title: Amifostine metabolite WR-1065 disrupts homologous recombination in mammalian cells.
abstract: Repair of DNA damage through homologous recombination (HR) pathways plays a crucial role in maintaining genome stability. However, overstimulation of HR pathways in response to genotoxic stress may abnormally elevate recombination frequencies, leading to increased mutation rates and delayed genomic instability. Radiation-induced genomic instability has been detected after exposure to both low- and high-linear energy transfer (LET) radiations, but the mechanisms responsible for initiating or propagating genomic instability are not known. We have demonstrated that WR-1065, the active metabolite of amifostine, protects against radiation-induced cell killing and delayed genomic instability. We hypothesize that hyperstimulation of HR pathways plays a mechanistic role in radiation-induced genomic instability and that, in part, WR-1065 exerts it radioprotective effect through suppression of the HR pathway. Results of this study demonstrate that WR-1065 treatment selectively protected against radiation-induced cell killing in HR-proficient cell lines compared to an HR-deficient cell line. Further, WR-1065 treatment decreases HR in response to DNA damage using two different mammalian cell systems. This suppression of hyper-recombination is a previously unrecognized mechanism by which WR-1065 effects radioprotection in mammalian cells.
authors.affiliation: Department of Radiation Oncology, Radiation Oncology Research Laboratory, University of Maryland School of Medicine, Baltimore, Maryland, USA.
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Dziegielewski
authors.forename: Wilfried
authors.initials: W
authors.lastname: Goetz
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Murley
authors.forename: David J
authors.initials: DJ
authors.lastname: Grdina
authors.forename: William F
authors.initials: WF
authors.lastname: Morgan
authors.forename: Janet E
authors.initials: JE
authors.lastname: Baulch
mesh_terms: D004999:Amifostine / Q000494:pharmacology*; D000818:Animals; D016466:CHO Cells; D002166:Camptothecin / Q000494:pharmacology; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D004268:DNA-Binding Proteins / Q000378:metabolism; D042822:Genomic Instability; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D008624:Mercaptoethylamines / Q000494:pharmacology*; D034622:RNA Interference; D051135:Rad51 Recombinase / Q000378:metabolism; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D011995:Recombination, Genetic
chemical_list: D004268:DNA-Binding Proteins; D008624:Mercaptoethylamines; D011837:Radiation-Protective Agents; D017382:Reactive Oxygen Species; C110901:X-ray repair cross complementing protein 3; C020174:N-(2-mercaptoethyl)-1,3-diaminopropane; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D004999:Amifostine; D006918:Hydroxyurea; D002166:Camptothecin