癌胚抗原启动子控制胞嘧啶脱氨酶基因体外对结肠癌细胞专一性杀伤

目的：研究癌胚抗原（CEA）启动子是否能控制大肠杆菌胞嘧啶脱氨酶（EC－CD）基因在CEA阳性结肠癌细胞中专一性表达和杀伤结肠癌细胞。方法：构建由CEA启动子驱动的含EC－CD基因的重组腺病毒载体AdCEACD与由巨细胞病毒（CMV）启动子驱动的含EC－CD基因的腺病毒载体AdCMVCD，分别感染CEA阳性的人结肠癌细胞株Lovo细胞和CEA阴性的Hela细胞，用RT－PCR法检测受染细胞中EC－CD基因的表达，并用MTT法检测感染后细胞对5－氟胞嘧啶（5－FC）的敏感性。结果：Lovo细胞在AdCMVCD与AdCEACD感染后均有EC－CDmRNA表达，且对5－FC的敏感性明显增强，Hela细胞在AdCMVCD感染后有EC－CDmRNA表达，对5－FC的敏感性增强，而在AdCEACD感染后则没有EC－CDmRNA表达，5－FC对其亦无杀伤作用。结论：CEA启动子能够控制EC－CD基因专一性地在CEA阳性的结肠癌细胞中表达，从而实现EC－CD基因的靶向性作用。

Carcino-Embryonic Antigen Promotor Controls the Specific Cytotoxicity of E.coli Cytosine Deaminase Gene in Colorectal Carcinoma Cells in vitro

Objective: To investigate whether carcino embryonic antigen(CEA) promotor determines the specific expression of E. coli. cytotosine deaminase(EC CD) gene and the specific cytoxicity in CEA producing colorectal carcinoma cells. Methods: Two recombinant adenovirus vectors, AdCEACD containing EC CD gene controlled under CEA promotor and AdCMVCD containing cytomegalovirus(CMV) promotor and EC CD gene, were constructed. The expression of EC CD gene in cells was tested with RT PCR and cytotoxic effects were assayed with MTT method. Results: The CEA producing cells (human colorectal carcinoma cell line Lovo cell) showed EC CD mRNA expression and became sensitive to 5 fluorocytosine (5 FC) after infection with AdCEACD and AdCMVCD respectively, The CEA nonproducing cells(Hela cell) expressed EC CD mRNA and were sensitive to 5 FC after infection with AdCMVCD, but had no expression of EC CD mRNA and no cytotoxic effect after infection with AdCEACD. Conclusion: CEA promotor could control the expression of EC CD gene in CEA positive colorectal carcinoma cells specifically in vitro .