ABSTRACT
BACKGROUND:Leukemia cells can obtain drug resistance phenotype mediated by adhesion to bone marrow stromal cells. But, for chronic myelogenous leukemia with adhesion functional defects, the role and mechanism of bone marrow stromal cells in imatinib-resistant formation remain unclear. OBJECTIVE:To construct the co-cultured model of bone marrow stromal cells-K562 cells and to investigate the influences of the co-culture with bone marrow stromal cells from the patients with chronic myelogenous leukemia on imatinib sensitivity of K562 cells and cellcycle. METHODS:The co-culture model was constructed by co-culturing K562 cells with bone marrow stromal cells isolated and cultured from the patients with chronic myelogenous leukemia. The IC50 values of K562 cells exposed to imatinib were quantified by MTT assay. The apoptotic rates of K562 cells exposed to 0.5μmol/L imatinib for 72 hours were detected by flow cytometry through Annexin V-FIT/PI labeling. The cellcycles, cellcycle protein (cyclin A, cyclin D1 and cyclin E) expression of K562 cells co-cultured with bone marrow stromal cells for 72 hours were analyzed by flow cytometry.RESULTS AND CONCLUSION:The IC50 values of co-culture group and suspension culture group were respectively (0.52±0.02)μmol/L and (1.27±0.05)μmol/L, and their comparison showed significant differences (P<0.01). After 72 hours of treatment with 0.5μmol/L imatinib, the apoptotic rates in the co-culture group and suspension culture group were respectively (15.48±4.17)%and (32.01±6.83)%, and their comparison showed significant differences (P<0.01). The percentages of G0-G1 phase of K562 cells co-cultured with bone marrow stromal cells for 72 hours were (48.81±8.27)%, which were significantly higher than the suspension culture group (25.78±3.26%) (P<0.01). The co-culture with bone marrow stromal cells from the patients with chronic myelogenous leukemia could mediate K562 cells resistance to imatinib. The mechanism was possibly related with G0/G1 arrest of K562 cells induced by co-culture with bone marrow stromal cells.
ABSTRACT
Objective To investigate the effects of adhesion mediated by bone nlalTow stroma celh from leukemia patient on chemotherapeutics sensitivity and cell cycle of Jurkat cells in the co-cultured model.Methods Bone mw stroma cells were isohted and cultured from leukemia patients routinely.To construct the co-cultured model.Jurkat cells were co-cultured with BMSCs the irradiated layer by 60Co,and the model was observed with scanning electron microscope.The IC50 values of Jurkat cells expesured to DNR were quantified by MTT.The cell cycles of Jurkat cells after 24h-adhesion in the co-cultured model were analyzed by Facs.The expression of cyclin A,cyclin E and p27 in Jurkat cells adhered to BMSCs for 4h.24h and 48h were detected by Western blot.Results Jurkat ceUs in the co-cultured model showed a decreased sensitivity to DNR.ICSO values for normal BMSCs,leukemic BMSCs and non-adhered control were of 1.78Ixmol/L,2.30pznol/L and 0.45p,mol/L,respectively.The percentages of Go-Gl phase for leukemic BMSCs group and non-adhered control group were of 48.74％±8.77％and 27.83％壬1.86％.Respectively.The percentages of Gz-M phase for leukemic BMSCs group and non-adhered control group were of2.01％±1.17％and 20.33％±1.84％。Respectively.Compared with eomrol group,the 24h-ad- hesion mediated by BMSCs from leukemia patients up-regulated the percentage of Go-G1 phase of Jurkat cells(P<O.01),but down-regula-ted the percentage of G2-M phase(P<O.01).The expression of cyclin A and cyclin E in Jurkat ceUs was up-regulated when adhered to BMSCs for four hours and the higher expression emerged after adhering for 24h and 48h.Oppositely,the expression of p27 were down-regulated.Especially after 48h-adhesion.Conclusions Drug resistance of leukemia cells csn be mediated by adhering to bone marrow stroma cells,which may be related to the changes of cell cycle.