A novel potential effective strategy for enhancing the antitumor immune response in breast cancer patients using a viable cancer cell-dendritic cell-based vaccine

Dendritic cells (DCs) have been used in a number of clinical trials for cancer immunotherapy; however, they have achieved limited success in solid tumors. Consequently the aim of the present study was to identify a novel potential immunotherapeutic target for breast cancer patients through in vitro optimization of a viable DC-based vaccine. Immature DCs were primed by viable MCF-7 breast cancer cells and the activity and maturation of DCs were assessed through measuring CD83, CD86 and major histocompatibility complex (MHC)-II expression, in addition to different T cell subpopulations, namely CD4⁺ T cells, CD8⁺ T cells, and CD4⁺CD25⁺ forkhead box protein 3 (Foxp3)⁺ regulatory T cells (Tregs), by flow cytometric analysis. Foxp3 level was also measured by enzyme-linked immunosorbent assay (ELISA) in addition to reverse-transcription quantitative polymerase chain reaction. The levels of interleukin-12 (IL-12) and interferon-γ (IFN-γ) were determined by ELISA. Finally, the cytotoxicity of cytotoxic T lymphocytes (CTLs) was evaluated through measuring lactate dehydrogenase (LDH) release by ELISA. The results demonstrated that CD83⁺, CD86⁺ and MHC-II⁺ DCs were significantly elevated (P<0.001) following priming with breast cancer cells. In addition, there was increased activation of CD4⁺ and CD8⁺ T-cells, with a significant decrease of CD4⁺CD25⁺Foxp3⁺ Tregs (P<0.001). Furthermore, a significant downregulation of FOXP3 gene expression (P<0.001) was identified, and a significant decrease in the level of its protein following activation (P<0.001) was demonstrated by ELISA. Additionally, significant increases in the secretion of IL-12 and IFN-γ (P=0.001) were observed. LDH release was significantly increased (P<0.001), indicating a marked cytotoxicity of CTLs against cancer cells. Therefore viable breast cancer cell-DC-based vaccines could expose an innovative avenue for a novel breast cancer immunotherapy.