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Glutathione S-transferase (glutathione + s-transferase)
Terms modified by Glutathione S-transferase Selected AbstractsMolecular dynamics of detoxification and toxin-tolerance genes in brown planthopper (Nilaparvata lugens Stål., Homoptera: Delphacidae) feeding on resistant rice plantsARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2005Zhifan Yang Abstract To investigate the molecular response of brown planthopper, Nilaparvata lugens (BPH) to BPH-resistant rice plants, we isolated cDNA fragments of the genes encoding for carboxylesterase (CAR), trypsin (TRY), cytochrome P450 monooxygenase (P450), NADH-quinone oxidoreductase (NQO), acetylcholinesterase (ACE), and Glutathione S-transferase (GST). Expression profiles of the genes were monitored on fourth instar nymphs feeding on rice varieties with different resistance levels. Northern blot hybridization showed that, compared with BPH reared on susceptible rice TN1, expression of the genes for P450 and CAR was apparently up-regulated and TRY mRNA decreased in BPH feeding on a highly resistant rice line B5 and a moderately resistant rice variety MH63, respectively. Two transcripts of GST increased in BPH feeding on B5; but in BPH feeding on MH63, this gene was inducible and its expression reached a maximum level at 24 h, and then decreased slightly. The expression of NQO gene was enhanced in BPH on B5 plants but showed a constant expression in BPH on MH63 plants. No difference in ACE gene expression among BPH on different rice plants was detected by the RT-PCR method. The results suggest these genes may play important roles in the defense response of BPH to resistant rice. Arch. Insect Biochem. Physiol. 59:59,66, 2005. © 2005 Wiley-Liss, Inc. [source] Biochemical mechanisms of insecticide resistance in the diamondback moth (DBM), Plutella xylostella L. (Lepidopterata: Yponomeutidae), in the Sydney region, AustraliaAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2009Vincent Y Eziah Abstract Following the detection of resistant diamondback moth (DBM) populations to synthetic pyrethroid, organophosphorus and indoxacarb insecticides in the Sydney Basin, a study of the major biochemical mechanisms was conducted to determine the type of resistance in these populations. The activity of cytochrome P450 monooxygenases increased two- to sixfold when compared with the susceptible strain. Up to a 1.9-fold increase in esterase activity in resistant strains compared with the susceptible strain was observed. In vitro inhibition studies showed that profenofos, methamidophos and chlorpyrifos strongly inhibited the esterases while permethrin and esfenvalerate resulted in less than 30% inhibition. Qualitative analysis of the esterases using native polyacrylamide gel electrophoresis showed four bands in both the susceptible and resistant individuals with more intense staining in the resistant individuals. The development of these bands was inhibited by methamidophos and chlorpyrifos pretreatment of the protein extract while permethrin and esfenvalerate did not exhibit this effect. Glutathione S-transferase (GST) activity was significantly higher in two field populations compared with the remaining populations. Overall, the study showed that the mechanisms of insecticide resistance in the DBM populations in the area studied were due to cytochrome P450 monooxygenases, esterase and GSTs, and possibly other non-metabolic mechanisms that were not investigated in the present study. [source] The role and frequency of glutathione s-transferase P1 polymorphism in Iranian patients affected with reflux esophagitisDISEASES OF THE ESOPHAGUS, Issue 7 2010N. Zendehdel SUMMARY Reflux esophagitis is a common complication of the gastroesophageal reflux disease. Glutathione s-transferases (GSTs) have important role in the protection of cells from the products of oxidative stress. GSTP1*B allele has a correlation with susceptibility to several diseases. In this case-control study, the role and frequency of GSTP1 polymorphism was evaluated in Iranian patients with erosive reflux esophagitis. Seventy patients with erosive reflux esophagitis and 75 normal individuals were enrolled in this study. The grade of esophagitis was determined via endoscopy. DNA was extracted from venous blood of each subject using the salting out method. GSTP1 genetic polymorphisms were detected using the polymerase chain reaction restriction fragment length polymorphism method. There was a significant difference in GSTP1 genotype frequency between patients and normal groups (P= 0.006). Also, in the patient group, the grade B of esophagitis was significantly associated with variant GSTP1 genotype (P= 0.028). The rate of throat pain symptom was higher in the no-variant group (P < 0.036). The GSTP1*B allele frequency in Iranian normal groups is similar to Orientals. Reflux esophagitis are more commonly found in variant (*B/*B and *A/*B) GSTP1 genotypes. In addition, GSTP1 polymorphism is correlated with a higher grade of esophagitis. [source] Chronic toxicity and responses of several important enzymes in Daphnia magna on exposure to sublethal microcystin-LRENVIRONMENTAL TOXICOLOGY, Issue 3 2005Wei Chen Abstract In the current study, the toxicological mechanisms of microcystin-LR and its disadvantageous effects on Daphnia magna were examined. Survival rate, number of newborn, activity of several important enzymes [glutathione S-transferase (GST), lactate dehydrogenase (LDH), phosphatases, and glutathione], accumulated microcystins, and ultrastructural changes in different organs of Daphnia were monitored over the course of 21-day chronic tests. The results indicated that low concentrations of dissolved microcystin had no harmful effect on Daphnia. On the contrary, stimulatory effects were detected. In the presence of toxin at high dosage and for long-term exposure, GST and glutathione levels decreased significantly. The decreased enzyme activity in the antioxidant system probably was caused by detoxification reactions with toxins. And these processes of detoxification at the beginning of chronic tests may enable phosphatases in Daphnia magna to withstand inhibition by the toxins. At the same time, we also found that the LDH activity in test animals increased with exposure to microcystin-LR, indicating that adverse effects occurred in Daphnia. With microcystin given at a higher dosage or for a longer exposure, the effect on Daphnia magna was fatal. In the meantime, microcystin began to accumulate in Daphnia magna, and phosphatase activity started to be inhibited. From the ultrastructure results of cells in D. magna, we obtained new information: the alimentary canal may be the target organ affected by exposure of microcystins to D. magna. The results of the current study also suggested that the oxidative damage and PPI (protein phosphatase inhibition) mechanisms of vertebrates also are adapted to Daphnia. