1
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Gordon R. The chromolinker hypothesis: Are eukaryotic genomes also circular? Biosystems 2024; 244:105280. [PMID: 39097218 DOI: 10.1016/j.biosystems.2024.105280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 07/29/2024] [Accepted: 07/31/2024] [Indexed: 08/05/2024]
Abstract
Over more than the past century, reports that chromosomes in Eukaryotes are linked have been published. Recently this has been confirmed by micromanipulation. The chromolinkers are DNAse sensitive, as has been previously reported. The arguments for and against chromolinkers have been reviewed, and a call for definitive research made, because if chromolinkers do exist, the whole basis for genetics may require revision.
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Affiliation(s)
- Richard Gordon
- Gulf Specimen Marine Laboratory & Aquarium, 222 Clark Drive, Panacea, FL, 32346, USA.
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2
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Yadav V, Fuentes JL, Krishnan A, Singh N, Vohora D. Guidance for the use and interpretation of assays for monitoring anti-genotoxicity. Life Sci 2024; 337:122341. [PMID: 38101613 DOI: 10.1016/j.lfs.2023.122341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/17/2023]
Abstract
Since DNA damage can occur spontaneously or be produced by the environmental genotoxins in living cells, it is important to investigate compounds that can reverse or protect DNA damage. An appropriate methodology is essential for the responsive identification of protection offered against DNA damage. This review includes information on the current state of knowledge on prokaryotic cell-based assays (SOS chromotest, umu test, vitotox assay) and cytogenetic techniques (micronucleus assay, chromosome aberration test and sister chromatid exchange assay) with an emphasis on the possibility to explore genoprotective compounds. Throughout the last decade, studies have extrapolated the scientific methodologies utilized for genotoxicity to assess genoprotective compounds. Therefore, shortcomings of genotoxicity studies are also mirrored in antigenotoxicity studies. While regulatory authorities around the world (OECD, US-EPA and ICH) continue to update diverse genotoxic assay strategies, there are still no clear guidelines/approaches for efficient experimental design to screen genoprotective compounds. As a consequence, non-synergetic and inconsistent implementation of the test method by the researchers to execute such simulations has been adopted, which inevitably results in unreliable findings. The review has made the first attempt to collect various facets of experimentally verified approaches for evaluating genoprotective compounds, as well as to acknowledge potential significance and constraints, and further focus on the assessment of end points which are required to validate such action. Henceforth, the review makes an incredible commitment by permitting readers to equate several components of their test arrangement with the provided simplified information, allowing the selection of convenient technique for the predefined compound from a central repository.
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Affiliation(s)
- Vaishali Yadav
- Neurobehavioral Pharmacology Laboratory, Department of Pharmacology, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi 110062, India
| | - Jorge L Fuentes
- School of Biology, Science Faculty, Industrial University of Santander, Bucaramanga 680002, Santander, Colombia
| | - Anuja Krishnan
- Department of Molecular Medicine, School of Interdisciplinary Science and Technology, Jamia Hamdard, New Delhi 110062, India
| | - Neenu Singh
- Leicester School of Allied Health Sciences, Faculty of Health & Life Sciences, De Montfort University, The Gateway, Leicester LE1 9BH, UK
| | - Divya Vohora
- Neurobehavioral Pharmacology Laboratory, Department of Pharmacology, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi 110062, India.
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3
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Saayman X, Graham E, Leung CWB, Esashi F. exo-FISH: Protocol for detecting DNA breaks in repetitive regions of mammalian genomes. STAR Protoc 2023; 4:102487. [PMID: 37549036 PMCID: PMC10425934 DOI: 10.1016/j.xpro.2023.102487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/07/2023] [Accepted: 07/12/2023] [Indexed: 08/09/2023] Open
Abstract
Detecting DNA breaks in defined regions of the genome is critical to advancing our understanding of genome stability maintenance. Here, we present exo-FISH, a protocol to label exposed single-stranded DNA in defined repetitive regions of mammalian genomes by combining in vitro restriction enzyme digestion on fixed cells with fluorescence in situ hybridization (FISH). We describe steps for cell harvesting and fixation, slide treatments, and FISH probe hybridization. We then detail procedures for imaging and analysis. For complete details on the use and execution of this protocol, please refer to Saayman et al. (2023).1.
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Affiliation(s)
- Xanita Saayman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
| | - Emily Graham
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | | | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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4
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Paniagua I, Jacobs JJL. Quantification of Chromosomal Aberrations in Mammalian Cells. Bio Protoc 2023; 13:e4739. [PMID: 37638291 PMCID: PMC10450737 DOI: 10.21769/bioprotoc.4739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 03/19/2023] [Accepted: 05/10/2023] [Indexed: 08/29/2023] Open
Abstract
Maintenance of genome integrity requires efficient and faithful resolution of DNA breaks and DNA replication obstacles. Dysfunctions in any of the processes orchestrating such resolution can lead to chromosomal instability, which appears as numerical and structural chromosome aberrations. Conventional cytogenetics remains as the golden standard method to detect naturally occurring chromosomal aberrations or those resulting from the treatment with genotoxic drugs. However, the success of cytogenetic studies depends on having high-quality chromosome spreads, which has been proven to be particularly challenging. Moreover, a lack of scoring guidelines and standardized methods for treating cells with genotoxic agents contribute to significant variability amongst different studies. Here, we report a simple and effective method for obtaining well-spread chromosomes from mammalian cells for the analysis of chromosomal aberrations. In this method, cells are (1) arrested in metaphase (when chromosome morphology is clearest), (2) swollen in hypotonic solution, (3) fixed before being dropped onto microscope slides, and (4) stained with DNA dyes to visualize the chromosomes. Metaphase chromosomes are then analyzed using high-resolution microscopy. We also provide examples, representative images, and useful guidelines to facilitate the scoring of the different chromosomal aberrations. This method can be used for the diagnosis of genetic diseases, as well as for cancer studies, by identifying chromosomal defects and providing insight into the cellular processes that influence chromosome integrity.
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Affiliation(s)
- Inés Paniagua
- Division of Oncogenomics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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5
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Yi J, Luo X, Xing J, Gedanken A, Lin X, Zhang C, Qiao G. Micelle encapsulation zinc-doped copper oxide nanocomposites reverse Olaparib resistance in ovarian cancer by disrupting homologous recombination repair. Bioeng Transl Med 2023; 8:e10507. [PMID: 37206208 PMCID: PMC10189445 DOI: 10.1002/btm2.10507] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 01/22/2023] [Accepted: 03/04/2023] [Indexed: 03/31/2024] Open
Abstract
Micelle Encapsulation Zinc-doped copper oxide nanocomposites (MEnZn-CuO NPs) is a novel doped metal nanomaterial prepared by our group based on Zinc doped copper oxide nanocomposites (Zn-CuO NPs) using non-micellar beam. Compared with Zn-CuO NPs, MEnZn-CuO NPs have uniform nanoproperties and high stability. In this study, we explored the anticancer effects of MEnZn-CuO NPs on human ovarian cancer cells. In addition to affecting cell proliferation, migration, apoptosis and autophagy, MEnZn-CuO NPs have a greater potential for clinical application by inducing HR repair defects in ovarian cancer cells in combination with poly (ADP-ribose) polymerase inhibitors for lethal effects.
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Affiliation(s)
- Jingyan Yi
- Department of Medical Cell Biology and Genetics, School of Basic Medical Sciences, Nucleic Acid Medicine of Luzhou Key Laboratory, Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, (Collaborative Innovation Center for Prevention of Cardiovascular Diseases), Institute of Cardiovascular ResearchSouthwest Medical UniversityLuzhouSichuan646000China
| | - Xin Luo
- Department of Pharmacology, School of Pharmacy, Nucleic Acid Medicine of Luzhou Key LaboratorySouthwest Medical UniversityLuzhouSichuan646000China
| | - Jinshan Xing
- Department of NeurosurgeryThe Affiliated Traditional Chinese Medicine Hospital of Southwest Medical UniversityLuzhouSichuan646000China
| | - Aharon Gedanken
- Center for Advanced Materials and NanotechnologyBar‐Ilan UniversityRamat Gan52900Israel
| | - Xiukun Lin
- College of Marine SciencesBeibu Gulf University12 Binhai RoadQinzhou535011GuangxiChina
| | - Chunxiang Zhang
- Nucleic Acid Medicine of Luzhou Key Laboratory, Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, (Collaborative Innovation Center for Prevention of Cardiovascular Diseases), Institute of Cardiovascular ResearchSouthwest Medical UniversityLuzhouSichuan646000China
| | - Gan Qiao
- Department of Pharmacology, School of Pharmacy, Nucleic Acid Medicine of Luzhou Key LaboratorySouthwest Medical UniversityLuzhouSichuan646000China
- School of Pharmacy, Central Nervous System Drug Key Laboratory of Sichuan Province, Nucleic Acid Medicine of Luzhou Key Laboratory, Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, (Collaborative Innovation Center for Prevention of Cardiovascular Diseases), Institute of Cardiovascular ResearchSouthwest Medical UniversityLuzhou646000SichuanChina
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6
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Application of neural network-based image analysis to detect sister chromatid cohesion defects. Sci Rep 2023; 13:2133. [PMID: 36747022 PMCID: PMC9902603 DOI: 10.1038/s41598-023-28742-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 01/24/2023] [Indexed: 02/08/2023] Open
Abstract
Sister chromatid cohesion (SCC) is mediated by the cohesin complex and its regulatory proteins. To evaluate the involvement of a protein in cohesin regulation, preparations of metaphase chromosome spreads and classifications of chromosome shapes after depletion of the target protein are commonly employed. Although this is a convenient and approved method, the evaluation and classification of each chromosome shape has to be performed manually by researchers. Therefore, this method is time consuming, and the results might be affected by the subjectivity of researchers. In this study, we developed neural network-based image recognition models to judge the positional relationship of sister chromatids, and thereby detect SCC defects. Transfer learning models based on SqueeezeNet or ResNet-18 were trained with more than 600 chromosome images labeled with the type of chromosome, which were classified according to the positional relationship between sister chromatids. The SqueezeNet-based trained model achieved a concordance rate of 73.1% with the sample answers given by a researcher. Importantly, the model successfully detected the SCC defect in the CTF18 deficient cell line, which was used as an SCC-defective model. These results indicate that neural-network-based image recognition models are valuable tools for examining SCC defects in different genetic backgrounds.
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7
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Schmidt N, Weber B, Klekar J, Liedtke S, Breitenbach S, Heitkam T. Preparation of Mitotic Chromosomes with the Dropping Technique. Methods Mol Biol 2023; 2672:151-162. [PMID: 37335474 DOI: 10.1007/978-1-0716-3226-0_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
The quality of chromosome preparation influences all downstream analyses and is therefore crucial. Hence, numerous protocols exist to produce microscopic slides with mitotic chromosomes. Nevertheless, due to the high content of fibers in and around a plant cell, preparation of plant chromosomes is still far from trivial and needs to be fine-tuned for each species and tissue type. Here, we outline the "dropping method," a straightforward and efficient protocol to prepare multiple slides with uniform quality from a single chromosome preparation. In this method, nuclei are extracted and cleaned to produce a nuclei suspension. In a drop-by-drop manner, this suspension is then applied from a certain height onto the slides, causing the nuclei to rupture and the chromosomes to spread. Due to the physical forces that accompany the dropping and spreading process, this method is best suited for species with small- to medium-sized chromosomes.
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Affiliation(s)
- Nicola Schmidt
- Faculty of Biology, Institute of Botany, Dresden, Germany
| | - Beatrice Weber
- Faculty of Biology, Institute of Botany, Dresden, Germany
| | - Jessica Klekar
- Faculty of Biology, Institute of Botany, Dresden, Germany
| | - Susan Liedtke
- Faculty of Biology, Institute of Botany, Dresden, Germany
| | | | - Tony Heitkam
- Faculty of Biology, Institute of Botany, Dresden, Germany.
