Possible involvement of pregnane X receptor–enhanced CYP24 expression in drug-induced osteomalacia
J. Clin. Invest. Jean Marc Pascussi, et al. 115:177 doi:10.1172/JCI21867 [Go to this article.]

Figure 2
Effects of rifampicin on CYP24 gene transcription in human hepatocytes. (A) Time course of induction of CYP24 and CYP3A4 by rifampicin (RIF). Hepatocytes were cultured for the indicated times with or without 20 μM rifampicin. Total RNA was reverse-transcribed and analyzed by quantitative RT-PCR using primers for CYP3A4 (white bars), CYP24 (black bars), and GAPDH. Data presented are means ± SE (from 3 different cultures from 3 different liver donors) of the ratio of mRNA levels in treated cells to corresponding levels in untreated cells, normalized with respect to GAPDH mRNA levels. (B) Dose-dependent induction of CYP24 and CYP3A4 by rifampicin. Hepatocytes were cultured for 48 hours in the absence or presence of increasing concentrations of rifampicin, from 1 μM to 20 μM. Total RNA was extracted and analyzed by quantitative RT-PCR for CYP24 (black bars), CYP3A4 (white bars), and GAPDH mRNA content. Data presented are means ± SE (from 3 different cultures from 3 different liver donors) of the ratio of mRNA levels in treated cells to corresponding levels in untreated cells, normalized with respect to GAPDH mRNA levels. (C) Rifampicin has direct transcriptional effects on CYP24. Hepatocytes from liver donor number 220 were untreated (UT) or pretreated with 10 μg/ml CHX for 1 hour before addition of 20 μM rifampicin. Total RNA was harvested 24 hours later, reverse-transcribed, and analyzed by semiquantitative RT-PCR for CYP24 (45 cycles) and GAPDH (25 cycles) mRNA content.