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 323,330, 2005. [source] Multimarker approach in transplanted mussels for evaluating water quality in Charentes, France, coast areas exposed to different anthropogenic conditionsENVIRONMENTAL TOXICOLOGY, Issue 5 2003M. Roméo Abstract An active biomonitoring experiment was performed using mussels collected at a clean site, Fier d'Ars, and transplanted to two locations, outside the harbor of La Rochelle and in the Baie de L'Aiguillon along the coast of Charentes (French Atlantic coast) beginning in April for several months. Mussels were collected in June and October. The cadmium, copper, and zinc concentrations of all resident and transplanted mussel samples and the polycyclic aromatic hydrocarbon and polychlorinated biphenyl concentrations in some mussel samples and in the sediment samples were determined. Mussel response was evaluated for several biochemical biomarkers: concentrations of metallothionein, activities of glutathione S-transferase and acetylcholinesterase (AChE) and levels of thiobarbituric reactive substance (TBARS). The physiological status of the animals was assessed using the condition index. A principal component analysis performed with the chemical and biochemical results of the evaluations of the resident and transplanted mussels collected in June allowed them to be separated into three groups: resident mussels from la Rochelle with high metal and TBARS levels, resident mussels from Baie de L'Aiguillon with a very high condition index, and resident mussels from Fier d'Ars and transplanted mussels at La Rochelle and Baie de L'Aiguillon with low TBARS and AChE activities. Strong seasonal variation from June to October of all parameters was noted. Mussels transplanted to La Rochelle appeared to be the most "polluted" in their pollutant concentrations and biochemical responses; moreover, the La Rochelle site had the highest concentration of organics in sediments of all the sites. The choice of Fier d'Ars as a reference site may be questionable because some of the biomarker responses of the mussels were higher than expected there, although these pollutants in mussels and sediment were present at the lowest concentrations measured. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 295,305, 2003. [source] Effects of dietary N -acetylcysteine on the oxidative stress induced in tilapia (Oreochromis Niloticus) exposed to a microcystin-producing cyanobacterial water bloom,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2009María Puerto Abstract Fish can be exposed to toxic cyanobacterial cells in natural waters and fish farms and suffer from oxidative damage. The present study investigates the effects of N-acetylcysteine (NAC), a glutathione (GSH) precursor, on the oxidative stress induced by Microcystis cyanobacterial cells containing microcystins (MCs) in tilapia fish (Oreochromis niloticus). Variation in lipid peroxidation (LPO) levels, carbonyl group content, reduced glutathione to oxidized glutathione ratio (GSH: GSSG), and catalase (Enzyme Commission [EC] 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1), glutathione reductase (GR; EC 1.8.1.7), glutathione peroxidase (GPx; EC 1.11.1.9), and glutathione S-transferase (EC 2.5.1.18) activities in liver and kidney of tilapia exposed to a single oral dose of 120 ,g MC-LR (with leucine [L] and arginine [R])/fish and killed in 24 h were investigated in the absence and presence of 20.0, 44.0, and 96.8 mg NAC/fish/d. Results showed a protective role of NAC, depending on the dose and the biomarker considered. The increase in LPO (1.9-and 1.4-fold in liver and kidney, respectively) and the decreased protein content and GSH:GSSG in the liver induced by MCs were recovered mainly by the lower doses of NAC employed. Antioxidant enzyme activities increased (range, 1.4-to 1.7-fold) by MCs also were ameliorated by NAC, although the highest level used induced significant alteration of some enzymatic activities, such as SOD, GPx, and GR. Thus, NAC can be considered to be a useful chemoprotectant that reduces hepatic and renal oxidative stress in the prophylaxis and treatment of MC-related intoxications in fish when careful attention is given to its application dose because of its own pro-oxidant activity, as shown in the present study at 96.8 mg NAC/ fish/d. [source] High epitope density in a single protein molecule significantly enhances antigenicity as well as immunogenicity: a novel strategy for modern vaccine development and a preliminary investigation about B,cell discrimination of monomeric proteinsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2005Wanli Liu Abstract Although early studies have shown a close correlation between epitope density and epitope-specific humoral immune responses, few attempts have been made to quantitatively compare the antigenic and immunogenic differences between protein molecules bearing low or high degrees of epitope density, nor have studies quantitatively investigated the mechanism of B,cell discrimination of monomeric antigens. In this study, we prepared glutathione S-transferase (GST) fusion proteins bearing various copies of the M2e epitope from the influenza virus M2,protein [GST-(M2e)8, GST-(M2e)4 and GST-(M2e)1], which were used to detect and compare the real-time kinetic binding with M2e-specific mAb by surface plasma resonance. Our data show clearly that fusion proteins bearing higher M2e epitope density resulted in higher average avidity for M2e-specific mAb. Furthermore, it was observed that fusion proteins bearing high M2e epitope density could induce polyclonal antibodies (pAb) with enhanced an average affinity constant (KA) for M2e epitope peptide compared to fusion proteins bearing low epitope density. The average KA of pAb induced by GST-(M2e)8 (3.08 × 108,M,1 or 9.96 × 108,M,1) was up to two orders of magnitude greater than the average KA of pAb induced by GST-(M2e)1 (2.00 × 106,M,1 or 3.43 × 106,M,1). Thus, the data presented here demonstrate that high epitope density in a single protein molecule significantly enhances antigenicity and immunogenicity. These findings enrich our knowledge of how epitope density might relate to the recognition, activation and antibody production processes of epitope-specific immature B,cells. [source] Multi-directional differentiation of doublecortin- and NG2-immunopositive progenitor cells in the adult rat neocortex in vivoEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2007Yasuhisa Tamura Abstract In the