Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many antineoplastic agents alter the reduced glutathione (GSH) status of liver and tumor tissue by inhibiting cellular GSH-linked enzymes. Thus, intracellular GSH plays an important role in a wide variety of antineoplastic interventions regarding therapeutic efficacy and toxicity. Mean GSH values were 0.791 +/- 0.072 mg/m wet weight (ww) and 0.719 +/- 0.047 mg/g ww in gastric cancer tissue and nontumorous glandular mucosa, respectively. Whereas, the average GSH level of normal gastric mucosa was 1.709 +/- 0.135 mg/g, the mean GSH level of normal liver biopsies was 2.378 +/- 0.260 mg/g. The GSH values of normal liver tissue were higher than the hepatocellular GSH concentrations of patients with gastric adenocarcinoma and of another group of tumor-bearing patients who had received chemotherapy preoperatively. These results suggest that the GSH levels of tumor and liver may influence the efficacy and/or toxicity of chemotherapeutic agents.
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PMID:Liver glutathione contents in patients with gastric adenocarcinomas. 232 Dec 74

Roles of oxygen free radicals in recombinant human TNF- and human lymphotoxin (LT)-mediated cytotoxicity have been examined. Nimustine (ACNU), which inhibits glutathione reductase, and buthionine sulphoximine (BSO), an inhibitor of glutathione (GSH) synthesis, were used to modify the steady-state level of intracellular H2O2. TNF-mediated cytotoxicity was augmented when ACNU was added simultaneously to target L cells or Meth A tumor cells. Similar augmented effect was observed when TNF or LT was added to ACNU-treated target cells. However, the addition of GSH nullified the augmentation of TNF-mediated cytotoxicity to ACNU-treated Meth A tumor cells. Meth A tumor cells were pretreated with BSO for 24 hr, and thereafter TNF or LT was added in the presence or the absence of BSO. The cytotoxic effect of TNF and LT was augmented by the treatment of the cell with BSO or simultaneous addition of BSO. High degree of the augmentation was obtained when the pretreatment with BSO and further addition of BSO were combined. These results suggest that oxygen free radicals are closely involved in TNF- and LT-mediated cytotoxicity and the modulation of intracellular GSH level alters the degree of the cytotoxicity of these cytotoxins.
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PMID:[Augmentation of TNF- and lymphotoxin-mediated cytotoxic effect in the combined use of ACNU and involvement of oxygen free radicals]. 232 76

Treatment of confluent cultures of human diploid fibroblasts with 12-O-tetradecanoylphorbol-13-acetate (TPA) (10(-7) M) resulted in a 70% reduction of the glutathione (GSH) content, compared with untreated controls. The effect, which was dose-dependent, was observed 8 h after the beginning of the treatment could be followed for up to 72 h. On the other hand, GSH reduction was specific for confluent cultures, as the level of glutathione remained unchanged by TPA treatment of sparse cultures. The addition of immobilized plasma membrane proteins to sparsely seeded cells has been shown previously to induce cellular reactions which are characteristic for confluent cultures. It was shown that TPA treatment of sparse cultures grown in the presence of immobilized plasma membrane proteins also resulted in a 70% reduction of glutathione content. These data agree with the postulated involvement of redox reactions in tumor promotion, and point to a central role of cell-cell contacts in the regulation of biochemical events which are critical in tumorigenesis.
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PMID:Reduction of glutathione content by 12-O-tetradecanoylphorbol-13-acetate in confluent, but not in sparse cultures of human diploid fibroblasts. 232 9

In the present study we have compared the levels of glutathione (GSH) S-transferase, GSH peroxidase and GSH reductase in human breast tumors and adjacent normal tissues obtained from the same individuals. We have also quantitated GST pi type antigen in these samples by western blotting. GST pi activity towards 1-chloro-2,4-dinitrobenzene was found to be elevated in tumors from three out of six patients (patient nos. 2, 4 and 5), whereas this activity was suppressed in tumor from patient no. 1. Results of Western blotting using antibodies raised against GST pi of human placenta were in agreement with the GST activity data. GSH peroxidase activity with cumene hydroperoxide as substrate was found to be elevated in four tumor samples (patient nos. 2, 4, 5, and 6) but suppressed in tumor from patient no. 1. On the other hand, GSH reductase activity was elevated in three samples (patients nos. 2, 4 and 5) and downregulated in the remaining three samples (patients nos. 1, 3 and 6). These results indicate that GSH-related enzymes are differentially altered in human breast tumors and GST pi type isoenzyme(s), unlike certain other human carcinomas such as colonic, are not uniformly elevated in human breast tumors.
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PMID:Differential expression of glutathione S-transferase, glutathione peroxidase and glutathione reductase in normal and malignant human breast tissues. 233 97

