Radiosensitive Xrs-5 and Parental CHO Cells Show Identical DNA Neutral Filter Elution Dose-response: Implications for a Relationship between Cell Radiosensitivity and Induction of DNA Double-strand Breaks

Summary The purpose of this work was to investigate a possible correlation between DNA elution dose-response and cell radiosensitivity. For this purpose neutral (pH 9·6) DNA filter elution dose-response curves were measured with radiosensitive xrs-5 and the parental Chinese hamster ovary (CHO) cells in the logarithmic and plateau phase of growth. No difference was observed between the two cell types in the DNA elution dose-response curves either in logarithmic or plateau phase, despite the dramatic differences in cell radiosensitivity. This observation indicates that the shape of the DNA elution dose-response curve and the shape of the cell survival curve are not causally related. It is proposed that the shoulder observed in the DNA elution dose-response curve reflects either partial release of DNA from chromatin, or cell cycle-specific alterations in the physicochemical properties of the DNA.