MIR155 and ERK regulate FOXO3A expression in cHL. (A-C) MIR155 contributes to FOXO3A repression. MIR155 was inhibited in the cell line L428 with a miScript miRNA inhibitor (anti-MIR155; Qiagen) compared with a negative control (NC). (A) The efficiency of MIR155 inhibition was confirmed by RT-qPCR 24 hours after transfection. (B) After 72 hours, the effect of MIR155 inhibition on FOXO3A protein levels was evaluated using immunoblot analysis. A representative of 8 experiments is shown. (C) Immunoblots from panel B were quantified using ImageJ 64 and significance was calculated by a 2-sided t test using GraphPad Prism software. (D) MIR155 inhibition leads to cell-cycle arrest in L428 72 hours after transfection. Data of 3 independent experiments are shown as mean ± SD. Significances were calculated by a 2-sided t test using GraphPad Prism software. **P < .01. (E-F) ERK mitigates FOXO3A expression. KM-H2 and L428 were treated with the ERK inhibitor U0126 or vehicle. (E) After 24 hours, cells were lysed and total FOXO3A levels were assessed with immunoblot. A representative of 3 experiments is shown. (F) Dose-dependent activation of FOXO3A by the ERK inhibitor U0126. ImageJ 64 was used to quantify immunoblots obtained in panel E. Pearson correlation coefficient “r” and the P value were calculated using GraphPad Prism 6.