Effects of flavones on Nrf2-targeted gene expression.

<p>(<b>A and B</b>) Luteolin exerts the strongest stimulatory effects on HO-1 and xCT expression. PC12 cells were treated with 20 μM luteolin and apigenin. After 6 h, RNA was prepared and the mRNA expression of HO-1 and xCT was analyzed by RT-Q-PCR and normalized to β-actin, as described in Materials and Methods. Data represent the mean ± SD of three independent experiments. *, <i>p</i><0.05; **, <i>p</i><0.01 represents significant differences compared with vehicle control. After 9 h, total cell lysates were prepared and subjected to Western blotting analysis of HO-1 and α-tubulin, which was used as a loading control. (<b>C-F</b>) Luteolin and apigenin counteract 4-HNE-mediated phase II enzyme expression. PC12 cells were treated with luteolin or apigenin (10 or 20 μM) 30 min prior to 4-HNE (25 μM) treatment. After 4 h, RNA was prepared and the expression of HO-1, xCT and GCLC was analyzed by RT-Q-PCR and normalized to β-actin, as described in Materials and Methods. After 6 h, total cell lysates were prepared and subjected to Western blotting analysis of HO-1 and α-tubulin, which was used as a loading control. Data obtained from immunoblots were then analyzed using Phoretix Gel Analysis Software as described under Materials and methods. The data represent the mean ± SD of three independent experiments. **<i>p</i><0.01 represents significant differences compared with vehicle control (without 4-HNE); #<i>p</i><0.01; ##, <i>p</i><0.01 represent significant differences compared with the 4-HNE-treated vehicle group.