An Antagonist of Dishevelled Protein-Protein Interaction Suppresses -Catenin-Dependent Tumor Cell Growth

Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, United States
Cancer Research (Impact Factor: 9.33). 02/2007; 67(2):573-9. DOI: 10.1158/0008-5472.CAN-06-2726
Source: PubMed


Recent progress in the development of inhibitors of protein-protein interactions has opened the door for developing drugs that act by novel and selective mechanisms. Building on that work, we designed a small-molecule inhibitor of the Wnt signaling pathway, which is aberrantly activated across a wide range of human tumors. The compound, named FJ9, disrupts the interaction between the Frizzed-7 Wnt receptor and the PDZ domain of Dishevelled, down-regulating canonical Wnt signaling and suppressing tumor cell growth. The antitumorigenic effects of FJ9 were pronounced, including induction of apoptosis in human cancer cell lines and tumor growth inhibition in a mouse xenograft model. FJ9 is thus among the first non-peptide inhibitors to show therapeutic efficacy through disruption of PDZ protein-protein interactions.

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Available from: Jie Zheng, Apr 14, 2014
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    • "Compound number 56 is shown to inhibit PDZ1 domain of NHERF1 [51], while the compound number 58 inhibits PDZ3 domain of PSD-95 protein [52]. Remaining 11 molecules with known Ki values in cluster two, have been experimentally characterized to inhibit Dishevelled PDZ domain [24], [53], [54]. Third cluster (pink colored) consists of 39 molecules, which are peptidomimetics where modifications have been introduced at either N or C-terminal of 4-mer or 5-mer peptides. "
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    ABSTRACT: Inhibitors of PDZ-peptide interactions have important implications in a variety of biological processes including treatment of cancer and Parkinson's disease. Even though experimental studies have reported characterization of peptidomimetic inhibitors of PDZ-peptide interactions, the binding modes for most of them have not been characterized by structural studies. In this study we have attempted to understand the structural basis of the small molecule-PDZ interactions by in silico analysis of the binding modes and binding affinities of a set of 38 small molecules with known Ki or Kd values for PDZ2 and PDZ3 domains of PSD-95 protein. These two PDZ domains show differential selectivity for these compounds despite having a high degree of sequence similarity and almost identical peptide binding pockets. Optimum binding modes for these ligands for PDZ2 and PDZ3 domains were identified by using a novel combination of semi-flexible docking and explicit solvent molecular dynamics (MD) simulations. Analysis of the binding modes revealed most of the peptidomimectic ligands which had high Ki or Kd moved away from the peptide binding pocket, while ligands with high binding affinities remained in the peptide binding pocket. The differential specificities of the PDZ2 and PDZ3 domains primarily arise from differences in the conformation of the loop connecting βB and βC strands, because this loop interacts with the N-terminal chemical moieties of the ligands. We have also computed the MM/PBSA binding free energy values for these 38 compounds with both the PDZ domains from multiple 5 ns MD trajectories on each complex i.e. a total of 228 MD trajectories of 5 ns length each. Interestingly, computational binding free energies show good agreement with experimental binding free energies with a correlation coefficient of approximately 0.6. Thus our study demonstrates that combined use of docking and MD simulations can help in identification of potent inhibitors of PDZ-peptide complexes.
    Preview · Article · Aug 2013 · PLoS ONE
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    • "Inhibition of Wnt signaling has been shown to reduce tumor growth in vitro and in mouse models using a variety of approaches [25,47,53-58]. For instance, small molecules have been used to inhibit Wnt secretion or the transportation of β-catenin from the nucleus [47,55], and siRNA has been used to inhibit Wnt-2 signaling and induce apoptosis in NSCLC cells [25]. "
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    ABSTRACT: Wnt-2 plays an oncogenic role in cancer, but which Frizzled receptor(s) mediates the Wnt-2 signaling pathway in lung cancer remains unclear. We sought to (1) identify and evaluate the activation of Wnt-2 signaling through Frizzled-8 in non-small cell lung cancer, and (2) test whether a novel expression construct dominant negative Wnt-2 (dnhWnt-2) reduces tumor growth in a colony formation assay and in a xenograft mouse model. Semi-quantitative RT-PCR was used to identify the expression of Wnt-2 and Frizzled-8 in 50 lung cancer tissues from patients. The TCF reporter assay (TOP/FOP) was used to detect the activation of the Wnt canonical pathway in vitro. A novel dnhWnt-2 construct was designed and used to inhibit activation of Wnt-2 signaling through Frizzled-8 in 293T, 293, A549 and A427 cells and in a xenograft mouse model. Statistical comparisons were made using Student's t-test. Among the 50 lung cancer samples, we identified a 91% correlation between the transcriptional increase of Wnt-2 and Frizzled-8 (p<0.05). The Wnt canonical pathway was activated when both Wnt-2 and Frizzled-8 were co-expressed in 293T, 293, A549 and A427 cells. The dnhWnt-2 construct we used inhibited the activation of Wnt-2 signaling in 293T, 293, A549 and A427 cells, and reduced the colony formation of NSCLC cells when beta-catenin was present (p<0.05). Inhibition of Wnt-2 activation by the dnhWnt-2 construct further reduced the size and mass of tumors in the xenograft mouse model (p<0.05). The inhibition also decreased the expression of target genes of Wnt signaling in these tumors. We demonstrated an activation of Wnt-2 signaling via the Frizzled-8 receptor in NSCLC cells. A novel dnhWnt-2 construct significantly inhibits Wnt-2 signaling, reduces colony formation of NSCLC cells in vitro and tumor growth in a xenograft mouse model. The dnhWnt-2 construct may provide a new therapeutic avenue for targeting the Wnt pathway in lung cancer.
    Full-text · Article · Jul 2013 · BMC Cancer
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    • "High levels of β-catenin have been described to correlate with CSC tumorigenicity in colon cancer83. Several pharmaceuticals are under investigation as inhibitors of Wnt signaling84,85. Monoclonal antibodies against the Wnt cascade have been tested with promising anti-tumor activity86. "
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    ABSTRACT: Cancer stem cells (CSCs) have been identified as rare cell populations in many cancers, including leukemia and solid tumors. Accumulating evidence has suggested that CSCs are capable of self-renewal and differentiation into various types of cancer cells. Aberrant regulation of gene expression and some signaling pathways has been observed in CSCs compared to other tumor cells. CSCs are thought to be responsible for cancer initiation, progression, metastasis, recurrence and drug resistance. The CSC hypothesis has recently attracted much attention due to the potential for discovery and development of CSC-related therapies and the identification of key molecules involved in controlling the unique properties of CSC populations. Over the past several years, a tremendous amount of effort has been invested in the development of new drugs, such as nanomedicines, that can take advantage of the "Achilles' heel" of CSCs by targeting cell-surface molecular markers or various signaling pathways. Novel compounds and therapeutic strategies that selectively target CSCs have been identified, some of which have been evaluated in preclinical and clinical studies. In this article, we review new findings related to the investigation of the CSC hypothesis, and discuss the crucial pathways involved in regulating the development of CSC populations and the advances in studies of drug resistance. In addition, we review new CSC-targeted therapeutic strategies aiming to eradicate malignancies.
    Full-text · Article · May 2013 · Acta Pharmacologica Sinica
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