Impact of microRNA- 21 antisense oligonucleotide on cisplatin resistance of EC9706/DDP cells

Objective To investigate the impact of microRNA(miRNA)- 21 antisense oligonucleotide on cisplatin(DDP) resistance of EC9706/DDP cells. Methods miRNA- 21 antisense oligonucleotides were designed and transfected into EC9706/DDP- resistant cells.The miRNA- 21 expression levels were detected by real- time fluorescent quantitative polymerase chain reaction(FQ- PCR).Methyl thiazol tetrazolium(MTT) method was used to measure the sensitivity of cells to DDP drugs.Colony formation assay was used to test the cell proliferation. The change of apoptosis was examined by flow cytometry. Western blotting was performed to detect the expression of B cell lymphoma/leukemia- 2(bcl- 2), and bcl- 2 associated X protein(bax) proteins. Results As compared with miRNA- NC negative control group and blank control group, the miRNA- 21 relative expression was decreased to(0.21±0.89),50% inhibitory dose(IC50)decreased to(16.22±1.85)mg/L, the number of clonal colonies was reduced, the apoptosis rate significantly increased to(30.5±2.9)%, bcl- 2 protein expression decreased,and bax protein expression increased in miRNA- 21 antisense oligonucleotide group(P< 0.05). Conclusion miRNA - 21 decreased the resistance of EC9706/DDP cells to DDP possibly through reducing the bcl- 2 protein expression, and increasing the bax protein expression. Key words: MicroRNA-21; Esophageal cancer; Cisplatin