A diverse array of bacteria live in the human mouth as part of a vital ecosystem known as the oral microbiome.
In a recent study published in Science Signaling, researchers found that one of these common bacteria can leave the mouth and potentially cause existing cancer cells in other parts of the body to spread.
These bacteria are believed to predominantly travel through the blood to different sites in the body where they are associated with serious infections of the brain, liver, and heart; preterm birth in pregnant women; and are present in high levels in colon tumors.
Poor oral hygiene could cause the bacteria to migrate to other parts of the body where cancers exist. Also, evidence exists for a link between severe gum disease and colorectal cancer.
The study is from Virginia Tech. One author is Daniel Slade.
Since 2012, several studies have shown this bacterium, F. nucleatum, directly invades colon tumors, but questions remained as to how this bacterium is contributing to cancer.
At first glance, F. nucleatum appears quite unremarkable and lives in harmony with other bacteria under the gums in the oral microbiome.
Despite its role as a common bacterium in the mouth, the correlations with colon cancer were too strong to ignore.
According to the team, there is no evidence that this bacterium is directly initiating cancer. Also, this bacterium does not appear to be releasing molecules that are causing the cancer cells to migrate.
Instead, F. nucleatum sticks to and even enters cancer cells.
This in turn causes cancer cells to release two proteins that are members of the cytokine protein family that play critical roles in immune system activation against infections.
Strikingly, the cytokine combination of the two proteins could induce the spread of cancer cells.
These cytokines released by an infected cell then can talk back to the same cell or those signals can be sent out to other cancer cells, immune cells, and various other cell types that surround a tumor.
In essence, one infected cell could be affecting multiple neighboring cells, so there doesn’t have to be a widespread infection within a tumor for it to be influencing a large surrounding area.
In addition, the two proteins also play roles in inflammation; a hallmark of cancer.
Together, these results provide a deeper understanding of how bacteria influence cancer.
While this process was shown to occur with colorectal cancer cells, the team is exploring if the same process is influencing other types of cancer, including pancreatic cancer, breast cancer, and oral squamous cell carcinoma of the mouth.
If you care about colon cancer, please read studies about common high blood pressure drugs may lower colon cancer risk and findings of a new way to diagnose colon cancer.
For more information about colon cancer and your health, please see recent studies about aspirin may stop colon cancer growth and recurrence and results showing that these gut bacteria may increase colon cancer risk.
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