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

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

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • ATP Binding Cassette Transporter, Subfamily G, Member 2
  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / 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*
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / genetics
  • MicroRNAs / antagonists & inhibitors
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • Piperazines / administration & dosage*
  • Pyrimidines / administration & dosage*

Substances

  • 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