Researchers from Massachusetts General Hospital have discovered that the increased melanoma risk for redheads appears to be chemically related to the generation of reactive oxygen species, raising the prospect that antioxidant treatments may be able to reduce the risk. The new findings appear in the journal Nature.
"We've known for a long time that people with red hair and fair skin have the highest melanoma risk of any skin type. These new findings do not increase that risk but identify a new mechanism to help explain it," says David Fisher, senior author of the Nature paper. "This may provide an opportunity to develop better sunscreens and other measures that directly address this pigmentation-associated risk."
Fisher explained that several types of the pigment melanin are found in the skin: a dark brown or black form called eumelanin, predominant in individuals with dark hair or skin, and a lighter blond-to-red pigment called pheomelanin, the predominant pigment in individuals with red hair, freckles and fair skin.
Red/blond melanin is known to be less effective than dark melanin in shielding against UV damage, but there were several hints that the incidence of melanoma in individuals of that skin type may not be fully explained by limited UV protection. Chiefly, while the increased risk of non-melanoma skin cancers is limited to sun-exposed areas, the melanoma risk also applies to areas of skin not exposed to sunlight.
In their search for additional unknown contributors to melanoma development, the researchers used strains of mice that were nearly identical genetically except for the gene that controls the type of melanin produced. One group of dark-colored mice had the typical variant leading to a predominance of dark melanin. Another group of mice had a "red hair-fair skin" version, the same variant that produces red hair and fair skin in humans.
Experiments eventually demonstrated that the red-pigment-associated risk appeared to be chemically related to the generation of reactive oxygen species - unstable oxygen-containing molecules that can damage cells and trigger cancer.
While this result suggests antioxidant treatments may be able to reduce this risk, Fisher cautions that further research is needed to identify safe and effective ways to exploit this knowledge. "Antioxidant treatments are not highly predictable in their actions and in some instances have even been seen to increase rather than prevent oxidative damage. Therefore we need to determine how to control this pathway safely and effectively," he said. "Right now we're excited to have a new clue to help better understand this mystery behind melanoma."
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Source: Massachusetts General Hospital