β-Catenin is required for intrinsic but not extrinsic BCR-ABL1 kinase-independent resistance to tyrosine kinase inhibitors in chronic myeloid leukemia

Leukemia. 2015 Dec;29(12):2328-37. doi: 10.1038/leu.2015.196. Epub 2015 Jul 23.

Abstract

Activation of nuclear β-catenin and expression of its transcriptional targets promotes chronic myeloid leukemia (CML) progression, tyrosine kinase inhibitor (TKI) resistance, and leukemic stem cell self-renewal. We report that nuclear β-catenin has a role in leukemia cell-intrinsic but not -extrinsic BCR-ABL1 kinase-independent TKI resistance. Upon imatinib inhibition of BCR-ABL1 kinase activity, β-catenin expression was maintained in intrinsically resistant cells grown in suspension culture and sensitive cells cultured in direct contact (DC) with bone marrow (BM) stromal cells. Thus, TKI resistance uncouples β-catenin expression from BCR-ABL1 kinase activity. In β-catenin reporter assays, intrinsically resistant cells showed increased transcriptional activity versus parental TKI-sensitive controls, and this was associated with restored expression of β-catenin target genes. In contrast, DC with BM stromal cells promoted TKI resistance, but had little effects on Lef/Tcf reporter activity and no consistent effects on cytoplasmic β-catenin levels, arguing against a role for β-catenin in extrinsic TKI resistance. N-cadherin or H-cadherin blocking antibodies abrogated DC-based resistance despite increasing Lef/Tcf reporter activity, suggesting that factors other than β-catenin contribute to extrinsic, BM-derived TKI resistance. Our data indicate that, while nuclear β-catenin enhances survival of intrinsically TKI-resistant CML progenitors, it is not required for extrinsic resistance mediated by the BM microenvironment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cadherins / physiology
  • Cell Line, Tumor
  • Drug Resistance, Neoplasm
  • Fusion Proteins, bcr-abl / physiology*
  • Humans
  • Imatinib Mesylate / therapeutic use
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / drug therapy*
  • Protein Kinase Inhibitors / therapeutic use*
  • Protein-Tyrosine Kinases / antagonists & inhibitors*
  • Proto-Oncogene Proteins / physiology
  • Wnt Proteins / physiology
  • Wnt-5a Protein
  • beta Catenin / physiology*

Substances

  • BCR-ABL1 fusion protein, human
  • CTNNB1 protein, human
  • Cadherins
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins
  • WNT5A protein, human
  • Wnt Proteins
  • Wnt-5a Protein
  • beta Catenin
  • Imatinib Mesylate
  • Protein-Tyrosine Kinases
  • Fusion Proteins, bcr-abl