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)

Nitric oxide (NO) challenge to human neuroblastoma cells (SH-SY5Y) ultimately results in apoptosis. Tumor suppressor protein p53 and cell cycle inhibitor p21 accumulate as an early sign of S-nitrosoglutathione-mediated toxicity. Cytochrome c release from mitochondria and caspase 3 activation also occurred. Cells transfected with either wild type (WT) or mutant (G93A) Cu, Zn-superoxide dismutase (Cu,Zn-SOD) produced comparable amounts of nitrite/nitrate but showed different degree of apoptosis. G93A cells were the most affected and WT cells the most protected; however, Cu, Zn-SOD content of these two cell lines was 2-fold the SH-SY5Y cells under both resting and treated conditions. We linked decreased susceptibility of the WT cells to higher and more stable Bcl-2 and decreased reactive oxygen species. Conversely, we linked G93A susceptibility to increased reactive oxygen species production since simultaneous administration of S-nitrosoglutathione and copper chelators protects from apoptosis. Furthermore, G93A cells showed a significant decrease of Bcl-2 expression and, as target of NO-derived radicals, showed lower cytochrome c oxidase activity. These results demonstrate that resistance to NO-mediated apoptosis is strictly related to the level and integrity of Cu,Zn-SOD and that the balance between reactive nitrogen and reactive oxygen species regulates neuroblastoma apoptosis.
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PMID:Cu,Zn-superoxide dismutase-dependent apoptosis induced by nitric oxide in neuronal cells. 1067 49

The Long-Evans Cinnamon (LEC) rat is a mutant strain characterized by abnormal copper metabolism and a high incidence of hepatitis and hepatoma. Using a yeast-based assay which scores mutants in p53 gene transcripts as red colonies, we detected frequent mutations in the liver of LEC rats. The majority (50-60%) of these were frameshift mutations caused by the insertion of an extra adenine (A) in the regions containing six consecutive adenines. The rate of A insertion was calculated to be 6.9-9.0% of the total p53 cDNA. Insertions of an extra adenine were found almost exclusively in the mRNA (cDNA), especially in the (A)(6) tract located at the most 5'-side (exon 4) among the three (A)(6) tracts (exons 4, 7, and 8), but rarely in the corresponding sites of genomic DNA. Wild-type p53 cDNA was transcribed in vitro into mRNA with the use of SP6 RNA polymerase and tested by the yeast functional assay. Subsequent sequencing detected A insertions at an overall rate of 1.6% in exons 7 and 8 but none in exon 4. This indicates that the A insertion in the exon 4 (A)(6) tract was an in vivo phenomenon rather than an artifact in reverse transcription or polymerase chain reaction. The percentage of red colonies increased sharply to about 20% of the liver samples in the acute hepatitis stage, and returned to control level of those in the chronic hepatitis stage, and increased again slightly to those in the neoplastic stage. The percentage of red colonies correlated with the serum GOT level (r=0.96, p<0.001) but not with the contents of copper and 8-hydroxydeoxyguanosine in the liver of LEC rats. Ethanol treatment of hepatic cell lines also increased the rate of transcriptional slippage at the (A)(6) tract. These findings indicate that cellular damage is responsible for the increase in the rate of mutation at the transcriptional level, and suggest that cellular damage degrades transcriptional fidelity, thereby further impairing cellular functions.
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PMID:Transcriptional slippage of p53 gene enhanced by cellular damage in rat liver: monitoring the slippage by a yeast functional assay. 1075 4

Several isothiocyanates have been proposed as promising chemopreventive agents for human cancers. However, it has been reported that allyl isothiocyanate exhibit carcinogenic potential, and benzyl isothiocyanate and phenethyl isothiocyanate have tumor-promoting activities. We investigated whether these isothiocyanates could cause DNA damage, using (32)P-labeled DNA fragments obtained from the human p53 tumor suppressor gene and the c-Ha-ras-1 protooncogene. Allyl isothiocyanate caused Cu(II)-mediated DNA damage and formation of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) more strongly than benzyl and phenethyl isothiocyanates. Catalase and bathocuproine, a Cu(I)-specific chelator, inhibited Cu(II)-mediated DNA damage by these isothiocyanates, suggesting involvement of H(2)O(2) and Cu(I). Isothiocyanates induced DNA damage frequently at thymine and cytosine residues in the presence of Cu(II). A UV-visible spectroscopic study revealed an association between the generation of superoxide and the yield of SH group from isothiocyanates. Furthermore, the yield of 8-oxodG formation was correlated with their superoxide-generating ability. Allyl isothiocyanate significantly induced 8-oxodG formation in HL-60 cells, but not in H(2)O(2)-resistant HP100 cells, suggesting the involvement of H(2)O(2) in cellular DNA damage. We conclude that oxidative DNA damage may play important roles in carcinogenic processes induced by allyl isothiocyanate.
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PMID:Mechanism of oxidative DNA damage induced by carcinogenic allyl isothiocyanate. 1075 76

