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)

We analysed p53 mutations in 24 patients with myelodysplastic syndrome (MDS) and overt acute myeloid leukaemia after a period of MDS, using polymerase chain reaction-single strand conformation polymorphism analysis. In exons 5 to 8, mobility shifts were detected in five of the 24 patients. Sequence analysis was subsequently performed, and four missense mutations (16.7%) and one silent nucleotide substitution were identified. Patients harbouring mutations were characterized as having advanced disease. Loss of the wild type allele was observed in three of the four patients with missense mutations. No mobility shifts of the N-ras or FMS gene were detected in these four patients. We next analysed the correlation of the p53 mutations with the progression of MDS in three patients. The mutation was accompanied by the progression in two of the three patients. These findings suggest that mutations of the p53 gene are associated with progression in some cases of MDS, while being compatible with stable disease or clonal evolution in others.
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PMID:Mutations of the p53 gene in myelodysplastic syndrome and overt leukemia. 855 5

The frequencies of p53 and N-ras gene mutations were examined in multiple myeloma. DNA samples of 45 cases of multiple myeloma were obtained from stored bone marrow smears. All samples were analyzed for the N-ras gene at codon 12 by the allele specific restriction analysis method and at codon 61 by direct sequencing. DNA was screened for mutations by single-strand conformation polymorphism analysis for the p53 gene in exons 5 to 8. DNA fragments showing an altered electrophoretic pattern were further studied by direct sequencing to confirm the mutations. Ras mutations were found in two cases at codon 61 (4.4%). A point mutation of the p53 gene was detected in one of 45 cases (2.2%). These 3 cases with mutations were in an advanced stage. In conclusion, N-ras and p53 gene mutations may occur at a late stage of multiple myeloma, but the frequencies of the mutations are very low.
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PMID:N-ras and p53 gene mutations are very rare events in multiple myeloma. 859 Jul 78

Renal cell carcinomas induced in male Wistar rats by iron chelate of nitrilotriacetate (Fe-NTA) were examined for mutations in ras oncogenes and p53 tumor suppressor gene. Fourteen primary tumors and two metastatic tumors from 11 animals were evaluated. Exons 1 and 2 of the H-, K-, and N-ras genes were amplified by polymerase chain reaction (PCR), and the presence of mutations was examined by direct sequencing. Exon 5 through exon 7 of p53 gene, including the 3' half of the conserved region II and the entire conserved region III through V, were surveyed for point mutations by PCR-single stranded conformation polymorphism (SSCP) analysis. Direct sequencing of the ras genes showed no mutations in codon 12, 13, or 61 among the tumors evaluated. SSCP analysis of p53 gene exon 6 indicated conformational changes in two primary tumors. One tumor had a CCG-to-CTG transition at codon 199, and the other had an ATC-to-att transition at codon 229 and two nonsense C-to-T transitions. These results suggest that neither ras genes nor p53 gene play a major role in the development of renal cell carcinomas induced by Fe-NTA.
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PMID:Absence of ras mutations and low incidence of p53 mutations in renal cell carcinomas induced by ferric nitrilotriacetate. 863 2

An iron chelate, ferric nitrilotriacetate (Fe-NTA, induces renal proximal tubular damage, a consequence of iron-catalyzed free radical reactions, that finally leads to a high incidence of renal cell carcinoma (RCC) in rodents. Previous studies have identified, within 24 h after administration of Fe-NTA, lipid peroxidation products, aldehyde-modified proteins and a variety of modified DNA bases such as 8-hydroxyguanine that may be mutagenic in vivo. In the present study, pathological features of the RCCs were studied, and, in an effort to correlate them with carcinogen-specific molecular events in Fe-NTA-induced carcinogenesis, the H-, K- and N-ras oncogenes and the p53 tumor suppressor gene were investigated for the presence of mutations. Fe-NTA-induced RCCs showed similarity to human RCCs in that they are often invasive, metastatic and fatal. None (0 of 12) of the tumors had mutation in codons 12, 13 and 61 of the H-, K- and N-ras genes by direct sequencing. Only one (1 of 12) tumor with high grade histology revealed a CGC-to-CTC (Arg to Leu) transversion in codon 246 of the p53 gene by the use of single strand conformation polymorphism (SSCP) analysis and direct sequencing. High expression of mutant p53 protein was confirmed by Western blotting and immunohistochemistry. Study of three peritoneal mesotheliomas induced by Fe-NTA revealed no mutation in ras and p53 genes. These results suggest that the ras and p53 genes are not the major targets of mutation in Fe-NTA-induced carcinogenesis of kidney and mesothelium. Instead, p53 mutation may work for potentiation of malignant character in Fe-NTA-induced renal carcinogenesis.
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PMID:Low incidence of point mutations in H-, K- and N-ras oncogenes and p53 tumor suppressor gene in renal cell carcinoma and peritoneal mesothelioma of Wistar rats induced by ferric nitrilotriacetate. 863 3

