Repair of chromosome damage induced by X-irradiation during G2 phase in a line of normal human fibroblasts and its malignant derivative
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 G2 phase. Malignant cells had significantly more chromatid breaks and gaps after exposure to 25, 50, or 100 rad. The gaps may represent single-strand breaks. 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 G2 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, 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 G2 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.
- Research Organization:
- Department of Pathology, Howard University College of Medicine, Washington, DC
- OSTI ID:
- 6654578
- Journal Information:
- J. Natl. Cancer Inst.; (United States), Vol. 69:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
CHROMOSOMES
BIOLOGICAL RADIATION EFFECTS
FIBROBLASTS
RADIOSENSITIVITY
BIOLOGICAL REPAIR
CELL CYCLE
CHROMOSOMAL ABERRATIONS
DNA
RADIATION DOSES
RADIOSENSITIVITY EFFECTS
RESPONSE MODIFYING FACTORS
X RADIATION
ANIMAL CELLS
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
CONNECTIVE TISSUE CELLS
DOSES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
MUTATIONS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
SOMATIC CELLS
560121* - Radiation Effects on Cells- External Source- (-1987)
550603 - Medicine- External Radiation in Therapy- (1980-)