BACKGROUND: Cisplatin (DDP)-based chemotherapy is the mainstay of first-line therapy for lung cancer. However, their efficacy is often limited by the existence or development of chemoresistance. The aim of this study was to find and investigate the function of miRNAs in cisplatin (DDP)-resistant non-small cell lung cancer (NSCLC) A549 cell. METHODS: Quantitative real-time PCR assay was employed to compare the differences of miRNA expression in both cisplatin-resistant A549 (A549/DDP) cell and the parental A549 cell. The dysregulated miRNAs were then corrected by transfecting oligonucleotides into A549/DDP cells. The cellular sensitivity to cisplatin, cell apoptosis and migration were conducted by MTT, flow cytometry and cell wound healing assay, respectively. RESULTS: Both miR-589 and miR-1244 were significantly down-regulated in A549/DDP cell compared to the parental A549, while the expression of miR-182 and miR-224 were increased in A549/DDP cell (P?