Scientists believe that a bacteria better known as a cause of severe food poisoning could be engineered to help destroy cancer cells. 

A study funded by Cancer Research UK and carried out by teams based in Glasgow and Birmingham has investigated how to develop potential treatments against bowel cancer using the bacteria Salmonella. 

The bug is is a major cause of the bacterial infection, gastroenteritis, which causes fever, chills, abdominal cramps, diarrhoea and vomiting if people consume contaminated food products such as undercooked meat or eggs. 

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Although most people recover naturally, it can cause life-threatening complications in young children, the elderly, pregnant women, and those who are immunosuppressed. 

Nonetheless, scientists have also been exploring the possibility that Salmonella could offer new avenues to combat bowel cancer. 

Until now, bacterial treatments have had limited success because - while they do have a suppressant effect on tumour cell growth - they also suppress a part of the immune system which is essential to fight tumours.

The latest research, published today in the journal EMBO Molecular Medicine, has now pinpointed the mechanism that causes the immune system to be suppressed and offers a solution to overcome the problem.

The paper studied the response of T cells - a form of white blood cell which is key to fighting infections as well as cancer - to a specially-engineered, safe form of Salmonella in mice with colorectal cancer.

The team found that the Salmonella prevents T cells from doing their job and stopping colorectal cancer cells in their tracks.

Bowel cancer is the second most common cause of cancer death in the UK, claiming around 16,800 lives every year. 

Bowel cancer is the second most common cause of cancer death in the UK (Image: Getty) Scotland is disproportionately affected by the disease with around 4,000 people being diagnosed each year.

The team found that the Salmonella depleted an amino acid called asparagine which suppresses tumour growth, but which also suppresses T cells by stopping their metabolic processes.

The researchers believe that Salmonella bacteria could be further engineered not attack asparagine, enabling the T cells to attack the cancer cells.   

Lead researcher Dr Kendle Maslowski, of the Cancer Research UK Scotland Institute in Glasgow and Glasgow University, said: “We know attenuated Salmonella and other bacteria have the power to tackle cancer, however until now it was not known why it was not proving as effective as it should be.

“Our research has discovered that it is an amino acid called asparagine that the bacteria attacks which is essential for T cells to be activated.

“We believe this knowledge could enable bacteria to be engineered not to attack asparagine allowing the T cells to act against the tumour cells leading to new effective treatments for cancer.”

Microscopic image of bowel cancer tumour with Salmonella inside (in blue)Microscopic image of bowel cancer tumour with Salmonella inside (in blue) (Image: CRUK) Dr Alastair Copland, a research fellow in immunology at Birmingham University and first author on the paper, added: “Bacterial therapies are an exciting way to treat cancer by essentially starving tumours of vital nutrients.

"One longstanding mystery has been why T cells, which are key to fighting cancer, don’t function optimally during this treatment.

“Now, we’ve identified the protein responsible for this, and pinpointed an exciting genetic target that could help us unleash the full potential of this therapy.

"It’s particularly rewarding to turn a disease-causing bug like Salmonella into one that combats cancer.”

While bacterial cancer therapy has been a focus of scientific interest since the 19th century, the dangers to health presented by bacteria had prevented it being explored further.

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Recent advances in genetic modification to make bacteria safe to use have seen a resurgence of research in this area of immunotherapy.

Director of Research at Cancer Research UK, Dr Catherine Elliott, said: “Bacterial therapies have not become mainstream despite the massive strides we are making with immunotherapies which use our own bodies’ immune system to attack cancer.

“But the power of bacteria has long been acknowledged as likely to hold significant potential to tackle disease.

“This exciting development from the Cancer Research UK Scotland Institute could lead to more effective treatments for patients with colorectal, and other cancers in future, providing hope for patients.”

Further research will now be undertaken to use this key discovery to develop future ways of harnessing the power of bacteria in cancer treatment.