NRP-1 expression in bladder cancer and its implications for tumor progression

Neuropilin-1 (NRP-1) overexpression has been reported in a variety of human cancers. However, the role of NRP-1 in bladder cancer (BC) remains unclear. The aim of present study was to analyze NRP-1 protein expression in BC tissues and to assess its prognostic significance for BC. NRP-1 messenger ribonucleic acid (mRNA) and protein expression were determined by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and immunohistochemistry in specimens of primary cancer and their adjacent noncancerous tissues in BC patients. Additionally, NRP-1 protein expression in 139 archived paraffin-embedded BC samples was analyzed by immunohistochemistry and correlated with clinicopathological characteristics and survival. Student's t test, Spearman's rank correlation, Kaplan-Meier plots, and Cox's proportional hazards regression model were used to analyze the data. By qRT-PCR and immunohistochemistry, the levels of NRP-1 mRNA and protein were significantly higher in BC, compared to that in adjacent noncancerous tissues (P < 0.001). High expression of NRP-1 was significantly associated with histologic grade (P = 0.016) and tumor stage (P = 0.001). Multivariate analysis showed that high expression of NRP-1 was an independent prognostic factor for overall survival. Our study suggests that overexpression of NRP-1 may play an important role in the progression of BC, and NRP-1 expression may serve as a biomarker for poor prognosis for BC.