Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.5.1.18 (glutathione S-transferase)
22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The objective of this study was to evaluate the chemopreventive potential of the black tea polyphenols Polyphenon-B and BTF-35 during the preinitiation phase of 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis. Hamsters were divided into six groups. Animals in groups 2 and 3 received diet containing Polyphenon-B and BTF-35, respectively, 4 weeks before carcinogen administration when they were 6 weeks of age and continued until the final exposure to carcinogen. At 10 weeks of age, animals in groups 1, 2, and 3 were painted with 0.5% DMBA three times a week for 14 weeks. Animals in groups 4 and 5 were given Polyphenon-B and BTF-35 alone, respectively, as in groups 2 and 3. Animals in group 6 served as control. All the animals were sacrificed after an experimental period of 18 weeks. Phase I and phase II xenobiotic-metabolizing enzymes and 8-hydroxy-deoxyguanosine (8-OH-dG) in the buccal pouch and liver were used as biomarkers of chemoprevention. Hamsters painted with DMBA showed increased expression of 8-OH-dG and enhanced activities of phase I (CYP450; total as well as CYP1A1, 1A2, and 2B isoforms and cytochrome b5) and phase II (GST and quinone reductase) xenobiotic-metabolizing enzymes with increased immunohistochemical expression of CYP1A1, and CYP1B1 isoforms in the buccal pouch. This was accompanied by increased phase I and decreased phase II enzyme activities in the liver. Administration of Polyphenon-B and BTF-35 significantly decreased tumor incidence, oxidative DNA damage, phase I enzyme activities as well as expression of CYP1A1 and CYP1B1 isoforms, while enhancing phase II enzyme activities in the buccal pouch and liver. Our results provide a mechanistic basis for the chemopreventive potential of black tea polyphenols. Furthermore, the greater efficacy of BTF-35 in chemoprevention of HBP carcinomas via inhibition of oxidative DNA damage and modulation of xenobiotic-metabolizing enzymes may have a major impact in human oral cancer prevention.
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PMID:Pretreatment with black tea polyphenols modulates xenobiotic-metabolizing enzymes in an experimental oral carcinogenesis model. 1854 9

Polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (B[a]P) and 7,12-dimethylbenz[a]anthracene (DMBA) are environmental pollutants, which undergo metabolic activation to exert their carcinogenic effects. Our earlier studies showed that naturally occurring plant phenols, protocatechuic, chlorogenic, tannic acids and resveratrol, besides inhibiting B[a]P and DMBA binding to DNA, modulate the activity of the enzymes involved in PAHs activation. The aim of the present study was further examination of the effect of these compounds on the expression and activities of CYP1A1/1A2, CYP1B1, CYP2B, and phase 2 enzymes in female BALB/C mouse epidermis treated with an initiating dose of B[a]P or DMBA. Application of a single 400 nmol dose of B[a]P alone significantly (by 119-127%) increased the activities of ethoxy- (EROD) and methoxy- (MROD) resorufin dealkylases and to lesser extent penthoxyresorufin depentylase (PROD) (by 32%). Western blot analysis with CYP1A1/1A2, CYP1B1 and CYP2B-specific antibodies showed the increase of CYP1A1/1A2 and CYP2B levels in B[a]P-treated animals. Phase 2 enzymes, gluthatione S-transferase and NAD(P)H:quinone oxidoreductase-1 (NQO1) were also significantly increased. In contrast to B[a]P, application of the initiating dose of DMBA (10 nmol) on mouse skin did not change the activities or protein levels of cytochrome P450, however increased the activities of NQO1 and GST. Pretreatment of mice with phenolic compounds one hour before B[a]P application significantly decreased the activities of all alkoxyresorufin dealkylases in comparison with the group of mice treated only with B[a]P. The sole exception was tannic acid which did not affect the PROD activity. This polyphenol, however, decreased the protein level of CYP1A1/1A2 and CYP1B1 isozymes enhanced by B[a]P. All phenolics, particularly resveratrol, significantly (by 129-174%) increased the activity of NQO1 in comparison with B[a]P-treated animals. On the other hand, pretreatment with phenolic compounds significantly diminished NQO1 activity in comparison with DMBA-treated group. These results indicate that the reduction of B[a]P-DNA adducts observed in our earlier studies may result from the decreased B[a]P activation by investigated plant phenols. In case of DMBA-DNA adducts, the scavenging or masking the binding sites to be occupied by DMBA reactive metabolites is more probable. Moreover, the lack of cytochrome P450 induction by the initiating dose of DMBA suggests that the constitutive expression of P450, particularly CYP1B1 is sufficient for DMBA activation and subsequent DNA adducts formation.
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PMID:The effect of initiating doses of benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene on the expression of PAH activating enzymes and its modulation by plant phenols. 1869

