HAMILTON MATUSHITA
Projetos de Pesquisa
Unidades Organizacionais
Instituto Central, Hospital das Clínicas, Faculdade de Medicina
2 resultados
Resultados de Busca
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- PROP1 and CTNNB1 expression in adamantinomatous craniopharyngiomas with or without beta-catenin mutations(2011) CANI, Carolina M. G.; MATUSHITA, Hamilton; CARVALHO, Luciani R. S.; SOARES, Ibere C.; BRITO, Luciana P.; ALMEIDA, Madson Q.; MENDONCA, Berenice B.INTRODUCTION: Activating mutations in exon 3 of the beta-catenin gene are involved in the pathogenesis of adamantinomatous craniopharyngiomas. Recently, the interaction between beta-catenin and PROP1 has been shown to be responsible for pituitary cell lineage determination. We hypothesized that dysregulated PROP1 expression could also be involved in the pathogenesis of craniopharyngiomas. OBJECTIVES: To determine whether dysregulated gene expression was responsible for tumor pathogenesis in adamantinomatous craniopharyngiomas, the beta-catenin gene was screened for mutations, and the expression of the beta-catenin gene and PROP1 was evaluated. METHODS: The beta-catenin gene was amplified and sequenced from 14 samples of adamantinomatous craniopharyngiomas. PROP1 and beta-catenin gene expression was assessed by real-time RT-PCR from 12 samples, and beta-catenin immunohistochemistry was performed on 11 samples. RESULTS: Mutations in the beta-catenin gene were identified in 64% of the adamantinomatous craniopharyngiomas samples. Evidence of beta-catenin gene overexpression was found in 71% of the tumors with beta-catenin mutations and in 40% of the tumors without mutations, and beta-catenin immunohistochemistry revealed a nuclear staining pattern for each of the analyzed samples. PROP1 expression was undetectable in all of the tumor samples. CONCLUSION: We found evidence of beta-catenin gene overexpression in the majority of adamantinomatous craniopharyngiomas, and we also detected a nuclear beta-catenin staining pattern regardless of the presence of a beta-catenin gene mutation. These results suggest that WNT signaling activation plays an important role in the pathogenesis of adamantinomatous craniopharyngiomas. Additionally, this study was the first to evaluate PROP1 expression in adamantinomatous craniopharyngiomas, and the absence of PROP1 expression indicates that this gene is not involved in the pathogenesis of this tumor, at least in this cohort.
- CTNNB1, AXIN1 and APC expression analysis of different medulloblastoma variants(2013) SILVA, Roseli da; MARIE, Suely K. N.; UNO, Miyuki; MATUSHITA, Hamilton; WAKAMATSU, Alda; ROSEMBERG, Sergio; OBA-SHINJO, Sueli M.OBJECTIVES: We investigated four components of the Wnt signaling pathway in medulloblastomas. Medulloblastoma is the most common type of malignant pediatric brain tumor, and the Wnt signaling pathway has been shown to be activated in this type of tumor. METHODS: Sixty-one medulloblastoma cases were analyzed for beta-catenin gene (CTNNB1) mutations, beta-catenin protein expression via immunostaining and Wnt signaling pathway-related gene expression. All data were correlated with histological subtypes and patient clinical information. RESULTS: CTNNB1 sequencing analysis revealed that 11 out of 61 medulloblastomas harbored missense mutations in residues 32, 33, 34 and 37, which are located in exon 3. These mutations alter the glycogen synthase kinase-3 beta phosphorylation sites, which participate in beta-catenin degradation. No significant differences were observed between mutation status and histological medulloblastoma type, patient age and overall or progression-free survival times. Nuclear beta-catenin accumulation, which was observed in 27.9% of the cases, was not associated with the histological type, CTNNB1 mutation status or tumor cell dissemination. The relative expression levels of genes that code for proteins involved in the Wnt signaling pathway (CTNNB1, APC, AXIN1 and WNT1) were also analyzed, but no significant correlations were found. In addition, large-cell variant medulloblastomas presented lower relative CTNNB1 expression as compared to the other tumor variants. CONCLUSIONS: A small subset of medulloblastomas carry CTNNB1 mutations with consequent nuclear accumulation of beta-catenin. The Wnt signaling pathway plays a role in classic, desmoplastic and extensive nodularity medulloblastoma variants but not in large-cell medulloblastomas.