- One-third of colon cancer cases is associated with Fusobacterium nucleatum which a common type of oral bacteria that is often implicated in tooth decay.
- Colon cancers associated with F. nucleatum are often the most aggressive.
- Findings could make it easier to identify and treat more aggressive colon cancers.
- Findings could explain why some colon cancer cases advance far more quickly than others
Over the years, studies have shown the connection between oral health and our overall well-being. Gum disease have been linked to heart disease, diabetes and high cholesterol and kidney disease and poor oral health has been associated with high blood pressure.
In addition to this list, emerging studies now show that the presence of a common type of oral bacteria often implicated in tooth decay – F. nucleatum – promotes the growth of colon cancer. Colon cancer cases associated with this type of bacteria are often most aggressive, but it was unclear why until now.
The research
Researchers at the Columbia University College of Dental Medicine headed by Yiping W. Han, PhD discovered that the bacterium makes a molecule called FadA adhesin, triggering a signaling pathway in colon cells that has been implicated in several cancers. They also established that FadA adhesin only stimulates the growth of cancerous cells, not healthy cells.
“We needed to find out why F. nucleatum only seemed to interact with the cancerous cells,” said Dr. Han, Professor of microbial sciences at Columbia University’s College of Dental Medicine and Vagelos College of Physicians & Surgeons.
Results of the study
In their latest study, the researchers found in cell cultures that noncancerous colon cells lack a protein, called Annexin A1, which stimulates cancer growth. They then confirmed both in vitro and later in mice that disabling Annexin A1 prevented F. nucleatum from binding to the cancer cells, slowing their growth.
The researchers also discovered that F. nucleatum increases production of Annexin A1, attracting more of the bacteria. “We identified a positive feedback loop that worsens the cancer’s progression,” says Dr. Han. “We propose a two-hit model, where genetic mutations are the first hit. F. nucleatum serves as the second hit, accelerating the cancer signaling pathway and speeding tumor growth.”
The importance of the study
The findings could make it easier to identify and treat more aggressive colon cancers. It also helps explain why some cases advance far more quickly than others, thanks to the same bacteria found in dental plaque.
