1
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Zhang H, Liu C, Zhu D, Zhang Q, Li J. Medicinal Chemistry Strategies for the Development of Inhibitors Disrupting β-Catenin's Interactions with Its Nuclear Partners. J Med Chem 2023; 66:1-31. [PMID: 36583662 DOI: 10.1021/acs.jmedchem.2c01016] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Dysregulation of the Wnt/β-catenin signaling pathway is strongly associated with various aspects of cancer, including tumor initiation, proliferation, and metastasis as well as antitumor immunity, and presents a promising opportunity for cancer therapy. Wnt/β-catenin signaling activation increases nuclear dephosphorylated β-catenin levels, resulting in β-catenin binding to TCF and additional cotranscription factors, such as BCL9, CBP, and p300. Therefore, directly disrupting β-catenin's interactions with these nuclear partners holds promise for the effective and selective suppression of the aberrant activation of Wnt/β-catenin signaling. Herein, we summarize recent advances in biochemical techniques and medicinal chemistry strategies used to identify potent peptide-based and small-molecule inhibitors that directly disrupt β-catenin's interactions with its nuclear binding partners. We discuss the challenges involved in developing drug-like inhibitors that target the interactions of β-catenin and its nuclear binding partner into therapeutic agents.
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Affiliation(s)
- Hao Zhang
- School of Pharmacy, Fudan University, Shanghai 201203, China.,Novel Technology Center of Pharmaceutical Chemistry, Shanghai Institute of Pharmaceutical Industry Co., Ltd., China State Institute of Pharmaceutical Industry, Shanghai 201203, China
| | - Chenglong Liu
- School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Di Zhu
- School of Pharmacy, Fudan University, Shanghai 201203, China.,Department of Pharmacology, School of Basic Medical Science, Fudan University, Shanghai 201100, China
| | - Qingwei Zhang
- Novel Technology Center of Pharmaceutical Chemistry, Shanghai Institute of Pharmaceutical Industry Co., Ltd., China State Institute of Pharmaceutical Industry, Shanghai 201203, China
| | - Jianqi Li
- Novel Technology Center of Pharmaceutical Chemistry, Shanghai Institute of Pharmaceutical Industry Co., Ltd., China State Institute of Pharmaceutical Industry, Shanghai 201203, China
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2
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Yang P, Zhu Y, Zheng Q, Meng S, Wu Y, Shuai W, Sun Q, Wang G. Recent advances of β-catenin small molecule inhibitors for cancer therapy: Current development and future perspectives. Eur J Med Chem 2022; 243:114789. [DOI: 10.1016/j.ejmech.2022.114789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/17/2022] [Accepted: 09/18/2022] [Indexed: 11/28/2022]
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3
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McCoy MA, Spicer D, Wells N, Hoogewijs K, Fiedler M, Baud MGJ. Biophysical Survey of Small-Molecule β-Catenin Inhibitors: A Cautionary Tale. J Med Chem 2022; 65:7246-7261. [PMID: 35581674 PMCID: PMC9150122 DOI: 10.1021/acs.jmedchem.2c00228] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The canonical Wingless-related
integration site signaling pathway
plays a critical role in human physiology, and its dysregulation can
lead to an array of diseases. β-Catenin is a multifunctional
protein within this pathway and an attractive yet challenging therapeutic
target, most notably in oncology. This has stimulated the search for
potent small-molecule inhibitors binding directly to the β-catenin
surface to inhibit its protein–protein interactions and downstream
signaling. Here, we provide an account of the claimed (and some putative)
small-molecule ligands of β-catenin from the literature. Through
in silico analysis, we show that most of these molecules contain promiscuous
chemical substructures notorious for interfering with screening assays.
Finally, and in line with this analysis, we demonstrate using orthogonal
biophysical techniques that none of the examined small molecules bind
at the surface of β-catenin. While shedding doubts on their
reported mode of action, this study also reaffirms β-catenin
as a prominent target in drug discovery.
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Affiliation(s)
- Michael A McCoy
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Dominique Spicer
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Neil Wells
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Kurt Hoogewijs
- National University of Ireland, University Road, Galway H91 TK33, Ireland
| | - Marc Fiedler
- Medical Research Council, Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, U.K
| | - Matthias G J Baud
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
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4
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Phull MS, Jadav SS, Gundla R, Mainkar PS. A perspective on medicinal chemistry approaches towards adenomatous polyposis coli and Wnt signal based colorectal cancer inhibitors. Eur J Med Chem 2021; 212:113149. [PMID: 33445154 DOI: 10.1016/j.ejmech.2020.113149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/22/2020] [Accepted: 12/28/2020] [Indexed: 12/24/2022]
Abstract
Colorectal cancer (CRC) is one of the major causes of carcinogenic mortality in numbers only after lung and breast cancers. The mutations in adenomatous polyposis coli (APC) gene leads to formation of colorectal polyps in the colonic region and which develop as a malignant tumour upon coalition with patient related risk factors. The protein-protein interaction (PPI) of APC with Asef (A Rac specific guanine nucleotide exchange factor) overwhelms the patient's conditions by rapidly spreading in the entire colorectal region. Most mutations in APC gene occur in mutated cluster region (MCR), where it specifically binds with the cytosolic β-catenin to regulate the Wnt signalling pathway required for CRC cell adhesion, invasion, progression, differentiation and stemness in initial cell cycle phages. The current broad spectrum perspective is attempted to elaborate the sources of identification, development of selective APC inhibitors by targeting emopamil-binding protein (EBP) & dehydrocholesterol reductase-7 & 24 (DHCR-7 & 24); APC-Asef, β-catenin/APC, Wnt/β-catenin, β-catenin/TCF4 PPI inhibitors with other vital Wnt signal cellular proteins and APC/Pol-β interface of colorectal cancer. In this context, this perspective would serve as a platform for design of new medicinal agents by targeting cellular essential components which could accelerate anti-colorectal potential candidates.
