Gastrointestinal tumors - How bacteria can lead to cancer - Wikipedia
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Tobacco smoke causes lung cancer, UV rays cause black skin cancer, and HP viruses cause cervical cancer. It is not well known that bacteria can also cause cancer. But they do – in the stomach and intestines.

Sometimes life takes detours. “I never thought I’d be looking for cancer-causing bacteria,” says Jens Buchhoff, a researcher at the German Cancer Research Center in Heidelberg. He found the immune system more exciting, but there were already many who wanted to deal with it. Then he stumbled upon a strange subject: Eben, the cancer-causing bacteria, and he stumbled.

Bacteria can lead to colon tumors

The community now researching this is still small, but the study situation is getting better and better. This week there’s one in Science Stady It appeared, which shows for the first time that it is not only a few bacteria that contribute to the development of cancer, but many bacteria. “I was surprised how many bacteria were able to do this,” Boschoff says.

Researchers isolated twelve strains of bacteria from the intestinal flora of people with inflammatory bowel diseases and were able to show that they all form DNA-damaging active substances. Damage to DNA is the onset of every cancer, when it occurs in certain genes important for cell growth. The researchers then looked closely at one of these active ingredients and showed that it promoted the growth of intestinal tumors in mice.

There are many ways to damage DNA. The genome consists of two interconnected strands of DNA, much like a zipper with two intertwined strands. Some bacteria secrete active components that completely cut the double strand of DNA, others cut one of the two strands, some cut at certain points in the strand, and others cut randomly.

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Intestinal bacteria wrap around a strand of DNA

Jens Puschhof was able to show the year 2020That a particular strain of the intestinal bacteria Escherichia coli can do something completely different in the gut cells’ genome. coli secretes colibactin, a factor that can wrap around the double strand of DNA. Almost as if “someone is going to tie a knot around the DNA strand,” says Buchhoff.

Why do bacteria destroy human genetic material?


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Why do bacteria produce substances that can damage human genetic material? “It is likely not to cause cancer in humans,” says researcher Jens Buchhoff.

Perhaps these “genotoxic” substances serve the bacteria better to keep competition at bay, for example, by attacking the genetic material directly. In addition, the substances can serve as a defense against viruses, the so-called phages. They too can be put out of business by attacking their genetic makeup. So the fact that bacteria promote human tumors is more than a coincidence.

If the intestinal cell then wants to read its genetic material, it has to open the double tape, that is, the zipper. Because the genetic code is hidden inside this cloud. And this is no longer possible – because of the knot. The double strand of DNA often breaks when the cell tries to read the DNA.

Possible cause of tumors

Jens Puschhof examined not only E-coli and its active ingredient colibactin, but also tumor tissues from colorectal cancer patients. In seven percent, he found distinct patterns in tumors that colibactin leaves in the genome. This suggests that colibactin contributed to these tumors.

A large part of cancer is just bad luck. Random errors in the genome of individual cells, which affect genes important for the development of cancer, are enough to cause the growth of deadly tumors.

But there are also environmental influences that are known to increase the incidence of such errors: Helicobacter pylori promotes stomach cancer, HP viruses promote cervical cancer, UV rays damage the genetic makeup of the skin and cause skin cancer, and tobacco smoke does the same to the lungs.

The Buchhof research community is still small, and many questions remain unanswered, not least how new knowledge can be used to protect against cancer. Heredity, lifestyle, and inflammation are still important cancer-causing factors in their own right, but one thing is clear: When it comes to the question of how cancer develops in the intestine, one should not lose sight of the intestinal microflora.

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