The role of neutrophil extracellular traps in cancer progression and metastasis

Neutrophil extracellular traps (NET) are the extracellular release of decondensed chromatin and granules known for their role in host defense against foreign pathogens. However, a novel and predominantly pro-tumorigenic role of NETs in cancer is emerging. Tumors induce NET formation through the secretion of an array of tumor and infection-derived factors. NET deposition favors tumor cell proliferation, immunosuppression and cancer-associated thrombosis. Moreover, NETs enhance metastasis by contributing to epithelial-to-mesenchymal transition. A mesenchymal transition in tumor cells potentiates their migratory and invasive abilities. Circulating NETs capture circulating tumor cells and increase vascular permeability, thereby promoting tumor cell intravasation and establishment of micrometastasis. NETs present in pre-metastatic niches serve as cytokines in the recruitment of tumor cells through CCDC25. Through NET-mediated laminin remodelling, dormant cells are reawakened favoring metastatic growth. Moreover, post-operative infection results in high NET deposition and exacerbates post-surgical cancer progression and recurrence. Anti-NET therapies are in use for autoimmune diseases and are now being investigated in the context of cancer. The hope is that anti-NET therapies may synergize with existing anti-cancer therapy to increase rate of response given their multi-faceted interplay in several domains of cancer progression.