Scientists have found DNA-damaging molecules in gut bacteria. This may help to explain why people with cancer are affected. Inflammatory bowel diseaseHigher rates of colorectal disease in IBD CancerThey are better than those with the condition.
A new study was published in the journal on Thursday, 27 October. ScienceResearchers identified a new class of DNA-damaging molecules or genotoxins that was previously unknown. They named it the “indolimines.”
These molecules can be produced by Morganella morganii, bacteriumIt proliferates in patients with IBD or those with colorectal disease. Cancer.
Indolimines damaged DNAIn lab experiments, and also drove the growth of cancer in mice with colorectal tumours.
Also, by preventing indolimine production M. morganiiThe scientists discovered that they could stop tumor growth in mice.
In the past, other gut bugs were linked to IBD or colorectal carcinoma. Cynthia SearsThis study did not include a participation by a Professor of Medicine and Oncology at Johns Hopkins University School of Medicine, Baltimore.
Select strains of, for example, are available in Escherichia coliThese chemicals are linked to IBD and create a genotoxin called Colibactin that damages DNA and causes tumor growth in mice.
The new study contributes to our understanding of the role that other bacteria may play in these diseases.
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“We have a vast array of data – and this is just one other piece that’s been added to that – that links the microbiome to colon diseases and colon cancer,” Sears said.
This research could eventually lead to screening tools for doctors that can help them identify patients at highest risk of developing colon cancer. All they have to do is take a sample of poop.
It may also be used to prevent the growth of cancer-linked bacteria and lower patients’ risk of developing it.
Sears explained that although we are aware of these clinical associations, we don’t know how they can be prevented or disrupted to lower the risk of developing cancer.
“We must determine at a molecular level the mediators so that we can bring something to patients’ beds.”
To identify these DNA-damaging molecules researchers first examined more than 100 strains of gut bacteria taken from the stool samples of 11 IBD sufferers. (IBD includes ulcerative colitis. inflammationItchy sores on the rectum or colon lining. Crohn’s Disease(This causes inflammation in any part or all of the digestive tract, but most often in the small intestine.
Each of the bacterial strains were grown in a laboratory dish with DNA. The team then identified 18 strains that had damaged the genetic molecule.
Scientists identified the individual molecules the bacteria produced, and then tested for DNA damage.
Researchers found that the DNA damage to which the bacteria was causing the DNA damage did not match that of colibactin.
The researchers stated that these data implied the existence previously unknown microbiota-derived genetotoxins in their report.
The researchers zoomed in closely to identify some unknown genotoxins. M. morganiiThis was previously reported to be a common problem in colon cancer patients’ stomachs.
This work led to the discovery of the indolimines and the identification of a bacterial genetic gene necessary for their production: the so-called Aspartate Aminotransferase Gene (aat), which codes an enzyme.
Related: Unique gut bacteria signatures are unique to people who live past 100 years.
In a mouse model for colorectal cancer M. morganiiThe aat gene was found in strains that accelerated tumor growth.
This gene was deleted from the bacteria by the team. The team thus stopped the making of indolimines and halted cancer growth.
“The best evidence they present is the mouse studies – that’s what convinced me,” Sears said.
However, this mouse model is not perfect. Researchers used “gnotobiotic” mice to determine which bacteria would grow in rodents. M. morganiiSeven other bacteria that were not genotoxic.
Scientists were then able to observe how cancer drives. M. morganiiSears explained that this did not capture the complexity and diversity of a natural microbiome.
To understand the extent of this problem, more research is required. M. morganiiIt can be found in various types of IBD or colorectal carcinoma.
Sears stated that further studies will be needed to determine how indolimines damage DNA and how important these molecules are in cancer development compared to other genotoxins.
She said that the paper was a “first step”.
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This article was first published by Live Science. Learn more Original article here.
