MiR-503逆转肺癌耐药细胞株A549/DDP的耐药性及其机制研究

BACKGROUND AND OBJECTIVE: Cisplatin-resistance in lung cancer cells is general in clinic, hence it is significant to investigate the mechanisms of cisplatin-resistant and develop new methods of reversing drug-resistance. Recent researches showed that miRNA could regulate cell growth, apoptosis, migration and invasion even in drug therapy in cancer by its target gene. The aim of this study is to investigate the effects and molecular mechanisms of miR-503 on reversing the cisplatin-resistance in lung cancer DDP-resistant cell line A549/DDP. METHODS: MTS assay was employed to determine the effect of miR-503 on A549/DDP' sensitivity to cisplatin. Apoptosis rate and intracellular concentration of rhodamine-123 (Rh-123) were determined by flow cytometry, the expression of multi-drugs resistant proteins MDR1 and MRP1, ERCC1, RhoE, Survivin and Bcl-2 were determined by Western blot and real time PCR. The phosphorylation of Akt was analyzed by Western blot, the transcriptional activities of NF-κB and AP-1 were detected by dual-luciferase reporter gene systems. RESULTS: MiR-503 was able to increase the cisplatin sensitivity of A549/DDP. After treatment with miR-503, the reverse folds (RF) to cisplatin was 2.48 fold, the intracellular level of Rh-123 was 2.49 fold, the apoptosis rate was 10.3 fold, the expressions of several drug-resistant related proteins, such as MDR1, MRP1, ERCC1, Survivin and Bcl-2 were downregulated significantly, as shown by WB, in contrast, the level of RhoE was elevated, the mRNA epression of MDR1 was 18.5%, the mRNA epression of MRP1 was 22.3%, the mRNA epression of ERCC1 was 18.6%, the mRNA epression of Survivin was 42.8%, the mRNA expression of Bcl-2 was 68.1%, the mRNA epression of RhoE was 206.5%, in addition, the phosphorylation of Akt decreased and transcriptional activities of NF-κB was 53.7%, AP-1 was 47.4% compared with control group. CONCLUSION: MiR-503 was able to reverse the cisplatin resistance of A549/DDP. MiR-503 processed this kind of effect by inhibiting the drug efflux, downregulating the expression of drug-resistant related proteins and promoting cell apoptosis.