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)

Oxidative stress associated with photodynamic therapy (PDT) is a transcriptional inducer of genes encoding stress proteins, including those belonging to the heat shock protein (hsp) family. The efficiency of PDT to function as a molecular switch by initiating expression of heterologous genes ligated to the human hsp promoter was examined in the present study. Selective and temporal reporter gene expression was documented after PDT in mouse radiation-induced fibrosarcoma cells stably transfected with recombinant vectors containing an hsp promoter ligated to either the lac-z or CAT reporter genes and in transfected radiation-induced fibrosarcoma tumors grown in C3H mice. Hyperthermia treatments were included as a positive control for all experiments. Expression vectors containing either human p53 or tumor necrosis factor (TNF)-alpha cDNA under the control of an hsp promoter were also constructed and evaluated. A p53 null and TNF-alpha-resistant human ovarian carcinoma (SKOV-3) cell line was stably transfected with either the p53 or TNF-alpha constructs. Inducible expression and function of p53 as well as inducible expression, secretion, and biological activity of TNF-alpha were documented after PDT or hyperthermia in transfected SKOV cells. These results demonstrate that PDT-mediated oxidative stress can function as a molecular switch for the selective and temporal expression of heterologous genes in tumor cells containing expression vectors under the control of an hsp promoter.
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PMID:Photodynamic therapy-mediated oxidative stress as a molecular switch for the temporal expression of genes ligated to the human heat shock promoter. 1074 34

We tested the effect of IL-1 on the expression of p21(WAF1) in human embryonic fibroblasts WI38. Exposure to IL-1 caused induction of p21(WAF1) protein in high-passage WI38 cells but not in early-passage cells. However, IL-1 did not stimulate the transcription of a CAT-reporter gene having two copies of the p53-responsive element on its promoter or the p53-binding capacity of nuclear extracts, although it increased transcriptional rate of p21(WAF1) in these high-passage cells. These results suggest that the induction of p21(WAF1) by IL-1 occurs at the transcriptional level, but p53 function is not required in these cells. Further studies found that IL-1 did not cause cell-cycle arrest, and the overexpression of p21(WAF1) resulted in only a slight delay of cell growth, while the level of p21(WAF1) coprecipitated with cyclin-dependent kinase-2 (Cdk2) was increased by IL-1. Moreover, a kinase assay of Cdk2 immunoprecipitates showed that IL-1 did not reduce the kinase activity, and IL-1 did not affect the status of phosphorylation of the retinoblastoma gene product (Rb). These findings imply that despite the induction of p21(WAF1), this cannot fully account for the growth arrest in high-passage WI38 cells. Thus, IL-1 mediates p21(WAF1) induction through a p53-independent pathway(s) in high-passage WI38 cells, but the cell cycle is regulated independently of p21(WAF1).
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PMID:IL-1 induces expression of p21(WAF1) independently of p53 in high-passage human embryonic fibroblasts WI38. 1078 99

We have analyzed the expression of the CDKN1A (p21(CIP1)), CDKN1B (p27(Kip1)), TP53, RB1 and MDM2 proteins and tumor cell proliferation by immunohistochemical staining in 59 cases of metastatic melanoma. The genomic status of the CDKN2A (INK4-ARF, p16/p14(ARF)), CDKN2B (p15) and CDKN2C (p18) genes was determined by PCR-SSCP (single-strand conformation polymorphism) in 46 of these cases. These results were correlated with various clinico-pathological parameters, including the outcome of combined chemoimmunotherapy. We found positive correlations between the expression of CDKN1A and MDM2 (r = 0.5063, P = 0.001), between the expression of CDKN1B and RB1 (r = 0.5026, P = 0.001), and between RB1 expression and tumor cell proliferation (0.5564, P<0.001). Two mutations in the CDKN2A (p16) gene were detected, including a novel base change AAC-->ATC (Asn to Ile) at codon 71, that also changes the codon 85 of the alternative reading frame gene p14(ARF) from CAA to CAT (Gln to His). Homozygous deletion at exon 2 of the CDKN2A (INK4-ARF) gene was detected in six cases. In seven cases, the 540C-->G polymorphism in the 3'UTR of the CDKN2A (p16) gene was found in linkage disequilibrium with the 74C-->A polymorphism in intron 1 of the CDKN2B gene (P < 0.0001). These cases had significantly lower expression of the TP53 protein (P = 0.0032). Both 540C-->G and 580C-->T polymorphisms in the 3'UTR of the CDKN2A (p16) gene were associated with significantly shorter progression time from primary to metastatic disease (P = 0.0071). We conclude, that although none of the analyzed cell cycle regulators could be singled out as a major prognostic factor, G(1)/S checkpoint abnormalities remain one of the most significant factors in the development of malignant melanoma.
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PMID:Analysis of G(1)/S checkpoint regulators in metastatic melanoma. 1086 49

