Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.5.1.18 (glutathione S-transferase)
22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rectal carcinomas of previously untreated patients were analyzed for oxygen status using a computerized polarographic needle electrode histograph. Microvessel density and expression of c-jun, vascular endothelial growth factor (VEGF) and several resistance-related proteins (glutathione S-transferase-pi, GST; thymidylate synthase, TS; metallothioneine, MT) were determined using immunohistochemistry. To examine whether a relationship exists between intratumoral vessel density and tumor oxygenation, microvessel counts were determined in a 400x field using factor-VIII-related antigen and were correlated with the corresponding pO2 values. Linear regression analysis revealed a significant relationship between vessel density and oxygenation status of the tumors. Expression of c-jun, VEGF and resistance-related proteins was correlated with microvessel counts and pO2 values. Significantly lower vessel counts were found in GST- and MT-positive tumors and in tumors with overexpression of c-jun and VEGF than in negative tumors. In addition, significantly lower pO2 values were found in c-jun- and VEGF-positive tumors as well as a tendency for pO2 values to be lower in tumors where MT, GST and TS were expressed. These data show that expression of c-jun, VEGF, and resistance-related proteins is linked with poor vascularization and low oxygenation status in rectal cancer.
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PMID:Association of resistance-related protein expression with poor vascularization and low levels of oxygen in human rectal cancer. 869 May 19

We investigated the utility of examining biological markers to predict chemoresponse and survival. The subjects consisted of 39 unresectable gastric cancer patients treated with a combination of 5-fluorouracil and cis-platinum. The expression of p53, bcl-2, thymidylate synthase (TS), glutathione S-transferase pi (GST-pi), and vascular endothelial growth factor (VEGF) in the formalin-fixed biopsy samples of primary tumors before chemotherapy was examined immunohistochemically. The positive rate for VEGF, bcl-2, TS, p53, and GST-pi was 51, 10, 46, 38, and 69%, respectively. VEGF-positive cases showed a higher response rate than did negative cases (11 of 20 versus 2 of 19 cases; P = 0.0057). The cases that were negative for p53, TS, bcl-2, and GST-pi were more likely to respond to chemotherapy than the cases that were positive for these markers. The 10 cases having 4 or 5 favorable phenotypes (VEGF positive, p53 negative, bcl-2 negative, TS negative, and GST-pi negative) survived longer than the remaining 29 cases (P = 0.0069). Multivariate analysis revealed that the number of favorable phenotypes (> or = 4 versus < or = 3) had a greater impact on survival than performance status (0 versus 1 or 2), age (> 60 years versus < or = 60 years), macroscopic type (scirrhous versus nonscirrhous), histological type (intestinal versus diffuse), or tumor extent (locally advanced versus metastatic). Immunohistochemical examination of biological markers in biopsy samples may be useful in predicting the clinical outcome of unresectable gastric cancer patients treated with 5-fluorouracil and cis-platinum.
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PMID:Biological markers as a predictor for response and prognosis of unresectable gastric cancer patients treated with 5-fluorouracil and cis-platinum. 962 64

When tumors undergo the angiogenic switch, cell growth and tissue invasion is facilitated by the formation of new capillaries from preexisting blood vessels, a process known as angiogenesis. Growth factors such as vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) and fibroblast growth factor (FGF) trigger the process of angiogenesis. Here we describe a protocol for the expression and one-step purification of human recombinant GST-FGF receptor type 1 (FGFR-1) from Sf9 cells. This protocol allows generating an active kinase as indicated by its reactivity with a monoclonal antibody to phosphorylated tyrosine. The purified enzyme displays a specific activity of 1.2 x 10(4) pmol mg(-1) min(-1), which is in the range of activities reported for homogeneously purified recombinant kinases. We have employed a number of compounds to show that the GST-FGFR-1 preparation is suitable to the identification of tyrosine kinase inhibitors. Considering that inhibitors of angiogenesis may represent an attractive tool in therapeutic strategies targeting invasive metastatic tumors the results presented here, along with available data on the structure of the ATP-binding pocket of FGFR-1, should facilitate the rational design of specific FGFR-1 inhibitory compounds.
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PMID:Expression and purification of human recombinant GST-FGF receptor-1. 1122 44

