UNIPROT:P04637 - FACTA Search

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Query: UNIPROT:P04637 (p53)
77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Metallocene complexes containing vanadium induce apoptosis in human cancer cells by an as yet unknown mechanism and may therefore be useful as a new class of cytotoxic anticancer drugs. Ultrastructural studies showing the formation of metallocene-DNA complexes prompted the hypothesis that their mechanism of action may resemble the DNA damage induced by cisplatin. Molecular genotoxicity testing provides insights into the mechanisms of action of new chemotherapeutic agents. Therefore, we determined the effects of three cytotoxic vanadocene complexes, vanadocene dichloride, vanadocene dithiocyanate, and vanadocene dioxycyanate, on genomic stability using the yeast DEL recombination assay and transcriptional activation of genotoxic stress-specific promoters in human HepG2 cells using the CAT-Tox(L) assay. Cisplatin caused an 11-fold increase of recombination frequency in yeast and induced transcriptional activation of the DNA damage-associated promoters such as the minimum promoter containing p53 response elements and the GADD45 promoter in addition to activating the promoters for c-fos, heat shock protein 70, metallothionine IIa, and the minimum promoter containing nuclear factor kappa(kappa)B response elements. In contrast to cisplatin, vanadocene complexes did not increase the DEL recombination frequency in yeast nor did they activate any of the DNA damage-associated promoters in HepG2 cells. Vanadocene complexes triggered activation of the c-fos promoter without affecting the minimum promoter containing p53 response elements or the GADD45 promoter. These results indicate that the apoptotic signal of vanadocene complexes is not triggered by primary DNA damage and it does not require p53 induction, thereby disproving the hypothesis that it mechanistically resembles the cytotoxic action of cisplatin.
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PMID:Molecular genotoxicity profiles of apoptosis-inducing vanadocene complexes. 993 Dec 82

The frequency of oxidative base damage, such as 8-hydroxyguanine (8-OH-Gua), was determined at the nucleotide level of resolution using the ligation-mediated PCR technique. Administration of a renal carcinogen, ferric nitrilotriacetate (Fe-NTA), is known to induce oxidative stress and subsequent formation of 8-OH-Gua in the rat kidney. Whole genomic DNA was isolated from the rat kidney after or without Fe-NTA treatment and then cleaved with hot piperidine. In order to assess the frequency of 8-OH-Gua formation, we chose three genes, the tumor suppressor gene p53, the heat shock protein 70 (HSP70-1) gene and the Na,K-ATPase alpha1 subunit gene. No alteration in the cleavage profile was observed in the p53 and HSP70 genes after Fe-NTA treatment. In the case of the p53 gene, a low incidence of point mutations has been observed in this carcinogenesis system. On the other hand, time-dependent alterations, corresponding to the time course of overall 8-OH-Gua formation and repair, were detected in the promoter region of the Na,K-ATPase alpha1 subunit gene. GpG and GpGpG in specific regions seem to be hotspots for the formation of 8-OH-Gua. These results were confirmed by formamidopyrimidine-DNA glycosylase-dependent DNA cleavage patterns. Thus, oxidative base damage, such as 8-OH-Gua, was not distributed uniformly along the whole genome, but seemed to be restricted to particular genes and regions.
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PMID:Analysis of 8-hydroxyguanine in rat kidney genomic DNA after administration of a renal carcinogen, ferric nitrilotriacetate. 1033 1

