title: DNA polymerase zeta accounts for the reduced cytotoxicity and enhanced mutagenicity of cisplatin in human colon carcinoma cells that have lost DNA mismatch repair.
abstract: The mutagenicity of cis-diamminedichloroplatinum(II) (DDP; cisplatin) and the rate at which resistance develops with repeated exposure to DDP are dependent on mutagenic translesional replication across DDP DNA adducts, mediated in part by DNA polymerase zeta, and on the integrity of the DNA mismatch repair (MMR) system. The aim of this study was to determine whether disabling Pol zeta by suppressing expression of its hREV3 subunit in human cancer cells can reduce the mutagenicity of DDP and whether loss of MMR facilitates mutagenic Pol zeta-dependent translesional bypass. The HCT116+ch3 (MMR(+)/REV3(+)) and HCT116 (MMR(-)/REV3(+)) human colon carcinoma cell lines were engineered to suppress hREV3 mRNA by stable expression of a short hairpin interfering RNA targeted to hREV3. The effect of knocking down REV3 expression was to completely offset the DDP resistance mediated by loss of MMR. Knockdown of REV3 also reduced the mutagenicity of DDP and eliminated the enhanced mutagenicity of DDP observed in the MMR(-)/REV3(+) cells. Similar results were obtained when the ability of the cells to express luciferase from a platinated plasmid was measured. We conclude that Pol zeta plays a central role in the mutagenic bypass of DDP adducts and that the DDP resistance, enhanced mutagenicity, and the increased capacity of MMR(-)/REV3(+) cells to express a gene burdened by DDP adducts are all dependent on the Pol zeta pathway.
authors.affiliation: Department of Medicine and the Cancer Center, University of California-San Diego, La Jolla, CA 92093, USA.
authors.forename: Xinjian
authors.initials: X
authors.lastname: Lin
authors.forename: Julie
authors.initials: J
authors.lastname: Trang
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Okuda
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Howell
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D020137:Base Pair Mismatch; D002945:Cisplatin / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D006801:Humans; D016296:Mutagenesis / Q000187:drug effects*; D019384:Nucleic Acid Synthesis Inhibitors; D010957:Plasmids; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D012333:RNA, Messenger; C425929:DNA polymerase zeta; D004259:DNA-Directed DNA Polymerase; C118285:REV3L protein, human; D002945:Cisplatin