Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The induction of quinone reductase [QR; NAD(P)H:(quinone acceptor) oxidoreductase; EC 1.6.99.2] in cultured cells and animal tissues of rodents has provided useful information on mechanisms of protection against carcinogens. We have developed a simple and efficient microtiter plate assay for the direct measurement of QR basal activity and inducibility in human peripheral blood lymphocytes (unstimulated, mitogen-stimulated and Epstein-Barr virus-transformed) grown in suspension culture. In these cells, QR was induced by monofunctional (electrophilic) inducers (i.e. 1,2-dithiole-3-thione, dimethyl fumarate, methyl vinyl sulfone) but not by bifunctional inducers (i.e. 1,1'-azonaphthalene, beta-naphthoflavone, 2,3,7,8-tetrachlorodibenzo-p-dioxin). QR is a major enzyme of xenobiotic metabolism that carries out obligatory two-electron reductions and thereby protects cells against the toxicity of quinones. It is induced in many tissues coordinately with other enzymes that protect against electrophiles. Since lymphocytes can be sampled easily and repetitively in man, this system may provide a simple short-term marker for assessing the capacity of tissues to detoxify electrophiles, such as quinones, and for measuring the response to inducers.
Carcinogenesis 1991 Dec
PMID:Induction of NAD(P)H:quinone reductase in human peripheral blood lymphocytes. 166 Jul 93

Quinone metabolites of catechol estrogens have been postulated to mediate estradiol-induced carcinogenesis. In this study, this postulate was examined by investigating the effect of modulators of quinone metabolism on estradiol-induced tumor incidence in male Syrian hamsters. 2(3)-t-Butyl-4-hydroxyanisol (BHA) and dicumarol which are known to stimulate or inhibit respectively, the activity of quinone reductase, lowered tumor incidence by 33 and 42% respectively (3/9 and 5/12 tumor-free animals/total respectively), from 100% (13/13) observed with 17 beta-estradiol (E2) treatment only. Ebselen, a substance with glutathione peroxidase-like activity, and sodium 2-mercaptoethanesulfonate (Mesna), a cytoprotective thiol-containing agent, were only marginally effective in decreasing the estradiol-induced kidney tumor incidence (3/11 and 4/19 tumor-free animals/total respectively). The lowering of tumor incidence by BHA and dicumarol correlated well with a 40-45% decrease in renal peroxidatic activity of cytochrome P450 in hamsters treated with these substances plus estradiol for 1 month. In addition, these compounds also inhibited the oxidation of diethylstilbestrol to its corresponding quinone in vitro. An influence on quinone reductase or other detoxifying enzymes in chronically treated male Syrian hamsters could not be detected. These data support a mediation of estradiol-induced carcinogenesis by quinones formed by metabolic oxidation of catechol estrogens.
Carcinogenesis 1990 Apr
PMID:Inhibition of estrogen-induced kidney carcinogenesis in Syrian hamsters by modulators of estrogen metabolism. 169 Oct 52

Non-transformed skin fibroblasts derived from five members of a cancer-prone family and three unrelated healthy volunteers were assayed for their levels of activity of the quinone reductase DT-diaphorase and for their sensitivity to the antitumor quinone mitomycin C (MMC). Previous studies of skin fibroblasts derived from one afflicted member of this family (3437T) demonstrated increased resistance to MMC under aerobic exposure conditions and a reduced level of DT-diaphorase. In the present study 3437T cells and a cell strain derived from another afflicted member of the cancer-prone family were found to be hyperresistant to the cytotoxic effects of MMC, and demonstrated negligible DT-diaphorase activity (30 +/- 10 nmol/min/mg protein). Cell strains derived from the three other family members demonstrated intermediate DT-diaphorase activity (400-800 nmol/min/mg protein). Enzyme activities of 1800-6000 nmol/min/mg protein were measured in the three control cell strains. A protein that was reactive with a rabbit polyclonal antibody raised against rat DT-diaphorase and corresponded to the known mol. wt of DT-diaphorase was clearly evident in the three control cell strains, but absent in the two MMC-hyperresistant cell strains. This protein was present in intermediate amounts in the remaining members of the cancer-prone family. Southern analysis of DNA isolated from all eight cell strains and restricted with EcoRI demonstrated the presence of a DNA sequence of approximately 15 kb which hybridized to a rat DT-diaphorase cDNA probe. Northern analysis revealed the presence of an RNA species approximately 1200 bp in size, consistent with that for a human DT-diaphorase mRNA, in all cell strains derived from family members. A post-transcriptional defect would, therefore, appear to be responsible for the decreased enzyme activity observed in the resistant cell strains. These results suggest a role for DT-diaphorase in MMC bioactivation and that reduced levels of the protein may be causally related to the cancer-prone tendency of this family.
Carcinogenesis 1991 Jul
PMID:DT-diaphorase activity and mitomycin C sensitivity in non-transformed cell strains derived from members of a cancer-prone family. 190 77

