Influence of miRNA-223 on drug-resistance of non-small cell lung cancer A549/DDP cells to cisplatin

HU Min; WEI Xiaoxia; ZOU Jie; CUI Facai; PANG Xiaohui

Abstract：Objective To explore the influence of miRNA?223 ( miR?223) on drug?resistance of non?small cell lung cancer A549/DDP cells to dichorodiamine platinum ( DDP ) and its possible mechanism. Methods The real?time fluorescence quantitative PCR ( qRT?PCR) was used to measure the miR?223 level of A549/DDP cells. According to the experimental protocol, A549/DDP cells were divided into 3 groups:control group, empty vector transfection group ( cells transfected with unrelated sequence) and inhibi?tor group ( cells transfected with miR?223 inhibitor) . The qRT?PCR and CCK?8 were applied to detect the effect of transfection and pro?liferation at 24, 48, 72 and 96 h post?transfection. The changes of drug?resistance of A549/DDP cells to cisplatin were measured by CCK?8. The cell cycle and apoptosis at 48 h post?transfection were detected via flow cytometry. The changes of expression of multidrug resistance protein, such as P?glycoprotein ( P?gp) , multidrug resistance associated protein 1 ( MRP1) and lung resistance related pro?tein (LRP), were evaluated by Western blotting. Results A higher level of miR?223 was observed in A549/DDP cells than in A549 cells with a (7?14±0?26)?fold increase. There was a decreased miR?223 level in inhibitor group after transfection, which was further decreased compared to (67?15±2?84)% of the control group and (65?80±3?47)% of the empty vector transfected group at 96 h post?transfection ( P<0?05) . Compared with the control group, there were elevated inhibitory rates of proliferation, early and late apoptotic rates and proportion of cells in G0/G1 phase but reduced proportion of cells in S and G2/M phases and three protein levels related to re?sistance genes in inhibitor group. The inhibited concentration of 50% (IC50) for DDP was (15?67±1?30) μg/ml in inhibitor group, lower than ( 33?71 ± 2?61) μg/ml in control group. Conclusion MiR?223 can increase the drug resistance of A549/DDP cells to DDP, possibly by increasing the gene expression related to resistance. The reduced level of miR?223 resulted in the inhibition of the proliferation, induction of apoptosis and cell cycle arrest and the down?regulation of drug resistance protein.