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8
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Dale KL, Armond JW, Hynds RE, Vladimirou E. Modest increase of KIF11 expression exposes fragilities in the mitotic spindle, causing chromosomal instability. J Cell Sci 2022; 135:jcs260031. [PMID: 35929456 PMCID: PMC10500341 DOI: 10.1242/jcs.260031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 08/01/2022] [Indexed: 11/20/2022] Open
Abstract
Chromosomal instability (CIN), the process of increased chromosomal alterations, compromises genomic integrity and has profound consequences on human health. Yet, our understanding of the molecular and mechanistic basis of CIN initiation remains limited. We developed a high-throughput, single-cell, image-based pipeline employing deep-learning and spot-counting models to detect CIN by automatically counting chromosomes and micronuclei. To identify CIN-initiating conditions, we used CRISPR activation in human diploid cells to upregulate, at physiologically relevant levels, 14 genes that are functionally important in cancer. We found that upregulation of CCND1, FOXA1 and NEK2 resulted in pronounced changes in chromosome counts, and KIF11 upregulation resulted in micronuclei formation. We identified KIF11-dependent fragilities within the mitotic spindle; increased levels of KIF11 caused centrosome fragmentation, higher microtubule stability, lagging chromosomes or mitotic catastrophe. Our findings demonstrate that even modest changes in the average expression of single genes in a karyotypically stable background are sufficient for initiating CIN by exposing fragilities of the mitotic spindle, which can lead to a genomically diverse cell population.
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Affiliation(s)
- Katie L. Dale
- Cancer Research UK Lung Cancer Centre of Excellence, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
- Mitotic Dynamics and Chromosomal Instability Laboratory, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
| | - Jonathan W. Armond
- Mitotic Dynamics and Chromosomal Instability Laboratory, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
| | - Robert E. Hynds
- Cancer Research UK Lung Cancer Centre of Excellence, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
- Epithelial Cell Biology in ENT Research Group, UCL Great Ormond Street Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Elina Vladimirou
- Cancer Research UK Lung Cancer Centre of Excellence, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
- Mitotic Dynamics and Chromosomal Instability Laboratory, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
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9
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Goh VST, Nakayama R, Blakely WF, Abe Y, Chua CEL, Chew ZH, Nakata A, Fujishima Y, Yoshida MA, Kasai K, Ariyoshi K, Miura T. Improved harvest and fixation methodology for isolated human peripheral blood mononuclear cells in cytokinesis-block micronucleus assay. Int J Radiat Biol 2020; 97:194-207. [PMID: 33135957 DOI: 10.1080/09553002.2021.1844338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE In suspected radiation exposures, cytokinesis-block micronucleus (CBMN) assay is used for biodosimetry by detecting micronuclei (MN) in binucleated (BN) cells in whole blood and isolated peripheral blood mononuclear cell (PBMC) cultures. Standardized harvest protocols for whole blood were published by the International Atomic Energy Agency (IAEA) in 2001 (Technical report no. 405) and 2011 (EPR-Biodosimetry). For isolated PBMC harvest, cytocentrifugation of fresh cells is recommended to preserve cytoplasmic boundaries for MN scoring. However, cytocentrifugation utilizes specialized equipment and long-term cell suspension storage is difficult. In this study, an alternative CBMN harvest protocol is proposed for laboratories interested in culturing PBMCs and storing fixed cells with routine biodosimetry methods. MATERIALS AND METHODS Peripheral blood from 4 males (24, 34, 41, 51 y.o.) and females (26, 37, 44, 56 y.o.) was irradiated with 0 and 2 Gy X-rays. For cells harvested with IAEA 2001 and 2011 protocols, whole blood was used. For cells harvested with our protocol (CRG), isolated PBMCs were used. CRG protocol was validated in DAPI, acridine orange and Giemsa stain, and in three other laboratories. Cytoplasm status, nuclear division index (NDI) and induced MN frequency (MN frequency at 2 Gy - background MN frequency at 0 Gy) (MN/1000 BN) of Giemsa-stained BN cells were compared in IAEA 2001, IAEA 2011, IAEA 2011 + formaldehyde (FA) and CRG protocols. Effects of low and high humidity spreading were evaluated. RESULTS >94% of 1000 BN cells were scorable with clear cytoplasmic boundaries in all donors harvested with CRG protocol. FA addition in IAEA 2011 protocol reduced cell rupture in whole blood cultures, but cell rupture was affected by age, sex and humidity. Almost all cells harvested with IAEA 2001 protocol had cytoplasm loss. PBMCs harvested with CRG protocol stained well in DAPI, acridine orange and Giemsa, and showed high scorable BN frequency in all laboratories. A higher NDI and a lower induced MN frequency were seen in 2 Gy isolated PBMC than whole blood cultures. CONCLUSION This quick CBMN harvest protocol for isolated PBMCs is a viable alternative to cytocentrifugation, as many scorable BN cells were obtained with routine biodosimetry reagents and equipment. IAEA 2011 + FA protocol should be used to improve CBMN harvest in whole blood cultures. Humidity during spreading should be optimized depending on the harvest protocol. NDI and MN frequency should be separately evaluated for whole blood and isolated PBMC cultures.
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Affiliation(s)
- Valerie Swee Ting Goh
- Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, Hirosaki, Japan
| | - Ryo Nakayama
- Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, Hirosaki, Japan
| | - William F Blakely
- Scientific Research Department, Armed Forces Radiobiology Research Institute (AFRRI), Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Yu Abe
- Department of Radiation Life Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Christelle En Lin Chua
- Department of Radiobiology, Singapore Nuclear Research and Safety Initiative (SNRSI), Singapore, Singapore
| | - Zi Huai Chew
- Department of Radiobiology, Singapore Nuclear Research and Safety Initiative (SNRSI), Singapore, Singapore
| | - Akifumi Nakata
- Department of Basic Pharmacy, Hokkaido Pharmaceutical University School of Pharmacy, Otaru, Japan
| | - Yohei Fujishima
- Department of Radiation Biology, Tohoku University School of Medicine, Sendai, Japan
| | | | - Kosuke Kasai
- Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, Hirosaki, Japan
| | - Kentaro Ariyoshi
- Integrated Center for Science and Humanities, Fukushima Medical University, Fukushima, Japan
| | - Tomisato Miura
- Department of Risk Analysis and Biodosimetry, Institute of Radiation Emergency Medicine, Hirosaki, Japan
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10
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Hsieh CL, Xia J, Lin H. MIWI prevents aneuploidy during meiosis by cleaving excess satellite RNA. EMBO J 2020; 39:e103614. [PMID: 32677148 DOI: 10.15252/embj.2019103614] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 06/10/2020] [Accepted: 06/16/2020] [Indexed: 01/01/2023] Open
Abstract
MIWI, a murine member of PIWI proteins mostly expressed during male meiosis, is crucial for piRNA biogenesis, post-transcriptional regulation, and spermiogenesis. However, its meiotic function remains unknown. Here, we report that MIWI deficiency alters meiotic kinetochore assembly, significantly increases chromosome misalignment at the meiosis metaphase I plate, and causes chromosome mis-segregation. Consequently, Miwi-deficient mice show elevated aneuploidy in metaphase II and spermatid death. Furthermore, in Miwi-null and Miwi slicer-deficient mutants, major and minor satellite RNAs from centromeric and pericentromeric satellite repeats accumulate in excess. Over-expression of satellite repeats in wild-type spermatocytes also causes elevated chromosome misalignment, whereas reduction of both strands of major or minor satellite RNAs results in lower frequencies of chromosome misalignment. We show that MIWI, guided by piRNA, cleaves major satellite RNAs, generating RNA fragments that may form substrates for subsequent Dicer cleavage. Furthermore, Dicer cleaves all satellite RNAs in conjunction with MIWI. These findings reveal a novel mechanism in which MIWI- and Dicer-mediated cleavage of the satellite RNAs prevents the over-expression of satellite RNAs, thus ensuring proper kinetochore assembly and faithful chromosome segregation during meiosis.
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Affiliation(s)
- Chia-Ling Hsieh
- Yale Stem Cell Center and Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Jing Xia
- Yale Stem Cell Center and Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Haifan Lin
- Yale Stem Cell Center and Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
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11
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Chennakrishnaiah S, Tsering T, Gregory C, Tawil N, Spinelli C, Montermini L, Karatzas N, Aprikian S, Choi D, Klewes L, Mai S, Rak J. Extracellular vesicles from genetically unstable, oncogene-driven cancer cells trigger micronuclei formation in endothelial cells. Sci Rep 2020; 10:8532. [PMID: 32444772 PMCID: PMC7244541 DOI: 10.1038/s41598-020-65640-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 05/07/2020] [Indexed: 01/08/2023] Open
Abstract
Oncogenic transformation impacts cancer cell interactions with their stroma, including through formation of abnormal blood vessels. This influence is often attributed to angiogenic growth factors, either soluble, or associated with tumor cell-derived extracellular vesicles (EVs). Here we examine some of the cancer-specific components of EV-mediated tumor-vascular interactions, including the impact of genetic driver mutations and genetic instability. Cancer cells expressing mutant HRAS oncogene exhibit aberrations of chromatin architecture, aneuploidy, cytoplasmic chromatin deposition and formation of micronuclei with a non-random chromosome content. EVs released from such HRAS-driven cells carry genomic DNA, including oncogenic sequences, and transfer this material to endothelial cells while inducing abnormal formation of micronuclei, along with cell migration and proliferation. Micronuclei were also triggered following treatment with EVs derived from glioma cells (and stem cells) expressing EGFRvIII oncogene, and in both endothelial cells and astrocytes. EVs from HRAS and EGFRvIII-driven cancer cells carry 19 common proteins while EVs from indolent control cells exhibit more divergent proteomes. Immortalized endothelial cell lines with disrupted TP53 pathway were refractory to EV-mediated micronuclei induction. We suggest that oncogenic transformation and intercellular trafficking of cancer-derived EVs may contribute to pathological vascular responses in cancer due to intercellular transmission of genomic instability.
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Affiliation(s)
- Shilpa Chennakrishnaiah
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Thupten Tsering
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Caroline Gregory
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Nadim Tawil
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Cristiana Spinelli
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Laura Montermini
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Nicolaos Karatzas
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Saro Aprikian
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Dongsic Choi
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Ludger Klewes
- Department of Cell Biology, Research Institute of Oncology and Hematology, Cancer Care Manitoba, University of Manitoba, Winnipeg, Canada
| | - Sabine Mai
- Department of Cell Biology, Research Institute of Oncology and Hematology, Cancer Care Manitoba, University of Manitoba, Winnipeg, Canada
| | - Janusz Rak
- Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada.
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12
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Baudoin NC, Nicholson JM, Soto K, Martin O, Chen J, Cimini D. Asymmetric clustering of centrosomes defines the early evolution of tetraploid cells. eLife 2020; 9:54565. [PMID: 32347795 PMCID: PMC7250578 DOI: 10.7554/elife.54565] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/28/2020] [Indexed: 12/13/2022] Open
Abstract
Tetraploidy has long been of interest to both cell and cancer biologists, partly because of its documented role in tumorigenesis. A common model proposes that the extra centrosomes that are typically acquired during tetraploidization are responsible for driving tumorigenesis. However, tetraploid cells evolved in culture have been shown to lack extra centrosomes. This observation raises questions about how tetraploid cells evolve and more specifically about the mechanisms(s) underlying centrosome loss. Here, using a combination of fixed cell analysis, live cell imaging, and mathematical modeling, we show that populations of newly formed tetraploid cells rapidly evolve in vitro to retain a near-tetraploid chromosome number while losing the extra centrosomes gained at the time of tetraploidization. This appears to happen through a process of natural selection in which tetraploid cells that inherit a single centrosome during a bipolar division with asymmetric centrosome clustering are favored for long-term survival.
