Fig. 1: NDRG2 sensitized U937 cells to cisplatin through the modulation of the BAK-to-Mcl-1 ratio.

a U937-Mock and -NDRG2 cells were incubated with cisplatin (10 μM, 20 h). The cells were stained with Annexin V/PI and analyzed by flow cytometry. b The cells were stained with MitoTracker Red CMXRos, and those with depolarized mitochondria were analyzed by flow cytometry. c Bcl-2 family proteins were analyzed by immunoblotting using the indicated antibodies. The normalized BAK or Mcl-1 band intensity with α-tubulin was acquired using Image J software to determine the fold induction. d U937-Mock and U937-NDRG2 cells treated with cisplatin were immunostained with anti-active Bax and analyzed using a confocal microscope. Active Bax was labeled with a FITC-conjugated secondary antibody (green), and the mitochondria and nuclei were stained with Mitotracker CMXRos (red) and DAPI (blue), respectively. U937-Mock cells infected with the shMcl-1 lentivirus (e) or U937-NDRG2 cells infected by the shBAK lentivirus (f) were treated with cisplatin and the apoptotic cells were analyzed by Annexin V/PI staining. Ctrl: vehicle treatment or not infected group. **p < 0.01, ***p < 0.005 by t-tests. Data are presented as mean ± SEM