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)

In the central nervous system oxidative stress has been implicated in the pathology of several neurological disorders. The ability to withstand reactive oxygen species and oxidative stress are essential for survival and therefore all aerobic cells are endowed with chemical and enzymatic antioxidative defense systems. The purpose of the present study was to investigate the antioxidative response at the transcriptional level following exposure of primary astrocytes to a pro-oxidant, Paraquat (PQ). This was done by investigating the time-dependent expression of selected genes encoding the antioxidative enzymes Mn- and CuZn superoxide dismutase (SOD) and catalase as well as the transcription factor component AP-1. Paraquat induced the expression of Mn- and CuZn SOD, catalase and decreases the expression of c-jun (a part of AP-1). Furthermore, the gene expression profiles were investigated after exposure to PQ using a commercial cDNA membrane array containing 207 genes from key oxidative stress pathways. The gene expression pattern clearly indicated that 60 microM PQ for 48 h induces genes related to oxidative stress, detoxification, mitotic arrest, DNA repair, and apoptosis. The PQ (48 h)-induced expressions of genes identified in cDNA array were confirmed by Northern blot analysis, which revealed a statistical significant up-regulation of genes involved in oxidative stress, detoxification, and DNA repair/synthesis and includes heme oxygenase-1 (11-fold), NAD(P)H dehydrogenase (8-fold), glutathione S-transferase P (7-fold), glucose-regulated 78-kDa protein (7-fold), glucose-regulated 75-kDa protein (6-fold), and growth-arrest and DNA-damage-inducible protein 45 (4.5-fold) and minor changes for heat shock 10-kDa protein, NADPH-cytochrome P450 reductase, heme oxygenase-2, proliferating cell nuclear antigen, and Bcl-2-associated death promoter. Thus, we could demonstrate a PQ-inducible effect of the mRNA of antioxidative enzymes, as well as the mRNAs of possible enzymes involved in the protection against oxidative stress.
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PMID:Characterization of the transcriptional profile in primary astrocytes after oxidative stress induced by Paraquat. 1793 86

Acetaminophen, a monocyclic phenolic compound and analgesic, when fed at 8900 p.p.m. in the diet, was reported to inhibit the hepatocarcinogenicity in rats of the aromatic amine proximate carcinogen N-hydroxy-N-acetyl-2-aminofluorene. To elucidate the mechanism(s) of this anticarcinogenicity, the present study examined whether acetaminophen at lower doses has the ability to inhibit the initiating effects in the rat liver of the precursor hepatocarcinogen N-acetyl-2-aminofluorene. Male F344 rats were allocated to six groups, which were maintained under reverse light cycle conditions to assure acetaminophen ingestion at the time of N-acetyl-2-aminofluorene administration during the dark phase, which was imposed from 07.00 to 19.00 h. Group 1 served as vehicle control (0.5% carboxymethylcellulose) for N-acetyl-2-aminofluorene, which was administered intragastrically 3 days per week at 2.6 mg/kg for 8 weeks (group 4) to achieve initiation. Acetaminophen was given in the diet either alone at 2400 or 4800 p.p.m. for 9 weeks (groups 2 and 3), or with N-acetyl-2-aminofluorene (groups 5 and 6), starting 1 week before N-acetyl-2-aminofluorene administration. Acetaminophen blood levels were about 1 and 4 microg/ml at the two dietary concentrations. N-acetyl-2-aminofluorene induced hepatocellular preneoplastic lesions measured as hepatocellular altered foci expressing glutathione S-transferase-P, reflecting initiation. Induced foci were reduced with administration of both concentrations of acetaminophen. Acetaminophen by itself produced no DNA adducts nor did it alter the high formation of N-acetyl-2-aminofluorene-DNA adducts, about 200 in 10 nucleotides, measured by nucleotide postlabeling. Acetaminophen did not affect background liver cell proliferation, but significantly reduced N-acetyl-2-aminofluorene-induced increased proliferation measured by proliferating cell nuclear antigen immunostaining. Thus, acetaminophen effectively protected hepatocytes from the initiating effects of N-acetyl-2-aminofluorene, possibly through a cytoprotective effect resulting from slowing the rate of induced cell turnover.
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PMID:Inhibition by acetaminophen of neoplastic initiation elicited in rat liver by the DNA-reactive hepatocarcinogen N-acetyl-2-aminofluorene. 1809 Jan 25

