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Sun H, Chen G, Guo B, Lv S, Yuan G. Potential clinical treatment prospects behind the molecular mechanism of alternative lengthening of telomeres (ALT). J Cancer 2023; 14:417-433. [PMID: 36860927 PMCID: PMC9969575 DOI: 10.7150/jca.80097] [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: 10/22/2022] [Accepted: 12/25/2022] [Indexed: 02/04/2023] Open
Abstract
Normal somatic cells inevitably experience replicative stress and senescence during proliferation. Somatic cell carcinogenesis can be prevented in part by limiting the reproduction of damaged or old cells and removing them from the cell cycle [1, 2]. However, Cancer cells must overcome the issues of replication pressure and senescence as well as preserve telomere length in order to achieve immortality, in contrast to normal somatic cells [1, 2]. Although telomerase accounts for the bulk of telomere lengthening methods in human cancer cells, there is a non-negligible portion of telomere lengthening pathways that depend on alternative lengthening of telomeres (ALT) [3]. For the selection of novel possible therapeutic targets for ALT-related disorders, a thorough understanding of the molecular biology of these diseases is crucial [4]. The roles of ALT, typical ALT tumor cell traits, the pathophysiology and molecular mechanisms of ALT tumor disorders, such as adrenocortical carcinoma (ACC), are all summarized in this work. Additionally, this research compiles as many of its hypothetically viable but unproven treatment targets as it can (ALT-associated PML bodies (APB), etc.). This review is intended to contribute as much as possible to the development of research, while also trying to provide a partial information for prospective investigations on ALT pathways and associated diseases.
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Affiliation(s)
- Haolu Sun
- Department of Pathophysiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230011, China
| | - Guijuan Chen
- School of Environment and Chemical Engineering, Anhui Vocational and Technical College, Hefei, 230011, China
| | - Baochang Guo
- Rehabilitation Department of Traditional Chinese Medicine, 969 Hospital of the Joint Support Force of the Chinese People's Liberation Army, Hohhot, 010000, China
| | - Shushu Lv
- Department of Pathology, The First Affiliated Hospital of Huzhou University, Huzhou 313000, China
| | - Guojun Yuan
- School of Environment and Chemical Engineering, Anhui Vocational and Technical College, Hefei, 230011, China
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2
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Quiroga-Artigas G, de Jong D, Schnitzler CE. GNL3 is an evolutionarily conserved stem cell gene influencing cell proliferation, animal growth and regeneration in the hydrozoan Hydractinia. Open Biol 2022; 12:220120. [PMID: 36069077 PMCID: PMC9449814 DOI: 10.1098/rsob.220120] [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] [Indexed: 11/12/2022] Open
Abstract
Nucleostemin (NS) is a vertebrate gene preferentially expressed in stem and cancer cells, which acts to regulate cell cycle progression, genome stability and ribosome biogenesis. NS and its paralogous gene, GNL3-like (GNL3L), arose in the vertebrate clade after a duplication event from their orthologous gene, G protein Nucleolar 3 (GNL3). Research on invertebrate GNL3, however, has been limited. To gain a greater understanding of the evolution and functions of the GNL3 gene, we have performed studies in the hydrozoan cnidarian Hydractinia symbiolongicarpus, a colonial hydroid that continuously generates pluripotent stem cells throughout its life cycle and presents impressive regenerative abilities. We show that Hydractinia GNL3 is expressed in stem and germline cells. The knockdown of GNL3 reduces the number of mitotic and S-phase cells in Hydractinia larvae of different ages. Genome editing of Hydractinia GNL3 via CRISPR/Cas9 resulted in colonies with reduced growth rates, polyps with impaired regeneration capabilities, gonadal morphological defects, and low sperm motility. Collectively, our study shows that GNL3 is an evolutionarily conserved stem cell and germline gene involved in cell proliferation, animal growth, regeneration and sexual reproduction in Hydractinia, and sheds new light into the evolution of GNL3 and of stem cell systems.
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Affiliation(s)
- Gonzalo Quiroga-Artigas
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA
| | - Danielle de Jong
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA
| | - Christine E Schnitzler
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA.,Department of Biology, University of Florida, Gainesville, FL, USA
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3
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Cela I, Cufaro MC, Fucito M, Pieragostino D, Lanuti P, Sallese M, Del Boccio P, Di Matteo A, Allocati N, De Laurenzi V, Federici L. Proteomic Investigation of the Role of Nucleostemin in Nucleophosmin-Mutated OCI-AML 3 Cell Line. Int J Mol Sci 2022; 23:ijms23147655. [PMID: 35886999 PMCID: PMC9317519 DOI: 10.3390/ijms23147655] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/07/2022] [Accepted: 07/09/2022] [Indexed: 02/06/2023] Open
Abstract
Nucleostemin (NS; a product of the GNL3 gene) is a nucleolar–nucleoplasm shuttling GTPase whose levels are high in stem cells and rapidly decrease upon differentiation. NS levels are also high in several solid and hematological neoplasms, including acute myeloid leukaemia (AML). While a role in telomere maintenance, response to stress stimuli and favoring DNA repair has been proposed in solid cancers, little or no information is available as to the role of nucleostemin in AML. Here, we investigate this issue via a proteomics approach. We use as a model system the OCI-AML 3 cell line harboring a heterozygous mutation at the NPM1 gene, which is the most frequent driver mutation in AML (approximately 30% of total AML cases). We show that NS is highly expressed in this cell line, and, contrary to what has previously been shown in other cancers, that its presence is dispensable for cell growth and viability. However, proteomics analysis of the OCI-AML 3 cell line before and after nucleostemin (NS) silencing showed several effects on different biological functions, as highlighted by ingenuity pathway analysis (IPA). In particular, we report an effect of down-regulating DNA repair through homologous recombination, and we confirmed a higher DNA damage rate in OCI-AML 3 cells when NS is depleted, which considerably increases upon stress induced by the topoisomerase II inhibitor etoposide. The data used are available via ProteomeXchange with the identifier PXD034012.
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Affiliation(s)
- Ilaria Cela
- Department of Innovative Technologies in Medicine & Dentistry, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (I.C.); (M.F.); (D.P.); (M.S.); (N.A.); (V.D.L.)
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
| | - Maria Concetta Cufaro
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
- Department of Pharmacy, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy
| | - Maurine Fucito
- Department of Innovative Technologies in Medicine & Dentistry, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (I.C.); (M.F.); (D.P.); (M.S.); (N.A.); (V.D.L.)
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
| | - Damiana Pieragostino
- Department of Innovative Technologies in Medicine & Dentistry, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (I.C.); (M.F.); (D.P.); (M.S.); (N.A.); (V.D.L.)
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
| | - Paola Lanuti
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
- Department of Medicine and Aging Science, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy
| | - Michele Sallese
- Department of Innovative Technologies in Medicine & Dentistry, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (I.C.); (M.F.); (D.P.); (M.S.); (N.A.); (V.D.L.)
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
| | - Piero Del Boccio
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
- Department of Pharmacy, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy
| | - Adele Di Matteo
- Institute of Molecular Biology and Pathology, National Research Council of Italy, P.le Aldo Moro 5, 00185 Rome, Italy;
| | - Nerino Allocati
- Department of Innovative Technologies in Medicine & Dentistry, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (I.C.); (M.F.); (D.P.); (M.S.); (N.A.); (V.D.L.)
| | - Vincenzo De Laurenzi
- Department of Innovative Technologies in Medicine & Dentistry, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (I.C.); (M.F.); (D.P.); (M.S.); (N.A.); (V.D.L.)
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
| | - Luca Federici
- Department of Innovative Technologies in Medicine & Dentistry, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (I.C.); (M.F.); (D.P.); (M.S.); (N.A.); (V.D.L.)
- Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (M.C.C.); (P.L.); (P.D.B.)
