Human cell adhesion molecule uvomorulin is differentially expressed in various skin tumors

The cell adhesion molecule uvomorulin is important in cell recognition processes, both during tissue formation in embryonic development and in the maintenance of adult epithelia. In addition, uvomorulin appears to play a crucial role in carcinogenesis. Therefore, in the present study, the expression of uvomorulin in normal human skin and several benign and malignant proliferative skin lesions was evaluated by immunofluorescence microscopy using affinity purified antibodies. In normal human epidermis, basal and suprabasal keratinocytes showed a strong and homogeneous staining of the cell membrane. In contrast, uvomorulin expression was decreased in squamous cell, as well as in solid basal cell, carcinoma. Interestingly, solid basal cell carcinoma showed a dimorphic staining pattern with a reduced fluorescence of the inner cell layers and normal staining of the peripheral basal cells. In contrast, no such dimorphic staining pattern could be observed in squamous cell carcinoma, in which uvomorulin expression was homogeneously reduced. Decreased expression of uvomorulin was not specific for malignant skin lesions, since it could also be observed in condylomata acuminata. These studies demonstrate that human uvomorulin is differentially expressed in proliferative skin disorders, which may account at least in part for the differences observed in the clinical course between squamous cell and basal cell carcinoma.