title: Effect of X-rays on expression of caspase-3 and p53 in EL-4 cells and its biological implications.
abstract: OBJECTIVE
  To investigate the effect of X-rays on expression of caspase-3 and p53 protein in EL-4 cells and its implications in induction of apoptosis and polyploid cells.
  
  
  METHODS
  Mouse lymphoma cell line (EL-4 cells) was used. Fluorescent staining and flow cytometry analysis were employed for measurement of protein expression, apoptosis, cell cycle, and polyploid cells.
  
  
  RESULTS
  The expression of caspase-3 protein increased significantly at 8 h and 12 h, compared with that of sham-irradiated control (P<0.05, respectively) and the expression of p53 protein increased significantly at 2, 4, 8, 12, and 24 h, compared with that of sham-irradiated control (P<0.05-P<0.01) in EL-4 cells after 4.0 Gy X-irradiation. Apoptosis of EL-4 cells was increased significantly at 2, 4, 8, 12, 24, 48, and 72 h after 4.0 Gy exposure, compared with that of sham-irradiated control (P<0.05-P<0.001). G2 phase cells were increased significantly at 4, 8, 12, 24, 48, and 72 h (P<0.05-P<0.001). However, no marked change in the number of 8 C polyploid cells was found from 2 to 48 h after 4.0 Gy exposure.
  
  
  CONCLUSIONS
  The expressions of caspase-3 and p53 protein in EL-4 cells are induced by X-rays, which might play an important role in the induction of apoptosis, and the molecular pathway for polyploid formation might be p53-independent.
authors.affiliation: Department of Radiation Biology, School of Public Health, Jilin University, Changchun 130021, Jilin, China. jugz@mail.jlu.edu.cn
authors.forename: Gui-Zhi
authors.initials: GZ
authors.lastname: Ju
authors.forename: Bo
authors.initials: B
authors.lastname: Shen
authors.forename: Shi-Long
authors.initials: SL
authors.lastname: Sun
authors.forename: Feng-Qin
authors.initials: FQ
authors.lastname: Yan
authors.forename: Shi-Bo
authors.initials: SB
authors.lastname: Fu
mesh_terms: D000818:Animals; D053148:Caspase 3 / Q000378:metabolism / Q000528:radiation effects*; D020169:Caspases / Q000378:metabolism / Q000528:radiation effects*; D053471:Caspases, Initiator; D045744:Cell Line, Tumor; D051379:Mice; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism / Q000528:radiation effects*; D014965:X-Rays
chemical_list: D016159:Tumor Suppressor Protein p53; C101136:Casp4 protein, mouse; D053148:Caspase 3; D020169:Caspases; D053471:Caspases, Initiator