Fig. 5.

Impact of COX-2 and PPARγ siRNA on celecoxib-induced DNA fragmentation of A549, H460, and H358 cells. Effect of COX-2 siRNA (A) and PPARγ siRNA (B) on COX-2 and PPARγ protein expression and DNA fragmentation in the presence or absence of 30 µM (A549, H460) or 50 µM (H358) celecoxib. Cells were incubated with celecoxib or its vehicle for 24 h (A549), 48 h (H460), and 18 h (H358), respectively. Transfection with COX-2 siRNA (A, 2.5 µg/ml), PPARγ siRNA (B, 1.25 µg/ml), or the respective equal concentrations of nonsilencing siRNA was performed 24 h prior to addition of test compounds to the cells. β-actin was used as loading control for Western blot analysis. Percent control represents comparison with vehicle-treated cells (100%) in the absence of test substances. Values are means ± SEM of n = 3–4 experiments. **P < 0.01, ***P < 0.001 versus corresponding vehicle control; ^#P < 0.05, ^###P < 0.001 versus celecoxib; one-way ANOVA plus Bonferroni test.