A radiation-induced acute apoptosis involving TP53 and BAX precedes the delayed apoptosis and neoplastic transformation of CGL1 human hybrid cells

Marc Mendonca, Brendan M. Mayhugh, Berry McDowell, Helen Chin-Sinex, Martin L. Smith, Joseph Dynlacht, Dan Spandau, Davina A. Lewis

Research output: Contribution to journalArticle

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Abstract

Exposing CGL1 (HeLa x fibroblast) hybrid cells to 7 Gy of X rays results in the onset of a delayed apoptosis in the progeny of the cells 10 to 12 cell divisions postirradiation that correlates with the emergence of neoplastically transformed foci. The delayed apoptosis begins around day 8 postirradiation and lasts for 11 days. We now demonstrate that the delayed apoptosis is also characterized by the appearance of ∼50-kb apoptotic DNA fragments and caspase 3 activation postirradiation. In addition, we confirm that stabilization of TP53 and transactivation of pro-apoptosis BAX also occurs during the delayed apoptosis and show that anti-apoptosis BCL-XL is down-regulated. To test whether the delayed apoptosis was due to a nonfunctional acute TP53 damage response in CGL1 cells, studies of acute apoptosis were completed. After irradiation, CGL1 cells underwent an acute wave of apoptosis that involves TP53 stabilization, transactivation of BAX gene expression, and a rapid caspase activation that ends by 96 h postirradiation. In addition, the acute onset of apoptosis correlates with transactivation of a standard wild-type TP53-responsive reporter (pG13-CAT) in CGL1 cells after radiation exposure. We propose that the onset of the delayed apoptosis is not the result of a nonfunctional acute TP53 damage response pathway but rather is a consequence of X-ray-induced genomic instability arising in the distant progeny of the irradiated cells.

Original languageEnglish
Pages (from-to)614-622
Number of pages9
JournalRadiation Research
Volume163
Issue number6
DOIs
StatePublished - Jun 2005

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Hybrid Cells
apoptosis
Radiation
Apoptosis
radiation
cells
transcriptional activation
Transcriptional Activation
progeny
X-radiation
stabilization
X-Rays
activation
damage
cell division
Genomic Instability
gene expression
caspases
fibroblasts
radiation dosage

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Radiology Nuclear Medicine and imaging
  • Biophysics
  • Radiation

Cite this

A radiation-induced acute apoptosis involving TP53 and BAX precedes the delayed apoptosis and neoplastic transformation of CGL1 human hybrid cells. / Mendonca, Marc; Mayhugh, Brendan M.; McDowell, Berry; Chin-Sinex, Helen; Smith, Martin L.; Dynlacht, Joseph; Spandau, Dan; Lewis, Davina A.

In: Radiation Research, Vol. 163, No. 6, 06.2005, p. 614-622.

Research output: Contribution to journalArticle

Mendonca, Marc ; Mayhugh, Brendan M. ; McDowell, Berry ; Chin-Sinex, Helen ; Smith, Martin L. ; Dynlacht, Joseph ; Spandau, Dan ; Lewis, Davina A. / A radiation-induced acute apoptosis involving TP53 and BAX precedes the delayed apoptosis and neoplastic transformation of CGL1 human hybrid cells. In: Radiation Research. 2005 ; Vol. 163, No. 6. pp. 614-622.
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