Radiation-induced apoptosis: Effects of cell age and dose fractionation Journal Article


Authors: Ling, C. C.; Guo, M.; Chen, C. H.; Deloherey, T.
Article Title: Radiation-induced apoptosis: Effects of cell age and dose fractionation
Abstract: The cell cycle dependence of radiation-induced apoptosis was measured using mitotically synchronized REC:myc(chl) and Ratl:mycb cells. Cells in S and G2 phases were more susceptible; the apoptotic fraction was about 0.7-0.8 as compared to about 0.4 for G1 cells at a dose of 10 Gy. Two-dimensional cytofluorimetric analysis of cells, pulsed-labeled with bromodeoxyuridine and then irradiated with 10 Gy, showed both G, and G2 blocks (6-8 h) for REC:myc(chl) cells but only G2 block for Rati: mycb cells. Consistent with these results, wild-type p53 and WAF1 (or p21), known to play a role in G, delay, was induced by radiation in REC:myc(chl) but not in Ratl:mycb cells. The cell cycle dependence of radiation-induced apoptosis and the absence of a G, block for Ratl:mycb cells led to the prediction and observation of the novel “Inverse split-dose effect,” i.e., a radiation dose given in two equal halves separated by a few hours yielded a higher level of apoptosis relative to that resulting from the same total dose given all at once. This effect is due to cell cycle progression from G1 to the more sensitive S-G2 phase during the interval between the split doses. In contrast, the inverse split-dose effect for apoptosis is absent for REC:myc(chl), due presumably to the radiation-induced G, delay. Parallel split-dose experiments, but using clonogenic survival as end points, show recovery for REC:myc(chl) cells but not for Ratl:mycb cells, reflecting the influence of split-dose, radiation-induced apoptosis. © 1995, American Association for Cancer Research. All rights reserved.
Keywords: nonhuman; radiation dose; animal cell; animal; cells, cultured; cell cycle; cell cycle s phase; apoptosis; cell population; radiation injury; protein p53; radiation dosage; radiation dose fractionation; genes, myc; cell damage; rat; irradiation; radiosensitivity; cell cycle g2 phase; rats; cyclins; cell aging; etiology; cell kinetics; cytofluorometry; priority journal; article; support, u.s. gov't, p.h.s.
Journal Title: Cancer Research
Volume: 55
Issue: 22
ISSN: 0008-5472
Publisher: American Association for Cancer Research  
Date Published: 1995-11-15
Start Page: 5207
End Page: 5212
Language: English
PUBMED: 7585576
PROVIDER: scopus
DOI/URL:
Notes: Article -- Export Date: 28 August 2018 -- Source: Scopus
Citation Impact
MSK Authors
  1. C Clifton Ling
    331 Ling
  2. Min Guo
    11 Guo
  3. Chang Hu Chen
    15 Chen