腺病毒介导的肝癌自杀基因疗法的实验研究

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。

xperimental Study on Adenovirus-Mediated Suicide Gene Therapy for Human Hepatucellular Carcinoma Using Escherichia Coli Cytosine Deaminase

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.