- Correspondence:
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Hornofova T, Pokorna B, Hubackova SS, Uvizl A, Kosla J, Bartek J, Hodny Z, Vasicova P. Phospho-SIM and exon8b of PML protein regulate formation of doxorubicin-induced rDNA-PML compartment. DNA Repair (Amst) 2022; 114:103319. [DOI: 10.1016/j.dnarep.2022.103319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 02/25/2022] [Accepted: 03/10/2022] [Indexed: 12/18/2022]
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Uggè M, Simoni M, Fracassi C, Bernardi R. PML isoforms: a molecular basis for PML pleiotropic functions. Trends Biochem Sci 2022; 47:609-619. [DOI: 10.1016/j.tibs.2022.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 10/19/2022]
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Identification of Key Proteins from the Alternative Lengthening of Telomeres-Associated Promyelocytic Leukemia Nuclear Bodies Pathway. BIOLOGY 2022; 11:biology11020185. [PMID: 35205052 PMCID: PMC8868596 DOI: 10.3390/biology11020185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 12/26/2022]
Abstract
Simple Summary The alternative lengthening of telomeres is a telomere maintenance mechanism used by some cancer types to elongate their telomeres without the aid of telomerase. This mechanism contributes to the proliferation and immortality of cancer cells. One of the hallmarks of this mechanism is the interaction with promyelocytic leukemia nuclear bodies, which are suspected to be the key places where telomere extension occurs. Despite the discovery of some mechanisms, elements, key genes, and proteins from the pathway, the alternative lengthening of telomeres mechanism is still poorly understood, and it is highly associated with a poor prognosis. In this study, we combined multiomics approaches with genomic, transcriptomic, and proteomic analyses of 71 genes/proteins related to promyelocytic leukemia nuclear bodies in more than 10,000 cancer samples from The Cancer Genome Atlas Consortium. As a result, 13 key proteins were proposed as candidates for future experimental studies that will validate these proteins as therapeutic markers, which will improve the understanding and treatment of these type of cancers. Abstract Alternative lengthening of telomeres-associated promyelocytic leukemia nuclear bodies (APBs) are a hallmark of telomere maintenance. In the last few years, APBs have been described as the main place where telomeric extension occurs in ALT-positive cancer cell lines. A different set of proteins have been associated with APBs function, however, the molecular mechanisms behind their assembly, colocalization, and clustering of telomeres, among others, remain unclear. To improve the understanding of APBs in the ALT pathway, we integrated multiomics analyses to evaluate genomic, transcriptomic and proteomic alterations, and functional interactions of 71 APBs-related genes/proteins in 32 Pan-Cancer Atlas studies from The Cancer Genome Atlas Consortium (TCGA). As a result, we identified 13 key proteins which showed distinctive mutations, interactions, and functional enrichment patterns across all the cancer types and proposed this set of proteins as candidates for future ex vivo and in vivo analyses that will validate these proteins to improve the understanding of the ALT pathway, fill the current research gap about APBs function and their role in ALT, and be considered as potential therapeutic targets for the diagnosis and treatment of ALT-positive cancers in the future.
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Mobility of Nucleostemin in Live Cells Is Specifically Related to Transcription Inhibition by Actinomycin D and GTP-Binding Motif. Int J Mol Sci 2021; 22:ijms22158293. [PMID: 34361059 PMCID: PMC8347349 DOI: 10.3390/ijms22158293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 07/24/2021] [Accepted: 07/29/2021] [Indexed: 12/04/2022] Open
Abstract
In vertebrates, nucleostemin (NS) is an important marker of proliferation in several types of stem and cancer cells, and it can also interact with the tumor-suppressing transcription factor p53. In the present study, the intra-nuclear diffusional dynamics of native NS tagged with GFP and two GFP-tagged NS mutants with deleted guanosine triphosphate (GTP)-binding domains were analyzed by fluorescence correlation spectroscopy. Free and slow binding diffusion coefficients were evaluated, either under normal culture conditions or under treatment with specific cellular proliferation inhibitors actinomycin D (ActD), 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), or trichostatin A (TSA). When treated with ActD, the fractional ratio of the slow diffusion was significantly decreased in the nucleoplasm. The decrease was proportional to ActD treatment duration. In contrast, DRB or TSA treatment did not affect NS diffusion. Interestingly, it was also found that the rate of diffusion of two NS mutants increased significantly even under normal conditions. These results suggest that the mobility of NS in the nucleoplasm is related to the initiation of DNA or RNA replication, and that the GTP-binding motif is also related to the large change of mobility.
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8
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Fonin AV, Silonov SA, Shpironok OG, Antifeeva IA, Petukhov AV, Romanovich AE, Kuznetsova IM, Uversky VN, Turoverov KK. The Role of Non-Specific Interactions in Canonical and ALT-Associated PML-Bodies Formation and Dynamics. Int J Mol Sci 2021; 22:ijms22115821. [PMID: 34072343 PMCID: PMC8198325 DOI: 10.3390/ijms22115821] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 04/30/2021] [Accepted: 05/22/2021] [Indexed: 12/19/2022] Open
Abstract
In this work, we put forward a hypothesis about the decisive role of multivalent nonspecific interactions in the early stages of PML body formation. Our analysis of the PML isoform sequences showed that some of the PML isoforms, primarily PML-II, are prone to phase separation due to their polyampholytic properties and the disordered structure of their C-terminal domains. The similarity of the charge properties of the C-terminal domains of PML-II and PML-VI isoforms made it possible for the first time to detect migration of PML-VI from PML bodies to the periphery of the cell nucleus, similar to the migration of PML-II isoforms. We found a population of “small” (area less than 1 µm2) spherical PML bodies with high dynamics of PML isoforms exchange with nucleoplasm and a low fraction of immobilized proteins, which indicates their liquid state properties. Such structures can act as “seeds” of functionally active PML bodies, providing the necessary concentration of PML isoforms for the formation of intermolecular disulfide bonds between PML monomers. FRAP analysis of larger bodies of toroidal topology showed the existence of an insoluble scaffold in their structure. The hypothesis about the role of nonspecific multiple weak interactions in the formation of PML bodies is further supported by the change in the composition of the scaffold proteins of PML bodies, but not their solidification, under conditions of induction of dimerization of PML isoforms under oxidative stress. Using the colocalization of ALT-associated PML bodies (APBs) with TRF1, we identified APBs and showed the difference in the dynamic properties of APBs and canonical PML bodies.
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Affiliation(s)
- Alexander V. Fonin
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., 194064 St. Petersburg, Russia; (S.A.S.); (O.G.S.); (I.A.A.); (I.M.K.)
- Correspondence: (A.V.F.); (V.N.U.); (K.K.T.); Tel.: +7-812-2971957 (K.K.T.); Fax: +7-812-2970341(K.K.T.)
| | - Sergey A. Silonov
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., 194064 St. Petersburg, Russia; (S.A.S.); (O.G.S.); (I.A.A.); (I.M.K.)
| | - Olesya G. Shpironok
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., 194064 St. Petersburg, Russia; (S.A.S.); (O.G.S.); (I.A.A.); (I.M.K.)
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Iuliia A. Antifeeva
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., 194064 St. Petersburg, Russia; (S.A.S.); (O.G.S.); (I.A.A.); (I.M.K.)
| | - Alexey V. Petukhov
- Institute of Hematology, Almazov National Medical Research Centre, 197341 St. Petersburg, Russia;
| | - Anna E. Romanovich
- St-Petersburg State University Science Park, Resource Center of Molecular and Cell Technologies, Universitetskaya nab. 7-9, 199034 St. Petersburg, Russia;
| | - Irina M. Kuznetsova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., 194064 St. Petersburg, Russia; (S.A.S.); (O.G.S.); (I.A.A.); (I.M.K.)
| | - Vladimir N. Uversky
- Department of Molecular Medicine and Byrd Alzheimer’s Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- Correspondence: (A.V.F.); (V.N.U.); (K.K.T.); Tel.: +7-812-2971957 (K.K.T.); Fax: +7-812-2970341(K.K.T.)
| | - Konstantin K. Turoverov
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., 194064 St. Petersburg, Russia; (S.A.S.); (O.G.S.); (I.A.A.); (I.M.K.)
- Peter the Great St.-Petersburg Polytechnic University, Polytechnicheskaya 29, 195251 St. Petersburg, Russia
- Correspondence: (A.V.F.); (V.N.U.); (K.K.T.); Tel.: +7-812-2971957 (K.K.T.); Fax: +7-812-2970341(K.K.T.)
