[ATM expression in K562 and SiHA cell lines in relation to their cell cycle restardation after gamma-irradiation]

Ataxia telangiectasis is caused by the mutation of AT gene (ATM) and it is characterized by hypersensitivity to the radiation. In order to investigate the relationship between ATM mRNA expression of K562 and SiHA two kinds of tumor cell lines and their cell cycle restardation after gamma-irradiation, their ATM mRNA expressions were measured by semi-quantitive RT-PCR and the cells were irradiated at the dose of 6, 10 and 15 Gy of (60)Co gamma ray and the change of the apoptosis and cell cycle arrest phenomenon were observed at the time of 6, 12, 24, 48 and 60 hours after irradiation. The results showed that the ATM mRNA relative expression level of K562 cell line was 0.04, that of SiHA cell line was 0.80, the ATM transcript levels in SiHA cells were 20 times as much as that in K562. In conclusion, the G(2)/M phase restardation after irradiation was observed in both cell lines, whereas SiHA exhibited a much stronger cell cycle restardation, a self-protection function, than that of K562.