CD自杀基因联合淋巴细胞趋化因子基因疗法的肿瘤治疗作用及免疫机理研究

Combined Use of CD Suicide Gene and Lymphotactin Gene Therapy Elicit Potent Antitumor Effects

本研究以腺病毒作为载体,将大肠杆菌胞嘧啶脱氨酶(CD)基因与小鼠淋巴细胞趋化因子(Ltn)基因体内联合转染,观察了其抗肿瘤效应并分析了免疫机理.小鼠皮下接种结肠腺癌CT26细胞后3天,肿瘤局部注射表达Ltn的重组腺病毒AdLtn和表达CD的重组腺病毒AdCD,然后连续10天给予5一氟胞嘧啶(5-FC)300mg/kg进行治疗,结果表明,联合治疗组荷瘤小鼠皮下肿瘤结节的生长受到明显抑制,小鼠存活期明显长于单用AdLtn治疗组或单用AdCD/5-FC治疗组.经联合治疗后小鼠脾细胞的NK活性和对(37结肠腺癌细胞的CTL杀伤活性明显增强.瘤体细胞FACS分析结果表明,经联合基因治疗后,肿瘤组织CD4^+、CD8^+细胞浸润增加,结肠腺癌细胞表达H-2Kd和B7-1分子明显增加.提示经CD自杀基因和Ltn基因联合治疗后,肿瘤细胞免疫原性增加.本研究结果表明联合应用自杀基因和Ltn基因治疗可以提高机体对肿瘤细胞免疫的应答,增加机体的抗肿瘤作用,是肿瘤基因治疗中一条新的途径.

Adenovirus harboring E. coli. cytosine deaminase gene (AdCD) and adenovirus encoding with lymphotactin gene (AdLtn) were used for gene therapy in vivo. BALB/c mice were inoculated subcutaneously with CT26 colon adeno-carcinoma cells and 3 days later received combined injection of AdCD and/or AdLtn followed by continuous injection with 5-fluorocytosine(5-FC) 300mg/kg. The results demonstrated that mice received combined therapy developed tumors most slowly and survived longest when compared with mice treated with AdCD/5-FC, AdLtn, AdlacZ/5-FC or PBS. To further explain the immunological mechanism of the antitumor effects by the combined therapy, we found that combined treatment with suicide gene and Ltn gene therapy achieved maximal cytotoxic effects of nature killer cells and specific cy-totoxic T lymphocytes. FACS analysis of the tumor mass demonstrated that AdCD/5-FC in combination with AdLtn therapy increased the expression of H-2K^d and B7-1 expression on tumor cells. The CD4^+ and CD8^+ cells infiltrated in the tumor mass after combined therapy were significantly increased when measured by FACS analysis. Our results demonstrated that combined transfer of suicide gene and lymphotactin gene induce nonspecific and specific antitumor immunity of the host and elicit more potent antitumor effect.