Oxidative stress-mediated non-apoptotic, non-autophagic cell death: A mechanistically distinct strategy to overcome resistance in colorectal cancer cells

Cancer remains a leading cause of mortality worldwide, with therapeutic failure often driven by apoptosis resistance a major hurdle that limits the efficacy of conventional anticancer therapies. Targeting alternative, caspase-independent cell death pathways has emerged as a promising strategy to overcome this resistance. In this study, we evaluated the effects of two mechanistically distinct small molecules a BCL-XL inhibitor and an NRF2 activator on colorectal cancer cell lines to investigate their ability to induce non-apoptotic cell death. Both agents reduced cell viability in a dose- and time-dependent manner. The NRF2 activator triggered cytoplasmic vacuolation at lower concentrations, characteristic of paraptosis, accompanied by endoplasmic reticulum (ER) dilation, oxidative stress, and downregulation of Alix, a key inhibitor of paraptosis. This mode of cell death required de novo protein synthesis and was independent of caspase activation, PARP cleavage, and DNA fragmentation. In contrast, the BCL-XL inhibitor displayed a dose-dependent switch between vacuolation-induced cell death and classical apoptosis, marked by phosphatidylserine externalization and DNA fragmentation. These findings underscore oxidative stress-mediated, vacuolation-associated non-apoptotic cell death as a mechanistically distinct and therapeutically relevant modality for targeting apoptosis-resistant cancer cells. This approach may pave the way for innovative cancer therapies that exploit tumor redox vulnerabilities while bypassing traditional cell death pathways.