High expression of long noncoding RNA NORAD indicates a poor prognosis and promotes clinical progression and metastasis in bladder cancer.

PURPOSE: To explore the function of NORAD in bladder cancer (BC), and to verify whether NORAD could be used as a biomarker to determine preoperative presence of progression and lymph node metastasis. To our knowledge, it is the first study investigating NORAD and its implications in BC.

METHODS: BC specimens of 90 patients underwent bladder cystectomy or transurethral resection between January 2012 to December 2016 were tested by fluorescence in situ hybridization. The association between NORAD expression and clinicopathological features and prognosis of the patients was analyzed using Kaplan-Meier survival analysis and Cox regression analysis. Quantitative real-time polymerase chain reaction was performed in 4 BC cell lines and 10 fresh tumor sample together with adjacent tissues. MTT, colony formation assay, and Annexin-V apoptosis detection were performed after knockdown of NORAD using shRNA in TSSCUP cells. Western blot was performed to related proteins extracted from these cells.

RESULTS: Fluorescence in situ hybridization indicated that high NORAD expression was associated with more advanced histological grade and clinical stage for patients with BC. Higher NORAD expression resulted in lower overall survival, and was an independent prognostic indicator. Real-time polymerase chain reaction showed that the expression of NORAD in BC tissues was higher than those measured in adjacent normal tissues. MTT and colony formation assay demonstrated that knockdown of NORAD results in lower proliferation in TSSCUP cells, whereas PUM2 expression was upregulated and E2F3 downregulated.

CONCLUSIONS: High NORAD expression could serve as an independent prognostic factor for overall survival of patients with transitional BC. NORAD could be considered as a promising candidate for novel biomarker and therapeutic target for human BC.