The effect of dietary intake of butylated hydroxytoluene (BHT) (0.6%) on the in vivo distribution, metabolism and DNA-binding of intragastrically administered 7,12-dimethylbenz[a]anthracene (DMBA) was evaluated. Urinary excretion of DMBA increased, blood content of metabolized DMBA increased and blood content of non-metabolized DMBA decreased for rats fed the diet containing BHT as compared to rats fed the control diet. The binding of DMBA to both liver and mammary DNA decreased for rats fed the diet containing BHT as compared to controls. The liver activities of glutathione-S-transferase (GST), epoxide hydrolase (EH) and NAD(P)H-quinone reductase (QR) increased in response to BHT feeding. However, no increase in the mammary tissue activities of these enzymes was observed. These results suggest that the ability of dietary BHT to inhibit the initiation of DMBA-induced mammary carcinogenesis partly may be due to decreased binding of DMBA to mammary DNA. This effect of BHT is not due to an increase in mammary tissue activities of GST, EH and QR, enzymes involved in carcinogen detoxification, but may involve increased liver metabolism of DMBA to products that do not bind to DNA.
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PMID:Effect of dietary butylated hydroxytoluene on the in vivo distribution, metabolism and DNA-binding of 7,12-dimethylbenz[a]anthracene. 210 65

The present study is part of an effort to identify biomarkers for various stages of preneoplasia. For this purpose, quinone reductase [NAD(P)H:quinone oxidoreductase, EC 1.6.99.2] (QR) activity in the forestomach of ICR/Ha mice was investigated at successive time points during benzo(a)pyrene (BP)-induced carcinogenesis. Six mg of BP in 0.2 ml of cottonseed oil or cottonseed oil alone were given orally twice a week for 2 weeks to female ICR/Ha mice. Ten mice from each group were sacrificed sequentially at 2-week intervals, and the QR activity was determined in the forestomach, a target tissue for BP carcinogenicity, and also in the glandular stomach, a non-target tissue. QR was significantly increased in the cytosolic, microsomal, and mitochondrial fractions of the forestomach of BP-treated animals. There was no significant increase in this activity in any fraction of the glandular stomach. The increases in QR activity in the subcellular fractions of the forestomach from BP-treated animals showed a two-surge pattern. The first was manifested at 2 weeks. The second, found at week 6, continued throughout the remaining course of the experiment. To our knowledge, the time course of changes in QR activity in the three subcellular fractions of mouse forestomach during BP carcinogenesis has not been demonstrated previously.
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PMID:Long term effects of benzo(a)pyrene on the activity of NAD(P)H:quinone reductase in the forestomach and glandular stomach of ICR/Ha mice. 210 67

