Trending Science: A summer suntan… without the cancer risk

With the start of summer, which some forecasters predicting will be the warmest summer for fifty years in Western Europe, many will be hoping to banish the pasty white skin of winter with a suntan developed after hours on the beach or in the park. Of course, this often means that people expose their skin to harmful UV rays without adequate protection, increasing the risk of skin cancer.

Now a team of scientists from the Massachusetts General Hospital have created a new compound that will give human skin a suntan without the need of the sun. Whilst it hasn’t yet been tested in clinical trials (just in mice and on patches of human skin leftover from surgeries) doctors are hopeful that it could one day be used as a potent weapon against skin cancer by keeping people away from UV rays. ‘It would not actually be a fake tan, it would be the real thing,’ said Professor David Fisher, who led the work on the new compound. ‘It would just be sunless.’

People with darker skin tones and those who tan easily have a far lower risk of melanoma, the deadliest form of skin cancer. The dark pigment, melanin, dissipates more than 99.9 % of absorbed UV rays, limiting radiation damage to cells that could be the springboard for cancer to develop. The new compound has its origins in a strain of ‘redhead’ mice with rust-coloured fur. The rodents harbour a variant of a gene called MC1R that gives rise to red hair and fair skin in humans. MC1R dictates whether a person tans or burns easily in the sun. In people who tan, this gene sets off a cascade of reactions during sun exposure that results in the production of melanin. The reason why people graced with red hair are so prone to burn in the sun is because the chain reaction that leads to the production of melanin doesn’t occur within their skin cells.

The researchers reasoned that they could help people tan in a way that was harmless to their skin and long-term health by finding a way to stimulate this melanin-making process. They targeted a protein called salt-inducible kinase (SIK), which essentially works as the ‘master on/off switch’ for melanin production, at a point further down the chain from where MC1R acts a block.

Applying the protein as a liquid to the shaved backs of redhead mice for a period of 7 days, they reported that the mice’s skin had turned almost jet black. The colour faded over a week or so, as would happen with a natural tan as skin cells replicate and replace themselves. Other than the darkened skin, the mice suffered no other obvious side-effects. They then applied the compound, modified to penetrate human skin, to human skin samples discarded from surgical procedures in a petri dish, resulting in a dark brown splotch. This indicated that the compound was able to spur melanin production. However, Professor Fisher is careful to assert that if the new compound is ever developed to be commercially available, it would not replace protective sun cream but would merely complement it. Because the compound simply ramps up melanin production, it should work on all skin types but be especially useful for people with fairer skin and hair.

Professor Fisher and his colleagues are indeed now looking for a commercial partner to carry out further testing in human trials. ‘It’s obviously critical that safety and toxicity studies need to be done,’ said Fisher. ‘This is not a toy, [nor] is it a cosmetic.’

The research has recently been published in the journal ‘Cell Reports.’