Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Relapse is a major cause of treatment failure in acute myeloid leukaemia (AML), and is usually accompanied by resistance to chemotherapy. To study whether relapse is accompanied by genetic alterations, we compared N-ras, p53 and FLT3 gene mutations in paired samples obtained at initial diagnosis and first relapse. 28 patients with relapsed AML were studied, and their duration of complete remission ranged from 133 to 989 d (mean 318 d). Karyotype changes were observed at relapse in 11 patients. Point mutations of the N-ras gene were positive at both stages (+/+) in three patients, positive at initial diagnosis and negative at relapse (+/-) in three patients, and negative at initial diagnosis and positive at relapse (-/+) in two patients. Internal tandem duplications of the FLT3 gene (FLT3/ITD) were +/+ in five patients, +/- in one patient, and -/+ in six patients. The p53 gene mutations were +/+ in two patients, +/- in one patient, and -/- in 25 patients. FLT3/ITD and mutant p53 at relapse were associated with short survival after relapse. These results indicate that relapse is frequently accompanied by molecular alterations that include the loss and/or acquisition of mutations. Thus relapse can be understood as clonal shift or collateral succession rather than clonal progression.
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PMID:Molecular evolution of acute myeloid leukaemia in relapse: unstable N-ras and FLT3 genes compared with p53 gene. 1019 23

The prevalence and significance of genetic abnormalities in older patients with acute myeloid leukemia (AML) are unknown. Polymerase chain reactions and single-stranded conformational polymorphism analyses were used to examine 140 elderly AML patients enrolled in the Southwest Oncology Group study 9031 for FLT3, RAS, and TP53 mutations, which were found in 34%, 19%, and 9% of patients, respectively. All but one of the FLT3 (46 of 47) mutations were internal tandem duplications (ITDs) within exons 11 and 12. In the remaining case, a novel internal tandem triplication was found in exon 11. FLT3 ITDs were associated with higher white blood cell counts, higher peripheral blast percentages, normal cytogenetics, and less disease resistance. All RAS mutations (28 of 28) were missense point mutations in codons 12, 13, or 61. RAS mutations were associated with lower peripheral blast and bone marrow blast percentages. Only 2 of 47 patients with FLT3 ITDs also had a RAS mutation, indicating a significant negative association between FLT3 and RAS mutations (P =.0013). Most TP53 mutations (11 of 12) were missense point mutations in exons 5 to 8 and were associated with abnormal cytogenetics, especially abnormalities in both chromosomes 5 and 7. FLT3 and RAS mutations were not associated with inferior clinical outcomes, but TP53 mutations were associated with a worse overall survival (median 1 versus 8 months, P =.0007). These results indicate that mutations in FLT3, RAS, or TP53 are common in older patients with AML and are associated with specific AML phenotypes as defined by laboratory values, cytogenetics, and clinical outcomes. (Blood. 2001;97:3589-3595)
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PMID:FLT3, RAS, and TP53 mutations in elderly patients with acute myeloid leukemia. 1136 55

Cytogenetic abnormalities are seen in approximately 50% of cases of myelodysplastic syndrome (MDS) and 80% of cases of secondary MDS (following chemotherapy or radiotherapy). These abnormalities generally consist of partial or complete chromosome deletion or addition (del5q, -7, +8, -Y, del20q), whereas balanced or unbalanced translocations are rarely found in MDS. Fluorescence hybridization techniques (fluorescence in situ hybridization [FISH], multiplex FISH, and spectral karyotyping) are useful in detecting chromosomal anomalies in cases in which few mitoses are obtained or rearrangements are complex. Ras mutations are the molecular abnormalities most frequently found in MDS, followed by p15 gene hypermethylation, FLT3 duplications, and p53 mutations, but none of these abnormalities are specific for MDS. The rare cases of balanced translocations in MDS have allowed the identification of genes whose rearrangements appear to play a role in the pathogenesis of some cases of MDS. These genes include MDS1-EVI1 in t(3;3) or t(3;21) translocations, TEL in t(5;12), HIP1 in t(5;7), MLF1 in t(3;5), and MEL1 in t(1;3). Genes more frequently implicated in the pathogenesis of MDS cases, such as those involving del5q, remain unknown, although some candidate genes are currently being studied. Cytogenetic and known molecular abnormalities generally carry a poor prognosis in MDS and can be incorporated into prognostic scoring systems such as the International Prognostic Scoring System.
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PMID:Chromosome and molecular abnormalities in myelodysplastic syndromes. 1150 56

