conservation of Mucous Epithelial Characteristics in the Human Middle Ear Epithelial Cell Line

Abstract

BACKGROUND AND OBJECTIVES: The stable cell line system of middle ear epithelial cells is essential for studying molecular pathogenesis of otitis media. Recently, we succeeded in establishing the human middle ear epithelial cell line (HMEEC) using a retrovirus. The cell line retains many of the phenotypic and morphological properties of the non-transformed, parental cultures such as the expression of cytokeratin and tight junctions. We aimed to show the conservation of mucosal characteristics and subcellular mechanisms of transcriptional regulation in this cell line. MATERIALS AND METHOD: RT-PCR was performed using mucin gene specific primers and total RNA extracted from HMEEC. The luciferase-expressing vector containing 5' flanking region of human beta defensin 2 (hBD-2), an inducible antimicrobial peptide, was transfected to HMEEC. After starvation of serum, HMEEC was treated with interleukin 1 alpha (IL-1alpha) and subsequently harvested 10 hrs later. Luciferase activity was measured using luminometer after the corresponding substrate was supplemented to the cell lysate. RESULTS: Expression of mucin genes (MUC1, 2 and 5B) in HMEEC was demonstrated by RT-PCR. Luciferase assay showed that IL-1alpha up-regulates the promoter activity of hBD-2 more than 10 fold. This transcriptional regulatory mechanism was also demonstrated in the well established reference cell lines, HeLa cells and A549 cells. CONCLUSION: We demonstrated the conservation of mucin gene expression and transcriptional regulatory mechanism of hBD-2 in HMEEC. The proposed cell line can serve as a useful experimental model for elucidating the pathogenesis of middle ear mucosa-related diseases.