisms. This insight into anti-angiogenic functions related to PAI-1 conformational changes could provide potential intervention points in angiogenesis associated with atherosclerotic plaques and cancer.

Plasminogen activator inhibitor-1 is a major stress-regulated gene: implications for stress-induced thrombosis in aged individuals

Plasminogen activator inhibitor-1 (PAI-1) is one of the primary inhibitors of the fibrinolytic system and has been implicated in a variety of thrombotic disorders. In this report, stress-induced changes in murine PAI-1 gene expression were investigated to study the role of this inhibitor in the development of stress-induced hypercoagulability. Restraint stress led to a dramatic induction of plasma PAI-1 antigen and of tissue PAI-1 mRNA with maximum induction in adipose tissues. In situ hybridization analysis of the stressed mice revealed that strong signals for PAI-1 mRNA were localized to hepatocytes, renal tubular epithelial cells, adrenomedullar chromaffin cells, neural cells in the paraaortic sympathetic ganglion, vascular smooth muscle cells, and adipocytes, but not to endothelial cells. These observations indicate that the stress induces the PAI-1 gene expression in a tissue-specific and cell type-specific manner. The induction of PAI-1 mRNA by restraint stress was greater than that observed for heat shock protein, a typical stress protein, suggesting that PAI-1 is one of the most highly induced stress proteins. Importantly, the magnitude of induction of PAI-1 mRNA by stress increased markedly with age, and this increase in PAI-1 correlated with tissue thrombosis in the older stressed mice. Moreover, much less tissue thrombosis was induced by restraint stress in young and aged PAI-1-deficient mice compared with age-matched wild-type mice. These results suggest that the large induction of PAI-1 by stress increases the risk for thrombosis in the older populations, and that the adipose tissue may be involved.

Post-transcriptional regulation of gene expression in the plasminogen activation system

The urokinase-mediated plasminogen activation (PA) system has been shown to play a key role in cell migration and tissue invasion by regulating both cell-associated proteolysis and cell-cell and cell-matrix interactions. The expression and activity of the components of this complex system are strictly regulated. The control of the expression occurs both at transcriptional and post-transcriptional levels. This review is focused on the post-transcriptional regulation of gene expression of all components of the PA system.

Plasminogen activator inhibitor-1 gene polymorphism 4G/4G genotype and lupus nephritis in Chinese patients

BACKGROUND

Abnormal regulation in the coagulation and fibrinolytic system may play an important role in mediating glomerular damage in lupus nephritis. Indeed, glomerular thrombosis occurs frequently in lupus nephritis and predicts the future development of glomerular sclerosis. In the murine model of active lupus nephritis, plasminogen activator inhibitor-1 (PAI-1) gene was overexpressed throughout the kidney, both within the glomeruli and also in tubules and vessels. The level of PAI-1 expression in the tissues appeared to correlate with the progression of lupus nephritis. Recently, a single base pair insertion/deletion 4G/5G polymorphism of the PAI-1 gene has been identified and shown to alter plasma PAI-1 activity. This study was therefore conducted to determine the association of the 4G/5G polymorphism of the PAI-1 gene with the development and severity of lupus nephritis.

METHODS

The PAI-1 gene polymorphism of 118 systemic lupus erythematosus (SLE) patients and 103 healthy controls who were gender and age matched was determined using standard polymerase chain reaction. PAI-1 genotype results were studied in relationship to the development and severity of lupus nephritis.

RESULTS

Allele frequencies of 4G/5G allele were 0.59/0.41 in lupus patients and 0.59/0.41 in controls (P = 1.000). No significant difference was noted in the genotype distribution between SLE patients with and without nephritis. However, lupus nephritis patients with the 4G4G genotype showed significantly heavier proteinuria (5.0 vs. 3.7 g/day; P = 0.023) when compared with patients with 4G5G and 5G5G genotypes. Also, 73.3% patients with 4G4G had an activity index > or =8 versus 37.3% patients with 4G5G and 5G5G (P = 0.003). Extensive necrotizing lesions were seen in 51.7% patients with 4G4G as compared with 23.5% patients with 4G5G and 5G5G (P = 0.014). The association of the 4G4G gene polymorphism with a higher nephritis activity and more severe necrotizing lesions persisted when only class III and class IV nephritis patients were studied. On the other hand, no significant association was noted between the PAI-1 gene polymorphism and the chronicity of the nephritis.

