The Role of Sensing Peptides in the Cross-talk between Microbiota and Human Cancer Cells.

The epithelium of the gastrointestinal tract is densely populated by complex microbial communities which exert both local and distant effects in the human body with relevant consequences on the metabolic status, immune system and overall health. A dynamic equilibrium between the many bacterial species and the host intestinal epithelium is maintained through the release of a large number of small molecules and peptides. The quorum sensing peptides are mainly secreted by Gram-positive bacteria and are able to "communicate" with human cells. Some sensing peptides have shown to promote angiogenesis, tumor cell invasion and metastasis of colon cancer as well as of breast cancer cells. On the other hand, quorum sensing cyclodipeptides produced by bacteria and fungi have shown significant antitumor activities. In this review, we summarize the available data on the pro-tumor activities of quorum sensing peptides and the anti-cancer functions of cyclodipeptides in the human malignancies.