OBJECTIVETo construct two recombinant plasmids of mdr1 and mcl1 shRNA, and to investigate their reversal effect on drug resistance in K562 adriamycin resistant cell lines (K562/A02).

METHODSTwo oligonucleotides of mdr1 and mcl1 gene were designed referring to that of GenBank, double-stranded DNA was derived through annealing, and cloned into pRNAT vector digested by two restricted endoenzymes. K562/A02 cells were transfected with the recombinant plasmids. The mdr1 mRNA expression and its protein product P-glycoprotein (P-gp) were detected by RT-PCR and flow cytometry. The expression of mcl1 gene was detected by RT-PCR. 50% inhibition concentration (IC50) of adriamycin (ADM) on K562/A02 cells was determined by MTT method. Cells apoptosis was analyzed by flow cytometry.

RESULTSComparing with K562/A02 cells, the shRNA of mdrl or mcl1 gene in vitro can remarkably increase the sensitivity of K562/A02 to adriamycin, down-regulate mdr1 or mcl1 gene expression, increase the K562/A02 cells apoptosis rates induced by adriamycin. Cotransfection of mdrl and mcl1 genes shRNA can also down-regulate the expression of their gene, more remarkably increase the sensitivity and apoptosis of K562/ A02 to adriamycin.

CONCLUSIONTransfection of mdrl or mcl1 gene shRNA can promote the sensitivity of K562/A02 to adriamycin and cotransfection of the two shRNA can more remarkably do so. The mel1 gene might be involved in adriamycin resistant in K562/A02 cells.