Navegando por Assunto "Neoplasias encefálicas"

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Acesso aberto (Open Access)
Epigenetic alterations in human brain tumors in a Brazilian population
(2006) ANSELMO, Nilson Praia; BELLO, Maria Josefa; GONZALEZ-GOMEZ, Pilar; DIAS, Luis Antonio Araújo; ALMEIDA, José Reinaldo Walter de; SANTOS, Marcelo José dos; HERRANZ, Juan Antonio Rey; CASARTELLI, Cacilda
Aberrant methylation of CpG islands located in promoter regions represents one of the major mechanisms for silencing cancer-related genes in tumor cells. We determined the frequency of aberrant CpG island methylation for several tumor-associated genes: DAPK, MGMT, p14ARF, p16INK4a, TP73, RB1 and TIMP-3 in 55 brain tumors, consisting of 26 neuroepithelial tumors, 6 peripheral nerve tumors, 13 meningeal tumors and 10 metastatic brain tumors. Aberrant methylation of at least one of the seven genes studied was detected in 83.6% of the cases. The frequencies of aberrant methylation were: 40% for p14ARF, 38.2% for MGMT, 30.9% for, p16INK4a, 14.6% for TP73 and for TIMP-3, 12.7% for DAPK and 1.8% for RB1. These data suggest that the hypermethylation observed in the genes p14ARF, MGMT and p16INK4a is a very important event in the formation or progression of brain tumors, since the inactivation of these genes directly interferes with the cell cycle or DNA repair. The altered methylation rate of the other genes has already been reported to be related to tumorigenesis, but the low methylation rate of RB1 found in tumors in our sample is different from that so far reported in the literature, suggesting that perhaps hypermethylation of the promoter is not the main event in the inactivation of this gene. Our results suggest that hypermethylation of the promoter region is a very common event in nervous system 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