RESUMO
BACKGROUND: In a recent report we described RPE65, a protein originally characterized in retinal pigment epithelium, to be expressed in normal human epidermis. RPE65 is suspected to be involved in cellular uptake of retinol which is transported in the bloodstream complexed with plasma retinol-binding protein. OBJECTIVES: To evaluate protein and mRNA expression of RPE65 in actinic keratosis (AK), squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) compared with normal skin. METHODS: RPE65 mRNA expression in skin tumours relative to normal skin of the respective donor was studied by real-time polymerase chain reaction in AK (n = 15), invasive SCC (n = 30) and BCC (n = 18). A peptide-specific anti-RPE65 antibody was used for immunohistochemical staining of formalin-fixed and paraffin-embedded tissue sections of the respective tumours. RESULTS: RPE65 mRNA expression was reduced in AK. A highly significant reduction of RPE65 mRNA was observed in invasive SCC relative to normal skin of the respective donors. Immunohistochemistry revealed a continuous staining of basal and suprabasal keratinocytes in normal human epidermis. RPE65 in AK shown by immunohistochemical staining was reduced and quite irregular, whereas invasive SCC revealed no staining of tumour cells with the anti-RPE65 antibody. RPE65 mRNA values were elevated, whereas immunohistochemical staining for RPE65 protein was heterogeneous in BCC. CONCLUSIONS: These results suggest progressive downregulation of RPE65 from AK to invasive SCC.
Assuntos
Carcinoma Basocelular/metabolismo , Carcinoma de Células Escamosas/metabolismo , Proteínas do Olho/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas de Ligação ao Retinol/metabolismo , Neoplasias Cutâneas/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma Basocelular/patologia , Carcinoma de Células Escamosas/patologia , Proteínas de Transporte , Regulação para Baixo , Proteínas do Olho/genética , Expressão Gênica , Humanos , Técnicas Imunoenzimáticas , Ceratose/metabolismo , Ceratose/patologia , Pessoa de Meia-Idade , Proteínas de Neoplasias/genética , Reação em Cadeia da Polimerase/métodos , RNA Mensageiro/genética , RNA Neoplásico/genética , Proteínas Plasmáticas de Ligação ao Retinol , Neoplasias Cutâneas/patologia , cis-trans-IsomerasesRESUMO
BACKGROUND: Autoantibodies directed against desmoplakin (Dp) I and II have recently been characterized in a subset of patients with severe erythema multiforme (EM), a recurrent inflammatory skin disease with a broad spectrum of clinical manifestations. These autoantibodies recognize a peptide epitope localized within the extreme end of the carboxy terminal domain of Dp responsible for the assembly of keratin filaments to the desmosomal plaque. Using dot blot analysis with overlapping synthetic peptides, the binding epitope YSYSYS has been identified. OBJECTIVES: To establish an enzyme-linked immunosorbent assay (ELISA) for detection of peptide-specific anti-Dp autoantibodies in sera of patients with EM. METHODS: A synthetic peptide containing the respective amino acid sequence was used as matrix for ELISA plates. Serum samples from patients with known EM and peptide-specific anti-Dp autoantibodies verified by immunoblotting, immunoprecipitation and epitope mapping were used. RESULTS: Establishing an index value of 42.0, 25 of 25 serum samples from five patients with peptide-specific anti-Dp autoantibodies were positive in the ELISA. From control sera, none of 31 bullous disease sera and only one (1.2%) of 83 normal human sera were positive. CONCLUSIONS: These data show that the ELISA presented in this study represents a sensitive and highly specific tool for the detection of peptide-specific anti-Dp autoantibodies in patients with EM.