Figure 2

Tumor cells expressing high levels of Mcl-1 and Bcl-xL protein exhibit chemoresistance. (a) Basal expression of Mcl-1 and Bcl-xL in various lung, colon and mesothelioma cancer cell lines determined by western blot analysis. (b) Mcl-1 and Bcl-xL contribute to cancer cell survival. A549, REN and H1299 cells were transfected with control siRNA, Mcl-1 siRNA, Bcl-xL siRNA, or a combination of both, via electroporation using Nucleofector II from Lonza (Switzerland). The cells were then seeded in 96 well plates, and cultured for 72 h. An XTT assay was performed following the manufacturer’s protocol to evaluate cell viability. Western blotting was used to measure the Bcl-xL and Mcl-1 protein levels after specific siRNA transfection. (c) To determine the chemo-response of DLD-1, H23, H1299, and A549 cells to SAHA and ABT-737, the cells were plated at a density of 5000 per well and treated with different concentrations of these chemotherapeutic agents over a 72 h incubation. An XTT assay was then performed in quadruplicate for each treatment condition and the experiments were repeated three times. (d) Mcl-1 was knocked down by siRNA in A549, REN and H1299 cells which were plated in a 96 well format. A control siRNA experiment was included. The cells were then treated with DMSO (control) or ABT-737 (IC30 doses) for 72 h, followed by an XTT assay for cell viability. The results were averaged from quadruplicate analyses for each treatment condition and the experiments were repeated three times.