YY1/circCTNNB1/miR-186-5p/YY1 positive loop aggravates lung cancer progression through the Wnt pathway

Lung cancer is one familiar cancer that threatens the lives of humans. circCTNNB1 has been disclosed to have regulatory functions in some diseases. However, the functions and related regulatory mechanisms of circCTNNB1 in lung cancer remain largely indistinct. The mRNA and protein expression levels were examined through real-time polymerase chain reaction (RT-qPCR) and western blot. The cell proliferation was tested through CCK-8 assay. The cell migration and invasion were confirmed through Transwell assays. The cell senescence was evaluated through SA-β-gal assay. The binding ability between miR-186-5p and circCTNNB1 (or YY1) was verified through luciferase reporter and RIP assays. In this study, the higher expression of circCTNNB1 was discovered in lung cancer tissues and cell lines and resulted in poor prognosis. In addition, circCTNNB1 facilitated lung cancer cell proliferation, migration, invasion, and suppressed cell senescence. Knockdown of circCTNNB1 retarded the Wnt pathway. Mechanism-related experiments revealed that circCTNNB1 combined with miR-186-5p to target YY1. Through rescue assays, YY1 overexpression could rescue decreased cell proliferation, migration, invasion, increased cell senescence, and retarded Wnt pathway mediated by circCTNNB1 suppression. Furthermore, YY1 acts as a transcription factor that can transcriptionally activate circCTNNB1 to form YY1/circCTNNB1/miR-186-5p/YY1 positive loop. Through in vivo assays, circCTNNB1 accelerated tumour growth in vivo. All findings revealed that a positive loop YY1/circCTNNB1/miR-186-5p/YY1 aggravated lung cancer progression by modulating the Wnt pathway.