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

ABSTRACT

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.