Unknown,Transcriptomics,Genomics,Proteomics

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MicroRNAs mediate rapamycin resistance in a myogenic tumor cell line

ABSTRACT: The mammalian target of rapamycin (mTOR) is a central regulator of cell proliferation. Inhibitors of mTOR are being evaluated as anti-tumor agents. Given the emerging role of microRNAs (miRNAs) in tumorgenesis we hypothesized that miRNAs could play important roles in the response of tumors to mTOR inhibitors. Rapamycin resistant myogenic cells developed by long-term rapamycin treatment showed extensive reprogramming of miRNAs expression, characterized by up-regulation of the mir-17~92 and related clusters and down-regulation of tumor-suppressor miRNAs. Antagonists of oncogenic miRNA families and mimics of tumor suppressor miRNAs (let-7) restored rapamycin sensitivity in resistant tumor cells. This study identified miRNAs as new downstream components of the mTOR-signaling pathway, which may determine the response of tumors to mTOR inhibitors. Total RNA was extracted from rapamycin sensitive (RS) cells (BC3H1, mouse brain tumor cell line with myogenic properties, ATCC) cultured in Dulbecco’s modified essential medium (DMEM) media supplemented with 20% fetal bovine serum (FBS), penicillin (100 U/ml) and streptomycin (100 mg/ml). Rapamycin resistant cells (RR1) were developed by culturing BC3H1 cells in the presence of 1 uM rapamycin for 6 months. Three samples in quadruplicate 1)RS cells treated with DMSO for 24 h(BC3H1, reference), 2) RS cells treated for 24 h with 100 nM rapamycin (BC3H1+R), 3) RR1 cells consantly treated with 1uM Rapamycion (RR1+R). For each experiment, 1 μM of total RNA was labeled with Hy3TM dye and a reference RNA pool (consisting of a mixture of equal amounts of total RNA from BC3H1, BC3H1+R and RR1+R cells) was labeled with Hy5TM dye using the miRCURYTM Labeling Kit. The samples were hybridized to Exiqon miRCURYTM LNA Arrays (V10.0).

ORGANISM(S): Mus musculus

SUBMITTER: Hana Totary-Jain

PROVIDER: E-GEOD-19916 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Reprogramming of the microRNA transcriptome mediates resistance to rapamycin.

Totary-Jain Hana H Sanoudou Despina D Ben-Dov Iddo Z IZ Dautriche Cula N CN Guarnieri Paolo P Marx Steven O SO Tuschl Thomas T Marks Andrew R AR

The Journal of biological chemistry 20130108 9

The mammalian target of rapamycin (mTOR) is a central regulator of cell proliferation that is often deregulated in cancer. Inhibitors of mTOR, including rapamycin and its analogues, are being evaluated as antitumor agents. For their promise to be fulfilled, it is of paramount importance to identify the mechanisms of resistance and develop novel therapies to overcome it. Given the emerging role of microRNAs (miRNAs) in tumorigenesis, we hypothesized that miRNAs could play important roles in the r ...[more]

PMID: 23300087

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Project description:Mammalian target of rapamycin (mTOR) is a serine/threonine kinase involved in multiple intracellular signaling pathways promoting tumor growth. mTOR is aberrantly activated in a significant portion of breast cancers and is a promising target for treatment. Rapamycin and its analogues are in clinical trials for breast cancer treatment. Patterns of gene expression (metagenes) may also be used to simulate a biologic process of effects of a drug treatment. In this study, we tested the hypothesis that the gene-expression signature regulated by rapamycin could predict disease outcome for patients with breast cancer. Results: Colony formation and sulforhodamine B (IC50 < 1nM) assays, and xenograft animals showed that MDA-MB-468 cells were sensitive to treatment with rapamycin. The comparison of in vitro and in vivo gene expression data identified a signature, termed rapamycin metagene index (RMI), of 31 genes upregulated by rapamycin treatment in vitro as well as in vivo (false discovery rate of 10%). In the Miller dataset, RMI was significantly associated with tumor size or lymph node status. High (>75) percentile) RMI was significantly associated with longer survival (P = 0.015). On multivariate analysis, RMI (P = 0.029), tumor size (P = 0.015) and lymph node status (P = 0.01) were prognostic. In van 't Veer study, RMI was not associated with the time to develop distant metastasis (P = 0.41). In Wang dataset, RMI predicted time to disease relapse (P = 0.09). Conclusions: Rapamycin-regulated gene expression signature predicts clinical outcome in breast cancer. This supports the central role of mTOR signaling in breast cancer biology and provides further impetus to pursue mTOR-targeted therapies for breast cancer treatment. Mol Cancer. 2009 Sep 24;8(1):75. Experiment Overall Design: Rapamycin treatment of MDA-MB-468 breast cancer cell line: Experiment Overall Design: MDA-MB-468 cell line was treated by DMSO (vehicle) and 100 nM rapamycin for 24 hours. We sought to identify differentially expressed genes. Experiment Overall Design: Rapamycin treatment of breast tumor xenografts: Experiment Overall Design: MDA-MB-468 cells were inoculated in the mammary fat pad of female nude mice. When resulting tumor volumes had reached 75-150 mm3, the mice were divided in four groups. Groups 1 and 2 received a single injection of DMSO (vehicle) or rapamycin (15 mg/kg) intraperitoneally and sacrificied 24 h later (1-day groups). Groups 3 and 4 received weekly injections of DMSO or rapamycin for 3 weeks and sacrificied 24 h after the last injection (22-day groups).

Project description:Mitochondrial oxidative function is tightly controlled to maintain energy homeostasis in response to nutrient and hormonal signals. An important cellular component in the energy sensing response is the target of rapamycin (TOR) kinase pathway; however whether and how mTOR controls mitochondrial oxidative activity is unknown. Here, we show that mTOR kinase activity stimulates mitochondrial gene expression and oxidative function. In skeletal muscle cells and TSC2-/- MEFs, the mTOR inhibitor rapamycin largely decreased gene expression of mitochondrial transcriptional regulators such as PGC-1alpha and the transcription factors ERRalpha and NRFs. As a consequence, mitochondrial gene expression and oxygen consumption were reduced upon mTOR inhibition. Using computational genomics, we identified the transcription factor YY1 as a common target of mTOR and PGC-1alpha that controls mitochondrial gene expression. Inhibition of mTOR resulted in a failure of YY1 to interact and be coactivated by PGC-1alpha. Notably, knock-down of YY1 in skeletal muscle cells caused a significant decrease in mRNAs of mitochondrial regulators and mitochondrial genes that resulted in a decrease in respiration. Moreover, YY1 was required for rapamycin-dependent repression of mitochondrial genes. Thus, we have identified a novel mechanism in which a nutrient sensor (mTOR) balances energy metabolism via transcriptional control of mitochondrial oxidative function. These results have important implications for our understanding of how these pathways might be altered in metabolic diseases and cancer. Experiment Overall Design: Using Affymetrix MOE430 v2 gene chips, biological triplicates of each condition were analyzed: vehicle-treated, rapamycin-treated, gfp-infected, and pgc-1alpha-infected resulting in a total of 12 samples. Experiment Overall Design: Data were analyzed by RMA (with default settings) in BioConductor 1.2 -- one batch for the Rapamycin vs. Vehicle, and another batch for the PGC vs GFP.

Dataset Information

MicroRNAs mediate rapamycin resistance in a myogenic tumor cell line

Publications

Reprogramming of the microRNA transcriptome mediates resistance to rapamycin.

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