Down-regulation of gelsolin may play a role in the progression of inverted papilloma through an antiapoptotic mechanism

Background: Gelsolin is an actin-binding protein with multiple cellular functions including apoptosis and is reported to be down-regulated in various cancers and premalignant lesions. The objective of this study was to identify gelsolin and caspase-3 expression in inverted papilloma (IP) and investigate the role of gelsolin in the progression of IP related to apoptosis. Methods: Specimens from 30 patients with nondysplastic IP were retrieved. The percentage of surface epithelium covered with squamous metaplastic epithelium was assessed. Immunohistochemically demonstrated gelsolin and caspase-3 expression were compared between IP and adjacent control mucosa. We analyzed the correlations among gelsolin expression, caspase-3 expression, and the degree of squamous metaplasia in IP. Results: The degree of squamous metaplasia of surface epithelium was inversely correlated with gelsolin (r=-0.610; p < 0.001) and caspase-3 expression (r = -0.433; p = 0.017). Gelsolin expression in IP was significantly lower than that in the control when >50% of surface epithelium showed squamous metaplasia (p = 0.015). Caspase-3 also showed diminished expression when >50% of surface epithelium had undergone squamous metaplasia (p = 0.035). Gelsolin and caspase-3 expression showed no significant differences when the degree of squamous metaplasia was >50%. Gelsolin and caspase-3 expression levels in IP had a positive relationship (r = 0.557; p = 0.001). Conclusion: Progression of IP may be related to an insidious decrease in caspase-3-mediated apoptosis, and down-regulated gelsolin expression may be correlated with the decrease in apoptosis, especially in more highly progressed IP in which >50% of surface epithelium has undergone squamous metaplasia.