Figure 2.

Activation of p53 and apoptosis induced by resveratrol is inhibited by pifithrin-α in MCF-7 cells. (A) Cells were treated with 10 μM resveratrol (RV) for 4 h in the presence or absence of 20 μM pifithrin-α (PFT-α), a specific p53 inhibitor. As shown by immunoblots of nuclear fractions from a representative experiment above, and the accompanying graph below, resveratrol caused nuclear accumulation, serine phosphorylation and acetylation of p53 (P<0.05 comparing lanes 1 and 3 for each parameter). Treatment with PFT-α resulted in decreased phosphorylation and acetylation of p53 (P<0.05 for all parameters, comparing lanes 3 and 4). Molecular weight markers in this figure are not shown, but are similar to those shown in Figure 1. (B) Cells were treated with 10 μM resveratrol for 24 h in the presence or absence of 20 μM PFT-α. Apoptosis, shown by an increase in nucleosome content determined by ELISA, occurred with resveratrol treatment (P<0.001, comparing lanes 1 and 3. Pifithrin-α had no effect alone, but significantly blocked resveratrol-induced apoptosis (comparing lanes 3 and 4, P<0.005). Means±s.e.m. of six experiments are shown.