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)

Several studies have documented that induction of the glucose-related protein (GRP78) is associated with the development of drug-resistance to antitumor drugs. However, nothing has been reported concerning GRP78 in human lung tumors and its relationship to several resistance proteins and angiogenesis. Therefore, this study analyzed the expression of GRP78 in a series of 62 consecutive lung cancer patients and examined whether or not a relationship exists between GRP78, several resistance proteins and microvessel density (MVD). Secondary, it evaluated the relationship of GRP78, LRP56 and GST-pi in cancer cell lines under hypoxic conditions and in sensitive and resistant cell lines. We determined that a relationship exists between GRP78 and the resistance proteins P170, LRP56 and GST-pi in human lung cancer. Furthermore, we observed an up-regulation of GRP78 in the resistant cell lines LUTC-ML54, OAW-Dox and OAW-Tax, but not in sensitive cell lines. Abnormal vascularization of malignant tumors is associated with the development of hypoxic regions. In hypoxic regions, several proteins, including drug resistance proteins, are expressed in greater quantities. Our study detected an inverse correlation between GRP78 and MVD. Carcinomas with low MVD exhibited a higher expression of GRP78. Furthermore, protein expression of GRP78, GST-pi and LRP56 increased in the cell lines A-549, RPMI-2650 and SC-MES-1 under hypoxic conditions. These observations suggest that hypoxia, tumor vascularization and the simultaneous expression of many resistance-related proteins, including GRP78, may play an important role in drug response and therapeutic effectiveness.
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PMID:Glucose-related protein (GRP78) and its relationship to the drug-resistance proteins P170, GST-pi, LRP56 and angiogenesis in non-small cell lung carcinomas. 1062 96

Toxic metals occur naturally at low concentrations throughout the environment, but are found in higher concentrations at many of the hazardous waste sites on the EPA Superfund list. As part of the Agency for Toxic Substances and Disease Registry (ATSDR) mandate to evaluate the toxicity of metals and mixtures, we chose four of the high-priority metal pollutants from ATSDR's HAZDAT list, including arsenic, cadmium, chromium, and lead, to test in a commercially developed assay system, CAT-Tox(L) (Xenometrix). This assay employs a battery of recombinant HepG2 cell lines to test the transcriptional activation capacity of xenobiotics in any of 13 different signal transduction pathways. Our specific aims were to identify metal-responsive promoters and determine whether the pattern of gene expression changed with a mixture of metals. Humic acid was used in all assays as a carrier to help solubilize the metals and, in all cases, the cells were exposed to the humic acid-metal mixture for 48 h. Humic acid alone, at 50-100 microM, showed moderate activation of the XRE promoter, but little other notable activity. As(V), at doses of 50-250 microM, produced a complex profile of activity showing significant dose-dependent induction of the hMTIIA, GST Ya, HSP70, FOS, XRE, NFkappaBRE, GADD153, p53RE, and CRE promoters. Pb(II) showed dose-related induction of the GST Ya, XRE, hMTIIA, GRP78, and CYP IA1 promoters at doses in the range of 12-100 microM. Cd(II), at 1.25-15 microM, yielded significant dose-dependent induction of hMTIIA, XRE, CYP IA1, GST Ya, HSP70, NFkappaBRE, and FOS. Whereas Cr(III) yielded small, though significant inductions of the CRE, FOS, GADD153, and XRE promoters only at the highest dose (750 microM), Cr(VI) produced significant dose-related inductions of the p53RE, FOS, NFkappaBRE, XRE, GADD45, HSP70, and CRE promoters at much lower doses, in the range of 5-10 microM. Assays testing serial dilutions of a mixture comprising 7.5 microM Cd(II), 750 microM Cr(III), and 100 microM Pb(II) (the combination of metals most frequently found at National Priority List sites) showed significant dose-dependent induction of the hMTIIA promoter, but failed to show dose-related induction of any other promoter and showed no evidence of synergistic activation of gene expression by the metals in this mixture. Our results thus show metal activation of gene expression through several previously unreported signal transduction pathways, including As(V) induction of GST Ya, FOS, XRE, NFkBRE, GADD153, p53RE, and CRE; Pb(II) induction of GST Ya, XRE, Cyp IA1, and GADD153; Cd(II) induction of NFkBRE, Cyp IA1, XRE, and GST Ya; and Cr(VI) induction of p53RE, XRE, GADD45, HSP70, and CRE promoters, and thus suggest new insights into the biochemical mechanisms of toxicity and carcinogenicity of metals. It is also an important finding that no evidence of synergistic activity was detected with the mixture of Cd(II), Cr(III), and Pb(II) tested in these assays.
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PMID:Effects of arsenic, cadmium, chromium, and lead on gene expression regulated by a battery of 13 different promoters in recombinant HepG2 cells. 1103 63