adult mammalian brain, multipotent stem or progenitor cells involved in reproduction of neurons and glial cells have been well investigated only in very restricted regions; the subventricular zone of the lateral ventricle and the dentate gyrus in the hippocampal formation. In the neocortex, a series of in vitro studies has suggested the possible existence of neural progenitor cells possessing neurogenic and/or gliogenic potential in adult mammals. However, the cellular properties of the cortical progenitor cells in vivo have not been fully elucidated. Using 5,-bromodeoxyuridine labeling and immunohistochemical analysis of cell differentiation markers, we found that a subpopulation of NG2-immunopositive cells co-expressing doublecortin (DCX), an immature neuron marker, ubiquitously reside in the adult rat neocortex. Furthermore, these cells are the major population of proliferating cells in the region. The DCX(+)/NG2(+) cells reproduced the same daughter cells, or differentiated into DCX(+)/NG2(,) (approximately 1%) or DCX(,)/NG2(+) (approximately 10%) cells within 2 weeks after cell division. The DCX(+)/NG2(,) cells were also immunopositive for TUC-4, a neuronal linage marker, suggesting that these cells were committed to neuronal cell differentiation, whereas the DCX(,)/NG2(+) cells showed faint immunoreactivity for glutathione S-transferase (GST)-pi, an oligodendrocyte lineage marker, in the cytoplasm, suggesting glial cell lineage, and thereafter the cells differentiated into NG2(,)/GST-pi(+) mature oligodendrocytes after a further 2 weeks. These findings indicate that DCX(+)/NG2(+) cells ubiquitously exist as ,multipotent progenitor cells' in the neocortex of adult rats. [source] Identification of the rat adrenal zona fasciculata/reticularis specific protein, inner zone antigen (IZAg), as the putative membrane progesterone receptorFEBS JOURNAL, Issue 7 2001Farah S. Raza Using immunological methods, a protein specific to the inner zones of the rat adrenal cortex, and called inner zone antigen (IZAg), was previously shown to have two interrelated forms of 26 kDa (IZAg1) and 55,60 kDa (IZAg2), and to have an action on steroid hydroxylation. After two-dimensional gel electrophoresis, and immunoaffinity column purification, N-terminal amino-acid analysis showed that the first 12 amino acids were identical to those of a recently described putative membrane located progesterone receptor (PPMR). RT-PCR was then used to generate the cDNA of this protein, using RNA extracted from rat adrenals. A glutathione S-transferase (GST)-fusion construct was expressed in Escherichia coli, and shown to generate an immunoreactive product of molecular mass consistent with its identification as IZAg1. More detailed examination of the distribution of this protein, not only in the zona fasciculata/reticularis of the adrenal cortex, but also in the Leydig cell, kidney and liver, suggest it may have a role in steroid hormone synthesis and/or metabolism. [source] Glutathione depletion in hippocampal cells increases levels of H and L ferritin and glutathione S-transferase mRNAsGENES TO CELLS, Issue 5 2007Nadya Morozova Glutathione plays an essential role in maintaining cellular redox balance, protecting cells from oxidative stress and detoxifying xenobiotic compounds. Glutathione depletion has been implicated in neurodegenerative disorders, including Alzheimer's and Parkinson's diseases. Cells of neuronal origin are acutely sensitive to glutathione depletion, providing an avenue for studying the mechanisms invoked for neuronal survival in response to oxidant challenge. We investigated the changes in mRNA profile in HT22 hippocampal cells following administration of homocysteic acid (HCA), a glutathione-depleting drug. We report that HCA treatment of HT22 murine hippocampal cells increases the levels of the mRNAs encoding at least three proteins involved in protection from oxidant injury, the mRNAs encoding heavy (H) and light (L) ferritin and glutathione S-transferase (GST). [source] Mammalian Mcm2/4/6/7 complex forms a toroidal structureGENES TO CELLS, Issue 5 2003Norikazu Yabuta Background: The Mcm proteins are a family of six homologous proteins (Mcm2,7) that play an important role in DNA replication. They form Mcm4/6/7 and Mcm2/4/6/7 complexes, but their structures are not known. Results: We found that the human Mcm2/4/6/7 tetramer forms a toroidal structure, with a central cavity about 3,4 nm in diameter. Observations were made using electron microscopy, employing the image analysis of single particles. The most predominant averaged image displayed a toroid harbouring four bulges forming corners, one of which was larger than the others. This structure was very similar to the mouse Mcm2/4/6/7 tetramer that was independently prepared and analysed by electron microscopy. These toroidal structures are distinct from that of the Mcm4/6/7 hexamer, which was also examined by electron microscopy. GST(glutathione S-transferase)-pull down and two hybrid experiments suggest that a putative Mcm6-Mcm6 hinge contributes to the formation of the Mcm7/4/6/6/4/7 heterohexamer. Conclusions: The Mcm2/4/6/7 tetramer forms a toroidal structure that is distinct from that of the Mcm4/6/7 hexamer in size and shape. [source] Hepatitis C virus core protein activates ERK and p38 MAPK in cooperation with ethanol in transgenic miceHEPATOLOGY, Issue 4 2003Takeya Tsutsumi In human chronic hepatitis C, alcohol intake is a synergistic factor for the acceleration of hepatocarcinogenesis. Recently, we showed a significant increase of reactive oxygen species (ROS) in hepatitis C virus (HCV) core-transgenic mice fed ethanol-containing diets. Because previous studies indicated that ROS is closely associated with mitogen-activated protein kinases (MAPK), we examined activities of c-Jun N-terminal kinase, p38 MAPK, and extracellular signal-regulated kinase (ERK) in the liver of core-transgenic and nontransgenic mice with short-term ethanol feeding. Activity of ERK and p38 MAPK was increased in core-transgenic mice compared with nontransgenic mice, whereas neither ERK nor p38 MAPK was activated in core-transgenic mice with normal diets. In addition, activity of cyclic-AMP and serum responsive element, downstream pathways of p38 MAPK and ERK, was also increased. Comparison of gene expression profiles by cDNA microarray and real-time PCR revealed that galectin-1, which is associated with cell transformation, was significantly increased in ethanol-fed core-transgenic mice. On the other hand, glutathione S-transferase (GST), which plays a key role in protecting cells from oxidative stress, was decreased. In conclusion, these results suggest that HCV core protein cooperates with ethanol for the activation