Targeting cholangiocarcinoma with ferroptosis-inducing siRNA-based nanotherapeutics

Background : Cholangiocarcinoma (CCA) is a highly lethal epithelial cell malignancy of the hepatic biliary tract. Efficacy of current standard-of-care therapy is limited. Ferroptosis, an iron-catalyzed, caspase-independent cell death driven by phospholipid peroxidation, has emerged as a novel therapeutic target. Our goal is to develop a tumor-selective therapeutic approach targeting ferroptosis in CCA using siRNA-based nanotherapeutics. Materials & Methods : Milk-derived nanovesicles (lactosomes) coated with EpCAM aptamer and packaged with siRNA against Glutathione Peroxidase 4 (siGPX4-lactosomes) and Ferroptosis Suppressor Protein 1 (siFSP1-lactosomes), were used to induce ferroptosis in murine CCA cells (FAC) and in syngeneic liver orthotopic CCA-bearing mice. In vitro , lactosome uptake and efficacy were assessed by fluorescence-based, cell-viability and molecular biology assays. In vivo , target engagement, tissue distribution, safety and efficacy were assessed. Results : EpCAM (epithelial cell adhesion molecule expressed on CCA cells)-coated lactosomes showed robust uptake by FAC cells in a EpCAM-dependent manner. EpCAM knockdown via siRNA reduced lactosome uptake, confirming aptamer selectivity. Dose-dependent siGPX4/siFSP1-lactosome treatment led to GPX4/FSP1 knockdown and induced ferroptotic cell death in up to 60% of FAC cells after 72 hours (p<0.001 vs. siNC). In CCA-bearing mice, intravenous administration of siRNA lactosomes was well-tolerated with no liver or systemic toxicity observed and demonstrated robust tumor distribution compared to non-tumorous tissues. Efficacy studies demonstrated that siGPX4/siFSP1-lactosomes significantly reduced intratumor Gpx4 and FSP1 mRNA expression by 40-60% and induced significant upregulation of ferroptosis markers Ptgs2 and Acsl4 (p<0.01 vs. siNC). Ferroptosis in siRNA-lactosome treated tumors was confirmed by immunohistochemistry for phospholipid peroxidation markers oxPAPC and 4-HNE. Additionally, proliferation marker Ki67 was significantly downregulated in siGPX4/siFSP1-lactosome treated tumors (p<0.05 vs. siNC), indicating ferroptosis-mediated tumor suppression. Importantly, siGPX4/siFSP1-lactosomes reduced tumor burden and expression of CCA markers CK19/7 in treated mice, as compared to control mice. Conclusions : siRNA-based nanotherapeutics targeting CCA can effectively and safely induce ferroptosis in vitro and in vivo , representing a potential therapeutic strategy for CCA treatment.