婴儿双歧杆菌介导的CD/5-FC自杀基因系统对黑色素瘤的抑瘤实验

目的 观察婴儿双歧杆菌介导的胞嘧啶脱氨酶／5-氟胞嘧啶(CD／5-FC)自杀基因系统对黑色素瘤的体内、外抑瘤效果。方法 含重组CD基因的婴儿双歧杆菌中加入5-FC．厌氧条件下培养24h后取其上清液．加到黑色素瘤B16-F10细胞上．观察其对细胞形态及细胞生长抑制率的影响；建立小鼠黑色素瘤动物模型，尾静脉注入含重组CD基因的婴儿双歧杆菌，腹腔注入5-FC，观察携带重组CD基因的婴儿双歧杆菌联合5-FC对黑色素瘤肿瘤体积及肿瘤体积倍增时间的影响。结果 ①体外实验：实验组肿瘤细胞形态显示出显著的损伤性改变，细胞生长受到明显抑制．而对照组肿瘤细胞影响不大。②小鼠黑色素瘤动物模型实验结果显示，经重组婴儿双歧杆菌联合5-FC治疗21d．实验组肿瘤倍增时间明显长于对照组．其肿瘤体积明显小于对照组．且随着观察时间的延长，这种差异越显著。结论 婴儿双歧杆菌介导的CD／5-FC自杀基因系统对黑色素瘤具有明显的抑瘤效果。

Antitumor Efficacy of CD/5-FC Suicide Gene Therapy System Mediated by Bifidobacterium Infantis against Melanoma

OBJECTIVE: To observe the antitumor efficacy of cytosine deaminase/5-fluorocytosine (CD/5-FC) suicide gene therapy system mediated by Bifidobacterium infantis against melanoma in vitro and in vivo. METHODS: Bifidobacterium infantis transfected by CD gene was incubated with 5-FC in anaerobic condition. The supernatant of bacteria was collected and added to the melanoma B16-F10 cells for assessment of the killing effect of this suicide gene system. Mice were incubated with melanoma B16-F10 cells to establish animal models. Then the mice bearing melanoma were treated by a combination of Bifidobacterium infantis transfected by CD gene and 5-FC. Bifidobacterium infantis transfected by CD gene was injected into the tail vein of mice and 5-FC was given introperitoneally. RESULTS: (1) In vitro, the tumor cells in test groups appeared damaged with remarkable changes in morphology, and the cell growth was significantly inhibited as compared against those in the control group. (2) In animal experiment, after the mice melanoma model being treated with the recombined bacteria and 5-FC for 21 days, the tumor growth span was remarkably prolonged and the tumor volume was significantly inhibited when compared with control. The differences became more obvious with the passage of observation time. CONCLUSION: CD/5-FC suicide gene therapy system mediated by Bifidobacterium infantis was noted to have good antitumor effect on melanoma.