Expression of PTEN and phosphorylated Akt in human cholesteatoma epithelium.
CONCLUSIONS
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.


OBJECTIVE
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.


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).
Yune
Tae Young
TY
Age-Related and Brain Diseases Research Center, College of Medicine, Kyung Hee University, GandongGu, Seoul, Korea.
Byun
Jae Yong
JY
D015153:Blotting, Western; D018424:Cholesteatoma, Middle Ear / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D007150:Immunohistochemistry; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012867:Skin / Q000378:metabolism
D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human