Background: Nucleostemin (NS) has been reported essential for maintenance of normal and cancer stem cell properties. However, the impacts of NS on malignant phenotype of OSCC and prognosis of patients with OSCC have not been clarified. The purpose of this study is to explore the impacts of NS in malignant phenotype and prognosis of OSCC.

Methods: We established NS-over-expression OSCC cell lines by using reporter system where the NS promoter drives GFP expression. Knock-down experiment was performed with small interfering RNA. The alterations of cell properties were analyzed using Cell proliferation assay and Matrigel invasion assay. Real time RT-PCR and Western blotting were used for expression analysis. An immunohistochemical analysis of NS was performed in 54 OSCC patients who were treated with preoperative chemoradiotherapy and surgery.

Results: Overexpression of NS increased malignant phenotypes of OSCC cells. On the other hand, down-regulation of NS by siRNA showed inverse phenominan. The immunohistochemical analysis demonstrated a high NS tumour expression to significantly correlate with the advanced tumour classification, nodal status, and poor prognosis in OSCC patients.

Conclusion: These findings suggest that NS may play an important role in malignant phenotype. Moreover, overexpression of NS may potentially affect prognosis in OSCC patients.