Curcumin induces immunogenic cell death in murine colorectal carcinoma CT26 cells

Different stressors of the endoplasmic reticulum (ER) can trigger immunogenic cell death (ICD), a modality of regulated cell death that can be therapeutically used to induce antitumor immune responses. Curcumin has been pointed out as an ER stressor, but its potential activity as an ICD inducer has not been studied. Thus, the goal of this work was to investigate whether curcumin triggers ICD in murine colorectal carcinoma CT26 cells in vitro. The results show that CT26 cells treated with curcumin underwent apoptosis and exposed damage-associated molecular patterns, namely calreticulin, HSP90, HMGB1, ATP and IL-1β. Curcumin-treated CT26 cells also exhibited increased expression of XBP1, which is suggestive of ER stress. In an in vivo vaccination-challenge model, curcumin-treated CT26 cells were immunogenic, rendering 80 to 100% of the BALB/c mice resistant to a subsequent challenge with viable CT26 cells. Taken together, these results suggest that curcumin is an ICD inducer and can potentially be used to induce antitumor immune responses.