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Yuan Y, Li Y, Wu X, Bo J, Zhang L, Zhang J, Hu Y, Chen Y, Zeng Y, Wei X, Zhang H. POH1 induces Smad3 deubiquitination and promotes lung cancer metastasis. Cancer Lett 2024; 582:216526. [PMID: 38061486 DOI: 10.1016/j.canlet.2023.216526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 11/23/2023] [Accepted: 11/24/2023] [Indexed: 01/16/2024]
Abstract
Smad3 is the key mediator of TGF-β1-triggered signal transduction and the related biological responses, promoting cell invasion and metastasis in various cancers, including lung cancer. However, the deubiquitinase stabilizing Smad3 remains unknown. In this study, we present a paradigm in which POH1 is identified as a novel deubiquitinase of Smad3 that plays a tumor-promoting role in lung adenocarcinoma (LUAD) by regulating Smad3 stability. POH1 markedly increased Smad3 protein levels and prolonged its half-life. POH1 directly interacted and colocalized with Smad3, leading to the removal of poly-deubiquitination of Smad3. Functionally, POH1 facilitated cell proliferation, migration, and invasion by stabilizing Smad3. Importantly, POH1 also promoted liver metastasis of lung cancer cells. The protein levels of both POH1 and Smad3 were raised in the tumor tissues of patients with LUAD, which predicts poor prognosis. Collectively, we demonstrate that POH1 acts as an oncoprotein by enhancing TGF-β1/Smad3 signaling and TGF-β1-mediated metastasis of lung cancer.
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Affiliation(s)
- Yang Yuan
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Yixiao Li
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Xiao Wu
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Jinsuo Bo
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Lei Zhang
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Jing Zhang
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Ye Hu
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Yining Chen
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Yiyan Zeng
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China
| | - Xiaofan Wei
- Department of Human Anatomy, Histology and Embryology, Program for Cancer and Cell Biology, School of Basic Medical Sciences, Peking University International Cancer Institute, and State Key Laboratory of Molecular Oncology, Peking University Health Science Center, Beijing 100191, China.
| | - Hongquan Zhang
- Department of Human Anatomy, Histology, and Embryology, Shenzhen University School of Medicine, Shenzhen, 518055, China.
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Lin XH, Li DP, Liu ZY, Zhang S, Tang WQ, Chen RX, Weng SQ, Tseng YJ, Xue RY, Dong L. Six immune-related promising biomarkers may promote hepatocellular carcinoma prognosis: a bioinformatics analysis and experimental validation. Cancer Cell Int 2023; 23:52. [PMID: 36959615 PMCID: PMC10035283 DOI: 10.1186/s12935-023-02888-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 02/23/2023] [Indexed: 03/25/2023] Open
Abstract
Background Abnormal miRNA and mRNA expression and dysregulated immune microenvironment have been found to frequently induce the progression of hepatocellular carcinoma (HCC) in recent reports. In particular, the immune-related competing endogenous RNAs (ceRNA) mechanism plays a crucial role in HCC progression. However, the underlying mechanisms remain unclear. Methods Differentially expressed immune-related genes were obtained from the Immport, GEO, and TCGA databases. The mRNA and protein expression levels in HCC tissues and adjacent normal tissues were confirmed, and we further investigated the methylation levels of these biomarkers to explore their function. Then, the TIMER and TISCH databases were used to assess the relationship between immune infiltration and hub genes. Survival analysis and univariate and multivariate Cox models were used to evaluate the association between hub genes and HCC diagnosis. Hub gene expression was experimentally validated in six HCC cell lines and 15 HCC samples using qRT-PCR and immunohistochemistry. The hub genes were uploaded to DSigDB for drug prediction enrichment analysis. Results We identified that patients with abnormal miRNAs (hsa-miR-125b-5p and hsa-miR-21-5p) and their targeted genes (NTF3, PSMD14, CD320, and SORT1) had a worse prognosis. Methylation analysis of miRNA-targeted genes suggested that alteration of methylation levels is also a factor in the induction of tumorigenesis. We also found that the development of HCC progression caused by miRNA-mRNA interactions may be closely correlated with the infiltration of immunocytes. Moreover, the GSEA, GO, and KEGG analysis suggested that several common immune-related biological processes and pathways were related to miRNA-targeted genes. The results of qRT-PCR, immunohistochemistry, and western blotting were consistent with our bioinformatics results, suggesting that abnormal miRNAs and their targeted genes may affect HCC progression. Conclusions Briefly, our study systematically describes the mechanisms of miRNA-mRNA interactions in HCC and predicts promising biomarkers that are associated with immune filtration for HCC progression. Supplementary Information The online version contains supplementary material available at 10.1186/s12935-023-02888-9.
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Affiliation(s)
- Xia-Hui Lin
- grid.8547.e0000 0001 0125 2443Department of Gastroenterology and Hepatology, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
- grid.413087.90000 0004 1755 3939Shanghai Institute of Liver Disease, Shanghai, 200032 China
| | - Dong-ping Li
- grid.8547.e0000 0001 0125 2443Department of Gastroenterology and Hepatology, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
- grid.413087.90000 0004 1755 3939Shanghai Institute of Liver Disease, Shanghai, 200032 China
| | - Zhi-Yong Liu
- grid.8547.e0000 0001 0125 2443Department of Gastroenterology and Hepatology, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
- grid.413087.90000 0004 1755 3939Shanghai Institute of Liver Disease, Shanghai, 200032 China
| | - Si Zhang
- grid.8547.e0000 0001 0125 2443Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032 China
| | - Wen-qing Tang
- grid.8547.e0000 0001 0125 2443Department of Gastroenterology and Hepatology, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
- grid.413087.90000 0004 1755 3939Shanghai Institute of Liver Disease, Shanghai, 200032 China
| | - Rong-xin Chen
- grid.8547.e0000 0001 0125 2443Key Laboratory of Carcinogenesis and Cancer Invasion, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
| | - Shu-qiang Weng
- grid.8547.e0000 0001 0125 2443Department of Gastroenterology and Hepatology, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
- grid.413087.90000 0004 1755 3939Shanghai Institute of Liver Disease, Shanghai, 200032 China
| | - Yu-jen Tseng
- grid.8547.e0000 0001 0125 2443Department of Digestive Diseases, Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200040 China
| | - Ru-yi Xue
- grid.8547.e0000 0001 0125 2443Department of Gastroenterology and Hepatology, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
- grid.413087.90000 0004 1755 3939Shanghai Institute of Liver Disease, Shanghai, 200032 China
| | - Ling Dong
- grid.8547.e0000 0001 0125 2443Department of Gastroenterology and Hepatology, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
- grid.413087.90000 0004 1755 3939Shanghai Institute of Liver Disease, Shanghai, 200032 China
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Jia C, Zhang X, Qu T, Wu X, Li Y, Zhao Y, Sun L, Wang Q. Depletion of PSMD14 suppresses bladder cancer proliferation by regulating GPX4. PeerJ 2023; 11:e14654. [PMID: 36632137 PMCID: PMC9828270 DOI: 10.7717/peerj.14654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 12/07/2022] [Indexed: 01/09/2023] Open
Abstract
Objective The aim of this study was to investigate the role of deubiquitinase (DUB) 26S proteasome non-ATPase regulatory subunit 14 (PSMD14) in patients with bladder cancer. Methods From 2016 to 2018, 181 patients diagnosed with primary bladder cancer at the Affiliated Hospital of Qingdao University were recruited. The expression of PSMD14 in bladder cancer tissues was tested by immunochemistry. The association between PSMD14 expression and clinical and pathological data and outcomes of bladder cancer patients was determined. Overexpression and knockdown cells were constructed to evaluate the effects of PSMD14 on proliferation of bladder cancer cells. Results Our results showed that PSMD14 was significantly overexpressed in bladder cancer tissues compared to adjacent non-tumor tissues (76.24% vs 23.76%, P = 0.02). The expression of PSMD14 was significantly higher in patients with larger tumor diameters (85.14% vs 70.09%, P = 0.019) and patients with a family history of cancer (92.16% vs 70.00%, P = 0.002). Patients with high expression of PSMD14 had poor disease-free survival (DFS) (HR = 2.89, 95% CI [1.247-6.711], P = 0.013). Gain and loss of function experiments demonstrated that PSMD14 deficiency inhibited bladder cancer cell proliferation. Additionally, depletion of PSMD14 suppressed bladder cancer cell growth via down-regulation of GPX4, and the promotion of PSMD14-induced cell growth was observably reversed by the GPX4 inhibitor RSL3. Conclusion We determined that PSMD14 is highly expressed in bladder cancer tissues, and that PSMD14 expression correlated with poor disease-free survival. Depletion of PSMD14 could inhibit the proliferation of bladder cancer cells through the downregulation of GPX4. Therefore, PSMD14 may be an effective target for the treatment of bladder cancer.
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Affiliation(s)
- Changxin Jia
- Department of Anesthesiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Xin Zhang
- Department of Anesthesiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Tingting Qu
- Department of Pathology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Xiuyun Wu
- Department of Anesthesiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Yu Li
- Department of Anesthesiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Yang Zhao
- Department of Anesthesiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Lijiang Sun
- Department of Urology Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Qing Wang
- Department of Endocrine and metabolic diseases, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
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Li Y, Zeng M, Zhang F, Wu FX, Li M. DeepCellEss: cell line-specific essential protein prediction with attention-based interpretable deep learning. Bioinformatics 2022; 39:6865030. [PMID: 36458923 PMCID: PMC9825760 DOI: 10.1093/bioinformatics/btac779] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 11/25/2022] [Accepted: 12/01/2022] [Indexed: 12/05/2022] Open
Abstract
MOTIVATION Protein essentiality is usually accepted to be a conditional trait and strongly affected by cellular environments. However, existing computational methods often do not take such characteristics into account, preferring to incorporate all available data and train a general model for all cell lines. In addition, the lack of model interpretability limits further exploration and analysis of essential protein predictions. RESULTS In this study, we proposed DeepCellEss, a sequence-based interpretable deep learning framework for cell line-specific essential protein predictions. DeepCellEss utilizes a convolutional neural network and bidirectional long short-term memory to learn short- and long-range latent information from protein sequences. Further, a multi-head self-attention mechanism is used to provide residue-level model interpretability. For model construction, we collected extremely large-scale benchmark datasets across 323 cell lines. Extensive computational experiments demonstrate that DeepCellEss yields effective prediction performance for different cell lines and outperforms existing sequence-based methods as well as network-based centrality measures. Finally, we conducted some case studies to illustrate the necessity of considering specific cell lines and the superiority of DeepCellEss. We believe that DeepCellEss can serve as a useful tool for predicting essential proteins across different cell lines. AVAILABILITY AND IMPLEMENTATION The DeepCellEss web server is available at http://csuligroup.com:8000/DeepCellEss. The source code and data underlying this study can be obtained from https://github.com/CSUBioGroup/DeepCellEss. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Yiming Li
- Hunan Provincial Key Lab on Bioinformatics, School of Computer Science and Engineering, Central South University, Changsha 410083, China
| | - Min Zeng
- Hunan Provincial Key Lab on Bioinformatics, School of Computer Science and Engineering, Central South University, Changsha 410083, China
| | - Fuhao Zhang
- Hunan Provincial Key Lab on Bioinformatics, School of Computer Science and Engineering, Central South University, Changsha 410083, China
| | - Fang-Xiang Wu
- Division of Biomedical Engineering, Department of Computer Science, Department of Mechanical Engineering University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada
| | - Min Li
- To whom correspondence should be addressed.