Mutations in signal transduction molecules, which regulate cell differentiation and proliferation, are involved in the development of leukemia. Aberrations of receptor type tyrosine kinases are known to arise from FLT3 mutations in acute myeloid leukemia (AML) and myelodysplastic syndrome, and c-Kit mutations in mast cell tumors. BCR/ABL found in chronic myelogenous leukemia (CML) is a hallmark of the constitutively active forms of cytoplasmic tyrosine kinases. Downstream of the tyrosine kinase is the RAS GTP-binding protein, and genetic mutations related to this protein have been found in a wide variety of malignant tumors including hematopoietic tumors. In the nucleus, transcription factor-encoding genes are frequently detected as the targets of chromosomal translocations found in specific types of leukemias. For instance, the AML1 gene generates AML1/MTG8 chimera by t (8;21) translocation in AML (M2), AML1/EVI-1 chimera by t (3;21) translocation in blastic crisis of CML, and TEL/AML1 chimera in t (12;21) translocation (pre-B cell type acute lymphoblastic leukemia). Another example of abnormal transcription factors is PML/RAR alpha generated by t (15;17) translocation found in acute promyelocytic leukemia. Mutations or deletions of tumor suppressor genes are frequently found in cell cycle regulators such as p53, RB and p16 genes. Therefore, mutations of any molecules involved in the signal transduction pathways from growth factor receptors to inside the nucleus are thought to contribute to neoplastic transformation of hematopoietic cells.
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PMID:[Molecular mechanisms in leukemogenesis]. 1214 88

Although FLT3 mutations are essentially found in myeloid-lineage leukemia cells, a high level of FLT3 expression was recently observed in MLL gene-rearranged acute lymphoblastic leukemia without FLT3 mutations. Here, we analyzed the biologic and clinical significance of the FLT3 transcript level in comparison with several gene alterations in 181 de novo acute myeloid leukemia (AML) cases. The mean expression level in AML was higher than that in normal mononuclear cells, whereas the range varied widely. A high level of FLT3 is related to internal tandem duplication of the FLT3 gene (FLT3/ITD), the mutations within the activation loop of FLT3 (FLT3/D835Mt), and tandem duplication of the MLL gene (MLL-TD) but not to p53 or N-RAS gene mutations. Furthermore, a high expression level in AML cases with FLT3 mutations was not related to MLL-TD. Overexpressed FLT3 revealed autophosphorylation and had the same sensitivity to the FLT3 inhibitor as FLT3/ITD. Overexpression of FLT3 (more than 200,000 copies/microgRNA) was an unfavorable prognostic factor for overall survival in 91 AML cases without FLT3/ITD. These results indicated that FLT3 overexpression may distinguish a novel disease entity in AML without FLT3 mutations and serve as a therapeutic target for FLT3 inhibitors.
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PMID:Biologic and clinical significance of the FLT3 transcript level in acute myeloid leukemia. 1460 73

