The Intestinal Microbiota and Colorectal Cancer

Abstract

The intestinal microbiota, composed of a large population of microorganisms, is often considered a “forgotten organ” in human health and diseases. Increasing evidence indicates that dysbiosis of the intestinal microbiota is closely related to colorectal cancer (CRC). The roles for intestinal microorganisms that initiated and facilitated the CRC process are becoming increasingly clear. Hypothesis models have been proposed to illustrate the complex relationship between the intestinal microbiota and CRC. Recent studies have identified Streptococcus bovis, enterotoxigenic Bacteroides fragilis, Fusobacterium nucleatum, Enterococcus faecalis, Escherichia coli, and Peptostreptococcus anaerobius as CRC candidate pathogens. In this review, we summarized the mechanisms involved in microbiota-related colorectal carcinogenesis, including inflammation, pathogenic bacteria, and their virulence factors, genotoxins, oxidative stress, bacterial metabolites, and biofilm. We also described the clinical values of intestinal microbiota and novel strategies for preventing and treating CRC.

The Role of the Gut-Liver Axis in Metabolic Dysfunction-Associated Fatty Liver Disease

“…Microbiota composition is critically influenced by genetic and environmental factors, such as diet, alcohol consumption, or certain drugs. These factors lead to quantitative and qualitative alterations that significantly impact the metabolic activity of the bacterial community and are involved in the pathogenesis of multiple diseases (11)(12)(13). In particular, dysbiosis and the alteration of the intestinal barrier are strongly associated with inflammation and metabolic disorders (14).…”

Postbiotics, Metabolic Signaling, and Cancer

“…However, there are numerous other interesting molecules including the odorous gas hydrogen sulfide (H 2 S) and a group of polysaccharides with mixed prebiotic/postbiotic properties called β-glucans. While several recent high-quality reviews covered the relationship between the intestinal microbiome and cancer [17][18][19][20][21][22], we focused on the available data on postbiotics and cancer with a special emphasis on metabolic signaling.…”

Participation of Short-Chain Fatty Acids and Their Receptors in Gut Inflammation and Colon Cancer

“…Disturbances in the normal microbial balance caused by environmental changes are frequently observed in CRC patients (Gagnière et al, 2016;Alhinai et al, 2019). Several bacterial species (e.g., Fusobacterium nucleatum, Streptococcus bovis, Bacteroides fragilis, Escherichia coli, Enterococcus faecalis, and Peptostreptococcus anaerobius) have been strongly related with colorectal carcinogenesis (Cheng et al, 2020;Janney et al, 2020). In addition, an increased risk of CRC was associated with the decreased production of SCFAs (Gomes et al, 2018).…”