In a breakthrough that could stop cancers turning deadly, scientists have identified an amino acid responsible for spreading tumours around the body.
An international research team has found that the compound, “asparagine”, plays a crucial role in seeding lethal secondary tumours.
While asparagine is produced naturally by the body, it is also absorbed from foods including asparagus, potatoes, dairy, beef, poultry, eggs and seafood.
The discovery suggests people with certain types of cancer — including triple-negative breast tumours, which are notoriously aggressive and difficult to treat — could be protected through a combination of a drug and a specially tailored diet.
“Our work has pinpointed one of the key mechanisms that promotes the ability of breast cancer cells to spread,” said Cambridge University oncologist Greg Hannon, lead author of a paper in the journal Nature. “The results suggest that changes in diet might impact both how an individual responds to primary therapy and the chances of lethal disease spreading later in life.”
While diets have long been advocated as a way of discouraging tumours from forming in the first place, this one would be specifically designed to stop them from metastasising. Although asparagine is found in nuts, seeds, soy, legumes and whole grains, most fruit and vegetables contain little of the compound.
Asparagine has been targeted in cancer treatment since the 1960s. While it is essential for the normal functioning of cells, some blood cancer cells cannot synthesise it and rely on stocks from food. Consequently, an asparagine suppressant called “L-asparaginase” is used against various types of leukaemia.
The new study suggests the drug could be “repurposed” to fight breast, lung, kidney and head and neck cancers, in combination with food restrictions.
The researchers found that when the drug was given to mice with triple-negative breast cancer, mutant cells were far less likely to invade other parts of the body. But when the rodents received food rich in asparagine, the cancer cells spread more rapidly.
When the scientists crunched data from breast cancer patients, they found a link between asparagine and metastasis. Tumours proved most prone to spreading if they had high levels of an enzyme which the body needs to manufacture the compound.
The team now plans an early-phase clinical trial where healthy volunteers receive a low-asparagine diet. If it reduces levels of the compound in the body, the next step will be to trial the diet on cancer patients