Fig. 8

Bmi-1 regulates NF-kB - miR-21/miR-34a via activating AKT. a Bmi-1 overexpression downregulates the expression of PTEN and increases the expression of phosphalated AKT (pAKT) in SGC7901 cells (left panel), and Bmi-1 knockdown upregulates the expression of PTEN and decreases the expression of pAKT in MKN45 cells (right panel). The expression of Bmi-1, PTEN, pAKT, and total AKT (tAKT) was analyzed by Western blot in gastric cancer cells. b Bmi-1 overexpression promotes the binding of p65 to the PTEN promoter region in SGC7901 cells. The binding of Bmi-1 to PTEN promoter was detected by ChIP in SGC7901 cells. The p16 promoter was used as positive control and GAPDH as negative control. c AKT inhibitor MK-2206 treatment reduces the expression of phosphalated p65 (pp65) induced by Bmi-1 overexpression (left panel), and activated AKT can increase the expression of pp65 inhibited by Bmi-1 knock down (right panel). The effect of Bmi-1 and AKT on pp65 and total p65 expression was tested by Western blot. d AKT inhibitor MK-2206 treatment suppresses NF-kB transcriptional activity induced by Bmi-1 overexpression (left panel), and activated AKT promotes NF-kB transcriptional activity inhibited by Bmi-1 knock down (right panel). Transcriptional activity of NF-kB in gastric cancer cells was tested by luciferase reporter activity assays. e AKT inhibitor MK-2206 treatment inhibits the expression of miR-21 and miR-34a induced by Bmi-1 overexpression (left panel), and activated AKT increases the expression of miR-21 and miR-34a inhibited by Bmi-1 knock down (right panel). Fold change of miR-21 and miR-34a in gastric cancer cells was analyzed by QRT-PCR. f Schematic representation of the molecular mechanisms and regulation pathways in Bmi-1 regulating gastric cancer stem cell-like properties. Error bars in all panels represent the mean ± SD (*P < 0.05, **P < 0.01)