ABSTRACT
OBJECTIVE: ASCT2 and LAT1 are aminoacid transporters involved in glutamine transport and play a role in tumor growth. Previous studies have shown an association of ASCT2 to cell proliferation through the mechanistic Target of Rapamycin (mTOR) translational machinery; LAT1 has been shown as a prognostic marker due to its relation to tumor invasion, microscopic vascular invasion and metastasis. This study analyzed the gene expression of ASCT2 and LAT1 in astrocytomas of different grades and how this correlates to clinical outcome in glioblastoma patients. METHOD: This is an observational study with ASCT2 and LAT1 mRNA expression analysis in 153 samples of human astrocytomas, distributed in different World Health Organization (WHO) grades of malignancy (23 at grade I or pilocytic astrocytoma, 26 at grade II or low-grade astrocytoma, 18 at grade III or anaplastic astrocytoma, 86 at grade IV astrocytoma or glioblastoma (AGIV or GBM)); these were compared to 22 non-neoplastic brain samples. RESULTS: Significant hyperexpression of both genes was observed particularly in malignant astrocytomas (GIII & GBM). Moreover, LAT1 hyperexpression impacted negatively in the overall survival in a subset of GBM patients. CONCLUSION: LAT1 is more expressed in higher grade astrocytomas. It leads to a poorer prognosis among GBM patients and may be a potential therapeutical target.
OBJETIVO: ASCT2 e LAT1 são transportadores de aminoácidos envolvidos no transporte de glutamina e desempenham um papel no crescimento tumoral. Estudos prévios mostraram uma associação de ASCT2 com proliferação celular através da maquinaria de tradução do mTOR; tem sido mostrado que o LAT1 é um marcador prognóstico devido à sua relação com invasão tumoral, invasão vascular microscópica e metástase. Este estudo analisou a expressão gênica de ASCT2 e LAT1 em astrocitomas de diferentes graus e sua correlação com desfecho clínico em pacientes com glioblastoma. METODO: Este é um estudo observacional com análise de expressão de RNAm de ASCT2 e LAT1 em 153 amostras de astrocitomas humanos, distribuídas em diferentes graus de malignidade segundo a OMS (23 astrocitomas de grau I ou astrocitoma pilocítico, 26 de astrocitoma de grau II ou astrocitoma de baixo grau, 18 de astrocitoma de grau III ou astrocitoma anaplásico, 86 de astrocitoma de grau IV ou glioblastoma (AGIV ou GBM); estes foram comparados com 22 amostras cerebrais não neoplásicas. RESULTADOS: Foi observada uma hiperexpressão de ambos os genes, particularmente nos astrocitomas malignos (GIII & GBM). Além disso, a hiperexpressão LAT1 impactou negativamente na sobrevida global em um grupo de pacientes com GBM. CONCLUSÃO: LAT1 é mais expresso em astrocitomas de grau maior. Isso leva a um pior prognóstico entre os pacientes com GBM e pode ser um potencial alvo terapêutico.
Subject(s)
Humans , Astrocytoma , Gene Expression , Glioblastoma/pathology , Large Neutral Amino Acid-Transporter 1/analysis , GlutamineABSTRACT
O desenvolvimento e invasão de tumores cerebrais primários são diretamente influenciados pela matriz extracelular. Considerando que lisil oxidase (LOX) e os demais membros da família das lisil oxidases (LOXL1, LOXL2, LOXL3 e LOXL4) apresentam complexidade tanto estrutural quanto funcional e estão envolvidos em processos biológicos vitais, como motilidade celular, sinalização celular e regulação gênica, a desregulação da expressão destas proteínas pode levar à gênese e progressão tumoral. O presente trabalho teve como objetivos avaliar os níveis de expressão dos genes que codificam todos os membros da família das lisil oxidases em astrocitomas de diferentes graus de malignidade e correlacionar com a expressão de BMP1 e HIF1A, mutação de IDH1 e tempo de sobrevida total dos pacientes. Adicionalmente, as expressões das proteínas codificadas por estes genes foram também realizadas, além de um estudo funcional in vitro do papel de LOX em astrocitomas. A análise da expressão dos genes foi realizada por PCR quantitativa em tempo real numa série de 153 astrocitomas e 22 amostras de tecido cerebral não neoplásico. A expressão proteica foi conduzida por imuno-histoquímica em amostras de astrocitomas. O silenciamento da expressão de LOX foi realizado em linhagens celulares de glioblastoma humano U87MG e A172 transfectadas com o siRNA para os ensaios funcionais. A expressão de todos os genes (LOX, LOXL1, LOXL2, LOXL3, LOXL4, BMP1 e HIF1A) aumentou com o grau de malignidade dos astrocitomas, com maiores níveis nos casos de glioblastoma. Foi encontrada uma correlação positiva nos valores de expressão dos genes principalmente nos glioblastomas. Somente a expressão de LOXL3 teve um impacto na sobrevida dos casos com GBM. Pacientes com maior expressão apresentaram maior sobrevida em relação aos com menor expressão de LOXL3. Os casos de astrocitoma grau II com mutação de IDH1 apresentaram menor expressão de LOXL1 e de LOXL4 quando comparados com os casos sem mutação. Os casos...
