Scientist uncovered bacteria induce unique mutational pattern in DNA, Cancer mutations can be caused by common bacteria in the gut that are transmitted by many people. By exposing human intestines cultured to certain strains of Escherichia coli bacteria, they found that these bacteria induce unique mutational patterns in the DNA of human cells.
This pattern of mutations is also found in the DNA of colon cancer patients, indicating that these mutations are caused by “bad” bacteria.
For the first time, researchers have discovered a direct link between germs that inhabit our bodies and genetic changes that drive cancer.
This finding could pave the way for colorectal cancer prevention by continuing to eradicate harmful bacteria. The results of this study were published in Nature on 27 February.
Our body contains at least as many bacteria as human cells. Most of these microbes contribute to healthy living, while others can cause disease. Among the bacteria with potentially harmful effects is the most well-known strain of intestinal bacteria: Escherichia coli (E. coli). Scientist uncovered bacteria induce unique mutational pattern in DNA.
This particular type of E. coli is “genotoxic”: it produces a small chemical called “colibactin” that can damage the DNA of human cells. Therefore, it has long been suspected that genotoxic E. coli that live in the intestines of 1 in 5 adults can be harmful to their human host.
Currently there are probiotics on the market that contain genotoxic E. coli strains. Although they can alleviate some physical ailments in the short term, these probiotics can cause cancer several decades after treatment. Scientist uncovered bacteria induce unique mutational pattern in DNA.
Cancer cells are driven by specific DNA mutations that allow these cells to grow into tumors. UV light or smoking can directly cause DNA damage that causes mutations, increasing the likelihood that normal cells will turn into cancer.
However, it was not previously known that bacteria in our intestines can also cause cancer mutations in cells due to the damaging effects of their DNA.
Every process that can cause DNA damage leaves certain mutation models called mutations or signatures. These specific signatures have been identified for various types of cancer, including tobacco smoke and ultraviolet light. The presence of these specific fingerprints in cancer DNA can provide information about previous exposures that might be the cause of disease. Scientist uncovered bacteria induce unique mutational pattern in DNA.
Genotoxic bacteria cause two models of simultaneous mutations in organoid DNA: replacing A with one of the four possible letters of the DNA code and losing one A in the long section A.
In both cases there is another A on the opposite strand of the DNA double helix, 3 to 4 bases from the mutated site.
The team wondered if their data could tell them something about the mechanism of damage to DNA induced by colibactin.
Their study shows the ability of colibactin to bind and connect two As at the same time. It was like a collapsing puzzle. The pattern of mutations that we saw in our experiments can be very well explained by the chemical structure of colibactin. Scientist uncovered bacteria induce unique mutational pattern in DNA.
After finding genotoxic traces of E. coli, the researchers began to search for traces in DNA oncologists. They analyzed mutations in more than 5,000 tumors that spread to various types of cancer.
One of them is one of the following: “More than 5% of colorectal cancers have high footprints, while we have seen this in less than 0.1% of all other cancers.
Some other cancers known to be prone to bacteria, such as oral and bladder cancers, also have footprints. It is known that E. coli can infect these organs, and we want to investigate whether the genotoxicity can affect other organs outside the large intestine. The signature that we set experimentally helped us in that regard.
This study can have a direct impact on human health. Humans can be tested for the presence of these genotoxic bacteria; It was reported that 10 to 20 percent of people can carry a “bad” version of E. coli in the intestine. Antibiotic treatment can kill these bacteria early on.
In the future, it will be very possible to detect the development of colon cancer very early or even prevent tumor development.