Objective To investigate the role and mechanism of long noncoding RNA (lncRNA) OGRU in the proliferation and migration of human lung adenocarcinoma cell line A549.Methods The levels of lncRNA and miRNA in human normal lung epithelial cell and cell line A549 were detected by microarrays. The levels of lncRNA OGRU and miR-21 were tested by the real time qPCR. Cell transfection was employed to deliver lncRNA OGRU, miR-21, and their respective negative-control sequences. CCK-8 assay and EdU staining were used to detect the cell proliferation. Scratch test and transwell test were used to detect cell migration. The protein levels of Ki67, E-cadherin and N-cadherin were detected by Western blot. Luciferase reporter gene technology was used to verify the relationship between lncRNA OGRU and miR-21.Results Compared with the human normal lung epithelial cell, the cell line A549 had lower expression of lncRNA OGRU and higher expression of miR-21 (P<0.05). Compared with the control group, lncRNA OGRU mimics increased the level of lncRNA OGRU and suppressed the proliferation and migration of A549 (P<0.05). Moreover, lncRNA OGRU mimics decreased the expression of Ki67 and N-cadherin, but increased the expression of E-cadherin (P<0.05). lncRNA OGRU inhibited the luciferase activity of miR-21 (P<0.05). miR-21 overexpression reduced lncRNA OGRU abundance, whereas lncRNA OGRU knock-down increased miR-21 levels (P<0.05). Compared with mimic group, mimic+miR-21 group enhanced proliferation and migration of A549 (P<0.05), yet remained significantly different from the control group (P<0.05). Compared with mimic group, mimic+miR-21 group up-regulated Ki67 and N-cadherin and down-regulated E-cadherin (P<0.05), yet remained significantly different from the control group (P<0.05). Conclusion lncRNA OGRU inhibits proliferation and migration of lung adenocarcinoma cell line A549 by sponging miR-21