The development and invasion of primary brain tumors are directly influenced by the extracellular matrix. Considering that lysyl oxidase (LOX) and other lysyl oxidase family members (LOXL1, LOXL2, LOXL3 e LOXL4) have both structural and functional complexity and that they are involved in vital biological processes such as cell motility, cell signaling and gene regulation, a deregulation of these proteins can lead to the genesis and tumor progression. This study aimed to evaluate the expression levels of genes that code for the lysyl oxidase family members in astrocytomas of different malignant grades and to correlate to the expression of BMP1 and HIF1A, IDH1 mutation and overall patients' survival. Moreover, protein expression coded by these genes was also analyzed, besides an in vitro functional study of LOX role in astrocytomas. Gene expression analysis was performed by quantitative real-time PCR in a series of 153 astrocytomas and 22 samples of non-neoplastic brain. Protein expression was analyzed by immunohistochemistry in astrocytoma samples. LOX knockdown was performed in cells of human glioblastoma U87MG and A172 transfected with siRNA. Expression levels of all genes (LOX, LOXL1, LOXL2, LOXL3, LOXL4, BMP1 e HIF1A) increased with the malignant grade of astrocytomas, glioblastomas presenting the higher levels. Positive correlations of gene expression values were observed specially in glioblastomas. Only LOXL3 expression impacted in the overall survival of glioblastoma cases. Patients with higher expression presented longer survival time than those with lower LOXL3 expression. Astrocytoma grade II cases with IDH1 mutation presented lower LOXL1 and LOXL4 expression when compared to those cases with wild type IDH1. On the other hand, GBM cases with IDH1-mutated presented lower LOX and LOXL1 expression than GBM cases without IDH1 mutation. Protein expression levels of lysyl oxidase family members were also higher in glioblastoma samples, with both nuclear...
Subject(s)
Humans , Astrocytoma , Gene Expression , Genetic Association Studies , Glioblastoma , Glioma/genetics , Immunohistochemistry , Mutation , Biomarkers, Tumor , Prognosis , Real-Time Polymerase Chain ReactionABSTRACT
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 β-catenin gene (CTNNB1) mutations, β-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-3β phosphorylation sites, which participate in β-catenin degradation. No significant differences were observed between mutation status and histological medulloblastoma type, patient age and overall or progression-free survival times. Nuclear β-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 β-catenin. The Wnt signaling pathway plays a role in classic, desmoplastic and extensive nodularity medulloblastoma variants but not in large-cell medulloblastomas.
Subject(s)
Adult , Child , Female , Humans , Male , Adenomatous Polyposis Coli Protein/analysis , Axin Protein/analysis , Cerebellar Neoplasms/pathology , Medulloblastoma/pathology , beta Catenin/analysis , Adenomatous Polyposis Coli Protein/metabolism , Axin Protein/metabolism , Chi-Square Distribution , Cerebellar Neoplasms/genetics , Cerebellar Neoplasms/metabolism , Disease-Free Survival , Gene Expression , Medulloblastoma/genetics , Medulloblastoma/metabolism , Real-Time Polymerase Chain Reaction , Statistics, Nonparametric , Wnt Signaling Pathway , beta Catenin/metabolismABSTRACT
Pompe's disease (PD) is a metabolic myopathy caused by the accumulation of lysosomal glycogen, secondary to acid α-glucosidase (GAA) enzyme deficiency. Childhood and late-onset forms are described, differing by the age of onset and symptoms. In this study were analyzed affected siblings with Pompe's disease (PD) and their distinct clinical and pathological presentations. METHOD: Diagnosis was performed by the clinical presentation of limb-girdle dystrophies and respiratory compromise. Confirmatory diagnoses were conducted by muscle biopsy, GAA activity measurement and by GAA gene genotyping. RESULTS: The findings suggested muscular involvement due to GAA deficiency. GAA genotyping showed they are homozygous for the c.-32-3C>A mutation. CONCLUSION: Herein we reported a family where three out of five siblings were diagnosed with late-onset PD, although it is a rare metabolic disease inherited in an autossomal recessive manner. We emphasize the importance of including this presentation within the differential diagnoses of the limb-girdle dystrophies once enzyme replacement therapy is available.
