BioProject

miRNA expression profiling was performed on MM.1S MM cells cultured 8 hours in control media or 50nM RGB-286638, with or without BMSCs. More...

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. Overall design: 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 2−ΔΔCt 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. Less...