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Jalan A, Jayasree PJ, Karemore P, Narayan KP, Khandelia P. Decoding the 'Fifth' Nucleotide: Impact of RNA Pseudouridylation on Gene Expression and Human Disease. Mol Biotechnol 2024; 66:1581-1598. [PMID: 37341888 DOI: 10.1007/s12033-023-00792-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 06/08/2023] [Indexed: 06/22/2023]
Abstract
Cellular RNAs, both coding and noncoding are adorned by > 100 chemical modifications, which impact various facets of RNA metabolism and gene expression. Very often derailments in these modifications are associated with a plethora of human diseases. One of the most oldest of such modification is pseudouridylation of RNA, wherein uridine is converted to a pseudouridine (Ψ) via an isomerization reaction. When discovered, Ψ was referred to as the 'fifth nucleotide' and is chemically distinct from uridine and any other known nucleotides. Experimental evidence accumulated over the past six decades, coupled together with the recent technological advances in pseudouridine detection, suggest the presence of pseudouridine on messenger RNA, as well as on diverse classes of non-coding RNA in human cells. RNA pseudouridylation has widespread effects on cellular RNA metabolism and gene expression, primarily via stabilizing RNA conformations and destabilizing interactions with RNA-binding proteins. However, much remains to be understood about the RNA targets and their recognition by the pseudouridylation machinery, the regulation of RNA pseudouridylation, and its crosstalk with other RNA modifications and gene regulatory processes. In this review, we summarize the mechanism and molecular machinery involved in depositing pseudouridine on target RNAs, molecular functions of RNA pseudouridylation, tools to detect pseudouridines, the role of RNA pseudouridylation in human diseases like cancer, and finally, the potential of pseudouridine to serve as a biomarker and as an attractive therapeutic target.
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Affiliation(s)
- Abhishek Jalan
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani - Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal-Malkajgiri District, Telangana, 500078, India
| | - P J Jayasree
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani - Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal-Malkajgiri District, Telangana, 500078, India
| | - Pragati Karemore
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani - Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal-Malkajgiri District, Telangana, 500078, India
| | - Kumar Pranav Narayan
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani - Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal-Malkajgiri District, Telangana, 500078, India
| | - Piyush Khandelia
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani - Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal-Malkajgiri District, Telangana, 500078, India.
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Zhang L, Zhang Y, Zhang S, Qiu L, Zhang Y, Zhou Y, Han J, Xie J. Translational Regulation by eIFs and RNA Modifications in Cancer. Genes (Basel) 2022; 13:2050. [PMID: 36360287 PMCID: PMC9690228 DOI: 10.3390/genes13112050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/25/2022] [Accepted: 11/04/2022] [Indexed: 11/04/2023] Open
Abstract
Translation is a fundamental process in all living organisms that involves the decoding of genetic information in mRNA by ribosomes and translation factors. The dysregulation of mRNA translation is a common feature of tumorigenesis. Protein expression reflects the total outcome of multiple regulatory mechanisms that change the metabolism of mRNA pathways from synthesis to degradation. Accumulated evidence has clarified the role of an increasing amount of mRNA modifications at each phase of the pathway, resulting in translational output. Translation machinery is directly affected by mRNA modifications, influencing translation initiation, elongation, and termination or altering mRNA abundance and subcellular localization. In this review, we focus on the translation initiation factors associated with cancer as well as several important RNA modifications, for which we describe their association with cancer.
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Affiliation(s)
- Linzhu Zhang
- School of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- The Third People’s Hospital of Chengdu, Clinical College of Southwest Jiao Tong University, Chengdu 610014, China
| | - Yaguang Zhang
- State Key Laboratory of Biotherapy, Frontiers Science Center for Disease-Related Molecular Network and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Su Zhang
- State Key Laboratory of Biotherapy, Frontiers Science Center for Disease-Related Molecular Network and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Lei Qiu
- State Key Laboratory of Biotherapy, Frontiers Science Center for Disease-Related Molecular Network and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yang Zhang
- State Key Laboratory of Biotherapy, Frontiers Science Center for Disease-Related Molecular Network and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Ying Zhou
- State Key Laboratory of Biotherapy, Frontiers Science Center for Disease-Related Molecular Network and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Junhong Han
- State Key Laboratory of Biotherapy, Frontiers Science Center for Disease-Related Molecular Network and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Jiang Xie
- School of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- The Third People’s Hospital of Chengdu, Clinical College of Southwest Jiao Tong University, Chengdu 610014, China
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Role of main RNA modifications in cancer: N 6-methyladenosine, 5-methylcytosine, and pseudouridine. Signal Transduct Target Ther 2022; 7:142. [PMID: 35484099 PMCID: PMC9051163 DOI: 10.1038/s41392-022-01003-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 04/12/2022] [Accepted: 04/14/2022] [Indexed: 12/16/2022] Open
Abstract
Cancer is one of the major diseases threatening human life and health worldwide. Epigenetic modification refers to heritable changes in the genetic material without any changes in the nucleic acid sequence and results in heritable phenotypic changes. Epigenetic modifications regulate many biological processes, such as growth, aging, and various diseases, including cancer. With the advancement of next-generation sequencing technology, the role of RNA modifications in cancer progression has become increasingly prominent and is a hot spot in scientific research. This review studied several common RNA modifications, such as N6-methyladenosine, 5-methylcytosine, and pseudouridine. The deposition and roles of these modifications in coding and noncoding RNAs are summarized in detail. Based on the RNA modification background, this review summarized the expression, function, and underlying molecular mechanism of these modifications and their regulators in cancer and further discussed the role of some existing small-molecule inhibitors. More in-depth studies on RNA modification and cancer are needed to broaden the understanding of epigenetics and cancer diagnosis, treatment, and prognosis.
