Gemcitabine-induced neutrophil extracellular traps via interleukin-8-CXCR1/2 pathway promote chemoresistance in pancreatic cancer

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers, and chemoresistance poses a significant challenge in its treatment. Neutrophil extracellular traps (NETs) have emerged as key players in the tumour microenvironment, but their role in chemoresistance remains unclear. METHODS: We investigated the involvement of NETs in PDAC chemoresistance using patient tumour samples, in vitro assays with gemcitabine (GEM)-treated PDAC cells, and in vivo mouse models. We evaluated cytokine production, NET formation and tumour response to GEM, with or without the CXCR1/2 inhibitor navarixin. RESULTS: NETs are significantly accumulated in the tumours of PDAC patients exhibiting poor response to chemotherapy. GEM-treated PDAC cells secrete pro-inflammatory cytokines such as interleukin-8 (IL-8). IL-8 promote the formation of chemotherapy-induced NETs (chemoNETosis) through activation of CXCR 1/2 on neutrophils. Importantly, treatment with navarixin significantly suppressed chemoNETosis, restored sensitivity to GEM, and significantly reduced tumour growth in vivo. CONCLUSIONS: Our findings reveal that NETs contribute to chemoresistance in PDAC and that IL-8-mediated chemoNETosis plays a pivotal role in this process. Inhibition of CXCR1/2-mediated NET formation enhances the efficacy of GEM. This approach may represent a promising therapeutic strategy for overcoming chemoresistance in PDAC. These results support further clinical investigation of anti-NETs therapies.