Sourcing the immune system to induce immunogenic cell death in Kras-colorectal cancer cells

Abstract

Background Current approaches aimed at inducing immunogenic cell death (ICD) to incite an immune response against cancer neoantigens are based on the use of chemotherapeutics and other agents. Results are hampered by issues of efficacy, combinatorial approaches, dosing and toxicity. Here, we adopted a strategy based on the use of an immunomolecule that overcomes pharmachemical limitations. Methods Cytofluorometry, electron microscopy, RT-PCR, western blotting, apotome immunofluorescence, MLR and xenografts. Results We report that an ICD process can be activated without the use of pharmacological compounds. We show that in Kras-mut/TP53-mut colorectal cancer cells the 15 kDa βGBP cytokine, a T cell effector with onco-suppressor properties and a potential role in cancer immunosurveillance, induces key canonical events required for ICD induction. We document ER stress, autophagy that extends from cancer cells to the corresponding xenograft tumours, CRT cell surface shifting, ATP release and evidence of dendritic cell activation, a process required for priming cytotoxic T cells into a specific anticancer immunogenic response. Conclusions Our findings provide experimental evidence for a rationale to explore a strategy based on the use of an immunomolecule that as a single agent couples oncosuppression with the activation of procedures necessary for the induction of long term response to cancer.

Intrinsic S phase checkpoint enforced by an antiproliferative oncosuppressor cytokine

“…Based on the evidence that βGBP is an effector molecule that normal cells use for self-regulation 10 , 12 and an enforcer of an S phase cytostatic block that drives cancer cells to apoptotic death 13 – 17 while instead enforcing reversible arrest in normal cells 10 , we hypothesized that under normal growth conditions βGBP may regulate transition through S phase. Here we report that in secondary cultures of murine embryonic fibroblasts a statutory checkpoint is indeed switched on within a defined time-window set in the early part of S phase via downregulation of signalling that while specific to the control of S phase in normal cells are downstream effectors of apoptotic cell death in cancer cells 18 , 19 .…”