title: Protein kinase C-mediated down-regulation of MDR3 mRNA expression in Chang liver cells.
abstract: MDR3 is a phospholipid translocator homologous to MDR1 P-glycoprotein. MDR3 localizes to the canalicular membrane and contributes to the secretion of bile. To elucidate the role of protein kinase C in the regulation of MDR3 gene expression, we investigated the effect of phorbol 12-myristate 13-acetate (PMA) on the level of MDR3 mRNA in human Chang liver cells by a reverse transcription-polymerase chain reaction method. The steady-state expression of MDR3 mRNA was decreased by PMA after treatment for 8-20 hr and at concentrations of 1-100 nM. PMA also decreased the doxorubicin-induced expression of MDR3 mRNA. 4alpha-Phorbol 12,13-didecanoate, a negative control compound, did not decrease the expression at these concentrations. The down-regulatory effect of PMA was partially suppressed by the protein kinase C inhibitors 2-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-3-(1H-indol-3-yl)maleimide (GF109203X) and calphostin C. Furthermore, cycloheximide, a protein synthesis inhibitor, antagonized the effect of PMA. From these results, it was suggested that the level of MDR3 mRNA was negatively regulated by a protein kinase C- and protein synthesis-dependent system and that the system regulated both the stable and inducible expression of MDR3 mRNA.
authors.affiliation: Department of Medicine, Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3, Kanagawa-machi, 920-1181, Kanazawa, Japan. s-wakusawa@hokuriku-u.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Wakusawa
authors.forename: R
authors.initials: R
authors.lastname: Ikeda
authors.forename: Y
authors.initials: Y
authors.lastname: Shiono
authors.forename: H
authors.initials: H
authors.lastname: Hayashi
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000096:biosynthesis / Q000235:genetics*; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000235:genetics*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology; D004347:Drug Interactions; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D011493:Protein Kinase C / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D018528:ATP-Binding Cassette Transporters; D000903:Antibiotics, Antineoplastic; D002273:Carcinogens; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D004317:Doxorubicin; C095122:multidrug resistance protein 3; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate