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Eid AT, Eid KT, Odom JV, Hinkle D, Leys M. Autosomal Dominant Retinitis Pigmentosa Secondary to TOPORS Mutations: A Report of a Novel Mutation and Clinical Findings. J Clin Med 2024; 13:1498. [PMID: 38592336 PMCID: PMC10934045 DOI: 10.3390/jcm13051498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 04/10/2024] Open
Abstract
Purpose: Mutations in Topoisomerase I-binding RS protein (TOPORS) have been previously documented and have been described to result in pathological autosomal dominant retinitis pigmentosa (adRP). In our study, we describe the various genotypes and clinical/phenotypic manifestations of TOPORS-related mutations of our unique patient population in Rural Appalachia. Methods: The medical records of 416 patients with inherited retinal disease at the West Virginia University Eye Institute who had undergone genetic testing between the years of 2015-2022 were reviewed. Patients found to have pathologic RP and mutations related to TOPORS were then analyzed. Results: In total, 7 patients (ages 12-70) were identified amongst three unique families. All patients were female in our study. The average follow-up period was 7.7 years. A mother (70 yr) and daughter (51 yr) had a novel heterozygous nonsense point mutation in TOPORS c.2431C > T, p.Gln811X (Exon 3) that led to premature termination of the desired protein resulting in early onset vision loss, cataract formation, and visual field restriction. The mother developed a full-thickness macular hole which was successfully repaired. Five other patients were found to have previously described TOPORS mutations. Visual field loss was progressive with age in both cohorts. Conclusions: Seven patients at our institution were identified to have mutations in TOPORS resulting in autosomal dominant retinitis pigmentosa. Two patients were found to have novel truncating mutations in the TOPORS gene resulting in profound night blindness and visual field loss, recurrent macular edema, and in one individual, epiretinal membrane formation leading to a macular hole which was able to be successfully repaired.
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Affiliation(s)
- Alen T. Eid
- Department of Ophthalmology and Visual Sciences, West Virginia University School of Medicine, Morgantown, WV 26506, USA;
| | - Kevin Toni Eid
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT 84112, USA;
| | - James Vernon Odom
- Department of Ophthalmology and Visual Sciences, West Virginia University School of Medicine, Morgantown, WV 26506, USA;
| | - David Hinkle
- Tulane University School of Medicine, New Orleans, LA 70112, USA;
| | - Monique Leys
- Department of Ophthalmology and Visual Sciences, West Virginia University School of Medicine, Morgantown, WV 26506, USA;
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Hariharasudhan G, Jeong SY, Kim MJ, Jung SM, Seo G, Moon JR, Lee S, Chang IY, Kee Y, You H, Lee JH. OUP accepted manuscript. Nucleic Acids Res 2022; 50:1501-1516. [PMID: 35061896 PMCID: PMC8860612 DOI: 10.1093/nar/gkac009] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 12/23/2021] [Accepted: 01/13/2022] [Indexed: 11/24/2022] Open
Abstract
Homologous recombination (HR) is critical for error-free repair of DNA double-strand breaks. Chromatin loading of RAD51, a key protein that mediates the recombination, is a crucial step in the execution of the HR repair. Here, we present evidence that SUMOylation of RAD51 is crucial for the RAD51 recruitment to chromatin and HR repair. We found that topoisomerase 1-binding arginine/serine-rich protein (TOPORS) induces the SUMOylation of RAD51 at lysine residues 57 and 70 in response to DNA damaging agents. The SUMOylation was facilitated by an ATM-induced phosphorylation of TOPORS at threonine 515 upon DNA damage. Knockdown of TOPORS or expression of SUMOylation-deficient RAD51 mutants caused reduction in supporting normal RAD51 functions during the HR repair, suggesting the physiological importance of the modification. We found that the SUMOylation-deficient RAD51 reduces the association with its crucial binding partner BRCA2, explaining its deficiency in supporting the HR repair. These findings altogether demonstrate a crucial role for TOPORS-mediated RAD51 SUMOylation in promoting HR repair and genomic maintenance.
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Affiliation(s)
- Gurusamy Hariharasudhan
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Seo-Yeon Jeong
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Pharmacology, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Min-Ji Kim
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Sung Mi Jung
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Gwanwoo Seo
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Pharmacology, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Ju-Ran Moon
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Sumi Lee
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - In-Youb Chang
- Department of Anatomy, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Younghoon Kee
- Correspondence may also be addressed to Younghoon Kee. Tel: +82 53 785 1610;
| | - Ho Jin You
- Correspondence may also be addressed to Ho Jin You. Tel: +82 62 230 6337;
| | - Jung-Hee Lee
- To whom correspondence should be addressed. Tel: +82 62 230 6399;
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3
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Firmal P, Shah VK, Pant R, Chattopadhyay S. RING finger protein TOPORS modulates the expression of tumor suppressor SMAR1 in colorectal cancer via the TLR4-TRIF pathway. Mol Oncol 2021; 16:1523-1540. [PMID: 34689394 PMCID: PMC8978522 DOI: 10.1002/1878-0261.13126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 10/22/2021] [Indexed: 11/13/2022] Open
Abstract
TOP1‐binding arginine/serine‐rich protein (TOPORS), a really interesting new gene finger protein, has the ability to bind to a palindromic consensus DNA sequence that enables it to function as a potential transcriptional regulator. However, its role in regulating the transcription of cancer‐associated genes is yet to be explored. As Toll‐like receptor 4 (TLR4) agonists are known to regress solid tumors, we observed that lipopolysaccharide (LPS) induces TOPORS via a TLR4‐TIR domain‐containing adapter‐inducing interferon‐β‐dependent pathway, which in turn modulates the transcription of tumor suppressor scaffold/matrix attachment region‐binding protein 1 (SMAR1, also known as BANP). ChIP analysis showed that TOPORS binds on the SMAR1 promoter and its occupancy increases upon LPS treatment. A previous study from our laboratory revealed that SMAR1 acts as a repressor of signal transducer and activator of transcription 3 (STAT3) transcription. Tumor growth, as well as tumor‐associated macrophage polarization, depends on the status of the STAT1:STAT3 ratio. LPS‐induced SMAR1 expression decreases STAT3 expression and also skews the macrophage polarization toward M1 phenotype. In contrast, LPS failed to polarize tumor‐associated macrophages to M1 phenotype in a SMAR1‐silenced condition, which shows the involvement of SMAR1 in dictating the fate of colorectal cancer progression. Identification of the molecular mechanism behind LPS‐mediated tumor regression would be crucial for designing cancer treatment strategies involving bacterial components.
