The expression of skin-specific gene K51 in the epidermal layer of human skin and in basal cell carcinoma cells.

Gene K51 probe isolated previously from the rat genomic library has been used to study the expression of its human counterpart by in situ hybridization and Northern blot analysis. A polyA-containing transcript of human gene K51 of 3 kb size has been detected in embryonic skin. The gene is also expressed in the epidermis of newborn humans and adults, but not in the adjacent mesenchymal tissues. Immunostaining with keratin antisera revealed predominantly earlier stage expression of K51 than cytokeratin markers. Sebaceous and sweat glands also contain cells expressing K51 gene. K51 expression was found in the cells of eight individual basal cell carcinomas tested, with the level of expression lower than in keratinocytes from normal human epidermis. We propose that K51 gene expression could serve as a convenient marker for the study of the process of skin keratinocyte development and the changes in this process associated with skin cancers and dysplasia.