Polkappa protein is a eukaryotic member of the DinB/Polkappa branch of the Y-family DNA polymerases, which are involved in the tolerance of DNA damage by replicative bypass. Despite universal conservation through evolution, the precise role(s) of Polkappa in this process has remained unknown. Here we report that mouse Polkappa can physically interact with ubiquitin by yeast two-hybrid screening, glutathione S-transferase pulldown, and immunoprecipitation methods. The association of Polkappa with ubiquitin requires the ubiquitin-binding motifs located at the C terminus of Polkappa. In addition, Polkappa binds with monoubiquitinated proliferating cell nuclear antigen (PCNA) more robustly than with non-ubiquitinated PCNA. The ubiquitin-binding motifs mediate the enhanced association between monoubiquitinated PCNA and Polkappa. The ubiquitin-binding motifs are also required for Polkappa to form nuclear foci after UV radiation. However, the ubiquitin-binding motifs do not affect Polkappa half-life. Finally, we have examined levels of Polkappa expression following the exposure of mouse cells to benzo[a]pyrene-dihydrodiol epoxide or UVB radiation.
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PMID:Requirements for the interaction of mouse Polkappa with ubiquitin and its biological significance. 1816 70

Cimetidine is known to have an anti-tumor effect on certain types of malignancies, though on hepatocellular carcinomas (HCCs), its effect remains unclear. We studied the anti-tumor effects of cimetidine on chemically-induced HCCs in rats. Four-week-old male Wistar rats (n=105) were divided into 4 groups. Those in groups A and B were administered diethylnitrosamine (DEN) intraperitoneally at 100 mg/kg body weight every week for 6 weeks, during which rats in group A were given tap water and those in group B received cimetidine (100 mg/kg/day) in their drinking water. Rats in groups C and D were administered saline instead of DEN and given tap water with 100 mg/kg/day of cimetidine, respectively. The animals were sacrificed at 7, 12, 22 and 32 weeks after the first administration of drugs and examined. Liver nodules were observed only in groups A and B, with the number of nodules, maximum diameter of the largest nodule, and liver weight significantly lower in group B. Immunohistochemistry findings showed that glutathione S-transferase placental-positive preneoplastic foci were significantly decreased in group B. Cimetidine treatment decreased the number of proliferating cell nuclear antigen-positive hepatocytes and tended to enhance natural killer (NK) cell activity in splenic lymphocytes. In addition, flow cytometry revealed that the proportion of NK cells among total splenic lymphocytes was not affected by cimetidine treatment. Our results showed that cimetidine has an inhibiting effect on hepatocarcinogenesis.
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PMID:Anti-tumor effects of cimetidine on hepatocellular carcinomas in diethylnitrosamine-treated rats. 1820 82