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Affiliation(s)
- Priyanka Firmal
- National Centre for Cell Science, S.P. Pune University Campus, Ganeshkhind, Pune, 411007
| | - Vibhuti Kumar Shah
- National Centre for Cell Science, S.P. Pune University Campus, Ganeshkhind, Pune, 411007
| | - Richa Pant
- National Centre for Cell Science, S.P. Pune University Campus, Ganeshkhind, Pune, 411007
| | - Samit Chattopadhyay
- National Centre for Cell Science, S.P. Pune University Campus, Ganeshkhind, Pune, 411007.,Department of Biological Sciences, BITS Pilani, K. K. Birla Goa Campus, NH 17B, Zuarinagar, Goa, 403726.,Indian Institute of Chemical Biology, Raja S C Mullick Road, Jadavpur, Kolkata, 700032
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4
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Pan M, Blattner C. Regulation of p53 by E3s. Cancers (Basel) 2021; 13:745. [PMID: 33670160 PMCID: PMC7916862 DOI: 10.3390/cancers13040745] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/15/2021] [Accepted: 02/05/2021] [Indexed: 12/18/2022] Open
Abstract
More than 40 years of research on p53 have given us tremendous knowledge about this protein. Today we know that p53 plays a role in different biological processes such as proliferation, invasion, pluripotency, metabolism, cell cycle control, ROS (reactive oxygen species) production, apoptosis, inflammation and autophagy. In the nucleus, p53 functions as a bona-fide transcription factor which activates and represses transcription of a number of target genes. In the cytoplasm, p53 can interact with proteins of the apoptotic machinery and by this also induces cell death. Despite being so important for the fate of the cell, expression levels of p53 are kept low in unstressed cells and the protein is largely inactive. The reason for the low expression level is that p53 is efficiently degraded by the ubiquitin-proteasome system and the vast inactivity of the tumor suppressor protein under normal growth conditions is due to the absence of activating and the presence of inactivating posttranslational modifications. E3s are important enzymes for these processes as they decorate p53 with ubiquitin and small ubiquitin-like proteins and by this control p53 degradation, stability and its subcellular localization. In this review, we provide an overview about E3s that target p53 and discuss the connection between p53, E3s and tumorigenesis.
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Affiliation(s)
| | - Christine Blattner
- Institute of Biological and Chemical Systems—Biological Information Processing, Karlsruhe Institute of Technology, PO-box 3640, 76021 Karlsruhe, Germany;
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5
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TOPORS, a tumor suppressor protein, contributes to the maintenance of higher-order chromatin architecture. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194518. [PMID: 32113985 DOI: 10.1016/j.bbagrm.2020.194518] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 02/06/2020] [Accepted: 02/22/2020] [Indexed: 11/22/2022]
Abstract
In the nucleus, chromosomes are hierarchically folded into active (A) and inactive (B) compartments composed of topologically associating domains (TADs). Genomic regions interact with nuclear lamina, termed lamina-associated domains (LADs). However, the molecular mechanisms underlying these 3D chromatin architectures remain incompletely understood. Here, we investigated the role of a potential tumor suppressor, TOP1 Binding Arginine/Serine Rich Protein (TOPORS), in genome organization. In mouse hepatocytes, chromatin interactions between A and B compartments increase and compartmentalization strength is reduced significantly upon Topors knockdown. Correspondingly, strength of TAD boundaries located at A/B borders is weakened. In the absence of TOPORS, chromatin-lamina interactions decrease and the coverage of LADs reduces from 53.31% to 46.52%. Interestingly, these changes in 3D genome are associated with PML nuclear bodies and PML-associated domains (PADs). Moreover, chromatin accessibility is altered predominantly at intergenic regions upon Topors knockdown, including a subset of enhancers. These alterations of chromatin are concordant with transcriptome changes, which are associated with carcinogenesis. Collectively, our findings demonstrate that TOPORS functions as a regulator in chromatin structure, providing novel insight into the architectural roles of tumor suppressors in higher-order genome organization.
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Bang S, Kaur S, Kurokawa M. Regulation of the p53 Family Proteins by the Ubiquitin Proteasomal Pathway. Int J Mol Sci 2019; 21:E261. [PMID: 31905981 PMCID: PMC6981958 DOI: 10.3390/ijms21010261] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 12/24/2019] [Indexed: 12/25/2022] Open
Abstract
The tumor suppressor p53 and its homologues, p63 and p73, play a pivotal role in the regulation of the DNA damage response, cellular homeostasis, development, aging, and metabolism. A number of mouse studies have shown that a genetic defect in the p53 family could lead to spontaneous tumor development, embryonic lethality, or severe tissue abnormality, indicating that the activity of the p53 family must be tightly regulated to maintain normal cellular functions. While the p53 family members are regulated at the level of gene expression as well as post-translational modification, they are also controlled at the level of protein stability through the ubiquitin proteasomal pathway. Over the last 20 years, many ubiquitin E3 ligases have been discovered that directly promote protein degradation of p53, p63, and p73 in vitro and in vivo. Here, we provide an overview of such E3 ligases and discuss their roles and functions.
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Affiliation(s)
| | | | - Manabu Kurokawa
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA; (S.B.); (S.K.)
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Lemée JM, Clavreul A, Aubry M, Com E, de Tayrac M, Mosser J, Menei P. Integration of transcriptome and proteome profiles in glioblastoma: looking for the missing link. BMC Mol Biol 2018; 19:13. [PMID: 30463513 PMCID: PMC6249855 DOI: 10.1186/s12867-018-0115-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 11/09/2018] [Indexed: 12/21/2022] Open
Abstract
Background Glioblastoma (GB) is the most common and aggressive tumor of the brain. Genotype-based approaches and independent analyses of the transcriptome or the proteome have led to progress in understanding the underlying biology of GB. Joint transcriptome and proteome profiling may reveal new biological insights, and identify pathogenic mechanisms or therapeutic targets for GB therapy. We present a comparison of transcriptome and proteome data from five GB biopsies (TZ) vs their corresponding peritumoral brain zone (PBZ). Omic analyses were performed using RNA microarray chips and the isotope-coded protein label method (ICPL). Results As described in other cancers, we found a poor correlation between transcriptome and proteome data in GB. We observed only two commonly deregulated mRNAs/proteins (neurofilament light polypeptide and synapsin 1) and 12 altered biological processes; they are related to cell communication, synaptic transmission and nervous system processes. This poor correlation may be a consequence of the techniques used to produce the omic profiles, the intrinsic properties of mRNA and proteins and/or of cancer- or GB-specific phenomena. Of interest, the analysis of the transcription factor binding sites present upstream from the open reading frames of all altered proteins identified by ICPL method shows a common binding site for the topoisomerase I and p53-binding protein TOPORS. Its expression was observed in 7/11 TZ samples and not in PBZ. Some findings suggest that TOPORS may function as a tumor suppressor; its implication in gliomagenesis should be examined in future studies. Conclusions In this study, we showed a low correlation between transcriptome and proteome data for GB samples as described in other cancer tissues. We observed that NEFL, SYN1 and 12 biological processes were deregulated in both the transcriptome and proteome data. It will be important to analyze more specifically these processes and these two proteins to allow the identification of new theranostic markers or potential therapeutic targets for GB. Electronic supplementary material The online version of this article (10.1186/s12867-018-0115-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jean-Michel Lemée
- Department of Neurosurgery, CHU Angers, University Hospital of Angers, 4, Rue Larrey, 49933, Angers Cedex 09, France. .,CRCINA, INSERM, Université de Nantes, Université d'Angers, Angers, France.
