Microrna-98 Sensitizes Cisplatin-Resistant Human Lung Adenocarcinoma Cells by up-Regulation of Hmga2

This study was done to explore the role of microRNA-98 (miR-98) in cisplatin sensitization in human lung adenocarcinoma cell line. Differential expressions of miRNAs were analysed between cisplatin-resistant human lung adenocarcinoma cell line A549/DDP and its parental cell A549 by miRNAs microarray, of which 14 miRNAs were showed to be significantly (>2-fold) up-regulated and 8 miRNAs had marked down-regulation (<0.5-fold) in A549/DDP cells compared with in A549 cells. MiR-98, a member in the let-7 family, acts as a negative regulator in the expression of HMGA2 (high mobility group A2) oncogene, and it has been shown to have a nearly 3-fold decrease in A549/DDP cells. We found that elevated expression of miR-98 led to a higher sensitivity of A549/DDP cells to cisplatin, and the protein level of HMGA2, was clearly up-regulated in both A549/DDP and A549 cells by miR-98. Moreover, both Bcl-XL and Bcl-2, were down-regulated in the Pre-miR-98(TM) transfectants cells. We for the first time demonstrated that the expression of miR-98 increases cells spontaneous apoptosis and sensitizes cells to cisplatin at least in part via HMGA2 up-regulation. Our findings provided insight into some specific miRNAs in lung cancer as potential therapeutic targets.