Downregulation of microRNA-30a in bronchoalveolar lavage fluid from idiopathic pulmonary fibrosis patients

MicroRNAs (miRs) are short, highly conserved small noncoding RNA molecules with fundamental roles in regulating gene expression. To identify miR biomarkers associated with idiopathic pulmonary fibrosis (IPF), the expression pattern of miRs in exosomes from bronchoalveolar lavage fluid (BALF) of elderly patients with IPF were evaluated. High-throughput quantitative detection of miR expression using a microarray indicated that miR-125b, miR-128, miR-21, miR-100, miR-140-3p and miR-374b were upregulated in patients with IPF, while let-7d, miR-103, miR-26 and miR-30a-5p were downregulated. The expression level of miR-30a-5p was further examined, and its potential target genes were predicted using target gene prediction analysis software. A direct regulatory association was confirmed between miR-30a-5p and TGF- activated kinase 1/MAP3K7 binding protein 3 (TAB3) via a dual-luciferase reporter assay. Overexpression of miR-30a-5p decreased TAB3, -smooth muscle actin and fibronectin expression in A549 cells with or without transforming growth factor-1 treatment. The decreased expression of miR-30a in the BALF of patients with IPF, along with the consequential increase in TAB3 expression, may be a crucial factor in IPF progression.