Synergistic antitumor effects of 131I-LC-1 IgM and IL-12 vaccine on Lewis lung carcinoma

This study was designed to determine the antitumor effects of iodine-131 labeled monoclonal antibody LC-1 (131I-LC-1), interleukin-12 (IL-12) vaccine, or the combination of both on C57BL/6 mice bearing Lewis lung carcinoma (LLC) tumors. Tumor-bearing mice models were randomly divided into 4 groups that were respectively injected intratumorally with phosphate buffered solution (PBS), IL-12 vaccine gene therapy (GT), 131I-LC-1 radioimmuno-therapy (RIT), or GT + RIT. Tumor volumes were measured before and after treatment. ELISA and RT-PCR determined the expression of IL-l2. LC-1 monoclonal antibody (Mab) was labeled with Na131I. Cytolytic T lymphocyte (CTL) activity assay, Natural Killer cell (NK) activity assay and apoptosis analysis were performed. Intratumoral 131I-LC-1 injection leads to higher delivery of the antibody to the tumor. Tumor apoptosis occurred in the GT, RIT and GT + RIT groups. Tumor growth was inhibited in the GT, RIT and GT + RIT groups. Compared with other groups, the combination of GT + RIT up-regulated the expression of IL-l2 gene and inhibited the tumor growth more effectively than either GT or RIT alone (p < 0.05). These results suggest that GT + RIT have the synergistic antitumor effects on tumor-bearing mice.