Fibrous sheath interacting protein 1 overexpression is associated with unfavorable prognosis in bladder cancer: a potential therapeutic target

The study aimed to investigate the clinical significance of fibrous sheath interacting protein 1 (FSIP1) in bladder cancer, and its potential relevance to the survival of patients with bladder cancer. A total of 225 surgical excised-bladder cancer tissues were collected from the patients with the follow-up data > 5 years. The FSIP1 expressions were assayed using immunohistochemistry. The messenger RNA (mRNA) and/or protein levels of FSIP1 in fresh bladder tumor tissues as well as bladder cancer cell lines were measured by quantitative real-time polymerase chain reaction (PCR) and Western blotting analysis. The correlation of FSIP1 expression with clinicopathological parameters was also evaluated. Western blotting analysis revealed that FSIP1 protein was detected in 94.1% (16/17) of bladder tumor specimens and in all three bladder cancer cell lines (5637, BIU-87, and T24 in particular), with significantly higher expression than those of their controls. Quantitative real-time PCR demonstrated an increased FSIP1 mRNA expression level in bladder cancer tissues than in normal adjacent tissues (P=0.012). FSIP1 overexpression showed good correlation with tumor stage and lymph node metastasis (P=0.027 and 0.000, respectively). Positive FSIP1 expression was independently associated with an unfavorable overall and disease-free survival by multivariate Cox regression (P=0.037 and 0.019, respectively). FSIP1 overexpression is associated with unfavorable prognosis in patients with bladder cancer. Thus, FSIP1 represents a potential therapeutic or predictive target for bladder cancer.