title: Polymerization by DNA polymerase eta is blocked by cis-diamminedichloroplatinum(II) 1,3-d(GpTpG) cross-link: implications for cytotoxic effects in nucleotide excision repair-negative tumor cells.
abstract: cis-Diamminedichloroplatinum(II) (cisplatin) forms DNA adducts that interfere with replication and transcription. The most common adducts formed in vivo are 1,2-intrastrand d(GpG) cross-links (Pt-GG) and d(ApG) cross-links (Pt-AG), with minor amounts of 1,3-d(GpNpG) cross-links (Pt-GNG), interstrand cross-links and monoadducts. Although the relative contribution of these different adducts to toxicity is not known, literature implicates that Pt-GG and Pt-AG adducts block replication. Thus, nucleotide excision repair (NER), by which platinum adducts are excised, and translesion DNA synthesis (TLS), which permits adduct bypass, are thought to be associated with cisplatin resistance. Recent studies have reported that the clinical benefit from platinum-based chemotherapy is high if tumor cells express low levels of NER factors. To investigate the role of platinum-DNA adducts in mediating tumor cell survival by TLS, we examined whether 1,3-intrastrand d(GpTpG) platinum cross-links (Pt-GTG), which probably exist in NER-negative tumor cells but not in NER-positive tumor cells, are bypassed by the translesion DNA polymerase eta (pol eta), which is known to bypass Pt-GG. We show that pol eta can incorporate the correct deoxycytidine triphosphate opposite the first 3'-cross-linked G of Pt-GTG but cannot insert any nucleotides opposite the second intact T or the third 5'-cross-linked G of the adducts, thereby suggesting that TLS does not facilitate replication past Pt-GTG adducts. Thus, our findings implicate Pt-GNG adducts as mediating the cytotoxicity of platinum-DNA adducts in NER-negative tumors in vivo.
authors.affiliation: Institute for Clinical Research, National Kyushu Cancer Center, 3-1-1 Notame, Fukuoka 811-1395, Japan.
authors.forename: Shotaro
authors.initials: S
authors.lastname: Chijiwa
authors.forename: Chikahide
authors.initials: C
authors.lastname: Masutani
authors.forename: Fumio
authors.initials: F
authors.lastname: Hanaoka
authors.forename: Shigenori
authors.initials: S
authors.lastname: Iwai
authors.forename: Isao
authors.initials: I
authors.lastname: Kuraoka
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000633:toxicity*; D016190:Carboplatin / Q000633:toxicity*; D002474:Cell-Free System; D002945:Cisplatin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000633:toxicity*; D018736:DNA Adducts / Q000494:pharmacology*; D004260:DNA Repair / Q000187:drug effects; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D003845:Deoxycytosine Nucleotides / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D019384:Nucleic Acid Synthesis Inhibitors; D009711:Nucleotides / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors; D013379:Substrate Specificity; D013698:Templates, Genetic; D000099270:Y-Family DNA Polymerases
chemical_list: D018906:Antineoplastic Agents, Alkylating; D016190:Carboplatin; D002945:Cisplatin; D018736:DNA Adducts; D004259:DNA-Directed DNA Polymerase; D003845:Deoxycytosine Nucleotides; D019384:Nucleic Acid Synthesis Inhibitors; D009711:Nucleotides; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; C024107:2'-deoxycytidine 5'-triphosphate; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases