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©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jan 14, 2016; 22(2): 501-518
Published online Jan 14, 2016. doi: 10.3748/wjg.v22.i2.501
Gut microbiota imbalance and colorectal cancer
Johan Gagnière, Jennifer Raisch, Julie Veziant, Nicolas Barnich, Richard Bonnet, Emmanuel Buc, Marie-Agnès Bringer, Denis Pezet, Mathilde Bonnet
Johan Gagnière, Jennifer Raisch, Julie Veziant, Nicolas Barnich, Richard Bonnet, Emmanuel Buc, Marie-Agnès Bringer, Denis Pezet, Mathilde Bonnet, Clermont Université, UMR 1071 Inserm/Université d’Auvergne, 63000 Clermont-Ferrand, France
Johan Gagnière, Jennifer Raisch, Julie Veziant, Nicolas Barnich, Richard Bonnet, Emmanuel Buc, Marie-Agnès Bringer, Denis Pezet, Mathilde Bonnet, INRA, USC-2018, 63000 Clermont-Ferrand, France
Johan Gagnière, Julie Veziant, Emmanuel Buc, Denis Pezet, Chirurgie Digestive, Centre Hospitalier Universitaire, 63000 Clermont-Ferrand, France
Richard Bonnet, Bactériologie, Centre Hospitalier Universitaire, 63000 Clermont-Ferrand, France
Jennifer Raisch, Laboratoire d’Immunologie, Institut Armand Frappier, Laval H7V 1B7, Canada
Marie-Agnès Bringer, INRA UMR 1324, CNRS UMR 6265, Université de Bourgogne, Centre des Sciences du Goût et de l’Alimentation, Eye Nutrition and Signalling Research Group, 21000 Dijon, France
Author contributions: Gagnière J, Raisch J and Veziant J organized and wrote the manuscript; Barnich N, Bonnet R, Buc E, Bringer MA and Pezet D supervised the writing of the manuscript; Bonnet M organized, wrote and supervised the writing and the manuscript.
Supported by Inserm and Université d’Auvergne (UMR 1071), INRA (USC-2018); and grants from “Conseil regional d’Auvergne”, “Nuovo Soldati Foundation for Cancer Research” and “Fondation pour la recherche médicale”.
Conflict-of-interest statement: None of the authors have any conflicts of interest to declare.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Mathilde Bonnet, PhD, M2iSH “Microbes, intestin, inflammation et Susceptibilité de l’Hôte” UMR 1071 Inserm/Université d’Auvergne USC INRA 2018, Centre Biomédical de Recherche et Valorisation, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France. mathilde.bonnet@udamail.fr
Telephone: +33-4-7318381 Fax: +33-4-73178371
Received: April 28, 2015
Peer-review started: May 6, 2015
First decision: August 25, 2015
Revised: September 6, 2015
Accepted: October 17, 2015
Article in press: October 20, 2015
Published online: January 14, 2016
The gut microbiota acts as a real organ. The symbiotic interactions between resident micro-organisms and the digestive tract highly contribute to maintain the gut homeostasis. However, alterations to the microbiome caused by environmental changes (e.g., infection, diet and/or lifestyle) can disturb this symbiotic relationship and promote disease, such as inflammatory bowel diseases and cancer. Colorectal cancer is a complex association of tumoral cells, non-neoplastic cells and a large amount of micro-organisms, and the involvement of the microbiota in colorectal carcinogenesis is becoming increasingly clear. Indeed, many changes in the bacterial composition of the gut microbiota have been reported in colorectal cancer, suggesting a major role of dysbiosis in colorectal carcinogenesis. Some bacterial species have been identified and suspected to play a role in colorectal carcinogenesis, such as Streptococcus bovis, Helicobacter pylori, Bacteroides fragilis, Enterococcus faecalis, Clostridium septicum, Fusobacterium spp. and Escherichia coli. The potential pro-carcinogenic effects of these bacteria are now better understood. In this review, we discuss the possible links between the bacterial microbiota and colorectal carcinogenesis, focusing on dysbiosis and the potential pro-carcinogenic properties of bacteria, such as genotoxicity and other virulence factors, inflammation, host defenses modulation, bacterial-derived metabolism, oxidative stress and anti-oxidative defenses modulation. We lastly describe how bacterial microbiota modifications could represent novel prognosis markers and/or targets for innovative therapeutic strategies.
Core tip: The gut microbiota acts as a real organ and many changes in its composition have been reported in colorectal cancer. The pro-carcinogenic properties of bacteria are now better understood. In this review, we discuss possible links between the bacterial microbiota and colorectal carcinogenesis, focusing on the dysbiosis-causing and pro-carcinogenic properties of bacteria, such as genotoxicity, inflammation, and oxidative stress. We lastly detail how microbiota modifications may represent novel prognosis markers and/or targets for innovative therapeutic strategies.
