Circ_PWWP2A promotes lung fibroblast proliferation and fibrosis via the miR-27b-3p/GATA3 axis, thereby aggravating idiopathic pulmonary fibrosis.

OBJECTIVE: This paper was to investigate the effect of circ_PWWP2A-mediated miR-27b-3p/GATA3 axis on idiopathic pulmonary fibrosis (IPF). METHODS: circ_PWWP2A expression in lung fibroblasts MLg2908 induced by different concentrations of TGF-ß was detected. The relationship between circ_PWWP2A or GATA3 and miR-27b-3p was analyzed by RNA immunoprecipitation and dual-luciferin reporter assay. The proliferation of MLg2908 cells was determined by MTT. GATA3, α-SMA, Collagen-I, and Collagen-III in cells were detected by RT-qPCR and Western blot. The rat model of IPF induced by bleomycin (BLM) was constructed and treated with circ_PWWP2A siRNA injection. HE and Masson staining were of utility to evaluate the pathological conditions of rat lung tissue, and circ_PWWP2A, miR-27b-3p, and GATA3 levels in lung tissues were detected by RT-qPCR. Immunohistochemistry was used to detect the staining of α-SMA, collagen I, and collagen III in the lung tissues of rats. RESULTS: circ_PWWP2A in MLg2908 cells induced by TGF-ß decreased in a concentration-dependent manner. MLg2908 cells transfected with circ_PWWP2A siRNA were induced by 5 ng/ml TGF-ß, decreasing circ_PWWP2A and GATA3 levels, increasing miR-27b-3p expression, and suppressing cell proliferation. The targeting relationship between circ_PWWP2A and miR-27b-3p, as well as miR-27b-3p and GATA3, was confirmed. Depleting miR-27b-3p reduced the inhibitory effect of circ_PWWP2A down-regulation on the proliferation of TGF-ß-treated MLg2908 cells, accompanied by increased expression of α-SMA, Collagen 1, and Collagen 3, and increased expression of GATA3. The in vivo results showed that BLM-induced fibrosis in rat lung tissue was obvious, accompanied by increased expression of circ_PWWP2A and GATA3, decreased expression of miR-27b-3p, and deepened staining of α-SMA, collagen I, and collagen III, but circ_PWWP2A siRNA could improve these phenomena. CONCLUSION: Silencing circ_PWWP2A can inhibit the proliferation of lung fibroblasts induced by TGF-ß through the miR-27b-3p/GATA3 axis, and reduce BLM-induced pulmonary fibrosis in rats, which may be a potential therapeutic target for IPF.

MiR-20a-5p suppressed TGF-ß1-triggered apoptosis of human bronchial epithelial BEAS-2B cells by targeting STAT3.

Apoptosis of bronchial epithelial cells contributes to lung diseases, including asthma. Although miR-20a-5p is reportedly downregulated in the bronchial epithelia of asthmatic patients, its function and mechanism still need to be explored. Here, we explored how miR-20a-5p affects human bronchial epithelial cells stimulated with transforming growth factor (TGF)-ß1. Using qRT-PCR, we observed downregulated miR-20a-5p levels in these cells. After transfecting miR-20a-5p mimics or inhibitors into human bronchial epithelium BEAS-2B cells, a Cell Counting Kit-8 assay and flow cytometry analysis showed that the mimics mitigated suppression of cell viability and acceleration of apoptosis that was triggered by TGF-ß1, whereas the inhibitors exerted the opposite effects. TGF-ß1 induced a decrease in expression of Bcl-2 and an increase in expression of Bax, both of which were inhibited by miR-20a-5p mimics and further enhanced by miR-20a-5p inhibitors. Further study verified that miR-20a-5p targeted the signal transducer and activator of transcription 3 (STAT3) and the STAT3 level was inversely related to the miR-20a-5p level. Furthermore, STAT3 overexpression partly counteracted the miR-20a-5p-induced anti-apoptotic effect in TGF-ß1-treated BEAS-2B cells. In summary, this study suggested that miR-20a-5p restrained apoptosis in TGF-ß1-stimulated BEAS-2B cells by targeting STAT3. MiR-20a-5p thus may be a novel therapeutic target for asthma treatment.