Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PLASMINOGEN”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed1975

Follicular plasminogen and plasminogen activator and the effect of plasmin on ovarian follicle wall.

Plasminogen, plasminogen activator, protease inhibitors, and a proteolytic activity are shown to be present in bovine follicular fluid. Much of the proteolytic activity appears to be due to plasmin. In addition, plasminogen activator activity can be demonstrated in follicle wall homogenates. Evidence that plasmin decreases the tensile strength of follicle wall preparations is also reported. The potential for the involvement of these substances in ovulation is discussed.

Animals↗
PubMed1983

Comparative electrophoretic analysis of human and porcine plasminogen activators in SDS-polyacrylamide gels containing plasminogen and casein.

Electrophoretic analysis of plasminogen activators from pig heart, human uterus, human plasma and human melanoma cells was performed in SDS-polyacrylamide gradient slab gels containing plasminogen and casein. Direct visualization of activator activity bands in polyacrylamide gels was achieved after removal of SDS, incubation in buffer, and staining with Coomassie brilliant blue. Tissue activator extracted from pig hearts displayed a molecular weight of 72000 and migrated similarly to activator secreted by human melanoma cells and to one activator component present in extracts of human uterus. Immunoadsorption experiments with melanoma cell activator antiserum indicated that these 72-kDa activators are all related immunologically. Human uterus also contained a second activator component with a molecular weight 55000, which migrated similarly to a higher molecular weight component of urokinase and cross-reacted with urokinase antiserum. We conclude that the 72-kDa uterine activator component represents a tissue activator and the 55-kDa component represents a urokinase-like activator. A euglobulin solution from venous occlusion plasma displayed multiple bands of plasmin activity in the Mr range 85000-96000. Two activator components were also present, one of Mr 72000 and another of Mr 62000. The 72-kDa euglobulin activator was adsorbed by MCA antiserum, and we conclude that this component represents vascular activator. The 62000 activator also had weak plasminogen-independent caseinolytic activity and was not affected by either melanoma cell activator or urokinase antisera. Conclusions concerning its identity cannot be made at this time.

Animals↗
PubMed1996

Effects of cadmium on the release of tissue plasminogen activator and plasminogen activator inhibitor type 1 from cultured human vascular smooth muscle cells and fibroblasts.

To evaluate the toxicity of cadmium on the blood fibrinolytic system during hemostasis, human vascular smooth muscle cells and human fibroblasts were cultured in the presence of cadmium chloride. It was found that cadmium markedly decreased the release of both tissue plasminogen activator antigen (t-PA:Ag) and plasminogen activator inhibitor type-1 antigen (PAI-1:Ag) from vascular smooth muscle cells. Other heavy metals including lead, manganese, mercury and nickel also decreased the t-PA:Ag and PAI-1:Ag release, however, cadmium was the most potent inhibitor. On the other hand, the release of t-PA:Ag was significantly increased whereas that of PAI-1:Ag was unaffected in fibroblasts after exposure to cadmium. Of the tested heavy metals, only cadmium increased the t-PA:Ag release from the cells. Electrophoretic enzymography revealed that cadmium reduced the activity of plasminogen activators in the conditioned medium of both vascular smooth muscle cells and fibroblasts. Cadmium markedly decreased the incorporation of [3H]leucine accompanied with a significant increase in the leakage of lactate dehydrogenase in vascular smooth muscle cells; however, the metal did not change these markers in fibroblasts. These results suggest that the regulation of fibrinolysis mediated by vascular smooth muscle cells and fibroblasts during hemostasis may be disturbed by cadmium.

Cadmium↗
PubMed1990

Forskolin down-regulates type-1 plasminogen activator inhibitor and tissue-type plasminogen activator and their mRNAs in human fibrosarcoma cells.

