title: Zebularine upregulates expression of CYP genes through inhibition of DNMT1 and PKR in HepG2 cells.
abstract: Drug-induced hepatotoxicity is one of the major reasons cited for drug withdrawal. Therefore, it is of extreme importance to detect human hepatotoxic candidates as early as possible during the drug development process. In this study, we aimed to enhance hepatocyte functions such as CYP gene expression in HepG2 cells, one of the most extensively used cell lines in evaluating hepatotoxicity of chemicals and drugs. We found that zebularine, a potent inhibitor of DNA methylation, remarkably upregulates the expression of CYP genes in HepG2 cells. In addition, we revealed that the upregulation of CYP gene expression by zebularine was mediated through the inhibition of both DNA methyltransferase 1 (DNMT1) and double-stranded RNA-dependent protein kinase (PKR). Furthermore, HepG2 cells treated with zebularine were more sensitive than control cells to drug toxicity. Taken together, our results show that zebularine may make HepG2 cells high-functioning and thus could be useful for evaluating the hepatotoxicity of chemicals and drugs speedily and accurately in in-vitro systems. The finding that zebularine upregulates CYP gene expression through DNMT1 and PKR modulation sheds light on the mechanisms controlling hepatocyte function and thus may aid in the development of new in-vitro systems using high-functioning hepatocytes.
authors.affiliation: Department of Pharmacology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Department of Pharmacology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Aizawa
authors.affiliation: Department of Pharmacology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
authors.forename: Kyaw Htet
authors.initials: KH
authors.lastname: Aung
authors.affiliation: Department of Pharmacology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Yamauchi
authors.affiliation: Department of Pharmacology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
authors.forename: Akito
authors.initials: A
authors.lastname: Tanoue
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D021983:Cyclophilins / Q000235:genetics*; D003562:Cytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000076123:DNA (Cytosine-5-)-Methyltransferase 1 / Q000235:genetics*; D019175:DNA Methylation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects; D006801:Humans; D019892:eIF-2 Kinase / Q000235:genetics*
chemical_list: D003562:Cytidine; C009131:pyrimidin-2-one beta-ribofuranoside; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; C000619380:DNMT1 protein, human; C000602769:EIF2AK2 protein, human; D019892:eIF-2 Kinase; D021983:Cyclophilins; C102923:PPIG protein, human