The therapeutic efficacy of fusion cell (FC)-based
cancer vaccine generated with whole
tumor cells and dendritic cells (DCs) requires the improved immunogenicity of both cells. Treatment of whole
tumor cells with
ethanol resulted in blockade of immune-suppressive soluble factors such as
transforming growth factor (TGF)-β1,
vascular endothelial growth factor, and
IL-10 without decreased expression of major histocompatibility complex (MHC) class I and the MUC1
tumor-associated
antigen. Moreover, the
ethanol-treated
tumor cells expressed "eat-me" signals such as
calreticulin (CRT) on the cell surface and released immunostimulatory factors such as
heat shock protein (HSP)90α and high-mobility group box 1 (
HMGB1). A dual stimulation of
protein-bound
polysaccharides isolated from Coriolus versicolor (TLR2 agonist) and
penicillin-inactivated Streptococcus pyogenes (TLR4 agonist) led human monocyte-derived DCs to produce HSP90α and multiple
cytokines such as IL-12p70 and
IL-10. Interestingly, incorporating
ethanol-treated
tumor cells and TLRs-stimulated DCs during the fusion process promoted fusion efficiency and up-regulated
MHC class II molecules on a per fusion basis. Moreover, fusions of
ethanol-treated
tumor cells and dual TLRs-stimulated DCs (E-
tumor/FCs) inhibited the production of multiple immune-suppressive soluble factors including TGF-β1 and up-regulated the production of IL-12p70 and HSP90α. Most importantly, E-
tumor/FCs activated T cells capable of producing high levels of IFN-γ, resulting in augmented MUC1-specific CTL induction. Collectively, our results illustrate the synergy between
ethanol-treated whole
tumor cells and dual TLRs-stimulated DCs in inducing augmented CTL responses in vitro by FC preparations. The alternative system is simple and may provide a platform for adoptive immunotherapy.