CONCLUSION

These findings suggest that the 4G/5G polymorphism of the PAI-1 gene is associated with the activity but not the chronicity of lupus nephritis. The presence of the 4G4G genotype does not increase the risk of developing SLE or lupus nephritis, but predicts the development of higher nephritis activity and more extensive necrotizing lesions.

Vertebrate serpins: construction of a conflict-free phylogeny by combining exon-intron and diagnostic site analyses

A combination of three independent biological features, genomic organization, diagnostic amino acid sites, and rare indels, was used to elucidate the phylogeny of the vertebrate serpin (serine protease inhibitor) superfamily. A strong correlation between serpin gene families displaying (1) a conserved exon-intron pattern and (2) family-specific combinations of amino acid residues at specific sites suggests that present-day vertebrates encompass six serpin gene families which evolved from primordial genes by massive intron insertion before or during early vertebrate radiation. Introns placed at homologous positions in the gene sequences in combination with diagnostic sequence characters may also constitute a reliable kinship indicator for other protein superfamilies.

A truncated plasminogen activator inhibitor-1 protein induces and inhibits angiostatin (kringles 1-3), a plasminogen cleavage product

Plasminogen activator inhibitor-1 (PAI-1) is a serpin protease inhibitor that binds plasminogen activators (uPA and tPA) at a reactive center loop located at the carboxyl-terminal amino acid residues 320-351. The loop is stretched across the top of the active PAI-1 protein maintaining the molecule in a rigid conformation. In the latent PAI-1 conformation, the reactive center loop is inserted into one of the beta sheets, thus making the reactive center loop unavailable for interaction with the plasminogen activators. We truncated porcine PAI-1 at the amino and carboxyl termini to eliminate the reactive center loop, part of a heparin binding site, and a vitronectin binding site. The region we maintained corresponds to amino acids 80-265 of mature human PAI-1 containing binding sites for vitronectin, heparin (partial), uPA, tPA, fibrin, thrombin, and the helix F region. The interaction of "inactive" PAI-1, rPAI-1(23), with plasminogen and uPA induces the formation of a proteolytic protein with angiostatin properties. Increasing amounts of rPAI-1(23) inhibit the proteolytic angiostatin fragment. Endothelial cells exposed to exogenous rPAI-1(23) exhibit reduced proliferation, reduced tube formation, and 47% apoptotic cells within 48 h. Transfected endothelial cells secreting rPAI-1(23) have a 30% reduction in proliferation, vastly reduced tube formation, and a 50% reduction in cell migration in the presence of VEGF. These two studies show that rPAI-1(23) interactions with uPA and plasminogen can inhibit plasmin by two mechanisms. In one mechanism, rPAI-1(23) cleaves plasmin to form a proteolytic angiostatin-like protein. In a second mechanism, rPAI-1(23) can bind uPA and/or plasminogen to reduce the number of uPA and plasminogen interactions, hence reducing the amount of plasmin that is produced.

Stimulation of plasminogen activator and inhibitor in the lymphatic endothelium

Chromogenic assays, immunoblotting, and Northern blot hybridization methods were employed to assess the effects of various agonists on the production of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) by the lymphatic endothelium (LEC). Fibrin autography showed that plasminogen-dependent fibrinolytic activity occurred at M(r) of 110 kDa, which represents a complex of tPA with PAI-1, and 65- and 55-kDa bands corresponding to tPA and uPA, respectively. The fractionation of lymph collected from ovine lymphatic vessels also produced a prominent lytic band of approximately 110 kDa, suggesting the formation of PA/PAI complexes in lymph. The stimulation of various agonists produced large-scale increases in tPA mRNA, as shown by Northern blot hybridization analyses. The effects of ECGF, histamine, and LPS on the presence of tPA and on enhancing the levels of mRNA reached maximum activity at 4 h and declined to levels below that of controls by 8 h. However, phorbol-treated cells exhibited reduced levels of tPA mRNA at 4 h, but was significantly increased by 8 h. A large-scale increase in PAI-1 mRNA steady-state levels was also stimulated by the agonists used in these studies. Both the 3.4- and 2.4-kb species of PAI-1 mRNA were increased. These observations demonstrated that tPA and PAI-1 are produced and secreted by LEC monolayer cultures and are also present in lymph.

