Sun-free tanning could keep skin safe from UV radiation

People with red hair know only too well that the genes that code for their glorious locks come bundled with others that bring higher than normal sun sensitivity – placing them at greater risk of skin cancer.

Research published in the journal Cell Reports reveals a potentially novel form of protection against ultra-violet radiation induced cancer: a class of molecules that can create an artificial tan.

A team led by David Fisher of the Massachusetts General Hospital in the US has designed molecules capable of suppressing a type of enzyme known as Salt Inducible Kinase in skin cells, triggering a boost to pigment-producing genes.

The molecules are applied topically, once fully developed, rather like a sunscreen. Increased pigmentation production then darkens the treated skin, making it more resistant to the damaging effects of ultra-violet radiation.

And just like a tan, the darkening fades after a few days, as the body routinely sheds its outer skin cells.

So far the molecules have been tested on human skin, cultured in a petri dish, and genetically engineered red-haired mice – which, the study reports, turned almost jet black after a hefty dose.

However, Fisher cautions that his tanning molecules – developed in collaboration with Nathanael Gray of the Dana-Farber Cancer Institute in Boston, US – are still a long way from coming to market.

“Human skin is a very good barrier and is a formidable penetration challenge,” he says.

And he should know: he’s hardly a newcomer to the quest for ultra-violet protective pigmentation-inducing topical treatments.

In 2006 he was part of a team that developed a compound from forskolin – a substance derived from the root of a member of the mint family – and demonstrated that it induced skin-darkening in mice.

The animal tests were promising, but the compound did not work for humans. This is mainly because our species has evolved to be almost hairless, and has developed super-tough, comparatively impermeable skin as a result. The forskolin molecules were simply too large to penetrate cell walls.

(Forskolin, by the way, has lately developed into a firm favourite of the natural health industry, claimed as beneficial in range of areas, from weight loss to asthma to heart disease. The substance is a research target for many serious scientists but so far there is little evidence to support the claims made for it.)

The new class of molecules developed by Fisher and Gray are small enough to enter human skin cells, and also have a strong ability to pass through fats – something else forskolin molecules had trouble with.

Testing the molecules on human breast skin maintained in Petri dishes, the team found the effects were robust, and correlated precisely with dosage: larger amounts produced more pigmentation on a predictable scale.

Fisher hopes the work will lead to more effective skin cancer protection for every one – but especially redheads, who are at substantially higher risk.

“We believe the potential importance of this work is towards a novel strategy for skin cancer prevention,” he says.

“Skin is the most common organ in our bodies to be afflicted with cancer, and the majority of cases are thought to be associated with UV radiation. But we’ve found that the picture is more complicated, that red-blonde pigments are also more intrinsically carcinogenic.”