Fap2 Mediates Fusobacterium nucleatum Colorectal Adenocarcinoma Enrichment by Binding to Tumor-Expressed Gal-GalNAc

Fusobacterium nucleatum is associated with colorectal cancer and promotes colonic tumor formation in preclinical models. However, fusobacteria are core members of the human oral microbiome and less prevalent in the healthy gut, raising questions about how fusobacteria localize to CRC. We identify a host polysaccharide and fusobacterial lectin that explicates fusobacteria abundance in CRC. Gal-GalNAc, which is overexpressed in CRC, is recognized by fusobacterial Fap2, which functions as a Gal-GalNAc lectin. F. nucleatum binding to clinical adenocarcinomas correlates with Gal-GalNAc expression and is reduced upon O-glycanase treatment. Clinical fusobacteria strains naturally lacking Fap2 or inactivated Fap2 mutants show reduced binding to Gal-GalNAc-expressing CRC cells and established CRCs in mice. Additionally, intravenously injected F. nucleatum localizes to mouse tumor tissues in a Fap2-dependent manner, suggesting that fusobacteria use a hematogenous route to reach colon adenocarcinomas. Thus, targeting F. nucleatum Fap2 or host epithelial Gal-GalNAc may reduce fusobacteria potentiation of CRC. [Display omitted] •Gal-GalNAc is highly expressed in human CRC, metastases, and a preclinical CRC model•Fap2 is a fusobacterial Gal-GalNAc-binding lectin•Fap2 mediates F. nucleatum binding to Gal-GalNAc overexpressed in CRC•Blood-borne Fap2-expressing F. nucleatum localizes to orthotopic mouse colon tumors F. nucleatum is associated with CRC and promotes colonic tumor formation in mice. Abed et al. identify a host polysaccharide, Gal-GalNAc, and fusobacterial lectin (Fap2) that explicates fusobacteria abundance in CRC. Targeting Fap2 or host Gal-GalNAc may provide a means to reduce F. nucleatum potentiation of CRC.