Clostridium butyricum inhibits the progression of colorectal cancer and alleviates intestinal inflammation via the myeloid differentiation factor 88 (MyD88)-nuclear factor-kappa B (NF-κB) signaling pathway

BACKGROUND: Clostridium butyricum (C. butyricum, CB) is a probiotic to modulate the intestinal disorders and CB supplement has been found to have a great impact on inflammation and cancer treatment. However, the effects and mechanisms of CB on colorectal cancer (CRC) are not clear. We performed this study to investigate the influence of CB on the progression of CRC and the potential mechanisms in vivo and in vitro. METHODS: We established azoxymethane (AOM)/dextran sulfate sodium salt (DSS) model mice (male, 6-week-old C57BL/6J) and divided them into the control (Ctrl) and CB groups at the end of the second DSS cycle. Mice in the CB group received treatment with CB [1×10(8) colony forming unit (CFU) in 100 µL phosphate buffered saline (PBS)] 3 times a week for 40 days by gavage administration. The apoptotic cells in tumor tissues were assessed by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. IL-6 and IL-10 were detected using enzyme linked immunosorbent assay (ELISA) assayes. Microbiota was analyzed through 16S rDNA sequencing. The location of CB was detected by the fluorescence in situ hybridization (FISH) assay. The function of CB on the proliferation of cell lines, HT-29 and CT-26, was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assayes. The expression of myeloid differentiation factor 88 (MyD88) and nuclear factor-kappa B (NF-κB) in cells and tissues was evaluated by real time quantitative PCR (RT-qPCR) and western blot. RESULTS: Mice in the CB group showed a lower incidence and total volume of CRC, more apoptotic cells in the tumor tissue, a lower level of IL-6, and a higher level of IL-10 compared with those in the Ctrl group. CB altered the composition of the gut microbiota and was enriched in the small intestine and tumor tissue. Moreover, CB restrained the proliferation and the expression of MyD88 and NF-κB in CRC cell lines and colon tissue. CONCLUSIONS: CB restrained the progression of CRC, improved the inflammation of AOM/DSS mice, altered the composition of their gut microbiota, and regulated the expression of MyD88 and NF-κB. We concluded that CB plays its role in CRC via MyD88 and the NF-κB signaling pathway.