Oncogenic mutations in the KRAS2, NRAS, or FLT3 gene are detected in more than 50% of patients with de novo acute myeloid leukemia (AML). RAS mutations are also prevalent in de novo myelodysplastic syndrome (MDS), especially chronic myelomonocytic leukemia and juvenile myelomonocytic leukemia. However, few studies have examined these genetic lesions in therapy-related myeloid malignancies. Monosomy 7/del(7q) and monosomy 5/del(5q) represent the most common cytogenetic abnormalities in therapy-related MDS and AML (t-MDS/t-AML) and are strongly associated with prior exposure to alkylating agents. Mutational analysis of bone marrow specimens from a well-characterized cohort of 26 t-MDS/t-AML patients with abnormalities of chromosomes 5 and/or 7 revealed 3 with RAS mutations. Further analyses of 23 of these cases uncovered one FLT3 internal tandem duplication and five TP53 mutations. The four patients with RAS or FLT3 mutations had monosomy 7, including one with abnormalities of chromosomes 5 and 7. One specimen demonstrated mutations in both KRAS2 and TP53. RAS and FLT3 mutations, which are thought to stimulate the proliferation of leukemia cells, appear to be less common in t-MDS/t-AML than in de novo AML, whereas TP53 mutations are more frequent.
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PMID:RAS, FLT3, and TP53 mutations in therapy-related myeloid malignancies with abnormalities of chromosomes 5 and 7. 1473 23

Mutations of the NRAS and TP53 genes and internal tandem duplication (ITD) of the FLT3 gene are among the most frequently observed molecular abnormalities in the myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). We sought to determine the incidence of these abnormalities in patients with MDS and a 5q deletion. NRAS and FLT3 mutations are uncommon in MDS patients with a 5q deletion and TP53 mutation is associated with the more advanced MDS subtypes.
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PMID:NRAS, FLT3 and TP53 mutations in patients with myelodysplastic syndrome and a del(5q). 1525 41

To clarify the role of the genetic mutations in the clinical course of acute myeloid leukemias (AML), we analyzed for p51, p53, FLT3 and N-ras gene mutations and the expression of the p51 gene in relapsed AML. Paired samples obtained from patients with AML at both stages of diagnosis and first relapse were analyzed. Twenty-four patients with relapsed AML survived for 6 to 81 months (median 24 months) from diagnosis. In one patient, no point mutation of the p51 gene was detected, but loss of the p51 gene expression was observed at both stages. Point mutations of the p53 gene were positive at both stages (+/+) in two patients and negative at diagnosis and positive at relapse (-/+) in two patients. Tandem duplication of the FLT3 gene was detected in five patients at both stages (+/+). N-ras gene mutations at both stages (+/+) were detected in three patients. Mutant p53 at relapse was associated with short survival in patients with relapsed AML (P<0.014). Our findings show that p53 mutations were, at least in part, associated with the mechanism of relapse in AML, while new p51, FLT3 and N-ras gene alterations did not occur at relapse. Loss of the p51 gene expression in de novo AML has not been reported yet.
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PMID:Abnormalities of p51, p53, FLT3 and N-ras genes and their prognostic value in relapsed acute myeloid leukemia. 1532 87

Recently, somatic mutations of the nucleophosmin gene (NPM1), which alter the subcellular localization of the product, have been reported in acute myeloid leukemia (AML). We analyzed the clinical significance of NPM1 mutations in comparison with cytogenetics, FLT3, NRAS, and TP53 mutations, and a partial tandem duplication of the MLL gene (MLL-TD) in 257 patients with AML. We found NPM1 mutations, including 4 novel sequence variants, in 64 of 257 (24.9%) patients. NPM1 mutations were associated with normal karyotype and with internal tandem duplication (ITD) and D835 mutations in FLT3, but not with other mutations. In 190 patients without the M3 French-American-British (FAB) subtype who were treated with the protocol of the Japan Adult Leukemia Study Group, multivariate analyses showed that the NPM1 mutation was a favorable factor for achieving complete remission but was associated with a high relapse rate. Sequential analysis using 39 paired samples obtained at diagnosis and relapse showed that NPM1 mutations were lost at relapse in 2 of the 17 patients who had NPM1 mutations at diagnosis. These results suggest that the NPM1 mutation is not necessarily an early event during leukemogenesis or that leukemia clones with NPM1 mutations are sensitive to chemotherapy.
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PMID:Clinical characteristics and prognostic implications of NPM1 mutations in acute myeloid leukemia. 1599 85