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Affiliation(s)
- Seung Hun Han
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
- Research Institute for Natural Sciences, Hanyang University, Seoul 04763, Korea
- Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, Korea
| | - Junho Choe
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
- Research Institute for Natural Sciences, Hanyang University, Seoul 04763, Korea
- Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, Korea
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Akincilar SC, Chan CHT, Ng QF, Fidan K, Tergaonkar V. Non-canonical roles of canonical telomere binding proteins in cancers. Cell Mol Life Sci 2021; 78:4235-4257. [PMID: 33599797 PMCID: PMC8164586 DOI: 10.1007/s00018-021-03783-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 12/28/2020] [Accepted: 01/29/2021] [Indexed: 02/06/2023]
Abstract
Reactivation of telomerase is a major hallmark observed in 90% of all cancers. Yet paradoxically, enhanced telomerase activity does not correlate with telomere length and cancers often possess short telomeres; suggestive of supplementary non-canonical roles that telomerase might play in the development of cancer. Moreover, studies have shown that aberrant expression of shelterin proteins coupled with their release from shortening telomeres can further promote cancer by mechanisms independent of their telomeric role. While targeting telomerase activity appears to be an attractive therapeutic option, this approach has failed in clinical trials due to undesirable cytotoxic effects on stem cells. To circumvent this concern, an alternative strategy could be to target the molecules involved in the non-canonical functions of telomeric proteins. In this review, we will focus on emerging evidence that has demonstrated the non-canonical roles of telomeric proteins and their impact on tumorigenesis. Furthermore, we aim to address current knowledge gaps in telomeric protein functions and propose future research approaches that can be undertaken to achieve this.
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Affiliation(s)
- Semih Can Akincilar
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Claire Hian Tzer Chan
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Qin Feng Ng
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Kerem Fidan
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Vinay Tergaonkar
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore.
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore.
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Nombela P, Miguel-López B, Blanco S. The role of m 6A, m 5C and Ψ RNA modifications in cancer: Novel therapeutic opportunities. Mol Cancer 2021; 20:18. [PMID: 33461542 PMCID: PMC7812662 DOI: 10.1186/s12943-020-01263-w] [Citation(s) in RCA: 257] [Impact Index Per Article: 85.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022] Open
Abstract
RNA modifications have recently emerged as critical posttranscriptional regulators of gene expression programmes. Significant advances have been made in understanding the functional role of RNA modifications in regulating coding and non-coding RNA processing and function, which in turn thoroughly shape distinct gene expression programmes. They affect diverse biological processes, and the correct deposition of many of these modifications is required for normal development. Alterations of their deposition are implicated in several diseases, including cancer. In this Review, we focus on the occurrence of N6-methyladenosine (m6A), 5-methylcytosine (m5C) and pseudouridine (Ψ) in coding and non-coding RNAs and describe their physiopathological role in cancer. We will highlight the latest insights into the mechanisms of how these posttranscriptional modifications influence tumour development, maintenance, and progression. Finally, we will summarize the latest advances on the development of small molecule inhibitors that target specific writers or erasers to rewind the epitranscriptome of a cancer cell and their therapeutic potential.
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Affiliation(s)
- Paz Nombela
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - University of Salamanca, 37007, Salamanca, Spain
| | - Borja Miguel-López
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - University of Salamanca, 37007, Salamanca, Spain
| | - Sandra Blanco
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - University of Salamanca, 37007, Salamanca, Spain. .,Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 37007, Salamanca, Spain.
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DKC1 Overexpression Induces a More Aggressive Cellular Behavior and Increases Intrinsic Ribosomal Activity in Immortalized Mammary Gland Cells. Cancers (Basel) 2020; 12:cancers12123512. [PMID: 33255756 PMCID: PMC7760958 DOI: 10.3390/cancers12123512] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/23/2020] [Accepted: 11/23/2020] [Indexed: 12/12/2022] Open
Abstract
Simple Summary Dyskerin is a nucleolar protein involved in the modification and processing of ribosomal RNA and in the stabilization of the telomerase RNA component. In several human tumors, including breast cancer, dyskerin overexpression is found related to patients’ worse prognosis. Our aim was to study this phenomenon at the molecular and cellular levels. We firstly confirmed the correlation between high dyskerin expression with patients’ shorter survival. Then, through the generation of cellular models of increased dyskerin expression, we found that increasing dyskerin levels conferred a more aggressive phenotype and increased intrinsic ribosomal activity only in cells derived from normal breast epithelium. Our study provides evidence on the prognostic and bio-pathological relevance of the overexpression of dyskerin in breast carcinoma. A possible mechanistic explanation of the effects of dyskerin overexpression, involving specific ribosomal RNA modification and consequent increased ribosomal activity, is also provided. Abstract Dyskerin is a nucleolar protein involved in the small nucleolar RNA (snoRNA)-guided pseudouridylation of specific uridines on ribosomal RNA (rRNA), and in the stabilization of the telomerase RNA component (hTR). Loss of function mutations in DKC1 causes X-linked dyskeratosis congenita, which is characterized by a failure of proliferating tissues and increased susceptibility to cancer. However, several tumors show dyskerin overexpression. We observed that patients with primary breast cancers with high dyskerin levels are more frequently characterized by shorter survival rates and positive lymph node status than those with tumors with a lower dyskerin expression. To functionally characterize the effects of high dyskerin expression, we generated stably overexpressing DKC1 models finding that increased dyskerin levels conferred a more aggressive cellular phenotype in untransformed immortalized MCF10A cells. Contextually, DKC1 overexpression led to an upregulation of some snoRNAs, including SNORA67 and a significantly increased U1445 modification on 18S rRNA, the known target of SNORA67. Lastly, we found that dyskerin overexpression strongly enhanced the synthetic activity of ribosomes increasing translational efficiency in MCF10A. Altogether, our results indicate that dyskerin may sustain the neoplastic phenotype from an early stage in breast cancer endowing ribosomes with an augmented translation efficiency.
