INCREASED LEVEL OF C-ERBB-2 NEU/HER-2 PROTEIN IN CUTANEOUS SQUAMOUS-CELL CARCINOMA/

Overexpression of c-ErbB-2/neu/HER-2 oncoprotein, a receptor tyrosine kinase, has been demonstrated in a variety of human cancers, To elucid ate the involvement of c-erbB-2 in human skin carcinogenesis, we exami ned expression of the protein in skin samples from live cases of kerat oacanthoma (KA), 10 of actinic keratosis (AK), 24 of squamous cell car cinoma (SCC) and 10 of basal cell carcinoma (BCC) and five samples of normal epidermis, using an immunohistochemical method on formalin-fixe d, paraffin-embedded sections, Expression of c-erbB-2 was also examine d in cultured SCC cell lines, a premalignant cell line and in cultured normal keratinocytes, Normal epidermal cells showed no or very little c-erbB-2 protein, but the covering epidermal layer of some tumours sh owed a few strongly positive cells. Samples of KA and AK showed barely detectable c-erbB-2, protein in only a few cases. Twenty of the 24 ca ses of SCC had elevated expression of c-erbB-2 protein, with a tendenc y to more positive cells in metastatic lesions. Five of the 10 cases o f BCC stained for c-erbB-2 but more weakly than those of SCC. Reaction products of the positive cells were seen in the cytoplasm. All three cultured SCC cell lines stained for c-erbB-2 protein more strongly tha n the premalignant HaCaT or normal keratinocytes. Our results indicate the possible involvement of c-erbB-2 overexpression in the malignant conversion of keratinocytes.