Unknown,Transcriptomics,Genomics,Proteomics

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Impact of Glucocorticoids and PI3K Inhibition on Gene Expression in Myeloma

ABSTRACT: We previously noted that combination glucocorticoids and PI3K inhibition induces synergistic cell death. To identify genes involved in myeloma cell death we examined mRNA expression in each individual treatment and in the combination. The glucocoriticoid resistant cells (MM.1RL) are used as a negative control. Gene expression is assessed using Illumina Human HT-12v4 bead chips For this experiment, the lab is using human multiple myeloma cell lines that were isolated from a patient. MM.1S cells display sensitivity to glucocorticoids. MM.1RL cells display resistance to glucocorticoid treatment due to spontaneous mutations that render the glucocorticoid receptor inoperable. In this experiment, there will be 4 conditions for the MM.1S cells, and 2 conditions for the MM.1RL cells. We will be treating the MM.1S cells with a glucocorticoid alone (Dexamethasone - 1 uM), a PI3K inhibitor alone (LY249002 - 25 uM), a combination of the two drugs, and a vehicle control. The MM.1RL cells will be treated with a PI3K inhibitor alone, and with a vehicle control. Since the PI3K inhibitor is diluted in DMSO, as a control an equal volume of DMSO will be added to all conditions not containing the PI3K inhibitor. Conditions within the MM.1S cell line will be compared with each other. Specifically, we hope to identify genes that are similarly affected by all three experimental conditions. The MM.1RL conditions will not be analyzed at this time. There will be 4 biological replicates of each condition.

ORGANISM(S): Homo sapiens

SUBMITTER: Nancy Krett

PROVIDER: E-GEOD-64704 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:miRNA expression profiling was performed on MM.1S MM cells cultured 8 hours in control media or 50nM RGB-286638, with or without BMSCs. The emerging role of miRNAs in the pathogenesis of multiple myeloma (MM) led us to hypothesize that the miRNA network might be among the inducible transcriptional alterations consequent to MM-bone marrow stromal cell (BMSC) interactions. Our data suggests that BMSC induced MM transcription led to aberrant miRNA expression. We therefore hypothesized that agents interfering with RNAPII transcription might inhibit aberrant miRNA expression in MM. To test this hypothesis we used RGB-286638, a novel protein kinase inhibitor, which works primarily via RNAPII inhibition followed by transcriptional arrest in MM cells. miRNA profiling of RGB-286638-exposed MM cells resulted in RNAPII arrest associated with reduced miRNA levels. RGB-286638 abrogated BMSCs-induced miRNAs, which correlated with growth arrest in MM cells. Analysis of RGB-286638-induced differentially-expressed miRNAs in MM cells, in the presence or absence of BMSCs, revealed RNAPII regulation of expression of BMSC-inducible miRNAs with established oncogenic functions in MM Our findings demonstrate the role of RNAPII in regulating miRNA network, suggesting a new rationale for using agents interfering with RNAPII transcription in the treatment of MM. TaqMan Low-Density Array (TLDA) using human miRNA version 2.0A and version 3.0B cards (Applied Biosystems) were applied to examine the global change of miRNA expression levels in MM.1S cells when co-cultured with BMSCs, with or without RGB-286638 treatment. A total of 756 mature miRNA updated in the Sanger miRBase v.15.0 were quantified according to the manufacturer's instructions as previously described. miRNAs with Ct values higher than 37 were excluded from the analysis. Normalization was carried out with the mean of RNU44 and RNU48. Relative quantification of miRNA expression was calculated with the 2M-bM-^HM-^RM-NM-^TM-NM-^TCt Ct method using the ddCt program (Shannon McCormack Advanced Molecular Diagnostics Laboratory Research Services). The data was presented as log10 of the relative quantity of each miRNA.

Project description:Conventional anti-cancer drug screening is typically performed in the absence of accessory cells (e.g. stromal cells) of the tumor microenvironment, which can profoundly alter anti-tumor drug activity. To address this major limitation, we have developed assays (e.g. the tumor cell-specific in vitro bioluminescence imaging (CS-BLI) assay) to selectively quantify tumor cell viability, in presence vs. absence of non-malignant stromal cells or drug treatment. These assays have allowed us to identify that neoplastic cells from diverse malignancies exhibit stroma-induced resistance to different anti-tumor agents. In this analysis, we evaluated the molecular changes triggered in myeloma cells by their in vitro interaction with stromal cells. The transcriptional profile of 3 human multiple myeloma (MM) cell lines (MM.1S, MM.1R, INA-6) co-cultured with stromal cells vs. when cultured alone was characterized by oligonucleotide microarray analysis, using the human U133 plus 2.0 Affymetrix GeneChip. Three human multiple myeloma (MM) cell lines (MM.1S, MM.1R, INA-6) stably expressing green fluorescent protein (GFP) were cultured in vitro for 24hrs either alone or in the presence of the human bone marrow stromal cell line HS-5. Fluorescence activated cell sorting was used to separate the GFP+ MM cells from GFP- stromal cells. The gene expression profiles of MM cells after their co-culture with stromal cells were compared with the profiles of MM cells cultured alone, according to previously described protocols for total RNA extraction and purification; cDNA synthesis; production of biotin-labeled cRNA; hybridization of cRNA with U133plus2.0 Affymetrix gene chips; and scanning of image output files. Scanned image output files were analyzed using DNA-Chip Analyzer (dChip) (www.dchip.org), including conversion to DCP files, normalization and modeling, and averaging of duplicate chips according to standard parameters recommended by the software. For each cell line, the gene expression profile in the presence of stomal cells was compared to the profile of the same cell line cultured in the absence of stromal cells. Technical replicates for each condition were analyzed (total of 12 gene expression profiles).

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Impact of Glucocorticoids and PI3K Inhibition on Gene Expression in Myeloma

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