Only a few human malignant peripheral nerve sheath tumour (MPNST)-cell lines have been reported, and their characteristics have not been fully established. In this study, we established a new human cell line, HS-Sch-2, from an MPNST of the ordinary type which arose in a 54-year-old woman without von Recklinghausen's disease. This cell line was characterized by chromosome analysis, immunohistochemistry, ultrastructural examination, and direct sequencing of the p53 gene. The HS-Sch-2 cells have grown for more than 48 months in vitro, and exhibited hypotriploid karyotypes with complex chromosome abnormalities lacking a specific pattern. Histological features of the heterotranplanted nude mouse tumours were essentially the same as those of the original MPNST, with positive reactions for S-100 protein and neuron-specific enolase but not for epithelial membrane antigen, fibronectin or CD34. Ultrastructural examination in vivo revealed intricate interdigitation of long cytoplasmic processes and basal lamina-like structures. In addition, direct sequencing of the p53 gene detected a point mutation from CGT to CAT at codon 273 in exon 8. This HS-Sch-2 cell line, which exhibits distinctive morphological characteristics of MPNST and a p53 point mutation, will be useful for biological and pathological investigations of MPNST.
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PMID:A new human malignant peripheral nerve sheath tumour-cell line, HS-sch-2, harbouring p53 point mutation. 1089 46

The p53 protein binds DNA as a tetramer inside the nucleus, but a form of the p53 protein during nuclear transport has not been fully elucidated. To verify whether the human p53 protein passes through the nuclear pore as a monomer or oligomer, two different p53 mutants N1 and C1NLS- with or without a nuclear localization signal (NLS), respectively, were expressed in Xenopus laevis embryos. By the whole-mount immunostaining method, their intracellular distributions were observed to exist in an NLS-dependent manner. In a immunoprecipitation assay system, NLS-defective mutants formed oligomer in the cytoplasm. When coexpressed with NLS-containing N1, C1NLS- still stayed in the cytoplasm and did not inhibit N1 transport into the nucleus. Furthermore, when oligomerization-defective p53 mutant was expressed in Xenopus embryos, efficiency of its nuclear transport was demonstrated to be unchanged compared to that of the wild type. Assuming that NLS-defective p53 mutants have no dominant-negative effect on wild-type p53 in the nucleus of p53 heterozygous cells, we investigated the dominant-negative effect by CAT activity assay using human cell line Saos-2 and NLS-defective mutants. It was found that the NLS-defective p53 mutant did not have a dominant-negative effect on the function of wild-type p53 protein in the nucleus. Data indicate that each monomeric p53 protein independently passes through the nuclear pore; however, the possibility of homooligomeric p53 protein transport into the nucleus is not completely excluded.
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PMID:Form of human p53 protein during nuclear transport in Xenopus laevis embryos. 1091 97

