Expression pattern of IQGAP1 in sinonasal inverted papillomas and squamous cell carcinomas

Abstract

The scaffold protein IQGAP1 is a ubiquitously expressed 190 kDa protein that participates in protein-protein interactions, integrating diverse signaling pathways. In this study, we examined the expression of IQGAP1 in sinonasal inverted papillomas (IP) and sinonasal squamous cell carcinomas (SCC), which include IP with SCC (IPcSCC) and SCC alone. We also tried to elucidate whether the amount of IQGAP1 expression is related with any clinicopathologic features of sinonasal SCCs. This was a retrospective study. The expression of IQGAP1 was analyzed by means of immunohistochemistry. The degrees of IQGAP1 expression and subcellular localization (rim formation) were analyzed with respect to the following clinicopathologic variables: age, gender, T stage, histologic differentiation, local recurrence, and distant metastasis. The expression of IQGAP1 was significantly higher in patients with IPcSCC (3.62 ± 0.14), and SCC (2.93 ± 0.34) compared with IP (1.43 ± 0.26). The rim formation scale was significantly higher in IPcSCC (2.39 ± 0.24) compared with IP (1.68 ± 0.15). Distant metastasis in patients with SCC significantly correlated with an increased IQGAP1 rim formation (p = 0.011). Histologic differentiation was also significantly correlated with a positive staining scale for IQGAP1 in IPcSCCs (p = 0.038). These results indicated that IQGAP1 expression is associated with both the histologic differentiation of IPcSCCs and is present in SCC cases where distant metastasis has occurred.