Epithelial–mesenchymal transition (EMT) may promote small airway remodeling and fibrosis in patients with COPD and increase the likelihood of lung cancer [17], circ0061052 regulates the expression of FoxC1/Snail by competitively binding miR-515-5p in human bronchial epithelial cells and involves in the CS-induced EMT and airway remodeling in COPD [18]. Here, SNAI1 is linked to chronic obstructive pulmonary disease.