Gut Microbiome Development Along The Colorectal Adenoma-carcinoma Sequence

Colorectal cancer is the third most commonly diagnosed cancer both in men and women. The incidence is higher in more developed countries such as North American, Western Europe, Australia and New Zealand, but is rapidly increasing in historically low risk areas such as Eastern Asia, Spain and Eastern Europe. Because of the key function in metabolism and immunoregulation, gut microbiota is believed to be directly involved in colorectal carcinogenesis. However, the the adenoma- or carcinoma- related gut microbe(s) have not been surveyed in a comprehensive manner.This study collected the fecal samples from healthy controls, advanced adenoma, and carcinoma patients, totally 147 individual, and performed the metagenome sequence. The clean sequenced data through filter, assembly, gene prediction and remove redundancy were used to construct a human gut microbiome gene set. This gene set contained 3,513,139 non-redundance gene. Metagenome-wide association study was performed based on this gene set, and identified 130,715 genes significantly different among control, adenoma and carcinoma. The significantly different genes were clustered into MLG(Metagenomic linkage groups). The classifiers between control vs carcinoma and control vs adenoma were build based on MLG. An analysis of potential risk factors indicates that high intake of red meat appear to associate with outgrowth of bacteria that might contribute to a more hostile gut environment, the intake of fruit and vegetable, in contrast, appear to negatively correlated with these bactetia. These findings suggest that faecal microbiome-based strategies may be useful for early diagnosis and treatment of colorectal adenoma or carcinoma.