Lack of uncoupling of S phase and mitosis after irradiation in p53- human lymphoblast cell lines

Frederik Wenz, Yongjia Yu, Hatsumi Nagasawa, Amy C. Imrich, Peter Keng, John B. Little

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


It has been shown that p53- human colorectal cancer cells arrest after DNA damage in a G2-like state and may then undergo DNA synthesis without intervening mitosis (Waldman et al., Nature 381, 713-716, 1996). To further clarify the role of p53 in the regulation of the G2/M-phase checkpoint, we have studied cells of three closely related human lymphoblastoid cell lines (TK6, WTK1 and TK6E6, an HPV16 E6-transfected TK6 line) with differing p53 status. The cells were irradiated with 1.5-12 Gy γ rays with or without 2 mM caffeine. There was no evidence of uncoupling of DNA synthesis and mitosis after irradiation in the p53-cell lines, WTK1 and TK6E6, suggesting that this uncoupling may not be a universal phenomenon. The apparent formation of tetraploid cells after irradiation of cells of the p53- WTK1 line was due to the occurrence of a G2-phase block in a pre-existing tetraploid population. These results support the conclusion that control of the G2/M-phase checkpoint after irradiation may differ among different cell types.

Original languageEnglish (US)
Pages (from-to)129-134
Number of pages6
JournalRadiation research
Issue number2
StatePublished - Aug 1997
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Radiation
  • Radiology Nuclear Medicine and imaging


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