Gracillin induces mitochondria-mediated apoptosis on pancreatic ductal adenocarcinoma through disruption of redox homeostasis via inhibiting NRF2/HO-1 antioxidant axis

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with limited treatment options and poor patient survival. Despite the use of combination chemotherapy regimens, including FOLFIRINOX and gemcitabine-based therapies, the majority of patients experience relapse, underscoring the urgent need for novel therapeutic strategies. Gracillin, a natural triterpenoidal saponin, has demonstrated anticancer potential in various malignancies; however, its effects on PDAC and underlying molecular mechanisms remain unexplored. In this study, we provide the first comprehensive investigation of the anticancer properties of gracillin in PDAC. Our findings demonstrate that gracillin effectively inhibits PDAC cell viability, induces mitochondria-mediated apoptosis, and promotes oxidative damage by disrupting intracellular redox homeostasis. Mechanistically, gracillin exerts its effects by inhibiting the NRF2/HO-1 antioxidant axis, leading to excessive reactive oxygen species (ROS) accumulation and mitochondrial dysfunction. Molecular docking and molecular dynamics simulations further revealed a strong binding affinity between gracillin and NRF2, suggesting that gracillin may act as a direct NRF2 inhibitor. To further validate that anticancer effects of gracillin are mediated through NRF2 inhibition, we also assessed the impact of combining gracillin treatment with siRNA-mediated NRF2 silencing. Additionally, we found that gracillin enhances the cytotoxicity of gemcitabine, exhibiting a synergistic effect in PDAC cells. Finally, in vivo xenograft studies confirmed the tumor-suppressive effects of gracillin, further validating its potential as an effective therapeutic agent for PDAC. Overall, our study elucidates the potential of gracillin as a promising anticancer agent targeting the NRF2/HO-1 axis to disrupt redox homeostasis in PDAC. These findings provide new insights into the development of NRF2-targeted therapies for overcoming chemoresistance in PDAC.