Identification of the Hind III polymorphic site in the PAI-1 gene: analysis of the PAI-1 Hind III polymorphism by PCR

The identification of the Hind III polymorphic site in the 3' end of the plasminogen activator inhibitor 1 (PAI-1) gene and a simple method to identify the Hind III polymorphism rapidly in the PAI-1 gene using PCR is described. The Hind III restriction site was identified by restriction site mapping and sequence analysis from a cosmid DNA clone. Genomic DNA was isolated from individual human umbilical cords and a 754-bp fragment of the human PAI-1 gene was amplified by PCR. Aliquots of the PCR products were digested with Hind III and analyzed by agarose gel electrophoresis. The presence of two fragments, 754 and 567 bp, was identified, and they were designated as 1/1 (750-bp band), 1/2 (754- and 567-bp bands), and 2/2 (567-bp band). The PCR method is considerably less time consuming than the conventional DNA genotyping using Southern blot analysis. To ensure that this new method identified the same PAI-1 genotypes as previously identified by Hind III restriction fragment length polymorphism (RFLP), samples were simultaneously genotyped by PCR and Southern blot analysis. Both methods identified the same Hind III genotypes in all the samples, confirming the reliability of this new PCR method for the rapid identification of the Hind III polymorphism in the human PAI-1 gene.

Adriana and Luisa Castellucci award lecture 1999: role of oxygen in the regulation of trophoblast gene expression and invasion

Changes in oxygen levels characterize normal and pathological human placentation. For example, relatively low Po(2)values are present around the blastocyst during implantation and in the placenta of the first trimester of pregnancy, a time of maximal trophoblast invasion. Our studies have revealed that low oxygen levels stimulate the in vitro invasiveness of cultured first trimester trophoblasts. This increased invasive ability is linked to elevated expression of some components of the plasminogen activator system and requires the participation of a putative haem protein. As gestation proceeds beyond the first trimester, and the extent of trophoblast invasion decreases, placental oxygen levels rise with a corresponding increase in blood flow. However, during certain pathological conditions, such as pre-eclampsia/intrauterine growth restriction, impaired remodelling of the uterine spiral arterioles leads to vessels with reduced diameters and localized regions of placental ischaemia/hypoxia. Placental hypoxia in the second half of gestation, as a consequence of reduced uteroplacental blood flow, may result in aberrant expression of genes that contribute to the pathophysiology of pre-eclampsia. Some of these genes encode certain cytokines and vasoactive molecules. We have also identified other genes whose expression is regulated by oxygen. Expression of one of them is induced in trophoblast and other cell types cultured under low oxygen levels and the product of the gene is a 43-kDa protein which we have termed PROXY-1. Compared to placental tissues and membranes isolated from uncomplicated pregnancies, PROXY-1 expression is elevated in tissues from pre-eclamptic pregnancies such as chorionic villi of peri-infarct regions, basal plate and membrane decidua, as well as chorion. Overall, these observations suggest that oxygen levels play an important role in placentation and in the pathophysiology of certain complications of pregnancy.