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Affiliation(s)
- Manjinder Singh Phull
- Department of Chemistry, School of Science, GITAM (Deemed to Be University), Hyderabad, 502329, Telangana, India
| | - Surender Singh Jadav
- Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad, 500007, Telangana, India
| | - Rambabu Gundla
- Department of Chemistry, School of Science, GITAM (Deemed to Be University), Hyderabad, 502329, Telangana, India
| | - Prathama S Mainkar
- Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad, 500007, Telangana, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, Utter Pradesh, India.
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5
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Chen Y, Fu Z, Li D, Yue Y, Liu X. Optimizations of a novel fluorescence polarization-based high-throughput screening assay for β-catenin/LEF1 interaction inhibitors. Anal Biochem 2020; 612:113966. [PMID: 32956692 DOI: 10.1016/j.ab.2020.113966] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/21/2020] [Accepted: 09/15/2020] [Indexed: 01/20/2023]
Abstract
Aberrant activation of the Wnt/β-catenin signaling pathway is prominent in the development and metastasis of non-small cell lung cancer (NSCLC). Highly effective inhibition of this pathway highlights a therapeutic avenue against NSCLC. Moreover, β-catenin/LEF1 interaction regulates β-catenin nuclear transport as well as the transcriptions of the key oncogenes in Wnt/β-catenin signaling pathway. Therefore, interruption of this interaction would be a promising therapeutic strategy for NSCLC metastasis. To date, no economical and rapid high-throughput screening (HTS) assay has been reported for the discovery of β-catenin/LEF1 interaction inhibitors. In this study, we developed a novel fluorescence polarization (FP)-based HTS assay to identify β-catenin/LEF1 interaction inhibitors. The FITC-LEF1 sequence, incubation time, temperature, and DMSO resistance were optimized, and then a high Z' factor of 0.77 was achieved. A pilot screening of a natural product library via this established FP screening assay identified sanguinarine analogues as potential β-catenin/LEF1 interaction inhibitors. GST pull-down and surface plasmon resonance (SPR) assay demonstrated that β-catenin/LEF1 interaction is a potential anticancer target of sanguinarine in vitro. This newly developed FP screening assay will be vital for the rapid discovery of novel Wnt inhibitors targeting β-catenin/LEF1 interaction.
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Affiliation(s)
- Yunyu Chen
- Institute for Drug Screening and Evaluation, Wannan Medical College, Wuhu, 241002, China
| | - Zhenghao Fu
- Institute for Drug Screening and Evaluation, Wannan Medical College, Wuhu, 241002, China
| | - Dongsheng Li
- Department of Medicinal Chemistry, Shanghai Synergy Pharmaceutical Sciences Co., Ltd., Shanghai, 201203, China
| | - Yuhuan Yue
- Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, 130122, China.
| | - Xiaoping Liu
- Institute for Drug Screening and Evaluation, Wannan Medical College, Wuhu, 241002, China.
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6
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Computational methods-guided design of modulators targeting protein-protein interactions (PPIs). Eur J Med Chem 2020; 207:112764. [PMID: 32871340 DOI: 10.1016/j.ejmech.2020.112764] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/09/2020] [Accepted: 08/16/2020] [Indexed: 12/15/2022]
Abstract
Protein-protein interactions (PPIs) play a pivotal role in extensive biological processes and are thus crucial to human health and the development of disease states. Due to their critical implications, PPIs have been spotlighted as promising drug targets of broad-spectrum therapeutic interests. However, owing to the general properties of PPIs, such as flat surfaces, featureless conformations, difficult topologies, and shallow pockets, previous attempts were faced with serious obstacles when targeting PPIs and almost portrayed them as "intractable" for decades. To date, rapid progress in computational chemistry and structural biology methods has promoted the exploitation of PPIs in drug discovery. These techniques boost their cost-effective and high-throughput traits, and enable the study of dynamic PPI interfaces. Thus, computational methods represent an alternative strategy to target "undruggable" PPI interfaces and have attracted intense pharmaceutical interest in recent years, as exemplified by the accumulating number of successful cases. In this review, we first introduce a diverse set of computational methods used to design PPI modulators. Herein, we focus on the recent progress in computational strategies and provide a comprehensive overview covering various methodologies. Importantly, a list of recently-reported successful examples is highlighted to verify the feasibility of these computational approaches. Finally, we conclude the general role of computational methods in targeting PPIs, and also discuss future perspectives on the development of such aids.