Hydrazobenzene is carcinogenic to rats and mice and azobenzene is carcinogenic to rats. Hydrazobenzene is a metabolic intermediate of azobenzene. To clarify the mechanism of carcinogenesis by azobenzene and hydrazobenzene, we investigated DNA damage induced by hydrazobenzene, using 32P-5'-end-labeled DNA fragments obtained from the c-Ha-ras-1 protooncogene and the p53 tumor suppressor gene. Hydrazobenzene caused DNA damage in the presence of Cu(II). Piperidine treatment enhanced the DNA damage greatly, suggesting that hydrazobenzene caused base modification and liberation. However, azobenzene did not cause DNA damage even in the presence of Cu(II). Hydrazobenzene plus Cu(II) caused DNA damage frequently at thymine residues. Catalase and a Cu(I)-specific chelator inhibited Cu(II)-mediated DNA damage by hydrazobenzene. Typical *OH scavengers did not inhibit the DNA damage. The main active species is probably a metal oxygen complex, such as Cu(I)-OOH. Formation of 8-oxo-7, 8-dihydro-2'-deoxyguanosine was increased by hydrazobenzene in the presence of Cu(II). Oxygen consumption and UV-Visible spectroscopic measurements have shown that hydrazobenzene is autoxidized to azobenzene with H2O2 formation. It is considered that the metal-mediated DNA damage by hydrazobenzene through H2O2 generation may be relevant for the expression of carcinogenicity of azobenzene and hydrazobenzene.
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PMID:Copper-dependent DNA damage induced by hydrazobenzene, an azobenzene metabolite. 1079 12

Toxic doses of transition metals are capable of disturbing the natural oxidation/reduction balance in cells through various mechanisms stemming from their own complex redox reactions with endogenous oxidants and effects on cellular antioxidant systems. The resulting oxidative stress may damage redox-sensitive signaling molecules, such as NO, S-nitrosothiols, AP-1, NF-kappaB, IkappaB, p53, p21ras, and others, and thus derange the cell signaling and gene expression systems. This, in turn, may produce a variety of toxic effects, including carcinogenesis. Experimental support for the relevance of oxidative damage to the mechanisms of metal toxicity and carcinogenicity is particularly strong for two essential (but toxic when overdosed) metals--iron and copper-- and three well-established human metal carcinogens--nickel, chromium, and cadmium. However, along with more specific effects of toxic metals associated with their selective binding to particular cell constituents and affecting calcium signaling, oxidative damage seems to become important as well in explaining mechanisms of pathogenicity of other metals, such as lead, mercury, and arsenic.
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PMID:Possible roles of nitric oxide and redox cell signaling in metal-induced toxicity and carcinogenesis: a review. 1098 86

Hemochromatosis and Wilson disease (WD), characterized by the excess hepatic deposition of iron and copper, respectively, produce oxidative stress and increase the risk of liver cancer. Because the frequency of p53 mutated alleles in nontumorous human tissue may be a biomarker of oxyradical damage and identify individuals at increased cancer risk, we have determined the frequency of p53 mutated alleles in nontumorous liver tissue from WD and hemochromatosis patients. When compared with the liver samples from normal controls, higher frequencies of G:C to T:A transversions at codon 249 (P < 0.001) and C:G to A:T transversions and C:G to T:A transitions at codon 250 (P < 0.001 and P < 0.005) were found in liver tissue from WD cases, and a higher frequency of G:C to T:A transversions at codon 249 (P < 0.05) also was found in liver tissue from hemochromatosis cases. Sixty percent of the WD and 28% of hemochromatosis cases also showed a higher expression of inducible nitric oxide synthase in the liver, which suggests nitric oxide as a source of increased oxidative stress. A high level of etheno-DNA adducts, formed from oxyradical-induced lipid peroxidation, in liver from WD and hemochromatosis patients has been reported previously. Therefore, we exposed a wild-type p53 TK-6 lymphoblastoid cell line to 4-hydroxynonenal, an unsaturated aldehyde involved in lipid peroxidation, and observed an increase in G to T transversions at p53 codon 249 (AGG to AGT). These results are consistent with the hypothesis that the generation of oxygen/nitrogen species and unsaturated aldehydes from iron and copper overload in hemochromatosis and WD causes mutations in the p53 tumor suppressor gene.
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PMID:Increased p53 mutation load in nontumorous human liver of wilson disease and hemochromatosis: oxyradical overload diseases. 1105 Jan 62

The tumor suppressor p53 is a transcription factor which binds DNA through a structurally complex domain stabilized by a zinc atom. Zinc chelation disrupts the architecture of this domain, inducing the protein to adopt an immunological phenotype identical to that of many mutant forms of p53. In this report, we used 65Zn to show that incorporation of zinc within the protein was required for folding in the 'wild-type' conformation capable of specific DNA-binding. Using a cellular assay, we show that addition of extracellular zinc at concentrations within the physiological range (5 microM) was required for renaturation and reactivation of wild-type p53. Among other divalent metals tested (Cd2+, Cu2+, Co2+, Fe2+ and Ni2+), only Co2+ at 125 microM had a similar effect. Recombinant metallothionein (MT), a metal chelator protein, was found to modulate p53 conformation in vitro. In cultured cells, overexpression of MT by transfection could modulate p53 transcriptional activity. Taken together, these results suggest that zinc binding plays a regulatory role in the control of p53 folding and DNA-binding activity.
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PMID:Metalloregulation of the tumor suppressor protein p53: zinc mediates the renaturation of p53 after exposure to metal chelators in vitro and in intact cells. 1107 39

