Identification of a miRNA panel as a promising biomarker for diagnosis of glioblastoma patients using next-generation RNA sequencing
Applying Next Generation Sequencing technique we compared the miRNA expression pattern of tumor tissue sample of 6 GPs and peritumoral region of 6 lower grade (I-II) Glioma patients, serving as control group. To determine the difference on miRNA expresion level between GBM and control cases, we performed cluster analysis on the NGS dataset of 6 replicates for each of the two goups of samples with iDEP 96 software. In order to characterize the extent of up- or downregulation, log2FC values were calculated using the iDEP.96 web tool applying the DESeq2 algorithm. On the base of that 117 known miRNAs were identified to be differentially expressed using a threshold of false discovery rate (FDR) <0.05 and fold-change> 2 during the analysis. Among them, 35 miRNAs were upregulated (log2FC > 2) and 82 miRNAs were downregulated (log2FC < -2) with biological revelance in tissue samples comparing with the control samples. To validate our results obtained by NGS, five upregulated miRNAs: hsa-miR-196a-5p, hsa-miR-21-3p, hsa-miR-92b-5p, hsa-miR-10b-3p, hsa-miR-503-5p and three downregulated miRNAs: hsa-mir-383-5p, hsa-mir-490-3p, hsa-mir-1224-3p were chosen for RT-qPCR analysis. As the result of that hsa-miR-196a-5p, hsa-miR-21-3p, and hsa-miR-10b-3p was significantly upregulated while hsa-mir-383-5p  and hsa-mir-490-3p was significantly downregulated, compared with those in the control samples. The other three miRNAs: hsa-miR-1224-3p, hsa-miR-92b-5p, hsa-miR-503-5p  did not show significant difference between the control group and GPs. Overall design: Tissue samples were gathered from peritumoral region of six individuals diagnosed with lower grade (Grade I-II.) glioma, serving as control group, and from six patients with GBM. All samples in both group were confirmed histopathologically. These intraoperative quick-frozen tissue samples were stored at -80°C until further processing. Total RNA was isolated from  the tissue samples of GBM and control group as well. Global transcriptomic profile was studied by RNA-sequencing applying the Illumina NextSeq500 platform including microRNA sequencing. In the case of all samples 3 replicates were included. In order to identify up-, or down-regulated microRNAs the GBM samples were compared to the  control samples.