<i>Fusobacterium nucleatum</i> supresses anti-tumor immunity by activating CEACAM1

Abstract

<i>Fusobacterium nucleatum (F. nucleatum</i>) is an oral anaerobe found to be enriched in colorectal cancer (CRC). Presence of <i>F. nucleatum</i> in CRC has been correlated with resistance to chemotherapy and poor prognosis. We previously demonstrated that the Fap2 outer-surface protein of <i>F. nucleatum</i> binds and activates the human inhibitory receptor TIGIT which is expressed by T and Natural Killer (NK) cells, and inhibits anti-tumor immunity. Here we show that <i>F. nucleatum</i> also binds and activates the human inhibitory receptor CEACAM1 leading to inhibition of T and NK cells activities. Our results suggest that using CEACAM1 and TIGIT inhibitors and specific targeting of fusobacteria should be considered for treating fusobacteria-colonized tumors.