RESUMO
Objective The purpose of this study was to investigate the differential expression of microRNA in gefitinib acquired resistant lung cancer cells and non-resistant cells and their roles on cell growth.MethodsGefitinib resistant NSCLC A549 and H1299 cells were constructed. The cell activity was detected by CCK-8 assays. Real-time PCR was used to detect microRNA expression. The intracellular microRNA expression profile was detected by microarray. The transfection of miRNA-7 mimic was used to up-regulate the expression of mir-7. EGFR protein expression was detected by Western -blotting.ResultsThe IC50 value of gefitinib resistant cells was 3 fold than that of their parental cells. The drug-resistant cells grew slowly compared with their parental cells. 43 miRNA were significantly changed in the gefitinib resistant cells, including 25 up-regulated miRNA and 18 down-regulated miRNA. The IC50 was significantly decreased and the EGFR expression was negatively regulated after up-regulated of mir-7.ConclusionmiR-7 expression negatively regulates EGFR expression and decreased expression of miR-7 is one of the mechanisms leading to gefitinib resistance in non-small cell lung cancer cells.