Induction of apoptosis is a function of external stimuli and cellular gene expression. Many cells respond to DNA damage by the induction of apoptosis, which depends on a functional p53 protein and is signaled by elevation of p53 levels. In this study, we found that a prior exposure to mild stress (42 degrees C) can protect HepG2 (p53+/+) cells from a subsequent UVC-induced apoptosis determined by DNA fragmentation and ratio of sub-G1 peak, but no heat-enhanced protection was found in Hep3B (p53-/-) cells. Although a similar inductive pattern of HSP70 protein and mRNA was detected in the two cell lines under thermal stress, the effect of thermal stress on UVC-induced apoptosis in HepG2 and Hep3B cells was obviously different. Overexpression of HSP70 by transient transfection of HSP70 expression vector in HepG2 cells significantly inhibited UVC-induced cell death; however, this inhibitory effect did not occur in transfected-Hep3B cells. Treatment of HepG2 cells with p53-specific antisense oligonucleotide could effectively block the antiapoptotic effect of thermal stress on UVC-induced apoptosis and increase of intracellular wild-type p53 protein by transfecting wtp53 expression plasmid into Hep3B cells yielded more resistance to UVC irradiation after prior thermal stress exposure. The results reveal an involvement of p53 in the antiapoptotic effect of thermal stress on UVC irradiation. Finally, a p53 protein increase was detected in UVC-treated HepG2 cells and could be coimmunoprecipitated with HSP70 after a thermal stress treatment. Prolonged p53 binding activity and enhanced expression of p53-controlled genes such as G1 arrest and DNA damage 45 and wild-type p53 activation factor 1/Cdk-interacting protein 1 by thermal stress are also observed in UVC-irradiated HepG2 cells. Based on these results, we propose that the antiapoptotic effect of thermal stress is mediated by increasing HSP70 and modulating intracellular p53 function.
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PMID:Involvement of heat-shock protein 70 and P53 proteins in attenuation of UVC-induced apoptosis by thermal stress in hepatocellular carcinoma cells. 1042 Aug 46

Studies investigating the relationship between common genetic variants and cancer risk are being reported with rapidly increasing frequency. We have identified 46 published case-control studies that have examined the effect of common alleles of 18 different genes on breast cancer risk. Of these, 12 report statistically significant associations, none of which were reported by more than one study. However, many of the studies were small: 10 of the 46 had 80% power or greater to detect a rare allele homozygote relative risk <2.5. We therefore combined the results of individual studies to obtain more precise estimates of risk. Statistically significant differences in genotype frequencies were found in three case-control comparisons of unselected cases. These were for CYP19 (TTTA)n polymorphism [(TTTA)10 carrier odds ratio (OR) = 2.33; P = 0.002], the GSTP1 Ile105Val polymorphism (Val carrier OR = 1.60; P = 0.02), and the TP53 Arg72Pro polymorphism (Pro carrier OR = 1.27; P = 0.03). In addition, the GSTM1 gene deletion was found to be significantly associated with postmenopausal breast cancer (null homozygote OR = 1.33; P = 0.04). There was also some evidence that homozygotes for the PR PROGINS allele are protected against breast cancer, although this result was of borderline statistical significance. For polymorphisms in BRCA1, COMT, CYP17, CYP1A1, NAT1, and NAT2, the best estimate of risk either from the individual studies or the meta-analyses was sufficiently precise to exclude a relative risk of 1.5 or greater. For the polymorphisms in EDH17B2, ER, CYP2D6, CYP2E1, GSTT1, HSP70, and TNFalpha, the risk estimates, although nonsignificant, were insufficiently precise to exclude a moderate risk (>1.5). Precise estimation of the risks associated with these and other as yet untested genes, as well as investigation of more complex risks arising from gene-gene and gene-environment interactions, will require much larger studies.
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PMID:A systematic review of genetic polymorphisms and breast cancer risk. 1054 11

Data concerning the expression of p53 in cervical carcinoma, one of the leading cause of death in developing countries, are still confusing. This study was designed to identify p53 in Egyptian cervical carcinoma in an attempt to evaluate its prognostic significance. Eleven chronic cervicitis and 38 invasive carcinoma (31 squamous cell carcinoma (sqcc) and 7 adenocarcinoma, ranging from stage IB to IVB), were stained with the monoclonal antibody anti p53, DO7, using the microwave for antigen retrieval. No immunoreactivity was detected in chronic cervicitis, while nuclear p53 reactivity was detected in all carcinoma and in squamous intra-epithelial lesions (SIL) overlying 8 sqcc. P53 immunohistochemical (IHC) expression was more pronounced in early clinical stages (p=0.007) and in adenocarcinoma compared to sqcc (p=0.015). A positive correlation was present between p53 and heat shock protein 70 (hsp70) expressions (p=0.005). No correlation could be found between p53 expression and tumor infiltrating lymphocytes, the presence or absence of either schistosomiasis or HPV infections. It can be concluded, that in the Egyptian population, p53 immunoreactivity appears to be an early event in cervical neoplasm, and seems to play an important role together with other cell regulatory proteins in the process of carcinogenesis, which could be different between sqcc and adenocarcinoma.
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PMID:p53 immunohistochemical expression of Egyptian cervical carcinoma. 1060 22

