目的

研究携带甲胎蛋白（AFP）启动子的酵母菌胞嘧啶脱氨酶/胸苷激酶（yCDglyTK）双自杀基因体内靶向性治疗肝癌的效果和机制。

方法

构建携带AFP启动子的yCDglyTK双自杀基因表达质粒，通过阳离子脂质体将携带AFP启动子的yCDglyTK双自杀基因转染HepG2和SMMC7721肝癌细胞的裸鼠肝癌皮下种植瘤，观察自杀基因体内杀瘤效果以及细胞凋亡的情况。

结果

成功构建携带AFP启动子的yCDglyTK双自杀基因，其靶向性地在AFP阳性的HepG2细胞种植瘤上表达，而AFP阴性的SMMC7721细胞种植瘤上无表达，氟胞嘧啶（5-FC）、更昔洛韦（GCV）及两者联合可有效抑制HepG2细胞种植瘤的生长，抑瘤效果GCV+5-FC＞5-FC＞GCV，而SMMC7721细胞种植瘤的生长未受影响。HepG2细胞种植瘤治疗后有明显的细胞凋亡，而SMMC7721细胞种植瘤内极少凋亡细胞。

结论

携带AFP启动子的yCDglyTK双自杀基因能有效地靶向性地杀伤AFP阳性的肝癌细胞，细胞凋亡可能是其杀伤的重要机制之一。

Objective

To study the effects and mechanisms of yeast cytosine deaminase/thymidine kinase (yCDglyTK)double suicide gene driven by alpha fetoprotein (AFP)promoter on hepatocellular carcinoma(HCC) in vivo.

Methods

To construct the expression plasmid with yCDglyTK double suicide gene driven by AFP promoter,HepG2 (AFP positive)and SMMC7721 (AFP negative)human HCC cell xenografts in nude mice were both transfected with the above-mentioned expression plasmid through cationic liposome,followed by treatment of the prodrugs 5-fluorocytosine (5-FC) and/or ganciclovir (GCV). The effect of inhibition was observed through measuring the tumor size and the number of apoptosis cells.

Results

The double suicide gene was expressed selectively on HepG2 cell xenografts, rather than on SMMC7721 cells. The prodrugs 5-FC and/or GCV could inhibit effectively the growth of HepG2 cell xenografts,but had no influence on SMMC7721 cells. The inhibitive effects of different prodrugs on HepG2 cells were GCV+5-FC＞5-FC＞GCV.Apoptotic cells were found in HepG2 xenografts after the treatment of prodrugs. However, in SMMC7721 cell xenografts, few apoptotic cells were found.

Conclusions

yCDglyTK double suicide gene driven by AFP promoter has a significant efficacy in treatmentof AFP positive HCC.Cell apoptosis may be an important mechanism of inhibiting the growth ofHCC.