We performed dual (two-color) fluorescence in situ hybridization (FISH) using direct fluorescent labeling probes for p53 and chromosome 17 in six gastrointestinal (3 stomach and 3 colon) cancers. In three of these (1 stomach and 2 colon) the interphase cell nuclei showed an imbalance of signals for the p53 and chromosome 17; that is, the p53 signal count was lower than the chromosome 17 signal count, indicating deletion of the p53 gene. Moreover, metaphase FISH analysis demonstrated that those nuclei actually had a chromosome 17 with deletion of the p53 gene. Interestingly, these three cases had an abnormal chromosome 17 copy number, that is, chromosome 17 aneusomy. Furthermore, to investigate the possibility of p53 mutation in tumors with an imbalance of signals for chromosome 17 and p53 per nucleus, we performed a GeneChip p53 assay which has recently been developed. GeneChip p53 assay demonstrated that a primary tumor sample from one colon cancer case had a heterozygous point mutation of CGT (Arg) to CAT (His) at codon 273 in exon 8. In addition, a sample of metastatic tumor in the liver from the same case revealed two heterozygous point mutations. One of them was the same mutation as that is the primary tumor; the other was GTG (Val) to GGG (Gly) at codon 217 in exon 6. In conclusion, we found that the combination of dual-color FISH and GeneChip p53 assay offered reliable results and important information concerning not only deletion of the p53 gene and chromosome 17 aneusomy but also p53 mutations. Using these techniques, we demonstrated that an imbalance of signals for chromosome 17 and p53 per nucleus, chromosome 17 aneusomy, and accumulation of p53 mutations had occurred during carcinogenesis and development of gastrointestinal cancers.
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PMID:Detection of aberrations of 17p and p53 gene in gastrointestinal cancers by dual (two-color) fluorescence in situ hybridization and GeneChip p53 assay. 1095 39

The p53 tumor suppressor protein functions as a transcription factor. It has, however, been previously reported that some p53 mutants are able to suppress cell growth independent of their transcriptional activity [Kaneuchi et al., (1999)]. In order to investigate the correlations between the trans-activation and growth-suppressive functions of p53, we have analyzed five p53 mutants by CAT reporter assay, colony formation assay, and growth-rate analysis. Five p53 mutants [Oh et al., (2000)]--199stop (Gly-->stop), 240ile (Ser-->Ile), 250ala (Pro-->Ala), 285lys (Glu-->Lys), and 291asn (Lys-->Asn)--were cotransfected with a reporter construct containing a p53-responsive element and then tested for their trans-activational activity in p53-null Saos-2 cells. As a result of a change in the protein structure, trans-activational activity was negated in 199stop, 240ile, 285lys, and 291asn, while 250ala retained its activity. Colony formation assay revealed that mutants 240ile and 250ala retained their growth suppression, while 199stop, 285lys, and 291asn did not. To study the features of these proteins, a group of isogenic cell lines that express mutant forms of p53 was generated from HeLa cells, and their growth rate was then examined: one group, containing 199stop, 285lys, and 291asn, showed a rapid growth rate, similar to that of the original HeLa cells; the other group, containing 240ile and 250ala, however, exhibited a slow growth rate. In conclusion, mutant p53 240ile, which completely lost its trans-activational activity, nevertheless continued to exhibit its growth-suppressive activity. Further work is required to understand how 240ile is involved in growth suppression.
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PMID:The p53 mutation which abrogates trans-activation while maintaining its growth-suppression activity. 1098 34

In this study, we sought to investigate the mechanism of the proapoptotic function of Egr-1 in relation to p53 status in normal isogenic cell backgrounds by using primary MEF cells established from homozygous (Egr-1(-/-)) and heterozygous (Egr-1(+/-)) Egr-1 knock-out mice. Ionizing radiation caused significantly enhanced apoptosis in Egr-1(+/-) cells (22.8%; p < 0.0001) when compared with Egr-1(-/-) cells (3.5%). Radiation elevated p53 protein in Egr-1(+/-) cells in 3-6 h. However, in Egr-1(-/-) cells, the p53 protein was down-regulated 1 h after radiation and was completely degraded at the later time points. Radiation elevated the p53-CAT activity in Egr-1(+/-) cells but not in Egr-1(-/-) cells. Interestingly, transient overexpression of EGR-1 in p53(-/-) MEF cells caused marginal induction of radiation-induced apoptosis when compared with p53(+/+) MEF cells. Together, these results indicate that Egr-1 may transregulate p53, and both EGR-1 and p53 functions are essential to mediate radiation-induced apoptosis. Rb, an Egr-1 target gene, forms a trimeric complex with p53 and MDM2 to prevent MDM2-mediated p53 degradation. Low levels of Rb including hypophosphorylated forms were observed in Egr-1(-/-) MEF cells before and after radiation when compared with the levels observed in Egr-1(+/-) cells. Elevated amounts of the p53-MDM2 complex and low amounts of Rb-MDM-2 complex were observed in Egr-1(-/-) cells after radiation. Because of a reduction in Rb binding to MDM2 and an increase in MDM2 binding with p53, p53 is directly degraded by MDM2, and this leads to inactivation of the p53-mediated apoptotic pathway in Egr-1(-/-) MEF cells. Thus, the proapoptotic function of Egr-1 may involve the mediation of Rb protein that is essential to overcome the antiapoptotic function of MDM2 on p53.
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PMID:Ionizing radiation down-regulates p53 protein in primary Egr-1-/- mouse embryonic fibroblast cells causing enhanced resistance to apoptosis. 1103 41

