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 have isolated a multidrug-resistant derivative of Chinese hamster ovary CHO-K1 cells by exposure to progressively increasing concentrations of Adriamycin. This cell line, designated CHO-Adrr, was 27-fold more resistant than the parental line to Adriamycin and showed similar degrees of cross-resistance to several other topoisomerase II (topo II) inhibitors, including mitoxantrone, daunomycin and etoposide. CHO-Adrr cells showed a lower (4-fold) level of cross-resistance to vincristine and colchicine, drugs associated with the multidrug-resistant phenotype. While CHO-Adrr cells showed no enhanced resistance to several mono- and bi-functional alkylating agents or to UV and ionizing radiation, they were greater than 80-fold resistant to mitomycin C (MMC). There was a 5-fold decreased level of daunomycin accumulation in CHO-Adrr cells compared to CHO-K1 cells and this was associated with increased drug efflux. The resistant cells had amplified multidrug resistance gene (mdr) sequences and overexpressed (mdr) mRNA. Verapamil was able to completely reverse Adriamycin resistance but reversal of MMC resistance was only partial, with residual 23-fold resistance. CHO-Adrr cells expressed a 4-fold reduced level of topo II protein but overexpressed an alpha class (basic) glutathione S-transferase (GST). Analysis of cell hybrids showed that while the level of resistance to Adriamycin dropped by a factor of 3 in CHO-K1/CHO-Adrr hybrids compared to CHO-Adrr/CHO-Adrr hybrids, resistance to MMC dropped 10-fold. Thus, CHO-Adrr cells appear to exhibit simultaneously several different drug resistance mechanisms including MDR and GST overexpression, and topo II reduction.
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PMID:Reduced topoisomerase II and elevated alpha class glutathione S-transferase expression in a multidrug resistant CHO cell line highly cross-resistant to mitomycin C. 131 88

Cytotoxicity of Adriamycin on human colon adenocarcinoma cell lines was investigated. Concentrations of Adriamycin producing 50% inhibition were very similar in HT29, Sw480, Sw620, and Sw1116 cells, whereas Caco-2 cells were relatively insensitive. As compared to the Sw1116 cell line, Caco-2 cells were also insensitive to mitoxantrone. Sensitivity to cisplatin, 5-fluorouracil, or ethacrynic acid was comparable in both cell lines. To find the mechanism for this mitoxantrone and Adriamycin resistance, several potential Adriamycin-detoxifying systems were characterized and quantified in both Sw1116 and Caco-2 cells. No dramatic differences in glutathione content and expression of both selenium dependent- and independent glutathione peroxidase, UDP-glucuronyltransferase, and cytochrome P-450 were found. However, highly significant differences in glutathione S-transferase activity were present, the expression of both class pi and class alpha glutathione S-transferases being much higher in the Caco-2 cell line. In addition, a slightly higher content of P-170 glycoprotein was present in the Caco-2 cells. These findings suggest that glutathione S-transferases, and to a lesser extent the P-170 glycoprotein, may be involved in mitoxantrone and Adriamycin resistance of Caco-2 colon carcinoma cells.
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PMID:Biochemical characterization of resistance to mitoxantrone and adriamycin in Caco-2 human colon adenocarcinoma cells: a possible role for glutathione S-transferases. 134 15

