Figure 5

Beta-catenin is involved in the dual promotive function of DKK1 on tumor migration and invasion. A: Knockdown of DKK1 repressed the mRNA and protein level of β-catenin in Bel7402 cells. B: Silencing of DKK1 attenuated the β-catenin-dependent transcriptional activity. Tumor cells were transfected with firefly luciferase reporter plasmids containing either wild-type or mutant TCF binding sites (indicated as Wt or Mut on the X axis), and a Renilla luciferase expressing construct. The firefly luciferase activity of each sample was normalized to the Renilla luciferase activity. The normalized luciferase activity of shControl-transfectants in each experiment was set as relative luciferase activity 1. Therefore, no error bar is shown for shControl-transfectants. **, p < 0.01, compared with shControl-transfectants. C: Transient expression of β-catenin in Bel7402-shDKK1 cells was detected by RT-PCR analysis. Bel7402-shDKK1 cells transfected with pcDNA3 (lane 2) or pcDNA3-β-catenin (lane 3) were analyzed using RT-PCR. D: Restoration of β-catenin reversed the anti-invasion effect of shDKK1. E, F: Treatment with GSK3β inhibitor LiCl (5 mM) attenuated the anti-migration and anti-invasion effect of shDKK1. In (E), after scratching a wound and removing the floating cells, tumors cells without treatment (panel 1, 3) or incubated with 5 mM LiCl (panel 2, 4) were applied to the wound scratch assay for 24 h. In (F) tumors cells treated as in (E) were applied to transwell chamber coated with Matrigel and then incubated for 24 h. The data are represented as means ± SEM. *, p <0.05; **, p <0.01.