SPG-56 from Sweet potato Zhongshu-1 delayed growth of tumor xenografts in nude mice by modulating gut microbiota.

Graphical abstract Highlights • Gut microbes of nude mice treated with SPG-56 (a new glycoprotein) were detected by 16S NDA sequence analysis methods. • Species distribution and diversities at different taxonomic levels were studied. • Both vitro and vivo anti-colon cancer activities of Lactobacillus fermentum and SCFAs were evaluated. Abstract The aim of this study was to explore the inhibitory effects of SPG-56 and intestinal microbes on the progression of colorectal cancer (CRC). An in-vivo model of CRC was generated by transplanting BALB/c nude mice with HCT-116 cells and tumor progression was monitored after treatment with SPG-56 (150 mg/kg), Lactobacillus fermentum (2 × 10⁸ cfu/0.2 ml) + SPG-56 (150 mg/kg) and short-chain fatty acids (SCFAs, 20 mM/0.2 ml). All three treatment modalities suppressed tumor growth when compared to the untreated tumor control (TC) group. Sequencing of 16S rRNA genes showed an enrichment of the gut microbiota in the SPG-56 group, with L. fermentum (LF) being the most abundant species. And the content of SCFAs in the SPG-56 group was also significantly higher than that in other groups. We hypothesize that SPG-56 increases the gut microbiota and induces SCFA production which, by mechanisms as yet unknown, triggers apoptosis in the tumor cells. [ABSTRACT FROM AUTHOR]