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van der Wal L, Bezstarosti K, Demmers JAA. A ubiquitinome analysis to study the functional roles of the proteasome associated deubiquitinating enzymes USP14 and UCH37. J Proteomics 2022; 262:104592. [PMID: 35489684 DOI: 10.1016/j.jprot.2022.104592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 04/05/2022] [Accepted: 04/17/2022] [Indexed: 12/12/2022]
Abstract
The removal of (poly)ubiquitin chains at the proteasome is a key step in the protein degradation pathway that determines which proteins are degraded and ultimately decides cell fate. Three different deubiquitinating enzymes (DUBs) are associated to the human proteasome, PSMD14 (RPN11), USP14 and UCH37 (UCHL5). However, the functional roles and specificities of these proteasomal DUBs remain elusive. To reveal the specificities of proteasome associated DUBs, we used SILAC based quantitative ubiquitinomics to study the effects of CRISPR-Cas9 based knockout of each of these DUBs on the dynamic cellular ubiquitinome. We observed distinct effects on the global ubiquitinome upon removal of either USP14 or UCH37, while the simultaneous removal of both DUBs suggested less functional redundancy than previously anticipated. We also investigated whether the small molecule inhibitor b-AP15 has the potential to specifically target USP14 and UCH37 by comparing treatment of wild-type versus USP14/UCH37 double-knockout cells with this drug. Strikingly, broad and severe off-target effects were observed, questioning the alleged specificity of this inhibitor. In conclusion, this work presents novel insights into the function of proteasome associated DUBs and illustrates the power of in-depth ubiquitinomics for screening the activity of DUBs and of DUB modulating compounds. SIGNIFICANCE Introduction: The removal of (poly)ubiquitin chains at the proteasome is a key step in the protein degradation pathway that determines which proteins are degraded and ultimately decides cell fate. Three different deubiquitinating enzymes (DUBs) are associated to the human proteasome, PSMD14/RPN11, USP14 and UCH37/UCHL5. However, the functional roles and specificities of these proteasomal DUBs remains elusive. MATERIALS & METHODS We have applied a SILAC based quantitative ubiquitinomics to study the effects of CRISPR-Cas9 based knockout of each of these DUBs on the dynamic cellular ubiquitinome. Also, we have studied the function of the small molecule inhibitor b-AP15, which has the potential to specifically target USP14 and UCH37. RESULTS We report distinct effects on the ubiquitinome and the ability of the proteasome to clear proteins upon removal of either USP14 or UCH37, while the simultaneous removal of both DUBs suggests less redundancy than previously anticipated. In addition, broad and severe off-target effects were observed for b-AP15, questioning the alleged specificity of this inhibitor. CONCLUSIONS This work presents novel insights into the function of proteasome associated DUBs and illustrates the power of in-depth ubiquitinomics for screening the activity of DUBs and of DUB modulating compounds.
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Affiliation(s)
- Lennart van der Wal
- Proteomics Center, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Karel Bezstarosti
- Proteomics Center, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Jeroen A A Demmers
- Proteomics Center, Erasmus University Medical Center, Rotterdam, the Netherlands.
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Li J, Li Y, Xu F, Sun B, Yang L, Wang H. Deubiquitinating enzyme PSMD14 facilitates gastric carcinogenesis through stabilizing PTBP1. Exp Cell Res 2022; 415:113148. [DOI: 10.1016/j.yexcr.2022.113148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 03/11/2022] [Accepted: 04/05/2022] [Indexed: 12/24/2022]
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Kannappan V, Ali M, Small B, Rajendran G, Elzhenni S, Taj H, Wang W, Dou QP. Recent Advances in Repurposing Disulfiram and Disulfiram Derivatives as Copper-Dependent Anticancer Agents. Front Mol Biosci 2021; 8:741316. [PMID: 34604310 PMCID: PMC8484884 DOI: 10.3389/fmolb.2021.741316] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 08/20/2021] [Indexed: 12/30/2022] Open
Abstract
Copper (Cu) plays a pivotal role in cancer progression by acting as a co-factor that regulates the activity of many enzymes and structural proteins in cancer cells. Therefore, Cu-based complexes have been investigated as novel anticancer metallodrugs and are considered as a complementary strategy for currently used platinum agents with undesirable general toxicity. Due to the high failure rate and increased cost of new drugs, there is a global drive towards the repositioning of known drugs for cancer treatment in recent years. Disulfiram (DSF) is a first-line antialcoholism drug used in clinics for more than 65 yr. In combination with Cu, it has shown great potential as an anticancer drug by targeting a wide range of cancers. The reaction between DSF and Cu ions forms a copper diethyldithiocarbamate complex (Cu(DDC)2 also known as CuET) which is the active, potent anticancer ingredient through inhibition of NF-κB and ubiquitin-proteasome system as well as alteration of the intracellular reactive oxygen species (ROS). Importantly, DSF/Cu inhibits several molecular targets related to drug resistance, stemness, angiogenesis and metastasis and is thus considered as a novel strategy for overcoming tumour recurrence and relapse in patients. Despite its excellent anticancer efficacy, DSF has proven unsuccessful in several cancer clinical trials. This is likely due to the poor stability, rapid metabolism and/or short plasma half-life of the currently used oral version of DSF and the inability to form Cu(DDC)2 at relevant concentrations in tumour tissues. Here, we summarize the scientific rationale, molecular targets, and mechanisms of action of DSF/Cu in cancer cells and the outcomes of oral DSF ± Cu in cancer clinical trials. We will focus on the novel insights on harnessing the immune system and hypoxic microenvironment using DSF/Cu complex and discuss the emerging delivery strategies that can overcome the shortcomings of DSF-based anticancer therapies and provide opportunities for translation of DSF/Cu or its Cu(DDC)2 complex into cancer therapeutics.
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Affiliation(s)
- Vinodh Kannappan
- Research Institute in Healthcare Science, Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, United Kingdom.,Disulfican Ltd, University of Wolverhampton Science Park, Wolverhampton, United Kingdom
| | - Misha Ali
- Departments of Oncology, Pharmacology and Pathology, School of Medicine, Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, MI, United States.,Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Benjamin Small
- Research Institute in Healthcare Science, Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, United Kingdom
| | - Gowtham Rajendran
- Research Institute in Healthcare Science, Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, United Kingdom
| | - Salena Elzhenni
- Departments of Oncology, Pharmacology and Pathology, School of Medicine, Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, MI, United States
| | - Hamza Taj
- Departments of Oncology, Pharmacology and Pathology, School of Medicine, Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, MI, United States
| | - Weiguang Wang
- Research Institute in Healthcare Science, Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, United Kingdom.,Disulfican Ltd, University of Wolverhampton Science Park, Wolverhampton, United Kingdom
| | - Q Ping Dou
- Departments of Oncology, Pharmacology and Pathology, School of Medicine, Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, MI, United States
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An Arsenite Relay between PSMD14 and AIRAP Enables Revival of Proteasomal DUB Activity. Biomolecules 2021; 11:biom11091317. [PMID: 34572530 PMCID: PMC8465394 DOI: 10.3390/biom11091317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/01/2021] [Accepted: 09/03/2021] [Indexed: 01/21/2023] Open
Abstract
Maintaining 26S proteasome activity under diverse physiological conditions is a fundamental requirement in order to maintain cellular proteostasis. Several quantitative and qualitative mechanisms have evolved to ensure that ubiquitin–proteasome system (UPS) substrates do not accumulate and lead to promiscuous protein–protein interactions that, in turn, lead to cellular malfunction. In this report, we demonstrate that Arsenite Inducible Regulatory Particle-Associate Protein (AIRAP), previously reported as a proteasomal adaptor required for maintaining proteasomal flux during arsenite exposure, can directly bind arsenite molecules. We further show that arsenite inhibits Psmd14/Rpn11 metalloprotease deubiquitination activity by substituting zinc binding to the MPN/JAMM domain. The proteasomal adaptor AIRAP is able to directly relieve PSMD14/Rpn11 inhibition. A possible metal relay between arsenylated PSMD14/Rpn11 and AIRAP may serve as a cellular mechanism that senses proteasomal inhibition to restore Psmd14/Rpn11 activity.
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Small-Molecule Inhibitors Targeting Proteasome-Associated Deubiquitinases. Int J Mol Sci 2021; 22:ijms22126213. [PMID: 34207520 PMCID: PMC8226605 DOI: 10.3390/ijms22126213] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/02/2021] [Accepted: 06/05/2021] [Indexed: 02/06/2023] Open
Abstract
The 26S proteasome is the principal protease for regulated intracellular proteolysis. This multi-subunit complex is also pivotal for clearance of harmful proteins that are produced throughout the lifetime of eukaryotes. Recent structural and kinetic studies have revealed a multitude of conformational states of the proteasome in substrate-free and substrate-engaged forms. These conformational transitions demonstrate that proteasome is a highly dynamic machinery during substrate processing that can be also controlled by a number of proteasome-associated factors. Essentially, three distinct family of deubiquitinases–USP14, RPN11, and UCH37–are associated with the 19S regulatory particle of human proteasome. USP14 and UCH37 are capable of editing ubiquitin conjugates during the process of their dynamic engagement into the proteasome prior to the catalytic commitment. In contrast, RPN11-mediated deubiquitination is directly coupled to substrate degradation by sensing the proteasome’s conformational switch into the commitment steps. Therefore, proteasome-bound deubiquitinases are likely to tailor the degradation events in accordance with substrate processing steps and for dynamic proteolysis outcomes. Recent chemical screening efforts have yielded highly selective small-molecule inhibitors for targeting proteasomal deubiquitinases, such as USP14 and RPN11. USP14 inhibitors, IU1 and its progeny, were found to promote the degradation of a subset of substrates probably by overriding USP14-imposed checkpoint on the proteasome. On the other hand, capzimin, a RPN11 inhibitor, stabilized the proteasome substrates and showed the anti-proliferative effects on cancer cells. It is highly conceivable that these specific inhibitors will aid to dissect the role of each deubiquitinase on the proteasome. Moreover, customized targeting of proteasome-associated deubiquitinases may also provide versatile therapeutic strategies for induced or repressed protein degradation depending on proteolytic demand and cellular context.
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Jing C, Li X, Zhou M, Zhang S, Lai Q, Liu D, Ye B, Li L, Wu Y, Li H, Yue K, Chen P, Yao X, Wu Y, Duan Y, Wang X. The PSMD14 inhibitor Thiolutin as a novel therapeutic approach for esophageal squamous cell carcinoma through facilitating SNAIL degradation. Theranostics 2021; 11:5847-5862. [PMID: 33897885 PMCID: PMC8058732 DOI: 10.7150/thno.46109] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 03/11/2021] [Indexed: 12/13/2022] Open
Abstract
Metastasis and chemoresistance are major causes of poor prognosis in patients with esophageal squamous cell carcinoma (ESCC), manipulated by multiple factors including deubiquitinating enzyme (DUB). DUB PSMD14 is reported to be a promising therapeutic target in various cancers. Here, we explored the antitumor activity of Thiolutin (THL), the PSMD14 inhibitor, as a new therapy strategy in ESCC. Methods: Through 4-NQO-induced murine ESCC model, we investigated the expression of PSMD14 in esophageal tumorigenesis. Ubiquitin-AMC assay was performed to evaluate DUB activity of PSMD14 with THL treatment. The effect of THL on epithelial-to-mesenchymal transition (EMT), invasion, stemness and chemosensitivity was detected by using in vitro and in vivo experiments. Immunoprecipitation and in vivo ubiquitination assay were conducted to examine whether THL could impair the deubiquitination and stability of SNAIL regulated by PSMD14. Results: Compared with normal esophageal epithelium, PSMD14 was upregulated in 4-NQO-induced murine esophageal epithelium dysplasia and ESCC tissues. THL could significantly weaken DUB activity of PSMD14. Furthermore, the results of in vitro and in vivo assays showed that THL efficiently suppressed motility and stemness and increased sensitivity to cisplatin in ESCC. Mechanically, THL impaired the interaction between PSMD14 and SNAIL, then promoted the ubiquitination and degradation of SNAIL to inhibit EMT which plays a crucial role in ESCC metastasis, stemness and chemosensitivity. TCGA database analysis revealed that high concomitant PSMD14/SNAIL expression predicted shorter overall survival in esophageal cancer. Conclusion: Our findings demonstrate for the first time that suppression of PSMD14/SNAIL axis by THL could be a novel and promising therapeutic approach for ESCC clinical therapy.
