The Multifaceted Role of Plasminogen in Cancer

Fibrinolytic factors like plasminogen, tissue-type plasminogen activator (tPA), and urokinase plasminogen activator (uPA) dissolve clots. Though mere extracellular-matrix-degrading enzymes, fibrinolytic factors interfere with many processes during primary cancer growth and metastasis. Their many receptors give them access to cellular functions that tumor cells have widely exploited to promote tumor cell survival, growth, and metastatic abilities. They give cancer cells tools to ensure their own survival by interfering with the signaling pathways involved in senescence, anoikis, and autophagy. They can also directly promote primary tumor growth and metastasis, and endow tumor cells with mechanisms to evade myelosuppression, thus acquiring drug resistance. In this review, recent studies on the role fibrinolytic factors play in metastasis and controlling cell-death-associated processes are presented, along with studies that describe how cancer cells have exploited plasminogen receptors to escape myelosuppression.

Molecular organization of the rat glia-derived nexin/protease nexin-1 promoter

The first three exons and the promoter of rat glia-derived nexin, also called protease nexin-1 (GDN/PN-1), have been identified through analysis of rat genomic clones. A 1.6 kilobase (kb) fragment containing 105 base pairs of the first exon and 5'-flanking sequences was sequenced. The 5'-flanking sequence and the first exon were found to be GC-rich, indicating that the 5' region of the rat GDN/PN-1 gene resides within a CpG island. A TATA box-like sequence, but no CAAT box, was found. The rat GDN/PN-1 promoter contains five SP1 consensus sites, four consensus sites for the MyoD1 transcription factor, and one binding site for the transcription factors NGFI-A, NGFI-C, Krox-20, and Wilms tumor factor. The presence of these consensus sequences is consistent with the known expression pattern of GDN/PN-1. Primer extension and RNase protection assays identified one transcriptional start site. The 1.6 kb promoter fragment cloned in a reporter plasmid was found to induce firefly luciferase expression in a cell-specific manner. A positive regulatory element is localized in the region -1545 to -389. In vitro CpG methylation blocked transcription from the GDN/PN-1 promoter in rat hepatoma cells but not in C6 rat glioma cells.

Prevention of experimental postoperative peritoneal adhesions through the intraperitoneal administration of tanshinone IIA

Postoperative adhesions develop after nearly every abdominal surgery. The formation of adhesions is associated with the inflammatory response, fibrinolytic system, and extracellular matrix deposition in response to injury. Tanshinone IIA is one of the major extracts obtained from Salvia miltiorrhiza, which has anti-inflammatory effects on many diseases. Postoperative adhesions were induced by injuring the parietal peritoneum and cecum in Wistar rats, followed by the administration of various dosages of tanshinone IIA. The adhesion scores for each group were collected seven days after the initial laparotomy. The activity of the tissue-type plasminogen activator in the peritoneal lavage fluid was measured. The messenger ribonucleic acid expression levels of the tissue-type plasminogen activator, plasminogen activator inhibitor-1, and cyclooxygenase-2 in the ischaemic tissues were measured by quantitative real-time polymerase chain reaction. The intraperitoneal administration of tanshinone IIA is effective for the prevention of the formation of postoperative adhesions in rats. Tanshinone IIA increased fibrinolytic activity in the peritoneal lavage fluid and tissue-type plasminogen activator messenger ribonucleic acid expression in ischaemic peritoneal tissues but decreased the plasminogen activator inhibitor and cyclooxygenase-2 messenger ribonucleic acid expression significantly. These results revealed that tanshinone IIA was a potent postoperative adhesion preventer by enhancing fibrinolytic activity and decreasing cyclooxygenase-2 activity.

Impact of uPA system gene polymorphisms on the susceptibility of environmental factors to carcinogenesis and the development of clinicopathology of oral cancer

BACKGROUND

The levels of urokinase plasminogen activator (uPA) system in tumor tissues are implicated as prognostic biomarkers in a wide range of malignancies. However, their possible impact on the risk and prognosis of oral cancer and the susceptibility of environmental carcinogens to oral cancer remains poorly investigated.

METHODS

The genetic polymorphisms of uPA, uPA receptor (uPAR), and plasminogen activator inhibitor (PAI)-1 were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 253 patients with oral cancer and 344 healthy controls.

RESULTS

There was no significant effect of uPA system genes on the susceptibility of oral cancer; however, the impact of uPA system gene polymorphisms on the susceptibility of betel nut and tobacco consumptions to oral cancer was revealed, except for that of uPAR gene polymorphism on tobacco consumption. Patients with oral cancer with at least one 5G allele of PAI-1 gene have a low risk for the development of clinical stage III or IV (p ≤ 0.05) and lymph node metastasis (p ≤ 0.05) compared with those with 4G/4G homozygotes.

CONCLUSIONS

Our results suggest that the combination of uPA system gene polymorphisms and environmental carcinogens was related to the risk of oral cancer, and the genetic polymorphism of PAI-1 was associated with a low risk to the clinicopathological development of oral cancer.

Spatiotemporal expression of the serine protease inhibitor, SERPINE2, in the mouse placenta and uterus during the estrous cycle, pregnancy, and lactation

BACKGROUND

SERPINE2, also known as glia-derived nexin or protease nexin-1, belongs to the serine protease inhibitor (SERPIN) superfamily. It is one of the potent serpins that modulates the activity of the plasminogen activator (PA) and was implicated in tissue remodeling. In this study, we investigated the expression patterns of SERPINE2 in the mouse placenta and uterus during the estrous cycle, pregnancy, and lactation.

METHODS

SERPINE2 was purified from mouse seminal vesicle secretion using liquid chromatography (LC) and identified by LC/tandem mass spectrometry. The antiserum against the SERPINE2 protein was raised in rabbits. To reveal the uterine and placental expression of SERPINE2, tissues at various stages were collected for real-time PCR quantification, Western blotting, and immunohistochemical staining.

RESULTS

Serpine2 mRNA was the major PA inhibitor in the placenta and uterus during the estrous cycle, pregnancy, and lactation, although Serpine1 mRNA had higher expression levels than Serpine2 mRNA in the placenta. Plat seemed to be the major PA in the mouse uterus and placenta. Antiserum against the SERPINE2 protein specifically recognized two forms of SERPINE2 and an extra 75-kDa protein, which was probably a complex of SERPINE2 with a certain protease, from among thousands of protein components in the tissue extract as demonstrated by Western blotting. In the uterus, SERPINE2 was primarily localized in luminal and glandular epithelial cells but it also was detected in circular and longitudinal smooth muscle cells during the estrous cycle and lactation. It was prominently expressed in decidual stroma cells, the metrial gland, and endometrial epithelium of the pregnant uterus. In the placenta, SERPINE2 was expressed in trophoblasts of the labyrinth and spongiotrophoblasts. However, its expression was remarkably reduced in giant cells which existed in the giant cell-decidual junction zone. In contrast, prominent expression of SERPINE2 seemed to be detected on clusters of glycogen cells near the junction zone. In addition, yolk sac membranes also showed high expression of SERPINE2.

CONCLUSIONS

These findings indicate that SERPINE2 is a major PA inhibitor in the placenta and uterus during the estrous cycle, pregnancy, and lactation. It may participate in the PA-modulated tissue remodeling process in the mouse placenta and uterus.

Impact of genetic variation on perioperative bleeding

Variation in bleeding in the perioperative period is a complex and multifactorial event associated with immediate and delayed consequences for the patient and health care resources. Little is known about the complex genetic influences on perioperative bleeding. With the discovery of multiple variations in the human genome and ever-growing databases of well-phenotyped surgical patients, better identification of patients at risk of bleeding is becoming a reality. In this review, polymorphisms in the platelet receptor genes, plasminogen activator inhibitor, and angiotensin genes among others will be discussed. We will explore the nature, effects, and implications of the genetics that influence perioperative bleeding above and beyond surgical bleeding, particularly in cardiac surgery.

