Salmonella bacteria could be used to treat bowel cancer, scientists hope.
Bowel cancer is the second most common cause of cancer death in the UK after lung cancer, with around 16,800 deaths per year.
Scotland is “disproportionately” affected, with around 4,000 people being diagnosed each year, according to Cancer Research UK.
Bacterial cancer therapy has been a focus of scientific interest since the 19th century but the health risks prevented it being explored further, although it led to developments in immunotherapy research.
Recent advances in genetic modification to make bacteria safe caused a resurgence of scientific interest, amid hopes of a breakthrough by Cancer Research UK-funded researchers in Glasgow and Birmingham who hope that “disease-causing” salmonella could be used to tackle bowel cancer.
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.
New research on mice pinpointed the mechanism that causes the immune system to be suppressed and offers a solution.
A paper, published on Tuesday in the journal EMBO Molecular Medicine, studied the response of T cells to a specially engineered safe form of salmonella in mice with colorectal cancer.
Researchers found that the salmonella prevents T cells, key immune cells that help protect the body from infection and cancer, from doing their job and stops colorectal cancer cells in their tracks.
Scientists found that salmonella depleted an amino acid, asparagine, which suppresses tumour growth, but also suppresses T cells by stopping their metabolic processes.
The researchers believe that salmonella could be further engineered to work alongside the immune system so T cells can attack cancer cells alongside the bacteria, with further research due to be undertaken.
Lead researcher Dr Kendle Maslowski, of the Cancer Research UK Scotland Institute in Glasgow and the University of Glasgow, 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.”
First author Dr Alastair Copland, a research fellow in immunology at the University of Birmingham, said: “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.”
Dr Catherine Elliott, director of research at Cancer Research UK, said: “Bacterial therapies have not become mainstream despite massive strides in 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.”
Published: by Radio NewsHub