The absence of estrogen receptors (ER) in human breast tumors has been associated with a poorer prognosis compared to patients with ER positive breast cancer. Previous studies from our laboratory have shown that a multidrug resistant human breast cancer cell line selected for resistance to Adriamycin (ADR) exhibited markedly increased expression of both the pi class glutathione S-transferase (GST-pi) and the selenium-dependent glutathione peroxidase. These studies also revealed that the ER status was inversely related to the expression of GST-pi in six human breast cancer cell lines and primary tumor specimens. In the present study, we have examined the relationship between ER status and several biological properties of these cells, including their levels of glutathione peroxidase (GSH-Px) and catalase expression, their capacity to generate toxic hydroxyl radicals (degrees OH) by redox cycling of ADR, and their sensitivities to the cytotoxic effects of ADR and the oxidant, H2O2. Our results show that expression of GSH-Px, but not catalase, is inversely related to the ER status in these cell lines. Formation of the degree OH induced by treatment of cells with ADR was inversely proportional to the GSH-Px activity in these cell lines, and thus directly related to the ER status. Sensitivity of these cells to ADR or to H2O2, however, was not consistently related to ER status, GSH-Px, or catalase activity, or to ADR induced degree OH radical formation. These results indicate that these parameters are not predictive of cellular susceptibility to oxidative damage in these cell lines under the conditions studied.
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PMID:Selenium-dependent glutathione peroxidase expression is inversely related to estrogen receptor content of human breast cancer cells. 165 87

In a P-glycoprotein-negative cell line, GLC4-Adr90, a 75-fold acquired Adriamycin (Adr) resistance coincided with a reduced cellular Adr level, an increased detoxifying capacity (glutathione (GSH) and glutathione S-transferase (GST) elevated), and a reduced topoisomerase-II (topo-II) activity compared with the parent cell line GLC4. The effect on Adr resistance of buthionine sulfoximine (BSO, GSH synthesis inhibitor), was studied alone or in combination with verapamil (drug-efflux inhibitor), docosahexaenoic acid (membrane lipid domain affector), ethacrynic acid (GST inhibitor), aphidicolin (DNA-polymerase-alpha inhibitor) or novobiocin (NOV, topo-II inhibitor). Cytotoxicity was tested using a microculture tetrazolium assay. In GLC4-Adr90, BSO and NOV increased Adr-induced cytotoxicity 12.9-fold and 1.8-fold respectively. The combination of BSO plus NOV showed an additive effect, decreasing the Adr resistance factor from 75 to 2.7. Combination of modulators of Adr resistance directed at different resistance mechanisms appears promising in vitro.
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PMID:Combined in vitro modulation of adriamycin resistance. 168 Aug 15

Four human colon cancer cell lines (SW620, LS 180, DLD-I, and HCT-15) and sub-lines isolated in vitro by selection with Adriamycin were studied for reversal of intrinsic and acquired Adriamycin resistance, using buthionine sulfoximine (BSO) to deplete cellular glutathione alone and in combination with the P-glycoprotein antagonist verapamil. GSH levels varied among the parental cell lines but did not increase with resistance. In the parental SW620, DLD-I and HCT-15 and their drug-resistant derivatives, there was no relation between the effect of the glutathione-depleting agent BSO, the mRNA expression of both selenium-dependent glutathione peroxidase (GPx) and glutathione S-transferase pi (GST pi), bulk glutathione S-transferase (GST) activity, and the degree of resistance. However, in LS 180 and its derivative sub-lines, which do not principally rely on P-glycoprotein (Pgp) for Adriamycin resistance, treatment with BSO demonstrated a relatively diminished GSH depletion and enhanced recovery. In comparison with the other acquired cell lines, BSO specifically reversed acquired resistance in the LS 180 Adriamycin-resistant subline (LS 180 Ad150) after short-term drug exposure. Furthermore, the LS 180 Ad150 cells demonstrated an increase in both GPx and GST pi mRNA expression. These observations suggest that glutathione-mediated detoxification of Adriamycin may play a role in the resistance of this sub-line. Verapamil enhanced Adriamycin cytotoxicity 1.2- to 12-fold in the intrinsically resistant cells and as much as 15-fold in cell lines with acquired resistance. Combination of BSO with verapamil resulted in additive, but not synergistic, reversal of resistance. The results underscore the complex nature of Adriamycin resistance, and suggest a role for drug-resistance-modulating agents in the treatment of colon carcinoma.
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PMID:Contribution of glutathione and glutathione-dependent enzymes in the reversal of adriamycin resistance in colon carcinoma cell lines. 168 79

