NAD(P)H:Quinone Oxidoreductase 1 Expression in Human Primary Melanotic Melanomas of the Skin

NAD(P)H:quinone oxidoreductase 1 (NQ01; DT-diaphorase; DTD) is a two-electron reducing enzyme which is often over-expressed in cancers and can activate quinones to form cytotoxic species. This over-expression is used as target in the design of novel anti-cancer drugs. DTD is also expressed in normal tissues, but little is known about its “body mapping”. Because of the dearth of information on the cell-specific expression of DTD in pigmentproducing cells of the skin, we analysed its expression in normal and tumoral samples. Twenty skin biopsies of primary malignant melanotic melanomas (ten with vertical invasion, ten with superficial spreading) were analysed by immunohistochemistry. In normal skin DTD expression was weak in all epidermal layers, including normal melanocytes. Malignant melanomas showed a very strong DTD expression in tumoral cells of all samples and in endothelial lining of peri-tumoral vessels. These results suggest that DT-diaphorase may be a new marker that could be useful in determining the extent of a malignant melanocytic lesion, and also tend to support the potential of malignant melanomas as target for DTDdirected antitumour agents.