Relationship between plasma plasminogen activator inhibitor 1 and insulin resistance

High plasminogen activator inhibitor 1 (PAI-1) levels are associated with an increased cardiovascular risk of atherothrombosis. Furthermore, increased plasma PAI-1 levels are associated with dyslipidemia, hyperinsulinemia and hypertension. This association between PAI-1 and metabolic components of the Metabolic Syndrome could explain the predisposition of insulin resistant patients to atherothrombosis. Recent studies have suggested that visceral adipose tissue might be the link between elevated plasma PAI-1 and insulin resistance in the Metabolic Syndrome. Indeed, visceral adipose tissue was proposed as a potentially important source of PAI-1 in humans. However, in light of recent studies, visceral adipose tissue appears to be involved in the increase of plasma PAI-1 via the metabolic disorders usually associated with central obesity, rather than directly. High plasma PAI-1 levels are undoubtedly related to insulin resistance, and the mechanisms which could explain such an increase in the Metabolic Syndrome appear to be multi-factorial and remain to be elucidated. These mechanisms may involve several metabolic disorders such as hyperinsulinemia, dyslipidemia, impaired glucose tolerance and hypertension, which would favor PAI-1 synthesis and release from different cell types.

Hypoxia induces transcription of the plasminogen activator inhibitor-1 gene through genistein-sensitive tyrosine kinase pathways in vascular endothelial cells

A decline in oxygen concentration perturbs endothelial function, which promotes local thrombosis. In this study, we determined whether hypoxia in the range of that observed in pathophysiological hypoxic states stimulates plasminogen activator inhibitor-1 (PAI-1) production in bovine aortic endothelial cells. PAI-1 production, measured by ELISA, was increased by 4.7-fold (P<0.05 versus normoxic control, n=4) at 12 hours after hypoxic stimulation. Northern blot analysis showed the progressive time-dependent increase in the steady-state level of PAI-1 mRNA expression by hypoxia, which reached a 7.5-fold increase (P<0.05 versus control, n=4) at 12 hours. Deferoxamine, which has been known to bind heme protein and to reproduce the hypoxic response, induced PAI-1 production at both the mRNA and protein levels. The half-life of PAI-1 mRNA, as determined by a standard decay assay, was not affected by hypoxia, suggesting that induction of PAI-1 mRNA was regulated mainly at the transcriptional level. Transient transfection assays of the human PAI-1 promoter-luciferase construct indicates that a hypoxia-responsive region lies between -414 and -107 relative to the transcription start site, where no putative hypoxia response element is found. The hypoxia-mediated increase in PAI-1 mRNA levels was attenuated by the tyrosine kinase inhibitors genistein (50 micromol/L) and herbimycin A (1 micromol/L), whereas PD98059 (50 micromol/L, MEK1 inhibitor), SB203580 (10 micromol/L, p38 mitogen-activated protein kinase inhibitor), and calphostin C (1 micromol/L, protein kinase C inhibitor) had no effect on the induction of PAI-1 expression by hypoxia and deferoxamine. Genistein but not daidzein blocked the production of hypoxia- and deferoxamine-induced PAI-1 protein. Thus, we conclude that hypoxia stimulates PAI-1 gene transcription and protein production through a signaling pathway involving genistein-sensitive tyrosine kinases in vascular endothelial cells.

Ethanol downregulates transcription of the PAI-1 gene in cultured human endothelial cells

Human endothelial cells are a major site of synthesis for plasminogen activator inhibitor type-1. Elevated plasminogen activator inhibitor type-1 levels in young survivors of myocardial infarction [1] suggest that plasminogen activator inhibitor type-1 may have an important pathologic role in the development of coronary artery disease. Epidemiological studies indicate that moderate alcohol consumption (1-2 drinks/day) reduces the risk for cardiovascular mortality. This cardioprotective benefit has been attributed in part to an increase in fibrinolysis, which decreases fibrin-based thrombosis. The studies described herein were performed to determine whether moderate levels of ethanol affect plasminogen activator inhibitor type-1 gene expression. Cultured human endothelial cells were exposed to 0.1% v/v ethanol for 1 hour. Following incubation in the absence of ethanol plasminogen activator inhibitor type-1, mRNA levels were decreased in a time- and dose-dependent manner, reaching a maximum decrease of 3- to 4-fold at 2 to 4 hours following ethanol challenge. This decline in mRNA occurs at the transcription level; therefore, nuclear transcription run-on assays were performed. A 2.5- to 5-fold decrease in the rate of plasminogen activator inhibitor type-1 gene transcription was measured at 2 and 4 hours following ethanol challenge. Next, a 3.4- and a 1.1-kb fragment from the plasminogen activator inhibitor type-1 promoter region were linked to a luciferase reporter gene, and these constructs were transfected into human endothelial cells. Treatment of these transiently transfected human endothelial cells with ethanol showed a 2- to 3.5-fold decrease in promoter activity, respectively. These results indicate that low doses of ethanol downregulate transcription of the plasminogen activator inhibitor type-1 gene in cultured human endothelial cells. However, the mechanism(s) for this transcriptional decrease is currently unknown.

