microRNA-141-3p mediates epithelial cell proliferation, apoptosis, and epithelial-mesenchymal transition and alleviates pulmonary fibrosis in mice via Spred2.

Objective: This study probed the mechanism of microRNA (miR)-141-3p in the progression of pulmonary fibrosis (PF).

Methods: Mice were intratracheally administered with bleomycin (BLM) to establish a PF mouse model. To investigate the effects of miR-141-3p/Spred2 on PF in mice, PF mice received tail vein injections with agomir-141-3p and/or adenovirus vectors overexpressing Spred2 one week after BLM treatment. Then, the pathological changes of lung tissues were analyzed with H&E and Masson's trichrome staining and hydroxyproline contents in lung tissues were measured. For cell experiments, after loss- and gain-of-function assays, the role of miR-141-3p/Spred2 in the apoptosis and viability of TGF-β1-stimulated MLE-12 cells was examined by flow cytometry and CCK-8 assay. miR-141-3p, Spred2, COl 1, and α-SMA expression was determined in cells and mice. Then, the binding of miR-141-3p to Spred2 was tested with a dual-luciferase reporter assay.

Results: There were abnormally upregulated Spred2 and downregulated miR-141-3p in lung tissues of PF mice. TGF-β1 decelerated viability and augmented apoptosis and COl 1 and α-SMA expression in MLE-12 cells. Spred2 knockdown diminished apoptosis and α-SMA and COl 1 expression while enhancing proliferation in TGF-β1-treated MLE-12 cells. Mechanistically, Spred2 was a target gene of miR-141-3p. miR-141-3p upregulation accelerated proliferation and repressed apoptosis and α-SMA and COl 1 expression in TGF-β1-treated MLE-12 cells, which was nullified by further overexpressing Spred2. miR-141-3p alleviated PF in mice by targeting Spred2.

Conclusion: miR-141-3p negatively modulates Spred2 to promote proliferation and repress epithelial-mesenchymal transition and apoptosis of epithelial cells, as well as ameliorating PF in mice.