Reversal of chemoresistance with small interference RNA (siRNA) in etoposide resistant acute myeloid leukemia cells (HL-60)

• The ABCB1 mRNA expression levels in etoposide-resistant HL-60 cells are elevated compared to parental HL-60 cells.
• Knockdown of ABCB1 mRNA gene by siRNA results in decrease in both ABCB1 mRNA and protein levels.
• Suppression of ABCB1 mRNA expression in resistant HL-60 cells, caused a decrease in the cytotoxic index (IC50 etoposide value) from 2.41 μM to 0.98 μM and enhanced etoposide-induced apoptosis.

BackgroundOverexpression of ATP-binding cassette (ABC) drug transporters is a major barrier in the success of cancer chemotherapy. One way to overcome overexpression of ABC drug transporter-mediated chemoresistance in acute myeloid leukemia is to suppress ABC drug transporter genes expression by small interference RNA (siRNA). In this study was assessed the involvement of ABCB1 gene in the mechanisms of resistance to etoposide in AML cells. Methods: The etoposide-resistant HL-60 cells were generated by stepwise exposure increasing concentrations of etoposide. The etoposide-resistant HL-60 cells were transfected with siRNAs using Transfection Reagent. The ABCB1 mRNA expression were assessed by real-time quantitative PCR. The MDR1/P-gp levels were measured by Western blotting. The sensitivity of resistant HL-60 cells to etoposide after transfection was determined using MTT assay. Apoptosis of resistant HL-60 cells after transfection was detected by flow cytometer.ResultsIt was found that siRNA effectively inhibited ABCB1 expression at both mRNA and protein levels. Knockdown of the ABCB1 gene correlated with increased sensitivity of the resistant HL-60 cells to etoposide and was observed to lower the cytotoxic index (IC50 etoposide value) after transfection.ConclusionsOur results indicate that product of the ABCB1 gene have effective role in resistance to etoposide in acute myeloid leukemia cells.