IL-8 depletion causes decrease in anti-apoptotic proteins and increase in pro-apoptotic proteins in AIPC cells. A. Depletion of IL-8 in PC-3 and (B) DU145 cells caused increased spontaneous apoptosis detected by caspase-9 activation; cleaved caspase-9 fragments, both of and 37 kDa and 35 kDa along with 39 kDa latent caspase-9 and cleaved poly(ADP-ribose)polymerase (PARP) (85 kDa) proteins are shown. Levels of BCL-2, BCL-xL, BAX and BAD were detected by western blotting of cell lysates prepared 48 h after transfecting the cells with 50 nM IL-8 siRNA or C-siRNA. β-Actin level is shown to ascertain equal protein loading in all lanes. C. Decrease in BCL-2 level was due to decrease in mRNA level determined by Q-PCR. D. The decrease in BCL-2 and increase in BAX level may also be due to rapid degradation of BCL-2 protein that in turn resulted in increased level of BAX. Inhibition of proteasome degradation of BCL-2 by MG132 shows unchanged level of BCL-2 between C-siRNA transfected control and IL-8siRNA transfected cells (Lanes 3 and 4).