Microbes interfere with cancer treatment
Cancer cells can neutralize the effect of chemotherapy by bacteria
Sergey Vasiliev, Naked Science
Pancreatic cancer is the sixth most common cancer among the adult population. The risk of its development is increased by smoking, alcohol consumption, fatty and spicy foods, and the prognosis is not too favorable: there is no sufficiently effective treatment against it yet. It also does not respond well to gemcitabine, one of the most effective chemotherapy drugs.
Ravid Straussman and his colleagues from the Israeli Weizmann Institute have found out what this feature of pancreatic cancer, and possibly some other oncological diseases, is related to. Scientists have been trying to understand how the presence of healthy cells sometimes helps the tumor to protect itself from the effects of drugs. During the first experiments, they found that the cells (they are colored red in the illustration to the note) were infected with Mycoplasma bacteria (green in the illustration), and at first they considered it contamination.
However, it was soon discovered that these mycoplasmas are capable of destroying gemcitabine, deactivating it due to the action of a mutated form of the enzyme cytidine deaminase. In an article published by the journal Scientists write that microbes capable of producing such a protein were isolated in 86 out of 113 biopsy samples taken from patients with pancreatic cancer. In addition to mycobacteria, they were representatives of many other groups.
The authors tested a total of 2,674 different species, common inhabitants of our body and common infections, finding that about 11 percent of them synthesize this dangerous form of cytidine deaminase. Almost all of them belong to the class of gamma-proteobacteria, which includes E. coli. Experiments in vitro and on laboratory mice have shown that antibiotics can cope with the bacteria decomposing gemcitabine. However, scientists agree that this is not the best way to increase the chances of the emergence of resistant forms of microbes again.
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