Breast cancer is the most common female cancer and the second cause of cancer death in women. Despite recent breakthroughs, much of the etiology of this disease is unknown and the most important risk factor, i.e., exposure to endogenous and exogenous estrogen throughout life cannot explain the heterogeneity of prognosis nor clinical features of patients. Recently, many gene polymorphisms in the metabolism of breast cancer have been described as possible neoplasm etiologic factors. This review is an attempt to summarize the current knowledge about these polymorphisms and to determine new target genes for diagnosis and treatment of the disease. Polymorphisms in the genes CYP17, CYP19, CYP1A1, CYP1A2, CYP1B1, UGT1A1, SULT1A1, 17-hydroxysteroid-dehydrogenase, COMT, GST, ESR1, and ESR2 are described.
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PMID:Genetic polymorphisms, the metabolism of estrogens and breast cancer: a review. 1871 61

The objective of this study was to evaluate the potential of the structurally related aliphatic isothiocyanates erucin and sulforaphane to modulate the pulmonary carcinogen-metabolising enzyme systems in rat lung, a target organ of their chemopreventive activity. Precision-cut rat lung slices were prepared and incubated for 24 h with a range of concentrations of either erucin or sulforaphane, up to 50microM. Neither compound modulated the O-deethylation of ethoxyresorufin whereas they elevated markedly CYP1A1 and, to a lesser extent, CYP1B1 apoprotein levels. Neither compound influenced the O-depentylation of pentoxyresorufin or CYP2B apoprotein levels, but sulforaphane caused a modest increase in CYP3A2 apoprotein levels. Pulmonary quinone reductase activity, monitored using 3-(4,5-dimethylthiazo-2-yl)-2,5-diphenyltetrazolium bromide as substrate, was markedly up-regulated by both compounds and was paralleled by a similar rise in protein levels. Both compounds increased cytosolic glutathione S-transferase activity, measured using 1-chloro-2,4-dinitrobenzene as the accepting substrate; a modest rise was seen in GSTalpha protein levels, determined immunologically, whereas GSTpi levels were un-affected by the same treatment. Finally, both erucin and sulforaphane increased total glutathione concentration in lung cytosol. It is concluded that these aliphatic isothiocyanates have the potential to antagonise the carcinogenicity of pulmonary carcinogens by stimulating the in situ detoxication of their DNA-binding genotoxic metabolites.
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PMID:Modulation of rat pulmonary carcinogen-metabolising enzyme systems by the isothiocyanates erucin and sulforaphane. 1882 65

Colorectal cancer literature regarding the interaction between polymorphisms in carcinogen-metabolizing enzymes and red meat intake/doneness is inconsistent. A case-control study was conducted to evaluate the interaction between red meat consumption, doneness, and polymorphisms in carcinogen-metabolizing enzymes. Colorectal cancer cases diagnosed 1997 to 2000, ages 20 to 74 years, were identified through the population-based Ontario Cancer Registry and recruited by the Ontario Family Colorectal Cancer Registry. Controls were sex-matched and age group-matched random sample of Ontario population. Epidemiologic and food questionnaires were completed by 1,095 cases and 1,890 controls; blood was provided by 842 and 1,251, respectively. Multivariate logistic regression was used to obtain adjusted odds ratio (OR) estimates. Increased red meat intake was associated with increased colorectal cancer risk [OR (> 5 versus < or = 2 servings/wk), 1.67 (1.36-2.05)]. Colorectal cancer risk also increased significantly with well-done meat intake [OR (> 2 servings/wk well-done versus < or = 2 servings/wk rare-regular), 1.57 (1.27-1.93)]. We evaluated interactions between genetic variants in 15 enzymes involved in the metabolism of carcinogens in overcooked meat (cytochrome P450, glutathione S-transferase, UDP-glucuronosyltransferases, SULT, NAT, mEH, and AHR). CYP2C9 and NAT2 variants were associated with colorectal cancer risk. Red meat intake was associated with increased colorectal cancer risk regardless of genotypes; however, CYP1B1 combined variant and SULT1A1-638G>A variant significantly modified the association between red meat doneness intake and colorectal cancer risk. In conclusion, well-done red meat intake was associated with an increased risk of colorectal cancer regardless of carcinogen-metabolizing genotype, although our data suggest that persons with CYP1B1 and SULT1A1 variants had the highest colorectal cancer risk.
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PMID:Red meat intake, doneness, polymorphisms in genes that encode carcinogen-metabolizing enzymes, and colorectal cancer risk. 1899 Jul 50

