Relationship between clock gene expression and CYP2C19 and CYP3A4 with benzodiazepines.

The present study aimed to clarify the expressions and roles of clock genes involved in drug metabolism in patients taking benzodiazepines (BZDs), as well as the drug metabolism regulators controlled by clock genes for each BZD type. The relationships between the expressions of the clock genes BMAL1, PER2, and DBP and the drug-metabolizing enzymes CYP3A4 and CYP2C19 were investigated using livers from BZD-detected autopsy cases. In addition, the effect of BZD exposure on various genes was examined in HepG2 human hepatocellular carcinoma cells. The expressions of DBP, CYP3A4, and CYP2C19 in the liver were lower in the diazepam-detected group than in the non-detected group. Furthermore, BMAL1 expression correlated with CYP2C19 expression. Cell culture experiments showed that the expressions of DBP and CYP3A4 decreased, whereas those of BMAL1 and CYP2C19 increased after diazepam and midazolam exposure. The results of the analyses of autopsy samples and cultured cells suggested that DBP regulates CYP3A4 when exposed to BZD. Understanding the relationship between these clock genes and CYPs may help achieve individualized drug therapy.