[Reversal of multidrug resistance by MDR1 shRNA expression vector in human leukemia K562/A02 cells]

Abstract

Objective: To construct a short hairpin RNA (shRNA) eukaryotic expression vector specific to MDR1 gene in multidrug resistance (MDR) human leukemia cell line K562/A02 to observe its silencing effect on MDR1 and P-glycprotein (P-gp) expression.

Methods: The shRNA expression vector was constructed by gene recombination, then transfected into the cultured K562/A02 cells. The transcription of MDR1 gene was detected by semi-quantitative RT-PCR and the expression level of P-gp was determined by Western blot. 50% inhibition concentration (IC50) of ADM in K562/A02 cells was determined by MTT method. The intracellular doxorubicin (ADM) concentration was determined by HPLC.

Results: The introduction of pEGFP-C1/U6/MDR1-A or pEGFP-C1/U6/MDR1-B expression vector was shown to efficiently and specifically inhibit the expression of P-gp according to results of Western blot, with an inhibitory rate of 50.67%. Semi-quantitative RT-PCR showed that mRNA transcription of MDR1 gene was reduced by (48.2 +/- 2.5)%. On the contrast, the control plasmid did not exhibit inhibitory effect on the protein expression and mRNA transcription of MDR1. The relative efficiency of K562/A02 to ADM was 40.8% or 62.4%, respectively, and the intracellular accumulation of ADM increased after shRNA treatment.

Conclusion: The shRNA expression vector targeting MDR1 gene showed dramatic inhibition on RNA transcription and protein expression. It could effectively restore the sensitivity of K562/A02 cells to conventional chemotherapeutic agents.