We have studied the effect of the adenylate cyclase-stimulating agent forskolin on expression of components of the plasminogen activation system in the human fibrosarcoma cell line HT-1080. By enzyme-linked immunosorbent assays, forskolin was found to cause a 2 to 4-fold decrease in intracellular and culture medium levels of type-1 inhibitor of plasminogen activators (PAI-1) and tissue-type plasminogen activator (t-PA). This was true for cells not treated with other agents and for cells, in which the PAI-1 and t-PA levels had been increased 5 to 10-fold by treatment with dexamethasone. This down-regulation could be traced back to corresponding decreases in the cellular levels of PAI-1 and t-PA mRNAs. Of the two PAI-1 mRNAs, the 2.4 kb species was 5-fold decreased by forskolin in cells treated with dexamethasone, while the 3.4 kb transcript was unaffected; in cells not treated with dexamethasone, forskolin affected the two PAI-1 transcripts in parallel. These studies show that in addition to the many inducers of PAI-1, PAI-1 gene expression is also subject to negative modulation by cyclic AMP. They also show that t-PA gene expression, in contrast to the induction by cyclic AMP observed in many other cell lines, may also be subject to negative regulation by cyclic AMP. Thus, hormonal agents acting with cyclic AMP as a second messenger may be involved in down-regulating PAI-1 and t-PA expression in vivo.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Cytokine-mediated regulation of rat ovarian function: interleukin-1 inhibits plasminogen activator activity through the induction of plasminogen activator inhibitor-1 (PAI-1).

Intraovarian IL-1 has recently been implicated as a mediator in the ovulatory process. Since PA activation is an established component of the ovulatory cascade, consideration was given in this report to the possibility that IL-1 may modulate ovarian PA economy. Whole ovarian dispersates from immature rats (25-27-days-old) were cultured under serum-free conditions for 48 h in the absence or presence of IL-1beta. Cellular PA activity was measured by plasminogen-dependent cleavage of 14C-labeled globin. Cells grown in the absence of IL-1 exhibited appreciable PA activity, as assessed by the cleavage of 0.074 +/- 0.026 mg [14C]-globin/5 x 10(5) cells (mean +/- SD). Exposure to IL-1 (10 ng/ml) led to a 30% reduction in cell-associated PA activity (p < 0.001). The IL-1-mediated inhibition occurred concurrently with a 10-fold increase in the ability of the corresponding conditioned media to inhibit exogenous urokinase activity. At similar cell densities of 5 x 10(5) cells/well, isolated cultures of theca and granulosa cells exhibited comparable PA activity in the absence of IL-1. However, only theca cells responded to IL-1 with inhibition of plasminogen activation and enhancement of urokinase inhibitory activity. Granulosa cells in turn failed to respond to IL-1. Both the inhibition of PA activity and the increase in urokinase inhibitory activity proved cell-density- and IL-1 dose-dependent. The IL-1-induced inhibition of urokinase was abolished by the administration of a polyclonal anti-rat PAI-1 IgG. Both effects of IL-1 were counteracted in a dose-dependent fashion by the soluble IL-1 receptor (which specifically complexes with IL-1), and by a highly-specific IL-1 receptor antagonist suggesting that the IL-1 effects are receptor-mediated. The present observations indicate that ovarian PA activity is subject to inhibition by IL-1 probably by way of PAI-1 of theca-interstitial origin. Inasmuch as IL-1 may be involved in initiating and maintaining the preovulatory cascade, the periovulatory activation of plasminogen must be accomplished by agents other than IL-1.

Animals↗
PubMed1984

Isolation of tissue-type plasminogen activator-inhibitor complexes from human plasma. Evidence for a rapid plasminogen activator inhibitor.

Plasminogen activator-inhibitor complexes were analyzed by SDS-polyacrylamide gel electrophoresis and enzymography. The complexes appeared as fibrinolytically active bands in the fibrin-indicator gel. A high-molecular-weight t-PA form comigrating with a t-PA-inhibitor complex (Mr 95 000-135 000) from cultured human endothelial cells was purified from plasma by immunoadsorption on anti-t-PA-Sepharose followed by gel filtration on Sephadex G-150. The high-molecular-weight t-PA form was fibrinolytically inactive when assayed by the fibrin-plate method. It was converted to a form with the same electrophoretic mobility as t-PA (Mr 72 000) when treated with 1.5 M NH4OH/39 mM SDS. These observations suggested that the plasma high-molecular-weight t-PA form was an enzyme-inhibitor complex. The complex did not show immunological cross-reactivity with a number of known plasma serine proteinase inhibitors. Both t-PA and u-PA rapidly formed complexes with an inhibitor which was present in plasma in pmolar concentrations. p-Aminobenzamidine blocked the reaction, indicating that the active center of the activator was indeed implicated in complex formation. The complex between the plasma inhibitor and t-PA and the high-molecular-weight t-PA had the same electrophoretic mobilities. The rapid plasminogen activator inhibitor in plasma showed remarkable similarity to a plasminogen activator inhibitor from cultured human endothelial cells. In addition to the high-molecular-weight t-PA form described above, three other t-PA forms were isolated from plasma. Our results indicated that they represented free t-PA and t-PA in complex with respectively C1-esterase inhibitor and alpha 2-antiplasmin.

