Fig. 5.

Inhibition of Noxa up-regulation attenuates killing by the ABT-737/cisplatin combination. UM-22A cells were seeded in 100-mm dishes, grown overnight, and then transfected for 24 h with nonspecific siRNA or Noxa siRNA, as described under Materials and Methods. The transfected cells were either then left untreated or treated for an additional 24 h with 0.1% DMSO, 10 μM ABT-737 alone, 10 μM cisplatin alone, or ABT-737 plus cisplatin (10 μM each). After treatment, cells were harvested and analyzed by immunoblotting to determine Noxa protein levels. In addition, trypan blue exclusion assays were used to determine the percentage of cell survival. The plotted data represent the average of means from three independent experiments, and error bars represent the S.E.M. P values were determined using one-way ANOVA followed by Tukey's multiple comparison test. ^*, P < 0.01 comparing ABT-737/cisplatin-treated cells transfected with Noxa siRNA versus nonspecific siRNA.