Clinical performance and utility of a NNMT-based urine test for bladder cancer.

BACKGROUND: Bladder cancer (BC) represents the most common neoplasm of the urinary tract. Although cystoscopy and urine cytology represent the gold standard methods to monitor BC, both procedures have limitations. Therefore, the identification of reliable biomarkers for early and noninvasive detection of BC is urgently required. METHODS: In this study, we analyzed nicotinamide N-methyltransferase (NNMT) expression in urine samples from 55 BC patients and 107 controls, using real-time polymerase chain reaction (PCR). Receiver operating characteristic (ROC) analysis was used to identify the best cutoff value to discriminate BC patients from healthy donors, and to evaluate the diagnostic accuracy of a urine-based NNMT test. RESULTS: The results demonstrated that urinary NNMT expression was significantly (p<0.05) higher in BC patients. Moreover, a significant (p<0.05) inverse correlation was found between NNMT expression and histological grade. The ROC analysis revealed that a ΔCq of 13.3 was the best cutoff value, since it was associated with the highest combination of sensitivity and specificity. Moreover, the area under the curve (AUC) value was 0.913 (p<0.05), indicating the excellent diagnostic accuracy of a urine-based NNMT test. CONCLUSIONS: Our data indicate that NNMT is a promising biomarker that could be used to support the early and noninvasive diagnosis of BC.

Upregulation of tissue and urinary nicotinamide N-methyltransferase in bladder cancer: potential for the development of a urine-based diagnostic test.

Carcinoma of the bladder is one of the most common urologic malignancies occurring worldwide. Diagnosis and monitoring of bladder urothelial carcinoma (UC) are based on cystoscopy and urinary cytology. However, these diagnostic methods still have some limitations, mainly related to invasive nature and lack of sensitivity. New reliable and non-invasive biomarkers for bladder cancer detection are therefore required. To explore the involvement of enzymes of drug metabolism in bladder cancer, in the present study, we analyzed the gene expression profiles of tumor and normal looking tissues obtained from the same patient by cDNA macroarray. The enzyme nicotinamide N-methyltransferase (NNMT) was identified as a highly expressed gene in bladder cancer. RT-PCR, Real-Time PCR, Western blot analysis, and catalytic activity assay, performed on a large cohort of patients with bladder UC, confirmed NNMT upregulation. NNMT mRNA and protein levels were also determined in urine specimens obtained from patients with bladder UC and healthy subjects. We found that NNMT expression levels were significantly higher in patients with bladder tumor compared to controls that showed very low or undetectable amounts of NNMT transcript and protein. Our results indicate that a marked NNMT increase is a peculiar feature of bladder UC and suggest the potential suitability of urine NNMT expression levels determination for early and non-invasive diagnosis of bladder cancer.