Altered expression of E-cadherin and β-catenin in malignant transformation of sinonasal inverted papillomas.

BACKGROUND: E-cadherin and β-catenin are molecules that mediate cell-cell adhesion in normal epithelium. Aberrant expression of these adhesion molecules results in the loss of intercellular adhesion, with possible cell transformation and tumour progression. We determined the role of E-cadherin and β-catenin in the pathogenesis of sinonasal inverted papilloma (IP) and its malignant transformation. METHODS: We determined the expression of E-cadherin and β-catenin by immunohistochemistry in paraffin-embedded tissue of 21 subjects with nasal polyps, 56 with IPs, 7 IPs with dysplasia and 18 IPs with squamous cell carcinoma (SCC). The clinicopathological variables of the IPs with SCC correlated with the degree of expression of E-cadherin and β-catenin. RESULTS: The degree of expression of E-cadherin and β-catenin in the cell membrane was significantly lower in IPs with SCC than in nasal polyps and IPs. The degree of expression of β-catenin was significantly lower in IPs with SCC with a malignant proportion > 50% compared to a malignant proportion ≤ 50%. However, there was no significant association between the degree of expression of E-cadherin and β-catenin and clinicopathological variables, such as age, gender, T stage, tumour differentiation, or SCC type (metachronous vs. synchronous). In addition, there was no significant relationship between recurrence or survival rate in IPs with SCC and the degree of expression of E-cadherin or β-catenin in the cell membrane or nuclear β-catenin. CONCLUSION: Decreased expression of E-cadherin and β-catenin in the cell membrane may be associated with carcinogenesis of IPs and help predict malignant transformation in sinonasal IPs.