METHODS: Highly purified human neutrophils (>99%) from healthy donors were stimulated, in vitro, with conditioned media derived from the TC cell lines TPC1 and 8505c (TC-CM). Neutrophil biological properties (e.g. chemotaxis, survival, activation, gene expression and protein release) were investigated.
RESULTS: Soluble factors derived from TC cell lines promoted neutrophil chemotaxis and survival. Neutrophil chemotaxis toward TC-CM was mediated by CXCL8/IL-8. Neutrophil survival induced by TC-CM was mediated by GM-CSF. Moreover, TC-CM induced neutrophil activation (CD11b and CD66b up-regulation, CD62L shedding), morphological changes and modified neutrophil kinetic properties. Furthermore, TC CM induced the release of reactive oxygen species (ROS), the expression of pro-inflammatory factors (CXCL8/IL-8, VEGF-A, TNF-α) and the release of matrix metalloproteinase-9 (MMP-9). In TC patients specimens, tumor-infiltrating neutrophils correlated with larger tumor size (r=0.43, p=0.01, Pearson correlation test).
CONCLUSIONS: TC cell lines produce soluble factors able to ‘educate’ neutrophils towards an activated functional state. Tumor-infiltrating neutrophils in TC patients correlated with tumor size. Further studies are in progress to elucidate the mechanisms underlying the roles of TANs in modifying TC behavior.