Interaction between ionizing radiation and supercoiled DNA within human tumor cells
- Department of Immunology, University of Birmingham (England)
The authors have analyzed DNA supercoiling within histone-free nuclei (nucleoids) using four human squamous cell carcinoma cell lines that express varying degrees of radiosensitivity. The entire DNA, arranged as negative supercoiled loops attached to the nuclear matrix, was extracted from single cells, stained with ethidium bromide, and passed through a flow cytometer recording both light scatter and red (DNA) fluorescence. Supercoiled loops of DNA from all cells were unwound with a low concentration of ethidium bromide, as seen by increased light scatter. Nucleoids from radiosensitive but not radioresistant cells resisted the transition from zero to positive supercoiling at higher concentrations of ethidium bromide. The profile of red DNA fluorescence from ethidium bromide-stained nucleoids showed that the radiosensitive cells expressed a greater variation in the total amount of ethidium bromide bound. After 12 Gy of gamma-radiation, radiosensitive cell lines produced nucleoids that contained a greater proportion of relaxed supercoiled DNA, making them larger than those from radioresistant cell lines. They suggest these observations are secondary effects resulting from an altered affinity between supercoiled looped DNA and the nuclear matrix. Combined with radiation damage, these structural alterations may lead to a more complex type of damage to repair within the radiosensitive cell lines.
- OSTI ID:
- 5459728
- Journal Information:
- Cancer Research; (United States), Journal Name: Cancer Research; (United States) Vol. 51:15; ISSN 0008-5472; ISSN CNREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Cells
& Tissue Culture
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANIMALS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CARCINOMAS
CELL CONSTITUENTS
CELL FLOW SYSTEMS
CELL NUCLEI
CONFIGURATION
DISEASES
DNA
DNA REPAIR
ELECTROMAGNETIC RADIATION
FLUORESCENCE
GAMMA RADIATION
HELICAL CONFIGURATION
IONIZING RADIATIONS
LUMINESCENCE
MAMMALS
MAN
NEOPLASMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PRIMATES
RADIATIONS
RADIOSENSITIVITY
RECOVERY
REPAIR
SCATTERING
TUMOR CELLS
VERTEBRATES