Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Betel-nut (BN) chewing related oral mucosal lesions are potential hazards to a large population worldwide. Genotoxicity of betel alkaloids, polyphenol and tannin fractions have been reported. It has been shown earlier that BN ingredients altered the level of endogenous glutathione (GSH) which could modulate the host susceptibility to the action of other chemical carcinogens. The north-east Indian variety of BN, locally known as 'kwai', is raw, wet and consumed unprocessed with betel-leaf and slaked lime and contains higher alkaloids, polyphenol and tannins as compared to the dried one. Therefore, the purpose of this study was to investigate the extent of DNA damage, pattern of cell kinetics, the level of p53-protein and endogenous GSH in kwai chewers in the tribal population of Meghalaya state in the northeastern region of India with an aim to see whether these end-points could serve as biomarkers of genetic damage of relevance for genotoxic/carcinogenic process. The present data show higher DNA damage, delay in cell kinetics, p53 expression and lower GSH-level in heavy chewers (HC) than nonchewers (NC). The influence of bleomycin (BLM) on chromatid break induction in G2-phase of peripheral blood lymphocytes in NC and HC has been analysed to determine individual susceptibility to carcinogenic assaults. HC showed higher induction of chromatid breaks than NC. Risk assessment in this study suggests an interaction between carcinogen exposure and mutagen sensitivity measures, risk estimates being higher in those individuals who both consume kwai and express sensitivity to free radical oxygen damage in vitro. From this study it seems that besides cytogenetical parameters, the level of endogenous GSH and the level of p53 protein could act as effective biomarkers for kwai chewers.
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PMID:The usefulness of cytogenetic parameters, level of p53 protein and endogenous glutathione as intermediate end-points in raw betel-nut genotoxicity. 1292 26

Anaesthetics have gained a lot of attention for their potential mutagenic/carcinogenic effects. In the present study we have investigated the genotoxicity of the inhalation anaesthetic sevoflurane on DNA of lymphocytes isolated from 20 patients undergoing orthopaedic surgery. The genotoxicity of the anaesthetic was studied by assaying DNA damage, apoptosis, DNA repair enzyme activity and GSH content in peripheral lymphocytes before, 15 min after anaesthesia and 24 h after surgery. Lymphocytes isolated 15 min after anaesthesia showed an increase in oxidized purine and pyrimidine bases without DNA strand break formation. DNA strand breaks occurred on the first post-operative day, associated with an enhancement of DNA repair activity and a decrease in GSH. Formation of strand breaks could be the consequence of DNA repair activity. In fact, at 24 h after surgery most of the oxidized DNA bases were repaired. When DNA damage was not repaired, activation of the cell cycle checkpoint protein p53 could lead to apoptosis. An altered redox status may contribute to lymphocytopenia due to an apoptotic event as a consequence of surgical trauma. The presence of apoptotic cells at 1 day after surgery could support the hypothesis that highly damaged peripheral lymphocytes are committed to undergo programmed cell death if the damage is not repaired. In conclusion, the actual risk from anaesthesia is presumably extremely small. However, these findings contribute to our understanding of the regulation of DNA damage/repair and cell death.
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PMID:Lymphocyte DNA damage precedes DNA repair or cell death after orthopaedic surgery under general anaesthesia. 1296 Apr 10

Green fluorescent protein (GFP) is employed as a selection marker for gene transduction and to track tumor cells. Transduction of enhanced GFP (eGFP) into human neuroblastoma cell lines via a lentiviral vector significantly sensitized CHLA-20 (wild-type and functional TP53), and to a lesser extent CHLA-90 cells (multidrug-resistant, mutant, and nonfunctional TP53) to carboplatin, doxorubicin, etoposide, or melphalan, relative to cells transduced using the cell surface antigen CD80 as a selection marker. Total glutathione (GSH) was significantly up-regulated (1.8- to 2.8-fold) after eGFP (but not CD80) transduction in cell lines with, but not in those lacking, functional p53. Cytotoxicity of GSH depletion by buthionine sulfoximine in CHLA-20 (but not in CHLA-20-eGFP) was diminished by hypoxia (2% O(2)). Thus, oxidative stress produced by GFP selects for cells with up-regulated GSH in a p53-dependent manner, and also enhanced the cytotoxicity of anticancer drugs in neuroblastoma cell lines. Our data suggest caution when employing GFP-transduced cells to assess drug sensitivity and that using a cell surface antigen as a selection marker for gene transduction may perturb cells less than GFP.
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PMID:Transduction of green fluorescent protein increased oxidative stress and enhanced sensitivity to cytotoxic drugs in neuroblastoma cell lines. 1455 10

