Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological inhibitor of both tissue-type and urokinase-type plasminogen activators. The balance between plasminogen activators and PAI-1 plays an important role in several physiological and pathophysiological processes such as atherosclerosis or thrombosis. Because these conditions are associated with hypoxia, it was the aim of the present study to investigate the influence of low O(2) tension on the expression of PAI-1 mRNA and protein using primary cultured rat hepatocytes as a model system. We found that PAI-1 mRNA and protein were induced by mild hypoxia (8% O(2)). The hypoxia-dependent PAI-1 mRNA induction was transcriptionally regulated because it was inhibited by actinomycin D (ActD). Luciferase (LUC) reporter gene constructs driven by about 800 bp of the 5'-flanking region of the rat PAI-1 gene were transiently transfected into primary rat hepatocytes; mild hypoxia caused a 3-fold induction, which was mediated by the PAI-1 promoter region -175/-158 containing 2 putative hypoxia response elements (HRE) binding the hypoxia-inducible factor (HIF-1). Mutation of the HRE-1 (-175/-168) or HRE-2 (-165/-158) also abolished the induction by mild hypoxia. Cotransfection of a HIF-1alpha vector and the PAI-1-LUC constructs, as well as gel shift assays, showed that the HRE-2 of the PAI-1 promoter was most critical for induction by hypoxia and HIF-1 binding. Thus, PAI-1 induction by mild hypoxia via a HIF-1 binding HRE in the rat PAI-1 promoter appears to be the mechanism causing the increase in PAI-1 in many clinical conditions associated with O(2) deficiency.
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PMID:Induction of the plasminogen activator inhibitor-1 gene expression by mild hypoxia via a hypoxia response element binding the hypoxia-inducible factor-1 in rat hepatocytes. 1059 62

Hepatocyte growth factor (HGF), a multifunctional cytokine of mesenchymal origin, activates the DNA binding of hypoxia inducible factor-1 (HIF-1) in the HepG2 cell line: the activated complex contained the inducible alpha subunit. An increased expression of HIF-1alpha (mRNA and nuclear protein levels) was observed. To investigate the molecular basis of the HIF-1 response under this non-hypoxic condition, we evaluated first the expression of putative target genes. We found a time-dependent increase in steady-state mRNA levels of heme oxygenase and urokinase plasminogen activator at 4 h, followed by that of urokinase receptor at 10 h. The enhanced expression of these genes might confer the invasive phenotype, since HGF is a proliferative and scatter factor. Second, we examined some aspects of HIF-1 activity regulation in HGF-treated cells with the following findings: (i) the activation of HIF-1 DNA binding was prevented by proteasome blockade, probably because stabilization of the cytosolic alpha-subunit protein level is not sufficient to generate a functional form: also under these conditions nuclear protein level of HIF-1alpha did not increase; (ii) N-acetylcysteine, a free radical scavenger, strongly decreased HIF-1 activation suggesting a role of reactive oxygen species in this process; (iii) the thiol reducing agent dithiothreitol was ineffective. Third, consistent with these data, N-acetylcysteine reduced the stimulatory effect of HGF on stress kinase activities, while p42/44 mitogen activated kinase (MAPK) was unmodified, suggesting an involvement of c-Jun-N-terminal kinase (JNK) and p38 MAPK in HIF-1 activation. Finally, LY 294002 induced the blockade of phosphatidylinositol 3-kinase (PI3K), one of the principal transducers of HGF/Met receptor signalling, prevented the enhancement of HIF-1 DNA binding and JNK activity, but the inhibition of p42/44 MAPK phosphorylation with PD 98059 was ineffective. In conclusion, we suggest that HGF triggers a signal transduction cascade involving PI3K and ultimately activates HIF-1.
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PMID:Hepatocyte growth factor signalling stimulates hypoxia inducible factor-1 (HIF-1) activity in HepG2 hepatoma cells. 1153 56

