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)

We examined the effect of selective thromboxane A2 (TXA2) receptor antagonists, calcium 5(Z)-1R, 2S, 3S, 4S-7-[3-phenylsulphonylaminobicyclo [2.2.1] hept-2-yl]-5-heptonoate hydrate (S-1452) and +/- -7-(3,5,6,-trimethyl-1,4-benzoquinon-2-yl)-7-phenylhaptanoic acid (AA-2414), on sensitivity to cis-diamminedichloroplatinum (II) (CDDP) in non-small-cell lung cancer cell lines. IC50 values to CDDP using MTT assay were decreased 2.1- and 4.6-fold respectively by treatment with 250 or 500 microM S-1452, for a 2 h simultaneous drug exposure, and those of PC-9/CDDP, a CDDP-resistant cell line, were decreased 3.1- and 6.1-fold. Sensitivity to carboplatin was also enhanced by the treatment with S-1452. IC50 values to CDDP and carboplatin were decreased by treatment with AA-2414 in a dose-dependent manner. Isobologram analysis showed that the combination of CDDP with S-1452 or AA-2414 produced supra-additive or additive effects in each cell line. Neither glutathione content nor glutathione S-transferase activity was changed in either cell line by treatment with 500 microM S-1452. Accumulation of platinum into PC-9 and PC-9/CDDP was increased by the treatment in a dose-dependent manner. Na+, K+-ATPase activity of PC-9 and PC-9/CDDP was enhanced by the treatment of S-1452 in a dose-dependent manner. These data show that the TXA2 receptor antagonists may enhance the sensitivity of non-small-cell lung cancer cell lines to platinum agents. Increase in Na+, K+-ATPase activity induced by S-1452 may be the mechanism of its sensitising effect through increase in platinum accumulation.
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PMID:Modulation of sensitivity to cis-diamminedichloroplatinum (II) by thromboxane A2 receptor antagonists in non-small-cell lung cancer cell lines. 893 34

The reduction of the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to a blue formazan product is widely used for assaying cell survival and proliferation. The reduction reaction is catalyzed by dehydrogenases localized in the mitochondria of viable cells. As part of an analysis of the ability of glutathione S-transferase (GST) enzymes to protect cells from electrophilic compounds, we found extremely high background levels of the formazan product produced by cells that overexpressed the mouse GST P1-1 enzyme. Further analysis with purified GST enzymes confirmed the ability of these enzymes to reduce MTT in vitro. These data suggest that cytotoxicity assays using MTT should be interpreted with caution, especially when studying the effects of compounds that can influence GST expression.
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PMID:Reduction of MTT by glutathione S-transferase. 979 44

In our previous paper we have described the isolation and characterization of a doxorubicin (DOX) resistant subline of breast adenocarcinoma SC6 cells. These cells were obtained after the treatment with low, clinically relevant doses of doxorubicin. They became cross-resistant to different wide used cytostatics. The expression of several genes involved in mitotic signal transduction, as well as cathepsins D and L, was similar in both parental and doxorubicin treated cells. The aim of this study was to examine the molecular mechanisms involved in resistance of these cells to doxorubicin. Activity of plasma membrane Pgp was examined in parental and resistant cells due to rhodamine-accumulation assay. The involvement of glutathione (GSH) and glutathione S-transferase (GST) in resistance to doxorubicin was determined in MTT modified assay due to the addition of specific inhibitors: buthionine sulfoximine (for GSH) or ethacrynic acid (for GST). The kinetic of apoptosis was followed after the treatment with DOX in control and SC6 cells by fluorescent microscope. The occurrence of apoptosis was confirmed by analysing DNA fragmentation in agarose gel. Our results indicate that P-glycoprotein, glutathione or glutathione transferases were not involved in resistance of SC6 cells to doxorubicin. However, the apoptosis was inhibited in doxorubicin-resistant cells. Therefore, even low doses of doxorubicin can induce the resistance to this drug due to inhibition of apoptosis.
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PMID:Inhibition of apoptosis is the cause of resistance to doxorubicin in human breast adenocarcinoma cells. 989 Jun 65

Recent findings suggest that intracellular oxidants are involved in the induction of apoptosis and this type of cell death can be inhibited by various antioxidants. In our accompanying paper, we have shown apoptosis in the villus tip cells of the monkey small intestinal epithelium. The aim of the present study was to evaluate the possible relationship between oxidative stress, antioxidant levels and the apoptotic process in the monkey small intestinal epithelium. Monkey small intestinal epithelial cells were isolated into different fractions consisting of villus, middle and crypt cells. Mitochondrial function was assessed by the reduction of the tetrazolium dye, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), with and without succinate. The extent of lipid peroxidation was assessed by measuring the formation of conjugated diene, depletion of polyunsaturated fatty acids and alpha-tocopherol. Level of antioxidant enzymes like, superoxide dismutase (SOD), catalase, glutathione S-transferase (GST), glutathione peroxidase (GPx) and glutathione reductase were also quantitated in various cell fractions. MTT reduction was significantly decreased in villus cells as compared to the cells from other fractions and this was evident even in presence of the respiratory substrate, succinate. Increased formation of conjugated diene and depletion of polyunsaturated fatty acids were seen in villus and crypt cells as compared to middle fraction cells. The alpha-tocopherol level was decreased in both villus and crypt cells as compared to cells from middle region. Significant decrease of SOD activity was seen in the villus tip cells and a slight decrease was seen in the crypt fractions. Glutathione dependent enzymes like GST, GPx and GSH reductase showed higher activity in the villus fractions. A similar observation was also seen in the catalase activity. This study has shown that although oxidative stress is seen in both villus and crypt cells, decreased mitochondrial function was seen in villus tip cells which may be responsible for apoptotic process in the intestinal epithelium.
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PMID:Apoptotic process in the monkey small intestinal epithelium: 2. Possible role of oxidative stress. 989 35

