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RNA profiling in metastatic colorectal cancer patients treated first-line with oxaliplatin

ABSTRACT: Oxaliplatin (oxPt) resistance in colorectal cancers (CRC) is a major medical problem, and predictive markers are urgently needed. Recently, miR-625-3p was reported as a promising predictive marker. Here, we have used in vitro models to show that miR-625-3p functionally induces oxPt resistance in CRC cells, and have identified signalling networks affected by miR-625-3p. The p38 MAPK activator MAP2K6 was shown to be a direct target of miR-625-3p, and, accordingly, was downregulated in patients not responding to oxPt therapy. miR-625-3p resistance could be reversed in CRC cells by anti-miR-625-3p treatment and by ectopic expression of a miR-625-3p insensitive MAP2K6 variant. In addition, by reducing p38 MAPK signalling using either siRNA technology, chemical inhibitors to p38 or by ectopic expression of dominant negative MAP2K6 protein we induced resistance to oxPt. Transcriptome, proteome and phosphoproteome profiles revealed inactivation of MAP2K6-p38 signalling as one likely mechanism a possible driving force behind of oxPt resistance. Our study shows that miR-625-3p induces oxPt resistance by abrogating MAP2K6-p38 regulated apoptosis and cell cycle control networks, and corroborates the predictive power of miR-625-3p

ORGANISM(S): Homo sapiens

PROVIDER: GSE83129 | GEO | 2016/06/09

SECONDARY ACCESSION(S): PRJNA324835

REPOSITORIES: GEO

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Project description:Background: T-cell intracellular antigen (TIA) proteins function as regulators of cell homeostasis. These proteins control gene expression globally at multiple levels in response to dynamic regulatory changes and environmental stresses. Herein we identified a micro(mi)RNA signature associated to transiently TIA-depleted HeLa cells and analyzed the potential role of miRNAs combining genome-wide analysis data on mRNA and miRNA profiles. Results: Using high-throughput miRNA expression profiling, transient depletion of TIA-proteins in HeLa cells was observed to promote significant and reproducible changes (>2-fold, FDR<0.0001) affecting to a pool of up-regulated miRNAs (miR-30b*, miR125a-3p, miR-193a-5p, miR-197_MM2, miR-203, miR-210, miR-371-5p, miR-373*, miR-483-5p, miR-492, miR-498, miR-503, miR-572, miR-586, miR-612, miR-615, miR-623, miR-625, miR-629, miR-638, miR-658, miR-663, miR-671, miR-769-3p and miR-744). Differential expression analysis of some miRNAs was validated by reverse transcription and real time PCR. By target prediction and combined analysis of the genome-wide expression profiles of the mRNAs and miRNAs identified in TIA-depleted HeLa cells, we detected concomitant connections between up-regulated miRNAs and putative and experimental targeted mRNAs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes database analyses suggest that targeted mRNAs are related with biological processes associated to the regulation of DNA-dependent transcription, signal transduction and multicellular organismal development as well as with the enrichment of pathways in cancer, focal adhesion, regulation of actin cytoskeleton and MAPK and Wnt signalling pathways, respectively. Conclusion: All this considered, these observations suggest that specific miRNAs could act as potential mediators of the epigenetic switch linking transcriptomic dynamics and cell phenotypes mediated by TIA proteins. The analysis includes two cell types. Three biological replicates were performed per cell type and they were compared by using three dual-channel microarray hybridizations.