Repurposing thioridazine for inducing immunogenic cell death in colorectal cancer via eIF2α/ATF4/CHOP and secretory autophagy pathways

Colorectal cancer (CRC) is a highly prevalent cancer type with limited targeted therapies available and 5-year survival rate, particularly for late-stage patients. There have been numerous attempts to repurpose drugs to tackle this problem. It has been reported that autophagy inducers could augment the effect of certain chemotherapeutic agents by enhancing immunogenic cell death (ICD). In this study, we employed bioinformatics tools to identify thioridazine (THD), an antipsychotic drug, and found that it could induce autophagy and ICD in CRC. Then in vitro and in vivo experiments were performed to further elucidate the molecular mechanism of THD in CRC. THD was found to induce endoplasmic reticulum (ER) stress in CRC cells by activating the eIF2α/ATF4/CHOP axis and facilitating the accumulation of secretory autophagosomes, leading to ICD. In addition, THD showed a remarkable ICD-activating effect when combined with oxaliplatin (OXA) to prevent tumor progression in the mouse model. Together, our findings suggest that the repurposed function of THD in inhibiting CRC involves the upregulation of autophagosomes and ER stress signals, promoting the release of ICD markers, and providing a potential candidate to enhance the clinical outcome for CRC treatment. Video Abstract.