Reversal of P-glycoprotein-mediated multidrug resistance with small interference RNA (siRNA) in leukemia cells

Abstract

The multidrug resistance (MDR) mediated by P-glycoprotein (P-gp), the MDR1 gene product, is one of the major obstacles in leukemia treatment. The present study was designed to explore a MDR1-targeted small interfering RNA (si-MDR1) approach for reversal of P-gp-mediated MDR in the MDR human leukemia cell line k562/A02. It was found that si-MDR1 significantly inhibited MDR1 expression at both mRNA and protein levels. Depletion of MDR1 by si-MDR1 correlated with the increased sensitivity of the cells to cytotoxic agents and with the enhanced intracellular retention of daunorubicin (DNR). One base-pair mutated control (si-MDR1-Mut) lost the effect of si-MDR1 on both the degradation of mdr1 mRNA and the reduction of P-gp expression. These findings indicate that siRNA specifically and efficiently interferes with the expression of mdr1 and could be used as a molecularly defined therapeutic approach for MDR in the treatment of leukemia.

Reversal of MDR1/P-glycoprotein-mediated multidrug resistance by RNA interference

“…Transient siRNA-mediated down regulation of the MDR1/P-gp expression resulted in relatively moderate inhibition in different cell models [25][26][27][28][29][30]. Since these studies used different experimental techniques, different protocols of proliferation assays [25,[27][28][29][30] or clonogenic assays [26], to determine the extent of the MDR reversal, the efficiencies of the different transient RNAi approaches are not directly comparable.…”

“…Since these studies used different experimental techniques, different protocols of proliferation assays [25,[27][28][29][30] or clonogenic assays [26], to determine the extent of the MDR reversal, the efficiencies of the different transient RNAi approaches are not directly comparable. However, the most pronounced transient MDR reversal of nearly 90% was achieved in the pancreatic carcinoma-derived cell line EPP85-181RDB [25].…”

RNA interference and potential therapeutic applications of short interfering RNAs

“…Experiments have been conducted in cell culture systems and the findings have indicated successful modulation of the MDR phenotype using RNAi in various cell lines. [104][105][106][107] Additionally, there is intense interest in the use of combinations of apoptosisinducing agents, for example tumor necrosis factorrelated apoptosis-inducing ligand, with siRNAs that silence genes which inhibit apoptosis such as Bcl-2, FLICE-like inhibitory protein or inhibition of apoptosis proteins. 108 Another approach that has been used to augment the effects of radiation and chemotherapy in cancer cells is RNAi-mediated silencing of DNA repair factors.…”

Growth of chronic myeloid leukemia cells is inhibited by infection with Ad-SH2-HA adenovirus that disrupts Grb2-Bcr-Abl complexes

“…K562, KU812, HL60 and ECV304 cells (0.5x10 6 /ml) infected with viruses were washed three times with pBs, the cells were suspended with medium (10% FCS), and plated in a 96-microwell plate at a concentration of 1x10 5 cells/per well. the Mtt assay was performed as we have previously reported (19). Briefly, three replicate wells were used for each treated group.…”