Decreased Plasminogen Activator Inhibitor and Tissue Metalloproteinase Inhibitor Expression May Promote Increased Metalloproteinase Activity with Increasing Duration of Human Atrial Fibrillation

INTRODUCTION

Atrial fibrosis has been shown to concur with the persistence of atrial fibrillation (AF) and is only incompletely reversible, thus counteracting attempts to restore and maintain sinus rhythm (SR). Besides the angiotensin system, the matrix metalloproteinases (MMP) play a major role in the pathogenesis of fibrosis. Thus, the present study investigated changes of the MMP system during the development of human AF.

METHODS AND RESULTS

Right atrial appendages of 146 patients were excised during heart surgery and grouped according to rhythm (SR vs AF) and AF duration. Hydroxyproline as a surrogate for collagen content and morphometrically determined collagen content increased significantly from SR (14.3 +/- 7.7%) to chronic permanent AF (CAF) of 6-24 months (21.2 +/- 9.2%, P = 0.02), and CAF of > 60 months (25.3 +/- 4.7%, P < 0.01). From SR to paroxysmal and chronic persistent AF (CPAF) and to CAF MMP-2 and MMP-9 activity rose, while their mRNA and protein levels were not altered significantly. Plasminogen activator inhibitor (PAI), an inhibitor of a potent activator of many MMPs, was significantly decreased with increasing duration of AF. In parallel, the mRNA levels of the tissue inhibitors of MMPs TIMP-1 and -2 decreased significantly.

CONCLUSION

Human atrial fibrogenesis is enhanced with increasing duration of AF: a longer AF duration is associated with elevated atrial interstitial MMP activity, but decreased PAI and TIMP expression.

Regulation of plasminogen activators in human thyroid follicular cells and their relationship to differentiated function

Human thyroid cells in culture take up and organify (125)I when cultured in TSH (acting through cAMP) and insulin. They also secrete urokinase (uPA) and tissue-type (tPA) plasminogen activators (5-100 IU/10(6)cells/day). TSH and insulin both decreased secreted PA activity (PAA), uPA and tPA protein and their mRNAs. Autocrine fibroblast growth factor increased secreted PAA and inhibited thyroid cell (125)I uptake. Epidermal growth factor (EGF) and the protein kinase C (PKC) activator, TPA significantly increased PAA and inhibited thyroid differentiated function, (TPA > EGF). For TPA, effects were rapid, increased PAA secretion and decreased (125)I uptake being seen at 4 h whereas for EGF, a 24 h incubation was required. qRT-PCR showed significantly increased mRNA expression of uPA with lesser effects on tPA. Aprotinin, which inhibits PAA, increased (125)I uptake but did not abrogate the effects of TPA and EGF. The MEKK inhibitor, PD98059 partially reversed the effects of EGF and TPA on PAA, and largely reversed the effects of EGF but not TPA on differentiated function. PKC inhibitors bisindoylmaleimide 1, and the specific PKCbeta inhibitor, LY379196 completely reversed the effects of TPA on (125)I uptake and PAA whereas EGF effects were unaffected. TPA inhibited follicle formation and this effect was blocked by LY379196 but not PD98059. We conclude that in thyroid cells, MAPK activation inversely correlates with (125)I uptake and directly correlates with PA expression, in contrast to the effects of cAMP. TPA effects on iodide metabolism, dissolution of follicles and uPA synthesis are mediated predominantly through PKCbeta whereas EGF exerts its effects through MAPK but not PKCbeta.

Expression and localisation of extracellular matrix degrading proteases and their inhibitors during the oestrous cycle and after induced luteolysis in the bovine corpus luteum

The corpus luteum (CL) offers the opportunity to study high proliferative processes during its development and degradation processes during its regression. We examined the mRNA expression of matrix metalloproteases (MMP)-1, MMP-2, MMP-9, MMP-14, MMP-19, tissue inhibitor of MMP (TIMP)-1, TIMP-2, tissue plasminogen activator (tPA), urokinase plasminogen activator (uPA), uPA-receptor (uPAR), PA-inhibitors (PAI)-1, PAI-2 in follicles 20 h after GnRH application, CLs during days 1–2, 3–4, 5–7 and 8–12 of the oestrous cycle as well as after induced luteolysis. Cows in the mid-luteal phase were injected with Cloprostenol and the CLs were collected at 0.5, 2, 4, 12, 24, 48 and 64 h after PGF2α injection. Real-time RT-PCR determined mRNA expressions. Expression from 20 h after GnRH to day 12: MMP-1, MMP-2, MMP-14 and tPA showed a clear expression, but no regulation. TIMP-1 and uPAR mRNA increased when compared with the follicular phase. TIMP-2, MMP-9, MMP-19 and uPA increased from the follicular phase to days 8–12. PAI-1 and PAI-2 expression increased from days 1–7 and decreased to days 8–12. Induced luteolysis: MMP-1, MMP-2, MMP-9, MMP-14, MMP-19 and TIMP-1 all increased at different time points and intensities, whereas TIMP-2 was constantly decreased from 24 to 64 h. The plasminogen activator system and their inhibitors were up-regulated from 2 to 64 h, tPA was already increased after 0.5 h. Immunohistochemistry for MMP-1, MMP-2, MMP-14: an increased staining for MMP-1 and MMP-14 was seen in large luteal cells beginning 24 h after PGF2α application. MMP-2 showed a strong increase in staining in endothelial cells at 48 h.

Novel functions of intracellular IL-1ra in human dermal fibroblasts: implications in the pathogenesis of fibrosis

Intracellular IL-1 receptor antagonist (icIL-1ra) is reportedly involved in functions independent of blocking IL-1 receptor signaling. Fibroblasts derived from the involved skin of patients with systemic sclerosis (SSc) are predominantly of the myofibroblast phenotype, with higher levels of icIL-1ra compared to normal skin fibroblasts. We examined the effect of overexpression of icIL-1ra on the phenotype and function of normal fibroblasts with respect to the expression of alpha smooth muscle actin (alpha-SMA), a specific marker for myofibroblasts, and plasminogen activator inhibitor (PAI), a protein involved in fibrogenesis and expressed at higher levels in myofibroblasts, and the production of collagenase (matrix metalloproteinase-1 (MMP-1)), the major enzyme involved in the degradation of native collagen in the skin. Normal human foreskin fibroblasts overexpressing icIL-1ra showed higher levels of alpha-SMA and PAI and had lower levels of collagenase and MMP-1 mRNA induced by inflammatory cytokines. By contrast, levels of mRNA for tissue inhibitor of metalloproteinase-1 in the transfected cells were not different from the control cells. Pretreatment of the ic-IL-1ra-transfected cells with antisense oligonucleotide directed against the mRNA of icIL-1ra restored MMP-1 expression induced by stimulation with IL-1beta. Our data indicate novel functions for icIL-1ra, which might be relevant to the genesis of fibrotic diseases such as SSc.

Plasminogen activators and their inhibitor gene expression in cutaneous NF1-related neurofibromas

Cutaneous neurofibromatosis 1 (NF1)-related neurofibromas are benign tumors and composed of Schwann cells, perineurial cells and/or fibroblasts, endothelial cells, mast cells and macrophages. Extracellular proteolysis namely plasminogen activation (PA) operates in many tissue destructive processes. We wanted to study plasminogen activators, urokinase (uPA) and tissue type (tPA) and their inhibitor PAI-1, which have not earlier been studied comprehensively in cutaneous NF1-related tumors. We analyzed the distribution of uPA, tPA and PAI-1 antigen level by immunohistochemistry and mRNA level by in situ hybridization, to identify which cells are primarily involved in proteolytic activity and plasminogen activation. Twelve NF1 skin tumor samples from six patients were obtained during the operations. Mast cells, macrophages and endothelial cells were distributed only locally. Their expression levels of PA components were not so notable. Large extent of tumor cells of Schwann cell origin and prominent expression levels of uPA, tPA and PAI-1 indicated that these cells are responsible for the main source of PA components in cutaneous NF1-related neurofibromas.

