The bovine dialysable leukocyte extract IMMUNEPOTENT CRP induces immunogenic cell death in breast cancer cells leading to long-term antitumour memory

Abstract

Abstract Background Cancer recurrence is a serious problem in breast cancer (BC) patients, and immunogenic cell death (ICD) has been proposed as a strategy to overcome this recurrence. IMMUNEPOTENT CRP (ICRP) acts as an immunomodulator and can be cytotoxic to cancer cells. Thus, we evaluated if ICRP induces ICD in BC cells. Methods Immunogenicity of ICRP-induced cell death was evaluated in vitro, analysing the principal biochemical characteristics of ICD in MCF-7, MDA-MB-231 and 4T1 cells. Ex vivo, we assessed the ability of killed cancer cells (KCC) obtained from ICRP-treated 4T1 cells (ICRP-KCC) to induce DC maturation, T-cell priming and T-cell-mediated cancer cytotoxicity. In vivo, we evaluated tumour establishment and antitumour immune memory after prophylactic ICRP-KCC vaccination in BALB/c mice. Results ICRP induced caspase-independent, ROS-dependent cell death, autophagosome formation, P-eIF2α, chaperone protein exposure, CD47 loss, ATP and HMBG1 release in BC cells. Additionally, ICRP-KCC promoted DC maturation, which triggered T-cell priming and cancer cytotoxicity. Prophylactic vaccination with ICRP-KCC prevented tumour establishment and induced long-term antitumour memory in BALB/c mice, involving DC maturation in lymph nodes, CD8+ T-cell augmentation in lymph nodes, peripheral blood and tumour site and ex vivo tumour-specific cytotoxicity by splenocytes. Conclusions ICRP induces ICD in BC cells, leading to long-term antitumour memory.