| | - Anne Clavreul
- Department of Neurosurgery, CHU Angers, University Hospital of Angers, 4, Rue Larrey, 49933, Angers Cedex 09, France.,CRCINA, INSERM, Université de Nantes, Université d'Angers, Angers, France
| | - Marc Aubry
- UEB, UMS 3480 Biosit, Faculté de Médecine, Université Rennes 1, Rennes, France.,Plate-forme Génomique Santé Biosit, Université Rennes 1, Rennes, France
| | - Emmanuelle Com
- Inserm U1085 IRSET, Université de Rennes 1, Rennes, France.,Protim, Université de Rennes 1, Rennes, France
| | - Marie de Tayrac
- UEB, UMS 3480 Biosit, Faculté de Médecine, Université Rennes 1, Rennes, France.,Service de Génétique Moléculaire et Génomique, CHU Rennes, Rennes, France.,CNRS, UMR 6290, Institut de Génétique et Développement de Rennes (IGdR), Rennes, France
| | - Jean Mosser
- UEB, UMS 3480 Biosit, Faculté de Médecine, Université Rennes 1, Rennes, France.,Plate-forme Génomique Santé Biosit, Université Rennes 1, Rennes, France.,Service de Génétique Moléculaire et Génomique, CHU Rennes, Rennes, France.,CNRS, UMR 6290, Institut de Génétique et Développement de Rennes (IGdR), Rennes, France
| | - Philippe Menei
- Department of Neurosurgery, CHU Angers, University Hospital of Angers, 4, Rue Larrey, 49933, Angers Cedex 09, France.,CRCINA, INSERM, Université de Nantes, Université d'Angers, Angers, France
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8
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The effects of graded levels of calorie restriction: VII. Topological rearrangement of hypothalamic aging networks. Aging (Albany NY) 2017; 8:917-32. [PMID: 27115072 PMCID: PMC4931844 DOI: 10.18632/aging.100944] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 03/31/2016] [Indexed: 12/31/2022]
Abstract
Connectivity in a gene-gene network declines with age, typically within gene clusters. We explored the effect of short-term (3 months) graded calorie restriction (CR) (up to 40 %) on network structure of aging-associated genes in the murine hypothalamus by using conditional mutual information. The networks showed a topological rearrangement when exposed to graded CR with a higher relative within cluster connectivity at 40CR. We observed changes in gene centrality concordant with changes in CR level, with Ppargc1a, and Ppt1 having increased centrality and Etfdh, Traf3 and Abcc1 decreased centrality as CR increased. This change in gene centrality in a graded manner with CR, occurred in the absence of parallel changes in gene expression levels. This study emphasizes the importance of augmenting traditional differential gene expression analyses to better understand structural changes in the transcriptome. Overall our results suggested that CR induced changes in centrality of biological relevant genes that play an important role in preventing the age-associated loss of network integrity irrespective of their gene expression levels.
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9
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Kumar S, Sharma G, Chakraborty C, Sharma AR, Kim J. Regulatory functional territory of PLK-1 and their substrates beyond mitosis. Oncotarget 2017; 8:37942-37962. [PMID: 28415805 PMCID: PMC5514964 DOI: 10.18632/oncotarget.16290] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 03/03/2017] [Indexed: 12/04/2022] Open
Abstract
Polo-like kinase 1 (PLK-1) is a well-known (Ser/Thr) mitotic protein kinase and is considered as a proto-oncogene. As hyper-activation of PLK-1 is broadly associated with poor prognosis and cancer progression, it is one of the most extensively studied mitotic kinases. During mitosis, PLK-1 regulates various cell cycle events, such as spindle pole maturation, chromosome segregation and cytokinesis. However, studies have demonstrated that the role of PLK-1 is not only restricted to mitosis, but PLK-1 can also regulate other vital events beyond mitosis, including transcription, translation, ciliogenesis, checkpoint adaptation and recovery, apoptosis, chromosomes dynamics etc. Recent reviews have tried to define the regulatory role of PLK-1 during mitosis progression and tumorigenesis, but its' functional role beyond mitosis is still largely unexplored. PLK-1 can regulate the activity of many proteins that work outside of its conventional territory. The dysregulation of these proteins can cause diseases such as Alzheimer's disease, tumorigenesis etc. and may also lead to drug resistance. Thus, in this review, we discussed the versatile role of PLK-1 and tried to collect data to validate its' functional role in cell cycle regulation apart from mitosis.
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Affiliation(s)
- Shiv Kumar
- Department of Biochemistry, Institute of Cell Differentiation and Aging, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Garima Sharma
- Institute For Skeletal Aging & Orthopedic Surgery, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Chiranjib Chakraborty
- Department of Bio-informatics, School of Computer and Information Sciences, Galgotias University, Greater Noida, Uttar Pradesh, India
| | - Ashish Ranjan Sharma
- Institute For Skeletal Aging & Orthopedic Surgery, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Jaebong Kim
- Department of Biochemistry, Institute of Cell Differentiation and Aging, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
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Abdelfatah E, Kerner Z, Nanda N, Ahuja N. Epigenetic therapy in gastrointestinal cancer: the right combination. Therap Adv Gastroenterol 2016; 9:560-79. [PMID: 27366224 PMCID: PMC4913338 DOI: 10.1177/1756283x16644247] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Epigenetics is a relatively recent field of molecular biology that has arisen over the past 25 years. Cancer is now understood to be a disease of widespread epigenetic dysregulation that interacts extensively with underlying genetic mutations. The development of drugs targeting these processes has rapidly progressed; with several drugs already FDA approved as first-line therapy in hematological malignancies. Gastrointestinal (GI) cancers possess high degrees of epigenetic dysregulation, exemplified by subtypes such as CpG island methylator phenotype (CIMP), and the potential benefit of epigenetic therapy in these cancers is evident. The application of epigenetic drugs in solid tumors, including GI cancers, is just emerging, with increased understanding of the cancer epigenome. In this review, we provide a brief overview of cancer epigenetics and the epigenetic targets of therapy including deoxyribonucleic acid (DNA) methylation, histone modifications, and chromatin remodeling. We discuss the epigenetic drugs currently in use, with a focus on DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, and explain the pharmacokinetic and mechanistic challenges in their application. We present the strategies employed in incorporating these drugs into the treatment of GI cancers, and explain the concept of the cancer stem cell in epigenetic reprogramming and reversal of chemo resistance. We discuss the most promising combination strategies in GI cancers including: (1) epigenetic sensitization to radiotherapy, (2) epigenetic sensitization to cytotoxic chemotherapy, and (3) epigenetic immune modulation and priming for immune therapy. Finally, we present preclinical and clinical trial data employing these strategies thus far in various GI cancers including colorectal, esophageal, gastric, and pancreatic cancer.
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Affiliation(s)
- Eihab Abdelfatah
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Zachary Kerner
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nainika Nanda
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- West Virginia University School of Medicine, Morgantown, WV, USA
| | - Nita Ahuja
- Department of Surgery and Oncology, Johns Hopkins University, 1650 Orleans St. Room 342, Baltimore, MD 21231, USA
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Plk1-targeted therapies in TP53- or RAS-mutated cancer. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 761:31-39. [PMID: 24630986 DOI: 10.1016/j.mrrev.2014.02.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/27/2014] [Accepted: 02/27/2014] [Indexed: 11/23/2022]
Abstract
Despite advances in treatment, prognosis for many types of carcinoma remains poor. Polo-like kinase 1 (Plk1) has been explored as a target for the development of anticancer drugs. As a mitotic master Ser/Thr kinase, Plk1 is involved in centrosomal maturation, microtubule nucleation, chromosomal segregation, and cytokinesis. Additional functions in interphase and in response to DNA damage have been revealed. The multiple locations of Plk1 correspond to distinct functions, mediated by phosphorylation of multiple substrates. Since it is highly expressed in several carcinomas, and expression of Plk1 is inversely correlated with the survival rate of patients in non-small cell lung, head and neck, and esophageal cancer, Plk1 is recognized as a valid prognostic marker. Connections between Plk1 and p53 or KRAS in carcinoma provide a rationale and several possible routes to the development of therapies. Tumors with both p53-deficiency and high Plk1 expression may be particularly sensitive to Plk1 inhibitors, although some controversial data exist. In KRAS-mutant cancers, on the other hand, Plk1 may be essential for tumor cell survival, but detailed studies as to whether Plk1 inhibitors are more effective in KRAS-mutant cancers must be performed in order to determine whether this is the case. Here, we present evidence for Plk1 as a prognostic marker and potentially effective target for the treatment of patients with carcinoma, to demonstrate the value of Plk1 as a target for the development of cancer treatment, especially for patients with solid tumors. In addition, the effects of Plk1 inhibition in p53- or KRAS-mutated cancer are discussed with respect to clinical implications. Structural specifics of Plk1 are presented, as well as current strategies for discovering new Plk1 inhibitors by targeting the conserved ATP binding site or polo-box domain of Plk1, in order to develop Plk1-specific anticancer drugs.
