PIAS1-mediated <i>WNT5A</i> suppression is important for the maintenance of breast Tumor Initiating Cells (TICs).

<p>(<b>a</b>) Western blot analyses with whole cell extracts from MDA-MB231 cells containing control shRNA, PIAS1 shRNA1 or shRNA2 cultured in DMEM plus 10% FBS. (<b>b</b>) Western blot analyses with whole cell extracts from MDA-MB231 PIAS1 shRNA2 cells containing either a control shRNA, a WNT5A-specific shRNA (WNT5A shRNA1), or a non-working WNT5A shRNA (WNT5A shRNA2). (<b>c</b>) Mammosphere assay. Cells were seeded in Stem Cell Media (SCM) at 5,000 cells/dish, and spheres were counted 7 days later. Shown is a representative of 3 independent experiments. Error bars represent SEM. <i>P</i> values were determined by paired <i>t</i>-test. (<b>d</b>) Same as in <b>c</b> except that the parental MDA-MB231 cells were used with or without recombinant WNT5A treatment as indicated. (<b>e</b>) Tumorigenesis <i>in vivo</i>. Cells as in <b>b</b> were injected subcutaneously into SCID-beige mice (5×10⁶ cells/mice; n = 6). Shown is a representative of 3 independent experiments. Each data point represents mean ± SEM. <i>P</i> values were determined by non-paired <i>t</i>-test.