不同肝癌细胞系中P53/P21/MDM2表达初步观察

选用P53状态不同的Hep3B、PLC／PRF／5、HCC—9204、HepG2、HepG2215细胞，通过Western印迹分析观察各细胞P53蛋白以及P53下游基因p21、mdm2蛋白表达情况；将报告基因PG13-CAT转染细胞，通过观察CAT酶表达水平反映各细胞中P53的反式活化功能；P21—LUC质粒细胞内转染，比较不同细胞中P53对P21启动子的活化情况。结果显示，PLC／PRF／5细胞中P53蛋白高表达、低功能，但P21蛋白以及报告基因P21—LUC转染细胞后荧光素酶均具有较高水平表达；Hep3B细胞中P53蛋白无表达、无功能，P21蛋白低表达，MDM2蛋白表达相对较高；HCC—9204细胞具有较高MDM2表达，P53蛋白表达及功能均较低，P21亦呈低表达；HepG2215较HepG2细胞具有较高的P53、P21蛋白表达，P53活化报告基因的活性也较强。结果提示，肝癌细胞中P53活性与其表达水平、存在状态有关；某些细胞中P21的活化表达存在不依赖于P53的途径；MDM2与P53的表达具有负性相关倾向。

Preliminary observation of P53/P21/MDM2 expression in different hepatoma cell lines

HepSB,PLC/PRF/5,HCC-9204,HepG2,HepG2215 cells with different p53 states were used to detect the expressions of p53, p2l and mdm2 by Western blotting. Reporter plasmids PG13-CAT and P21-LUC were transfected respectively by phosphate calcium precipitation or lipofectamine to further detect P53 activity and their effect on p21 promoter in each cell line. Results showed that P53 in PLC/PRF/5 cell line had high expression but its effect on PG13-CAT was weak; P21 and transfected reporter(P21-LUC )expression were moderately high in this cell line. In Hep3B cell line, P53 could neither express nor activate p21-promotor and P21 expression was also low. Nevertheless, MDM2 had comparatively high expression. MDM2 in HCC-9204 had the highest expression among all the 5 cell lines, but P53 expression and function were low. P53 expression or function and P21 expression were higher in HepG2215 than in HepG2 cell, but MDM2 expression level was just the opposite. It is indicated that P53 activity in hepatoma cells is related to its expression degree and its type. There probably exists a P53-independent pathway which promotes P21 expression in some cell lines. The results of MDM2 and P53 expression show that these 2 kinds proteins have the incline of negative correlation.