The role of ferroptosis in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a highly heterogeneous and aggressive malignancy of the bile ducts, characterized by a poor prognosis and high mortality rate. Despite advancements in treatment, effective targeted therapies and reliable prognostic biomarkers remain limited. Ferroptosis, a regulated form of cell death, has emerged as a potential therapeutic target in various cancers. However, its role in CCA remains poorly understood. In this study, we conducted a comprehensive analysis of ferroptosis-related genes (FRGs) to predict the prognosis of CCA and identify potential therapeutic targets. Using the least absolute shrinkage and selection operator (LASSO) Cox regression analysis on a training dataset, followed by validation in four independent public datasets, we developed a six-FRG signature that stratified CCA patients into low-risk and high-risk groups based on survival outcomes. High-risk patients exhibited shorter overall survival and were associated with fluke infection, advanced clinical stages, elevated cancer-associated fibroblast (CAF) scores, and increased expression of CAF markers. The FRG signature also estimated drug sensitivity, predicting potentially effective drugs in each CCA patient. Furthermore, validation of the FRG signature in ten CCA cell lines confirmed its ability to classify CCA cell lines into low-risk and high-risk groups, with high-risk cell lines exhibiting resistance to ferroptosis inducers, including erastin and RSL3. Further analysis identified acyl-CoA synthetase long-chain family member 3 (ACSL3) as a key ferroptosis suppressor in high-risk CCA. ACSL3 was upregulated in high-risk cell lines and associated with increased levels of monounsaturated fatty acid (MUFA)-containing phospholipids, which conferred resistance to ferroptosis. Silencing ACSL3 sensitized high-risk cell lines to RSL3, whereas ferroptosis resistance was enhanced by MUFA supplementation and lipid droplet biogenesis inhibition. These findings suggest that ferroptosis resistance in high-risk CCA is mediated by ACSL3, highlighting its role as a potential therapeutic target. Collectively, our study constructed a novel FRG signature model that can predict CCA prognosis and potential therapeutic targets and identified ACSL3 as a critical driver of ferroptosis resistance. This work offers new insights into the mechanisms of ferroptosis in CCA and suggests that targeting ferroptosis pathways, particularly ACSL3-mediated resistance, could be a promising strategy for precision therapy in CCA patients.