Cell protein holds key to melanoma spread

In collaboration with the Press Association

A team of international scientists has made a significant stride forward in understanding how malignant melanoma cells can evade cancer therapy and spread around the body.

Malignant melanoma is the most serious form of skin cancer, and is very difficult to treat if caught late, as it can metastasise, or spread, with ease.

The research found that a protein called Mitf was responsible for regulating the way melanocytes - the cells which cause melanoma when they become damaged - grow and divide.

When the level of this protein inside a melanoma cell drops, the cancer cell changes its behaviour: it stops growing and 'blends in' with its neighbours.

This makes it less likely to be affected by chemotherapy drugs, which are designed to target fast-growing cells.

Conversely, when Mitf levels rise again, the cells start growing and dividing rapidly, and spreading.

The team found that the process that controls Mitf levels - known as 'epigenetic modification' - is readily reversible.

This could help explain why the spread of melanoma is so hard to treat - the cells can switch easily from a fast-growing form, susceptible to chemotherapy, to a 'dormant' form that can hide away in tissue and evade chemotherapy.

"The problem is that once a melanoma has spread to other parts of the body, it becomes very difficult to treat," Dr Charlotte Proby of Cancer Research UK told the BBC.

"After five years, fewer than ten per cent of patients in this situation are alive.

"The main feature of melanoma that governs the likelihood of spread is the thickness of the initial tumour.

"Thin melanomas - 1mm or less thick - are very treatable, while if the tumour is 4mm thick or more, it is much more likely that it will have metastasised."

The study is published in the journal Genes and Development.