RESUMO
Using in silico analysis of The Cancer Genome Atlas (TCGA), we identified microRNAs associated with glioblastoma (GBM) survival, and predicted their functions in glioma growth and progression. Inhibition of two "risky" miRNAs, miR-148a and miR-31, in orthotopic xenograft GBM mouse models suppressed tumor growth and thereby prolonged animal survival. Intracranial tumors treated with uncomplexed miR-148a and miR-31 antagomirs exhibited reduced proliferation, stem cell depletion, and normalized tumor vasculature. Growth-promoting functions of these two miRNAs were, in part, mediated by the common target, the factor inhibiting hypoxia-inducible factor 1 (FIH1), and the downstream pathways involving hypoxia-inducible factor HIF1α and Notch signaling. Therefore, miR-31 and miR-148a regulate glioma growth by maintaining tumor stem cells and their niche, and providing the tumor a way to activate angiogenesis even in a normoxic environment. This is the first study that demonstrates intratumoral uptake and growth-inhibiting effects of uncomplexed antagomirs in orthotopic glioma.
Assuntos
Neoplasias Encefálicas/genética , Glioblastoma/genética , MicroRNAs/biossíntese , Oligonucleotídeos/administração & dosagem , Animais , Apoptose/efeitos dos fármacos , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/terapia , Proliferação de Células/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica , Genoma Humano , Glioblastoma/patologia , Glioblastoma/terapia , Humanos , Camundongos , MicroRNAs/antagonistas & inibidores , Neovascularização Patológica/genética , Neovascularização Patológica/patologia , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Alzheimer's disease (AD) is a multifactorial and fatal neurodegenerative disorder for which the mechanisms leading to profound neuronal loss are incompletely recognized. MicroRNAs (miRNAs) are recently discovered small regulatory RNA molecules that repress gene expression and are increasingly acknowledged as prime regulators involved in human brain pathologies. Here we identified two homologous miRNAs, miR-132 and miR-212, downregulated in temporal cortical areas and CA1 hippocampal neurons of human AD brains. Sequence-specific inhibition of miR-132 and miR-212 induces apoptosis in cultured primary neurons, whereas their overexpression is neuroprotective against oxidative stress. Using primary neurons and PC12 cells, we demonstrate that miR-132/212 controls cell survival by direct regulation of PTEN, FOXO3a and P300, which are all key elements of AKT signaling pathway. Silencing of these three target genes by RNAi abrogates apoptosis caused by the miR-132/212 inhibition. We further demonstrate that mRNA and protein levels of PTEN, FOXO3a, P300 and most of the direct pro-apoptotic transcriptional targets of FOXO3a are significantly elevated in human AD brains. These results indicate that the miR-132/miR-212/PTEN/FOXO3a signaling pathway contributes to AD neurodegeneration.
Assuntos
Doença de Alzheimer/genética , Apoptose/genética , Fatores de Transcrição Forkhead/genética , Regulação da Expressão Gênica , MicroRNAs/genética , Neurônios/metabolismo , Doença de Alzheimer/metabolismo , Animais , Apoptose/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Regulação para Baixo , Proteína Forkhead Box O3 , Fatores de Transcrição Forkhead/metabolismo , Humanos , Peróxido de Hidrogênio/farmacologia , Camundongos , MicroRNAs/metabolismo , Modelos Biológicos , PTEN Fosfo-Hidrolase/genética , PTEN Fosfo-Hidrolase/metabolismo , Interferência de RNA , Ratos , Transdução de Sinais , Fatores de Transcrição de p300-CBP/metabolismoRESUMO
BACKGROUND: Given multiple studies of brain microRNA (miRNA) in relation to Alzheimer's disease (AD) with few consistent results and the heterogeneity of this disease, the objective of this study was to explore their mechanism by evaluating their relation to different elements of Alzheimer's disease pathology, confounding factors and mRNA expression data from the same subjects in the same brain region. METHODS: We report analyses of expression profiling of miRNA (n = 700 subjects) and lincRNA (n = 540 subjects) from the dorsolateral prefrontal cortex of individuals participating in two longitudinal cohort studies of aging. RESULTS: We confirm the association of two well-established miRNA (miR-132, miR-129) with pathologic AD in our dataset and then further characterize this association in terms of its component neuritic ß-amyloid plaques and neurofibrillary tangle pathologies. Additionally, we identify one new miRNA (miR-99) and four lincRNA that are associated with these traits. Many other previously reported associations of microRNA with AD are associated with the confounders quantified in our longitudinal cohort. Finally, by performing analyses integrating both miRNA and RNA sequence data from the same individuals (525 samples), we characterize the impact of AD associated miRNA on human brain expression: we show that the effects of miR-132 and miR-129-5b converge on certain genes such as EP300 and find a role for miR200 and its target genes in AD using an integrated miRNA/mRNA analysis. CONCLUSIONS: Overall, miRNAs play a modest role in human AD, but we observe robust evidence that a small number of miRNAs are responsible for specific alterations in the cortical transcriptome that are associated with AD.