A doença de Pompe (DP) é uma miopatia originada do acúmulo lisossomal de glicogênio, devido à deficiência da enzima α-glicosidase ácida (GAA), sendo descritas formas de inicio precoce e tardio. Neste estudo analisamos retrospectivamente o perfil clinico e patológico de 3 irmãos portadores de doença de Pompe de inicio tardio. MÉTODO: O diagnóstico foi realizado mediante apresentação clinica de distrofia de cinturas associado a comprometimento respiratório, sendo confirmado por biópsia muscular e análise da atividade e genotipagem da GAA. RESULTADOS: Os exames clínicos e laboratoriais demonstram envolvimento muscular devido à deficiência da GAA, com uma mutação c.-32-3C>A em homozigose. CONCLUSÃO: Relatamos os aspectos clínicos e laboratoriais de 3 irmãos afetados por doença de Pompe de início tardio. Enfatizamos a importância de incluir esta patologia no diagnóstico diferencial das distrofias de cinturas, uma vez que para esta patologia específica existe a possibilidade terapêutica através de reposição enzimática.
Subject(s)
Adult , Female , Humans , Male , Middle Aged , Glycogen Storage Disease Type II/genetics , Homozygote , Mutation/genetics , alpha-Glucosidases/deficiency , alpha-Glucosidases/genetics , Creatine Kinase/blood , Electromyography , Genotype , Glycogen Storage Disease Type II/diagnosis , Phenotype , Polysomnography , Siblings , SpirometryABSTRACT
INTRODUCTION: Astrocytic gliomas are the most common intracranial central nervous system neoplasias, accounting for about 60 percent of all primary central nervous system tumors. Despite advances in the treatment of gliomas, no effective therapeutic approach is yet available; hence, the search for a more realistic model to generate more effective therapies is essential. OBJECTIVE: To develop an experimental malignant astrocytoma model with the characteristics of the human tumor. METHOD: Primary cells from subcutaneous xenograft tumors produced with malignant astrocytoma U87MG cells were inoculated intracerebrally by stereotaxis into immunosuppressed (athymic) Rowett rats. RESULTS: All four injected animals developed non-infiltrative tumors, although other glioblastoma characteristics, such as necrosis, pseudopalisading cells and intense mitotic activity, were observed. CONCLUSION: A malignant astrocytoma intracerebral xenograft model with poorly invasive behavior was achieved in athymic Rowett rats. Tumor invasiveness in an experimental animal model may depend on a combination of several factors, including the cell line used to induce tumor formation, the rat strains and the status of the animal's immune system.
Subject(s)
Animals , Female , Humans , Rats , Astrocytoma/pathology , Brain Neoplasms/pathology , Glioblastoma/pathology , Immunocompromised Host , Brain Neoplasms/immunology , Cell Line, Tumor , Disease Models, Animal , Glioblastoma/immunology , Neoplasm Transplantation , Rats, Nude , Transplantation, HeterologousABSTRACT
PURPOSE: Data are conflicting concerning the risk for ischemic stroke associated with a common polymorphism in the gene encoding 5,10-methylenetetrahydrofolate reductase C677T, which predisposes carriers to hyperhomocysteinemia. A meta-analysis study suggested that the 5,10-methylenetetrahydrofolate reductase 677TT genotype might have a small influence in determining susceptibility to ischemic stroke. METHODS: We analyzed the 5,10-methylenetetrahydrofolate reductase 677TT genotype polymorphism in Brazilian subjects with ischemic stroke, using a case-control design. RESULTS: We compared 5,10-methylenetetrahydrofolate reductase genotypes in groups of subjects presenting ischemic stroke (n = 127) and normal control (n = 126) and found an odds ratio of 1.97 (95 percent CI, 0.84-4.64) in a multivariate analysis in which results were adjusted to baseline clinical characteristics of study participants. CONCLUSION: We found that the homozygous 5,10-methylenetetrahydrofolate reductase C677T genotype was not a risk factor for ischemic stroke in these Brazilian subjects.
OBJETIVO: Os dados são conflitantes em relação a risco de acidente cerebrovascular associado a polimorfismo do gene 5,10-metilenetetrahidrofolato redutase C677T, o qual predispõe a hiperhomocisteinemia. Um estudo de meta-análise sugere que o genotipo 5,10-metilenetetrahidrofolato redutase 677TT poderia ter uma pequena influência em determinar susceptibilidade a acidente cerebrovascular. MÉTODOS: Analisamos este polimorfismo em indivíduos brasileiros com acidente cerebrovascular isquêmico, baseando-se em um estudo de caso-controle. RESULTADOS: Comparamos os genótipos 5,10-metilenetetrahidrofolato redutase em grupos de indivíduos com acidente cerebrovascular isquêmico (n=127) e controle normal (n=126), e encontramos Odds Ratio de 1,97 (IC 95 por cento 0,84 - 4,64) em uma análise multivariada, na qual os resultados foram ajustados a características clínicas basais dos indivíduos estudados. DISCUSSÃO: Nossos estudos indicam que o genótipo 5,10-metilenetetrahidrofolato redutase C677T não é um fator de risco para acidente cerebrovascular isquêmico entre indivíduos brasileiros.