CGP049090 and PKF115-584 Selectively Kill CLL Cells

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Abstract Number: 5637

Presentation Title: Selective killing of B cell chronic lymphocytic

leukemia (B-CLL) cells through specific inhibition of beta-

catenin/lef-1 signaling by two small molecule compounds (CGP049090

and PKF115-584)

Author Block: Rajesh Kumar Gandhirajan, Staib, Birgit Hempsch,

Katharina Minke, Iris Gehrke, Timo Schinköthe, Guenter Plickert,

Axel Schlösser, Esther K. Schmitt, Hallek, Karl Anton

Kreuzer. University at Cologne, Cologne, Germany, Novartis Pharma

Inc., Nürnberg, Germany, Novartis Institutes for Biomedical

Research, Basel, Switzerland

Recently it has been shown that the two small molecule compounds

CGP049090 and PKF115-584 effectively inhibit & #946;-catenin/lef-1

signaling in colon carcinoma cells.

In B cell chronic lymphocytic leukemia (B-CLL) lef-1 is excessively

overexpressed while it is not or low expressed in normal tissues

including B cells.

In order to assess the potential of these compounds for CLL therapy,

MEC-1 cell line, naive B-CLL cells and normal blood leucocytes (PBL)

were treated with various concentrations of both substances. Cell

survival was assessed by ATP viability assay and Differential

Staining Cytotoxicity (DiSC) assay. Apoptosis was monitored by

caspase 3/7 assay, PARP-cleavage and DNA fragmentation.

At the protein level, known target genes of & #946;-catenin/lef-1

signaling were analyzed by immunoblotting. In order to investigate

specific disruption of & #946;-catenin/lef-1 complexation co-

immunoprecipitations were performed.

The results showed both compounds induced dose dependent apoptosis

with LC50 of 0.12µM (CGP049090), 0.49µM (PKF115-584) in MEC-1 cell

line and 0.33µM (CGP049090) and 0.23µM (PKF115-584) in primary naïve

B-CLL cells. PBL were not significantly affected as ascertained by

LC50 values of 90.92µM (CGP049090) and 39.88µM (PKF115-584).

Apoptosis was seen in CLL cells within six hours of incubation.

Immunoblotting showed diminished & #946;-catenin/lef-1 target proteins

like c-myc, survivin and cyclin D1. Moreover, by co-

immunoprecipitation effective disruption of & #946;-catenin and lef-1

could be observed upon treatment with the inhibitors.

As it has been shown earlier that CGP049090 does not lead to gross

systemic toxicity in mice it can be suggested that both compounds

are potential candidates for CLL therapy.

2007 AACR Annual Meeting

April 14-18, 2007

Los Angeles, CA

Copyright © 2007 American Association for Cancer Research. All

rights reserved.