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)

This study investigated the hypothesis that p53 accumulation in neuroblastoma, in the absence of mutation, is associated with functional inactivation, which interferes with downstream mediators of p53 function. To test this hypothesis, p53 expression, location, and functional integrity was examined in neuroblastoma by irradiating 6 neuroblastoma cell lines and studying the effects on p53 transcriptional function, cell cycle arrest, and induction of apoptosis, together with the transcriptional function of p53 after irradiation in three ex vivo primary, untreated neuroblastoma tumors. p53 sequencing showed five neuroblastoma cell lines, two of which were MYCN-amplified, and that all of the tumors were wild-type for p53. p53 was found to be predominantly nuclear before and after irradiation and to up-regulate the p53 responsive genes WAF1 and MDM2 in wild-type p53 cell lines and a poorly-differentiated neuroblastoma, but not a differentiating neuroblastoma or the ganglioneuroblastoma part of a nodular ganglioneuroblastoma in short term culture. This suggests intact p53 transcriptional activity in proliferating neuroblastoma. Irradiation of wild-type p53 neuroblastoma cell lines led to G(1) cell cycle arrest in cell lines without MYCN amplification, but not in those with MYCN amplification, despite induction of WAF1. This suggests MYCN amplification may alter downstream mediators of p53 function in neuroblastoma.
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PMID:p53 cellular localization and function in neuroblastoma: evidence for defective G(1) arrest despite WAF1 induction in MYCN-amplified cells. 1139 84

The p73 gene is a p53 homologue which induces apoptosis and inhibits cell proliferation. Although p73 maps at 1p36.3 and is frequently deleted in neuroblastoma (NB), it does not act as a classic oncosuppressor gene. In developing sympathetic neurons of mice, p73 is predominantly expressed as a truncated anti-apoptotic isoform (DeltaNp73), which antagonizes both p53 and the full-length p73 protein (TAp73). This suggests that p73 may be part of a complex tumor-control mechanism. To determine the role of DeltaNp73 in NB we analyzed the pattern of expression of this gene in vivo and evaluated the prognostic significance of its expression. Our results indicate that DeltaNp73 expression is associated with reduced apoptosis in a NB tumor tissue. Expression of this variant in NB patients significantly correlates with age at diagnosis and VMA urinary excretion. Moreover it is strongly associated with reduced survival (HR=7.93; P<0.001) and progression-free survival (HR=5.3; P<0.001) and its role in predicting a poorer outcome is independent from age, primary tumor site, stage and MYCN amplification (OS: HR=5.24, P=0.012; PFS: HR=4.36, P=0.005). In conclusion our data seem to indicate that DeltaNp73 is a crucial gene in neuroblastoma pathogenesis.
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PMID:Expression of DeltaNp73 is a molecular marker for adverse outcome in neuroblastoma patients. 1185 3

We report a case of pleuropulmonary blastoma with complex cytogenetic abnormalities, including trisomy 2, trisomy 8, dup(7), der(10) t(8; 10)(q13; q22), add(17), and double minutes (dmin). Fluorescence in situ hybridization FISH analysis demonstrated TP53 deletion and amplification of MYCN; the latter has not been reported in PPB.
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PMID:Molecular cytogenetic analysis of a pleuropulmonary blastoma. 1266 36

Aberrant hypermethylation occurs in tumour cell CpG islands and is an important pathway for the repression of gene transcription in cancers. We investigated aberrant hypermethylation of 11 genes by methylation-specific polymerase chain reaction (PCR), after treatment of the DNA with bisulphite, and correlated the findings with MYCN amplification and allelic status at 1p in a series of 44 neuroblastic tumours. This tumour series includes five ganglioneuromas (G), one ganglioneuroblastoma (GN) and 38 neuroblastomas (six stage 1 tumours; five stage 2 tumours; six stage 3 cases; 19 stage 4 tumours, and two stage 4S cases). Aberrant methylation of at least one of the 11 genes studied was detected in 95% (42 of 44) of the cases. The frequencies of aberrant methylation were: 64% for thrombospondin-1 (THBS1); 30% for tissue inhibitor of metalloproteinase 3 (TIMP-3); 27% for O6-methylguanine-DNA methyltransferase (MGMT); 25% for p73; 18% for RB1; 14% for death-associated protein kinase (DAPK), p14ARF, p16INK4a and caspase 8, and 0% for TP53 and glutathione S-transferase P1 (GSTP1). No aberrant methylation was observed in four control normal tissue samples (brain and adrenal medulla). MYCN amplification was found in 11 cases (all stage 4 neuroblastomas), whereas allelic loss at 1p was identified in 16 samples (13 stage 4 and two stage 3 neuroblastomas, and one ganglioneuroma). All but one case with caspase 8 methylation also displayed MYCN amplification. Our results suggest that promoter hypermethylation is a frequent epigenetic event in the tumorigenesis of neuroblastic tumours, but no specific pattern of hypermethylated genes could be demonstrated.
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PMID:Aberrant methylation of multiple genes in neuroblastic tumours. relationship with MYCN amplification and allelic status at 1p. 1282 52

