Background: Numerous molecular markers of sinonasal inverted papillomas (IP) were investigated in the past; however, significance of angiogenesis and inhibition of apoptosis were not well documented. This study was designed to determine expression of angiogenic marker CD34 antigen, antiapoptotic marker Bcl-2 oncoprotein, and proliferative marker Ki-67 antigen in the group of patients with IP. We matched up these findings to the group of patients with sinonasal carcinoma (SNC) and used chronic rhinosinusitis (CRS) patients as control group. In addition, we compared expression of the markers among IP patients who displayed distinctly different patterns of clinical behavior.
Methods: Tissue samples were obtained from 46 surgically treated patients; 18 of them had a diagnosis of IP, 9 had documented SNC, and the remaining 19 patients had CRS. All specimens were stained using immunohistochemistry techniques for CD34 (mean vessel density [MVD]), Bcl-2, and Ki-67 antigens. Morphometry was evaluated by computer image analysis system.
Results: We noted statistically significant differences in expression of CD34 antigen, Bcl-2 protein, and Ki-67 antigen (for all groups, ANOVA p < 0.001) among the investigated groups. The mean value of CD34 antigen was significantly higher in the IP group than in the CRS group, but it was below the levels of the SNC group. Compared with the cases not complicated by recurrence, the patients with recurrent IP exhibited higher MVD levels, while levels of bcl-2 and Ki67 protein expression did not differ in a significant way between recurrent and nonrecurrent cases. The significant positive correlations were observed between Bcl-2 protein and Ki-67 antigen in IP and SNC groups and between Bcl-2 protein and CD34 antigen in the CRS group.
Conclusion: Our findings underscore importance of angiogenesis in the development and prognosis of IP and support further investigation of this aspect of IP tumor growth.