大肠杆菌CD自杀基因转染诱导肿细胞凋亡及旁观者效应的研究

以重组腺病毒AdCD为载体将大肠杆菌胞嘧啶脱氨酶(CD)基因体外传染小鼠红白血病细胞FBL3,结果显示,转染了CD基因的FBL3细胞对5-氟胞嘧啶(5-FC)的敏感性显著提高,进一步研究发现,AdCD/5-FC系统可以诱导肿瘤细胞发生凋亡;将经AdCD/5-FC处理过的FBL3细胞上清倍比稀释后,加入到野生型FBL3细胞中,发现当上清仅占6.25％时,即对野生型FBL3细胞发挥明显的杀伤作用,提示旁观者效应在AdCD介导的细胞毒作用中起着重要的作用。本实验还观察了CD基因体内转染后的杀伤效果,荷瘤小鼠局部注射AdCD并连续10天给予5-FC(300mg/kg)治疗后,小鼠皮下肿瘤结节的生长受到明显抑制。

Induction of Tumor Cell Apoptosis by Adenovirus-Mediated E. coli Cyto-sine Deaminase Gene Transfection and Its Bystander eftect

Adenoviruses harboring E. coli cytosine deaminase gene (AdCD) were used to transfect murine FBL-3 ery-throleukemia cells in vitro. FBL3 cells infected with AdCD were more sensitive to 5-fluorocytosine (5-FC) than cells infected with a control adenovirus AdLacZ. Further study indicated that this combination therapy (AdCD and 5-FC) killed tumor cells by inducing apoptosis of FBL-3 cells. The supematants from FBL-3 cells treated with AdCD/5-Fc were transferred on the culture system of uninfected (wild - type) FBL-3 cells, the result indicated that only 6.25% of the supernatant could induce significant cytotoxicity on wild type FBL3 cells. The results demonoustrated that bystander effect plays an important role in AdCD-mediated cytotoxicities. Direct injection of AdCD into established subcutaneous FBL3 tumor in mice followed by daily intraperitoneal injection of 5-FC for 10 days was found to inhibit tumor growth significant-