title: Elevated expression of artemis in human fibroblast cells is associated with cellular radiosensitivity and increased apoptosis.
abstract: BACKGROUND
  The objective of this study was to determine the molecular mechanisms responsible for cellular radiosensitivity in two human fibroblast cell lines 84BR and 175BR derived from two cancer patients.
  
  
  METHODS
  Clonogenic assays were performed following exposure to increasing doses of gamma radiation to confirm radiosensitivity. γ-H2AX foci assays were used to determine the efficiency of DNA double-strand break (DSB) repair in cells. Quantitative PCR (Q-PCR) established the expression levels of key DNA DSB repair genes. Imaging flow cytometry using annexin V-FITC was used to compare artemis expression and apoptosis in cells.
  
  
  RESULTS
  Clonogenic cellular hypersensitivity in the 84BR and 175BR cell lines was associated with a defect in DNA DSB repair measured by the γ-H2AX foci assay. The Q-PCR analysis and imaging flow cytometry revealed a two-fold overexpression of the artemis DNA repair gene, which was associated with an increased level of apoptosis in the cells before and after radiation exposure. Overexpression of normal artemis protein in a normal immortalised fibroblast cell line NB1-Tert resulted in increased radiosensitivity and apoptosis.
  
  
  CONCLUSIONS
  We conclude that elevated expression of artemis is associated with higher levels of DNA DSB, radiosensitivity and elevated apoptosis in two radio-hypersensitive cell lines. These data reveal a potentially novel mechanism responsible for radiosensitivity and show that increased artemis expression in cells can result in either radiation resistance or enhanced sensitivity.
authors.affiliation: Brunel Institute of Cancer Genetics and Pharmacogenomics, Division of Biosciences, Brunel University, Uxbridge UB8 3PH, UK.
authors.forename: G
authors.initials: G
authors.lastname: Ulus-Senguloglu
authors.forename: C F
authors.initials: CF
authors.lastname: Arlett
authors.forename: P N
authors.initials: PN
authors.lastname: Plowman
authors.forename: J
authors.initials: J
authors.lastname: Parnell
authors.forename: N
authors.initials: N
authors.lastname: Patel
authors.forename: E C
authors.initials: EC
authors.lastname: Bourton
authors.forename: C N
authors.initials: CN
authors.lastname: Parris
mesh_terms: D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology / Q000528:radiation effects; D002999:Clone Cells / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair / Q000235:genetics; D004268:DNA-Binding Proteins; D004307:Dose-Response Relationship, Radiation; D004720:Endonucleases; D005260:Female; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology / Q000528:radiation effects*; D006801:Humans; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D011836:Radiation Tolerance; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C426344:DCLRE1C protein, human; D004720:Endonucleases