Figure 7. Foretinib and auranofin suppress cell viability and tumor-sphere formation by ALDH1high cells. (A) c-Met, phospho-Met, PKCλ and ALDH1A3 protein expression in MDA-MB 157 and MDA-MB 468 human basal-like breast cancer cell lines. β-actin was used as an internal control. (B) Cell viability of ALDH1high cells isolated from MDA-MB 157 cells treated for 7 days with foretinib (0.03, 0.1, 0.3, 1, 3 and 10 μM) was assessed in WST-8 assays. Values for the test groups are expressed relative to cells treated with 0.1% DMSO. (C) Cell viability of ALDH1high cells isolated from MDA-MB 157 cells treated for 7 days with auranofin (0.03, 0.1, 0.3, 1, 3 and 10 μM) was assessed using WST-8 assays. Values for the test groups are expressed relative to cells treated with 0.06% DMSO. (D) Cell viability of ALDH1high cells isolated from MDA-MB 157 cells treated for 7 days with or without foretinib (0.1, 0.3, 1 μM) and/or auranofin (0.1, 0.3, 1 μM) was assessed using WST-8 assays. Values for the test groups are expressed relative to cells treated with 0.01% DMSO. (E) Representative images of tumor-spheres formed by ALDH1high cells isolated from MDA-MB 157 cells treated for 6 days with foretinib and/or auranofin. Bars: 100 μm. (F), (G) Foretinib and/or auranofin suppressed tumor-sphere formation measured as tumor-sphere area (F) or number (G). Values for the test groups are expressed relative to cells treated with 0.01% DMSO. (B), (C), (D), (F): Data represent the mean±SE (three independent experiments). (G): Data represent the mean±SD (three independent experiments). (D), (F), (G): Statistical significance was determined by Tukey's test. p-Value (**p<0.01, *p<0.05); vs. 0.01% DMSO. N.S.: Not significant.