title: Induction of nuclear translocation of mutant cytoplasmic p53 by geranylgeranoic acid in a human hepatoma cell line.
abstract: Mutant p53 proteins in human hepatoma cell lines such as HuH-7 (Y220C) and PLC/PRF/5 (R249S) accumulate in the cytoplasm, and lose their transcriptional function. Geranylgeranoic acid (GGA) is a naturally occurring acyclic diterpenoid that induces cell death in both cell lines, but not in HepG2 cells harboring wild-type p53. Here, we demonstrate that micromolar concentrations of GGA induce a rapid nuclear translocation of cytoplasmic p53 in both p53-mutant cell lines and p53 knockdown attenuates GGA-induced cell death in HuH-7 cells. Cell-free experiments demonstrate that GGA is able to release 670-kD p53-containing complexes from putative huge macromolecular aggregates in post-mitochondrial fractions as revealed on blue-native gradient PAGE. Among several p53-target genes tested, GGA upregulates PUMA gene expression, and ivermectin, an inhibitor for importin α/β, blocks GGA-induced nuclear translocation of cytoplasmic p53 and suppresses GGA-induced upregulation of PUMA mRNA levels in HuH-7 cells. Taken together, these data suggest that GGA treatment stimulates a nuclear translocation of mutant p53 through its dissociation from cytoplasmic aggregates, which may be essential for GGA-induced cell death.
authors.affiliation: Molecular and Cellular Biology, Graduate School of Human Health Science, University of Nagasaki, Academy Hills 1-1-1, Nagayo, Nagasaki 851-2195, Japan.
authors.forename: Chieko
authors.initials: C
authors.lastname: Iwao
authors.affiliation: Molecular and Cellular Biology, Graduate School of Human Health Science, University of Nagasaki, Academy Hills 1-1-1, Nagayo, Nagasaki 851-2195, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Shidoji
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D051017:Apoptosis Regulatory Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure; D003600:Cytosol / Q000187:drug effects / Q000648:ultrastructure; D004224:Diterpenes / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007559:Ivermectin / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D028901:alpha Karyopherins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D028961:beta Karyopherins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; D004224:Diterpenes; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D028901:alpha Karyopherins; D028961:beta Karyopherins; D007559:Ivermectin; C040155:geranylgeranic acid