GPC3 DNA vaccine elicits potent cellular antitumor immunity against HCC in mice.

Background/Aims: DNA-based tumor vaccine immunotherapy which elicits exclusively cellular immune response against cancer cells in an antigen-specific fashion has been documented to be an effective treatment for cancers in the past decade. Glypican 3 (GPC3) is especially overexpressed in hepatocellular carcinoma (HCC), but not in benign liver lesions and normal adult tissues, which makes it an ideal tumor antigen designed for HCC immunotherapy. Methodology: We constructed a GPC3 cDNA vaccine by using a recombinant plasmid encoding murine GPC3 cDNA for treatment of HCC in a C57BL/6 mouse model. The specificity and effectiveness of anti-tumor immunity were assessed in vitro and in vivo studies. Results: In vitro studies showed that GPC3 DNA vaccine induced potent specific cytotoxic T lymphoctyes (CTLs) immune response against C57BL/6 homogenous HCC cell line Hepa 1-6 (GPC3*). However, there was no detectable immune response against GPC3-negative SP 2/0 cells and Sk-Hep-1 cells. In vivo study indicated that GPC3 DNA vaccine could significantly suppress homogenous tumor growth and prolong survival time of tumor bearing mice. Conclusions: This study demonstrated the first time that the GPC3 DNA vaccine could elicit specific and effective cellular antitumor immunity against GPC3(+) HCC. This may provide an alternative option for immunotherapy of HCC.