Overexpression of Long Non-Coding RNA NNT-AS1 Correlates with Tumor Progression and Poor Prognosis in Osteosarcoma.

BACKGROUND/AIMS: Increasing evidence demonstrates that long non-coding RNAs (lncRNAs) play critical regulatory roles in cancers, including osteosarcoma. A previous study showed that Nicotinamide Nucleotide Transhydrogenase-antisense RNA1 (NNT-AS1) was aberrantly expressed in several types of cancer. However, the potential biological roles and regulatory mechanisms of NNT-AS1 in osteosarcoma progression remain unknown.

METHODS: Quantitative RT-PCR was performed to examine the expression of NNT-AS1 in human tissues and cells. The biological functions of NNT-AS1 were determined by CCK-8, colony formation, Flow cytometry and Transwell assays in vitro. A mouse xenograft model was performed to investigate the effect of NNT-AS1 on tumor growth in vivo.

RESULTS: In this study, we found the expression of NNT-AS1 was significantly increased in tumor tissues compared to adjacent normal tissues. Furthermore, upregulated NNT-AS1 expression predicted poor prognosis and was an independent and significant risk factor for osteosarcoma patient survival. Further experiments revealed that NNT-AS1 knockdown significantly inhibited cell proliferation by inducing cell cycle arrest and promoting apoptosis in osteosarcoma cells. Moreover, NNT-AS1 silencing suppressed cell migration and invasion in vitro. In a tumor xenograft model, knockdown of NNT-AS1 suppressed tumor growth of OS-732 cells in vivo.

CONCLUSIONS: Taken together, these findings indicate that NNT-AS1 functions as an oncogene in osteosarcoma and could be a novel diagnostic and therapeutic target for osteosarcoma.