SOX-2, but not Oct4, is highly expressed in early-stage endometrial adenocarcinoma and is related to tumour grading

Background: Expression of SOX-2 and Oct4 as markers for the identification of cancer stem cells (CSCs) has been revealed in several malignancies. In this study, the co-expression of SOX-2 and Oct4 and their correlation with clinicopathological features of endometrial adenocarcinomas (EACs) was investigated. Methods: SOX-2 and Oct4 expression was assessed by immunohistochemistry in 27 (39.13%) stage IA and in 42 (60.87%) stage IB International Federation of Gynaecology and Obstetrics (FIGO) EACs and related to the clinicopathological features of patients. Results: The expression of SOX-2 was confirmed in 62/69 tumour specimens compared to Oct4 expression in 46/69 specimens (P = 0.015) and no difference in median staining intensity between SOX-2 and Oct-4 was observed. The highest median SOX-2 expression was found in high-grade (G3) EAC samples compared to moderate-grade (G2) EAC specimens (P = 0.020) and low-grade (G1) specimens (P = 0.008), while no differences in median Oct4 expression in EAC samples according to grading were present. In G3 specimens, significantly higher median SOX-2 expression was noted compared to Oct4 (P = 0.002). SOX-2 and Oct4 co-expression was observed only in G1 EAC (R: 0.51; P = 0.031). Age of EAC diagnosis was positively correlated with SOX-2 expression (b = 0.193; R² = 10.83%; P = 0.003) but not to age of menarche, menopause, parity or body mass index. Conclusions: There is no need to use SOX-2 expression as a poor outcome predictor in stage I EAC, and SOX-2 expression should be analysed in more advanced stages.