大肠杆菌嘌呤核苷磷酸化酶自杀基因对人胃癌细胞的作用

目的：探讨大肠杆菌嘌呤核苷磷酸化酶自杀基因对胃癌细胞MKN-45的抑制及杀伤作用, 并证实旁观者效应。方法：构建真核表达载体pcDNA3.1-ePNP, 将重组载体转染MKN-45细胞获得高表达大肠杆菌嘌呤核苷磷酸化酶基因（ePNP）的MKN-45细胞克隆。在MKN-45/ePNP细胞培养物中加入前体药物MePdR, 观察MePdR对该细胞的杀伤作用及旁观者效应。结果：随MePdR浓度的增大, MKN-45/ePNP细胞的生存率逐步下降,在MePdR浓度达到1 mg•L^-1时MKN-45/ePNP细胞全部被杀灭, 而未经转染的MKN-45细胞的生存率则不受影响，MePdR对MKN-45/ePNP有显著的抑制及杀灭作用；当MKN-45/ePNP细胞占总细胞的10%时，全部细胞被杀死。结论:ePNP/MePdR 自杀基因系统对胃癌细胞有生长抑制及杀伤作用并具有旁观者效应。

Effects of E. coli purine nucleoside phosphorylase suicide gene therapy on gastric cancer cells

Objective To study the effects E.coli purine nucleoside phosphorylase suicide gene on human gastric cancer MKN-45 cells as well as the bystander effect.Methods The ePNP gene was subcloned to pcDNA3.1 to construct recombinant eukaryotic expression vector pcDNA3.1-ePNP.The recombinant plasmid was transfected into MKN-45 cells by lipofectamin method and positive cell clones were screened with G418.Then MePdR was added to these gene-modified cells and the sensitivity of the cells to MePdR was studied as well as the bystander effect.Results MePdR treatment of MKN-45/ePNP cells induced cytotoxic and antiproliferative effects in a concentration-dependent manner with 100% cell death since 1 mg·L-1.Bystander effect was strong in vitro as 100% of tumor cells were killed by MePdR with only 10% MKN-45/ePNP cells.The gene-modified gastric cancer cells MKN-45/ePNP were sensitive to the treatment of MePdR compared with unmodified tumor cells,and also a remarkable bystander effect was observed.Conclusion The efficiency of ePNP/MePdR system and the potential feasibility of suicide gene strategy for clinical therapy of human gastric cancer are demonstrated.