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Doctoral Thesis
DOI
10.11606/T.17.2009.tde-02032010-121437
Document
Author
Full name
Luciana Oliveira de Almeida
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2009
Supervisor
Committee
Casartelli, Cacilda (President)
Ferraz, Victor Evangelista de Faria
Mendes Junior, Celso Teixeira
Smith, Marilia de Arruda Cardoso
Vretos, Christina
Title in Portuguese
Análise epigenética e de polimorfismos em tumores extra-axiais do sistema nervoso
Keywords in Portuguese
Meningiomas
Metástases
Metilação
Polimorfismos
Schwanomas
Abstract in Portuguese
Os tumores extra-axias do sistema nervoso são de localização extra-cerebral e na maioria das vezes benignos; meningiomas, schwanomas e metástases fazem parte deste grupo. O aparecimento de um tumor ocorre a partir do acúmulo de alterações genéticas e epigenéticas nas células. Para entender o mecanismo molecular da progressão tumoral e a formação de metástases é indispensável identificar os genes que acumulam essas alterações. Sendo assim, este trabalho teve como objetivo analisar o perfil de metilação dos genes TP16, TP53, DAL-1, GSTP-1, MEN-1, NDRG2 e das DNA metiltransferases 3A, 3B e 3L e sua associação com os tumores extra-axiais e ainda, avaliar, através de um estudo caso-controle, a influência dos SNPs TP53 Pro47Ser e Arg72Pro, EGF + 61, GSTP-1 Ile105Val e WRN Cys1367Arg no desenvolvimento e prognóstico desses tumores. A técnica utilizada para a análise de hipermetilação foi a MSP, e através dela observamos que a atividade das DNMTs não está associada à metilação dos tumores extra-axiais e ainda, os perfis de metilação das DNMTs de novo não estão associados com alterações no padrão de metilação dos genes TP16, TP53, DAL-1, GSTP-1, MEN- 1 e NDRG2. Observamos que a metilação do gene TP53 está associada principalmente aos tumores de maior grau de malignidade, a uma deficiência na resposta a tratamentos e, conseqüentemente, a um maior número de óbitos. A metilação do gene TP16 está envolvida mais freqüentemente na formação de schwanomas e a de NDRG2 na progressão dos meningiomas. A análise de polimorfismos foi realizada através da técnica de PCR-RFLP e observamos diferenças nas distribuições genotípicas entre pacientes e controles nos SNPs TP53 Pro47Ser e Arg72Pro, EGF + 61 e GSTP-1 Ile105Val, onde as variantes Ser47, Pro72, EGF G61 e Val105 foram observadas com maior freqüência entre os portadores de tumores extra-axiais. Dessa forma, estas variantes podem ser fatores de susceptibilidade para o desenvolvimento dos tumores.
Title in English
Epigenetic and Polymorphism Analysis in Extra-Axial Brain Tumors.
Keywords in English
Meningioma
Metastasis
Methylation
Polymorphism
Schwannoma
Abstract in English
The extra-axial brain tumors have extra-brain localization and in most of the time they are benign, meningiomas, schwannomas and metastasis are included in this group. The appearance of a tumor occurs because of the accumulation of genetic and epigenetic alterations in the cells. In order to understand the molecular mechanism of the tumor progression and the metastasis formation it is important to identify the genes that accumulate the alterations. Thereby, the objective of this study was to analyze the methylation profile of the genes TP16, TP53, DAL-1, GSTP-1, MEN-1, NDRG2 and the DNA methyltransferases 3A, 3B and 3L and their association with the extra-axial brain tumors. Another purpose was to determine, in a case-control study, the roles of the TP53 Pro47Ser and Arg72Pro, EGF + 61, GSTP-1 Ile105Val and WRN Cys1367Arg SNPs in the development and prognosis of these tumors. We used the MSP to screen the hypermethylation profile and we observed no association between the DNMTs activity and the hypermethylation of the tumors. We also did not find association between the methylation of the DNMTs de novo and alterations in the methylation profile of the genes TP16, TP53, DAL-1, GSTP-1, MEN-1 and NDRG2. We observed that TP53 hypermethylation was associated with the high grade tumors, a poor response to the treatments and, consequently, the high number of obits. The TP16 methylation was involved with the shwannomas formation and the NDRG2 gene was involved in the meningiomas progression. For the polymorphism analysis, we used the PCR-RFLP technique and we observed differences in the genotype distributions between cases and controls of TP53 Pro47Ser and Arg72Pro, EGF + 61 and GSTP-1 Ile105Val SNPs, where the variants Ser47, Pro72, EGF G61 and Val105 were more frequent in patients than in controls. Thus, these variants can be important factors of susceptibility to the tumor development.
 
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Publishing Date
2010-03-16
 
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