FIG 4.

P53 is required for DFO-induced reactivation of EBV. (A) Knockdown of p53 attenuates DFO-directed induction of EBV IE lytic antigens. AGS-Akata cells grown in 10-cm dishes were transduced with lentivirus plasmids that express either of two different nontargeting shRNAs (4 μg/dish; controls 1 and 2) or a mixture of five shRNAs that target p53 (0.8 μg of each one/dish). Two days later, cells were incubated for 24 h in the absence (−) or presence (+) of 200 μM DFO and harvested, and whole-cell extracts were prepared and analyzed for the indicated proteins by immunoblotting. (B) Overexpression of p53 rescues DFO induction of EBV reactivation inhibited by knockdown of p53. AGS-Akata cells were cotransfected with (i) control 1 shRNA or the shRNAs that target p53 as described for panel A and (ii) 100 ng/dish of pcDNA3-WTp53 (lanes 5 and 6) or pcDNA3 (lanes 1 to 4). Two days later, the cells were incubated in the absence or presence of 200 μM DFO for 24 h and processed as described for panel A. Data shown are representative of those from three independent experiments.