Figure 6. Jab1 depletion enhances the antitumor effects of cisplatin in NPC cells.

(A) Forty-eight hours after the cells were treated with control (Cont-si) or Jab1 siRNA (Jab1-si), NPC cells were treated with the 2 μM of cisplatin (CP) for another 48 hours, and the growth-inhibitory effects of cisplatin were quantified by an MTT assay. The inhibition ratio (%) is marked on the graphs. Data represent three independent experiments, mean±s.d. **P <0.01. (B) 1 nM (+) or 5 nM (++) of Jab1 siRNA-treated NPC cells were seeded into 6-well plates and exposed to cisplatin (CP) for 48 hours, and 10 days later the number of colonies formed were counted. (Left) Representative results of colony formation assays. (Right) Quantification of the relative number of colonies. The inhibition ratios (%) are marked on the graphs. Data represent three independent experiments, mean ±s.d. *P <0.05, **P <0.01. (C) siRNA-transfected NPC cells were stained with Annexin V and PI after cisplatin treatment for 48 hours. (Left) Representative results of apoptosis assays in NPC cells. (Right) Quantification of the percentage of apoptotic cells. Data represent three independent experiments, mean±s.d. *P <0.05, **P <0.01. (D) siRNA-transfected NPC cell were exposed to 10 μM of cisplatin for 48h; apoptotic cells were measured by the western blot analysis of cleaved PARP and cleaved caspase-3. Protein levels were quantified using ImageJ software.