ABSTRACT
In many instances, multidrug resistance (MDR) is mediated by increasing the expression at the cell surface of the MDR1 gene product, P-glycoprotein (P-gp), a 170-kD energy-dependent efflux pump. The aim of this study was to investigate the potential benefit of combination therapy with magnetic Fe(3)O(4) nanoparticle [MNP (Fe(3)O(4))] and MDR1 shRNA expression vector in K562/A02 cells. For stable reversal of "classical" MDR by short hairpin RNA (shRNA) aiming directly at the target sequence (3491-3509, 1539-1557, and 3103-3121 nucleotide) of MDR1 mRNA. PGC silencer-U6-neo-GFP-shRNA/MDR1 called PGY1-1, PGY1-2, and PGY1-3 were constructed and transfected into K562/A02 cells by lipofectamine 2000. After transfected and incubated with or without MNP (Fe(3)O(4)) for 48 hours, the transcription of MDR1 mRNA and the expression of P-gp were detected by quantitative real-time PCR and Western-blot assay respectively. Meanwhile intracellular concentration of DNR in K562/A02 cells was detected by flow cytometry (FCM). PGC silencer-U6-neo-GFP-shRNA/MDR1 was successfully constructed, which was confirmed by sequencing and PGY1-2 had the greatest MDR1 gene inhibitory ratio. Analysis of the reversal ratio of MDR, the concentration of daunorubicin (DNR) and the transcription of MDR1 gene and expression of P-gp in K562/A02 showed that combination of DNR with either MNP (Fe(3)O(4)) or PGY1-2 exerted a potent cytotoxic effect on K562/A02 cells, while combination of MNP (Fe(3)O(4)) and PGY1-2 could synergistically reverse multidrug resistance. Thus our in vitro data strongly suggested that a combination of MNP (Fe(3)O(4)) and shRNA expression vector might be a more sufficient and less toxic anti-MDR method on leukemia.
Subject(s)
Daunorubicin/administration & dosage , Drug Resistance, Multiple/drug effects , Drug Resistance, Multiple/genetics , Drug Resistance, Neoplasm/drug effects , Drug Resistance, Neoplasm/genetics , Genes, MDR , Magnetite Nanoparticles/administration & dosage , RNA, Small Interfering/administration & dosage , RNA, Small Interfering/genetics , ATP Binding Cassette Transporter, Subfamily B , ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , Antibiotics, Antineoplastic/administration & dosage , Base Sequence , DNA Primers/genetics , Doxorubicin/administration & dosage , Genetic Vectors , Humans , K562 Cells , Molecular Sequence Data , Nanomedicine , TransfectionABSTRACT
This study was purposed to construct and identify the short hairpin RNA (shRNA) eukaryotic expression vector for targeting gene mdr-1 which may play an important role in K562/A02. Short hairpin RNA (shRNA) aiming at the target sequence was to synthesized, the 3491-3509, 1539-1557and 3103-3121 nucleotide of mdr-1 mRNA were selected as targets. The selected nucleotides were cloned in the plasmid pGCSilencer-U6-neo-GFP respectively, and the resultant recombinant plasmids were named as pGY1-1, pGY1-2 and pGY1-3. The sequences of the recombinant plasmids were identified by DNA sequencing and PCR electrophoresis. The recombinant plasmids were transfected into the cell line K562/A02 by lipofection. After being transfected for 48 hours, the inhibition of mdr-1 mRNA was detected by real time-PCR, and P-gp expression was detected by Western blot. The results showed that the specific oligonucleotide was cloned into the vector successfully, and the expression of mdr-1 mRNA and P-gp in K562/A02 cells was reduced after transfecting the recombinant plasmid, as compared to the control group. It is concluded that the shRNA eukaryotic expression vector has been successfully established which can inhibit the expression of mdr-1 mRNA, setting up the basis to futher explore the effects of mdr-1 on cell line of K562/A02.