Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glutathione (GSH) levels and glutathione S-transferase (GST) activities were measured in the leukemia cells of 12 patients with chronic lymphocytic leukemia. Both were correlated with prior clinical exposure to alkylating agents and with DNA cross-link formation by chlorambucil in these cells in vitro. No correlation was observed between prior exposure to alkylating agents and GSH level or GST activity. An inverse correlation was observed between GST activity and cross-linking by chlorambucil, which was enhanced if both GST activity and GSH level were related to cross-linking. These findings suggest that the combination of GST and GSH protects the DNA of leukemia cells from chlorambucil, but the role of this combination in clinical resistance remains to be determined.
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PMID:Glutathione S-transferase activity, sulfhydryl group and glutathione levels, and DNA cross-linking activity with chlorambucil in chronic lymphocytic leukemia. 232 47

N,N'-Bis(trans-4-hydroxycyclohexyl)-N'-nitrosourea (BHCNU) is a nitrosourea which has carbamoylating but not alkylating activity. It has been shown to carbamoylate and inactivate glutathione reductase thereby reducing the intracellular levels of glutathione (GSH). Since GSH depletion by buthionine-S,R-sulfoximine potentiates the cytotoxicity of cyclophosphamide, with a corresponding increase in DNA cross-linking, we have investigated the potential interaction between BHCNU and cyclophosphamide. Treatment of K562 human leukemia cells with 15 microM BHCNU for 1 h resulted in depletion of glutathione to 40% of control values, without significant reduction of cell viability. Subsequent treatment with 10 microM 4-hydroperoxycyclophosphamide (4-HC), a self-activating derivative of cyclophosphamide, reduced the level of glutathione to less than 20% of control values. BHCNU pretreatment enhanced the cytotoxicity of 4-HC resulting in a dose modification factor of 2.5. Alkaline elution analysis of cellular DNA demonstrated that the level of interstrand cross-linking was 2-fold higher in GSH-depleted cells than in nondepleted cells, and the induction of single strand breaks was markedly increased. These findings demonstrate that BHCNU potentiates the cytotoxicity of 4-HC and suggest that this is due to the increased formation of DNA interstrand cross-links caused by a reduced intracellular conjugation of 4-HC with glutathione which results in an increased binding of 4-HC to DNA targets.
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PMID:Depletion of cellular glutathione by N,N'-bis(trans-4-hydroxycyclohexyl)-N'-nitrosourea as a determinant of sensitivity of K562 human leukemia cells to 4-hydroperoxycyclophosphamide. 235 56

Correlation between sensitivity to two cross-linking agents, 1-(4-amino-2-methylpyridine-5-yl)-methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU) and cisplatin (DDP), and intracellular glutathione (GSH) level was investigated for two naturally drug-resistant human colon cancer cell lines in comparison with two drug-sensitive human leukemia cell lines. As a result, no appreciable correlation was observed between them. We also studied the possibility that DL-buthionine-S,R-sulfoximine (BSO), an inhibitor of GSH biosynthesis, can sensitize the cancer cells to these anticancer agents via depletion of intracellular GSH. It was found that BSO potentiated ACNU cytotoxicity against human leukemia K562 cells and DDP cytotoxicity against K562 and human colon cancer WiDr cells. It indicates that cancer cells with higher GSH level are more effectively sensitized by BSO regardless of degree of their intrinsic sensitivity to these anticancer agents. These results suggest that intracellular GSH level is not a common mechanism for natural resistance to cross-linking agents in human colon cancer cells but one of the determinants of sensitivity to these anticancer agents of GSH-rich cells.
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PMID:Intracellular glutathione levels in human colon cancer cells naturally resistant to cross-linking agents. 259 79