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12
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Luxton HJ, Barnouin K, Kelly G, Hanrahan S, Totty N, Neal DE, Whitaker HC. Regulation of the localisation and function of the oncogene LYRIC/AEG-1 by ubiquitination at K486 and K491. Mol Oncol 2014; 8:633-41. [PMID: 24529480 PMCID: PMC4013555 DOI: 10.1016/j.molonc.2014.01.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 01/13/2014] [Accepted: 01/14/2014] [Indexed: 11/30/2022] Open
Abstract
The pivotal role of LYRIC/AEG‐1 in malignant transformation, tumourigenesis and chemo‐resistance has previously been demonstrated in different cell types and sub‐cellular compartments. The localisation of LYRIC/AEG‐1 appears crucial to its function and is regulated by three lysine‐rich nuclear localisation signal regions, one of which was previously demonstrated to be modified by ubiquitin. Here we show that mutation of LYRIC/AEG‐1 at K486 and K491 results in a loss of ubiquitination. A K486/491R double mutant that is incapable of ubiquitination shows reduced binding to the NFκB subunit p65 or importin‐β resulting in a distinctive peri‐nuclear localisation of LYRIC/AEG‐1. We also provide evidence to suggest that TOPORS, an E3 ligase that also regulates p53 modification may be responsible for LYRIC/AEG‐1 ubiquitin modification. Overall we demonstrate that specific sites of LYRIC/AEG‐1 ubiquitination are essential for regulating LYRIC/AEG‐1 localisation and functionally interacting proteins. LYRIC/AEG‐1 is an important oncogene. 2 specific lysine residues in exNLS‐2 are ubiquitinated. Deletion of both lysine residues changes localisation and interaction with p65. LYRIC/AEG‐1 interacts with TOPORS, a known E3 ligase.
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Affiliation(s)
- Hayley J Luxton
- Uro-Oncology Research Group, Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK
| | - Karin Barnouin
- Protein Analysis and Proteomics, Cancer Research UK London Research Institute, London WC2A 3LY, UK; Protein Analysis and Proteomics, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Potters Bar EN6 3LD, UK
| | - Gavin Kelly
- Bioinformatics and Biostatistics, Cancer Research UK London Research Institute, London WC2A 3LY, UK
| | - Sarah Hanrahan
- Protein Analysis and Proteomics, Cancer Research UK London Research Institute, London WC2A 3LY, UK
| | - Nick Totty
- Protein Analysis and Proteomics, Cancer Research UK London Research Institute, London WC2A 3LY, UK
| | - David E Neal
- Uro-Oncology Research Group, Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK
| | - Hayley C Whitaker
- Uro-Oncology Research Group, Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK.
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Yamada T, Christov K, Shilkaitis A, Bratescu L, Green A, Santini S, Bizzarri AR, Cannistraro S, Gupta TKD, Beattie CW. p28, a first in class peptide inhibitor of cop1 binding to p53. Br J Cancer 2013; 108:2495-504. [PMID: 23736031 PMCID: PMC3694247 DOI: 10.1038/bjc.2013.266] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 05/08/2013] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND A 28 amino-acid (aa) cell-penetrating peptide (p28) derived from azurin, a redox protein secreted from the opportunistic pathogen Pseudomonas aeruginosa, produces a post-translational increase in p53 in cancer cells by inhibiting its ubiquitination. METHODS In silico computational simulations were used to predict motifs within the p53 DNA-binding domain (DBD) as potential sites for p28 binding. In vitro direct and competitive pull-down studies as well as western blot and RT-PCR analyses were used to validate predictions. RESULTS The L1 loop (aa 112-124), a region within the S7-S8 loop (aa 214-236) and T140, P142, Q144, W146, R282 and L289 of the p53DBD were identified as potential sites for p28 binding. p28 decreased the level of the E3 ligase COP1 >80%, in p53wt and p53mut cells with no decrease in COP1 in p53dom/neg or p53null cells. Brief increases in the expression of the E3 ligases, TOPORS, Pirh2 and HDM2 (human double minute 2) in p53wt and p53mut cells were in response to sustained increases in p53. CONCLUSION These data identify the specific motifs within the DBD of p53 that bind p28 and suggest that p28 inhibition of COP1 binding results in the sustained, post-translational increase in p53 levels and subsequent inhibition of cancer cell growth independent of an HDM2 pathway.
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Affiliation(s)
- T Yamada
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
| | - K Christov
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
| | - A Shilkaitis
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
| | - L Bratescu
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
| | - A Green
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
| | - S Santini
- Biophysics and Nanoscience Centre, CNISM, Facoltà di Scienze, Università della Tuscia, Viterbo, Italy
| | - A R Bizzarri
- Biophysics and Nanoscience Centre, CNISM, Facoltà di Scienze, Università della Tuscia, Viterbo, Italy
| | - S Cannistraro
- Biophysics and Nanoscience Centre, CNISM, Facoltà di Scienze, Università della Tuscia, Viterbo, Italy
| | - T K D Gupta
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
| | - C W Beattie
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
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Seong KM, Nam SY, Kim JY, Yang KH, An S, Jin YW, Kim CS. TOPORS modulates H2AX discriminating genotoxic stresses. J Biochem Mol Toxicol 2012; 26:429-38. [PMID: 22972498 DOI: 10.1002/jbt.21438] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/26/2012] [Accepted: 08/11/2012] [Indexed: 11/07/2022]
Abstract
H2AX plays an important role in chromatin reorganization implicated in DNA repair and apoptosis under various DNA damaging conditions. In this study, the interaction between TOPORS (topoisomerase I-binding protein) and H2AX was verified using mammalian cell extracts exposed to diverse DNA damaging stresses such as ionizing radiation, doxorubicin, camptothecin, and hydrogen peroxide. In vitro assays for ubiquitination revealed that TOPORS functions as a novel E3 ligase for H2AX ubiquitination. TOPORS was found to be dissociated from H2AX proteins when cells were exposed to oxidative stress, but not replication-inducing DNA damaging stress. The protein stability of H2AX was decreased when TOPORS was ectopically expressed in cells, and oxidative stresses such as hydrogen peroxide and ionizing radiation induced recovery of the H2AX protein level. Therefore, these biochemical data suggest that TOPORS plays a key role in the turnover of H2AX protein, discriminating the type of DNA damaging stress.
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Affiliation(s)
- Ki Moon Seong
- Division of Radiation Effect Research, Radiation Health Research Institute, Korea Hydro & Nuclear Power Co., Ltd., 132-703, Seoul, Korea.
