Abstract: The ras oncogene product ras p21, which is structurally homologous to G-protein, participates in the regulation of cellular proliferation and differentiation. The histopathology of psoriasis is characterized by hyperkeratosis and parakeratosis. The purpose of this study was to investigate, by dot blot and Dig-DNA labeling in situ hybridization techniques, the expression of c-Ha-ras proto-oncogene in normal skin and active plaque psoriatic lesions. The results showed: (1) dot blot revealed one fold elevation of c-Ha-ras gene transcript levels in psoriatic lesions compared with normal controls. (2) In normal epidermis, only a few basal cells expressed ras gene, however, the ras gene was expressed throughout all layers of epidermis of active psoriatic lesions except horny layer and predominantly in prickle cells. Our results suggest that overexpression of c-Ha-ras oncogene and changes of expression pattern might be central to the pathogenesis of psoriatic epidermal hyperplasia and abnormal pattern of cellular differentiation.

Key words: Oncogenes, Psoriasis