High hsa_circ_0020123 expression indicates poor progression to non-small cell lung cancer by regulating the miR-495/HOXC9 axis.

Circular RNAs (circRNAs) belong to non-protein-coding RNAs that regulate different pathophysiological procedures. Upregulation of hsa_circ_0020123 is found in non-small cell lung cancer (NSCLC); however, its activity and functions are not clear. In this study, the results showed that hsa_circ_0020123 expression increased in both tumor tissues and NSCLC cells. A higher hsa_circ_0020123 expression also led to poor prognoses among NSCLC patients assayed via FISH. The data of FISH also confirmed that hsa_circ_0020123 primarily had a cytoplasmic location. Hsa_circ_0020123 knockdown caused a significant decrease in nude mouse xenograft growth. Bioinformatics analyses and dual luciferase reporter assays confirmed that hsa_circ_0020123 was an miR-495 sponge and that the gene was a miR-495 target. The miR-495 downregulation reversed cell migration and proliferation inhibition induced by hsa_circ_0020123 silencing . HOXC9 overexpression reversed miR-495-induced inhibition of cell migration and proliferation. The dual luciferase reporter assay demonstrated that hsa_circ_0020123 interacted with miR-495 by binding to the HOXC9 3'-UTR to suppresses post-transcriptional HOXC9 expression. Taken together, our study found that hsa_circ_0020123 functioned like a tumor promoter via a novel hsa_circ_0020123/miR-495/HOXC9 axis, highlighting its possibility as a new NSCLC therapeutic target.