05). BBR increased protein levels of p53 and FOXO3a through p38 MAPK pathway It has reported that p53 cooperated with BBR-induced growth inhibition and apoptosis of NSCLC cells [6]. In this study, we showed that BBR increased FOXO3a, a transcription factor with known tumor suppressor activity [11], protein expression in a dose-dependent manner (Figure 4A). Similar results were obtained with PC9 cells (not shown). Next, we used special inhibitors of p38 MAPK and ERK1/2 to pre-treated A549 cells to examine the role of these kinases in mediating the effect of BBR on induction of p53 and FOXO3a. As shown in Figure 4B, we found that

the inhibitor of p38 MAPK (SB203580) abrogated BBR-induced p53 and FOXO3a protein expression, while the inhibitors of ERK1/2

(PD98059) had no effect (Figure 4D). Similar results were observed using CH5424802 mouse p38 MAPK siRNAs; intriguingly, we found that silencing of p38α (Figure 4C), but not p38β isoforms (not shown), abrogated the effect of BBR on p53 or FOXO3a protein expression. This result suggested that activation of p38α isoform was involved in the BBR-induced p53 and FOXO3a protein BIRB 796 expression; and that activation of ERK1/2 played no role in this process. Figure 4 Berberine increased p53 and FOXO3a protein expression through p38α MAPK pathway. A, A549 cells were exposed to increased concentration of BBR for 24 h. Afterwards, the expression of FOXO3a and p53 protein were detected by Western blot. B-C, A549 cells were treated with SB203580 (10 μM) (B), or p38α, β siRNAs (70 nM each) (C) for 2 h or 30 h before CUDC-907 manufacturer exposure of the cells to BBR (25 μM) for an additional 24 h. Afterwards, the expression of p38 α or β isoforms, p53 and FOXO3a protein was detected by Western blot. D, A549 cells were treated with PD98059 (20 μM) for 2 h and 30 before exposure of the cells to BBR (25 μM) for an additional 24 h. Afterwards, the expression of p53 and FOXO3a protein was detected by Western blot. The bar graphs

represent the mean ± SD of p53/GAPDH and FOXO3a/GAPDH of three independent experiments. E-F, A549 cells were treated with SB203580 (10 μM) Nitroxoline for 2 h before exposure of the cells to BBR (25 μM) for an additional 24 h. Afterwards, the cells were collected and processed for analysis of cell cycle distribution by Flow cytometry after propidium iodide (PI) staining (E). And the percentages of the cell population in each phase (G0/G1, S and G2/M) of cell cycle were assessed by Multicycle AV DNA Analysis Software. Data are expressed as a percentage of total cells. Values are given as the mean ± SD of relative percentage of cell cycle phases from 3 independent experiments performed in triplicate. In separated experiment, the cell viability was determined using the MTT assay (F). *indicates significant difference as compared to the untreated control group (P < 0.05). **Indicates significant difference from BBR treated alone (P < 0.05). Previously, we showed that BBR induced cell cycle arrest in G0/G1 phase.