Hepatocyte growth factor (HGF) plays an important role in tumor growth and progression also by regulating invasive/metastatic phenotype and angiogenesis. Here we report that a molecular mechanism possibly contributing to these functions of HGF may be hypoxia inducible factor-1 (HIF-1)-dependent expression of genes of the plasminogen activation system. The following findings support this conclusion: (1) HGF enhanced the activity of a luciferase reporter construct under the control of multiple HIF-1 responsive elements (HRE) in HepG2 cells, and the cotransfection of the dominant negative for the beta-subunit (ARNT) prevented this increase; (2) HGF activated uPA and PAI-1 promoters through HIF-1 activity regulated by PI3K/JNK1 transducers, as demonstrated by cotransfection with the reporter gene promoters and the dominant negative for ARNT, p85 subunit of PI3K or JNK1; (3) hypoxia was additive to HGF in increasing reporter vector activities, but probably through different transduction pathways; (4) JNK1 wild-type expression vector increased HIF-1alpha protein expression probably in a phosphorylated state and, thus, functional for transactivating activity; and (5) c-Jun did not seem to be involved in the activation of the luciferase construct containing multiple HREs because it was not prevented by expression of TAM-67, which is the dominant negative mutant form for c-Jun.
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PMID:Hepatocyte growth factor signaling regulates transactivation of genes belonging to the plasminogen activation system via hypoxia inducible factor-1. 1456 96

Cholera toxin (CT) is the causative agent of cholera, binds to GM1 glycosphingolipids, induces the production of cellular cAMP and is also a very powerful mucosal adjuvant. Although the mechanism of the CT induction of cAMP production is well understood, molecular mechanisms of the adjuvanticity of cholera toxin are yet to be delineated. Here, we examined the interaction of CT with human lymphocytes and monocytes by analyzing the host transcriptional profiles using cDNA arrays. The time courses of the transcriptional activations and repressions of affected genes in lymphocytes and monocytes in response to cholera toxin were determined. CT induced the expression of IL-8 and MIP-1 early in the CT exposure. VEGF, TIMP1, HIF-1alpha, MMP11, hek 8, MCP1, IL-6, GCP 2, urokinase plasminogen activator, and TNF-alpha receptor were upregulated after 4h CT treatment. These genes showed increased expression for 48 h. MRP-14, MRP-8A increased expression after 16 h CT treatment. RT-PCR and real-time PCR using cDNA specific primers confirmed the CT induction and repression of selected genes. The results suggest that immunomodulatory genes were among the genes that were affected the most by CT, and induction of these genes may contribute to the CT adjuvanticity.
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PMID:Induction of immunomodulator transcriptional responses by cholera toxin. 1602 26

In human obesity, the stroma vascular fraction (SVF) of white adipose tissue (WAT) is enriched in macrophages. These cells may contribute to low-grade inflammation and to its metabolic complications. Little is known about the effect of weight loss on macrophages and genes involved in macrophage attraction. We examined subcutaneous WAT (scWAT) of 7 lean and 17 morbidly obese subjects before and 3 months after bypass surgery. Immunomorphological changes of the number of scWAT-infiltrating macrophages were evaluated, along with concomitant changes in expression of SVF-overexpressed genes. The number of scWAT-infiltrating macrophages before surgery was higher in obese than in lean subjects (HAM56+/CD68+; 22.6 +/- 4.3 vs. 1.4 +/- 0.6%, P < 0.001). Typical "crowns" of macrophages were observed around adipocytes. Drastic weight loss resulted in a significant decrease in macrophage number (-11.63 +/- 2.3%, P < 0.001), and remaining macrophages stained positive for the anti-inflammatory protein interleukin 10. Genes involved in macrophage attraction (monocyte chemotactic protein [MCP]-1, plasminogen activator urokinase receptor [PLAUR], and colony-stimulating factor [CSF]-3) and hypoxia (hypoxia-inducible factor-1alpha [HIF-1alpha]), expression of which increases in obesity and decreases after surgery, were predominantly expressed in the SVF. We show that improvement of the inflammatory profile after weight loss is related to a reduced number of macrophages in scWAT. MCP-1, PLAUR, CSF-3, and HIF-1alpha may play roles in the attraction of macrophages in scWAT.
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PMID:Reduction of macrophage infiltration and chemoattractant gene expression changes in white adipose tissue of morbidly obese subjects after surgery-induced weight loss. 1604 92