of some MAPK pathways, and leads to the modulation of several genes, contributing to the pathogenesis of liver disease of HCV- infected patients with high ethanol consumption. (Hepatology 2003;38:820,828). [source] Microarray analysis of acaricide-inducible gene expression in the southern cattle tick, Rhipicephalus (Boophilus) microplusINSECT MOLECULAR BIOLOGY, Issue 6 2008L. Saldivar Abstract Acaricide-inducible differential gene expression was studied in larvae of Rhipicephalus (Boophilus) microplus using a microarray-based approach. The acaricides used were: coumaphos, permethrin, ivermectin, and amitraz. The microarrays contained over 13 000 probes, having been derived from a previously described R. microplus gene index (BmiGI Version 2; Wang et al., 2007). Relative quantitative reverse transcriptase-PCR, real time PCR, and serial analysis of gene expression data was used to verify microarray data. Among the differentially expressed genes with informative annotation were legumain, glutathione S-transferase, and a putative salivary gland-associated protein. [source] Influence of glutathione S-transferase pi and p53 expression on tumor frequency and spectrum in miceINTERNATIONAL JOURNAL OF CANCER, Issue 1 2005Laurent Gate Abstract The role of glutathione S-transferase , (GST,) in tumor development has been previously suggested; however the exact function of this enzyme in carcinogenesis remains unclear. GST, has been identified as a modulator of cell signaling by interacting with and inhibiting c-Jun N-terminal kinase (JNK). This kinase has been in turn described as a regulator of p53 stability and transcriptional activity. To study the possible interaction between GST, and p53, we crossed GST,-deficient animals with p53,/, mice. Double knock out animals were viable but developed tumors within 6 months of age; the life span of these animals was however similar to that of GST,+/,/p53,/, and GST,+/+/p53,/,. Mice heterozygous for p53 lived significantly longer than the p53,/, animals and developed tumors much later, and the expression of GST, did not significantly modify the life span of the animals. In contrast, in a wild-type p53 background, GST,,/, mice developed tumors with a significantly higher frequency than heterozygous and wild-type animals with a median tumor free life span 20 weeks shorter. In addition, in p53+/+ background, one third of the GST,,/, animals developed lung adenomas, while less than 10% of GST,+/, and GST,+/+ presented such tumors. GST, expression did not alter the expression of tumorigenesis markers such as COX-2 or ornithine decarboxylase in response to phorbol ester. Furthermore, GST,-deficient mouse embryo fibroblasts were more sensitive to H2O2 -induced apoptosis. P53,/, cells, independent of GST, status, were more sensitive to UV and other DNA damaging agents than their wild-type counterparts. These results suggest that GST, may play a protective role in the development of spontaneous tumors. [source] Studies on some enzymes involved in insecticide resistance in fenitrothion-resistant and -susceptible strains of Musca domestica L. (Dipt, Muscidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 9 2002S. Ahmed Co-administration of fenitrothion with three synergists, namely piperonyl butoxide (PBO), tributylphosphorotrithioate (DEF) and diethyl maleate (DEM) was investigated, respectively, at 1 : 5, 1 : 5 and 1 : 10 ratio. This co-administration of fenitrothion with PBO, DEF and DEM caused a decrease in the doses which produced 50% lethality (LD50s) in 571ab but had no synergistic effect on fenitrothion toxicity was observed in the Cooper strain. The effect of topical application of fenitrothion alone and in combination with PBO, DEF and DEM at the LD50 level on some enzyme activities in 571ab and Cooper strains was examined. The application of fenitrothion alone and in combination with DEF and DEM at LD50 level caused a significant decrease in activities of total esterases, acetylcholinesterase (AChE) and glutathione S-transferase (GST) in the 571ab strain. The decrease in GST activity was not significant in treated flies of the Cooper strain when compared with GST activity of control flies. A non-significant effect on total cytochrome P450 level was observed with fenitrothion alone and the fenitrothion + PBO treatment. No increase in activity level of total esterases, AChE and GST was found, which might suggest that changes in activity level of these enzymes are not related to fenitrothion resistance in the 571ab strain. [source] Inhibition by Cu2+ and Cd2+ of a mu-class glutathione S-transferase from shrimp Litopenaeus vannameiJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2010Alex J. Salazar-Medina Abstract Glutathione S -transferases (GSTs) are a family of detoxifying enzymes that catalyze the conjugation of glutathione (GSH) to electrophiles, thereby increasing the solubility of xenobiotics and aiding its excretion from the cell. The present work presents the inhibition of a mu-class GST of the marine shrimp Litopenaeus vannamei by copper (Cu2+) and cadmium (Cd2+). The protein was overexpressed in bacteria and its enzymatic activity measured using 1-chloro-2,4-dinitrobenzene. The mean inhibitory concentration (IC50) for shrimp GST against Cu2+ was 4.77 ,M and for Cd2+ was 0.39 ,M. A molecular model of the protein based on the crystal structure of a maize GST bound to cadmium showed that the metal binds in the GSH-binding site by coordination with Asp and Gln residues. These results are consistent with the experimental data and suggest that sublethal concentration of metals may affect the capacity of the organism to detoxify pesticides or xenobiotics. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:218,222, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.20326 [source] Changes in expression and activity of glutathione S -transferase in different organs of schistosoma haematobium -infected hamsterJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 3 2003S. A. Sheweita Abstract Schistosomiasis is a major health problem in many subtropical developing countries, causing a number of serious pathologies, including bladder cancer. Most of the toxic compounds formed as a result of these infestations are derived either exogenously or formed endogenously and can be conjugated with glutathione (GSH) via glutathione S-transferase (GST). The present study investigates the effect of Schistosma haematobium infection on the activity of GST and glutathione reductase (GR) and levels of glutathione and free radicals (measured as thiobarbituric acid reactive substances) in different organs of the male hamster. The total activity of GST was increased in several organs; in kidney by 50 and 