Transcriptional and posttranscriptional regulation of the plasminogen activator system

The core protein components of the plasminogen activator (PA) system are two plasminogen activators, two plasminogen activator inhibitors and a urokinase type plasminogen activator-specific cell surface receptor. Various types of biological regulation are exerted through the interplay of these components mutually and with extracellular matrix proteins and cell membrane proteins, with or without involving proteolytic activity. Reflecting these diverse biological roles, the level and activity of each component of the PA system is under the control of a variety of regulatory mechanisms. The expression level of a protein reflects the level of the corresponding mRNA, which is essentially the net result of de novo synthesis, i.e. transcription, and degradation. Many recent studies have shown that the regulation of mRNA stability is dynamic and cell specific. Accordingly, we are learning that the mRNAs of the PA system are also the subject of diverse regulatory mechanisms. In this short review, we summarize current understanding of the transcriptional and mRNA-stability regulation of the PA system.

Activation of gelatinases by fibrin is PA/plasmin system-dependent in human glomerular endothelial cells

Evidence suggests that fibrin deposit is related to severity of glomerulonephropathy. Fibrin is considered to play an active role beyond a haemostatic plug or temporary matrix in response to injury. We have reported that fibrin induced specific morphological changes and up-regulated intercellular adhesion molecule-1 expression of glomerular endothelial cells (GECs). Changes of gelatinases activity have been implicated playing a prominent role in glomerular diseases involving matrix turnover. This study examined whether overlying fibrin influences the expression of gelatinase A and B in cultured human GECs and mechanism underlying the activation. No gelatinase activity was detectable in supernatant of cultured GECs; however, physiological concentration of fibrin (0.5-2.0 mg/ml) induced a dramatic expression of activated MMP-2 and MMP-9 at both mRNA and protein level in a dose and time dependent manner. Increased mRNA level of membrane-type 1 matrix metalloproteinases (MT1-MMPs) was also found. Interestingly, we observed that fibrin also induced the expression of tissue type plasminogen activator (tPA), urokinase type plasminogen activator (uPA) and plasminogen activator inhibitor-1 by casein zymographic and reverse zymographic analysis. Fibrin plate assay revealed the net activity was PA predominant. Serine protease inhibitor aprotinin blocked the conversion of pro-gelatinase A and B to their active forms. The results demonstrate that overlying fibrin increased the secretion of gelatinase A and B from GECs. PA/plasmin proteolytic pathways contributed to the activation of gelatinases.

Genetic risk factors in myocardial infarction at young age

The role of genetic susceptibility to coronary artery disease (CAD) seems to be quite important in young patients. In the last years the attention has been focused on polymorphisms influencing some biological functions (coagulation and fibrinolysis, platelets, vascular function, lipid metabolism, inflammation). The study of prothrombotic polymorphisms has kindled a deep interest. The role of atherosclerosis and thrombosis is different in the different ages. In all the studies we examined, the polymorphism G20210A in the prothrombin gene was associated with an increased risk of acute myocardial infarction (AMI) in young people, especially when other risk factors were present. Contradictory results have been found in the studies on Factor V Leiden: according to many authors the activated protein C resistance (APCR) is associated with an increased risk of AMI only in smokers, above all if women. On the other hand, some polymorphisms of the Factor VII gene seem to be protective. Young AMI could be also caused by a reduction of the fibrinolytic activity, as it was found when the allele 4G in the promoter of plasminogen activator inhibitor (PAI) gene is present. The attention has also been focused on the effects of variations in genes that influence platelet functions. According to a metanalysis of studies published up to 1999, there is no association between the polymorphism PlA1/A2 of the GP IIIa gene and young AMI, whereas there is doubt about the role of the polymorphism in the GP IIb e GP Ib genes. Moreover, it seems to be present an association with the polymorphisms in the thrombopoietin gene (C4830A and A5713G). Also the role of some genes coding for proteins influencing the vascular functions has been valued. Few studies were performed on genetics of the renin-angiotensin-aldosterone system and the results are insufficient and contradictory, such as those about the association between the polymorphism G894T in the eNOS gene or the polymorphism C677T in the MTHFR gene and young AMI. Genes coding for proteins involved in the lipid metabolism have been closely examined. Many polymorphisms were discovered in the Apo B gene: the variant C-516T was found to be associated with increased LDL levels, whereas the results about the association between this and other polymorphisms in the same gene (I/D of LAL sequence, PvuII, MspI, Asp4311Ser) and young AMI are discordant. On the other hand, the variant e4 of the ApoE gene was associated with an increased risk of AMI at young age in many works. In the last years, a particular interest has kindled the study of the relationship between inflammation, atherosclerosis and CAD. Even if the studies performed are few, it was found an association between young AMI and polymorphism C-260T in the CD14 gene, between coronarics atherosclerosis and polymorphism A516C in the E Selectin gene or polymorphisms Leu125Val and Ser563Asn in the PECAM1 gene.

[Remarks of the Zurich Discussion Panel on the gene test]

Leider besteht für diesen Artikel keine Zusammenfassung. Als Einstieg stellen wir den Textanfang zur Verfügung. Seit einiger Zeit wird ein Gentest angeboten, mit dem sich angeblich das individuelle Risiko für z.B. Herz-/Kreislauferkrankungen, Thrombosen, Osteoporose, Mammakarzinom oder Schwangerschaftskomplikationen durch die Analyse von 18 genetischen Parametern bzw. deren Polymorphismen erkennen lässt. Anhand der Ergebnisse dieses Tests soll es dann möglich sein, für jede Frau die optimale Hormonsubstitution festzulegen und die individuellen Krankheitsrisiken durch geeignete Massnahmen zu minimieren. Nach der Veröffentlichung einer kurzen Stellungnahme zu diesem Gentest im Addendum der jüngsten Empfehlungen des Zürcher Gesprächskreises zur Hormonsubstitution in ‘Frauenarzt’ 2/2002 gingen verschiedene Kommentare ein. Der Zürcher Gesprächskreis sieht sich deshalb veranlasst, zum Thema Polymorphismen eine ausführliche Stellungnahme abzugeben.

Collagen modulates gene activation of plasminogen activator system molecules

Skin extracellular matrix (ECM) molecules regulate a variety of cellular activities, including cell movement, which are central to wound healing and metastasis. Regulated cell movement is modulated by proteases and their associated molecules, including the serine proteases urinary-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) and their inhibitors (PAIs). As a result of wounding and loss of basement membrane structure, epidermal keratinocytes can become exposed to collagen. To test the hypothesis that during wounding, exposed collagen, the most abundant ECM molecule in the skin, regulates keratinocyte PA and PAI gene expression, we utilized an in vitro model in which activated keratinocytes were cultured in dishes coated with collagen or other ECM substrates. tPA, uPA, and PAI-1 mRNA and enzymatic activity were detected when activated keratinocytes attached to fibronectin, vitronectin, collagen IV, and RGD peptide. In contrast, adhesion to collagen I and collagen III completely suppressed expression of PAI-1 mRNA and protein and further increased tPA expression and activity. Similarly, keratinocyte adhesion to laminin-1 suppressed PAI-1 mRNA and protein expression and increased tPA activity. The suppressive effect of collagen I on PAI-1 gene induction was dependent on the maintenance of its native fibrillar structure. Thus, it would appear that collagen- and laminin-regulated gene expression of molecules associated with plasminogen activation provides an additional dimension in the regulation of cell movement and matrix remodeling in skin wound healing.

