Extracellular RNAs from lung cancer cells activate epithelial cells and induce neutrophil extracellular traps

Neutrophil infiltration is frequently observed in lung cancer tissues. Extracellular RNAs (exRNAs) may facilitate tumor progression. The present study investigated the cross-talk of tumor exRNAs and neutrophil extracellular traps (NETs) in lung cancer. Lewis lung carcinoma (LLC) cells were cultured with the deprived sera. And the cell culture supernatants (CCS) were analyzed in vitro and in vivo. The results revealed that exRNAs from lung cancer CCS promoted the inflammatory cytokine interleukin-1 beta and reduced the vascular cell adhesion molecule-1 expression in lung epithelial cells. Lung cancer CCS-treated epithelial cells induced the production of NETs. By contrast, NETs reduced the tight junction protein claudin-5 in epithelial cells. Furthermore, NETs caused the necrosis of epithelial cells, which resulted in the release of exRNAs. In mice, lung cancer cells instilled in the lung recruited neutrophils and initiated NETs. In patients with lung cancer, NETs were also observed. These results suggested that exRNAs in the cell culture supernatant may indirectly induce NETs and contribute to lung cancer oncogenesis.