Screening of miRNAs responsible for drug resistance in MCF7-ADR. (A) Direct comparison of MCF7 and MCF7-ADR genomic status based aCGH. Modified Figure1B, differences in genomic status between MCF7 and MCF7-ADR are shown (FC > 2). (B) The number of genes and miRNAs located on the amplified or deleted genome regions in MCF7-ADR as compared with MCF7 (FC > 2). (C) Scatter plot of 49 miRNAs that locates in the deleted genomic regions in MCF7-ADR. (D) Scatter plot of 72 miRNAs whose expression was down-regulated in MCF7-ADR when compared with MCF7. (E) Twelve miRNAs (miR-23b, miR-25, miR-27b, miR-93, miR-106b, miR-189, miR-489, miR-505, miR-542-5p, miR-565, miR-652 and let-7d), which are overlapped between deleted and down-regulated in MCF7-ADR, are candidates responsible for drug resistance in MCF7-ADR. (F) Transfection analysis of selected 12 miRNAs in MCF7-ADR-Luc, which stably express luciferase. All miRNAs were transfected at 20 nM. Seventy-two hours after transfection, cell growth was estimated by luciferase activity in MCF7-ADR-Luc cells (n = 3-6 per group). P < 0.05.