Abstract: Objective To verify the targeting regulatory relationship of MicR-320c-5p to SERPINA1 gene by dual luciferase reporter system. 
Methods The 3′UTR sequence of SERPINA1 gene was obtained from the genome of human normal lung epithelial cells. Candidate miRNAs were identified by sequence matching. 3% cigarette smoke extract （CSE） was used to induce human bronchial epithelial cells(BEAS-2b cells) to establish a chronic obstructive pulmonary disease （COPD） cell model as the experimental group, and the normally cultured BEAS-2b cells as the control group. The expression levels of SERPINA1 and candidate miRNAs in the two groups were detected by real time flurocent qualitative polymerase chain reaction (RT-qPCR). Wild-type and mutant double luciferase reporter gene vector was constructed. Dual-luciferase reporter plasmids (psiCHECK-2-SERPINA1-3′UTR and psiCHECK-2-SERPINA1-3′UTR ) and miRNA plasmids (miR-320-5p mimic) were co-transfected into 293 T cells respectively for fluorescence activity determination. 
Results By sequence matching, the candidate miR-26, miR-210, miR-320c and miR-96 were set as targeted miRNAs. Compared with the control group, the mRNA expression level of SERPINA1 gene in the experimental group was significantly increased (P＜0.05), while the expression levels of four candidate miRNAs were significantly decreased (P＜0.01), of which miR-320c and miR-96 were more significant (P＜0.001). Based on the correlation between miR-320c and the prognosis of COPD, miR-320c was selected for the subsequent double luciferase experiment. The relative luciferase activity of the construct carrying MicR-320c-5p mimic and SERPINA1 wild type 3, UTR was significantly decreased(P＜0.001), while the relative luciferase activity of the construct carrying SERPINA1 mutant 3′UTR was not significantly decreased (P＞0.05).
Conclusion SERPINA1 expression is up-regulated in BEAS-2b cells induced by 3% CSE, and miR-320c-5p expression is down-regulated. miR-320c-5p may play an important role in the occurrence and development of COPD by negatively regulating SERPINA1 expression.

Key words: pulmonary disease, chronic obstructive, luciferins, micR-320-5p