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Researchers Identify Substance Which Protects Against UV Skin Damage
Heralds Possible Agent for Skin Cancer Prevention
A substance called pTpT enhances a skin cell's natural ability to repair DNA damage from ultraviolet (UV) radiation, according to researchers from the Boston University School of Medicine. The finding suggests the possibility that topical agents could eventually be created which not only induce tanning, but also lower the risk of skin cancer. Their discovery was reported in the November 11 issue of the Proceedings of the National Academy of Sciences. According to co-author Barbara Gilchrest, MD, chair of the department of dermatology and professor of dermatology at the Boston University School of Medicine, the study extends the finding, reported in Nature in December 1994, that pTpT promotes tanning by inducing melanocytes (skin pigment cells) to produce melanin. "Tanning is the body's natural response to UV damage, so that the cell's DNA is protected from further UV radiation. Since we knew that pTpT could induce the tanning response, we reasoned that it might also protect against UV light in other ways. Our study confirms that hypothesis," she says. The scientists irradiated normal skin cells (keratinocytes and fibroblasts) with damaging doses of UV light, then measured how well the damage was repaired and how well the cells survived. They then compared the results in otherwise identical cells that had been pre-treated with pTpT. The "plain" cells exhibited the normal response to UV damage and eventually began to repair the damaged DNA. But the pTpT-treated cells repaired the DNA much faster. "Not only does pTpT induce tanning, but it primes the cell to protect itself by enhancing DNA repair capacity," Gilchrest says. Although more research is needed, Gilchrest believes that pTpT may have clinical applications one day. "A skin tanning lotion containing a pTpT-like substance would not only produce a tan, but in addition treated skin might be innately better able to deal with whatever UV damage it might encounter. With this substance, we could lower the overall risk of skin cancer," she says. Approximately 1 million people in the United States develop skin cancer every year, and more than 40,000 develop melanoma, the most deadly form of skin cancer. Roughly 9,300 Americans each year die from some form of skin cancer.
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