title: A radiosensitizing effect of RAD51 inhibition in glioblastoma stem-like cells.
abstract: Radioresistant glioblastoma stem cells (GSCs) contribute to tumor recurrence and identification of the molecular targets involved in radioresistance mechanisms is likely to enhance therapeutic efficacy. This study analyzed the DNA damage response following ionizing radiation (IR) in 10 GSC lines derived from patients.
  
  
  
  DNA damage was quantified by Comet assay and DNA repair effectors were assessed by Low Density Array. The effect of RAD51 inhibitor, RI-1, was evaluated by comet and annexin V assays.
  
  
  
  While all GSC lines displayed efficient DNA repair machinery following ionizing radiation, our results demonstrated heterogeneous responses within two distinct groups showing different intrinsic radioresistance, up to 4Gy for group 1 and up to 8Gy for group 2. Radioresistant cell group 2 (comprising 5 out of 10 GSCs) showed significantly higher RAD51 expression after IR. In these cells, inhibition of RAD51 prevented DNA repair up to 180 min after IR and induced apoptosis. In addition, RAD51 protein expression in glioblastoma seems to be associated with poor progression-free survival.
  
  
  
  These results underscore the importance of RAD51 in radioresistance of GSCs. RAD51 inhibition could be a therapeutic strategy helping to treat a significant number of glioblastoma, in combination with radiotherapy.
authors: INSERM1084, Laboratoire de Neurosciences Expérimentales et Cliniques, Poitiers, F-86021, France.|Université de Poitiers, U1084, Poitiers, F-86022, France.|CHU de Poitiers, Laboratoire de Cancérologie Biologique, Poitiers, F-86021, France.
authors: Anaïs
authors: A
authors: Balbous
authors: CHU de Poitiers, Laboratoire de Cancérologie Biologique, Poitiers, F-86021, France.
authors: Ulrich
authors: U
authors: Cortes
authors: CHU de Poitiers, Laboratoire de Cancérologie Biologique, Poitiers, F-86021, France.
authors: Karline
authors: K
authors: Guilloteau
authors: CHU de Poitiers, Laboratoire de Cancérologie Biologique, Poitiers, F-86021, France.
authors: Pierre
authors: P
authors: Rivet
authors: CHU de Poitiers, Service d'Oncologie Radiotherapique, Poitiers, F86021, France.
authors: Baptiste
authors: B
authors: Pinel
authors: CHU de Poitiers, Service d'Anatomo-cytopathologie, Poitiers, F86021, France.
authors: Mathilde
authors: M
authors: Duchesne
authors: CHU de Poitiers, Service d'Anatomo-cytopathologie, Poitiers, F86021, France.
authors: Julie
authors: J
authors: Godet
authors: CHU de Poitiers, Service d'Oncologie Radiotherapique, Poitiers, F86021, France.
authors: Odile
authors: O
authors: Boissonnade
authors: CHU de Poitiers, Service de Neurochirurgie, Poitiers, F86021, France.
authors: Michel
authors: M
authors: Wager
authors: CHU de Poitiers, Service d'Oncologie Radiotherapique, Poitiers, F86021, France.
authors: René Jean
authors: RJ
authors: Bensadoun
authors: CHU de Poitiers, Laboratoire de Cancérologie Biologique, Poitiers, F-86021, France.
authors: Jean-Claude
authors: JC
authors: Chomel
authors: INSERM1084, Laboratoire de Neurosciences Expérimentales et Cliniques, Poitiers, F-86021, France. l.karayan-tapon@chu-poitiers.fr.|Université de Poitiers, U1084, Poitiers, F-86022, France. l.karayan-tapon@chu-poitiers.fr.|CHU de Poitiers, Laboratoire de Cancérologie Biologique, Poitiers, F-86021, France. l.karayan-tapon@chu-poitiers.fr.
authors: Lucie
authors: L
authors: Karayan-Tapon
mesh_terms: D015153:Blotting, Western; D045744:Cell Line, Tumor; D020552:Comet Assay; D004249:DNA Damage / Q000528:radiation effects; D005434:Flow Cytometry; D005909:Glioblastoma / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000528:radiation effects; D051135:Rad51 Recombinase / Q000378:metabolism*; D011836:Radiation Tolerance / Q000502:physiology*; D046888:Tissue Array Analysis
chemical_list: C495153:RAD51 protein, human; D051135:Rad51 Recombinase
keywords: Comet assay; Glioblastoma stem cells; RAD51; Radioresistance