Background & objective: Ataxia telangiectasia is caused by ataxia telangiectasia mutant(ATM) gene and it is characterized by hypersensitivity to the radiation. So the ATM expression should be related to the radiation sensitivity. This study was designed to investigate the relationship between ATM expression in two kinds of tumor cell lines and their cell cycle arrest after irradiation of ionization radiation to explore their self-protection function.
Methods: ATM mRNA and protein expression of HL-60 and SiHA cell lines were measured by semi-quantitive reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry. The cells were irradiated at the dose of 6, 10, and 15 Gy by (60)Co and the change of apoptosis and cell cycle arrest phenomenon at the time of 6, 12, 24, 48, and 60 hours after the radiation were observed.
Results: The ATM mean protein fluorescent intensity of HL-60 and SiHA cells were 14.11+/-2.38 and 27.74+/-1.16,respectively. The ATM protein abundance in SiHA was two times more than that in HL-60,and consistent with this, the ATM RNA relative expression of HL-60 and SiHA cells were 0.09 and 0.80, respectively. The ATM transcript levels in SiHA are 9 times more than that in HL-60. The G(2)/M phase arrest after the radiation was observed in both cell lines, whereas SiHA exhibits a much strong cell cycle arrest than HL-60.
Conclusion: The cell cycle arrest of HL-60 and SiHA cell lines to the irradiation corresponds to their ATM expression levels. The lower ATM expression, the weaker response for cell cycle arrest induced by radiation.