Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.3 (complex I)
 8,901 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The antineoplastic benzanthroquinone drug doxorubicin can undergo flavoenzyme-catalyzed one-electron reduction which, in an aerobic environment, leads to the generation of oxygen-derived species. We therefore sought to determine whether doxorubicin in the presence of NADH dehydrogenase and the transition metal ions Fe(III) or Cu(II) induces DNA base modifications in isolated human chromatin. NADH dehydrogenase-catalyzed reduction of doxorubicin (25-100 microM) caused hydroxyl radical production detected as methane generated from dimethyl sulfoxide; addition of isolated human chromatin to the system produced a concentration-dependent quenching of detectable hydroxyl radical formation. Doxorubicin (5-50 microM)-stimulated enzyme-catalyzed oxidation of NADH was also diminished, but still detectable, in the presence of chromatin. Doxorubicin-induced DNA base modifications in chromatin were measured by gas chromatography/mass spectrometry with selected-ion monitoring. Production of modified bases required the addition of transition metal ion and was enhanced by the addition of active flavoenzyme. The non-redox cycling analogue 5-iminodaunorubicin induced significantly less base modification than did doxorubicin. In the presence of Fe(III), NADH dehydrogenase-catalyzed reduction of doxorubicin caused enhancement in the content of all modified bases over control levels. Substitution of Cu(II) for Fe(III) altered both the degree and the pattern of doxorubicin/NADH dehydrogenase-induced base modifications. The scavengers of hydroxyl radical mannitol and dimethyl sulfoxide or catalase did not significantly affect doxorubicin/NADH/NADH dehydrogenase/transition metal ion-induced base modifications. Superoxide dismutase further enhanced production of all base modifications. The data demonstrate that flavoenzyme-catalyzed redox cycling of doxorubicin generates typical hydroxyl radical-induced base modifications in the DNA of isolated human chromatin, suggesting a possible mechanism for the mutagenicity of doxorubicin in vivo.
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PMID:DNA base modifications induced in isolated human chromatin by NADH dehydrogenase-catalyzed reduction of doxorubicin. 131 97

The quinonoid anthracycline, doxorubicin (Adriamycin) is a potent anti-neoplastic agent whose clinical use is limited by severe cardiotoxicity. Mitochondrial damage is a major component of this cardiotoxicity, and rival oxidative and non-oxidative mechanisms for inactivation of the electron transport chain have been proposed. Using bovine heart submitochondrial preparations (SMP) we have now found that both oxidative and non-oxidative mechanisms occur in vitro, depending solely on the concentration of doxorubicin employed. Redox cycling of doxorubicin by Complex I of the respiratory chain (which generates doxorubicin semiquinone radicals, O2-, H2O2, and .OH) caused a 70% decrease in the Vmax. for NADH dehydrogenase during 15 min incubation of SMP, and an 80% decrease in NADH oxidase activity after 2 h incubation. This inactivation required only 25-50 microM-doxorubicin and represents true oxidative damage, since both NADH (for doxorubicin redox cycling) and oxygen were obligatory participants. The damage appears localized between the NADH dehydrogenase flavin (site of doxorubicin reduction) and iron-sulphur centre N-1. Succinate dehydrogenase, succinate oxidase, and cytochrome c oxidase activities were strongly inhibited by higher doxorubicin concentrations, but this phenomenon did not involve doxorubicin redox cycling (no NADH or oxygen requirement). Doxorubicin concentrations of 0.5 mM were required for 50% decreases in these activities, except for cytochrome c oxidase which was only 30% inhibited following incubation with even 1.0 mM-doxorubicin. Our results indicate that low concentrations of doxorubicin (50 microM or less) can catalyse a site-specific oxidative damage to the NADH oxidation pathway. In contrast, ten-fold higher doxorubicin concentrations (or more) are required for non-oxidative inactivation of the electron transport chain; probably via binding to cardiolipin and/or generalized membrane chaotropic effects. The development of agents to block doxorubicin toxicity in vivo will clearly require detailed clinical studies of doxorubicin uptake in the heart.
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PMID:Oxidative and non-oxidative mechanisms in the inactivation of cardiac mitochondrial electron transport chain components by doxorubicin. 271 42