Polyozellus multiplex, a Korean wild mushroom, was extracted using methanol, and the extract was further fractionated with water and ethylacetate. Assay of each fraction with MTT revealed significant tumoristatic effects of the water fraction of Polyozellus multiplex against human gastric and other cancer cells but not normal human lymphocytes. Modifying effects of the water fraction on glandular stomach mucosa were investigated in male Wistar rats treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The dietary 0.5% or 1% water fraction of Polyozellus multiplex significantly increased glutathione S-transferase (GST) and superoxide dismutase (SOD) activities, and showed a tendency for increase in glutathione (GSH) levels, compared to the MNNG alone group. It also caused a significant reduction in proliferating cell nuclear antigen (PCNA)-labeling index of the glandular stomach epithelium, along with increase in p53 tumor suppressor gene expression. These results suggest that Polyozellus multiplex is a candidate for chemoprevention against gastric cancer.
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PMID:Polyozellus multiplex, a Korean wild mushroom, as a potent chemopreventive agent against stomach cancer. 1456 27

Drug resistance, intrinsic or acquired, is a problem for all chemotherapeutic agents. In this review, we examine numerous strategies that have been tested or proposed to reverse drug resistance. Included among these strategies are approaches targeting the apoptosis pathway. Although the process of apoptosis is complex, it provides several potential sites for therapeutic intervention. A variety of targets and approaches are being pursued, including the suppression of proteins inhibiting apoptosis using antisense oligonucleotides (ASOs), and small molecules targeted at proteins that modulate apoptosis. An alternate strategy is based on numerous studies that have documented methylation of critical regions in the genome in human cancers. Consequently, efforts have been directed at re-expressing genes, including genes that affect drug sensitivity, using 5-azacytidine and 2'-deoxy-5-azacytidine (DAC, decitabine) as demethylating agents. While this strategy may be effective as a single modality, success will most likely be achieved if it is used to modulate gene expression in combination with other modalities such as chemotherapy. At a more basic level, attempts have been made to modulate glutathione (GSH) levels. Owing to its reactivity and high intracellular concentrations, GSH has been implicated in resistance to several chemotherapeutic agents. Several approaches designed to deplete intracellular GSH levels have been pursued including the use of buthionine-(S,R)-sulfoxime (BSO), a potent and specific inhibitor of gamma-glutamyl cysteine synthetase (gamma-GCS), the rate-limiting step in the synthesis of GSH, a hammerhead ribozyme against gamma-GCS mRNA to downregulate specifically its levels and targeting cJun expression to reduce GSH levels. Alternate strategies have targeted p53. The frequent occurrence of p53 mutations in human cancer has led to the development of numerous approaches to restore wild-type (wt) p53. The goals of these interventions are to either revert the malignant phenotype or enhance drug sensitivity. The approach most extensively investigated has utilized one of several viral vectors. An alternate approach, the use of small molecules to restore wt function to mutant p53, remains an option. Finally, the conceptually simplest mechanism of resistance is one that reduces intracellular drug accumulation. Such reduction can be effected by a variety of drug efflux pumps, of which the most widely studied is P-glycoprotein (Pgp). The first strategy utilized to inhibit Pgp function relied on the identification of non-chemotherapeutic agents as competitors. Other approaches have included the use of hammerhead ribozymes against the MDR-1 gene and MDR-1-targeted ASOs. Although modulation of drug resistance has not yet been proven to be an effective clinical tool, we have learned an enormous amount about drug resistance. Should we succeed, these pioneering basic and clinical studies will have paved the road for future developments.
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PMID:Strategies for reversing drug resistance. 1457 55