Carbaryl and thiabendazole, two widely used pesticides, have been shown to induce cytochrome P450 1A1 (CYP1A1) expression, but neither compound is capable of displacing [3H] 2,3,7,8-tetrachlorodibenzo-P-dioxin from its aryl hydrocarbon receptor binding site. In the present study, we investigated the transcriptional regulation of CYP1A1 as well as other genes in various human hepatoma HepG2 cell lines stably transfected with the chloramphenicol acetyl transferase (CAT) reporter gene and cloned under the control of each of 14 promoters or response elements from relevant stress genes. Carbaryl and thiabendazole were found to activate CYP1A1 at the level of transcription, as demonstrated by the dose-dependent increase in reporter CAT and CYP1A1 mRNAs. Moreover, this effect appeared to be mediated via the xenobiotic responsive element (XRE), because both pesticides specifically activated various fusion constructs containing XRE sequences (CYP1A, glutathione S-transferase, and XRE). Carbaryl and to a lesser extent thiabendazole also activated other stress genes such as c-fos and NF-kappaBRE, HSP70 and GRP78, and GADD153 at a transcriptional level. These data suggest that these molecules induce early alert genes, including those known to be sensitive to oxidative stress. This led us to examine the genotoxic effect of carbaryl and thiabendazole by an in vitro DNA repair solid-phase assay. Both compounds provoked a strong DNA-damaging activity in the human lymphoblastoid cell line that constitutively expresses human CYP1A1 cDNA, but not in the parental line, indicating that CYP1A1 is chiefly implicated in carbaryl and thiabendazole genotoxicity. This effect was confirmed on HepG2 cells. These observations support the notion that intracellular signals leading to CYP1A1 induction, oxidative stress, and genotoxicity are intimately related.
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PMID:Induction of cytochrome P450 1A1 gene expression, oxidative stress, and genotoxicity by carbaryl and thiabendazole in transfected human HepG2 and lymphoblastoid cells. 1122 73

The CAT-Tox (L) assay has recently been developed and validated for detecting and quantifying the specific molecular mechanisms that underlie toxicity of various xenobotic chemicals. We performed this assay to measure the transcriptional responses associated with 2,4,6-trinitrotoluene (TNT) and 2 of its byproducts [2,4 and 2,6-dinitotoluenes (DNTs)] to 13 different recombinant cell lines generated from human liver carcinoma cells (HepG2) by creating stable transfectants of mammalian promoter chloramphenicol acetyltransferase (CAT) gene fusions. Cytoxicity test with the parental HepG2 cells, using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]-based assay for cell viability, yielded LC50 values of 105 +/- 6 mg/mL for TNT in 1% dimethyl sulfoxide (DMSO), and > 300 mg/mL for DNTs, upon 48 h of exposure. TNT appeared to be more toxic than 2,4-DNT, which also showed a higher toxicity compared to 2,6-DNT. Of the 13 recombinant constructs evaluated, 8 (CYP 1A1, GST Ya, XRE, HMTIIA, c-fos, HSP70, GADD153, and GADD45), 5 (c-fos, HSP70, GADD153, GADD45, and GRP78), and none showed inductions to significant levels (p < 0.05), for TNT, 2,4-DNT, and 2,6-DNT, respectively. For most constructs, the induction of stress genes was concentration-dependent. These results show the potential for TNT and 2,4-DNT to cause protein damage and/or perturbations of protein biosynthesis (HSP70 and GRP78), alterations in DNA sequence or its helical structure (c-fos, GADD153, GADD45), and the potential involvement of TNT in the biotransformation process (CYP 1A1, GST Ya, XRE), and in the toxicokinetics of metal ions (HMTIIA). Within the range of concentrations tested (0-300 mg TNT or DNT/mL in 1% DMSO), no significant inductions (p > 0.05) of NFKBRE, p53RE, CRE, and RARE were found.
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PMID:Transcriptional activation of stress genes and cytotoxicity in human liver carcinoma cells (HepG2) exposed to 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and 2,6-dinitrotoluene. 1140 92

