Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006826 (cancer)
 1,092,456 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intracellular glutathione (GSH) levels for seven mammalian cell lines (four human tumors, two rodent, one monkey) were determined by flow cytometry following staining with monochlorobimane (MBCl), and the results were compared with GSH levels measured by the Tietze assay. The mean fluorescence intensity for all but the two rodent lines did not correlate with GSH levels determined biochemically. Good agreement between the two assays was observed for the rodent lines following depletion of GSH by buthionine sulfoximine, but the level of GSH depletion achieved in the human and monkey lines was always underestimated by MBCl/flow cytometry. These discrepancies were not resolved by increasing stain concentration or staining time. Total glutathione S-transferase (GST) activity and GST isozyme profiles were determined for each of the cell lines. Western analysis with antibodies raised against rat Ya, Yb1, and Yc and human pi isozymes revealed that the rodent cell lines expressed abundant alpha (Ya, Yc subunits) and mu (Yb1 subunits) class isozymes. In contrast, GST-pi was the predominant isozyme detected in the human tumor cell lines and Cos-7 monkey cells. Michaelis-Menten analysis with purified GSTs from rat liver as well as purified human placental (pi) GST revealed that the conjugation of MBCl and GSH catalyzed by the alpha (1-1 and 2-2) and mu (3-3 and 3-4) class GST isozymes was approximately 10 and 80 times more efficient than was conjugation by the GST pi form, respectively. These data indicate that the GST-catalyzed conjugation of GSH and MBCl is isozyme dependent and that MBCl is a relatively poor substrate for the pi isozyme. As a consequence of this isozyme rate differential, the MBCl/flow cytometry technique for GSH quantitation must be applied cautiously, particularly with human tumor cells, many of which have been shown to have high GST-pi activity. Application to other cell types should also be made after careful characterization of GSH levels and GST isozyme composition and only after comparison with other independent assays of GSH concentration.
Cancer Res 1991 Apr 01
PMID:Influence of glutathione S-transferases on cellular glutathione determination by flow cytometry using monochlorobimane. 200 62

To explain the sequence-dependent in vitro cytotoxic synergism between 4-hydroperoxycyclophosphamide (4-HC) and cisplatin in the K-562 human leukemia cell line, we have hypothesized that 4-HC decreases cellular glutathione (GSH) levels and that the resulting diminution of the cellular protective effect of GSH leads to the increased cytotoxicity of cisplatin. Exposure of K-562 cells to 4-HC resulted in a concentration- and time-dependent depletion of cellular GSH. To determine the effect of modulation of GSH levels on the toxicity of cisplatin, K-562 cells were exposed to buthionine sulfoximine (BSO) and/or GSH ethyl esters. Depletion of GSH to approximately 10% of control values by BSO potentiated the cytotoxicity of cisplatin, while rapid replenishment of GSH to within normal levels by GSH esters abolished the potentiation of BSO. Doubling cellular GSH by incubation with GSH esters protected against cisplatin cytotoxicity. Of importance, pretreatment of K-562 cells with BSO, in addition to increasing the cytotoxicity of 4-HC and cisplatin, abolished the synergism between the two drugs. The working hypothesis was also tested in two other cell lines in which the cytotoxic synergism between 4-HC and cisplatin was exhibited: the Raji cell line, a human lymphoblastic cell line, and the L1210-CPA cell line, a subclone of the murine L1210 leukemia with resistance to 4-HC. GSH levels in these two cell lines were not altered by incubation with concentrations of 4-HC at which the synergism was observed. In conclusion, the data for the K-562 cell line, indicating that (a) 4-HC depletes cellular GSH levels, (b) the lowering of cellular GSH levels enhances the toxicity of cisplatin, and (c) intact GSH stores are required for the synergism, strongly support the postulate that the cytotoxic synergism between 4-HC and cisplatin is modulated by GSH levels in this cell line. However, the lack of 4-HC-mediated depletion of GSH at concentrations of 4-HC resulting in cytotoxic synergism in the Raji and L1210-CPA cell line indicates that mechanisms other than modulation of GSH levels by 4-HC are responsible for the synergism in these cells.
Cancer Res 1991 May 15
PMID:Role of glutathione in the in vitro synergism between 4-hydroperoxy-cyclophosphamide and cisplatin in leukemia cell lines. 202 33