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Braun KR, DeWispelaere AM, Bressler SL, Fukai N, Kenagy RD, Chen L, Clowes AW, Kinsella MG. Inhibition of PDGF-B induction and cell growth by syndecan-1 involves the ubiquitin and SUMO-1 ligase, Topors. PLoS One 2012; 7:e43701. [PMID: 22912899 PMCID: PMC3422340 DOI: 10.1371/journal.pone.0043701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 07/23/2012] [Indexed: 01/14/2023] Open
Abstract
Syndecans are receptors for soluble ligands, including heparin-binding growth factors, and matrix proteins. However, intracellular targets of syndecan-1 (Sdc-1)-mediated signaling are not fully understood. A yeast two-hybrid protein interaction screening of a mouse embryo library identified the ubiquitin and SUMO-1 E3 ligase, Topors, as a novel ligand of the Sdc-1 cytoplasmic domain (S1CD), a finding confirmed by ligand blotting and co-precipitation with Sdc-1 from cell lysates. Deletion mutagenesis identified an 18-amino acid sequence of Topors required for the interaction with the S1CD. By immunohistochemistry, Topors and Sdc-1 co-localized near the cell periphery in normal murine mammary gland (NMuMG) cells in vitro and in mouse embryonic epithelia in vivo. Finally, siRNA-mediated knockdown of Topors demonstrated that Topors is a growth promoter for murine arterial smooth muscle cells and is required for the inhibitory effect of Sdc-1 on cell growth and platelet-derived growth factor-B induction. These data suggest a novel mechanism for the inhibitory effects of Sdc-1 on cell growth that involves the interaction between the cytoplasmic domain of Sdc-1 and the SUMO-1 E3 ligase, Topors.
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Affiliation(s)
- Kathleen R. Braun
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Allison M. DeWispelaere
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Steven L. Bressler
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Nozomi Fukai
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Richard D. Kenagy
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Lihua Chen
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Alexander W. Clowes
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Michael G. Kinsella
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
- * E-mail:
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Lee SW, Seong MW, Jeon YJ, Chung CH. Ubiquitin E3 ligases controlling p53 stability. Anim Cells Syst (Seoul) 2012. [DOI: 10.1080/19768354.2012.688769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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17
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Nuclear structure and chromosome segregation in Drosophila male meiosis depend on the ubiquitin ligase dTopors. Genetics 2011; 189:779-93. [PMID: 21900273 DOI: 10.1534/genetics.111.133819] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In many organisms, homolog pairing and synapsis at meiotic prophase depend on interactions between chromosomes and the nuclear membrane. Male Drosophila lack synapsis, but nonetheless, their chromosomes closely associate with the nuclear periphery at prophase I. To explore the functional significance of this association, we characterize mutations in nuclear blebber (nbl), a gene required for both spermatocyte nuclear shape and meiotic chromosome transmission. We demonstrate that nbl corresponds to dtopors, the Drosophila homolog of the mammalian dual ubiquitin/small ubiquitin-related modifier (SUMO) ligase Topors. We show that mutations in dtopors cause abnormalities in lamin localizations, centriole separation, and prophase I chromatin condensation and also cause anaphase I bridges that likely result from unresolved homolog connections. Bridge formation does not require mod(mdg4) in meiosis, suggesting that bridges do not result from misregulation of the male homolog conjunction complex. At the ultrastructural level, we observe disruption of nuclear shape, an uneven perinuclear space, and excess membranous structures. We show that dTopors localizes to the nuclear lamina at prophase, and also transiently to intranuclear foci. As a role of dtopors at gypsy insulator has been reported, we also asked whether these new alleles affected expression of the gypsy-induced mutation ct(6) and found that it was unaltered in dtopors homozygotes. Our results indicate that dTopors is required for germline nuclear structure and meiotic chromosome segregation, but in contrast, is not necessary for gypsy insulator function. We suggest that dtopors plays a structural role in spermatocyte lamina that is critical for multiple aspects of meiotic chromosome transmission.
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Bae SK, Gwak J, Song IS, Park HS, Oh S. Induction of apoptosis in colon cancer cells by a novel topoisomerase I inhibitor TopIn. Biochem Biophys Res Commun 2011; 409:75-81. [PMID: 21549095 DOI: 10.1016/j.bbrc.2011.04.108] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 04/21/2011] [Indexed: 10/18/2022]
Abstract
The tumor suppressor p53 plays an important role in cellular emergency mechanisms through regulating the genes involved in cell cycle arrest and apoptosis. To identify small molecules that can activate p53-responsive transcription, we performed chemical screening using genetically engineered HCT116 reporter cells. We found that TopIn (7-phenyl-6H-[1,2,5]oxadiazolo[3,4-e]indole 3-oxide) efficiently activated p53-mediated transcriptional activity and induced phosphorylation of p53 at Ser15, thereby stabilizing the p53 protein. Furthermore, TopIn upregulated the expression of p21(WAF1/CIP1), a downstream target of p53, and suppressed cellular proliferation in various colon cancer cells. Additionally, TopIn induced DNA fragmentation, caspase-3/7 activation and poly ADP ribose polymerase cleavage, typical biochemical markers of apoptosis, in p53 wild-type and mutated colon cancer cells. Finally, we found that TopIn inhibited topoisomerase I activity, but not topoisomerase II, in vitro and induced the formation of the topoisomerase I-DNA complex in HCT116 colon cancer cells. Unlike camptothecin (CPT) and its derivative SN38, TopIn did not affect the activity of the ATP-binding cassette transporter breast cancer resistance protein (BCRP) or multidrug-resistant protein-1 (MDR-1). These results suggest that TopIn may present a promising new topoisomerase I-targeting anti-tumor therapeutics.
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Affiliation(s)
- Soo Kyung Bae
- College of Pharmacy, The Catholic University of Korea, Bucheon, Republic of Korea
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Liu XS, Song B, Liu X. The substrates of Plk1, beyond the functions in mitosis. Protein Cell 2010; 1:999-1010. [PMID: 21153517 PMCID: PMC4875153 DOI: 10.1007/s13238-010-0131-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 11/08/2010] [Indexed: 12/01/2022] Open
Abstract
Polo-like kinase 1 (Plk1) is a key regulator of cell division in eukaryotic cells. In this short review, we briefly summarized the well-established functions modulated by Plk1 during mitosis. Beyond mitosis, we focused mainly on the unexpected processes in which Plk1 emerges as a critical player, including microtubule dynamics, DNA replication, chromosome dynamics, p53 regulation, and recovery from the G2 DNA-damage checkpoint. Our discussion is mainly based on the critical substrates targeted by Plk1 during these cellular events and the functional significance associated with each phosphorylation event.
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Affiliation(s)
- X. Shawn Liu
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907 USA
| | - Bing Song
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907 USA
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907 USA
- Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907 USA
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Boellmann F, Zhang L, Clewell HJ, Schroth GP, Kenyon EM, Andersen ME, Thomas RS. Genome-wide Analysis of DNA Methylation and Gene Expression Changes in the Mouse Lung following Subchronic Arsenate Exposure. Toxicol Sci 2010; 117:404-17. [DOI: 10.1093/toxsci/kfq225] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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21
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Yang X, Li H, Deng A, Liu X. Plk1 phosphorylation of Topors is involved in its degradation. Mol Biol Rep 2010; 37:3023-8. [PMID: 19821153 PMCID: PMC4965875 DOI: 10.1007/s11033-009-9871-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 09/29/2009] [Indexed: 10/20/2022]
Abstract
Topors is a DNA topoisomerase I- and p53-binding protein, and mainly functions as a p53 regulator. Accumulating evidence also supports the notion that Topors plays the role as a negative regulator of cell growth, and possibly as a tumor suppressor. Here, we demonstrated that Topors is also involved in normal mitotic progression, since Topors depletion delays mitotic entry and affects mitotic progression. Furthermore, Topors is degradated in response to the activation of the spindle checkpoint. Significantly, Polo-like kinase 1 (Plk1)-associated phosphorylation of Topors at S718 is essential for nocodazole-induced degradation of Topors.
