Biomedicine

Melanoma: Beyond the Light

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Science  09 Nov 2012:
Vol. 338, Issue 6108, pp. 723
DOI: 10.1126/science.338.6108.723-c

Despite successful implementation of strategies that reduce exposure to ultraviolet radiation, the incidence of melanoma—the least common but most fatal form of skin cancer—continues to rise. This observation, together with the fact that melanomas can occur on non–sun-exposed skin, indicates that additional mechanisms independent of ultraviolet light contribute to tumorigenesis.

CREDIT: ISTOCKPHOTO

A new mechanistic clue has emerged from a mouse study designed to investigate why people with red hair and fair skin have the highest risk of developing melanoma. One distinguishing characteristic of these individuals is that they produce the red/yellow pigment pheomelanin. Mitra et al. found that genetically manipulated mice with pigmentation mimicking the human red-hair trait developed invasive melanoma at a higher rate than did mice with pigmentation mimicking dark-skinned humans, even in the absence of exposure to ultraviolet radiation. Selective ablation of pheomelanin synthesis by introduction of an albino allele protected the mice against melanoma. This suggests that pheomelanin itself plays a causal role in melanoma development, at least in mice, possibly by inducing oxidative damage to skin cells.

Nature 10.1038/nature11624 (2012).

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