Increased expression of uPA, uPAR, and PAI-1 in psoriatic skin and in basal cell carcinomas

There is substantial evidence implicating the urokinase system in tissue remodeling during neo-vascularization, inflammation, tumor invasion, and metastasis. Regulated degradation of the extracellular matrix at the leading edge of migrating cells, mediated by uPA and uPAR, is required for tissue remodeling, invasiveness, and angiogenesis. Psoriasis and basal cell carcinoma (BCC) are the most common skin diseases. Pathogenesis of both of them is associated with keratinocyte hyperproliferation, inflammatory cell migration, and angiogenesis—processes in which the plasminogen system (uPA, uPAR, tPA, and PAI-1) plays a crucial role. In the present study, the comparative analysis of uPA, uPAR, tPA, and PAI-1 expression in the normal skin, in the biopsies of patients with psoriasis vulgaris, and BCC was carried out. uPA, uPAR, and PAI-1 expression was up-regulated in the epidermis of psoriatic skin and in tumor cells in BCC. Increased uPAR expression was detected in the derma of psoriatic lesions and in the stroma surrounding tumor cells in BCC. Increased expression of uPA in epidermal cells in psoriasis and in tumor cells in BCC suggests an important role of the uPA system for aggressively proliferating and invading cells of epidermal origin. A possible activation of the stroma, as a result of uPA–uPAR interaction between tumor cells and the surrounding stroma, is suggested.