Cell proliferation, apoptosis, and apoptosis inhibition in malignant transformation of sinonasal inverted papilloma.

Conclusion. Increasing cell proliferation seems to be a very important factor in the development of inverted papilloma (IP). Apoptosis that was increased but weakly inhibited by Bcl-2 did not cause imbalance in the cell proliferation. Further increased cell proliferation in IP with dysplasia was an important mechanism of growth in dysplastic areas. Objectives. The purpose of this study was to compare cell proliferation, apoptosis, and apoptosis inhibition by Bcl-2 in IP. Patients and methods. Cell proliferation and apoptosis inhibition were detected by immunohistochemical staining with monoclonal antibodies to Ki-67 and Bcl-2. Apoptosis was detected by the transferase-mediated dUTP nick end-labeling (TUNEL) method. Results. As regards the Ki-67 index (KI), a significant increase was observed in IP with severe dysplasia, IP with carcinoma and invasive squamous cell carcinoma (SCC) compared with EP and IP with mild and moderate dysplasia. For the apoptosis index (AI), a significant increase was observed in IP with mild and moderate dysplasia compared with IP with carcinoma, invasive SCC and EP. For the Bcl-2 index (BI), a significant increase in expression was observed in IP with severe dysplasia and carcinoma and invasive SCC compared with control, EP and IP with mild dysplasia. Among IP, the KI (average 18.2%) was much higher than the AI (6.4%) and BI (4.1%). [ABSTRACT FROM AUTHOR]