46% at 6 and 10 weeks postinfection, respectively, and in bladder tissues by 169, 23, and 130% at 2, 4, and 6 weeks postinfection, respectively. In support of this, the expression of GST isozymes was also induced in kidney and bladder tissues at early stages (2, 4, and 6 weeks) and reduced at the later stages of infection (8 and 10 weeks). In contrast, the expression of these isozymes was decreased in the spleen and liver at 2, 4, 6, 8, and 10 weeks postinfection. Also, such activity was decreased in lungs by 74 and 78% and in bladders by 65 and 72% at 8 and 10 weeks postinfection, respectively. GSH levels increased in lungs by 95, 40, and 56% at 2, 4, and 6 weeks and in spleen by 26 and 74% at 4 and 6 weeks, respectively, but decreased at later stages of S. haematobium infection in these organs. The depletion of GSH levels also occurred in bladders by 72 and 54% at 8 and 10 weeks postinfection, respectively. The activity of GR was increased in the livers, lungs, and kidneys of the S. haematobium -infected hamster. TBARS also increased in the lung by 14, 65, 53, 828, and 624% and in the kidney by 64, 29, 87, 190, and 111%, and in the bladder by 216, 23, 1468, 528, and 1025% at 2, 4, 6, 8, and 10 weeks postinfection, respectively. This study indicates that low GST expression and high levels of free radicals could provide new evidence for damage to the bladder and other organs as a result of S. haematobium infection. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:138,145, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10071 [source] Effects of benzo[a]pyrene on tissue activities of metabolizing enzymes and antioxidant system in normal and protein-malnourished ratsJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 2 2003Osama A. Badary Abstract The effects of benzo[a]pyrene (B[a]P) on some drug-metabolizing and antioxidant systems in liver, lung, and stomach were investigated in normal and protein malnutrition (PM) rats. PM significantly inhibited tissue glutathione (GSH) content and increased hepatic lipid peroxidation. Cytochrome P450 isoform CYP1A1 was significantly increased in various tissues (42,73%). Also, lung glutathione S-transferase (GST) activity was significantly decreased (19%) in PM rats. On the other hand, B[a]P significantly induced tissue GSH of control and PM rats. Also, hepatic lipid peroxidation were significantly increased in control rats treated with B[a]P. Superoxide dismutase (SOD) activity was decreased by B[a]P treatment in PM rat stomach. B[a]P significantly induced both quinone reductase (QR) (in all tissues) and hepatic GST of control and PM rats. GST activity in PM rat liver was significantly higher than that of control rat liver after B[a]P treatment. Also, B[a]P induced hepatic CYP1A1 by 32-fold and 27-fold (P , 0.05) in control and PM rats, respectively. Stomach and hepatic UDP-glucuronosyltransferase activities were significantly decreased (34%) and increased (74%), respectively by B[a]P in PM rats. The results suggest that PM status has a modifying effect on the response of some antioxidant and metabolizing systems to a well-known carcinogen risk. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:86,91, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10064 [source] Cloning, Sequencing, and Functional Characterization of the Rat Homologue of Receptor Activator of NF-,B Ligand,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 11 2000Jiake Xu Abstract A complementary DNA (cDNA) encoding the rat homologue of receptor activator of NF-,B ligand/osteoprotegerin ligand/osteoclast differentiation factor/tumor necrosis factor (TNF)-related activation-induced cytokine (RANKL/OPGL/ODF/TRANCE) was cloned and sequenced from tibias of ovariectomized (OVX) rats. The predicted amino acid sequence of rat RANKL (rRANKL) has 84% and 96% identity to that of human and mouse RANKL, respectively, and 35% and 37% similarity to that of human and mouse TNF-related apoptosis-inducing ligand (TRAIL), respectively. RANKL transcripts were expressed abundantly in the thymus and bone tissues of OVX rats. rRANKL has a single hydrophobic region between residues 53 and 69, which is most likely to serve as a transmembrane domain. The long C-terminal region containing ,-sheet-forming sequences of the TNF-like core is considered the extracellular region. Three truncated domains within the TNF-like core region were expressed as glutathione S-transferase (GST) fusion proteins and investigated for their ability to induce osteoclastogenesis. The results showed that GST-rRANKL (aa160-318) containing the full TNF-like core region had the highest capability to induce the formation of osteoclast-like cells from RAW264.7 cells. GST-rRANKL (aa239-318 and aa160-268) had lesser degrees of osteoclast inductivity. Furthermore, the GST-rRANKL (aa160-318) is capable of (1) inducing osteoclast formation from rat spleen cells in the presence of macrophage colony-stimulating factor (M-CSF), (2) stimulating mature rat osteoclast polarization and bone resorption ex vivo, and (3) inducing systemic hypercalcemia in vivo; thus the full TNF-like core region of rRANKL is an important regulator of calcium homeostasis and osteoclastic function. [source] Inhibition of apoptosis by progesterone in cardiomyocytesAGING CELL, Issue 5 2010Stephen Morrissy Summary While gender-based differences in heart disease have raised the possibility that estrogen (ES) or progesterone (PG) may have cardioprotective effects, recent controversy regarding hormone replacement therapy has questioned the cardiac effects of these steroids. Using cardiomyocytes, we tested whether ES or PG has protective effects at the cellular level. We found that PG but not ES protects cardiomyocytes from apoptotic cell death induced by doxorubicin (Dox). PG inhibited apoptosis in a dose-dependent manner, by 12 ± 4.0% at 1 ,m and 60 ± 1.0% at 10 ,m. The anti-apoptotic effect of PG was also time dependent, causing 18 ± 5% or 62 + 2% decrease in caspase-3 activity within 1 h or 72 h of pretreatment. While PG causes nuclear translocation of its receptor within 20 min, the cytoprotective effect of PG was canceled by mifepristone (MF), a PG receptor antagonist. Analyses using Affymetrix high-density oligonucleotide array and RT-PCR found that PG induced Bcl-xL, metallothionine, NADPH quinone oxidoreductase 1, glutathione peroxidase-3, and four isoforms of glutathione S-transferase. Western blot analyses revealed that PG indeed induced an elevation of Bcl-xL protein in a dose- and time-dependent manner. Nuclear run-on assay indicated that PG induced Bcl-xL gene transcription. Inhibiting the expression of Bcl-xL using siRNA reduced the cytoprotective effect of PG. Our data suggests that PG