We have investigated the mechanisms of induction of apoptosis by the antineoplastic ether lipid ET-18-OCH3 (ALP) in sensitive S49wt mouse lymphoma cells and ALP-resistant S49ar variants, both with wild-type p53, and in related L1210 cells with mutated p53. Ether lipid-resistant S49ar cells were cross-resistant to extracellular stress factors (cold shock, heat shock, H2O2, dimethylsulfoxide) and to radiation-induced apoptosis but not to physiological apoptotic signals (dexamethasone, growth factor deprivation, thapsigargin, C2-ceramide) and expressed similar levels of the apoptosis-regulating proteins Bcl-2, Bcl-X, Bax, Bad and Bak as did the parent S49wt cells. The uptake of [3H]-ALP was strongly reduced in the stress-resistant cells but this was not associated with significant differences in membrane cholesterol:phospholipid content nor in membrane microviscosity. In S49ar cells the activity of the antioxidant enzyme glutathione peroxidase (GSH-Px) was increased 4-fold and depletion of glutathione with the drug L-buthionine-S-R-sulfoximine (L-BSO) lowered the resistance of S49ar cells to ALP, stress factors and ionising radiation. The results indicate that ether lipids induce apoptosis by imposing a special form of physico-chemical stress, mediated by reactive oxygen species but independent of p53 status. The capacity of glutathione-dependent anti-oxidant defence appeared an important and shared determinant of the sensitivity to ether lipids, several types of extracellular stress and ionising radiation.
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PMID:Signalling steps in apoptosis by ether lipids. 1463 26

Certain hexavalent chromium (Cr(VI))-containing compounds are recognized occupational human lung carcinogens and may pose an environmental health risk. The carcinogenicity of Cr(VI) is targeted to particulate forms of moderate to low solubility. Soluble Cr(VI) oxyanions in the immediate cellular microenvironment traverse the cell membrane by non-specific anionic transporters. Cr(VI) is reductively metabolized within cells by agents including ascorbic acid (Asc), glutathione (GSH) and cysteine (Cys). During Cr(VI) reduction, a diverse range of genetic lesions are generated including Cr-DNA binary (mono) adducts, Cr-DNA ternary adducts, DNA protein crosslinks (DPCs), bi-functional (DNA interstrand crosslinks (ICLs)) adducts, single-strand breaks (SSBs) and oxidized bases. Some forms of Cr damage, such as ICLs, present physical barriers to DNA replication/transcription and, thus, likely promote a terminal cell fate such as apoptosis or terminal growth arrest. Other lesions, such as ternary DNA adducts, are potentially pre-mutagenic. Cr(VI) exposure elicits a classical DNA damage response within cells including activation of the p53 signaling pathway and cell cycle arrest or apoptosis. Moreover, Cr(VI) also induces the ATM-dependent DNA damage response pathway which is paradoxically required for both apoptosis and survival after Cr(VI) insult. In yeast, moderately cytotoxic concentrations of Cr(VI) result in an initial G1 arrest and delayed S phase progression, whereas less toxic levels of Cr(VI) induce G2 arrest, which requires homologous recombination for exit and survival. The past several years has witnessed many important advances in our understanding of the genetic/cellular damage produced by exposure to Cr(VI). Further information is needed regarding the potential involvement of oxygen radicals in Cr genotoxicity, the specific DNA repair pathways activated by Cr and the complex signaling mechanisms involved in the cellular response to Cr(VI). These pertinent issues must be considered in relation to the potential role that each plays in the induction of human respiratory tract cancer by particulate Cr(VI) compounds.
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PMID:Complexities of chromium carcinogenesis: role of cellular response, repair and recovery mechanisms. 1464 11

