Télomères et Cancer

Publications de l’équipe

Année de publication : 2015

Luis Jaime Castro-Vega, Karina Jouravleva, Paola Ortiz-Montero, Win-Yan Liu, Jorge Luis Galeano, Martha Romero, Tatiana Popova, Silvia Bacchetti, Jean Paul Vernot, Arturo Londoño-Vallejo (2015 Jul 15)

The senescent microenvironment promotes the emergence of heterogeneous cancer stem-like cells.

Carcinogenesis : 1180-92 : DOI : 10.1093/carcin/bgv101 En savoir plus
Résumé

There is a well-established association between aging and the onset of metastasis. Although the mechanisms through which age impinges upon the malignant phenotype remain uncharacterized, the role of a senescent microenvironment has been emphasized. We reported previously that human epithelial cells that undergo telomere-driven chromosome instability (T-CIN) display global microRNA (miR) deregulation and develop migration and invasion capacities. Here, we show that post-crisis cells are not able to form tumors unless a senescent microenvironment is provided. The characterization of cell lines established from such tumors revealed that these cells have acquired cell autonomous tumorigenicity, giving rise to heterogeneous tumors. Further experiments demonstrate that explanted cells, while displaying differences in cell differentiation markers, are all endowed of enhanced stem cell properties including self-renewal and multilineage differentiation capacity. Treatments of T-CIN+ cells with senescence-conditioned media induce sphere formation exclusively in cells with senescence-associated tumorigenicity, a capacity that depends on miR-145 repression. These results indicate that the senescent microenvironment, while promoting further transdifferentiations in cells with genome instability, is able to propel the progression of premalignant cells towards a malignant, cell stem-like state.

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S Jacquin, V Rincheval, B Mignotte, S Richard, M Humbert, O Mercier, A Londoño-Vallejo, E Fadel, S Eddahibi (2015 Jun 30)

Inactivation of p53 Is Sufficient to Induce Development of Pulmonary Hypertension in Rats.

PloS one : e0131940 : DOI : 10.1371/journal.pone.0131940 En savoir plus
Résumé

Pulmonary artery smooth muscle cells (PA-SMCs) in pulmonary arterial hypertension (PAH) show similarities to cancer cells. Due to the growth-suppressive and pro-apoptotic effects of p53 and its inactivation in cancer, we hypothesized that the p53 pathway could be altered in PAH. We therefore explored the involvement of p53 in the monocrotaline (MCT) rat model of pulmonary hypertension (PH) and the pathophysiological consequences of p53 inactivation in response to animal treatment with pifithrin-α (PFT, an inhibitor of p53 activity).

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Delphine Trochet, Xénia Mergui, Ivana Ivkovic, Rosa Maria Porreca, Michèle Gerbault-Seureau, Assitan Sidibe, Florence Richard, Arturo Londono-Vallejo, Martine Perret, Fabienne Aujard, Jean-François Riou (2015 Apr 18)

Telomere regulation during ageing and tumorigenesis of the grey mouse lemur.

Biochimie : 100-10 : DOI : 10.1016/j.biochi.2015.04.002 En savoir plus
Résumé

Telomere erosion leading to replicative senescence has been well documented in human and anthropoid primates, and provides a clue against tumorigenesis. In contrast, other mammals, such as laboratory mice, with short lifespan and low body weight mass have different telomere biology without replicative senescence. We analyzed telomere biology in the grey mouse lemur, a small prosimian model with a relative long lifespan currently used in ageing research. We report an average telomere length by telomere restriction fragment (TRF) among the longest reported so far for a primate species (25-30 kb), but without detectable overall telomere shortening with ageing on blood samples. However, we demonstrate using universal STELA (Single Telomere Length Amplification) the existence of short telomeres, the increase of which, while correlating with ageing might be related to another mechanism than replicative senescence. We also found a low stringency of telomerase restriction in tissues and an ease to immortalize fibroblasts in vitro upon spontaneous telomerase activation. Finally, we describe the first grey mouse lemur cancer cell line showing a dramatic telomere shortening and high telomerase activity associated with polyploidy. Our overall results suggest that telomere biology in grey mouse lemur is an exception among primates, with at best a physiologically limited replicative telomere ageing and closest to that observed in small rodents.

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Stéphane Terry, Nathalie Nicolaiew, Victor Basset, Fannie Semprez, Pascale Soyeux, Pascale Maillé, Francis Vacherot, Guillaume Ploussard, Arturo Londoño-Vallejo, Alexandre de la Taille, Yves Allory (2015 Feb 3)

Clinical value of ERG, TFF3, and SPINK1 for molecular subtyping of prostate cancer.

