Expression and significance of PTEN and HIF-1α proteins in sinonasal inverted papilloma

Abstract

To investigate the expression and clinical significance of phosphatase and tensin homology deleted on chromosome ten (PTEN) and hypoxia-inducible factor 1 alpha (HIF-1α) in sinonasal inverted papilloma (SNIP) of different pathological grades. Fifty-five paraffin samples from patients with SNIP and a control group of 10 paraffin samples of patients with normal nasal cavity mucosa (NM) who underwent inferior turbinectomy were consisted in this study. Among the 55 cases of SNIP, 30 cases were without dysplasia subtypes, 11 cases were with dysplasia subtypes, and 14 cases with canceration to squamous cell carcinoma (SCC) subtypes. PTEN and HIF-1α expression in SNIP was detected by immunohistochemistry. The differences between NM and SNIP, and among the three subtypes were analyzed, and the relationship between PTEN, HIF-1α expression and SNIP recurrence and the correlation between PTEN expression and HIF-1α expression were also analyzed. SPSS 16.0 software was used to analyze the data. The positive expression rate of PTEN in NM and SNIP was 100% and 65.5%, the difference was significant (U = 147, P = 0.014), while HIF-1α was 0 and 30.9%, the difference was significant (U = 190, P = 0.045). The positive expression rate of PTEN in SNIP without dysplasia, SNIP with dysplasia and NSCC was 83.3%, 63.6%, 28.6%, respectively, the difference was significant (H = 12.644, P = 0.002); while HIF-1α was 16.7%, 45.5%, 50.0%, respectively, the difference was significant (H = 8.292, P = 0.016). A total of 22 SNIP patients recurred. PTEN had lower expression in recurrent SNIP (45.5%) than that in non-recurrent SNIP (82.8%), and the difference was significant(χ² = 7.834, P = 0.005). However, the expression of HIF-1α had no significant difference between recurrent SNIP and the SNIP which had no recurrence (χ² = 0.901, P = 0.343). The expression of PTEN protein was negatively correlated with that of HIF-1α protein (r = -0.503, P = 0.001). PTEN expression decreased graduately with the severity of malignancy of SNIP, but HIF-1α increased. The expression of HIF-1α was induced by hypoxia, which may negatively effect the expression of PTEN, and both HIF-1α and PTEN may play critical roles in the progress of SNIP. PTEN is one of the factors responsible for the postoperative recurrence of SNIP.