Plasminogen Activator Inhibitor 1: Molecular Aspects and Clinical Importance

Plasminogen activator inhibitor-1 (PAI-1) is the major physiologic inhibitor of plasminogen activation in plasma and in the blood vessel wall. PAI-1 exhibits distinctive structural and functional properties that have been extensively studied over the past decade. Aside from the physiological role of PAI-1, there is accumulating evidence that increased production of PAI-1 may contribute to the development of ischemic cardiovascular disease. Efforts are now underway to develop and test specific inhibitors of PAI-1.

Genetic determinants of arterial thrombosis

This chapter describes examples of genetic variation involved in the function or regulation of a number of haemostatic proteins involved in the thrombotic process. In each case, the data suggest associations between genotype and disease and, particularly in the case of fibrinogen, PAI-1, Factor VII and Factor XIII, there is interaction between genotype and environment in determination of the relevant plasma level, providing a possible explanation for the differential response of individuals to their environment.

Thiazolidinediones down-regulate plasminogen activator inhibitor type 1 expression in human vascular endothelial cells: A possible role for PPARgamma in endothelial function

The effect of peroxisome proliferator-activated receptor (PPAR) gamma activators, thiazolidinediones, on plasminogen activator type 1 (PAI-1) was examined in cultured human umbilical vein endothelial cells (HUVEC). Tumor necrosis factor alpha (TNF-alpha) enhanced PAI-1 secretion and mRNA expression by approximately 2-fold. The thiazolidinediones, troglitazone and pioglitazone, decreased basal and TNF-alpha-stimulated PAI-1 secretion and mRNA expression in HUVEC in a dose-dependent fashion. PPARgamma mRNA in HUVEC could be detected by reverse transcriptase-polymerase chain reaction using specific primers. These results suggest that PPARgamma may regulate PAI-1 expression in HUVEC and that thiazolidinediones have a therapeutic potential for improving endothelial dysfunction observed in insulin resistance.

Evidence that heparin but not hirudin reduces PAI-1 expression in cultured human endothelial cells

Heparin and other antithrombotic drugs besides their anticoagulant action could have a profibrinolytic effect. We have analyzed the effect of unfractionated heparin (UFH) and hirudin on PAI-1 gene expression in human umbilical vein endothelial cells (HUVEC). Cells were stimulated with UFH (1 and 10 IU/ml) and hirudin (20 and 100 TIU/ml). Samples were obtained before and 2, 6, and 24 hours after stimulation. mRNA analysis was conducted by reverse transcription followed by polymerase chain reaction, and PAI-1 antigen was determined by ELISA. Addition of UFH (10 IU/ml) to HUVEC resulted in a decrease of PAI-1 mRNA at 6 hours (40% reduction) and 24 hours (60% reduction) and PAI-1 antigen. Hirudin, however, did not modify significantly the PAI-1 mRNA nor the inhibitor secretion. The addition of UFH (10 or 100 IU/ml) to endotoxin-stimulated HUVEC also reduced the increased PAI-1 mRNA and antigen secretion (45%), whereas no effect could be observed with hirudin. Our results suggest that UFH, but not hirudin, by reducing the endothelial expression of PAI-1 might have a profibrinolytic effect.