Chromatography, Gel↗
PubMed2005

The possible role of tissue-type plasminogen activator and the plasminogen system in the pathogenesis of major depression.

Major depressive disorder (MDD) is one of the most common psychiatric illnesses with an unknown etiology. Evidence from animal and human studies has suggested that brain-derived neurotrophic factor (BDNF) function may be implicated in the pathogenesis of MDD. Tissue-type plasminogen activator (tPA) is a highly specific serine proteinase that catalyses the generation of zymogen plasminogen from the proteinase plasmin. Recent studies have found that the proteolytic cleavage of proBDNF, a BDNF precursor, to BDNF by the plasmin represents a mechanism by which the direction of BDNF action is controlled. Furthermore, studies using mice deficient in tPA has demonstrated that tPA is important for the stress reaction, a common precipitating factor for MDD. A study of the serum levels of the plasminogen activator inhibitor-1 (PAI-1), the major inhibitor of tPA, found that women with MDD had a higher PAI-1 concentration than normal controls. From these findings, it is proposed that the tPA/plasminogen system may play a role in the pathogenesis of MDD. Attempts to confirm the tPA/plasminogen hypothesis may lead to new directions in the study of the pathogenesis of MDD and the development of a novel intervention of this disorder.

Major Depressive Disorder↗
PubMed1997

Lead perturbs the regulation of spontaneous release of tissue plasminogen activator and plasminogen activator inhibitor-1 from vascular smooth muscle cells and fibroblasts in culture.

To evaluate the toxicity of lead on the blood fibrinolytic system during hemostasis, human aortic smooth muscle cells and human fetal lung fibroblasts were cultured in the presence of lead chloride. Tissue plasminogen activator antigen (t-PA:Ag) and plasminogen activator inhibitor-1 antigen (PAI-1:Ag) released were determined by enzyme immunoassay. It was found that lead decreased the release of both t-PA:Ag and PAI-1:Ag from vascular smooth muscle cells. On the other hand, in fibroblasts, the release of t-PA:Ag was markedly decreased whereas that of PAI-1:Ag was markedly increased by the metal. Fibrin zymography showed that lead reduced the plasminogen activator activity in the conditioned medium of both cell types. However, lead did not cause a nonspecific cell damage and an alteration of protein synthesis when evaluated by lactate dehydrogenase leakage and [14C]leucine incorporation, respectively. Lead accumulated within either vascular smooth muscle cells or fibroblasts in a dose-dependent manner; intracellular accumulation of calcium could be increased by lead. However, the effects of lead on the release of t-PA:Ag and PAI-1:Ag were different from those of calcium ionophore A23187. It was therefore suggested that regulation of spontaneous release of fibrinolytic proteins from subendothelial cells is disturbed by lead through intracellular calcium-independent pathway.

Aorta↗
PubMed1993

Plasminogen activators and plasminogen activator inhibitors in human colorectal carcinoma tissues are not expressed by the tumour cells.

Plasminogen activators (PA) have been implicated with the degradation of extracellular matrix during the invasive growth of metastasising tumour cells. The significance of PA expression in tumour cells for the in vivo growth of malignant tumours is still a matter of debate. We, therefore, performed immunohistological studies on human colon tumours using monoclonal antibodies against urokinase- (u-PA) and tissue-type plasminogen activator (t-PA) as well as against plasminogen activator inhibitors 1 and 2 (PAI-1, PAI-2). Normal colorectal mucosa of seven samples was negative for all four constituents of the PA system. Tumour epithelium of 64 colorectal carcinomas and 10 liver metastases was consistently negative for both, PA and their inhibitors. However, two of four human colon carcinoma cell lines weakly expressed u-PA, PAI-1 and PAI-2. Intestinal dendritic or fibroblast-like cells within the tumour tissue strongly expressed u-PA and, at a lower level, also t-PA, PAI-1 and PAI-2. Vascular endothelial cells were weakly positive for all components of the PA system in colon carcinoma. Our findings indicate that colon carcinoma cells in their natural environment do not express constituents of the PA system. PA activity, previously found in colon carcinoma tissue, is most likely derived from interstitial cells.