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Elsharawy KA, Mohammed OJ, Aleskandarany MA, Hyder A, El-Gammal HL, Abou-Dobara MI, Green AR, Dalton LW, Rakha EA. The nucleolar-related protein Dyskerin pseudouridine synthase 1 (DKC1) predicts poor prognosis in breast cancer. Br J Cancer 2020; 123:1543-1552. [PMID: 32868896 PMCID: PMC7653035 DOI: 10.1038/s41416-020-01045-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/28/2020] [Accepted: 08/13/2020] [Indexed: 12/20/2022] Open
Abstract
Background Hypertrophy of the nucleolus is a distinctive cytological feature of malignant cells and corresponds to aggressive behaviour. This study aimed to identify the key gene associated with nucleolar prominence (NP) in breast cancer (BC) and determine its prognostic significance. Methods From The Cancer Genome Atlas (TCGA) cohort, digital whole slide images identified cancers having NP served as label and an information theory algorithm was applied to find which mRNA gene best explained NP. Dyskerin Pseudouridine Synthase 1 (DKC1) was identified. DKC1 expression was assessed using mRNA data of Molecular Taxonomy of Breast Cancer International Consortium (METABRIC, n = 1980) and TCGA (n = 855). DKC1 protein expression was assessed using immunohistochemistry in Nottingham BC cohort (n = 943). Results Nuclear and nucleolar expressions of DKC1 protein were significantly associated with higher tumour grade (p < 0.0001), high nucleolar score (p < 0.001) and poor Nottingham Prognostic Index (p < 0.0001). High DKC1 expression was associated with shorter BC-specific survival (BCSS). In multivariate analysis, DKC1 mRNA and protein expressions were independent risk factors for BCSS (p < 0.01). Conclusion DKC1 expression is strongly correlated with NP and its overexpression in BC is associated with unfavourable clinicopathological characteristics and poor outcome. This has been a detailed example in the correlation of phenotype with genotype.
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Affiliation(s)
- Khloud A Elsharawy
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK.,Faculty of Science, Damietta University, Damietta, Egypt
| | - Omar J Mohammed
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK
| | - Mohammed A Aleskandarany
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK
| | - Ayman Hyder
- Faculty of Science, Damietta University, Damietta, Egypt
| | | | | | - Andrew R Green
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK
| | - Leslie W Dalton
- Department of Histopathology, South Austin Hospital, Austin, TX, USA
| | - Emad A Rakha
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK.
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Bajaj S, Kumar MS, Peters GJ, Mayur YC. Targeting telomerase for its advent in cancer therapeutics. Med Res Rev 2020; 40:1871-1919. [PMID: 32391613 DOI: 10.1002/med.21674] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 04/19/2020] [Accepted: 04/21/2020] [Indexed: 12/24/2022]
Abstract
Telomerase has emerged as an important primary target in anticancer therapy. It is a distinctive reverse transcriptase enzyme, which extends the length of telomere at the 3' chromosomal end, and uses telomerase reverse transcriptase (TERT) and telomerase RNA template-containing domains. Telomerase has a vital role and is a contributing factor in human health, mainly affecting cell aging and cell proliferation. Due to its unique feature, it ensures unrestricted cell proliferation in malignancy and plays a major role in cancer disease. The development of telomerase inhibitors with increased specificity and better pharmacokinetics is being considered to design and develop newer potent anticancer agents. Use of natural and synthetic compounds for the inhibition of telomerase activity can lead to an opening of new vistas in cancer treatment. This review details about the telomerase biochemistry, use of natural and synthetic compounds; vaccines and oncolytic virus in therapy that suppress the telomerase activity. We have discussed structure-activity relationships of various natural and synthetic telomerase inhibitors to help medicinal chemists and chemical biology researchers with a ready reference and updated status of their clinical trials. Suppression of human TERT (hTERT) activity through inhibition of hTERT promoter is an important approach for telomerase inhibition.
