Increasing evidence has indicated that long noncoding RNAs (lncRNAs) could participate in diverse cancers. Among these, lymphoid enhancer-binding factor 1 antisense RNA 1 (LEF1-AS1) was recently identified as an oncogenic lncRNA, but little is known about its function in non-small-cell lung cancer (NSCLC). In the present study, we found that LEF1-AS1 was markedly upregulated in lung cancer tissues and could promote NSCLC cell proliferation and migration in vivo and in vitro. LEF1-AS1 could bind with miR-489 and further negatively regulate miR-489 to promote SRY-related HMG box transcription factor 4 (SOX4) expression. In conclusion, these data suggested that LEF1-AS1 promoted NSCLC tumorigenesis dependent on the miR-489-SOX4 axis and implicated the potential application of LEF1-AS1 for the prognosis and treatment of NSCLC. [ABSTRACT FROM AUTHOR]