[Immune response of heparinase gene modified dendritic cell-based vaccine on gastric cancer cells]

To explore the feasibility of heparinase vaccine in active immunity for gastric cancer.

Dendritic cells originated from the peripheral blood mononuclear cells (PBMC) of healthy HLA-A2 positive donors were transfected with recombinant adenovirus containing heparinase full length cDNA of heparanase to generate heparanase gene modified DC vaccine. T lymphocytes from the same donors were activated by those genetically modified DC vaccine repeatedly to generate heparanase specific cytotoxicity T lymphocytes (CTL). CTL-mediated cell lysis to gastric cancer cells of the lines KATO-III and SGC-7901 was analyzed in vitro by standard (51)Cr releasing assay. Heparinase specific CTL were co-cultured with KATO-III and SGC-7901 cells, and then ELISA was used to detect the IFN-gamma release.

Expression of heparanase was significantly increased in the DCs transfected with heparinase recombinant adenovirus. Heparanase specific CTL generated from the genetically modified DC vaccine exhibited potent lysis to the KATO-III gastric cancer cells positive in both heparinase and HLA-A2 at each E/T ratio, whereas, these heparinase specific CTL could not lyse the SGC-7901 cells positive to heparinase but negative to HLA-A2, with a specific lysis rate of only 11.1% +/- 4.6% even at an E:T ratio of 40:1. Further study showed that heparanase vaccination had no detectable lysis on the autologous lymphocytes in vitro with a specific lysis rate of only 11.4% +/- 7.9% even at an E:T ratio of 40:1. The IFN-gamma release amount when the heparanase specific CTL were co-cultured with the KATO-III cells was 280.4 pg/ml +/- 23.5 pg/ml, significantly higher than that when the heparanase specific CTL were co-cultured with the rAd5-Lacz modified DC (120.6 pg/ml +/- 18.9 pg/ml), and that of the IL-2 stimulated T cells (60.0 pg/ml +/- 10.6 pg/ml, both P < 0.05). In contrast the IFN-gamma release amounts of the SGC-7901 cells and autologous lymphocytes remained unchanged when they were co-cultured with either above-mentioned effector cells (both P > 0.05).

DC genetically modified by heparanase gene activate heparanase specific CTL and induce potent immune response against HLA-matched and heparinase positive gastric cancer cells in vitro, whereas they have no killing effect on autologous lymphocytes. Heparanase is an effective and safe target for immunogen therapy of tumor, thus providing a new biotherapy method for advanced gastric cancer.