AB147. Wild-type p53-induced phosphatase 1 is a prognostic marker and therapeutic target in bladder transitional cell carcinoma

OBJECTIVE: Wild-type p53-induced phosphatase (Wip1) is known as an oncogene and is associated with development of various types of human cancers. However, the expression and role of Wip1 in human bladder transitional cell carcinoma (TCC) remains unclear. METHODS: The expression of Wip1 in bladder cancer patients was determined using immunohistochemistry. Bladder cancer T24 was transfected with Wip1-siRNA or negative control siRNA. Cell proliferation, invasion and migration and were determined using MTT assay, transwell assay, respectively. RESULTS: In this study, immunohistochemistry evaluation found that Wip1 was overexpressed in bladder TCC tissues compared with corresponding normal bladder tissues in 106 bladder TCC patients (P<0.0001). Moreover, high expression of Wip1 was significantly associated with increasing tumor size (P=0.002), pathological grade (P=0.025), clinical T stage (P=0.001) and lymph nodal metastasis (P=0.003). The Kaplan-Meier survival analysis revealed that patients with high Wip1 expression showed a lower overall survival time (P<0.0001), and the Cox proportional hazards regression model demonstrated that Wip1 expression was an independent prognostic factor in bladder TCC patients (P=0.025). In addition, downregulation of Wip1 by transfected with small interfering RNA (siRNA) in bladder cancer cells inhibited cell proliferation, invasion and migration (P<0.05), along with the upregulation of p53 protein levels (P<0.05). CONCLUSIONS: Our findings suggest that Wip1 may act as a potential prognostic marker and therapeutic target of bladder cancer.