MicroRNA-200a Affects the Proliferation of Airway Smooth Muscle Cells and Airway Remodeling by Targeting FOXC1 via the PI3K/AKT Signaling Pathway in Ovalbumin-Induced Asthmatic Mice.

BACKGROUND/AIMS: The etiology of asthma, which is a complicated disorder with various symptoms, including wheezing, coughing, and airflow obstruction, remains poorly understood. In addition, the effects of microRNAs (miRs) have not been explored. This study explored the effect of microRNA-200a (miR-200a) on airway smooth muscle cells (ASMCs) and airway remodeling in asthmatic mice. Furthermore, we speculated that miR-200a achieves its effect by targeting FOXC1 via the PI3K/AKT signaling pathway based on differentially expressed gene screening, target miR predictions and a bioinformatics analysis.

METHODS: Eighty mice were assigned to a saline group or an ovalbumin (OVA) group, and the OVA group was transfected with a series of inhibitors, activators, and siRNAs to test the established mouse model. Airway reactivity and the ratio of eosinophils (EOSs) to leukocytes were detected. An ELISA was adopted to measure the levels of interleukin (IL)-4, IL-6, IL-8, tumor necrosis factor (TNF)-α, and immunoglobulin E (IgE). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to determine the expression of FOXC1, PI3K, AKT, NF-κB, cyclin D1, TGF-β1 and p-AKT in ASMCs. Finally, CCK-8 assays were performed to detect cell proliferation and flow cytometry to detect apoptosis and cell cycle entry.

RESULTS: The bioinformatics analysis indicated that miR-200a mediated the PI3K/AKT signaling pathway by targeting FOXC1. In addition, mouse models of asthma were established. An elevated expression of miR-200a, a decreased mRNA and protein expression of FOXC1, PI3K, AKT, NF-κB, cyclin D1 and TGF-β1, a decreased expression of p-AKT, suppressed cell proliferation, accelerated apoptosis, and an increased number of cells at the G0/G1 phase were observed following the upregulation of miR-200a and downregulation of FOXC1.

CONCLUSION: The overexpression of miR-200a may downregulate FOXC1, thereby inhibiting the activation of the PI3K/AKT signaling pathway and ultimately suppressing ASMC proliferation and airway remodeling in asthmatic mice. This evidence supports the potential that miR-200a represents a new approach to treating asthma.