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: KEGG:D00031 (Glutathione)
5,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We measured the glutathione content of a panel of human malignant melanoma cell lines by flow cytometry after staining with mercury orange, using visible light (488 nm) excitation, and compared the values obtained with those measured biochemically using a modified Tietze assay. Glutathione levels were depleted by culturing cells with various concentrations of buthionine sulphoximine to provide a suitable spread of glutathione concentrations. The two assays showed good correlation (r = 0.93). We found a number of technical factors to be critically important. In particular, the conditions of staining, cell number, and method of mixing media, cells and stain were responsible for wide variations in fluorescence intensity. We applied the flow cytometric technique to cell suspensions obtained by fine needle aspiration biopsy of human malignant melanoma deposits, and observed a proportion of cells with high glutathione levels in many samples. The results confirm the feasibility of measuring glutathione content by visible light flow cytometry, and raise the possibility of monitoring glutathione content as an indicator of drug resistance in clinical therapy of human malignant melanoma.
Melanoma Res
PMID:Glutathione content of human malignant melanoma cell lines: correlation of flow cytometric and biochemical assays, and application to human tumour aspirates. 142 88

Glutathione transferases are enzymes implied in the resistance of tumor cells to bifunctional alkylating cytostatic drugs. We have investigated the effect of the glutathione transferase inhibitor by ethacrynic acid on the cytotoxicity of melphalan to a human melanoma cell line (RPMI 8322) with a high level of glutathione transferase activity. Using 1-chloro-2,4-dinitrobenzene as substrate, ethacrynic acid was shown to inhibit the activity of purified human glutathione transferases, with 50% inhibition values of 1, 10, and 15 microM for transferase mu (class mu), transferase epsilon (class alpha) and transferase pi (class pi), respectively, all of which occur in RPMI 8322 cells. Ethacrynic acid at a concentration of 20 microM, which by itself was noncytotoxic, increased the cytotoxicity of melphalan to RPMI 8322 human melanoma cells approximately 2-fold. The induction of DNA interstrand cross-links by 40 microM melphalan was increased 1.4-fold by 30 microM ethacrynic acid. These results indicate that a potentiation of the cytotoxic effect of bifunctional alkylating agents can be achieved by inhibition of glutathione transferase and that the enhanced cytotoxicity may be caused at least in part by increased formation of drug-DNA adducts.
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PMID:Sensitization of human melanoma cells to the cytotoxic effect of melphalan by the glutathione transferase inhibitor ethacrynic acid. 198 11

Exposure of cultured human melanoma cells from three different cell lines to Adriamycin and carmustine at non-cytotoxic (micromolar) concentrations results in a rapid, reversible depletion of cellular glutathione; maximal depletion is achieved within 1 h, and glutathione levels recover within 2-3 h. Glutathione depletion is accompanied by an enhancement of the cytotoxic effects of the alkylating agent melphalan, which ranges from 15- to 55-fold. These results suggest that the combination of Adriamycin and carmustine may provide a rational drug combination for the rapid depletion of glutathione from malignant melanoma, thereby sensitizing these tumor cells to alkylating agent cytotoxicity.
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PMID:Sensitization of human melanoma cells to melphalan cytotoxicity by adriamycin and carmustine. 206 51

A panel of four cell sublines, each selected for resistance to a different antineoplastic agent, has been developed from a human malignant melanoma cell line G3361. Following repeated exposure to escalating doses of the drug of interest, cloned sublines were developed that are 9-fold resistant to cisplatin (G3361/CP), 11-fold resistant to 4-hydroxyperoxy-cyclophosphamide (4-HC) (G3361/HC), 4-fold resistant to carmustine (BCNU) (G3361/BCNU), and 4-fold resistant to melphalan (G3361/PAM). The cross-resistance of each resistant cell line was determined for cisplatin, BCNU, 4-HC, melphalan, carboplatin, nitrogen mustard, and Adriamycin. In general, the alkylating agent-resistant cell lines were specifically resistant to the drug used for selection with the exception of the G3361/CP line, which was greater than 10-fold resistant to the cisplatin analogue carboplatin, 4-fold resistant to 4-HC, and slightly (1.5-fold) resistant to melphalan, and the G3361/BCNU line, which was slightly (1.8-fold) resistant to melphalan. Collateral sensitivity of the G3361/CP, G3361/PAM, and G3361/4HC lines to killing by BCNU was also observed. Glutathione-S-transferase activity was elevated in each of the alkylating agent-resistant cell lines by 3- to 5-fold with chlorodinitrobenzene substrate. On Western blotting, the glutathione-S-transferase-pi (GST-pi) isoenzyme protein was elevated in the resistant cells by 3- to 5-fold. A complementary DNA (pTS4-10) coding for GST-pi has been cloned from a lambda gt11 library, sequenced, and used as a probe to determine the relative levels of GST-pi mRNA in the alkylating agent-resistant cell lines. GST-pi mRNA levels were elevated (8- to 15-fold) in the resistant cell lines, indicating that the GST-pi increases were mediated through an increase in mRNA levels. GST-pi elevations are a frequent event in cells selected for alkylating agent resistance, and in some cases, of multiple drug resistance. However, the lack of cross-resistance among cell lines selected for resistance to different alkylating agents, all of which have elevated GST-pi levels, indicates that increased levels of GST-pi cannot be the predominate mechanism for resistance to the tested drugs in these cell lines.
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PMID:Cross-resistance and glutathione-S-transferase-pi levels among four human melanoma cell lines selected for alkylating agent resistance. 280 68