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7
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Wang Z, Zhang M, Wang J, Ji H. Optimization of Peptidomimetics as Selective Inhibitors for the β-Catenin/T-Cell Factor Protein-Protein Interaction. J Med Chem 2019; 62:3617-3635. [PMID: 30856332 DOI: 10.1021/acs.jmedchem.9b00147] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The β-catenin/T-cell factor (Tcf) protein-protein interaction (PPI) plays a critical role in the β-catenin signaling pathway which is hyperactivated in many cancers and fibroses. Based on compound 1, which was designed to target the Tcf4 G13ANDE17 binding site of β-catenin, extensive structure-activity relationship studies have been conducted. As a result, compounds 53 and 57 were found to disrupt the β-catenin/Tcf PPI with the Ki values of 0.64 and 0.44 μM, respectively, and exhibit good selectivity for β-catenin/Tcf over β-catenin/E-cadherin and β-catenin/adenomatous polyposis coli (APC) PPIs. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium (MTS) cell viability assays revealed that 56, the ethyl ester of 53, was more potent than 53 in inhibiting viability of most of the Wnt/β-catenin hyperactive cancer cells. Further cell-based studies indicated that 56 disrupted the β-catenin/Tcf PPI without affecting the β-catenin/E-cadherin and β-catenin/APC PPIs, suppressed transactivation of Wnt/β-catenin signaling in dose-dependent manners, and inhibited migration and invasiveness of Wnt/β-catenin-dependent cancer cells.
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Affiliation(s)
- Zhen Wang
- Drug Discovery Department , H. Lee Moffitt Cancer Center and Research Institute , Tampa , Florida 33612-9497 , United States
| | - Min Zhang
- Drug Discovery Department , H. Lee Moffitt Cancer Center and Research Institute , Tampa , Florida 33612-9497 , United States
| | - Jin Wang
- Drug Discovery Department , H. Lee Moffitt Cancer Center and Research Institute , Tampa , Florida 33612-9497 , United States
| | - Haitao Ji
- Drug Discovery Department , H. Lee Moffitt Cancer Center and Research Institute , Tampa , Florida 33612-9497 , United States.,Departments of Oncologic Sciences and Chemistry , University of South Florida , Tampa , Florida 33620-9497 , United States
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8
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Schneider JA, Craven TW, Kasper AC, Yun C, Haugbro M, Briggs EM, Svetlov V, Nudler E, Knaut H, Bonneau R, Garabedian MJ, Kirshenbaum K, Logan SK. Design of Peptoid-peptide Macrocycles to Inhibit the β-catenin TCF Interaction in Prostate Cancer. Nat Commun 2018; 9:4396. [PMID: 30352998 PMCID: PMC6199279 DOI: 10.1038/s41467-018-06845-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 09/21/2018] [Indexed: 12/19/2022] Open
Abstract
New chemical inhibitors of protein-protein interactions are needed to propel advances in molecular pharmacology. Peptoids are peptidomimetic oligomers with the capability to inhibit protein-protein interactions by mimicking protein secondary structure motifs. Here we report the in silico design of a macrocycle primarily composed of peptoid subunits that targets the β-catenin:TCF interaction. The β-catenin:TCF interaction plays a critical role in the Wnt signaling pathway which is over-activated in multiple cancers, including prostate cancer. Using the Rosetta suite of protein design algorithms, we evaluate how different macrocycle structures can bind a pocket on β-catenin that associates with TCF. The in silico designed macrocycles are screened in vitro using luciferase reporters to identify promising compounds. The most active macrocycle inhibits both Wnt and AR-signaling in prostate cancer cell lines, and markedly diminishes their proliferation. In vivo potential is demonstrated through a zebrafish model, in which Wnt signaling is potently inhibited.
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Affiliation(s)
- Jeffrey A Schneider
- Departments of Urology, New York University School of Medicine, New York, NY, 10016, USA
| | - Timothy W Craven
- Department of Chemistry, New York University, New York, NY, 10003, USA
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, 10003, USA
| | - Amanda C Kasper
- Department of Chemistry, New York University, New York, NY, 10003, USA
| | - Chi Yun
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Michael Haugbro
- Department of Chemistry, New York University, New York, NY, 10003, USA
| | - Erica M Briggs
- Departments of Urology, New York University School of Medicine, New York, NY, 10016, USA
- Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA
| | - Vladimir Svetlov
- Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA
- Howard Hughes Medical Institute, New York University School of Medicine, New York, NY, 10016, USA
| | - Evgeny Nudler
- Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA
- Howard Hughes Medical Institute, New York University School of Medicine, New York, NY, 10016, USA
| | - Holger Knaut
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Richard Bonneau
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, 10003, USA
| | - Michael J Garabedian
- Departments of Urology, New York University School of Medicine, New York, NY, 10016, USA
- Microbiology, New York University School of Medicine, New York, NY, 10016, USA
| | - Kent Kirshenbaum
- Department of Chemistry, New York University, New York, NY, 10003, USA.
| | - Susan K Logan
- Departments of Urology, New York University School of Medicine, New York, NY, 10016, USA.
- Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA.
