Study on the roles of SDF-1/CXCR4 axis in imatinib resistance of K562 cells co-cultured with the bone marrow stromal cells / 中国医师杂志

ABSTRACT

Objective To investigate influences of co-culture with the bone marrow stromal cells (BMSCs) on imatinib sensitivity,and the role of stromal cell-derived factor-1 (SDF-1)/chemokine receptor 4 (CXCR4) axis in imatinib resistance of K562 cells in the co-culture model.Methods The model was constructed by co-culturing K562 cells with BMSCs isolated and cultured from the patients with chronic myeloid leukemia.The apoptosis rate and the CXCR4 expressing rate of the K562 cells exposed to 0.5 μmol/L imatinib for 72 hours were detected by fluorescent-activated cell scanning (FACS) machine.The K562 cells were exposed to 0.5 μmol/L imatinib for 4 hours,and labelled by calckin-AM fluorescent labeling sytem.The adhesion rate of the K562 cells co-cultured with BMSCs for 24 hours was calculated with fluorescence intensity.The IC50 value of K562 cells exposed to imatinib was detected by methyl thiazolyl tetrazolium (MTT) assay while the SDF-1/CXCR4 axis was blocked by 10 μg/ml monoclonal antibody of CXCR4.Results The apoptosis rate of K562 cells exposed to 0.5 μmol/L imatinib for 72 hours in co-culture group and suspension culture group was (15.48 ±4.17) ％ and (32.01 ±6.83) ％,respectively.The apoptosis rates of K562 cells in the two groups were significantly different (t =5.587,P =0.001).For the co-culture group,the CXCR4 expressing rates of K562 cells unexposed and exposed to 0.5 μmol/L imatinib for 72 hours were (20.31 ± 3.76) ％ (suspension cultured11.28％ ± 3.44％) and (53.64 ± 5.35) ％ (suspension cultured25.34％ ± 3.21％),respectively.Those results showed that co-culture with BMSCs and exposure to imatinib induced the K562 cells to express CXCR4.The adhesion rates of the K562 cells to the BMSCs were elevated from (42.18 ± 6.17) ％ to (68.97 ± 11.08) ％ when the K562 cells were exposed to 0.5 μmol/L imatinib for 4 hours.The IC50 values of block group (the SDF-1/CXCR4 axis was blocked by 10 μg/ml monoclonal antibody of CXCR4) and unblock group were (0.68 ± 0.04) μmol/L and (1.27 ± 0.05) μmol/L,respectively.The IC50 values of two groups were significantly different(t =4.869,P =0.001).Conclusions The K562 cells co-cultured with the BMSCs from the patients with chronic myeloid leukemia can obtain resistance to imatinib,which was related with that co-culture with the BMSCs and exposure to imatinib can induce the K562 cells to express CXCR4.To a certain extent,the imatinib resistance mediated by co-culture with BMSCs can be reversed by monoclonal antibody of CXCR4.