Altered basic fibroblast growth factor expression in common epidermal neoplasms: Examination with in situ hybridization and immunohistochemistry

Background: The fibroblast growth factor family consists of acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), and Kaposi fibroblast growth factor (kFGF). The distribution of these growth factors in skin disease has not been determined. Objective: The purpose of this study was to determine the distribution of these growth factors in keratinocytic lesions and normal skin. Methods: Skin sections from common disorders of keratinocytes were examined by in situ hybridization with specific probes for aFGF, bFGF, and kFGF, and immunohistochemistry. Results: Of the growth factors studied, only bFGF was present in skin. bFGF messenger RNA was highly expressed in both normal epidermis and benign and malignant epithelial neoplasms. In normal skin, bFGF was expressed predominantly in a suprabasal fashion, whereas in epithelial neoplasms, homogeneous high level expression of bFGF was observed. Conclusion: bFGF is the primary member of the fibroblast growth factor expressed in the skin. The source of synthesis of bFGF is keratinocytes. Immunoreactivity for bFGF appears to be primarily confined to upper layers of the epidermis in normal skin, but is expressed at all layers of the epidermis in both benign and malignant neoplastic conditions. Genetic changes that promote epithelial tumors may also promote translation of bFGF messenger RNA into protein. Specific inhibition of bFGF activity may have application in the treatment of common skin diseases.