Gonadotrophin surge-induced upregulation of mRNA for plasminogen activator inhibitors 1 and 2 within bovine periovulatory follicular and luteal tissue

The serine proteinases, tissue-type (tPA) and urokinase (uPA) plasminogen activator, are implicated in the ovulatory processes via their ability to convert plasminogen to its active form, plasmin. One mechanism for regulation of plasmin-directed ovarian extracellular matrix remodelling during follicle rupture and corpus luteum formation is through inhibition of plasminogen activation by the plasminogen activator inhibitors (PAI-1 and PAI-2). The effect of the preovulatory gonadotrophin surge on the temporal and spatial regulation of expression of PAI-1 and PAI-2 mRNA and PAI activity in preovulatory bovine follicles and new corpora lutea collected at 0, 6, 12, 18, 24 and 48 h after a GnRH-induced gonadotrophin surge was examined. Both PAI-1 and PAI-2 mRNAs were upregulated markedly after the gonadotrophin surge, with the highest expression observed in follicles collected at about the time of ovulation (24 h) and in corpora lutea (48 h). PAI-1 mRNA was localized primarily to the thecal layer of preovulatory follicles. In contrast, PAI-2 mRNA was localized specifically to the granulosa cell layer. Significant PAI activity was detected in follicle extracts, but temporal or spatial differences in PAI activity were not detected in response to the gonadotrophin surge. These results indicate that PAI-1 and PAI-2 mRNAs are upregulated in preovulatory bovine follicles after the gonadotrophin surge in a cell-specific way. Regulation of PAI-1 and PAI-2 may help to control plasminogen activator activity associated with ovulation and early corpus luteum formation.

Applying a highly specific and reproducible cDNA RDA method to clone garlic up-regulated genes in human gastric cancer cells

AIM: To develop and optimize cDNA representational difference analysis (cDNA RDA) method and to identify and clone garlic up-regulated genes in human gastric cancer (HGC) cells.

METHODS: We performed cDNA RDA method by using abundant double-stranded cDNA messages provided by two self-constructed cDNA libraries (Allitridi-treated and paternal HGC cell line BGC823 cells cDNA libraries respectively). BamH I and Xho I restriction sites harbored in the library vector were used to select representations. Northern and Slot blots analyses were employed to identify the obtained difference products.

RESULTS: Fragments released from the cDNA library vector after restriction endonuclease digestion acted as good marker indicating the appropriate digestion degree for library DNA. Two novel expressed sequence tags (ESTs) and a recombinant gene were obtained. Slot blots result showed a 8-fold increase of glia-derived nexin/protease nexin 1 (GDN/PN1) gene expression level and 4-fold increase of hepatitis B virus x-interacting protein (XIP) mRNA level in BGC823 cells after Allitridi treatment for 72 h.

CONCLUSION: Elevated levels of GDN/PN1 and XIP mRNAs induced by Allitridi provide valuable molecular evidence for elucidating the garlic's efficacies against neurodegenerative and inflammatory diseases. Isolation of a recombinant gene and two novel ESTs further show cDNA RDA based on cDNA libraries to be a powerful method with high specificity and reproducibility in cloning differentially expressed genes.

Epidermal growth factor and pro-inflammatory cytokines regulate the expression of components of plasminogen activation system in U373-MG astrocytoma cells

Cytokines and growth factors that influence both secretion of the extracellular matrix (ECM) proteins and migration of the cells decide about the final outcome of tissue remodelling. We have examined expression of the components of the plasminogen activation system in human astrocytoma U373-MG cells and found that interleukin 1beta (IL-1beta), tumour necrosis factor alpha TNF-alpha), interferon gamma (INF-gamma) and epidermal growth factor (EGF) specifically regulate the expression of tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitor type 1 (PAI-1) and protease nexin-1 (PN-1). We conclude that EGF and IFN-gamma are new important regulators of the plasminogen activation system in astrocytoma cells and, therefore, may influence turnover of extracellular matrix and migration of cells within the brain.

Plasminogen Activators and Inhibitors in the Corneas of Mice Infected with Pseudomonas aeruginosa

PURPOSE

To characterize the presence of plasminogen activators and their inhibitors in the corneas during the inflammatory response in naïve and immunized mice intracorneally infected with Pseudomonas aeruginosa.

METHODS

RT-PCR was used to detect gene expression for plasminogen activators and their inhibitors in naïve and immunized mice. Immunoblot analysis, zymography, and ELISA were used to demonstrate the syntheses of these proteins.

RESULTS

Naïve mice intracorneally infected with P. aeruginosa showed a temporally enhanced expression of tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitors 1 and 2 (PAI-1 and PAI-2), over a several-day holding period. Immunized mice demonstrated a lower and shorter expression of these factors over the same period. Expression of these factors at the mRNA and protein levels may have been due to enzymes and inhibitors present in inflammatory cells and in resident corneal cells.

CONCLUSIONS

These results show a correlation between the overexpression of the PA system in infected naïve mice as part of the inflammatory response, with eventual ocular destruction. Immunized mice exhibit a more balanced and shorter expression of the PA system, which may contribute to the restoration of corneal clarity.

Continuing metformin throughout pregnancy in women with polycystic ovary syndrome appears to safely reduce first-trimester spontaneous abortion: a pilot study

OBJECTIVE

To determine whether metformin would safely reduce the rate of first-trimester spontaneous abortion without teratogenicity in 19 women with the polycystic ovary syndrome (PCOS).

DESIGN

Prospective pilot study.

SETTING

Outpatient.

PATIENT(S)

Twenty-two previously oligoamenorrheic, nondiabetic women with PCOS; 125 women with PCOS who were not currently pregnant and who had > or = 1 previous pregnancy while they were not receiving metformin.

INTERVENTION(S)

Metformin, 1.5-2.55 g/day, throughout pregnancy.

MAIN OUTCOME MEASURE(S)

Rates of first-trimester spontaneous abortion and teratogenicity.

RESULT(S)

Before metformin, 10 women had 22 previous pregnancies with 16 first-trimester spontaneous abortions (73%). While receiving metformin, these 10 women had 6 normal live births (60%), 1 spontaneous abortion (10%), and 3 normal ongoing pregnancies (30%) (all > or = 13 weeks; median gestation, 23 weeks). Among women receiving metformin, including those with live births and normal pregnancy for at least the first trimester, 1 of 10 (10%) had first-trimester spontaneous abortion compared with 73% in 22 previous pregnancies without metformin (P<.002). To date, the 19 women receiving metformin have had no adverse maternal side effects, and no birth defects have occurred; 9 (47%) had normal term live births, 2 (11%) had normal and appropriate for gestational age births (one at 33 and one at 35 weeks), 6 (32%) have ongoing normal pregnancies lasting longer than the first trimester, and 2 (10.5%) had first-trimester spontaneous abortions. Sonography showed normal fetal development without congenital defects in the 6 ongoing pregnancies (median gestation, 23 weeks). Among women who received metformin before conception, reductions in insulin and plasminogen activator inhibitor activity were correlated (r=0.65, P=.04).

CONCLUSION(S)

Metformin therapy throughout pregnancy in women with PCOS reduces the otherwise high rate of first-trimester spontaneous abortion seen among women not receiving metformin and does not appear to be teratogenic.