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Functional impacts of the ubiquitin-proteasome system on DNA damage recognition in global genome nucleotide excision repair. Sci Rep 2020; 10:19704. [PMID: 33184426 PMCID: PMC7665181 DOI: 10.1038/s41598-020-76898-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 11/04/2020] [Indexed: 12/13/2022] Open
Abstract
The ubiquitin-proteasome system (UPS) plays crucial roles in regulation of various biological processes, including DNA repair. In mammalian global genome nucleotide excision repair (GG-NER), activation of the DDB2-associated ubiquitin ligase upon UV-induced DNA damage is necessary for efficient recognition of lesions. To date, however, the precise roles of UPS in GG-NER remain incompletely understood. Here, we show that the proteasome subunit PSMD14 and the UPS shuttle factor RAD23B can be recruited to sites with UV-induced photolesions even in the absence of XPC, suggesting that proteolysis occurs at DNA damage sites. Unexpectedly, sustained inhibition of proteasome activity results in aggregation of PSMD14 (presumably with other proteasome components) at the periphery of nucleoli, by which DDB2 is immobilized and sequestered from its lesion recognition functions. Although depletion of PSMD14 alleviates such DDB2 immobilization induced by proteasome inhibitors, recruitment of DDB2 to DNA damage sites is then severely compromised in the absence of PSMD14. Because all of these proteasome dysfunctions selectively impair removal of cyclobutane pyrimidine dimers, but not (6-4) photoproducts, our results indicate that the functional integrity of the proteasome is essential for the DDB2-mediated lesion recognition sub-pathway, but not for GG-NER initiated through direct lesion recognition by XPC.
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Shin JY, Muniyappan S, Tran NN, Park H, Lee SB, Lee BH. Deubiquitination Reactions on the Proteasome for Proteasome Versatility. Int J Mol Sci 2020; 21:E5312. [PMID: 32726943 PMCID: PMC7432943 DOI: 10.3390/ijms21155312] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/21/2020] [Accepted: 07/23/2020] [Indexed: 12/17/2022] Open
Abstract
The 26S proteasome, a master player in proteolysis, is the most complex and meticulously contextured protease in eukaryotic cells. While capable of hosting thousands of discrete substrates due to the selective recognition of ubiquitin tags, this protease complex is also dynamically checked through diverse regulatory mechanisms. The proteasome's versatility ensures precise control over active proteolysis, yet prevents runaway or futile degradation of many essential cellular proteins. Among the multi-layered processes regulating the proteasome's proteolysis, deubiquitination reactions are prominent because they not only recycle ubiquitins, but also impose a critical checkpoint for substrate degradation on the proteasome. Of note, three distinct classes of deubiquitinating enzymes-USP14, RPN11, and UCH37-are associated with the 19S subunits of the human proteasome. Recent biochemical and structural studies suggest that these enzymes exert dynamic influence over proteasome output with limited redundancy, and at times act in opposition. Such distinct activities occur spatially on the proteasome, temporally through substrate processing, and differentially for ubiquitin topology. Therefore, deubiquitinating enzymes on the proteasome may fine-tune the degradation depending on various cellular contexts and for dynamic proteolysis outcomes. Given that the proteasome is among the most important drug targets, the biology of proteasome-associated deubiquitination should be further elucidated for its potential targeting in human diseases.
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Affiliation(s)
- Ji Yeong Shin
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Center for Cell Fate Reprogramming & Control, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Srinivasan Muniyappan
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
| | - Non-Nuoc Tran
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Center for Cell Fate Reprogramming & Control, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Hyeonjeong Park
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
| | - Sung Bae Lee
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Byung-Hoon Lee
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Center for Cell Fate Reprogramming & Control, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
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Zhang L, Xu H, Ma C, Zhang J, Zhao Y, Yang X, Wang S, Li D. Upregulation of deubiquitinase PSMD14 in lung adenocarcinoma (LUAD) and its prognostic significance. J Cancer 2020; 11:2962-2971. [PMID: 32226511 PMCID: PMC7086243 DOI: 10.7150/jca.39539] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 01/24/2020] [Indexed: 01/01/2023] Open
Abstract
PSMD14 is a 19S-proteasome-associated deubiquitinating enzyme that facilitates protein degradation by the 20S proteasome core particle. Although accumulating evidence indicates that PSMD14 has emerged as a critical oncogenic factor by promoting tumor growth, the expression and function of PSMD14 in non-small cell lung cancer (NSCLC) remain largely unknown. In this study, we assessed PSMD14 expression and correlated it with clinical-pathological features and patient survival in NSCLC. We also determined the roles of PSMD14 in the regulation of lung adenocarcinoma (LUAD) cell growth. The results showed that PSMD14 expression was significantly upregulated in human NSCLC tissues compared with adjacent non-cancerous tissues. The PSMD14 level was associated with tumor size, lymph node invasion, and TNM stage in LUAD patients. Importantly, high PSMD14 expression was associated with poor overall survival (OS) and disease-free survival (DFS) in LUAD patients. Further, knockdown of PSMD14 significantly inhibited cell growth and caused G1 arrest and cellular senescence by increasing p21 stability in LUAD cells. PSMD14 knockdown also promoted cell apoptosis by increasing cleaved caspase-3 levels in H1299 cells. PSMD14 may serve as a potential prognostic marker and therapeutic target for LUAD patients.
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Affiliation(s)
- Ling Zhang
- Center for Translational Medicine, The Affiliated Zhangjiagang Hospital of Soochow University, 68 Jiyang W Rd, Suzhou, 215600, China
| | - Hui Xu
- Department of Thoracic Surgery, The Affiliated Zhangjiagang Hospital of Soochow University, 68 Jiyang W Rd, Suzhou, 215600, China
| | - Chunping Ma
- Department of Thoracic Surgery, The Affiliated Zhangjiagang Hospital of Soochow University, 68 Jiyang W Rd, Suzhou, 215600, China
| | - Jieru Zhang
- Department of Respiratory & Critical Care Medicine, The Affiliated Zhangjiagang Hospital of Soochow University, 68 Jiyang W Rd, Suzhou, 215600, China
| | - Yuanjie Zhao
- Department of General Surgery, The Affiliated Zhangjiagang Hospital of Soochow University, 68 Jiyang W Rd, Suzhou, 215600, China
| | - Xiaomei Yang
- Department of Emergency, The Affiliated Zhangjiagang Hospital of Soochow University, 68 Jiyang W Rd, Suzhou, 215600, China
| | - Shusheng Wang
- Department of General Surgery, The Affiliated Zhangjiagang Hospital of Soochow University, 68 Jiyang W Rd, Suzhou, 215600, China
| | - Dawei Li
- Center for Translational Medicine, The Affiliated Zhangjiagang Hospital of Soochow University, 68 Jiyang W Rd, Suzhou, 215600, China
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Proteasome Inhibitors: Harnessing Proteostasis to Combat Disease. Molecules 2020; 25:molecules25030671. [PMID: 32033280 PMCID: PMC7037493 DOI: 10.3390/molecules25030671] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/25/2020] [Accepted: 01/28/2020] [Indexed: 02/07/2023] Open
Abstract
The proteasome is the central component of the main cellular protein degradation pathway. During the past four decades, the critical function of the proteasome in numerous physiological processes has been revealed, and proteasome activity has been linked to various human diseases. The proteasome prevents the accumulation of misfolded proteins, controls the cell cycle, and regulates the immune response, to name a few important roles for this macromolecular "machine." As a therapeutic target, proteasome inhibitors have been approved for the treatment of multiple myeloma and mantle cell lymphoma. However, inability to sufficiently inhibit proteasome activity at tolerated doses has hampered efforts to expand the scope of proteasome inhibitor-based therapies. With emerging new modalities in myeloma, it might seem challenging to develop additional proteasome-based therapies. However, the constant development of new applications for proteasome inhibitors and deeper insights into the intricacies of protein homeostasis suggest that proteasome inhibitors might have novel therapeutic applications. Herein, we summarize the latest advances in proteasome inhibitor development and discuss the future of proteasome inhibitors and other proteasome-based therapies in combating human diseases.
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15
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Deubiquitinase PSMD14 enhances hepatocellular carcinoma growth and metastasis by stabilizing GRB2. Cancer Lett 2020; 469:22-34. [DOI: 10.1016/j.canlet.2019.10.025] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 09/23/2019] [Accepted: 10/15/2019] [Indexed: 01/17/2023]
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Repurposing old drugs as new inhibitors of the ubiquitin-proteasome pathway for cancer treatment. Semin Cancer Biol 2019; 68:105-122. [PMID: 31883910 DOI: 10.1016/j.semcancer.2019.12.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 10/30/2019] [Accepted: 12/15/2019] [Indexed: 12/25/2022]
Abstract
The ubiquitin-proteasome system (UPS) plays a central role in the degradation of cellular proteins. Targeting protein degradation has been validated as an effective strategy for cancer therapy since 2003. Several components of the UPS have been validated as potential anticancer targets, including 20S proteasomes, 19S proteasome-associated deubiquitinases (DUBs) and ubiquitin ligases (E3s). 20S proteasome inhibitors (such as bortezomib/BTZ and carfilzomib/CFZ) have been approved by the U.S. Food and Drug Administration (FDA) for the treatment of multiple myeloma (MM) and some other liquid tumors. Although survival of MM patients has been improved by the introduction of BTZ-based therapies, these clinical 20S proteasome inhibitors have several limitations, including emergence of resistance in MM patients, neuro-toxicities, and little efficacy in solid tumors. One of strategies to improve the current status of cancer treatment is to repurpose old drugs with UPS-inhibitory properties as new anticancer agents. Old drug reposition represents an attractive drug discovery approach compared to the traditional de novo drug discovery process which is time-consuming and costly. In this review, we summarize status of repurposed inhibitors of various UPS components, including 20S proteasomes, 19S-associated DUBs, and ubiquitin ligase E3s. The original and new mechanisms of action, molecular targets, and potential anticancer activities of these repurposed UPS inhibitors are reviewed, and their new uses including combinational therapies for cancer treatment are discussed.
