15 January 2018

Microbes and broccoli against colorectal cancer

GM bacteria beat colon cancer with vegetables

Evgenia Efimova, Vesti

Some fantastic breakthroughs happen thanks to a great imagination. Imagine this picture: researchers are "recruiting" certain strains of intestinal bacteria to chase and kill cancer cells in the human colon. It sounds like a description of a war movie, but the team of the National University of Singapore is doing exactly that.

They genetically modify a common type of intestinal bacteria so that they capture colorectal cancer cells and turn a special substance (it was found in broccoli) into a cancer-killing toxin.

At first, experts, as already mentioned, genetically modified the harmless form of the bacterium, usually found in the human intestine E.coli Nissle.

The resulting bacterium was engineered to bind to a compound called heparan sulfate proteoglycan. This protein was found on the surface of colorectal cancer cells. Let us explain that colorectal cancer is a malignant neoplasm of the large intestine.

The microorganism sits on cancer cells, and then waits for its "host" to eat products containing glucosinolates. Glucosinolates found in broccoli, cabbage and other cruciferous vegetables are then converted into a substance called sulforaphane. The modified bacterium secretes a special enzyme for this. Sulforaphane is a long–known cancer-killing compound.

Drawing from the press release With these special bacteria, a broccoli a day can keep the cancer doctor away – VM.

Experts tested the process in vitro for the first time and found that the combination of modified bacteria and glucosinolates kills over 99 percent of colorectal cancer cells.

And then, already on tests of an unusual combination on mice, the results were just as impressive, reducing the number of tumors by an astounding 75 percent.

To date, there are still many obstacles that need to be overcome before this type of treatment is tried in humans. For example, it is not yet known what side effects will arise from the introduction of modified bacteria into the human body.

At the moment, there are research groups working on creating a kind of protective systems for genetically modified bacteria, which, in case of undesirable behavior of microbes, will start the process of their self-destruction.

Singapore scientists believe that in the future such engineered bacteria will be used as protibiotics to prevent the development of cancer or destroy cancer cells that are too small to detect during surgical removal.

The results of the study are presented in the scientific publication Nature Biomedical Engineering.

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