Enhanced Induction of Anti-tumor CTLs in Vitro by a Lentivirus-tranduced Dendrtic Cell Vaccine Expressing Secondary Lymphoid Tissue Chemokine and Mucin 1

Aims: Dendritic cell (DC)-based cancer immunotherapy requires an immunogenic tumor associated antigen (TAA) and an effective strategy for its presentation to lymphocytes. Here, we explored whether transduction of DCs with lentiviruses (LVs) expressing a fusion protein of secondary lymphoid tissue chemokine (SLC) and mucin 1 (MUC1) could stimulate antigen-specific cytotoxic T cells (CTLs) to human cancer cells in vitro. Materials and methods: HLA-A2+ peripheral blood monocyte-derived DCs were transduced with recombinant lentiviruses LV at different multiplicities of infection (MOI), and MUC1, SLC or SLC-MUC1 mRNA and protein were detected by RT-PCR and Western blotting, respectively. Transduction efficiencies and phenotypes of DCs were evaluated by flow cytometry. Induction of T lymphocyte proliferation by DCs was examined with a Cell Count Kit-8 (CCK-8). CTL activities against tumor cells were analyzed by lactate dehydrogenase (LDH) cytotoxicity and enzyme-linked immunospot (ELISPOT) assays.
Results: Stable expression of MUC1, SLC and SLC-MUC1 was obtained in DCs transduced with recombinant LVs, and the transduction efficiencies were dose-dependent. Transduction with LVs did not appreciably change the DC phenotype. CTL induced by LV MUC1 DCs potently and specifically lysed the HLA-A2+, MUC1+ colon cancer cell line HCT-116. Moreover, this cytolytic activity against HCT-116 was enhanced with CTL stimulated by LV SLC-MUC1 DCs.
Conclusions: DCs transduced with MUC1 could induce effective cytolytic activity against tumor cells in an antigen-specific and HLA-restricted fashion in vitro, and SLC promoted MUC1-specific anti-tumor activity. The transduction of DCs with LV SLC-MUC1 may be a promising strategy in DC-based cancer immunotherapy.