Overexpression of long noncoding RNA NORAD in colorectal cancer associates with tumor progression

PURPOSE: The aim of this study was to elucidate the role and clinical significance of long noncoding RNA-activated by DNA damage (NORAD) in colorectal cancer (CRC). METHODS: Sixty pairs of tumorous and adjacent nontumorous tissues derived from CRC patients were subjected to quantitative real-time polymerase chain reaction to determine the expression level of NORAD. The serum levels of NORAD expression were also measured in an independent cohort of CRC patients as well as patients with benign diseases and healthy controls. Comparative analyses were performed to investigate the relationships between NORAD levels in tissues and clinicopathological features of CRC. Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic value of NORAD in patients with CRC. Furthermore, the potential functions of NORAD in the development of CRC were explored in vitro, using the HCT116 and SW1116 CRC cell lines. RESULT: NORAD expression was significantly upregulated in the tumorous tissues of CRC patients (P<0.001) compared to the adjacent nontumorous tissues. Higher NORAD expression was associated with advanced CRC. Moreover, serum levels supported that NORAD could distinguish CRC patients from healthy controls and patients with benign diseases, indicating a potential diagnostic role in CRC. The ROC curve analysis showed a diagnostic efficacy with area under the curve of 0.800 (95% CI: 0.737–0.853). Mechanistic investigations indicated that NORAD silencing reduced CRC cell proliferation, migration, and invasion. CONCLUSION: NORAD may serve as a novel predictor in CRC and may be a potential target for future therapy.