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Loe TK, Li JSZ, Zhang Y, Azeroglu B, Boddy MN, Denchi EL. Telomere length heterogeneity in ALT cells is maintained by PML-dependent localization of the BTR complex to telomeres. Genes Dev 2020; 34:650-662. [PMID: 32217664 PMCID: PMC7197349 DOI: 10.1101/gad.333963.119] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/26/2020] [Indexed: 12/11/2022]
Abstract
In this study, Loe et al. sought to understand ALT-associated PML bodies (APBs) and their function in the alternative lengthening of telomeres (ALT) pathway, a telomerase-independent mechanism of telomere extension that some cancer cells that use. Using CRISPR/Cas9 to delete PML and APB components from ALT-positive cells, they found that PML is required for the ALT mechanism, and that this necessity stems from APBs’ role in localizing the BLM–TOP3A–RMI (BTR) complex to ALT telomere ends, suggesting that BTR localization to telomeres is sufficient to sustain ALT activity. Telomeres consist of TTAGGG repeats bound by protein complexes that serve to protect the natural end of linear chromosomes. Most cells maintain telomere repeat lengths by using the enzyme telomerase, although there are some cancer cells that use a telomerase-independent mechanism of telomere extension, termed alternative lengthening of telomeres (ALT). Cells that use ALT are characterized, in part, by the presence of specialized PML nuclear bodies called ALT-associated PML bodies (APBs). APBs localize to and cluster telomeric ends together with telomeric and DNA damage factors, which led to the proposal that these bodies act as a platform on which ALT can occur. However, the necessity of APBs and their function in the ALT pathway has remained unclear. Here, we used CRISPR/Cas9 to delete PML and APB components from ALT-positive cells to cleanly define the function of APBs in ALT. We found that PML is required for the ALT mechanism, and that this necessity stems from APBs’ role in localizing the BLM–TOP3A–RMI (BTR) complex to ALT telomere ends. Strikingly, recruitment of the BTR complex to telomeres in a PML-independent manner bypasses the need for PML in the ALT pathway, suggesting that BTR localization to telomeres is sufficient to sustain ALT activity.
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Affiliation(s)
- Taylor K Loe
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Julia Su Zhou Li
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093, USA
| | - Yuxiang Zhang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Benura Azeroglu
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Michael Nicholas Boddy
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Eros Lazzerini Denchi
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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10
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Ségal-Bendirdjian E, Geli V. Non-canonical Roles of Telomerase: Unraveling the Imbroglio. Front Cell Dev Biol 2019; 7:332. [PMID: 31911897 PMCID: PMC6914764 DOI: 10.3389/fcell.2019.00332] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/27/2019] [Indexed: 12/11/2022] Open
Abstract
Telomerase plays a critical role in stem cell function and tissue regeneration that depends on its ability to elongate telomeres. For nearly two decades, it turned out that TERT regulates a broad spectrum of functions including signal transduction, gene expression regulation, and protection against oxidative damage that are independent of its telomere elongation activity. These conclusions that were mainly obtained in cell lines overexpressing telomerase were further strengthened by in vivo models of ectopic expression of telomerase or models of G1 TERT knockout mice without detectable telomere dysfunction. However, the later models were questioned due to the presence of aberrantly shortened telomere in the germline of the parents TERT+/- that were used to create the G1 TERT -/- mice. The physiological relevance of the functions associated with overexpressed telomerase raised also some concerns due to artifactual situations and localizations and complications to quantify the level of TERT. Another concern with non-canonical functions of TERT was the difficulty to separate a direct TERT-related function from secondary effects. Despite these concerns, more and more evidence accumulates for non-canonical roles of telomerase that are non-obligatory extra-telomeric. Here, we review these non-canonical roles of the TERT subunit of telomerase. Also, we emphasize recent results that link TERT to mitochondria and protection to reactive oxygen species suggesting a protective role of TERT in neurons. Throughout this review, we dissect some controversies regarding the non-canonical functions of telomerase and provide some insights to explain these discrepancies. Finally, we discuss the importance of understanding these alternative functions of telomerase for the development of anticancer strategies.
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Affiliation(s)
- Evelyne Ségal-Bendirdjian
- INSERM UMR-S 1124, Team: Cellular Homeostasis, Cancer and Therapies, INSERM US36, CNRS UMS 2009, BioMedTech Facilities, Université de Paris, Paris, France
| | - Vincent Geli
- Marseille Cancer Research Center, U1068 INSERM, UMR 7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, Equipe labellisée Ligue, Marseille, France
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11
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Vancurova M, Hanzlikova H, Knoblochova L, Kosla J, Majera D, Mistrik M, Burdova K, Hodny Z, Bartek J. PML nuclear bodies are recruited to persistent DNA damage lesions in an RNF168-53BP1 dependent manner and contribute to DNA repair. DNA Repair (Amst) 2019; 78:114-127. [PMID: 31009828 DOI: 10.1016/j.dnarep.2019.04.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 03/07/2019] [Accepted: 04/01/2019] [Indexed: 11/29/2022]
Abstract
The bulk of DNA damage caused by ionizing radiation (IR) is generally repaired within hours, yet a subset of DNA lesions may persist even for long periods of time. Such persisting IR-induced foci (pIRIF) co-associate with PML nuclear bodies (PML-NBs) and are among the characteristics of cellular senescence. Here we addressed some fundamental questions concerning the nature and determinants of this co-association, the role of PML-NBs at such sites, and the reason for the persistence of DNA damage in human primary cells. We show that the persistent DNA lesions are devoid of homologous recombination (HR) proteins BRCA1 and Rad51. Our super-resolution microscopy-based analysis showed that PML-NBs are juxtaposed to and partially overlap with the pIRIFs. Notably, depletion of 53BP1 resulted in decreased intersection between PML-NBs and pIRIFs implicating the RNF168-53BP1 pathway in their interaction. To test whether the formation and persistence of IRIFs is PML-dependent and to investigate the role of PML in the context of DNA repair and senescence, we genetically deleted PML in human hTERT-RPE-1 cells. Unexpectedly, upon high-dose IR treatment, cells displayed similar DNA damage signalling, repair dynamics and kinetics of cellular senescence regardless of the presence or absence of PML. In contrast, the PML knock-out cells showed increased sensitivity to low doses of IR and DNA-damaging agents mitomycin C, cisplatin and camptothecin that all cause DNA lesions requiring repair by HR. These results, along with enhanced sensitivity of the PML knock-out cells to DNA-PK and PARP inhibitors implicate PML as a factor contributing to HR-mediated DNA repair.
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Affiliation(s)
- Marketa Vancurova
- Department of Genome Integrity, Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Hana Hanzlikova
- Department of Genome Integrity, Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Lucie Knoblochova
- Department of Genome Integrity, Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jan Kosla
- Department of Genome Integrity, Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Dusana Majera
- Laboratory of Genome Integrity, Institute of Molecular and Translational Medicine, Palacky University, Olomouc, Czech Republic
| | - Martin Mistrik
- Laboratory of Genome Integrity, Institute of Molecular and Translational Medicine, Palacky University, Olomouc, Czech Republic
| | - Kamila Burdova
- Laboratory of Cancer Cell Biology, Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Zdenek Hodny
- Department of Genome Integrity, Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic.
| | - Jiri Bartek
- Department of Genome Integrity, Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic; Laboratory of Genome Integrity, Institute of Molecular and Translational Medicine, Palacky University, Olomouc, Czech Republic; Genome Integrity Unit, Danish Cancer Society Research Center, Copenhagen, Denmark; Science for Life Laboratory, Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 21, Stockholm, Sweden.
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12
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Lin T, Lin TC, McGrail DJ, Bhupal PK, Ku YH, Zhang W, Meng L, Lin SY, Peng G, Tsai RYL. Nucleostemin reveals a dichotomous nature of genome maintenance in mammary tumor progression. Oncogene 2019; 38:3919-3931. [PMID: 30692636 PMCID: PMC6525051 DOI: 10.1038/s41388-019-0710-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 01/11/2019] [Accepted: 01/15/2019] [Indexed: 12/17/2022]
Abstract
A defective homologous recombination (HR) repair program increases tumor incidence as well as providing a survival advantage in patients with breast and ovarian cancers. Here, we hypothesize that the tumor-promoting side of genome maintenance programs may be contributed by a self-renewal protein, nucleostemin (NS). To address this issue, we established its functional importance in mammary tumor progression in mice and showed that mammary tumor cells become highly susceptible to replicative DNA damage following NS depletion and are protected from hydroxyurea-induced damage by NS overexpression. Breast cancer cells with basal-like characters display more reliance on NS for genome maintenance than those with luminal characters. Mechanistically, NS-deficient cells demonstrate a significantly reduced HR repair activity. TCGA analyses of human breast cancers revealed that NS is co-enriched positively with HR repair proteins and that high NS expression correlates with low HR defects and predicts poor progression-free survival and resistance to knockdown of cell cycle checkpoint genes in triple-negative/basal-like breast cancers. This work indicates that NS constitutes a tumor-promoting genome maintenance program required for mammary tumor progression.