Expression of three major classes of glutathione S-transferases (GSTs), i.e. alpha, mu and pi class, P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) were studied in childhood acute lymphoblastic leukaemia (ALL), acute myeloid leukaemia (AML) and normal peripheral blood lymphocytes by flow cytometry. In vitro cytotoxicity of 4-hydroxy-ifosfamide (IFOS), daunorubicin (DNR) and prednisolone (PRED) was assessed by the MTT assay. Expression of alpha, mu and pi class GST did not significantly differ between leukaemic cells from 100 initial and 14 unrelated relapse ALL patients (GSTalpha P=026; GSTmu P=O009; GSTpi P=0.13). The expression of GSTalpha (1.4-fold, P=0.0004), GSTpi (13-fold, P = 0001) and to a lesser extent also GSTmu (1.1-fold, P=0.03) was higher in ALL compared with normal peripheral blood lymphocytes. Expression of GSTmu and GST7pi was significantly higher in 18 AML compared with 100 ALL patients at initial diagnosis (respectively 1.3-fold, P=0.0005 and 2-fold, P<0.0001). In contrast, GSTalpha was median 2-fold lower expressed in the AML samples (P< 0.0001). Expression levels of alpha, mu and pi class GSTs were not related to the degree of resistance to IFOS, DNR and PRED nor to immunophenotype, white blood cell count or age at presentation of childhood ALL. One exception was a remarkably low expression of GSTalpha in IFOS-sensitive samples compared with a heterogenous expression in IFOS-resistant samples (P= 0.02). Expression of GSTpi, but not of GSTalpha or GSTmu, weakly correlated with the expression of MRP (Rs 0.36, P = 0.002, n = 74) but not with P-gp. However, a high expression of both GSTpi and MRP was not associated with in vitro resistance to IFOS, DNR or PRED. The present data suggest that expression of GSTs is not linked to the degree of resistance to IFOS, DNR and PRED or clinical risk factors in childhood ALL. Whether the high expression of GSTmu and GSTpi in AML cells contributes to the relative resistance to IFOS, DNR and PRED compared with ALL samples (P < or = 0.0001) warrants further study.
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PMID:Different expression of glutathione S-transferase alpha, mu and pi in childhood acute lymphoblastic and myeloid leukaemia. 1005 Jul 15

The aim of this study was to obtain insight into the role of the multidrug resistance (MDR) phenomenon in hormone-independent progressive prostate cancer. Using immunocytochemistry and Western blotting we determined the expression of P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP), glutathione-S-transferase-pi (GST-pi), Bcl-2, Bax, topoisomerase (Topo) I, II alpha and II beta in the human prostate cancer cell lines PC3, TSU-Pr1, DU145 and LNCaP derivatives LNCaP-R, LNCaP-LNO and LNCaP-FGC. Proliferative activity was assessed by immunocytochemistry. MTT assays were used to determine the sensitivity to etoposide, doxorubicin and vinblastin. Pgp was not expressed in any of the cell lines. MRP was variably expressed. GST-pi was expressed in TSU-Pr1, PC3 and DU145. The expression of Bcl-2 was restricted to TSU-Pr1, whereas Bax was found in all cell lines. Topo II alpha was expressed at the highest level in the rapidly proliferating cell lines TSU-Pr1 and DU145. Topo I and II beta were equally expressed. Resistance profiles varied among the cell lines, with TSU-Pr1 being the most sensitive and LNCaP-LNO relatively resistant. Multiple MDR proteins were expressed in prostate cancer cell lines and may well influence response to chemotherapy. Future functional studies, using chemo-selected MDR models, may further help to determine the mechanism or combination of mechanisms underlying the resistance of prostate cancer to chemotherapy.
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PMID:Chemosensitivity of prostate cancer cell lines and expression of multidrug resistance-related proteins. 1049 44