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Schauer NJ, Magin RS, Liu X, Doherty LM, Buhrlage SJ. Advances in Discovering Deubiquitinating Enzyme (DUB) Inhibitors. J Med Chem 2019; 63:2731-2750. [DOI: 10.1021/acs.jmedchem.9b01138] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Nathan J. Schauer
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Robert S. Magin
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Xiaoxi Liu
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Laura M. Doherty
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
- Department of Systems Biology and Laboratory of Systems Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Sara J. Buhrlage
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
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18
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Seo D, Jung SM, Park JS, Lee J, Ha J, Kim M, Park SH. The deubiquitinating enzyme PSMD14 facilitates tumor growth and chemoresistance through stabilizing the ALK2 receptor in the initiation of BMP6 signaling pathway. EBioMedicine 2019; 49:55-71. [PMID: 31685442 PMCID: PMC7113187 DOI: 10.1016/j.ebiom.2019.10.039] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 09/23/2019] [Accepted: 10/21/2019] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Although bone morphogenetic protein 6 (BMP6) signaling pathway has been implicated in many types of cancer, its role of tumorigenesis seems to be controversial and its ubiquitin-modifying mechanisms have not been fully addressed. Our study was designed to investigate how BMP6 signaling pathway is regulated by ubiquitin-modifying systems and to address molecular and clinical significance in colorectal cancers. METHODS Human deubiquitnase (DUB) siRNA library was used to screen the specific DUB, named PSMD14, involved in BMP6 signaling pathway. Immunoblot, immunoprecipitation and ubiquitination assays were used to analyze targets of the PSMD14. A role of PSMD14-mediated BMP6 signaling pathway for malignant cancer progression was investigated using in vitro and in vivo model of colorectal cancers as well as clinical samples of colorectal cancer patients. FINDINGS The deubiquitinase PSMD14 acts as a positive regulator for the initiation of the BMP6 signaling pathway through deubiquitinating K48-linked ALK2 type I receptor ubiquitination mediated by Smurf1 E3 ligase, resulting in increased stability of the ALK2. This role of PSMD14 is independent of its intrinsic role in the 26S proteasome system. Furthermore, either PSMD14 or ALK2 depletion significantly decreases tumorigenesis of HCT116 colorectal cancer cells in a xenograft model as well as cancer stemness/chemoresistance, and expression of the PSMD14 and ALK2 gene are correlated with malignant progression and the survival of colorectal cancer patients. INTERPRETATION These findings suggest that the PSMD14-ALK2 axis plays an essential role in initiation of the BMP6 signaling pathway and contributes to tumorigenesis and chemoresistance of colorectal cancers.
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Affiliation(s)
- Dongyeob Seo
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Su Myung Jung
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jin Seok Park
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jaewon Lee
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jihoon Ha
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Minbeom Kim
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Seok Hee Park
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
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Yu W, Li J, Wang Q, Wang B, Zhang L, Liu Y, Tang M, Xu G, Yang Z, Wang X, Zhang J, Liu Y, Shi G. Targeting POH1 inhibits prostate cancer cell growth and enhances the suppressive efficacy of androgen deprivation and docetaxel. Prostate 2019; 79:1304-1315. [PMID: 31212367 DOI: 10.1002/pros.23838] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 04/15/2019] [Accepted: 05/03/2019] [Indexed: 01/20/2023]
Abstract
BACKGROUND POH1, a member of the JAMM domain containing deubiquitinases, functions in malignant progression of certain types of cancer. However, the role of POH1 in prostate cancer (PCa) remains unclear. METHODS We performed RNA interference against the JAMM members in PC3 cells and analyzed cell proliferation. POH1 knockdown was established to evaluate the effects of POH1 on cell growth in vitro and in vivo. RNA-sequencing was utilized to explore the molecular details underlying the biological function of POH1 in PCa. The expression of POH1 in PCa tissues was detected by immunohistochemistry. The POH1 inhibitor capzimin was evaluated to explore whether pharmacologically inhibiting POH1 significantly affected PCa cell proliferation alone or enhanced the inhibitory efficacy of docetaxel and androgen deprivation. RESULTS Functional analyses identified POH1 as a JAMM deubiquitinase that is required for PCa proliferation. Importantly, expression of POH1 was higher in human PCa tissues (PCas) than that in normal prostate tissues, and a positive correlation was detected between elevated POH1 expression and higher pathological grades in PCas. In vivo experiments further demonstrated that depleting POH1 significantly suppressed the growth of PCa cell xenografts. POH1 deficiency profoundly inhibited the expression of a set of genes involving the cell cycle and caused G0/G1 phase arrest. Furthermore, the POH1 inhibitor capzimin phenotypically recapitulated the effects of POH1 knockdown and improved the efficacy of docetaxel and androgen deprivation in PCa cells. CONCLUSIONS POH1 was overexpressed in PCas and was correlated with pathological grades in human PCas. Inhibiting POH1 by gene silencing or pharmacological inhibition with capzimin suppressed PCa cell growth. Exploring the inhibition of POH1 in combination with other drugs may provide a strategy to benefit patients with PCa.
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Affiliation(s)
- Wandong Yu
- Department of Urology, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China
| | - Junhong Li
- Department of Urology, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China
| | - Qiang Wang
- Department of Urology, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China
| | - Boshi Wang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Li Zhang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yun Liu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ming Tang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guiqing Xu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhaojuan Yang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xilong Wang
- Department of Urology, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China
| | - Jun Zhang
- Department of Urology, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China
| | - Yongzhong Liu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guowei Shi
- Department of Urology, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China
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Zhong L, Yang X, Zhu Y, Peng J, Cao Y. Radix Tetrastigma Hemsleyani Flavone Suppresses Cutaneous Squamous Cell Carcinoma A431 Cells via Proteasome Inhibition. Med Sci Monit 2019; 25:436-442. [PMID: 30643111 PMCID: PMC6342065 DOI: 10.12659/msm.913889] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Background Radix Tetrastigma Hemsleyani Flavone (RTHF) has detoxification and anti-inflammation activity and is widely used. Here, we report that RTHF inhibits cell proliferation and induces apoptosis in cutaneous squamous cell carcinoma A431 cells and is a potential strategy for cancer therapy. Material/Methods A431 cells were cultured in different concentrations of RTHF. The inhibition of cell proliferation was assessed by MTT assay, cell apoptosis was shown through FCM, and cell invasion was assessed by Transwell methods. Enzyme proteasome assay was used to detect the activity of proteasome and DUB. Expression of apoptosis-related and ubiquitin proteasome pathway-associated proteins were assessed by PCR and Western blot. Results RTHF obviously suppressed the proliferation and induced apoptosis of A431 cells in a dose-dependent manner. Transwell assay showed that RTHF inhibited the cell metastasis significantly. Enzyme proteasome assay show that the RTHF treatment of activity of proteasome and DUB was significantly lower than in control. RTHF increased the expression of Bax and inhibited Bcl-2, pro-caspase3, and pro-caspase9 activity. The expression of USP14, UCHL5, and POH1 decreased and ub-prs increased significantly in the treatment group. Conclusions Our study reveals that RTHF-mediated inhibition of DUBs and proteasome may provide a potential strategy for cancer therapy.
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Affiliation(s)
- Liangrui Zhong
- Department of Dermatology, Zhejiang Hospital of Traditional Chinese Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China (mainland)
| | - Xiaohong Yang
- Department of Dermatology, Zhejiang Hospital of Traditional Chinese Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China (mainland)
| | - Yiping Zhu
- Department of Dermatology, The Third People's Hospital in Hangzhou Affiliated to Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China (mainland)
| | - Jianzhong Peng
- Department of Dermatology, The Third People's Hospital in Hangzhou Affiliated to Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China (mainland)
| | - Yi Cao
- Department of Dermatology, Zhejiang Hospital of Traditional Chinese Medicine, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China (mainland)
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Chen X, Yang Q, Xiao L, Tang D, Dou QP, Liu J. Metal-based proteasomal deubiquitinase inhibitors as potential anticancer agents. Cancer Metastasis Rev 2018; 36:655-668. [PMID: 29039082 PMCID: PMC5721122 DOI: 10.1007/s10555-017-9701-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Deubiquitinases (DUBs) play an important role in protein quality control in eukaryotic cells due to their ability to specifically remove ubiquitin from substrate proteins. Therefore, recent findings have focused on the relevance of DUBs to cancer development, and pharmacological intervention on these enzymes has become a promising strategy for cancer therapy. In particular, several DUBs are physically and/or functionally associated with the proteasome and are attractive targets for the development of novel anticancer drugs. The successful clinical application of cisplatin in cancer treatment has prompted researchers to develop various metal-based anticancer agents with new properties. Recently, we have reported that several metal-based drugs, such as the antirheumatic gold agent auranofin (AF), the antifouling paint biocides copper pyrithione (CuPT) and zinc pyrithione (ZnPT), and also our two synthesized complexes platinum pyrithione (PtPT) and nickel pyrithione (NiPT), can target the proteasomal DUBs UCHL5 and USP14. In this review, we summarize the recently reported small molecule inhibitors of proteasomal DUBs, with a focus on discussion of the unique nature of metal-based proteasomal DUB inhibitors and their anticancer activity.
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Affiliation(s)
- Xin Chen
- Protein Modification and Degradation Lab, School of Basic Medical Sciences, Affiliated Tumor Hospital of Guangzhou Medical University, Guangzhou, China
| | - Qianqian Yang
- Protein Modification and Degradation Lab, School of Basic Medical Sciences, Affiliated Tumor Hospital of Guangzhou Medical University, Guangzhou, China
| | - Lu Xiao
- Protein Modification and Degradation Lab, School of Basic Medical Sciences, Affiliated Tumor Hospital of Guangzhou Medical University, Guangzhou, China
| | - Daolin Tang
- Protein Modification and Degradation Lab, School of Basic Medical Sciences, Affiliated Tumor Hospital of Guangzhou Medical University, Guangzhou, China.,Department of Surgery, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Q Ping Dou
- Protein Modification and Degradation Lab, School of Basic Medical Sciences, Affiliated Tumor Hospital of Guangzhou Medical University, Guangzhou, China.,The Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Detroit, USA.,Department of Oncology, Pharmacology and Pathology, School of Medicine, Wayne State University, Detroit, MI, 48201-2013, USA
| | - Jinbao Liu
- Protein Modification and Degradation Lab, School of Basic Medical Sciences, Affiliated Tumor Hospital of Guangzhou Medical University, Guangzhou, China.
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22
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Wang CH, Lu SX, Liu LL, Li Y, Yang X, He YF, Chen SL, Cai SH, Wang H, Yun JP. POH1 Knockdown Induces Cancer Cell Apoptosis via p53 and Bim. Neoplasia 2018; 20:411-424. [PMID: 29573636 PMCID: PMC5915990 DOI: 10.1016/j.neo.2018.02.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 02/13/2018] [Accepted: 02/19/2018] [Indexed: 12/02/2022] Open
Abstract
The ubiquitin-proteasome system is implicated in cell apoptosis that is frequently dysregulated in human cancers. POH1/rpn11/PSMD14, as a part of the 19S proteasomal subunit, contributes to the progression of malignancy, but its role in apoptosis remains unclear. Here, we showed that POH1 expression was increased and associated with poor outcomes in three independent cohorts of patients with hepatocellular carcinoma (HCC), esophageal cancer (EC), and colorectal cancer (CRC). The knockdown of POH1 significantly inhibited tumor cell proliferation and induced apoptosis mediated by the mitochondrial pathway in vitro. Intratumoral injection of POH1 small interfering RNA (siRNA) significantly reduced the progression of tumor growth and induced apoptosis in vivo. Furthermore, p53 or Bim siRNA markedly attenuated the apoptosis induced by POH1 depletion. POH1 depletion resulted in cell apoptosis by increasing the stability of p53 and Bim and inhibiting their ubiquitination. Overall, POH1 knockdown induced cell apoptosis through increased expression of p53 and Bim via enhanced protein stability and attenuated degradation. Thus, POH1 may serve as a potential prognostic marker and therapeutic target in human cancers.
