Expression of desmoglein I and plakoglobin in skin carcinomas

Reduction or absence of cell-cell adhesion molecules has been reported in v arious carinomas and the abnormal expression of these molecules contributes to the invasive and metastatic behavior of malignant tumor cells. In epide rmal keratinocytes, the main cell-cell adhesion systems are adherens juncti ons and desmosomes. Previous studies have shown that, in skin carcinomas, t he decreased expression of E-cadherin, major constitutional glycoprotein of adherens junctions, is associated with the invasive and metastatic ability of the tumor cells. In the present study, we examined the expression of de smoglein I and plakoglobin, the constitutional components of desmosomes, in various skin carcinomas such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), extramammary Paget's disease and Bowen's disease by an imm unofluorescence method. In normal human skin, desmoglein I and plakoglobin were strongly expressed in the intercellular space of the epidermis except for the basal cell layer. In BCC and SCC, the expression of desmoglein I an d plakoglobin was markedly reduced or absent in tumor cells. In carcinoma i n situ of Paget's disease, compared with the normal epidermal cells surroun ding tumor cell nests, the expression of these molecules was reduced in tum or cells. In Paget's disease with dermal infiltration of tumor cells, the e xpression of these molecules was almost absent throughout the epidermis. In Bowen's disease, the expression of desmoglein I was reduced in the clumpin g cells and dyskeratotic cells. These results suggest that the expression o f desmosomal cadherin is reduced or absent in human skin carcinomas, and th at reduction of these molecules may also contribute to the invasiveness and metastasis of skin carcinomas.