FIGURE 5.

NRF2 is essential for 1,2-NQ-induced IL-11 production. A, a putative NRF2-binding site is partially overlapped with the 5′ AP-1 site. B, HepG2 cells were transfected with an empty vector or graded amounts (0.1, 0.3, and 1.0 μg/sample) of an expression vector for Myc-tagged NRF2 along with the indicated reporter vectors. Luciferase activities were calculated 18 h after transfection, and relative luciferase activities are expressed as -fold activation compared with empty vector-transfected cells. Results are mean ± S.D. (error bars) of triplicate samples. ***, p < 0.001; ns, not significant versus control vector-transfected cells. C, knockdown of NRF2 by siRNA suppresses 1,2-NQ-induced Il11 mRNA induction. HepG2 cells were transfected with control siRNA or two different siRNAs against NRF2. At 48 h after transfection, cells were unstimulated or stimulated with 1,2-NQ (50 μm) for 4 h. Relative amounts of NRF2 or IL11 mRNAs were determined by qPCR. Results are mean ± S.D. of triplicate samples. ***, p < 0.001 versus control siRNA-transfected cells. Cell lysates were analyzed by immunoblotting with the indicated antibodies. D, knockdown of NRF2 by siRNA does not suppress H₂O₂-induced Il11 mRNA induction. HepG2 cells were transfected with siRNAs as in C and stimulated with H₂O₂ (1 mm) for 4 h. Relative amounts of NRF2 or IL11 mRNAs were determined by qPCR. Results are mean ± S.D. of triplicate samples. **, p < 0.01; ns, not significant versus control siRNA-transfected cells. All results are representative of two or three independent experiments.