The occurrence and persistence of DNA fragmentation, as detected by the alkaline elution technique, have been studied in rats treated with single oral doses of the hepatocarcinogen 2-nitropropane (2-NP). A progressive increase of liver DNA fragmentation was observed at doses ranging from 0.5 to 8 mmol/kg; single strand breaks reached the maximum frequency 6 h after administration, and were partially reduced after 36 h. In contrast, DNA fragmentation was absent in lung, kidney, bone marrow and brain of rats given 8 mmol/kg. The role of cytochrome P-450 in the activation of 2-NP is indicated by the increase of liver DNA damage in rats pretreated with phenobarbital or beta-naphtoflavone, and by its reduction produced by methoxsalen. Both administration of GSH and GSH depletion did not result in clearcut modifications of the genotoxic effect of 2-NP for the liver.
Cancer Lett 1991 Apr
PMID:DNA fragmentation by 2-nitropropane in rat tissues, and effects of the modulation of biotransformation processes. 202 80

Effect of dietary calorie restriction and fat reduction on growth of established mammary carcinoma in rats and on glutathione levels in liver and tumor tissue was investigated. Reduced (GSH) and oxidized (GSSG) glutathione were determined enzymatically. Female Sprague-Dawley rats were injected with 25 mg/kg methylnitrosourea (MNU) on day 50 of life for tumor induction, and subsequently fed a diet containing 50 kcal/day with 45% (energy %) fat. When tumors reached approximately 1 cm3, the diet was changed for 10 +/- 2 weeks. Four dietary groups were formed: two high calorie groups (50 kcal/day) with 45% or 25% fat and two calorie restricted groups (35 kcal/day) with 45% or 25% fat, respectively. Tumor growth was significantly inhibited by the 30% calorie restriction, and the inhibition was most effective in the calorie restricted group with low fat level. However, reduction of fat, alone, had no significant inhibitory effect. GSSG levels in both liver and tumor showed no differences among the groups. Hepatic GSH levels tended to be lower in the calorie-restricted groups, and showed no difference between isocaloric groups with different fat levels. In contrast, GSH in tumor tissue tended to be lower in the low fat groups, independently of calorie levels.
Cancer Lett 1991 May 01
PMID:Effect of dietary calorie and fat restriction on mammary tumor growth and hepatic as well as tumor glutathione in rats. 202 87

Present studies show the in vitro addition of glutathione (GSH) can significantly alter selenite induced growth inhibition of mammary tumor cell line 13 (CMT-13). Preincubation with 100 microM GSH for 24 h partially prevented the growth inhibition caused by 12.6 microM selenite. Pre-incubation with 100 microM GSH for 48 h completely prevented the growth inhibition caused by 12.6 microM selenite. In marked contrast, simultaneous addition of GSH and selenite dramatically increased the severity of selenite-mediated growth inhibition and resulted in cell death. Exposure to selenite (12.6 microM) increased intracellular GSH throughout the 3 day incubation period. Addition of GSH to the medium also led to an approximate 25% increase in intracellular GSH that persisted for 72 h. Cellular retention of selenium following selenite supplementation was decreased up to 70% by GSH preincubation yet increased markedly (greater than or equal to 240%) by the simultaneous addition of GSH and selenite. The rate of selenite uptake was not consistently altered by GSH pretreatment. However, the simultaneous addition of GSH and selenite resulted in a dramatically increased rate of selenium uptake. These data indicate that extracellular GSH can alter the toxicity of supplemental selenite. The protective effect of GSH pre-incubation against selenite toxicity appears to relate to altered selenium retention.
Cancer Lett 1991 May 01
PMID:Influence of supplemental glutathione on selenite-mediated growth inhibition of canine mammary cells. 202 90

Epidemiological and experimental studies suggest that dietary milk products may exert an inhibitory effect on the development of several types of tumors. Some recent experiments in rodents indicate that the antitumor activity of the dairy products is in the protein fraction and more specifically in the whey protein component of milk. We and others have demonstrated that whey protein diets result in increased glutathione (GSH) concentration in a number of tissues, and that some of the beneficial effects of whey protein intake are abrogated by inhibition of GSH synthesis. Whey protein is particularly rich in substrates for GSH synthesis. We suggest that whey protein may be exerting its effect on carcinogenesis by enhancing GSH concentration.
Cancer Lett 1991 May 01
PMID:Whey proteins in cancer prevention. 202 91

The effects of the antioxidants, glutathione (GSH) and its precursor cysteine (Cys) on oxidative damage induced by ferric nitrilotriacetate (Fe-NTA) were examined. Fe-NTA-associated oxidative stress caused the depletion of renal cellular GSH content. Administration of exogenous GSH and Cys suppressed 8-hydroxydeoxyguanosine (8-OH-dG) formation, an indicator of oxidative DNA damage and nephrotoxicity following Fe-NTA treatment. This suggests that generation of free radicals may be causally involved in oxidative lesion generation. Since lipid peroxidation was found to be inhibited only by GSH and not Cys treatment, this suggests that this effect and the DNA damage might be mediated by different pathways. Fe-NTA-associated oxidative stress in renal tubular cells might thus operate via both intracellular and external space modes.
Cancer Lett 1991 Jun 14
PMID:The effects of exogenous glutathione and cysteine on oxidative stress induced by ferric nitrilotriacetate. 204 81

