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构建了含有大肠杆菌胞嘧啶脱氨酶基因（ＥＣ－ＣＤ）的重组逆转录病毒载体ＬＣＤＳＮ。经ＰＡ３１７细胞包装后，感染人结肠癌细胞株ＬｏＶｏ。Ｇ４１８筛选得到稳定表达ＥＣ－ＣＤ基因的细胞克隆ＬｏＶｏ／ＬＣＤＳＮ。ＬｏＶｏ／ＬＣＤＳＮ与野生型ＬｏＶｏ细胞相比，生长曲线无明显差异，细胞形态亦无改变。ＬｏＶｏ和ＬｏＶｏ／ＬＣＤＳＮ都对５－ＦＵ很敏感（ＩＣ５０约为０．５μｍｏｌ／Ｌ）。表达ＣＤ基因使细胞对基本无毒性的原药５－ＦＣ的敏感性增加，半杀伤浓度由野生型ＬｏＶｏ细胞的２２０００μｍｏｌ／Ｌ降低到ＬｏＶｏ／ＬＣＤＳＮ的１３μｍｏｌ／Ｌ。旁杀伤实验证明，将转基因细胞和不转基因细胞以３０∶７０的比例混合，给予低浓度５－ＦＣ，８０％以上的肿瘤细胞被杀死。
A recombinant retrovirus vector LCDSN containing the E.coli cytosine deaminase gene (EC-CD) was constructed. After being packaged by PA317 cells, the human colon cancer cell line LoVo was infected. G418 was screened to obtain stable cell cloning of EC-CD gene clone LoVo / LCDSN. Compared with wild-type LoVo cells, LoVo / LCDSN showed no significant difference in growth curve and no change in cell morphology. LoVo and LoVo / LCDSN are sensitive to 5-FU (IC50 is about 0.5μmol / L). The expression of the CD gene increased the sensitivity of the cells to the essentially non-toxic 5-FC, a half-killing concentration reduced from 22000 μmol / L in wild-type LoVo cells to 13 μmol / L in LoVo / LCDSN. By-kill assays demonstrated that the transgenic and non-transgenic cells were mixed in a 30:70 ratio giving low concentrations of 5-FC and over 80% of the tumor cells were killed.