We have investigated the dose (in the range of microM) and time-dependent effects of four different retinoids (retinol, retinal, retinoic acid and retinol palmitate) on human dermal fibroblasts cultivated in vitro. Retinol and retinal, at a concentration of 20 microM, caused cell damage as evaluated by lactate dehydrogenase activity released into the culture medium. The oxidised glutathione (GSSG)/reduced glutathione (GSH) ratio and malondialdehyde production indicated that 20 microM of retinol provoked oxidative stress in the cultivated human fibroblasts. In the first 8 h after retinol treatment the levels of p53 and Bax proteins as well as caspase 3 activity increased, suggesting apoptotic cell death during the first hours of treatment. If the retinol treatment exceeded 18-24 h we observed necrotic cell death. Vitamin E and coenzyme Q(10) had a protective effect against oxidative stress generated by retinol. Both antioxidant molecules reduced retinol uptake, and in the case of vitamin E the expression of CRABP-II mRNA was induced, providing a plausible explanation for its protective effect.
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PMID:Retinol, at concentrations greater than the physiological limit, induces oxidative stress and apoptosis in human dermal fibroblasts. 1500 15

Accumulating evidence demonstrates that oxidative stress is one of the underlying mechanisms to induce apoptosis in different biological systems. The aim of this study was to examine the simultaneous presence and correlation between oxidative stress events, apoptosis, apoptosis-associated proteins and monocyte/macrophage infiltration during the course of acute puromycin aminonucleoside nephrosis (PAN). To induce nephrosis, Sprague-Dawley rats were injected intraperitoneally with puromycin aminonucleoside and killed at weeks 1 and 2 of nephrosis. Controls represent animals injected with 0.9% saline solution. Kidney sections were homogenized to measure nitric oxide (NO), malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase activities by appropriate enzymatic and biochemical methods. Renal frozen sections were studied for superoxide anion (O(2) (-)) by a histochemical method, for apoptosis by TUNEL (terminal-deoxynucleotidyl-transferase-mediated dUTP- digoxigenin nick end labelling) and for apoptosis-associated protein expression and monocyte/macrophage infiltration by monoclonal antibodies. Increased renal apoptosis, p53, Bax, Bcl-2 accompanied by increased O(2) (-) and NO generation, lipid peroxidation (MDA) and monocyte/macrophage infiltration were found in nephrotic animals. Renal oxidative stress (O(2) (-), NO and MDA) was correlated with apoptosis, p53 expression, monocyte/macrophage cells and proteinuria. Anti-oxidant molecules (SOD and GSH) remained unchanged apart from a decreased activity of catalase which correlated with glomerular apoptosis. In conclusion, the close correlation between the presence of apoptosis and oxidative events confirms the role of oxidative stress in the apoptosis observed during PAN.
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PMID:Increased oxidative stress and apoptosis in acute puromycin aminonucleoside nephrosis. 1511 91

To clarify the molecular basis of the cytoprotective properties of immunophilin ligands (IPLs), the anti-apoptotic effects of IPLs were determined in human glioma U251 cells. GPI1046 and V10367, non-immunosuppressive IPLs (NI-IPLs), as well as FK506, an immunosuppressive IPL (I-IPL), had cytoprotective effects against hydrogen peroxide (H20O)-induced apoptotic cell death in U251 cells. H2O2 increased both the ratio of bax/bcl-2 and the p53 mRNA expression. However, pre-treatment with FK506 and V10367 significantly prevented any increase in this ratio or p53 mRNA expression. GPI1046 also reduced the ratio of bax/bcl-2 to the normal level. In addition, H2O2 significantly increased activities of all three caspases, caspase-3, caspase-8, and caspase-9, in comparison with non-H2O2 controls. However, FK506 prevented the increase of these caspase activities. On the other hand, it is well-known that glutathione (GSH) and neurotrophic factor (NTF) is related to the induction of apoptosis in neuronal cells. In U251 cells, FK506, GPI1046 and V10367 had GSH-activating and NTF-activating effects. Thus, the immunosuppressive effect is not essential for the cytoprotective properties of IPLs, and IPLs have multiple beneficial properties such as the anti-apoptotic effect, GSH-activating effect, and NTF-activating effect, although the anti-apoptotic effect of NI-IPLs is independent of the regulation of apoptotic activators such as caspase-3.
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PMID:Molecular basis of anti-apoptotic effect of immunophilin ligands on hydrogen peroxide-induced apoptosis in human glioma cells. 1526 Jan 30


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