Molecular Mechanisms of Neutrophil Extracellular Traps in Promoting Gastric Cancer Epithelial–Mesenchymal Transition Through SERPINE-1 Expression

Abstract

Gastric cancer remains a significant global health concern, with its progression and metastasis often associated with epithelial–mesenchymal transition (EMT). This study investigated the role of neutrophil extracellular traps (NETs) in promoting gastric cancer EMT by regulating SERPINE-1 expression, which encodes plasminogen activator inhibitor-1 (PAI-1). Western blot and immunohistochemistry were used to detect protein expression. Cell Counting Kit-8 was tested for cell proliferation ability using clones. The SERPINE-1 gene was knocked down using lentivirus. Immunofluorescence was used to detect the co-expression of proteins, and a Transwell assay and wound-healing assay were used to investigate the migration ability of cells. Experimental conclusions were verified in vivo using a nude mouse model. We first demonstrated overexpression of PAI-1 in gastric cancer tissues and cell lines. Subsequently, we found that NETs significantly enhanced the expression of EMT-related markers. These changes were accompanied by increases in cell invasion, migration, proliferation and tumour sphere formation. To further elucidate the mechanism, we employed lentivirus-mediated SERPINE-1 knockdown to reverse NET-induced EMT phenotype effectively. Mechanistically, we found that NETs activated the transforming growth factor (TGF)-β signalling pathway via PAI-1 as evidenced by increased expression of TGF-β1, TGF-βR1, TGF-βR2, phosphorylated Smad2/3 and Smad4. Finally, in vivo experiments using a nude mouse model of gastric cancer liver metastasis confirmed that NET-treated HGC-27 cells exhibited enhanced metastatic potential and SERPINE-1 knockdown abrogated metastatic potential. Our findings reveal a novel mechanism by which NETs promote EMT and metastasis in gastric cancer via the PAI-1–TGF-β axis. PAI-1 can be used as a potential target for the treatment of gastric cancer, and the expression of PAI-1 is closely related to the prognosis of patients with gastric cancer. Therapeutic strategies targeting NETs or PAI-1 may help prevent EMT and metastasis of gastric cancer and improve clinical outcomes in patients.