title: Downregulation of cytochrome P450 2C8 by 3-methylcholanthrene in human hepatocellular carcinoma cell lines.
abstract: The marked induction of cytochromes P450 such as CYP1A1 caused by polycyclic aromatic hydrocarbons (PAHs) like 3-methylcholanthrene (MC) is often accompanied by suppression of other hepatic P450s. The molecular mechanisms, functional consequences, and human relevance of P450 downregulation by PAHs are poorly understood. MC suppresses mRNA levels for CYP2C8, an important human P450, in cultured human hepatocytes. To avoid hepatocyte lot-to-lot variability, we assessed CYP2C8 regulation by MC in HepaRG cells, a terminally differentiated human hepatocellular carcinoma cell line that maintains high P450 expression. MC strongly induced CYP1A1 mRNA levels and markedly downregulated CYP2C8 mRNA levels in HepaRG cells. Although MC also suppressed CYP2C8 mRNA levels in the HepG2 human hepatocellular carcinoma cell line, basal CYP2C8 expression was extremely low. HepaRG cells appear to be an appropriate model system for studying the mechanisms and functional consequences of CYP2C8 downregulation by PAHs.
authors.affiliation: Department of Pharmacology and Toxicology, Medical Sciences Building, University of Toronto, Toronto, ON M5S 1A8, Canada.|Department of Pharmacology and Toxicology, Medical Sciences Building, University of Toronto, Toronto, ON M5S 1A8, Canada.
authors.forename: Rucha
authors.initials: R
authors.lastname: Utgikar
authors.affiliation: Department of Pharmacology and Toxicology, Medical Sciences Building, University of Toronto, Toronto, ON M5S 1A8, Canada.|Department of Pharmacology and Toxicology, Medical Sciences Building, University of Toronto, Toronto, ON M5S 1A8, Canada.
authors.forename: David S
authors.initials: DS
authors.lastname: Riddick
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D065727:Cytochrome P-450 CYP2C8 / Q000235:genetics*; D015536:Down-Regulation / Q000187:drug effects*; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D008748:Methylcholanthrene / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D008748:Methylcholanthrene; C450259:CYP2C8 protein, human; D065727:Cytochrome P-450 CYP2C8
keywords: 3-methylcholanthrene; 3-méthylcholanthrène; CYP2C8; HepG2 cells; HepaRG cells; aryl hydrocarbon receptor; cellules HepG2; cellules HepaRG; cytochrome P450; drug metabolism; hydrocarbures polycycliques aromatiques; métabolisme des médicaments; polycyclic aromatic hydrocarbons; récepteur des hydrocarbures arylés