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9
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Wu X, Ji H. Rhodium-Catalyzed [4 + 1] Cyclization via C-H Activation for the Synthesis of Divergent Heterocycles Bearing a Quaternary Carbon. J Org Chem 2018; 83:4650-4656. [PMID: 29608841 DOI: 10.1021/acs.joc.8b00397] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The development of an efficient approach to construct fused polycyclic systems bearing a quaternary carbon center represents a great challenge to synthetic chemistry. Herein, we report a Rh(III)-catalyzed [4 + 1] annulation of propargyl alcohols with various heterocyclic scaffolds under an air atmosphere. Diverse fused heterocycles containing a quaternary carbon center were obtained in moderate to good yields. Additionally, this method features a high atom-economy, metal oxidant free, simple operation, and compatibility with various functional groups.
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Affiliation(s)
- Xiaowei Wu
- Drug Discovery Department , H. Lee Moffitt Cancer Center and Research Institute , 12902 Magnolia Drive , Tampa , Florida 33612-9416 , United States
| | - Haitao Ji
- Drug Discovery Department , H. Lee Moffitt Cancer Center and Research Institute , 12902 Magnolia Drive , Tampa , Florida 33612-9416 , United States.,Departments of Oncologic Sciences and Chemistry , University of South Florida , Tampa , Florida 33612 , United States
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10
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Liu S, Wang J, Shao T, Song P, Kong Q, Hua H, Luo T, Jiang Y. The natural agent rhein induces β-catenin degradation and tumour growth arrest. J Cell Mol Med 2017; 22:589-599. [PMID: 29024409 PMCID: PMC5742736 DOI: 10.1111/jcmm.13346] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Accepted: 07/11/2017] [Indexed: 02/05/2023] Open
Abstract
The natural agent rhein is an ananthraquinone derivative of rhubarb, which has anticancer effects. To determine the mechanisms underlying the anticancer effects of rhein, we detected the effect of rhein on several oncoproteins. Here, we show that rhein induces β‐catenin degradation in both hepatoma cell HepG2 and cervical cancer cell Hela. Treatment of HepG2 and Hela cells with rhein shortens the half‐life of β‐catenin. The proteasome inhibitor MG132 blunts the downregulation of β‐catenin by rhein. The induction of β‐catenin degradation by rhein is dependent on GSK3 but independent of Akt. Treatment of HepG2 and Hela cells with GSK3 inhibitor or GSK3β knockdown abrogates the effect of rhein on β‐catenin. GSK3β knockdown compromises the inhibition of HepG2 and Hela cell growth by rhein. Furthermore, rhein dose not downregulate β‐catenin mutant that is deficient of phosphorylation at multiple residues including Ser33, Ser37, Thr41 and Ser45. Moreover, rhein induces cell cycle arrest at S phase in both HepG2 and Hela cells. Intraperitoneal administration of rhein suppresses tumour cells proliferation and tumour growth in HepG2 xenografts model. Finally, the levels of β‐catenin are reduced in rhein‐treated tumours. These data demonstrate that rhein can induce β‐catenin degradation and inhibit tumour growth.
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Affiliation(s)
- Shu Liu
- State Key Laboratory of Biotherapy, Section of Oncogene, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Jiao Wang
- School of Basic Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Ting Shao
- State Key Laboratory of Biotherapy, Section of Oncogene, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Peiying Song
- State Key Laboratory of Biotherapy, Section of Oncogene, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Qingbin Kong
- State Key Laboratory of Biotherapy, Section of Oncogene, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Hui Hua
- Laboratory of Stem Cell Biology, West China Hospital, Sichuan University, Chengdu, China
| | - Ting Luo
- Cancer Center, West China Hospital, Chengdu, China
| | - Yangfu Jiang
- State Key Laboratory of Biotherapy, Section of Oncogene, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
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11
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Yan M, Li G, An J. Discovery of small molecule inhibitors of the Wnt/β-catenin signaling pathway by targeting β-catenin/Tcf4 interactions. Exp Biol Med (Maywood) 2017; 242:1185-1197. [PMID: 28474989 DOI: 10.1177/1535370217708198] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Wnt/β-catenin signaling pathway typically shows aberrant activation in various cancer cells, especially colorectal cancer cells. This signaling pathway regulates the expression of a variety of tumor-related proteins, including c-myc and cyclin D1, and plays essential roles in tumorigenesis and in the development of many cancers. Small molecules that block the interactions between β-catenin and Tcf4, a downstream stage of activation of the Wnt/β-catenin signaling pathway, could efficiently cut off this signal transduction and thereby act as a novel class of anticancer drugs. This paper reviews the currently reported inhibitors that target β-catenin/Tcf4 interactions, focusing on the discovery approaches taken in the design of these inhibitors and their bioactivities. A brief perspective is then shared on the future discovery and development of this class of inhibitors. Impact statement This mini-review summarized the current knowledge of inhibitors of interactions of beta-catenin/Tcf4 published to date according to their discovery approaches, and discussed their in vitro and in vivo activities, selectivities, and pharmacokinetic properties. Several reviews presently available now in this field describe modulators of the Wnt/beta-catenin pathway, but are generally focused on the bioactivities of these inhibitors. By contrast, this review focused on the drug discovery approaches taken in identifying these types of inhibitors and provided our perspective on further strategies for future drug discoveries. This review also integrated many recently published and important works on highly selective inhibitors as well as rational drug design. We believe that the findings and strategies summarized in this review have broad implications and will be of interest throughout the biochemical and pharmaceutical research community.
