The Role of Gut Microbiota and Mucin Barrier in the Pathogenesis of Colorectal Cancer

Colorectal cancer (CRC) is one of the most common and fatal malignant tumors globally, and its development is increasingly related to the gut microbiota. Despite its effect on CRC having been extensively researched, the intestinal mucus barrier, which forms a fundamental link between the host tissues and gut microbes, is seldom discussed. A double-layered barrier, mainly formed by MUC2 mucin, isolates the outside world from epithelial cells to maintain intestinal homeostasis. Furthermore, it is subjected to a dynamic impact of microbial activity. Now, increasing evidence shows that mucus barrier disruption driven by certain gut microbes is an early event in the development of CRC. This review first introduces the structure and function of the colonic mucus barrier and then discusses how gut microbiota in different areas promote the development of CRC by disrupting the mucus layer. Finally, we examine translational opportunities for exploiting microbiota-mucus barrier interactions in CRC therapy.