Glutathione-S-transferase (GST) activity and glutathione (GSH) content have been studied in human urinary bladder (UB) specimens obtained from healthy controls (HC) (n = 8) and from patients with superficial transitional cell carcinoma (TCC) (n = 9), either in TCC and in adjacent normal (ANE) tissues of the same patient. The GST activity was significantly higher in TCC in comparison with ANE (ten fold) and with HC (five fold). This activity was also significantly higher in HC than in ANE (two fold). The Km values obtained in the whole population (1.26 +/- 0.3 X 10(-3) mol/l) suggest that a unique form of isoenzyme is present in the UB epithelium and that it is the same acidic form "rho" described in erythrocytes. The GSH content was significantly higher in TCC than in ANE (2.5 fold) and also that in HC (three fold). A good correlation between GST activity and GSH content was observed in HC but not in TCC or ANE. These results demonstrate the relation between the activity of the GST system and the development of the TCC as well as its role in the cellular resistance to chemotherapy. A possible decrease of the GST activity before the development of the tumor is also discussed.
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PMID:Glutathione-S-transferase activity in human superficial transitional cell carcinoma of the bladder. Comparison with healthy controls. 237 71

Mitomycin C (MC) activation to a reactive species was studied in nuclei isolated from rat liver and EMT6 tumor cells. Both preparations were similar in the rate of 4-(p-nitrobenzyl)pyridine (NBP) alkylation by MC and the levels of NADPH-cytochrome P-450 reductase. MC activation by both hepatic and EMT6 cell nuclei was inhibited by the presence of O2 and by heat inactivation. NADPH was preferred over NADH as the source of reducing equivalents by both types of isolated nuclei. MC activation to alkylating metabolites was not affected when EDTA or diethylenetriaminepentaacetic acid, two Fe2+ chelating agents, was present in the incubation system with either preparation of isolated nuclei. Glutathione (1 and 5 mM) and N-acetylcysteine (1 and 10 mM) both inhibited MC alkylation of NBP in nuclear preparations from rat liver and EMT6 tumor cells by 50-60%. Ethylxanthate (1 mM) effectively inhibited the MC alkylation of NBP by hepatic nuclei but was unable to inhibit MC alkylation of NBP by tumor cell nuclei. At 100 mM, ethylxanthate produced a slight stimulation in the rate of MC alkylation of NBP. These data are consistent with the hypothesis that MC activation in EMT6 tumor cells proceeds via a one electron reduction pathway which is inhibitable by glutathione but not inhibitable by ethylxanthate. Hepatic nuclei are apparently able to activate MC by either a one- or two-electron pathway.
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PMID:Effects of glutathione and ethylxanthate on mitomycin C activation by isolated rat hepatic or EMT6 mouse mammary tumor nuclei. 241 96

Cellular glutathione (GSH) levels were found to be 7-fold higher in a human lung adenocarcinoma cell line (A549) than in a normal human lung fibroblast line (CCL-210). Differential modulation of cellular GSH was explored in these cell lines by (a) stimulation of GSH synthesis by oxothiazolidine-4-carboxylate (OTZ) and (b) inhibition of GSH synthesis by buthionine sulfoximine (BSO). In the tumor cell line, OTZ treatment had no effect; however, GSH levels of 140-170% of control were achieved in the normal fibroblast line. With BSO, the normal cell line was depleted of GSH at a faster relative rate than with the tumor line. Within 7 h, 5% GSH remained in the CCL-210 line while approximately 40% GSH remained in the A549 line. Survival response of normal versus tumor cell lines to selected chemotherapy drugs was compared following modulation of GSH levels. OTZ pretreatment of the A549 line provided no protection to a 1-h exposure to melphalan, cisplatin, or bleomycin; however, OTZ pretreatment of CCL-210 elevated GSH and provided protection to melphalan, cisplatin, and bleomycin (protection ratios at 5% survival of 1.2, 1.4, and 1.4, respectively). Neocarzinostatin toxicity in the normal CCL-210 line pretreated with BSO was greatly reduced (protection ratio at 50% survival = 5.0). The same BSO treatment to A549 cells (40% GSH remaining) yielded a similar survival curve to control cells. These studies demonstrate that selective differential chemotherapy responses of normal versus tumor cells is possible by manipulating the GSH synthetic cycle. Should basic phenotypic differences with regard to reductive capacity exist in vivo, such manipulation in GSH levels might yield a therapeutic gain for carefully selected chemotherapy drugs.
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PMID:Selective modulation of glutathione levels in human normal versus tumor cells and subsequent differential response to chemotherapy drugs. 242 85

