Over-expression of protein tyrosine phosphatase 4A2 correlates with tumor progression and poor prognosis in nasopharyngeal carcinoma

// Ying Gao 1, 2, * , Mengping Zhang 1, * , Zhousan Zheng 1, * , Ying He 1, 2, * , Yujia Zhu 3 , Quanyong Cheng 4 , Jian Rong 5 , Huiwen Weng 1 , Cui Chen 1 , Yi Xu 1 , Miao Yun 2, 6 , Jiaxing Zhang 1, 2 and Sheng Ye 1 1 Department of Oncology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, PR China 2 Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, PR China 3 Departments of Radiation Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, PR China 4 Department of Private Surgery Medical Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, PR China 5 Department of Extracorporeal Circulation, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, PR China 6 Department of Ultrasound, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, PR China * These authors have contributed equally to this work Correspondence to: Sheng Ye, email: yes20111212@163.com Jiaxing Zhang, email: zjxlundy@hotmail.com Keywords: protein tyrosine phosphatase 4A2(PTP4A2), nasopharyngeal carcinoma, tumor progression, prognosis, biomarker Received: July 07, 2017      Accepted: August 04, 2017      Published: August 24, 2017 ABSTRACT Protein tyrosine phosphatase 4A2 (PTP4A2) has been implicated as an oncogenic protein in several human cancers. However, the level of PTP4A2 expression and its prognostic significance in nasopharyngeal carcinoma (NPC) remains unknown. In this study, Western blotting (WB), quantitative real-time PCR (qT-PCR) and immunohischemistry (IHC) was applied to evaluated the expression levels of PTP4A2 in NPC cell lines and tumor tissues combining two independent cohorts. Receiver-operator curve (ROC) analysis was used to assessed the optimal cut-off score in training cohort (266 cases). This cut-off score was subjected to determine the association of PTP4A2 expression with patients’ clinical characteristics and survival outcome in the validation cohort (201 cases) and the overall population (467 cases). We found that PTP4A2 were significantly overexpressed in NPC cell lines compared with normal nasopharyngeal epithelial cell. Moreover, overexpression of PTP4A2 was positively correlated with advanced T classification ( P<0.001 ) and TNM stages ( P<0.001 ). And higher PTP4A2 expression was an independent prognostic factor for adverse overall survival ( P<0.05 ) and poor disease-free survival ( P<0.05 ). Our results demonstrated that the overexpression of PTP4A2 was closely associated with poor survival outcome in patients with NPC and may represent a novel prognostic biomarker and therapeutic target for this disease.