目的：探讨组织特异性胞嘧啶脱氨酶/5氟胞嘧啶（cytisine deaminase/5fluorocytosine,CD/5FC）系统热化疗对结肠癌肝转移裸鼠模型的治疗作用。方法：将含CEA启动子调控CD基因表达的逆转录病毒载体进行扩增、纯化、包装，并收集病毒上清。45只裸鼠经门静脉注射人结肠癌LoVo细胞，成瘤后2 d腹腔注射病毒上清（0.2 ml/次，每天1次，共5 d）。随机分为对照组、常温化疗组和热化疗组，分别经腹腔注射生理盐水、室温前药5FC和43 ℃前药5FC\[均为500 mg/（kg·d）\]进行治疗。治疗21 d后处死裸鼠， 观察肝脏转移率和转移结节数， RTPCR检测CD基因在肿瘤组织的表达，光镜及电镜下观察肿瘤病理学的变化。结果：病毒滴度为5.6×106 CFU/L。CD基因在移植瘤组织中有效表达。热化疗组的肝转移率与转移结节数均低于常温化疗组\[133% vs 40.0%,(0.20±0.56)个vs（0.80±1.01）个；均P<0.05\]。光镜下见对照组肝转移瘤组织细胞生长活跃，热化疗组较化疗组肝转移瘤细胞生长受抑制更明显。电镜下见化疗组、热化疗组肝转移瘤细胞有不同程度的凋亡改变。结论：组织特异性CD/5FC系统热化疗对裸鼠结肠癌肝转移瘤有明显的抑制作用。

Objective:To investigate the effectiveness of tissue specific cytisine deaminase/5fluorocytosine (CD/5FC) thermochemotherapy system in treatment of liver metastasis of colon cancer in nude mice. Methods: CEA promoterregulated recombinant retroviral vector G1CEACDNa was packaged, propagated and purified, and the viral supernatant was harvested. Human colon cancer LoVo cells were injected into the portal veins of 45 nude mice. Two days after the establishment of liver metastasis model, the viral supernatant was intraperitoneally injected into mice（0.2 ml/d, 5 d）. The 45 mice were then randomly divided into 3 groups, namely, the control group (injected with sodium), chemotherapy group (prodrug/5FC) and thermochemotherapy group (43 ℃ prodrug/5FC). After treated for 21 d, the mice were sacrificed and liver metastasis rate and liver metastasis nodule numbers were observed. Expression of CD gene in liver metastasis tissues was determined by RTPCR. Pathological changes of liver metastasis tissues were examined by light microscope and electron microscope.Results: The virus titer of G1CEACDNa was 5.6×106 CFU/L. CD gene was effectively expressed in the liver metastasis tissues. Liver metastasis rates and number of liver metastasis nodules were significantly lower in the thermochemotherapy group than in the chemotherapy group (13.3% vs 400%, \[0.20±0.56\] vs \[0.80±1.01\]; all P<0.05). The tumor cells grew well in the control group, and were greatly inhibited in the thermochemotherapy group compared that in the other two groups. The tumor cells showed different degrees of apoptosis in the thermochemotherapy and chemotherapy groups under electron microscope.Conclusion: The tissue specific CD/5FC thermochemotherapy system can inhibit the growth of liver metastasis of colon cancer in nude mice.

福建省自然科学基金资助项目（No.C0410045）