Extracellular Tat protein, the transactivating factor of the human immunodeficiency virus type 1 (HIV-1), modulates gene expression, growth, and angiogenic activity in endothelial cells by interacting with the vascular endothelial growth factor (VEGF) receptor-2 (Flk-1/KDR). Recombinant Tat protein, produced as glutathione-S-transferase chimera (GST-Tat), activates mitogen-activated protein kinase (MAPK) ERK(1/2) in human, murine, and bovine endothelial cells whereas GST is ineffective. In bovine aortic endothelial cells, GST-Tat and the 165 amino acid VEGF isoform (VEGF165) induce transient ERK(1/2) phosphorylation with similar potency and kinetics. The synthetic peptide Tat(41-60), but not peptides Tat(1-21) and Tat(71-86), causes ERK(1/2) phosphorylation, thus implicating Tat/KDR interaction in the activation of this signalling pathway. Accordingly, GST-Tat induces ERK(1/2) phosphorylation in KDR-transfected porcine aortic endothelial cells but not in parental cells. MAPK kinase inhibitors PD098059 and U0126 prevent ERK(1/2) phosphorylation by Tat. However, they do not affect the angiogenic activity exerted by Tat in the murine Matrigel plug and chick embryo chorioallantoic membrane assays. Blocking of MAPK kinase activity impairs instead the angiogenic response to VEGF165 and to fibroblast growth factor-2 (FGF-2). Our data demonstrate that ERK(1/2) activation following the interaction of HIV-1 Tat protein with endothelial cell Flk-1/KDR receptor does not represent an absolute requirement for a full angiogenic response to this growth factor that appears to utilize mechanism(s) at least in part distinct from those triggered by other prototypic angiogenic growth factors.
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PMID:Activation of endothelial cell mitogen activated protein kinase ERK(1/2) by extracellular HIV-1 Tat protein. 1140 52

Hypoxia-inducible factor-1 (HIF-1) is a master transcription factor that controls transcriptional activation of a number of genes responsive to the low cellular oxygen tension, including vascular endothelial growth factor (VEGF), erythropoietin, and glycolytic enzymes. The stability and activity of HIF-1alpha are regulated by binding to various proteins such as pVHL, p53, and p300/CBP. Here, using the yeast two-hybrid screening system, we found that HIF-1alpha interacts with Jab1 (Jun activation domain-binding protein-1), which is a coactivator of AP-1 transcription factor and fifth subunit of COP9 signalosome complex. The interaction of Jab1 with HIF-1alpha was confirmed by GST pull-down assay and also reproduced in vivo in HEK 293 cells, where endogenous Jab1 was coimmunoprecipitated with the overexpressed HIF-1alpha. Moreover, Jab1-enhanced transcriptional activity of HIF-1 under hypoxia led to increase the expression of VEGF, a major HIF-1 target gene. Furthermore, Jab1 increased HIF-1alpha protein levels, which was due to the enhanced HIF-1alpha stability. The binding of HIF-1alpha and p53 tumor suppressor protein, negative regulator of HIF-1alpha stability, was interfered in a Jab1-dependent manner. Taken together, these results indicate that Jab1 should be considered as a novel regulator of HIF-1alpha stability via direct interaction.
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PMID:Jab1 interacts directly with HIF-1alpha and regulates its stability. 1170 26

Protein-protein interactions with the molecular chaperone hsp90 and phosphorylation on serine 1179 by the protein kinase Akt leads to activation of endothelial nitric oxide synthase. However, the interplay between these protein-protein interactions remains to be established. In the present study, we show that vascular endothelial growth factor stimulates the coordinated association of hsp90, Akt, and resultant phosphorylation of eNOS. Characterization of the domains of hsp90 required to bind eNOS, using yeast 2-hybrid, cell-based coprecipitation experiments, and GST-fusion proteins, revealed that the M region of hsp90 interacts with the amino terminus of eNOS and Akt. The addition of purified hsp90 to in vitro kinase assays facilitates Akt-driven phosphorylation of recombinant eNOS protein, but not a short peptide encoding the Akt phosphorylation site, suggesting that hsp90 may function as a scaffold for eNOS and Akt. In vivo, coexpression of adenoviral or the cDNA for hsp90 with eNOS promotes nitric oxide release; an effect eliminated using a catalytically functional phosphorylation mutant of eNOS. These results demonstrate that stimulation of endothelial cells with vascular endothelial growth factor recruits eNOS and Akt to an adjacent region on the same domain of hsp90, thereby facilitating eNOS phosphorylation and enzyme activation.
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PMID:Domain mapping studies reveal that the M domain of hsp90 serves as a molecular scaffold to regulate Akt-dependent phosphorylation of endothelial nitric oxide synthase and NO release. 1198 82

The anti-angiogenic agents angiostatin and endostatin have been shown to affect endothelial cell migration in a number of studies. We have examined the effect of these agents on intracellular signalling pathways known to regulate endothelial cell migration and proliferation/survival. Both agents inhibited fibroblast growth factor (FGF)-, and vascular endothelial growth factor (VEGF)-mediated migration of primary human microvascular endothelial cells and affected vascular formation in the embryoid body model. However, using phosphospecific antibodies we could not detect any effect of angiostatin or endostatin on phospholipase C-gamma (PLC-gamma), Akt/PKB, p44/42 mitogen-activated protein kinase (MAPK), p38 MAPK and p21-activated kinase (PAK) activity. Furthermore, using a glutathione S-transferase (GST)-PAK pull-down assay, we could not detect any effect on Rac activity. We conclude that angiostatin and endostatin inhibit chemotaxis, without affecting intracellular signalling pathways known to regulate endothelial migration and proliferation/survival.
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PMID:Angiostatin and endostatin inhibit endothelial cell migration in response to FGF and VEGF without interfering with specific intracellular signal transduction pathways. 1258 31