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Affiliation(s)
- Tao Lin
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA
| | - Tsung-Chin Lin
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA
| | - Daniel J McGrail
- Department of Systems Biology, MD Anderson Cancer Center, Houston, TX, USA
| | - Parnit K Bhupal
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA
| | - Yi-Hsuan Ku
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA
| | - Wen Zhang
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA
| | - Lingjun Meng
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA
| | - Shiaw-Yih Lin
- Department of Systems Biology, MD Anderson Cancer Center, Houston, TX, USA
| | - Guang Peng
- Department of Clinical Cancer Prevention, MD Anderson Cancer Center, Houston, TX, USA
| | - Robert Y L Tsai
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA. .,Department of Molecular and Cellular Medicine, Texas A&M University, College Station, TX, USA.
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13
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Kavyasudha C, Joel JP, Devi A. Differential expression of nucleostemin in the cytoplasm and nuclei of normal and cancerous cell lines. Turk J Biol 2018; 42:250-258. [PMID: 30814887 DOI: 10.3906/biy-1712-10] [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: 11/03/2022] Open
Abstract
Studies conducted in the past decade have reported nucleostemin (NS) as a nucleolar protein that has a role in self-renewal and cell cycle regulation in cancer/stem cells, but is absent in differentiated cells. The localization and expression patterns of NS have always been disputed, as reports indicate its varied levels among tissues and cells. This study evaluates the expression and localization pattern of NS in normal cells, cancer cell lines, and stem cells. Our findings revealed that the expression of NS was high in cancers originating from the skin and liver compared to the normal cell lines. NS knockdown effects the proliferation of normal cell lines, similar to cancerous cell lines. The localization pattern of NS was analyzed by immunofluorescence, which showed that NS was localized in the nuclei of normal cell lines but is present both in the nucleus and the cytoplasm of cancerous/stem cell lines. Interestingly, we observed that siNS cancerous cell lines had lower NS in the cytoplasm, which did not salvage the reduction in proliferation caused by siNS. We postulate that the loss of NS in the nucleus inhibits the proliferative ability of both normal and cancerous cells at similar rates, although the role of NS in the cytoplasm apart from proliferation needs to be further explored.
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Affiliation(s)
- Chavali Kavyasudha
- Stem Cell Biology Laboratory, Department of Genetic Engineering, SRM University , Kattankulathur , India
| | - Joseph P Joel
- Stem Cell Biology Laboratory, Department of Genetic Engineering, SRM University , Kattankulathur , India
| | - Arikketh Devi
- Stem Cell Biology Laboratory, Department of Genetic Engineering, SRM University , Kattankulathur , India
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14
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Li C, Peng Q, Wan X, Sun H, Tang J. C-terminal motifs in promyelocytic leukemia protein isoforms critically regulate PML nuclear body formation. J Cell Sci 2017; 130:3496-3506. [PMID: 28851805 DOI: 10.1242/jcs.202879] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 08/10/2017] [Indexed: 12/11/2022] Open
Abstract
Promyelocytic leukemia protein (PML) nuclear bodies (NBs), which are sub-nuclear protein structures, are involved in a variety of important cellular functions. PML-NBs are assembled by PML isoforms, and contact between small ubiquitin-like modifiers (SUMOs) with the SUMO interaction motif (SIM) are critically involved in this process. PML isoforms contain a common N-terminal region and a variable C-terminus. However, the contribution of the C-terminal regions to PML-NB formation remains poorly defined. Here, using high-resolution microscopy, we show that mutation of the SIM distinctively influences the structure of NBs formed by each individual PML isoform, with that of PML-III and PML-V minimally changed, and PML-I and PML-IV dramatically impaired. We further identify several C-terminal elements that are important in regulating NB structure and provide strong evidence to suggest that the 8b element in PML-IV possesses a strong ability to interact with SUMO-1 and SUMO-2, and critically participates in NB formation. Our findings highlight the importance of PML C-termini in NB assembly and function, and provide molecular insight into the PML-NB assembly of each distinctive isoform.
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Affiliation(s)
- Chuang Li
- State Key Laboratory of Agrobiotechnology and College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Qiongfang Peng
- State Key Laboratory of Agrobiotechnology and College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Xiao Wan
- State Key Laboratory of Agrobiotechnology and College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Haili Sun
- State Key Laboratory of Agrobiotechnology and College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Jun Tang
- State Key Laboratory of Agrobiotechnology and College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
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15
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Kamranvar SA, Masucci MG. Regulation of Telomere Homeostasis during Epstein-Barr virus Infection and Immortalization. Viruses 2017; 9:v9080217. [PMID: 28792435 PMCID: PMC5580474 DOI: 10.3390/v9080217] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 07/25/2017] [Accepted: 07/26/2017] [Indexed: 12/11/2022] Open
Abstract
The acquisition of unlimited proliferative potential is dependent on the activation of mechanisms for telomere maintenance, which counteracts telomere shortening and the consequent triggering of the DNA damage response, cell cycle arrest, and apoptosis. The capacity of Epstein Barr virus (EBV) to infect B-lymphocytes in vitro and transform the infected cells into autonomously proliferating immortal cell lines underlies the association of this human gamma-herpesvirus with a broad variety of lymphoid and epithelial cell malignancies. Current evidence suggests that both telomerase-dependent and -independent pathways of telomere elongation are activated in the infected cells during the early and late phases of virus-induced immortalization. Here we review the interaction of EBV with different components of the telomere maintenance machinery and the mechanisms by which the virus regulates telomere homeostasis in proliferating cells. We also discuss how these viral strategies may contribute to malignant transformation.
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Affiliation(s)
- Siamak A Kamranvar
- Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, 751 23 Uppsala, Sweden.
| | - Maria G Masucci
- Department of Cell and Molecular Biology, Karolinska Institutet, 171 77 Stockholm, Sweden.
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16
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Knockdown of Nucleostemin in an ovarian cancer SKOV-3 cell line and its effects on cell malignancy. Biochem Biophys Res Commun 2017; 487:262-267. [PMID: 28412352 DOI: 10.1016/j.bbrc.2017.04.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 04/11/2017] [Indexed: 01/22/2023]
Abstract
Nucleostemin plays an essential role in the proliferation of some stem cells and cancer cells, but no research has been conducted to assess the link between Nucleostemin and ovarian cancer. To investigate the role of Nucleostemin in ovarian cancer tumorigenesis, we generated short hairpin (sh)RNA to knockdown the expression of the Nucleostemin gene in an ovarian cancer SKOV-3 cell line. We found that knockdown of this gene led to cell-cycle arrest, as well as to an increase in apoptosis. In addition, migration and invasion demonstrated significant inhibition in Nucleostemin-deficient cells. Furthermore, the knockdown of Nucleostemin dramatically suppressed xenograft progression in BALB/c nude mice. Our findings suggest that Nucleostemin is associated with malignancy in an ovarian cancer SKOV-3 cell line.
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17
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Grigoryan EN, Markitantova YV. Cellular and Molecular Preconditions for Retinal Pigment Epithelium (RPE) Natural Reprogramming during Retinal Regeneration in Urodela. Biomedicines 2016; 4:E28. [PMID: 28536395 PMCID: PMC5344269 DOI: 10.3390/biomedicines4040028] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 11/26/2016] [Accepted: 11/26/2016] [Indexed: 12/25/2022] Open
Abstract
Many regeneration processes in animals are based on the phenomenon of cell reprogramming followed by proliferation and differentiation in a different specialization direction. An insight into what makes natural (in vivo) cell reprogramming possible can help to solve a number of biomedical problems. In particular, the first problem is to reveal the intrinsic properties of the cells that are necessary and sufficient for reprogramming; the second, to evaluate these properties and, on this basis, to reveal potential endogenous sources for cell substitution in damaged tissues; and the third, to use the acquired data for developing approaches to in vitro cell reprogramming in order to obtain a cell reserve for damaged tissue repair. Normal cells of the retinal pigment epithelium (RPE) in newts (Urodela) can change their specialization and transform into retinal neurons and ganglion cells (i.e., actualize their retinogenic potential). Therefore, they can serve as a model that provides the possibility to identify factors of the initial competence of vertebrate cells for reprogramming in vivo. This review deals mainly with the endogenous properties of native newt RPE cells themselves and, to a lesser extent, with exogenous mechanisms regulating the process of reprogramming, which are actively discussed.
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Affiliation(s)
- Eleonora N Grigoryan
- Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow 119334, Russia.
| | - Yuliya V Markitantova
- Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow 119334, Russia.
