Sept. 20, 2006 -- Fair-skinned people who yearn for a suntan -- even though they know it's hopeless and unhealthy -- may one day have cause for celebration.
Harvard scientists have discovered new information about how the skin tans or -- in the case of fair-skinned people -- stubbornly refuses to tan due to a genetic defect. Using a skin treatment, they have turned pale skin dark, while also protecting it from ultraviolet-induced .
"Darkening a person's skin may mimic the protective benefit seen in people who otherwise make a large amount of pigment," says researcher David E. Fisher, MD, PhD, director of the Melanoma Program at Dana Farber Cancer Institute in Boston. And that could translate into a reduction in the toll of the potentially deadly skin cancer melanoma, expected to be diagnosed this year in 62,000 people in the U.S. and to result in 8,000 deaths, according to American Cancer Society projections.
The study appears in the Sept. 21 edition of the journal Nature. Fisher cautions that the study was done only in animals. Using a topical cream instead of the sun's rays, Fisher's team was able to switch on the tanning mechanism in the skin cells of fair-skinned mice, turning them into olive-skinned animals. "This has not been demonstrated in people and there is a lot that needs to be proven before it's ready for even a first attempt in clinical subjects," Fisher says.
Even so, the study was called intriguing by Meenhard Herlyn, DVM, PhD, a tumor biologist at The Wistar Institute, a research center on the campus of the University of Pennsylvania. "What he clearly has shown is ... you can induce a pigmentation, tanning, and the purpose is that people who are very susceptible to skin cancer, including melanoma, can be protected."
Like much of science, the finding was accidental, Fisher says. "We were attempting to generate mouse models to study the ability of ultraviolet radiation to induce melanoma in the skin," Fisher says. They used mice whose fair skin came from the same genetic roots as fair-skinned people. "We ran into this technical difficulty, that no matter what we did, the red-haired mice sunburned. We've proven what people had known for thousands of years -- redheads don't tan."
But the finding, Fisher says, was much more rigorous evidence than the long-standing observation. They decided to take a closer look at what happens when the skin tans -- or in the case of fair-skinned people, doesn't tan.
In fair-skinned people, a receptor for the melanocyte-stimulating hormone, which induces pigment production from melanocyte cells, often has small changes in the genetic sequence, which make it function poorly. Fisher's team studied mice that were engineered to have this mutation.