We identified vascular endothelial growth factor and type I collagen inducible protein (VCIP), also known as phosphatidic acid phosphatase 2b (PAP2b), in a functional assay of angiogenesis. VCIP/PAP2b exhibits an Arg-Gly-Asp (RGD) cell adhesion sequence. Immunoprecipitation and fluorescence-activated cell sorting analyses demonstrated that VCIP-RGD is exposed to the outside of the cell surface. Retroviral transduction of VCIP induced cell aggregation/cell- cell interactions, modestly increased p120 catenin expression and promoted activation of the Fak, Akt and GSK3beta protein kinases. Furthermore, expression of recombinant VCIP promoted adhesion, spreading and tyrosine phosphorylation of Fak, Shc, Cas and paxillin in endothelial cells. GST-VCIP-RGD, but not GST-VCIP-RGE, specifically interacted with a subset of integrins, and these interactions were effectively blocked by anti-alpha(v)beta(3) and anti-alpha(5)beta(1) integrin antibodies, and by PAP2b/VCIP-derived peptides. Interestingly, PAP2b/VCIP is expressed in close proximity to vascular endothelial growth factor, von Willebrand factor and alpha(v)beta(3) integrin in tumor vasculatures. These findings demonstrate an unexpected function of PAP2b/VCIP, and represent an important step towards understanding the molecular mechanisms by which PAP2b/VCIP-induced cell-cell interactions regulate specific intracellular signaling pathways.
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PMID:Regulation of cell-cell interactions by phosphatidic acid phosphatase 2b/VCIP. 1266 Jan 61

The acute increase in vascular permeability produced by vascular endothelial growth factor (VEGF-A(165)) requires activation of endothelial Flk-1 receptors (VEGFR-2) and stimulation of platelet-activating factor (PAF) synthesis. Like PAF, VEGF-A(165) promotes translocation of P-selectin to the endothelial cell (EC) surface. However, the mechanisms involved remain unknown. By treating human umbilical vein endothelial cells (HUVECs) with VEGF analogs, we show that activation of VEGFR-1 or VEGFR-2 or both induced a rapid and transient translocation of endothelial P-selectin and neutrophil adhesion to activated ECs. The effects mediated by VEGF-A(165) and VEGF-A(121) (VEGFR-1/VEGFR-2 agonists) were blocked by a selective VEGFR-2 inhibitor, SU1498. VEGF-A(165) was twice as potent as VEGF-A(121), which can be explained by the binding capacity of VEGF-A(165) to its coreceptor neuropilin-1 (NRP-1). Indeed, treatment with NRP-1 antagonist (GST-Ex7) reduced the effect of VEGF-A(165) to the levels observed upon stimulation with VEGF-A(121). Finally, the use of selective PAF receptor antagonists reduced VEGF-A(165)-mediated P-selectin translocation. Together, these data show that maximal P-selectin translocation and subsequent neutrophil adhesion was mediated by VEGF-A(165) on the activation of VEGFR-2/NRP-1 complex and required PAF synthesis.
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PMID:VEGF-mediated endothelial P-selectin translocation: role of VEGF receptors and endogenous PAF synthesis. 1476 37

Previous studies have shown that the adaptor protein Shb is involved in receptor tyrosine kinase signaling. In this study, we demonstrate that Shb is phosphorylated in an Src-dependent manner upon vascular endothelial growth factor (VEGF) stimulation using porcine aortic endothelial cells expressing the human VEGF receptor 2 (VEGFR-2) (KDR). In co-immunoprecipitation experiments, we could detect an interaction between Shb and the VEGFR-2 in human telomerase-immortalized microvascular endothelial cells. Furthermore, in a glutathione S-transferase pull-down assay, the Src homology 2 domain of Shb was shown to interact with phosphorylated tyrosine 1175 in the C-terminal tail of VEGFR-2. VEGF-induced Shb phosphorylation was lost in porcine aortic endothelial cells expressing a chimeric murine VEGFR-2 (Flk-1) with a mutation at the corresponding position. Shb expression was specifically decreased by 80%, in a transient manner, by using the short interfering RNA technique. Reduced Shb expression led to a loss of stimulation of phosphatidylinositol 3-kinase, phosphorylation of focal adhesion kinase at tyrosine 576, the generation of focal adhesions, and stress fiber formation in response to VEGF. Furthermore, we show that VEGF-induced migration is inhibited in Shb short interfering RNA-treated cells. Our data demonstrate that Shb is important for VEGF signaling in endothelial cells. This is achieved by Shb binding to tyrosine 1175 in the VEGFR-2, which regulates VEGF-induced formation of focal adhesions and cell migration, of which the latter occurs in a phosphatidylinositol 3-kinase-dependent manner.
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PMID:The adaptor protein shb binds to tyrosine 1175 in vascular endothelial growth factor (VEGF) receptor-2 and regulates VEGF-dependent cellular migration. 1502 17


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