ABSTRACT
<p><b>OBJECTIVES</b>To evaluate the efficacy of antitumour colon cancer cell vaccine modified by escherichia coli cytosine deaminase (EC-CD).</p><p><b>METHODS</b>Mouse colon cancer cell vaccine CT26/CD was established by gene modification using retrovirus plasmid pLCDSN. Its tumorigenicity and effect on liver metastasis model established with wild-type colon cancer were evaluated.</p><p><b>RESULTS</b>CT26/CD was established successfully and proliferated in medium containing 0.6 g/L G418 stably. EC-CD gene expression on these mutant cells was confirmed by RT-PCR. These mutant cells were more sensitive to 5-fluorocytosine (5-FC) compared with the wild-type ones (P=0.000), and presented excellent bystander effect. CT26/CD had the same tumorigenicity as its parental cells (P=0.892). CT26/CD, combined with the prodrug 5-FC, could inhibit tumor progress and live metastasis, and prolonged the survival of the liver metastasis model animals (P=0.000).</p><p><b>CONCLUSION</b>The colon cancer cell vaccine modified by EC-CD presented anti-tumor effect in vivo, when treated with the prodrug.</p>