Action of caffeine on x-irradiated HeLa cells. IV. Progression delays and enhanced cell killing at high caffeine concentrations
The response of x-irradiated and unirradiated HeLa S3 cells to treatment with caffeine at concentrations between 1 and 10 nM has been examined with respect to both delay in progression through the cell generation cycle and enhancement of the expression of potentially lethal x-ray damage. Progression is delayed in a concentration-dependent fashion: the generation time is doubled at about 4 mM. The duration of G/sub 1/ is lengthened, and the rate of DNA synthesis is reduced, although the kinetics are different in the two phases; the rate of DNA synthesis is usually unaffected at 1 or 2 mM, while there is no concentration threshold for the slowing of progression through G/sub 1/. Progression through G/sub 2/ appears to be unaffected by concentrations up to at least 10 mM. Killing of irradiated cells in G/sub 2/ is somewhat greater after treatment with the higher caffeine concentrations than reported previously for 1 mM. Moreover, an additional mode of killing is observed in irradiated G/sub 1/ cells which had been found previously to be only slightly affected by 1 mM caffeine; they suffer extensive killing at concentrations above 5 mM. The time-survival curves for irradiated, caffeine-treated G/sub 1/ and G/sub 2/ cells have characteristically different shapes. The dose-survival curves for cells treated with the higher caffeine concentrations display steeper terminal slopes and narrower shoulders.
- Research Organization:
- Washington Univ., St. Louis, MO
- OSTI ID:
- 5099738
- Journal Information:
- Radiat. Res.; (United States), Vol. 82:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CAFFEINE
RADIOSENSITIVITY EFFECTS
HELA CELLS
BIOLOGICAL RADIATION EFFECTS
BIOSYNTHESIS
CELL CYCLE
CELL KILLING
CELL PROLIFERATION
DNA
DOSE-RESPONSE RELATIONSHIPS
EXPERIMENTAL DATA
SURVIVAL CURVES
X RADIATION
BIOLOGICAL EFFECTS
DATA
DRUGS
ELECTROMAGNETIC RADIATION
HETEROCYCLIC COMPOUNDS
INFORMATION
IONIZING RADIATIONS
NUCLEIC ACIDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PURINES
RADIATION EFFECTS
RADIATIONS
SYNTHESIS
XANTHINES
560121* - Radiation Effects on Cells- External Source- (-1987)