CirRNA circFAM126A Exerts Oncogenic Functions in NSCLC to Upregulate IRS2

Non-small cell lung cancer (NSCLC) is a common histological subtype of lung cancer, which occupies 80-85% of the proportion in all lung cancer cases. Therefore, this study was designed to clarify the role and underlying molecular mechanisms of circFAM126A in NSCLC. The real-time quantitative polymerase chain reaction (RT-qPCR) assay was conducted to assess circFAM126A, FAM126A, miR-613, and IRS2 expression in NSCLC tissues and cells. The proliferation ability of cells was measured by MTT, EdU, and colony-forming assays. The flow cytometry assay was performed to evaluate cell cycle distribution and apoptosis of NSCLC cells. The migration and invasion were determined by wound healing and transwell matrigel assays, respectively. The interaction relationship between miR-613 and circFAM126A or IRS2 was analyzed by dual-luciferase reporter and RNA pull-down assays. Tumorigenesis in nude mice was conducted to clarify the functional roles of circFAM126A inhibition in vivo. CircFAM126A was obviously overexpressed in NSCLC tissues and cells when compared with controls. The loss-of-functional experiments suggested that knockdown of circFAM126A suppressed proliferation, migration and invasion, as well as caused apoptosis and cell cycle arrest in NSCLC cells, which was abolished by silencing of miR-613. In addition, IRS2 was a target gene of miR-613. Overexpression of miR-613 exerted carcinoma inhibitor role in NSCLC by inhibition of IRS2 expression. Consistently, the silencing of circFAM126A also functioned anti-tumorigenic roles in nude mice in vivo. Mechanistically, circFAM126A could function as a miRNA sponge for miR-613 to regulate the expression of IRS2, thereby regulating proliferation, migration, invasion, apoptosis, and cell cycle arrest in NSCLC cells.