Kaempferol in reversing drug resistance of chronic myelogenous leukemia K562/ADM cells and its related mechanism

Objective To investigate the drug resistance of kaempferol reversed adriamycin (ADM)-resistant K562/ADM cells in chronic myelogenous leukemia (CML) and its related mechanism. Methods Methyl thiazolyl tetrazolium (MTT) method was used to detect the toxicity of ADM on K562 and K562/ADM cells for 24 h. The half inhibitory concentration (IC50) of ADM and the drug resistance multiple for 24 h were calculated. MTT method was used to detect the toxicity of kaempferol on K562/ADM cells for 24 h. The 5% inhibitory concentration (IC5) and 10% inhibitory concentration (IC10) of kaempferol for 24 h were calculated to determine the concentration of kaempferol in the subsequent experiments. And the cells untreated by the kaempferol were selected as the control group. The cell inhibition after the treatment of ADM for 24 h of the blank control group and kaempferol intervention group was detected by using MTT method. And then the cell inhibition for 24 h and ADM IC50 for 24 h in the above groups were calculated. The ratio of IC50 in the blank control group and kaempferol group was the reversal drug resistance multiple of kaempferol. The fluorescence intensity of ADM in K562/ADM cells treated by kaempferol was detected by using flow cytometry. Western blotting was used to detect the expressions of P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), phosphorylated p38 (p-p38), and total p38 (t-p38) protein in K562/ADM cells after the treatment of kaempferol, the specific inhibitor of p38-MAPK signaling pathway SB202190, and the combination of kaempferol and SB202190. Results After the treatment of ADM for 24 h, the IC50 value of K562 and K562/ADM cells was (0.9±0.6), (28.1 ±3.5) μg/ml, respectively. The drug resistance multiple of K562/ADM cells on the treatment of ADM for 24 h was 31.16 compared with the K562 cells. MTT method showed that kaempferol inhibited the proliferation of K562/ADM cells in a dose-dependent manner. According to the IC5 and IC10, 0.5 μmol/L and 1.0 μmol/L kaempferol were determined to do the subsequent experiments. After the combined interaction of kaempferol and ADM for 24 h, the ADM IC50 of K562/ADM cells in the blank control group, 0.5 μmol/L kaempferol group and 1.0 μmol/L kaempferol group was (33.7±5.7), (21.4±0.6), (15.9±1.8) μg/ml, respectively (F = 30.85, P 0.05); SB202190 could reduce the relative expressions of P-gp, MRP1 and p-p38 protein (all P 0.05). Conclusions Kaempferol can decrease the relative expressions of P-gp and MRP1 in K562/ADM cells by inhibiting p38-MAPK pathway, so as to increase the concentrations of ADM and to reverse the drug resistance of K562/ADM cells. Key words: Leukemia, myelogenous, chronic; Drug resistance, neoplasm; Kaempferol; Doxorubicin; P-glycoprotein; Multidrug resistance-associated protein 1; p38; MAP kinase; K562/ADM cells