Localization of plasminogen activators and plasminogen-activator inhibitors in human gingival tissues demonstrated by immunohistochemistry and in situ hybridization

The plasminogen-activating system plays an important part in tissue proteolysis in physiological as well as pathological processes. Plasminogen activators u-PA (urokinase) and t-PA (tissue) as well as the inhibitors PAI-1 and PAI-2 are present in gingival crevicular fluid in concentrations significantly greater than in plasma. This fact, and the finding that the concentrations of t-PA and PAI-2 are higher in areas with gingival inflammation, indicate local production of these components. The present study describes, by means of in situ hybridization and immunohistochemistry, the localization of the plasminogen activators and their inhibitors in gingival tissues from patients undergoing periodontal surgery. t-PA mRNA and t-PA antigen were primarily found in the epithelial tissues, predominantly in the sulcular and junctional regions, although occasionally in the oral epithelium and in blood vessels of the connective tissue. u-PA and u-PA-receptor signals were seen in single cells within the junctional and sulcular epithelia and adjacent to blood vessels close to the junctional epithelium, but rarely in the oral epithelium. Similar to t-PA, the predominant location of PAI-2 mRNA was the gingival epithelia. In the junctional and sulcular epithelia, PAI-2 mRNA was seen throughout the thickness, while in the oral epithelium the strongest signals were seen in stratum granulosum and stratum spinosum. PAI-1 mRNA was invariably found in the connective tissue associated with blood vessels. The present study confirms earlier indications of local production of plasminogen activators and their inhibitors in gingival tissues. In addition, the results demonstrate that t-PA and PAI-2 in these patients are produced predominantly in the epithelial tissues. Furthermore, the presence of t-PA and PAI-2 seems to be most pronounced in the areas likely to be subjected to bacterial assault.

Reduction of tumor cell migration and metastasis by adenoviral gene transfer of plasminogen activator inhibitors

Recombinant adenoviral vectors expressing u-PA, t-PA, PAI-1 and PAI-2 were employed to correlate the expression of components of the fibrinolytic system with the invasiveness of HT 1080 tumor cells. Migration through Transwell inserts in vitro in the presence of plasminogen was increased up to 22% by overexpression of u-PA, whereas t-PA had no effect. Gene transfer of PAI-1 or PAI-2 both reduced migration in a dose-dependent manner by up to 43% with PAI-1 and 29% with PAI-2. Two routes of gene transfer were used to alter metastasis of subcutaneously implanted HT 1080 cells expressing firefly luciferase in nude mice. Infection of cultured tumor cells with adenovirus expressing either PAI-1 or PAI-2 before implantation significantly reduced the incidence of lung metastasis by 60% compared with control virus. However, only PAI-2 reduced the incidence of lung and brain metastasis following liver gene transfer. Although PAI gene transfer by either route reduced primary tumor size, it had little effect on tumor vascularization or host survival. The migratory and metastatic phenotype of HT 1080 tumor cells is thus directly dependent on u-PA expression levels and can be altered by gene transfer of u-PA or plasminogen activator inhibitors.

The MH1 domains of smad2 and smad3 are involved in the regulation of the ALK7 signals

The biological responses of the transforming growth factor beta (TGF-beta) superfamily are induced by activation of a receptor complex and Smad proteins. We surveyed the TGF-beta superfamily receptors using the degenerate PCR strategy, and found activin receptor-like kinase 7 (ALK7) to be abundantly expressed in fetal rat pancreatic islets. ALK7 is also expressed in adult rat islets and pancreatic beta-cell-derived MIN6 cells. The constitutively active form of ALK7, ALK7(T194D), activated Smad3 and a chimeric Smad protein, Smad3-2, containing the MH1 domain of Smad3 and the MH2 domain of Smad2, and translocated them to nuclei and then induced activation of the human PAI-1 promoter. However, neither Smad2 nor Smad2-3 protein, containing the MH1 domain of Smad2 and the MH2 domain of Smad3 were activated. These results indicate that the ALK7 signal regulates nuclear localization and activation of Smad2 and Smad3, and the MH1 domain of Smad2 has inhibitory effects on the nuclear localization.

Regulation of prothrombin, thrombin receptor, and protease nexin-1 expression during development and after denervation in muscle

Prothrombin, thrombin receptor (ThR), and protease nexin-1 (PN-1) mRNA levels in mouse muscle were quantified using competitive reverse transcriptase-polymerase chain reaction during development and after denervation to examine the possible role of thrombin in activity-dependent synapse elimination at the neuromuscular junction. The results showed that the levels of prothrombin and ThR were maximal at birth and decreased by two orders of magnitude by postnatal day 20 (P20). The level of PN-1 mRNA was fairly constant during development except for a 4-fold to 5-fold downregulation at P10 and P15, the periods of maximal synapse elimination at the rodent neuromuscular junction. The expression of prothrombin mRNA in muscle at birth was 41-fold and 22-fold lower than those of ThR and PN-1, respectively, and the level of difference between prothrombin and PN-1 reached almost three orders of magnitude at adulthood. Denervation of adult muscle resulted in a reversal of the relative expression levels of the three genes. There were rapid 8-fold and 10-fold increases in prothrombin and ThR mRNA, respectively, and a 2-fold decrease in PN-1 mRNA. The changes in mRNA levels of the three genes after denervation indicated that these genes were regulated in a innervation-dependent manner and that nerve activity may play an important regulatory role in the expression of prothrombin, ThR, and PN-1. The concurrent regulation of prothrombin and ThR suggests that thrombin-mediated cellular activities in muscle may be affected via the activation of ThR. An elevated level of local thrombin or thrombin-like activity might result from the decreased inhibitory activity of PN-1 during the period of peak synapse elimination in muscle development.

Array-based multiplex analysis of candidate genes reveals two independent and additive genetic risk factors for myocardial infarction in the Finnish population

We analysed common variants of eight genes implicated previously as risk factors for coronary heart disease or myocardial infarction (MI) in a cross-sectional study on patients with a history of MI and in carefully matched controls from the Finnish population. The most common low density lipoprotein receptor mutations in Finland were also included in our analysis. Multiplex genotyping of the target genes was performed using a specific and efficient array-based minisequencing system. The 4G allele of the plasminogen activator inhibitor gene (P < 0.05) and the PlA2 allele of the glycoprotein IIIa gene (P < 0.01) were associated with an increased risk of MI in our study population. We analysed the combined effect of these risk alleles and found that the concurrent carrier status of the two genetic variants conferred a high risk for the development of MI in our sample (OR = 4.5, P = 0.001), which was particularly prominent in male subjects (OR = 6.4, P = 0.0005). This study demonstrates the application of a new powerful tool for genome analysis to yield information on the inherited determinants of susceptibility to MI. The observation of two separate genes contributing an additive risk of developing MI exemplifies the advantages of multiplex analysis of genetic variation.

Regulation of prothrombin, thrombin receptor, and protease nexin-1 expression during development and after denervation in muscle

Prothrombin, thrombin receptor (ThR), and protease nexin-1 (PN-1) mRNA levels in mouse muscle were quantified using competitive reverse transcriptase-polymerase chain reaction during development and after denervation to examine the possible role of thrombin in activity-dependent synapse elimination at the neuromuscular junction. The results showed that the levels of prothrombin and ThR were maximal at birth and decreased by two orders of magnitude by postnatal day 20 (P20). The level of PN-1 mRNA was fairly constant during development except for a 4-fold to 5-fold downregulation at P10 and P15, the periods of maximal synapse elimination at the rodent neuromuscular junction. The expression of prothrombin mRNA in muscle at birth was 41-fold and 22-fold lower than those of ThR and PN-1, respectively, and the level of difference between prothrombin and PN-1 reached almost three orders of magnitude at adulthood. Denervation of adult muscle resulted in a reversal of the relative expression levels of the three genes. There were rapid 8-fold and 10-fold increases in prothrombin and ThR mRNA, respectively, and a 2-fold decrease in PN-1 mRNA. The changes in mRNA levels of the three genes after denervation indicated that these genes were regulated in a innervation-dependent manner and that nerve activity may play an important regulatory role in the expression of prothrombin, ThR, and PN-1. The concurrent regulation of prothrombin and ThR suggests that thrombin-mediated cellular activities in muscle may be affected via the activation of ThR. An elevated level of local thrombin or thrombin-like activity might result from the decreased inhibitory activity of PN-1 during the period of peak synapse elimination in muscle development.

