A certain type of bacteria commonly found in the mouth can migrate to the gut and grow in colorectal cancer (CRC) tumors, potentially worsening cancer progression, according to a study.
The authors write that Fusobacterium nucleatum (Fn), a bacterium that is associated with periodontitis and oral carcinoma but is not typically found in the lower intestines of healthy people, is not only abundant in CRC tumors but may also be responsible for the development of these tumors.
“This trend is highly virulent in the context of CRC and should be the focus of subsequent mechanistic studies of Fn pathogenicity in CRC and the development of targeted inhibitors,” write the authors, led by Susan Bullman, PhD, of the Fred Hutchinson Cancer Research Center.
To test oral bacteria for the presence of F. nucleatum, colorectal tumors from more than 200 patients were analyzed. Researchers examined the genetic factors of F. nucleatum bacteria associated with tumor colonization in CRC. According to the study, they analyzed 135 strains, including those taken from oral samples of people without cancer and strains isolated from colorectal cancer tumors.
They found 483 genetic factors enriched among CRC strains, with a focus on the F. nucleatum subspecies, Fna. Interestingly, they found that Fna consists of two distinct groups, with Fna C2 being predominant in CRC tumors. Further analysis identified 195 genetic factors associated with Fna C2, indicating its increased ability to be metabolized and colonize in the gastrointestinal tract, the authors write.
The F. nucleatum subtype was found in almost 50% of the tumors studied. Additionally, this subtype was found in approximately 30% of stool samples from colorectal cancer patients, they wrote.
“Fna C2 is a highly virulent Fn subgroup that should be the focus of mechanistic studies and therapeutic drug development in CRC,” Bullman et al concluded.