induces a cytoprotective effect in cardiomyocytes in association with induction of Bcl-xL gene. [source] ANTIOXIDANT ACTIVITIES AND HYPOLIPIDEMIC EFFECTS OF AN AQUEOUS EXTRACT FROM FLOWER BUDS OF CLEISTOCALYX OPERCULATUS (ROXB.) MERR.JOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2009AND PERRY ABSTRACT The antioxidant activities and hypolipidemic effects of aqueous extract from Cleistocalyx operculatus flower buds (COB) (Roxb.) Merr. and Perry, a commonly used material for drink preparation in Vietnam, were investigated in vitro and in diabetic rats. In vitro, the aqueous extract of COB which has highest phenolic and flavonoid contents showed a strong antioxidant effect and highest pancreatic lipase inhibitory activity when compared with green tea and guava leaf extracts. Oral administration of aqueous extract from COB (500 mg/kg body weight/day) on streptozotocin-induced diabetic rats for 8 weeks resulted in significant reduction in the levels of glucose, total cholesterol and triglyceride in plasma as well as the concentration of glucose and sorbitol in the lens. In addition, COB showed significant recovery in the activities of antioxidant enzymes (superoxide dismutase, glutathione S-transferase) and glutathione level in liver with markedly decrease in the lipid peroxide level in liver and lens of the COB-treated diabetic rats. These results indicated that COB showed antioxidant activities, prevention of sorbitol accumulation in lens and hypolipidemic effects in addition to its antidiabetic effects and may be considered as a promising material for the prevention of diabetic complications and metabolic syndrome. PRACTICAL APPLICATIONS In recent years, research on traditional medicinal plants for the management of diabetes has attracted the interest of medical scientists. A suitable plant material for antidiabetes and prevention of diabetic complications should possess various biological components, such as antihyperglycemia, antioxidant activities and antihyperlipidemia, without side effects. In this study, the aqueous extract from Cleistocalyx operculatus flower buds (COB) with high polyphenolic and flavonoid content has shown beneficial biological functions in vitro and in diabetic rats, including antioxidant activity, hypolipidemic and hypoglycemic effects. The results of our study suggest that COB might have a potential role in the management of the prediabetic state and the prevention of diabetic complications. Therefore, there is the possibility for the development of C. operculatus as a beverage for the prevention of diabetes, as well as the prevention of the metabolic syndrome. [source] Association of Caspr/paranodin with tumour suppressor schwannomin/merlin and ,1 integrin in the central nervous systemJOURNAL OF NEUROCHEMISTRY, Issue 2 2003Natalia Denisenko-Nehrbass Abstract Caspr/paranodin is an essential neuronal component of paranodal axoglial junctions, associated with contactin/F3. Its short intracellular domain contains a conserved motif (GNP motif) capable of binding protein 4.1 domains [FERM domains (four point one, ezrin, radixin, moesin)]. Schwannomin/merlin is a tumour suppressor expressed in many cell types, including in neurons, the function and partners of which are still poorly characterized. We show that the FERM domain of schwannomin binds to the paranodin GNP motif in glutathione S-transferase (GST)-pull down assays and in transfected COS-7 cells. The two proteins co-immunoprecipitated in brain extracts. In addition, paranodin and schwannomin were associated with integrin ,1 in transfected cells and in brain homogenates. The presence of paranodin increased the association between integrin ,1 and schwannomin or its N-terminal domain, suggesting that the interactions between these proteins are interdependent. In jimpy mutant mice, which display a severe dysmyelination with deficient paranodal junctions, the interactions between paranodin, schwannomin and integrin ,1 were profoundly altered. Our results show that schwannomin and integrin ,1 can be associated with paranodin in the central nervous system. Since integrin ,1 and schwannomin do not appear to be enriched in paranodes they may be quantitatively minor partners of paranodin in these regions and/or be associated with paranodin at other locations. [source] Epidemiology of Intracranial StenosisJOURNAL OF NEUROIMAGING, Issue S1 2009M. Fareed K. Suri MD ABSTRACT Intracranial stenosis is a common etiology for ischemic stroke. Due to limitations of imaging studies, there are limited data on the prevalence of symptomatic and asymptomatic intracranial stenosis. Intracranial stenosis is more prevalent in Asian, Hispanic, and African-American populations. The reported proportion of patients with symptomatic intracranial stenosis among those hospitalized for ischemic cerebral events varies from 1% in non-Hispanic whites to as high as 50% in Asian populations. In population-based studies, the estimated prevalence of symptomatic intracranial disease varies from 1 in 100,000 for whites to 15 in 100,000 in African Americans. A Chinese population-based study reported intracranial stenosis in 7% of the population aged more than 40 years. Autopsy studies have noted intracranial atherosclerotic disease in about 23% of population in the 6th decade and 80% of population in the 9th decade of life. Angiotensin-converting enzyme polymorphisms, plasma endostatin/vascular endothelial growth factor ratio, glutathione S-transferase omega-1 gene polymorphism, and plasma homocysteine levels are non-modifiable risk factors noted to be associated with intracranial stenosis. Hypertension and serum lipid profile are major modifiable risk factors, whereas sickle cell disease is an uncommon risk factor that can be managed to reduce risk. Associations of intracranial atherosclerosis with diabetes mellitus, metabolic syndrome, Alzheimer's disease, aortic plaques, radiotherapy, and meningitis are less well documented. [source] Intracellular glutathione mediates the denitrosylation of protein nitrosothiols in the rat spinal cordJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2009Jorge M. Romero Abstract Protein S-nitrosothiols (PrSNOs) have been implicated in the pathophysiology of neuroinflammatory and neurodegenerative disorders. Although the metabolically instability of PrSNOs is well known, there is little understanding of the factors involved in the cleavage of S-NO linkage in intact cells. To address this issue, we conducted chase experiments in spinal cord slices incubated with S-nitrosoglutathione (GSNO). The results show that removal of GSNO leads to a rapid disappearance of PrSNOs (t½ , 2 hr), which is greatly accelerated when glutathione (GSH) levels are raised