Abstract
Interleukin-2-inducible T-cell kinase (Itk) is a member of the Btk (Bruton's tyrosine kinase) family of tyrosine kinases. Itk plays an important role in normal T-cell functions and in the pathophysiology of both autoimmune diseases and T-cell malignancies. Here, we describe the initial characterization of a selective inhibitor, 7-benzyl-1-(3-(piperidin-1-yl)propyl)-2-(4-(pyridin-4-yl)phenyl)-1H-imidazo[4,5-g]quinoxalin-6(5H)-one (CTA056), that was developed through screening a 9600-compound combinatorial solution phase library, followed by molecular modeling, and extensive structure-activity relationship studies. CTA056 exhibits the highest inhibitory effects toward Itk, followed by Btk and endothelial and epithelial tyrosine kinase. Among the 41 cancer cell lines analyzed, CTA056 selectively targets acute lymphoblastic T-cell leukemia and cutaneous T-cell lymphoma. Normal T cells are minimally affected. Incubation of Jurkat and MOLT-4 cells with CTA056 resulted in the inhibition of the phosphorylation of Itk and its effectors including PLC-γ, Akt, and extracellular signal-regulated kinase, as well as the decreased secretion of targeted genes such as interleukin-2 and interferon-γ. Jurkat cells also underwent apoptosis in a dose-dependent manner when incubated with CTA056. The potent apoptosis-inducing potential of CTA056 is reflected by the significant modulation of microRNAs involved in survival pathways and oncogenesis. The in vitro cytotoxic effect on malignant T cells is further validated in a xenograft model. The selective expression and activation of Itk in malignant T cells, as well as the specificity of CTA056 for Itk, make this molecule a potential therapeutic agent for the treatment of T-cell leukemia and lymphoma.
Footnotes
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The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
This work was supported in part by the National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases [Grant DK52659]; the National Institutes of Health National Cancer Institute [Grants CA150197, CA098116]; C-Tag Bioscience, Inc.; a U.S. Department of Defense postdoctoral training award [Grant PC080859] and Auburn Community Cancer Endowment Fund (to W.G.); and an early career award from the Howard Hughes Medical Institute, the Burroughs Wellcome Fund, and the Martin and Dorothy Spatz Charitable Foundation (to E.M.).
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
ABBREVIATIONS:
- T-ALL
- T-cell acute lymphoblastic leukemia
- Itk
- interleukin-2-inducible T-cell kinase
- Btk
- Bruton's tyrosine kinase
- Etk
- endothelial and epithelial tyrosine kinase
- miRNA
- microRNA
- PI
- propidium iodide
- DIEA
- N,N-diisopropylethylamine
- DMF
- N,N-dimethylformamide
- Pd/C
- palladium on carbon
- DMSO
- dimethyl sulfoxide
- RP-HPLC
- reversed-phase high-performance liquid chromatography
- TLC
- thin-layer chromatography
- DTT
- dithiothreitol
- CTA056
- 7-benzyl-1-(3-(piperidin-1-yl)propyl)-2-(4-(pyridin-4-yl)phenyl)-1H-imidazo[4,5-g]quinoxalin-6(5H)-one
- MTT
- 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
- IL
- interleukin
- IFN
- interferon
- PCR
- polymerase chain reaction
- ELISA
- enzyme-linked immunosorbent assay
- ANOVA
- analysis of variance.
- Received May 8, 2012.
- Accepted August 16, 2012.
- Copyright © 2012 The American Society for Pharmacology and Experimental Therapeutics
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