Studies have suggested that the alpha class glutathione S-transferase (GST) may protect cells from the chemotherapeutic drugs chlorambucil and melphalan. In order to further define the function of human alpha class GST, a complementary DNA which encodes it was ligated into an expression vector under the direction of the human metallothionein-IIA promoter and stably transfected into human MCF-7 breast cancer cells in conjunction with the G418-selectable plasmid pSV2neo. Clonal cell lines were identified which expressed increased levels of GST enzyme activity (2.2- to 5.6-fold). The transfected cell lines also had increased peroxidase activity using cumene hydroperoxide as the substrate (1.9- to 3.8-fold) which is consistent with the intrinsic peroxidase activity of alpha class GSTs. Southern blot analysis indicated that genomic DNA from these cells contained a fragment indistinguishable from the transfected alpha class GST complementary DNA (850 base pairs); Northern blot analysis of total cellular RNA indicated that these cells contained appropriately sized alpha class GST RNA (980 nucleotides); and Western blot analysis indicated that, while MCF-7 cells contained no detectable alpha class GST protein, the transfected cells contained markedly elevated levels of alpha class GST but no detectable mu or pi class GST. These alpha class GST transfected cells had increased resistance to ethacrynic acid (2.1- to 3.0-fold). However, the transfected cells failed to show any increased resistance measured at the drug dosage which inhibited 50% of the colony formation to the chemotherapeutic drugs chlorambucil, melphalan, Adriamycin, or cisplatin under conditions of either continuous or 1-h drug exposure. Neither was there any change in sensitivity to the cytotoxins benzo(a)pyrene, benzo(a)pyrene-trans-7,8-dihydrodiol-9,10-epoxide (anti), or 1-chloro-2,4-dinitrobenzene. These studies indicate that expression of this human alpha class GST by itself in MCF-7 human breast cancer cells does not confer resistance to the chemotherapeutic drugs tested under the conditions used in these studies.
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PMID:Antineoplastic drug sensitivity of human MCF-7 breast cancer cells stably transfected with a human alpha class glutathione S-transferase gene. 198 77

The effects of GSH depletion in a human breast cancer cell line and a multi-drug resistant subline (ADRr) were determined in a number of experimental conditions. The ADRr cells contained lower GSH concentration which cannot be explained solely on the basis of differences in cell kinetics, and yet the rate-limiting synthetic enzyme gamma-glutamylcysteine synthetase was increased 2-fold. Inhibition of GSH synthesis by BSO resulted in more rapid and more pronounced GSH depletion in ADRr compared to the wild-type cells, suggesting that enhanced GSH utilization and efflux in the resistant cells account for the lowered basal concentration. In addition, the gamma-glutamyl moiety salvage enzyme gamma-glutamyltranspeptidase was reduced markedly in the ADRr cell line. Since these cells have overexpression of the efflux pump protein P-glycoprotein, we examined the effects on cellular GSH of inhibition of the pump's function by verapamil. We found that verapamil significantly depleted cellular GSH. In a rat mammary carcinoma cell line selected in Adriamycin for multi-drug resistance, a similar molecular phenotype has been described including diminished cellular GSH concentration. Verapamil treatment of these cells also resulted in significant depletion of cellular GSH. These results are consistent with the recent report that combined treatment of BSO and verapamil has an additive effect on cytotoxicity. It is likely that decreased basal GSH concentration is due to oxidation and conjugation of it in reactions catalyzed by the enhanced peroxidase and GST found in these cells.
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PMID:Glutathione depletion in human and in rat multi-drug resistant breast cancer cell lines. 199 9

