Bcl-xL and Mcl-1 overexpression protect codependent cell lines from ABT-737–induced apoptosis. U266, MM.1s, 8226/S, and KMS-11 cell lines were stably transfected with pcDNA3.1 (Neo) and (A) pcDNA–Bcl-xL or (B) pcDNA–Mcl-1 vectors. Cell lines were treated with indicated concentrations of ABT-737 for 24 hours, and viability was determined by annexin V/PI staining. The data presented are the mean ± SD of at least 3 independent experiments. U266–Bcl-xL is significantly different from U266-Neo (P < .05) at 0.1μM ABT-737. MM.1s-Bcl-xL is significantly different from MM.1s-Neo at all concentrations of ABT-737 (0.1μM, P < .05; 0.2μM, P < .001; 0.4-0.8μM, P < .005). 8226-Bcl-xL is significantly different from 8226-Neo at all concentrations of ABT-737 (P < .005). MM.1s-Mcl-1 is significantly different from MM.1s-Neo (P < .005) at 0.4 to 0.8μM ABT-737. KMS11-Mcl-1 is statistically different from KMS11-Neo (P < .05) at all concentrations of ABT-737. 8226-Mcl-1 is significantly different from 8226-Neo (P < .001) at all concentrations of ABT-737. (C) Protein lysates were obtained using 2% 3(3-cholamidopropyl) dimethylammonio-1-propane sulfonate buffer for the indicated transfectants of KMS11, MM.1s, U266. Antiapoptotic proteins Mcl-1 and Bcl-xL were immunoprecipitated using specific monoclonal antibodies as described in “Antibodies” and “Coimmunoprecipitation studies.” The pellets were probed for Bim, Mcl-1, and Bcl-xL. The blots are representative of 2 independent experiments.
