Neutrophils promote tumor invasion via FAM3C-mediated epithelial-to-mesenchymal transition in gastric cancer

In gastric cancer, lymph node metastasis (LNM) is the major metastasis route, and lymphatic invasion is the precursor of LNM. Tumor-associated neutrophils (TANs) promote LNM. However, the molecular mechanisms underlying TANs-mediated lymphatic invasion and/or LNM remain unclear. Herein, we revealed that high level of TANs was the independent risk factor for lymphatic invasion and LNM respectively, and lymphatic tumor cell-neutrophil clusters were positively correlated with LNM. Crosstalk between neutrophils and tumor cells was required for enhanced tumor cell invasiveness, endowing neutrophils to boost epithelial-to-mesenchymal transition (EMT) of tumor cells and in turn promoting LNM. Mechanically, tumor cells educated neutrophils via TGF beta 1 to produce more FAM3C through Smad2/3 signaling activation, and FAM3C promoted tumor cell EMT through JNK-ZEB1/Snail signaling pathway. The crosstalk enhanced the affinity of neutrophils with tumor cells through interaction of integrins alpha 6 beta 1 and alpha 6 beta 4 with CD151. Furthermore, studies using tumor-bearing mice demonstrated that neutrophils were the important driver for gastric cancer tumorigenesis and invasiveness. The study clearly identifies the functional roles of TANs in promoting tumor invasion, and facilitates a better understanding of novel mechanisms responsible for LNM of gastric cancer, which provides potential targets for developing new strategies to prevent or treat LNM in gastric cancer.

Automated summary

In gastric cancer, tumor-associated neutrophils (TANs) promote lymph node metastasis (LNM) through enhancing tumor cell invasiveness and epithelial-to-mesenchymal transition (EMT). The crosstalk between neutrophils and tumor cells is mediated by various signaling pathways including TGF beta 1, FAM3C, and JNK-ZEB1/Snail, and involves interaction of integrins alpha 6 beta 1 and alpha 6 beta 4 with CD151. Studies using tumor-bearing mice confirm the importance of neutrophils in gastric cancer tumorigenesis and invasiveness. Understanding the functional roles of TANs in promoting tumor invasion provides potential targets for developing strategies to prevent or treat LNM in gastric cancer.