ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of cytosine deaminase (CD) gene plus 5-fluorocytosine (5-Fc) on the growth of human colon cancer xenograftin nude mice.</p><p><b>METHODS</b>Retroviral vector expressing CD gene was transfected into human colon cancer SW1116 cells. Expression of the transfected CD gene in SW1116 (SWCD(2)) was confirmed by RT-PCR. The cytotoxicity of 5-Fc on SW1116 was determined by MTT assay in vitro. In vivo, the CD gene expression vector was injected intratumorally and 5-Fc was given by ip injections.</p><p><b>RESULTS</b>In vitro, SWCD(2) cells were killed by 5-Fc with an IC(50) of 66 micromol/L while the nontrasfected SW1116 cells needed an IC(50) of 16 000 micromol/L to be killed. The growth of SWCD(2) xenografts was significantly inhibited by systemic administration of 5-Fc.</p><p><b>CONCLUSION</b>CD gene/5-Fc system is a potential gene therapy strategy for human colon cancer.</p>