A method for synthesis of the phaeomelanin pigment intermediate compound 5-S-L-cysteinyl-glycine-L-dopa is presented. This thioether has been suggested as a precursor to 5-S-L-cysteinyl-L-dopa, the key intermediate compound in phaeomelanin pigment formation. 5-S-Glutathione-L-dopa is first synthesized by the tyrosinase-catalyzed reaction between L-dopa and glutathione. The 5-S-glutathione-L-dopa is then converted to 5-S-L-cysteinyl-glycine-L-dopa using the enzyme gamma-glutamyl transpeptidase. The compound thus obtained was suitable as a substrate for melanoma cell and serum dipeptidase which converts the compound into 5-S-L-cysteinyl-L-dopa and glycine. The optimum pH for the dipeptidase from melanoma cells was 7.5 and the Km was 1.2 mM.
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PMID:Synthesis of 5-S-L-cysteinyl-glycine-L-dopa, a natural substrate for serum and melanocyte dipeptidase. 312 Jun 20

The effects of selenium compounds such as sodium selenite, sodium selenate, seleno-DL-cystine and seleno-DL-methionine (100 microM and 10 microM) on B16 and pigmented cloned pB16 murine melanoma cells were investigated in vitro. At the tested concentrations, B16 cells showed a greater sensitivity to the toxic effects of sodium selenite and seleno-DL-cystine than pB16 cells, whereas no decrease of B16 and pB16 cell number was observed after incubation with sodium selenate or seleno-DL-methionine. Glutathione (GSH) percentages were strongly decreased only by selenite and seleno-DL-cystine; it was marked more in B16 than in pB16 cells. The pretreatment of B16 cells with a GSH depleting agent (10 microM buthionine-[S,R]-sulfoximine) did not significantly influence the cytotoxic effects of selenite and seleno-DL-cystine. On both cell populations, GSH preincubation (50 microM) enhanced the cytotoxicity of selenite whereas the survival of seleno-DL-cystine treated cells was increased. Glutathione peroxidase (GSH-Px) activity in B16 cells was more sensitive than in pB16 cells to the activating effect of selenite, and particularly of seleno-DL-cystine: however, cell-free controls indicated that activation was mainly due to glutathione reductase. The rate of 75Se (as sodium selenite) uptake in both cell populations was maximal within the first hour of incubation, with a preferential accumulation in the cytosol; after 24 h of incubation, the amount of 75Se in cytosol and pellet was approximately the same.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of selenium compounds on murine B16 melanoma cells and pigmented cloned pB16 cells. 806 97

Glutathione transferases (GSTs) are enzymes involved in the resistance of tumor cells to bifunctional alkylating cytostatic drugs. We investigated the melphalan sensitivity together with activity and cellular concentration of GST isoenzymes of human melanoma cell line RPMI 8322 in different phases of the cell cycle. By centrifugal elutriation three cell fractions containing different proportions of cells in the G1 phase were isolated. Melphalan sensitivity was estimated by the colony formation assay. The cell fraction with the largest proportion of G1 cells was more sensitive to the drug than the fractions enriched in S and G2 cells. The GST activity of the cell fractions was measured with 1-chloro-2,4-dinitrobenzene (CDNB) as substrate and the concentrations of GST P1-1, GST M1-1 and GST A1-1 were quantitated by use of isoenzyme-specific ELISA. The results show that there were less GST activity and lower GST P1-1 and A1-1 concentrations in the G1 cell enriched fraction, demonstrating a cell cycle dependence of GST expression. Thus, the cell fraction most sensitive to melphalan had the highest proportion of G1 cells and displayed the lowest GST activity, suggesting that the cell cycle dependent sensitivity to melphalan may at least partially depend on the expression of GSTs.
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PMID:Cell cycle dependent sensitivity of human melanoma cells to melphalan is correlated with the activity and cellular concentration of glutathione transferases. 829 55

