Silencing of Long Non-Coding RNA (LncRNA) Non-Coding RNA Activated by DNA Damage (NORAD) Inhibits Proliferation, Invasion, Migration, and Promotes Apoptosis of Glioma Cells via Downregulating the Expression of AKR1B1.

BACKGROUND We aimed to investigate the functions of long non-coding RNA (lncRNA) non-coding RNA activated by DNA damage (NORAD) in glioma and identify the potential mechanisms. MATERIAL AND METHODS The expression of NORAD and AKR1B1 in human glioma cell lines were examined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Then, cell proliferation, invasion, and migration were tested by Cell Counting Kit-8 (CCK-8), colony formation assay, Transwell, and scratch wound healing assay after NORAD silencing. Meanwhile, western blotting was utilized to measure the expression of migration-related proteins. Apoptosis of glioma cells was detected using flow cytometry and apoptosis-related proteins expression was determined. Moreover, the correlation between NORAD and AKR1B1 was verified by RNA-binding protein immunoprecipitation (RIP assay). After co-transfection with AKR1B1 overexpressed plasmid and NORAD siRNA, cell proliferation, invasion, migration, and apoptosis were examined again. Furthermore, the expression of proteins in extracellular signal-regulated kinase (ERK) signaling was tested using western blotting. RESULTS The results revealed that NORAD and AKR1B1 were highly expressed in glioma cells. NORAD silencing inhibited proliferation, invasion and migration but promoted apoptosis of glioma cells, accompanied by the expression changes of migration- and apoptosis-related proteins. However, after co-transfection with AKR1B1 pcDNA3.1 in NORAD silencing cells, the effects of NORAD silencing on proliferation, invasion, migration, and apoptosis were attenuated. Consistently, the expression of phosphorylated ERK (p-ERK) was decreased after NORAD silencing, which were reversed following AKR1B1 overexpression. CONCLUSIONS These findings demonstrated that NORAD silencing suppressed proliferation, invasion, and migration and boosted apoptosis of glioma cells via downregulating the AKR1B1 expression, which may provide a potential therapeutic target for glioma treatment.