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Affiliation(s)
| | | | - G J Peters
- Department of Medical Oncology, VU University Medical Centre, Amsterdam, The Netherlands
| | - Y C Mayur
- SPPSPTM, SVKM's NMIMS, Mumbai, India
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Nersisyan L, Hopp L, Loeffler-Wirth H, Galle J, Loeffler M, Arakelyan A, Binder H. Telomere Length Maintenance and Its Transcriptional Regulation in Lynch Syndrome and Sporadic Colorectal Carcinoma. Front Oncol 2019; 9:1172. [PMID: 31750255 PMCID: PMC6848383 DOI: 10.3389/fonc.2019.01172] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Accepted: 10/18/2019] [Indexed: 12/14/2022] Open
Abstract
Background: Activation of telomere maintenance mechanisms (TMMs) is a hallmark of most cancers, and is required to prevent genome instability and to establish cellular immortality through reconstitution of capping of chromosome ends. TMM depends on the cancer type. Comparative studies linking tumor biology and TMM have potential impact for evaluating cancer onset and development. Methods: We have studied alterations of telomere length, their sequence composition and transcriptional regulation in mismatch repair deficient colorectal cancers arising in Lynch syndrome (LS-CRC) and microsatellite instable (MSI) sporadic CRC (MSI s-CRC), and for comparison, in microsatellite stable (MSS) s-CRC and in benign colon mucosa. Our study applied bioinformatics analysis of whole genome DNA and RNA sequencing data and a pathway model to study telomere length alterations and the potential effect of the "classical" telomerase (TEL-) and alternative (ALT-) TMM using transcriptomic signatures. Results: We have found progressive decrease of mean telomere length in all cancer subtypes compared with reference systems. Our results support the view that telomere attrition is an early event in tumorigenesis. TMM gets activated in all tumors studied due to concerted overexpression of a large fraction of genes with direct relation to telomere function, where only a very small fraction of them showed recurrent mutations. TEL-related transcriptional state was dominating in all CRC subtypes, showing, however, subtype-specific activation patterns; while contribution of the ALT-TMM was slightly more prominent in the hypermutated MSI s-CRC and LS-CRC. TEL-TMM is mainly activated by over-expression of DKC1 and/or TERT genes and their interaction partners, where DKC1 is more prominent in MSS than in MSI s-CRC and can serve as a transcriptomic marker of TMM activity. Conclusions: Our results suggest that transcriptional patterns are indicative for TMM pathway activation with subtle differences between TEL and ALT mechanisms in a CRC subtype-specific fashion. Sequencing data potentially provide a suited measure to study alterations of telomere length and of underlying transcriptional regulation. Further studies are needed to improve this method.
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Affiliation(s)
- Lilit Nersisyan
- Group of Bioinformatics, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia
| | - Lydia Hopp
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany
| | - Henry Loeffler-Wirth
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany
| | - Jörg Galle
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany
| | - Markus Loeffler
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany.,Institute for Medical Informatics, Statistics and Epidemiology, Leipzig University, Leipzig, Germany
| | - Arsen Arakelyan
- Group of Bioinformatics, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia
| | - Hans Binder
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany
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Turning Uridines around: Role of rRNA Pseudouridylation in Ribosome Biogenesis and Ribosomal Function. Biomolecules 2018; 8:biom8020038. [PMID: 29874862 PMCID: PMC6023024 DOI: 10.3390/biom8020038] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 05/28/2018] [Accepted: 05/31/2018] [Indexed: 01/09/2023] Open
Abstract
Ribosomal RNA (rRNA) is extensively edited through base methylation and acetylation, 2'-O-ribose methylation and uridine isomerization. In human rRNA, 95 uridines are predicted to by modified to pseudouridine by ribonucleoprotein complexes sharing four core proteins and differing for a RNA sequence guiding the complex to specific residues to be modified. Most pseudouridylation sites are placed within functionally important ribosomal domains and can influence ribosomal functional features. Information obtained so far only partially explained the degree of regulation and the consequences of pseudouridylation on ribosomal structure and function in different physiological and pathological conditions. This short review focuses on the available evidence in this topic, highlighting open questions in the field and perspectives that the development of emerging techniques is offering.
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The importance of being (slightly) modified: The role of rRNA editing on gene expression control and its connections with cancer. Biochim Biophys Acta Rev Cancer 2016; 1866:330-338. [PMID: 27815156 DOI: 10.1016/j.bbcan.2016.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 10/12/2016] [Accepted: 10/30/2016] [Indexed: 12/22/2022]
Abstract
In human ribosomal RNAs, over 200 residues are modified by specific, RNA-driven enzymatic complexes or stand-alone, RNA-independent enzymes. In most cases, modification sites are placed in specific positions within important functional areas of the ribosome. Some evidence indicates that the altered control in ribosomal RNA modifications may affect ribosomal function during mRNA translation. Here we provide an overview of the connections linking ribosomal RNA modifications to ribosome function, and suggest how aberrant modifications may affect the control of the expression of key cancer genes, thus contributing to tumor development. In addition, the future perspectives in this field are discussed.
