Scientists confirm new route to skin cancer

Cancer Research UK

Cancer Research UK funded scientists at The Institute of Cancer Research have unravelled a complex chain of molecular triggers involved in the development of malignant melanoma, the deadliest form of skin cancer, a study published in Cancer Research* reveals today (Monday).

The researchers discovered how a damaged version of a gene called RAS stimulates the growth of about 15-20 per cent of malignant melanomas.

Understanding more about the behaviour of those genes damaged by the sun that then cause skin cancer is important. In the future it will help scientists develop drugs to target individuals whose cancer developed as a result of a particular genetic fault.

Malignant melanoma, or melanoma, is the most serious type of skin cancer and because of the complicated molecular mechanism behind the disease, it often difficult to treat. And the number of people who get it in the UK is increasing.

Most skin cancers are caused by damage to genes from UV (ultraviolet) rays in sunlight. Melanoma occurs when melanocytes, the cells in the skin that protect us from UV light, grow uncontrollably.

The growth and behaviour of melanocytes are controlled by many different factors. Crucially, faults in the RAF genes are important because they send signals to the cell

telling it to grow. Scientists already know that faults in the B-RAF gene are associated with around 50-70 per cent of melanomas.

However, until now it was not known how a growth signal was generated in the melanomas in which B-RAF is not mutated. This new research reveals that faults in the RAS gene activate another form of RAF, C-RAF, which then substitutes for B-RAF and so contributes to the development of melanoma.

Lead researcher Professor Richard Marais, from The Institute of Cancer Research, said: "We knew that RAS is mutated in up to a fifth of melanoma cases, but did not know how it was able to drive the growth of cancer cells. This research found that RAS activates one of the RAF proteins and from our previous work, we knew that a different RAF protein was implicated in the development of most other melanomas.Knowing more about the behaviour of all the different pathways involved in the development of melanoma could have implications for drug targeting. This discovery has the potential to enable us to develop targeted treatments to repair this particular fault and reverse the effects of the disease.”

Professor John Toy, Cancer Research UK’s medical director, said: "These findings will help improve our general understanding of how melanomas develop and grow out of control. Finding new treatments to effectively target melanoma is of critical importance because cases of the disease are set to treble over the next thirty years. It’s important to remember that 80 per cent of malignant melanomas are due to excess exposure to the sun and these cases could be prevented if we protect ourselves from the harmful effects of the sun."

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Notes to Editor

In melanoma RAS mutations are accompanied by switching signalling from BRAF to CRAF and disrupted cAMP signalling. Dumaz et al. (2006). Cancer Research Vol 66 Issue 19.

This research was supported by Cancer Research UK and The Institute of Cancer Research.

Malignant melanoma

Malignant melanoma, also known as melanoma, is the most serious type of skin cancer. Every year around 8,000 cases of malignant melanoma are diagnosed in the UK. Malignant melanoma causes almost 1,800 deaths each year in the UK.

It usually develops in cells in the outer layer of the skin. The first visible signs of this may be a change in the normal look or feel of a mole.

Melanoma affects adults of all ages. It is one of the few cancers to affect young adults and is the third most common cancer amongst 15-39 year olds. However risk of this disease increases with age.

More women than men develop malignant melanoma. Melanomas in women are most common on the legs and in men they are most common on the back.

When melanoma is caught early it can be treated successfully. However, if a malignant melanoma is left it can spread to other parts of the body and may be fatal.

Non-malignant melanoma

Non-melanoma skin cancer is the most common and easily treated type of cancer. More than nine out of ten skin cancers are this type. There are over 65,000 new cases reported each year in the UK. Nine of out ten non-melanoma skin cancers are easily treatable and unlikely to spread.

These cancers are most common on areas of skin frequently exposed to the sun such as the head, neck, hands and forearms.

People most at risk of skin cancer tend to have:

  • fair skin that burns in strong sun
  • red or fair hair
  • lots of moles or freckles
  • a personal or family history of skin cancer
  • experience of sunburn, especially when young

Skin cancer is very strongly linked to ultra violet radiation (UVR) exposure. UVR is invisible and cannot be felt of the skin. It penetrates skin cells, causing damage that can lead to sunburn, skin ageing, DNA damage and skin cancer. There are three types of UVR, but only two reach the earth’s surface, UVA and UVB. UVC is filtered out by the ozone layer. UVA is responsible for skin ageing and is also likely to cause skin cancer. UVB causes redness and sunburn. Exposure to UVB is a major risk factor for all types of skin cancer.

The strength of UV rays outdoors varies from day to day and according to the time of year. Find out how strong the sun is by looking at the UV Index. The risk of burning depends on the strength of UV rays and your skin type.

SunSmart

SunSmart is the UK's national skin cancer prevention campaign. SunSmart is commissioned by the UK Health Departments and run by Cancer Research UK.

Remember the SunSmart code:

  • Spend time in the shade between 11 and 3
  • Make sure you never burn
  • Aim to cover up with a hat, t-shirt and sunglasses
  • Remember to take extra care with children
  • Then use factor 15+ sunscreen or higher

Also, report mole changes or unusual skin growths promptly to your doctor. For more information about the SunSmart campaign, visit www.sunsmart.org.uk

The Institute of Cancer Research

The Institute of Cancer Research is Europe’s leading cancer research centre with expert scientists working on cutting edge research. It was founded in 1909 to carry out research into the causes of cancer and to develop new strategies for its prevention, diagnosis, treatment and care. Click here for further information.

The Institute works in a unique partnership with The Royal Marsden NHS Foundation Trust, forming the largest Comprehensive Cancer Centre in Europe. This relationship enables close daily contact with those on the frontline in the fight against cancer - the clinicians, the carers and most importantly, the patients.

The Institute is a charity that relies on voluntary income. The Institute is one of the world’s most cost-effective major cancer research organisations with over 90p in every £ directly supporting research.

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