本文观察了胞嘧啶脱氨酶(CD)基因/5-氟胞嘧啶(5FC)自杀基因疗法对肝癌模型的治疗作用。以CMV启动子调控CD基因的重组腺病毒载体AdexCMV.CD在体外能有效转染人肝癌细胞株SMMC-7721和HepG2,转染后的细胞体外生长能力无明显变化,对5FC的敏感性明显增高。当以AFP上游调控序列驱动CD基因的重组腺病毒载体AdexAFP.CD分别转染SMMC-7721和HepG2时,CD基因能在HepG2中表达,使HepG2对5FC的敏感性增高,但不能使SMMC-7721的生长受到5FC的抑制。[~3H]TdR掺入法观察体外旁观者效应时发现,当细胞总数中转染细胞数超过20％时,其生长明显被5FC抑制。将AdexCMV.CD直接注射入裸鼠接种SMMC-7721细胞形成的皮下肿瘤中,并全身应用5FC后,与对照组相比,肿瘤大小在开始治疗后第8天约缩小3倍,第18天约缩小4倍,以上结果表明,腺病毒介导的CD/5FC自杀基因系统能在体内、外有效地抑制肝癌的生长。以AFP上游调控序列驱动CD基因的腺病毒载体介导的基因转染能在AFP阳性的肝癌细胞中特异表达。

To evaluate whether in vitro and in vivo transfer of E. Coli cytosine deaminase gene will confer sensitivity of a solid tumor to prodrug 5-fluorocytosine(5FC), we used an adenovirus vector(AdexCMV. CD) carrying the cytosine deaminase gene driven by the CMV promoter, infected SMMC-7721 or HepG2 cells hepatocellular carcinoma cells in vitro, and found AdexCMV. CD vector could effectively suppressed the growth of SMMC-7721 and HepG2 cells. When the two cells were infected with AdexAFP. CD vector in which the CD gene was driven by the AFP gene 5'-flanking region, only HepG2 cells were conferred sensitivity to 5FC. (Infection with AdexCMV.CD, when as few as 20% of cells transfected the CD gene, SMMC-7721 cells were associated with a bystander effect when combined with 5FC in cell mixing studies.) Consistent with these in vitro observations, AdexCMV. CD was directly injected into established subcutaneous SMMC-7721 tumors in nude mice receiving 5FC,there was a 60% reduction in tumor size at day 8, 70% reduction at day 24. Our results suggested that adenovirus-mediated tumor-specific gene transfer of CD gene and concomitant administration of 5 FC may have potential as a strategy for local control of tumor growth.

国家自然科学基金，优秀中青年人才专项基金(39421009)