Fusobacterium nucleatum outer membrane vesicles activate the TNFR1/NF-κB signaling pathway to promote OSCC proliferation

Fusobacterium nucleatum (F. nucleatum, Fn) has emerged as a significant bacterium linked to cancer. However, the precise mechanisms by which Fn drives the progression of oral squamous cell carcinoma (OSCC) remain obscure. Outer membrane vesicles (OMVs), small vesicular structures secreted by Gram-negative bacteria, are known to contribute to their pathogenicity. This study investigated the role of Fn OMVs in oral cancer progression and the underlying mechanisms.

Metagenomic sequencing was conducted on both oral cancer and control tissues. OMVs were isolated through ultracentrifugation. Cell proliferation assays on two cancer cell lines assessed the impact of Fn and its OMVs. Fn OMVs were administered to mice to evaluate their influence on tumorigenesis. RNA-seq was performed on OMV-treated cells to identify enriched genes, which were validated via qPCR and Western blot. Knockdown experiments were executed in vitro and in vivo to confirm the involvement of Fn OMVs in TNFR1-mediated NF-κB signaling.

Fn prevalence was markedly higher in oral cancer tissues compared to non-cancerous samples. In vitro, Fn and its OMVs significantly enhanced the growth and proliferation of oral cancer cell lines. Mice treated with Fn OMVs developed larger tumors than those receiving Fn alone. Furthermore, Fn OMVs notably induced TNFR1 expression and activated the NF-κB signaling pathway, as confirmed by RNA-seq, qPCR, and Western blot. TNFR1 knockdown significantly diminished the effects of Fn OMVs on cancer cell proliferation in vitro and tumor formation in vivo.

This study compellingly demonstrates that Fn OMVs are pivotal in OSCC progression by directly activating TNFR1-mediated NF-κB signaling. These findings pave the way for future research into the prevention and treatment of oral cancer. Competing Interest Statement The authors have declared no competing interest.