Immunohistochemical detection of ras P21 oncoprotein in human skin lesions

This study was undertaken to investigate the role of the human ras family gene product [P21] in various benign, precancerous and malignant skin lesions. A streptavidin-biotin peroxidase method was performed using the monoclonal antibody (Mab)Y13259 in paraffin tissue sections of a total of 69 skin lesions (5 benign hyperplasias, 12 seborrheic keratoses, 9 solar keratoses, 20 basal cell carcinomas and 23 squamous cell carcinomas). The adjacent normal skin was also studied in all cases. The expression of ras P21 was evaluated and graded in relation to the intensity of cytoplasmic immunostaining and the percentage proportion of positive epidermal cells. The following findings were noted in this study: 1) The positivity of ras P21 increased towards the keratin layer, according to cell maturation, in all normal, hyperplastic and "borderline" lesions, and to a lower degree in the seborrheic ones. 2) Comparing B.C.C. and S.C.C., higher expression was demonstrated in the latter, probably due to the high percentage of the well differentiated component.