Correlation of ALDH1, CD44, OCT4 and SOX2 in tongue squamous cell carcinoma and their association with disease progression and prognosis

BACKGROUND: Recently, studies indicated that cancer stem cell plays a key role in cancer development and progression. However, the role of cancer stem cell has not been well elucidated in tongue squamous cell carcinoma (TSCC). The objective of this study was to investigate the relationships between the expressions of stem cell markers and the prognosis of TSCC. MATERIALS AND METHODS: Immunohistochemistry was employed to analyse the protein expression levels of ALDH1, CD44, OCT4 and SOX2 in 66 TSCC tissue samples. The results were then evaluated semiquantitatively and compared with other clinicopathological variables. RESULTS: Immunohistochemistry revealed that the ALDH1, CD44, OCT4 and SOX2 proteins were overexpressed in the 66 TSCC specimens used in this study. Spearman's correlation analysis showed that the expressions of ALDH1 and CD44 were significantly correlated with SOX2 except other proteins (P < 0.05) and that OCT4 and SOX2 were significantly related (P < 0.01). Kaplan-Meier analysis revealed that T category, node metastasis, TNM stage, differentiation and distant metastasis were associated with poor patient survival (P < 0.05). Multivariate Cox regression analysis demonstrated that SOX2, recurrence and distant metastasis were independent prognostic factors of overall survival in patients with TSCC. CONCLUSION: Taken together, these data suggest that the stem cell markers ALDH1, CD44, OCT4 and SOX2 are closely related in TSCC, and the expression of SOX2 can be used as a prognostic indicator of TSCC.