Evidence for Contributions of Gut Microbiota to Colorectal Carcinogenesis

Abstract

The contributions of the commensal gut microbiota to the maintenance of human health have long been contemplated. Whereas earlier studies were limited by an inability to analyze microbiota in sufficient depth, recent advances in the application of high throughput sequencing have allowed for an in-depth microbiota analysis in large numbers of individuals. Multiple lines of evidence have been generated that are supportive of an active role of gut microbiota in colorectal carcinogenesis. Although no single microbe has yet been shown to be causally linked to CRC, contributions of the gut microbiota to colorectal carcinogenesis are evident. Further advances in the field, which should include prospective studies in high-risk cohorts, should generate the data needed to start translating findings into microbiota-based screening and prevention regimen that can help to reduce the burden of CRC.

Activity of Zearalenone in the Porcine Intestinal Tract

“…Microbiota can also exert a negative influence on animals. Pathogenic microorganisms produce toxic metabolites and fecal enzymes that can lead to the formation of carcinogenic substances and the activation of procarcinogenic compounds [ 45 , 123 ]. The majority of research investigating bacterial effects on mycotoxins focuses on gut microbiota’s ability to eliminate toxic compounds.…”

O6‐carboxymethylguanine DNA adduct formation and lipid peroxidation upon in vitro gastrointestinal digestion of haem‐rich meat

“…With respect to NOC formation, the N ‐nitrosating properties of certain bacteria colonising the individual human gut (and a possible connection to carcinogenesis) have been demonstrated before . Furthermore, the possible role (of the exact composition) of the individual gut microbiota in health and disease was already pointed out decades ago , and has been brought to the surface even more in recent years . Other examples of significant inter‐individual differences in the transformation of dietary compounds or contaminants such as, phytoestrogens , heterocyclic aromatic amines , polycyclic aromatic hydrocarbons , etc.…”

“…Next to the involvement of haem in the gastrointestinal formation of cyto‐ and genotoxic compounds upon red meat digestion, it is very likely that other factors may play a role in the formation pathway(s) of both MDA and the O 6 ‐CMG DNA adduct. As a first factor, the colonic microbiota consist of a complex mixture with several attributes that differ inter‐ and intra‐individually and even by anatomical site along the colon and their location within the lumen . The colonic bacteria are constantly influenced by their surroundings; haem‐Fe can, e.g.…”

Potential Use of Biotherapeutic Bacteria to Target Colorectal Cancer-Associated Taxa

“…For example, Purcell et al [31] used qPCR analysis to show that elevated levels of Enterotoxigenic B. fragilis (ETBF) was associated with the early onset of colorectal carcinogenesis. B. fragilis is thought to promote colon carcinogenesis by stimulating cell proliferation and by inducing inflammation via the TH17-dependent pathway [61]. ETBF produces a 20-kDa metalloprotease virulence factor called B. fragilis toxin (BFT) [62].…”