Sun-free tan protects against cancer
22 September 2006
Scientists have discovered a new way to protect mice from skin cancer, and give them a real suntan at the same time. In future, could the treatment boost the hopes of paler people, heralding summers free of smelly fake tan and harmful sunbeds?
Antenna investigates...
This story was published in Nature on 21 September 2006.
The researchers' crucial first step was uncovering the molecular secrets of how we get a tan - until now it's been a bit of a mystery.
'For the first time, we've pieced together the tanning process which begins with sunlight hitting the skin. We looked at the changes that occur in different cells and that cause skin to turn darker.'David Fisher, cancer scientist, Harvard University, USA
David Fisher, cancer scientist, Harvard University, USA
Image: Sam Ogden
The scientists worked out how mice tan.
Image: NASA
By understanding how skin cells respond to sunlight, the scientists were able to harness the cells' tanning potential and turn it on without the need for damaging rays. This natural, but sunless, tan protected mice from skin cancer too. |
How does sunlight make our skin tan?
When we sit in the sun, we turn darker because our bodies produce melanin - a pigment that colours our skin. Melanin is also our bodies' natural defence against skin cancer.
How much melanin we produce is partly controlled by a gene called Mc1r. Normally, skin cells start making melanin when they receive a signal from other sunlight-sensing cells. In redheads Mc1r doesn't work properly, so the message never gets through and sunlight doesn't make redheads' skin darken, leaving them vulnerable to burning.
To test whether the effects of this faulty gene could be 'corrected', the scientists genetically engineered mice to be smaller, furrier versions of human redheads.
'We used mice that were genetically engineered to tan very easily and others which were entirely blocked in their ability to tan. These pale mice contained a variation in exactly the same gene associated with red hair and fair skin in people.'David Fisher, cancer scientist, Harvard University, USA
Next, the scientists made a special lotion which specifically targeted the melanin production machinery in an attempt to trigger darkening without a need for sun exposure. They rubbed it onto the skin of the 'redhead' mice and tested it by shining UV light, equivalent to the midday sun on the beach in Florida, onto the furry animals.
The lotion had amazing results. Instead of burning, the 'redhead' mice's skin turned darker in the same way as a natural tan. By boosting melanin production it protected them from skin cancer too - the animals suffered less skin damage from UV light and fewer tumours than mice that had not been lathered with the lotion.
So could this research help people at risk from sunburn and skin cancer?
It's fashionable for fair people to be tanned, but sitting in the sun is a dangerous pastime. Skin cancer is one of the most common kinds of cancer, and the number of cases per year is shooting up alarmingly. It's the ultraviolet (UV) rays in sunshine and sunbeds that are harmful and the paler a person's skin, the more they are at risk.
The lotion protects mice from damaging UV rays like those used in sunbeds.
'We believe the principle shown in our research on mice is likely to be the same in humans, but my hunch is that there will be better ways to carry this out. Mice have much thinner skin, so the drug we used on them won't necessarily work so efficiently on us.'David Fisher
It's always important to cover up in the hottest sunshine.
Image: Stephanie Syjuco
'The major problem with UV light is that it damages DNA, causing short-term burning, inflammation and scarring, as well as skin cancers. All of these are dangerous.'David Fisher |
Even if the protective tan does work on us, it wouldn't be a foolproof way of avoiding damaging UV rays. Cancer experts think the risk would still be high.
'We welcome this advance in our understanding of the tanning process, but it's important to point out that a drug-induced tan alone is unlikely to fully protect people from sunburn or skin cancer.'Hazel Nunn, cancer expert, Cancer Research UK
Hazel Nunn, cancer expert, Cancer Research UK
Image: Cancer Research UK