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

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 µmol/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.

• Authors: Eleonora Turrini, Sierk Haenisch, Sandra Laechelt, Tobias Diewock, Oliver Bruhn, Ingolf Cascorbi
• Journal: Pharmacogenetics and genomics (Pharmacogenet Genomics) Vol. 22 Issue 3 Pg. 198-205 (Mar 2012) ISSN: 1744-6880 [Electronic] United States
• PMID: 22241070 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ABCB1 protein, human
• ABCG2 protein, human
• ATP Binding Cassette Transporter, Subfamily B
• ATP Binding Cassette Transporter, Subfamily B, Member 1
• ATP Binding Cassette Transporter, Subfamily G, Member 2
• ATP-Binding Cassette Transporters
• Benzamides
• MIRN212 microRNA, human
• MIRN328 microRNA, human
• MicroRNAs
• Neoplasm Proteins
• Piperazines
• Pyrimidines
• Imatinib Mesylate

Topics

• ATP Binding Cassette Transporter, Subfamily B
• ATP Binding Cassette Transporter, Subfamily B, Member 1 (genetics, metabolism)
• ATP Binding Cassette Transporter, Subfamily G, Member 2
• ATP-Binding Cassette Transporters (genetics, metabolism)
• Benzamides
• Cell Line, Tumor
• Dose-Response Relationship, Drug
• Drug Resistance, Neoplasm (genetics)
• Gene Expression Regulation, Leukemic (drug effects)
• Humans
• Imatinib Mesylate
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive (drug therapy, genetics)
• MicroRNAs (antagonists & inhibitors, genetics, metabolism)
• Neoplasm Proteins (genetics, metabolism)
• Piperazines (administration & dosage)
• Pyrimidines (administration & dosage)