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MicroRNA-26a promotes cholangiocarcinoma growth by activating ?-catenin.

ABSTRACT: MicroRNAs (miRNAs) have been implicated in the development and progression of human cancers. We investigated the roles and mechanisms of miR-26a in human cholangiocarcinoma.We used in situ hybridization and quantitative reverse transcriptase polymerase chain reaction to measure expression of miR-26a in human cholangiocarcinoma tissues and cell lines (eg, CCLP1, SG231, HuCCT1, TFK1). Human cholangiocarcinoma cell lines were transduced with lentiviruses that expressed miR-26a1 or a scrambled sequence (control); proliferation and colony formation were analyzed. We analyzed growth of human cholangiocarcinoma cells that overexpress miR-26a or its inhibitor in severe combined immune-deficient mice. Immunoblot, immunoprecipitation, DNA pull-down, immunofluorescence, and luciferase reporter assays were used to measure expression and activity of glycogen synthase kinase (GSK)-3?, ?-catenin, and related signaling molecules.Human cholangiocarcinoma tissues and cell lines had increased levels of miR-26a compared with the noncancerous biliary epithelial cells. Overexpression of miR-26a increased proliferation of cholangiocarcinoma cells and colony formation in vitro, whereas miR-26 depletion reduced these parameters. In severe combined immune-deficient mice, overexpression of miR-26a by cholangiocarcinoma cells increased tumor growth and overexpression of the miR-26a inhibitor reduced it. GSK-3? messenger RNA was identified as a direct target of miR-26a by computational analysis and experimental assays. miR-26a-mediated reduction of GSK-3? resulted in activation of ?-catenin and induction of several downstream genes including c-Myc, cyclinD1, and peroxisome proliferator-activated receptor ?. Depletion of ?-catenin partially prevented miR-26a-induced tumor cell proliferation and colony formation.miR-26a promotes cholangiocarcinoma growth by inhibition of GSK-3? and subsequent activation of ?-catenin. These signaling molecules might be targets for prevention or treatment of cholangiocarcinoma.

SUBMITTER: Zhang J

PROVIDER: S-EPMC3668336 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

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MicroRNA-26a promotes cholangiocarcinoma growth by activating β-catenin.

Zhang Jinqiang J Han Chang C Wu Tong T

Gastroenterology 20120403 1

<h4>Background & aims</h4>MicroRNAs (miRNAs) have been implicated in the development and progression of human cancers. We investigated the roles and mechanisms of miR-26a in human cholangiocarcinoma.<h4>Methods</h4>We used in situ hybridization and quantitative reverse transcriptase polymerase chain reaction to measure expression of miR-26a in human cholangiocarcinoma tissues and cell lines (eg, CCLP1, SG231, HuCCT1, TFK1). Human cholangiocarcinoma cell lines were transduced with lentiviruses th ...[more]

PMID: 22484120

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Project description:Triggering Receptor Expressed on Myeloid cells 2 (TREM2), which is expressed on myeloid cells including microglia in the CNS, has recently been identified as a risk factor for Alzheimer's disease (AD). TREM2 transmits intracellular signals through its transmembrane binding partner DNAX-activating protein 12 (DAP12). Homozygous mutations inactivating TREM2 or DAP12 lead to Nasu-Hakola disease; however, how AD risk-conferring variants increase AD risk is not clear. To elucidate the signaling pathways underlying reduced TREM2 expression or loss of function in microglia, we respectively knocked down and knocked out the expression of TREM2 in in vitro and in vivo models. We found that TREM2 deficiency reduced the viability and proliferation of primary microglia, reduced microgliosis in Trem2-/- mouse brains, induced cell cycle arrest at the G1/S checkpoint, and decreased the stability of β-catenin, a key component of the canonical Wnt signaling pathway responsible for maintaining many biological processes, including cell survival. TREM2 stabilized β-catenin by inhibiting its degradation via the Akt/GSK3β signaling pathway. More importantly, treatment with Wnt3a, LiCl, or TDZD-8, which activates the β-catenin-mediated Wnt signaling pathway, rescued microglia survival and microgliosis in Trem2-/- microglia and/or in Trem2-/- mouse brain. Together, our studies demonstrate a critical role of TREM2-mediated Wnt/β-catenin pathway in microglial viability and suggest that modulating this pathway therapeutically may help to combat the impaired microglial survival and microgliosis associated with AD.SIGNIFICANCE STATEMENT Mutations in the TREM2 (Triggering Receptor Expressed on Myeloid cells 2) gene are associated with increased risk for Alzheimer's disease (AD) with effective sizes comparable to that of the apolipoprotein E (APOE) ε4 allele, making it imperative to understand the molecular pathway(s) underlying TREM2 function in microglia. Our findings shed new light on the relationship between TREM2/DNAX-activating protein 12 (DAP12) signaling and Wnt/β-catenin signaling and provide clues as to how reduced TREM2 function might impair microglial survival in AD pathogenesis. We demonstrate that TREM2 promotes microglial survival by activating the Wnt/β-catenin signaling pathway and that it is possible to restore Wnt/β-catenin signaling when TREM2 activity is disrupted or reduced. Therefore, we demonstrate the potential for manipulating the TREM2/β-catenin signaling pathway for the treatment of AD.

Dataset Information

MicroRNA-26a promotes cholangiocarcinoma growth by activating ?-catenin.

Publications

MicroRNA-26a promotes cholangiocarcinoma growth by activating β-catenin.

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