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Affiliation(s)
- Chun-Hua Wang
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Shi-Xun Lu
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Li-Li Liu
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Yong Li
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Xia Yang
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Yang-Fan He
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Shi-Lu Chen
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Shao-Hang Cai
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Hong Wang
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
| | - Jing-Ping Yun
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, 651# Dong Feng Road East, Guangzhou 510060, China; Department of Pathology, Sun Yat-sen University Cancer Center, 651# Dong Feng Road East, Guangzhou 510060, China.
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23
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Zhu R, Liu Y, Zhou H, Li L, Li Y, Ding F, Cao X, Liu Z. Deubiquitinating enzyme PSMD14 promotes tumor metastasis through stabilizing SNAIL in human esophageal squamous cell carcinoma. Cancer Lett 2018; 418:125-134. [PMID: 29331416 DOI: 10.1016/j.canlet.2018.01.025] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 12/20/2017] [Accepted: 01/08/2018] [Indexed: 12/15/2022]
Abstract
The epithelial-mesenchymal transition (EMT) transcription factor SNAIL is associated with distant metastasis and poor prognosis of esophageal squamous cell carcinoma (ESCC) patients. The proteolysis of SNAIL is mediated by the ubiquitin-proteasome system. Several E3 ligases have been characterized to promote SNAIL ubiquitination and degradation. However, the reverse process - deubiquitination of SNAIL remains largely unknown. In this study, we performed a mass spectrometry to examine the interaction between SNAIL and deubiquitinating enzyme(s). Subsequently, the deubiquitinating enzyme PSMD14 was identified to target SNAIL for deubiquitination and stabilization. Furthermore, knockdown of PSMD14 significantly blocks SNAIL-induced EMT and then suppresses tumor cell migration and invasion in vitro and tumor metastasis in vivo. In addition, the high expression level of PSMD14 predicts poor prognosis for esophageal cancer patients. These findings suggest PSMD14 as a bona fide deubiquitinating enzyme to regulate SNAIL at the post-translational level and provide a promising therapeutic strategy against tumor metastasis of esophageal cancer.
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Affiliation(s)
- Rui Zhu
- State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, PR China
| | - Yongshuo Liu
- State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, PR China; Department of Clinical Laboratory, Binzhou Medical University Hospital, Binzhou, Shandong 256603, PR China
| | - Honghong Zhou
- State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, PR China
| | - Lei Li
- State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, PR China
| | - Yi Li
- State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, PR China
| | - Fang Ding
- State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, PR China
| | - Xiufeng Cao
- Department of Surgical Oncology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China
| | - Zhihua Liu
- State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, PR China.
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24
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de Poot SAH, Tian G, Finley D. Meddling with Fate: The Proteasomal Deubiquitinating Enzymes. J Mol Biol 2017; 429:3525-3545. [PMID: 28988953 DOI: 10.1016/j.jmb.2017.09.015] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/20/2017] [Accepted: 09/26/2017] [Indexed: 01/06/2023]
Abstract
Three deubiquitinating enzymes-Rpn11, Usp14, and Uch37-are associated with the proteasome regulatory particle. These enzymes allow proteasomes to remove ubiquitin from substrates before they are translocated into the core particle to be degraded. Although the translocation channel is too narrow for folded proteins, the force of translocation unfolds them mechanically. As translocation proceeds, ubiquitin chains bound to substrate are drawn to the channel's entry port, where they can impede further translocation. Rpn11, situated over the port, can remove these chains without compromising degradation because substrates must be irreversibly committed to degradation before Rpn11 acts. This coupling between deubiquitination and substrate degradation is ensured by the Ins-1 loop of Rpn11, which controls ubiquitin access to its catalytic site. In contrast to Rpn11, Usp14 and Uch37 can rescue substrates from degradation by promoting substrate dissociation from the proteasome prior to the commitment step. Uch37 is unique in being a component of both the proteasome and a second multisubunit assembly, the INO80 complex. However, only recruitment into the proteasome activates Uch37. Recruitment to the proteasome likewise activates Usp14. However, the influence of Usp14 on the proteasome depends on the substrate, due to its marked preference for proteins that carry multiple ubiquitin chains. Usp14 exerts complex control over the proteasome, suppressing proteasome activity even when inactive in deubiquitination. A major challenge for the field will be to elucidate the specificities of Rpn11, Usp14, and Uch37 in greater depth, employing not only model in vitro substrates but also their endogenous targets.
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Affiliation(s)
- Stefanie A H de Poot
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Geng Tian
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Daniel Finley
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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25
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Blockade of deubiquitylating enzyme Rpn11 triggers apoptosis in multiple myeloma cells and overcomes bortezomib resistance. Oncogene 2017; 36:5631-5638. [PMID: 28581522 DOI: 10.1038/onc.2017.172] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/03/2017] [Accepted: 05/01/2017] [Indexed: 12/11/2022]
Abstract
Proteasome inhibition is an effective therapy for multiple myeloma (MM) patients; however, the emergence of drug resistance is common. Novel therapeutic strategies to overcome proteasome inhibitor resistance are needed. In this study, we examined whether targeting deubiquitylating (DUB) enzymes upstream of 20S proteasome overcomes proteasome inhibitor resistance. Gene expression analysis, immunohistochemical studies of MM patient bone marrow, reverse transcription-PCR and protein analysis show that Rpn11/POH1, a DUB enzyme upstream of 20S proteasome, is more highly expressed in patient MM cells than in normal plasma cells. Importantly, Rpn11 expression directly correlates with poor patient survival. Loss-of-function studies show that Rpn11-siRNA knockdown decreases MM cell viability. Pharmacological inhibition of Rpn11 with O-phenanthroline (OPA) blocks cellular proteasome function, induces apoptosis in MM cells and overcomes resistance to proteasome inhibitor bortezomib. Mechanistically, Rpn11 inhibition in MM cells activates caspase cascade and endoplasmic stress response signaling. Human MM xenograft model studies demonstrate that OPA treatment reduces progression of tumor growth and prolongs survival in mice. Finally, blockade of Rpn11 increases the cytotoxic activity of anti-MM agents lenalidomide, pomalidomide or dexamethasone. Overall, our preclinical data provide the rationale for targeting DUB enzyme Rpn11 upstream of 20S proteasome to enhance cytotoxicity and overcome proteasome inhibitor resistance in MM.
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26
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Luo G, Hu N, Xia X, Zhou J, Ye C. RPN11 deubiquitinase promotes proliferation and migration of breast cancer cells. Mol Med Rep 2017; 16:331-338. [PMID: 28535005 DOI: 10.3892/mmr.2017.6587] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 02/21/2017] [Indexed: 11/06/2022] Open
Abstract
The deubiquitinase enzyme RPN11 is involved in oncogenesis in various types of cancer. However, in breast cancer, the expression levels, prognostic relevance and biological function of RPN11 remains unclear. In the present study, RPN11 expression levels in breast cancer tissues and adjacent non‑tumor tissues were determined by reverse transcription‑quantitative polymerase chain reaction and immunohistochemical staining, and the association of RPN11 with clinicopathological features of breast cancer was evaluated. RPN11 expression was upregulated in breast cancer tissues compared with healthy tissues. Additionally, high expression levels of RPN11 may be an indicator of poor prognosis, as validated by a breast cancer cohort from the Gene Expression Omnibus database. Knockdown of RPN11 in MDA‑MB‑231 and T47D cells significantly reduced cell proliferation and enhanced G0/G1 arrest and apoptosis. Exogenous overexpression of RPN11 in MCF7 and Hs578T cells promoted cell growth and inhibited apoptosis. In addition, knockdown of RPN11 abrogated cell migration and reduced epithelial‑mesenchymal transition. In conclusion, these findings suggested that RPN11 may function as an oncogene and its upregulation in breast cancer suggests that it may be a therapeutic target.
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Affiliation(s)
- Guoqing Luo
- Breast Center, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
| | - Ningdong Hu
- The First Zone of Cardiothoracic Department, Qingyuan People's Hospital, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan, Guangdong 511518, P.R. China
| | - Xu Xia
- The First Zone of Cardiothoracic Department, Qingyuan People's Hospital, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan, Guangdong 511518, P.R. China
| | - Jingjing Zhou
- The First Zone of Cardiothoracic Department, Qingyuan People's Hospital, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan, Guangdong 511518, P.R. China
| | - Changsheng Ye
- Breast Center, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
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27
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Li J, Yakushi T, Parlati F, Mackinnon AL, Perez C, Ma Y, Carter KP, Colayco S, Magnuson G, Brown B, Nguyen K, Vasile S, Suyama E, Smith LH, Sergienko E, Pinkerton AB, Chung TDY, Palmer AE, Pass I, Hess S, Cohen SM, Deshaies RJ. Capzimin is a potent and specific inhibitor of proteasome isopeptidase Rpn11. Nat Chem Biol 2017; 13:486-493. [PMID: 28244987 DOI: 10.1038/nchembio.2326] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/23/2017] [Indexed: 12/28/2022]
Abstract
The proteasome is a vital cellular machine that maintains protein homeostasis, which is of particular importance in multiple myeloma and possibly other cancers. Targeting of proteasome 20S peptidase activity with bortezomib and carfilzomib has been widely used to treat myeloma. However, not all patients respond to these compounds, and those who do eventually suffer relapse. Therefore, there is an urgent and unmet need to develop new drugs that target proteostasis through different mechanisms. We identified quinoline-8-thiol (8TQ) as a first-in-class inhibitor of the proteasome 19S subunit Rpn11. A derivative of 8TQ, capzimin, shows >5-fold selectivity for Rpn11 over the related JAMM proteases and >2 logs selectivity over several other metalloenzymes. Capzimin stabilized proteasome substrates, induced an unfolded protein response, and blocked proliferation of cancer cells, including those resistant to bortezomib. Proteomic analysis revealed that capzimin stabilized a subset of polyubiquitinated substrates. Identification of capzimin offers an alternative path to develop proteasome inhibitors for cancer therapy.
