Figure 5. Prohibitin accumulation protects against cisplatin-induced cell death.

Cells were treated with 25 μM of cisplatin for 24 h. LB373 (A and B) and Mel 85 (C and D) are more sensitive to cisplatin treatment when PHB is partially knocked down using specific small interference RNA (siRNA). Note that PHB siRNA, but not ctl siRNA, avoided the accumulation of PHB after cisplatin treatment (A and C). As for Figures 3 and 4, the ratio was determined as 1 for each control condition (absence of cisplatin). The relative frequency of hypodiploid cells was used as a measure for cell death. Increased death was observed in both cell lines treated with PHBsi RNA (B and D), which also led to a significant sensitivity of cells to cisplatin treatment. (PHBsi, small interference RNA to PHB; Ctlsi, nonspecific small interference RNA). Representative experiment of three independent assays.