Expression Pattern of Gap Junction Protein, Connexin 26 and 43 in Human Middle Ear Cholesteatomas

Abstract

Background and Objectives: A human cholesteatoma in the middle ear is characterized by the presence of a keratinizing epithelium from hyperproliferative properties. It needs intercellular signal exchange through gap junctions as well as intracellular signal pathway for hyperproliferation. Connexin (Cx) is a gap junction protein for intercellular communication, and especially Cx26 and Cx43 are plenty in human epithelial cells. The objective of this study was to analyze the expression pattern of Cx43 and Cx26 in human middle ear cholesteatomas against normal epitheliums.

Subjects and Method: Ten retroauricular skins (RAS), ear canal skins (ECS), and cholesteatomas were taken during middle ear operations at the Department of Otolaryngology. Immunohistochemical staining, reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting were used to detect Cx43 and Cx26.

Results: In human cholesteatomas, Cx43 were expressed in the whole suprabasal layers, especially in the middle portion, except in the basal layer, and Cx26 were usually expressed in the supra layer and in the basal layers. But normal RASs showed weak expression of Cx43 in the upper spinosal and granular layers, but not in the basal layers, and the restricted localization of Cx26 in the basal layer. The expression of Cx43 and Cx26 in EASs was weak but showed similar patterns to that of cholesteatomas. In RT-PCR and Western blot, the expression of Cx43 and Cx26 were increased in cholesteatomas than in RASs.

Conclusion: Human middle ear cholesteatomas showed upregulated expression and different localization of Cx43 and Cx26, gap junction proteins for intercellular communication, compared with normal RASs, suggesting that perturbations of intercellular communication through gap junctions may be associated with the pathology of human middle ear cholesteatomas.