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18
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Upregulated expression of Nucleostemin/GNL3 is associated with poor prognosis and Sorafenib Resistance in Hepatocellular Carcinoma. Pathol Res Pract 2016; 213:688-697. [PMID: 28476378 DOI: 10.1016/j.prp.2016.11.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 11/06/2016] [Accepted: 11/11/2016] [Indexed: 12/13/2022]
Abstract
Nucleostemin (NS)/GNL3 protein has been recently documented to be a nucleolar protein that was abundantly expressed in stem cells and cancer cells. Herein, we showed that NS was upregulated in HCC tissues and the expression of NS was inversely correlated with that of p53. Overexpression of NS predicted significantly worsened prognosis in HCC patients, suggesting that NS might serve as a prognostic marker of HCC. In addition, we found that depletion of NS sensitized HCC cells to sorafenib-induced apoptosis. Moreover, we found that the mechanism underlying NS-mediated sorafenib resistance involved dysregulated expression of p53, and downstream Bax and Bcl-2 proteins. NS interacted with p53 in HCC cells. Depletion of NS increased the expression of p53 and Bax, whereas impaired the level of cellular Bcl-2. Interference of NS enhanced the cytotoxic effects of sorafenib in HCC cells. Furthermore, ectopic expression of NS impaired the apoptosis of HCC cells following sorafenib exposure. Therefore, NS may contribute to sorafenib resistance in HCC cells through the modulation of p53 pathway and Bcl-2 proteins. These findings indicated that the combination of silencing NS expression and sorafenib treatment is a promising therapeutic strategy in treatment of HCC.
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19
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Wilson FR, Ho A, Walker JR, Zhu XD. Cdk-dependent phosphorylation regulates TRF1 recruitment to PML bodies and promotes C-circle production in ALT cells. J Cell Sci 2016; 129:2559-72. [PMID: 27185864 DOI: 10.1242/jcs.186098] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/06/2016] [Indexed: 12/26/2022] Open
Abstract
TRF1, a duplex telomeric DNA binding protein, is implicated in homologous-recombination-based alternative lengthening of telomeres, known as ALT. However, how TRF1 promotes ALT activity has yet to be fully characterized. Here we report that Cdk-dependent TRF1 phosphorylation on T371 acts as a switch to create a pool of TRF1, referred to as (pT371)TRF1, which is recruited to ALT-associated PML bodies (APBs) in S and G2 phases independently of its binding to telomeric DNA. We find that phosphorylation of T371 is essential for APB formation and C-circle production, both of which are hallmarks of ALT. We show that the interaction of (pT371)TRF1 with APBs is dependent upon ATM and homologous-recombination-promoting factors Mre11 and BRCA1. In addition, (pT371)TRF1 interaction with APBs is sensitive to transcription inhibition, which also reduces DNA damage at telomeres. Furthermore, overexpression of RNaseH1 impairs (pT371)TRF1 recruitment to APBs in the presence of campothecin, an inhibitor that prevents topoisomerase I from resolving RNA-DNA hybrids. These results suggest that transcription-associated DNA damage, perhaps arising from processing RNA-DNA hybrids at telomeres, triggers (pT371)TRF1 recruitment to APBs to facilitate ALT activity.
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Affiliation(s)
- Florence R Wilson
- Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| | - Angus Ho
- Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| | - John R Walker
- Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| | - Xu-Dong Zhu
- Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1
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20
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Tsai RYL. Balancing self-renewal against genome preservation in stem cells: How do they manage to have the cake and eat it too? Cell Mol Life Sci 2016; 73:1803-23. [PMID: 26886024 PMCID: PMC5040593 DOI: 10.1007/s00018-016-2152-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/18/2016] [Accepted: 01/28/2016] [Indexed: 01/22/2023]
Abstract
Stem cells are endowed with the awesome power of self-renewal and multi-lineage differentiation that allows them to be major contributors to tissue homeostasis. Owing to their longevity and self-renewal capacity, they are also faced with a higher risk of genomic damage compared to differentiated cells. Damage on the genome, if not prevented or repaired properly, will threaten the survival of stem cells and culminate in organ failure, premature aging, or cancer formation. It is therefore of paramount importance that stem cells remain genomically stable throughout life. Given their unique biological and functional requirement, stem cells are thought to manage genotoxic stress somewhat differently from non-stem cells. The focus of this article is to review the current knowledge on how stem cells escape the barrage of oxidative and replicative DNA damage to stay in self-renewal. A clear statement on this subject should help us better understand tissue regeneration, aging, and cancer.
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Affiliation(s)
- Robert Y L Tsai
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University Health Science Center, 2121 W. Holcombe Blvd, Houston, TX, 77030, USA.
- Department of Molecular and Cellular Medicine, Texas A&M University Health Science Center, College Station, TX, 77843, USA.
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21
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Shekhani MT, Barber JR, Bezerra SM, Heaphy CM, Gonzalez Roibon ND, Taheri D, Reis LO, Guner G, Joshu CE, Netto GJ, Meeker AK. High-resolution telomere fluorescence in situ hybridization reveals intriguing anomalies in germ cell tumors. Hum Pathol 2016; 54:106-12. [PMID: 27085557 DOI: 10.1016/j.humpath.2016.03.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/23/2016] [Accepted: 03/31/2016] [Indexed: 12/26/2022]
Abstract
Testicular germ cell tumor (TGCT) is the most common malignancy of young men. Most patients are completely cured, which distinguishes these from most other malignancies. Orchiectomy specimens (n=76) were evaluated using high-resolution (single-cell discriminative) telomere-specific fluorescence in situ hybridization (FISH) with simultaneous Oct4 immunofluorescence to describe telomere length phenotype in TGCT neoplastic cells. For the first time, the TGCT precursor lesion, germ cell neoplasia in situ (GCNIS) is also evaluated in depth. The intensity of the signals from cancerous cells was compared to the same patient's reference cells-namely, healthy germ cells (defined as "medium" length) and interstitial/somatic cells (defined as "short" telomere length). We observed short telomeres in most GCNIS and pure seminomas (P=.006 and P=.0005, respectively). In contrast, nonseminomas displayed longer telomeres. Lesion-specific telomere lengths were documented in mixed tumor cases. Embryonal carcinoma (EC) demonstrated the longest telomeres. A fraction of EC displays the telomerase-independent alternative lengthening of telomeres (ALT) phenotype (24% of cases). Loss of ATRX or DAXX nuclear expression was strongly associated with ALT; however, nuclear expression of both proteins was retained in half of ALT-positive ECs. The particular distribution of telomere lengths among TGCT and GCNIS precursors implicate telomeres anomalies in pathogenesis. These results may advise management decisions as well.
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Affiliation(s)
- Mohammed Talha Shekhani
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD; Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - John R Barber
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - Stephania M Bezerra
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Christopher M Heaphy
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD; Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
| | | | - Diana Taheri
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Leonardo O Reis
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Gunes Guner
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Corinne E Joshu
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD; Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - George J Netto
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD; Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD; Department of Urology, James Buchanan Brady Urological Institute at Johns Hopkins, Baltimore, MD
| | - Alan K Meeker
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD; Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD; Department of Urology, James Buchanan Brady Urological Institute at Johns Hopkins, Baltimore, MD.
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22
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Affiliation(s)
- R Y L Tsai
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX, USA
- Department of Molecular and Cellular Medicine, Texas A&M University Health Science Center, College Station, TX, USA
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23
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Abstract
Nucleostemin (NS) protects the genome from replication-induced DNA damage and has an indispensable role in maintaining the continuous proliferation of both p53-wild-type and mutant cells. Yet, some outcomes of NS-deficient cells appear to be shaped by their p53 status, which stimulates conflicting claims on the role of p53 in executing the NS function. This disparity was conveniently attributed to the usual suspect of cell-type variations. To provide a definitive resolution, we investigated the interplay between NS and p53 in two pairs of isogenic cells, that is, genetically modified mouse embryonic fibroblast (MEF) cells and HCT116 human colon cancer cells. In MEF cells, p53 deletion further compromises rather than rescues the proliferative potential of NS-depleted cells without changing their G2/M arrest fate before prophase entry. The detrimental effect of p53 loss in NS-depleted MEF cells correlates with a dramatic increase of polyploid giant cells (PGCs) (up to 24%), which indicates aberrant mitosis. To determine how p53 shapes the response of cells to NS depletion at the molecular level, we showed that p53 turns on the expression of reprimo and MDM2 in NS-deficient MEF cells. In absence of p53, NS-deficient MEF cells exhibit increased levels of phosphorylated cdc2 (Y15) protein and cyclin B1. In cancer (HCT116) cells, NS loss leads to G2/M arrest under both p53wt and p53ko conditions and increases phosphorylated cdc2 more in p53ko than in p53wt cells, as it does in MEF cells. Unlike its effect in MEF cells, NS depletion decreases tumor growth and increases the expression of reprimo and cyclin B1 in a p53-independent manner in HCT116 cells. Our data indicate that the p53 status of NS-deficient cells orchestrates how they respond to G2/M arrest in a normal versus cancer cell distinct fashion.
