Fig. 3.

Inhibition of PXR affects PB-induced CYP3A4 expression. Human primary hepatocytes (HL#139) were infected with lentiviral/hPXR/small hairpin RNA (shRNA) or lentiviral-negative control followed by treatment with 0.1% DMSO, 10 µM RIF, or 1 mM PB as detailed in Materials and Methods. Expression of hPXR (A) and CYP3A4 (B) was analyzed by RT-PCR and western blotting assays. In a separate experiment, human primary hepatocytes (HL#139) and fully differentiated hCAR-null HepaRG cells were treated with 0.1% DMSO, 10 µM RIF, 1 mM PB, and 2.5 µM SPA70 alone or cotreatment of SPA70 with RIF or PB (C and D). RT-PCR and western blotting were used to measure the mRNA and protein expression of CYP3A4. Data are expressed as mean ± S.D. (n = 3) (***P < 0.001).