Reversal of multi-drug resistance in K562/A02 cells by two short hairpin RNAs(shRNA) of mdr1 and mcll genes

Objective To construct two recombinant plasmids of mdrl and mell shRNA,and to in- vestigate their reversal effect on drug resistance in K562 adriamycin resistant cell lines(K562/A02).Meth- ods Two oligonucleotides of mdrl and mell gene were designed referring to that of GenBank,double-stran- ded DNA was derived through annealing,and cloned into pRNAT vector digested by two restricted endoen- zymes.K562/A02 cells were transfected with the recombinant plasmids.The mdrl mRNA expression and its protein product P-glycoprotein(P-gp)were detected by RT-PCR and flow cytometry.The expression of mell gene was detected by RT-PCR.50% inhibition concentration(IC_(50))of adriamycin(ADM)on K562/A02 cells was determined by MTT method.Cells apoptosis was analyzed by flow cytometry.Results Comparing with K562/A02 cells,the shRNA of mdrl or mell gene in vitro can remarkably increase the sensitivity of K562/A02 to adriamycin,down-regulate mdrl or mell gene expression,increase the K562/A02 cells apopto- sis rates induced by adriamycin.Cotransfection of mdrl and mell genes shRNA can also down-regulate the expression of their gene,more remarkably increase the sensitivity and apoptosis of K562/A02 to adriamycin. Conclusion Transfection of mdrl or mell gene shRNA can promote the sensitivity of K562/A02 to adriamy- cin and cotransfection of the two shRNA can more remarkably do so.The mell gene might be involved in adri- amycin resistant in K562/A02 cells.