title: Low production of reactive oxygen species and high DNA repair: mechanism of radioresistance of prostate cancer stem cells.
abstract: BACKGROUND
  Cancer stem cells (CSCs) are resistant to radiotherapy and are responsible for tumor recurrence of various malignant tumors, including prostate cancer.
  
  
  METHODS
  In order to define the radioresistance mechanism of prostate CSCs, their proliferative activity, cell cycle distribution, expression of CD133 stem cell marker, reactive oxygen species (ROS) production, and DNA repair efficiency were examined using prostatospheres and adherent LNCaP cells as a model of prostate CSC and bulk model of differentiated cells, respectively.
  
  
  RESULTS
  Compared to adherent cells, prostatospheres exhibited greater number of low-to-intermediate ROS-producing cells and CD133-positive cells. Prostatospheres showed higher expression of DNA repair proteins after ionizing radiation (IR).
  
  
  CONCLUSIONS
  Low vulnerability to ROS-induced cellular damage and the efficient repair of IR-induced DNA injury may explain the radioresistance of prostate CSCs. Therefore, increasing ROS-induced cytotoxicity and inhibition of DNA repair in prostate CSCs may help achieve complete eradication of prostate CSCs by radiotherapy.
authors.affiliation: Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-2dong, Songpa-gu, Seoul, 138-736, Republic of Korea. yongcho@amc.seoul.kr.
authors.forename: Young Seok
authors.initials: YS
authors.lastname: Kim
authors.forename: Mun Jung
authors.initials: MJ
authors.lastname: Kang
authors.forename: Yong Mee
authors.initials: YM
authors.lastname: Cho
mesh_terms: D034961:Antigens, Nuclear / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D048430:Cell Shape; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D000072200:Ku Autoantigen; D008297:Male; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000528:radiation effects*; D011471:Prostatic Neoplasms; D011836:Radiation Tolerance; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018874:Spheroids, Cellular / Q000378:metabolism
chemical_list: D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D017382:Reactive Oxygen Species; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen
keywords: DNA repair; Prostatic neoplasms; neoplastic stem cells; radioresistance; radiotherapy; reactive oxygen species