Nucleolar spindle-associated protein 1 promotes tumorigenesis and predicts poor prognosis in human esophageal squamous cell carcinoma.

The microtubule binding protein, nucleolar spindle-associated protein 1 (NUSAP1), has a crucial function in mitosis and its expression is closely associated with carcinogenesis. Herein, we aimed to determine the function of NUSAP1 in the development of human esophageal squamous cell carcinoma (ESCC), and the association of NUSAP1 expression with ESCC. Immunohistochemical staining of ESCC tissue sections indicated that NUSAP1 was expressed to a higher degree in tumor tissues than in adjacent nontumor tissues. NUSAP1 levels were relevant closely to histological differentiation (P = 0.049). Overall survival was longer in patients with lower NUSAP1 levels ( P < 0.001). NUSAP1 expression ( P = 0.002), histological differentiation ( P < 0.001), tumor depth ( P = 0.045), lymph node metastases ( P < 0.001), and tumor-node-metastasis staging ( P = 0.008) were greatly associated with overall survival using univariate analysis. Multivariate analysis suggested that histological differentiation ( P = 0.014) and NUSAP1 expression ( P = 0.026) could be independent prognostic markers for ESCC. Additionally, the biological behavior of ESCC cells was investigated in vitro and in vivo. Suppression of NUSAP1 inhibited cellular proliferation and invasion, and induced cell cycle arrest and apoptosis in vitro. More importantly, knockdown of NUSAP1 led to inhibition of tumor formation in nude mice. These findings indicated that NUSAP1 is a potential prognostic biomarker in ESCC, and is an ESCC oncogene. Thus, NUSAP1 could represent a therapeutic target for ESCC.