DNA conformation of Chinese hamster V79 cells and sensitivity to ionizing radiation

Journal Article · Tue Jul 01 04:00:00 EDT 1986 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3576855· OSTI ID:5015751

Olive, P L; Hilton, J; Durand, R E

Chinese hamster V79 cells grown for 20 h in suspension culture form small clusters of cells (spheroids) which are more resistant to killing by ionizing radiation than V79 cells grown as monolayers. This resistance appears to be due to the greater capacity of cells grown in contact to repair radiation damage. Attempts to relate this ''contact effect'' to differences in DNA susceptibility or DNA repair capacity have provided conflicting results. Two techniques, alkaline sucrose gradient sedimentation and alkaline elution, show no difference in the amounts of radiation-induced DNA single-strand breakage or its repair between suspension or monolayer cells. However, using the alkali-unwinding assay, the rate of DNA unwinding is much slower for suspension cells than for monolayer cells. Interestingly, a decrease in salt concentration or in pH of the unwinding solution eliminates these differences in DNA unwinding kinetics. A fourth assay, sedimentation of nucleoids on neutral sucrose gradients, also shows a significant decrease in radiation damage produced in suspension compared to monolayer cultures. It is believed that this assay measures differences in DNA conformation (supercoiling) as well as differences in DNA strand breakage. We conclude from these four assays that the same number of DNA strand breaks/Gy is produced in monolayer and spheroid cells. However, changes in DNA conformation or packaging occur when cells are grown as spheroids, and these changes are responsible for reducing DNA damage by ionizing radiation.

• Research Organization: Univ. of British Columbia, Vancouver
• OSTI ID: 5015751
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 1; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560121* -- Radiation Effects on Cells-- External Source-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
CELL CULTURES
CHO CELLS
CULTIVATION TECHNIQUES
DNA
IN VITRO
NUCLEIC ACIDS
ORGANIC COMPOUNDS
RADIOSENSITIVITY
RESPONSE MODIFYING FACTORS
STRAND BREAKS