In the present study we have used beef heart submitochondrial preparations (BH-SMP) to demonstrate that a component of mitochondrial Complex I, probably the NADH dehydrogenase flavin, is the mitochondrial site of anthracycline reduction. During forward electron transport, the anthracyclines doxorubicin (Adriamycin) and daunorubicin acted as one-electron acceptors for BH-SMP (i.e. were reduced to semiquinone radical species) only when NADH was used as substrate; succinate and ascorbate were without effect. Inhibitor experiments (rotenone, amytal, piericidin A) indicated that the anthracycline reduction site lies on the substrate side of ubiquinone. Doxorubicin and daunorubicin semiquinone radicals were readily detected by ESR spectroscopy. Doxorubicin and daunorubicin semiquinone radicals (g congruent to 2.004, signal width congruent to 4.5 G) reacted avidly with molecular oxygen, presumably to produce O2-, to complete the redox cycle. The identification of Complex I as the site of anthracycline reduction was confirmed by studies of ATP-energized reverse electron transport using succinate or ascorbate as substrates, in the presence of antimycin A or KCN respiratory blocks. Doxorubicin and daunorubicin inhibited the reduction of NAD+ to NADH during reverse electron transport. Furthermore, during reverse electron transport in the absence of added NAD+, doxorubicin and daunorubicin addition caused oxygen consumption due to reduction of molecular oxygen (to O2-) by the anthracycline semiquinone radicals. With succinate as electron source both thenoyltrifluoroacetone (an inhibitor of Complex II) and rotenone blocked oxygen consumption, but with ascorbate as electron source only rotenone was an effective inhibitor. NADH oxidation by doxorubicin during BH-SMP forward electron transport had a KM of 99 microM and a Vmax of 30 nmol X min-1 X mg-1 (at pH 7.4 and 23 degrees C); values for daunorubicin were 71 microM and 37 nmol X min-1 X mg-1. Oxygen consumption at pH 7.2 and 37 degrees C exhibited KM values of 65 microM for doxorubicin and 47 microM for daunorubicin, and Vmax values of 116 nmol X min-1 X mg-1 for doxorubicin and 114 nmol X min-1 X mg-1 for daunorubicin. In marked contrast with these results, 5-iminodaunodrubicin (a new anthracycline with diminished cardiotoxic potential) exhibited little or no tendency to undergo reduction, or to redox cycle with BH-SMP. Redox cycling of anthracyclines by mitochondrial NADH dehydrogenase is shown, in the accompanying paper (Doroshow, J. H., and Davies, K. J. A. (1986) J. Biol. Chem. 261, 3068-3074), to generate O2-, H2O2, and OH which may underlie the cardiotoxicity of these antitumor agents.
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PMID:Redox cycling of anthracyclines by cardiac mitochondria. I. Anthracycline radical formation by NADH dehydrogenase. 345 45

This investigation examined the effect of the anthracycline antitumor agents on reactive oxygen metabolism in rat heart. Oxygen radical production by doxorubicin, daunorubicin, and various anthracycline analogues was determined in heart homogenate, sarcoplasmic reticulum, mitochondria, and cytosol, the major sites of cardiac damage by the anthracycline drugs. Superoxide production in heart sarcosomes was significantly increased by anthracycline treatment; for doxorubicin, the reaction appeared to follow saturation kinetics with an apparent Km of 112.62 microM, required NADPH as cofactor, was accompanied by the accumulation of hydrogen peroxide, and probably resulted from the transfer of electrons to molecular oxygen by the doxorubicin semiquinone after reduction of the drug by sarcosomal NADPH:cytochrome P-450 reductase (NADPH:ferricytochrome oxidoreductase, EC 1.6.2.4). Superoxide formation was also significantly enhanced by the anthracycline antibiotics in the mitochondrial fraction. Doxorubicin stimulated mitochondrial superoxide formation in a dose-dependent manner that also appeared to follow saturation kinetics (apparent Km of 454.55 microM); however, drug-related superoxide production by mitochondria required NADH rather than NADPH and was significantly increased in the presence of rotenone, which suggested that the proximal portion of the mitochondrial NADH dehydrogenase complex [NADH:(acceptor) oxidoreductase, EC 1.6.99.3] was responsible for the reduction of doxorubicin at this site. In heart cytosol, anthracycline-induced superoxide formation and oxygen consumption required NADH and were significantly reduced by allopurinol, a potent inhibitor of xanthine oxidase (xanthine:oxygen oxidoreductase, EC 1.2.3.2). Reactive oxygen production was detected in all of our studies despite the presence of both superoxide dismutase (superoxide:superoxide oxidoreductase, EC 1.15.1.1) and glutathione peroxidase (glutathione:hydrogen peroxide oxidoreductase, EC 1.11.1.9) in each cardiac fraction. These results suggest that free radical formation by the anthracycline antitumor agents, which occurs in the same myocardial compartments that are subject to drug-induced tissue injury, may damage the heart by exceeding the oxygen radical detoxifying capacity of cardiac mitochondria and sarcoplasmic reticulum.
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PMID:Effect of anthracycline antibiotics on oxygen radical formation in rat heart. 629 97

