The Study On The Reversal Effects Of Pulsed Magnetic Fields On The Multidrug Resistant Cell Line K562/ADR

Drug resistance of the leukemic cell leads to the failure of chemotherapy during treating leukemia. These tumor cells could resist antineoplastic drugs with different structures and mechanisms, which is termed multidrug resistance (MDR) .So how to reverse the multidrug resistance of leukemia become an important research in the therapy of leukemia.PMF has its potency, but the study is very young, and just restrict at study of the effects of PMF on cells .So the study is broad outlook. In the research, we used K562 cell line as study model, to investigate the effects and mechanisms of PMF on reversal MDR of K562/ADR cell.K-562 is a human chronic myeloid leukemic cell line which is built by Lozzio CB etc in 1957, the key features of the cell lines is the Philadelphia chromosome(ph). It has been used as a model in experiments of high undifferentiated chronic myeloid leukemia. In our assay, the human leukemic wild-type K562 (K562/S) and resistance cell Lines (K562/ADR) was obtained from Institute of hematonosis Chinese Academy of Medical Sciences.The assay includes two parts:1 The reversing effects of PMF on K562/ADR.2 The mechanism of PMF reversing K562/ADR's multidrug resistance (MDR)objective: To investigate the reversal effects and mechanisms of pulsed magnetic fields(PMF) on the drug resistant cell line K562/ADR in vitro. Methods: MTT assay was used to determine the IC₅₀ of ADR on K562/S and K562/ ADR cell lines, the detriment of PMF on K562/ADR cell line , and the reversal effects of the drug resistance after the different frequencies of PMF treatment. Using RT-PCR and agarose gel electrophoresis to detect the differences of MDR1 gene expressions in K562/S, K562/ADR and K562/ADR exposed to PMF. Finally ,flow cytometry (FCM) was applied to assess the intracellular concentration of ADR. Results: The multiples frequencies of PMF produced the different effects on the IC₅₀ of ADR on K562/ ADR cell line. In the same conditions,70Hz PMF could produce the most significant effect. MDR1 is highly expressed in K562/ADR, but not expressed in K562/S.when K562/ADR exposed to PMF, the quantity of gene expression is reduced obviously. The result of FCM essay was that 70Hz PMF could increase the intracellular concentration of ADR. Conclusion: PMF can reverse the multidrug resistance of K562/ADR by reducing MDR1 gene expression and enhancing the concentration of drug in K562/ADR cells. The reversal effects of PMF on multidrug resistance K562/ADR cells was related to the frequency of PMF. The reversal effect of low frequency PMF was better than the high frequency PMF.