Increased expression of microRNA in the inflamed colonic mucosa of patients with active ulcerative colitis

Background and Aims: MicroRNA (miRNA) are endogenous, approximately 22-nucleotide non-coding RNA that suppress gene expression at post-transcriptional levels by binding to the 3'-untranslated region of specific mRNA targets through base-pairing. It has been recently reported that miRNA have critical functions in key biological processes such as cell proliferation and cell death in various cancer cells. However, the relationship between intestinal inflammation and miRNA expression remains unclear. In the present study, we used microarray technology to identify miRNA induced in the colonic mucosa of patients with active ulcerative colitis (UC). Methods: Two colonic biopsy specimens from patients with active stage (> Matts grade 2) of UC under colonoscopy and two colonic biopsy specimens from healthy volunteers were obtained for gene expression profiles. Total RNA was extracted, and miRNA expression profiles were investigated using miRNA Microarray. Subsequently, to confirm the result of the Microarray investigation, we checked the expression of several selected miRNA using real-time polymerase chain reaction (PCR) in 12 colonic biopsy specimens from patients with active UC under colonoscopy and 12 specimens from the healthy volunteers. Results: In the microarray study, the expression of several miRNA was upregulated in the colonic mucosa of patients with active UC. Furthermore, two miRNA (miR-21, miR-155) were selected in the study using real-time PCR. Conclusion: Upregulated miRNA may be responsible for the development of intestinal inflammation in UC.