The role of intracellular glutathione (GSH) against the genotoxicity of azathioprine (AZA) was examined by the use of rat hepatocytes and alkaline and neutral elution techniques. Treatment of hepatocytes with AZA for 3 h induced DNA fragmentation in alkaline conditions but not in neutral conditions. A dose-dependent increase in DNA single-strand breaks was observed with the treatment of AZA ranging from 0.3 mM to 1.0 mM with concomitant cytotoxicity. However, neither 6-mercaptopurine, which is a major metabolite of AZA, nor 6-mercaptopurine riboside, an active form of the former, induced the DNA damage at the same concentrations. Moreover, the elution rate of DNA fragmentation, even at low dose of AZA that is not cytotoxic, significantly increased in the presence of buthionine sulfoximine, which is a selective inhibitor of gamma-glutamylcysteine synthetase; i.e., depletion of GSH in hepatocytes enhanced the DNA damage by AZA. Thus, AZA has been proved to be genotoxic, and the genotoxicity is likely to be protected by GSH present in hepatocytes, suggesting that GSH depletion potentiates the carcinogenic effect of AZA.
J Cancer Res Clin Oncol 1991
PMID:Modulation of genotoxicity of azathioprine by intracellular glutathione in hepatocytes. 206 52

To elucidate the mechanism(s) of cisplatin resistance, we have characterized a human non-small cell lung cancer cell line (PC-9/CDDP) selected from the wild type (PC-9) for acquired resistance to cisplatin. PC-9/CDDP demonstrated 28-fold resistance to cisplatin, with cross resistance to other chemotherapeutic drugs including chlorambucil (X 6.3), melphalan (X 3.7) and 3-[(4-amino-2-methyl-5-pyrimidinyl)]methyl-1-(2-chloroethyl)-1-nitros our ea (ACNU) (x 3.9). There was no expression of mdr-1 mRNA in either wild-type or resistant cells. The mRNA and protein levels of glutathione S-transferase (GST) pi were similar in the two lines. A GST-mu isozyme was present in equal amounts and the activities of selenium-dependent and independent glutathione peroxidase and glutathione reductase were unchanged. The mRNA level of human metallothionein IIA and the total intracellular metallothionein levels were reduced in the resistant cells. Significantly increased intracellular glutathione (GSH) levels were found in the resistant cells (20.0 vs 63.5 nmol/mg protein) and manipulation of these levels with buthionine sulfoximine produced a partial sensitization to either cisplatin or chlorambucil. Increased GSH probably also played a role in determining cadmium chloride resistance of the PC-9/CDDP, even though this cell line had a reduced metallothionein level. Also contributing to the cisplatin resistance phenotype was a reduced intracellular level of platinum in the PC-9/CDDP. Thus, at least two distinct mechanisms have been selected in the resistant cells which confer the phenotype and allow degrees of cross resistance to other electrophilic drugs.
Jpn J Cancer Res 1990 May
PMID:Determinants of drug response in a cisplatin-resistant human lung cancer cell line. 211 1

Resistance of a rat ovarian tumor cell line (O-342/DDP) to cisplatin was induced in vitro by stepwise increase of cisplatin concentrations. Both chemosensitive parental cells (O-342) and resistant O-342/DDP cells grow in a monolayer and enter log-phase growth about 24 h after seeding (cell population doubling time in log-phase growth is about 24 h). O-342/DDP cells show a 33-fold resistance to cisplatin as compared to O-342 cells (ID50 = 33 microM in O-342/DDP vs 1 microM in O-342 cells). The intracellular total glutathione (GSH + GSSG) of O-342/DDP cells was twice as high as that of O-342 cells (3.04 vs 1.37 nmol/10(6) cells), while the intracellular GSSG was increased by 26% in O-342/DDP cells compared to O-342 cells. DNA interstrand crosslinks were found to be 8.5 times higher in O-342 cells than in O-342/DDP cells (204 vs 24 rad equiv.), following cisplatin treatment. DNA single-strand breaks were approximately doubled in the sensitive line as compared to the resistant line following exposure to cisplatin. Chromosome analysis uncovered a change in the karyotype of O-342/DDP cell as compared to O-342 cells. In the sensitive line hyperploid (3n) clones, in the resistant line near-diploid clones predominated. Both DL-buthionine-(S,R)-sulfoximine and 3-aminobenzamide were able to sensitize the resistant line towards cisplatin. Thus, the present results suggest that mechanisms for cisplatin resistance in this tumor line apparently are multi-factorial, and include a higher intracellular GSH content and an increased repair activity.
J Cancer Res Clin Oncol 1990
PMID:In vitro investigations on induction and reversal of cisplatin resistance in a rat ovarian tumor cell line. 212 38


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