Expression of PTHrP and RANKL in acquired middle ear cholesteatoma epithelium.

Regarded as the most important clinical characteristic of middle ear cholesteatoma, the exact mechanism of bone resorption in cholesteatoma still remains unknown. To investigate protein expression of PTHrP and RANKL in acquired middle ear cholesteatoma epithelium and analyze their functional roles in the etiopathogenesis of bone resorption in middle ear cholesteatoma. A total of 22 patients who underwent surgical treatment for middle ear cholesteatoma were recruited in the study. Protein expression of PTHrP and RANKL in middle ear cholesteatoma and normal postauricular skin was investigated by immunohistochemical staining. Correlations between bone resorption degree and expression of PTHrP and RANKL were also analyzed. Protein expression of PTHrP and RANKL in cholesteatoma epithelium significantly increased when compared with normal postauricular skin epithelium. In cholesteatoma epithelium, a significantly positive association was observed between PTHrP and RANKL expression. Meanwhile, obviously positive correlations between protein expression of PTHrP and RANKL and bone resorption degree were discovered. The increased protein expression of PTHrP and RANKL in cholesteatoma epithelium, and their associations with the degree of bone resorption, revealing that PTHrP might promote bone resorption process in middle ear cholesteatoma through RANKL signaling pathway.