Circ_0000376, a Novel circRNA, Promotes the Progression of Non-Small Cell Lung Cancer Through Regulating the miR-1182/NOVA2 Network

BACKGROUND: Hypoxia has been shown to induce the malignant progression of cancer, including non-small cell lung cancer (NSCLC). Circular RNA (circRNA) is considered to be an important regulator of cancer progression. However, the role of a newly discovered circRNA, circ_0000376, in the progression of NSCLC is unclear. METHODS: The relative expression levels of circ_0000376, miR-1182 and neuro-oncological ventral antigen 2 (NOVA2) were detected via quantitative real-time polymerase chain reaction (qRT-PCR). Glucose consumption and lactate production were determined using Glucose Assay Kit and Lactate Assay Kit, respectively. Moreover, the protein levels of glycolysis markers and NOVA2 were measured using Western blot (WB) analysis. Furthermore, 3-(4, 5-dimethyl-2 thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay was performed to assess cell viability, and transwell assay was employed to evaluate cell migration and invasion. The interaction between miR-1182 and circ_0000376 or NOVA2 was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. In addition, animal experiments were conducted to assess the influence of circ_0000376 silencing on NSCLC tumor growth in vivo. RESULTS: Circ_0000376 was upregulated in NSCLC, and its high expression was related to the poor overall survival of NSCLC patients. Hypoxia could enhance circ_0000376 expression and promote the glycolysis, viability, migration, and invasion of NSCLC cells. However, silencing of circ_0000376 could inhibit the glycolysis, viability, migration, and invasion of hypoxia-induced NSCLC cells. Additionally, circ_0000376 could sponge miR-1182, and miR-1182 could target NOVA2. MiR-1182 silencing could reverse the inhibitory effect of circ_0000376 knockdown on NSCLC progression, and NOVA2 overexpression also could reverse the suppressive effect of miR-1182 overexpression on NSCLC progression. Meanwhile, miR-1182 inhibitor could invert the negative regulation effect of circ_0000376 silencing on NOVA2 expression. In addition, circ_0000376 knockdown inhibited the NSCLC tumor growth via regulating the miR-1182 and NOVA2 expression in vivo. CONCLUSION: Circ_0000376 promoted NSCLC progression by regulating the miR-1182/NOVA2 axis, suggesting that circ_0000376 might be a potential biomarker for NSCLC treatment.