Natural hormone ‘turbo charges’ the immune system to fight off cancer by blocking a protein that causes tumours to take hold
- Natural Killer (NK) cells prevent both the growth and spread of tumours
- Protein activin-A blocks NK cells, which is a key way cancer takes hold
- Hormone follistatin inhibited activin-A in cells in the laboratory
Scientists have discovered how to ‘turbo charge’ the immune system to help in the fight against cancer.
Natural killer (NK) cells, the ‘soldiers’ of immunity, prevent both the growth and spread of tumours.
Australian researchers discovered the protein activin-A blocks NK cells, which is thought to be one of the key ways cancer takes hold.
Using the naturally-occurring hormone follistatin, the team inhibited activin-A in human and mouse NK cells in the laboratory.
The researchers believe their study ‘opens the door’ to new drugs that provide a ‘deeper and more durable way to overcome the immune suppression seen in cancer’.
Scientists have discovered how to ‘turbo charge’ the immune system to fight cancer (stock)
The study was carried out by the University of Queensland and Monash Biomedicine Discovery Institute.
Study author Professor Nicholas Huntington, of Monash, said: ‘These findings may open the door to novel immune-therapy drugs.
‘[These] provide a deeper and more durable way to overcome the immune suppression seen in cancer, improving patient outcome.’
One in two people born after 1960 in the UK will develop cancer at some point in their lives, Cancer Research UK statistics show.
And in the US, around 1.7 million new cases were diagnosed last year alone, according to the National Cancer Institute.
Chemo is often a go-to treatment, however, it can fail if surviving cells mutate to become resistant to its mechanism.
NK cells have been shown to protect against the development and spread of cancer, the researchers wrote. Malignant tumours have also been linked to NK cell suppression, they added.
However, the signals that inhibit NK cell activity were largely a mystery.
Writing in the journal Science Signaling, the Australian scientists discovered activin-A blocks the division of NK cells in the laboratory.
The protein, which is found in healthy and malignant human cells, reduces the production of the enzyme granzyme b. This is released by NK cells to trigger tumour ‘suicide’.
Follistatin then inhibited activin-A’s action in both human and mouse NK cells in the laboratory. The hormone also slowed melanoma growth in the rodents.
Previous studies have linked activin-A to ‘malignant cellular reprogramming’ in breast and ovarian cancer.
High circulating amounts of the protein have also been associated with tumour progression and poor prognosis in lung cancer.
Follistatin, which is involved in muscle mass and strength, has been shown to inhibit the ‘biological activity’ of activin-A.
HOW DO TUMOURS GROW?
Cancer cells initially stay within the body tissue from where they developed, for example the breast ducts.
They then grow and divide to create more cells, which end up being a tumour. A tumour may contain millions of cancer cells.
All body tissues are surrounded by a membrane that keeps its cells inside. If cancer cells break through this layer, the tumour is called invasive.
As a tumour grows, its centre moves further away from the blood vessels in the area where it is growing.
This causes the centre to have less oxygen and nutrients, which cancer cells cannot live without. They therefore send out signals, called angiogenic factors, that encourage new blood vessels into the tumour.
Once a tumour has its own blood supply, it can rapidly expand by stimulating the growth of hundreds of new capillaries to bring it oxygen and nutrients.
As it grows, the mass puts pressure on surrounding structures. But how it enters these tissues is not fully understood.
One theory is it forces itself into normal tissue. This blocks blood vessels, which causes the healthy tissue to die and makes it easier for the cancer to continue to spread.
Many cancers also contain high levels of enzymes that break down healthy cells and tissues.
They also produce a mysterious substance, which growing research suggests stimulates them to move, however, this is unclear.
Source: Cancer Research UK