with the permeable analogue GSH ethyl ester. Moreover, PrSNOs are stable in the presence of the GSH depletor diethyl maleate, indicating that GSH is critical for protein denitrosylation. Inhibition of GSH-dependent enzymes (glutathione S-transferase, glutathione peroxidase, and glutaredoxin) and enzymes that could mediate denitrosylation (alcohol dehydrogense-III, thioredoxin and protein disulfide isomerase) do not alter the rate of PrSNO decomposition. These findings and the lack of protein glutathionylation during the chase indicate that most proteins are denitrosylated via rapid transnitrosylation with GSH. The differences in the denitrosylation rate of individual proteins suggest the existence of additional structural factors in this process. This study is relevant to our recent discovery that PrSNOs accumulate in the central nervous system of patients with multiple sclerosis. © 2008 Wiley-Liss, Inc. [source] Synergistic effects of nicotine on arecoline-induced cytotoxicity in human buccal mucosal fibroblastsJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 8 2001Yu-Chao Chang Abstract: Areca quid chewing has been linked to oral submucous fibrosis and oral cancer. Arecoline, a major areca nut alkaloid, is considered to be the most important etiologic factor in the areca nut. In order to elucidate the pathobiological effects of arecoline, cytotoxicity assays, cellular glutathione S-transferase (GST) activity and lipid peroxidation assay were employed to investigate cultured human buccal mucosal fibroblasts. To date, there is a large proportion of areca quid chewers who are also smokers. Furthermore, nicotine, the major product of cigarette smoking, was added to test how it modulated the cytotoxicity of arecoline. At a concentration higher than 50 ,g/ml, arecoline was shown to be cytotoxic to human buccal fibroblasts in a dose-dependent manner by the alamar blue dye colorimetric assay (P<0.05). In addition, arecoline significantly decreased GST activity in a dose-dependent manner (P<0.05). At concentrations of 100 ,g/ml and 400 ,g/ml, arecoline reduced GST activity about 21% and 46%, respectively, during a 24 h incubation period. However, arecoline at any test dose did not increase lipid peroxidation in the present human buccal fibroblast test system. The addition of extracellular nicotine acted synergistically on the arecoline-induced cytotoxicity. Arecoline at a concentration of 50 ,g/ml caused about 30% of cell death over the 24 h incubation period. However, 2.5 mM nicotine enhanced the cytotoxic response and caused about 50% of cell death on 50 ,g/ml arecoline-induced cytotoxicity. Taken together, arecoline may render human buccal mucosal fibroblasts more vulnerable to other reactive agents in cigarettes via GST reduction. The compounds of tobacco products may act synergistically in the pathogenesis of oral mucosal lesions in areca quid chewers. The data presented here may partly explain why patients who combined the habits of areca quid chewing and cigarette smoking are at greater risk of contracting oral cancer. [source] Dose-response efficacy of caraway (Carum carvi L.) on tissue lipid peroxidation and antioxidant profile in rat colon carcinogenesisJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 8 2006Muthaiyan Kamaleeswari Colon cancer is a leading cause of cancer death and its prevention is of great interest throughout the world. This study was conducted to examine the efficacy of different doses of dietary caraway (Carum carvi L.) on tissue lipid peroxidation (LPO) and antioxidant profile in rat colon carcinogenesis. Wistar male rats were divided into 6 groups and were fed a modified pellet diet for the whole of 30 weeks. To induce colon cancer, rats were given a weekly subcutaneous injection of 1,2-dimethylhydrazine (DMH) at a dose of 20 mg kg,1 (based on body weight) for the first 15 weeks. Caraway was supplemented every day orally at doses of 30, 60 and 90 mg kg,1 for different groups of rats for the total period of 30 weeks. All rats were sacrificed at the end of 30 weeks, the colons were examined visually for masses and were subsequently evaluated histologically. The results showed diminished levels of intestinal, colonic and caecal LPO products, such as conjugated dienes (CD), lipid hydroperoxides (LOOH) and thiobarbituric acid reactive substances (TBARS) and also the antioxidants superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and glutathione reductase (GR) in DMH treated rats, which were significantly reversed (P < 0.05) on caraway supplementation. Moreover, enhanced activity of intestinal, colonic and caecal glutathione peroxidase (GPx), glutathione S-transferase (GST) and colonic ascorbic acid and ,-tocopherol levels were observed in carcinogen-treated rats, which were significantly (P < 0.05) reduced on caraway supplementation. Thus, our study showed that caraway supplementation at a dose of 60 mg kg,1 had a modulatory role on tissue LPO, antioxidant profile and prevented DMH-induced histopathological lesions in colon cancer rats. [source] Changes in brain biogenic amines and haem biosynthesis and their response to combined administration of succimers and Centella asiatica in lead poisoned ratsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2006Geetu Saxena This study was designed to investigate the therapeutic potential of meso 2,3-dimercaptosuccinic acid (DMSA) and one of its monoesters, monoisoamyl DMSA (MiADMSA), individually or when administered in combination with an extract of Centella asiatica against experimental lead intoxication in rats. Biochemical variables indicative of alterations in the central nervous system and haem biosynthesis were investigated to determine the toxicity in male Wistar rats. Thirty five rats were exposed to 0.2% lead acetate for 10 weeks, followed by 10 days of treatment with DMSA and MiADMSA (50 mg kg,1, i.p., once daily) alone and in combination with C. asiatica (200 mg kg,1, p.o., once daily). Biochemical variables indicative of oxidative stress and brain biogenic amines, along with lead concentration in blood and brain, were measured. Lead exposure caused a significant depletion of blood and brain ,-aminolevulinic acid dehydratase (ALAD) activity, an important enzyme of the haem biosynthesis pathway, and glutathione (GSH) level. These changes were accompanied by a marked increase in reactive oxygen species (ROS) level, thiobarbituric acid reactive substances (TBARS), ,-aminolevulinic acid synthase (ALAS) and oxidized glutathione (GSSG) activity in blood and brain. Significant depletion of brain noradrenaline (norepinephrine, NE), 5-hydroxytryptamine (5-HT), dopamine (DA) and acetylcholinesterase (AChE) also were observed following lead exposure. Also