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Lin P, Mobasher ME, Hakakian Y, Kakarla V, Naseem AF, Ziai H, Alawi F. Differential requirements for H/ACA ribonucleoprotein components in cell proliferation and response to DNA damage. Histochem Cell Biol 2015; 144:543-58. [PMID: 26265134 DOI: 10.1007/s00418-015-1359-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2015] [Indexed: 02/07/2023]
Abstract
H/ACA ribonucleoproteins (RNPs) are comprised of four conserved proteins, dyskerin, NHP2, NOP10, and GAR1, and a function-specifying, noncoding H/ACA RNA. H/ACA RNPs contribute to telomerase assembly and stabilization, and posttranscriptional processing of nascent ribosomal RNA and spliceosomal RNA. However, very little is known about the coordinated action of the four proteins in other biologic processes. As described herein, we observed a differential requirement for the proteins in cell proliferation and identified a possible reliance for these factors in regulation of specific DNA damage biomarkers. In particular, GAR1 expression was upregulated following exposure to all forms of genotoxic stress tested. In contrast, levels of the other proteins were either reduced or unaffected. Only GAR1 showed an altered subcellular localization with a shift from the nucleolus to the nucleoplasm after ultraviolet-C irradiation and doxorubicin treatments. Transient siRNA-mediated depletion of GAR1 and dyskerin arrested cell proliferation, whereas loss of either NHP2 or NOP10 had no effect. Finally, loss of dyskerin, GAR1, NHP2, and NOP10, respectively, limited the accumulation of DNA damage biomarkers. However, the individual responses were dependent upon the specific type of damage incurred. In general, loss of GAR1 had the most suppressive effect on the biomarkers tested. Since the specific responses to genotoxic stress, the contribution of each protein to cell proliferation, and the activation of DNA damage biomarkers were not equivalent, this suggests the possibility that at least some of the proteins, most notably GAR1, may potentially function independently of their respective roles within H/ACA RNP complexes.
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Affiliation(s)
- Ping Lin
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Levy Building - Room 328B, Philadelphia, PA, 19104, USA
| | - Maral E Mobasher
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Levy Building - Room 328B, Philadelphia, PA, 19104, USA
| | - Yasaman Hakakian
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Levy Building - Room 328B, Philadelphia, PA, 19104, USA
| | - Veena Kakarla
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Levy Building - Room 328B, Philadelphia, PA, 19104, USA
| | - Anum F Naseem
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Levy Building - Room 328B, Philadelphia, PA, 19104, USA
| | - Heliya Ziai
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Levy Building - Room 328B, Philadelphia, PA, 19104, USA
| | - Faizan Alawi
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Levy Building - Room 328B, Philadelphia, PA, 19104, USA.
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Armistead J, Patel N, Wu X, Hemming R, Chowdhury B, Basra GS, Del Bigio MR, Ding H, Triggs-Raine B. Growth arrest in the ribosomopathy, Bowen-Conradi syndrome, is due to dramatically reduced cell proliferation and a defect in mitotic progression. Biochim Biophys Acta Mol Basis Dis 2015; 1852:1029-37. [PMID: 25708872 DOI: 10.1016/j.bbadis.2015.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 02/10/2015] [Accepted: 02/14/2015] [Indexed: 02/05/2023]
Abstract
Bowen-Conradi syndrome (BCS) is a ribosomopathy characterized by severe developmental delay and growth failure that typically leads to death by one year of age. It is caused by a c.257A>G, p.D86G substitution in the ribosomal biogenesis protein, Essential for Mitotic Growth 1 (EMG1). We generated a knock-in of the D86G substitution in mice to characterize the effects of EMG1 deficiency, particularly in the brain, where EMG1 expression is high. Embryos homozygous for the mutation in Emg1 were small for gestational age with neural tube defects, and died between embryonic days 8.5 and 12.5. These embryos exhibited dramatically reduced cell proliferation, which we also detected in autopsy brain tissue and bone marrow of BCS patients, consistent with a requirement for high levels of EMG1 in tissues with rapid cell proliferation. In fibroblasts derived from the BCS mouse embryos, we detected a high proportion of binucleated cells, indicating that a mitotic defect underlies the growth arrest in BCS. These studies add to growing evidence of a link between ribosome biogenesis, mitotic progression, and brain development that is currently unexplored.
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Affiliation(s)
- Joy Armistead
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada; Manitoba Institute of Child Health, Winnipeg, MB, Canada; Institute of Developmental Biology, University of Cologne, Cologne, Germany.
| | - Nehal Patel
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada.
| | - Xiaoli Wu
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada.
| | - Richard Hemming
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada.
| | - Biswajit Chowdhury
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada; Manitoba Institute of Child Health, Winnipeg, MB, Canada.
| | - Gagandeep Singh Basra
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada.
| | - Marc R Del Bigio
- Department of Pathology, University of Manitoba, Winnipeg, MB, Canada; Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB, Canada; Manitoba Institute of Child Health, Winnipeg, MB, Canada.
| | - Hao Ding
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada.
| | - Barbara Triggs-Raine
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada; Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB, Canada; Manitoba Institute of Child Health, Winnipeg, MB, Canada.
