Figure 6: The effect of combined DNMT1 and PKR inhibition on CYP gene expression in HepG2 cells.

(A) shDNMT1 was stably transfected into HepG2 cells and shDNMT1-HepG2-2, -5 and -6 cells showed downregulation of DNMT1 protein level. (B) Expression levels of CYP1A1, 1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1 and 3A4 were examined in shDNMT1-HepG2-2, -5 and -6 cells by qRT-PCR. The expression level observed in parent cells was considered to be 1.0 expression. (C–E) shDNMT1-HepG2-2 cells (C), shDNMT1-HepG2-5 cells (D) and shDNMT1-HepG2-6 cells (E) were exposed to 1000 μM PKR inhibitor for 72 h, and expression levels of CYP1A1, 1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1 and 3A4 were examined by qRT-PCR. The expression level of parent HepG2 cells without PKR inhibitor treatment was considered to be 1.0 expression. 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. *p < 0.05, compared to parent HepG2 cells.