seen was a significant depletion in brain glutathione peroxidase (GPx), glutathione S-transferase (GST) and monoamine oxidase activity, as well as blood and brain superoxide dismutase (SOD) activity. These biochemical changes were correlated with an increased uptake of lead in blood and brain. Combined administration of MiADMSA and C. asiatica was most effective in reducing these alterations, including biogenic amines, besides reducing body lead burden, compared with individual treatment with MiADMSA. Certain other biochemical variables responded favourably to combination therapy and monotherapy with MiADMSA. Thus, supplementation of C. asiatica during chelation could be recommended for achieving optimum effects of chelation therapy. [source] In-vitro effect of flavonoids from Solidago canadensis extract on glutathione S-transferaseJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2006Pál Apáti Solidago canadensis is typical of a flavonoid-rich herb and the effect of an aqueous ethanol extract on glutathione-S-transferase (GST) activity using HepG2 cells was compared with those of the flavonol quercetin and its glycosides quercitrin and rutin, found as major constituents. The composition of the extract was determined by HPLC and rutin was found to be the major flavonoidal component of the extract. Total GST activity was assessed using 1-chloro-2,4-dinitrobenzene as a substrate. The glycosides rutin and quercitrin gave dose-dependent increases in GST activity, with a 50% and 24.5% increase at 250 mm, respectively, while the aglycone quercetin inhibited the enzyme by 30% at 250 mm. The total extract of the herb gave an overall dose-dependent increase, the fractions corresponding to the flavonoids showed activating effects while those containing caffeic acid derivatives were inhibitory. The activity observed corresponds to that reported for similar compounds in-vivo using rats, thus the HepG2 cell line could serve as a more satisfactory method of assessing the effects of extracts and compounds on GST. [source] Assessment of carcinogenic potential of repeated fish fried oil in miceMOLECULAR CARCINOGENESIS, Issue 10 2006Manoj K. Pandey Abstract Our prior studies have shown that single topical treatment of repeated fish fried oil extract (RFFE), containing various polycyclic aromatic hydrocarbons (PAHs), to the dorsal epidermis of mice caused enhancement of DNA damage along with higher expression of p53 and p21WAF1 proteins and cell-cycle arrest. In the present study carcinogenic potential of repeated fish fried oil (RFFO) and RFFE was assessed. Single topical application of RFFO (100 µL/animal) and RFFE (100,500 µg/animal) to Swiss albino female mice resulted in significant induction (1.8- to 7.4-fold) of ornithine decarboxylase activity. Twice weekly topical application of methylcholanthrene (MCA) for 24 wk or single topical application of 7,12-dimethylbenzanthracene (DMBA) or RFFO or RFFE, as initiator followed by twice weekly application of 12-O-tetradecanoyl phorbol myristate acetate (TPA) as promoter for 24 wk, resulted in development of skin papillomas after 6, 7, 18, and 9 wk, respectively. The cumulative number of tumors in MCA, DMBA/TPA, RFFE (200 µg)/TPA, and RFFE (500 µg)/TPA groups were 276, 168, 34, and 58 after 24 wk while negligible or minimal initiating activity was noticed in RFFO/TPA group. No tumors were found in animals either given twice weekly topical application of RFFO or a single initiating dose of DMBA followed by twice weekly application of RFFO. Histopathology of skin of animals treated with RFFE/TPA showed marked proliferation of epidermal layers along with abnormal mitosis and multinucleated tumor appearance. Skin of animals in groups RFFO/TPA and DMBA/RFFO showed sloughing and regeneration of epidermal layers, oedema along with proliferation of fibroblasts. Histochemical localization of ,-glutamyl transpeptidase was found to be substantially higher in skin of mice treated with RFFO/TPA and RFFE/TPA. Animals treated with RFFO/TPA, DMBA/RFFO, and RFFE/TPA resulted in significant induction of cutaneous aryl hydrocarbon hydroxylase (AHH) (421,432%), ethoxyresorufin-O-deethylase (252,316%), and glutathione S-transferase (133,245%) activities. Animals treated with RFFO/TPA, DMBA/RFFO, and RFFE/TPA led to significant reduction in glutathione content (39,44%) with a concomitant increase in lipid peroxidation (254,492%). Animals treated with RFFO/TPA and RFFE/TPA led a significant decrease in catalase (43,69%) and superoxide dismutase (20,31%) activities while glutathione reductase activity was found to be diminished (23,51%) in RFFO, RFFO/TPA, DMBA/RFFO, and RFFE/TPA treated groups. These results suggest that RFFE possess skin tumor initiating activity and that it may have weak promoting activity as well, which may involve free radicals. © 2006 Wiley-Liss, Inc. [source] Sequential changes in hepatocarcinogenesis induced by diethylnitrosamine plus thioacetamide in Fischer 344 rats: Induction of gankyrin expression in liver fibrosis, pRB degradation in cirrhosis, and methylation of p16INK4A exon 1 in hepatocellular carcinomaMOLECULAR CARCINOGENESIS, Issue 3 2001Tae Jun Park Abstract To clarify the sequential changes in pRB and p16 during different stages of hepatocarcinogenesis such as fibrosis, cirrhosis, hepatocellular adenoma (HCA), and hepatocellular carcinoma (HCC), male Fischer 344 rats were singly injected with diethylnitrosamine (DEN), immediately followed with phenobarbital for 1 wk and then thioacetamide (TAA) for 39 wk in drinking water. Rats were killed at 9, 20, 30, and 40 wk after DEN initiation and changes of pRB level, p16 gene hypermethylation, and in vivo gankyrin expression were examined. Histologic examination showed stepwise appearances of fibrosis, cirrhosis, HCA, and HCC at weeks 9, 20, 30, and 40, respectively. Hypermethylation of p16 exon 1 was not found until HCA but appeared in 50% of the rats with HCC accompanied by complete loss of its mRNA expression. The amount of glutathione S-transferase,gankyrin bound to pRB and pRB degradation in the liver depended on the concentration of gankyrin and incubation time. Gankyrin expression preceded pRB degradation in liver cirrhosis. In conclusion, gankyrin expression induced in liver fibrosis accelerated the degradation of pRB during liver cirrhosis, and inactivation of p16 exon 1 by DNA hypermethylation occurred during the progression of tumor cells to poorly differentiated HCC. Inactivation of pRB and/or p16 resulted in complete loss of regulation in the cell-division cycle during early and late stages, respectively, of hepatocarcinogenesis. Mol. Carcinog. 30:138,150, 2001. © 2001 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||