Damage to bone tissue due to heat shock is one of the main causes of the failure of osseointegration at the bone-implant interface. To investigate the effect of heat shock on regeneration of bone tissue, osteoblasts were exposed to heat shock for 10 minutes at 42, 45, or 48 degrees C or kept at 37 degrees C as a control. After 10 minutes of heat shock, disruption of actin filaments was seen in the cells and the degree of disruption increased with the temperature. The cytoskeleton reassembled after a 12-hour incubation at 37 degrees C in the cells treated at 42 or 45 degrees C, but this reversible recovery did not occur in the cells treated at 48 degrees C. Flow cytometric analysis showed that heat shock at 48 degrees C increased the number of necrotic cells to 15-20% within minutes (p < 0.05 compared with 37 degrees C). Apoptosis, evidenced by annexin V staining, DNA laddering, and caspase 3 activation, started after 6-8 hours of incubation, reached a peak at 12 hours, and gradually declined (p<0.05). Pretreatment with the antioxidant N-acetyl-L-cysteine reduced the necrosis induced at 48 degrees C of heat shock by one-half (p<0.05) but had no significant effect on caspase 3 activation induced by heat shock, suggesting that reactive oxygen species were critical in heat shock-induced necrosis but not in apoptosis. Heat shock at 48 degrees C induced a sustained translocation of p53 into the nucleus and a sustained activation of c-jun N-terminal kinase, whereas that at 42 and 45 degrees C induced only transient p53 translocation and c-jun N-terminal kinase activation. These results suggest that the sustained activation of p53 and c-jun N-terminal kinase pathways may contribute to heat shock-induced apoptosis. On the other hand, heat shock protein 70 increased dramatically in the cells treated at 45 or 48 degrees C, suggesting that the protecting mechanism in the cells was also activated. Such protection was able to prevent apoptosis in cells treated at 45 degrees C but not in those treated at 48 degrees C.
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PMID:Heat shock-induced necrosis and apoptosis in osteoblasts. 1063 56

The tumor suppressor protein p53 is a transcription factor that can positively regulate the expression of critical target genes involved in negative control of cell growth or induction of apoptosis; p53 is also able to suppress the transcription of other genes by virtue of its ability to bind components of the basal transcription machinery. Over 50% of human tumors are characterized by p53 mutations that result in a loss of wild-type p53 (wtp53) function in the transcriptional control of these target genes. We have exploited this loss of p53 function in the regulation of gene transcription to develop a novel gene therapy strategy that maximizes expression of the potential therapeutic gene in tumors while simultaneously down-regulating the same gene in normal cells. In one construct (unit I), the potential therapeutic gene (in this case represented by a luciferase reporter) is placed under the control of a promoter such as the heat shock protein 70 gene promoter, which is repressed by wtp53 but overexpressed in many tumor cells with defective p53 function. Residual expression of the reporter in normal cells is repressed by cotransfection of another construct (unit II) consisting of a repressor of unit I under the control of a promoter that is activated by wtp53 expression. Unit II contains a promoter with a consensus wtp53 binding site driving a transcriptional repressor or an antisense construct for the gene in unit I. Our results suggest that this dual control approach may represent a strategy with wide applications in the field of cancer gene therapy.
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PMID:Targeting gene expression to tumor cells with loss of wild-type p53 function. 1067 50

