Lung Adenocarcinoma Promotes NETosis via the NPM1–TNFAIP6–CD44–SPP1 Axis

<b>Background:</b> While neutrophil extracellular traps (NETs) have been shown to contribute to cancer progression, including that of lung adenocarcinoma, the mechanisms underlying NET formation within the tumor immune microenvironment (TIME) remain incompletely understood. Notably, neutrophil infiltration has been strongly linked to tumor necrosis factor alpha-inducible protein 6 (TNFAIP6) expression. <b>Methods:</b> In vitro and in vivo experiments were performed. DNA pulldown coupled with mass spectrometry, bioinformatics analyses, immunohistochemistry, and dual-luciferase reporter assays were conducted. DNA pulldown Western blotting, chromatin immunoprecipitation-quantitative PCR, and dual-luciferase reporter assays using truncated promoter constructs were also employed. <b>Results:</b> TNFAIP6 expressed by lung adenocarcinoma cells was shown to induce NET formation (a form of programmed cell death called NETosis). Mechanistically, TNFAIP6 interacted with CD44 in lung adenocarcinoma cells, leading to increased extracellular availability of secreted phosphoprotein 1 (SPP1) within the TIME and the subsequent promotion of NETosis. Additionally, nucleophosmin 1 (NPM1) significantly enhances the transcriptional activation of <i>TNFAIP6</i> and associates with the -2000 to -1700 bp region of its promoter. <b>Conclusions:</b> These findings delineate a regulatory model in which lung adenocarcinoma cells directly stimulate NETosis through the NPM1-TNFAIP6-CD44-SPP1 axis, suggesting that therapeutic targeting of this pathway may attenuate tumor progression.