Differential expression of micro-RNA in tumor and non-tumor tissues of patients with colorectal cancer.

e13516 Background: The colorectal cancer (CRC) incidence is steadily increasing. Moreover, the problem of its early diagnosis remains unresolved due to the low specificity of known tumor markers, and the problem of creating new therapeutic approaches is due to the lack of a complete understanding of the mechanisms of regulation of gene expression in this oncopathology. The study of micro-RNAs (short non-coding RNAs that regulate gene expression) can be the solution to both problems. The aim of the study was to analyze micro-RNA differential expression in the tumor and non-tumor tissues of CRC patients. Methods: 5 patients with CRC (colon adenocarcinoma, G2) were selected for the multiple parallel micro-RNA sequencing. The mirVana miRNA Isolation Kit protocol was used to isolate small RNA fractions. The miRNA library was prepared using the TruSeq Small RNASample Preparation Kit. Sequencing of the nucleotide sequences of cDNA libraries was performed using a MiSeq (Illumina, USA). The copy numbers of micro-RNA were determined by comparing the nucleotide sequence of the sequenced molecules in each sample with the known nucleotide sequences of micro-RNA presented in the databases. When analyzing the differential expression of micro-RNA, the DESeq2 method implemented in R medium was used. Results: Six differentially expressed micro-RNAs were detected (p < 0.05): 2 that decrease expression (hsa-miR-143-3p,hsa-miR-26a-5p) and 4 increase expression in the tumor relative to non-tumor (hsa-miR-25-3p, hsa-miR-92a-3p, hsa-miR-21-5p, hsa-let-7i-5p). The highest level of expression in both tumor and non-tumor tissue was observed for hsa-miR-143-3p, the lowest one for hsa-let-7i-5p. Moreover, the largest difference in micro-RNA expression in tumor tissue relative to non-tumor was shown for hsa-miR-92a-3p (4.5 times, p = 0.02), the smallest for hsa-miR-143-3p (2.4 times, p = 0.04). For miRNAs that differentially changed their expression, a search was made for target genes using the miRWalk 3.0 database. 14573 target genes were found, of which 3346 were for hypo-expressed micro-RNAs and 11228 for hyper-expressed micro-RNAs. Conclusions: Sequencing revealed 6 differentially expressed micro-RNAs (hsa-miR-143-3p, hsa-miR-26a-5p, hsa-miR-25-3p, hsa-miR-92a-3p, hsa-miR-21-5p, hsa-let-7i-5p) in the tumor tissue is relatively non-tumor tissues of the colon. The data obtained expand the understanding of the mechanisms of gene regulation in the context of this oncopathology and may possibly become the basis for highly specific tumor markers panel.