Primary mediastinal B cell lymphoma (PMBL) is a diffuse large B cell lymphoma (DLCL) postulated to arise from noncirculating thymic B lymphocytes. Because of its distinctive clinical and morphological features and putative unique cellular origin, PMBL is generally considered a distinct clinicopathological entity. Little is known, however, about the molecular characteristics of PMBL. Therefore, we analyzed 16 PMBLs for molecular alterations involving the bcl-1, bcl-2, bcl-6, c-myc, H-ras, K-ras, N-ras, and p53 genes and for Epstein-Barr virus infection, which are commonly involved in lymphoid neoplasia. Employing a combination of Southern blotting and/or polymerase chain reaction and single-strand conformation polymorphism assays, we detected genetic alterations in 7 of the 16 (44%) PMBLs. Whereas the bcl-6 gene is rearranged in up to 45% of DLCLs, rearrangement of the bcl-6 gene was detected in only 1 of these 16 (6%) PMBLS. Point mutations of the 5' noncoding region of the c-myc gene were demonstrated in 3 other cases (19%), although c-myc gene rearrangements were not seen by Southern blotting. Missense point mutations of the p53 gene were identified in 3 additional PMBLs (19%). Alterations of the bcl-1, bcl-2, or ras genes and evidence of Epstein-Barr virus infection were not observed. In conclusion, a variety of molecular lesions occur in PMBLs and may be involved in their pathogenesis. This molecular genetic pattern bears little resemblance to that known for other B cell malignancies, including DLCL. In particular, the infrequent occurrence of bcl-6 gene rearrangement in PMBLs distinguishes them from other DLCLs of B cell origin, suggesting that PMBLs do not represent a distinct subtype of DLCL.
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PMID:Molecular characterization of primary mediastinal B cell lymphoma. 866 86

Protooncogenes are cell cycle-related genes that are involved in cell growth of proliferation. Alterations in the level of expression of these genes, or expression of aberrant gene productions, have been observed in tumors and precancerous conditions. To determine if expression of these genes is altered in patients with inflammatory bowel disease (IBD) --who are at risk for development of colon cancer--we assayed transcripts of 15 protooncogenes in colonic epithelial cells of IBD patients and controls. Nine of these genes (H-ras, c-myc, c-fos, c-jun, junB, N-myc, c-abl, c-yes, and p53) were expressed in epithelial cells, whereas two (RB1 and N-ras) were not. expression of four other genes (c-src, K-ras, c-raf, and c-myb) was observed, but the intensity of these bands was too low for densitometric analysis. The steady-state levels of transcripts of H-ras and five nuclear protooncogenes (c-myc, c-fos, c-jun, junB, and N-myc) were lower in epithelial cells from involved or uninvolved IBD samples than in normal epithelial cells from either sporadic colon cancer or diverticulitis patients. The level of c-fos mRNA was two- to threefold higher in involved than in uninvolved areas of the colons of two ulcerative colitis (UC) patients, but not in one Crohn's disease (CD) patient. Message abundance of c-abl transcripts was two- to threefold lower in UC epithelial cells than in either the CD or control samples. The steady-state level of c-yes-encoded mRNA was considerably higher in IBD patients resected for colon cancer than in patients resected for active chronic IBD or in controls. The level of p53 message was constant in these samples. Increased levels of c-fos mRNA in involved UC relative to uninvolved UC may be related to the disease process. Decreased expression of c-abl transcript in UC may be a diagnostic marker for UC and may be related to the rate of cell turnover in these diseases. Enhanced expression of c-yes in IBD patients with tumors compared to active chronic IBD and controls suggests that expression of this gene may be a marker for development of colon cancer in IBD.
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PMID:Expression of protooncogene-encoded mRNA by colonic epithelial cells in inflammatory bowel disease. 867 85

Rare inherited cancer syndromes have proven invaluable for the identification of genes involved in the more frequent corresponding noninherited cases. We report on a family with an adult onset, incompletely penetrant, autosomal dominant syndrome of myelodysplasia and acute myelogenous leukemia, affecting at least eight, and probably ten, individuals from three generations. The patients have developed leukemias differing in morphologic subtype, tumor cytogenetics, and abruptness of presentation. Some have presented with acute onset and others with protracted myelodysplasia. This family does not have an unusual incidence of other malignancies; however, one person at 50% risk of inheriting this gene developed atypical mycobacterium infection in the absence of leukemia, but also without appreciable risk factors for acquired deficiencies in cellular immunity. Features common to affected family members, including the individual with mycobacterium infection, are the early presence in the bone marrow of red cell and platelet maturation defects. A search for mutations in diseased marrows fails to detect abnormalities of p53 or N-ras. Two of the affected family members, third degree relatives, have co-inherited a constitutional chromosomal banding variation of 9p21-22, potentially suggesting linkage to this locus. The variable penetrance and expressivity of this syndrome support a multistep model of leukemia evolution, in which the gene defined by this family's syndrome is the signal step.
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PMID:A family inheriting different subtypes of acute myelogenous leukemia. 870 48

