Treatment with Mcl-1 siRNA decreases MM cell proliferation. (A) Down-regulation of Mcl-1 expression in a dose-dependent manner by Mcl-1 siRNA. MM1s cells were transfected with indicated doses of Mcl-1 siRNA (and scrambled siRNA, 5 μg). Mcl-1 expression was determined by Western blot analysis at 24 hours (left) and 48 hours (right). Whole-cell lysates of MM1s cells served as an additional control. Because no change in Bcl-2 expression was observed, Bcl-2 is used as a loading control. (B) Transfection of Mcl-1 siRNA inhibits MM1s proliferation. After transfection with Mcl-1 siRNA or scrambled siRNA (5 μg), 2 × 104 MM1s cells per well were cultured for 24 and 48 hours. Proliferation assays were performed as described in “Materials and methods.” Nontransfected cells served as an additional control. Results shown are the percentage of 3H-thymidine incorporation compared with control. Shown is 1 representative experiment of 3; error bars indicate standard deviation.