Stimulation of plasminogen activator inhibitor-1 expression in immortalized human trophoblast cells cultured under low levels of oxygen

Low levels of oxygen characterize certain biological settings such as the first trimester human placenta and rapidly growing tumors. Hypoxia in tumors and expression of high levels of tumor-associated plasminogen activator inhibitor-1 (PAI-1) indicate a poor prognosis for some cancer patients. Furthermore, PAI-1 may promote tumor invasion and metastasis by modulating cell adhesion and detachment from the extracellular matrix. In this study, we used immortalized human trophoblasts (HTR-8/SVneo cells) derived from first trimester placenta to study the effect of exposure to low levels of oxygen on PAI-1 expression. Cell viability following 24-h exposure to 1% oxygen was similar to that of cells cultured under 20% oxygen. Exposure to hypoxia resulted in time-dependent increases in PAI-1 mRNA and protein levels, as determined by Northern blot analysis and enzyme-linked immunosorbent assay. Culture with cobalt chloride or Tiron also resulted in increased PAI-1 mRNA levels, while carbon monoxide inhibited the hypoxia-mediated increase, thereby indicating that a heme protein is involved in the stimulation of PAI-1 expression by hypoxia. Incubation with transforming growth factor-beta1 (TGF-beta1) also resulted in increased levels of PAI-1 mRNA. However, addition of a neutralizing anti-TGF-beta antibody to hypoxic cultures did not abrogate the increase in PAI-1 mRNA levels, suggesting that hypoxia stimulates PAI-1 expression via a pathway that does not require TGF-beta production. These results indicate that, through their effect on PAI-1 expression, oxygen levels may play an important role in modulating cellular migration and invasion.

Genotype-specific transcriptional regulation of PAI-1 gene by insulin, hypertriglyceridemic VLDL, and Lp(a) in transfected, cultured human endothelial cells

Plasminogen activator inhibitor-1 (PAI-1) has been shown to be an independent risk factor for coronary artery disease. Variations in plasma PAI-1 levels have been attributed to variations in the PAI-1 gene, and associations between PAI-1 levels and PAI-1 genotypes suggest that PAI-1 expression may be regulated in a genotype-specific manner by insulin, hypertriglyceridemic (HTG) very low density lipoprotein (VLDL), or lipoprotein(a) [Lp(a)]. Polymerase chain reaction-amplified 1106-bp fragments of the promoter of the 1/1 and 2/2 PAI-1 genotypes were sequenced and showed 5 regions of small nucleotide differences in the 1/1 versus 2/2 PAI-1 promoters that consistently occurred with high frequency. These fragments were ligated into the luciferase reporter gene, and 1/1 and 2/2 PAI-1 genotype human umbilical vein endothelial cell (HUVEC) cultures were transiently transfected with their respective p1PAI110/luc and p2PAI110/luc constructs and vice versa. Insulin induced an approximately 12- to 16-fold increase in luciferase activity in both the 1/1 and 2/2 PAI-1 genotype HUVEC cultures transfected with the p1PAI110/luc construct. HTG-VLDL and Lp(a) induced luciferase activity by approximately 14- to 16- and approximately 8- to 11-fold, respectively, in both the 1/1 and 2/2 PAI-1 genotype HUVEC cultures transfected with the p2PAI110/luc construct. The positive control interleukin-1 showed an approximately 7- to 12-fold response in the 1/1 and 2/2 PAI-1 genotype HUVEC cultures transfected with either of the constructs. These cross-over results demonstrate that regulation of either the 1/1 or 2/2 PAI-1 genotype by its respective inducer is due to the promoter itself and not to some factor(s) expressed differently in the 1/1 or 2/2 PAI-1 genotype HUVEC cultures.

Stereodependent inhibition of plasminogen activator inhibitor type 1 by phosphorothioate oligonucleotides: proof of sequence specificity in cell culture and in vivo rat experiments

Hexadecadeoxyribonucleotides complementary to a fragment of human PAI-1 mRNA located upstream of the start codon and their phosphorothioate analogs were studied in cultured HUVECs as sequence-dependent inhibitors of PAI-1 expression. The activity of the random mixture of diastereomers of phosphorothioate hexadecanucleotide PS-16H has been compared with that of isosequential, stereoregular [All-Sp] and [All-Rp] isomers. The highest inhibitory effect on PAI-1 synthesis was observed with the [All-Sp] diastereomer. Stereorandom phosphorothioate oligonucleotide PS-16R complementary to the same region of rat PAI-1 mRNA, when injected into tail vein of rats, substantially decreased the level of PAI-1 in blood plasma.

