The radiation response of cells recovering after chronic hypoxia

Journal Article · Tue Aug 01 04:00:00 EDT 1989 · Radiation Research; (USA)

DOI:https://doi.org/10.2307/3577618· OSTI ID:5601977

Kwok, T T; Sutherland, R M ^[1]

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1. Univ. of Rochester, New York, NY (USA)

Experiments were performed to study the influence of hypoxic pretreatment on the radiation response of A431 human squamous carcinoma cells. Reaeration for 10 min after chronic hypoxia (greater than 2 h) was found to enhance the radiosensitivity of A431 cells, and the maximal effect was seen for those cells reaerated after 12 h of hypoxia. The radiosensitivity enhancement for reaerated cells after 12 h of hypoxia was maximized by 5 min after the return to aerobic conditions and reached the control level by 12 h of reaeration. This enhanced radiosensitive state was characterized by a reduced shoulder region and increased slope of the radiation dose-response curve for cells in both the exponential and plateau phases of growth. There was a slight increase in the number of G1 and decrease in the number of S and G2 + M cells for both exponential- and plateau-phase cultures following 12 h hypoxic treatment. Although growth inhibition induced by 12 h of hypoxia was seen for cells in the exponential phase, there was no cell number change in the plateau-phase culture after hypoxia. Plating efficiency (PE) of cells in both growth phases was reduced by 30% after hypoxia. Furthermore, in the exponential-phase culture, the extent of reduction in PE after hypoxia was similar among cells in different phases of the cell cycle. Although S-phase cells in exponentially growing cultures were relatively more resistant to radiation than G1 and G2 + M cells, the cell age-response pattern was the same whether the cells had been aerobic or hypoxic before reaeration and irradiation. Furthermore, the enhancement ratio associated with reaeration after 12 h of hypoxia for these three subpopulations of cells was 1.3. Our results indicate that the increase in radiosensitivity due to reaeration after chronic hypoxia is unlikely to be related to the changes of cell cycle stage and growth phase during hypoxic treatment.

• OSTI ID: 5601977
• Journal Information: Radiation Research; (USA), Journal Name: Radiation Research; (USA) Vol. 119:2; ISSN 0033-7587; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560120* -- Radiation Effects on Biochemicals
Cells
& Tissue Culture
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AEROBIC CONDITIONS
ANIMAL CELLS
ANIMALS
ANOXIA
CARCINOMAS
CELL CYCLE
CELL DIVISION
DISEASES
DOSE-RESPONSE RELATIONSHIPS
ELEMENTS
MAMMALS
MAN
NEOPLASMS
NONMETALS
OXYGEN
PRIMATES
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
SURVIVAL CURVES
TUMOR CELLS
VERTEBRATES