miR-16-2-3p enhances glucocorticoid sensitivity in ulcerative colitis by targeting CREB1 and NF-κB1.

In this study, we systematically investigated the role of miR-16-2-3p, a microRNA passenger strand derived from the MIR16-2 hairpin, in glucocorticoid resistance (GCR) and its underlying regulatory mechanisms. The results showed that miR-16-2-3p expression was significantly downregulated in patients with GCR and in glucocorticoid-resistant-like inflammatory models, and was positively correlated with glucocorticoid receptor (GR) expression, accompanied by a reduced responsiveness to the glucocorticoid dexamethasone (Dex). Functional experiments demonstrated that overexpression of miR-16-2-3p enhanced the inhibitory effects of Dex on inflammatory cytokines (interleukin [IL]-1β, IL-6, IL-8, and tumour necrosis factor alpha [TNF-α]) and promoted nuclear translocation of the GR, whereas inhibition of miR-16-2-3p expression attenuated the anti-inflammatory effects of Dex. Mechanistically, cAMP response element-binding protein 1 (CREB1) was identified as a direct target of miR-16-2-3p, and CREB1 silencing promoted GR nuclear translocation and enhanced the anti-inflammatory efficacy of Dex. In addition, miR-16-2-3p further suppressed nuclear factor kappa-B (NF-κB) signalling by targeting NF-κB1 (p105), thereby synergistically strengthening the inhibitory effect of Dex on NF-κB. In vivo, overexpression of miR-16-2-3p significantly improved the pathological phenotype of dextran sulphate sodium (DSS)-induced ulcerative colitis (UC) in mice and enhanced the therapeutic effect of Dex. Our findings revealed a dual molecular mechanism by which miR-16-2-3p enhances glucocorticoid sensitivity (GCS) through targeting CREB1 and NF-κB1, providing experimental evidence for its potential as a novel therapeutic agent for GCR.