Effect of combined treatment with radiation and low dose etoposide on cell survival

N. Shigematsu, T. Kawata, N. Ihara, O. Kawaguchi, S. Kutsuki, R. Ishibashi, A. Kubo, H. Ito

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Background: To improve the radiotherapy results, we evaluated etoposide as an effective radiosensitizer by using cultured cell-lines. Materials and Methods: Four cell lines having different doubling times (DT) were used: V79 (Chinese hamster fibroblasts, DT=9 hours), (1), T24 (human bladder cancer, DT=19 hours) (2), MDA-MB231 (human breast cancer, DT=25-30 hours) (3) and RMG1 (human ovarian cancer, DT=50 hours) (4). Cell survival was determined by colony assay and cell cycle analysis was performed by flow-cytometry. Results; The survival curves showed RMG1 to be the most radiosensitive, followed by MDA-MB231, T24, and V79. V79 was most chemosensitive to etoposide, followed by T24, MDA-MB231 and RMG1. Neither 24-hours exposure to etoposide (≤0.05 μg/ml) or 0.5-h exposure (≤1.0 μg/ml) had any cell killing effect on any of the cell lines used. When the cells were irradiated after exposure to 1 μg/ml of etoposide for 0.5 hours, no radiosensitization was observed in any of the cell lines except V79. Enhanced radiosensitivity was observed in V79 and T24 cells (which have a relatively short DT) when they were incubated with 0.05 μg/ml etoposide for 24 hours but no enhanced effect was seen in MDA-MB231 or RMG1 cells (which have a relatively long DT). Conclusion: It is suggested that a combination of radiation and etoposide may be useful in the treatment of rapidly growing cancer.

Original languageEnglish
Pages (from-to)325-328
Number of pages4
JournalAnticancer research
Issue number1 A
Publication statusPublished - 2001


  • Etoposide
  • Radiosensitization

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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