Dihydrodiol dehydrogenase (DD; EC 1.3.1.20) will oxidize non-K-region trans-dihydrodiols of polycyclic aromatic hydrocarbons (PAHs), a reaction that can suppress the formation of PAHs) anti-diol epoxides or ultimate carcinogens. Using benzenedihydrodiol [(+/-)-trans-1,2-dihydroxy-3,5-cyclohexadiene] as a model substrate for trans-dihydrodiol metabolites of PAHs, 23 human liver and eight human lung samples were examined for enzyme activity. In human liver, enzyme activity could be measured spectrophotometrically and specific activities ranged from 0.16 to 6.1 nmol benzenedihydrodiol oxidized min/mg protein. Western blot analysis of human liver cytosol using rabbit anti-rat DD serum detected two bands of mol. wts 34,000 and 27,000. The former mol. wt is identical to that observed for the homogeneous rat liver enzyme. Gel-filtration experiments indicate that human liver DD activity elutes as a single peak and co-elutes with the purified rat liver enzyme, suggesting that the lower mol. wt species may be an artefact of degradation. Preparations of the human liver enzyme required NADP- for activity and were in general, insensitive to inhibition by dicoumarol, indomethacin and 6-medroxyprogesterone acetate. These properties distinguish the enzyme from alcohol dehydrogenase, quinone reductase and rat liver DD. In human lung, DD activity was barely detectable using a sensitive radiochemical assay in which the oxidation of benzenedihydrodiol to catechol is linked to catechol-O-methyl transferase using [3H]S-adenosyl methionine as methyl donor. Specific activities were approximately 1000th of that observed for human liver and ranged from 1 to 4 pmol benzenedihydrodiol oxidized/min/mg protein. Western blot analysis of lung cytosol detected three bands of mol. wts 34,000, 31,000 and 28,000. The relatively high levels of DD in human liver suggest that this enzyme may play an important role in PAH detoxication in this organ, while the low levels of DD in lung may contribute to the susceptibility of this tissue to PAH-induced carcinogenesis.
Carcinogenesis 1990 Jul
PMID:Characterization of dihydrodiol dehydrogenase in human liver and lung. 219 14

The distribution of NADPH-dependent quinone reductase and NADPH-cytochrome P-450 reductase activities was determined in the urinary bladders of male and female rabbits. In urinary bladder transitional epithelium (UBTE) and in urinary bladder non-transitional tissue (UBNT) microsomal quinone reductases demonstrated significant (P less than 0.05) sex-dependent differences in the case of both dicoumarol-insensitive (male greater than female) and dicoumarol-sensitive or DT-diaphorase (female greater than male) activities. Microsomal NADPH-cytochrome P-450 reductase activities in UBTE and in UBNT were found to be similar in male and female rabbits. The activities of microsomal and cytosolic quinone reductases and the activity of microsomal NADPH-cytochrome P-450 reductase in UBNT were much lower than those in UBTE. NADPH-cytochrome P-450 reductase and similar flavo-enzymes activate quinones via one-electron reduction into semiquinone free radicals, which then react with molecular oxygen, forming superoxide anions. DT-diaphorase acts as a detoxifying enzyme by converting many quinones via a unique two-electron reduction into less reactive hydroquinones, enabling their excretion as water-soluble conjugates. Since UBTE contains substantial activities of prostaglandin H synthase (PHS) and NADPH-cytochrome P-450 reductase, unlike UBNT, the toxicity and carcinogenicity of xenobiotics which are either quinones or form quinones in situ through the mediation of PHS would be high in UBTE. The risk of carcinogenicity of quinones in UBTE would be higher in male rabbits than in female rabbits due to sex-dependent differences in the relative proportions of the one-electron reduction pathway, represented by NADPH-cytochrome P-450 reductase, and the two-electron reduction pathway, represented by DT-diaphorase (female greater than male).
Carcinogenesis 1986 Mar
PMID:Sex-dependent activities of quinone reductases in rabbits indicate higher risk of bladder cancer in the male. 241 7

Dietary supplementation of vitamin C to diethylstilbestrol (DES)- or estradiol-treated male Syrian hamsters is known to inhibit renal carcinogenesis by approximately 50%. To elucidate the mechanism of inhibition, the influence of administration of vitamin C on a series of previously described biochemical markers of kidney carcinogenesis was investigated. Hamsters were stratified into four groups: (i) untreated controls; (ii) vitamin C-treated; (iii) estrogen-treated; and (iv) estrogen plus vitamin C-treated animals. Concomitant administration of vitamin C and diethylstilbestrol (DES) decreased concentrations of the major DES-DNA adduct by 70-90% in liver, kidney and testis than those receiving DES only. Diethylstilbestrol-4',4"-quinone has previously been shown to be the genotoxic metabolite of DES responsible for DNA adduct formation in vivo. In vitro, vitamin C reduced diethylstilbestrol-4',4"-quinone to cis- and trans-diethylstilbestrol in a dose-dependent fashion. Changes in activities of quinone reductase, catalase, superoxide dismutase and of glutathione metabolizing enzymes (glutathione peroxidase, glutathione reductase, gamma-glutamyl transpeptidase and glucose-6-phosphate dehydrogenase) in response to vitamin C were not observed or not sufficiently large to account for the 50% decrease in tumor incidence. No differences were detected in indirect estrogen-induced kidney DNA adducts in response to vitamin C treatment. It is concluded that vitamin C inhibits estrogen-induced carcinogenesis by reducing concentrations of estrogen quinone metabolites and their DNA adducts.
Carcinogenesis 1989 Nov
PMID:Mechanism of inhibition of estrogen-induced renal carcinogenesis in male Syrian hamsters by vitamin C. 257 56

