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Recovery of CHO cells from hyperthermic potentiation to x rays: repair of DNA and chromatin

Journal Article · · Radiat. Res.; (United States)
DOI:https://doi.org/10.2307/3575563· OSTI ID:6565280
; ;
Above the critical temperature, ca. 42.5/sup 0/C, hyperthermic potentiation of Chinese hamster ovary (CHO) cells to x irradiation was accompanied by increased binding of nonhistone proteins to DNA and by reduced rates of rejoining of DNA strand breaks. These biochemical changes were reversed as the cells recovered from the hyperthermic exposures at 37/sup 0/C. If the hyperthermically treated cells were incubated at 37/sup 0/C before x irradiation, the ratio of nonhistone protein to DNA returned to normal in 12 h but the depressed rate of rejoining of DNA strand breaks and increased cell radiosensitivity remained unaltered. Cell radiosensitivity began to decrease after 12 h and recovery from hyperthermia-potentiated radiosensitivity was complete by 48 h. In the same interval, the rate of rejoining of DNA strand breaks also returned to normal. From this behavior, we conclude that the reduction in the rate of rejoining of DNA strand breaks involved changes in DNA structure which were restored only after the thermal enhancement of protein binding was reversed. These experiments provide support for the viewpoint that critical hyperthermic potentiation (i.e., above 42.5/sup 0/C for CHO cells) may have logistical advantages over subcritical hyperthermic potentiation (i.e., below 42.5/sup 0/C) in clinical situations.
Research Organization:
Colorado State Univ., Fort Collins
OSTI ID:
6565280
Journal Information:
Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 85:2; ISSN RAREA
Country of Publication:
United States
Language:
English

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Related Subjects

560121* -- Radiation Effects on Cells-- External Source-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BODY TEMPERATURE
CARBON 14 COMPOUNDS
CELL CULTURES
CHROMATIN
CONNECTIVE TISSUE CELLS
DNA
ELECTROMAGNETIC RADIATION
FIBROBLASTS
HYPERTHERMIA
IONIZING RADIATIONS
LABELLED COMPOUNDS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
RADIATIONS
RADIOINDUCTION
RADIOSENSITIVITY EFFECTS
RECOVERY
REPAIR
SOMATIC CELLS
STRAND BREAKS
SURVIVAL CURVES
SYNCHRONOUS CULTURES
SYNERGISM
X RADIATION