Fungal dysbiosis of the gut microbiota is associated with colorectal cancer in Chinese patients

Changes in bacteria and virions are associated with colorectal cancer (CRC). However, the fungal microbiota in the intestines of CRC patients remains largely unexamined. We identified differences in the intestinal fungal microbiota between healthy persons and patients with colorectal polyps or CRC. Using second-generation sequencing technology, we sequenced and aligned the ITS1 regions of fungi collected from fecal samples. We found a significant increase in the Candida albicans levels in the guts of CRC patients. Dectin-1 is a C-type lectin receptor that recognizes beta-1,3-glucan in the cell walls of most fungi and is expressed by many cell types, including dendritic cells, macrophages, and monocytes. However, the mechanisms controlling the expressions and functions of dectin-1 in intestinal epithelial cells (IECs) remain unclear. Furthermore, the putative effects of C. albicans on IECs are unknown. C. albicans induces the proliferation of IECs by activating the Wnt signaling pathway, and the Wnt pathway contributes to the development of CRC. Mice infected with C. albicans show an activation of the Wnt pathway. Therefore, IECs may recognize the activation of the Wnt pathway by C. albicans through dectin-1 to promote the development of CRC.