An important biological function of glutathione (GSH) resides in the detoxication reactions mediated by enzymes such as glutathione-S-transferase (GSTs) and glutathione peroxidase (GPX). An increasing body of evidence implies that GSH and these enzymes play important roles in determining the sensitivity of tumours against cytotoxic drugs like quinone antibiotics, in particular adriamycin (Adr). In the present study, we have analysed the effects of cell-cycle on GSH and GSH-dependent enzymes in an attempt to explain cell-cycle specificity of these antileukaemic drugs which were shown to be involved in free-radical-type reactions. Determination of GSH, GST, GPX and superoxide dismutase in cell-cycle-enriched fractions of five different human myeloid leukaemia cell lines (KG1, K562, U937, ML-1 and ML-2) yielded results identical to those obtained in random cultures, which implies that neither GSH nor GSH-related enzymes are cell-cycle regulated. These findings argue against the presumption that cell-cycle specificity of cytotoxic drugs like Adr could be due to the glutathione-dependent metabolism in myeloid leukaemia cell lines.
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PMID:Influence of cell cycle on glutathione-S-transferase, selenium-dependent glutathione peroxidase, superoxide dismutase and glutathione levels in human myeloid leukaemia cell lines. 276 62

Cell lysates of mouse peritoneal macrophages, in the presence of reduced glutathione, converted leukotriene LTA4 to LTC4, and neither LTD4 nor LTE4 was detected. Therefore, like cultured rat basophilic leukemia cells (RBL cells), the peritoneal macrophage contains LTC4 synthetase and appears to contain little, if any, gamma-glutamyl transpeptidase. When LTA4 was added to subcellular fractions of mouse macrophage lysate, the highest specific activity of LTC4 synthetase (nmol LTC4/mg protein per 10 min) was associated with the particulate or membrane fractions (i.e., 10(4) and 10(5) X g pellets). The 10(5) X g supernatant contains approx. 1% of the specific activity and 6% of the total LTC4 synthetase activity compared with that of the 10(5) X g pellet. Conversely, the 10(5) X g supernatant had four-times more specific activity and 19-times more total GSH S-transferase activity than did the 10(5) X g pellet when evaluated using 1-chloro-2,4-dinitrobenzene (DNCB) as the substrate. LTA4 was converted to LTC4 by the membrane enzyme LTC4 synthetase in a dose-dependent manner at low LTA4 concentrations (3-50 microM) and reached a plateau of approx. 30 microM LTA4 using the macrophage 10(5) X g pellet as an enzyme source. The apparent Km value of LTC4 synthetase for LTA4 was estimated to be 5 microM based on Lineweaver-Burk plots. Enzyme in the 10(5) X g supernatant produced negligible quantities of LTC4 (1% or less of the particulate fractions) over a wide range of LTA4 concentrations. However, an enzyme in the 10(5) X g supernatant fraction presumed to be GSH S-transferase effectively catalyzes the conjugation of glutathione (GSH) with the aromatic compound DNCB. The apparent Km value of GSH S-transferase for DNCB was estimated to be 1.0-1.5 mM. On the other hand, enzyme from the membrane fraction (i.e., 10(5) X g pellet) catalyzed this reaction at a negligible rate over a wide range of DNCB concentrations. The apparent Km value of LTC4 synthetase for GSH was estimated to be 0.36 mM and the corresponding Km value estimated for the glutathione S-transferase was 0.25-0.76 mM. These values indicate similar kinetics for GSH utilization by both enzymes. These Km values are also significantly lower than the intracellular GSH levels of 2 to 5 mM. Therefore, it is suggested that the substrate limiting LTC4 synthetase activity is LTA4 and not GSH. Our results indicate that LTC4 synthetase from mouse peritoneal macrophages is a particulate or membrane-bound enzyme, as was reported by Bach et al.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Characterization of leukotriene C4 synthetase in mouse peritoneal exudate cells. 283 15

