title: Frequencies of mutagenic translesion DNA synthesis over cisplatin-guanine intra-strand crosslinks in lacZ plasmids propagated in human cells.
abstract: Cisplatin (cis-diamminedichloroplatinum(II)), a widely used anticancer drug, forms inter- and intra-strand DNA crosslinks. The major intra-strand crosslinks are Pt adducts at 1,2-d(GpG) and 1,3-d(GpNpG) (Pt-GG and Pt-GNG, respectively). Although most of the intra-strand crosslinks are removed by the nucleotide excision repair (NER), the remaining crosslinks can cause mutations through the translesion DNA synthesis (TLS) during chromosome replication. To understand the precise mechanism of cisplatin mutagenesis in human cells, the plasmid carrying a single Pt-GG or 1,3-d(GpTpG) crosslink (Pt-GTG) site-specifically in lacZ gene was constructed and propagated in NER-defective xeroderma pigmentosum cells. The plasmids retrieved from the cells were introduced into indicator bacterial cells to access frequencies of TLS and mutations. The experiments revealed that Pt-GTG blocked DNA replication more strongly and caused more mutations (29.1%) than Pt-GG (1.7%). Most mutations were G to A or T base changes at 5' G residue in the Pt-GTG crosslinks. These results indicate that the Pt-GTG crosslinks become effective obstacles for cancer cell division, and have an important role for cisplatin cancer therapy.
authors.affiliation: Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujikawa
authors.affiliation: Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kawanishi
authors.affiliation: Biological Chemistry Group, Division of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Kuraoka
authors.affiliation: Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570, Japan; Department of Life Science, Dongguk University, 26, 3 Pil-dong, Jung-gu, Seoul 100-715, South Korea. Electronic address: yagi-t@riast.osakafu-u.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yagi
mesh_terms: D002945:Cisplatin / Q000494:pharmacology*; D004249:DNA Damage / Q000187:drug effects*; D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects*; D006147:Guanine / Q000494:pharmacology*; D006801:Humans; D007763:Lac Operon; D016296:Mutagenesis / Q000187:drug effects; D009153:Mutagens / Q000633:toxicity*; D010957:Plasmids / Q000235:genetics; D014983:Xeroderma Pigmentosum / Q000188:drug therapy
chemical_list: D009153:Mutagens; D006147:Guanine; D002945:Cisplatin
keywords: Cisplatin; Intra-strand crosslink; Mutation; Translesion DNA synthesis