Cholinergic stimulation increases thrombin activity and gene expression in cultured mouse muscle

Activity-dependent synapse reduction is a major determinant of neuromuscular innervation. Previous research has shown that nanomolar concentrations of hirudin, a specific thrombin antagonist, significantly attenuates this reduction, and protease nexin 1 (PN1), an endogenous thrombin inhibitor closely localized to the neuromuscular synapse, can inhibit synapse reduction at similar concentrations. Protease inhibitors which do not inhibit thrombin, including cystatin and aprotinin, had no effect on synapse reduction. We present a series of experiments examining whether prothrombin and/or PN1 gene expression, as well as thrombin activity, are regulated in muscle cultures by acetylcholine (ACh) receptor activation. We also studied the effect of exogenous thrombin on synapse elimination in co-cultures of muscle and cholinergic neurons. Cultured muscle cells were electrically blocked with tetrodotoxin (TTX), or co-treated with ACh in order to isolate ACh receptor activation. Electrical blockade resulted in a decrease in thrombin release to about two-thirds of control values. The application of ACh to electrically blocked muscle cultures resulted in a 2.5-fold increase in thrombin activity released into the medium and a 2-fold increase in prothrombin gene expression. In contrast, ACh treatment in the presence of TTX had no effect on PN1 gene expression compared to treatment with TTX alone. In addition, exogenous thrombin significantly increased synapse elimination in unstimulated muscle/cholinergic neuron co-cultures. These results suggest that thrombin or a thrombin-like molecule released from muscle is required for activity-dependent synapse elimination and is regulated by neuromuscular activity.

Gene targeting and gene transfer studies of the biological role of the plasminogen/plasmin system

A possible role of the plasminogen/plasmin or fibrinolytic system in several biological processes has been implied from correlations between fibrinolytic activity and (patho)physiological phenomena. However, such indirect evidence does not allow to definitively establish the biological relevance of this system. Two recently developed technologies, gene targeting and gene transfer, have allowed to more definitively characterize the in vivo role of gene products. The consequences of gain or loss of function of fibrinolytic system components on reproduction, development, health, survival and on hemostasis, thrombosis, neointima formation, tissue remodeling, brain function, malignancy and neovascularization is summarized below. In addition, the possible use of transgenic mice to study gene regulation or to generate monoclonal antibodies against conserved epitopes in the targeted proteins is discussed.

Differential regulation of plasminogen activation in normal keratinocytes and SCC-4 cells by fibroblasts

The plasminogen activator (PA)/plasmin system is thought to be involved in processes such as tumor invasion and wound healing, during which epithelial and mesenchymal cells come close together. However, information on regulation of the PA/plasmin system during epithelial-mesenchymal interactions is scarce. Therefore, we examined the in vitro modulation of the production and activity of the components of the PA/plasmin system in squamous carcinoma cells (SCC-4) and normal human keratinocytes in relation to cell density and the presence or absence of fibroblasts (3T3 cells). There was an inverse relation between cell density and mRNA expression for urokinase-type plasminogen activator (u-PA) and u-PA receptor in both SCC-4 cells and keratinocytes. In addition, such a relation was found for plasminogen activator inhibitor types 1 (PAI-1) and 2 (PAI-2) in SCC-4 monocultures, but not in keratinocyte monocultures. In contrast to monocultures, variation of cell density did not affect the mRNA expression of the components of the PA/plasmin system in cocultures of SCC-4 cells or keratinocytes with 3T3 cells. However, the relative expression of mRNAs in co-cultures was clearly different from that in monocultures, especially at low cell density. For most of the components of the PA/plasmin system, a decrease in mRNA expression and u-PA receptor protein was observed at most cell densities, whereas for PAI-1 only in keratinocytes a marked increase was documented. Zymography of supernatants revealed that the levels of both free u-PA and PA-PAI were increased in SCC-4/3T3 co-cultures, whereas in keratinocytes/3T3 co-cultures, only levels of the PA-PAI complex were increased, while the amount of free u-PA activity decreased. This occurred despite the increase u-PA immunoreactivity and was probably caused by the markedly elevated levels of immunoreactive PAI-1. The results of the present study reveal that the production and synthesis of various components of the PA/plasmin system in keratinocytes and SCC-4 cells depend on the density of epithelial cells and are modulated by fibroblasts, probably through a direct cell-cell or cell-matrix contact. Fibroblast-induced modulations are similar in keratinocytes and SCC-4 cells except for the regulation of PAI-1, which is markedly enhanced only in keratinocytes. This suggests that the modulation of PA activity in the direct microenvironment may be different under physiologic and pathologic conditions.

Human Co115 colon carcinoma cells potentiate the degradation of laminin mediated by tissue-type plasminogen activator

The plasminogen activation (PA) system of human Co115 colon carcinoma cells was investigated. Analysis at the levels of protein and mRNA of cultured cells and of histozymography of tumor xenografts in nude mice showed that Co115 cells produce only tissue type PA (t-PA) and no urokinase (u-PA). Also, mRNA for the u-PA receptor and for PA inhibitor type 2 (PAI-2), but not for PAI-1, were detected. We developed a quantitative degradation assay using glutaraldehyde-immobilized 125I-laminin to investigate the capacity of Co115 cells to degrade laminin. Laminin degradation by Co115 cells was completely inhibited by 100 micrograms/ml of polyclonal anti-t-PA IgG, by the plasmin inhibitors aprotinin (100 micrograms/ml) or epsilon-aminocaproic acid (EACA; at 0.3 M), but not by antibodies against u-PA or u-PAR nor by nonimmune IgG. Cycloheximide-treated Co115 cells were unable to degrade laminin but increased laminin degradation induced by conditioned medium of Co115 cells or recombinant t-PA. No potentiation was observed when Co115 cells and laminin were kept separated by Transwell inserts. Our results suggest that Co115 human colon carcinoma cells degrade laminin by potentiating t-PA-mediated plasminogen activation at the cell surface which requires close contact between tumor cells and laminin substrate.

Gene regulation of interleukin-1 beta, interleukin-1 receptor type I, and plasminogen activator inhibitor-1 and -2 in human granulosa-luteal cells

OBJECTIVE

To investigate the regulation of messenger ribonucleic acid (mRNA) levels of interleukin-1 beta (IL-1 beta), interleukin-1 (IL-1) receptor type 1, and plasminogen activator (PA) inhibitor-1 and -2 in cumulus cells, granulosa-luteal cells, and macrophage-depleted granulosa-luteal cells obtained from human preovulatory follicles.

DESIGN

Prospective longitudinal study.

SETTING, PATIENTS

Patients undergoing assisted reproductive technologies (ART) in the Department of Gynecology and Obstetrics, Stanford University, Stanford, California.

INTERVENTIONS

Cumulus cells and granulosa-luteal cells were collected by ultrasound-guided transvaginal aspiration at the time of ART.

MAIN OUTCOME MEASURES

Northern blot analysis of mRNA levels of IL-1 beta, IL-1 receptor type 1, PA inhibitor-1 and -2 in cumulus cells, granulosa-luteal cells and macrophage-depleted granulosa-luteal cells, and indirect immunocytochemical analysis of the IL-1 system and macrophages in granulosa-luteal cell preparations were performed.

