Researchers at the Fox Chase Cancer Center in Philadelphiafound that very low levels of ultraviolet light (UVB) can betumorigenic for cultured skin melanocytes from geneticallysusceptible mice, while skin cells from normal mice are notaffected by the same amount of radiation.

The scientists developed a transgenic mouse model formelanoma to test the various factors that are thought to beresponsible for this deadly cancer: genetic susceptibility,ultraviolet radiation and the degree of skin pigmentation.

Genetic predisposition, therefore, seems to play a role in thedisease. Lionel Larue, Nancy Dougherty, and Beatrice Mintzreported their findings in Wednesday's issue of Proceedings ofthe National Academy of Sciences.

The transgenic mice in these experiments housed the Tyr-SV40E transgene, which "leads to skin and eye melanomasinitiated by simian virus 40 oncogenic sequences driven by thetyrosinase gene promoter expressed in pigment cells," thereport said.

A single exposure to low-intensity radiation -- mainly UVB --transforms transgenic mouse skin melanocytes in culture.These cells are tumorigenic when inoculated into immune-deficient hosts.

The researchers are quick to point out that their mouse modelsystem should not be construed as a literal model for humanmelanoma. Rather, it is a way to control and test the variablesimplicated in this disease --something that just can't be done inhumans.

-- Jennifer Van Brunt

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