“There are more and more papers coming out showing that they may be part of carcinogenesis,” says Straussmann. The bacterium may also alter the immune system’s ability to target and destroy cancer cells, he added. “But we’re really just scratching the surface here.” Much more needs to be done to study the effects of bacteria in tumors on the course of cancer, he says.
We already have some clues. For example, a 2022 study by Chinese scientists suggested that some bacteria within breast tumors may facilitate the spread of cancer cells to other parts of the body. Researchers found bacteria living within breast tumor cells circulating in the blood of mice. These circulating cancer cells slough off the primary tumor and travel to other parts of the body where they can metastasize and multiply. But as tumor cells rattle around in the bloodstream, some of them are under stress that causes them to break apart.
Chinese researchers have found that microbes within these migrating tumor cells appear to protect the cells from some of the stresses they experience. They seem to do this by helping to reorganize the internal cell-supporting structure known as the cytoskeleton, making the cell more robust. When the scientists removed these bacteria from mouse tumors, the primary breast cancers continued to grow, but the tumors appeared to lose their ability to metastasize.
“Certain microorganisms in the intestine, skin, other mucosal organs and tumors can either promote or antagonize tumor growth and progression,” said Douglas Hanahan, an oncologist at the Swiss Institute. There is growing evidence that there is.” He contributed to experimental cancer research in Lausanne, Switzerland, Cancer hallmarks: a new dimension. However, the image is still vague. “The situation is very complicated, and although there are clues, there is no clear point as to who is doing what.”
We also looked at other studies Fusobacterium nucleatum, an oral bacterium associated with periodontal disease, but may also be associated with many different cancers. It appears that these bacteria can travel from the mouth through the bloodstream to colorectal cancer cells. Each bacterium has specific particles on its surface that can bind to the surface of cancer cells and colonize them.
Once established, this bacterium can accelerate tumor growth and spread by interfering with the immune system’s ability to kill cancer cells.protein produced by Fusobacterium nucleatum Binds to molecular regulatory machinery on the surface of human natural killer cells and T cells. Both of these are important parts of the immune system’s defense against tumors. This binding inhibits the cell’s ability to destroy cancer cells. The bacterium also deploys a molecular weapon that makes cancer cells more resistant to chemotherapy.
moreover, Fusobacterium nucleatumDNA was found in a human breast cancer sample. This suggests that it also affects tumors elsewhere in the body. In one study, introducing the bacterium into mice with breast cancer accelerated the progression and spread of the disease. Giving the mice antibiotics prevented this.
While it may be tempting to incorporate antibiotics into cancer treatment, it is not that simple. Because many of the microbes in our bodies are benign or even beneficial, aggressive antibiotic treatment could do more harm than good, Hanahan says.
Instead, researchers must seek to fully unravel the complexity of the tumor-associated microbiome. Entire microbial communities exist within tumors, supporting each other in unexpected ways.
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