Tramadol Triggers Paraptotic Cell Death through ATF4 in Breast Cancer Cells

Breast cancer treatment has significantly improved, achieving a five-year survival rate of 90%. However, 30% to 50% of survivors continue to suffer from persistent pain, a common long-term side effect. Tramadol, an analgesic often prescribed for postsurgical pain, has recently been shown to have anticancer effects on breast cancer cells. The use of tramadol in postoperative care has been associated with reduced recurrence and improved survival rates, but the mechanisms involved in its anticancer activity are not fully understood. This study explored how tramadol induces paraptosis, a form of nonapoptotic cell death, by focusing on endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) pathways in breast cancer cells. The findings revealed that tramadol treatment increased ROS levels, triggering ER stress and activating the p-eIF2α/ATF4/CHOP signaling axis. This stress response led to cytoplasmic vacuolization and mitochondrial dysfunction, both of which are key features of paraptosis. Inhibiting ROS production or blocking the ATF4 pathway reduced tramadol-induced paraptosis, confirming the critical role of these mechanisms in breast cancer cells. In summary, tramadol induces paraptosis in breast cancer cells by activating ROS and ER stress, offering potential insight into its anticancer effects. These findings could have implications for improving both pain management and cancer treatment outcomes in breast cancer patients.