The chronic ethanol intake influence on the gluthatione S-transferase (GST-P) and transforming growth factor alpha (TGF-alpha) expression in remodeling/persistent preneoplastic lesions (PNLs) was evaluated in the resistant hepatocyte model. Male Wistar rats were allocated into five groups: G1, non-treated, fed water and chow ad libitum; G2, non-treated and pair-fed chow (restricted to match that of G3 group) and a maltodextrin (MD) solution in tap water (matched ethanol-derived calories); G3, fed 5% ethanol in drinking water and chow ad libitum; G4, diethylnitrosamine (DEN, 200 mg/kg, body weight) plus 200 parts per million of 2-acetylaminofluorene (2-AAF) for 3 weeks and pair-fed chow (restricted to match that of G5 group) and an MD solution in tap water (matched ethanol-derived calories); G5, DEN/2-AAF treatment, fed ethanol 5% and chow ad libitum. All animals were subjected to 70% partial hepatectomy at week 3 and sacrificed at weeks 12 or 22, respectively. Liver samples were collected for histological analysis or immunohistochemical expression of GST-P, TGF-alpha and proliferating cell nuclear antigen or zymography for matrix metalloproteinases-2 and -9. At the end of ethanol treatment, there was a significant increase in the percentage of liver area occupied by persistent GST-P-positive PNLs, the number of TGF-alpha-positive PNLs and the development of liver tumors in ethanol-fed and DEN/2-AAF-treated groups (G5 versus G4, P < 0.001). In addition, ethanol feeding led to a significant increase in cell proliferation mainly in remodeling and persistent PNLs with immunoreactivity for TGF-alpha at week 22 (P < 0.001). Gelatinase activities were not altered by ethanol treatment. The results demonstrated that ethanol enhances the selective growth of PNL with double expression of TGF-alpha and GST-P markers.
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PMID:Chronic ethanol intake promotes double gluthatione S-transferase/transforming growth factor-alpha-positive hepatocellular lesions in male Wistar rats. 1827 18

Ginkgo biloba (EGb) has been proposed as a promising candidate for cancer chemoprevention and has shown protective effects on the liver against chemically induced oxidative injury and fibrosis. The potential beneficial effects of EGb were investigated in two rat liver carcinogenesis bioassays induced by diethylnitrosamine (DEN). In a short-term study for anti-initiating screening, male Wistar rats were fed a basal diet or supplemented diet with 500 or 1000 ppm EGb and initiated 14 days later with a single dose of DEN (100 mg/kg i.p.). The respective groups were killed 24h or 2 weeks after DEN-initiation. Liver samples were collected for the analysis of proliferating cell nuclear antigen (PCNA), transforming growth factor alpha (TGF-alpha), p53, apoptosis and induction of single hepatocytes and minifoci positive for the enzyme glutathione S-transferase P-form (GST-P). In a medium-term study for anti-promoting screening, the animals received a single dose of DEN (200 mg/kg i.p.) and, 2 weeks later, were fed a basal diet or supplemented diet with 500 or 1000 ppm EGb for 6 weeks. All animals underwent 70% partial hepatectomy (PH) at week 3 and killed at week 8. Liver samples were collected to analyze development of preneoplastic foci of altered hepatocytes (FAH) expressing GST-P. In the short-term study, pretreatment of rats with 1000 ppm EGb significantly reduced the rates of cell proliferation, apoptosis and p53, TGF-alpha immunoreactivity and the number of GST-P-positive hepatocytes. In the medium-term study, EGb treatment during the post-initiation stage failed to reduce the development of DEN-induced GST-P-positive foci. Thus, EGb presented inhibitory actions during initiation but not promotion of rat liver carcinogenesis induced by DEN.
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PMID:Protective effects of Ginkgo biloba against rat liver carcinogenesis. 1836 57

To examine the possible modifying effect of the extract of Siraitia grosvenori (SGE), a naturally occurring antioxidative agent, on piperonyl butoxide (PBO)-promoted hepatocarcinogenesis, male F344 rats were administered a single intraperitoneal injection of N-diethylnitrosamine (DEN) as an initiator followed by administration of a diet containing 2% PBO for 7 weeks with or without SGE (1,000 ppm) in the drinking water. To enhance cellular proliferation, all animals underwent two-thirds partial hepatectomy 1 week after the commencement of PBO administration. Pretreatment with SGE was also applied to the PBO + SGE group for 2 weeks prior to DEN initiation. Liver immunohistochemistry revealed that although the PBO-mediated increase in the number of glutathione S-transferase placental form (GST-P)-positive foci and proliferating cell nuclear antigen-positive cells remained unaltered with SGE coadministration, the area of the GST-P-positive foci was increased. On the contrary, real-time RT-PCR showed that coadministration of SGE increased hepatic GST and glutathione peroxidase (GSH-Px) antioxidant activities and mRNA expression levels of the phase II enzymes that are known to be transcriptionally up-regulated through the Nrf 2-Keap1-antioxidant responsive element (ARE) as well as the phase III enzymes. Furthermore, measurement of thiobarbituric acid-reactive substances showed a decrease in lipid peroxidation by SGE coadministration. The results suggest that SGE may exert hepatic antioxidant activity by up-regulating the genes under the control of the Nrf 2-Keap1-ARE transcriptional machinery; however, this activity was neither effective nor sufficient for suppression of PBO-promoted early hepatocarcinogenesis.
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PMID:Modifying effect of Siraitia grosvenori extract on piperonyl butoxide-promoted hepatocarcinogenesis in rats. 1854 11

