In the present study, we demonstrated a flexible relation between circFOXO3 and miR-214-3p as follows: (1) A luciferase reporter assay confirmed the direct binding of the predicted miRNA (miR-214-3p) to a binding site in circFOXO3; (2) RIP assays revealed that circFOXO3 and miR-214-3p are present together in a rele(vant RNA-induced silencing complex; (3) miR-214-3p overexpression suppressed CS-induced lung inflammation; (4) circFOXO3 was found to serve as an miR-214-3p sponge, consequently enhancing IKK-β expression and activating the NF-κB pathway. Here, NFKB1 is linked to Cowden syndrome 1.