The cell synthesis of heat shock proteins is increased by a variety of environmental and pathophysiological stressful conditions. The 70-kD heat shock protein family (HSP70 family) which constitutively expresses hsc70 and heat-inducible hsp70 is thought to be involved in protein-protein interactions, including oncogene products. We investigated the HSP70 family expression and biological behavior of gastric cancer, and its relation to p53 overexpression. Expressions of HSP70 and p53 in 164 primary gastric tumors were determined immunohistochemically. Exploratory data were analyzed on a set of 164 primary gastric cancers, and we constructed in prognostic significance of the HSP70 expression level and the relation to p53 overexpression. Expression of HSP70 (hsc70 and hsp70) were detected in nuclei and/or cytoplasm of cancer cells. Western blotting analysis showed that hsc70 and hsp70 were both expressed in five gastric cancer cell lines. Immunohistochemically stained positive cells of HSP70 varied from 0 (very weak) to 100%, in each case. The median level of positive cell rate was 19.0%. A HSP70 expression of over 19.0% was related to the differentiated tissue type of gastric cancer, but not to other clinicopathological factors. There was no difference in survival rates in subjects with higher and lower groups of HSP70 expression. HSP70 expression was also not related to p53 overexpression in the nuclei and p53 overexpression-related poorer prognosis. Our findings show that the expression of HSP70 is not associated with tumor advance-related characteristics or with the prognosis of gastric cancer. Measurements of HSP70 expression do not appear to be a useful prognostic marker.
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PMID:Overexpression of the heat shock protein HSP70 family and p53 protein and prognosis for patients with gastric cancer. 1070 41

Cyclopentenone prostaglandins inhibit virus replication in several DNA and RNA virus models. In this report we investigated the effect of prostaglandin A1 (PGA1) on HIV-1 transcription in human CD4+ Jurkat T lymphocyte cells. A dramatic reduction of HIV-1 RNA levels was detected up to seven days post infection in both unstimulated and phorbol 12-mystrate 13-acetate (PMA)-stimulated cells treated with PGA1- PGA1 treatment of cells was also effective in inhibiting the transcription of a chloramphenicol acetyltransferase (CAT) reporter gene, under the control of HIV-1 LTR, in Jurkat-Tat cells. We also show that PGA1 induced the synthesis of 70-kDa heat-shock protein (HSP70) in this cell system and the induction correlated with the drug-antiviral activity. PGA1 was also found to induce the loss of the tumor suppressor p53 protein, in the "proliferative" conformation, in a time correlation with the induction of the HSP70 As the "proliferative" p53 has been involved in the positive trans-activation of the HIV-1 LTR its depletion could contribute to the inhibitory mechanisms of PGA1 on virus transcription.
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PMID:Inhibition of HIV-1 transcription by cyclopentenone prostaglandin A1 in Jurkat T lymphocytes. 1103 55

The prognosis of osteosarcoma has been improved by chemotherapy. Heat shock proteins (HSPs) assist in folding proteins at posttranslation and degeneration under stress. We investigated the effect of HSPs on survival in osteosarcoma. Conventional osteosarcomas of the extremities from 70 patients aged 30 years or younger were used. Preoperational chemotherapy was performed in all cases. Tissues at surgery and biopsy were immunohistochemically stained with anti-HSP27, HSP47, HSP60, HSP70, HSP90alpha, HSP90beta, and p53 antibodies. We classified the cases in which more than 10% of tumor cells were positive into the overexpressing group. Overall survival was compared between the groups either overexpressing HSPs or not using Wilcoxon's test and Cox's proportional hazard model. The overexpression rate at biopsy was 22% (HSP27), 88% (HSP47), 66% (HSP60), 48% (HSP70(, 47% (HSP90alpha), 31% (HSP90beta), and 17% (p53), respectively. The rate at surgery was 33% (HSP27), 94% (HSP47), 60% (HSP60), 49% (HSP70), 28% (HSP90alpha), 40% (HSP90beta), and 17% (p53), respectively. HSP27 and p53 overexpression at biopsy had a negative prognostic value. HSP27 showed the strongest negative prognostic value in osteosarcoma. It is therefore important to investigate further its function in cellular regulation and drug resistance.
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PMID:Expression of heat shock proteins in osteosarcoma and its relationship to prognosis. 1108 53

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