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Affiliation(s)
- Jing Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Tanya Yakushi
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, California, USA
| | - Francesco Parlati
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Andrew L Mackinnon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Christian Perez
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Yuyong Ma
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Kyle P Carter
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, Colorado, USA
| | - Sharon Colayco
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Gavin Magnuson
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Brock Brown
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Kevin Nguyen
- Sanford-Burnham Center for Chemical Genomics at Sanford-Burnham Medical Research Institute Lake Nona, Orlando, Florida, USA
| | - Stefan Vasile
- Sanford-Burnham Center for Chemical Genomics at Sanford-Burnham Medical Research Institute Lake Nona, Orlando, Florida, USA
| | - Eigo Suyama
- Sanford-Burnham Center for Chemical Genomics at Sanford-Burnham Medical Research Institute Lake Nona, Orlando, Florida, USA
| | - Layton H Smith
- Sanford-Burnham Center for Chemical Genomics at Sanford-Burnham Medical Research Institute Lake Nona, Orlando, Florida, USA
| | - Eduard Sergienko
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Anthony B Pinkerton
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Thomas D Y Chung
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Amy E Palmer
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, Colorado, USA
| | - Ian Pass
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Sonja Hess
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, California, USA
| | - Seth M Cohen
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Raymond J Deshaies
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California, USA
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28
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Bista R, Lee DW, Pepper OB, Azorsa DO, Arceci RJ, Aleem E. Disulfiram overcomes bortezomib and cytarabine resistance in Down-syndrome-associated acute myeloid leukemia cells. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2017; 36:22. [PMID: 28143565 PMCID: PMC5286849 DOI: 10.1186/s13046-017-0493-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 01/26/2017] [Indexed: 02/02/2023]
Abstract
Background Children with Down syndrome (DS) have increased risk for developing AML (DS-AMKL), and they usually experience severe therapy-related toxicities compared to non DS-AMKL. Refractory/relapsed disease has very poor outcome, and patients would benefit from novel, less toxic, therapeutic strategies that overcome resistance. Relapse/resistance are linked to cancer stem cells with high aldehyde dehydrogenase (ALDH) activity. The purpose of the present work was to study less toxic alternative therapeutic agents for relapsed/refractory DS-AMKL. Methods Fourteen AML cell lines including the DS-AMKL CMY and CMK from relapsed/refractory AML were used. Cytarabine (Ara-C), bortezomib (BTZ), disulfiram/copper (DSF/Cu2+) were evaluated for cytotoxicity, depletion of ALDH-positive cells, and resistance. BTZ-resistant CMY and CMK variants were generated by continuous BTZ treatment. Cell viability was assessed using CellTiter-Glo®, ALDH activity by ALDELUORTM, and proteasome inhibition by western blot of ubiquitinated proteins and the Proteasome-Glo™ Chymotrypsin-Like (CT-like) assay, apoptosis by Annexin V Fluos/Propidium iodide staining, and mutations were detected using PCR, cloning and sequencing. Results Ara-C-resistant AML cell lines were sensitive to BTZ and DSF/Cu2+. The Ara-C-resistant DS-AMKL CMY cells had a high percentage of ALDHbright “stem-like” populations that may underlie Ara-C resistance. One percent of these cells were still resistant to BTZ but sensitive to DSF/Cu2+. To understand the mechanism of BTZ resistance, BTZ resistant (CMY-BR) and (CMK-BR) were generated. A novel mutation PSMB5 Q62P underlied BTZ resistance, and was associated with an overexpression of the β5 proteasome subunit. BTZ-resistance conferred increased resistance to Ara-C due to G1 arrest in the CMY-BR cells, which protected the cells from S-phase damage by Ara-C. CMY-BR and CMK-BR cells were cross-resistant to CFZ and MG-132 but sensitive to DSF/Cu2+. In this setting, DSF/Cu2+ induced apoptosis and proteasome inhibition independent of CT-like activity inhibition. Conclusions We provide evidence that DSF/Cu2+ overcomes Ara-C and BTZ resistance in cell lines from DS-AMKL patients. A novel mutation underlying BTZ resistance was detected that may identify BTZ-resistant patients, who may not benefit from treatment with CFZ or Ara-C, but may be responsive to DSF/Cu2+. Our findings support the clinical development of DSF/Cu2+ as a less toxic efficacious treatment approach in patients with relapsed/refractory DS-AMKL. Electronic supplementary material The online version of this article (doi:10.1186/s13046-017-0493-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ranjan Bista
- Institute of Molecular Medicine at Phoenix Children's Hospital, Phoenix, AZ, USA
| | - David W Lee
- Institute of Molecular Medicine at Phoenix Children's Hospital, Phoenix, AZ, USA.,Department of Child Health, University of Arizona College of Medicine-Phoenix, Biosciences Partnership Building (BSPB), 5th floor, 475 N 5th Street, Phoenix, AZ, 85004, USA
| | - Oliver B Pepper
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Biosciences Partnership Building (BSPB), 5th floor, 475 N 5th Street, Phoenix, AZ, 85004, USA.,Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - David O Azorsa
- Institute of Molecular Medicine at Phoenix Children's Hospital, Phoenix, AZ, USA.,Department of Child Health, University of Arizona College of Medicine-Phoenix, Biosciences Partnership Building (BSPB), 5th floor, 475 N 5th Street, Phoenix, AZ, 85004, USA
| | - Robert J Arceci
- Institute of Molecular Medicine at Phoenix Children's Hospital, Phoenix, AZ, USA.,Department of Child Health, University of Arizona College of Medicine-Phoenix, Biosciences Partnership Building (BSPB), 5th floor, 475 N 5th Street, Phoenix, AZ, 85004, USA
| | - Eiman Aleem
- Institute of Molecular Medicine at Phoenix Children's Hospital, Phoenix, AZ, USA. .,Department of Child Health, University of Arizona College of Medicine-Phoenix, Biosciences Partnership Building (BSPB), 5th floor, 475 N 5th Street, Phoenix, AZ, 85004, USA. .,Department of Zoology, Faculty of Science, Alexandria University, Alexandria, Egypt.
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29
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Singh SK, Sahu I, Mali SM, Hemantha HP, Kleifeld O, Glickman MH, Brik A. Synthetic Uncleavable Ubiquitinated Proteins Dissect Proteasome Deubiquitination and Degradation, and Highlight Distinctive Fate of Tetraubiquitin. J Am Chem Soc 2016; 138:16004-16015. [PMID: 27960333 DOI: 10.1021/jacs.6b09611] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Various hypotheses have been proposed regarding how chain length, linkage type, position on substrate, and susceptibility to deubiquitinases (DUBs) affect processing of different substrates by proteasome. Here we report a new strategy for the chemical synthesis of ubiquitinated proteins to generate a set of well-defined conjugates bearing an oxime bond between the chain and the substrate. We confirmed that this isopeptide replacement is resistant to DUBs and to shaving by proteasome. Analyzing products generated by proteasomes ranked how chain length governed degradation outcome. Our results support that (1) the cleavage of the proximal isopeptide bond is not a prerequisite for proteasomal degradation, (2) by overcoming trimming at the proteasome, tetraUb is a fundamentally different signal than shorter chains, and (3) the tetra-ubiquitin chain can be degraded with the substrate. Together these results highlight the usefulness of chemistry to dissect the contribution of proteasome-associated DUBs and the complexity of the degradation process.
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Affiliation(s)
- Sumeet K Singh
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology , 3200008 Haifa, Israel
| | - Indrajit Sahu
- Department of Biology Technion-Israel Institute of Technology , 3200008 Haifa, Israel
| | - Sachitanand M Mali
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology , 3200008 Haifa, Israel
| | - Hosahalli P Hemantha
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology , 3200008 Haifa, Israel
| | - Oded Kleifeld
- Department of Biology Technion-Israel Institute of Technology , 3200008 Haifa, Israel
| | - Michael H Glickman
- Department of Biology Technion-Israel Institute of Technology , 3200008 Haifa, Israel
| | - Ashraf Brik
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology , 3200008 Haifa, Israel
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30
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Abstract
This review examines the small molecules described over the past decade as inhibitors of any of the approximately 100 human deubiquitinating enzymes (DUBs). Structures from patent publications as well as from the primary literature are included. Inhibitors of two viral DUBs are also described since these proteases share structural similarity with one of the human DUB sub-families. The structure, function and disease associations of certain DUBs are presented. The evolution of the screening assays used to identify and characterise new inhibitors is discussed. Several emerging trends in the series are highlighted and the ‘drug-likeness’ of the various inhibitors is analysed. Large pharmaceutical company collaborations have drawn attention to this field, and these recent advances are discussed in the context of the wider range of therapeutically important DUB targets.
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Affiliation(s)
- Mark Kemp
- MISSION Therapeutics, Babraham Research Campus, Cambridge, United Kingdom
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31
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Śledź P, Baumeister W. Structure-Driven Developments of 26S Proteasome Inhibitors. Annu Rev Pharmacol Toxicol 2016; 56:191-209. [DOI: 10.1146/annurev-pharmtox-010814-124727] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Paweł Śledź
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany;
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany;
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32
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Wang B, Ma A, Zhang L, Jin WL, Qian Y, Xu G, Qiu B, Yang Z, Liu Y, Xia Q, Liu Y. POH1 deubiquitylates and stabilizes E2F1 to promote tumour formation. Nat Commun 2015; 6:8704. [PMID: 26510456 PMCID: PMC4846323 DOI: 10.1038/ncomms9704] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 09/23/2015] [Indexed: 12/29/2022] Open
Abstract
Hyperactivation of the transcriptional factor E2F1 occurs frequently in human cancers and contributes to malignant progression. E2F1 activity is regulated by proteolysis mediated by the ubiquitin–proteasome system. However, the deubiquitylase that controls E2F1 ubiquitylation and stability remains undefined. Here we demonstrate that the deubiquitylase POH1 stabilizes E2F1 protein through binding to and deubiquitylating E2F1. Conditional knockout of Poh1 alleles results in reduced E2F1 expression in primary mouse liver cells. The POH1-mediated regulation of E2F1 expression strengthens E2F1-downstream prosurvival signals, including upregulation of Survivin and FOXM1 protein levels, and efficiently facilitates tumour growth of liver cancer cells in nude mice. Importantly, human hepatocellular carcinomas (HCCs) recapitulate POH1 regulation of E2F1 expression, as nuclear abundance of POH1 is increased in HCCs and correlates with E2F1 overexpression and tumour growth. Thus, our study suggests that the hyperactivated POH1–E2F1 regulation may contribute to the development of liver cancer. The transcription factor E2F1 controls the expression of multiple genes and is frequently overactivated in cancer. Here, the authors show that E2F1 is deubiquitinated by POH1 and that this enhances the role of E2F1 in cell survival, and contributes to the pathogenesis of liver cancer.
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Affiliation(s)
- Boshi Wang
- State Key laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200032, China
| | - Aihui Ma
- State Key laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200032, China
| | - Li Zhang
- State Key laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200032, China
| | - Wei-Lin Jin
- Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Engineering, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, School of Electronic Information and Electronic Engineering, Shanghai Jiaotong University, Shanghai 200240, China
| | - Yu Qian
- State Key laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200032, China
| | - Guiqin Xu
- State Key laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200032, China
| | - Bijun Qiu
- Department of Liver Surgery, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200217, China
| | - Zhaojuan Yang
- State Key laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200032, China
| | - Yun Liu
- State Key laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200032, China
| | - Qiang Xia
- Department of Liver Surgery, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200217, China
| | - Yongzhong Liu
- State Key laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200032, China
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33
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Inhibition of proteasome deubiquitinase activity: a strategy to overcome resistance to conventional proteasome inhibitors? Drug Resist Updat 2015; 21-22:20-9. [DOI: 10.1016/j.drup.2015.06.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Revised: 06/22/2015] [Accepted: 06/27/2015] [Indexed: 11/19/2022]
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34
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Clinically used antirheumatic agent auranofin is a proteasomal deubiquitinase inhibitor and inhibits tumor growth. Oncotarget 2015; 5:5453-71. [PMID: 24977961 PMCID: PMC4170648 DOI: 10.18632/oncotarget.2113] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Proteasomes are attractive emerging targets for anti-cancer therapies. Auranofin
(Aur), a gold-containing compound clinically used to treat rheumatic arthritis, was
recently approved by US Food and Drug Administration for Phase II clinical trial to
treat cancer but its anti-cancer mechanism is poorly understood. Here we report that
(i) Aur shows proteasome-inhibitory effect that is comparable to that of
bortezomib/Velcade (Vel); (ii) different from bortezomib, Aur inhibits
proteasome-associated deubiquitinases (DUBs) UCHL5 and USP14 rather than the 20S
proteasome; (iii) inhibition of the proteasome-associated DUBs is required for
Aur-induced cytotoxicity; and (iv) Aur selectively inhibits tumor growth in
vivo and induces cytotoxicity in cancer cells from acute myeloid leukemia
patients. This study provides important novel insight into understanding the
proteasome-inhibiting property of metal-containing compounds. Although several DUB
inhibitors were reported, this study uncovers the first drug already used in clinic
that can inhibit proteasome-associated DUBs with promising anti-tumor effects.
