人微管不稳定蛋白基因真核表达载体的构建与表达及对食管癌细胞的作用

目的 构建人微管不稳定蛋白基因(stathmin)真核表达载体,研究其对食管癌细胞EC9706的作用.方法 采用逆转录聚合酶链反应(RT-PCR)扩增stathmin cDNA,克隆至pMDl8-T载体并酶切鉴定后,亚克隆至pEGFP-C2真核表达载体.将测序鉴定正确的重组载体和空载体经脂质体转染EC9706细胞,G418筛选获得稳定转染的细胞株.通过荧光显微镜观察转染细胞荧光蛋白的表达,采用Western blot检测转染细胞中增强型荧光蛋白(EGFP)和stathmin融合蛋白的表达.选取稳定转染的细胞株,采用细胞计数法绘制细胞生长曲线,采用流式细胞仪分析细胞的增殖状态,平板克隆形成实验、裸鼠移植瘤实验分析转染细胞成瘤性.结果 RT-PCR扩增获得450 bp的cDNA编码序列;克隆至pMD18-T载体,经酶切鉴定后获反向插入质粒;亚克隆至pEGFP-C2载体后,经酶切与测序鉴定,重组载体pEGFP-stathmin构建成功.重组载体和空载体转染EC9706细胞,G418筛选获得稳定转染的细胞株.通过荧光显微镜观察到,转染细胞中呈现绿色荧光;经Western blot证实,重组载体表达46 000的融合蛋白.与空载体转染细胞相比,转染重组载体的EC9706细胞形态变大,增殖速度减慢,细胞分裂阻滞于G2/M期,细胞克隆形成数减少,裸鼠体内成瘤性降低(P＜0.05).结论 构建的真核表达载体pEGFP-stathmin在食管癌EC9706细胞中能够稳定表达,并抑制肿瘤细胞的增殖和成瘤性.

Construction and expression of human stathmin gene eukaryotic expression vector and its effect on esophageal cancer cells

OBJECTIVE: To construct an eukaryotic expression vector of human stathmin gene and to assess its effect on esophageal cancer EC9706 cells. METHODS: Stathmin cDNA coding sequence was amplified by RT-PCR from Eca109 cells and was cloned into pMD18-T vector. After identifying and sequencing, the correct inserting stathmin gene was sub-cloned into eukaryotic expression vector pEGFP-C2. EC9706 cells were transfected with this recombinant plasmid and control plasmid using Lipofectamine 2000, and the stable intergrant was selected with G418 medium. The expression of enhanced green fluorescent protein (EGFP) protein was detected by fluorescence microscopy and EGFP/stathmin fusion protein by Western blot assay in transfected EC9706 cells. The growth curve of the two stably transfected cells was protracted with cell counting. FACS was used to detect the cell cycle. The clone formation rate in plate and in nude mice was tested to investigate the tumorigenic characteristics of the two stably transfected cells in vitro and vivo. RESULTS: A 450 bp coding sequence of stathmin cDNA was amplified by RT-PCR, which was cloned into pMD18-T vector. After identified with restriction enzyme the recombinant plasmid pMD18-T-stathmin containing reverse inserting sequence was constructed successfully. Then, the sub-clone pEGFP-stathmin was sequenced, confirming that the recombinant vector was right. The recombinant plasmid pEGFP-stathmin and pEGFP-C2 vector were transfected separately into EC9706 cells. After selecting with G418, the cells were transfected steadily. EGFP in EC9706 cells was observed after transfection by fluorescence microscopy. The expressed product was proved to be 46,000 EGFP/stathmin fusion protein by Western blot. Compared with those transfected with pEGFP-C2, the growth of cells transfected with pEGFP-stathmin became slow, the cells were swelled, the cell cycle was blocked at G2/M phase, the average clone formation rate decreased in vitro, and the tumorigenicity of inoculated cells in nude mice was decreased. CONCLUSION: The recombinant eukaryotic expression vector pEGFP-stathmin has been constructed successfully. It expresses steadily in esophageal cancer cells and inhibits the proliferation and tumorigenicity of transfected cells.