The role of Fusobacterium nucleatum in macrophage M2 polarization and NF-κB pathway activation in colorectal cancer

<i>Fusobacterium nucleatum</i> is strongly linked to colorectal cancer (CRC) progression, but its mechanisms for influencing macrophage polarization and tumor development are not well understood. We established an <i>in vitro</i> model of <i>F. nucleatum</i> infection in RAW264.7 macrophages to investigate these processes. Macrophage polarization was evaluated using scanning electron microscopy (SEM), real-time quantitative PCR (RT-qPCR), and immunofluorescence staining. RNA sequencing (RNA-Seq) identified differentially expressed genes (DEGs) and enriched pathways, focusing on the role of the NF-κB signaling pathway in macrophage polarization. <i>F. nucleatum</i> infection induced M2 polarization in RAW264.7 macrophages, as confirmed by SEM analysis and RT-qPCR validation. A total of 2,029 DEGs were identified after <i>F. nucleatum</i> infection, with 763 upregulated and 1,266 downregulated. GO and KEGG enrichment analysis showed that cytokine-cytokine receptor interaction, TNF signaling, and NF-κB signaling pathways are upregulated in macrophages after <i>F. nucleatum</i> infection, indicating enhanced cytokine activity and immune response. Key genes (<i>Nfkb1</i>, <i>Nfkb2</i>, <i>Malt</i>, <i>Lta</i>, <i>Ltb</i>, <i>Tnf</i>) and proteins (P50, P100) in the NF-κB pathway are upregulated, indicating the crucial role of the NF-κB pathway in M2 macrophage polarization. This study offers crucial evidence regarding the role of the NF-κB signaling pathway in modulating <i>F. nucleatum</i>-induced macrophage M2 polarization, underscoring its significance in the progression of colorectal cancer.