Cytochrome P-450-mediated redox cycling between the synthetic estrogen diethylstilbestrol (DES) and diethylstilbestrol-4',4"-quinone (DES Q) has previously been demonstrated. Cytochrome P-450 reductase catalyzes the reduction of DES Q presumably via a semiquinone formed by one-electron reduction. A reducing action of NAD(P)H quinone reductase (EC 1.6.99.2) mediating two-electron reduction of DES Q has been investigated in the present work. Quinone reductase catalyzed the conversion in the presence of NADH or NADPH of DES Q to 53-65% Z-DES, a marker product of reduction. Dicumarol (15 microM), a known specific inhibitor of quinone reductase, inhibited this reduction almost completely. Using microsomes from Syrian hamster kidney, a target organ of estrogen-induced carcinogenesis, the reduction of DES Q was only partially inhibited by dicumarol. Apparent Km values of quinone reductase and cytochrome P-450 reductase were 17.25 and 11.9 microM, respectively. These data demonstrate that in hamster kidney, quinone reductase and cytochrome P-450 reductase compete for the reduction of DES Q. Microsomal 02-. radical generation was stimulated 10-fold over base levels by the addition of 100 microM DES Q. The formation of 02-. radicals was inhibited by addition of superoxide dismutase (0.2 mg/ml) or by 2'-AMP or NADP, known inhibitors of cytochrome P-450 reductase. In contrast, dicumarol enhanced microsome-mediated 02-. formation. It is concluded that cytochrome P-450 reductase in hamster kidney microsomes mediates one-electron reduction of estrogen quinones to free radicals (semiquinones), which may subsequently enter redox cycling with molecular oxygen to form 02-.. Moreover, quinone reductase reduces DES Q directly to E- and Z-DES, and thus may prevent the formation of toxic intermediates during redox cycling of estrogens. Measurements of quinone reductase activity in liver and kidney of hamsters treated with estrogen for various lengths of time revealed a temporary decrease in activity by 80% specifically in the kidney after 1 month of chronic treatment with estradiol. Thus, a temporary decrease in quinone reductase activity, which occurred specifically in estrogen-exposed hamster kidney, may enhance the formation of free radical intermediates generated during biotransformation of estrogens.
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PMID:Temporary decrease in renal quinone reductase activity induced by chronic administration of estradiol to male Syrian hamsters. Increased superoxide formation by redox cycling of estrogen. 283 Nov 97

Carcinogenesis is blocked by an extraordinary variety of agents belonging to many different classes--e.g., phenolic antioxidants, azo dyes, polycyclic aromatics, flavonoids, coumarins, cinnamates, indoles, isothiocyanates, 1,2-dithiol-3-thiones, and thiocarbamates. The only known common property of these anticarcinogens is their ability to elevate in animal cells the activities of enzymes that inactivate the reactive electrophilic forms of carcinogens. Structure-activity studies on the induction of quinone reductase [NAD(P)H:(quinone-acceptor) oxidoreductase, EC 1.6.99.2] and glutathione S-transferases have revealed that many anti-carcinogenic enzyme inducers contain a distinctive and hitherto unrecognized chemical feature (or acquire this feature after metabolism) that regulates the synthesis of these protective enzymes. The inducers are Michael reaction acceptors characterized by olefinic (or acetylenic) bonds that are rendered electrophilic (positively charged) by conjugation with electron-withdrawing substrates. The potency of inducers parallels their efficiency in Michael reactions. Many inducers are also substrates for glutathione S-transferases, which is further evidence for their electrophilicity. These generalizations have not only provided mechanistic insight into the perplexing question of how such seemingly unrelated anticarcinogens induce chemoprotective enzymes, but also have led to the prediction of the structures of inducers with potential chemoprotective activity.
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PMID:Identification of a common chemical signal regulating the induction of enzymes that protect against chemical carcinogenesis. 314 25


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