Many in vitro tumor models have been examined to help understand the precise mechanisms responsible for drug resistance. The importance of these results in vivo remains uncertain. MatB 13762 is a rat mammary adenocarcinoma cell line that can be grown both in vitro and as a solid tumor in Fischer 344 rats, thus permitting the examination of tumor cell drug resistance under both conditions. Two cell lines have been selected in vitro for resistance to Adriamycin (AdrR) and melphalan (MlnR), respectively. Each subline has the following features: AdrR, increased mdr-1 messenger RNA, a high level of cross-resistance to vincristine and atypical low level resistance to melphalan and 1,3-bis(2-chloroethyl)-1-nitrosourea, decreased cellular glutathione content, and increased expression of Yc and Yp glutathione S-transferase isozymes; MlnR, low level drug resistance to melphalan and cross-resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea, Adriamycin, and vincristine; increased cellular concentration of glutathione; elevated glutathione S-transferase activity; and greatly increased messenger RNA specific to the Yc and Yp glutathione-S-transferase subunits. Most of the biochemical and molecular features described above are present but significantly less prominent in tumors grown in vivo. This model provides the opportunity to examine the magnitude of expression and the clinical significance of in vitro resistance in an in vivo model.
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PMID:In vivo and in vitro mechanisms of drug resistance in a rat mammary carcinoma model. 199 82

Rat liver epithelial cells resistant to the growth-inhibitory effects of transforming growth factor beta 1 (TGF-beta 1) were isolated after 3 h exposure to 1.5 micrograms/ml of N-methyl-N'-nitro-N-nitrosoguanidine followed by continuous treatment with 1 ng/ml TGF-beta 1 for 6 weeks. In comparison to the parental or N-methyl-N'-nitro-N-nitrosoguanidine-exposed rat liver epithelial cells (concentration causing 50% inhibition of the rate of DNA synthesis, 0.25 ng/ml), these cells were 10-fold more resistant to the antiproliferative effects of TGF-beta 1 and exhibited resistance to growth inhibition by a highly purified liver-derived growth inhibitor, recombinant human tumor necrosis factor, and transforming growth factor beta 2. Single cell cloning of these resistant cells led to the isolation of a nontransformed clonal cell population (clone 11) which maintained stable resistance in the absence of TGF-beta 1 treatment. Binding of 125I-labeled TGF-beta 1 to rat liver epithelial cells and clone 11 cells was similar. Clone 11 cells exhibited a 5-10-fold resistance to the cytotoxins Adriamycin and vinblastine as assessed by a clonogenic assay. This drug resistance was accompanied by an increase in the steady state levels of the mRNAs for multidrug resistance gene (MDR-1), glutathione S-transferase-P, TGF-beta 1, and c-myc genes. The data presented here suggest an association between resistance to the growth-inhibitory effects of TGF-beta 1- and MDR-1-mediated multidrug resistance.
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PMID:Isolation and characterization of a rat liver epithelial cell line resistant to the antiproliferative effects of transforming growth factor beta (type 1). 211 Dec 9

A subline of the human breast tumor cell line (MCF-7), selected for resistance to Adriamycin and having the multidrug resistance phenotype, also developed significant cross-resistance to mitomycin C and its two analogues, BMY 25282 and BMY 25067. Because mitomycin C and the analogues contain both quinone and aziridine moieties, the mechanism of tumor cell kill is thought to involve alkylation and cross-linking of DNA molecules, hence they are not expected to show cross-resistance to cells selected for resistance to a DNA intercalator. Studies to understand this novel observation show that the resistant MCF-7 cells form significantly less hydroxyl radical and DNA cross-linking in the presence of mitomycin C and BMY 25282 than the sensitive cells. Although BMY 25067 formed less free radicals in the resistant cells, similar to the other two drugs, the formation of DNA cross-links was identical in both cell lines, indicating a somewhat different mechanism of tumor cell kill by this analogue. DNA cross-link formation increased slightly with time in the sensitive cells while there was a small decrease in the resistant cells. This difference in the formation of toxic intermediates appeared to result from enhanced detoxification of reactive species (hydrogen peroxide and alkylating intermediates) as a result of significantly higher glutathione peroxidase (14-fold) and glutathione S-transferase (44-fold) activities in the resistant cell line. These events, i.e., free radical formation and DNA alkylation, showed a good correlation with the cytotoxicity in drug-sensitive cells, indicating that both mechanisms contribute to cell killing of human breast tumor cells.
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PMID:DNA interstrand cross-link and free radical formation in a human multidrug-resistant cell line from mitomycin C and its analogues. 215 43


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