Fig. 4

Ionising radiation increases CBR1 mRNA via Nrf2 activation in HNSCC. a, CBR1 expression by western blot analysis 24 h after IR from 0 to 6 Gy in HNSCC cells (FaDu, YD10B, SNU-1041, YD8). α-tubulin was used as an internal loading control. b, Total RNA extracted from FaDu and YD8 cells measured by quantitative RT-PCR analysis (t-test; n = 4; *, p < 0.05; **, P < 0.01; ***, P < 0.001). c, FaDu cells were transfected with the luciferase reporter constructs prior to IR. Luciferase activity was assayed 48 h after IR. The relative luciferase activities are expressed in comparison with the activity of the pGL3-Basic construct (two-way ANOVA; **, P < 0.01; ***, P < 0.001). d, FaDu cells were transfected with scrambled or Nrf2 siRNA, prior to IR. Nrf2 and CBR1 expression levels were measured 48 h after IR (4 Gy). e, FaDu cells were transfected with each CBR1 reporter and treated with Scrambled siRNA or Nrf2-siRNA prior to IR. Luciferase activity was examined 48 h after IR (4 Gy, right panel) (t-test; n = 3; ***, P < 0.001 vs. Scrambled siRNA). f, The correlation was evaluated between Nrf2 mRNA expression and CBR1 mRNA expression from TCGA data (sample number = 279)