Towards the human colorectal cancer microbiome

Area of Science:

• Microbiology
• Oncology
• Gastroenterology

Background:

• Colorectal cancer (CRC) development is influenced by multiple factors, with increasing evidence linking intestinal bacteria to disease initiation and progression.
• Understanding the colonic microbiome's role in sporadic CRC is crucial for developing new diagnostic and therapeutic strategies.

Purpose of the Study:

• To create a high-resolution map of colonic dysbiosis associated with human colorectal cancer (CRC).
• To compare microbial colonization patterns in tumor tissue versus adjacent non-malignant mucosa.

Main Methods:

• Deep rRNA sequencing was employed to analyze and compare the microbiomes of colon tumor tissue and adjacent non-malignant mucosa.
• Microbial colonization patterns were investigated to identify differences between tumor and healthy tissue.

Main Results:

• Striking differences in microbial colonization were observed between tumor and non-malignant mucosa.
• Tumors consistently harbored Coriobacteria and other proposed probiotic species, while potentially pathogenic Enterobacteria were underrepresented.
• Inter-individual variability in colonization was noted, but tumor-specific microbial niches were consistently identified.

Conclusions:

• CRC-associated physiological and metabolic changes appear to recruit specific commensal-like bacteria to the tumor microenvironment.
• These recruited microbes may have a competitive advantage, potentially displacing bacteria implicated in CRC etiology.
• This study provides foundational insights into the CRC microbiome, paving the way for novel microbiome-related diagnostics and therapeutics.