Overexpression of osteopontin promotes cell proliferation and migration in human nasopharyngeal carcinoma and is associated with poor prognosis

Nasopharyngeal carcinoma (NPC), a malignant tumor at the top and side of the nasopharyngeal cavity, highly occurs in the southern region of China. Cancer cell metastasis is one of the leading causes of death in NPC patients. Osteopontin (OPN), is a phosphorylated extracellular matrix protein with a variety of functions, was found to be overexpressed in many cancers. However, the expression and role of OPN in patients with NPC in Guangxi, China are unclear. Here, we observed that NPC patients had upregulated OPN at mRNA protein and levels. Immunochemistry (IHC) analysis of OPN expression in 68 NPC clinical specimens indicated that high expression of OPN had positive correlation with NPC lymph node metastasis (P = 0.012), distant metastasis (P = 0.001) and TNM staging (P = 0.018). Moreover, compared with relatively low OPN, NPC patients with higher expression of OPN showed a poorer overall survival rate (P = 0.001, log rank test). Multivariate analysis showed that OPN expression in NPC was an independent prognostic marker. The proliferation, apoptosis and migration ability of CEN-2Z cancer cells in NPC were determined by MTT, flow cytometry and wound-healing assays, respectively. Upregulation of OPN in CEN-2Z cancer cells promoted cancer cell proliferation and migration, and suppressed apoptosis. In sum, our result suggests OPN could be used as a valuable oncoprotein and show that overexpression of OPN in NPC may serve as a potential prognostic marker.