The synergistic effect of miR-203 and cytarabine on the inhibition of cell proliferation and induction of apoptosis in chronic myelogenous leukemia cells.

Cytarabine (Ara-C) is a commonly used chemotherapeutic drug for the treatment of leukemia, known for its significant tolerability. The down regulation of miR-203 in leukemia cells suggests its potential involvement in the pathogenesis of leukemia. In this study, we investigated the effects and possible mechanisms of miR-203 and Ara-C on proliferation and apoptosis of human leukemia K562 cells which were cultured with Ara-C and/or with transfection of miR-203 expression vectors. Our results showed that the combination of Ara-C and miR-203 synergistically inhibited the proliferation of K562 cells and the sensitivity of leukemia cells to Ara-C was increased by 2.5-fold with trasfection of miR-203. The proportion of apoptotic cells in the Ara-C and miR-203 combination group was higher than Ara-C or control plasmid group. Caspase-3 and caspase-9 activities were increased in Ara-C and miR-203 combination group. miR-203 down regulated the protein level of Bcr/abl in K562 cells compared with plasmid control. In conclusion, Ara-C in combination with miR-203 has a synergistic effect of proliferation inhibition and apoptosis induction in chronic myelogenous leukemia K562 cells, which may be associated with miR-203 down regulating Bcr/abl, thereby inhibiting cell proliferation and promoting cell apoptosis.