Is low-dose hyper-radiosensitivity a measure of G2-phase cell radiosensitivity?

Research output: Contribution to journalReview articlepeer-review

55 Scopus citations


Low-dose hyper-radiosensitivity describes a phenomenon by which cells die from excessive sensitivity to small single doses of ionizing radiation below ∼20-30 cGy. This review describes experimental data that strongly imply that low-dose hyper-radiosensitivity is exclusively associated with the survival response of cells in the G2 phase of the cycle. This G2-centric concept arose when the characteristic cell survival pattern that denotes low-dose hyper-radiosensitivity was not detected in the radiation survival response of cell populations enriched in G1 or S phase cells. In contrast, an extended or exaggerated low-dose hyper-radiosensitivity response was evident from populations selected to contain only G2 phase cells by flow cytometry cell sorting. The historical data that has defined the field of low-dose hyper-radiosensitivity will be considered with respect to the radiation sensitivity of, and cell cycle checkpoints specific to, G2 phase cells. A working model of the putative mechanism of low-dose hyper-radiosensitivity will be presented within this context. The foundation of the model is a rapidly occurring dose-dependent pre-mitotic cell-cycle checkpoint that is specific to cells irradiated in the G2 phase. This early G2 phase checkpoint has been demonstrated to exhibit a dose expression profile that is comparable to the cell-survival pattern that defines low-dose hyper-radiosensitivity and is therefore a likely key regulator of the phenomenon.

Original languageEnglish (US)
Pages (from-to)197-207
Number of pages11
JournalCancer and Metastasis Reviews
Issue number3-4
StatePublished - Aug 2004
Externally publishedYes


  • cell-cycle checkpoints
  • low-dose hyper-radiosensitivity
  • radiosensitivity

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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