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Affiliation(s)
- Nicolaas C Baudoin
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, United States
| | - Joshua M Nicholson
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, United States
| | - Kimberly Soto
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, United States
| | - Olga Martin
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, United States
| | - Jing Chen
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, United States
| | - Daniela Cimini
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, United States
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13
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Zhao Q, Coughlan KA, Zou MH, Song P. Loss of AMPKalpha1 Triggers Centrosome Amplification via PLK4 Upregulation in Mouse Embryonic Fibroblasts. Int J Mol Sci 2020; 21:ijms21082772. [PMID: 32316320 PMCID: PMC7216113 DOI: 10.3390/ijms21082772] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 04/15/2020] [Accepted: 04/15/2020] [Indexed: 11/16/2022] Open
Abstract
Recent evidence indicates that activation of adenosine monophosphate-activated protein kinase (AMPK), a highly conserved sensor and modulator of cellular energy and redox, regulates cell mitosis. However, the underlying molecular mechanisms for AMPKα subunit regulation of chromosome segregation remain poorly understood. This study aimed to ascertain if AMPKα1 deletion contributes to chromosome missegregation by elevating Polo-like kinase 4 (PLK4) expression. Centrosome proteins and aneuploidy were monitored in cultured mouse embryonic fibroblasts (MEFs) isolated from wild type (WT, C57BL/6J) or AMPKα1 homozygous deficient (AMPKα1−/−) mice by Western blotting and metaphase chromosome spread. Deletion of AMPKα1, the predominant AMPKα isoform in immortalized MEFs, led to centrosome amplification and chromosome missegregation, as well as the consequent aneuploidy (34–66%) and micronucleus. Furthermore, AMPKα1 null cells exhibited a significant induction of PLK4. Knockdown of nuclear factor kappa B2/p52 ameliorated the PLK4 elevation in AMPKα1-deleted MEFs. Finally, PLK4 inhibition by Centrinone reversed centrosome amplification of AMPKα1-deleted MEFs. Taken together, our results suggest that AMPKα1 plays a fundamental role in the maintenance of chromosomal integrity through the control of p52-mediated transcription of PLK4, a trigger of centriole biogenesis.
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Affiliation(s)
- Qiang Zhao
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30302, USA; (Q.Z.); (M.-H.Z.)
| | | | - Ming-Hui Zou
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30302, USA; (Q.Z.); (M.-H.Z.)
| | - Ping Song
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30302, USA; (Q.Z.); (M.-H.Z.)
- Correspondence: ; Tel.: +1-404-413-6636
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14
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Meijering AEC, Biebricher AS, Sitters G, Brouwer I, Peterman EJG, Wuite GJL, Heller I. Imaging unlabeled proteins on DNA with super-resolution. Nucleic Acids Res 2020; 48:e34. [PMID: 32016413 PMCID: PMC7102996 DOI: 10.1093/nar/gkaa061] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/24/2019] [Accepted: 01/24/2020] [Indexed: 02/06/2023] Open
Abstract
Fluorescence microscopy is invaluable to a range of biomolecular analysis approaches. The required labeling of proteins of interest, however, can be challenging and potentially perturb biomolecular functionality as well as cause imaging artefacts and photo bleaching issues. Here, we introduce inverse (super-resolution) imaging of unlabeled proteins bound to DNA. In this new method, we use DNA-binding fluorophores that transiently label bare DNA but not protein-bound DNA. In addition to demonstrating diffraction-limited inverse imaging, we show that inverse Binding-Activated Localization Microscopy or 'iBALM' can resolve biomolecular features smaller than the diffraction limit. The current detection limit is estimated to lie at features between 5 and 15 nm in size. Although the current image-acquisition times preclude super-resolving fast dynamics, we show that diffraction-limited inverse imaging can reveal molecular mobility at ∼0.2 s temporal resolution and that the method works both with DNA-intercalating and non-intercalating dyes. Our experiments show that such inverse imaging approaches are valuable additions to the single-molecule toolkit that relieve potential limitations posed by labeling.
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Affiliation(s)
- Anna E C Meijering
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Andreas S Biebricher
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Gerrit Sitters
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Ineke Brouwer
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Erwin J G Peterman
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Gijs J L Wuite
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Iddo Heller
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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15
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Wu PH, Gilkes DM, Phillip JM, Narkar A, Cheng TWT, Marchand J, Lee MH, Li R, Wirtz D. Single-cell morphology encodes metastatic potential. SCIENCE ADVANCES 2020; 6:eaaw6938. [PMID: 32010778 PMCID: PMC6976289 DOI: 10.1126/sciadv.aaw6938] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 11/13/2019] [Indexed: 05/10/2023]
Abstract
A central goal of precision medicine is to predict disease outcomes and design treatments based on multidimensional information from afflicted cells and tissues. Cell morphology is an emergent readout of the molecular underpinnings of a cell's functions and, thus, can be used as a method to define the functional state of an individual cell. We measured 216 features derived from cell and nucleus morphology for more than 30,000 breast cancer cells. We find that single cell-derived clones (SCCs) established from the same parental cells exhibit distinct and heritable morphological traits associated with genomic (ploidy) and transcriptomic phenotypes. Using unsupervised clustering analysis, we find that the morphological classes of SCCs predict distinct tumorigenic and metastatic potentials in vivo using multiple mouse models of breast cancer. These findings lay the groundwork for using quantitative morpho-profiling in vitro as a potentially convenient and economical method for phenotyping function in cancer in vivo.
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Affiliation(s)
- Pei-Hsun Wu
- Johns Hopkins Physical Sciences–Oncology Center, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Daniele M. Gilkes
- Johns Hopkins Physical Sciences–Oncology Center, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Jude M. Phillip
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Akshay Narkar
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Thomas Wen-Tao Cheng
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
- Division of Vascular and Endovascular Surgery, Boston Medical Center, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jorge Marchand
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Meng-Horng Lee
- Johns Hopkins Physical Sciences–Oncology Center, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Rong Li
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
- Mechanobiology Institute National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore
| | - Denis Wirtz
- Johns Hopkins Physical Sciences–Oncology Center, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
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16
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Yao Q, Gao J, Chen F, Li W. Development and application of an optimized drop-slide technique for metaphase chromosome spreads in maize. Biotech Histochem 2019; 95:276-284. [PMID: 31762324 DOI: 10.1080/10520295.2019.1686167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Chromosome spreads are important for complex molecular cytogenetic studies. An adequate chromosome spreading method for identification and isolation of the maize B chromosome, however, has not been reported. We used the maize inbred lines, B73 and Mo17, the hybrid YD08 line and the landrace DP76 to develop an optimized chromosome spreading method. We investigated the effects of four treatment factors on the quality of metaphase chromosome spreads using a factorial analysis of variance. Optimal conditions for metaphase spreading were identified using regression analysis based on multifactor orthogonal design of four treatment factors with five levels for each factor. We developed optimal conditions for metaphase spreading as follows: nitrous oxide treatment for 2 h, glacial acetic acid fixation for 2 h, enzyme hydrolysis for 6.0 h, and a drop height of 35 cm for cell suspension. We obtained high quality metaphase chromosome spreads with large metaphase areas, large numbers of chromosomes, few chromosome overlaps and high frequency of intact metaphases. Our optimized drop-slide procedure was markedly better than the traditional flame smear technique. We identified 487 B chromosomes in three forms from maize landraces from Southwest China. We found no relation between the C-band number and B chromosome. Single B chromosomes also were isolated directly from a metaphase chromosome drop-slide using a micromanipulator. Our optimized method provides a simple, efficient and reproducible procedure for preparing high quality plant chromosome spreads.
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Affiliation(s)
- Qilun Yao
- Department of Life Sciences, Yangtze Normal University, Fuling 408100, P. R. China.,Centre for Green Development and Collaborative Innovation in Wuling Mountain Region, Yangtze Normal University, Fuling, 408100, P. R. China
| | - Jian Gao
- Department of Life Sciences, Yangtze Normal University, Fuling 408100, P. R. China.,Centre for Green Development and Collaborative Innovation in Wuling Mountain Region, Yangtze Normal University, Fuling, 408100, P. R. China
| | - Fabo Chen
- Department of Life Sciences, Yangtze Normal University, Fuling 408100, P. R. China.,Centre for Green Development and Collaborative Innovation in Wuling Mountain Region, Yangtze Normal University, Fuling, 408100, P. R. China
| | - Wenbo Li
- Department of Life Sciences, Yangtze Normal University, Fuling 408100, P. R. China.,Centre for Green Development and Collaborative Innovation in Wuling Mountain Region, Yangtze Normal University, Fuling, 408100, P. R. China
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17
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Pang PS, Liu T, Lin W, Tsang CM, Yip YL, Zhou Y, Guan XY, Chan RCK, Tsao SW, Deng W. Defining early events of Epstein-Barr virus (EBV) infection in immortalized nasopharyngeal epithelial cells using cell-free EBV infection. J Gen Virol 2019; 100:999-1012. [PMID: 30816843 DOI: 10.1099/jgv.0.001243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Epstein-Barr virus (EBV) infection is strongly associated with nasopharyngeal carcinoma, a common cancer in Southeast Asia and certain regions of Africa. However, the dynamics of EBV episome maintenance in infected nasopharyngeal epithelial (NPE) cells remain largely undefined. Here, we report the establishment of a highly efficient cell-free EBV infection method for NPE cells. By using this method, we have defined some of the dynamic events involved in the early stage of EBV infection in NPE cells. We report, for the first time, a rapid loss of EBV copies from infected NPE cells during the first 12-72 h post-infection. The rate of EBV loss slowed at later stages of infection. Live cell imaging revealed that the freshly infected NPE cells were delayed in entry into mitosis compared with uninfected cells. Freshly infected NPE cells transcribed significantly higher levels of lytic EBV genes BZLF1 and BMRF1 yet significantly lower levels of EBER1/2 than stably infected NPE cells. Notably, there were very low or undetectable levels of protein expressions of EBNA1, LMP1, Zta and Rta in freshly infected NPE cells, whereas EBNA1 and LMP1 proteins were readily detected in stable EBV-infected NPE cells. The kinetics of EBV loss and the differential EBV gene expression profiles between freshly and stably infected NPE cells are in line with the suggestion of epigenetic changes in the EBV genome that affect viral gene expression and the adaptation of host cells to EBV infection to maintain persistent EBV infection in NPE cells.
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Affiliation(s)
- Pei Shin Pang
- 1School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China
| | - Tengfei Liu
- 1School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China
| | - Weitao Lin
- 1School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China
| | - Chi-Man Tsang
- 1School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China.,2Department of Anatomical and Cellular Pathology, The State Key Translational Laboratory, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Yim-Ling Yip
- 1School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China
| | - Yuan Zhou
- 1School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China
| | - Xin-Yuan Guan
- 3Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China
| | - Ronald Cheong-Kin Chan
- 2Department of Anatomical and Cellular Pathology, The State Key Translational Laboratory, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Sai-Wah Tsao
- 1School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China
| | - Wen Deng
- 4School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, PR China
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18
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Abstract
Fluorescence in situ hybridization (FISH) is used to examine chromosomal abnormalities and DNA damage. Developed in the early 1980s, this technique remains an important tool for understanding chromosome biology and diagnosing genetic disease and cancer. Use of FISH on metaphase chromosomes allows the visualization of chromosomal abnormalities at specific loci. Here, we describe methods for creating metaphase chromosome spreads and the use of telomere FISH probes to detect chromosome ends.