A proposed mechanism for the melanoma specific activity of phenolic amines is based upon the ability of the enzyme tyrosinase to oxidize these prodrugs to toxic intermediates. In this study, we synthesized an iodinated analog of gamma-L-glutaminyl-4-hydroxybenzene (GHB) with increased antimelanoma activity in both human and murine melanoma cell lines. GHB and gamma-L-glutaminyl-4-hydroxy-3-iodobenzene (I-GHB) were shown to be substrates for both mammalian and mushroom tyrosinase. Glutathione, a cellular antioxidant, inhibited tyrosinase mediated formation of gamma-L-glutaminyl-3,4-benzoquinone (GBQ) from GHB, inhibited melanin production, and blocked the inhibition of the enzyme thymidylate synthase by oxidized GHB. Buthionine sulfoximine (BSO) depletion of cellular glutathione enhanced the growth inhibitory activity and the inhibition of in situ thymidylate synthase by phenolic amines in melanoma cells. GHB and I-GHB were shown to be approximately 5- and 10-fold more cytotoxic, respectively, in highly metastatic B16-BL6 cells than in weakly metastatic B16-F1 cells with approximately equal tyrosinase activity. B16-BL6 cells had approximately 20-fold higher gamma-glutamyltranspeptidase (gamma-GTPase) activity than B16-F1 cells which suggested the possible involvement of this enzyme in the activation of the cytotoxicity of the phenolic amines. 4-Aminophenol, a product of gamma-GTPase reaction with GHB, was a substrate for tyrosinase and a potent inhibitor of in situ thymidylate synthase activity in melanogenic cells. In pigmented melanoma cells containing the enzyme tyrosinase, the quinone mediated mechanism of phenolic amine cytotoxicity may be uniquely important and the cellular antioxidant glutathione essential in the detoxification of these quinone-generated intermediates.
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PMID:Mechanism(s) regulating inhibition of thymidylate synthase and growth by gamma-L-glutaminyl-4-hydroxy-3-iodobenzene, a novel melanin precursor, in melanogenic melanoma cells. 843 97

Glutathione (GSH) performs several important biological functions, including quenching of reactive oxygen species, and protection of cells from toxic compounds such as quinones. The first step in the synthesis of GSH is catalysed by gamma-glutamylcysteine synthetase, an enzyme which is inhibited by cystamine and buthionine sulfoximine (BSO). In this study, we examined the possibility that the effect of hydroquinone (HQ) on pigmentation could be potentiated by inhibiting the production of GSH. In vitro studies using melanoma cell lines demonstrated that both cystamine and BSO could potentiate the inhibitory effects of HQ on tyrosinase activity and melanin content. A synergistic decrease in hair pigmentation was observed when a combination of HQ (2 or 4%) and BSO (5%) was applied to the dorsal skin of C57BL mice. In black hairless guinea-pigs, the application of HQ plus either BSO or cystamine resulted in a significant decrease in epidermal pigmentation when compared with any of the agents alone. The possibility exists that in the future a combination of HQ plus cystamine or BSO could be used to treat disorders such as melasma and post-inflammatory hyperpigmentation.
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PMID:Enhancement of the depigmenting effect of hydroquinone by cystamine and buthionine sulfoximine. 854 87

The aim of this investigation was to test for the scintigraphic detection of metastases of malignant melanoma with a new radiopharmaceutical, 99Tcm-glutathione (99Tcm-GSH), in comparison with 99Tcm-anti-melanoma antibody (99Tcm-AMAb). Glutathione was labelled with 99Tcm by a Sn2+ reduction method with an efficiency of > 99% as determined by instant thin layer chromatography (ITLC). Anti-melanoma antibody was obtained as a kit from SORIN (Italy) and labelled with 99TcmO-4. Forty-three patients with a total of 55 biopsy-proven metastatic melanoma foci, 1 ocular melanoma and 20 benign pathologic foci, also confirmed by ultrasound, computed tomography and magnetic resonance imaging, were included in the study after giving their informed consent. Following the intravenous (i.v.) injection of 500 MBq 99Tcm-AMAb, scintigraphic images of the involved areas were obtained 6 h post-injection. Three days later, the same patients were given 500 MBq 99Tcm-GSH i.v. and images were obtained 6 and 24 h post-injection. The images were classified as positive (focal abnormal accumulation) or negative. Quantitative evaluation was also applied. Regions of interest were drawn over the involved areas and nearby soft tissues and the target-to-nontarget (T/NT) ratios obtained with 99Tcm-AMAb (T/NT: 1.92 +/- 0.2) and 99Tcm-GSH (T/NT: 1.84 +/- 0.2) were compared (0.1 < P < or = 0.3). The sensitivity (and specificity) of 99Tcm-AMAb and 99Tcm-GSH in the detection of malignant melanoma metastases were 91% (95%) and 84% (90%), respectively. Compared with 99Tcm-AMAb, the advantages of 99Tcm-GSH are lower levels of blood radioactivity, lower costs and easy in-house preparation. In conclusion, our results show that 99Tcm-GSH is a potentially useful radiopharmaceutical for the detection of metastases of malignant melanoma.
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PMID:Clinical evaluation of metastases of malignant melanoma imaging with 99Tcm-glutathione and 99Tcm-anti-melanoma antibody: a comparative study. 858 59


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