Cholesteatoma epithelium is characterized by increased expression of Ki-67, p53 and p21, with minimal apoptosis.

ABSTRACT

OBJECTIVE: To investigate differences in cell proliferation, cell cycle arrest and apoptosis between cholesteatoma and control skin. MATERIAL AND METHODS: Immunohistochemical sections of 15 cholesteatoma and 15 paired control retro-auricular skin samples were examined for Ki-67, p53, p21 and active caspase 3, using image analysis, as well as for DNA fragmentation. RESULTS: The retro-auricular skin samples contained 5.7% +/- 3.6%, Ki-67-positive cells and showed a normal expression pattern. In the cholesteatoma epithelium 11.7% +/- 9.5% of the cells were Ki-67-positive and these cells were dominantly expressed in the basal and parabasal cell layers. Retro-auricular skin contained 5.8% +/- 5.4% p53-positive cells and 1.0% +/- 0.9%, p21-positive cells. In the cholesteatoma epithelium 17.8% +/- 12.3% of the cells were p53-positive and 14.3% +/- 11.6% were p21-positive The expression of Ki-67, p53 and p21 differed significantly between the two groups (p < 0.05). In the cholesteatoma epithelium a positive correlation was found between p53 and p21 expression (p = 0.016). Active caspase 3 positivity and DNA fragmentation were rarely seen in the cholesteatoma epithelium. CONCLUSION: Our results indicate that increased cell proliferation in cholesteatoma epithelium is accompanied by an increase in p53 and p21 protein levels, whilst apoptosis is minimal.