Single-cell analysis of K562 cells: an imatinib-resistant subpopulation is adherent and has upregulated expression of BCR-ABL mRNA and protein

Exp Hematol. 2014 Mar;42(3):183-191.e5. doi: 10.1016/j.exphem.2013.11.006. Epub 2013 Nov 20.

Abstract

In chronic myeloid leukemia (CML) cells from different stages of maturation may have differential expression of BCR-ABL at both messenger RNA (mRNA) and protein level. However, the significance of such differential expression to clinical disease behavior is unknown. Using the CML-derived, BCR-ABL expressing cell line, K562, distinct plastic-adherent (K562/Adh) and nonadherent (K562/NonAdh) subpopulations were established and then analyzed both as single cells and as bulk cell populations. BCR-ABL mRNA was upregulated in K562/Adh compared with K562/NonAdh cells in both single cell and bulk population analyses (p < 0.0001). Similarly, phosphorylation of BCR protein was upregulated in K562/Adh, compared with K562/NonAdh cells (63.42% vs. 23.1%; p = 0.007), and these two K562 subpopulations were found to express significantly different microRNA species. Furthermore, treatment with the BCR-ABL tyrosine kinase inhibitor, imatinib, reduced cell viability more rapidly in K562/NonAdh compared with K562/Adh cells (p < 0.005) both at single and bulk cell levels. This discovery of an adherent subpopulation of K562 cells with increased BCR-ABL mRNA, increased phosphorylated BCR protein expression, differential microRNA expression, and increased imatinib resistance suggests that a similar subpopulation of cells can also mediate clinical resistance to imatinib during treatment of patients with CML.

MeSH terms

  • Benzamides / pharmacology*
  • Cell Adhesion / drug effects
  • Cell Survival / drug effects
  • Drug Resistance, Neoplasm / drug effects*
  • Flow Cytometry
  • Fusion Proteins, bcr-abl / genetics*
  • Fusion Proteins, bcr-abl / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Imatinib Mesylate
  • In Situ Hybridization, Fluorescence
  • K562 Cells
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / genetics
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / metabolism
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / pathology
  • MicroRNAs / genetics
  • Phosphorylation / drug effects
  • Piperazines / pharmacology*
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-bcr / genetics
  • Proto-Oncogene Proteins c-bcr / metabolism
  • Pyrimidines / pharmacology*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Single-Cell Analysis / methods*
  • Up-Regulation / drug effects

Substances

  • Benzamides
  • MicroRNAs
  • Piperazines
  • Protein Kinase Inhibitors
  • Pyrimidines
  • RNA, Messenger
  • Imatinib Mesylate
  • Fusion Proteins, bcr-abl
  • BCR protein, human
  • Proto-Oncogene Proteins c-bcr