Fibrinolytic factors have an important role in tumor progression through the degradation of extracellular matrix. The increased levels of urokinase-type plasminogen activator (uPA), uPA-receptor (uPAR) and type-1 PA inhibitor (PAI-1) are reported in human renal cell carcinoma (RCC). Connexin (Cx) gene, a member of gap junction, is known to act as a tumor suppressor gene. We have reported that Cx32 improves malignant phenotypes of metastatic RCC cells via the inhibition of Src-dependent signaling. In this study, we examined the effect of expression of Cx32 gene on the production of uPA, uPAR and PAI-1, and on the induction of PAI-1 stimulated by hypoxia in a human metastatic RCC cell line, Caki-1 cells. Cx32 expression decreased both mRNA level and production of PAI-1, uPA and uPAR in Caki-1 cells. Cx32 also decreased hypoxia-inducible factor (HIF)-1alpha and HIF-2alpha mRNA level. PP1, a Src inhibitor, significantly decreased PAI-1, uPA, uPAR and HIF-alpha mRNA levels in Caki-1 cells. Furthermore, Cx32 suppressed the induction of HIF-2alpha protein in Caki-1 cells under hypoxia. PAI-1 mRNA level in Cx32-transfected Caki-1 cells was lower than that of mock transfectant under hypoxic conditions. These results suggest that Cx32 might reduce PAI-1, uPA and uPAR production in metastatic RCC cells via the inhibition of Src-dependent induction of HIF-1alpha and HIF-2alpha gene expression and that Cx32 might suppress hypoxia-inducible gene expression under hypoxic conditions.
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PMID:Connexin 32 down-regulates the fibrinolytic factors in metastatic renal cell carcinoma cells. 1628 36

Hepatocyte growth factor (HGF) receptor Met and hypoxia-inducible factor-1 (HIF-1) signaling pathways are commonly activated in aggressive tumors and promote progression. Since both Met and HIF-1alpha proteins are heat shock protein (Hsp) 90 clients, Hsp90 inhibitors might be expected to positively impact tumor progression. Here, we systematically evaluated the inhibitory effects of the prototypical Hsp90 inhibitor geldanamycin (GA) on cellular processes involved in invasion and angiogenesis in T24 bladder cancer cells stimulated with HGF and chemical hypoxia. First, we demonstrated the positive feedback loop between Met and HIF-1 pathways, which serves to sustain and amplifies their signaling in T24 cells. GA downregulated Met by inhibiting new protein maturation, thereby dampening HGF signaling. HGF and chemical hypoxia with CoCl2 cooperatively promoted in vitro invasion and vascular endothelial growth factor (VEGF) secretion, while CoCl2 but not HGF activated urokinase-type plasminogen activator and matrix metalloproteinase 2, both of which promote invasion and angiogenesis. Low dose GA (100 nmol/L) inhibited these processes by suppressing both HGF and HIF-1 pathways. Notably, brief GA pretreatment inhibited in vitro invasion and VEGF secretion induced by HGF as effectively as did continuous treatment. Moreover, we found that GA inhibited activation of focal adhesion kinase, focal adhesion assembly, and actin reorganization induced by HGF and integrin engagement by extracellular matrix. Thus, GA widely suppresses extrinsic stimuli-induced signaling that contribute to tumor invasion and angiogenesis in this bladder carcinoma model, suggesting the utility of Hsp90 inhibitors in preventing tumor progression and metastasis.
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PMID:Low dose geldanamycin inhibits hepatocyte growth factor and hypoxia-stimulated invasion of cancer cells. 1752 27

