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Neoplasias astrocitárias e correlação com as proteínas p53 mutada e Ki-67 Translated title: Astrocytic neoplasms and correlation with mutate p53 and Ki-67 proteins

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      Abstract

      As neoplasias astrocitárias correspondem a 60% dos tumores do sistema nervoso central, sendo o estudo da biologia molecular um importante passo para a compreensão da gênese e comportamento biológico destas doenças. As proteínas Ki-67, que é um marcador de proliferação celular, e p53, que é o produto do gene supressor de tumor de mesmo nome, são importantes marcadores tumorais. O objetivo deste estudo foi identificar e quantificar as proteínas Ki-67 e produto do gene supressor de tumor TP53 em diferentes graus de malignidade das neoplasias astrocitárias, bem como analisar suas relações com idade e sexo. Foram estudadas por imuno-histoquímica as proteínas Ki-67 e p53 em 47 pacientes com neoplasias astrocitárias ressecadas cirurgicamente, classificadas previamente e revisadas quanto ao grau de malignidade, de acordo com o proposto pela Organização Mundial da Saúde. Os núcleos celulares imunomarcados foram quantificados no programa Imagelab-softium pela razão paramétrica absoluta entre os núcleos de células positivas e o número total de células tumorais, sendo contadas 1000 células. O delineamento utilizado foi transversal não controlado. Para análise estatística as variáveis foram divididas em grupos, que para a Ki-67 foram ausente, <5% e >5% e para a p53 foram ausente (0), <25% (1+), entre 25 e 50% (2+), entre 50 e 75% (3+) e maior que 75% (4+). Ki-67 esteve presente em 37 casos (78,72%) expressando correlação com maior grau de malignidade (p<0,001) . A p53 esteve presente em 14 casos (35,13%) tendo maior correlação com astrocitoma grau IV (p=0,59). Não houve correlação estatisticamente significativa entre p53 e Ki-67, bem com entre estas variáveis, idade e sexo. Concluiu-se que a hipótese de maior presença de Ki-67 e p53 em neoplasias astrocitárias de maior grau de malignidade, com exceção da correlação entre grau III e p53, é corroborada pelos resultados deste estudo.

      Translated abstract

      The astrocytic neoplasms respond by 60% of the central nervous system tumors, being the study of the molecular biology an important step for the understanding of the genesis and biological behavior of these diseases. The Ki-67 proteins, which are markers of the cellular proliferation, and p53, which is the product of the tumor suppressor gene TP53, are both important tumoral markers. This study intends to identify and quantify the Ki-67 and p53 proteins in astrocytic tumors of different grades of malignancy, as well as to analyze their relations with age and gender. Ki-67 and p53 proteins in 47 patients with surgically resected astrocytic neoplasms were studied through immunohistochemistry. They have been previously classified and reviewed concerning their histological grade, as suggested by the World Health Organization. The immunomarked cellular nuclei were quantified by the program Imagelab-softium for the absolute parametric reason between the nuclei of the positive cells and the total amount of tumoral cells, being counted 1000 cells. The lineation used has been transversal not controlled. For the statistical analysis the variables were divided into groups. For the Ki-67 they were absent, <5% and >5% and for p53 they were absent (0), <25% (1+), between 25 and 50% (2+), between 50 and 75% (3+), and higher than 75% (4+). Ki-67 was present in 37 cases (78.72%) evidencing a correlation with a higher malignancy degree (p<0,001). p53 was present in 14 cases (35.13%) with a higher correlation with astrocytoma grade IV (p=0.59). There has not been a statistically significant correlation between p53 and Ki-67, as well as among these variables, age and gender. The hypotheses of a greater presence of Ki-67 and p53 in astrocytic neoplasms with a higher degree of malignancy, except for the correlation between grade III and p53, is corroborated by the results of this study.

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      Most cited references 34

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      Influence of p53 mutations on prognosis of patients with glioblastoma.

