Transfection of colorectal cancer cells with chemokine MCP-3 (monocyte chemotactic protein-3) gene retards tumor growth and inhibits tumor metastasis

AIM: To evaluate the possibility of the induction of antitumor immune response by transfecting the colorectal cancer cells with chemokine MCP-3 gene. METHODS: Mouse MCP-3 gene was transduced into mouse colorectal cancer cells CMT93 by using of Liposome. G418-resistant clones were selected and the MCP-3 mRNA expression was detected by RT-PCR. The chemotactic activity of MCP-3 in the cell culture supernatant was detected by Chemotaxis assay. The tumorigenicity of wild type CMT93 and CMT93 gene transfectants were detected by in vivo experiments. The immune cell infiltrations in tumor tissue and tumor metastasis were detected histopathologically. RESULTS: MCP-3 mRNA expression was detected by RTPCR in gene-transfected cells (CMT93/MCP-3), but not in control groups. And MCP-3 secreted in the cell culture supernatant possessed chemotatic activity. The results from in vivo experiments showed that the tumorigenicity of CMT93/MCP-3 had not decreased, but the tumors derived from CMT93/MCP-3 cells grew more slowly than those from CMT93 cells (1.021 +/- 0.253) cm(2) vs(1.769 +/- 0.371) cm(2), P<0.05) or CMT93/mock cells (1.021 +/- 0.253) cm(2) vs(1.680 +/-0.643)cm(2), P<0.05). Histophathological results showed few immune cells infiltrating in the tumor tissue derived from the controls. In the tumor tissue derived from CMT93/MCP-3, infiltrating immune cells increased. In addition, no tumor metastasis was found in all mice inoculated with CMT93/ MCP-3 tumor cells. But all mice had tumor metastasis in CMT93 controls and 4 in 5 mice had tumor metastasis in CMT93/mock controls. CONCLUSION: The results suggested that the transfection of chemokine MCP-3 gene could promote the induction of anti-colorectal cancer immunity, but the tumor growth could not be inhibited completely by merely MCP-3 gene transfection.