Previous studies from this laboratory have established that acquired resistance of murine L1210 leukemia cells to L-phenylalanine mustard (L-PAM) and other alkylating agents is accompanied by a two-to threefold elevation in their glutathione (GSH) concentration (Biochem. Pharm. 31:121). In an attempt to gain insight into the mechanism by which resistant tumor cells maintain their increased GSH content, we have assessed the possible role of gamma-glutamyl transpeptidase (gamma-GT), a membrane bound enzyme involved in GSH metabolism. These results indicate that the enzyme is present in both sensitive and resistant murine L1210 leukemia cells but that the cellular content of gamma-GT is elevated two-to threefold in L-PAM resistant cells as compared to their sensitive counterparts. This elevation in enzymatic activity correlates well with the increased cellular GSH content in resistant cells. The results of a detailed kinetic analysis of gamma-GT activity indicate that there is no difference, between cell types, in the apparent Km of the enzyme for the gamma-glutamyl donor (L-gamma-glutamyl-p-nitroanilide) or the acceptor (glycylglycine). However, the apparent Vmax is increased two-to threefold in L-PAM resistant tumor cells. Investigation into the role of gamma-GT in the extracellular metabolism of GSH indicates that resistant tumor cells metabolize two-fold more GSH than do sensitive cells and that such metabolism results in a similar difference in the intracellular concentration of cysteine. Results of studies with cellular lysates also indicate a role for the enzyme in the supply of cysteine to the glutathione precursor pool of the tumor cell and in the maintenance of elevated GSH concentrations in cells resistant to alkylating agents.
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PMID:gamma-Glutamyl transpeptidase (gamma-GT) and maintenance of thiol pools in tumor cells resistant to alkylating agents. 288 24

We investigated the mechanism of antitumor activity of the water-soluble derivative of menadione, menadione sodium bisulfite (vitamin K3), versus murine leukemia L1210. Vitamin K3, in concentrations greater than 27 microM, caused time- and concentration-dependent depletion of the acid-soluble thiol (GSH) pool. Maximal GSH depletion to 15% of control occurred at 45 microM vitamin K3. Vitamin K3-mediated GSH depletion and vitamin K3-mediated growth inhibition were abrogated by coincubation with 1 mM cysteine or 1 mM reduced glutathione but not by 1 mM ascorbic acid or 180 microM alpha-tocopherol. Low concentrations of vitamin K3 (9-27 microM) elevated both the GSH pool and the total glutathione pool, the latter to a greater degree. Vitamin K3 also caused an increased rate of superoxide anion generation by L1210, maximal at 45 microM vitamin K3 (300% of control), and a concentration-dependent depletion of the reduced nicotinamide adenine dinucleotide phosphate (NADPH) and total nicotinamide adenine dinucleotide phosphate (NADP) pools. Forty-fifty % depletion of the NADPH pool occurred after exposure to 27 microM vitamin K3 and 100% occurred at 36 microM vitamin K3; 27 microM vitamin K3 is a nontoxic concentration of vitamin K3. Loss of NADPH and total NADP was prevented by coincubation with 1 mM cysteine but not by coincubation with ascorbic acid or alpha-tocopherol. We conclude that tumor cell growth inhibition by vitamin K3 is modulated by acid-soluble thiols and may be caused by GSH pool and/or NADPH depletion. Toleration of partial NADPH depletion by L1210 cells may indicate that a threshold level of NADPH loss of greater than 50% is necessary for toxicity. NADPH depletion may be a toxic effect common to quinone drugs. Equitoxic concentrations of vitamin K3, phylloquinone, lapachol, dichlorolapachol, and doxorubicin caused L1210 NADPH pools to deplete to 30 +/- 10 (SD), 60 +/- 10, 60 +/- 11, and 80 +/- 12% of control, respectively. In contrast, GSH depletion may not be a common mechanism of toxicity. Of these quinones, only vitamin K3 caused significant GSH depletion when studied in equitoxic concentrations.
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PMID:Modulation of cytotoxicity of menadione sodium bisulfite versus leukemia L1210 by the acid-soluble thiol pool. 299 58

Red cell pyruvate kinase (PK), pyrimidine 5'nucleotidase (P5N) and reduced glutathione content (GSH) were studied in 126 untreated patients with acute leukaemia (AL, 80 cases), chronic lymphocytic leukaemia (B-CLL, 38 cases) and B-cell lymphoma with leukaemic expression (LSCL, eight cases). Acute leukaemias were classified into lymphoblastic (ALL) and non-lymphoblastic (ANLL), the latter have been further sub-divided into four different variants according to FAB morphological criteria (1976). A significant decrease of PK activity was observed only in the ANLL group, leading to a clear-cut difference with the ALL group where a normal value was obtained. The decrease of P5N activity was similar in all the morphological variants of ANLL and no abnormalities in the low PEP assay system or after fructose 1,6-bisphosphate (Fru 1,6-P2) activation were observed. P5N activity was found to be significantly decreased in all groups of patients except in B-CLL, where it was normal. In regards to the different morphological groups of ANLL, a striking decrease of P5N activity was observed in the M3 variant. Although red cell GSH content was significantly increased in all groups of patients, no correlation was demonstrated between the raised GSH levels and the decreased P5N activities.
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PMID:Characteristics of red cell pyruvate kinase (PK) and pyrimidine 5'nucleotidase (P5N) abnormalities in acute leukaemia and chronic lymphoid diseases with leukaemic expression. 303 59