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Affiliation(s)
- P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA.
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19
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Lin W, Yip YL, Jia L, Deng W, Zheng H, Dai W, Ko JMY, Lo KW, Chung GTY, Yip KY, Lee SD, Kwan JSH, Zhang J, Liu T, Chan JYW, Kwong DLW, Lee VHF, Nicholls JM, Busson P, Liu X, Chiang AKS, Hui KF, Kwok H, Cheung ST, Cheung YC, Chan CK, Li B, Cheung ALM, Hau PM, Zhou Y, Tsang CM, Middeldorp J, Chen H, Lung ML, Tsao SW. Establishment and characterization of new tumor xenografts and cancer cell lines from EBV-positive nasopharyngeal carcinoma. Nat Commun 2018; 9:4663. [PMID: 30405107 PMCID: PMC6220246 DOI: 10.1038/s41467-018-06889-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 09/25/2018] [Indexed: 12/30/2022] Open
Abstract
The lack of representative nasopharyngeal carcinoma (NPC) models has seriously hampered research on EBV carcinogenesis and preclinical studies in NPC. Here we report the successful growth of five NPC patient-derived xenografts (PDXs) from fifty-eight attempts of transplantation of NPC specimens into NOD/SCID mice. The take rates for primary and recurrent NPC are 4.9% and 17.6%, respectively. Successful establishment of a new EBV-positive NPC cell line, NPC43, is achieved directly from patient NPC tissues by including Rho-associated coiled-coil containing kinases inhibitor (Y-27632) in culture medium. Spontaneous lytic reactivation of EBV can be observed in NPC43 upon withdrawal of Y-27632. Whole-exome sequencing (WES) reveals a close similarity in mutational profiles of these NPC PDXs with their corresponding patient NPC. Whole-genome sequencing (WGS) further delineates the genomic landscape and sequences of EBV genomes in these newly established NPC models, which supports their potential use in future studies of NPC. The lack of appropriate models restricts pre-clinical research for nasopharyngeal carcinoma (NPC). Here the authors report the development and characterization of NPC patient-derived xenografts (PDXs), and EBV positive NPC cell line from patient tumor, and suggest their potential use in future NPC research.
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Affiliation(s)
- Weitao Lin
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Yim Ling Yip
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Lin Jia
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Wen Deng
- School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Hong Zheng
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.,Center for Biomedical Informatics Research, Stanford University, Stanford, 94305, CA, USA
| | - Wei Dai
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Josephine Mun Yee Ko
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Kwok Wai Lo
- Department of Anatomical and Cellular Pathology and State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Hong Kong, China
| | - Grace Tin Yun Chung
- Department of Anatomical and Cellular Pathology and State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Hong Kong, China
| | - Kevin Y Yip
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Sau-Dan Lee
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Johnny Sheung-Him Kwan
- Department of Anatomical and Cellular Pathology and State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Hong Kong, China
| | - Jun Zhang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Tengfei Liu
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Jimmy Yu-Wai Chan
- Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Dora Lai-Wan Kwong
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Victor Ho-Fun Lee
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - John Malcolm Nicholls
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Pierre Busson
- Gustave Roussy, Paris-Saclay University, CNRS, UMR8126, Villejuif, F-94805, France
| | - Xuefeng Liu
- Center for Cell Reprogramming, Department of Pathology, Georgetown University Medical Center, Washington, 20057, DC, USA.,Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, China.,Affiliated Cancer Hospital & Institute, Guangzhou Medical University, Guangzhou, 510095, Guangdong, China
| | - Alan Kwok Shing Chiang
- Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Kwai Fung Hui
- Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Hin Kwok
- Center for Genomic Sciences, The University of Hong Kong, Hong Kong, China
| | - Siu Tim Cheung
- Department of Surgery and Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Yuk Chun Cheung
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Chi Keung Chan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Bin Li
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.,College of Life Science and Technology, Jinan University, Guangzhou, 510632, Guangdong, China
| | - Annie Lai-Man Cheung
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Pok Man Hau
- Department of Anatomical and Cellular Pathology and State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Hong Kong, China
| | - Yuan Zhou
- Department of Anatomical and Cellular Pathology and State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Hong Kong, China
| | - Chi Man Tsang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.,Department of Anatomical and Cellular Pathology and State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Hong Kong, China
| | - Jaap Middeldorp
- VU University Medical Center, Department of Pathology, Cancer Center Amsterdam, de Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands
| | - Honglin Chen
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Maria Li Lung
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
| | - Sai Wah Tsao
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
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20
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Yip YL, Lin W, Deng W, Jia L, Lo KW, Busson P, Vérillaud B, Liu X, Tsang CM, Lung ML, Tsao SW. Establishment of a nasopharyngeal carcinoma cell line capable of undergoing lytic Epstein-Barr virus reactivation. J Transl Med 2018; 98:1093-1104. [PMID: 29769697 DOI: 10.1038/s41374-018-0034-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/22/2017] [Accepted: 01/10/2018] [Indexed: 01/30/2023] Open
Abstract
Epstein-Barr virus (EBV) infects more than 90% of the adult human population. Undifferentiated nasopharyngeal carcinoma (NPC) is common in Southeast Asia, with a particularly high incidence among southern Chinese. The EBV genome can be detected in practically all cancer cells in undifferentiated NPC. The role of EBV in pathogenesis of undifferentiated NPC remains elusive. NPC cell lines are known to be difficult to establish in culture. The EBV+ve NPC cell lines, even if established in culture, rapidly lost their EBV episomes upon prolonged propagation. At present, the C666-1 NPC cell line, which is defective in lytic EBV reactivation, is the only EBV+ve NPC cell line available for NPC and EBV research. The need to establish new and representative NPC cell lines is eminent for NPC and EBV research. In this study, we report the use of the Rho-associated kinase inhibitor (Y-27632) has facilitated the establishment of a new EBV+ve NPC cell line from an earlier established NPC xenograft, C17. The C17 cell line was tumorigenic in immune-deficient mice (NOD/SCID). It retained the EBV episomes and could be induced to undergo productive lytic reactivation of EBV to generate infectious virus particles. The C17 cell line represents a new investigative tool for NPC and EBV studies. The ability of C17 to undergo lytic reactivation is unique and opens up the opportunity to examine regulation of latent and lytic infection of EBV and their contributions to NPC pathogenesis.
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Affiliation(s)
- Yim Ling Yip
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Weitao Lin
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Wen Deng
- School of Nursing, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Lin Jia
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Kwok Wai Lo
- Department of Anatomical and Cellular Pathology, State Key Laboratory in Oncology in South China, Prince of Wales Hospital, Shatin, Hong Kong
| | - Pierre Busson
- Laboratoire de Biologie des Tumeurs Humaines, Institut Gustave Roussy, Villejuif, France
| | - Benjamin Vérillaud
- Laboratoire de Biologie des Tumeurs Humaines, Institut Gustave Roussy, Villejuif, France
| | - Xuefeng Liu
- Department of Pathology and Center for Cellular Reprogramming, Georgetown University Medical Center, Washington, DC, USA.,Cancer Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Chi Man Tsang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Maria Li Lung
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Sai Wah Tsao
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China.
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21
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Balázs M, Koroknai V, Szász I, Ecsedi S. Detection of CCND1 Locus Amplification by Fluorescence In Situ Hybridization. Methods Mol Biol 2018; 1726:85-100. [PMID: 29468546 DOI: 10.1007/978-1-4939-7565-5_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
It is well known that chromosomal aberrations of tumors are associated with the initiation and progression of malignancy. Fluorescence in situ hybridization (FISH) is a powerful, rapid method to detect chromosome copy number and structural alterations in tissue sections, chromosome, or interphase cellular preparations via hybridization of complementary probe sequences. The technique is based on the complementary nature of DNA double strands, which allows fluorescently labeled DNA probes to be used as probes to label the complementary sequences of target cells, chromosomes, and tissues. FISH technique has many applications, including basic gene mapping, used in pathological diagnosis to detect chromosome and gene copy number aberrations, translocations, microdeletions, and duplications. For the recognition of gene amplifications and deletions, locus-specific probes that are collections of one or a few cloned DNA sequences are routinely used. Multiplex-FISH (M-FISH) technique visualizes all chromosomes with different colors using spectrally distinct fluorophores for each chromosome in one experiment to detect numerical and structural alterations of chromosomes obtained from tumor cells. Recently many of the gene-specific probes are commercially available.
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Affiliation(s)
- Margit Balázs
- Department of Preventive Medicine, Faculty of Public Health, University of Debrecen, Debrecen, Hungary.
| | - Viktória Koroknai
- MTA-DE Public Health Research Group, University of Debrecen, Debrecen, Hungary
| | - István Szász
- MTA-DE Public Health Research Group, University of Debrecen, Debrecen, Hungary
| | - Szilvia Ecsedi
- MTA-DE Public Health Research Group, University of Debrecen, Debrecen, Hungary
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22
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Jeynes JCG, Geraki K, Jeynes C, Zhaohong M, Bettiol AA, Latorre E, Harries LW, Soeller C. Nanoscale Properties of Human Telomeres Measured with a Dual Purpose X-ray Fluorescence and Super Resolution Microscopy Gold Nanoparticle Probe. ACS NANO 2017; 11:12632-12640. [PMID: 29091397 PMCID: PMC5951601 DOI: 10.1021/acsnano.7b07064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 11/01/2017] [Indexed: 05/18/2023]
Abstract
Techniques to analyze human telomeres are imperative in studying the molecular mechanism of aging and related diseases. Two important aspects of telomeres are their length in DNA base pairs (bps) and their biophysical nanometer dimensions. However, there are currently no techniques that can simultaneously measure these quantities in individual cell nuclei. Here, we develop and evaluate a telomere "dual" gold nanoparticle-fluorescent probe simultaneously compatible with both X-ray fluorescence (XRF) and super resolution microscopy. We used silver enhancement to independently visualize the spatial locations of gold nanoparticles inside the nuclei, comparing to a standard QFISH (quantitative fluorescence in situ hybridization) probe, and showed good specificity at ∼90%. For sensitivity, we calculated telomere length based on a DNA/gold binding ratio using XRF and compared to quantitative polymerase chain reaction (qPCR) measurements. The sensitivity was low (∼10%), probably because of steric interference prohibiting the relatively large 10 nm gold nanoparticles access to DNA space. We then measured the biophysical characteristics of individual telomeres using super resolution microscopy. Telomeres that have an average length of ∼10 kbps, have diameters ranging between ∼60-300 nm. Further, we treated cells with a telomere-shortening drug and showed there was a small but significant difference in telomere diameter in drug-treated vs control cells. We discuss our results in relation to the current debate surrounding telomere compaction.
