Upregulation of microRNA-16 alters the response to inhaled β-agonists in patients with asthma though modulating expression of ADRB2

MicroRNAs (miRNAs) are non-coding RNAs of ~22 nucleotides in length, which serve an important role in numerous diseases. Asthma is a chronic airway inflammatory disease, which is the most common chronic disease among children. The role of miRNA (miR)-16 in asthma is unclear. The objective of the present study was to examine the underlying molecular mechanism of the involvement of miR-16 in asthma. A total of 72 volunteers diagnosed with asthma consented to participate in the study, of whom 52 participants were identified to be sensitive to salmeterol and 20 participants were identified to be resistant to salmeterol. Receiver operating characteristic (ROC) curve analysis was performed to compare the expression levels of serum miR-16 between the sensitive and resistant groups, and to confirm the association between the expression level of serum miR-16 and forced expiratory volume in 1 sec (FEV1). In silico analysis, a luciferase assay, reverse transcription-quantitative polymerase chain reaction analysis and western blotting were performed to elucidate the molecular mechanism underlying the role of miR-16 in asthma. ROC results demonstrated that the serum miR-16 level may function as a biomarker to predict the response to salmeterol therapy, and the miR-16 expression level displayed a significant negative correlation with FEV1. According to the in silico analysis, adrenoreceptor β-2 (ADRB2) was a direct target of miR-16, and it was further confirmed by luciferase assay that 25 nM miR-16 mimic had an inhibitory effect on the luciferase activity of the wild-type ADRB2 3′ untranslated region (UTR); the inhibitory effect on the luciferase activity of the wild-type ADRB2 3′UTR was stronger with 50 nM miR-16 mimic, and strongest with 75 nM miR-16 mimic, whereas the luciferase activity of the mutant ADRB2 3′UTR in cells was similar following treatment with 0, 25, 50 or 75 nM miR-16 mimic. miR-16 reduced the mRNA and protein expression levels of ADRB2 in a dose-dependent manner. These results identified that miR-16 may be used as a predictive biomarker of therapeutic response in asthma.