Figure 7: The effect of the combination of either 5-aza-dC or RG108 and PKR inhibitor on CYP gene expression in HepG2 cells.

(A,B) The phosphorylation and expression of PKR after 5-aza-dC (A) or RG108 (B) treatment for 72 h at different concentrations. After treatment, the cells were harvested and western blot analysis was performed to detect the phosphorylated and total PKR protein levels. GAPDH was used as a loading control. A typical image is shown and the experiment was performed independently three times under each condition. (C,D) Expression levels of CYP1A1, 1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1 and 3A4 were examined in HepG2 cells exposed to a combination of PKR inhibitor and either 5-aza-dC (C) or RG108 (D). After 72 h exposure, expression levels of CYPs were examined by qRT-PCR. The comparative threshold cycle (Ct) method was used to determine the relative ratio of expression for each gene, which was corrected against HPRT1. Each data point represents the mean ± SEM of the values obtained from three independent experiments. The expression levels measured in control HepG2 cells were considered to be 1.0 expression. *p < 0.05, compared to control HepG2 cells.