Comparison of response to radiation, hyperthermia and cisplatin in parental and polymerase beta knockout cells.

The role of polymerase beta in response to radiation, cisplatin and hyperthermia was examined in a pair of mouse cell lines, comprising a normal parental line and a derivative with polymerase beta knockout. Cell survival was assessed using the colony survival assay. For irradiation, there was no difference in response between the two cell lines. Treatment with cisplatin for 1 h showed a large increase in resistance in the mutant cell line. The results with hyperthermia were more complex. The mutant was more resistant to 45 degrees C heating, but was slightly more heat sensitive than the wild type at 41 degrees C. Thus, in summary, while the knockout of polymerase beta did not alter radiation sensitivity, it did increase resistance to cisplatin and induced resistance to hyperthermia at higher temperatures (45 degrees C).