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.