Expression of Prostaglandin E2 Receptors in Acquired Middle Ear Cholesteatoma

OBJECTIVES To investigate the expression of prostaglandin E2 receptor subtypes, E-prostanoid (EP) 1-4 receptors, in acquired cholesteatoma and its possible role in the pathologic process of this disorder. METHODS Specimens of human acquired cholesteatoma were obtained from 29 patients and 19 skin biopsies of normal external auditory canal were as controls. The mRNA and protein expression of EP receptors was assessed by quantitative real-time polymerase chain reaction, immunohistochemistry and Western blot. RESULTS In acquired cholesteatoma, EP1-EP4 receptors were mainly expressed on squamous epithelium and subepithelial infiltrated inflammatory cells. In external auditory canal skin, EP1-EP4 receptors were mainly expressed on squamous epithelium and glandular epithelium. The expression of EP4 receptor on mRNA and protein levels were significant lower in acquired cholesteatoma compared with controls. EP1-EP3 receptors had no significant difference between the experimental and control group. CONCLUSION Low expression of EP4 may play a crucial role in the pathologic process of inflammation reaction and bone destruction in acquired cholesteatoma, but not EP1, EP2, or EP3 receptors.