Gut microbiota imbalance and colorectal cancer

• Published in: World journal of gastroenterology : WJG Vol. 22; no. 2; pp. 501 - 518
• Main Authors: Gagnière, Johan, Raisch, Jennifer, Veziant, Julie, Barnich, Nicolas, Bonnet, Richard, Buc, Emmanuel, Bringer, Marie-Agnès, Pezet, Denis, Bonnet, Mathilde
• Format: Journal Article
• Language: English
• Published: United States Baishideng Publishing Group Co. Limited 14.01.2016; Baishideng Publishing Group Inc
• Subjects: Animals; Bacteria - metabolism; Bacteria - pathogenicity; cancer; Cell Transformation, Neoplastic - metabolism; Cell Transformation, Neoplastic - pathology; Colorectal; Colorectal Neoplasms - metabolism; Colorectal Neoplasms - microbiology; Colorectal Neoplasms - pathology; DNA Damage; Dysbiosis; Dysbiosis;Cyclomodulin; Gastrointestinal Microbiome; Gut; Host-Pathogen Interactions; Humans; Inflammation Mediators - metabolism; Intestines - microbiology; Life Sciences; microbiota; Oxidative; Oxidative Stress; stress; Topic Highlight; Virulence Factors - metabolism; Gut microbiota; Oxidative stress; Cyclomodulin; Dysbiosis; Colorectal cancer
• ISSN: 1007-9327; 2219-2840
• DOI: 10.3748/wjg.v22.i2.501

The gut microbiota acts as a real organ. The symbioticinteractions between resident micro-organisms and thedigestive tract highly contribute to maintain the guthomeostasis. However, alterations to the microbiomecaused by environmental changes （e.g. , infection, dietand/or lifestyle） can disturb this symbiotic relationshipand promote disease, such as inflammatory boweldiseases and cancer. Colorectal cancer is a complexassociation of tumoral cells, non-neoplastic cells and alarge amount of micro-organisms, and the involvementof the microbiota in colorectal carcinogenesis isbecoming increasingly clear. Indeed, many changes inthe bacterial composition of the gut microbiota havebeen reported in colorectal cancer, suggesting a majorrole of dysbiosis in colorectal carcinogenesis. Somebacterial species have been identified and suspectedto play a role in colorectal carcinogenesis, such asStreptococcus bovis , Helicobacter pylori , Bacteroides fragilis , Enterococcus faecalis , Clostridium septicum ,Fusobacterium spp. and Escherichia coli . The potentialpro-carcinogenic effects of these bacteria are nowbetter understood. In this review, we discuss thepossible links between the bacterial microbiota andcolorectal carcinogenesis, focusing on dysbiosis andthe potential pro-carcinogenic properties of bacteria,such as genotoxicity and other virulence factors,inflammation, host defenses modulation, bacterialderivedmetabolism, oxidative stress and antioxidativedefenses modulation. We lastly describehow bacterial microbiota modifications could representnovel prognosis markers and/or targets for innovativetherapeutic strategies.