RESUMO
BACKGROUND: Melanoma is one of the highest metastatic cancers and its incidence is rapidly increasing. A great effort has been devoted to determine gene mutations and expression profiles in melanoma cells, but less attention has been given to the possible influence of melanin synthesis in melanocytes on melanomagenesis. SLC7A11 encodes the cystine/glutamate antiporter xCT and its expression increases the antioxidant capacity of cells by providing cysteine that may be used for glutathione (GSH) synthesis. Melanocytes, however, can also use cysteine for pheomelanin synthesis and pigmentation. Therefore, pheomelanin synthesis may lead to chronic oxidative stress. Possible consequences of this for melanomagenesis have never been explored. METHODS: We quantified the expression of SLC7A11 and other genes that are involved in the synthesis of pheomelanin but do not regulate the transport of cysteine from the extracellular medium to the cytosol (CTNS, MC1R, ASIP and SLC45A2) in non-tumorous skin of 45 patients of cutaneous melanoma and 50 healthy individuals. We controlled for the effects of Fitzpatrick skin type, age, gender, body mass, frequency of sun exposure and sunburns and number of melanocytic nevi, as well as for the intrinsic antioxidant capacity as given by the expression of the gene NFE2L2. RESULTS: The expression of SLC7A11, but not of the other genes, was significantly higher in melanoma patients than in healthy individuals. This was independent of phenotypic factors and antioxidant capacity, thus supporting an effect of pheomelanin-induced oxidative stress on melanomagenesis. CONCLUSION: Our findings indicate that SLC7A11 downregulation in normal epidermal melanocytes may represent a preventive treatment against melanoma.
Assuntos
Sistema y+ de Transporte de Aminoácidos/biossíntese , Melanoma/metabolismo , Neoplasias Cutâneas/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Sistema y+ de Transporte de Aminoácidos/genética , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Melanoma/genética , Melanoma/patologia , Pessoa de Meia-Idade , Gravidez , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Adulto JovemRESUMO
Las manifestaciones cutáneas de la granulomatosis alérgica de Churg-Strauss (síndrome de Churg-Strauss) se presentan en dos tercios de los pacientes. Presentamos el caso de una mujer de 37 años con un granuloma necrosante extravascular de Churg-Strauss como manifestación cutánea de la granulomatosis alérgica de Churg-Strauss. Aunque la presentación clínica era típica, fueron precisas tres biopsias cutáneas para su diagnóstico. El granuloma necrosante extravascular de Churg-Strauss consiste en un granuloma en empalizada con degeneración basófila del colágeno, infiltración por neutrófilos y leucocitoclasia. Aunque inicialmente descrito como específico de la enfermedad de Churg-Strauss, se ha observado en otras vasculitis sistémicas y en diversas enfermedades del tejido conectivo y linfoproliferativas. (AU)
