Guo Shan-Yu, Gu Qin-Long, Zhu Zheng-Gang, Hong He-Qun, Lin Yan-Zhen
Department of Surgery, the Affiliated Shanghai Ninth People's Hospital, Shanghai Second Medical University, Shanghai 200011, China.
World J Gastroenterol. 2003 Feb;9(2):233-7. doi: 10.3748/wjg.v9.i2.233.
Cancer gene therapy has received more and more attentions in the recent decade. Various systems of gene therapy for cancer have been developed. One of the most promising choices is the suicide gene. The product of thymidine kinase (TK) gene can convert ganciclovir (GCV) to phosphorylated GCV, which inhibits the synthesis of cell DNA, and then induces the cells to death. Cytokines play an important role in anti-tumor immunity. This experiment was designed to combine the TK gene and mIL-2/mGM-CSF genes to treat gastric cancer, and was expected to produce a marked anti-tumor effect.
TK gene was constructed into the retroviral vector pLxSN, and the mIL-2 and mGM-CSF genes were inserted into the eukaryotic expressing vector pIRES. The gastric cancer cells were transfected by retroviral serum that was harvested from the package cells. In vitro study, the transfected gastric cancer cells were maintained in the GCV- contained medium, to assay the cell killing effect and bystander effect. In vivo experiment, retroviral serum and cytokines plasmid were transfected into tumor-bearing mice, to observe the changes of tumor volumes and survival of the mice.
In vitro experiment, 20 % TK gene transduced cells could cause 70-80 % of total cells to death. In vivo results showed that there was no treatment effect in control group and TK/GCV could inhibit the tumor growth. The strongest anti-tumor effect was shown in TK+mIL-2+mGM-CSF group. The pathologic examination showed necrosis of the cancer in the treated groups.
TK/GCV can kill tumor cells and inhibit the tumor growth in vivo. IL-2 and GM-CSF strongly enhance the anti-tumor effect. Through the retrovirus and liposome methods, the suicide gene and cytokine genes are all expressed in the tissues.
癌症基因治疗在近十年中受到越来越多的关注。已开发出多种癌症基因治疗系统。最有前景的选择之一是自杀基因。胸苷激酶（TK）基因的产物可将更昔洛韦（GCV）转化为磷酸化的GCV，抑制细胞DNA的合成，进而诱导细胞死亡。细胞因子在抗肿瘤免疫中起重要作用。本实验旨在将TK基因与mIL-2/mGM-CSF基因联合用于治疗胃癌，预期产生显著的抗肿瘤效果。
将TK基因构建到逆转录病毒载体pLxSN中，将mIL-2和mGM-CSF基因插入真核表达载体pIRES。用从包装细胞收获的逆转录病毒血清转染胃癌细胞。在体外研究中，将转染后的胃癌细胞置于含GCV的培养基中，以检测细胞杀伤作用和旁观者效应。在体内实验中，将逆转录病毒血清和细胞因子质粒转染到荷瘤小鼠体内，观察肿瘤体积的变化和小鼠的存活情况。
体外实验中，20%的TK基因转导细胞可导致70 - 80%的总细胞死亡。体内结果显示，对照组无治疗效果，TK/GCV可抑制肿瘤生长。TK+mIL-2+mGM-CSF组显示出最强的抗肿瘤效果。病理检查显示治疗组肿瘤出现坏死。
TK/GCV可在体内杀死肿瘤细胞并抑制肿瘤生长。IL-2和GM-CSF可强烈增强抗肿瘤效果。通过逆转录病毒和脂质体方法，自杀基因和细胞因子基因均在组织中表达。