Modulation of plasminogen activator inhibitor type-1 biosynthesis in vitro and in vivo with oligo(nucleoside phosphorothioate)s and related constructs

Oligonucleotides with a nucleotide sequence complementary to various regions of human plasminogen activator inhibitor type-1 (PAI-1) mRNA have been studied as antisense inhibitors of expression of PAI-1 protein in cultured cells [human umbilical vein endothelial cells (HUVEC), human aortic smooth muscle cells, human hybrid endothelial cells]. Hexadeca(deoxyribonucleoside phosphorothioate) 13 complementary to a fragment of a signal peptide PAI-1 mRNA was found to be most active, giving ca. 70% inhibition of PAI-1 release in a time- and dose-dependent way. The stereo-regular All-S(P) and All-R(P) diastereomers of 13 were studied and found to inhibit PAI-1 synthesis in HUVEC in a stereo-dependent manner, with the All-S(P) diastereomer considerably more active than the stereo-random construct and All-R(P) isomer. The observed stereo-dependent activity of oligonucleotide phosphorothioate constructs is presumably governed by their resistance to nucleases. The corresponding phosphodiester analogue of 13 was not active unless covalently bound at its 5'-end to a lipophilic alcohol residue (menthol, heptadecanol). The observed antisense activity of phosphodiester oligonucleotide bioconjugates in cultured human hybrid endothelial cells was paralleled by their increased stability in human plasma with respect to unconjugated oligonucleotide. The oligo(deoxyribonucleoside phosphorothioate) complementary to the same signal peptide region of rat PAI-1 mRNA was found to reduce the PAI-1 level in blood plasma of rats after intravenous administration into the tail vein. The effect was both time- and dose-dependent. The same oligonucleotide was found to protect against arterial thrombus formation in the rat (lower incidence of venous thrombosis, lower thrombus weight, and increased occlusion time in experimentally induced thrombosis). An anti-PAI-1 inhibitory activity has been independently reported for a 20-mer oligo(2'-O-methyl-ribonucleoside phosphorothioate) complementary to a 3'-untranslated region of human PAI-1 mRNA in cultured HUVEC and human aortic smooth muscle cells.

Mutational analysis of the genes encoding urokinase-type plasminogen activator (uPA) and its inhibitor PAI-1 in advanced ovarian cancer

Evidence has accumulated that urokinase-type plasminogen activator (uPA), its inhibitor (PAI-1) and receptor (uPAR) are involved in tumor invasion and metastasis. We analyzed the DNA sequences encoding these factors to see if they are altered in the ovarian cancer cell lines OV-MZ-6, OV-MZ-19, and OVCAR-3. In the uPA-encoding cDNA derived from OV-MZ-6 cells (but not in the uPA-cDNA from OVCAR-3 and OV-MZ-19), a so-far unknown mutation was identified in codon 121, resulting in a proline to leucine exchange. This exchange creates an AluI restriction site making restriction fragment length polymorphism (RFLP) analyses possible. Previously published PAI-1 sequences pointed to a variation of amino acid 15 of the PAI-1 signal sequence representing either threonine or alanine, which was confirmed in the present study. The uPAR cDNAs of all three cell lines encoded the published wild-type sequence. In order to elucidate the possible role of the Pro121Leu exchange in uPA and the Ala/Thr variants in the signal sequence of PAI-1 in the development and/or progression of human ovarian cancer, we studied the presence of these mutants or variants in a series of 22 ovarian cancer tissues. In addition to the wild-type sequence, the Pro121Leu exchange in the uPA sequence was detected in 10 out of 22 tumor tissues; 11 tumors carried exclusively the Pro121 allele; in one case exclusively the Leu121 allele was detected. In 18/22 tumors, triplet 15 in the signal sequence of PAI-1 encoded alanine, four DNAs contained both the Ala and the Thr allele. Furthermore, we analyzed another known common single-base-pair insertion/deletion polymorphism (ins/del allele) found in the promoter region of the PAI-1 gene and thought to be of functional importance in regulating PAI-1 gene expression. The PAI-1 ins-allele was found in 3/22, the del-allele in 6/22 and both alleles in 13/22 ovarian cancer tissues. In genomic DNA isolated from peripheral blood of 23 healthy donors, we observed similar allele frequencies of the three polymorphisms as found in the 22 ovarian carcinomas. Taken together, these results suggest that the polymorphisms observed in the uPA and PAI-1 genes may not be linked to ovarian cancer.

