MicroRNA-146a expression inhibits the proliferation and promotes the apoptosis of bronchial smooth muscle cells in asthma by directly targeting the epidermal growth factor receptor.

The present study aimed to determine the expression of microRNA-146a (miR-146a) in the plasma of children with asthma, and to investigate the effect of miR-146a on the proliferation and apoptosis of bronchial smooth muscle cells (BSMCs). Reverse transcription-quantitative polymerase chain reaction was used to determine the expression levels of miR-146a mimics and its inhibitor. A Cell Counting kit-8 assay was performed to examine the proliferation of BSMCs. Caspase-3/7 activity was determined using a Caspase-Glo 3/7 kit. To measure the expression levels of proteins associated with apoptosis, western blotting was performed. The target gene of miR-146a was identified using a dual-luciferase reporter assay. The plasma levels of miR-146a in children with asthma were significantly higher compared with those in healthy children. Enhanced miR-146a expression inhibited the proliferation of BSMCs. BSMC apoptosis was promoted by miR-146a. The mechanism underlying the miR-146a-induced promotion of BSMC apoptosis may be its direct targeting of epidermal growth factor receptor (EGFR), which affects downstream signaling pathways. In conclusion, miR-146a expression in asthma inhibits the proliferation and promotes the apoptosis of BSMCs by direct targeting of EGFR.