RESULTS

Interleukin-1 beta mRNA levels in uncultured cumulus cells were less than those of uncultured granulosa-luteal cells with no differences in IL-1 receptor type 1 mRNA levels between these two cell types. Granulosa-luteal cell IL-1 receptor type 1 mRNA levels were expressed constitutively throughout 24 hours of culture with no effect by hCG, whereas IL-1 beta mRNA levels increased within 6 hours, and then remained elevated for 24 hours with no effect by hCG. Interleukin-1 beta significantly increased granulosa-luteal cell mRNA levels of IL-1 beta (over twofold), IL-1 receptor type 1 (over twofold), PA inhibitor-1 (approximately 1.4-fold), and PA inhibitor-2 (approximately 1.6-fold). In contrast, IL-1 beta had no effect on IL-1 beta and IL-1 receptor type 1 mRNA levels in macrophage-depleted granulosa-luteal cells. Granulosa-luteal cells, not macrophages, account for the majority of the immunocytochemical staining for IL-1 beta and IL-1 receptor type 1 in follicular aspirates.

CONCLUSIONS

These studies suggest that the IL-1 system is regulated in human granulosa-luteal cells during the periovulatory period. Furthermore, the augmentation of PA inhibitor-1 and -2 mRNA levels by IL-1 beta suggests a potential role for IL-1 beta in remodeling of the human ovary during the periovulatory period.

Influence of exogenous growth factors on the expression of plasminogen activators and plasminogen activator inhibitors by cells isolated from normal and healing rabbit ligaments

In this investigation, we demonstrate that cells from normal and healing rabbit ligaments are selective in their responsiveness to various growth factors. The cells analyzed included fibroblasts isolated from the synovium, the anterior cruciate ligament, and the medial collateral ligament (midsubstance and epiligament). Fibroblasts isolated from scar tissue of medial collateral ligament that had been allowed to heal for 3 weeks also were analyzed. The addition of insulin-like growth factor-2 or transforming growth factor-beta 1 was observed to alter, in a dose-dependent manner, the expression of plasminogen activator and plasminogen activator inhibitor by connective tissue cells. However, the response to these growth factors was cell specific. Fibroblasts isolated from the midsubstance, epiligament, and scar tissue of the medial collateral ligament were responsive to these growth factors; fibroblasts isolated from the anterior cruciate ligament and synovium did not have a detectable response. The cells from the normal and healing medial collateral ligament responded to both growth factors by increasing plasminogen activator inhibitor activity. This was observed at both the protein and RNA level. In contrast, the addition of insulin-like growth factor-1 or acidic or basic fibroblast growth factor to cells derived from normal or healing ligament did not result in any detectable alteration of plasminogen activator or plasminogen activator inhibitor activity. These results are similar to those observed with an explant system and indicate that cells isolated from ligament tissue maintain their responsiveness to these growth factors in the absence of matrix. As the major effect of insulin-like growth factor-2 and transforming growth factor-beta 1 on the cells tested was to increase plasminogen activator inhibitor activity, such an alteration should diminish the activity of plasminogen activator, an enzyme capable of directly and indirectly proteolyzing matrix molecules, and thus contribute to a more anabolic environment.

Hypofibrinolysis: a common, major cause of osteonecrosis

In 30 patients with osteonecrosis of the hip (12 idiopathic, 18 secondary), we assessed the role of hypofibrinolysis mediated by high levels of plasminogen activator inhibitor (PAI). We evaluated hypofibrinolysis as a common, potentially reversible, pathophysiologic cause of idiopathic osteonecrosis. In all 18 patients with secondary osteonecrosis, PAI was normal, as was the ability to activate fibrinolysis. Nine of the 12 patients with idiopathic osteonecrosis had exceptionally high PAI levels and could not normally elevate tissue plasminogen activator (tPA-Fx), the major stimulator of fibrinolysis, after 10 min of venous occlusion at 100 mm Hg. The group of 12 patients with idiopathic osteonecrosis, compared to the 18 with secondary osteonecrosis, had low mean stimulated tPA-Fx (1.92 vs. 7.6 IU/ml, P < or = .001) and very high stimulated PAI-Fx (70 vs. 7.6 U/ml, P < or = .01). Three of the 12 patients with idiopathic osteonecrosis had both normal PAI and normal stimulated tPA-Fx. These three patients and 14 of the 18 with secondary osteonecrosis had high lipoprotein (a) [Lp(a)] (> 20 mg/dl). Mean Lp(a) was much higher (60 mg/dl) in the patients with secondary osteonecrosis than Lp(a) (16 mg/dl, P < or = .001) in the 12 patients with idiopathic osteonecrosis. These findings suggest that hypofibrinolysis mediated by high PAI is a common cause of idiopathic osteonecrosis, whereas high Lp(a) may play an etiologic role in secondary osteonecrosis. Prospective studies of patients with high PAI and/or high Lp(a) should be carried out to assess further their apparently causal roles in osteonecrosis.

LPS induces major changes in the extracellular proteolytic balance in the murine kidney

Recent investigations have shown that in the murine kidney urokinase (uPA) and tissue-type plasminogen activator (tPA) are synthesized and released in urine by tubular epithelial cells, raising the possibility that plasminogen activators (PAs) may be involved in the maintenance of patency and fluidity in renal tubules. To further investigate the contribution of the PA system in renal pathology, we have determined the effects of LPS on the renal production of PAs: we localized PA-catalyzed proteolysis by zymographic analysis of tissue sections and studied the accumulation of mRNAs for PAs and their inhibitors (PAI-1 and PAI-2) by in situ hybridization. Both a single and two injections of LPS induced a dramatic reduction in urinary and renal uPA enzymatic activity; this decrease in catalytic activity was attributable to a reduction in uPA mRNA levels in both proximal and distal tubules. By contrast, we noticed a marked increase of tPA mRNA content in glomerular cells which was not accompanied by a concomitant increase in tPA-mediated proteolytic activity. In addition, a major up-regulation in PAI-1 mRNA levels was observed throughout the kidney, while PAI-2 mRNA was not detectable in the kidneys of control or LPS-injected animals. Our investigations document the profound alterations of the PA/PAI balance in renal tissue following in vivo LPS administration. They suggest that imbalanced extracellular proteolysis might participate in the alterations of kidney function observed in septic shock.

Plasminogen activators, their inhibitors, and urokinase receptor emerge in late stages of melanocytic tumor progression

Degradation of the extracellular matrix and other tissue barriers by proteases like plasminogen activators (PAs) is a prerequisite for neoplastic growth and metastasis. Recently, we reported that highly metastatic behavior of human melanoma cells in nude mice correlates with urokinase-type PA (u-PA) expression and activity and with PA inhibitor type 1 and 2 (PAI-1, PAI-2) expression. Here we report on the occurrence of components of the PA system in the various stages of human melanoma tumor progression in situ. We studied the protein distribution on freshly frozen lesions of common nevocellular nevi (n = 25), dysplastic (= atypical) nevi (n = 16), early primary melanomas (n = 8), advanced primary melanomas (n = 11), and melanoma metastases (n = 17). Tissue-type PA was present in endothelial cells in all lesions, whereas in metastases it could be detected in tumor cells in a minority of the lesions. u-PA, its receptor, PAI-1, and PAI-2 could not be detected in benign and in early stages but appeared frequently in advanced primary melanoma and melanoma metastasis lesions. u-PA was detected in stromal cells and in tumor cells at the invasive front, the u-PA receptor and PAI-2 in tumor cells, and PAI-1 in the extracellular matrix surrounding tumor cells. Localization of the corresponding messenger RNAs and enzyme activities revealed a similar distribution. We conclude that plasminogen activation is a late event in melanoma tumor progression.

