RRC ID 65764
Author Terashima S, Hosokawa Y, Tsuruga E, Mariya Y, Nakamura T.
Title Impact of time interval and dose rate on cell survival following low-dose fractionated exposures.
Journal J Radiat Res
Abstract Enhanced cell lethality, also known as hyper-radiosensitivity, has been reported at low doses of radiation (≤0.5 Gy) in various cell lines, and is expected to be an effective cancer therapy. We conducted this study to examine the impact of time interval and dose rate of low-dose fractionated exposures with a short time interval. We evaluated the cell-survival rates of V79 and A549 cells using clonogenic assays. We performed fractionated exposures in unit doses of 0.25, 0.5, 1.0 and 2.0 Gy. We exposed the cells to 2 Gy of X-rays (i) at dose-rates of 1.0, 1.5 and 2.0 Gy/min at 1-min intervals and (ii) at a dose-rate of 2.0 Gy/min at 10-s, 1-min and 3-min intervals by fractionated exposures. Apoptosis and cell cycle analyses were also evaluated in the fractionated exposures (unit dose 0.25 Gy) and compared with single exposures by using flow cytometry. Both cell-type survival rates with fractionated exposures (unit dose 0.25 Gy) with short time intervals were markedly lower than those for single exposures delivering the same dose. When the dose rates were lower, the cytotoxic effect decreased compared with exposure to a dose-rate of 2.0 Gy/min. On the other hand, levels of apoptosis and cell cycle distribution were not significantly different between low-dose fractionated exposures and single exposures in either cell line. These results indicate that a stronger cytotoxic effect was induced with low-dose fractionated exposures with a short time interval for a given dose due to the hyper-radiosensitivity phenomenon, suggesting that dose rates are important for effective low-dose fractionated exposures.
Volume 58(6)
Pages 782-790
Published 2017-11-1
DOI 10.1093/jrr/rrx025
PII 3862721
PMID 28595296
PMC PMC5710595
MeSH Animals Apoptosis / radiation effects Cell Cycle / radiation effects Cell Line Cell Survival / radiation effects Clone Cells Dose Fractionation, Radiation* Dose-Response Relationship, Radiation Humans Time Factors
IF 1.95
Human and Animal Cells A549