Repair of chromosome damage induced by X-irradiation during G/sub 2/ phase in a line of normal human fibroblasts and its malignant derivative
- Howard Univ. College of Medicine, Washington, DC
A line of normal human skin fibroblasts (KD) differed from its malignant derivative (HUT-14) in the extent of cytogenetic damage induced by X-irradiation during G/sub 2/ phase. Malignant cells had significantly more chromatid breaks and gaps after exposure to 25, 50, or 100 rad. Results from alkaline elution of cellular DNA immediately after irradiation showed that the normal and malignant cells in asynchronous population were equally sensitive to DNA single-strand breakage by X-irradiation. Caffeine or ..beta..-cytosine arabinoside (ara-C), inhibitors of DNA repair, when added directly following G/sub 2/ phase exposure, significantly increased the incidence of radiation-induced chromatid damage in the normal cells. In contrast, similar treatment of the malignant cells had little influence. Ara-C differed from caffeine in its effects; whereas both agents increased the frequency of chromatid breaks and gaps, only ara-C increased the frequency of gaps to the level observed in the irradiated malignant cells. Addition of catalase, which destroys H/sub 2/O/sub 2/, or mannitol, a scavenger of the derivative free hydroxyl radical (.OH), to the cultures of malignant cells before, during, and following irradiation significantly reduced the chromatid damage; and catalase prevented formation of chromatid gaps. The DNA damage induced by X-ray during G/sub 2/ phase in the normal KD cells was apparently repaired by a caffeine- and ara-C-sensitive mechanism(s) that was deficient or absent in their malignant derivatives.
- OSTI ID:
- 6515249
- Journal Information:
- JNCI, J. Natl. Cancer Inst.; (United States), Vol. 69:2
- Country of Publication:
- United States
- Language:
- English
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STRAND BREAKS
BIOLOGICAL REPAIR
RADIOINDUCTION
X RADIATION
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL EFFECTS
CAFFEINE
CATALASE
CELL KILLING
CYTOSINE
DNA
EXTERNAL IRRADIATION
FIBROBLASTS
IN VITRO
MAN
RADICALS
TUMOR CELLS
AMINES
ANALEPTICS
ANIMAL CELLS
ANIMALS
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BIOLOGICAL RECOVERY
CARBOXYLIC ACIDS
CENTRAL NERVOUS SYSTEM AGENTS
CONNECTIVE TISSUE CELLS
DRUGS
ELECTROMAGNETIC RADIATION
ENZYMES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
IONIZING RADIATIONS
IRRADIATION
MAMMALS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDOREDUCTASES
PEROXIDASES
PORPHYRINS
PRIMATES
PURINES
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
SOMATIC CELLS
VERTEBRATES
XANTHINES
560121* - Radiation Effects on Cells- External Source- (-1987)