Abstract: Objective: To study the effect of EBF1 gene knockdown on proliferation of lung adenocarcinoma A549 cells in vitro and in vivo, and to explore its mechanism.Methods: Immunohistochemistry and RT-PCR were used to detect the expression of EBF1 in lung cancer tissues and lung cancer cell lines. A recombinant retroviral shRNA expression vector was constructed and transfected into A549 cells according to the shRNA sequence of EBF1 designed by our lab. Knockdown of EBF1 gene was detected by RT-PCR and Western blot. MTT and BrdU staining were used to detect the effect of EF1-shRNA on the proliferation of A549 cells in vitro; the detection of the effect of ebf1-shRNA on the invasion and migration of A549 cells in vitro by Transwell and scratch experiments;flow cytometry was used to analyze the cell cycle of each group; subcutaneous inoculation of cells in axilla of nude mice was used to observe the effect of EBF1-shRNA on the tumorigenicity of A549 cells in nude mice; Western blot was used to detect the expression of CDK6, P21 and P27 proteins. Results: EBF1 was not expressed in stromal cells of adjacent tissues and lung cancer tissues, but in nuclei of NSCLC and SCLC cancer cells. EBF1-shRNA knockdown EBF1 gene expression effectively; knockdown EBF1 gene expression can inhibit the proliferation of A549 cells in vitro and in vivo, and block the cell cycle of experimental group at G1 phase; after knockdown EBF1 gene expression, CDK6 protein expression in experimental group cells decreases, while P21 and P27 protein increase. Conclusion: EBF1-shRNA can inhibit the proliferation of lung adenocarcinoma A549 in vitro and in vivo by blocking cell cycle in G1 phase, which involves the decrease of CDK6 expression and the up-regulation of P21/P27 expression.

Key words: lung neoplasms, adenocarcinoma, RNA interference, cell proliferation, cell cycle, A549 cells, EBF1