Knowledge of the molecular events that govern human thyroid tumorigenesis has grown considerably in the past ten years. Key genetic alterations and new oncogenic pathways have been identified. Molecular genetic aberrations in thyroid carcinomas bear noteworthy resemblance to those in acute myelogenous leukemias. Thyroid carcinomas and myeloid leukemias both possess transcription factor gene rearrangements-PPARgamma-related translocations in thyroid carcinoma and RARalpha-related and CBF-related translocations (amongst others) in myeloid leukemia. PPARgamma and RARalpha are closely related members ofthe same nuclear receptor subfamily, and the PML-RARalpha and PAX8-PPARgamma fusion proteins both function as dominant negative inhibitors of their wild-type parent proteins. Thyroid carcinomas and myeloid leukemias also both harbor NRAS mutations (15-25% of both cancers) and receptor tyrosine kinase mutations--RET mutations in thyroid carcinomas and FLT3 mutations in myeloid leukemias. The NRAS and tyrosine receptor kinase mutations are not observed in the same thyroid carcinoma or leukemia patients, suggesting that multiple initiating pathways exist in both. Lastly, thyroid carcinomas and myeloid leukemias possess p53 mutations at relatively low frequency (10-15%) in patients who tend to be older and have more aggressive, therapy resistant disease. Such parallels are unlikely to occur by chance alone and argue that common mechanisms underlie these diverse epithelial and hematologic cancers. The comparison of thyroid carcinomas and myeloid leukemias may highlight areas of thyroid cancer investigation worthy of further focus. For example, few collaborating mutations have been defined in thyroid carcinomas even though they play a clear role in myeloid leukemias, as exemplified by RARalpha rearrangements and FLT3 mutations that together dictate the promyleocytic leukemia phenotype. Functional interactions between collaborating mutations are possible at multiple levels, and it is tempting to speculate that some thyroid carcinomas might develop through an unique combination or co-activation of RET and RAS and/or RET and PPARgamma (and/or other) signaling systems. In fact, the ELE1-RET (PTC3) fusion protein contains the ELE1 nuclear receptor co-activator domain and it appears to physically associate with and inhibit wild-type PPARgamma in some papillary carcinomas. The similarities of the fusion proteins in thyroid carcinoma and myeloid leukemia suggest that a more directed search for fusion genes in non-thyroid carcinomas is warranted. In fact, novel fusion genes have been identified recently in aggressive midline, secretory breast, and renal cell carcinomas, although the epithelial nature of the latter is not well-documented. Interestingly, these cancers all tend to present more frequently in adolescence and young adulthood in a manner similar to thyroid and myeloid malignancies that have fusion genes. The analyses of cancers that present earlier in life may enhance fusion gene recognition in other carcinoma types. Definition and biologic characterization of the precursor cells that give rise to thyroid carcinoma will also be important. Myeloid leukemias are thought to arise from stem/progenitor cells that acquire disturbed self-renewal and differentiation capacities but retain characteristics of the myeloid lineages. Although the presence of comparable stem/progenitor cells in the thyroid are not defined, distinct thyroid cancer lineages and patterns of differentiation exist and candidate stem/progenitor cells such as the p63-immunoreactive solid cell nests are apparent. A last important area is development of molecular-based therapies for thyroid carcinoma patients resistant to standard radio-iodine treatment. Treatments for such cancers are limited and pathways defined by thyroid cancer mutations are prime targets for pharmacologic interventions with molecular inhibitors. Tyrosine kinase inhibitors and nuclear receptor ligands have proven dramatically effective in some myeloid leukemia patients. Various molecular inhibitors are being investigated now in thyroid cancer models. Such developments predict that the thyroid cancer model will continue to provide biologic insights into human carcinoma biology and that improved pathologic diagnosis and treatment for thyroid cancer patients sit on the not too distant horizon.
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PMID:Molecular events in follicular thyroid tumors. 1620 39


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