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Affiliation(s)
- Maocai Yan
- 1 School of Pharmacy, Jining Medical University, Rizhao, Shandong 276800, P. R. China
| | - Guanqun Li
- 2 Upstate Medical University, State University of New York, Syracuse, NY 13210, USA
| | - Jing An
- 3 Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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12
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The Intersection of Structural and Chemical Biology - An Essential Synergy. Cell Chem Biol 2016; 23:173-182. [PMID: 26933743 DOI: 10.1016/j.chembiol.2015.12.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 12/04/2015] [Accepted: 12/04/2015] [Indexed: 12/22/2022]
Abstract
The continual improvement in our ability to generate high resolution structural models of biological molecules has stimulated and supported innovative chemical biology projects that target increasingly challenging ligand interaction sites. In this review we outline some of the recent developments in chemical biology and rational ligand design and show selected examples that illustrate the synergy between these research areas.
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13
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Lu B, Green BA, Farr JM, Lopes FCM, Van Raay TJ. Wnt Drug Discovery: Weaving Through the Screens, Patents and Clinical Trials. Cancers (Basel) 2016; 8:cancers8090082. [PMID: 27598201 PMCID: PMC5040984 DOI: 10.3390/cancers8090082] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 08/09/2016] [Accepted: 08/15/2016] [Indexed: 12/17/2022] Open
Abstract
The Wnt signaling pathway is intricately involved in many aspects of development and is the root cause of an increasing number of diseases. For example, colorectal cancer is the second leading cause of death in the industrialized world and aberration of Wnt signaling within the colonic stem cell is the cause of more than 90% of these cancers. Despite our advances in successfully targeting other pathways, such as Human Epidermal Growth Factor Receptor 2 (HER2), there are no clinically relevant therapies available for Wnt-related diseases. Here, we investigated where research activities are focused with respect to Wnt signaling modulators by searching the United States Patent and Trade Office (USPTO) for patents and patent applications related to Wnt modulators and compared this to clinical trials focusing on Wnt modulation. We found that while the transition of intellectual property surrounding the Wnt ligand-receptor interface to clinical trials is robust, this is not true for specific inhibitors of β-catenin, which is constitutively active in many cancers. Considering the ubiquitous use of the synthetic T-cell Factor/Lymphoid Enhancer Factor (TCF/Lef) reporter system and its success in identifying novel modulators in vitro, we speculate that this model of drug discovery does not capture the complexity of in vivo Wnt signaling that may be required if we are to successfully target the Wnt pathway in the clinic. Notwithstanding, increasingly more complex models are being developed, which may not be high throughput, but more pragmatic in our pursuit to control Wnt signaling.
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Affiliation(s)
- Benjamin Lu
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Brooke A Green
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Jacqueline M Farr
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Flávia C M Lopes
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Terence J Van Raay
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
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14
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Small-molecule inhibitors of Wnt signaling pathway: towards novel anticancer therapeutics. Future Med Chem 2015; 7:2485-505. [PMID: 26670195 DOI: 10.4155/fmc.15.159] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The Wnt signaling pathway involves secreted glycoproteins that bind to the Frizzled family receptors to activate intracellular signal transduction events that regulate cell proliferation, apoptosis, cell migration and many critical aspects of developmental biology. DISCUSSION Aberrant Wnt signaling underlies a wide range of pathologies in humans including tumor initiation, tumor growth, cell senescence, cell death, differentiation and metastasis. The inhibition of Wnt signaling offers a novel approach for anticancer therapeutics. CONCLUSION Focusing on recent developments, we reviewed the small-molecule inhibitors targeting various components of Wnt signaling pathways and the progress from the discovery of lead compounds to highly potent inhibitors with significant therapeutic potential.
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15
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Hoggard LR, Zhang Y, Zhang M, Panic V, Wisniewski JA, Ji H. Rational design of selective small-molecule inhibitors for β-catenin/B-cell lymphoma 9 protein-protein interactions. J Am Chem Soc 2015; 137:12249-60. [PMID: 26352795 DOI: 10.1021/jacs.5b04988] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Selective inhibition of α-helix-mediated protein-protein interactions (PPIs) with small organic molecules provides great potential for the discovery of chemical probes and therapeutic agents. Protein Data Bank data mining using the HippDB database indicated that (1) the side chains of hydrophobic projecting hot spots at positions i, i + 3, and i + 7 of an α-helix had few orientations when interacting with the second protein and (2) the hot spot pockets of PPI complexes had different sizes, shapes, and chemical groups when interacting with the same hydrophobic projecting hot spots of α-helix. On the basis of these observations, a small organic molecule, 4'-fluoro-N-phenyl-[1,1'-biphenyl]-3-carboxamide, was designed as a generic scaffold that itself directly mimics the binding mode of the side chains of hydrophobic projecting hot spots at positions i, i + 3, and i + 7 of an α-helix. Convenient decoration of this generic scaffold led to the selective disruption of α-helix-mediated PPIs. A series of small-molecule inhibitors selective for β-catenin/B-cell lymphoma 9 (BCL9) over β-catenin/cadherin PPIs was designed and synthesized. The binding mode of new inhibitors was characterized by site-directed mutagenesis and structure-activity relationship studies. This new class of inhibitors can selectively disrupt β-catenin/BCL9 over β-catenin/cadherin PPIs, suppress the transactivation of canonical Wnt signaling, downregulate the expression of Wnt target genes, and inhibit the growth of Wnt/β-catenin-dependent cancer cells.
