Objective: To investigate the expression of nucleolar spindle associated protein 1 (Nusap1) in cholangiocarcinoma tissue and its clinical significance.    
Methods: The expressions of Nusap1 mRNA in cholangiocarcinoma and normal bile duct tissue were analyzed by using the GEPIA database tool. The expression levels of Nusap1 protein in 61 paired specimens of cholangiocarcinoma and adjacent tissue were determined by immunohistochemical technique, and the relations of Nusap1 protein expression with clinical parameters and the total survival time of the patients were analyzed. 
Results: The GEPIA database analysis showed that the Nusap1 mRNA was highly expressed in cholangiocarcinoma tissue compared to that in normal bile duct tissue (P<0.05). The results of immunohistochemical staining showed that the expression level of Nusap1 protein was significantly higher than that in the tumor adjacent tissue (47.5% vs. 14.8%, P<0.05). Moreover, the Nusap1 protein expression was significantly associated with the TNM stage (P=0.001), lymph node metastasis (P=0.011), and survival status (P=0.010). Kaplan-Meier analysis showed that the median survival time of patients with positive Nusap1 expression was 23 months and in those with negative Nusap1 expression was 45 months, and the postoperative survival time of the former was significantly shorter than that of the latter (P=0.000). 
Conclusion: Nusap1 expression is increased in cholangiocarcinoma tissue, and it may be closely related to the progression and poor prognosis of cholangiocarcinoma. Nusap1 may potentially become an indicator of prognosis and treatment target for cholangiocarcinoma.