Scientists discover cancer causing 'mechanism' used by certain bacteria
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Loading... - Arthur Girard
- 15 Aug 2024
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An international research team led by Croatian scientists has uncovered a significant mechanism by which certain bacteria in the digestive system may contribute to the development of cancer. The study, published in the prestigious journal Nature, provides new insights into how specific microbes, known as "oncomicrobes," can promote tumor formation.
The team, led by Janosh Terziq, highlighted that while Earth hosts a vast diversity of microbial species, only a small number, specifically 11, have been identified as human carcinogens. These oncomicrobes include viruses like HPV and hepatitis B, as well as the bacterium Helicobacter pylori. Additionally, there are other bacteria, such as Bacteroides fragilis (Bf) and Fusobacterium nucleatum (Fn), which do not directly cause cancer but can support its development.
Terziq explained the various ways these bacteria contribute to cancer. For instance, the toxin produced by Bf creates reactive compounds that damage cells, while Fn stimulates tumor cell proliferation and prevents their death. Another example is a toxin from certain strains of E. coli, known as colibact, which damages DNA and may contribute to tumorigenesis.
One of the critical discoveries made by Terziq's team is the role of nitrosamines, compounds long known to cause DNA damage, in the cancer-causing process. The research demonstrated that certain bacteria can convert specific nitrosamines into more harmful compounds, which then cause DNA damage and lead to cancer. Specifically, they found that some bacteria convert N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) into N-butyl-N-(3-carboxypropyl) nitrosamine (BCPN). BCPN accumulates in the bladder tissue and induces cancer in mice. The study also showed that by using antibiotics to eliminate these bacteria, the development of tumors in mice could be prevented.
The experiments conducted involved "humanized" mice, meaning that the researchers made the experimental conditions as close as possible to what occurs in humans. For example, the research team used mice living in completely sterile conditions and then colonized them with human bacteria that convert BBN to BCPN. This approach allowed them to closely study the effects of these bacteria on tumor formation.
Terziq's research group has been investigating bladder tumors for some time, and this discovery is a crucial part of their ongoing work. Initially, they found that significantly reducing gut bacteria through antibiotics nearly prevented bladder tumor formation in mice. This led to further exploration of the reasons behind this effect, ultimately revealing that the bacteria were converting chemicals into more dangerous forms that could trigger cancer.
The findings from this study open new avenues for cancer prevention and treatment, particularly by targeting specific bacteria that contribute to cancer development.