Colonic Neoplasms↗
PubMed1995

Plasminogen activator and plasminogen activator inhibitor expression by normal and aneurysmal human aortic smooth muscle cells in culture.

OBJECTIVES: Matrix metalloproteinases may play a major role in aortic wall degeneration causing abdominal aortic aneurysm (AAA). Available plasmin, required for MMP zymogen activation, is regulated by plasminogen activators (uPA, tPA) and plasminogen activator inhibitors (PAI-1, PAI-2). To appraise the impact of these regulatory proteins on aortic wall degeneration, expression at the level of translation and transcription was determined in human aortic smooth muscle cell (SMC) cultures. METHODS: Explants were derived from aneurysmal aortic tissue (n = 6) and from three male organ donors. Cells were also stimulated with 0.1-1.0 ng/ml IL-1 beta. RESULTS: uPA antigen and tPA antigen in the conditioned medium (CM) of normal SMCs were not detectable but AAA SMCs produced uPA (values are given as median (interquartile range)), [1.97 ng/ml/10(6) cells (1.50-8.21)] and tPA [7.02 ng/ml/10(6) cells (6.20-14.90)]. uPA antigen was absent from normal SMC cell extract (CE) but present in small amounts in AAA SMC CE [0.80 ng/mg protein (0.40-1.24)]. tPA was detectable in the CE of normal SMCs [3.2 ng/mg protein (1.90-3.40)] but at a lower concentration than in AAA SMCs [13.14 ng/mg protein (7.20-27.00)] (p < 0.05). IL-1 beta suppressed production of uPA and tPA in both types of SMCs. The difference in baseline PAI-1 release from normal SMCs and AAA SMCs was not statistically significant. Selective upregulation of PAI-1 was observed for AAA SMC after IL-1 beta stimulation. Northern analysis of AAA SMCs grown in serum containing medium exhibited clear bands for uPA. CONCLUSIONS: Human AAA SMCs are a source of elevated plasminogen activators. In the absence of a reciprocal rise of PAI an imbalance is created favouring proteolysis.

Aged↗
PubMed1988

Effectors of the activation of human [Glu1]plasminogen by human tissue plasminogen activator.

The activation of human [Glu1]plasminogen [( Glu1]Pg) by human recombinant (rec) two-chain tissue plasminogen activator (t-PA) is inhibited by Cl-, at physiological concentrations, and stimulated by epsilon-aminocaproic acid (EACA), as well as fibrin(ogen). Chloride functions as a result of its binding to [Glu1]Pg, with a Ki of approximately 9.0 mM, thereby rendering [Glu1]Pg a less effective substrate for two-chain rec-t-PA. EACA stimulates the activation in Cl-(-)containing solutions, with a Ka of approximately 4.0 mM, primarily by reversal of the Cl-(-)inhibitory effect. Fibrinogen appears to exert its stimulatory properties mainly through effects on the enzyme, two-chain rec-t-PA, with a Ka of approximately 3.7 microM in activation systems containing physiological levels of Cl-. Analysis of the results of this paper reveals that normal plasma components, Cl- and fibrinogen, exert major regulatory roles on the ability of [Glu1]Pg to be activated by two-chain rec-t-PA, in in vitro systems. The presence of Cl- inhibits the stimulation of [Glu1]Pg activation that would normally occur in the presence of fibrinogen, a result of possible importance to the observation that some degree of systemic fibrinogenolysis accompanies therapeutic use of tissue plasminogen activator.

Aminocaproic Acid↗
PubMed2000

Plasminogen-independent initiation of the pro-urokinase activation cascade in vivo. Activation of pro-urokinase by glandular kallikrein (mGK-6) in plasminogen-deficient mice.

