Circular RNA hsa_circUCK2 involved in regulation of pulmonary fibrosis induced by silicon dioxide

BackgroundPulmonary fibrosis currently lacks screening and diagnostic methods in the early stages and effective treatments in the later stages, so there is an urgent need to explore the mechanisms and develop targeted treatments.ObjectiveTo screen the expression of differentially expressed circular RNA (circRNA) hsa_circUCK2 under pathological conditions and to explore its effect on pulmonary fibrosis.MethodsIn the cell-based experiments, hsa_circUCK2 was knocked down in HPF-a cells using small interfering RNA (siRNA), and HPF-a cells were stimulated by TGF-β1. Four groups were set up: si-NC group, si-circUCK2 group, si-NC+TGF-β1-treated group, and si-circUCK2+TGF-β1-treated group. Western blot assay was used to detect the expression of fibronectin (FN1) in HPF-a cells of the four groups, scratch assay was used to detect the migration ability of HPF-a cells, and CCK-8 assay was used to detect the proliferation ability of HPF-a cells in the two groups with TGF-β1 stimulation, the si-NC+TGF-β1-treated group and the si-circUCK2+TGF-β1-treated group. In the animal experiments, forty-eighty healthy SPF-grade male C57BL/6 mice were randomly divided into four groups: saline+si-con group, saline+si-circ_0000115 group, SiO2+si-con group, and SiO2+si-circ_0000115 group. Mouse lung circRNA mmu_circ_0000115 (mouse homolog of hsa_circUCK2) was knocked down by tracheal drip injection of siRNA, and a mouse lung fibrosis model was constructed by tracheal drip injection of SiO2 suspension (0.2 g·kg−1, 50 mg·mL−1) after 48 h. Real-time fluorescence quantitative PCR was used to detect the knockout efficiency in each organ of the mouse, Western blot was applied to detect the expression of type I collagen α2 (COL1A2) in the lung tissues, and Sirius red was used to detect collagen synthesis in the lung tissues.ResultsIn the cell-based experiments, after the knockdown of hsa_circUCK2, the Western blot results showed that the expression level of the FN1 protein in TGF-β1-stimulated HPF-a cells was significantly down-regulated (P