Objective      To determine the effect of miR-193b over-expression on the expression of bcr/abl in chronic myelocytic leukemia K562 cells by transfection of recombinant adenovirus of Ad-pre-microRNA-193b.       Methods      After K562 cells were infected by Ad-pre-microRNA-193b virus

the expression of miR-193b was detected by real-time PCR. The expression of bcr/abl at mRNA and protein levels was detected by qRT-PCR and Western blotting. Cell proliferation was measured by CCK-8 assay

and cell apoptosis was tested by flow cytometry.       Results      Compared with control cells

the level of microRNA-193b was significantly up-regulated in K562 cells after Ad-pre-microRNA-193b infection. The expression of bcr/abl was significantly decreased

and BCR/ABL fusion protein was decreased too. The virus infection resulted in significant inhibition in cell proliferation and obvious improvement in apoptotic rate (both P0.05).        Conclusion      miR-193b down-regulates the expression of bcr/abl and inhibits the biological effects of K562 cells. The over-expression of miR-193b may be an effective target in the treatment of chronic myelogenous leukemia.