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Doctoral Thesis
DOI
https://doi.org/10.11606/T.17.2019.tde-27052020-081149
Document
Author
Full name
Mirella Baroni Milan
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2019
Supervisor
Committee
Tone, Luiz Gonzaga (President)
Leopoldino, Andréia Machado
Lopes, Luiz Fernando
Panepucci, Rodrigo Alexandre
Title in Portuguese
Avaliação do envolvimento das quinases MST1 e MST2 no Meduloblastoma e seu papel na regulação de vias moleculares associadas
Keywords in Portuguese
Droga XMU-MP-1
Meduloblastoma
Quinases MST1 e MST2
Silenciamento gênico
Vias moleculares de desenvolvimento
Abstract in Portuguese
O Meduloblastoma (MB) é a neoplasia maligna do sistema nervoso central mais frequente na infância. Apesar dos avanços, cerca de um terço dos pacientes vão à óbito devido à recorrência do tumor e a maioria dos sobreviventes sofre efeitos secundários a longo prazo. A biologia tumoral do MB está associada com a desregulação de vias de sinalização que controlam o desenvolvimento embrionário, como as vias Wnt, Shh, Notch, TGF-β e Hippo. Estudos mostram que essas vias cooperam na carcinogênese e progressão do MB, mas ainda faltam dados de como ocorre a interação dessas vias e quais proteínas podem estar envolvidas nessas redes. Alguns trabalhos apontam as quinases MST1 e MST2 como proteínas chave na regulação dessas vias moleculares em diferentes tumores. Portanto o objetivo do presente estudo foi analisar o envolvimento das quinases MST1 e MST2 no MB e avaliar seu papel na regulação das vias moleculares associadas. Primeiro foi realizada a análise da expressão gênica de MST1 e MST2 nas amostras e subgrupos moleculares de MB e nos cerebelos não-neoplásicos. Em seguida, foram realizados ensaios in vitro após inibição farmacológica de MST1/2 e após transfecção com siRNA nas linhagens celulares de MB. Foi realizada análise in silico de enriquecimento de vias com os genes correlacionados com a expressão de MST2 e alguns desses genes foram validados. Os principais resultados foram que MST2 possui uma maior expressão gênica nas amostras tumorais e linhagens celulares de MB quando comparada com a expressão nos cerebelos, e a expressão gênica de MST2 é maior nos subgrupos moleculares WNT e SHH. Não existe diferença na expressão de MST1 nas amostras de MB quando comparada com cerebelos e entre os subgrupos moleculares. A inibição farmacológica de MST1/2 e o silenciamento gênico de MST2 promoveram uma diminuição na viabilidade celular e na formação de colônias e provocou alterações no ciclo celular. Na análise in silico, os genes mais correlacionados com MST2 participam das vias moleculares Wnt, Hippo, TGF-β e Shh, e a inibição de MST1/2 promoveu alteração da expressão de alvos dessas vias. Com esses dados pode-se observar que a MST2 regula mecanismos importantes para a progressão tumoral e está envolvido com relevantes vias em MB, sendo um promissor alvo terapêutico para este tumor.
Title in English
Evaluation of MST1 and MST2 kinases involvement in Medulloblastoma and their role regulating associated molecular pathways
Keywords in English
Developmental signaling pathways
Knockdown
Medulloblastoma
MST1 and MST2 Kinase
XMU-MP-1 drug
Abstract in English
Medulloblastoma (MB) is the most common malignant tumor of the central nervous system in childhood. Despite the advances, about one third of patients die due to tumor recurrence and most survivors suffer long-term side effects. Biology of MB is associated with the dysregulation of signaling pathways that control embryonic development, such as the Wnt, Shh, Notch, TGF-β, and Hippo pathways. Studies show that these pathways cooperate in the carcinogenesis and progression of MB, but data are still lacking on how this interaction occurs and which proteins may be involved in this network. Some studies point to MST1 and MST2 kinases as key proteins in the regulation of these molecular pathways in different tumors. Therefore, the aim of the present study was to analyze the involvement of MST1 and MST2 kinases in MB and to evaluate their role in the regulation of associated molecular pathways. First, we analyzed the gene expression of MST1 and MST2 in MB samples and molecular subgroups and in non-neoplastic cerebellum. Subsequently, in vitro assays were performed after pharmacological inhibition of MST1/2 and after siRNA transfection in MB cell lines. Pathway enrichment in silico analysis was performed with genes correlated with MST2 expression and some of these genes were validated. The main results were that MST2 has a higher expression in MB tumor samples and cell lines when compared with expression in the cerebellum, and MST2 expression is higher in the WNT and SHH molecular subgroups. There is no difference in MST1 expression in MB samples compared to cerebellum and between molecular subgroups. Pharmacological inhibition of MST1/2 and gene silencing of MST2 promoted a decrease in cell viability and colony formation and caused changes in the cell cycle. In silico analysis showed that the genes most correlated with MST2 participate in the Wnt, Hippo, TGF-β and Shh pathways, and inhibition of MST1/2 promoted expression alteration of some target pathways. With these data it can be observed that MST2 regulates important mechanisms for tumor progression and is involved with relevant pathways in MB, being a promising therapeutic target for this tumor.
 
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Publishing Date
2020-07-13
 
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