Navegando por Autor "Klumb, Claudete Esteves"
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Artigo Chromosome 17 abnormalities and mutation of the TP53 gene: Correlation between cytogenetics, flow cytometry and molecular analysis in three cases of chronic myeloid leukemia(Sociedade Brasileira de Genética, 2005) Otero, Luize; Cavalcanti Júnior, Geraldo Barroso; Klumb, Claudete Esteves; Scheiner, Marcos Antonio Mauricio; Magluta, Eliane Pereira Simões; Fernandez, Teresa de Souza; Silva, Maria Luiza Macedo; Pires, Virgínia; Andrade, Gabriela Vasconcelos; Maia, Raquel Ciuvalschi; Tabak, DanielAlterations involving the short arm of chromosome 17 (17p) during the progression of chronic myeloid leukemia (CML) have been described. This chromosomal region contains the tumor suppressor gene TP53 that may be an important factor in the evolution of this disease. In this study, we used flow cytometry and western blotting to assess p53 protein expression and single stranded conformational polymorphism to examine TP53 gene alterations in three patients with CML who showed alterations in 17p. Only the case with del(17)(p11) had p53 expression positive by flow cytometry and an abnormal migration pattern by SSCP analysis. The importance of the correlation between the results obtained with these techniques, as well as the clinical course of the patients, are discussed.Artigo Coexpression of p53 protein and MDR functional phenotype in leukemias: the predominant association in chronic myeloid leukemia(Wiley, 2004) Cavalcanti Junior, Geraldo Barroso; Vasconcelos, Flavia da Cunha; Faria, Giselle Pinto de; Scheiner, Marcos Antônio Maurício; Dobbin, Jane de Almeida; Klumb, Claudete Esteves; Maia, Raquel C.; https://orcid.org/0000-0001-9227-4145Background: One of the best characterized resistance mechanisms of leukemias is multidrug resistance (MDR) mediated by P-glycoprotein (Pgp) and multidrug-resistant related protein (MRP). In addition to Pgp and MRP, p53 mutation or inactivation might play a relevant role in therapeutic failure. Some studies have demonstrated that Pgp and MRP may be activated in association with overexpression of mutant or inactivated p53 protein. The aim of this study was to investigate the association between p53 expression and MDR functional phenotype analyzed by flow cytometry (FCM). Methods: Rhodamine-123 assay analyzed by FCM was used to detect the MDR phenotype that was positive in 18 out of 41 (43.9%) cases of chronic myeloid leukemia (CML), 16 out of 28 (57.1%) chronic lymphoid leukemia (CLL) cases, 11 out of 28 (39.3%) acute myeloid leukemia (AML) cases, and four out of 22 (18.2%) acute lymphoid leukemia (ALL) cases. Results: Variable levels of p53 expression were observed in leukemic cells: 12 out of 41 (29.2%) in CML, nine out of 28 (32.1%) in CLL, 15 out of 28 (53.6%) in AML, and eight out of 22 (36.4%) in ALL samples. Conclusions: In our study, no significant association between p53 expression and MDR functional phenotype was observed in ALL, CLL, and AML. On the other hand, a significant association (P 0.0003) of the coexpression was observed in CML. The p53 overexpression was more frequently seen in the accelerated phase and the blastic phase of this disease. Our results suggest that an MDR functional phenotype could be associated with p53 mutation in the advanced stage of leukemias.