Drug-induced oxidative stress actively prevents caspase activation and hepatocyte apoptosis

Cell death is a fundamental process for health and disease. Emerging research unveiled numerous distinct cell death modalities with similar and intertwined signaling pathways, but different outcomes, rising the need to understand the decision points during cell death signaling. Paracetamol (Acetaminophen, APAP)-induced hepatocyte death includes several apoptotic processes, but eventually ends as oncotic necrosis without any caspase activation. Here, we studied this paradoxical form of cell death and revealed that APAP not only fails to activate caspases, but also strongly impedes their activation upon classical apoptosis induction. We explored different hypotheses and deciphered that high oxidative stress consistently blocks caspase activity. Importantly, caspase inhibition and the associated switch from apoptotic to necrotic cell death is reversible through the administration of antioxidants. Thus, exemplified by APAP-induced cell death, our study stresses that the cellular redox status is a critical decision maker between different forms of cell death as it directly affects caspase activity.