The environmental carcinogen 5-methylchrysene (5MC) can be activated to mutagenic metabolites by several isozymes of cytochrome P-450 (CYP). The resulting reactive diol-epoxides can be detoxified via conjugation by glutathione S-transferases (GST). We investigated whether expression of human glutathione S-transferase P1 (hGSTP1) would differentially protect cells against the cytotoxicity or mutagenicity of 5MC or its 1,2-dihydrodiol intermediate (5MC-1,2-diol) in V79MZ cells with activation via stably transfected human CYP1B1 (hCYP1B1) as compared to activation by human CYP1A1 (hCYP1A1). The parent compound 5MC was only 2-fold more cytotoxic in the CYP-expressing cell lines than in the V79MZ parental cell line, while 5MC-1,2-dihydrodiol was more than 30-fold more cytotoxic in CYP-transfected cells compared to V79MZ cells. Cells co-expressing either hCYP1B1 or hCYP1A1 together with hGSTP1 were 2-fold less sensitive to 5MC or 5MC-1,2-diol cytotoxicity than their CYP-only parent lines. The 5MC was highly mutagenic with similar potency in both hCYP-transfected cell lines, while 5MC-1,2-diol was 2-fold more mutagenic in hCYP1B1-transfected cells as compared to hCYP1A1 cells. Coexpression of hGSTP1 with either hCYP reduced 5MC or 5MC-1,2-diol mutagenicity by 1.4-4.5-fold compared to the corresponding hCYP-only expressing cell lines. The greater protection against mutagenicity of 5MC is in contrast to our previous studies in which we found greater protection by hGSTP1 against cytotoxicity than mutagenicity of benzo[a]pyrene in cells co-expressing hCYP1A1. Protection against mutagenicity by hGSTP1 was greater with activation of either compound by hCYP1B1 than with hCYP1A1 activation. These studies show that the relative efficacy of protection by hGSTP1 against mutagenicity of 5MC or 5MC-1,2-diol is in part determined by the specific CYP pathway that catalyzes activation to the toxic or mutagenic metabolites.
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PMID:Cytotoxicity and mutagenicity of 5-methylchrysene and its 1,2-dihydrodiol in V79MZ cells modified to express human CYP1A1 or CYP1B1, in the presence or absence of human GSTP1 coexpression. 1899 97

The hamster buccal pouch (HBP) carcinogenesis model is one of the most well characterized animal systems for analyzing the development of oral squamous cell carcinoma (OSCC), a common malignancy worldwide. HBP carcinomas that closely mimic human OSCC are useful in understanding the molecular mechanisms of neoplastic transformation. The present study is a comparative evaluation of markers of carcinogen activation, oxidative stress, cell proliferation, apoptosis, invasion, and angiogenesis in human and hamster OSCCs. Enhanced expression of CYP1A1 and CYP1B1 isoforms in both human and hamster oral tumours was associated with significantly increased expression of 8-hydroxy 2-deoxyguanosine (8-OHdG) indicating oxidative DNA damage. Analysis of markers of cell survival and proliferation revealed increased expression of PCNA, GST-P, and NF-kappaB with downregulation of p21, p53 and IkappaB in both human and hamster OSCCs. In addition, both human and hamster oral carcinomas displayed invasive, and angiogenic properties as revealed by dysregulated cytokeratin expression, downregulation of RECK, and increased expression of uPA, MMP-2 and-9, HIF-1alpha, and VEGF. The results reveal aberrant expression of multiple molecules in key signaling pathways in both human OSCCs and HBP carcinomas rendering the HBP model as an important tool for monitoring oral oncogenesis.
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PMID:Of humans and hamsters: a comparative evaluation of carcinogen activation, DNA damage, cell proliferation, apoptosis, invasion, and angiogenesis in oral cancer patients and hamster buccal pouch carcinomas. 1925 Aug 57

A reduction in endogenously generated reactive oxygen species in vivo delays benzo(a)pyrene (BaP)-accelerated atherosclerosis, as revealed in hypercholesterolemic mice overexpressing Cu/Zn-superoxide dismutase (SOD) and/or catalase. To understand the molecular events involved in this protective action, we studied the effects of Cu/Zn-SOD and/or catalase overexpression on BaP detoxification and on aryl hydrocarbon receptor (AhR) expression and its target gene expression in mouse aortic endothelial cells (MAECs). Our data demonstrate that overexpression of Cu/Zn-SOD and/or catalase leads to an 18- to 20-fold increase in the expression of AhR protein in MAECs. After BaP exposure, the amount of AhR binding to the cytochrome P450 (CYP) 1A1 promoter was significantly greater, and the concentrations of BaP reactive intermediates were significantly less in MAECs overexpressing Cu/Zn-SOD and/or catalase than in wild-type cells. In addition, the BaP-induced CYP1A1 and 1B1 protein levels and BaP-elevated glutathione S-transferase (GST) activity were significantly higher in these transgenic cells, in parallel with elevated GSTp1, CYP1A1, and CYP1B1 mRNA levels, compared to wild-type MAECs. Moreover, knockdown of AhR with RNA interference diminished the Cu/Zn-SOD and catalase enhancement of CYP1A1 expression, GST activity, and BaP detoxification. These data demonstrate that overexpression of Cu/Zn-SOD and/or catalase is associated with upregulation of AhR and its target genes, such as xenobiotic-metabolizing enzymes.
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PMID:Overexpression of Cu/Zn-superoxide dismutase and/or catalase accelerates benzo(a)pyrene detoxification by upregulation of the aryl hydrocarbon receptor in mouse endothelial cells. 1966 5