L1210 leukemia is a murine leukemia which is associated with anemia and marked neutrophilia. In order to determine the significance of free radicals (FR) in this disorder, we determined the presence and localization of free radical scavengers (FRS) and scavenger-like systems in L1210 leukemia cells obtained in vivo and from in vitro cultures. FR are metabolized or detoxified by certain FRS such as glutathione (GSH and GSSG), superoxide dismutase (SOD) and enzymes such as epoxide hydrolase (EH). In all cases specific fractions of L1210 cells, bone marrow and liver were examined for FR/FRS levels. Reduced (GSH) and oxidized (GSSG) glutathione were measured fluorometerically using o-opthalaldehyde (OPT). SOD was determined colorimetrically utilizing pyrogallol by substrate autolysis inhibition, and EH was determined by utilizing [3H] styrene oxide as a substrate. Ratios of GSH/GSSG in fractions prepared from in vivo and in vitro L1210 cells showed a predominance of GSH-reductase with the highest activity in mitochondria (ratio = 15 vs. 10). Normal liver showed a similar pattern whereas, leukemic liver showed altered GSH/GSSG ratios in mitochrondria and microsomes. Leukemic bone marrow showed a predominance of GSH-reductase in all fractions. EH activity was highest in microsomal fractions obtained from L1210 cells grown in vitro and found to become increased in both the mitrochondrial (100%) and microsomal (200%) fractions when cells were exposed to retinoic acid (RA) in culture. SOD activity in the cytosolic (21.2 U SOD/mg) and mitochondrial (12 U SOD/mg) fractions whereas, leukemic liver showed a significant decrease in activity in all fractions compared to normals. SOD was determined in fractions taken from L1210 cells in vivo and in vitro. Results demonstrated detectable but reduced SOD activity in the L1210 cell fractions as contrasted with liver activity. Results from these studies indicate that certain FRS systems are functional in L1210 leukemic animals. Furthermore, variations in the ratios or levels may be of significance in the leukemic and hematological states.
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PMID:The significance of free radicals and free radical scavengers in L1210 leukemia. 322 4

The glutathione (GSH) synthesis inhibitor, buthionine sulfoximine (BSO) was tested for cytotoxicity and thiol depletion in murine and human tumor cells in vitro, and for its antitumor activity and toxicity in vivo. The cell lines used in these studies included murine L-1210 leukemia, human RPMI 8226 myeloma, MCF-7 breast cancer and WiDr colon carcinoma. Soft agar colony forming assays showed that BSO was most effective at reducing tumor colony formation when exposed continuously to cells in vitro. Drug concentrations which inhibited colony formation to 50% of control levels ranged from 2.0-6.2 mM (for 1 hour exposures), 2-100 mM for 24 hour exposures and 0.4-1.40 microM (for continuous BSO exposures). Human myeloma cells proved most sensitive to BSO. In vitro cytotoxicity correlated with depletion of intracellular nonprotein sulfhydryls to less than or equal to 10% of control values in both L-1210 and 8226 cells. This was routinely achieved with prolonged exposures to mM BSO concentrations for greater than 24 hours. Normal mice tolerated high BSO doses (up to 5.0 g/kg) without evidence of acute toxicity. BSO was not active against L-1210 leukemia-bearing DBA/2 mice. When tested in vivo against MOPC-315 plasmacytoma-bearing BALB/c mice, BSO was not active at doses up to 4.0 g/kg. In contrast, the bifunctional alkylating agent melphalan (L-PAM) was active against MOPC-315 and this activity was enhanced by a 24 hour pretreatment of mice with 50 mg/kg of L-BSO.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cytotoxic effects of glutathione synthesis inhibition by L-buthionine-(SR)-sulfoximine on human and murine tumor cells. 358 42


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