Long Noncoding RNA FENDRR Inhibits Lung Fibroblast Proliferation via a Reduction of β-Catenin

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive, and usually lethal lung disease and it has been widely accepted that fibroblast proliferation is one of the key characteristics of IPF. Long noncoding RNAs (lncRNAs) play vital roles in the pathogenesis of many diseases. In this study, we investigated the role of lncRNA FENDRR on fibroblast proliferation. Human lung fibroblasts stably overexpressing FENDRR showed a reduced cell proliferation compared to those expressing the control vector. On the other hand, FENDRR silencing increased fibroblast proliferation. FENDRR bound serine-arginine rich splicing factor 9 (SRSF9) and inhibited the phosphorylation of p70 ribosomal S6 kinase 1 (PS6K), a downstream protein of the mammalian target of rapamycin (mTOR) signaling. Silencing SRSF9 reduced fibroblast proliferation. FENDRR reduced β-catenin protein, but not mRNA levels. The reduction of β-catenin protein levels in lung fibroblasts by gene silencing or chemical inhibitor decreased fibroblast proliferation. Adenovirus-mediated FENDRR transfer to the lungs of mice reduced asbestos-induced fibrotic lesions and collagen deposition. RNA sequencing of lung tissues identified 7 cell proliferation-related genes that were up-regulated by asbestos but reversed by FENDRR. In conclusion, FENDRR inhibits fibroblast proliferation and functions as an anti-fibrotic lncRNA.