The increased excretion of urinary orosomucoid 1 as a useful biomarker for bladder cancer.

Improving the early detection rate and prediction of bladder cancer remains a great challenge in management of this disease. To examine the value of urinary orosomucoid 1 (ORM1) for the early detection and surveillance of bladder cancer, two-dimensional differential gel electrophoresis (2-DE) and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF/TOFMS) were applied to identify the differently expressed proteins in urine between bladder cancer and healthy controls. Thirteen different proteins including ORM1 were identified. After verification by western blotting, the ORM1 expressions were quantified in 186 urine samples by enzyme-linked immunosorbent assay (ELISA) correcting for creatinine expression. ELISA quantification showed the urinary ORM1-Cr was found to be higher in bladder cancer patients compared to controls and benign cases (7172.23±3049.67 versus 2243.16±969.01, 2493.48±830.37 ng/ml, respectively, P<0.0001). Furthermore, the pearson correlation analysis indicated that urinary ORM1 had high positive correlation with the pathology classification of bladder cancer. Receiver operating characteristic (ROC) analysis was used to calculate the cut-off value for early diagnosis of bladder cancer, and rendered an optimum cut-off value of 3912.97 ng/mg corresponding to 91.96% sensitivity and 94.34% specificity. Moreover, a cut-off value with 7351.28 ng/mg was utilized to distinguish infiltrating urothelial carcinoma from bladder cancer patients corresponding to 91.89% sensitivity and 90.67% specificity. In conclusion, our findings suggested the elevated urinary ORM1 could be a useful biomarker for bladder cancer. Further research is warranted to elucidate the pathogenic mechanisms of elevated ORM1.