‘Safe’ salmonella can teach immune system to fight cancerous tumours
Scientists show injecting food poisoning bacteria can flag the disease and prompt defensive response
By in Boston SALMONELLA can be injected into tumours to flag cancer to the immune system so that it can be quickly cleared from the body, scientists have shown.
Cancer is extremely good at evading the body’s immune system, largely because a tumour is normal tissue that has gone awry, so the body does not see it as an invader.
Some cancers have also evolved in such a way that they can suppress or hide from the immune system.
However, scientists have now shown they can use the salmonella bacteria as a “Trojan horse” to infiltrate cancer cells so the body knows they should be attacked.
Researchers at the Chonnam National University Hwasun Hospital in Jeonnam, South Korea, have engineered a safe form of salmonella that is one million times less potent than the strain that causes food poisoning, but is recognised by the immune system.
Animal trials have been so successful that the team are seeking funding for testing in humans.
In tests on mice with colon cancer, more than half were completely cured without any side-effects. British scientists said it offered a “fascinating new way” to tackle cancer.
Joon Haeng Rhee, professor of microbiology at Chonnam, said: “We believe that this was a kind of groundbreaking trial to turn tumour-helping immune cells, Dr Jekyll, into tumourkilling ones, Mr Hyde. We use very cheap attenuated bacteria to target the tumour tissue and very promptly changed Dr Jekyll into very furious Mr Hyde by inducing salmonella in situ.”
Previous studies have looked at using bacteria such as salmonella to carry anti-cancer drugs into tumours, but it is the first time the scientists have tried using the body’s own response to salmonella to fight a tumour.
They discovered the possibility while working on unrelated research in which they noticed the bacteria that attacked shellfish produced a protein called FlaB, causing a strong immune response.
Prof Kevin Harrington, professor of biological cancer therapies at the Institute of Cancer Research, London, said: “It has been known for some time that certain types of bacteria, including strains of salmonella, are able to grow in tumours but not in normal tissues. However, until now, attempts to use bacteria as anti-cancer therapies have had limited success.”
Rare chickens such as the “Scots Dumpy”, used by the Picts to warn of the approach of the Roman army, could be brought back from the brink of extinction by Edinburgh University. Scientists have genetically engineered chickens that can act as surrogates and lay the eggs of other rare breeds.
At the American Association for the Advancement of Science conference, lead researcher Dr Mike McGrew, of Edinburgh University’s Roslin Institute, which brought the world Dolly the sheep, said: “These chickens are a first step in saving and protecting rare poultry breeds from loss.”