Hepatocellular Carcinoma Cells Cotransfected With Chemokine And Costimulatory Molecule Genes Augment Antitumor Effect In Vivo

An important aspect of immunity is the recruitment and accumulation of lymphocytes into target tissues. All chemokine family members are chemotactic for selected populations of leukocytes. Another important aspect of immunity is to induce proliferation and cytokine production in T cells, and costimulatory molecules are thought to play an important role in priming T cells. Genetic modification of many types of tumor cells to express either costimulatory molecules, such as B7-1, 4-1 BB L, or chemokines, such as MIP-la, increases their immunogenicity. To augment antitumor effect in vivo, the combination treatment of hepatocellular carcinoma cells with costimulatory molecule genes and chemokine genes mediated by retrovirus was investigated.In this work we transfected hepal-6 cell line with mMIP-la, m4-lBBL or mB7-l gene respectively, more over, we also transfect the tumor cells with both mMIP-la and m4-lBBL genes. The expression of mMIP-la was confirmed by RT-PCR and immunohistochemistry; while the expression of m4-lBB L or mB7-l was confirmed by flow cytometry. When m4-lBB L or mB7-l transfected cells were used as stimulators of allogeneic spleen lymphocytes in mixed lymphocyte-tumor culture (MLTC), T-cell proliferation were significantly increased. Chemotaxis assay showed that mMIP -la modified cells can secreted substantial levels of chemokine activity for activated mouse spleen lymphocytes. None of the transfectants, including the multi-gene tranfectant showed altered grow rate in vitro. The injection of mMIP-la transfected tumor cells subcutaneously(s.c.) retarded tumour growth, while the injection of m4-lBBL or mB7-l transfectants prolonged the animal tumor bearing lifespan. All tumor-free animals developed long-term immunity against wild-type Hepal-6 but not against EL4. Mice inoculated with the mixture of w.t Hepal-6 and the chemokine/costimulatory molecule producing hepal-6 didn't develop tumor. Inflammatory cells infiltration were found in the inoculation sites of hepal-6 transfectants, while both CD8+ and CD4+ cells were detected. These results suggest that the combination of costimulatory gene and chemokine gene therapy can augment antitumor effect in vivo.