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Affiliation(s)
- Logan R Hoggard
- Department of Chemistry, Center for Cell and Genome Science, University of Utah , Salt Lake City, Utah 84112-0850, United States
| | - Yongqiang Zhang
- Department of Chemistry, Center for Cell and Genome Science, University of Utah , Salt Lake City, Utah 84112-0850, United States
| | - Min Zhang
- Department of Chemistry, Center for Cell and Genome Science, University of Utah , Salt Lake City, Utah 84112-0850, United States
| | - Vanja Panic
- Department of Chemistry, Center for Cell and Genome Science, University of Utah , Salt Lake City, Utah 84112-0850, United States
| | - John A Wisniewski
- Department of Chemistry, Center for Cell and Genome Science, University of Utah , Salt Lake City, Utah 84112-0850, United States
| | - Haitao Ji
- Department of Chemistry, Center for Cell and Genome Science, University of Utah , Salt Lake City, Utah 84112-0850, United States
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16
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Sheng C, Dong G, Miao Z, Zhang W, Wang W. State-of-the-art strategies for targeting protein-protein interactions by small-molecule inhibitors. Chem Soc Rev 2015; 44:8238-59. [PMID: 26248294 DOI: 10.1039/c5cs00252d] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Targeting protein-protein interactions (PPIs) has emerged as a viable approach in modern drug discovery. However, the identification of small molecules enabling us to effectively interrupt their interactions presents significant challenges. In the recent past, significant advances have been made in the development of new biological and chemical strategies to facilitate the discovery process of small-molecule PPI inhibitors. This review aims to highlight the state-of-the-art technologies and the achievements made recently in this field. The "hot spots" of PPIs have been proved to be critical for small molecules to bind. Three strategies including screening, designing, and synthetic approaches have been explored for discovering PPI inhibitors by targeting the "hot spots". Although the classic high throughput screening approach can be used, fragment screening, fragment-based drug design and newly improved virtual screening are demonstrated to be more effective in the discovery of PPI inhibitors. In addition to screening approaches, design strategies including anchor-based and small molecule mimetics of secondary structures involved in PPIs have become powerful tools as well. Finally, constructing new chemically spaced libraries with high diversity and complexity is becoming an important area of interest for PPI inhibitors. The successful cases from the recent five year studies are used to illustrate how these approaches are implemented to uncover and optimize small molecule PPI inhibitors and notably some of them have become promising therapeutics.
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Affiliation(s)
- Chunquan Sheng
- Department of Medicinal Chemistry, School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, P. R. China.
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17
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Soldi R, Horrigan SK, Cholody MW, Padia J, Sorna V, Bearss J, Gilcrease G, Bhalla K, Verma A, Vankayalapati H, Sharma S. Design, Synthesis, and Biological Evaluation of a Series of Anthracene-9,10-dione Dioxime β-Catenin Pathway Inhibitors. J Med Chem 2015; 58:5854-62. [PMID: 26182238 DOI: 10.1021/acs.jmedchem.5b00460] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The Wnt/β-catenin signaling pathway plays a vital role in cell growth, the regulation, cell development, and the differentiation of normal stem cells. Constitutive activation of the Wnt/β-catenin signaling pathway is found in many human cancers, and thus, it is an attractive target for anticancer therapy. Specific inhibitors of this pathway have been keenly researched and developed. Cell based screening of compounds library, hit-to-lead optimization, computational and structure-based design strategies resulted in the design and synthesis of a series of anthracene-9,10-dione dioxime series of compounds demonstrated potent inhibition of β-catenin in vitro (IC50 < 10 nM, 14) and the growth of several cancer cell lines. This article discusses the potential of inhibiting the Wnt/β-catenin signaling pathway as a therapeutic approach for cancer along with an overview of the development of specific inhibitors.
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Affiliation(s)
- Raffaella Soldi
- †Division of Oncology of School of Medicine and Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, Utah 84112, United States
| | - Stephen K Horrigan
- ‡ Beta Cat Pharmaceuticals LLC, 22 Firstfield Road, Gaithersburg, Maryland 20878, United States
| | | | - Janak Padia
- ∥PrimeTime Life Sciences, 9700, Great Seneca Highway, Rockville, Maryland 20850, United States
| | - Venkataswamy Sorna
- †Division of Oncology of School of Medicine and Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, Utah 84112, United States
| | - Jared Bearss
- †Division of Oncology of School of Medicine and Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, Utah 84112, United States
| | - Glynn Gilcrease
- †Division of Oncology of School of Medicine and Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, Utah 84112, United States
| | - Kapil Bhalla
- ⊥Cockrell Center for Advanced Therapeutics, The Methodist Hospital Research Institute, 6670 Bertner Avenue, R9-113, Houston, Texas 77030, United States
| | - Anupam Verma
- #Department of Pediatric Hematology/Oncology, Primary Children's Hospital, University of Utah, 100 Mario Capecchi Drive, Salt Lake City, Utah 84113, United States
| | - Hariprasad Vankayalapati
- †Division of Oncology of School of Medicine and Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, Utah 84112, United States
| | - Sunil Sharma
- †Division of Oncology of School of Medicine and Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, Utah 84112, United States
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18
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Sammak S, Zinzalla G. Targeting protein-protein interactions (PPIs) of transcription factors: Challenges of intrinsically disordered proteins (IDPs) and regions (IDRs). PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 119:41-6. [PMID: 26126425 DOI: 10.1016/j.pbiomolbio.2015.06.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 06/23/2015] [Accepted: 06/25/2015] [Indexed: 12/26/2022]
Abstract
In this review we discuss recent progress in targeting the protein-protein interactions made by oncogenic transcription factors. We particularly focus on the challenges posed by the prevalence of intrinsically disordered regions in this class of protein and the strategies being used to overcome them.
