Apoptosis induced by X-irradiation of rec-myc cells is postmitotic and not predicted by the time after irradiation or behavior of sister cells.
Rat embryo cells expressing the c-myc oncogene (rec-myc) were studied by time-lapse microscopy to determine whether radiation-induced apoptosis occurred before or after mitosis. Following X-irradiation with 9.5 Gy, cells were imaged every 3 min for 6 days. Episodes of apoptotic blebbing were very consistent from cell to cell, lasting 30-60 min, followed by cessation of movement and cell death. In contrast, the time of initiation of apoptotic blebbing was unpredictable. At least 96% of the apoptotic episodes were postmitotic, after one to four cell divisions and 2-97 h after a given division. Sister cells often behaved differently from one another, with apoptosis in one sister occurring many h or several divisions after apoptosis in the other. Thus, the onset of radiation-induced apoptosis in rec-myc cells is not strictly programmed but may result from the segregation of chromosome aberrations in the postirradiation generations.
Vidair
C A
CA
Department of Radiation Oncology, University of California, San Francisco 94143, USA.
Chen
C H
CH
Ling
C C
CC
Dewey
W C
WC
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D002450:Cell Communication; D002455:Cell Division; D002460:Cell Line; D016259:Genes, myc; D006801:Humans; D007700:Kinetics; D008938:Mitosis; D051381:Rats; D013997:Time Factors; D014162:Transfection; D014965:X-Rays