Fig. 1

Akt1 inhibition promoted breast cancer cell invasion through inducing β-catenin nuclear accumulation. (a) Western blot of Akt1, β-catenin total and nuclear protein expression in MCF-7, BT-474, MDA-MB-231 and SKBR3 cells after treated with two Akt1 siRNA. β-actin and Lamin B1 were used as an internal control respectively. Note that Akt1 siRNA could knockdown the protein expression of Akt1, but upregulate the expression of β-catenin total and nuclear protein in these four distinct breast cancer cells, n = 5 per group. (b) Immunohistochemical staining of β-catenin (Green) in MCF-7 and MDA-MB-231 cells after treated with two Akt1 siRNA. Cell nuclei were stained with Hoechst 33342 (Blue). Note that Akt1 siRNA could induce nuclear β-catenin accumulation in MCF-7 and MDA-MB-231 cells, n = 3 per group. (c) Akt1 siRNA enhanced the β-catenin-dependent transcriptional activity. The firefly luciferase activity of each sample was normalized to the Renilla luciferase activity. **p < 0.01, ***p < 0.001 compared with Control group, one-way ANOVA, n = 5 per group. (d) Expression of myr-Akt1 in MCF-7 and MDA-MB-231 cells reduced the expression of β-catenin total protein as well as its nuclear accumulation. (e) Expression of myr-Akt1 in MCF-7 and MDA-MB-231 cells reduced the β-catenin-dependent transcriptional activity. The firefly luciferase activity of each sample was normalized to the Renilla luciferase activity. ***p < 0.001 compared with Vector group, A two-tailed unpaired t-test, n = 5 per group. (f) Western blot analysis showing that the AXIN stabilizer XAV939 could reverse Akt1 siRNA induced β-catenin nuclear accumulation, n = 5 per group. (g-h) Transwell assay with Matrigel demonstrated that Akt1 knockdown could enhance the invasion ability of MCF-7 and MDA-MB-231 cells, while XAV-939 reversed Akt1 siRNA-induced breast cancer invasion. **p < 0.01, ***p < 0.001, one-way ANOVA, n = 5 per group