Humans have a love-hate relationship with the sun. On the one hand, it's an excellent source of vitamin D that can make bones strong, and it feels wonderfully warming and can give skin a burnished, healthy glow. But too much exposure to the sun’s ultraviolet (UV) radiation can damage the skin’s DNA and contribute to premature aging and skin cancer.
Human skin has a way to defend against the sun’s assault, by turning fair, vulnerable skin darker as a barrier against UV rays, but it’s hardly enough to ward off potential damage. But researchers now think they have developed something that can be applied on the skin and trigger the same tanning process that the sun does — except at a level that can actually protect it from the effects of UV radiation.
In a study published in Cell Reports, Dr. David Fisher, chairman of dermatology at Massachusetts General Hospital, and his team have been studying the skin’s tanning process for more than a decade. Fisher reported 10 years ago on the gene largely responsible for the tan — he found that it was missing in people with red hair and extremely fair skin, who fail to tan.
In their latest report, Fisher and his colleagues found a way to control the tanning process connected to that gene. After testing their skin-darkening agent in mice, they tested it in samples of human skin in a lab dish — the human skin cells tanned just as they would have in the sun, except without the exposure to the harmful UV rays.
"We see pretty potent efficacy in human skin cells," he says. "What I view as a big opportunity here is something that might be able to enhance the protection provided by sunscreens currently."
Fisher says that the lab-tanned skin cells looked indistinguishable from skin cells that were tanned by the sun, meaning they benefited from the protection provided by the darker pigment without the need for exposure to UV rays. Studies have shown that the melanin in tanned skin, which is more prevalent in darker skinned individuals, can protect against UV rays’ damaging effects. Skin cancer rates are lower among darker-skinned people than among those with fairer skin, so darker skin is a plus when it comes to forming a barrier against the sun.
More studies are needed to confirm that the same process could be triggered in people, and not just dishes of skin cells. But Fisher is cautiously optimistic that it can be, since it involves exploiting a naturally occurring process that the body relies upon already.
He believes that combining sunscreen with the darkening tanning product could be an entirely new way to fight skin cancer. While current sunscreens are undeniably important ways to protect the skin from UV, the blocking effect of sunscreens also means skin isn’t raising its natural tanning defense against the sun with melanin, which could potentially leave skin more vulnerable to damage if sunscreen isn’t applied properly and often.
A tanning agent could address that problem, he says, by boosting sunscreen’s protective effect.
"There is unequivocal evidence that sunscreens are protective against several types of skin cancer," he says. "But there is also unequivocal evidence that they are not enough. Just look at the data — skin is the most common site of cancer in people despite the embarrassing fact that UV radiation is broadly recognized as a cause in all common forms of skin cancer. We haven’t conquered this problem. So the concept of combining the darkening agent with a UV blocking agent might provide a whole new dimension of protection."
And, potentially, a much more effective way to lower rates of skin cancer.