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Affiliation(s)
- Susan Sammak
- Department of Microbiology, Cell and Tumour Biology, and Science for Life Laboratory, Karolinska Institutet, Tomtebodavägen 23A, Stockholm 171 65, Sweden
| | - Giovanna Zinzalla
- Department of Microbiology, Cell and Tumour Biology, and Science for Life Laboratory, Karolinska Institutet, Tomtebodavägen 23A, Stockholm 171 65, Sweden.
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19
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Catrow JL, Zhang Y, Zhang M, Ji H. Discovery of Selective Small-Molecule Inhibitors for the β-Catenin/T-Cell Factor Protein-Protein Interaction through the Optimization of the Acyl Hydrazone Moiety. J Med Chem 2015; 58:4678-92. [PMID: 25985283 DOI: 10.1021/acs.jmedchem.5b00223] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Acyl hydrazone is an important functional group for the discovery of bioactive small molecules. This functional group is also recognized as a pan assay interference structure. In this study, a new small-molecule inhibitor for the β-catenin/Tcf protein-protein interaction (PPI), ZINC02092166, was identified through AlphaScreen and FP assays. This compound contains an acyl hydrazone group and exhibits higher inhibitory activities in cell-based assays than biochemical assays. Inhibitor optimization resulted in chemically stable derivatives that disrupt the β-catenin/Tcf PPI. The binding mode of new inhibitors was characterized by site-directed mutagenesis and structure-activity relationship studies. This series of inhibitors with a new scaffold exhibits dual selectivity for β-catenin/Tcf over β-catenin/cadherin and β-catenin/APC PPIs. One derivative of this series suppresses canonical Wnt signaling, downregulates the expression of Wnt target genes, and inhibits the growth of cancer cells. This compound represents a solid starting point for the development of potent and selective β-catenin/Tcf inhibitors.
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Affiliation(s)
- J Leon Catrow
- Department of Chemistry, Center for Cell and Genome Science, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
| | - Yongqiang Zhang
- Department of Chemistry, Center for Cell and Genome Science, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
| | - Min Zhang
- Department of Chemistry, Center for Cell and Genome Science, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
| | - Haitao Ji
- Department of Chemistry, Center for Cell and Genome Science, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
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20
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AlphaScreen selectivity assay for β-catenin/B-cell lymphoma 9 inhibitors. Anal Biochem 2015; 469:43-53. [DOI: 10.1016/j.ab.2014.09.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/03/2014] [Accepted: 09/25/2014] [Indexed: 01/07/2023]
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21
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Huang Z, Zhang M, Burton SD, Katsakhyan LN, Ji H. Targeting the Tcf4 G13ANDE17 binding site to selectively disrupt β-catenin/T-cell factor protein-protein interactions. ACS Chem Biol 2014; 9:193-201. [PMID: 24191653 DOI: 10.1021/cb400795x] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Selective disruption of protein-protein interactions by small molecules is important for probing the structure and dynamic aspects of cellular network. It can also provide new therapeutic targets. β-Catenin of the canonical Wnt signaling pathway uses the same positively charged groove to bind with T-cell factor (Tcf), cadherin, and adenomatous polysis coli (APC). The extravagant formation of β-catenin/Tcf interactions drives the initiation and progression of many cancers and fibroses, while β-catenin/cadherin and β-catenin/APC interactions are essential for cell-cell adhesion and β-catenin degradation. In this study, a selective binding site that can differentiate β-catenin/Tcf, β-catenin/cadherin, and β-catenin/APC interactions was identified by alanine scanning and biochemical assays. A new peptidomimetic strategy that incorporates SiteMap and multiple-copy simultaneous search was used to design selective small-molecule inhibitors for β-catenin/Tcf interactions. A potent inhibitor was discovered to bind with β-catenin and completely disrupt β-catenin/Tcf interactions. It also exhibits dual selectivity for β-catenin/Tcf over β-catenin/cadherin and β-catenin/APC interactions in both biochemical and cell-based assays. This study provides a proof of concept for designing selective inhibitors for β-catenin/Tcf interactions.