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Affiliation(s)
- Guanqun Huang
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA; Department of general surgery, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou 510700, China
| | - Lingjun Meng
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA
| | - Robert Y L Tsai
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA; Department of Molecular and Cellular Medicine, Texas A&M University Health Science Center, College Station, TX 77054, USA
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24
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Yuan F, Cheng Q, Li G, Tong T. Nucleostemin Knockdown Sensitizes Hepatocellular Carcinoma Cells to Ultraviolet and Serum Starvation-Induced Apoptosis. PLoS One 2015; 10:e0141678. [PMID: 26517370 PMCID: PMC4627730 DOI: 10.1371/journal.pone.0141678] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 10/12/2015] [Indexed: 11/20/2022] Open
Abstract
Nucleostemin (NS) is a GTP-binding protein that is predominantly expressed in embryonic and adult stem cells but not in terminally differentiated cells. NS plays an essential role in maintaining the continuous proliferation of stem cells and some types of cancer cells. However, the role of NS in hepatocellular carcinoma (HCC) remains unclear. Therefore, this study aimed to clarify the role of NS in HCC. First, we demonstrated high expression of NS in most HCC cell lines and liver cancer tissues. NS knockdown induced a severe decline in cell viability of MHCC97H cells as detected by MTT and cell proliferation assays. Next, we used ultraviolet (UV) and serum starvation-induced apoptosis models to investigate whether NS suppression or up-regulation affects HCC cell apoptosis. After UV treatment or serum starvation, apoptosis was strongly enhanced in MHCC97H and Bel7402 cells transfected with small interfering RNA against NS, whereas NS overexpression inhibited UV- and serum-induced apoptosis of HCC cells. Furthermore, after UV irradiation, inhibition of NS increased the expression of pro-apoptosis protein caspase 3 and decreased the expression of anti-apoptosis protein Bcl-2. A caspase 3 inhibitor could obviously prevent NS knockdown-induced apoptosis. In conclusion, our study demonstrated overexpression of NS in most HCC tissues compared with their matched surrounding tissues, and silencing NS promoted UV- and serum starvation-induced apoptosis of MHCC97H and Bel7402 cells. Therefore, the NS gene might be a potential therapeutic target of HCC.
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Affiliation(s)
- Fuwen Yuan
- Research Center on Aging, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, China
- Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Beijing, China
| | - Qian Cheng
- Research Center on Aging, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, China
- Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Beijing, China
| | - Guodong Li
- Research Center on Aging, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, China
- Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Beijing, China
| | - Tanjun Tong
- Research Center on Aging, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, China
- Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Beijing, China
- * E-mail:
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25
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Markitantova YV, Avdonin PP, Grigoryan EN. Identification of the gene encoding nucleostemin in the eye tissues of Pleurodeles waltl. BIOL BULL+ 2015. [DOI: 10.1134/s1062359015050088] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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26
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Abstract
A veritable explosion of primary research papers within the past 10 years focuses on nucleolar and ribosomal stress, and for good reason: with ribosome biosynthesis consuming ~80% of a cell’s energy, nearly all metabolic and signaling pathways lead ultimately to or from the nucleolus. We begin by describing p53 activation upon nucleolar stress resulting in cell cycle arrest or apoptosis. The significance of this mechanism cannot be understated, as oncologists are now inducing nucleolar stress strategically in cancer cells as a potential anti-cancer therapy. We also summarize the human ribosomopathies, syndromes in which ribosome biogenesis or function are impaired leading to birth defects or bone narrow failures; the perplexing problem in the ribosomopathies is why only certain cells are affected despite the fact that the causative mutation is systemic. We then describe p53-independent nucleolar stress, first in yeast which lacks p53, and then in other model metazoans that lack MDM2, the critical E3 ubiquitin ligase that normally inactivates p53. Do these presumably ancient p53-independent nucleolar stress pathways remain latent in human cells? If they still exist, can we use them to target >50% of known human cancers that lack functional p53?
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Affiliation(s)
- Allison James
- a Department of Biological Sciences; Louisiana State University; Baton Rouge, LA USA
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Osterwald S, Deeg KI, Chung I, Parisotto D, Wörz S, Rohr K, Erfle H, Rippe K. PML induces compaction, TRF2 depletion and DNA damage signaling at telomeres and promotes their alternative lengthening. J Cell Sci 2015; 128:1887-1900. [DOI: 10.1242/jcs.148296] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Abstract
ABSTRACT
The alternative lengthening of telomeres (ALT) mechanism allows cancer cells to escape senescence and apoptosis in the absence of active telomerase. A characteristic feature of this pathway is the assembly of ALT-associated promyelocytic leukemia (PML) nuclear bodies (APBs) at telomeres. Here, we dissected the role of APBs in a human ALT cell line by performing an RNA interference screen using an automated 3D fluorescence microscopy platform and advanced 3D image analysis. We identified 29 proteins that affected APB formation, which included proteins involved in telomere and chromatin organization, protein sumoylation and DNA repair. By integrating and extending these findings, we found that APB formation induced clustering of telomere repeats, telomere compaction and concomitant depletion of the shelterin protein TRF2 (also known as TERF2). These APB-dependent changes correlated with the induction of a DNA damage response at telomeres in APBs as evident by a strong enrichment of the phosphorylated form of the ataxia telangiectasia mutated (ATM) kinase. Accordingly, we propose that APBs promote telomere maintenance by inducing a DNA damage response in ALT-positive tumor cells through changing the telomeric chromatin state to trigger ATM phosphorylation.
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Affiliation(s)
- Sarah Osterwald
- Research Group Genome Organization & Function, Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, 69120 Heidelberg, Germany
| | - Katharina I. Deeg
- Research Group Genome Organization & Function, Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, 69120 Heidelberg, Germany
| | - Inn Chung
- Research Group Genome Organization & Function, Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, 69120 Heidelberg, Germany
| | - Daniel Parisotto
- Research Group Genome Organization & Function, Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, 69120 Heidelberg, Germany
| | - Stefan Wörz
- Department of Bioinformatics and Functional Genomics, Biomedical Computer Vision Group, University of Heidelberg & DKFZ, BioQuant, IPMB, 69120 Heidelberg, Germany
| | - Karl Rohr
- Department of Bioinformatics and Functional Genomics, Biomedical Computer Vision Group, University of Heidelberg & DKFZ, BioQuant, IPMB, 69120 Heidelberg, Germany
| | - Holger Erfle
- ViroQuant-CellNetworks RNAi Screening Facility, University of Heidelberg & BioQuant, 69120 Heidelberg, Germany
| | - Karsten Rippe
- Research Group Genome Organization & Function, Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, 69120 Heidelberg, Germany
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Tsai RYL. Pluripotency Versus Self-Renewal of ES Cells: Two Sides of the Same Coin or More? Stem Cells 2015; 33:2358-9. [PMID: 25809666 DOI: 10.1002/stem.2008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 02/28/2015] [Indexed: 12/22/2022]
Affiliation(s)
- Robert Y L Tsai
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas, 77030, USA.,Department of Molecular and Cellular Medicine, Texas A&M University Health Science Center, College Station, Texas, 77843, USA
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Samse K, Emathinger J, Hariharan N, Quijada P, Ilves K, Völkers M, Ormachea L, De La Torre A, Orogo AM, Alvarez R, Din S, Mohsin S, Monsanto M, Fischer KM, Dembitsky WP, Gustafsson ÅB, Sussman MA. Functional Effect of Pim1 Depends upon Intracellular Localization in Human Cardiac Progenitor Cells. J Biol Chem 2015; 290:13935-47. [PMID: 25882843 DOI: 10.1074/jbc.m114.617431] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Indexed: 01/07/2023] Open
Abstract
Human cardiac progenitor cells (hCPC) improve heart function after autologous transfer in heart failure patients. Regenerative potential of hCPCs is severely limited with age, requiring genetic modification to enhance therapeutic potential. A legacy of work from our laboratory with Pim1 kinase reveals effects on proliferation, survival, metabolism, and rejuvenation of hCPCs in vitro and in vivo. We demonstrate that subcellular targeting of Pim1 bolsters the distinct cardioprotective effects of this kinase in hCPCs to increase proliferation and survival, and antagonize cellular senescence. Adult hCPCs isolated from patients undergoing left ventricular assist device implantation were engineered to overexpress Pim1 throughout the cell (PimWT) or targeted to either mitochondrial (Mito-Pim1) or nuclear (Nuc-Pim1) compartments. Nuc-Pim1 enhances stem cell youthfulness associated with decreased senescence-associated β-galactosidase activity, preserved telomere length, reduced expression of p16 and p53, and up-regulation of nucleostemin relative to PimWT hCPCs. Alternately, Mito-Pim1 enhances survival by increasing expression of Bcl-2 and Bcl-XL and decreasing cell death after H2O2 treatment, thereby preserving mitochondrial integrity superior to PimWT. Mito-Pim1 increases the proliferation rate by up-regulation of cell cycle modulators Cyclin D, CDK4, and phospho-Rb. Optimal stem cell traits such as proliferation, survival, and increased youthful properties of aged hCPCs are enhanced after targeted Pim1 localization to mitochondrial or nuclear compartments. Targeted Pim1 overexpression in hCPCs allows for selection of the desired phenotypic properties to overcome patient variability and improve specific stem cell characteristics.
