NRF2 Regulates HER1 Signaling Pathway to Modulate the Sensitivity of Ovarian Cancer Cells to Lapatinib and Erlotinib

Figure 5

Inhibition and knockdown of NRF2 by bexarotene and siRNA, respectively, elevate the level of ROS and depletion of total glutathione level. (a) Bexarotene treatment and knockdown of NRF2 by siRNA cause increase in ROS levels. Exponentially growing cells were seeded in triplicates in opaque flat bottom black-walled 96-well plates for 24 h. Following this, cells were either left untreated (UT) or treated with 2.5 μM bexarotene or 7 pmol of siRNA (scrambled or targeted) for different time points as indicated. Following incubations, cells were loaded with DCFDA fluorescent stain for 45 min and assayed for ROS by measuring fluorescence as described in Materials and Methods. (b) Bexarotene and siRNA cause depletion of total glutathione. Exponentially growing cells were seeded in 60 mm tissue culture plates for 24 h and either left untreated (UT) or treated with media containing 1 nM heregulin alone (HRG) or with cotreatment of 2.5 μM bexarotene or 100 pmol siRNA for 24 h before being harvested to prepare protein lysates and processed for glutathione assay as described in Materials and Methods. Data is shown as fold change of bexarotene or siRNA-treated cells to UT or scrambled siRNA, respectively, with statistical significance determined by one-way ANOVA followed by Tukey’s post hoc test. , , , and .

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