Curcumin Enhance the Sensitivity of Imatinib by Decreasing MicroRNA-21 Expression in K562/IM Cells

OBJECTIVE To investigate the reversal effect of curcumin on drug resistance in imatinib-resistant K562 (K562/IM) cells and explore the possible mechanism. METHODS The K562/IM cells were treated with curcumin at non-toxicity concentration alone or combined with imatinib, respectively. Cell viability was measured by MTT assays. The apoptosis of cells were detected by Annexin V/PI method. The expression of microRNA-21 was measured by fluorescence quantitative polymerase chain reaction. Bcl-2 protein level was measured by Western blot. After transfected with microRNA-21 mimic and inhibitor, the sensitivity of imatinib and Bcl-2 protein level on K562/IM cell were analyzed. RESULTS Curcumin at non-toxicity concentration (25 μmol·L^-1) could significantly enhance the sensitivity of K562/IM cells to imatinib and promoted the imatinib-induced cell apoptosis. The apoptosis rate of K562/IM cells were increased from 6.3% to 23.6% after the combined use of curcumin and imatinib (P<0.05). Levels of microRNA-21 and Bcl-2 were significantly decreased after curcumin treatment. Meanwhile, after transfected with microRNA-21 inhibitor, a significant down-regulation of Bcl-2 protein and a significant up-regulation of sensitivity to imatinib were noted on K562/IM cells. CONCLUSION Curcumin could significantly enhance the sensitivity of K562/IM cells to imatinib and induce the cell apoptosis, these effects may be attribute to the down-regulation effect of curcumin on microRNA-21 and Bcl-2 expression.