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MicroRNA profiles of meningiomas

ABSTRACT: Meningiomas, one of the most common human brain tumors, are derived from arachnoidal cells associated with brain meninges, usually benign and frequently associated with neurofibromatosis type 2. Here we define a human meningioma-typical miRNA profile and characterize effects of one down-regulated miRNA, miR-200a, on tumor growth. Elevated levels of miR-200a inhibited meningioma cell growth in culture and in a tumor model in vivo. Up-regulation of miR-200a decreased expression of transcription factors, ZEB1 and SIP1, with consequently increased expression of E-cadherin, an adhesion protein associated with cell differentiation. Down-regulation of miR-200a in meningiomas and arachnoidal cells resulted in increased expression of β -catenin and cyclin D1 involved in cell proliferation. miR-200a was found to directly target β -catenin mRNA, thereby inhibiting its translation and blocking β -catenin-Wnt signaling, frequently involved in cancer. A direct correlation was found between down-regulation of miR-200a and up-regulation of β-catenin in human meningioma samples. Thus, miR-200a appears to act as a multi-functional tumor suppressor miRNA in meningiomas through effects on the E-cadherin and β -catenin-Wnt signaling pathways. This reveals a previously unrecognized signaling cascade involved in meningioma tumor development and highlights a novel molecular interaction between miR-200a and Wnt signaling, thereby providing insights into novel therapies for meningiomas.

ORGANISM(S): Mus musculus Rattus norvegicus Homo sapiens

PROVIDER: GSE17792 | GEO | 2009/08/25

SECONDARY ACCESSION(S): PRJNA117869

REPOSITORIES: GEO

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Project description:Although mutations in Kras are present in 21% of lung tumors, there is a high level of heterogeneity in phenotype and outcomes amongst lung cancer patients suggesting the importance of other pathways. Wnt/β-catenin signaling is a known oncogenic pathway that plays a well defined role in colon and skin cancer but its role in lung cancer remains unclear. We show that activation of Wnt/β-catenin in the bronchiolar epithelium of the adult lung does not promote tumor development by itself. However, activation of Wnt/β- catenin signaling leads to a dramatic increase in tumor formation both in overall tumor number and size compared to KrasG12D alone. We show that activation of Wnt/β- catenin signaling significantly alters the KrasG12D tumor phenotype resulting in a phenotypic switch from bronchiolar epithelium to the highly proliferative distal progenitors found in the embryonic lung. This is associated with a decrease in E- cadherin expression at the cell surface which may increase metastasis in Wnt/β-catenin signaling positive tumors. Together, these data suggest that activation of Wnt/β-catenin signaling in combination with other oncogenic pathways in lung epithelium may lead to a more aggressive phenotype due to the imposition of an embryonic distal progenitor phenotype accompanied by decreased E-cadherin expression. We performed microarray analysis of control murine lung, CC10-cre:KrasG12D, and CC10-cre:Ctnnb1ex3flox:LSL-KrasG12D double mutant micro-dissected murine lung tumors to determine their transcriptional phenotype. Lungs of five-month-old mice were PBS inflated and all the tumors in each lobe were dissected. The total number of tumors obtained from three out of the 5 pulmonar lobes of each animal was called a sample the other two lobes were saved in case there were problems and the array needed to be repeated. Trizol was used to isolate RNA for microarray analysis. Samples & Genotypes: control murine lung n=2 animals, CC10-cre:KrasG12D n=2 animals, and CC10-cre:Ctnnb1ex3flox:LSL-KrasG12D n=2 animals.

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MicroRNA profiles of meningiomas

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