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Expression of p53 protein in human middle ear cholesteatomas: pathogenetic implications
A P Albino1, J A Reed, J K Bogdany
1Department of Otolaryngology, Manhattan Eye, Ear, & Throat Hospital, New York, New York 10021, USA.
Background:
Cholesteatoma is a destructive lesion of the middle ear or mastoid process or both. The molecular and cellular defects that result in the clinical hallmarks of acquired and congenital cholesteatomas, namely invasion, migration, uncoordinated proliferation, altered differentiation, aggressiveness, and recidivism, are unknown. Determining the existence of defects in the normal biology, biochemistry, and genetic complement of the major cellular constituents comprising a cholesteatoma (i.e., fibroblasts and keratinocytes) is critical to the understanding of the pathogenesis of cholesteatomas. It has been speculated that the development of human cholesteatomas is due, in part, to the altered control of cellular proliferation, which tilts the balance toward the aggressive, invasive growth of squamous epithelium within the middle ear. However, whether this altered control is due to defects in the mechanisms and underlying genes that control proliferation, or to cytokines released from infiltrating inflammatory cells, or to some other mechanism is unknown. The nuclear phosphoprotein p53 tumor suppressor gene plays a critical regulatory role in cell cycle control and apoptosis. In the current article, the authors have analyzed congenital, primary and secondary acquired, and recurrent cholesteatomas for the altered expression of p53 and Ki-67, a marker of active proliferation.
Methods:
p53 and Ki-67 expression was determined by immunohistochemical assays using specific monoclonal antibodies.
Results:
The authors' results indicate that p53 is elevated 9- to 20-fold in all cholesteatomas when compared to the expression of p53 in normal postauricular skin or tympanic membrane. However, there is no concomitant increase in Ki-67 expression in cholesteatomas.
Conclusions:
These data indicate a defect in cholesteatomas in the mechanisms that p53 engages (i.e., cell cycle control or apoptosis or both). In addition, these data further suggest that there is no intrinsic difference between any clinicopathologic group of cholesteatomas, at least with respect to p53-expression and, presumably, p53 function.
Insights
Cholesteatoma, a destructive ear lesion, shows elevated p53 protein but not Ki-67. This suggests a defect in cell cycle control or apoptosis mechanisms, indicating abnormal p53 pathway function in cholesteatoma development.
Area of Science:
- Otolaryngology
- Molecular Biology
- Oncology
Background:
- Cholesteatoma is a destructive lesion of the middle ear and/or mastoid process.
- The underlying molecular and cellular defects driving cholesteatoma invasion, proliferation, and recurrence are not fully understood.
- The tumor suppressor gene p53 is crucial for regulating cell cycle control and apoptosis.
Purpose of the Study:
- To investigate the expression of p53 and Ki-67 in various types of cholesteatomas.
- To determine if altered p53 expression correlates with cholesteatoma aggressiveness and recurrence.
- To explore potential defects in cell cycle regulation and apoptosis in cholesteatoma pathogenesis.
Main Methods:
- Immunohistochemical assays were performed using specific monoclonal antibodies to detect p53 and Ki-67 expression.
- Expression levels were analyzed in congenital, primary acquired, secondary acquired, and recurrent cholesteatomas.
- Comparisons were made to normal postauricular skin and tympanic membrane tissue.
Main Results:
- p53 expression was significantly elevated (9- to 20-fold) in all cholesteatoma samples compared to normal tissues.
- No corresponding increase in Ki-67, a marker of active proliferation, was observed in cholesteatomas.
- These findings were consistent across all clinicopathologic groups of cholesteatomas studied.
Conclusions:
- The data indicate a defect in the p53-mediated mechanisms of cell cycle control or apoptosis in cholesteatomas.
- The results suggest that altered p53 pathway function contributes to cholesteatoma pathogenesis.
- There appear to be no significant differences in p53 expression or function among different clinical types of cholesteatomas.
