miR-320d Is Associated with Reduced Nasopharyngeal Carcinoma Progression, Potentially through the NF-κB/IL-8 Axis-Mediated Inhibition of Neutrophil Extracellular Trap Formation.

Objectives: Nasopharyngeal carcinoma (NPC) is an aggressive head and neck malignancy in which post-treatment recurrence and distant metastasis remain major contributors to poor clinical outcomes. Although microRNAs are important post-transcriptional regulators of tumor progression, the role of miR-320d in NPC remains incompletely understood. This study evaluated the biological role of miR-320d and explored whether it is involved in regulating neutrophil extracellular trap (NET) formation through the nuclear factor kappa-B (NF-κB)/interleukin-8 (IL-8) signaling axis. Methods: miR-320d was overexpressed in NPC cell lines S18 and 5-8F, and cell viability, migration, and invasion were evaluated. Integrated transcriptomic and proteomic analyses were performed to identify miR-320d-regulated genes, proteins, and pathways. Western blotting, immunohistochemistry, and immunofluorescence analyses were used to validate NET-associated proteins, including glycoprotein Ib platelet subunit alpha (GP1BA), histone deacetylase 10 (HDAC10), and fibrinogen gamma chain (FGG), as well as the expression of NET formation markers, including peptidyl arginine deiminase 4 (PADI4), myeloperoxidase (MPO), and neutrophil elastase (NE); and key components of the NF-κB/IL-8 axis. Results: miR-320d overexpression significantly inhibited the viability, migration, and invasion of both S18 and 5-8F cells. Multi-omics analyses indicated that miR-320d-regulated molecules were mainly enriched in NET-related pathways. Consistently, miR-320d reduced the expression of GP1BA, HDAC10, FGG, PADI4, MPO, and NE. Mechanistically, miR-320d suppressed NF-κB signaling, as shown by decreased phosphorylated NF-κB (p-NF-κB) and total NF-κB levels, and reduced IL-8 secretion in NPC cells. Conclusion: miR-320d may suppress NPC progression, at least in part, by attenuating NF-κB/IL-8-associated NET formation. These findings suggest that the miR-320d/NF-κB/IL-8/NET regulatory axis may participate in NPC progression and may warrant further translational investigation.