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Affiliation(s)
- Xiaoming Yang
- College of Chemistry, Sichuan University, Chengdu 610064, China.
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22
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Selmer KK, Grøndahl J, Riise R, Brandal K, Braaten Ø, Bragadottir R, Undlien DE. Autosomal dominant pericentral retinal dystrophy caused by a novel missense mutation in the TOPORS gene. Acta Ophthalmol 2010; 88:323-8. [PMID: 19183411 DOI: 10.1111/j.1755-3768.2008.01465.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE This study aimed to identify the genetic cause of autosomal dominant pericentral retinal dystrophy (adPRD) in a large Norwegian family with 35 affected members. METHODS The family was characterized by clinical ophthalmological examination along with fundus photography, dark adaptometry and electroretinography. We performed a genome-wide linkage analysis followed by sequencing of a candidate gene to identify the mutation causing the disease. RESULTS The ophthalmological examinations revealed an atypical form of retinitis pigmentosa (RP), which we prefer to call adPRD. Compared with classical RP, this phenotype has a favourable prognosis. Linkage analysis showed a linkage peak covering the most recently reported adRP gene TOPORS. This gene was sequenced in 19 family members and a novel missense mutation, c.1205a>c, resulting in an amino acid substitution p.Q402P, was detected in all affected members. The mutation showed complete co-segregation with the disease in this family, with a LOD score of 7.3. It is located in a highly conserved region and alignment with the appropriate DNA sequence from other species shows complete conservation of this amino acid. The mutation was not detected in 207 healthy, unrelated controls of Norwegian origin. CONCLUSIONS We present a novel mutation in the TOPORS gene co-segregating with a distinct phenotype of adPRD in a large Norwegian family.
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Marshall H, Bhaumik M, Aviv H, Moore D, Yao M, Dutta J, Rahim H, Gounder M, Ganesan S, Saleem A, Rubin E. Deficiency of the dual ubiquitin/SUMO ligase Topors results in genetic instability and an increased rate of malignancy in mice. BMC Mol Biol 2010; 11:31. [PMID: 20429939 PMCID: PMC2873312 DOI: 10.1186/1471-2199-11-31] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Accepted: 04/29/2010] [Indexed: 01/07/2023] Open
Abstract
Background Topors is a nuclear protein that co-localizes with promyelocytic leukemia bodies and has both ubiquitin and SUMO E3 ligase activity. Expression studies implicated Topors as a tumor suppressor in various malignancies. To gain insight into the function of Topors, we generated a Topors-deficient mouse strain. Results Mice homozygous for a mutant Topors allele exhibited a high rate of perinatal mortality and decreased lifespan. In addition, heterozygotes were found to have an increased incidence of malignancy, involving a variety of tissues. Consistent with this finding, primary embryonic fibroblasts lacking Topors exhibited an increased rate of malignant transformation, associated with aneuploidy and defective chromosomal segregation. While loss of Topors did not alter sensitivity to DNA-damaging or microtubule-targeting agents, cells lacking Topors exhibited altered pericentric heterochromatin, manifested by mislocalization of HP1α and an increase in transcription from pericentric major satellite DNA. Topors-deficient cells exhibited a transcriptional profile similar to that of cells treated with histone deacetylase inhibitors, and were resistant to the anti-proliferative effects of the histone deacetylase inhibitor trichostatin A. Conclusion These results indicate a unique role for Topors in the maintenance of genomic stability and pericentric heterochromatin, as well as in cellular sensitivity to histone deacetylase inhibitors.
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Affiliation(s)
- Henderson Marshall
- Department of Pharmacology, Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08901, USA
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Huang HY, Li SH, Yu SC, Chou FF, Tzeng CC, Hu TH, Uen YH, Tian YF, Wang YH, Fang FM, Huang WW, Wei YC, Wu JM, Li CF. Homozygous deletion of MTAP gene as a poor prognosticator in gastrointestinal stromal tumors. Clin Cancer Res 2009; 15:6963-72. [PMID: 19887491 DOI: 10.1158/1078-0432.ccr-09-1511] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Chromosome 9 is frequently deleted in high-risk gastrointestinal stromal tumors (GISTs), whereas its specific tumor suppressor genes (TSGs) are less understood. We did an integrative study of MTAP gene at 9p21 to analyze its implication in GISTs. EXPERIMENTAL DESIGN To search TSGs on chromosome 9, we used ultrahigh-resolution array comparative genomic hybridization to profile DNA copy number alterations of 22 GISTs, with special attention to MTAP gene. MTAP immunoexpression was assessable for 306 independent GISTs on tissue microarrays, with 146 cases analyzed for MTAP homozygous deletion, 181 for mutations of KIT and PDGFRA receptor tyrosine kinase genes, and 7 for MTAP hypermethylation. RESULTS Array comparative genomic hybridization identified 11 candidate TSGs on 9p and six on 9q. MTAP and/or CDKN2A/CDKN2B at 9p21.3 were deleted in one intermediate-risk (11%) and seven high-risk (70%) GISTs with two cases homozygously codeleted at both loci. MTAP homozygous deletion, present in 25 of 146 cases, was highly associated with larger size and higher mitotic rate, Ki-67 index, and risk level (all P < 0.01) but not with receptor tyrosine kinase genotypes. Whereas MTAP homozygous deletion correlated with MTAP protein loss (P < 0.001), 7 of 30 GISTs without MTAP expression did not show homozygous deletion, including three MTAP-hypermethylated cases. MTAP homozygous deletion was univariately predictive of decreased disease-free survival (P < 0.0001) and remained multivariately independent (P = 0.0369, hazard ratio = 2.166), together with high-risk category (P < 0.0001), Ki-67 index >5% (P = 0.0106), and nongastric location (P = 0.0416). CONCLUSIONS MTAP homozygous deletion, the predominant mechanism to deplete protein expression, is present in 17% of GISTs. It correlates with important prognosticators and independently predicts worse outcomes, highlighting the role in disease progression.
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Affiliation(s)
- Hsuan-Ying Huang
- Departments of Pathology, Surgery, and Radiation Oncology, and Divisions of Oncology and Gastroenterology, Department of Internal Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan
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Yang X, Li H, Zhou Z, Wang WH, Deng A, Andrisani O, Liu X. Plk1-mediated phosphorylation of Topors regulates p53 stability. J Biol Chem 2009; 284:18588-92. [PMID: 19473992 PMCID: PMC2707202 DOI: 10.1074/jbc.c109.001560] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 05/20/2009] [Indexed: 11/06/2022] Open
Abstract
Polo-like kinase 1 (Plk1) overexpression is associated with tumorigenesis by an unknown mechanism. Likewise, Plk1 was suggested to act as a negative regulator of tumor suppressor p53, but the mechanism remains to be determined. Herein, we have identified topoisomerase I-binding protein (Topors), a p53-binding protein, as a Plk1 target. We show that Plk1 phosphorylates Topors on Ser(718) in vivo. Significantly, expression of a Plk1-unphosphorylatable Topors mutant (S718A) leads to a dramatic accumulation of p53 through inhibition of p53 degradation. Topors is an ubiquitin and small ubiquitin-like modifier ubiquitin-protein isopeptide ligase (SUMO E3) ligase. Plk1-mediated phosphorylation of Topors inhibits Topors-mediated sumoylation of p53, whereas p53 ubiquitination is enhanced, leading to p53 degradation. These results demonstrate that Plk1 modulates Topors activity in suppressing p53 function and identify a likely mechanism for the tumorigenic potential of Plk1.
