The quorum sensing peptide EntF* promotes colorectal cancer metastasis in mice: a new factor in the host-microbiome interaction.

BACKGROUND: Colorectal cancer, one of the most common malignancies worldwide, is associated with a high mortality rate, mainly caused by metastasis. Comparative metagenome-wide association analyses of healthy individuals and cancer patients suggest a role for the human intestinal microbiota in tumor progression. However, the microbial molecules involved in host-microbe communication are largely unknown, with current studies mainly focusing on short-chain fatty acids and amino acid metabolites as potential mediators. Quorum sensing peptides are not yet considered in this context since their presence in vivo and their ability to affect host cells have not been reported so far. RESULTS: Here, we show that EntF*, a metabolite of the quorum sensing peptide EntF produced by Enterococcus faecium, is naturally present in mice bloodstream. Moreover, by using an orthotopic mouse model, we show that EntF* promotes colorectal cancer metastasis in vivo, with metastatic lesions in liver and lung tissues. In vitro tests suggest that EntF* regulates E-cadherin expression and consequently the epithelial-mesenchymal transition, via the CXCR4 receptor. In addition, alanine-scanning analysis indicates that the first, second, sixth, and tenth amino acid of EntF* are critical for epithelial-mesenchymal transition and tumor metastasis. CONCLUSION: Our work identifies a new class of molecules, quorum sensing peptides, as potential regulators of host-microbe interactions. We prove, for the first time, the presence of a selected quorum sensing peptide metabolite in a mouse model, and we demonstrate its effects on colorectal cancer metastasis. We believe that our work represents a starting point for future investigations on the role of microbiome in colorectal cancer metastasis and for the development of novel bio-therapeutics in other disease areas.

NanI sialidase contributes to toxin expression and host cell binding of Clostridium perfringens type G strain CP56 in vitro.

Necrotic enteritis, caused by NetB producing Clostridium perfringens type G strains, is a globally important poultry disease. An initial step in the pathogenesis of necrotic enteritis is the colonization and degradation of the intestinal mucus layer, a process in which C. perfringens sialidases - such as NanI sialidase - may play an important role. Sialidases cleave terminal sialic acid from complex carbohydrates on glycoconjugates, such as mucins. This study shows that NE-associated C. perfringens strain CP56 is able to use sialic acid (Neu5Ac) as a carbon source for bacterial growth. It is shown that supplementation of Neu5Ac in the growth medium does not only induce the production of extracellular sialidases of strain CP56, but also increases the production of both alpha toxin and NetB toxin. Moreover, it was found that pre-treating avian hepatocellular carcinoma cells (LMH cells) with the recombinant NanI sialidase increases the adherence of C. perfringens type G strain CP56 to these cells. As such, the data suggest an important role for sialidases in the pathogenesis of the disease.