Introduction:
Accumulating evidence testifies to the considerably significant roles of circular RNAs (circRNAs) in non-small cell lung cancer (NSCLC). This report describes the exploration of the molecular mechanism of circRNA_0001421 (circ_0001421) in NSCLC.

Material and methods:
The relative levels of circ_0001421, microRNA-409-3p (miR-409-3p) and transmembrane protein 14A (TMEM14A) were assayed through quantitative real-time polymerase chain reaction (qRT-PCR). Cell colony formation ability was detected by colony formation assay. Transwell assay was exploited for assessing cell migration and invasion. Glycolysis was evaluated via ECAR measurement, glucose consumption, lactate production and protein detection. The protein levels were examined using Western blot. The target combination between miR-409-3p and circ_0001421 or TMEM14A was analyzed by dual-luciferase reporter assay. Xenotransplantation assay was applied for estimating the effect of circ_0001421 on NSCLC in 10 mice.

Results:
Circ_0001421 was up-regulated in NSCLC tissues and cells. Down-regulation of circ_0001421 suppressed colony formation, migration, invasion and glycolysis of NSCLC cells. Circ_0001421 could sponge microRNA-409-3p (miR-409-3p) and miR-409-3p inhibition relieved the effects of circ_0001421 knockdown on NSCLC cells. MiR-409-3p targeted transmembrane protein 14A (TMEM14A) and circ_0001421 modulated TMEM14A expression via targeting miR-409-3p. Overexpression of miR-409-3p suppressed NSCLC progression by inhibiting TMEM14A. Circ_0001421 depression restrained tumor growth of NSCLC by the miR-409-3p/TMEM14A axis in vivo.

Conclusions:
Circ_0001421 facilitated the development of NSCLC via the regulation of the miR-409-3p/TMEM14A axis. Circ_0001421 may be a promising therapeutic target in NSCLC.