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Affiliation(s)
- Xiaoming Yang
- From the College of Chemistry, Sichuan University, Chengdu 610064, China and
- the Departments of Biochemistry and
| | | | | | - Wen-Horng Wang
- Basic Medical Sciences, Purdue University, West Lafayette, Indiana 47907
| | - Anping Deng
- From the College of Chemistry, Sichuan University, Chengdu 610064, China and
| | - Ourania Andrisani
- Basic Medical Sciences, Purdue University, West Lafayette, Indiana 47907
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Park HJ, Zheng H, Kulkarni D, Kerrigan J, Pungaliya P, Saleem A, Rubin EH. Identification of phosphorylation sites of TOPORS and a role for serine 98 in the regulation of ubiquitin but not SUMO E3 ligase activity. Biochemistry 2009; 47:13887-96. [PMID: 19053840 DOI: 10.1021/bi801904q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
TOPORS is the first example of a protein that possesses both ubiquitin and SUMO E3 ligase activity. The ubiquitination activity maps to a conserved RING domain in the N-terminal region of the protein, which is not required for sumoylation activity. Similar to other E3 ligases, it is likely that the ubiquitin and sumoylation activities of TOPORS are regulated by post-translational modifications. Therefore, we employed mass spectrometry to identify post-translational modifications of TOPORS. Several putative phosphorylated regions were identified in conserved regions of the protein. We investigated the role of phosphorylation of serine 98, which is adjacent to the RING domain, in both cells and in vitro. Mutation of serine 98 to aspartic acid resulted in an increase in the ubiquitin ligase activity of TOPORS both in cells and in vitro. In addition, this mutation increased the binding of TOPORS to the E2 enzyme UbcH5a both in vitro and in cells. Conversely, a phospho-deficient mutant (S98A) exhibited little change in ubiquitin ligase activity compared to wild-type TOPORS, both in cells and in vitro. Neither of the mutants affected the localization of TOPORS to punctate nuclear regions. In addition, neither mutant affected the SUMO ligase activity of TOPORS in cells or in vitro. Molecular modeling studies support a role for serine 98 in regulating TOPORS-E2 interactions. Our findings indicate that phosphorylation of serine 98 regulates the ubiquitin but not the SUMO ligase activity of TOPORS, consistent with a potential binary switch function for TOPORS in protein ubiquitination versus sumoylation.
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Affiliation(s)
- Hye-Jin Park
- Departments of Pharmacology and Medicine, The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 195 Little Albany Street, New Brunswick, New Jersey 08901, USA
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Kim KI, Baek SH. Small ubiquitin-like modifiers in cellular malignancy and metastasis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 273:265-311. [PMID: 19215907 DOI: 10.1016/s1937-6448(08)01807-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Small ubiquitin-like modifiers (SUMOs) mediate a variety of cellular functions of protein targets mainly in the nucleus but in other cellular compartments as well, and thereby participate in maintaining cellular homeostasis. SUMO system plays important roles in transcriptional regulation, DNA damage responses, maintaining genome integrity, and signaling pathways. Thus, in some cases, loss of regulated control on SUMOylation/deSUMOylation processes causes a defect in maintaining homeostasis and hence gives a cue to cancer development and progression. Furthermore, recent studies have revealed that SUMO system is involved in cancer metastasis. In this review, we will summarize the possible role of SUMO system in cancer development, progression, and metastasis and discuss future directions.
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Affiliation(s)
- Keun Il Kim
- Department of Biological Sciences, Research Center for Women's Disease, Sookmyung Women's University, Seoul, Korea
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Guan B, Pungaliya P, Li X, Uquillas C, Mutton LN, Rubin EH, Bieberich CJ. Ubiquitination by TOPORS regulates the prostate tumor suppressor NKX3.1. J Biol Chem 2007; 283:4834-40. [PMID: 18077445 DOI: 10.1074/jbc.m708630200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NKX3.1 gene located at 8p21.2 encodes a homeodomain-containing transcription factor that acts as a haploinsufficient tumor suppressor in prostate cancer. Diminished protein expression of NKX3.1 has been observed in prostate cancer precursors and carcinomas. TOPORS is a ubiquitously expressed E3 ubiquitin ligase that can ubiquitinate tumor suppressor p53. Here we report interaction between NKX3.1 and TOPORS. NKX3.1 can be ubiquitinated by TOPORS in vitro and in vivo, and overexpression of TOPORS leads to NKX3.1 proteasomal degradation in prostate cancer cells. Conversely, small interfering RNA-mediated knockdown of TOPORS leads to an increased steady-state level and prolonged half-life of NKX3.1. These data establish TOPORS as a negative regulator of NKX3.1 and implicate TOPORS in prostate cancer progression.
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Affiliation(s)
- Bin Guan
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, Maryland 21250, USA
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29
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Hammer E, Heilbronn R, Weger S. The E3 ligase Topors induces the accumulation of polysumoylated forms of DNA topoisomerase I in vitro and in vivo. FEBS Lett 2007; 581:5418-24. [PMID: 17976381 DOI: 10.1016/j.febslet.2007.10.040] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 10/22/2007] [Accepted: 10/22/2007] [Indexed: 11/30/2022]
Abstract
Human Topors has originally been identified as binding partner of p53 and DNA topoisomerase I (TOP1). It can function as both an ubiquitin and SUMO-1 E3 ligase for p53. Here we demonstrate that Topors enhances the formation of high-molecular weight SUMO-1 conjugates of TOP1 in a reconstituted in vitro system and also in human osteosarcoma cells, similar to treatment with CPT. In contrast to the situation observed with p53, overall sumoylation levels were rather unaffected. Experiments with TOP1 point mutants strongly suggest that the high-molecular weight conjugates represent SUMO-1 chains formed on a limited number of SUMO-1 acceptor sites.
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Affiliation(s)
- Eva Hammer
- Institute of Virology, Charité Campus Benjamin Franklin, Free University of Berlin, Hindenburgdamm 27, 12203 Berlin, Germany
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30
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Pungaliya P, Kulkarni D, Park HJ, Marshall H, Zheng H, Lackland H, Saleem A, Rubin EH. TOPORS functions as a SUMO-1 E3 ligase for chromatin-modifying proteins. J Proteome Res 2007; 6:3918-23. [PMID: 17803295 DOI: 10.1021/pr0703674] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
TOPORS is the first example of a protein with both ubiquitin and SUMO-1 E3 ligase activity and has been implicated as a tumor suppressor in several different malignancies. To gain insight into the cellular role of TOPORS, a proteomic screen was performed to identify candidate sumoylation substrates. The results indicate that many of the putative substrates are involved in chromatin modification or transcriptional regulation. Transfection studies confirmed mammalian Sin3A as a sumoylation substrate for TOPORS. These findings suggest that TOPORS may function as a tumor suppressor by regulating mSin3A and other proteins involved in chromatin modification.