The plasminogen activation (PA) system is involved in the degradation of fibrin and various extracellular matrix proteins, taking part in a number of physiological and pathological tissue remodeling processes including cancer invasion. This system is organized as a classical proteolytic cascade, and as for other cascade systems, understanding the physiological initiation mechanism is of central importance. The attempts to identify initiation routes for activation of the proform of the key enzyme urokinase-type plasminogen activator (pro-uPA) in vivo have been hampered by the strong activator potency of the plasmin, that is generated during the progress of the cascade. Using gene-targeted mice deficient in plasminogen (Plg -/- mice) [Bugge, T. H., Flick, M. J., Daugherty, C. C., and Degen, J. L. (1995) Genes Dev. 9, 794-807], we have now demonstrated and identified a component capable of initiating the cascade by activating pro-uPA. The urine from Plg -/- mice contained active two-chain uPA as well as a proteinase capable of activating exogenously added pro-uPA. The active component was purified and identified by mass spectrometry-based peptide mapping as mouse glandular kallikrein mGK-6 (true tissue kallikrein). The pro-uPA converting activity of the mGK-6 enzyme, as well as its ability to cleave a synthetic substrate for glandular kallikrein, was inhibited by the serine proteinase inhibitor leupeptin but not by other serine proteinase inhibitors such as aprotinin, antithrombin III, or alpha(1)-antitrypsin. We suggest that mouse glandular kallikrein mGK-6 is an activator of pro-uPA in the mouse urinary tract in vivo. Since this kallikrein is expressed in a number of tissues and also occurs in plasma, it can also be considered a candidate for a physiological pro-uPA activator in other locations.

Amino Acid Sequence↗
PubMed2000

Detection of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 2(PAI-2) in gingival crevicular fluid from healthy, gingivitis and periodontitis patients.

BACKGROUND: The regulation of plasminogen activation is a key element in controlling proteolytic events in the extracellular matrix. Our previous studies had demonstrated that in inflamed gingival tissues, tissue-type plasminogen activator (t-PA) is significantly increased in the extracellular matrix of the connective tissue and that interleukin 1beta(IL-1beta) can up regulate the level of t-PA and plasminogen activator inhibitor-2 (PAI-2) synthesis by human gingival fibroblasts. METHOD: In the present study, the levels of t-PA and PAI-2 in gingival crevicular fluid (GCF) were measured from healthy, gingivitis and periodontitis sites and compared before and after periodontal treatment. Crevicular fluid from106 periodontal sites in 33 patients were collected. 24 sites from 11 periodontitis patients received periodontal treatment after the first sample collection and post-treatment samples were collected 14 days after treatment. All samples were analyzed by enzyme-linked immunosorbent assay (ELISA) for t-PA and PAI-2. RESULTS: The results showed that significantly high levels of t-PA and PAI-2 in GCF were found in the gingivitis and periodontitis sites. Periodontal treatment led to significant decreases of PAI-2, but not t-PA, after 14 days. A significant positive linear correlation was found between t-PA and PAI-2 in GCF (r=0.80, p<0.01). In the healthy group, different sites from within the same subject showed little variation of t-PA and PAI-2 in GCF. However, the gingivitis and periodontitis sites showed large variation. These results suggest a good correlation between t-PA and PAI-2 with the severity of periodontal conditions. CONCLUSION: This study indicates that t-PA and PAI-2 may play a significant rôle in the periodontal tissue destruction and tissue remodeling and that t-PA and PAI-2 in GCF may be used as clinical markers to evaluate the periodontal diseases and assess treatment.

Adult↗
PubMed1995

The significance of fibrin binding by plasminogen activator inhibitor 1 for the mechanism of tissue-type plasminogen activator-mediated fibrinolysis.

