Ferroptosis- and stemness inhibition-mediated therapeutic potency of ferrous oxide nanoparticles-diethyldithiocarbamate using a co-spheroid 3D model of pancreatic cancer.

[BACKGROUND] Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a high mortality rate and exhibits a limited response to apoptosis-dependent chemotherapeutic drugs (e.g., gemcitabine, Gem). This is mainly attributed to the antioxidant defense system (glutathione and aldehyde dehydrogenase (ALDH) 1A1), which sustains stemness features of cancer stem cells (CSCs) and activated pancreatic stellate cells (PSCs)-generated excess stromal proteins. This dense stroma retards drug delivery.

[METHODS] This study established co-spheroid model consisting of mouse PDAC cell line (KPC) and PSCs (1:5) to accurately investigate the anti-PDAC activity of nanocomplex of ferrous oxide nanoparticles-diethyldithiocarbamate (FeO NPs-DE), compared to Gem, using in vitro and in vivo 3D models.

[RESULTS] In vitro and in vivo co-spheroid models demonstrated higher therapeutic efficacy of FeO NPs-DE than Gem. FeO NPs-DE induced selective accumulation of iron-dependent ferroptosis (non-apoptosis)-generated a lethal lipid peroxidation that was potentiated by DE-mediated glutathione and ALDH1A1 suppression. This led to collapse of stemness, as evidenced by down-regulating CSC genes and p-AKT protein expression. Subsequently, gene and/or protein levels of PSC activators (transforming growth factor (TGF)-β, plasminogen activator inhibitor-1, ZEB1, and phosphorylated extracellular signal-regulated kinase) and stromal proteins (collagen 1A2, smooth muscle actin, fibronectin, and matrix metalloproteinase-9) were suppressed. Moreover, DE of nanocomplex enhanced caspase 3-dependent apoptosis with diminishing the main oncogene, BCL-2.

[CONCLUSIONS] FeO NPs-DE had a stronger eradicating effect than Gem on primary and metastatic peritoneal PDAC tumors. This nanocomplex-mediated ferroptosis and stemness inhibition provides an effective therapeutic approach for PDAC.