Type I interferons modulate autophagy to shape gemcitabine response in pancreatic cancer cells

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy characterized by poor prognosis and limited response to gemcitabine, the standard first-line chemotherapy. One major contributor to chemoresistance is autophagy, a process frequently upregulated in PDAC. In this study, we examined the ability of type I interferons (IFNα2b and IFNβ1a) to modulate autophagy and disturb tumor cell resistance to gemcitabine. PDAC cells were treated with increasing concentrations of IFNα2b or IFNβ1a, and cell proliferation was assessed by [3H]-thymidine incorporation. Apoptosis was evaluated by TUNEL staining following treatments with interferons and/or gemcitabine. STAT1 phosphorylation was analyzed as a marker of downstream type I interferon signaling. Autophagy was analyzed by western blot for LC3B, Beclin-1, Bcl-XL and p62/SQSTM1, and by quantifying autophagic flux using mCherry-EGFP-LC3B-transfected cells in the presence or absence of lysosomal inhibitors. We found that IFNα2b promoted autophagic flux and reduced gemcitabine-induced cell death, indicating a cytoprotective role. In contrast, IFNβ1a reduced autophagosome formation and significantly enhanced cell death, without clear evidence of altering autophagic flux. Both interferons induced STAT1 phosphorylation, confirming engagement of downstream type I interferon signaling. Our findings highlight the contrasting roles of IFNα2b and IFNβ1a in the regulation of autophagy and gemcitabine response and suggest that IFNβ1a, by reducing autophagosome formation, may sensitize PDAC cells to chemotherapy. These findings identify IFNβ1a as a potential chemosensitizing agent in PDAC and provide a rationale for further evaluating combinations of IFNβ1a, gemcitabine, and autophagy-targeting strategies to overcome chemoresistance.