Correlation between polymerase beta activity and thermal radiosensitization in Chinese hamster ovary cells

The enhancement of the radiosensitivity of CHO cells was determined for various single and multiple heat treatments followed by X-irradiation at 0 degrees C to prevent repair during exposure. Furthermore, the reduction in the activity of DNA polymerase beta was determined after the same heat treatments. The thermal enhancement ratios for cell killing, calculated on the 10% survival level for the various experimental conditions, showed a clear-cut correlation with the activity of DNA polymerase beta measured by the end of the various heat treatments. These results indicate that the thermal radiosensitization observed in many biological systems might be associated with the transient loss of polymerase beta activity.