DOI: 10.1097/01.COT.0000291282.01281.43
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Issn Print: 0276-2234
Publication Date: 2005/11/10
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Excerpt
The scientists noted that current skin cancer prevention efforts (sunscreens, wide-brimmed hats, and protective clothing) are aimed at blocking solar radiation, but they do not address the cellular and molecular events responsible for sunlight's damage to skin.
Differences in how ultraviolet light affects the photochemistry of human pigments may help to explain why red-haired, fair-skinned people are more prone to develop skin cancer than those with black hair and darker skin, said John D. Simon, PhD, the George B. Geller Professor of Chemistry and Vice Provost for Academic Affairs at Duke University.
Noting that he has spent 10 years on this research, Dr. Simon said his working hypothesis is that people of Celtic origin with reddish hair have more pheomelanin (red pigment) than people with black hair, who have more eumelanin (black pigment), and that pheomelanin is more photoreactive and photolabile than eumelanin.
Because pheomelanin allows more light absorption, it gives rise to more highly reactive oxygen-activated free radicals—which can ultimately lead to skin cancer, Dr. Simon has hypothesized.
“Up until now, there has been no systematic study of the two human pigments to determine whether there could possibly be a link between skin cancer rates and the chemical and photochemical properties of the pigments.”
Now, his research has shown that there is a significant difference in the way the human red and black pigments react in cells to oxidative stress caused by free radicals, noted Dr. Simon, who has studied melanosomes from hair shafts and retinal pigment epithelium.
He and his colleagues used the application of an innovative technology, ultraviolet free electron laser photoelectron emission microscopy (UV-FEL-PEEM) to measure the oxygen-activating potentials of pigments from red-haired and black-haired people. The technology for Dr. Simon's measurements was provided by Duke University's Free Electron Laser Laboratory.
After doing the research using UV-FEL-PEEM, “we find that the red pigment is more reactive than the black pigment, suggesting that the stress in cells does in fact result in part from the different chemical properties of the pigments,” he said.
“This is the first measurement to ever be reported that compared the two human pigments, and also clearly links the red pigments to possible oxidative stress through their electrochemical properties.
