Fusobacterium nucleatum induces excess methyltransferase‐like 3‐mediated microRNA‐4717‐3p maturation to promote colorectal cancer cell proliferation

Fusobacterium nucleatum infection plays vital roles in colorectal cancer (CRC) progression. Overexpression of microRNA‐4717‐3p (miR‐4717) was reported to be upregulated in F. nucleatum positive CRC tissues, however, the underlying mechanism is unknown. In this study, we found that miR‐4717 promoted CRC cell proliferation in vitro and growth of CRC in vivo following F. nucleatum infection. MicroRNA‐4717 suppressed the expression of mitogen‐activated protein kinase kinase 4 (MAP2K4), a tumor suppressor, by directly targeting its 3′‐UTR. Furthermore, we confirmed that methyltransferase‐like 3 (METTL3)‐dependent m(6)A methylation could methylate primary (pri)‐miR‐4717, which further promoted the maturation of pri‐miR‐4717, and METTL3 positively regulated CRC cell proliferation through miR‐4717/MAP2K4 pathways. In conclusion, F. nucleatum‐induced miR‐4717 excessive maturation through METTL3‐dependent m(6)A modification promotes CRC cell proliferation, which provides a potential therapeutic target and diagnostic biomarker for CRC.