PUMA induces apoptosis in p53-deficient PC-3 cells. PC-3 cells were treated with 2 µg siRNA for 72 h, and subsequently were transfected with 8 µg PUMA or pCEP4 plasmid. (A) PUMA-induced apoptosis was initially evaluated by inhibition of cell survival. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed 24 h subsequent to complementary DNA transfection in siRNA-treated PC-3 cells. The fold inductions are shown relative to mock-transfected cells. (B) DNA fragmentation was determined by histone release. Histone release was measured by enzyme-linked immunosorbent assay in samples collected 9 h subsequent to the second transfection. The fold induction of DNA fragmentation in PC-3 cells transfected with PUMA plasmids is shown relative to the control value of pCEP4-transfected cells. (C) Caspase-3 activation was determined in control and p53-deficient PC-3 cells 8 h subsequent to transfection with PUMA. *P<0.05, **P<0.01. PUMA, p53 upregulated modulator of apoptosis; siRNA, small interfering RNA; sc, control.