Oncogenic bacteria
Bacterial mycoplasma protein can provoke the development of cancer
Sergey Syrov, XX2 century, based on the materials of the University of Maryland: Institute of Human Virology Researchers Discover That a Bacterial Protein Promotes Cancer.
Researchers from The Institute of Human Virology (IHV) at the University of Maryland School of Medicine in Baltimore (University of Maryland, Baltimore, School of Medicine, UMSOM) report that DnaK, a mycoplasma protein, disrupts the ability of a mycoplasma-infected cell to repair DNA damage, which can cause cancer.
An article about the study was published in the journal PNAS (Proceedings of the National Academy of Sciences).
If the scientists' conclusions are correct, bacterial infections are noticeably more likely than previously thought to cause cancer.
The discovery was presented to the public by one of the discoverers of the human immunodeficiency virus, Professor Robert Gallo.
"Currently, approximately 20% of cancer cases are believed to be caused by an infection, mainly viral," says Professor Gallo. – Mycoplasmas are a family of bacteria that are associated with cancer, especially in people with HIV. Our work explains how a bacterial infection can trigger a series of events leading to cancer. It is especially important that the infection should not persist, and the protein should not be constantly present in all cancer cells. The study also shows the mechanism of how certain bacterial infections can interfere with the action of specific anti-cancer drugs."
Mice with suppressed immunity were used as a model to analyze the effect of mycoplasma infection on the development of lymphoma. The time after which lymphoma developed in uninfected mice and animals infected with mycoplasma was compared. The mice were infected with a strain of mycoplasma obtained from an HIV patient. It turned out that mycoplasma infection accelerates the development of lymphoma. In addition, it turned out that some, but not all of the cancer cells had bacterial DNA. The discovery of only a small amount of bacterial DNA in cancer cells showed that the infection does not have to persist to cause cancer.
"We focused on the DnaK protein, one of the chaperone protein family," says David Zella, the first author of the publication. – In our case, DnaK reduces the activity of important cellular proteins involved in DNA repair and anti-cancer activity, such as p53. Thus, cells infected with mycoplasma cannot properly repair damaged DNA, thus increasing the risk of developing cancer."
The authors explain that bacteria can secrete DnaK, and DnaK gets into nearby uninfected cells. The study also shows that through the suppression of p53, DnaK also reduces the effectiveness of anti-cancer drugs.
Thus, mycoplasma infection can not only cause events leading to the accumulation of DNA damage and oncogenesis in infected cells, but also cause cancer-causing events in nearby uninfected cells.
The researchers noted that mycoplasmas are not the only group of bacteria whose infection can provoke the development of cancer.
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