Figure 4.
ABT-737 and WEHI-539 sensitize colon CSCs toward chemotherapy. (a) Untransduced or (b) BCLXL-transduced spheroid cultures were treated with 1 μM of ABT-737, ABT-199 or WEHI-539 for 24 h and limiting dilution assay was performed on CSCs (TOP-GFPhigh). ABT-737 and WEHI-539 decreased clonogenic capacity in CSCs (a), but not when BCLXL is overexpressed (b). Significance is indicated (***P<0.001) and is related to vehicle (DMSO) alone treatment. (c) Western blot analysis on the different spheroid cultures for BCL2 (upper panel), BCLXL (middle panel) and BCLW (lower panel) proteins. Control western blots for the kinase ERK1/2, which is stably expressed in the spheroids, are shown. (d) Spheroid cultures were treated with 100 nM ABT-737 or WEHI-539 in combination with 50 μM oxaliplatin for 24 h and subsequently analyzed for caspase-3 activity or (e) clonogenic capacity using limiting dilution on CSCs (TOP-GFPhigh). Significance is indicated (**P<0.01 and ***P<0.001) and is related to oxaliplatin alone treatment. (f) Spheroid cultures were treated with 100 nM ABT-737, ABT-199 or WEHI-539 in combination with 0.5 μM oxaliplatin for 24 h and cell numbers were measured at various time points using cell titer blue