Mechanism of Fusobacterium nucleatum via Regulating miR-181b for Forming An Inflammatory Microenvironment in Colon Cancer Cells / 胃肠病学

ABSTRACT

Background:Fusobacterium nucleatum (Fn)is a common oral pathogen. Studies have shown that Fn is closely related to the occurrence and development of colorectal cancer,especially the inflammation-related colorectal cancer. Aims:To investigate the mechanism of Fn in forming an inflammatory microenvironment in colon cancer cells. Methods:An inflammation model of Caco-2 cells infected by Fn was constructed,and miRNA sequencing was performed. miR-181b mimics or inhibitor was transfected into Fn infected Caco-2 cells. mRNA and protein expressions of TNF-α were determined by qRT-PCR and Western blotting,respectively,and concentration of TNF-α in supernatant was measured by ELISA, number of lymphocyte penetrating the membrane was measured by Transwell chamber. Results:Compared with control group,mRNA and protein expressions of TNF-α were significantly increased (P < 0. 05),concentration of TNF-α in supernatant was significantly increased (P < 0. 05),and number of lymphocyte penetrating the membrane was significantly increased in Fn group (P < 0. 05). miRNA sequencing and qRT-PCR results showed that expression of miR-181b was significantly decreased in Fn group than in control group (P < 0. 05). Compared with control group,mRNA and protein expressions of TNF-α were significantly decreased in miR-181b mimics + Fn group (P < 0. 05),however,mRNA and protein expressions of TNF-α were significantly increased in miR-181b inhibitor group (P < 0. 05). Bioinformatics tools and Luciferase assay confirmed that TNF-α might be the target gene of miR-181b in Caco-2 cells. Conclusions:Fn can up-regulate the expression of TNF-α by inhibiting miR-181b in Caco-2 cells and recruiting lymphocytes to form an inflammatory microenvironment.