Abstract
Changes in gut microbiota composition have consistently been observed in patients with colorectal cancer (CRC). Yet, it is not entirely clear how the gut microbiota interacts with tumor cells. We know that tumor cells undergo a drastic change in energy metabolism, mediated by microRNAs (miRNAs), and that tumor-derived miRNAs affect the stromal and immune cell fractions of the tumor microenvironment. Recent studies suggest that host intestinal miRNAs can also affect the growth and composition of the gut microbiota. Our previous CRC studies showed a high-level of interconnectedness between host miRNAs and their microbiota. Considering all the evidence to date, we postulate that the altered nutrient composition and miRNA expression in the CRC microenvironment selectively exerts pressure on the surrounding microbiota, leading to alterations in its composition. In this review article, we present our current understanding of the role of miRNAs in mediating host–microbiota interactions in CRC.
Highlights
An average human intestine contains more than 100 trillion bacteria [1]
Bacterial candidates such as Fusobacterium nucleatum and Bacteroides fragilis are consistently enriched in tumor tissues, and included in that signature
We present our current understanding of the role of miRNAs in mediating host–microbiota interactions in colorectal cancer (CRC) (Figure 1)
Summary
An average human intestine contains more than 100 trillion bacteria (collectively known as the gut microbiota) [1]. A number of studies have suggested that the gut microbiota is crucial to human health and to the development of diseases, including colorectal cancer (CRC) [2,3,4,5,6,7]. Mutations in the tumor-suppressor adenomatous polyposis coli (APC) gene are associated with a distinct inter-microbiota association network [2] These findings suggest that a common genetic factor might orchestrate the dynamic host–microbiota interaction(s) and functional relationship(s). Microbial-metabolites and other secreted factors affect miRNA/gene expression profiles in cells present in tumor the tumor microenvironment. The tumor-derived miRNAs have a role in regulating stromal and tumor infiltrating immune cells by by affecting gene expression delivered in EVs stromal and tumor infiltrating immune cells affecting gene expressionthrough throughmiRNAs miRNAs delivered interactions willwill create a favorable microenvironment in (4). Such interactions create a favorable microenvironmentfor fortumor tumorcells cells that that include include angiogenesis, immune evasion, microbiota composition angiogenesis, immune evasion, andand microbiota composition (5).(5)
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