Upregulation of DKK3 by miR-483-3p plays an important role in the chemoprevention of colorectal cancer mediated by black raspberry anthocyanins.

Abstract

It is reported that black raspberry (BRB) anthocyanins could act as a potential chemopreventive agent for colorectal cancer (CRC). However, the underlying mechanism by which BRB anthocyanins inhibits the carcinogenesis of CRC cells has not been elucidated. The abnormal expression of microRNAs (miRNAs) that target important tumor suppressor genes is usually associated with CRC development. In this study, we explored whether BRB anthocyanins could affect the expression of certain miRNAs in an azoxymethane (AOM)/dextran sulphate sodium (DSS)-induced CRC mouse model and human CRC cell lines. miRNA microarray analysis was used to determine the differences in miRNA expression between AOM/DSS-induced mice fed with a diet supplemented without or with BRB anthocyanins. The expression of one particular miRNA, miR-483-3p, was found to decrease dramatically in AOM/DSS-induced mice that were fed with a diet supplemented with BRB anthocyanins. Subsequent quantitative real-time polymerase chain reaction and Western blot analyses showed that the reduced expression of miR-483-3p was accompanied by an increased expression of Dickkopf 3 (DKK3), a potential target of miR-483-3p as predicted by bioinformatic analysis. The protein and messenger RNA levels of DKK3 were significantly upregulated when the miR-483-3p level was reduced by a miR-483-3p-specific inhibitor, suggesting that DKK3 might be the target gene of miR-483-3p. In addition, the downstream factors of the DKK3 signaling pathway, which included Wnt/β-catenin, also played a role in the miR-483-3p-mediated anticancer effect of BRB anthocyanins. Thus, miR-483-3p might be a potential target in BRB anthocyanin-mediated prevention of CRC.