circ0066187 promotes pulmonary fibrogenesis through targeting STAT3-mediated metabolism signal pathway.

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive interstitial pneumonia, with increasing incidence and prevalence. One of the cellular characteristics is the differentiation of fibroblasts to myofibroblasts. However, the metabolic-related signaling pathway regulated by circular RNAs (circRNAs) during this process remains unclear. Here, we demonstrated that circ0066187 promoted fibroblast-to-myofibroblast differentiation by metabolic-related signaling pathway. Mechanism analysis research identified that circ0066187 directly targeted signal transducer and activator of transcription 3 (STAT3)-mediated metabolism signal pathway to enhance fibroblast-to-myofibroblast differentiation by sponging miR-29b-2-5p, resulting in pulmonary fibrosis. Integrative multi-omics analysis of metabolomics and proteomics revealed three pathways co-enriched in proteomics and metabolomics, namely, Protein digestion and absorption, PI3K-Akt signaling pathway, and FoxO signaling pathway. In these three signaling pathways, seven differentially expressed metabolites such as L-glutamine, L-proline, adenosine monophosphate (AMP), L-arginine, L-phenylalanine, L-lysine and L-tryptophan, and six differentially expressed proteins containing dipeptidyl peptidase-4 (DPP4), cyclin D1 (CCND1), cyclin-dependent kinase 2 (CDK2), fibroblast growth factor 2 (FGF2), collagen type VI alpha 1 (COL6A1) and superoxide dismutase 2 (SOD2) were co-enriched. Gain-and loss-of-function studies and rescue experiments were performed to verify that circ0066187 promoted STAT3 expression by inhibiting miR-29b-2-5p expression to control the above metabolites and proteins. As a result, these metabolites and proteins provided the material basis and energy requirements for the progression of pulmonary fibrosis. In conclusion, circ0066187 can function as a profibrotic metabolism-related factor, and interference with circ0066187 can prevent pulmonary fibrosis. The finding supported that circ0066187 can be a metabolism-related therapeutic target for IPF treatment.