Abstract 1959: Global microRNA expression analysis of Sox-2 positive and negative glioblastoma cells

Introduction: Glioblastoma multiforme (GBM) is the most frequent intracranial malignity of astrocytic origin in adults. This tumor is characterized by infaust prognosis, which is primarily caused by resistance to the therapy and early relapses relate to the presence of glioblastoma stem cells (GSCs). These cells form neurospheres in vitro and express markers of stemness such as Sox-2, Oct-4, and nestin. Targeting of GSCs could be a novel promising therapeutic approach leading to the overcome of therapy resistance and better prognosis of GBM patients. One of the approaches how to successfully regulate GSC is a targeted regulation of microRNAs (miRNAs). These small non-coding RNA molecules post-transcriptionally regulate an expression of more than 2/3 of all human genes that are also involved in stem cell associated signaling pathways. Moreover, deregulated expression of some miRNAs has been observed in many cancers including GBM. Cell lines and Methods: We have prepared eleven Sox-2 positive and negative paired primary GBM cell lines, which have been cultured under DMEM/F12 medium supplemented with bFGF, EGF, and B12 supplement and DMEM medium supplemented with 10% FBS, respectively. The global miRNA expression analysis was performed using GeneChip miRNA 4.0 Array (Affymetrix). Targeted regulation of miRNA levels have been carried out by the transient transfection of specific anti-miRNAs or miRNA mimics in GSC cell lines NCH 601 acquired from Interdisciplinary Center For Neurosciences (Heidelberg, Germany). The sphere formation assay was analyzed using IncuCyte ZOOM instrument (Essen BioScience). Sox-2 and nestin expressions were analyzed on both protein and transcriptional levels using combination of PAGE with Western blotting and real-time PCR, respectively. Results: Analysis of Sox-2 positive and negative paired GBM cell lines revealed 29 differentially expressed miRNAs, from which miR-93-3p, miR-95-5p, miR-106b-5p, miR-22-3p, and miR-3195 showed high significance (adjust. P value < 0.05) and association with both Sox-2 (Spearman R; p < 0.002) and nestin (Spearman R; p < 0.02) expressions. MiR-22-3p and miR-3195 showed lower expression whereas other miRNAs higher expression in Sox-2 positive GBM cells. The in vitro analyses also suggest that miR-22-3p and miR-106b-5p affect the sphere formation potential and Sox-2 expression in GSC cells. Conclusion: Taken together, our data suggest that miR-22-3p and miR-106b-5p are probably involved in GSC biology and,