目的研究乙型肝炎病毒(HBV)启动子(含增强子)调控下的增强型绿色荧光蛋白(EGFP) 报告基因在肝癌细胞中的表达。方法用聚合酶链反应(PCR)技术分别扩增出HBV的4个启动子,载入 T载体,测序后插入到含EGFP报告基因的质粒pEGFP-1,构建出HBV不同启动子调控的EGFP基因表达载体,经酶切、测序鉴定各重组体。采用脂质体介导法将4种构建好的载体转染肝癌细胞株H e p G 2,用倒置荧光显微镜观察各重组体转染细胞中EGFP的表达。结果各目的片段测序正确并成功插入表达载体中, 转染了各质粒的阳性细胞克隆均可检测出E G F P的表达,不同启动子调控下的蛋白表达量有所不同。结论 H B V启动子调控下的E G F P报告基因能够在肝癌细胞中特异表达,不同启动子表达效率之间存在一定的差异性,从而为肝脏疾病的基因治疗提供了一个新的选择。
Summary: To investigate the killing effect of PNP/MeP-dR suicide gene system on hepatoma cells, pcDNA3.0/PNP, an eukaryotic expression vector harboring E. coli PNP gene, was transfected into human hepatoma HepG2 cells by liposome-mediated method. A HepG2 cell line with stable PNP gene expression, HepG2/PNP, was established with presence of G418 selection. The cell growth curves were determined with trypan blue staining. The sensitivity of HepG2/PNP to MeP-dR and bystander effects were assayed by MTT and FCM methods. The enzymatic activity of the product of PNP gene was determined by HPLC method. The cytotoxic effects of MeP-dR on HepG2/PNP cells were obvious (IC 50=4.5 μmol/L) and all HepG2/PNP cells were killed 4 days after the treatment with 100 μmol/L MeP-dR. In mixed cultures containing increasing percentages of HepG2/PNP cells, total population killing was demonstrated when HepG2/PNP cells accounted for as few as 5 % of all HepG2 cells 8 days after the treatment with 100μmol MeP-dR. High-pressure liquid chromatography (HPLC) demonstrated that the PNP enzyme could convert MeP-dR into 6-MP. PNP/MeP-dR suicide gene system had an advantage over traditional suicide gene systems for hepatoma gene therapy. Our e results suggest that high-level bystander effects of this system result in significant anti-tumor responses to hepatoma gene therapy, especially in vivo.