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Affiliation(s)
- J. Charles G. Jeynes
- Centre
for Biomedical Modelling and Analysis, University
of Exeter, Exeter, Devon, U.K., EX2 5DW
- E-mail:
| | | | | | - Mi Zhaohong
- Centre
for Ion Beam Applications, National University
of Singapore, Singapore, 119077
| | - Andrew A. Bettiol
- Centre
for Ion Beam Applications, National University
of Singapore, Singapore, 119077
| | - Eva Latorre
- Medical
School, RILD Building, University of Exeter, Barrack Road, Exeter, Devon, EX2 5DW
| | - Lorna Wendy Harries
- Medical
School, RILD Building, University of Exeter, Barrack Road, Exeter, Devon, EX2 5DW
| | - Christian Soeller
- Living
Systems
Institute & Biomedical Physics, University
of Exeter, Exeter, Devon, U.K., EX2 5DW
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23
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Kukolj E, Kaufmann T, Dick AE, Zeillinger R, Gerlich DW, Slade D. PARP inhibition causes premature loss of cohesion in cancer cells. Oncotarget 2017; 8:103931-103951. [PMID: 29262611 PMCID: PMC5732777 DOI: 10.18632/oncotarget.21879] [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: 06/22/2017] [Accepted: 09/22/2017] [Indexed: 12/11/2022] Open
Abstract
Poly(ADP-ribose) polymerases (PARPs) regulate various aspects of cellular function including mitotic progression. Although PARP inhibitors have been undergoing various clinical trials and the PARP1/2 inhibitor olaparib was approved as monotherapy for BRCA-mutated ovarian cancer, their mode of action in killing tumour cells is not fully understood. We investigated the effect of PARP inhibition on mitosis in cancerous (cervical, ovary, breast and osteosarcoma) and non-cancerous cells by live-cell imaging. The clinically relevant inhibitor olaparib induced strong perturbations in mitosis, including problems with chromosome alignment at the metaphase plate, anaphase delay, and premature loss of cohesion (cohesion fatigue) after a prolonged metaphase arrest, resulting in sister chromatid scattering. PARP1 and PARP2 depletion suppressed the phenotype while PARP2 overexpression enhanced it, suggesting that olaparib-bound PARP1 and PARP2 rather than the lack of catalytic activity causes this phenotype. Olaparib-induced mitotic chromatid scattering was observed in various cancer cell lines with increased protein levels of PARP1 and PARP2, but not in non-cancer or cancer cell lines that expressed lower levels of PARP1 or PARP2. Interestingly, the sister chromatid scattering phenotype occurred only when olaparib was added during the S-phase preceding mitosis, suggesting that PARP1 and PARP2 entrapment at replication forks impairs sister chromatid cohesion. Clinically relevant DNA-damaging agents that impair replication progression such as topoisomerase inhibitors and cisplatin were also found to induce sister chromatid scattering and metaphase plate alignment problems, suggesting that these mitotic phenotypes are a common outcome of replication perturbation.
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Affiliation(s)
- Eva Kukolj
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, Vienna, Austria
| | - Tanja Kaufmann
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, Vienna, Austria
| | - Amalie E Dick
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, Vienna, Austria
| | - Robert Zeillinger
- Molecular Oncology Group, Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria
| | - Daniel W Gerlich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, Vienna, Austria
| | - Dea Slade
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, Vienna, Austria
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24
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Rodríguez-Domínguez JM, Ríos-Lara LL, Tapia-Campos E, Barba-Gonzalez R. An improved technique for obtaining well-spread metaphases from plants with numerous large chromosomes. Biotech Histochem 2017; 92:159-166. [PMID: 28418749 DOI: 10.1080/10520295.2017.1288927] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Preparations that contain well-spread metaphase chromosomes are critical for plant cytogenetic analyses including chromosome counts, banding procedures, in situ hybridization, karyotyping and construction of ideograms. Chromosome spreading is difficult for plants with large and numerous chromosomes. We report here a technique for obtaining cytoplasm-free, well-spread metaphases from two Amaryllidaceae species: Sprekelia formosissima (2n = 120) and Hymenocallis howardii (2n = 96). The technique has three main steps: 1) pretreatment to cause chromosome condensation, 2) dripping onto tilted slides coated with a thin layer of pure acetic acid and 3) application of steam and acetic acid to produce cytoplasmic hydrolysis, which spreads the chromosomes.
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Affiliation(s)
- J M Rodríguez-Domínguez
- a Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco , A.C. Unidad de Biotecnología Vegetal , Guadalajara , Jalisco , México
| | - L L Ríos-Lara
- a Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco , A.C. Unidad de Biotecnología Vegetal , Guadalajara , Jalisco , México
| | - E Tapia-Campos
- a Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco , A.C. Unidad de Biotecnología Vegetal , Guadalajara , Jalisco , México
| | - R Barba-Gonzalez
- a Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco , A.C. Unidad de Biotecnología Vegetal , Guadalajara , Jalisco , México
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25
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Pathak R, Koturbash I, Hauer-Jensen M. Detection of Inter-chromosomal Stable Aberrations by Multiple Fluorescence In Situ Hybridization (mFISH) and Spectral Karyotyping (SKY) in Irradiated Mice. J Vis Exp 2017. [PMID: 28117817 DOI: 10.3791/55162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Ionizing radiation (IR) induces numerous stable and unstable chromosomal aberrations. Unstable aberrations, where chromosome morphology is substantially compromised, can easily be identified by conventional chromosome staining techniques. However, detection of stable aberrations, which involve exchange or translocation of genetic materials without considerable modification in the chromosome morphology, requires sophisticated chromosome painting techniques that rely on in situ hybridization of fluorescently labeled DNA probes, a chromosome painting technique popularly known as fluorescence in situ hybridization (FISH). FISH probes can be specific for whole chromosome/s or precise sub-region on chromosome/s. The method not only allows visualization of stable aberrations, but it can also allow detection of the chromosome/s or specific DNA sequence/s involved in a particular aberration formation. A variety of chromosome painting techniques are available in cytogenetics; here two highly sensitive methods, multiple fluorescence in situ hybridization (mFISH) and spectral karyotyping (SKY), are discussed to identify inter-chromosomal stable aberrations that form in the bone marrow cells of mice after exposure to total body irradiation. Although both techniques rely on fluorescent labeled DNA probes, the method of detection and the process of image acquisition of the fluorescent signals are different. These two techniques have been used in various research areas, such as radiation biology, cancer cytogenetics, retrospective radiation biodosimetry, clinical cytogenetics, evolutionary cytogenetics, and comparative cytogenetics.
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Affiliation(s)
- Rupak Pathak
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences;
| | - Igor Koturbash
- Department of Environmental Health, Fay W. Boozman School of Public Health, University of Arkansas for Medical Sciences
| | - Martin Hauer-Jensen
- Division of Radiation Health, Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences; Surgical Service, Central Arkansas Veterans Healthcare System
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26
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Hang S, Tiwari AFY, Ngan HYS, Yip YL, Cheung ALM, Tsao SW, Deng W. Extremely stringent activation of p16INK4a prevents immortalization of uterine cervical epithelial cells without human papillomavirus oncogene expression. Oncotarget 2016; 7:45656-45670. [PMID: 27344169 PMCID: PMC5216750 DOI: 10.18632/oncotarget.10120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 05/29/2016] [Indexed: 11/25/2022] Open
Abstract
Cervical epithelial cell immortalization with defined genetic factors without viral oncogenes has never been reported. Here we report that HPV-negative cervical epithelial cells failed to be immortalized by telomerase activation or the combination of p53 knockdown and telomerase activation. Under those conditions, p16INK4a expression was always elevated during the late stage of limited cell lifespan, suggesting that cervical epithelial cells possess an intrinsic property of uniquely stringent activation of p16INK4a, which may offer an explanation for the rarity of HPV-negative cervical cancer. Combining p16INK4a knockdown with telomerase activation resulted in efficient immortalization of HPV-negative cervical epithelial cells under ordinary culture conditions. Compared with the HPV16-E6E7-immortalized cell lines derived from the same primary cell sources, the novel HPV-negative immortalized cell lines had lower degrees of chromosomal instability, maintained more sensitive p53/p21 response to DNA damage, exhibited more stringent G2 checkpoint function, and were more resistant to replication-stress-induced genomic instability. The newly immortalized HPV-negative cervical epithelial cell lines were non-tumorigenic in nude mice. The cell lines can be used not only as much-needed HPV-negative non-malignant cell models but also as starting models that can be genetically manipulated in a stepwise fashion to investigate the roles of defined genetic alterations in the development of HPV-negative cervical cancer.
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Affiliation(s)
- Su Hang
- School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China.,College of Forensic Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shanxi Province, P.R. China
| | - Agnes F Y Tiwari
- School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China
| | - Hextan Y S Ngan
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong, SAR, China
| | - Yim-Ling Yip
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China
| | - Annie L M Cheung
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China
| | - Sai Wah Tsao
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China
| | - Wen Deng
- School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China
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27
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Solovyeva AI, Stefanova VN, Podgornaya OI, Demin SI. Karyotype features of trematode Himasthla elongata. Mol Cytogenet 2016; 9:34. [PMID: 27134655 PMCID: PMC4850635 DOI: 10.1186/s13039-016-0246-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/12/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Trematodes have a complex life cycle with animal host changes and alternation of parthenogenetic and hermaphrodite generations. The parthenogenetic generation of the worm (rediae) from the first intermediate host Littorina littorea was used for chromosome spreads production. Karyotype description of parasitic flatworm Himasthla elongata Mehlis, 1831 (Digenea: Himasthlidae) based on fluorochrome banding and 18S rDNA mapping. RESULTS Chromosome spreads were obtained from cercariae embryos and redial tissue suspensions with high pressure squash method.74.4 % of the analysed spreads contained 12 chromosome pairs (2n = 24). Chromosome classification was performed according to the morphometry and nomenclature published. H. elongata spread chromosomes had a rather bead-like structure. Ideograms of DAPI-banded chromosomes contained 130 individual bands. According to flow cytometry data, the H. elongata genome contains 1.25 pg of DNA, so one band contains, on average, 9.4 Mb of DNA. Image bank captures of individual high-resolution DAPI-banded chromosomes were provided. Differential DAPI- and CMA3-staining revealed the chromatin areas that differed in AT- or GC-content. Both dyes stained chromosomes all along but with varying intensities in different areas. FISH revealed that vast majority (95.0 %) of interphase nuclei contained one signal for 18S rDNA. This corresponded to the number of nucleoli per cell detected by observations in vivo. The rDNA signal was observed on one or two homologs of chromosome 10 in 72.2 % of analysed chromosome spreads, therefore chromosome 10 possessed the main rDNA cluster and minor ones on chromosomes 3 and 6, that corresponds with AgNOR results. CONCLUSIONS Himasthla elongata chromosomes variations presented as image bank. Differential chromosome staining with fluorochromes and FISH used for 18S rDNA mapping let us to conclude: (1) Himasthla elongata karyotype is 2n = 24; (2) chromosome number deviates from the previously studied echinostomatids (2n = 14-22); (3). Chromosome 10 possesses the main rDNA cluster with the minor ones existing on chromosomes 3 and 6.
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Affiliation(s)
| | | | - Olga I Podgornaya
- Institute of Cytology RAS, St. Petersburg, 194064 Russia ; Saint Petersburg State University, St. Petersburg, 199034 Russia ; Far Eastern Federal University, Vladivostok, 690922 Russia
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28
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Dayal JHS, Albergante L, Newman TJ, South AP. Quantitation of multiclonality in control and drug-treated tumour populations using high-throughput analysis of karyotypic heterogeneity. CONVERGENT SCIENCE PHYSICAL ONCOLOGY 2015. [DOI: 10.1088/2057-1739/1/2/025001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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29
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Ramakumar A, Subramanian U, Prasanna PGS. High-throughput sample processing and sample management; the functional evolution of classical cytogenetic assay towards automation. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 793:132-41. [PMID: 26520383 DOI: 10.1016/j.mrgentox.2015.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 07/23/2015] [Indexed: 10/23/2022]
Abstract
High-throughput individual diagnostic dose assessment is essential for medical management of radiation-exposed subjects after a mass casualty. Cytogenetic assays such as the Dicentric Chromosome Assay (DCA) are recognized as the gold standard by international regulatory authorities. DCA is a multi-step and multi-day bioassay. DCA, as described in the IAEA manual, can be used to assess dose up to 4-6 weeks post-exposure quite accurately but throughput is still a major issue and automation is very essential. The throughput is limited, both in terms of sample preparation as well as analysis of chromosome aberrations. Thus, there is a need to design and develop novel solutions that could utilize extensive laboratory automation for sample preparation, and bioinformatics approaches for chromosome-aberration analysis to overcome throughput issues. We have transitioned the bench-based cytogenetic DCA to a coherent process performing high-throughput automated biodosimetry for individual dose assessment ensuring quality control (QC) and quality assurance (QA) aspects in accordance with international harmonized protocols. A Laboratory Information Management System (LIMS) is designed, implemented and adapted to manage increased sample processing capacity, develop and maintain standard operating procedures (SOP) for robotic instruments, avoid data transcription errors during processing, and automate analysis of chromosome-aberrations using an image analysis platform. Our efforts described in this paper intend to bridge the current technological gaps and enhance the potential application of DCA for a dose-based stratification of subjects following a mass casualty. This paper describes one such potential integrated automated laboratory system and functional evolution of the classical DCA towards increasing critically needed throughput.
