IMMUNOLOCALIZATION OF LOW-MOLECULAR-WEIGHT STRESS PROTEIN HSP-27 IN NORMAL SKIN AND COMMON CUTANEOUS LESIONS

Stress proteins, which are found ubiquitously in mammalian cells, appe ar to be implicated in the regulation of cell growth and protection fr om environmental insult. Although we previously demonstrated the expre ssion of low-molecular-weight stress protein, HSP 27, in cultured kera tinocytes, HSP 27 has not yet been identified in human skin. Using sta ndard immunohistochemistry on routinely processed paraffin sections, w e examined specimens of common epidermal lesions and normal skin with a monoclonal antibody to HSP 27. Normal skin from the breast, foreskin , and lower extremity demonstrated strong cytoplasmic staining in the suprabasal epidermis. There was no change in the intensity of staining or cellular localization related to age, body location, or gender. Se ctions of actinic keratosis, superficial basal cell carcinoma, seborrh eic keratosis, and psoriasis also exhibited strong cytoplasmic stainin g in the suprabasal layers of the epidermis. In contrast, cutaneous sq uamous cell carcinoma demonstrated only weak cytoplasmic staining thro ughout the infiltrating tumor. This is of particular interest, since o ther investigators have reported a loss of HSP 27 expression in oncoge nically transformed cells that exhibit a tumorigenic phenotype. To our knowledge, this study provides the first demonstration of HSP 27 expr ession in human skin.