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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 investigate the radiosensitivity of ataxiate langiectasia (AT) cell lines and whether cytogenetic adaptive response to low dose radiation can be induced. Methods AT5B1VA (AT) cells and GM0639 (GM) cells were pre-irradiated with 2cGy60Coγ ray and then were irradiated with 1.0Gy or 3.0Gy60Coγ ray after 6h of culture. Chromosome aberrations were analyzed. Results GM cells in G1 phase significantly reduced the chromosomal aberration induced by 1.0Gy or 3.0Gy60Coγ-ray irradiation after preincubation with 2cGy60Coγ ray, and the observed value of chromosome aberration was significantly lower than the expected value (P <0.001 ), But this phenomenon was not observed in AT cells. There was no significant difference between the observed value of chromosome aberration and the expected value (P> 0.05). In addition, the aberration rate of AT cells induced by 1.0Gy or 3.0Gy60Coγ ray Including centromere aberrations, centromere aberration and chromatid aberrations) were significantly higher than GM cells (P <0.001). Conclusion Low-dose ionizing radiation can not induce cytogenetic adaptive responses in AT cells. AT cells are highly sensitive to ionizing radiation-induced chromosome aberrations, which may be due to the inability to correctly repair DNA double-strand breaks.