G{sub 2}/M-phase arrest and release in ataxia telangiectasia and normal cells after exposure to ionizing radiation

Journal Article · Sat Oct 01 04:00:00 EDT 1994 · Radiation Research

DOI:https://doi.org/10.2307/3578563· OSTI ID:79327

Hong, J H; Gatti, R A; Huo, Y K; Chiang, C S; McBride, W H ^[1]

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1. Univ. of California School of Medicine, Los Angeles, CA (United States)

Cells from patients with ataxia telangiectasia (AT) are abnormal in their response to irradiation as judged by clonogenic survival and accumulation in G{sub 2} phase. The relationship of the results of these two assays, however, is still a matter of controversy. Flow cytometry was used to measure the distribution of cells in the phases of the cell cycle after 2 Gy irradiation in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) and SV40-transformed fibroblasts. AT cells showed increased and prolonged accumulation in G{sub 2}/M phase regardless of the cell type (lymphoblastoid or fibroblast) or complementation group (A, C or D). To test the hypothesis that prolonged accumulation of AT cells in G{sub 2} phase after irradiation was not simply a reflection of their radiosensitivity, we gave iso-survival radiation doses to SV40-transformed fibroblasts of two AT and one control cell lines. The two AT cell lines exited from the G{sub 2}/M-phase block more slowly than control cells after each dose tested. This implies that prolonged accumulation in G{sub 2}/M phase in AT cells is not directly related to radiosensitivity as measured by clonogenic survival, but that factors involved in the exit from G{sub 2} phase after irradiation may be abnormally regulated. We found that G{sub 2}-phase arrest of AT cells did not necessarily result in a fatal consequence in the first cell cycle after irradiation. Furthermore, G{sub 2}-phase arrest did not lead to detectable DNA fragmentation characteristic of apoptosis as judged by gel electrophoresis. 37 refs., 6 figs.

• Sponsoring Organization: USDOE
• OSTI ID: 79327
• Journal Information: Radiation Research, Journal Name: Radiation Research Journal Issue: 1 Vol. 140; ISSN 0033-7587; ISSN RAREAE
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOLOGICAL RADIATION EFFECTS
CELL CYCLE
CELL FLOW SYSTEMS
COMPARATIVE EVALUATIONS
ELECTROPHORESIS
FIBROBLASTS
IONIZING RADIATIONS
RADIATION DOSES
RADIOSENSITIVITY