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15
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Fong YW, Ho JJ, Inouye C, Tjian R. The dyskerin ribonucleoprotein complex as an OCT4/SOX2 coactivator in embryonic stem cells. eLife 2014; 3. [PMID: 25407680 PMCID: PMC4270071 DOI: 10.7554/elife.03573] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 11/19/2014] [Indexed: 01/06/2023] Open
Abstract
Acquisition of pluripotency is driven largely at the transcriptional level by activators OCT4, SOX2, and NANOG that must in turn cooperate with diverse coactivators to execute stem cell-specific gene expression programs. Using a biochemically defined in vitro transcription system that mediates OCT4/SOX2 and coactivator-dependent transcription of the Nanog gene, we report the purification and identification of the dyskerin (DKC1) ribonucleoprotein complex as an OCT4/SOX2 coactivator whose activity appears to be modulated by a subset of associated small nucleolar RNAs (snoRNAs). The DKC1 complex occupies enhancers and regulates the expression of key pluripotency genes critical for self-renewal in embryonic stem (ES) cells. Depletion of DKC1 in fibroblasts significantly decreased the efficiency of induced pluripotent stem (iPS) cell generation. This study thus reveals an unanticipated transcriptional role of the DKC1 complex in stem cell maintenance and somatic cell reprogramming. DOI:http://dx.doi.org/10.7554/eLife.03573.001 The stem cells found in an embryo are able to develop into any of the cell types found in the body of the animal: an ability called pluripotency. When a cell becomes a specialized cell type, such as a nerve cell or a muscle cell, it loses this ability. However, mature cells can be reprogrammed back to a pluripotent state by artificially introducing certain proteins (known as ‘reprogramming factors’) into the mature cells. A core group of reprogramming factors are known to activate networks of genes that are normally only expressed in stem cells, and by doing so trigger and maintain a pluripotent state. Other proteins help these core factors to regulate these networks of genes. In 2011, researchers discovered that a protein complex called XPC—which is normally involved in DNA repair—also helps two core reprogramming factors to activate an important gene related to pluripotency. Now, Fong et al., including several of the researchers involved in the 2011 work, have identified another unexpected partner for the same two core reprogramming factors. The protein complex, called DKC1, has a number of known functions related to the processing of RNA molecules. This complex has also been linked to a fatal, rare human disorder called dyskeratosis congenita—a condition that affects many parts of the body, including the skin and bone marrow. Fong et al. found that when embryonic stems cells from mice are depleted of the DKC1 complex, the activation of important pluripotency-related genes by two of the core reprogramming factors is markedly reduced. The XPC and DKC1 protein complexes were found to interact in pluripotent cells, and together they can activate a pluripotency-related gene to a greater extent than either can individually. Fong et al. propose that DKC1 binds to XPC, which in turn binds to two of the core reprogramming factors. The DKC1 complex also binds to RNA molecules, and Fong et al. found that when the DKC1 complex binds to certain RNAs it is more able to help reprogramming factors activate pluripotency-related genes. On the other hand, other RNA molecules seem to inhibit the complex's ability to activate these genes. Mutations identified in people with dyskeratosis congenita can prevent the DKC1 complex from binding to a subset of human RNA molecules. Moreover, the activity of stem cells is impaired in people with this developmental condition. As such, one of the next challenges will be to investigate if these mutations and RNA binding could be linked to problems with the activation of genes related to pluripotency in stem cells. DOI:http://dx.doi.org/10.7554/eLife.03573.002
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Affiliation(s)
- Yick W Fong
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Jaclyn J Ho
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Carla Inouye
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Robert Tjian
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
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Dickman CTD, Towle R, Saini R, Garnis C. Molecular characterization of immortalized normal and dysplastic oral cell lines. J Oral Pathol Med 2014; 44:329-36. [PMID: 25169794 DOI: 10.1111/jop.12236] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2014] [Indexed: 12/19/2022]
Abstract
BACKGROUND Cell lines have been developed for modeling cancer and cancer progression. The molecular background of these cell lines is often unknown to those using them to model disease behaviors. As molecular alterations are the ultimate drivers of cell phenotypes, having an understanding of the molecular make-up of these systems is critical for understanding the disease biology modeled. METHODS Six immortalized normal, one immortalized dysplasia, one self-immortalized dysplasia, and two primary normal cell lines derived from oral tissues were analyzed for DNA copy number changes and changes in both mRNA and miRNA expression using SMRT-v.2 genome-wide tiling comparative genomic hybridization arrays, Agilent Whole Genome 4x44k expression arrays, and Exiqon V2.M-RT-PCR microRNA Human panels. RESULTS DNA copy number alterations were detected in both normal and dysplastic immortalized cell lines-as well as in the single non-immortalized dysplastic cell line. These lines were found to have changes in expression of genes related to cell cycle control as well as alterations in miRNAs that are deregulated in clinical oral squamous cell carcinoma tissues. Immortal lines-whether normal or dysplastic-had increased disruption in expression relative to primary lines. All data are available as a public resource. CONCLUSIONS Molecular profiling experiments have identified DNA, mRNA, and miRNA alterations for a panel of normal and dysplastic oral tissue cell lines. These data are a valuable resource to those modeling diseases of the oral mucosa, and give insight into the selection of model cell lines and the interpretation of data from those lines.
