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

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 cultured:11.28％ ± 3.44％) and (53.64 ± 5.35) ％ (suspension cultured:25.34％ ± 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.

Adherence to treatment with imatinib in chronic myeloid leukemia: a study of the first decade of responses obtained at a Brazilian hospital

Objetive: The aim of this study was to identify the reasons for failure in adherence to imatinib mesylate treatment in chronic myeloid leukemia. Methods: A retrospective review was performed of 100 non-electronic records of patients with Ph+ chronic myeloid leukemia treated with imatinib mesylate. The study period was from January 2001 to January2011. Data were analyzed by Chi-Square and Correspondence analysis using the Statistical Analysis System software package. Results: At the beginning of treatment 41% of patients were in advanced stages of the disease. The unavailability of the drug (44.8%) and myelotoxicity (25.7%) were the most frequent reasons for interruption. The adherence rate was < 90% in 47% of the cases. The low adherence influenced the cytogenetic response (p-value = 0.020) and molecular response (p-value = 0.001). Very high adherence (> 95%) induced complete cytogenetic response, major cytogenetic response and major molecular response. Conclusion: The population of this study obtained lower-than-expected therapeutic responses compared to other studies. .

Chronic myeloid leukemia: an overview of the determinants of effectiveness and therapeutic response in the first decade of treatment with imatinib mesylate in a Brazilian hospital

Background: In the last decade, there has been a revolution in chronic myeloid leukemia treatment with the introduction of tyrosine kinase inhibitors with imatinib mesylate becoming the frontline therapy. Objective: To evaluate the therapeutic efficacy of imatinib mesylate in treating chronic myeloid leukemia patients and to identify factors related to therapeutic efficacy. Methods: This retrospective study was based on information obtained from patients'records in the Hematology Service of Hospital Universitário Walter Cantídio of the Universidade Federal do Ceará (HUWC / UFC). All patients diagnosed with chronic myeloid leukemia that took imatinib mesylate for a minimum of 12 months in the period from January 2001 to January 2011 were included. From a population of 160 patients, 100 were eligible for analysis. Results: The study population consisted of 100 patients who were mostly male (51%) with ages rangingbetween 21 and 40 years (42%), from the countryside (59%), in the chronic phase (95%), with high-riskprognostic factors (40%); the prognosis of high risk was not associated with complete hematologic responseor complete cytogenetic response, but correlated to complete molecular response or major molecularresponse. Reticulin condensation was associated with complete hematologic response and completecytogenetic response. It was found that 53% of patients had greater than 90% adherence to treatment. Thehigh adherence was correlated to attaining complete cytogenetic response in less than 12 months. Moreover,20% of patients had good response. Conclusion: Significant changes are indispensable in the monitoring of patients with chronic myeloid leukemia. Thus, the multidisciplinary team is important as it provides access to the full treatment and not just to medications. .