MicroRNA-206 is involved in the pathogenesis of ulcerative colitis via regulation of adenosine A3 receptor

Increasing evidence suggests that miRNAs are widely dysregulated in ulcerative colitis (UC), potentially affecting UC pathogenesis, diagnosis, and therapy. microRNA (miR) -206 has been reported to be upregulated in UC; however, its function and role in UC remain unknown. Here, we elucidate the function of miR-206 in the pathogenesis of UC. In patients with active-UC, miR-206 and adenosine A3 receptor (A3AR) levels were significantly upregulated and downregulated, respectively, and were inversely correlated. A3AR was expressed in the colon mucosa (particularly in colon epithelial-cell membranes). In HT-29 cells, miR-206 downregulated A3AR mRNA/protein expression by directly targeting the A3AR 3'-UTR; miR-206 overexpression and knockdown respectively increased and decreased TNF-alpha-induced nuclear NF-kappa B/p65, p-I kappa B-alpha, IKK alpha, p-IKK alpha and IL-8/IL-1 beta secretion. However, A3AR-siRNA reversed the miR-206 inhibitory effect. Furthermore, miR-206 increased dextran sodium sulphate-induced colitis severity (i.e., increased bodyweight loss, DAI score, colon shrinkage, and MPO activity), which was partially ameliorated by miR-206-antagomir treatment. miR-206-agomir treatment potently suppressed A3AR expression and increased NF-kappa B signalling and downstream cytokine (TNF-alpha/IL-8/IL-1 beta) expression in the mouse colon, in contrast to miR-206-antagomir administration. Taken together, our results demonstrated that miR-206 has a proinflammatory role in UC by downregulating A3AR expression and activating NF-kappa B signalling.