5-FC/CD系统对荷大肠癌裸鼠肿瘤的杀伤效应

Killing effect of 5 FC/CD system on nude mice bearing human colorectal carcinoma *

目的研究ｃｄ基因对大肠肿瘤的特异杀伤作用，探索自杀基因靶向治疗大肠癌的有效途径．方法逆转录病毒感染法将Ｇ１ｃｅａｃｄＮａ及ｐｃｄ２分别转导入高分泌ＣＥＡ的大肠癌细胞Ｌｏｖｏ中，再分别接种到裸鼠皮下．成瘤后腹腔给予５ＦＣ（５００ｍｇ／ｋｇ）治疗，观察肿瘤重量的变化及病理学特点．结果含Ｇ１ｃｅａｃｄＮａ及ｐｃｄ２逆转录病毒载体的病毒滴度分别为：１３×１０７及２１×１０８ＣＦＵ／Ｌ．所有转基因成功并接种动物均成瘤．腹腔给予５ＦＣ治疗后发现，转由ＣＥＡ基因顺式转录调控序列（ＴＲＳ）驱动ｃｄ基因的组织特异性重组逆转录病毒载体Ｇ１ｃｅａｃｄＮａ的肿瘤对５ＦＣ的敏感性明显高于转非ｃｅａ调控ｃｄ基因的肿瘤，治疗结束后肿瘤重量分别为３１ｍｇ±８ｍｇ及１１３ｍｇ±２３ｍｇ（Ｐ＜００１）．结论本实验提示ｃｅａ转录调控序列可控制ｃｄ基因在ＣＥＡ阳性的大肠癌组织中高效表达。

AIM To study the killing effect of cytosine deaminase (cd) and targeted therapy for colorectal. METHODS The recombinant retroviral vector G1 ceacd Na, in which carcinoembryonic antigen (CEA) promoter was employed to drive the cd gene, was constructed. After packaging in PA317 cells and havesting viral supernant, the retroviral construct and p cd 2 were produced to CEA highly produced clolorectal carcinoma cell line Lovo and then 1 2×10 6 parental Lovo cells, Lovo cells transfected p cd 2 retroviral vectors and Lovo cells transfected G1 ceacd Na retroviral vectors were injected sc into flanking nude mice respectively. 500mg/kg 5 FC were given ip daily when the tumors were palpable. All the mice were sacrificed at the end of the treatment and the pathological analysis was made. RESULTS Virus titer of p cd 2 and G1 ceacd Na was 1 3×10 7 and 2 1×10 8 CFU/L respectively. All mice with implanted tumor cells developed tumors and a higher antitumor effect was observed in nude mice bearing ceacd tumors than in the mice bearing cd tumors following administration of 5 FC systemically ( P <0 01). CONCLUSION This efficient therapeutic approach involving cea/cd chimeric gene might be a potential tool for the colorectal carcinoma specific gene therapy. Suicide gene controlled by tissue specific promotor could result in obvious antitumor effects.