Discrepancies between patterns of potentially lethal damage repair in the RIF-1 tumor system in vitro and in vivo
Repair of potentially lethal damage (PLD) was studied in the RIF-1 tumor system in several different growth states in vivo and in vitro. Exponentially growing, fed plateau, and unfed plateau cells in cell culture as well as small and large subcutaneous or intramuscular tumors were investigated. Large single doses of radiation followed by variable repair times as well as graded doses of radiation to generate survival curves immediately after irradiation or after full repair were investigated. All repair-promoting conditions studied in vitro (delayed subculture, exposure of cells to depleted growth medium after irradiation) increased surviving fraction after a single dose. The D0 of the cell survival curve was also increased by these procedures. No PLD repair was observed for any tumors irradiated in vivo and maintained in the animal for varying times prior to assay in vitro. The nearly 100% cell yield obtained when this tumor is prepared as a single-cell suspension for colony formation, the representative cell sample obtained, and the constant cell yield per gram as a function of time postirradiation suggest that this discrepancy is not an artifact of the assay system. The most logical explanation of these data and information on radiocurability of this neoplasm is that PLD repair, which is so frequently demonstrated in vitro, may not be a major factor in the radioresponse of this tumor when left in situ.
- Research Organization:
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle
- OSTI ID:
- 6253301
- Journal Information:
- Radiat. Res.; (United States), Vol. 93:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DNA
BIOLOGICAL REPAIR
TUMOR CELLS
BIOLOGICAL RADIATION EFFECTS
COMPARATIVE EVALUATIONS
EXTERNAL IRRADIATION
IN VITRO
IN VIVO
RADIATION DOSES
SURVIVAL CURVES
ANIMAL CELLS
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
DOSES
IRRADIATION
NUCLEIC ACIDS
ORGANIC COMPOUNDS
RADIATION EFFECTS
RECOVERY
REPAIR
560152* - Radiation Effects on Animals- Animals
560121 - Radiation Effects on Cells- External Source- (-1987)