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LncRNA NNT-AS1 regulates the progression of lung cancer through the NNT-AS1/miR-3666/E2F2 axis.

OBJECTIVE
Lung cancer is the main burden on human health, with high mortality and poor prognosis. The involvement of long non-coding RNAs (lncRNAs) in the development of cancer has attracted wide attention. This study aimed to investigate the role and novel mechanisms of lncRNA nicotinamide nucleotide transhydrogenase antisense RNA 1 (NNT-AS1) in the progression of lung cancer.


MATERIALS AND METHODS
Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was performed to detect the expression of NNT-AS1, microRNA-3666 (miR-3666), and E2F transcription factor 2 (E2F2). 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to analyze cell proliferation. Flow cytometry was carried out to investigate cell apoptosis. Transwell assay was conducted to observe cell invasion. The interaction between miR-3666 and NNT-AS1 or E2F2 was predicted by bioinformatics tool starBase v2.0 and verified by Dual-Luciferase reporter assay. The protein level of E2F2 was quantified by Western blot.


RESULTS
NNT-AS1 and E2F2 were upregulated, but miR-3666 was downregulated in lung cancer tissues and cells. NNT-AS1 knockdown attenuated proliferation and invasion but enhanced apoptosis of lung cancer cells, while miR-3666 inhibition reversed these effects. It was confirmed that miR-3666 was a target of NNT-AS1 and it directly interacted with E2F2. The inhibitory proliferation and invasion, and acceleratory apoptosis of lung cancer cells, caused by miR-3666 enrichment, were overturned by E2F2 overexpression. Furthermore, E2F2 was regulated by NNT-AS1 through miR-3666.


CONCLUSIONS
NNT-AS1 participated in the progression of lung cancer through NNT-AS1/miR-3666/E2F2 regulatory axis at least in part. Our study supplied a promising strategy for the treatment of lung cancer.