Malignant insulinoma is an rare form of cancer with poor prognosis and a reported 5-year survival of 35%. Relatively little is known about the etiology of this disease or of the oncogenes and tumor suppressor genes that participate in its genesis and progression. To address this issue, several protooncogenes, including K-ras, N-ras, erbB-2, erbB-3,c-myc, c-fos, c-jun were examined. Also analyzed was the expression of the growth factors TGF-alpha, EGF, and insulin as well as the EGF receptor (EGF-R), p53 and the putative anti-metastasis gene nm23-H1. These were examined in malignant insulinomas, benign insulinomas, pancreatic B cell hyperplasias and in normal endocrine pancreas. Normal endocrine pancreas showed moderate immunoreaction for c-myc and a strong reaction for insulin. All other parameters were negative. Benign pancreatic B cell hyperplasias were slightly or moderately positive for N-ras and TGF-alpha, and were weakly positive for EGF-R. They were strongly positive for c-myc and insulin. In malignant insulinomas there was strong immunoreaction for c-myc, TGF-alpha, N-ras, K-ras and p53. Insulin reaction was moderate or strong. Molecular genetic studies have been performed for the presence of activating point mutations in codon 12 of the c-K-ras oncogene. Mutations were detected using primer-mediated, mutant-enriched, polymerase chain reaction-restriction fragment length polymorphism analysis and were further characterized by allele-specific oligonucleotide hybridization. Four out of six patients with malignant insulinoma and two out of eight patients with benign insulinoma harbored K-ras point mutations at codon 12. All patients with mutated K-ras oncogene also had elevated levels of p53 protein as well as c-myc and TGF-alpha. In one extremely malignant case we found concomitant mutation at codon 12 of K-ras and codon 61 of the N-ras gene. Our data are consistent with the idea that malignant progression is accompanied by the progressive accumulation of multiple genetic lesions and suggest that activation of myc, TGF-alpha and ras genes may be early events in the development of insulinoma.
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PMID:Molecular genetics of malignant insulinoma. 871 89

Starting 4 years after the Chernobyl accident, a dramatic increase in incidence of thyroid carcinoma was noticed in children from contaminated areas. The incidence of benign thyroid lesions in the exposed population was also increased. To study the possible role of ras and p53 genes in radiation-induced thyroid tumorigenesis, 33 papillary carcinomas, one follicular carcinoma and 22 benign lesions removed from children aged 5-19 were screened for point mutations of H-, K-, and N-ras, as well as of p53 (exons 5-8) using single strand conformation polymorphism (SSCP) analysis. Ras point mutations were detected in 1/1 case of follicular carcinoma (N-ras codon 61 CAAgln-->AAAlys), and in 3/7 follicular adenomas (N-ras codon 61 CAAgln-->CGAarg x 2, CAAgln-->AAAlys). None of the cases of papillary thyroid carcinoma was positive for ras oncogene abnormalities. The lack of K-ras mutations was confirmed by allele-specific oligonucleotide hybridization (ASOH), and by sequencing in five cases. Somatic point mutations in p53 were found by SSCP in 2/33 papillary thyroid carcinomas, with one missense mutation (exon 5, codon 160 ATGmet-->GTGval) and another silent mutation (codon 182, TGCcys-->TGTcys). Immunohisto-chemically, focally positive p53 staining was found in four papillary carcinomas being primarily confined to solid and poorly-differentiated areas in tumors. These data demonstrate that as opposed to the few reports on tumors arising after therapeutic external irradiation, ras mutations are not primary events in the development of post-Chernobyl thyroid papillary carcinomas. p53 mutations do not appear to be important in the development of these tumors, but may in some cases have a role in progression to a more aggressive phenotype that has not yet fully manifested in these pediatric neoplasms.
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PMID:Prevalence of mutations of ras and p53 in benign and malignant thyroid tumors from children exposed to radiation after the Chernobyl nuclear accident. 876 Dec 89

Oral cancer, although uncommon in the Western world, accounts for up to 40% of all malignancies in parts of India and South East Asia. Recognised aetiological agents of oral cancer include tobacco and alcohol. This paper reviews the spectrum of molecular changes found in oral squamous cell carcinomas from Western (U.K., U.S.A., Australia) and Eastern (India, S.E. Asia) countries. p53 mutations are common in tumours from the West (47%) but are infrequent in the East (7%). Tumours from India and South East Asia are characterised by the involvement of ras oncogenes, including mutation, loss of heterozygosity (H-ras) and amplification (K- and N-ras), events which are uncommon in the West. The possibility that these genetic differences reflect aetiology and/or ethnic origin is discussed.
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PMID:Molecular changes in oral cancer may reflect aetiology and ethnic origin. 876 70


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