Research progress of metabolites of intestinal flora in tumors

In the recent years, evidences have suggested a close correlation of intestinal flora with occurrence and development of tumor. Intestinal flora not only impact the malignant characteristics of cancer cells but also indirectly exert their oncogenic or anti-cancer effects through producing some metabolites. Gut microbiota derived metabolites, including lipopolysaccharide, bile acids, hydrogen sulfide and short-chain fatty acids, have been found to regulate the tumor growth, metastasis and drug resistance through various molecular mechanisms. These metabolites and related regulators can serve as clinical biomarkers for early diagnosis and prognosis evaluation, meanwhile have great potential to be developed as targets for anti-cancer drugs. This review summarized the recent research progress regarding the roles of representative gut microbiota derived metabolites in tumor initiation and development, which not only enrich the theories regarding tumor related microecosystem, but also provide novel insights into the therapeutic strategies against gut microbiota-induced tumor initiation and development.