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Affiliation(s)
- Kaitlen Samse
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Jacqueline Emathinger
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Nirmala Hariharan
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Pearl Quijada
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Kelli Ilves
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Mirko Völkers
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Lucia Ormachea
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Andrea De La Torre
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Amabel M Orogo
- the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, and
| | - Roberto Alvarez
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Shabana Din
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Sadia Mohsin
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Megan Monsanto
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | - Kimberlee M Fischer
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182
| | | | - Åsa B Gustafsson
- the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, and
| | - Mark A Sussman
- From the San Diego Heart Research Institute, San Diego State University, San Diego, California 92182,
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30
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Hariharan N, Quijada P, Mohsin S, Joyo A, Samse K, Monsanto M, De La Torre A, Avitabile D, Ormachea L, McGregor MJ, Tsai EJ, Sussman MA. Nucleostemin rejuvenates cardiac progenitor cells and antagonizes myocardial aging. J Am Coll Cardiol 2015; 65:133-47. [PMID: 25593054 DOI: 10.1016/j.jacc.2014.09.086] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 09/03/2014] [Accepted: 09/23/2014] [Indexed: 12/16/2022]
Abstract
BACKGROUND Functional decline in stem cell-mediated regeneration contributes to aging associated with cellular senescence in c-kit+ cardiac progenitor cells (CPCs). Clinical implementation of CPC-based therapy in elderly patients would benefit tremendously from understanding molecular characteristics of senescence to antagonize aging. Nucleostemin (NS) is a nucleolar protein regulating stem cell proliferation and pluripotency. OBJECTIVES This study sought to demonstrate that NS preserves characteristics associated with "stemness" in CPCs and antagonizes myocardial senescence and aging. METHODS CPCs isolated from human fetal (fetal human cardiac progenitor cell [FhCPC]) and adult failing (adult human cardiac progenitor cell [AhCPC]) hearts, as well as young (young cardiac progenitor cell [YCPC]) and old mice (old cardiac progenitor cell [OCPC]), were studied for senescence characteristics and NS expression. Heterozygous knockout mice with 1 functional allele of NS (NS+/-) were used to demonstrate that NS preserves myocardial structure and function and slows characteristics of aging. RESULTS NS expression is decreased in AhCPCs relative to FhCPCs, correlating with lowered proliferation potential and shortened telomere length. AhCPC characteristics resemble those of OCPCs, which have a phenotype induced by NS silencing, resulting in cell flattening, senescence, multinucleated cells, decreased S-phase progression, diminished expression of stemness markers, and up-regulation of p53 and p16. CPC senescence resulting from NS loss is partially p53 dependent and is rescued by concurrent silencing of p53. Mechanistically, NS induction correlates with Pim-1 kinase-mediated stabilization of c-Myc. Engineering OCPCs and AhCPCs to overexpress NS decreases senescent and multinucleated cells, restores morphology, and antagonizes senescence, thereby preserving phenotypic properties of "stemness." Early cardiac aging with a decline in cardiac function, an increase in senescence markers p53 and p16, telomere attrition, and accompanied CPC exhaustion is evident in NS+/- mice. CONCLUSIONS Youthful properties and antagonism of senescence in CPCs and the myocardium are consistent with a role for NS downstream from Pim-1 signaling that enhances cardiac regeneration.
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Affiliation(s)
- Nirmala Hariharan
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Pearl Quijada
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Sadia Mohsin
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Anya Joyo
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Kaitlen Samse
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Megan Monsanto
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Andrea De La Torre
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Daniele Avitabile
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California; Department of Clinical and Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Lucia Ormachea
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Michael J McGregor
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California
| | - Emily J Tsai
- Section in Cardiology and Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Mark A Sussman
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, California.
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Abstract
A quintessential trait of stem cells is embedded in their ability to self-renew without incurring DNA damage as a result of genome replication. One key self-renewal factor is the nucleolar GTP-binding protein nucleostemin (also known as guanine-nucleotide-binding protein-like 3, GNL3, in invertebrate species). Several studies have recently pointed to an unexpected role of nucleostemin in safeguarding the genome integrity of stem and cancer cells. Since its discovery, the predominant presence of nucleostemin in the nucleolus has led to the notion that it might function in the card-carrying event of the nucleolus--the biogenesis of ribosomes. As tantalizing as this might be, a ribosomal role of nucleostemin is refuted by evidence from recent studies, which argues that nucleostemin depletion triggers a primary event of DNA damage in S phase cells that then leads to ribosomal perturbation. Furthermore, there have been conflicting reports regarding the p53 dependency of nucleostemin activity and the cell cycle arrest profile of nucleostemin-depleted cells. In this Commentary, I propose a model that explains how the many contradictory observations surrounding nucleostemin can be reconciled and suggest that this protein might not be as multi-tasking as has been previously perceived. The story of nucleostemin highlights the complexity of the underlying molecular events associated with the appearance of any cell biological phenotype and also signifies a new understanding of the genome maintenance program in stem cells.
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Affiliation(s)
- Robert Y L Tsai
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
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32
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SUN XIAOLI, JIA YU, WEI YUANYU, LIU SHUAI, YUE BAOHONG. Gene expression profiling of HL-60 cells following knockdown of nucleostemin using DNA microarrays. Oncol Rep 2014; 32:739-47. [DOI: 10.3892/or.2014.3240] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/29/2014] [Indexed: 11/05/2022] Open
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Hariharan N, Sussman MA. Stressing on the nucleolus in cardiovascular disease. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1842:798-801. [PMID: 24514103 PMCID: PMC3972279 DOI: 10.1016/j.bbadis.2013.09.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/18/2013] [Indexed: 12/23/2022]
Abstract
The nucleolus is a multifunctional organelle with multiple roles involving cell proliferation, growth, survival, ribosome biogenesis and stress response signaling. Alteration of nucleolar morphology and architecture signifies an early response to increased cellular stress. This review briefly summarizes nucleolar response to cardiac stress signals and details the role played by nucleolar proteins in cardiovascular pathophysiology. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.
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Affiliation(s)
- Nirmala Hariharan
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, CA 92182, USA
| | - Mark A Sussman
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, CA 92182, USA.
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34
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Abstract
Long known as the center of ribosome synthesis, the nucleolus is connected to cell cycle regulation in more subtle ways. One is a surveillance system that reacts promptly when rRNA synthesis or processing is impaired, halting cell cycle progression. Conversely, the nucleolus also acts as a first-responder to growth-related stress signals. Here we review emerging concepts on how these "infraribosomal" links between the nucleolus and cell cycle progression operate in both forward and reverse gears. We offer perspectives on how new cancer therapeutic designs that target this infraribosomal mode of cell growth control may shape future clinical progress.
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Affiliation(s)
- Robert Y L Tsai
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA; and
| | - Thoru Pederson
- Program in Cell and Developmental Dynamics, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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35
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Lin T, Meng L, Lin TC, Wu LJ, Pederson T, Tsai RYL. Nucleostemin and GNL3L exercise distinct functions in genome protection and ribosome synthesis, respectively. J Cell Sci 2014; 127:2302-12. [PMID: 24610951 DOI: 10.1242/jcs.143842] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The mammalian nucleolar proteins nucleostemin and GNL3-like (GNL3L) are encoded by paralogous genes that arose from an ancestral invertebrate gene, GNL3. Invertebrate GNL3 has been implicated in ribosome biosynthesis, as has its mammalian descendent, GNL3L. The paralogous mammalian nucleostemin protein has, instead, been implicated in cell renewal. Here, we found that depletion of nucleostemin in a human breast carcinoma cell line triggers prompt and significant DNA damage in S-phase cells without perturbing the initial step of ribosomal (r)RNA synthesis and only mildly affects the total ribosome production. By contrast, GNL3L depletion markedly impairs ribosome production without inducing appreciable DNA damage. These results indicate that, during vertebrate evolution, GNL3L retained the role of the ancestral gene in ribosome biosynthesis, whereas the paralogous nucleostemin acquired a novel genome-protective function. Our results provide a coherent explanation for what had seemed to be contradictory findings about the functions of the invertebrate versus vertebrate genes and are suggestive of how the nucleolus was fine-tuned for a role in genome protection and cell-cycle control as the vertebrates evolved.
