Bcl-xL and Myeloid cell leukaemia-1 contribute to apoptosis resistance of colorectal cancer cells

Figure 3 Modulation of Bcl-x_L expression alters chemotherapeutic drug-induced apoptosis. A: SW480 cells were transfected with siRNA specific for Bcl-x_L or transfected with siRNA specific for GFP as control (20 nmol/L). After the indicated time post transfection, total RNA was extracted and analyzed for Bcl-x_L expression by quantitative real-time PCR (left panel). Relative expression was calculated as described in the materials and methods section. In addition, after the indicated time post transfection, cells were lyzed and analyzed for Bcl-x_L expression by Western blot (right panel). α-Tubulin expression was used to control equal loading; B: SW480 cells were transfected with siRNA specific for Bcl-x_L or transfected with siRNA specific for GFP as control. 24 h post transfection, cells were treated with 5-FU (10 &mgr;g/mL), oxaliplatin (16 &mgr;g/mL) and irinotecan (60 &mgr;g/mL) for further 24 h. Cells were then harvested and analyzed for apoptosis induction (left panel). In addition, cell viability was measured by MTT assay and is shown relative to mock treated controls (right panel); C: SW480 cells were transfected with pcDNA3 Bcl-x_L or pcDNA3 empty vector as control. 24 h post transfection, cells were analyzed for Bcl-x_L expression using Western blotting (left panel). In addition, 24 h post transfection, cells were treated with 5-FU (15 &mgr;g/mL), oxaliplatin (10 &mgr;g/mL) and irinotecan (40 &mgr;g/mL) for further 24 h. Cells were then harvested and analyzed for apoptosis induction by flow cytometry. (B) and (C) assays were performed in triplicates. Values are means ± SD, ^aP < 0.05.