Neutrophil Dynamics Contribute to Disease Progression and Poor Survival in Pancreatic Cancer.

Background: Tumor-promoting inflammation and immune evasion are hallmarks of cancer, contributing to the survival and proliferation of tumor cells. Infiltrating leukocytes and pro-inflammatory cytokines released into the tumor microenvironment (TME) often cause this inflammation and immune evasion. Neutrophils are leukocytes that contribute to inflammation and have immunomodulatory functions. They are shown to have pro- or anti-tumorigenic roles contingent on cancer type. Methods: In this study, we examined the role of neutrophil recruitment in pancreatic cancer (PC) progression using patient samples and murine models. Results: We observed enhanced neutrophil infiltration and neutrophil extracellular trap (NET) formation, which were dependent on disease stage and tumor site. Our murine model studies showed that the infiltration of neutrophils and NETs was dependent on disease progression. Moreover, chemokine receptor CXCR2 and its ligands played a crucial role in neutrophil recruitment. The expression of CXCR2 and its ligands was associated with a worse prognosis for patients. Conclusions: Our data demonstrates that gemcitabine therapy enhances neutrophil recruitment and NET formation in PC. In addition, we observed altered neutrophil phenotypes in PC dependent on disease progression, suggesting a context-dependent immunomodulatory role. Together, our data demonstrate that CXCR2-driven neutrophil recruitment increases with PC progression, is enhanced by gemcitabine chemotherapy, promotes an immunosuppressive microenvironment, and is associated with poor patient survival.