The incidence of Melanoma, a type of skin cancer, is rising faster than any other form of cancer in the world. In the United States there are about 62,000 cases each year, most due to the harmful ultraviolet rays of the sun.
Light-skinned, red-haired people who burn easily and don't tan are most at risk of developing melanomas. That's because the cells on the surface of their skin cannot be activated to make darker pigment or tan.
David Fisher and colleagues at Dana Farber Institute http://dana-farber.org and Children's Hospital in Boston experimented with red-furred, light-skinned mice in an effort to trigger the pigment response. He says the goal was to reactivate the pathway just beyond the point where there was a block to the tanning path. "The idea was to see whether we could reactivate a tanning response, and that's exactly what we saw."
The scientists applied a topical cream that, as Fisher and colleagues describe it, "switched on the tanning mechanism" in the cells of the fair-skinned mice. "What we saw is that after several days, and then in a progressive fashion, the skin began to get darker and darker until ultimately after doing this once a day, five days a week, within a couple of weeks the mice were nearly black."
The induced-tanned skin was chemically indistinguishable from naturally darker skin and remained protected against sunburn and skin cancers until the sunless tan faded.
Fisher says available sunless tanning creams are cosmetics, work like dyes and don't provide protection against the sun. "Whereas the approach that we are taking is more to understand the actual pathway and reactivate it, because that pathway and the dark pigmentation that occurs in people is actually, in epidemiological studies, the most powerful predictor of protection against skin cancer in human populations."
Fisher says the research could lead to better protection against skin cancers. But he says much more research needs to be done before trials can begin in humans. "The first step is to verify that the biology, that the science of how this pathway works, is indeed really the same in human as in mouse. The second is to find drugs that will be capable of penetrating into the human skin and hit that target with the appropriate activity. And the third, and by no means less important requirement, is that we need to know that what we are doing is safe."
The study was published in the Journal Nature.