不同p53状态的肝癌细胞系DNA损伤修复能力的比较

目的 观察不同p53状态的肝癌细胞在DNA损伤因素存在下，探讨p53在肝细胞癌发生过程中的作用。方法 选用内源性表达野生型p53、突变型p53、p53全基因缺失的HepG2、PLC／PRF／5、Hep3B肝癌细胞系，将含有p53结合序列的CAT报告基因质粒分别转染各细胞，通过ELISA方法检测报告基因CAT活化情况，观察p53功能状态；用细胞生长曲线比较不同p53状态的细胞生长速度的差异；给予一定剂量的紫外线照射，检测各细胞程序外DNA损伤修复(UDS)能力；观察紫外线照射后细胞克隆形成情况，反映不同细胞系在紫外线照射后细胞存活率的不同。结果 报告基因CAT在HepG2细胞表达最强，而在PLC／PRF／5、Hep3B肝癌细胞均处于较低水平，说明HepG2细胞具有功能性的p53表达；HepG2细胞生长速度明显慢于其他两种细胞；紫外线照射后，HepG2具有较好的DNA损伤修复能力以及较高的细胞生存率。结论 野生型p53具有抑制肝癌细胞生长、保持细胞良好的DNA损伤修复的功能。

Comparison of DNA repair capacity in hepatoma cell lines with different p53 activity

ObjectiveTo examine the association of p53 and DNA repair capacity in hepatoma cell lines. MethodsThe hepatoma cells of HepG2, Hep3B and PLC /PRF /5 were transfected by phosphate calcium precipitation method with reporter plasmid PG13-CAT, which contains the chloramphenicol acetyltransferase gene located at downstream of 13 repeats of p53 binding sequences. CAT activity was assayed by ELISA to indicate p53 function. Cell proliferation rate was observed by growth curve. DNA damage repair capacity was determined by unscheduled DNA synthesis(UDS) and cell clone forming after UV-irradiation in the three cell lines. ResultsReporter gene CAT could express well in HepG2 cell but not in either PLC /PRF /5 or Hep3B. The growth curve suggested HepG2 had a slowest proliferating rate. After UV-irradiation, HepG2 was more competent to repair damaged DNA and had a higher survival rate. ConclusionThis study suggests wild type p53 may play a role to inhibit hepatoma cell growth and keep cells in good condition to repair damaged DNA.