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Affiliation(s)
- Adarsh Ramakumar
- Scientific Research Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bldg. 42, Bethesda, MD 20889, USA.
| | - Uma Subramanian
- Scientific Research Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bldg. 42, Bethesda, MD 20889, USA
| | - Pataje G S Prasanna
- Scientific Research Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bldg. 42, Bethesda, MD 20889, USA
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30
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King C, Diaz HB, McNeely S, Barnard D, Dempsey J, Blosser W, Beckmann R, Barda D, Marshall MS. LY2606368 Causes Replication Catastrophe and Antitumor Effects through CHK1-Dependent Mechanisms. Mol Cancer Ther 2015; 14:2004-13. [PMID: 26141948 DOI: 10.1158/1535-7163.mct-14-1037] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 06/27/2015] [Indexed: 12/13/2022]
Abstract
CHK1 is a multifunctional protein kinase integral to both the cellular response to DNA damage and control of the number of active replication forks. CHK1 inhibitors are currently under investigation as chemopotentiating agents due to CHK1's role in establishing DNA damage checkpoints in the cell cycle. Here, we describe the characterization of a novel CHK1 inhibitor, LY2606368, which as a single agent causes double-stranded DNA breakage while simultaneously removing the protection of the DNA damage checkpoints. The action of LY2606368 is dependent upon inhibition of CHK1 and the corresponding increase in CDC25A activation of CDK2, which increases the number of replication forks while reducing their stability. Treatment of cells with LY2606368 results in the rapid appearance of TUNEL and pH2AX-positive double-stranded DNA breaks in the S-phase cell population. Loss of the CHK1-dependent DNA damage checkpoints permits cells with damaged DNA to proceed into early mitosis and die. The majority of treated mitotic nuclei consist of extensively fragmented chromosomes. Inhibition of apoptosis by the caspase inhibitor Z-VAD-FMK had no effect on chromosome fragmentation, indicating that LY2606368 causes replication catastrophe. Changes in the ratio of RPA2 to phosphorylated H2AX following LY2606368 treatment further support replication catastrophe as the mechanism of DNA damage. LY2606368 shows similar activity in xenograft tumor models, which results in significant tumor growth inhibition. LY2606368 is a potent representative of a novel class of drugs for the treatment of cancer that acts through replication catastrophe.
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Affiliation(s)
- Constance King
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - H Bruce Diaz
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Samuel McNeely
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Darlene Barnard
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Jack Dempsey
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Wayne Blosser
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Richard Beckmann
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - David Barda
- Chemistry Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana
| | - Mark S Marshall
- Oncology Discovery Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana.
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31
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Nopparat J, Zhang J, Lu JP, Chen YH, Zheng D, Neufer PD, Fan JM, Hong H, Boykin C, Lu Q. δ-Catenin, a Wnt/β-catenin modulator, reveals inducible mutagenesis promoting cancer cell survival adaptation and metabolic reprogramming. Oncogene 2015; 34:1542-52. [PMID: 24727894 PMCID: PMC4197123 DOI: 10.1038/onc.2014.89] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 01/16/2014] [Accepted: 02/17/2014] [Indexed: 02/06/2023]
Abstract
Mutations of Wnt/β-catenin signaling pathway has essential roles in development and cancer. Although β-catenin and adenomatous polyposis coli (APC) gene mutations are well established and are known to drive tumorigenesis, discoveries of mutations in other components of the pathway lagged, which hinders the understanding of cancer mechanisms. Here we report that δ-catenin (gene designation: CTNND2), a primarily neural member of the β-catenin superfamily that promotes canonical Wnt/β-catenin/LEF-1-mediated transcription, displays exonic mutations in human prostate cancer and promotes cancer cell survival adaptation and metabolic reprogramming. When overexpressed in cells derived from prostate tumor xenografts, δ-catenin gene invariably gives rise to mutations, leading to sequence disruptions predicting functional alterations. Ectopic δ-catenin gene integrating into host chromosomes is locus nonselective. δ-Catenin mutations promote tumor development in mouse prostate with probasin promoter (ARR2PB)-driven, prostate-specific expression of Myc oncogene, whereas mutant cells empower survival advantage upon overgrowth and glucose deprivation. Reprogramming energy utilization accompanies the downregulation of glucose transporter-1 and poly (ADP-ribose) polymerase cleavage while preserving tumor type 2 pyruvate kinase expression. δ-Catenin mutations increase β-catenin translocation to the nucleus and hypoxia-inducible factor 1α (HIF-1α) expression. Therefore, introducing δ-catenin mutations is an important milestone in prostate cancer metabolic adaptation by modulating β-catenin and HIF-1α signaling under glucose shortage to amplify its tumor-promoting potential.
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Affiliation(s)
- J Nopparat
- Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - J Zhang
- Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - J-P Lu
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Y-H Chen
- 1] Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC, USA [2] Leo Jenkins Cancer Center, The Brody School of Medicine, East Carolina University, Greenville, NC, USA [3] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - D Zheng
- 1] Department of Kinesiology, East Carolina University, Greenville, NC, USA [2] East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - P D Neufer
- 1] Department of Kinesiology, East Carolina University, Greenville, NC, USA [2] East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA [3] Department of Physiology, The Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - J M Fan
- Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - H Hong
- Department of Pathology and Laboratory Medicine, The Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - C Boykin
- Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Q Lu
- 1] Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC, USA [2] Leo Jenkins Cancer Center, The Brody School of Medicine, East Carolina University, Greenville, NC, USA [3] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
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32
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Lam DC, Luo SY, Deng W, Kwan JS, Rodriguez-Canales J, Cheung AL, Cheng GH, Lin CH, Wistuba II, Sham PC, Wan TS, Tsao SW. Oncogenic mutation profiling in new lung cancer and mesothelioma cell lines. Onco Targets Ther 2015; 8:195-209. [PMID: 25653542 PMCID: PMC4303463 DOI: 10.2147/ott.s71242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Background Thoracic tumor, especially lung cancer, ranks as the top cancer mortality in most parts of the world. Lung adenocarcinoma is the predominant subtype and there is increasing knowledge on therapeutic molecular targets, namely EGFR, ALK, KRAS, and ROS1, among lung cancers. Lung cancer cell lines established with known clinical characteristics and molecular profiling of oncogenic targets like ALK or KRAS could be useful tools for understanding the biology of known molecular targets as well as for drug testing and screening. Materials and methods Five new cancer cell lines were established from pleural fluid or biopsy tissues obtained from Chinese patients with primary lung adenocarcinomas or malignant pleural mesothelioma. They were characterized by immunohistochemistry, growth kinetics, tests for tumorigenicity, EGFR and KRAS gene mutations, ALK gene rearrangement and OncoSeq mutation profiling. Results These newly established lung adenocarcinoma and mesothelioma cell lines were maintained for over 100 passages and demonstrated morphological and immunohistochemical features as well as growth kinetics of tumor cell lines. One of these new cell lines bears EML4-ALK rearrangement variant 2, two lung cancer cell lines bear different KRAS mutations at codon 12, and known single nucleotide polymorphism variants were identified in these cell lines. Discussion Four new lung adenocarcinoma and one mesothelioma cell lines were established from patients with different clinical characteristics and oncogenic mutation profiles. These characterized cell lines and their mutation profiles will provide resources for exploration of lung cancer and mesothelioma biology with regard to the presence of known oncogenic mutations.
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Affiliation(s)
- David Cl Lam
- Department of Medicine, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Susan Y Luo
- Department of Medicine, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Wen Deng
- School of Nursing, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Johnny Sh Kwan
- Department of Psychiatry, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Jaime Rodriguez-Canales
- Department of Translational Molecular Pathology, MD Anderson Cancer Center, University of Texas at Houston, Houston, TX, USA
| | - Annie Lm Cheung
- Department of Anatomy, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Grace Hw Cheng
- Center for Genome Sciences, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Chi-Ho Lin
- Center for Genome Sciences, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Ignacio I Wistuba
- Department of Translational Molecular Pathology, MD Anderson Cancer Center, University of Texas at Houston, Houston, TX, USA
| | - Pak C Sham
- Center for Genome Sciences, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Thomas Sk Wan
- Department of Pathology, University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Sai-Wah Tsao
- Department of Anatomy, University of Hong Kong, Hong Kong SAR, People's Republic of China
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33
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Deng W, Zhou Y, Tiwari AFY, Su H, Yang J, Zhu D, Lau VMY, Hau PM, Yip YL, Cheung ALM, Guan XY, Tsao SW. p21/Cyclin E pathway modulates anticlastogenic function of Bmi-1 in cancer cells. Int J Cancer 2014; 136:1361-70. [PMID: 25131797 PMCID: PMC4312942 DOI: 10.1002/ijc.29114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 06/25/2014] [Accepted: 06/27/2014] [Indexed: 12/14/2022]
Abstract
Apart from regulating stem cell self-renewal, embryonic development and proliferation, Bmi-1 has been recently reported to be critical in the maintenance of genome integrity. In searching for novel mechanisms underlying the anticlastogenic function of Bmi-1, we observed, for the first time, that Bmi-1 positively regulates p21 expression. We extended the finding that Bmi-1 deficiency induced chromosome breaks in multiple cancer cell models. Interestingly, we further demonstrated that knockdown of cyclin E or ectopic overexpression of p21 rescued Bmi-1 deficiency-induced chromosome breaks. We therefore conclude that p21/cyclin E pathway is crucial in modulating the anticlastogenic function of Bmi-1. As it is well established that the overexpression of cyclin E potently induces genome instability and p21 suppresses the function of cyclin E, the novel and important implication from our findings is that Bmi-1 plays an important role in limiting genomic instability in cylin E-overexpressing cancer cells by positive regulation of p21.
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Affiliation(s)
- Wen Deng
- School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
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Experimental characterization of methanol-acetic acid fixative sessile drop dynamics in dry and humid air by video imaging and interference analysis. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2014.02.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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A Semi-Closed Device for Chromosome Spreading for Cytogenetic Analysis. MICROMACHINES 2014. [DOI: 10.3390/mi5020158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Kirov I, Divashuk M, Van Laere K, Soloviev A, Khrustaleva L. An easy "SteamDrop" method for high quality plant chromosome preparation. Mol Cytogenet 2014; 7:21. [PMID: 24602284 PMCID: PMC3995958 DOI: 10.1186/1755-8166-7-21] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Accepted: 02/26/2014] [Indexed: 12/01/2022] Open
Abstract
Background The chromosome preparation is a crucial step for obtaining satisfactory results in molecular cytogenetic researches. The preparation of plant chromosomes for molecular cytogenetic purposes remains a challenge for some species. In contrast to human chromosome preparation, the processes occurring during plant chromosome preparation and causing chromosome spreading are still poorly understood. Results We studied the dynamics of plant chromosome spreading after dropping cell suspension on slides. We showed that steam stimulates cytoplasm hydrolysis and rapid chromosome spreading and that chromosomes stretch during this chromosome spreading. Based on these observations, we developed a novel method, named “SteamDrop”, for the preparation of well-spread mitotic and pachytene chromosomes and successfully used it for 28 plant species with large and small chromosomes. We applied cell suspensions in ethanol instead of the commonly used ethanol/acetic acid fixative. Mitotic and meiotic chromosomes prepared via “SteamDrop” were used in fluorescent in situ hybridization (FISH) experiments with repetitive and unique DNA probes. Long storage of cell suspensions in ethanol did not impair the quality of chromosome preparations. Conclusion The SteamDrop procedure provides a robust and routine method for high quality plant chromosome preparations. The method can be applied for metaphase as well as pachytene chromosome preparation in wide range of species. The chromosomes prepared by SteamDrop are well suitable for repetitive and unique DNA visualization.
