Figure 7.

Thioalbamide inhibits CSCs propagation. (a) Mammosphere formation efficiency assay was performed on breast cancer cells (MCF7, T47D, SKBR3, MDA-MB-231, and MDA-MB-468) after treatment for five days with 25 nM, 50 nM, and 100 nM thioalbamide. All breast cancer cells tested showed a significant dose dependent reduction in mammosphere formation after treatment with thioalbamide. Mammospheres were grown in no-attachment conditions and counted using an Olympus BX41 (4× magnification) microscope. 3D-spheres >50 μm were counted using an eye piece (“graticule”), and the percentage of cells plated that formed spheres was calculated and referred to as percent mammosphere formation efficiency (MFE). (b) Representative images of MCF7 cell mammospheres. Scale bar: 125 µm. (c) CD44 expression and (d) ALDH activity were chosen as CSC markers. Anti-human CD44-APC antibodies and (d) an ALDEFLUOR assay kit were used to stain MCF7 cells. Samples were analyzed using a SONY SH800 cell sorter. A significant reduction of CD44-positive cells and ALDH-positive cells was detected after treatment with 50 nM of thioalbamide in MCF7 cells grown in no-attachment (mammospheres) conditions. Values represent the mean ± SD of three independent experiments. ns = not significant; * P value < 0.05; ** P value <0.01; *** P value < 0.001; **** P value < 0.0001.