Ethacrynic Acid Exhibits Selective Toxicity to Chronic Lymphocytic Leukemia Cells by Inhibition of the Wnt/beta-catenin Pathway

PLoS One. 2009 Dec 14;4(12):e8294. doi: 10.1371/journal.pone.0008294.

Abstract

Background: Aberrant activation of Wnt/beta-catenin signaling promotes the development of several cancers. It has been demonstrated that the Wnt signaling pathway is activated in chronic lymphocytic leukemia (CLL) cells, and that uncontrolled Wnt/beta-catenin signaling may contribute to the defect in apoptosis that characterizes this malignancy. Thus, the Wnt signaling pathway is an attractive candidate for developing targeted therapies for CLL.

Methodology/principal findings: The diuretic agent ethacrynic acid (EA) was identified as a Wnt inhibitor using a cell-based Wnt reporter assay. In vitro assays further confirmed the inhibitory effect of EA on Wnt/beta-catenin signaling. Cell viability assays showed that EA selectively induced cell death in primary CLL cells. Exposure of CLL cells to EA decreased the expression of Wnt/beta-catenin target genes, including LEF-1, cyclin D1 and fibronectin. Immune co-precipitation experiments demonstrated that EA could directly bind to LEF-1 protein and destabilize the LEF-1/beta-catenin complex. N-acetyl-L-cysteine (NAC), which can react with the alpha, beta-unsaturated ketone in EA, but not other anti-oxidants, prevented the drug's inhibition of Wnt/beta-catenin activation and its ability to induce apoptosis in CLL cells.

Conclusions/significance: Our studies indicate that EA selectively suppresses CLL survival due to inhibition of Wnt/beta-catenin signaling. Antagonizing Wnt signaling in CLL with EA or related drugs may represent an effective treatment of this disease.

Publication types

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

MeSH terms

  • Acetylcysteine / pharmacology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cyclin D1 / genetics
  • Cyclin D1 / metabolism
  • Drug Screening Assays, Antitumor
  • Ethacrynic Acid / toxicity*
  • Fibronectins / genetics
  • Fibronectins / metabolism
  • Frizzled Receptors / genetics
  • Frizzled Receptors / metabolism
  • Gene Expression Regulation, Leukemic / drug effects
  • Humans
  • Leukemia, Lymphocytic, Chronic, B-Cell / genetics
  • Leukemia, Lymphocytic, Chronic, B-Cell / metabolism*
  • Leukemia, Lymphocytic, Chronic, B-Cell / pathology*
  • Lymphoid Enhancer-Binding Factor 1 / genetics
  • Lymphoid Enhancer-Binding Factor 1 / metabolism
  • Protein Binding / drug effects
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism
  • Signal Transduction / drug effects*
  • Wnt Proteins / metabolism*
  • beta Catenin / metabolism*

Substances

  • FZD5 protein, human
  • Fibronectins
  • Frizzled Receptors
  • LEF1 protein, human
  • Lymphoid Enhancer-Binding Factor 1
  • Receptors, G-Protein-Coupled
  • Wnt Proteins
  • beta Catenin
  • Cyclin D1
  • Ethacrynic Acid
  • Acetylcysteine