Hyperthermia radiosensitization in human glioma cells comparison of recovery of polymerase activity, survival, and potentially lethal damage repair
- Ottawa Regional Cancer Centre, Ontario (Canada)
DNA polymerase inactivation is compared to thermal radiosensitization and inhibition of damage recovery in human glioma cells. Two human glioma cell lines (U87MG and U373MG) were exposed to hyperthermia and irradiation. Hyperthermia was given at 43[degrees]C and 45[degrees]C and DNA polymerase [alpha] + [delta] + [epsilon] and [beta] activities were measured. Hyperthermia was given at various times before irradiation and the degree of radiosensitization and polymerase activity was assessed at various times after heating. In addition the ability of cells to undergo repair of potentially lethal radiation damage was assessed for cells irradiated at various times after heating. Polymerase [alpha] + [delta] + [epsilon] and polymerase [beta] both recovered after heating but polymerase [beta] was faster and was complete in U373MG but not in the U87MG cell lines after 48 h incubation after heating (45[degrees]C, 60 min). Incubation, between hyperthermia and irradiation resulted in a loss of radiosensitization and a loss of inhibition of repair of potentially lethal damage. These changes correlated well with recovery of polymerase [beta] but not with polymerase [alpha] + [delta] + [epsilon]. The correlation of polymerase [beta] activity and thermoradiosensitization and its recovery indicate that polymerase [beta] may be one of the mechanisms involved in thermoradiosensitization. 35 refs., 7 figs.
- OSTI ID:
- 6820744
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics; (United States), Vol. 29:1; ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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