Role and Mechanisms of Neutrophil ExtracellularTraps in Hepatocellular Carcinoma Metastasis

HCC (hepatocellular carcinoma) is an inflammation-related cancer, and the tumor immune microenvironment plays a crucial role in the occurrence and development of HCC. This study aims to investigate therole and related mechanisms of NETs (neutrophil extracellular traps) in HCC metastasis. The levels of NETs inserum and tumor tissues of HCC patients were detected by ELISA and immunohistochemistry to examine the correlation between NETs and liver cancer metastasis. In in vitro experiments, a co-culture model of NETs and HCCcell lines Hep3B and CSQT-2 was established, and the effects of NETs on HCC cell migration were investigatedthrough scratch assays and Transwell experiments. In in vivo experiments, a tail vein injection metastasis modelwas established, and NETs formation was induced in mice using lipopolysaccharide. The effects of NETs on tumormetastasis were examined by evaluating liver pathological changes and levels of Ki67 protein in the liver. Finally,to explore the mechanisms by which NETs influence HCC metastasis, the modification of extracellular matrix byNETs was detected using mass spectrometry, and the effects of the modified extracellular matrix protein on the integrin/FAK signaling pathway were assessed. The results showed that the levels of MPO (myeloperoxidase) proteinwere higher in tumor tissues of high-metastatic HCC patients, and the levels of MPO and neutrophil elastase in theserum of advanced HCC patients were elevated compared to early HCC patients. Co-culture of NETs with Hep3Band CSQT-2 cells promoted the migration ability of these cells in vitro. NETs promoted inflammatory cell infiltration in the liver of C57BL/6 mice in vivo. After tail vein injection of metastatic tumors, induction of NETs led toan increase in Ki67 protein levels in liver tissue, indicating that NETs promote liver metastasis of HCC cells. Theinhibition of NETs release by ATRA can alleviate the NETs-mediated promotion of migration and proliferation.Mechanistic studies found that NETs generated hypochlorous acid, which resulted in tyrosine chlorination modification of the laminin C1 peptide segment LKDYEDLR in the extracellular matrix. Moreover, hypochlorous acidtreated LAMC1 led to activation of the integrin/FAK signaling pathway. Therefore, this study confirms that NETscan promote HCC metastasis, and its mechanism is associated with ECM remodeling induction and regulation ofthe Integrin/FAK signaling pathway.