Fibroblast growth factor-2 (FGF-2) is a powerful mitogen and angiogenic factor whose expression is strongly regulated at the translational level. The constitutive upregulation of FGF-2 isoforms in transformed cells prompted us to investigate the post-transcriptional effects of a tumour suppressor, p53, on FGF-2 expression. We show here in human primary skin fibroblasts that the cell density-dependent variation of FGF-2 mRNA translatability was inversely correlated with endogenous p53 expression. Transient cell transfection revealed an inhibitory effect of wild-type p53 on the expression of chimeric FGF--CAT proteins. RNAse mapping experiments ruled out any effect of p53 on FGF--CAT mRNA accumulation, suggesting a translational inhibition. This inhibition was mediated by the FGF-2 mRNA leader, but not by vascular endothelial growth factor or platelet derived growth factor mRNA leaders. Neither p53-like protein p73, nor p21/waf had any inhibitory activity. Furthermore a set of hot spot mutants of p53 bearing mutations in the DNA binding domain had no post-transcriptional inhibitory effect. In contrast a p53 mutant of the transactivating domain was still able to block FGF--CAT expression, indicating that the post-transcriptional activity of p53 described here was independent of the trans-activation of target genes. Such data reveal a novel mechanism by which p53 efficiently blocks the expression of a major proliferating, anti-apoptotic and angiogenic gene.
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PMID:Tumour suppressor p53 inhibits human fibroblast growth factor 2 expression by a post-transcriptional mechanism. 1131 15

Neuroblastomas can acquire a sustained high-level drug resistance during chemotherapy and especially myeloablative chemoradiotherapy. p53 mutations are rare in primary neuroblastomas, but a loss of p53 function could play a role in multidrug resistance. We determined p53 function by measuring induction of p21 and/or MDM2 proteins in response to melphalan (L-PAM) in seven L-PAM-sensitive and 11 L-PAM-resistant neuroblastoma cell lines. p53 was functional in seven/seven drug-sensitive but in only 4/11 drug-resistant cell lines (P = 0.01). In four of the seven cell lines lacking p53 function, mutations of p53 were detected by the microarray GeneChip p53 Assay and automated sequencing, whereas six cell lines with functional p53 had no evidence of p53 mutations. All of the cell lines with wild-type (wt) p53 showed a strong transactivation of the p53-HBS/CAT reporter gene, whereas the four cell lines with mutant p53 failed to transactivate p53 HBS/CAT. Overexpression of MDM2 protein (relative to p53 functional lines) was seen in two p53-nonfunctional cell lines with wt p53; one showed genomic amplification of MDM2. Nonfunctional and mutated p53 was detected in a resistant cell line, whereas a sensitive cell line derived from the same patient before treatment had functional and wt p53. Loss of p53 function was selectively achieved by transduction of human papillomavirus 16 E6 (which degrades p53) into two drug-sensitive neuroblastoma cell lines with intact p53, causing high-level drug resistance to L-PAM, carboplatin, and etoposide. These data obtained with neuroblastoma cell lines suggest that the high-level drug resistance observed in some recurrent neuroblastomas is attributable to p53 mutations and/or a loss of p53 function acquired during chemotherapy. If confirmed in patient tumor samples, these data support development of p53-independent therapies for consolidation and/or salvage of recurrent neuroblastomas.
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PMID:Loss of p53 function confers high-level multidrug resistance in neuroblastoma cell lines. 1150 71


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