It has been suggested that patients with nonalcoholic steatohepatitis (NASH) may have high risk for liver cancer. However, it is unknown whether high-fat diet (HFD) induced NASH promotes hepatocarcinogenesis. In this study, Sprague-Dawley rats were injected with a low dose of hepatic carcinogen diethylnitrosamine (DEN) and then fed either Lieber-DeCarli control diet (CD) or HFD for 6 weeks. Liver histology and the hepatic placental form of glutathione S-transferase (P-GST) positive foci were examined. Expression levels of proliferating cell nuclear antigen (PCNA), cyclinD1, phosphorylated mitogen-activated protein kinase (MAPK) including extracellular signal-regulated kinase (ERK) and p38, as well as tumor necrosis factor-alpha (TNF-alpha), and nuclear factor-kappaB (NF-kappaB) were measured in the liver. Induction of lipid peroxidation end products (malondialdehyde plus 4-hydroxynonenal) in liver and apoptotic hepatocytes were also assessed. Results showed that HFD-fed rats developed significantly higher incidence and multiplicity of P-GST positive foci along with more fat accumulation, infiltration of inflammatory cells and higher lipid peroxidation in the liver, when compared with rats fed the CD. This high prevalence of hepatic lesions in the liver was accompanied by greater PCNA expression and cyclinD1 protein concentration but little change in hepatocyte apoptosis. HFD feeding elevated hepatic phosphorylated ERK but reduced phosphorylated p38 when compared with the CD feeding. In addition, a significantly higher expression of TNF-alpha mRNA and nuclear NF-kappaB p65 protein were observed in HFD group than in CD group. These data clearly demonstrate that NASH induced by HFD promoted DEN-initiated early hepatocarcinogenesis, which was associated with elevated TNF-alpha/NF-kappaB signaling and MAPK related hepatocyte proliferation.
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PMID:Nonalcoholic steatohepatitis induced by a high-fat diet promotes diethylnitrosamine-initiated early hepatocarcinogenesis in rats. 1900 24

Activity of metalloproteinases 2 and 9 (MMP-2 and 9) during promotion and progression of rat liver carcinogenesis was investigated in a modified resistant hepatocyte model. Development of preneoplastic liver lesions positive for glutathione S-transferase 7-7-(GST-P 7-7-positive PNL) and tumors besides hepatocytes positive for proliferating cell nuclear antigen (PCNA) were quantified and compared to MMP-2 and-9 activity using gelatin zymography. Marked increases in GST-P 7-7-positive PNL development, PCNA labeling indices, MMP-2 (pro, intermediate and active forms) and pro-MMP-9 activity were observed after proliferative stimulus induced by 2-acetylaminofluorene (2-AAF) exposure cycles. After 2-AAF withdrawal, increase in MMP-2 activity was detected only in neoplastic mixed lesions, whereas active MMP-9 was increased in both PLN and neoplastic tissues. Our findings suggest that MMP-2 may be associated with proliferative events induced by 2-AAF rather than with selective growth of PNL and that MMP-9 could be associated with progression of PNL and neoplastic mixed lesions.
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PMID:Metalloproteinases 2 and 9 activity during promotion and progression stages of rat liver carcinogenesis. 1905 82

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


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