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Affiliation(s)
- Zheng Huang
- Department
of Chemistry,
Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112−0850, United States
| | - Min Zhang
- Department
of Chemistry,
Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112−0850, United States
| | - Shawn D. Burton
- Department
of Chemistry,
Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112−0850, United States
| | - Levon N. Katsakhyan
- Department
of Chemistry,
Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112−0850, United States
| | - Haitao Ji
- Department
of Chemistry,
Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112−0850, United States
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22
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Trautmann M, Sievers E, Aretz S, Kindler D, Michels S, Friedrichs N, Renner M, Kirfel J, Steiner S, Huss S, Koch A, Penzel R, Larsson O, Kawai A, Tanaka S, Sonobe H, Waha A, Schirmacher P, Mechtersheimer G, Wardelmann E, Büttner R, Hartmann W. SS18-SSX fusion protein-induced Wnt/β-catenin signaling is a therapeutic target in synovial sarcoma. Oncogene 2013; 33:5006-16. [PMID: 24166495 DOI: 10.1038/onc.2013.443] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 09/11/2013] [Accepted: 09/16/2013] [Indexed: 12/11/2022]
Abstract
Synovial sarcoma is a high-grade soft tissue malignancy characterized by a specific reciprocal translocation t(X;18), which leads to the fusion of the SS18 (SYT) gene to one of three SSX genes (SSX1, SSX2 or SSX4). The resulting chimeric SS18-SSX protein is suggested to act as an oncogenic transcriptional regulator. Despite multimodal therapeutic approaches, metastatic disease is often lethal and the development of novel targeted therapeutic strategies is required. Several expression-profiling studies identified distinct gene expression signatures, implying a consistent role of Wnt/β-catenin signaling in synovial sarcoma tumorigenesis. Here we investigate the functional and therapeutic relevance of Wnt/β-catenin pathway activation in vitro and in vivo. Immunohistochemical analyses of nuclear β-catenin and Wnt downstream targets revealed activation of canonical Wnt signaling in a significant subset of 30 primary synovial sarcoma specimens. Functional aspects of Wnt signaling including dependence of Tcf/β-catenin complex activity on the SS18-SSX fusion proteins were analyzed. Efficient SS18-SSX-dependent activation of the Tcf/β-catenin transcriptional complex was confirmed by TOPflash reporter luciferase assays and immunoblotting. In five human synovial sarcoma cell lines, inhibition of the Tcf/β-catenin protein-protein interaction significantly blocked the canonical Wnt/β-catenin signaling cascade, accompanied by the effective downregulation of Wnt targets (AXIN2, CDC25A, c-MYC, DKK1, CyclinD1 and Survivin) and the specific suppression of cell viability associated with the induction of apoptosis. In SYO-1 synovial sarcoma xenografts, administration of small molecule Tcf/β-catenin complex inhibitors significantly reduced tumor growth, associated with diminished AXIN2 protein levels. In summary, SS18-SSX-induced Wnt/β-catenin signaling appears to be of crucial biological importance in synovial sarcoma tumorigenesis and progression, representing a potential molecular target for the development of novel therapeutic strategies.
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Affiliation(s)
- M Trautmann
- 1] Department of Pathology, University Hospital Cologne, Cologne, Germany [2] Department of Pathology, University Hospital Bonn, Bonn, Germany
| | - E Sievers
- Department of Pathology, University Hospital Cologne, Cologne, Germany
| | - S Aretz
- Institute of Human Genetics, University of Bonn, Bonn, Germany
| | - D Kindler
- Department of Pathology, University Hospital Cologne, Cologne, Germany
| | - S Michels
- Department of Pathology, University Hospital Cologne, Cologne, Germany
| | - N Friedrichs
- Department of Pathology, University Hospital Cologne, Cologne, Germany
| | - M Renner
- Department of Pathology, University Hospital Heidelberg, Heidelberg, Germany
| | - J Kirfel
- Department of Pathology, University Hospital Bonn, Bonn, Germany
| | - S Steiner
- Department of Pathology, University Hospital Bonn, Bonn, Germany
| | - S Huss
- Department of Pathology, University Hospital Cologne, Cologne, Germany
| | - A Koch
- Department of Neuropathology, Charité-Universitätsmedizin, Berlin, Germany
| | - R Penzel
- Department of Pathology, University Hospital Heidelberg, Heidelberg, Germany
| | - O Larsson
- Departments of Oncology & Pathology, The Karolinska Institute, Stockholm, Sweden
| | - A Kawai
- Division of Orthopaedic Surgery, National Cancer Center Hospital, Tokyo, Japan
| | - S Tanaka
- Laboratory of Molecular & Cellular Pathology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - H Sonobe
- Department of Laboratory Medicine, Chungoku Central Hospital, Fukuyama, Hiroshima, Japan
| | - A Waha
- Department of Neuropathology, University Hospital Bonn, Bonn, Germany
| | - P Schirmacher
- Department of Pathology, University Hospital Heidelberg, Heidelberg, Germany
| | - G Mechtersheimer
- Department of Pathology, University Hospital Heidelberg, Heidelberg, Germany
| | - E Wardelmann
- Department of Pathology, University Hospital Cologne, Cologne, Germany
| | - R Büttner
- Department of Pathology, University Hospital Cologne, Cologne, Germany
| | - W Hartmann
- Department of Pathology, University Hospital Cologne, Cologne, Germany
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