Early studies of p53 in neuroblastoma reported infrequent mutations in tumours and cell lines. Cytoplasmic sequestration was later proposed as an alternative mechanism of inactivation, but many studies have since reported an intact p53 pathway in neuroblastoma cell lines, as detected by nuclear p53 accumulation after DNA damage, intact DNA binding, transcriptional activation of target genes and the induction of apoptosis. In some MYCN amplified cell lines however, an irradiation induced G(1) arrest does not occur, despite the presence of normal p53. Neuroblastoma usually responds to chemotherapy but frequently relapses, and there is evidence from tumours, and cell lines that p53 inactivation via mutation or MDM2 amplification occurs at relapse and is sometimes associated with multidrug resistance. If p53 inactivation occurs frequently in relapsed tumours it may be appropriate to include p53 independent therapies in the initial management of high-risk neuroblastoma.
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PMID:The p53 pathway and its inactivation in neuroblastoma. 1288 Sep 66

Neuroblastomas are the most frequently occurring solid tumors in children under 5 years. Spontaneous regression is more common in neuroblastomas than in any other tumor type, especially in young patients under 12 months. Unfortunately, the full clinical spectrum of neuroblastomas also includes very aggressive tumors, unresponsive to multi-modality treatment and accounting for most of the pediatric cancer mortalities under 5 years of age. It is generally emphasized that more than one biological entity of neuroblastoma exists. Structural genetic defects such as amplification of MYCN, gain of chromosome 17q and LOH of 1p and several other chromosomal regions have proven to be valuable as prognostic factors and will be discussed in relation to their clinical relevance. Recent research is starting to uncover important molecular pathways involved in the pathogenesis of neuroblastomas. The aim of this review is to discuss several important aspects of the biology of the neuroblast, such as the role of overexpressed oncogenes like MYCN and cyclin D1, the mechanisms leading to decreased apoptosis, like overexpression of BCL-2, survivin, NM23, epigenetic silencing of caspase 8 and the role of tumor suppressor genes, like p53, p73 and RASSF1A. In addition, the role of specific proteins overexpressed in neuroblastomas, such as the neurotrophin receptors TrkA, B and C in relation to spontaneous regression and anti-angiogenesis will be discussed. Finally, we will try to relate these pathways to the embryonal origin of neuroblastomas and discuss possible new avenues in the therapeutic approach of future neuroblastoma patients.
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PMID:Pediatric neuroblastomas: genetic and epigenetic 'danse macabre'. 1469 5

Xeroderma pigmentosum (XP) is a rare autosomal recessive syndrome. Laboratory investigations have failed to detect any consistent anomaly in cells from XP heterozygotic subjects, although examples of behavior intermediate between normal and XP cells have been reported. To estimate random aneuploidy we applied fluorescence in situ hybridization (FISH) with alpha-satellite probes for chromosomes 8 and 9 and replication pattern for TP53 (p53), ERBB2 (HER-2/neu), and MYCN (N-MYC) loci and for the imprinted SNRPN locus. A significantly higher rate of aneuploidy rate was observed in XP patients and carriers than in controls. The asynchrony pattern was significantly higher in XP carriers and patients with all three coding loci analyzed and significantly lower in XP patients and carriers with the imprinted locus SNRPN than in the control group. Molecular cytogenetic parameters such as random aneuploidy and replication pattern, which are known to reflect chromosomal instability, may be part of the tumorigenesis process. In XP patients and carriers, this genetic instability may represent a potential for developing malignancies.
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PMID:Molecular cytogenetic parameters in fibroblasts from patients and carriers of xeroderma pigmentosum. 1503 91