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Affiliation(s)
- Tao Lin
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Lingjun Meng
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Tsung-Chin Lin
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Laura J Wu
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Thoru Pederson
- Program in Cell and Developmental Dynamics, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Robert Y L Tsai
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
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36
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Lin T, Ibrahim W, Peng CY, Finegold MJ, Tsai RY. A novel role of nucleostemin in maintaining the genome integrity of dividing hepatocytes during mouse liver development and regeneration. Hepatology 2013; 58:2176-87. [PMID: 23813570 PMCID: PMC3844114 DOI: 10.1002/hep.26600] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 06/17/2013] [Indexed: 01/04/2023]
Abstract
UNLABELLED During liver development and regeneration, hepatocytes undergo rapid cell division and face an increased risk of DNA damage associated with active DNA replication. The mechanism that protects proliferating hepatocytes from replication-induced DNA damage remains unclear. Nucleostemin (NS) is known to be up-regulated during liver regeneration, and loss of NS is associated with increased DNA damage in cancer cells. To determine whether NS is involved in protecting the genome integrity of proliferating hepatocytes, we created an albumin promoter-driven NS conditional-null (albNS(cko) ) mouse model. Livers of albNS(cko) mice begin to show loss of NS in developing hepatocytes from the first postnatal week and increased DNA damage and hepatocellular injury at 1-2 weeks of age. At 3-4 weeks, albNS(cko) livers develop bile duct hyperplasia and show increased apoptotic cells, necrosis, regenerative nodules, and evidence suggestive of hepatic stem/progenitor cell activation. CCl4 treatment enhances degeneration and DNA damage in NS-deleted hepatocytes and increases biliary hyperplasia and A6(+) cells in albNS(cko) livers. After 70% partial hepatectomy, albNS(cko) livers show increased DNA damage in parallel with a blunted and prolonged regenerative response. The DNA damage in NS-depleted hepatocytes is explained by the impaired recruitment of a core DNA repair enzyme, RAD51, to replication-induced DNA damage foci. CONCLUSION This work reveals a novel genome-protective role of NS in developing and regenerating hepatocytes.
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Affiliation(s)
- Tao Lin
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030 USA
| | - Wessam Ibrahim
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030 USA
| | - Cheng-Yuan Peng
- School of Medicine, China Medical University, Taichung, 40402, Taiwan, Division of Hepatogastroenterology, Department of Internal Medicine, China Medical University Hospital, Taichung, 40402, Taiwan
| | - Milton J Finegold
- Gastrointestinal & Hepatobiliary Pathology, Texas Children's Hospital Houston, Texas 77030 USA, Department of Pathology & Immunology, Baylor College of Medicine, Texas 77030 USA
| | - Robert Y.L. Tsai
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030 USA
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37
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Yamashita M, Nitta E, Nagamatsu G, Ikushima YM, Hosokawa K, Arai F, Suda T. Nucleostemin is indispensable for the maintenance and genetic stability of hematopoietic stem cells. Biochem Biophys Res Commun 2013; 441:196-201. [DOI: 10.1016/j.bbrc.2013.10.032] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 10/08/2013] [Indexed: 01/10/2023]
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38
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Uema N, Ooshio T, Harada K, Naito M, Naka K, Hoshii T, Tadokoro Y, Ohta K, Ali MAE, Katano M, Soga T, Nakanuma Y, Okuda A, Hirao A. Abundant nucleostemin expression supports the undifferentiated properties of germ cell tumors. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:592-603. [PMID: 23885716 DOI: 10.1016/j.ajpath.2013.04.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 03/21/2013] [Accepted: 04/30/2013] [Indexed: 12/23/2022]
Abstract
Nucleostemin (NS) is a nucleolar GTP-binding protein that is involved in ribosomal biogenesis and protection of telomeres. We investigated the expression of NS in human germ cell tumors and its function in a mouse germ cell tumor model. NS was abundantly expressed in undifferentiated, but not differentiated, types of human testicular germ cell tumors. NS was expressed concomitantly with OCT3/4, a critical regulator of the undifferentiated status of pluripotent stem cells in primordial germ cells and embryonal carcinomas. To investigate the roles of NS in tumor growth in vivo, we used a mouse teratoma model. Analysis of teratomas derived from embryonic stem cells in which the NS promoter drives GFP expression showed that cells highly expressing NS were actively proliferating and exhibited the characteristics of tumor-initiating cells, including the ability to initiate and propagate tumor cells in vivo. NS-expressing cells exhibited higher levels of GTP than non-NS-expressing cells. Because NS protein is stabilized by intracellular GTP, metabolic changes may contribute to abundant NS expression in the undifferentiated cells. OCT3/4 deficiency in teratomas led to loss of NS expression, resulting in growth retardation. Finally, we found that teratomas deficient in NS lost their undifferentiated characteristics, resulting in defective tumor proliferation. These data indicate that abundant expression of NS supports the undifferentiated properties of germ cell tumors.
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Affiliation(s)
- Noriyuki Uema
- Division of Molecular Genetics, Cancer and Stem Cell Program, Cancer Research Institute, Kanazawa University, Kanazawa, Japan
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Nucleostemin deletion reveals an essential mechanism that maintains the genomic stability of stem and progenitor cells. Proc Natl Acad Sci U S A 2013; 110:11415-20. [PMID: 23798389 DOI: 10.1073/pnas.1301672110] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Stem and progenitor cells maintain a robust DNA replication program during the tissue expansion phase of embryogenesis. The unique mechanism that protects them from the increased risk of replication-induced DNA damage, and hence permits self-renewal, remains unclear. To determine whether the genome integrity of stem/progenitor cells is safeguarded by mechanisms involving molecules beyond the core DNA repair machinery, we created a nucleostemin (a stem and cancer cell-enriched protein) conditional-null allele and showed that neural-specific knockout of nucleostemin predisposes embryos to spontaneous DNA damage that leads to severe brain defects in vivo. In cultured neural stem cells, depletion of nucleostemin triggers replication-dependent DNA damage and perturbs self-renewal, whereas overexpression of nucleostemin shows a protective effect against hydroxyurea-induced DNA damage. Mechanistic studies performed in mouse embryonic fibroblast cells showed that loss of nucleostemin triggers DNA damage and growth arrest independently of the p53 status or rRNA synthesis. Instead, nucleostemin is directly recruited to DNA damage sites and regulates the recruitment of the core repair protein, RAD51, to hydroxyurea-induced foci. This work establishes the primary function of nucleostemin in maintaining the genomic stability of actively dividing stem/progenitor cells by promoting the recruitment of RAD51 to stalled replication-induced DNA damage foci.
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40
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PML-mediated signaling and its role in cancer stem cells. Oncogene 2013; 33:1475-84. [PMID: 23563177 DOI: 10.1038/onc.2013.111] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 02/06/2013] [Accepted: 02/09/2013] [Indexed: 02/08/2023]
Abstract
The promyelocytic leukemia (PML) protein, initially discovered as a part of the PML/retinoic acid receptor alpha fusion protein, has been found to be a critical player in oncogenesis and tumor progression. Multiple cellular activities, including DNA repair, alternative lengthening of telomeres, transcriptional control, apoptosis and senescence, are regulated by PML and its featured subcellular structure, the PML nuclear body. In correspondence with its role in many important life processes, PML mediates several complex downstream signaling pathways. The determinant function of PML in tumorigenesis and cancer progression raises the interest in its involvement in cancer stem cells (CSCs), a subpopulation of cancer cells that share properties with stem cells and are critical for tumor propagation. Recently, there are exciting discoveries concerning the requirement of PML in CSC maintenance. Growing evidences strongly suggest a positive role of PML in regulating CSCs in both hematopoietic cancers and solid tumors, whereas the underlying mechanisms may be different and remain elusive. Here we summarize and discuss the PML-mediated signaling pathways in cancers and their potential roles in regulating CSCs.
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A new level of protection. Nat Rev Mol Cell Biol 2012. [DOI: 10.1038/nrm3388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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