Hydrogen peroxide was cytotoxic to the small intestine epithelial cell line, IEC-6, as judged from an MTT assay and the release of lactate dehydrogenase. The glutathione S-transferase and thioredoxin reductase activities and SH content decreased dose-dependently with H2O2, but thioredoxin activity increased at low H2O2 concentrations. In addition, the increase in thioredoxin activity was time-dependent during the initial stages of oxidative stress. A reverse transcription-polymerase chain reaction (RT-PCR) amplification also showed that the mRNA content in IEC-6 cells increased time-dependently at 0.25 mM H2O2. These results indicate that cellular oxidative shock causes an increase in the activity of thioredoxin, which is involved in the defense mechanism against oxidative stress.
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PMID:Increase in thioredoxin activity of intestinal epithelial cells mediated by oxidative stress. 1051 9

In order to probe the characteristics of drug resistance and its mechanisms of renal cell carcinoma, drug-resistant spectrum of renal cell carcinoma cell line GRC-1 was detected by in vitro MTT colorimetric assay, the mechanism of drug resistance in GRC-1 was also studied by the methods of both immunocytochemistry assay and flow fluorescence cytometry. The results demonstrated that GRC-1 was cross-resistant to adriamycin, vincrinstine, etoposide and carboplatinium, both mdr1 gene product P-glycoprotein and GST-pi which was an isozyme of glutathione S-transferases were expressed in GRC-1. The accumulation of net intracellular drugs of GRC-1 was less than that of drug sensitive breast cancer cell line MCF7, and the ability of pumping drugs out of cells was higher than that of MCF7. The results suggested that there is an intrinsic multidrug resistance in GRC-1 cell line, and both P-glycoprotein and glutathione systems play a role in the development of drug resistance for GRC-1. GRC-1 is an ideal target cell line for the study of drug resistance.
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PMID:[Drug resistance and its mechanism of intrinsic drug-resistant cell line GRC-1]. 1067 18

Mutations in the beta-amyloid precursor protein (APP) gene cause familial Alzheimer's disease (AD). Although amyloid beta peptide (Abeta) is the principal constituent of senile plaques in AD, other cleavage products of APP are also implicated in playing a role in the pathogenesis of AD. C-terminal fragments of APP (APP-CTs), that contain complete Abeta sequence, are found in neuritic plaques, neurofibrillary tangles and the cytosol of lymphoblastoid cells obtained from AD patients. Our previous report demonstrated that APP-CT105 causes death of differentiated PC12 cells and cultured rat cortical neurons (Kim and Suh [1996] J. Neurochem. 67:1172-1182) and induces strong inward currents in Xenopus oocyte (Fraser et al., [1996] J. Neurochem. 66:2034-2040). In the present study, to investigate which domain of APP-CT105 is responsible for the neurotoxicity, we have made deletion mutants of APP-CT105 without Abeta and transmembrane domain (TM) or without NPTY domain, a putative endocytosis signaling sequence, using the PCR-amplified strategy and the recombinant GST-fusion protein strategy. The effect on cell survival of the deletion mutants of APP-CT105 (8 microM) was then determined by the LDH and MTT assay. We found that C-terminal fragment without NPTY significantly causes cell death in NGF-differentiated PC12 cells and cultured rat cortical neurons. This finding suggests that NPTY may not play an important role in APP-CT105 mediated neurotoxicity. We found, however, that C-terminal fragment without Abeta and TM significantly induces neuronal cell death. Our results suggest that in addition to Abeta, C-terminal fragment of APP without Abeta and TM domain itself may also participate in the neuronal degeneration in AD.
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PMID:APP carboxyl-terminal fragment without or with abeta domain equally induces cytotoxicity in differentiated PC12 cells and cortical neurons. 1079 60

Aflatoxin B(1) (AFB(1)) biotransformation comprises cytochrome P450-mediated reactions resulting in hydroxylated and demethylated metabolites as well as AFB(1) epoxides. As the latter are highly nucleophilic, the species-specific rate of epoxidation and the ability for rapid conjugation to glutathione by glutathione S-transferase determines the individual susceptibility to AFB(1). Here we show the time- and dose-dependent rate of AFB(1)-metabolism in bovine hepatocytes. Aflatoxin M(1) (AFM(1)) is the most prominent metabolite formed within the first 2-8 hr of incubation, whereas AFB(1)-dhd is detectable in medium mainly after a prolonged incubation period. The delayed formation of AFB(1)-dhd corresponds to the cytotoxicity demonstrated by the MTT assay. alpha-Naphthoflavone and ketoconazole, inhibitors of CYP1A and CYP3A, respectively in humans, were used to evaluate the contribution of specific P450 isoenzymes in bovine biotransformation of AFB(1). Initial experiments confirmed that alpha-naphthoflavone and ketoconazole inhibited ethoxyresorufin O-deethylation and testosterone 6beta-hydroxylation also in bovine hepatocytes. Both inhibitors reduced AFM(1) and AFB(1)-dhd formation concentration dependently, suggesting that both enzyme groups contribute to the formation of these metabolites. However, the formation of AFM(1) was less inhibited by both compounds than the formation of AFB(1)-dhd.
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PMID:Cytochrome P450-mediated metabolism and cytotoxicity of aflatoxin B(1) in bovine hepatocytes. 1090 38


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