| Autor: |
H., Macphail S., P., BanÁth J., Y., Yu T., M., Chu E. H., H., Lambur, L., Olive P. |
| Předmět: |
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| Zdroj: |
International Journal of Radiation Biology; May2003, Vol. 79 Issue 5, p351-359, 9p, 14 Black and White Photographs, 1 Chart, 23 Graphs |
| Abstrakt: |
Purpose : Exposure to ionizing radiation results in phosphorylation of histone H2AX ( γ H2AX) at sites of DNA double-strand breaks. To determine the relationship between γ H2AX formation and radiosensitivity, the rate of formation and loss of γ H2AX were examined in several cultured cell lines following exposure to 250 kV X-rays. Materials and methods : Flow and image cytometry were both performed using a mouse monoclonal antibody against γ H2AX. Immunoblotting was used to confirm cell line-dependent differences in antibody staining. Cell lines examined included V79 and CHO-K1 hamster cells, the human tumour cell lines SiHa, WiDr, DU145, WIL-2NS, HT144, HCC1937 and U87, and the normal cell strain HFL1. Radiosensitivity was measured using a standard clonogenic assay. Results : Using flow cytometry, γ H2AX formation was detected 1 h after doses as low as 20 cGy. Peak levels of γ H2AX were observed within 15-30 min after irradiation and both the rate of radiation-induced γ H2AX formation and loss were cell type dependent. Maximum levels of γ H2AX formation were lower for HT144 cells mutant for the ataxia telangiectasia gene. Half-times of loss after irradiation ranged from 1.6 to 7.2 h and were associated with a decrease in the total number of foci per cell. The half-time of loss of γ H2AX was correlated with clonogenic survival for 10 cell lines ( r 2 =0.66). Conclusions : γ H2AX can be detected with excellent sensitivity using both flow and image analysis. The rate of γ H2AX loss may be an important factor in the response of cells to ionizing radiation, with more rapid loss and less retention associated with more radioresistant cell lines. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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