Knowledge on interplay between the cardiac molecular response to transplantation-induced stress and primary graft dysfunction (PGD) is limited. A cDNA array identified HIF-1, EGR-1, NAB-2, VEGF-A and uPA as mediators of cardiac tissue response to transplantation-induced stress. mRNA expression of these molecules was measured in left ventricular biopsies from 200 donors before and after aortic cross-clamping and at 10-, 30- and 60-min reperfusion by real-time RT-PCR. HIF-1alpha expression at two time points was significantly associated with PGD, as shown by univariate analysis, receiver operating characteristic curve and multivariate logistic regression. At a cut-off level of 200 arbitrary units, HIF-1alpha after aortic cross-clamping in donors (78% sensitivity, 83% specificity) and at 10-min reperfusion (85% sensitivity, 83% specificity) identified PGD. HIF-1alpha demonstrates the potential to be a predictive marker for PGD; however, as multiple factors were tested at different time points, prospective evaluation is clearly necessary to confirm this observation.
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PMID:Donor myocardial HIF-1alpha is an independent predictor of cardiac allograft dysfunction: a 7-year prospective, exploratory study. 1761 66

The hamster buccal pouch (HBP) carcinogenesis model is one of the most well characterized animal systems for analyzing the development of oral squamous cell carcinoma (OSCC), a common malignancy worldwide. HBP carcinomas that closely mimic human OSCC are useful in understanding the molecular mechanisms of neoplastic transformation. The present study is a comparative evaluation of markers of carcinogen activation, oxidative stress, cell proliferation, apoptosis, invasion, and angiogenesis in human and hamster OSCCs. Enhanced expression of CYP1A1 and CYP1B1 isoforms in both human and hamster oral tumours was associated with significantly increased expression of 8-hydroxy 2-deoxyguanosine (8-OHdG) indicating oxidative DNA damage. Analysis of markers of cell survival and proliferation revealed increased expression of PCNA, GST-P, and NF-kappaB with downregulation of p21, p53 and IkappaB in both human and hamster OSCCs. In addition, both human and hamster oral carcinomas displayed invasive, and angiogenic properties as revealed by dysregulated cytokeratin expression, downregulation of RECK, and increased expression of uPA, MMP-2 and-9, HIF-1alpha, and VEGF. The results reveal aberrant expression of multiple molecules in key signaling pathways in both human OSCCs and HBP carcinomas rendering the HBP model as an important tool for monitoring oral oncogenesis.
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PMID:Of humans and hamsters: a comparative evaluation of carcinogen activation, DNA damage, cell proliferation, apoptosis, invasion, and angiogenesis in oral cancer patients and hamster buccal pouch carcinomas. 1925 Aug 57

We sought to evaluate the molecular markers involved in breast tumorigenesis in a rat model that mimics many essential elements of human breast cancer. Female Sprague-Dawley rats were divided into two groups. Animals in group 1 were given a single dose of 7,12-dimethylbenz[a]anthracene (DMBA) (20 mg/rat) dissolved in 1 ml of sesame oil by intragastric intubation. Group 2 animals received basal diet and served as control. We analyzed DMBA-induced changes in the expression of CYP isoforms (CYP1A1 and 1B1) involved in DMBA metabolism, markers of oxidative stress (4HNE, HEL, and 8-OHdG), cell survival and proliferation (PCNA, NF-kappaB-p50, NF-kappaB-p65, GST-P, and p53), apoptosis (Bcl-2, Bax, caspases, Apaf-1, cytochrome C, and Fas), invasion (uPA, MMP-2, MMP-9, TIMP-2, and RECK), and angiogenesis (VEGF, VEGF-R1, HIF-1alpha, and PLGF) by immunohistochemical localization, Western blot, and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. The present study demonstrates increased carcinogen metabolism, oxidative stress, cell proliferation, together with apoptosis evasion, invasion, metastasis, and neovascularization that may confer a selective growth advantage to DMBA-induced mammary tumors. Aberrant expression of multiple molecules in key signaling pathways in Sprague-Dawley rat mammary tumors renders this model as an important tool for monitoring carcinogenic progression and chemointervention.
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PMID:Evaluation of molecular markers in a rat model of mammary carcinogenesis. 1972 28


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