Epidemiological studies have shown that there exists some correlation between cadmium exposure and human cancers. The evidence that cadmium and cadmium compounds are probable human carcinogens is also supported by experimental studies reporting induction of malignant tumors formation in multiple species of laboratory animals exposed to these compounds. In vitro studies with mammalian cells have also shown that cadmium is clastogenic, but its mutagenic potential is rather weak. In this research, we performed the MTT assay for cell viability to assess the cytotoxicity of cadmium chloride (CdCl2), and the CAT-Tox (L) assay to measure the induction of stress genes in thirteen different recombinant cell lines generated from human liver carcinoma cells (HepG2), by creating stable transfectants of different mammalian promoter-chloramphenicol acetyltransferase (CAT) gene fusions. Cytotoxicity experiments with the parental cell line yielded a LC50 of 6.1 +/- 0.8 microg/mL, upon 48 h of exposure. Four (metallothionein--HMTIIA, 70-kDa heat shock protein--HSP70, xenobitic response element--XRE, and cyclic adenosine monophosphate response element--CRE) out of the 13 constructs evaluated showed statistically significant inductions (p < 0.05). The induction of these genes was concentration-dependent. Marginal inductions were also recorded for the c-fos, and 153-kDa growth arrest DNA damage (GADD153) promoters, indicating a potential for CdCl2 to damage DNA. However, no significant inductions (p > 0.05) of gene expression were recorded for cytochrome P4501A1--CYP1A1, glutathion-S-transferase Ya subunit--GST Ya, nuclear factor kappa (B site) response element--NFkappaBRE, tumor suppressor protein response element--p53RE, 45-kDa growth arrest DNA damage--GADD45, 78-kDa glucose regulated protein--GRP78, and retinoic acid response element--RARE. As expected, these results indicate that metallothioneins and heat shock proteins appear to be excellent candidates for biomarkers for detecting cadmium-induced proteotoxic effects at the molecular and cellular levels. Induction of XRE indicates the potential involvement of CdCl2 in the biotransformation process in the liver, while activation of CRE indicates stimulation of cellular signaling through the protein kinases pathway.
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PMID:Cytotoxicity and transcriptional activation of stress genes in human liver carcinoma cells (HepG2) exposed to cadmium chloride. 1167 4