The specific, reversible interaction between plasminogen activator inhibitor 1 (PAI-1) and intact fibrin polymers was studied using both purified components and isolated activated platelets as a source of PAI-1. A key reagent in these experiments is a PAI-1 mutant, having its P1 reactive center residue arginine replaced by methionine (PAI-1 R346M). The second-order association rate of PAI-1 R346M with tissue-type plasminogen activator is over 10,000-fold lower than that of wild-type PAI-1, whereas the ability of the variant to bind to fibrin is unaltered. Competition experiments demonstrated that PAI-1 R346M is equally effective as wild-type PAI-1 in displacing 125I-labeled PAI-1 from fibrin. Fibrinolysis, mediated by tissue-type plasminogen activator, is inhibited in a dose-dependent manner by purified PAI-1. The inhibition can be relieved in a dose-dependent manner by PAI-1 R346M, presumably due to displacement of wild-type PAI-1 by PAI-1 R346M. Perfusion studies, using platelet-rich clots, revealed that the incorporation of PAI-1 R346M dose dependently decreased the 50% clot lysis time. These data indicate that PAI-1 R346M displaces fibrin-bound, endogenous PAI-1 released from activated platelets. Implications to manipulate PAI-1 activity for the management of clinical complications, in particular reocclusion after thrombolytic therapy, are discussed.

Amino Acid Sequence↗
PubMed1995

Very low density lipoprotein receptor binds and mediates endocytosis of urokinase-type plasminogen activator-type-1 plasminogen activator inhibitor complex.

Very low density lipoprotein receptor (VLDL-R) was found to be expressed in bovine mammary gland and the human breast carcinoma cell line MCF-7 as an M(r) 105,000 variant, and in Chinese hamster ovary (CHO) cells transfected with human VLDL-R cDNA as an M(r) 130,000 variant. The receptor was purified by ligand affinity chromatography with immobilized M(r) 40,000 receptor-associated protein (RAP). The purified receptor was found to bind urokinase-type plasminogen activator-type-1 plasminogen activator inhibitor complex (u-PA.PAI-1), while there was no or very weak binding of active site blocked u-PA (DFP-u-PA), PAI-1 or u-PA-type-2 plasminogen activator inhibitor complex. The binding of u-PA.PAI-1 was blocked by RAP. The transfected CHO cells had an efficient, RAP-sensitive endocytosis of u-PA.PAI-1, severalfold higher than non-transfected parental CHO cells. u-PA.PAI-1 endocytosis was partially inhibited by DFP-u-PA, which blocks binding of the complex to the u-PA receptor. RAP and DFP-u-PA sensitive u-PA.PAI-1 endocytosis was also observed in MCF-7 cells, which were without detectable levels of other RAP-binding endocytosis receptors. These results show that VLDL-R represents a novel endocytosis mechanism for u-PA receptor-bound u-PA.PAI-1.

Amino Acid Sequence↗
PubMed1997

Variants of tissue-type plasminogen activator that display extraordinary resistance to inhibition by the serpin plasminogen activator inhibitor type 1.

Fibrinolysis is regulated in part by the interaction of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1). Previous investigations suggest that three specific arginine residues, Arg-298, Arg-299, and Arg-304 of t-PA, play a critical role in this important regulatory interaction. Our earlier studies have demonstrated that conversion of any of these three residues to a glutamic acid residue reduced the rate of inhibition of t-PA by PAI-1 by factors varying from 58-64. In addition, we have reported that the second order rate constant for inhibition by PAI-1 of the variant t-PA/K296E,R298E,R299E is reduced by a factor of approximately 2800 compared with that of wild type t-PA. In this study, we have significantly extended our earlier observations by identifying t-PA variants that are substantially more resistant to inhibition by PAI-1 than any previously reported variants of t-PA or urokinase-type plasminogen activator. Single-chain t-PA/R275E,R298E, R299E,R304E, for example, is inhibited by PAI-1 approximately 120, 000 times less rapidly than single-chain, wild type t-PA. We also report the first direct comparison of the effects of charge reversal mutations of Arg-298, Arg-299, and/or Arg-304 on the properties of the single- and two-chain forms of t-PA. While these mutations confer extraordinary resistance to inhibition by PAI-1 to both forms of the enzyme, our observations reveal that the single-chain enzyme is affected to a greater extent than the two-chain enzyme. Two-chain, wild type t-PA is inhibited by PAI-1 approximately 1.4 times more rapidly than single-chain t-PA. The corresponding ratio increases to 7.6 or 6.7, respectively, for variants of t-PA containing the R298E, R299E or R298E,R299E,R304E mutations.

