Abstract: Objective: To investigate the effect of gene therapy on colocarcinoma with the system of TK/GCV(Thymidine kinase/Ganciclovior) and CD/5Fc(Cytosine deaminase/5Fluorocytosine). Methods: With the method of transplantation of cultivated cells, 32 nude mice were injected subcutaneouly on the back with human colocarcinoma cell line SW480. They were divided into 4 groups at random, control, TK/GCV, CD/5Fc and system of TK/GCV and CD/5Fc group. Each group had 8 nude mice. TK,CD mediated by the reverse transcription virus were injected directly into the tumor. The common statuses of mice, the bulk, weight, inhibition rate, pathology and survival period of the tumor were detected. Results: Animal model of SW480 was successfully constructed. Each treatment group, especially the combined gene therapy group obviously inhibited the tumor′s growth and prolonged the survival period. The difference was significant between control and treatment groups, and the combined gene therapy group worked more markedly. There was mutual effect between TK/GCV and CD/5FcConclusions: TK/GCV or CD/5Fc obviously inhibits the growth of human colocarcinoma cell line SW480, and their combination has a greater anticancer effect.

Key words: Colorectal neoplasms, Thymidine kinase, Ganciclovir, Cytosine deaminase, 5fluorocytosine, Mice, nude