Navegando por Assunto "Meduloblastomas"

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Acesso aberto (Open Access)
Análises dos genes TP53, PTEN, IDH1 e IDH2 em tumores não gliais do sistema nervoso humano
(Universidade Federal do Pará, 2016-06-17) LOPES, Cleiton Mendes; ANSELMO, Nilson Praia; http://lattes.cnpq.br/6518287721873199
Despite the considerable incidence, studies of genetic changes in gene TP53, PTEN, IDH2 and IDH1, in not glial tumors are rare and, in some cases, nonexistent. Glial tumors are usually not classified as benign and rarely evolve to malignancy, with different classifications, effects and locations. The tumor suppressor genes and response to DNA damage, TP53 and PTEN are among the most commonly mutated gene in human tumors. The genes IDH1 and IDH2 are involved in cell metabolism and also were frequently found mutated in gliomas, melanomas and leukemias, currently being considered as good markers for gliomas. Genetic analyzes were performed in those genes, in order to verify that are associated with the etiology and/or progression of non-glial tumors of Human Nervous System (HNS). SSCPPCR techniques for the amplification of the region of interest and mutational screening of samples for subsequent sequencing were used. We analyzed 37 samples of non-glial tumors (14 schwannomas, meningiomas 3, 4 Medulloblastomas, 2 neurocytomas and 14 metastases of Central Nervous System (CNS). Only the gene IDH1 polymorphisms presented on the SSCP 12 (32.4%) samples, and then subjected to sequencing. However, sequencing reactions were satisfactory in only 5 samples, of the polymorphic, (1 metastasis, meningioma 1 and 3 schwannomas). Analysis of these samples have identified 5 different mutations, one present in all, one transversion T → A in codon 106 of exon 4 of the IDH1 gene resulting in amino acid substitution of threonine by serine. Were also identified other mutations in noncoding regions (intron 4) of gene IDH1 in two of these samples. The mutations found in our study had not yet been reported in the literature. Our results indicate the participation the gene IDH1 in the pathogenesis of these tumors.
Acesso aberto (Open Access)
Valor prognóstico do SNP TP53 ARG72PRO na susceptibilidade ao desenvolvimento e na sobrevida de pacientes brasileiros com meduloblastoma
(Universidade Federal do Pará, 2011-12-22) CARVALHO, Raimundo Miranda de; BURBANO, Rommel Mario Rodriguéz; http://lattes.cnpq.br/4362051219348099
Medulloblastoma is a highly cellular malignant embryonal neoplasm, and it is the most common malignant pediatric brain tumor, comprising 20 to 25% of pediatric central nervous systen tumors. To investigate the role of the TP53 Arg72Pro single nucleotide polymorphism (SNP) on medulloblastoma risk, medulloblastoma prognosis, and adjuvant therapy response, we performed a case-control study with 122 patientes and 122 healthy controls from Brazil. Compared to Arg/Arg, which is the most common genotype in the study population, both the Arg/Pro and Pro/Pro genotypes did not influence the medulloblastoma development risk (OR= 1.36 and P= 0.339 for the Arg/Pro genotype; OR=1.50 and P=0.389 for the Pro/Pro genotype). With regard to prognosis, the disease-free survival was not significantly different among the TP53 Arg72Pro SNP genotypes (P > 0.05), but the less frequent genotype, Pro/Pro, was associated with a shorter overall survival of medulloblastoma patients (P= 0.021). These data suggested that although there is no association between the TP53 Arg72Pro and medulloblastoma risk, the Pro/Pro genotype is associated with a shorter overall survival of patients submitted to adjuvant therapy. Nevertheless, due to the interethnic composition of the Brazilian population, future studies on larger populations from other parts of the world are essential for a definitive conclusion of the function of the TP53 Arg72Pro SNP