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.