Oral microbiome contribution in colorectal carcinogenesis: polymicrobial interactions and virulence determinants

Area of Science:

• Microbiology
• Oncology
• Ecology

Background:

• Colorectal cancer (CRC) research traditionally focused on individual microbes, but evidence suggests polymicrobial consortia are key.
• Oral bacteria can translocate to the colon, forming structured communities that influence colorectal carcinogenesis.
• Existing frameworks need expansion to incorporate the ecological roles of oral taxa in CRC.

Purpose of the Study:

• To propose an expanded ecological framework for understanding oral taxa in colorectal carcinogenesis.
• To integrate conceptual frameworks: oral microbial complexes, bridging organisms, and the driver-passenger model.
• To shift interpretation from taxonomy-centered to a functional virulome-based view of CRC-associated microbes.

Main Methods:

• Review and synthesis of existing literature on oral bacteria, colorectal cancer, and microbial ecology.
• Integration of three complementary conceptual frameworks: oral microbial complexes, bridging organisms, and the extended driver-passenger model.
• Analysis of virulence factors and their roles in microbial interactions and tumor progression.

Main Results:

• Oral bacteria, including *Fusobacterium nucleatum*, form structured, interactive communities in the colorectal niche.
• *F. nucleatum* acts as a bridging organism, facilitating interspecies adhesion and spatial organization within these consortia.
• Key oral virulence factors contribute to CRC pathogenesis, including biofilm formation, barrier disruption, immune evasion, and metastasis.

Conclusions:

• Recognizing CRC-associated oral communities as structured ecosystems has significant diagnostic and therapeutic implications.
• Detecting pathobionts, their clusters, and virulence determinants can improve microbiome-based CRC risk stratification.
• Targeting microbial interactions and virulence factors offers a precision strategy against carcinogenic consortia.