Recent studies in our laboratory indicated that arsenic trioxide has the ability to cause significant cytotoxicity, and induction of a significant number of stress genes in human liver carcinoma cells, HepG2. However, similar investigations with atrazine did not show any significant effects of this chemical on HepG2 cells, even at its maximum solubility of 100 microg/mL in 1% dimethyl sulfoxide (DMSO). Further cytogenetic studies were therefore carried out to investigate the combined effects of arsenic trioxide and atrazine on cell viability and gene expression in immortalized human hepatocytes. Cytotoxicity was evaluated using the MTT-assay for cell viability, while the CAT-Tox (L) assay was performed to measure the induction of stress genes in thirteen different recombinant cell lines generated from human liver carcinoma cells (HepG2), by creating stable transfectants of different mammalian promoter-chloramphenicol acetyltransferase (CAT) gene fusions. Cytotoxicity experiments yielded LC50 values of 11.9 +/- 2.6 microg/mL for arsenic trioxide in de-ionized water, and 3.6 +/- 0.4 microg/mL for arsenic trioxide in 100 microg/mL atrazine; indicating a 3 fold increase in arsenic toxicity associated with the atrazine exposure. Co-exposure of HepG2 cells to atrazine also resulted in a significant increase in the potency of arsenic trioxide to upregulate a number of stress genes including those of the glutathione-S-transferase Ya subunit--GST Ya, metallothioneinIIa--HMTIIA, 70-kDa heat shock protein--HSP70, c-fos, 153-kDa growth arrest and DNA damage (GADD153), 45-kDa growth arrest and DNA damage (GADD45), and 78-kDa glucose regulated protein--GRP78 promoters, as well as the xenobiotic response element--XRE, tumor suppressor protein response element--p53RE, cyclic adenosine monophosphate response element--CRE, and retinoic acid response element--RARE. No significant changes were observed with respect to the influence of atrazine on the modulation of cytochrome P450 1A1-CYP 1A1, and nuclear factor kappa (B site) response element--NFkappaBRE by arsenic trioxide. These results indicate that co-exposure to atrazine strongly potentiates arsenic trioxide-induced cytotoxicity and transcriptional activation of stress genes in transformed human hepatocytes.
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PMID:Atrazine potentiation of arsenic trioxide-induced cytotoxicity and gene expression in human liver carcinoma cells (HepG2). 1167 11

The full-length cDNA clone of a novel GRP78-binding protein (GBP) was isolated from rat brain using PCR-selected cDNA subtraction. GBP was predominantly expressed in neuronal cells among various brain tissues. GBP mRNA was already detected in the E12 brain and then gradually increased to reach a peak within P0-2 weeks after birth. GBP expression in the brain decreased age-dependently to approximately 30% of the postnatal level at 12 months. GBP encoded 1021 amino acids and was predicted to have two transmembrane regions and glutamic acid- and proline-rich regions. Because the sequence of GBP offered few clues to the possible function, we performed a GST-tagged GBP pull-down assay in PC12 lysates and identified GRP78, one of the heat shock proteins, as a counterpart. Observation of COS7 cells expressing green fluorescent protein- or Myc-tagged GBP showed that GBP was localized in the endoplasmic reticulum-Golgi domain where BODIPY 558/568 (4,4-difluro-5-(2-thienyl)-4-bora-3alpha,4alpha-diaza-S-indacene)-labeled brefeldin A accumulated. To investigate a biological role for GBP, we established Neuro2a cells stably expressing Myc-tagged GBP. Overexpression of GBP did not affect cell growth or morphological features but attenuated the time-dependent decrease in cell viability caused by serum deprivation compared with control cells. After 48 h of serum starvation, Neuro2a cells overexpressing GBP were resistant to the cell death induced by serum withdrawal. These results suggest that GBP would have a relevant functional role in embryonic and postnatal development of the brain.
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PMID:Cloning and characterization of a novel GRP78-binding protein in the rat brain. 1251 90

Murine hepatic cytochrome P450 2A5 (CYP2A5) is uniquely induced by a variety of agents that cause liver injury and inflammation, conditions that are typically associated with downregulation of P450s. We hypothesized that induction of CYP2A5 occurs in response to hepatocellular damage resulting in endoplasmic reticulum (ER) stress. Treatment of mice in vivo and mouse hepatocytes in primary culture with the CYP2A5 inducer pyrazole resulted in overexpression of the ER stress biomarker glucose-regulated protein (GRP) 78. Treatment of primary hepatocytes with ER stress activators thapsigargin, tunicamycin, and trans-4,5-dihydroxy-1,2-dithiane (DTT(ox)) and the calcium ionophore A23187 (calcimycin) resulted in elevated GRP78 mRNA levels; however, only the reducing agent DTT(ox) induced levels of CYP2A5 mRNA, protein, and coumarin 7-hydroxylase activity. To test the hypothesis that CYP2A5 induction is due to liver injury resulting from altered cellular redox status, we demonstrated that CYP2A5 induction, elevated serum alanine aminotransferase, and oxidative protein damage occur concurrently in pyrazole-treated mice. Pyrazole also induced the expression of cytosolic alpha and mu class glutathione S-transferase expression both in vivo and in primary mouse hepatocytes. Moreover, treatment of hepatocytes with the redox cycling quinone menadione resulted in overexpression of CYP2A5 and GSTM1 mRNA. Finally, pretreatment of hepatocytes with the antioxidants N-acetylcysteine and vitamin E attenuated pyrazole-mediated increases in CYP2A5 mRNA levels. These findings clearly indicate that induction of mouse hepatic CYP2A5 during liver injury occurs via a novel mechanism involving ER stress due to altered cellular redox status.
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PMID:Endoplasmic reticulum stress due to altered cellular redox status positively regulates murine hepatic CYP2A5 expression. 1461 Feb 26

