目的　观察电离辐射对 772 1细胞 (人肝癌细胞 )细胞周期和p53、Ku70和Ku80基因表达的影响。方法　以人肝癌细胞株 772 1为研究对象 ,通过克隆形成实验拟合出 772 1细胞的剂量存活曲线 ;用流式细胞技术检测 75mGyX射线照射后 772 1细胞周期变化 ;用原位杂交方法检测 772 1细胞p53、Ku70和Ku80基因在 75mGyX射线照射前、后的表达情况。结果　与对照组相比 ,75mGyX射线照射后 0 5～ 6h ,772 1细胞S期延长 (P <0 0 5)。p53、Ku70和Ku80基因的表达照射前与照射后比较差异无显著性。结论　 772 1细胞在 75mGyX射线照射后 ,未出现G1期阻滞 ,p53、Ku70和Ku80基因在照射前、后表达无明显变化 ,是由于这些基因自身存在缺陷或激活机制存在缺陷所致 Objective To observe the effect of ionizing radiation on the cell cycle and the expression of p53, Ku70 and Ku80 in 772 1 cells (human hepatoma cells). Methods Human hepatocellular carcinoma cell line 772 1 was used as a research object and the 772 1 cell survival curve was fitted by clonogenic assay. Flow cytometry was used to detect the cell cycle changes of 772 1 cells after 75 mGy X-ray irradiation. The in situ hybridization was used to detect 772 1 cells p53, Ku70 and Ku80 gene expression before and after 75mGy X-ray irradiation. Results Compared with the control group, the S phase of 772 1 cells was prolonged at 0 5 ~ 6 h after 75 mGy X - ray irradiation (P <0 05). The expression of p53, Ku70 and Ku80 genes had no significant difference before and after irradiation. Conclusion There was no G1 arrest in 772 1 cells after 75 mGy X-ray irradiation. There was no significant change in p53, Ku70 and Ku80 genes before and after irradiation, which was due to defects in their genes or defects in their activation mechanism