Fig. 4.
p52 protects cells from apoptotic death. (A) p52 protects LNCaP cells from apoptotic death induced by androgen deprivation. LNCaP cells were infected with adenoviruses expressing p100 or p52. The cells were cultured in RPMI medium 1640 supplemented with 10% FBS or 10% charcoal-stripped FBS. The degree of apoptosis was measured by cell death detection ELISA according to the manufacturer's instructions (catalog no. 1544675, Roche, Indianapolis, IN). Protein fractions were prepared and used for Western blot analysis by using antibody against cleaved poly(ADP-ribose)polymerase. (B) p52 increases the resistance of DU145 cells to etoposide-induced apoptosis. DU145 cells were infected with adenoviruses containing p100 or p52 and then treated with or without 50 μM etoposide for 24 h. The degree of apoptosis was measured by cell death detection ELISA, and cleavage of poly(ADP-ribose)polymerase was confirmed by Western blot analysis. (C) Dominant-negative Stat3 and the Stat3 mutant defective in acetylation abolish the antiapoptotic activity of p52. DU145 cells were transfected with p100 or p52 or cotransfected with Stat3F or Stat3K685R as indicated. The cells were then treated with 50 μM etoposide for 24 h. The degree of apoptosis was measured by cell death detection ELISA.