Knockdown of miR-25 increases the sensitivity of liver cancer stem cells to TRAIL-induced apoptosis via PTEN/PI3K/Akt/Bad signaling pathway

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is considered as a promising anticancer agent, it induced apoptosis in cancer cells selectively without damaging the normal tissue cells. However, the resistance of cancer cells to TRAIL limits its application. Since the cancer stem cells (CSCs) are believed to be responsible for the treatment failure in multiple cancers including hepatocellular carcinoma (HCC), the aim of this study was to investigate the strategies to increase the sensitivity of liver cancer stem cells (LCSCs) to TRAIL. In the present study, we observed significant upregulation of miR-25 in LCSCs compared with the non-CSCs. Furthermore, we found that knockdown of miR-25 by its antisense oligonucleotide (anti-miR-25) significantly increased the sensitivity of LCSCs to TRAIL-induced apoptosis. The gene of phosphatase and tensin homologue (PTEN), which is a natural inhibitor of PI3K, was found to be directly regulated by miR-25 in HepG2-CSCs. We demonstrated that knockdown of miR-25 increased the expression of PTEN. Mechanistically, inhibition of Bad phosphorylation, which is regulated by the PTEN/PI3K/AKT pathway, is essential for the functional roles of anti-miR-25 in HepG2-CSCs. In conclusion, our findings indicate that overexpression of miR-25 is associated with the low-sensitivity to TRAIL in LCSCs. Knockdown of miR-25 may represent a potential strategy for increasing the efficacy of TRAIL by targeting the PTEN/PI3K/Akt/Bad signaling pathway.