Effect of caffeine on radiation-induced apoptosis in TK6 cells

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30 Scopus citations


Apoptosis has been measured in cells of the human TK6 lymphoblastoid cell line by recording the release of endonuclease-digested DNA from affected cells using flow cytometry. In asynchronously dividing cells, DNA degradation characteristic of apoptosis was first seen 12 h after irradiation as a defined DNA fluorescent peak of sub-G1-phase content, reaching a maximum of 30-50% of the population by 24-72 h. Treating cells with 2 mM caffeine either before or up to 3 h after irradiation eliminated the degradation of DNA entirely. In addition, the percentage of cells in which apoptosis could be detected microscopically decreased from 62.4 ± 0.95% to 16.7± 1.5% 72 h after caffeine treatment. Delaying caffeine treatment for 12 h after irradiation reduced DNA degradation by approximately 50% compared to cells receiving radiation alone. DNA degradation induced by serum deprivation was unaffected by caffeine treatment. These data support the contention that irradiation of TK6 cells produces a long-lived cellular signal which triggers apoptosis. Apoptosis produced by serum deprivation does not operate through the same pathway.

Original languageEnglish (US)
Pages (from-to)170-175
Number of pages6
JournalRadiation Research
Issue number2
StatePublished - 1995
Externally publishedYes

ASJC Scopus subject areas

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


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