双自杀基因慢病毒转移载体系统的构建及其对K562细胞的杀伤作用

为了探讨双自杀基因慢病毒转移载体系统对K562细胞的杀伤作用,采用分子生物学方法构建了含大肠杆菌胞嘧啶脱氨酶(E.coli CD)和单纯疱疹病毒胸苷激酶(HSV-TK)的双自杀基因慢病毒转移载体,将慢病毒基因转移系统中的3种成分质粒(目的基因转移载体、包装结构及包膜结构质粒)用脂质体分为2组(实验组、对照组)共转染入病毒包装细胞293T,在荧光显微镜下观察转染效果,在透射电镜下观察上清中的病毒颗粒.大量收集病毒上清,浓缩后感染K562细胞,荧光显微镜下观察感染效果,RT-PCR鉴定目的基因在K562细胞中的整合转录.给予前体药物5-氟胞嘧啶(5-FC)和(或)无环鸟苷(GCV)后,用MTT法测定体外杀伤效应,扫描电镜下观察使用前体药物后K562细胞的变化.结果表明成功构建了双自杀基因慢病毒转移载体,脂质体法可有效将上述慢病毒表达质粒转入293T细胞.荧光显微镜下观察到对照组大量绿色荧光蛋白(green fluorescenceprotein,GFP)表达.透射电镜下观察到大量浓缩后病毒颗粒.荧光显微镜下观察到此基因转移载体系统对293T细胞及K562细胞的感染率均很高,单独使用GCV或5-FC对转染自杀基因的K562细胞的生长抑制率(growth inhibition ration,GIR)分别为48.73%、50.16%,与未转染K562细胞比较明显升高,有显著性差异(P＜0.01),联合使用5-FC和GCV时K562细胞的GIR为87.69%,比单独使用5-FC或GCV时明显升高,有显著性差异(P＜0.01).结论双自杀基因慢病毒基因转移载体系统可将双自杀基因高效转移至K562细胞,是一种有效的基因转移载体系统.

Establishment of Lentivirus-Mediated System of Double Suicide Genes and Its Killing Effects on K562 Cells

To establish lentivirus-mediated system of double suicide genes and explore its killing effects on K562 cells, lentivirus transfer vector for double suicide genes was constructed using molecular methods, three plasmids of lentivirus gene transfer vector system were transferred into packaging cell line 293T using lipofectine method, the transfer effect was observed through fluorescence microscopy, the lentivirus particles were observed by means of electron microscopy. High titer of lentivirus was harvested from the supernatant of virus-producing cell culture and concentrated by high-speed centrifugation with Poly-L-Lysine (PLL). The K562 cells were infected with the concentrated supernatant containing the virus with the double suicide genes. Fluorescence microscopy and RT- PCR confirmed the integration and expression of extraneous gene. The cytotoxicity to these transgenic cells treated with 5-FC and GCV was measured by MTT assays. The growth inhibition ratio (GIR) of cells and inhibition concentration 50 (IC(50)) were counted. After administration of GCV and 5-FC, the changes of those cells were observed through scanning electron microscope. The results showed that lentivirus transfer vector with double suicide genes was constructed successfully. The above-mentioned plasmids were effectively transferred into 293T cells. So much green fluorescence was observed through fluorescence microscope. A lot of lentivirus particles were observed through transmission electron microscope. Double suicide genes mediated by lentivirus were stably integrated and expressed in K562 cells after infection with the concentrated virus using fluorescence microscopy and RT-PCR. The GIR of K562 cells using GCV or 5-FC was 48.73% or 50.69% respectively and it was apparently higher than that of untransfected cells (P < 0.01). When using GCV and 5-FC together, the GIR was 87.69%, which was apparently higher than that of group using GCV or 5-FC alone (P < 0.01). In conclusion, lentivirus-mediated gene transfer system could transfer CD and TK double suicide genes into K562 cells with high efficiency and it had strong killing effects when giving 5-FC and/or GCV. The cytotoxic effects of double suicide genes were superior to that of single suicide gene. The lentivirus-mediated double suicide gene transfer system is a high-efficiency gene transfer vector.