The in vivo effects of buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) biosynthesis, on the cytotoxicity of cyclophosphamide (CYM), cisplatin (CDDP) and bleomycin (BLM), were examined by monitoring the changes of non-protein thiols (NPSH) in normal tissues and in the NFSa fibrosarcoma. We used the lung colony assay as a measure of tumor response and the spleen colony assay as a measure of normal tissue response to CYM. In this study, 5 mmol/kg of BSO was subcutaneously injected four times every 12 hr before administration of the above anti-neoplastic drugs. GSH levels in subcutaneous NFSa tumors decreased to 2% of the control 12 hr after the last administration of BSO, but in the bone marrow, had recovered to 41%. In the colony assays, BSO increased the anti-cancer effects of the three chemotherapeutic agents, but did not modify the bone marrow suppression by CYM. This finding was a result of the differential response of GSH depletion in the tumor and in the bone marrow. Our study demonstrates that BSO is an effective chemosensitizer of these drugs and may be of therapeutic value when used at an optimal interval.
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PMID:Chemosensitization by buthionine sulfoximine in vivo. 242 90

By sequential use of GSH-affinity chromatography and chromatofocusing, the isoenzymes of glutathione transferase from tumor and non-tumor kidney tissues have been purified and their properties compared. On the basis of electrophoretic mobilities on SDS/polyacrylamide gel, substrate specificities toward the diagnostic substrates cumene hydroperoxide and ethacrynic acid and immunoreactivity with antisera raised against alpha, mu and pi class glutathione transferases, it was found that most of the isoenzymes purified from both tumor and non-tumor kidney can be identified as members of either alpha or pi classes. All the samples investigated lacked mu class glutathione transferase. In addition, we could identify in tumor samples two transferases GST-7.6 and GST-5.8/5.9 which on the basis of immunological properties cannot be related to any of the members of the three major classes of glutathione transferases. The latter do not appear to have corresponding forms in non-tumor tissues. It was suggested that specific transferases can be selectively expressed by tumor kidney carcinoma.
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PMID:Electrophoretic and immunological analysis of glutathione transferase isoenzymes of human kidney carcinoma. 249 96

Five nitroimidazole hypoxic cell radiosensitizers were evaluated in a human lung adenocarcinoma cell line (A549) whose GSH level was 8-fold higher than Chinese hamster V79 cells. One millimolar concentrations of Misonidazole (MISO), SR-2508, RSU-1164, RSU-1172, and Ro-03-8799 sensitized hypoxic A549 cells to radiation, with Ro-03-8799 giving the highest sensitizer enhancement ration (SER) (2.3). However, MISO, SR-2508 and Ro-03-8799 were less effective in this cell line than in V79 cells, presumably due to higher GSH content of the A549 cells. Increased hypoxic radiosensitization was seen with 0.1 mM Ro-03-8799 after GSH depletion by BSO as compared to 0.1 mM Ro-03-8799 alone (SER-1.8 vs 1.3). The combination of GSH depletion and 0.1 mM Ro-03-8799 was considerably more toxic than 0.1 mM or 1.0 mM Ro-03-8799 alone. This sensitivity was much greater than has been observed for SR-2508. These data show that Ro-03-8799 was the most efficient hypoxic cell radiosensitizer in a human tumor cell line considerably higher in GSH than the rodent cell lines often used in hypoxic radiosensitization studies. Thus, Ro-03-8799 may be a more effective hypoxic cell sensitizer in human tumors that are high in GSH.
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PMID:Evaluation of nitroimidazole hypoxic cell radiosensitizers in a human tumor cell line high in intracellular glutathione. 252 17


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