Heparin-binding epidermal growth factor (EGF)-like growth factor is a 22-kDa glycoprotein that was originally identified as a secreted product of cultured human macrophages. Although the growth factor mRNA has been identified in various cells and tissues, the tissue distribution of the protein itself has rarely been demonstrated. In this study, the EGF-like growth factor was detected immunohistochemically in a variety of human skin samples by indirect immunofluorescence using a polyclonal rabbit antiserum raised against residues 26-41 of mature heparin-binding EGF. The keratinocytes of a variety of epithelium-derived structures demonstrated reproducible, specific staining for the EGF. In normal tissues, this staining was prominent in the basal cells of the epidermis and in the epithelial cells lining epidermal appendages such as hair follicles, sebaceous sweat glands and eccrine sweat glands. In addition, specific staining was detected in skin cancers derived from the basal epithelial cell layer, including basal and squamous cell carcinomas of the skin, with no staining detected in melanoma specimens. Immunoreactive heparin-binding EGF was characteristically associated with the surface of cells. With minor exceptions, the immunoreactive sites are identical to the known EGF receptor distribution in the skin, and suggest that keratinocyte-derived heparin-binding EGF may act in concert with other EGF family members in processes such as skin morphogenesis and wound repair, as well as in the development of skin cancers.
Bibliographical noteFunding Information:
The authors thank Ken Brown, (Babraham Institute, Cambridge, UK) for kindly providing the anti-HB-EGF[26–41] antibody that was used for immunohis- tochemistry in these experiments, and Cindy McAll-ister, (Wexner Institute, Columbus, OH, USA) for assistance with confocal microscopy. GEB and DRB were supported by the Children's Hospital Research Foundation (020-871 and 020-872). GEB was also supported by NIH no. GM50905, an American College of Surgeons Faculty Fellowship Award, The Ohio State University Department of Surgery
Human HB-EGF was recombinantly produced in Escherichia coli, as described previously (Besner et al., 1992), purified and sequenced to verify identity and homogeneity. Recombinant human EGF was from Upstate Biotechnology (Lake Placid, NY, USA), recombinant human TGF-á was from Collaborative Biomedical Products (Bedford, MA, USA) and recombinant human amphiregulin (AR) was from R&D Systems (Minneapolis, MN, USA). 5-bromo-4-chloro-3-indolyl-phosphate (BCIP), Nitroblue Ter-azolium (NBT) and human-preabsorbed goat anti-rabbit IgG (H ‡ L)-alkaline phosphatase conjugate were from Gibco BRL (Grand Island, NY, USA). Cryomolds and OCT embedding medium were from Miles Tissue-Tek (Elkhart, IN, USA). 2-Methylbutane and Superfrost Plus microscope slides were from Fisher Scientific (Pittsburgh, PA, USA). Normal goat serum, biotinylated goat anti-rabbit IgG and fluorescein avidin different cell sorting (DCS) were from Vector Laboratories, (Burlingame, CA, USA). Rabbit IgG was from Cappel Research Products (Durham, NC, USA). Human tissues, including skin from various areas of the body, were from excised operative or autopsy specimens obtained in compliance with regulations of the Human Subjects Committee of Children's Hospital, Columbus, OH, USA. Some tissue samples were obtained from the Cooperative Human Tissue Network, which is funded by the National Cancer Institute.