Up-regulation of miR-125b reverses epithelial-mesenchymal transition in paclitaxel-resistant lung cancer cells.

Recent studies have demonstrated that acquisition of epithelial-mesenchymal transition (EMT) is associated with drug resistance in lung cancer cells. However, the underlying mechanisms are not fully elucidated. Emerging evidence suggests that microRNAs play a crucial role in controlling EMT. The aim of this study was to explore the potential role of miR-125b in governing EMT in paclitaxel-resistant (PR) lung cancer cells. To achieve this goal, we explored the role of miR-125b in regulation of EMT in stable PR lung cancer cells, namely A549-PR and H460-PR. We found that miR-125b was significantly downregulated in A549-PR and H460-PR cells. Notably, ectopic expression of miR-125b led to the reversal of EMT phenotype. Moreover, we found that miR-125b governed PR-induced EMT partly due to down-regulation of its target Sema4C. More importantly, overexpression of miR-125b or depletion of Sema4C sensitized PR cells to paclitaxel. Furthermore, stable overexpression miR-125b in A549-PR cells inhibited tumor xenograft growth in immunodeficient mice. Our study implied that up-regulation of miR-125b could be a novel approach to reverse chemotherapy resistance in lung cancers.