Expression Of Emp1in Sinonasal Inverted Papilloma And Its Relationship With Metaplasia

Backgrounds and ObjectivesSinonasal inverted papilloma(SNIP) is one of primary sinonasal tumors and its major pathological changes are severe remodelling and metaplasia of nasal epithelium, showing an increase of epithelial hyperplasia with variable transitional and stratified squamous cells. Although not a common lesion of the sinonasal tract, it is clinically challenging due to the tendency for recurrence and the potential for malignant transformation. Epithelial membrane protein1(EMP1) is found to regulate epithelial cell proliferation and differentiation, andits down-regulation is reported in various squamous cell carcinomas. The aim of this study was to investigate if EMP1plays an important role in the pathogenesis of sinonasal inverted papilloma (SNIP).MethodsTwenty-five patients with SNIP and fifteen controls of healthy subjects were recruited from the Departments of Otolaryngology in the Qilu Hospital of Shandong University. All SNIP patients were diagnosed based on clinical symptoms and histo-pathologic examination. Papillomas were obtained from patients who underwent endoscopic sinus surgery. Inferior turbinate (IT) tissues were obtained from the subjects with septal deviationand served as controls. None of the controls had chronic rhinosinusitis with and without nasal polyps (NP) nor had allergic rhinitis(AR). Fresh specimens were divided into two sections; one was preserved with RNA later for gene expression profiling, another was fixed in formalin for histological evaluation.ResultsA moderate epithelial metaplasia (12/25,48%) showing irregular stratification with the increase of transitional/squamous cells was the most common epithelial alteration occurred in the SNIP tissues. EMP1staining was observed in all layers of the epithelial cells in healthy controls; whilst it was found only in the basal layer and ciliated cells (in mild metaplasia) in SNIP epithelium. Both EMP1protein and mRNA levels were significantly decreased (3.0-fold and2.6-fold, respectively), compared to the controls. Moreover, EMP1expression level was significantly inversely-correlated with the severity of epithelial metaplasia in SNIPs.ConclusionsDown-regulation of EMP1is associated with severe level of epithelial metaplasia in SNIP epithelium, and it could be a biomarker for evaluating aberrant epithelial remodeling in SNIP epithelium.