Inflammation and apoptosis in malignant transformation of sinonasal inverted papilloma: the role of the bridge molecules, cyclooxygenase-2, and nuclear factor κB.

PURPOSE: This study examined the early events in the neoplastic progression of the sinonasal inverted papilloma to squamous cell carcinoma from the viewpoint of chronic inflammation and apoptosis. MATERIALS AND METHODS: In total, 118 archival slides stained with hematoxylin and eosin from 45 patients were graded according to histopathology (grades I-IV). Their representative portions were transferred to a tissue microarray, sections of which were stained immunohistochemically for cyclooxygenase-2, p53, bax, bcl-2, and nuclear factor κB. RESULTS: Cyclooxygenase-2 expression was positively correlated with histopathologic grade, with higher expression in advanced grades. p53s were detected in all cores from advanced grades (III, IV), but not in early grades (I, II). The expressions of nuclear factor κB, bax, and bcl-2 were not correlated with the grade. CONCLUSIONS: A p53 mutation seems be a critical event for the malignant transformation of the sinonasal inverted papilloma. Cyclooxygenase-2-mediated inflammatory signals, activated as a consequence of the p53 mutation, may contribute to promoting the proliferation of the advanced sinonasal inverted papilloma.