These days, redheads the world over are acutely aware of the dangers they run by exposing themselves to the sun. In exchange for their fiery locks, they are unfortunately subject to a 40% increase in the risk of being diagnosed with melanoma, the most aggressive type of skin cancer. So far, our understanding of why that is has been extremely limited. We have known for a long time that the increased cancer risk is linked to a specific variation of the MC1R gene, which is also responsible for the freckles and pale skin tone that is usually associated with red hair. However, new data from a study recently published in Nature has shed new light on the mechanism behind the increased risk – and on what science can do to help.
In healthy humans, the skin contains special cells that produce pigment, interspersed with regular skin cells. These cells are known as melanocytes and they produce a pigment called melanin. Melanin is produced in response to UV light to protect the rest of the skin cells from the harmful effects of UV radiation: in a way, it is the body’s own way to apply sunscreen. Melanin production is the reason we tan when we are exposed to the sunshine and it is very important to protect the skin. People with pale skin and red hair tend to have less efficient melanin production, which is why they find it hard to tan before they become sunburnt. In particular, inside a single melanocyte MC1R is essential to drive melanin production after the cell becomes stimulated with UV light. In redheads, MC1R is present in a defective variant (which is known as the RHC variation), which means that UV exposure is not efficiently translated into melanin production. This recent study has shown that in order to function correctly, the MC1R molecule has to be palmitoylated – which means it needs to be modified inside the cell by adding extra fatty acid chains to it (such as palmytic acid). This is not just an interesting science fact, but it can help redheads fight the risk of melanoma.
Melanoma is a cancer that arises when melanocytes become transformed and start multiplying uncontrollably. While it is relatively rare, it is becoming more and more common. Unfortunately, unlike other types of skin cancer it is incredibly aggressive and patients who are diagnosed with the disease at an advanced stage have a very low chance of survival. Since UV damage is one of the key reasons melanocytes turn into cancerous melanoma cells, it makes sense that people with red hair and lower ability to defend themselves from UV radiation would be more at risk for the disease. The idea behind these recently published work is that since MC1R needs to be palmitoylated in order to function properly, we can give redheads at especially high risk of being diagnosed with skin cancer drugs that will palmitoylate MC1R inside the cells before the cancer develops. This will make the defective MC1R in the melanocytes function more effectively, which in turn means that the melanocytes will be able to produce more melanin and defend themselves from UV radiation, in turn hugely decreasing the risk of melanoma.
Of course, these pre-emptive therapies are still a long way off from being available to patients. In the meantime, the safest thing to do for those with pale complexions (and in fact for everyone) is to use sunscreen responsibly, avoid excessive exposure to the sun and most definitely avoid tanning booths, which deliver an impossibly high dose of UV rays to the skin.