Abstract: Background and purpose: Inflammatory bowel diseases (IBD) are a group of chronic intestinal diseases, including ulcerative colitis (UC) and Crohn’s disease (CD). This study identified differentially expressed miRNAs in UC, CD and colitis-associated colorectal cancers (CAC) to explore their potential as novel molecular biomarkers. Methods: Tissue samples were taken from 13 UC patients, 3 CD patients, 12 CAC patients, and 8 ageand gender-matched healthy controls. The miRNA expressions were detected by real-time fluorescent quantitative polymerase chain reaction (RTFQ-PCR) assay. Known targets of deregulated miRNAs were utilized using miRWalk 2.0 database, and subsequent bioinformatics analysis of these target genes was performed by DAVID software (GO-analysis, KEGG-analysis and BIOCARTA-analysis). Results: The data showed that miR-146a, miR-27a, miR-29a, miR-20a and miR-21 were upregulated in UC, CD and CAC tissues compared with normal control. Moreover, the target genes of these miRNAs were enriched in several key signal transduction pathways including cancer-related pathway and immunity-associated pathway. Conclusion: miR-146a, miR-27a, miR-29a, miR-20a and miR-21 may play important roles in the switching from IBD to CAC.

Key words: miRNA, Ulcerative colitis, Crohn’s disease, Colitis-associated colorectal cancers, Real-time fluorescent quantitative polymerase chain reaction, GO-analysis, KEGG-analysis, BIOCARTA-analysis