Arginine↗
PubMed2005

Expressions of urokinase-type plasminogen activator, its receptor and plasminogen activator inhibitor-1 in gastric cancer cells and effects of Helicobacter pylori.

OBJECTIVE: Destruction of the extracellular matrix is essential for tumor invasion and metastasis. The relationship between Helicobacter pylori (H. pylori) infection and destruction of the extracellular matrix is not yet clear. Urokinase-type plasminogen activator (uPA) plays an important role in the destruction of the extracellular matrix and basement membrane. Urokinase-type plasminogen activator receptor (uPAR) and plasminogen activator inhibitor-1(PAI-1) appear to be associated with these processes. To clarify the role of H. pylori infection in the processes of destruction of the extracellular matrix and basement membrane in cancerous tissue, the effect of H. pylori on the expressions of uPA, uPAR and PAI-1 in cancer cells was investigated. MATERIALS AND METHODS: Gastric cancer cell lines (MKN45, KATO-III) were co-cultured with H. pylori standard strain (NCTC11637), cagA-negative strain and clinical isolated strain. The specific inductions of uPA, uPAR and PAI-1 mRNA were examined by reverse transcription-polymerase chain reaction (RT-PCR) amplification. The secreted uPA antigen was measured by enzyme-linked immunosorbent assay (ELISA). To evaluate the role of transcription factor NF-kappaB in uPA and uPAR gene transcription with H. pylori stimulation, the effect of NF-kappaB inhibitor MG132 on H. pylori-induced uPA and uPAR mRNA expression was examined. RESULTS: The expressions of both uPA and uPAR mRNAs in the gastric cancer cell lines (MKN45 and KATO- III) were increased markedly (uPA mRNA; MKN45: 12-fold, KATO-III: 5-fold) (uPAR mRNA; MKN45: 3-fold, KATO-III: 3-fold) with H. pylori NCTC11637 strain stimulation, whereas the expression levels of uPA and uPAR mRNA did not increase with cagA-negative strain stimulation. These cancer cell lines slightly secreted uPA antigen into the culture medium, and the amount of uPA antigen increased dramatically by stimulation with H. pylori NCTC11637 and cagA-positive clinical isolated strains. These gastric cancer cell lines also slightly secreted PAI-1 antigen into the culture medium, and the amount of PAI-1 antigen was not affected by H. pylori NCTC11637 stimulation. H. pylori-induced uPA and uPAR mRNA expressions were strongly down-regulated by pretreatment with MG132 in both cell lines. CONCLUSIONS: The results of this study indicated the possibility that cagA-positive H. pylori may play an important role not only in tissue remodeling, angiogenesis and wound healing but also in the process of degradation of the extracellular matrix breakdown, tumor invasion and metastasis by inducing uPA and uPAR complex in the gastric cancer cells.

Base Sequence↗
PubMed1987

Mouse ovarian granulosa cells produce urokinase-type plasminogen activator, whereas the corresponding rat cells produce tissue-type plasminogen activator.

It is well established that rat ovarian granulosa cells produce tissue plasminogen activator (tPA). The synthesis and secretion of the enzyme are induced by gonadotropins, and correlate well with the time of follicular rupture in vivo. We have found that in contrast, mouse granulosa cells produce a different form of plasminogen activator, the urokinase-type (uPA). As with tPA synthesis in the rat, uPA production by mouse granulosa cells is induced by gonadotropins, dibutyryl cAMP, and prostaglandin E2. However, dexamethasone, a drug which has no effect on tPA synthesis in rat cells inhibits uPA synthesis in the mouse. Results of these determinations made in cell culture were corroborated by examining follicular fluid, which is secreted in vivo predominantly by granulosa cells, from stimulated rat and mouse ovarian follicles. Rat follicular fluid contained only tPA, and mouse follicular fluid only uPA, indicating that in vivo, granulosa cells from the two species are secreting different enzymes. The difference in the type of plasminogen activator produced by the rat and mouse granulosa cells was confirmed at the messenger RNA level. After hormone stimulation, only tPA mRNA was present in rat cells, whereas only uPA mRNA was found in mouse cells. Furthermore, the regulation of uPA levels in mouse cells occurs via transient modulation of steady-state levels of mRNA, a pattern similar to that seen with tPA in rat cells.

Animals↗