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Affiliation(s)
- Pooja Pungaliya
- Department of Pharmacology, The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 195 Little Albany Street, New Brunswick, New Jersey 08901, USA
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31
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Capelson M, Corces VG. The ubiquitin ligase dTopors directs the nuclear organization of a chromatin insulator. Mol Cell 2005; 20:105-16. [PMID: 16209949 DOI: 10.1016/j.molcel.2005.08.031] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 08/10/2005] [Accepted: 08/29/2005] [Indexed: 10/25/2022]
Abstract
Chromatin insulators are gene regulatory elements implicated in the establishment of independent chromatin domains. The gypsy insulator of D. melanogaster confers its activity through a protein complex that consists of three known components, Su(Hw), Mod(mdg4)2.2, and CP190. We have identified a factor, Drosophila Topoisomerase I-interacting RS protein (dTopors) that interacts with the insulator protein complex and is required for gypsy insulator function. In the absence of Mod(mdg4)2.2, nuclear clustering of insulator complexes is disrupted and insulator activity is compromised. Overexpression of dTopors in the mod(mdg4)2.2 null mutant rescues insulator activity and restores the formation of nuclear insulator bodies. dTopors associates with the nuclear lamina, and mutations in lamin disrupt dTopors localization as well as nuclear organization and activity of the gypsy insulator. Thus, dTopors appears to be involved in the establishment of chromatin organization through its ability to mediate the association of insulator complexes with a fixed nuclear substrate.
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Affiliation(s)
- Maya Capelson
- Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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32
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Weger S, Hammer E, Heilbronn R. Topors acts as a SUMO-1 E3 ligase for p53 in vitro and in vivo. FEBS Lett 2005; 579:5007-12. [PMID: 16122737 DOI: 10.1016/j.febslet.2005.07.088] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 07/13/2005] [Accepted: 07/18/2005] [Indexed: 12/22/2022]
Abstract
Human Topors, which was originally identified as cellular binding partner of DNA topoisomerase I and of p53, has recently been shown to function as an ubiquitin E3 ligase for p53 in a manner dependent on its N'-terminally located RING finger. Here, we demonstrate that Topors also enhances the conjugation of the small ubiquitin-like modifier 1 (SUMO-1) to p53 in vivo and in a reconstituted in vitro system. The Topors SUMO-1 E3 ligase activity does not depend upon its RING finger motif. In HeLa cells, Topors induced p53 sumoylation was accompanied by an increase in endogenous p53 protein levels. Furthermore, Topors enhances the sumoylation of a variety of other, yet unidentified, cellular proteins.
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Affiliation(s)
- Stefan Weger
- Institute of Infectious Diseases, Department of Virology, Charité Campus Benjamin Franklin, Free University of Berlin, Hindenburgdamm 27, 12203 Berlin, Germany.
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33
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Bredel M, Bredel C, Juric D, Harsh GR, Vogel H, Recht LD, Sikic BI. High-resolution genome-wide mapping of genetic alterations in human glial brain tumors. Cancer Res 2005; 65:4088-96. [PMID: 15899798 DOI: 10.1158/0008-5472.can-04-4229] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
High-resolution genome-wide mapping of exact boundaries of chromosomal alterations should facilitate the localization and identification of genes involved in gliomagenesis and may characterize genetic subgroups of glial brain tumors. We have done such mapping using cDNA microarray-based comparative genomic hybridization technology to profile copy number alterations across 42,000 mapped human cDNA clones, in a series of 54 gliomas of varying histogenesis and tumor grade. This gene-by-gene approach permitted the precise sizing of critical amplicons and deletions and the detection of multiple new genetic aberrations. It has also revealed recurrent patterns of occurrence of distinct chromosomal aberrations as well as their interrelationships and showed that gliomas can be clustered into distinct genetic subgroups. A subset of detected alterations was shown predominantly associated with either astrocytic or oligodendrocytic tumor phenotype. Finally, five novel minimally deleted regions were identified in a subset of tumors, containing putative candidate tumor suppressor genes (TOPORS, FANCG, RAD51, TP53BP1, and BIK) that could have a role in gliomagenesis.
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Affiliation(s)
- Markus Bredel
- Division of Oncology, Center for Clinical Sciences Research, Stanford University School of Medicine, Stanford, California 94305-5151, USA.
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34
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Lin L, Ozaki T, Takada Y, Kageyama H, Nakamura Y, Hata A, Zhang JH, Simonds WF, Nakagawara A, Koseki H. topors, a p53 and topoisomerase I-binding RING finger protein, is a coactivator of p53 in growth suppression induced by DNA damage. Oncogene 2005; 24:3385-96. [PMID: 15735665 DOI: 10.1038/sj.onc.1208554] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The RING family zinc-finger protein topors (topoisomerase I-binding protein) binds not only topoisomerase I, but also p53 and the AAV-2 Rep78/68 proteins. topors maps to human chromosome 9p21, which contains candidate tumor suppressor genes implicated in small cell lung cancers. In this study, we isolated the murine counterpart of topors and investigated its impact on p53 function. The deduced amino-acid sequence of mouse topors exhibits extensive similarity to human topors. Overexpressed myc-tagged topors associates with and stabilizes p53, and enhances the p53-dependent transcriptional activities of p21(Waf1), MDM2 and Bax promoters and elevates endogenous p21(Waf1) mRNA levels. Overexpression of topors consequently results in the suppression of cell growth by cell cycle arrest and/or by the induction of apoptosis. Taken together, these studies identify topors as a positive regulator of p53. The expression of topors is induced by exposure to the genotoxic reagents cisplatin and camptothecin, a DNA topoisomerase I inhibitor. We therefore postulate that topors mediates p53-dependent cellular responses induced by DNA damage, suggesting its physiological role as a tumor suppressor.
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Affiliation(s)
- Ling Lin
- Department of Molecular Embryology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
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Rajendra R, Malegaonkar D, Pungaliya P, Marshall H, Rasheed Z, Brownell J, Liu LF, Lutzker S, Saleem A, Rubin EH. Topors functions as an E3 ubiquitin ligase with specific E2 enzymes and ubiquitinates p53. J Biol Chem 2004; 279:36440-4. [PMID: 15247280 DOI: 10.1074/jbc.c400300200] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The human topoisomerase I- and p53-binding protein topors contains a highly conserved, N-terminal C3HC4-type RING domain that is homologous to the RING domains of known E3 ubiquitin ligases. We demonstrate that topors functions in vitro as a RING-dependent E3 ubiquitin ligase with the E2 enzymes UbcH5a, UbcH5c, and UbcH6 but not with UbcH7, CDC34, or UbcH2b. Additional studies indicate that a conserved tryptophan within the topors RING domain is required for ubiquitination activity. Furthermore, both in vitro and cellular studies implicate p53 as a ubiquitination substrate for topors. Similar to MDM2, overexpression of topors results in a proteasome-dependent decrease in p53 protein expression in a human osteosarcoma cell line. These results are similar to the recent finding that a Drosophila topors orthologue ubiquitinates the Hairy transcriptional repressor and suggest that topors functions as a ubiquitin ligase for multiple transcription factors.
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Affiliation(s)
- Rajeev Rajendra
- Department of Pharmacology, The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick, NJ 08901, USA
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