Conclusion: We found a reduced PTEN and an increased phosphorylated Akt (p-Akt) expression in cholesteatoma epithelium when compared with retro-auricular (RA) skin. The negative correlation between cholesteatoma PTEN and p-Akt may suggest that cellular survival mechanisms may be involved in cholesteatoma epithelial hyperplasia.
Objectives: The tumor suppressor PTEN regulates the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway and modulates cell cycle progression and cell survival. We hypothesized that PTEN might be involved in this pathway mechanism in cholesteatoma.
Materials and methods: Western blotting and immunohistochemistry were used to examine the expression of PTEN and p-Akt in 16 cases of cholesteatoma and paired cases of RA skin.
Results: In cholesteatoma, p-Akt expression was significantly higher than in RA skin, whereas PTEN expression was significantly lower in cholesteatoma when compared with skin (p < 0.05). Immunohistochemical analysis showed that weak PTEN immunoreactivity was observed in the nuclei of cholesteatoma epithelium, whereas strong PTEN immunoreactivity was detected in the nuclei of skin. Also, strong p-Akt immunoreactivity was observed in the cytoplasm of cholesteatoma epithelium, whereas very weak or no p-Akt immunoreactivity was observed in the RA skin. Furthermore, we found that a significant inverse correlation exists between PTEN and p-Akt expression (r = -0.796).