Study of establishment of K562/HHT cell line and reversal of multidrug resistance by antiprogestin drug mifepristone

AIM: To study the mechanism of multidrug resistance (MDR) of leukemia cells induced by homoharringtonine (HHT) and the reversal effect of mifepristone on MDR.METHODS: Human leukemia cell line K562 was induced into MDR cell line by intermittent administration of high dose of HHT.MTT assay was used to detect the sensitivity of these MDR cells to all sorts of chemotherapeutic agents with or without mifepristone.The cytotoxicity of mifepristone was also observed.RT-PCR was used to detect the expression of MDR1 gene and glucosylceramide synthase (GCS) gene.Flow cytometry was used to detect the expression of P-glucoprotein and the accumulative value of intracellular daunorubicin (DNR) in these MDR cells with or without mifepristone.Immunohistochemistry was used to detect the expression of Bcl-2,Bax and caspase-3 in these MDR cells with or without mifepristone.RESULTS: MDR cell line K562/HHT was acquired after induced by HHT for 2 months.This MDR cell line possessed the ability of 462.6 fold resistance to HHT and cross-resistance to adriamycin,vincristine and etoposide.The expression of MDR1 gene,GCS gene,P-glucoprotein and Bcl-2/Bax ratio in K562/HHT cells were significantly higher than those in K562 cells (P<0.05).The caspase-3 expression and the accumulative value of intracellular DNR in K562/HHT cells were significantly lower than those in K562 cells (P<0.05).10 μmol/L mifepristone reversed the resistance of K562/HHT cells to HHT,adriamycin,vincristine and etoposide at different levels.The Bcl-2/Bax ratio,caspase-3 expression and accumulative value of intracellular DNR in K562/HHT cells treated with RU486 were significantly different compared with K562/HHT cells without RU486 treatment (P<0.05).CONCLUSIONS: Leukemia cell line K562 can be induced into MDR cell line K562/HHT by HHT.P-glucoprotein,GCS,Bcl-2/Bax ratio and caspase-3 may play an important role in K562/HHT cells.Mifepristone can reverse MDR in K562/HHT cells by decreasing the accumulative value of intracellular drug and regulating the expression of Bcl-2,Bax and caspase-3.