title: Involvement of the Artemis protein in the relative biological efficiency observed with the 76-MeV proton beam used at the Institut Curie Proton Therapy Center in Orsay.
abstract: OBJECTIVE
  Previously we showed that the relative biological efficiency for induced cell killing by the 76-MeV beam used at the Institut Curie Proton Therapy Center in Orsay increased with depth throughout the spread-out Bragg peak (SOBP). To investigate the repair pathways underlying this increase, we used an isogenic human cell model in which individual DNA repair proteins have been depleted, and techniques dedicated to precise measurements of radiation-induced DNA single-strand breaks (SSBs) and double-strand breaks (DSBs).
  
  
  METHODS
  The 3-Gy surviving fractions of HeLa cells individually depleted of Ogg1, XRCC1, and PARP1 (the base excision repair/SSB repair pathway) or of ATM, DNA-PKcs, XRCC4, and Artemis (nonhomologous end-joining pathway) were determined at the 3 positions previously defined in the SOBP. Quantification of incident SSBs and DSBs by the alkaline elution technique and 3-dimensional (3D) immunofluorescence of γ-H2AX foci, respectively, was performed in SQ20 B cells.
  
  
  RESULTS
  We showed that the amount of SSBs and DSBs depends directly on the particle fluence and that the increase in relative biological efficiency observed in the distal part of the SOBP is due to a subset of lesions generated under these conditions, leading to cell death via a pathway in which the Artemis protein plays a central role.
  
  
  CONCLUSIONS
  Because therapies like proton or carbon beams are now being used to treat cancer, it is even more important to dissect the mechanisms implicated in the repair of the lesions generated by these particles. Additionally, alteration of the expression or activity of the Artemis protein could be a novel therapeutic tool before high linear energy transfer irradiation treatment.
authors.affiliation: Institut Curie Centre de Protonthérapie d'Orsay, Centre Universitaire, Orsay, France; Institut Curie, Centre Universitaire, Orsay, France; INSERM U612, Centre Universitaire, Orsay, France.
authors.forename: Valentin
authors.initials: V
authors.lastname: Calugaru
authors.affiliation: Institut Curie Centre de Protonthérapie d'Orsay, Centre Universitaire, Orsay, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Nauraye
authors.affiliation: Institut Curie, Centre Universitaire, Orsay, France.
authors.forename: Fabrice P
authors.initials: FP
authors.lastname: Cordelières
authors.affiliation: Centre d'Etude Atomique, Direction des Sciences du Vivant, Institut des Maladies Emergentes et des Thérapies Innovantes, Service d'Etude des Prions et des Infections Atypiques, Fontenay-aux-Roses, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Biard
authors.affiliation: Institut Curie Centre de Protonthérapie d'Orsay, Centre Universitaire, Orsay, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: De Marzi
authors.affiliation: Institut Curie, Centre Universitaire, Orsay, France; INSERM U612, Centre Universitaire, Orsay, France.
authors.forename: Janet
authors.initials: J
authors.lastname: Hall
authors.affiliation: Institut Curie, Centre Universitaire, Orsay, France; INSERM U612, Centre Universitaire, Orsay, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Favaudon
authors.affiliation: Institut Curie, Centre Universitaire, Orsay, France; INSERM U612, Centre Universitaire, Orsay, France. Electronic address: frederique.megnin@inserm.fr.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Mégnin-Chanet
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000502:physiology; D002173:Cancer Care Facilities; D002470:Cell Survival / Q000502:physiology / Q000528:radiation effects*; D053903:DNA Breaks, Double-Stranded; D053904:DNA Breaks, Single-Stranded; D045647:DNA Glycosylases / Q000502:physiology; D004260:DNA Repair / Q000502:physiology*; D051747:DNA-Activated Protein Kinase / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D004720:Endonucleases; D005602:France; D006367:HeLa Cells; D006657:Histones / Q000032:analysis; D006801:Humans; D009010:Monte Carlo Method; D009687:Nuclear Proteins / Q000172:deficiency / Q000502:physiology*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology; D061766:Proton Therapy; D011522:Protons; D012062:Relative Biological Effectiveness; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D009687:Nuclear Proteins; D011522:Protons; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; C101467:XRCC4 protein, human; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C426344:DCLRE1C protein, human; D004720:Endonucleases; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human