Lead (Pb) and mercury (Hg) are widespread environmental contaminants that induce prominent neural toxicity. Although the brain is not the major Pb and Hg depot in the body, these metals preferentially accumulate in astroglia to exert toxic effects. In this study, we examined the effects of Pb acetate and HgCl(2) on the expression of GRP78, a molecular chaperone in the endoplasmic reticulum (ER) that may provide cytoprotection in response to cellular stresses in the C6 rat glioma cell line. We also evaluated the DNA binding activities of several redox-regulated transcription factors in metal-treated cells. Our results showed that mRNA levels of GRP78 were up-regulated by Pb and Hg at 0.1 and 1 micro M, but down-regulated at higher concentrations (10 micro M). GRP78 protein levels increased in a concentration- and time-dependent manner in Pb and/or Hg-treated cells. Pb increased protein binding to the GST- Upsilon a antioxidant/electrophile response element (ARE/EpRE) and to the NF- kappaB consensus binding sequence of the cytomegalovirus 2 (CMB2) promoter, but decreased protein binding to the Ha-ras ARE/EpRE or to the c-fos 12-O-tetradecanoyl-phorbol-13-acetate (TPA) response element (TRE). In contrast, Hg activated DNA binding by all redox-regulated transcription factors. These studies shed some light on the molecular mechanisms of Pb and Hg toxicity in C6 rat glioma cells and suggest that GRP78 and oxidative stress may participate in the neurotoxic response to these metals.
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PMID:Induction of 78 kD glucose-regulated protein (GRP78) expression and redox-regulated transcription factor activity by lead and mercury in C6 rat glioma cells. 1511 Dec 46

Epithelial cells of the thick ascending limb of Henle's loop (TALH cells) play a major role in the urinary concentrating mechanism. They are normally exposed to variable and often very high osmotic stress, which is particularly due to high sodium and chloride reabsorption and very low water permeability of the luminal membrane. It is already established that elevation of the activity of aldose reductase and hence an increase in intracellular sorbitol are indispensable for the osmotic adaptation and stability of the TALH cells. To identify new molecular factors potentially associated with the osmotic stress-resistant phenotype in kidney cells, TALH cells exhibiting low or high levels of resistance to osmotic stress were characterized using proteomic tools. Two-dimensional gel analysis showed a total number of 40 proteins that were differentially expressed in TALH cells under osmotic stress. Twenty-five proteins were overexpressed, whereas 15 proteins showed a down-regulation. Besides the sorbitol pathway enzyme aldose reductase, whose expression was 15 times increased, many other metabolic enzymes like glutathione S-transferase, malate dehydrogenase, lactate dehydrogenase, alpha enolase, glyceraldehyde-3-phosphate dehydrogenase, and triose-phosphate isomerase were up-regulated. Among the cytoskeleton proteins and cytoskeleton-associated proteins vimentin, cytokeratin, tropomyosin 4, and annexins I, II, and V were up-regulated, whereas tubulin and tropomyosins 1, 2, and 3 were down-regulated. The heat shock proteins alpha-crystallin chain B, HSP70, and HSP90 were found to be overexpressed. In contrast to the results in oxidative stress the endoplasmic reticulum stress proteins like glucose-regulated proteins (GRP78, GRP94, and GRP96), calreticulin, and protein-disulfide isomerase were down-regulated under hypertonic stress.
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PMID:Proteomic analysis of cellular response to osmotic stress in thick ascending limb of Henle's loop (TALH) cells. 1597 15


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