Surprising link between gut microbes and bladder cancer

Now, a new study by researchers at the European Molecular Biology Laboratory (EMBL) in collaboration with the University of Split in Croatia has found that microbes interfere with the way the body responds to carcinogens, which cause normal cells to turn cancerous, leading to tumors and cancer.

Previously, researchers found that if mice were exposed to BBN (a chemical found in tobacco smoke), they developed an aggressive form of bladder cancer. So this discovery is used as a common laboratory model of cancer caused by carcinogens.

In this regard, the laboratory of Janos Terzic, at the University of Split in Croatia, discovered a strange observation when studying this model.

The team said that if the mice were given antibiotics, at a dose that killed 99.9% of gut bacteria, at the time they were exposed to BBN, their chances of developing tumors were much lower.

“While 90% of the mice exposed to BBN developed bladder tumors, only 10% of the mice that also received antibiotics developed tumors,” said Blanca Roje, the study’s first co-author. “This led us to hypothesize that gut bacteria might be involved in regulating how the body processes BBN. ​​We repeated the experiment five times before realizing that with a specific treatment (in this case, antibiotics), we were able to stop the cancer from developing.”

The study focused on biotransformation, the ability of microorganisms to change or break down chemicals in their environment.

The researchers discovered that bacteria living in the gut of mice can convert BBN into BCPN (a class of compounds called nitrosamines).

But BCPN concentrates in the urinary bladder, and stimulates tumor formation in a microbiome-dependent manner.

The researchers then studied more than 500 isolated and cultured bacteria to identify the specific bacterial species involved in the conversion of BBN to BCPN.

“We found 12 species that can carry out this carcinogenic biological transformation,” said Boyao Chan, co-first author of the study.

The research team used human fecal samples to show that human gut bacteria can also convert BBN to BCPN. The study showed that if human feces were transplanted into the intestines of mice that did not have their own gut microbiome, they could also convert BBN to BCPN.

This lays the foundation for further research to find out whether a person’s gut microbiome represents a predisposition to chemical-induced cancer, and could therefore be used to predict individual risk and prevent the development of cancer, the researchers said.

They explained that these results do not mean that the use of antibiotics can prevent cancer globally, and more studies are required to understand how the microbiome affects the metabolism of different types of carcinogens.

The study was published in the journal Nature.

Source: Medical Express