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Affiliation(s)
| | | | | | | | - Ludmila Khrustaleva
- Department of Genetics and Biotechnology, Russian State Agrarian University-MTAA, Timiryazevskay str, 49, 127550 Moscow, Russia.
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Cornélio DA, Tavares JCM, Pimentel TVCDA, Cavalcanti GB, Batistuzzo de Medeiros SR. Cytokinesis-block micronucleus assay adapted for analyzing genomic instability of human mesenchymal stem cells. Stem Cells Dev 2014; 23:823-38. [PMID: 24328548 DOI: 10.1089/scd.2013.0383] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Human mesenchymal stem cells (hMSCs) are multipotent cells used in cell therapy research. One of the problems involving hMSCs is the possibility of genetic instability during in vitro expansion required to obtain a suitable number of cells for clinical applications. The cytokinesis-block micronucleus (CBMN) assay measures genetic instability by analyzing the presence of micronucleus (MN), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs) in binucleated cells. The present study describes modifications in the CBMN assay methodology to analyze genetic instability in hMSCs isolated from the umbilical vein and in vitro expanded. The best protocol to achieve binucleated hMSCs with preserved cytoplasm was as follows: cytochalasin B concentration (4.0 μg/mL), use of hypotonic treatment (3 min), and the fixative solution (9 methanol:1 acetic acid). These adaptations were reproduced in three hMSC primary cell cultures and also in XP4PA and A549 cell lines. The frequency of hMSCs treated with mitomycin-C presenting MN was lower than that with other nuclear alterations, indicating that the hMSCs contain mechanisms to avoid a high level of chromosomal breaks. However, a high frequency of cells with NPBs was detected and spontaneous anaphase bridges under normal hMSC in vitro culture were observed. Considering that anaphase bridges are characteristic alterations in tumor cells, the CBMN assay is indicated as an important tool associated with other genetic analyses in order to ensure the safe clinical use of hMSCs in cell therapy.
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Affiliation(s)
- Déborah Afonso Cornélio
- 1 Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte , Natal, Brazil
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Nag A, Savova V, Fung HL, Miron A, Yuan GC, Zhang K, Gimelbrant AA. Chromatin signature of widespread monoallelic expression. eLife 2013; 2:e01256. [PMID: 24381246 PMCID: PMC3873816 DOI: 10.7554/elife.01256] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In mammals, numerous autosomal genes are subject to mitotically stable monoallelic expression (MAE), including genes that play critical roles in a variety of human diseases. Due to challenges posed by the clonal nature of MAE, very little is known about its regulation; in particular, no molecular features have been specifically linked to MAE. In this study, we report an approach that distinguishes MAE genes in human cells with great accuracy: a chromatin signature consisting of chromatin marks associated with active transcription (H3K36me3) and silencing (H3K27me3) simultaneously occurring in the gene body. The MAE signature is present in ∼20% of ubiquitously expressed genes and over 30% of tissue-specific genes across cell types. Notably, it is enriched among key developmental genes that have bivalent chromatin structure in pluripotent cells. Our results open a new approach to the study of MAE that is independent of polymorphisms, and suggest that MAE is linked to cell differentiation. DOI:http://dx.doi.org/10.7554/eLife.01256.001 Understanding how genes are activated and silenced is one of the central challenges in modern biology. These processes underpin the development of a fertilized egg into a complex organism, and they can also lead to life-threatening diseases when they go wrong. There are two copies of each gene in a human cell, a maternal copy and a paternal copy, and it is thought that both copies are usually regulated together. However, there are exceptions to this rule: for certain genes only the maternal copy is expressed as a protein in some cells, whereas the paternal copy is expressed in other cells. This form of gene regulation, which is called monoallelic expression, can result in neighboring cells heading down very different paths. In extreme cases, depending on the differences between the two copies of the gene, cells that express one copy may function normally, while cells where the other copy is activated will start forming tumors. However, despite these potentially grave consequences, and early results which suggested that monoallelic expression affected a large number of human and mouse genes, it has proved to be a major technical challenge to identify these genes in most cell types. Now, Nag, Savova et al. have discovered a molecular signature that can be used to detect monoallelic expression. The signature was found in chromatin, the densely packed structure formed by DNA and proteins inside the cell nucleus. Nag, Savova et al. discovered that the genes that are subject to monoallelic expression are bound with proteins that are modified in two contrasting ways. One modification, which is usually a sign of gene silencing, is prevalent on the inactive copy of the gene, and the other, which often marks active genes, is chiefly present on the active copy. Nag, Savova et al. report that these modifications are found in different sets of genes in different cell types, indicating distinct genome-wide patterns of monoallelic expression. The chromatin signature approach lets them estimate the fraction of human genes that are subject to monoallelic expression. This number is surprisingly high: about 20% of commonly expressed genes and more than one-third of tissue-specific genes. In a particularly intriguing finding, almost all bivalent genes—a subset of genes that are involved in determining the fate of cell during development—are estimated to become monoallelic when they are activated. In addition to these unexpected findings, the chromatin signature approach opens the door to exploring monoallelic expression as a form of gene regulation in all types of cells and, ultimately, to understanding how it is involved in both normal development and in disease. DOI:http://dx.doi.org/10.7554/eLife.01256.002
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Affiliation(s)
- Anwesha Nag
- Department of Cancer Biology and Center for Cancer Systems Biology, Dana-Farber Cancer Institute, Boston, United States
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Qu YY, Xing LY, Hughes ED, Saunders TL. Chromosome Dropper Tool: Effect of Slide Angles on Chromosome Spread Quality for Murine Embryonic Stem Cells. J Histotechnol 2013. [DOI: 10.1179/his.2008.31.2.75] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Pericentromeric regions are refractory to prompt repair after replication stress-induced breakage in HPV16 E6E7-expressing epithelial cells. PLoS One 2012; 7:e48576. [PMID: 23119062 PMCID: PMC3485353 DOI: 10.1371/journal.pone.0048576] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 09/26/2012] [Indexed: 12/12/2022] Open
Abstract
Chromosomal instability is the major form of genomic instability in cancer cells. Amongst various forms of chromosomal instability, pericentromeric or centromeric instability remains particularly poorly understood. In the present study, we found that pericentromeric instability, evidenced by dynamic formation of pericentromeric or centromeric rearrangements, breaks, deletions or iso-chromosomes, was a general phenomenon in human cells immortalized by expression of human papillomavirus type 16 E6 and E7 (HPV16 E6E7). In particular, for the first time, we surprisingly found a dramatic increase in the proportion of pericentromeric chromosomal aberrations relative to total aberrations in HPV16 E6E7-expressing cells 72 h after release from aphidicolin (APH)-induced replication stress, with pericentromeric chromosomal aberrations becoming the predominant type of structural aberrations (∼70% of total aberrations). In contrast, pericentromeric aberrations accounted for only about 20% of total aberrations in cells at the end of APH treatment. This increase in relative proportion of pericentromeric aberrations after release from APH treatment revealed that pericentromeric breaks induced by replication stress are refractory to prompt repair in HPV16 E6E7-expressing epithelial cells. Telomerase-immortalized epithelial cells without HPV16 E6E7 expression did not exhibit such preferential pericentromeric instability after release from APH treatment. Cancer development is often associated with replication stress. Since HPV16 E6 and E7 inactivate p53 and Rb, and p53 and Rb pathway defects are common in cancer, our finding that pericentromeric regions are refractory to prompt repair after replication stress-induced breakage in HPV16 E6E7-expressing cells may shed light on mechanism of general pericentromeric instability in cancer.
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Deng W, Pang PS, Tsang CM, Hau PM, Yip YL, Cheung ALM, Tsao SW. Epstein-Barr virus-encoded latent membrane protein 1 impairs G2 checkpoint in human nasopharyngeal epithelial cells through defective Chk1 activation. PLoS One 2012; 7:e39095. [PMID: 22761726 PMCID: PMC3382577 DOI: 10.1371/journal.pone.0039095] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 05/18/2012] [Indexed: 11/19/2022] Open
Abstract
Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia, particularly in southern regions of China. EBV infection is closely associated with NPC and has long been postulated to play an etiological role in the development of NPC. However, the role of EBV in malignant transformation of nasopharyngeal epithelial cells remains enigmatic. The current hypothesis of NPC development is that premalignant nasopharyngeal epithelial cells harboring genetic alterations support EBV infection and expression of EBV genes induces further genomic instability to facilitate the development of NPC. The latent membrane protein 1 (LMP1) is a well-documented EBV-encoded oncogene. The involvement of LMP1 in human epithelial malignancies has been implicated, but the mechanisms of oncogenic actions of LMP1, particularly in nasopharyngeal cells, are unclear. Here we observed that LMP1 expression in nasopharyngeal epithelial cells impaired G2 checkpoint, leading to formation of unrepaired chromatid breaks in metaphases after γ-ray irradiation. We further found that defective Chk1 activation was involved in the induction of G2 checkpoint defect in LMP1-expressing nasopharyngeal epithelial cells. Impairment of G2 checkpoint could result in loss of the acentrically broken chromatids and propagation of broken centric chromatids in daughter cells exiting mitosis, which facilitates chromosome instability. Our findings suggest that LMP1 expression facilitates genomic instability in cells under genotoxic stress. Elucidation of the mechanisms involved in LMP1-induced genomic instability in nasopharyngeal epithelial cells will shed lights on the understanding of role of EBV infection in NPC development.
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Affiliation(s)
- Wen Deng
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Pei Shin Pang
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Chi Man Tsang
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Pok Man Hau
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Yim Ling Yip
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Annie L. M. Cheung
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Sai Wah Tsao
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- * E-mail:
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42
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Advanced microtechnologies for detection of chromosome abnormalities by fluorescent in situ hybridization. Biomed Microdevices 2012; 14:453-60. [DOI: 10.1007/s10544-011-9622-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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43
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Chen M, Huang JD, Deng HK, Dong S, Deng W, Tsang SL, Huen MSY, Chen L, Zan T, Zhu GX, Guan XY. Overexpression of eIF-5A2 in mice causes accelerated organismal aging by increasing chromosome instability. BMC Cancer 2011; 11:199. [PMID: 21612665 PMCID: PMC3118894 DOI: 10.1186/1471-2407-11-199] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 05/26/2011] [Indexed: 11/24/2022] Open
Abstract
Background Amplification of 3q26 is one of the most frequent genetic alterations in many human malignancies. Recently, we isolated a novel oncogene eIF-5A2 within the 3q26 region. Functional study has demonstrated the oncogenic role of eIF-5A2 in the initiation and progression of human cancers. In the present study, we aim to investigate the physiological and pathological effect of eIF-5A2 in an eIF-5A2 transgenic mouse model. Methods An eIF-5A2 transgenic mouse model was generated using human eIF-5A2 cDNA. The eIF-5A2 transgenic mice were characterized by histological and immunohistochemistry analyses. The aging phenotypes were further characterized by wound healing, bone X-ray imaging and calcification analysis. Mouse embryo fibroblasts (MEF) were isolated to further investigate molecular mechanism of eIF-5A2 in aging. Results Instead of resulting in spontaneous tumor formation, overexpression of eIF-5A2 accelerated the aging process in adult transgenic mice. This included decreased growth rate and body weight, shortened life span, kyphosis, osteoporosis, delay of wound healing and ossification. Investigation of the correlation between cellular senescence and aging showed that cellular senescence is not required for the aging phenotypes in eIF-5A2 mice. Interestingly, we found that activation of eIF-5A2 repressed p19 level and therefore destabilized p53 in transgenic mouse embryo fibroblast (MEF) cells. This subsequently allowed for the accumulation of chromosomal instability, such as errors in cell dividing during metaphase and anaphase. Additionally, a significantly increase in number of aneuploidy cells (p < 0.05) resulted from an increase in the incidences of misaligned and lagging chromosomal materials, anaphase bridges, and micronuclei in the transgenic mice. Conclusion These observations suggest that eIF-5A2 mouse models could accelerate organismal aging by increasing chromosome instability.