Doxorubicin (DOX) is a broad spectrum anthracycline antibiotic used to treat a variety of cancers. Redox activation of DOX to form reactive oxygen species has been implicated in DOX-induced cardiotoxicity. In this work we investigated DOX-induced apoptosis in cultured bovine aortic endothelial cells and cardiomyocytes isolated from adult rat heart. Exposure of bovine aortic endothelial cells or myocytes to submicromolar levels of DOX induced significant apoptosis as measured by DNA fragmentation and terminal deoxynucleotidyltransferase-mediated nick-end labeling assays. Pretreatment of cells with 100 microm nitrone spin traps, N-tert-butyl-alpha-phenylnitrone (PBN) or alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) dramatically inhibited DOX-induced apoptosis. Ebselen (20-50 microm), a glutathione peroxidase mimetic, also significantly inhibited apoptosis. DOX (0.5-1 microm) inactivated mitochondrial complex I by a superoxide-dependent mechanism. PBN (100 microm), POBN (100 microm), and ebselen (50 microm) restored complex I activity. These compounds also inhibited DOX-induced caspase-3 activation and cytochrome c release. PBN and ebselen also restored glutathione levels in DOX-treated cells. We conclude that nitrone spin traps and ebselen inhibit the DOX-induced apoptotic signaling mechanism and that this antiapoptotic mechanism may be linked in part to the inhibition in formation or scavenging of hydrogen peroxide. Therapeutic strategies to mitigate DOX cardiotoxicity should be reexamined in light of these emerging antiapoptotic mechanisms of antioxidants.
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PMID:Doxorubicin-induced apoptosis in endothelial cells and cardiomyocytes is ameliorated by nitrone spin traps and ebselen. Role of reactive oxygen and nitrogen species. 1089 61

Doxorubicin (DOX) resistant A10A cells derived from human squamous carcinoma A431 cells were found to exhibit a smaller degree of apoptosis after DOX treatment as compared to their parent cells. Induction of reactive oxygen species (ROS) formation and mitochondrial depolarization by DOX were more pronounced in the parent cells than in the A10A cells. The fact that catalase suppressed the DOX effect on ROS induction, mitochondrial depolarization and apoptosis in both cell lines suggests an involvement of ROS in the DOX-induced apoptosis. To investigate the underlying mechanisms for DOX resistance in A10A cells, RT-PCR based differential display was used. One of the clones, which was down-regulated in the A10A cells, had sequence homology with part of the mitochondrial NADH dehydrogenase III (ND3) gene. NADH dehydrogenase plays an important role in generating ROS during DOX treatment. The results indicate that down-regulation of ND3 may at least in part contribute to the mechanism for A10A cells resistant to DOX-induced apoptosis.
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PMID:The decrease of mitochondrial NADH dehydrogenease and drug induced apoptosis in doxorubicin resistant A431 cells. 1095 45

The antitumor drugs of the anthraquinone group are widely used agents in the treatment of a variety of human neoplasms. However, their clinical effectiveness is limited by several factors, among which dose-dependent cardiotoxicity is of great importance. Numerous data indicate that the cardiac effects of these drugs are the consequence of one-electron transfer from reduced nucleotides to atmospheric oxygen. This process is catalyzed primarily by NADH dehydrogenase, NADPH cytochrome P450 reductase, and xanthine oxidase, and leads to the formation of reactive oxygen species. In our previous studies we have shown that the NADH dehydrogenase catalyzed electron transfer phenomenon is correlated with the affinity of anthraquinone drugs to the enzyme. In this work data are presented on the ability of compounds belonging to several structural types of anthraquinone cytostatics (sugar- and quinone-modified derivatives of DR and ADR, and anthracenedione compounds) to stimulate free radical formation in the above three enzymatic systems. It has been shown that the three oxidoreductases exhibit different structural requirements with respect to their substrate properties for anthraquinones. Therefore, evaluation of the structural factors determining the ability of anthraquinone compounds to generate active oxygen species cannot be limited to a single oxidoreductase system but must include all types of enzymatic systems involved in the catalysis of one-electron transfer reactions.
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PMID:Differential ability of cytostatics from anthraquinone group to generate free radicals in three enzymatic systems: NADH dehydrogenase, NADPH cytochrome P450 reductase, and xanthine oxidase. 1268 75