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Affiliation(s)
- Christopher T D Dickman
- Department of Integrative Oncology, British Columbia Cancer Research Centre, Vancouver, BC, Canada
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Rocchi L, Barbosa AJM, Onofrillo C, Del Rio A, Montanaro L. Inhibition of human dyskerin as a new approach to target ribosome biogenesis. PLoS One 2014; 9:e101971. [PMID: 25010840 PMCID: PMC4092089 DOI: 10.1371/journal.pone.0101971] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 06/13/2014] [Indexed: 11/19/2022] Open
Abstract
The product of the DKC1 gene, dyskerin, is required for both ribosome biogenesis and telomerase complex stabilization. Targeting these cellular processes has been explored for the development of drugs to selectively or preferentially kill cancer cells. Presently, intense research is conducted involving the identification of new biological targets whose modulation may simultaneously interfere with multiple cellular functions that are known to be hyper-activated by neoplastic transformations. Here, we report, for the first time, the computational identification of small molecules able to inhibit dyskerin catalytic activity. Different insilico techniques were applied to select compounds and analyze the binding modes and the interaction patterns of ligands in the human dyskerin catalytic site. We also describe a newly developed and optimized fast real-time PCR assay that was used to detect dyskerin pseudouridylation activity invitro. The identification of new dyskerin inhibitors constitutes the first proof of principle that the pseudouridylation activity can be modulated by means of small molecule agents. Therefore, the presented results, obtained through the usage of computational tools and experimental validation, indicate an alternative therapeutic strategy to target ribosome biogenesis pathway.
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Affiliation(s)
- Laura Rocchi
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy
- Surgical Pathology Unit, University Hospital of Parma, Parma, Italy
| | - Arménio J. M. Barbosa
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | - Carmine Onofrillo
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy
- “Giorgio Prodi” Interdepartmental Cancer Research Centre, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | - Alberto Del Rio
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy
- Institute for Organic Chemistry and Photoreactivity, National Research Council, Bologna, Italy
- * E-mail: (ADR); (LM)
| | - Lorenzo Montanaro
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy
- * E-mail: (ADR); (LM)
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18
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Acute dyskerin depletion triggers cellular senescence and renders osteosarcoma cells resistant to genotoxic stress-induced apoptosis. Biochem Biophys Res Commun 2014; 446:1268-75. [PMID: 24690175 DOI: 10.1016/j.bbrc.2014.03.114] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 03/22/2014] [Indexed: 01/02/2023]
Abstract
Dyskerin is a conserved, nucleolar RNA-binding protein implicated in an increasing array of fundamental cellular processes. Germline mutation in the dyskerin gene (DKC1) is the cause of X-linked dyskeratosis congenita (DC). Conversely, wild-type dyskerin is overexpressed in sporadic cancers, and high-levels may be associated with poor prognosis. It was previously reported that acute loss of dyskerin function via siRNA-mediated depletion slowed the proliferation of transformed cell lines. However, the mechanisms remained unclear. Using human U2OS osteosarcoma cells, we show that siRNA-mediated dyskerin depletion induced cellular senescence as evidenced by proliferative arrest, senescence-associated heterochromatinization and a senescence-associated molecular profile. Senescence can render cells resistant to apoptosis. Conversely, chromatin relaxation can reverse the repressive effects of senescence-associated heterochromatinization on apoptosis. To this end, genotoxic stress-induced apoptosis was suppressed in dyskerin-depleted cells. In contrast, agents that induce chromatin relaxation, including histone deacetylase inhibitors and the DNA intercalator chloroquine, sensitized dyskerin-depleted cells to apoptosis. Dyskerin is a core component of the telomerase complex and plays an important role in telomere homeostasis. Defective telomere maintenance resulting in premature senescence is thought to primarily underlie the pathogenesis of X-linked DC. Since U2OS cells are telomerase-negative, this leads us to conclude that loss of dyskerin function can also induce cellular senescence via mechanisms independent of telomere shortening.
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Bedal KB, Grässel S, Oefner PJ, Reinders J, Reichert TE, Bauer R. Collagen XVI induces expression of MMP9 via modulation of AP-1 transcription factors and facilitates invasion of oral squamous cell carcinoma. PLoS One 2014; 9:e86777. [PMID: 24466237 PMCID: PMC3900656 DOI: 10.1371/journal.pone.0086777] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 12/17/2013] [Indexed: 01/08/2023] Open
Abstract
Collagen XVI belongs to the family of fibril-associated collagens with interrupted triple helices (FACIT). It is overexpressed during the progression of oral squamous cell carcinoma (OSCC). The present data show a strong collagen XVI-dependent induction of MMP9 and an increase in OSCC cell invasion. We found activated integrin-linked kinase (ILK) in a complex with kindlin-1 and activation of protein kinase B (PKB/Akt) to be responsible for MMP9 induction. Inhibition of the formation of focal adhesions reduced MMP9 expression. Moreover, collagen XVI overexpressing OSCC cell clones (COLXVI cell clones) transfected with vectors containing different MMP9 promoter fragments adjacent to a luciferase reporter revealed an increase in luciferase signal dependent on AP-1 binding sites. Deletion of the AP-1 binding site 98 bp upstream of the reported transcription start site and inhibition of AP-1 with Tanshinone IIA resulted in decreased MMP9 expression. The AP-1 subunit JunB showed differential expression between COLXVI cell clones and mock control cells. Additionally, mass spectrometric analysis of immunoprecipitates revealed that c-Fos interacted strongly with dyskerin in COLXVI cell clones compared to mock controls.