The MYCN oncogene is the major negative prognostic marker in neuroblastoma with important roles in both the pathogenesis and clinical behavior of this aggressive malignancy. MYC oncogenes activate both proliferative and apoptotic cellular pathways and, accordingly, inhibition of p53-mediated apoptosis is a prerequisite for MYC-driven tumorigenesis. To identify novel transcriptional targets mediating the MYCN-dependent phenotype, we screened a MYCN-amplified neuroblastoma cell line by using chromatin immunoprecipitation (ChIP) cloning. We identified the essential p53 inhibitor and protooncogene MDM2 as a putative target. MDM2 has multiple p53-independent functions modulating cell cycle and transcriptional events. Standard ChIP with MYCN antibodies established the binding of MYCN to a consensus E-box within the human MDM2 promoter. Oligonucleotide pull-down assays further established the capacity of MYCN to bind to this promoter region, confirming the ChIP results. Luciferase reporter assays confirmed the E-box-specific, MYCN-dependent regulation of the MDM2 promoter in MYCN-inducible neuroblastoma cell lines. Real-time quantitative PCR and Western blot analysis demonstrated a rapid increase in endogenous MDM2 mRNA and MDM2 protein upon induction of MYCN. Targeted inhibition of MYCN in a MYCN-amplified neuroblastoma cell line resulted in decreased MDM2 expression levels with concomitant stabilization of p53 and induction of apoptosis. Our finding that MYCN directly modulates baseline MDM2 levels suggests a mechanism contributing to the pathogenesis of neuroblastoma and other MYC-driven malignancies through inhibition of MYC-stimulated apoptosis.
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PMID:The p53 regulatory gene MDM2 is a direct transcriptional target of MYCN in neuroblastoma. 1564 44

The human ETS family gene TEL2/ETV7 is highly homologous to TEL1/ETV6, a frequent target of chromosome translocations in human leukemia and specific solid tumors. Here we report that TEL2 augments the proliferation and survival of normal mouse B cells and dramatically accelerates lymphoma development in Emu-Myc transgenic mice. Nonetheless, inactivation of the p53 pathway was a hallmark of all TEL2/Emu-Myc lymphomas, indicating that TEL2 expression alone is insufficient to bypass this apoptotic checkpoint. Although TEL2 is infrequently up-regulated in human sporadic Burkitt's lymphoma, analysis of pediatric B-cell acute lymphocytic leukemia (B-ALL) samples showed increased coexpression of TEL2 and MYC and/or MYCN in over one-third of B-ALL patients. Therefore, TEL2 and MYC also appear to cooperate in provoking a cadre of human B-cell malignancies.
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PMID:The novel ETS factor TEL2 cooperates with Myc in B lymphomagenesis. 1574 32

Female rats of the inbred strain BDII are genetically predisposed to endometrial estrogen-dependent adenocarcinomas (EAC). More than 90% of them spontaneously develop this tumor type before the age of 24 months. In order to dissect out the genetic components behind these tumors we have made crosses between BDII females and rats from 2 other strains that are nonsusceptible to EAC. It was found that EAC tumors developed in a subset of intercross and backcross animals from both interstrain crosses. The chromosomal changes in the developing tumors were studied using cytogenetic and molecular cytogenetic methods. From these studies, we conclude that certain chromosome regions were recurrently engaged in chromosomal changes such as increases in copy number (e.g., trisomy, amplification) or decreases (e.g., deletion). Based on the analysis of 56 tumors, 8 regions were found to be particularly often involved: RNO4prx, gain=34 (61%) (amplification 12 cases); RNO5mid, loss=15 (27%); RNO6prx, gain=25 (45%) (amplification 8 cases); RNO10 loss, prx-mid/gain dst=25 (45%) (amplification 1 case); RNO12q, gain=23 (41%); RNO15p loss/RNO15q gain=29 (52%) (amplification 1 case) [RNO, rat chromosome; prx, proximal; mid, middle; dst, distal; p, short arm; q, long arm]. We begun to analyze these regions in detail using various molecular methods and within them there are certain possible target genes, such as MET (RNO4q21), CDKN2A/2B (RNO5q32), MYCN (RNO6q15 approximately q16), and TP53 (RNO10q24 approximately q25), but it is clear that several other genes, still unidentified, must also be involved.
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PMID:Cytogenetic aberrations in spontaneous endometrial adenocarcinomas in the BDII rat model as revealed by chromosome banding and comparative genome hybridization. 1589 83


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