Doxorubicin (DOX) is a highly effective treatment for several forms of cancer. However, DOX induces a cumulative and dose-dependent cardiomyopathy that has been ascribed to redox-cycling of the molecule on the mitochondrial complex I generating in the process increased oxidative stress. Mitochondrial dysfunction, including induction of the mitochondrial permeability transition (MPT) and inhibition of mitochondrial respiration have been implicated as major determinants in the pathogenesis of DOX cardiotoxicity. The adenine nucleotide translocator (ANT) has been suggested to be a principal component of the MPT pore and a possible target for DOX-induced cardiotoxicity. Nonetheless, no definitive evidence has been presented showing that altered ANT activity is due to decreased amount of the protein. By using carboxyatractyloside as a specific modulator of ANT activity and Western blotting, we observed that following DOX treatment in rats: (1) the amount of "functional ANT" that contributes to cardiac mitochondrial respiration with different substrates is reduced, (2) titrations with carboxyatracyloside revealed a lower threshold for MPT induction and most importantly, (3) a specific decrease in the amount of the ANT protein. This study identifies the ANT as one important target for DOX-induced cardiac toxicity and correlates the decrease in ANT protein concentration with inhibition of mitochondrial respiration and increased ability to form or at least regulate MPT pores.
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PMID:Depletion of adenine nucleotide translocator protein in heart mitochondria from doxorubicin-treated rats--relevance for mitochondrial dysfunction. 1642 79

Cumulative doses of doxorubicin, a potent anticancer drug, lead to serious myocardial dysfunction. Numerous mechanisms including apoptosis have been proposed to account for its cardiotoxicity. Cardiac apoptosis induced by doxorubicin has been related to excessive reactive oxygen species production by the mitochondrial NADH dehydrogenase. Here, we explored whether doxorubicin treatment activates other superoxide anion generating systems such as the NADPH oxidases, membrane-embedded flavin-containing enzymes, and whether the subsequent oxidative stress contributes to apoptosis. We showed that doxorubicin treatment of rat cardiomyoblasts H9c2 triggers increases in caspase-3 like activity and hypoploid cells, both common features of apoptosis. Doxorubicin exposure also leads to a rapid superoxide production through NADPH oxidase activation. Inhibition of these enzymes using diphenyliodonium and apocynin reduces doxorubicin-induced reactive oxygen species production, caspase-3 like activity and sub-G1 cell population. In conclusion, NADPH oxidases participate to doxorubicin-induced cardiac apoptosis.
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PMID:NADPH oxidases participate to doxorubicin-induced cardiac myocyte apoptosis. 1969 79

The dibenzylbutyrolactolic lignan (-)-cubebin was isolated from dry seeds of Piper cubeba L. (Piperaceae). (-)-Cubebin possesses anti-inflammatory, analgesic and antimicrobial activities. Doxorubicin (DXR) is a topoisomerase-interactive agent that may induce single- and double-strand breaks, intercalate into the DNA and generate oxygen free radicals. Here, we examine the mutagenicity and recombinogenicity of different concentrations of (-)-cubebin alone or in combination with DXR using standard (ST) and high bioactivation (HB) crosses of the wing Somatic Mutation And Recombination Test in Drosophila melanogaster. The results from both crosses were rather similar. (-)-Cubebin alone did not induce mutation or recombination. At lower concentrations, (-)-cubebin statistically reduced the frequencies of DXR-induced mutant spots. At higher concentrations, however, (-)-cubebin was found to potentiate the effects of DXR, leading to either an increase in the production of mutant spots or a reduction, due to toxicity. These results suggest that depending on the concentration, (-)-cubebin may interact with the enzymatic system that catalyzes the metabolic detoxification of DXR, inhibiting the activity of mitochondrial complex I and thereby scavenging free radicals. Recombination was found to be the major effect of the treatments with DXR alone. The combined treatments reduced DXR mutagenicity but did not affect DXR recombinogenicity.
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PMID:The effect of the dibenzylbutyrolactolic lignan (-)-cubebin on doxorubicin mutagenicity and recombinogenicity in wing somatic cells of Drosophila melanogaster. 2138 98


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