Pyrrolidine dithiocarbamate (PDTC) is a metal-chelating compound that exerts prooxidant or antioxidant effects and is widely used to study redox regulation of cell function. In the present study, we investigated effects of PDTC on the function of rat thyroid follicular FRTL-5 cells. Treatment of the cells with PDTC resulted in a marked decrease in Pax-8 messenger RNA level and its DNA-binding activity. This decrease was associated with a significant reduction in thyroperoxidase (TPO) messenger RNA level. Expression of TTF-1 and thyroglobulin was not affected by PDTC. Treatment with PDTC also decreased DNA-binding activity of p53, a tumor suppressor protein, and increased cell proliferation rates. These changes were not observed by the treatment with another antioxidant, N-acetyl-L-cysteine, suggesting that the metal-chelating, prooxidant property of PDTC is responsible for its effects. Indeed, the intracellular level of copper was significantly increased by PDTC. Treatment with bathocuproinedisulfonic acid, a noncell-permeable chelator of Cu1+, abrogated the copper increase by PDTC and its effects on Pax-8 and TPO expression as well as on p53 binding. Taken together, these results indicate that the intracellular level of redox-active copper is crucial for Pax-8 and TPO expression and for proliferation of thyroid follicular cells.
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PMID:Regulation of thyroid follicular cell function by intracellular redox-active copper. 1110 45

Heme is considered to play an instrumental role in the pathology of hemolysis, trauma, and reperfusion following ischemia. However, data are sparse and experimental models are required. The transport of heme by hemopexin to tissues is a specific, membrane receptor-mediated process. Hemopexin recycles after endocytosis like transferrin. Heme oxygenase-1 (HO-1), transferrin, the transferrin receptor, and ferritin are regulated by heme-hemopexin. Genes that encode proteins important for cellular defenses against oxidative stress, such as the cysteine-rich metallothioneins (MTs), are also activated by hemopexin, as are proteins that regulate cell cycle control including p21WAF1 and the tumor suppressor p53. The hemopexin system is being investigated to establish how intracellular events are affected by signal(s) from the plasma membrane due to hemopexin receptor occupancy and heme transport. A transient oxidative modification of proteins, shown by carbonyl production, takes place. Redox processes at the cell surface, which generate cuprous ions, are involved in the regulation of the MT-1 and HO-1 genes by heme-hemopexin before heme catabolism and intracellular release of iron. The "redox-sensitive" transcription factors activated by the hemopexin system include c- Jun, RelA/NFkappaB and MTF-1. The specific copper chelator bathocuproine disulfonate prevents carbonyl production, the nuclear translocation of MTF-1, and the induction of MT-1 revealing a novel, pivotal role for copper in the hemopexin system. In addition, surface redox-active copper is the first link shown for the concomitant regulation of HO-1 and MT-1 and is required for the activation of the amino-terminal c-Jun kinase (JNK) by heme-hemopexin.
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PMID:Links between cell-surface events involving redox-active copper and gene regulation in the hemopexin heme transport system. 1122 23

DNA adduct formation is thought to be a major cause of DNA damage by carcinogenic aromatic amines. We investigated the ability of an aromatic amine, 4-aminobiphenyl (4-ABP) and its N-hydroxy metabolite (4-ABP(NHOH)) to cause oxidative DNA damage, using (32)P-labeled human DNA fragments from the p53 tumor suppressor gene and the c-Ha-ras-1 protooncogene. 4-ABP(NHOH) was found to cause Cu(II)-mediated DNA damage, especially at thymine residues. Addition of the endogenous reductant NADH led to dramatic enhancement of this process. Catalase and bathocuproine, a Cu(I)-specific chelator, reduced the amount of DNA damage, suggesting the involvement of H(2)O(2) and Cu(I). 4-ABP(NHOH) dose-dependently induced 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in the presence of Cu(ll) and NADH. 4-ABP(NHOH) conversion to nitrosobiphenyl, as measured by UV-visible spectroscopy, occurred rapidly in the presence of Cu(II), suggesting Cu(II)-mediated autoxidation. Increased amounts of 8-OHdG were found in HL-60 cells compared to the H(2)O(2)-resistant clone HP100 following 4-ABP(NHOH) treatment, further supporting the involvement of H(2)O(2). The present study demonstrates that an N-hydroxy derivative of 4-ABP induces oxidative DNA damage through H(2)O(2) in both a cell-free system and in cultured human cells. We conclude that, in addition to DNA adduct formation, oxidative DNA damage may play an important role in the carcinogenic process of 4-ABP.
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PMID:Mechanism of oxidative DNA damage induced by carcinogenic 4-aminobiphenyl. 1127 76


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