Philadelphia - Public health officials, physicians, and others have for some years been warning that overexposure to the sun - in particular, the ultraviolet component of sunlight - is an important risk factor for developing melanoma, the most dangerous form of skin cancer. The advice, however, has been based on epidemiological associations between sun exposure and melanoma, statistical analyses of data about large groups of people over their lifetimes, rather than demonstrable links.
Now, in a new laboratory study, researchers at The Wistar Institute have confirmed that exposure to ultraviolet light can trigger melanoma.
"Despite widespread awareness that excessive exposure to the sun can increase one's risk of developing skin cancer, this is the first direct evidence showing a cause-and-effect relationship between the two," says Wistar professor Meenhard Herlyn, D.V.M. Herlyn is senior author on the study, which appears in the March issue of the American Journal of Pathology.
To investigate the connections between ultraviolet light and melanoma, the scientists first grafted patches of human skin onto the backs of mice. Then, in order to accelerate a disease process thought to unfold over many years, they used a gene-therapy technique to induce overproduction in the mice of an otherwise naturally occurring growth factor. When the skin was exposed to ultraviolet B, a variety of pathological changes in the skin known to be melanoma precursors were documented in many of the mice, with overt melanoma seen in some.
The first author on the study is Carola Berking, M.D. Other Wistar co-authors include Richelle Takemoto, B.S., and Kapaettu Satyamoorthy, Ph.D. Rosalie Elenitsas with the University of Pennsylvania School of Medicine is also a co-author. Support for the research was provided by grants from the National Institutes of Health and a postdoctoral research fellowship for Berking from Deutsche Forschungsgemeinschaft.