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Liu N, Huang H, Dou QP, Liu J. Inhibition of 19S proteasome-associated deubiquitinases by metal-containing compounds. Oncoscience 2015; 2:457-66. [PMID: 26097878 PMCID: PMC4468331 DOI: 10.18632/oncoscience.167] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 05/24/2015] [Indexed: 12/31/2022] Open
Abstract
Copper and gold complexes have clinical activity in several diseases including cancer. Recently, we have reported that the anti-cancer activity of copper (II) pyrithione CuPT and gold (I) complex auranofin is associated with targeting the 19S proteasome-associated deubiquitinases (DUBs), UCHL5 and USP14. Here we discuss metal DUB inhibitors in treating cancer and other diseases. (from Editor). Several copper and gold complexes have clinical activity in treating some human diseases including cancer. Recently, we have reported that the anti-cancer activity of copper (II) pyrithione CuPT and gold (I) complex auranofin is tightly associated with their ability to target and inhibit the 19S proteasome-associated deubiquitinases (DUBs), UCHL5 and USP14. In this article we review small molecule inhibitors of DUBs and 19S proteasome-associated DUBs. We then describe and discuss the ubique nature of CuPT and auranofin, which is inhibition of 19S proteasome-associated UCHL5 and USP14. We finally suggest the potential to develop novel, specific metal-based DUB inhibitors for treating cancer and other diseases.
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Affiliation(s)
- Ningning Liu
- State Key Lab of Respiratory Disease, Protein Modification and Degradation Lab, Department of Pathophysiology, Guangzhou Medical University, Guangdong, China ; Guangzhou Research Institute of Cardiovascular Disease, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Hongbiao Huang
- State Key Lab of Respiratory Disease, Protein Modification and Degradation Lab, Department of Pathophysiology, Guangzhou Medical University, Guangdong, China
| | - Q Ping Dou
- State Key Lab of Respiratory Disease, Protein Modification and Degradation Lab, Department of Pathophysiology, Guangzhou Medical University, Guangdong, China ; The Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, and Departments of Oncology, Pharmacology and Pathology, School of Medicine, Wayne State University, Detroit, Michigan, USA
| | - Jinbao Liu
- State Key Lab of Respiratory Disease, Protein Modification and Degradation Lab, Department of Pathophysiology, Guangzhou Medical University, Guangdong, China
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Deubiquitinase inhibition as a cancer therapeutic strategy. Pharmacol Ther 2015; 147:32-54. [DOI: 10.1016/j.pharmthera.2014.11.002] [Citation(s) in RCA: 200] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 09/16/2014] [Indexed: 12/27/2022]
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Mansour W, Nakasone MA, von Delbrück M, Yu Z, Krutauz D, Reis N, Kleifeld O, Sommer T, Fushman D, Glickman MH. Disassembly of Lys11 and mixed linkage polyubiquitin conjugates provides insights into function of proteasomal deubiquitinases Rpn11 and Ubp6. J Biol Chem 2014; 290:4688-4704. [PMID: 25389291 DOI: 10.1074/jbc.m114.568295] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein homeostasis is largely dependent on proteolysis by the ubiquitin-proteasome system. Diverse polyubiquitin modifications are reported to target cellular proteins to the proteasome. At the proteasome, deubiquitination is an essential preprocessing event that contributes to degradation efficiency. We characterized the specificities of two proteasome-associated deubiquitinases (DUBs), Rpn11 and Ubp6, and explored their impact on overall proteasome DUB activity. This was accomplished by constructing a panel of well defined ubiquitin (Ub) conjugates, including homogeneous linkages of varying lengths as well as a heterogeneously modified target. Rpn11 and Ubp6 processed Lys(11) and Lys(63) linkages with comparable efficiencies that increased with chain length. In contrast, processing of Lys(48) linkages by proteasome was inversely correlated to chain length. Fluorescently labeled tetra-Ub chains revealed endo-chain preference for Ubp6 acting on Lys(48) and random action for Rpn11. Proteasomes were more efficient at deconjugating identical substrates than their constituent DUBs by roughly 2 orders of magnitude. Incorporation into proteasomes significantly enhanced enzymatic efficiency of Rpn11, due in part to alleviation of the autoinhibitory role of its C terminus. The broad specificity of Rpn11 could explain how proteasomes were more effective at disassembling a heterogeneously modified conjugate compared with homogeneous Lys(48)-linked chains. The reduced ability to disassemble homogeneous Lys(48)-linked chains longer than 4 Ub units may prolong residency time on the proteasome.
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Affiliation(s)
- Wissam Mansour
- From the Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Mark A Nakasone
- From the Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel,; the Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland 20742
| | - Maximilian von Delbrück
- the Max-Delbrück-Zentrum für Molekulare Medizin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany, and
| | - Zanlin Yu
- From the Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Daria Krutauz
- From the Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Noa Reis
- From the Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Oded Kleifeld
- the Department of Biochemistry and Molecular Biology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne 3800, Australia
| | - Thomas Sommer
- the Max-Delbrück-Zentrum für Molekulare Medizin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany, and
| | - David Fushman
- the Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland 20742
| | - Michael H Glickman
- From the Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel,.
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38
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Abstract
The ATP-dependent degradation of polyubiquitylated proteins by the 26S proteasome is essential for the maintenance of proteome stability and the regulation of a plethora of cellular processes. Degradation of substrates is preceded by the removal of polyubiquitin moieties through the isopeptidase activity of the subunit Rpn11. Here we describe three crystal structures of the heterodimer of the Mpr1-Pad1-N-terminal domains of Rpn8 and Rpn11, crystallized as a fusion protein in complex with a nanobody. This fusion protein exhibits modest deubiquitylation activity toward a model substrate. Full activation requires incorporation of Rpn11 into the 26S proteasome and is dependent on ATP hydrolysis, suggesting that substrate processing and polyubiquitin removal are coupled. Based on our structures, we propose that premature activation is prevented by the combined effects of low intrinsic ubiquitin affinity, an insertion segment acting as a physical barrier across the substrate access channel, and a conformationally unstable catalytic loop in Rpn11. The docking of the structure into the proteasome EM density revealed contacts of Rpn11 with ATPase subunits, which likely stabilize the active conformation and boost the affinity for the proximal ubiquitin moiety. The narrow space around the Rpn11 active site at the entrance to the ATPase ring pore is likely to prevent erroneous deubiquitylation of folded proteins.
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Dou QP. Deubiquitinating Enzymes as Novel Targets for Cancer Therapies. RESISTANCE TO TARGETED ANTI-CANCER THERAPEUTICS 2014. [PMCID: PMC7123001 DOI: 10.1007/978-3-319-06752-0_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Most ubiquitinated proteins can be recognized and degraded by the 26S proteasome. In the meantime, protein deubiquitination by various deubiquitinating enzymes (DUBs) regulates protein stability within cells, and it can counterbalance intracellular homeostasis mediated by ubiquitination. Numerous reports have demonstrated that an aberrant process of the ubiquitin-proteasome pathway (UPP) regulated by the ubiquitination and deubiquitination systems results in failure of balancing between protein stability and degradation, and this failure can lead to tumorigenesis in various organs and tissues of mammals. The identification of molecular properties for various DUBs is very critical to understand cancer development and tumorigenesis. Therefore, knowledge of DUBs and their association with cancer and diseases is indispensible for developing effective inhibitors for DUBs. This chapter describes various features and functions of cancer-related DUBs. In addition, we summarize several inhibitors that specifically target certain DUBs in cancer and suggest that DUBs may be one of the most ideal and attractive therapeutic targets.
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Affiliation(s)
- Q. Ping Dou
- Wayne State University, Detroit, Michigan USA
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40
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Hao R, Nanduri P, Rao Y, Panichelli RS, Ito A, Yoshida M, Yao TP. Proteasomes activate aggresome disassembly and clearance by producing unanchored ubiquitin chains. Mol Cell 2013; 51:819-28. [PMID: 24035499 DOI: 10.1016/j.molcel.2013.08.016] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 06/11/2013] [Accepted: 08/05/2013] [Indexed: 11/19/2022]
Abstract
Aberrant protein aggregation is a dominant pathological feature in neurodegenerative diseases. Protein aggregates cannot be processed by the proteasome; instead, they are frequently concentrated to the aggresome, a perinuclear inclusion body, and subsequently removed by autophagy. Paradoxically, proteasomes are also concentrated at aggresomes and other related inclusion bodies prevalent in neurodegenerative disease. Here, we show that proteasomes are crucial components in aggresome clearance. The disassembly and disposal of aggresomes requires Poh1, a proteasomal deubiquitinating enzyme that cleaves ubiquitinated proteins and releases ubiquitin chains. In Poh1-deficient cells, aggresome clearance is blocked. Remarkably, microinjection of free lysine (K) 63-linked ubiquitin chains restores aggresome degradation. We present evidence that free ubiquitin chains produced by Poh1 bind and activate the deacetylase HDAC6, which, in turn, stimulates actinomyosin- and autophagy-dependent aggresome processing. Thus, unanchored ubiquitin chains are key signaling molecules that connect and coordinate the proteasome and autophagy to eliminate toxic protein aggregates.
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Affiliation(s)
- Rui Hao
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710, USA
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41
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Stone HR, Morris JR. DNA damage emergency: cellular garbage disposal to the rescue? Oncogene 2013; 33:805-13. [PMID: 23503465 DOI: 10.1038/onc.2013.60] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 12/18/2012] [Accepted: 12/22/2012] [Indexed: 12/19/2022]
Abstract
The proteasome is a cellular machine found in the cytosol, nucleus and on chromatin that performs much of the proteolysis in eukaryotic cells. Recent reports show it is enriched at sites of double-stranded DNA breaks (DSBs) in mammalian cells. What is it doing there? This review will address three possibilities suggested by recent reports: in degrading proteins after their ubiquitination at and eviction from chromatin; as a deubiquitinase, specific to the antagonism of ubiquitin conjugates generated as part of the signalling of a DSB; and as a functional component of DNA repair mechanism itself. These findings add complexity to the proteasome as a potential therapeutic target in cancer treatment.
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Affiliation(s)
- H R Stone
- School of Cancer Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - J R Morris
- School of Cancer Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
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42
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Burrage LC, Eble TN, Hixson PM, Roney EK, Cheung SW, Franco LM. A mosaic 2q24.2 deletion narrows the critical region to a 0.4 Mb interval that includes TBR1, TANK, and PSMD14. Am J Med Genet A 2013; 161A:841-4. [PMID: 23444363 DOI: 10.1002/ajmg.a.35751] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 10/11/2012] [Indexed: 11/11/2022]
Abstract
Interstitial deletions involving 2q24 have been associated with a wide range of phenotypes including intellectual disability and short stature. To date, the smallest common region among reported cases of deletions in this region is approximately 2.65 Mb and contains 15 genes. In the present case report, we describe an 18-year-old male with mild intellectual disability, short stature, and mosaicism for a 0.422 Mb deletion on 2q24.2 that was diagnosed by comparative genomic hybridization and confirmed with fluorescent in situ hybridization (FISH). This deletion, which is present in approximately 61% of cells, includes three genes: TBR1, TANK, and PSMD14. The findings suggest that the critical region for intellectual disability and short stature in 2q24.2 can be narrowed to a 0.422 Mb segment. TBR1, a transcription factor involved in early cortical development, is a strong candidate for the intellectual disability phenotype seen in our patient and in patients with larger deletions in this region of the genome.