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Affiliation(s)
- Muhan Chen
- Department of Clinical Oncology, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, China
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Deng W, Tsao SW, Mak GWY, Tsang CM, Ching YP, Guan XY, Huen MSY, Cheung ALM. Impact of G₂ checkpoint defect on centromeric instability. Oncogene 2010; 30:1281-9. [PMID: 21057540 DOI: 10.1038/onc.2010.508] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Centromeric instability is characterized by dynamic formation of centromeric breaks, deletions, isochromosomes and translocations, which are commonly observed in cancer. So far, however, the mechanisms of centromeric instability in cancer cells are still poorly understood. In this study, we tested the hypothesis that G(2) checkpoint defect promotes centromeric instability. Our observations from multiple approaches consistently support this hypothesis. We found that overexpression of cyclin B1, one of the pivotal genes driving G(2) to M phase transition, impaired G(2) checkpoint and promoted the formation of centromeric aberrations in telomerase-immortalized cell lines. Conversely, centromeric instability in cancer cells was ameliorated through reinforcement of G(2) checkpoint by cyclin B1 knockdown. Remarkably, treatment with KU55933 for only 2.5 h, which abrogated G(2) checkpoint, was sufficient to produce centromeric aberrations. Moreover, centromeric aberrations constituted the major form of structural abnormalities in G(2) checkpoint-defective ataxia telangiectasia cells. Statistical analysis showed that the frequencies of centromeric aberrations in G(2) checkpoint-defective cells were always significantly overrepresented compared with random assumption. As there are multiple pathways leading to G(2) checkpoint defect, our finding offers a broad explanation for the common occurrence of centromeric aberrations in cancer cells.
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Affiliation(s)
- W Deng
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China
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Metaphase FISH on a chip: miniaturized microfluidic device for fluorescence in situ hybridization. SENSORS 2010; 10:9831-46. [PMID: 22163442 PMCID: PMC3231008 DOI: 10.3390/s101109831] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 09/23/2010] [Accepted: 10/15/2010] [Indexed: 12/29/2022]
Abstract
Fluorescence in situ Hybridization (FISH) is a major cytogenetic technique for clinical genetic diagnosis of both inherited and acquired chromosomal abnormalities. Although FISH techniques have evolved and are often used together with other cytogenetic methods like CGH, PRINS and PNA-FISH, the process continues to be a manual, labour intensive, expensive and time consuming technique, often taking over 3 5 days, even in dedicated labs. We have developed a novel microFISH device to perform metaphase FISH on a chip which overcomes many shortcomings of the current laboratory protocols. This work also introduces a novel splashing device for preparing metaphase spreads on a microscope glass slide, followed by a rapid adhesive tape-based bonding protocol leading to rapid fabrication of the microFISH device. The microFISH device allows for an optimized metaphase FISH protocol on a chip with over a 20-fold reduction in the reagent volume. This is the first demonstration of metaphase FISH on a microfluidic device and offers a possibility of automation and significant cost reduction of many routine diagnostic tests of genetic anomalies.
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Tsang CM, Zhang G, Seto E, Takada K, Deng W, Yip YL, Man C, Hau PM, Chen H, Cao Y, Lo KW, Middeldorp JM, Cheung ALM, Tsao SW. Epstein-Barr virus infection in immortalized nasopharyngeal epithelial cells: regulation of infection and phenotypic characterization. Int J Cancer 2010; 127:1570-83. [PMID: 20091869 DOI: 10.1002/ijc.25173] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Epstein-Barr virus (EBV) infection has been postulated to be an early event involved in the pathogenesis of nasopharyngeal carcinomas (NPC). The lack of representative premalignant nasopharyngeal epithelial cell system for EBV infection has hampered research investigation into the regulation and involvement of EBV infection in NPC pathogenesis. We have compared the efficiency of EBV infection in nasopharyngeal epithelial cells with different biological properties including immortalized, primary and cancerous nasopharyngeal epithelial cells. EBV infection could be achieved in all the nasopharyngeal epithelial cells examined with variable infection rate. TGF-beta effectively enhanced EBV infection into nasopharyngeal epithelial cells both in the immortalized and primary nasopharyngeal epithelial cells. Stable infection of EBV was achieved in a telomerase-immortalized nasopharyngeal epithelial cell line, NP460hTert. The expression pattern of EBV-encoded genes and biological properties of this EBV infected cell line on long-term propagation were monitored. The EBV-infected nasopharyngeal epithelial cells acquired anchorage-independent growth and exhibited invasive growth properties on prolonged propagation. A distinguished feature of this EBV-infected nasopharyngeal epithelial cell model was its enhanced ability to survive under growth factor and nutrient starvation. This was evidenced by the suppressed activation of apoptotic markers and sustained activation of pAkt of EBV-infected cells compared to control cells under nutrient starvation. Examination of cytokine profiles of EBV-infected NP460hTert cells to nutrient and growth factor deprivation revealed upregulation of expression of MCP-1 and GRO-alpha. The establishment of a stable EBV infection model of premalignant nasopharyngeal epithelial cells will facilitate research investigation into the pathogenic role of EBV in NPC development.
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Affiliation(s)
- Chi Man Tsang
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
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Yip YL, Tsang CM, Deng W, Cheung PY, Jin Y, Cheung ALM, Lung ML, Tsao SW. Expression of Epstein-Barr virus-encoded LMP1 and hTERT extends the life span and immortalizes primary cultures of nasopharyngeal epithelial cells. J Med Virol 2010; 82:1711-23. [DOI: 10.1002/jmv.21875] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Zaidi SK, Medina RF, Pockwinse SM, Bakshi R, Kota KP, Ali SA, Young DW, Nickerson JA, Javed A, Montecino M, van Wijnen AJ, Lian JB, Stein JL, Stein GS. Subnuclear localization and intranuclear trafficking of transcription factors. Methods Mol Biol 2010; 647:77-93. [PMID: 20694661 DOI: 10.1007/978-1-60761-738-9_4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Nuclear microenvironments are architecturally organized subnuclear sites where the regulatory machinery for gene expression, replication, and repair resides. This compartmentalization is necessary to attain required stoichiometry for organization and assembly of regulatory complexes for combinatorial control. Combined and methodical application of molecular, cellular, biochemical, and in vivo genetic approaches is required to fully understand complexities of biological control. Here we provide methodologies to characterize nuclear organization of regulatory machinery by in situ immunofluorescence microscopy.
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Affiliation(s)
- Sayyed K Zaidi
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA, USA
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Liang Y, Zhong Z, Huang Y, Deng W, Cao J, Tsao G, Liu Q, Pei D, Kang T, Zeng YX. Stem-like cancer cells are inducible by increasing genomic instability in cancer cells. J Biol Chem 2009; 285:4931-40. [PMID: 20007324 PMCID: PMC2836097 DOI: 10.1074/jbc.m109.048397] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The existence of cancer stem cells (CSCs) or stem-like cancer cells (SLCCs) is regarded as the cause of tumor formation and recurrence. However, the origin of such cells remains controversial with two competing hypotheses: CSCs are either transformed from tissue adult stem cells or dedifferentiated from transformed progenitor cells. Compelling evidence has determined the chromosomal aneuploidy to be one of the hallmarks of cancer cells, indicating genome instability plays an important role in tumorigenesis, for which CSCs are believed to be the initiator. To gain direct evidence that genomic instability is involved in the induction of SLCCs, we utilized multiple approaches to enhance genomic instability and monitored the percentage of SLCC in cultured cancer cells. Using side population (SP) cells as a marker for SLCC in human nasopharyngeal carcinoma (NPC) and CD133 for human neuroblastoma cells, we found that DNA damage inducers, UV and mitomycin C were capable of increasing SP cells in NPC CNE-2 and neuroblastoma SKN-SH cells. Likewise, either overexpression of a key regulator of cell cycle, Mad2, or knock down of Aurora B, an important kinase in mitosis, or Cdh1, a key E3 ligase in cell cycle, resulted in a significant increase of SP cells in CNE-2. More interestingly, enrichment of SP cells was observed in recurrent tumor tissues as compared with the primary tumor in the same NPC patients. Our study thus suggested that, beside transformation of tissue stem cells leading to CSC generation, genomic instability could be another potential mechanism resulting in SLCC formation, especially at tumor recurrence stage.
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Affiliation(s)
- Yi Liang
- State Key Laboratory of Oncology in Southern China, Guangzhou, China
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Nicholson JM, Duesberg P. On the karyotypic origin and evolution of cancer cells. ACTA ACUST UNITED AC 2009; 194:96-110. [PMID: 19781442 DOI: 10.1016/j.cancergencyto.2009.06.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Revised: 06/10/2009] [Accepted: 06/11/2009] [Indexed: 12/26/2022]
Abstract
Cancers have clonal, aneuploid karyotypes that evolve ever more malignant phenotypes spontaneously. Because these facts are hard to explain by conventional mutation theory, we propose here a karyotypic cancer theory. According to this theory, carcinogens initiate carcinogenesis by inducing random aneuploidy. Aneuploidy then catalyzes karyotypic evolutions, because it destabilizes the karyotype by unbalancing teams of proteins that segregate, synthesize, and repair chromosomes. Sporadically, such evolutions generate new cancer-causing karyotypes, which are stabilized within narrow limits against the inherent instability of aneuploidy by selection for oncogenic function. Here we have tested this theory prospectively by analyzing the karyotypes of distinct tumorigenic clones, which arose from mass cultures of human cells within a few months after transfection with artificially activated oncogenes. All clones from the same parental cells had individual, "near-clonal" karyotypes and phenotypes, although the parental oncogenes were identical. The karyotypes of distinct tumors formed by a given clone in immunodeficient mice were variants of those of the input clones. The karyotypes of tumorigenic clones also evolved on passages in vitro, in which they acquired either enhanced tumorigenicity spontaneously or resistance against methotrexate upon selection. We conclude that activated oncogenes initiate carcinogenesis indirectly by inducing random aneuploidy, much like conventional carcinogens, but more effectively because the oncogenes are integrated into the genome. Since aneuploidy destabilizes the karyotype, such cells evolve new, cancer-specific karyotypes spontaneously, much like new species. Because individual karyotypes of tumorigenic clones correlate and coevolve with individual phenotypes, we conclude that specific karyotypes as a whole are the genomes of cancer cells. Owing to the flexibility of their aneuploid karyotypes, cancers evolve at rates that are roughly proportional to their degrees of aneuploidy. In sum, genomes consisting of individual and flexible karyotypes explain the characteristic individuality, stability, and flexibility of cancers.
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Affiliation(s)
- Joshua M Nicholson
- Department of Molecular and Cell Biology, Donner Laboratory, University of California Berkeley, Berkeley, CA 94720, USA
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