The constitutive and inducible expression of aryl hydrocarbon receptor (AhR) and of the AhR-regulated genes coding for CYP1A1, CYP1A2, CYP1B1, CYP2S1, and Nrf2 was investigated by real-time or traditional PCR in cerebral areas (cortex, cerebellum, midbrain, and hippocampus), blood-brain interfaces (meninges and brain microvessels) and liver obtained from control pigs and from pigs treated with beta-naphthoflavone (betaNF), a potent AhR agonist. The enzymatic activities of ethoxyresorufin-O-deethylase (EROD), and methoxyresorufin-O-deethylase (MEROD), marker for CYP1A1 and CYP1A2, the GST and various antioxidant enzymes (catalase, superoxide dismutase, GSSG-reductase, and GSH-peroxidase) were also determined in the same CNS regions. The AhR, CYP1A1, CYP1A2, CYP1B1, Nrf2 mRNAs were detected, although at different extent, in all the CNS regions, while CYP2S1 mRNA was detected only in midbrain. In the blood-brain interfaces, the constitutive basal expression of AhR and CYP1A1 was comparable to the hepatic one and even higher for CYP1B1 and Nrf2. The treatment with betaNF determined the induction of CYP1A1 and 1B1 (but not of AhR, CYP1A2, and Nrf2) mRNA levels in various CNS areas; notably, CYP1A1 mRNA was increased to about 300-fold in the microvessels. The analysis of enzymatic activities revealed that EROD, but not MEROD, was induced in microsomes but not in mitochondria of all the CNS areas. However, the mitochondrial EROD activities were comparable (in midbrain, meninges) or higher (in cortex, cerebellum, hippocampus) than the microsomal ones, suggesting an important metabolic function of CYP1A1 in this subcellular localization. The activities of GST and antioxidant enzymes were detected in all CNS tissues, with levels lower than the hepatic ones, but found quite evenly distributed and marginally affected by betaNF treatment. The high expression of metabolic enzymes found in blood-brain interfaces could represent a very important defence toward toxins of CNS.
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PMID:Effect of beta-naphthoflavone on AhR-regulated genes (CYP1A1, 1A2, 1B1, 2S1, Nrf2, and GST) and antioxidant enzymes in various brain regions of pig. 1978 62

The objective of this study was to evaluate molecular markers involved in mammary tumorigenesis in a canine model that mimics many essential elements of human breast cancer. Thirty mammary gland tumors and control tissues obtained from female dogs were included in the study. We analyzed changes in the expression of markers of hormone and receptor status (estradiol, estrogen receptor; ER and HER-2/neu), hormone metabolism (CYP1A1 and CYP1B1), cell proliferation and survival [proliferating cell nuclear antigen (PCNA), glutathione S-transferase-P (GST-P), nuclear factor-kappaB (NF-kappaB-p50, NF-kappaB-p65), phosphorylated-inhibitor of kappaB-alpha (p-IkappaB-alpha) and IkappaB], apoptosis (Bcl-2, Bax, caspases, Apaf-1, cytochrome-C, and PARP), invasion [matrix metalloproteinases-2 and -9 (MMP-2, MMP-9), tissue inhibitor of matrix metalloproteinase-2 (TIMP-2), and reversion-inducing cysteine-rich protein with Kazal motifs (RECK)], angiogenesis [vascular endothelial growth factor (VEGF)], and epigenetics [DNA methyltransferase (Dnmt-1), histone deacetylase (HDAC-1)] by immunohistochemical localization and Western blot analysis and correlated these with histological grade. The present study provides evidence that increased expression of ER, HER-2/neu, estradiol, and its metabolizing enzymes, as well as proteins involved in cell proliferation, apoptosis evasion, invasion, and angiogenesis may confer a selective growth advantage to canine mammary tumors. To our knowledge this is the first report on the hallmark capabilities of canine mammary tumors, which lends credence to the view that the dog is a valuable model for human breast cancer studies.
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PMID:Evaluation of molecular markers in canine mammary tumors: correlation with histological grading. 2022 57


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