Figure 4. MicroRNA-107 (miR-107) induced reactive oxygen species (ROS) accumulation and cell death by targeting cofilin-1 in hepatocellular carcinoma (HCC) cells. (A) MiR-107 target sequence on cofilin-1 (CFL1) 3' UTR (untranslated region). (B) Luciferase activity assays of luciferase vectors with cofilin-1 3' UTR were performed following transfection with miR-107 or negative control for 24 h. **P < 0.01 vs. HDACi-R (histone deacetylase inhibitor-resistant) cells cofilin-1 3' UTR group. (C) MiR-107 induced reactive oxygen species (ROS) accumulation, as detected by MitoSOX staining. (D) H2O2-induced HA22T cell death was higher than HDACi-R cells. Transfection with si-cofilin-1 (si-CFL-1) and miR-107 mimic decreased cofilin-1 (CFL-1) expression and enhanced H2O2-induced cleavage caspase-3 expression, as detected by western blotting assay. (E) Quantification of Figure 4D. Fold change of cleavage caspase-3 after normalization using actin. *P < 0.05, ***P < 0.001 vs. HA22T control. #P < 0.05, ###P < 0.001 vs. HDACi-R control.