Small molecule inhibitors of Wnt/beta-catenin/lef-1 signaling induces apoptosis in chronic lymphocytic leukemia cells in vitro and in vivo.

Abstract

BACKGROUND:

Lymphoid enhancer factor-1 (lef-1) is overexpressed in B-cell chronic lymphocytic leukemia (CLL) when compared with normal B cells and transcribes several genes implicated in the pathogenesis of CLL. We therefore hypothesize that antagonism of lef-1 might lead to killing of CLL cells. We used two small molecule inhibitors of Wnt/beta-catenin/lef-1 signaling (CGP049090 and PKF115-584) to test our hypothesis.

DESIGN AND METHODS:

Enriched CLL cells and healthy B cells were used in this study. Small interfering RNA (siRNA)-mediated knockdown of lef-1 in primary CLL cells was done using nucleofection, and 50% lethal concentration (LC(50)) of two small molecules was assessed using ATP-based cell viability assay. Apoptotic response was investigated in time course experiments with different apoptotic markers. Specificity of the small molecules was demonstrated by coimmunoprecipitation experiments for the lef-1/beta-catenin interaction. In vivo studies were done in JVM-3 subcutaneous xenograft model.

RESULTS:

Inhibition of lef-1 by siRNA leads to increased apoptosis of CLL cells and inhibited proliferation of JVM-3 cell lines. The two small molecule inhibitors (CGP049090 and PKF115-584) efficiently kill CLL cells (LC(50)<1 microM), whereas normal B cells were not significantly affected. Coimmunoprecipitation showed a selective disruption of beta-catenin/lef-1 interaction. In vivo studies exhibited tumor inhibition of 69% with CGP049090 and 57% with PKF115-584 when compared with vehicle-treated controls, and the intervention was well tolerated.

CONCLUSIONS:

We have demonstrated that targeting lef-1 is a new and selective therapeutic approach in CLL. CGP049090 or PKF115-584 may be attractive compounds for CLL and other malignancies that deserve further (pre)clinical evaluation.

• Authors: Rajesh Kumar Gandhirajan, Peter Anton Staib, Katharina Minke, Iris Gehrke, Günther Plickert, Axel Schlösser, Esther Katharina Schmitt, Michael Hallek, Karl-Anton Kreuzer
• Journal: Neoplasia (New York, N.Y.) (Neoplasia) Vol. 12 Issue 4 Pg. 326-35 (Apr 2010) ISSN: 1476-5586 [Electronic] United States
• PMID: 20360943 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• CGP049090
• Lymphoid Enhancer-Binding Factor 1
• PKF115-584
• Wnt Proteins
• beta Catenin
• Perylene

Topics

• Animals
• Antineoplastic Agents (chemistry, pharmacology)
• Apoptosis (drug effects)
• Humans
• Leukemia, Lymphocytic, Chronic, B-Cell (pathology)
• Lymphoid Enhancer-Binding Factor 1 (antagonists & inhibitors, metabolism, physiology)
• Mice
• Mice, Nude
• Molecular Weight
• Perylene (analogs & derivatives, chemistry, pharmacology)
• Signal Transduction (drug effects)
• Tumor Cells, Cultured
• Up-Regulation (drug effects)
• Wnt Proteins (antagonists & inhibitors, metabolism, physiology)
• Xenograft Model Antitumor Assays
• beta Catenin (antagonists & inhibitors, metabolism, physiology)