BCR-ABL–dependent expression of the miR-17-92 cluster in bcr-abl⁺ cells. (A) Genomic organization of 3 paralogous miR-17 miRNA clusters (▪ indicates mature miRNAs embedded in precursor miRNAs; □, pre-miRNAs) according to Tanzer and Stadler.¹¹  The role of 17-3p expression as a unique miRNA or a reverse-complement strand is not yet clearly defined. (B) Heat map of miRNA expression profiling from total RNA of K562 cells treated with imatinib, using the miCHIP microarray platform. For each capture probe, the median of 4 background corrected replicas ± SD was calculated. Every experiment was normalized to the average of total signal intensity on each array. For comparative analysis, technical and biologic replicas were averaged after normalization. The left column shows parental K562 cells, and the right column shows imatinib-treated K562 cells. *miRNAs of the miR-17-92 cluster. (C) Heat map of miRNA expression profiling from total RNA of K562 cells treated with lentivirally expressed anti–bcr-abl shRNAs using the miCHIP microarray platform. The left side shows the comparison between parental and control shRNA²⁰  transduced K562 cells, and the right side that between control shRNAs²⁰  and anti–bcr-abl shRNAs. miRNA expression shown in panels B and C was regulated at least 2-fold in at least 1 treatment condition. (D) miRNA-specific quantitative RT-PCR of miRNAs regulated by BCR-ABL as determined by miCHIP. miRNA expression in K562 cells treated as described above with imatinib (dark gray bars) and lentivirally expressed anti–bcr-abl shRNA (blue bars) was compared with the appropriate controls as described in panels B and C. Mean and SD of 2 independent experiments. *No change in miRNA expression. miR-16 served as an endogenous control. (E-F) miRNA-specific quantitative RT-PCR from LAMA-84 (E) and EM-2 (F) cells treated as described for K562 cells. miR-16 served as an endogenous control. Mean and SD of 2 independent experiments. *No change in miRNA expression. (G) miRNA-specific quantitative RT-PCR after treatment of BCR-ABL–negative HL-60 cells with imatinib. miR-16 served as an endogenous control. *No change in miRNA expression.