Five frequent polymorphisms of the PAI-1 gene: lack of association between genotypes, PAI activity, and triglyceride levels in a healthy population

The main function of plasminogen activator inhibitor type 1 (PAI-1) is to decrease fibrinolysis, which leads to fibrin accumulation. An elevated plasma PAI-1 concentration has been identified as a risk factor for the development of myocardial infarction, and an association between 1 polymorphism of the PAI-1 promoter and plasma PAI-1 levels has been described. Our aim was to identify new polymorphisms in the PAI-1 gene and to further examine the relationship between PAI-1 genotypes and circulating PAI-1 levels. We report the presence of 4 new polymorphisms that were identified by non-isotopic single-strand conformational polymorphism analysis followed by sequencing. These polymorphisms were investigated in relation to PAI-1 levels in a sample of 256 healthy men, aged 50-59 years, from France and Northern Ireland. Two G/A substitutions were detected at positions -844 and +9785. The former is in strong positive linkage disequilibrium with the previously described 4G/5G polymorphism at position -675. Two polymorphisms in the 3' untranslated region were identified. One corresponds to a T/G substitution at position +11,053 and is in negative linkage disequilibrium with the G/A substitution (+9785). The other is a 9-nucleotide insertion/deletion located between nucleotides +11,320 and +11,345 in a threefold-repeated sequence. This polymorphism is in strong positive linkage disequilibrium with the G/A substitution (+9785). The overall heterozygosity provided by the 5 PAI-1 polymorphisms (including the 4 new variants and the 4G/5G polymorphism) was .77. No significant association was found between PAI activity and genotypes; furthermore, the well known associations between PAI activity and body mass index, serum triglycerides, or insulin were homogeneous according to PAI-1 genotypes.

A novel G/A and the 4G/5G polymorphism within the promoter of the plasminogen activator inhibitor-1 gene in patients with deep vein thrombosis

Plasma plasminogen activator inhibitor-1 (PAI-1) level was observed to be associated with sequence variations at the PAI-1 locus. Therefore, PAI-1 gene promoter was screened for possibly new polymorphisms and to investigate the contribution of these sequence variations to PAI-1 levels in patients with deep vein thrombosis (DVT). DNA was isolated from blood of 83 consecutive unrelated patients (42 +/- 11 years old) and from 50 apparently healthy subjects of similar age and gender distribution. Six fragments covering DNA sequence- 1523 base pairs (bp) upstream from the start of PAI-1 gene transcription to +90 bp in the first exon, were amplified by polymerase chain reaction and analyzed by single-strand conformation polymorphisms. Two polymorphisms were found: a previously described 4G/5G deletion/insertion polymorphism -675bp upstream from the start of transcription and a novel G/A single base substitution polymorphism further upstream at -844 bp. The two polymorphisms were in strong linkage disequilibrium. Significant differences between patients and controls were observed neither for the frequencies of the 4G/5G alleles (0.60/0.40 and 0.59/0.41, respectively) nor for the frequencies of the G/A alleles (0.33/0.67 and 0.41/0.59, respectively). The distribution of both polymorphisms was similar in idiopathic and secondary DVT as well as in first and recurrent DVT. In patients association between the 4G/5G genotypes and PAI activity was observed, with the highest values in the 4G/4G genotype (13.3 U/mL), median values in the 4G/5G genotype (9.8 U/mL) and the lowest values in the 5G/5G genotype (2.0 U/mL). Despite the lack of association between the G/A genotypes and plasma PAI-1 levels, electrophoretic mobility shift assay showed specific binding of a nuclear protein from human vascular endothelial cells extracts to both the G and the A variant, suggesting functional importance of this novel G/A polymorphism in regulating the expression of PAI-1 gene.