Arnicolide D induces endoplasmic reticulum stress-mediated oncosis via ATF4 and CHOP in hepatocellular carcinoma cells.

Endoplasmic reticulum (ER) stress can trigger various cell death mechanisms beyond apoptosis, providing promise in cancer treatment. Oncosis, characterized by cellular swelling and increased membrane permeability, represents a non-apoptotic form of cell death. In our study, we discovered that Arnicolide D (AD), a natural sesquiterpene lactone compound, induces ER stress-mediated oncosis in hepatocellular carcinoma (HCC) cells, and this process is reactive oxygen species (ROS)-dependent. Furthermore, we identified the activation of the PERK-eIF2α-ATF4-CHOP pathway during ER stress as a pivotal factor in AD-induced oncosis. Notably, the protein synthesis inhibitor cycloheximide (CHX) was found to effectively reverse AD-induced oncosis, suggesting ATF4 and CHOP may hold crucial roles in the induction of oncosis by AD. These proteins play a vital part in promoting protein synthesis during ER stress, ultimately leading to cell death. Subsequent studies, in where we individually or simultaneously knocked down ATF4 and CHOP in HCC cells, provided further confirmation of their indispensable roles in AD-induced oncosis. Moreover, additional animal experiments not only substantiated AD's ability to inhibit HCC tumor growth but also solidified the essential role of ER stress-mediated and ROS-dependent oncosis in AD's therapeutic potential. In summary, our research findings strongly indicate that AD holds promise as a therapeutic agent for HCC by its ability to induce oncosis.