Variable and multiple expression of Protease Nexin-1 during mouse organogenesis and nervous system development

Protease Nexin-1 (PN-1) also known as Glia-Derived Nexin (GDN) inhibits the activity of several serine proteases including thrombin, tissue (tPA)- and urokinase (uPA)-type plasminogen activators. These and other serine proteases seem to play roles in development and tissue homeostasis. To gain insight into where and when PN-1 might counteract serine protease activities in vivo, we examined its mRNA and protein expression in the mouse embryo, postnatal developing nervous system and adult tissues. These analyses revealed distinct temporal and spatial PN-1 expression patterns in developing cartilage, lung, skin, urogenital tract, and central and peripheral nervous system. In the embryonic spinal cord, PN-1 expression occurs in cells lining the neural canal that are different from the cells previously shown to express tPA. In the developing postnatal brain, PN-1 expression appears transiently in many neuronal cell populations. These findings suggest a role for PN-1 in the maturation of the central nervous system, a phase that is accompanied by the appearance of different forms of PN-1. In adults, few distinct neuronal cell populations like pyramidal cells of the layer V in the neocortex retained detectable levels of PN-1 expression. Also, mRNA and protein levels did not correspond in adult spleen and muscle tissues. The widespread and complex regulation of PN-1 expression during embryonic development and, in particular, in the early postnatal nervous system as well as in adult tissues suggests multiple roles for this serine protease inhibitor in organogenesis and tissue homeostasis.

Protease-nexin I as an androgen-dependent secretory product of the murine seminal vesicle

A search for inhibitors of urokinase-type plasminogen activator (uPA) in the male and female murine genital tracts revealed high levels of a uPA ligand in the seminal vesicle. This ligand is functionally, biochemically and immunologically indistinguishable from protease-nexin I (PN-I), a serpin ligand of thrombin and uPA previously detected only in mesenchymal cells and astrocytes. A survey of murine tissues indicates that PN-I mRNA is most abundant in seminal vesicles, where it represents 0.2-0.4% of the mRNAs. PN-I is synthesized in the epithelium of the seminal vesicle, as determined by in situ hybridization, and is secreted in the lumen of the gland. PN-I levels are much lower in immature animals, and strongly decreased upon castration. Testosterone treatment of castrated males rapidly restores PN-I mRNA levels, indicating that PN-I gene expression is under androgen control.

Cytokines induce urokinase-dependent adhesion of human myeloid cells. A regulatory role for plasminogen activator inhibitors

Differentiation of monocytic precursors often results in adhesive properties thought to be important in migration. In this study, the influence of cytokines, known to induce macrophage differentiation, on the adhesiveness of the monocytic cell line U937 was examined in vitro. Despite development of a macrophage morphology, < 5% of cytokine-stimulated U937 cells were adherent at 24 h. Addition of 1-10 nM urokinase-type plasminogen activator (uPA) induced adherence in the presence of transforming growth factor type beta-1, 1,25-(OH)2 vitamin D3, granulocyte macrophage colony-stimulating factor, or tumor necrosis factor alpha. uPA-dependent adhesiveness was reversible after 24 h of stimulation with cytokines and uPA as adherence was prevented by the subsequent addition of anti-uPA antibodies. Adherence induced by diisopropylfluorophosphate-inactivated uPA was severalfold greater than that seen with active uPA. This difference was largely due to cell-surface turnover of active uPA complexed with plasminogen activator inhibitor (PAI). These data indicate that cytokines prime monocyte progenitors for uPA receptor-mediated signals leading to adherence, continued uPA receptor occupancy is required for adherence, and PAI decreases adherence by promoting clearance of uPA/PAI complexes. Thus the interaction of uPA and PAI at the cell surface, known to affect extracellular matrix proteolysis and hence myeloid cell migration, also regulates adhesion. The coordinated regulation of these two uPA functions by PAI may enhance the migratory potential of monocytic cells.

Protease nexin 1 is expressed in the human placenta

Protease nexin 1 (PN1), a serine protease inhibitor that inactivates thrombin, urokinase, and plasmin, is produced abundantly in cultures of human fibroblasts and rat and human glioma cells. The major sites of PN1 synthesis in vivo and the specific physiological function(s) of this serpin are unknown. Using Northern blot analysis and a full-length PN1 cDNA probe we demonstrated the presence of PN1 mRNA in human term placentas. In situ hybridization of placental tissue with a PN1 riboprobe showed that PN1 mRNA is present throughout the placenta and is also abundant in the placental membranes. Immunohistochemical analysis with an anti-PN1 antibody showed co-localization of PN1 and its mRNA within the placenta.

Physical mapping of four serpin genes: alpha 1-antitrypsin, alpha 1-antichymotrypsin, corticosteroid-binding globulin, and protein C inhibitor, within a 280-kb region on chromosome I4q32.1

Alpha 1-antitrypsin (alpha 1AT; protease inhibitor [PI] locus), alpha 1-antichymotrypsin (alpha 1ACT; AACT locus), corticosteroid-binding globulin (CBG; CBG locus), and protein C inhibitor (PCI; PCI locus) are members of the serine protease inhibitor (serpin) superfamily. A noncoding PI-like (PIL) gene has been located 12 kb 3' of the PI gene. The PI, PIL, and AACT loci have been localized to 14q32.1, the CBG locus has been localized to 14q31-14q32.1, and PCI has been mapped to chromosome 14. Genetic linkage analysis suggests tight linkage between PI and AACT. We have used pulsed-field gel electrophoresis to generate a physical map linking these five serpin genes. The order of the genetic loci is AACT/PCI-PI-PIL-CBG, with a maximum distance of about 220 kb between the AACT/PCI and PI genes. These genes form a PI cluster at 14q32.1, similar to that of the homologous genes on murine chromosome l2. The close proximity of these genes has implications for disease-association studies.

Induction of endothelial cell expression of the plasminogen activator inhibitor type 1 gene by thrombosis in vivo

BACKGROUND

We have shown previously that products from activated platelets can augment synthesis of plasminogen activator inhibitor type 1 (PAI-1) in cultured endothelial and hepatoma (Hep G2) cells in vitro and increase plasma PAI-1 activity in vivo in rabbits. Accordingly, the effects of activation of platelets associated with thrombosis and thrombolysis in vivo on plasma PAI-1 activity and expression of the PAI-1 gene in endothelium, liver, and other organs were characterized.

METHODS AND RESULTS

Endothelial injury giving rise to platelet-rich thrombi was induced with electrical stimulation in carotid arteries in rabbits. Clot lysis and recanalization were induced subsequently with intravenous tissue-type plasminogen activator (t-PA) and verified with Doppler flow probes. Plasma PAI-1 activity (mean +/- SD) increased from 6 +/- 2 arbitrary units (AU)/ml to 129 +/- 48 AU/ml (n = 15) within several hours after recanalization. When t-PA had failed to induce recanalization, the increase was much less (from 7 +/- 2 to 42 +/- 23 AU/ml, n = 11). To define mechanisms responsible for these changes, PAI-1 messenger RNA (mRNA) was evaluated by Northern blot analysis and localized in tissues by in situ hybridization. Strong and consistent induction of PAI-1 mRNA was evident in aorta, heart, and liver of animals subjected to thrombosis (twofold to threefold increases compared with values in controls), particularly in those in which thrombolysis had been induced (fourfold to sixfold). After thrombolysis, an intense, PAI-1 mRNA-specific signal was detected in endothelium of aorta, liver, and heart, with less intense signals in endothelium of lung, adrenals, and kidneys.

CONCLUSIONS

The increases in plasma PAI-1 activity follow a preceding increase in endothelial cell expression of the PAI-1 gene as reflected by PAI-1 mRNA levels. Thus, increased synthesis of endothelial cell PAI-1 after thrombosis and thrombolysis may attenuate endogenous fibrinolysis early after coronary thrombolysis, thereby potentiating early, thrombotic reocclusion.