Ewing's sarcoma: an analysis of miRNA expression profiles and target genes in paraffin-embedded primary tumor tissue

The molecular mechanism responsible for Ewing Sarcoma (ES) remains largely unknown. This study compared global miRNA expression in biopsies from 20 ES patients, affected by primary untreated tumors, with miRNA expressed in normal human mesenchymal stromal cells (MSCs) by microarray analysis. A miRTarBase database was used to identify the predicted target genes for differentially-expressed miRNAs. The miRNAs microarray analysis revealed distinct patterns of miRNA expression between ES biopsies and normal MSCs. 58 of the 954 analyzed miRNAs were significantly differentially expressed in ES samples compared to MSCs. Moreover, the qRT-PCR analysis, carried out on three selected miRNAs, showed that miR-181b, miR-1915 and miR-1275 were significantly aberrantly-regulated, confirming the microarray results. Bio-database analysis identified BCL-2 as a bona fide target gene of the miR-21, miR-181a, miR-181b, miR-29a, miR-29b, miR-497, miR-195, miR-Let-7a, miR-34a. Using paraffin-embedded tissues from ES, this study has identified several potential target miRNAs and one gene that might be considered novel critical biomarkers for ES pathogenesis. Biopsies from 20 ES patients using paraffin-embedded tissues and normal human mesenchymal stromal cells as controls.