title: [Radiation-induced G2 phase arrest may contribute to the radioresistance of breast cancer stem cells].
abstract: OBJECTIVE
  To investigate radiation-induced cell cycle changes of human breast cancer stem cells enriched by suspension culture.
  
  
  METHODS
  The tumorigenicity of human breast cancer stem cell line MCF-7 cultured in serum-free media was confirmed in NOD/SCID mice, and the radiosensitivity of the cells was tested by clone formation assay following radiation exposure. Flow cytometry was performed to evaluate radiation-induced cell cycle changes, and the protein expression of pCDC25C (ser216) was measured by Western blotting.
  
  
  RESULTS
  After the exposure to 2 Gy radiation, the survived fraction of the cells in suspension culture and those in adherent culture was 0.856 ∓ 0.061 and 0.783 ∓ 0.097, respectively, and the cells in suspension culture showed an obviously greater capacity of tumorigenicity in NOD/SCID mice. The radiation exposure resulted in an obvious increase in the proportion of G2 phase cells from (22.03 ∓ 2.12)% to (45.83 ∓ 2.25)% and significantly increased the expression of pCDC25C (ser216).
  
  
  CONCLUSIONS
  Radiation- induced G2 phase arrest may contribute to the resistance of the breast cancer stem cells to radiotherapy.
authors.affiliation: Department of Radiation Oncology, Southern Medical University, Guangzhou 510515, China. tianyunhong1985@163.com
authors.forename: Yun-hong
authors.initials: YH
authors.lastname: Tian
authors.forename: Guo-zhu
authors.initials: GZ
authors.lastname: Xie
authors.forename: Chen
authors.initials: C
authors.lastname: Ren
authors.forename: Quan-quan
authors.initials: QQ
authors.lastname: Sun
authors.forename: Ai-min
authors.initials: AM
authors.lastname: Sun
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Ya-wei
authors.initials: YW
authors.lastname: Yuan
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology*; D018929:Cell Culture Techniques / Q000379:methods; D045744:Cell Line, Tumor / Q000528:radiation effects; D005260:Female; D059565:G2 Phase Cell Cycle Checkpoints / Q000528:radiation effects*; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D014411:Neoplastic Stem Cells / Q000473:pathology / Q000528:radiation effects*; D011836:Radiation Tolerance