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Pharmacogenet Genomics. 2012 Mar;22(3):198-205. doi: 10.1097/FPC.0b013e328350012b.

MicroRNA profiling in K-562 cells under imatinib treatment: influence of miR-212 and miR-328 on ABCG2 expression.

Author information

1
Institute of Experimental and Clinical Pharmacology, University of Kiel, Kiel, Germany.

Abstract

BACKGROUND:

Despite the enormous success of imatinib in chronic myeloid leukemia (CML), therapy resistance has emerged in a significant proportion of patients, partly because of the overexpression of ABC efflux transporters.

METHODS:

Using an array comprising 667 miRNAs, we investigated whether the expression of microRNAs (miRNAs) is altered in CML K-562 cells becoming resistant to increasing concentrations of imatinib. ABCB1 and ABCG2 mRNA (quantitative real-time PCR) and protein expression (western blot) were quantified under short-term and 4 months' imatinib treatment. Interaction of miR-212 and miR-328 with ABCG2 was investigated by transfection experiments and reporter gene assays using respective miRNA precursors or miRNA inhibitors.

RESULTS:

Although ABCB1 protein was not expressed, ABCG2 protein was 7.2-fold elevated after long-term treatment with 0.3 ┬Ámol/l imatinib and decreased gradually at higher concentrations. miRNAs miR-212 and miR-328 were identified to correlate inversely with ABCG2 expression under these conditions. Short-term treatment also induced ABCG2 protein concentration dependently and caused a downregulation of miR-212, but not of miR-328 at all tested concentrations (P=0.050). Reporter gene assays confirmed miR-212 to target the 3'-UTR region of ABCG2. In contrast, transfection of anti-miR-212 revealed an upregulation of ABCG2 protein expression, whereas the effect of anti-miR-328 was weak.

CONCLUSION:

Our study suggests an association of imatinib treatment, miRNA downregulation and ABCG2 overexpression, possibly contributing to the mechanisms involved in imatinib distribution and response in CML therapy.

PMID:
22241070
DOI:
10.1097/FPC.0b013e328350012b
[Indexed for MEDLINE]

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