MicroRNA is a large class of non-coding small RNA that exerts critical roles in many physiological processes including cell proliferation. MicroRNA-7 (miR-7) has been considered as a tumor suppressor in most malignant tumors versus a tumor promoter in some other ones. However, its role in chronic myeloid leukemia remains unknown. Herein, we found that K562 cell proliferation was largely suppressed when it was stably transfected with miR-7. In accordance with that, apoptosis was also significantly upregulated in miR-7 stably-transfected K562 cells. Moreover, we found that miR-7-overexpressed K562 cells were far more sensitive to imatinib than controls. Further investigations showed that the ABL1 was a direct target of miR-7. Expression level of BCR-ABL and the activity of its downstream PI3K/AKT pathway were significantly reduced in miR-7-transfected cells. Taken together, our results showed that miR-7 inhibited proliferation and promoted apoptosis in K562 cells, and miR-7 might help to sensitize them to imatinib through BCR-ABL/PI3K/AICT signaling in chronic myeloid leukemia. (C) 2017 Elsevier Inc. All rights reserved.