title: In tumor cells regulation of DNA double strand break repair through EGF receptor involves both NHEJ and HR and is independent of p53 and K-Ras status.
abstract: OBJECTIVE
  The purpose of this study was to examine whether the epidermal growth factor receptor (EGFR) may be used as a general target to modulate DNA double strand break (DSB) repair in tumor cells.
  
  
  METHODS
  Experiments were performed with human tumor cell lines A549, H1299 and HeLa and primate cell line CV1. EGF, ARG and TGFα were used for EGFR activation, cetuximab or erlotinib for inhibition. Overall DSB repair was assessed by γH2AX/53BP1 co-immunostaining and non-homologous end-joining (NHEJ) and homologous recombination (HR) by using NHEJ and HR reporter cells; cell cycle distribution was determined by flow cytometry and protein expression by Western blot.
  
  
  RESULTS
  EGFR activation was found to stimulate overall DSB repair as well as NHEJ regardless of the ligand used. This stimulation was abolished when EGFR signaling was blocked. This regulation was found for all cell lines tested, irrespective of their p53 or K-Ras status. Stimulation and inhibition of EGFR were also found to affect HR.
  
  
  CONCLUSIONS
  Regulation of DSB repair by EGFR involves both the NHEJ and HR pathway, and appears to occur in most tumor cell lines regardless of p53 and K-Ras mutation status.
authors.affiliation: Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Myllynen
authors.forename: Thorsten
authors.initials: T
authors.lastname: Rieckmann
authors.forename: Jochen
authors.initials: J
authors.lastname: Dahm-Daphi
authors.forename: Ulla
authors.initials: U
authors.lastname: Kasten-Pisula
authors.forename: Cordula
authors.initials: C
authors.lastname: Petersen
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Dikomey
authors.forename: Malte
authors.initials: M
authors.lastname: Kriegs
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002283:Carcinoma, Bronchogenic / Q000235:genetics* / Q000532:radiotherapy; D002453:Cell Cycle / Q000235:genetics / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair / Q000235:genetics*; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts / Q000528:radiation effects; D005455:Fluorescent Antibody Technique; D016158:Genes, p53 / Q000235:genetics / Q000528:radiation effects; D011905:Genes, ras / Q000235:genetics; D000882:Haplorhini; D059765:Homologous Recombination / Q000235:genetics*; D006801:Humans; D011839:Radiation, Ionizing; D014407:Tumor Cells, Cultured / Q000528:radiation effects; D002583:Uterine Cervical Neoplasms / Q000235:genetics* / Q000532:radiotherapy
chemical_list: D066246:ErbB Receptors