title: Multiple pathways of recombination define cellular responses to cisplatin.
abstract: BACKGROUND
  Cisplatin is a DNA-damaging drug used for treatment of testicular tumors. The toxicity of cisplatin probably results from its ability to form DNA adducts that inhibit polymerases. Blocked replication represents a particular challenge for tumor cells, which are committed to unremitting division. Recombination provides a mechanism by which replication can proceed despite the presence of lesions and therefore could be significant for managing cisplatin toxicity.
  
  
  RESULTS
  Recombination-deficient Escherichia coli mutants were strikingly sensitive to cisplatin when compared with the parental strain. Our data identified both daughter-strand gap and double-strand break recombination pathways as critical for survival following treatment with cisplatin. Although it is established that nucleotide excision repair (NER) significantly protects against cisplatin toxicity, most recombination-deficient strains were as sensitive to the drug as the NER-deficient uvrA mutant. Recombination/NER deficient double mutants were more sensitive to cisplatin than the corresponding single mutants, suggesting that recombination and NER pathways play independent roles in countering cisplatin toxicity. Cisplatin was a potent recombinogen in comparison with the trans isomer and canonical alkylating agents. Mitomycin C, which like cisplatin, forms DNA cross-links, was also recombinogenic at minimally toxic doses.
  
  
  CONCLUSIONS
  We have demonstrated that all of the major recombination pathways are critical for E. coli survival following treatment with cisplatin. Moreover, recombination pathways act independently of NER and are of equal importance to NER as genoprotective systems against cisplatin toxicity. Taken together, these results shed new light on how cells survive and succumb to this widely used anticancer drug.
authors.affiliation: Department of Chemistry, Division of Bioengineering and Environmental Health, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Z Z
authors.initials: ZZ
authors.lastname: Zdraveski
authors.forename: J A
authors.initials: JA
authors.lastname: Mello
authors.forename: M G
authors.initials: MG
authors.lastname: Marinus
authors.forename: J M
authors.initials: JM
authors.lastname: Essigmann
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D005838:Genotype; D009154:Mutation / Q000502:physiology; D011995:Recombination, Genetic / Q000187:drug effects* / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D003432:Cross-Linking Reagents; C034697:transplatin; D002945:Cisplatin