Tumor-associated neutrophils (TANs) in human carcinoma-draining lymph nodes: a novel TAN compartment.

OBJECTIVES

The role of tumor-associated neutrophils (TANs) in the nodal spread of cancer cells remains unexplored. The present study evaluates the occurrence and clinical significance of human nodal TANs.

METHODS

The relevance, derivation, phenotype and interactions of nodal TANs were explored a large immunohistochemical analysis of carcinoma-draining lymph nodes, and their clinical significance was evaluated on a retrospective cohort of oral squamous cell carcinomas (OSCC). The tumor-promoting function of nodal TAN was probed in the OSCC TCGA dataset combining TAN and epithelial-to-mesenchymal transition (EMT) signatures.

RESULTS

The pan-carcinoma screening identified a consistent infiltration (59%) of CD66b  TANs in tumor-draining lymph nodes (TDLNs). Microscopic findings, including the occurrence of intra-lymphatic conjugates of TANs and cancer cells, indicate that TANs migrate through lymphatic vessels. experiments revealed that OSCC cell lines sustain neutrophil viability and activation via release of GM-CSF. Moreover, by retrospective analysis, a high CD66b TAN density in M-TDLNs of OSCC ( = 182 patients) predicted a worse prognosis. The analysis of the OSCC-TCGA dataset unveiled that the expression of a set of neutrophil-specific genes in the primary tumor (PT) is highly associated with an EMT signature, which predicts nodal spread. Accordingly, in the PT of OSCC cases, CD66bTANs co-localised with PDPNS100A9 EMT-switched tumor cells in areas of lymphangiogenesis. The pro-EMT signature is lacking in peripheral blood neutrophils from OSCC patients, suggesting tissue skewing of TANs.

CONCLUSION

Our findings are consistent with a novel pro-tumoral TAN compartment that may promote nodal spread EMT, through the lymphatics.