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Affiliation(s)
- Lindsay C Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Regulation of pluripotency and cellular reprogramming by the ubiquitin-proteasome system. Cell Stem Cell 2012; 11:783-98. [PMID: 23103054 DOI: 10.1016/j.stem.2012.09.011] [Citation(s) in RCA: 210] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 07/13/2012] [Accepted: 09/17/2012] [Indexed: 11/22/2022]
Abstract
Although transcriptional regulation of stem cell pluripotency and differentiation has been extensively studied, only a small number of studies have addressed the roles for posttranslational modifications in these processes. A key mechanism of posttranslational modification is ubiquitination by the ubiquitin-proteasome system (UPS). Here, using shotgun proteomics, we map the ubiquitinated protein landscape during embryonic stem cell (ESC) differentiation and induced pluripotency. Moreover, using UPS-targeted RNAi screens, we identify additional regulators of pluripotency and differentiation. We focus on two of these proteins, the deubiquitinating enzyme Psmd14 and the E3 ligase Fbxw7, and characterize their importance in ESC pluripotency and cellular reprogramming. This global characterization of the UPS as a key regulator of stem cell pluripotency opens the way for future studies that focus on specific UPS enzymes or ubiquitinated substrates.
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The proteasomal de-ubiquitinating enzyme POH1 promotes the double-strand DNA break response. EMBO J 2012; 31:3918-34. [PMID: 22909820 DOI: 10.1038/emboj.2012.232] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 07/26/2012] [Indexed: 02/06/2023] Open
Abstract
The regulation of Ubiquitin (Ub) conjugates generated by the complex network of proteins that promote the mammalian DNA double-strand break (DSB) response is not fully understood. We show here that the Ub protease POH1/rpn11/PSMD14 resident in the 19S proteasome regulatory particle is required for processing poly-Ub formed in the DSB response. Proteasome activity is required to restrict tudor domain-dependent 53BP1 accumulation at sites of DNA damage. This occurs both through antagonism of RNF8/RNF168-mediated lysine 63-linked poly-Ub and through the promotion of JMJD2A retention on chromatin. Consistent with this role POH1 acts in opposition to RNF8/RNF168 to modulate end-joining DNA repair. Additionally, POH1 acts independently of 53BP1 in homologous recombination repair to promote RAD51 loading. Accordingly, POH1-deficient cells are sensitive to DNA damaging agents. These data demonstrate that proteasomal POH1 is a key de-ubiquitinating enzyme that regulates ubiquitin conjugates generated in response to damage and that several aspects of the DSB response are regulated by the proteasome.
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45
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D'Arcy P, Linder S. Proteasome deubiquitinases as novel targets for cancer therapy. Int J Biochem Cell Biol 2012; 44:1729-38. [PMID: 22819849 DOI: 10.1016/j.biocel.2012.07.011] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 07/10/2012] [Accepted: 07/11/2012] [Indexed: 12/27/2022]
Abstract
The ubiquitin-proteasome system (UPS) is a conserved pathway regulating numerous biological processes including protein turnover, DNA repair, and intracellular trafficking. Tumor cells are dependent on a functioning UPS, making it an ideal target for the development of novel anti-cancer therapies. The development of bortezomib (Velcade(®)) as a treatment for multiple myeloma and mantle cell lymphoma has verified this and suggests that targeting other components of the UPS may be a viable strategy for the treatment for cancer. We recently described a novel class of proteasome inhibitors that function by an alternative mechanism of action (D'Arcy et al., 2011). The small molecule b-AP15 blocks the deubiquitinase (DUB) activity of the 19S regulatory particle (19S RP) without inhibiting the proteolytic activities of the 20S core particle (20S CP). b-AP15 inhibits two proteasome-associated DUBs, USP14 and UCHL5, resulting in a rapid accumulation of high molecular weight ubiquitin conjugates and a functional proteasome shutdown. Interestingly, b-AP15 displays several differences to bortezomib including insensitivity to over-expression of the anti-apoptotic mediator Bcl-2 and anti-tumor activity in solid tumor models. In this review we will discuss the potential of proteasome deubiquitinase inhibitors as additions to the therapeutic arsenal against cancer.
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Affiliation(s)
- Pádraig D'Arcy
- Institute for Oncology-Pathology, Cancer Center Karolinska, Karolinska Institute, 17176 Stockholm, Sweden.
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46
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Schmitt SM, Frezza M, Dou QP. New applications of old metal-binding drugs in the treatment of human cancer. Front Biosci (Schol Ed) 2012; 4:375-91. [PMID: 22202066 DOI: 10.2741/274] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Significant advances in the use of metal complexes, precipitated by platinum, have fostered a renewed interest in harnessing their rich potential in the treatment of cancer. In addition to platinum-based complexes, the anticancer properties of other metals such as ruthenium have been realized, and ruthenium-based compounds are currently being investigated in clinical trials. Since the process of drug development can be expensive and cumbersome, finding new applications of existing drugs may provide effective means to expedite the regulatory process in bringing new drugs to the clinical setting. Encouraging findings from laboratory studies reveal significant anticancer activity from different classes of metal-chelating compounds, such as disulfiram, clioquinol, and dithiocarbamate derivatives that are currently approved for the treatment of various pathological disorders. Their use as coordination complexes with metals such as copper, zinc, and gold that target the ubiquitin-proteasome pathway have shown significant promise as potential anticancer agents. This review discusses the unique role of several selected metals in relation to their anti-cancer properties as well as the new therapeutic potential of several previously approved metal-chelating drugs. In vitro and in vivo experimental evidence along with mechanisms of action (e.g., via targeting the tumor proteasome) will also be discussed with anticipation of strengthening this exciting new concept.
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Affiliation(s)
- Sara M Schmitt
- Barbara Ann Karmanos Cancer Institute, School of Medicine, Wayne State University, Detroit, Michigan 48201, USA
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Abstract
In May 2003, the US Food and Drug Administration (FDA) granted accelerated approval for the use of the first-in-class proteasome inhibitor bortezomib as a third-line therapy in multiple myeloma, and the European Union followed suit a year later. Bortezomib has subsequently been approved for multiple myeloma as a second-line treatment on its own and as a first-line therapy in combination with an alkylating agent and a corticosteroid. Furthermore, bortezomib has also been approved as a second-line therapy for mantle cell lymphoma. In this chapter, the focus is on the current clinical research on bortezomib, its adverse effects, and the resistance of multiple myeloma patients to bortezomib-based therapy. The various applications of bortezomib in different diseases and recent advances in the development of a new generation of inhibitors that target the proteasome or other parts of the ubiquitin-proteasome system are also reviewed.
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Affiliation(s)
- Boris Cvek
- Department of Cell Biology & Genetics, Palacky University, Olomouc, Czech Republic
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48
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Mulenga A, Erikson K. A snapshot of the Ixodes scapularis degradome. Gene 2011; 482:78-93. [PMID: 21596113 DOI: 10.1016/j.gene.2011.04.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/04/2011] [Accepted: 04/15/2011] [Indexed: 01/19/2023]
Abstract
Parasitic encoded proteases are essential to regulating interactions between parasites and their hosts and thus they represent attractive anti-parasitic druggable and/or vaccine target. We have utilized annotations of Ixodes scapularis proteases in gene bank and version 9.3 MEROPS database to compile an index of at least 233 putatively active and 150 putatively inactive protease enzymes that are encoded by the I. scapularis genome. The 233 putatively active protease homologs hereafter referred to as the degradome (the full repertoire of proteases encoded by the I. scapularis genome) represent ~1.14% of the 20485 putative I. scapularis protein content. Consistent with observations in other animals, the content of the I. scapularis degradome is ~6.0% (14/233) aspartic, ~19% (44/233) cysteine, ~40% (93/233) metallo, ~28.3% (66/233) serine and ~6.4% (15/233) threonine proteases. When scanned against other tick sequences, ~11% (25/233) of I. scapularis putatively active proteases are conserved in other tick species with ≥ 60% amino acid identity levels. The I. scapularis genome does not apparently encode for putatively inactive aspartic proteases. Of the 150 putative inactive protease homologs none are from the aspartic protease class, ~8% (12/150) are cysteine, ~58.7% (88/150) metallo, 30% (45/150) serine and ~3.3% (5/150) are threonine proteases. The I. scapularis tick genome appears to have evolutionarily lost proteolytic activity of at least 6 protease families, C56 and C64 (cysteine), M20 and M23 (metallo), S24 and S28 (serine) as revealed by a lack of the putatively active proteases in these families. The overall protease content is comparable to other organisms. However, the paucity of the S1 chymotrypsin/trypsin-like serine protease family in the I. scapularis genome where it is ~12.7% (28/233) of the degradome as opposed to ~22-48% content in other blood feeding arthropods, Pediculus humanus humanus, Anopheles gambiae, Aedes Aegypti and Culex pipiens quinquefasciatus is notable. The data is presented as a one-stop index of proteases encoded by the I. scapularis genome.
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Affiliation(s)
- Albert Mulenga
- Texas A & M University AgriLife Research, Department of Entomology, College Station, TX 77843, USA.
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49
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Frezza M, Hindo S, Chen D, Davenport A, Schmitt S, Tomco D, Dou QP. Novel metals and metal complexes as platforms for cancer therapy. Curr Pharm Des 2011; 16:1813-25. [PMID: 20337575 DOI: 10.2174/138161210791209009] [Citation(s) in RCA: 344] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Accepted: 03/22/2010] [Indexed: 12/17/2022]
Abstract
Metals are essential cellular components selected by nature to function in several indispensable biochemical processes for living organisms. Metals are endowed with unique characteristics that include redox activity, variable coordination modes, and reactivity towards organic substrates. Due to their reactivity, metals are tightly regulated under normal conditions and aberrant metal ion concentrations are associated with various pathological disorders, including cancer. For these reasons, coordination complexes, either as drugs or prodrugs, become very attractive probes as potential anticancer agents. The use of metals and their salts for medicinal purposes, from iatrochemistry to modern day, has been present throughout human history. The discovery of cisplatin, cis-[Pt(II) (NH(3))(2)Cl(2)], was a defining moment which triggered the interest in platinum(II)- and other metal-containing complexes as potential novel anticancer drugs. Other interests in this field address concerns for uptake, toxicity, and resistance to metallodrugs. This review article highlights selected metals that have gained considerable interest in both the development and the treatment of cancer. For example, copper is enriched in various human cancer tissues and is a co-factor essential for tumor angiogenesis processes. However the use of copper-binding ligands to target tumor copper could provide a novel strategy for cancer selective treatment. The use of nonessential metals as probes to target molecular pathways as anticancer agents is also emphasized. Finally, based on the interface between molecular biology and bioinorganic chemistry the design of coordination complexes for cancer treatment is reviewed and design strategies and mechanisms of action are discussed.
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Affiliation(s)
- Michael Frezza
- Barbara Ann Karmanos Cancer Institute, Department of Oncology and Pathology, School of Medicine, Wayne State University, Detroit, Michigan 48201, USA
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50
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Abstract
The proteasome is an intricate molecular machine, which serves to degrade proteins following their conjugation to ubiquitin. Substrates dock onto the proteasome at its 19-subunit regulatory particle via a diverse set of ubiquitin receptors and are then translocated into an internal chamber within the 28-subunit proteolytic core particle (CP), where they are hydrolyzed. Substrate is threaded into the CP through a narrow gated channel, and thus translocation requires unfolding of the substrate. Six distinct ATPases in the regulatory particle appear to form a ring complex and to drive unfolding as well as translocation. ATP-dependent, degradation-coupled deubiquitination of the substrate is required both for efficient substrate degradation and for preventing the degradation of the ubiquitin tag. However, the proteasome also contains deubiquitinating enzymes (DUBs) that can remove ubiquitin before substrate degradation initiates, thus allowing some substrates to dissociate from the proteasome and escape degradation. Here we examine the key elements of this molecular machine and how they cooperate in the processing of proteolytic substrates.
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Affiliation(s)
- Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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