Expression of c-erbB receptors and ligands in human nasal epithelium

Background: The epidermal growth fatter (EGF) family of growth factors play s an important role in maintenance and repair in a variety of epithelial ti ssues. However, very little is known about coexpression of these factors an d their receptors, the c-erbB family of receptor tyrosine kinases, in human nasal epithelium. Objective: we sought to investigate the expression of these molecules in cu ltured nasal epithelial cells and nasal mucosa from healthy individuals. Methods: Identification of c-erbB receptors and their ligands was sought by using reverse transcription PCR, Western blotting, and immunohistochemistr y. Results: Messenger RNA encoding the EGF receptors (EGFR) c-erbB2 and c-erbB 3, but not c-erbB4, was detected in primary cultures of human nasal epithel ial cells. Transcripts encoding EGF, heparin-binding EGF, transforming grow th factor (TGF) alpha, and amphiregulin were also detected. Receptor and li gand expression was confirmed by using immunocytochemical staining of the c ells and Western blotting of the cell lysates, Immunohistochemical analysis of tissue sections obtained from biopsy specimens of nasal mucosa revealed intense membrane staining for the EGFR within the respiratory nasal epithe lium, which was predominantly localized at the level of the columnar epithe lial layers. Similar staining patterns were observed for c-erbB2 and c-erbB 3 in the respiratory nasal epithelium. Evidence for EGF, transforming growt h factor alpha, heparin-binding EGF, amphiregulin, and betacellulin immunos taining in the nasal epithelium nas also obtained; their staining patterns paralleled that of EGFR immunostaining. Conclusion: Colocalization of c-erbB receptors and ligands establishes a ba sis on which to investigate c-erbB receptor-mediated effects in human nasal epithelium.