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Affiliation(s)
- Konstanze B. Bedal
- Department of Oral and Maxillofacial Surgery, University Hospital Regensburg, Regensburg, Germany
- Center for Medical Biotechnology, BioPark I, Regensburg, Germany
| | - Susanne Grässel
- Department of Orthopaedic Surgery, Experimental Orthopaedics, University Hospital Regensburg, Regensburg, Germany
- Center for Medical Biotechnology, BioPark I, Regensburg, Germany
| | - Peter J. Oefner
- Institute of Functional Genomics, University of Regensburg, Regensburg, Germany
| | - Joerg Reinders
- Institute of Functional Genomics, University of Regensburg, Regensburg, Germany
| | - Torsten E. Reichert
- Department of Oral and Maxillofacial Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Richard Bauer
- Department of Oral and Maxillofacial Surgery, University Hospital Regensburg, Regensburg, Germany
- Center for Medical Biotechnology, BioPark I, Regensburg, Germany
- * E-mail:
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20
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Liu B, Zhang J, Huang C, Liu H. Dyskerin overexpression in human hepatocellular carcinoma is associated with advanced clinical stage and poor patient prognosis. PLoS One 2012; 7:e43147. [PMID: 22912812 PMCID: PMC3418259 DOI: 10.1371/journal.pone.0043147] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 07/16/2012] [Indexed: 01/08/2023] Open
Abstract
Background Dyskerin (encoded by the DKC1 gene) is an essential nucleolar protein involved in cell proliferation, where it is required for the pseudo-uridylation of ribosomal RNA (rRNA) molecules and the stabilization of the telomerase RNA component. Dyskerin expression has been reported to predict poor survival in some cancer patients. The aim of the present study was to analyze the expression of dyskerin in hepatocellular carcinoma (HCC) and to determine its correlation with clinicopathologic features, including the survival of patients with HCC. Methodology/Principal Findings Dyskerin protein expression was detected by immunohistochemistry in paraffin sections of 252 HCC cases and 80 noncancerous liver tissues. The correlation was analyzed between dyskerin expression levels and clinicopathologic variables and prognosis. Dyskerin protein was significantly overexpressed in HCC tissues when compared to noncancerous liver tissue. Dyskerin overexpression was positively correlated with the hepatitis B surface antigen status, serum alpha-fetoprotein, and advanced clinical stage in HCC patients. A survival analysis indicated that HCC patients with higher dyskerin expression had a significantly shorter overall survival and 5-year survival time when compared to those with low expression. A multivariate analysis suggested that dyskerin overexpression was an independent factor for prognosis (hazard risk, 2.912; P = 0.007). Expression of DKC1 mRNA was measured by quantitative RT-PCR in 80 HCC and 50 non-cancerous tissues. The relationship between DKC1, TERT, MKI67, and MYC mRNA expression in HCC tissues was also evaluated. DKC1 mRNA was significantly overexpressed in HCC tissues and showed a significant correlation with MKI67 and MYC mRNA but a weak correlation with TERT mRNA. Conclusions/Significance Dyskerin overexpression in HCC patients was correlated with MYC and MKI67 expression and showed a possible involvement in the tumorigenic process. Dyskerin overexpression may be an unfavorable prognostic factor in patients with HCC.
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Affiliation(s)
- Bei Liu
- Department of Pathology, Affiliated Tianyou Hospital, Wuhan University of Science and Technology, Wuhan, China
| | - Jinglei Zhang
- Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai, China
| | - Chen Huang
- Medical Research Center, Peking University Third Hospital, Beijing, China
- * E-mail: (CH); (HL)
| | - Hui Liu
- Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai, China
- * E-mail: (CH); (HL)
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Alawi F, Lin P. Dyskerin is required for tumor cell growth through mechanisms that are independent of its role in telomerase and only partially related to its function in precursor rRNA processing. Mol Carcinog 2010; 50:334-45. [PMID: 21480387 DOI: 10.1002/mc.20715] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 10/28/2010] [Accepted: 10/29/2010] [Indexed: 12/18/2022]
Abstract
Dyskerin is an essential nucleolar protein required for the biogenesis of ribonucleoproteins that incorporate H/ACA RNAs. Through binding to specific H/ACA RNAs, dyskerin exerts most of its influence in the cell. To that end, dyskerin is a core component of the telomerase complex and is required for normal telomere maintenance. Dyskerin is also required for post-transcriptional processing of precursor rRNA. Germline dyskerin mutations increase cancer susceptibility. Conversely, wild-type dyskerin is usually over-expressed and not mutated in sporadic cancers. However, the contributions of dyskerin to sporadic tumorigenesis are unknown. Described herein, we demonstrate that acute loss of dyskerin function by RNA interference significantly reduced steady-state levels of H/ACA RNAs, disrupted the morphology and inhibited anchorage-independent growth of telomerase-positive and telomerase-negative human cell lines. Unexpectedly, dyskerin depletion only transiently delayed rRNA maturation but with no appreciable effect on the levels of total 18S or 28S rRNA. Instead, while rRNA processing defects typically trigger p53-dependent G1 arrest, dyskerin-depleted cells accumulated in G2/M by a p53-independent mechanism, and this was associated with an accumulation of aberrant mitotic figures that were characterized by multi-polar spindles. Telomerase activity and the rate of rRNA processing are typically increased during neoplasia. However, our cumulative findings indicate that dyskerin contributes to tumor cell growth through mechanisms which do not require the presence of cellular telomerase activity, and which may be only partially dependent upon the protein's role in rRNA processing. These data also reinforce the notion that loss and gain of dyskerin function may play important roles in tumorigenesis.
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Affiliation(s)
- Faizan Alawi
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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