# The dysbiosis signature of Fusobacterium nucleatum in colorectal cancer-cause or consequences? A systematic review

## TL;DR

This paper reviews whether the presence of Fusobacterium nucleatum in colorectal cancer is a cause or consequence, and suggests it could be a potential biomarker for cancer risk.

## Contribution

The paper systematically reviews the role of Fusobacterium nucleatum in colorectal cancer and proposes it as a potential prognostic biomarker.

## Key findings

- Fusobacterium nucleatum is found in colorectal cancer specimens and expresses virulence factors like FadA, Fap2, and MORN2.
- There is evidence suggesting F. nucleatum could serve as a prognostic biomarker for colorectal cancer risk.
- Antibiotic treatment targeting F. nucleatum may have potential for CRC prevention.

## Abstract

Colorectal cancer (CRC) is the third most common cause of cancer globally and the fourth attributable cause of mortality and morbidity due to cancer. An emerging factor contributing to CRC is the gut microbiota and the cellular changes associated with it. Further insights on this may help in the prevention, diagnosis and new therapeutic approaches to colorectal cancer. In most cases of CRC, genetic factors appear to contribute less to its aetiology than environmental and epigenetic factors; therefore, it may be important to investigate these environmental factors, their effects, and the mechanisms that may contribute to this cancer. The gut microbiota has recently been highlighted as a potential risk factor that may affect the structural components of the tumor microenvironment, as well as free radical and enzymatic metabolites directly, or indirectly. Many studies have reported changes in the gut microbiota of patients with colorectal cancer. What is controversial is whether the cancer is the cause or consequence of the change in the microbiota. There is strong evidence supporting both possibilities. The presence of Fusobacterium nucleatum in human colorectal specimens has been demonstrated by RNA-sequencing. F. nucleatum has been shown to express high levels of virulence factors such as FadA, Fap2 and MORN2 proteins. Our review of the published data suggest that F. nucleatum may be a prognostic biomarker of CRC risk, and hence raises the potential of antibiotic treatment of F. nucleatum for the prevention of CRC.