用染色体畸变研究AT细胞系辐射敏感性和适应性反应

Study on radiosensitivity and adaptive response of AT cells by using chromosome aberrations

目的探讨毛细血管扩张运动共济失调症(ataxiatelangiectasia,AT)细胞系的辐射敏感性和对低剂量辐射能否诱导细胞遗传学适应性反应。方法用2cGy60Coγ射线预先照射进入G1期的AT5B1VA(AT)细胞和GM0639(GM)细胞,培养6h后再照射1.0Gy或3.0Gy60Coγ射线,分析染色体畸变。结果G1期的GM细胞在预照射2cGy60Coγ射线的诱导剂量后能非常显著地降低随后照射1.0Gy或3.0Gy60Coγ射线诱发的染色体畸变率,染色体畸变的观察值非常显著地低于预期值(P<0.001),而对AT细胞则没有观察到这种现象,染色体畸变的观察值与预期值差异无统计学意义(P>0.05);另外,1.0Gy或3.0Gy60Coγ射线诱发AT细胞的各种畸变率(包括着丝粒畸变、无着丝粒畸变和染色单体型畸变)均显著地高于GM细胞(P<0.001)。结论低剂量电离辐射不能诱导AT细胞产生细胞遗传学适应性反应;AT细胞对电离辐射诱发染色体畸变高度敏感,可能是由于不能正确修复DNA双链断裂的结果。

Objective To explore radiosensitivity of AT (ataxia telangiectasia)cells and to find out whether cytogenetic adaptive response of AT cells could be induced by low-dose of ionizing radiation. Methods(AT5B1VA(AT) cells) and GM0639(GM)cells at G_1 phase were exposed to a priming dose of 2 cGy ()^(60)Co γ- rays 6 hours before irradiation with a challenge dose of 1.0 Gy or 3.0 Gy ()^(60)Co γ-rays,and then chromosome aberrations were analyzed. Results The GM cells exposed to 2 cGy ()^(60)Co γ- rays could reduce the frequencies of chromosome aberrations induced by following irradiation with 1.0 Gy or 3.0 Gy ()^(60)Co γ- rays,i.e. the observation values for chromosome aberration were significantly lower than expectation values(P<0.001). However, for AT cells this phenomenon was not observed, i.e. the observation values for chromosome aberration were similar to expectation values(P>0.05). On the other hand, various frequencies of chromosome aberrations induced with 1.0 Gy or 3.0 Gy ()^(60)Co γ-rays for AT cells were significantly higher than those for GM cells(P<0.001). Conclusion For AT cells the cytogenetic adaptive response could not be induced with low dose of ionizing radiation, but the chromosome aberrations induced by ionizing radiation for the AT cells were highly sensitive for them. The reason might be due to that the AT cells could not correctly repair DNA double- strand break.;