Fig. 5
Tempol inhibits cycling hypoxia-induced Bcl-xL induction and expression in vivo. a Bcl-xL promoter-dependent transactivation of luciferase activity in U251 and U87 cells cultured in normoxia (Nor) and cycling (CyH) hypoxia (<1 % O2) with or without pretreatment with Tempol, YC-1, or Bay 11-7082. ***P < 0.001 compared to Nor. #P < 0.05, ##P < 0.01, ###P < 0.001 compared to CyH with vehicle treatment. b In vivo bioluminescence (BLI) images of the transcriptional activation of Bcl-xL in U87 glioblastoma xenografts before and after Tempol, YC-1, or Bay 11-7082 treatment. c Quantitative data obtained from the BLI imaging of the transcriptional activation of Bcl-xL in U87 xenografts. Data represent the mean ± standard deviation of average counts within the tumor region of interest in BLI from 6 mice. ***P < 0.001 compared to Nor. #P < 0.05, ##P < 0.01, ###P < 0.001 compared to CyH with vehicle treatment. d Bcl-xL protein levels in homogenized tumor tissues derived from the above groups. e Bcl-xL mRNA levels in normoxic cells (Hoechst 3342+ and GFP−), chronic hypoxic cells (Hoechst 3342− and GFP+), and cycling hypoxic cells (Hoechst 3342+ and GFP+) isolated from disaggregated GBM8401/hif-1-r and U87/hif-1-r xenografts. ***P < 0.001 compared to normoxic tumor cells (Hoechst 3342+ and GFP−). Error bars denote the standard deviation within triplicate experiments