MiR-106b inhibitors sensitize TRAIL-induced apoptosis in hepatocellular carcinoma through increase of death receptor 4.

TNF-related apoptosis-inducing ligand (TRAIL), which is a member of the TNF superfamily, can induce tumor cell apoptosis. However, multiple types of tumor, including hepatocellular carcinoma, show tolerance to TRAIL. Previous studies have demonstrated that tumor cells usually change their expression profile of microRNA (miRNA) to obtain the ability of tolerance to drugs. However, whether such change of miRNA on TRAIL sensitivity is seen in hepatocellular carcinoma still needs to be explored. In this study, we observed overexpression of miR-106b in both HCC patients' tumor tissues and cell lines. Furthermore, we found that overexpression of miR-106b is associated with the sensitivity of TRAIL to HCC. Silencing of miR-106b with antisense oligonucleotide (anti-miR-106b) is proved to enhance the TRAIL-induced apoptosis and reduce the acquired drug resistance to TRAIL in HCC. Mechanically, we didn't observe the obvious change of pro-apoptotic proteins (Bax and Bid) and anti-apoptotic proteins (Bcl-2, Mcl-1 and Bcl-xl) after treatment of anti-miR-106b. However, we used the methods of bioinformatics, flow cytometry, cellular and molecular methods to prove that miR-106b directly targeted to death receptor 4 (DR4) 3'-UTR (3'-Untranslated Regions). MiR-106b inhibitors induced increase of DR4 expression and therefore enhancing TRAIL-mediated apoptosis in HCC. In summary, these results suggest the application of miR-106b inhibitors in HCC treatment. Combination with miR-106b inhibitors and TRAIL may be a novel clinical treatment method on HCC treatment in the future.