      The influence of p53 mutations on the biology of astrocytic tumors is controversial. p53 is thought to be inactivated in the early stage of gliomagenesis; however, what role its inactivation plays in the malignancy of gliomas remains unknown. To understand the significance of p53 inactivation, the authors identified the locus of p53 gene mutation in glioma samples at different stages of progression and studied the correlation between the mutation and clinical behavior. Samples from newly diagnosed gliomas, including pure and mixed astrocytomas, were analyzed for p53 mutations using a yeast functional assay. To determine the locus of the gene mutations, DNA sequencing was performed. The incidence of p53 mutations was higher in anaplastic astrocytomas (AA, 48%) than glioblastomas (GBM, 31%). There was no significant difference in the average ages of GBM patients with and without p53 mutations (54.9 years +/- 2.3 and 53.2 years +/- 4.6, respectively). In GBM patients, the mutation did not affect progression free survival or overall survival. Astrocytomas and GBM differed in the distribution of p53 mutation loci. The p53 gene mutation does not markedly affect the survival of GBM patients. The difference in the location of p53 mutations between AA and GBM suggests that in gliomas, the p53 mutation may contribute not only to tumorigenesis (as an early event) but also to progression to malignancy (as a late event). Copyright 2002 American Cancer Society.DOI 10.1002/cncr.10677
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        High frequency of p53 protein accumulation without p53 gene mutation in human juvenile pilocytic, low grade and anaplastic astrocytomas.

        We analysed 31 non-glioblastoma astrocytomas for alterations in p53 protein expression and for mutations in the p53 gene. Immunohistochemistry detected p53 protein accumulation in 71% (five of seven) of juvenile pilocytic astrocytomas (WHO grade I), 63% (five of eight) of astrocytomas (WHO grade II), and 63% (10 of 16) of anaplastic astrocytomas (WHO grade III). The single strand conformation polymorphism (SSCP) assay of exons 2-11 of the p53 gene and direct DNA sequencing identified p53 mutations in 14% (one of seven) of grade I, 25% (two of eight) of grade II, and 19% (three of 16) of grade III astrocytomas. This is the first report of a p53 mutation in grade I juvenile pilocytic astrocytomas. Immunohistochemistry and SSCP analyses gave concordant results in 55% (17 of the 31) of the tumors. A total of 14 tumors, 60-80% within each grade, showed p53 protein accumulation in the absence of detectable mutations of the p53 gene. No mdm-2 gene amplification was found in these tumors. The similar frequency of p53 alterations in tumors of grades I-III suggests that the p53 gene plays a significant role early in the formation of astrocytomas rather than late in tumor progression to higher grade. The data suggest that mechanisms other than p53 gene inactivation by mutation or mdm-2 complex formation result in the accumulation of P53 protein in > 70% of non-glioblastoma astrocytomas.
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          Loss of DCC expression in astrocytomas: relation to p53 abnormalities, cell kinetics, and survival

           A Hara,  M Saegusa,  T MIKAMI (2001)
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            Author and article information

            Affiliations
            [1 ] IPEM
            [2 ] Universidade Federal do Paraná Brazil
            [3 ] FEPAR
            [4 ] Universidade de São Paulo Brazil
            [5 ] UNICENP
            [6 ] HUEC
            Contributors
            Role: ND
            Role: ND
            Role: ND
            Role: ND
            Role: ND
            Role: ND
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            Role: ND
            Journal
            anp
            Arquivos de Neuro-Psiquiatria
            Arq. Neuro-Psiquiatr.
            Academia Brasileira de Neurologia - ABNEURO (São Paulo )
            1678-4227
            December 2005
            : 63
            : 4
            : 997-1004
            S0004-282X2005000600017
            10.1590/S0004-282X2005000600017

            http://creativecommons.org/licenses/by/4.0/

            Product
            Product Information: SciELO Brazil
            Categories
            NEUROSCIENCES
            PSYCHIATRY

            Neurosciences, Clinical Psychology & Psychiatry

            astrocytoma, p53, Ki-67, astrocitoma

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