Cancer : 1422-30 : DOI : 10.1002/cncr.29233 En savoir plus
Résumé

In view of the marked molecular heterogeneity of prostate cancer (PCa), clinical and pathologic parameters alone may be unreliable for predicting disease outcomes after surgical intervention. The development of biomarkers may be helpful to estimate tumor heterogeneity and stratify patients in terms of their risk of progression. Levels of v-ets avian erythroblastosis virus E26 oncogene homolog (ERG), trefoil factor 3 (TFF3), and serine peptidase inhibitor, Kazal type 1 (SPINK1) are commonly elevated in PCa, but it is unclear whether the evaluation of these 3 markers can help to discriminate patients who will have different clinical outcomes. The authors investigated whether assessment of ERG, TFF3, and SPINK1 expression could help to define clinically relevant, distinct subsets of patients with PCa.

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Michael Schertzer, Karina Jouravleva, Mylene Perderiset, Florent Dingli, Damarys Loew, Tangui Le Guen, Barbara Bardoni, Jean-Pierre de Villartay, Patrick Revy, Arturo Londoño-Vallejo (2015 Jan 27)

Human regulator of telomere elongation helicase 1 (RTEL1) is required for the nuclear and cytoplasmic trafficking of pre-U2 RNA.

Nucleic acids research : 1834-47 : DOI : 10.1093/nar/gku1402 En savoir plus
Résumé

Hoyeraal-Hreidarsson syndrome (HHS) is a severe form of Dyskeratosis congenita characterized by developmental defects, bone marrow failure and immunodeficiency and has been associated with telomere dysfunction. Recently, mutations in Regulator of Telomere ELongation helicase 1 (RTEL1), a helicase first identified in Mus musculus as being responsible for the maintenance of long telomeres, have been identified in several HHS patients. Here we show that RTEL1 is required for the export and the correct cytoplasmic trafficking of the small nuclear (sn) RNA pre-U2, a component of the major spliceosome complex. RTEL1-HHS cells show abnormal subcellular partitioning of pre-U2, defects in the recycling of ribonucleotide proteins (RNP) in the cytoplasm and splicing defects. While most of these phenotypes can be suppressed by re-expressing the wild-type protein in RTEL1-HHS cells, expression of RTEL1 mutated variants in immortalized cells provokes cytoplasmic mislocalizations of pre-U2 and other RNP components, as well as splicing defects, thus phenocopying RTEL1-HHS cellular defects. Strikingly, expression of a cytoplasmic form of RTEL1 is sufficient to correct RNP mislocalizations both in RTEL1-HHS cells and in cells expressing nuclear mutated forms of RTEL1. This work unravels completely unanticipated roles for RTEL1 in RNP trafficking and strongly suggests that defects in RNP biogenesis pathways contribute to the pathology of HHS.

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Année de publication : 2014

Adélaïde Saint-Léger, Melanie Koelblen, Livia Civitelli, Amadou Bah, Nadir Djerbi, Marie-Josèphe Giraud-Panis, Arturo Londoño-Vallejo, Fiorentina Ascenzioni, Eric Gilson (2014 Dec 9)

The basic N-terminal domain of TRF2 limits recombination endonuclease action at human telomeres.

Cell cycle (Georgetown, Tex.) : 2469-74 : DOI : 10.4161/cc.29422 En savoir plus
Résumé

The stability of mammalian telomeres depends upon TRF2, which prevents inappropriate repair and checkpoint activation. By using a plasmid integration assay in yeasts carrying humanized telomeres, we demonstrated that TRF2 possesses the intrinsic property to both stimulate initial homologous recombination events and to prevent their resolution via its basic N-terminal domain. In human cells, we further showed that this TRF2 domain prevents telomere shortening mediated by the resolvase-associated protein SLX4 as well as GEN1 and MUS81, 2 different types of endonucleases with resolvase activities. We propose that various types of resolvase activities are kept in check by the basic N-terminal domain of TRF2 in order to favor an accurate repair of the stalled forks that occur during telomere replication.

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Karla Perez-Toralla, Guillaume Mottet, Ezgi Tulukcuoglu Guneri, Jérôme Champ, François-Clément Bidard, Jean-Yves Pierga, Jerzy Klijanienko, Irena Draskovic, Laurent Malaquin, Jean-Louis Viovy, Stéphanie Descroix (2014 Dec 5)

FISH in chips: turning microfluidic fluorescence in situ hybridization into a quantitative and clinically reliable molecular diagnosis tool.

Lab on a chip : 811-22 : DOI : 10.1039/c4lc01059k En savoir plus
Résumé

Microfluidic systems bear promise to provide new powerful tools for the molecular characterization of cancer cells, in particular for the routine detection of multiple cancer biomarkers using a minute amount of the sample. However, taking miniaturized cell-based assays into the clinics requires the implementation and validation of complex biological protocols on chip, as well as the development of disposable microdevices produced at a low cost. Based on a recently developed microfluidic chip made of Cyclic Olefin Copolymer for cell immobilization with minimal dead volume and controlled shear stress, we developed a protocol performed entirely in the liquid phase, allowing the immobilization and fixation of cells and their quantitative characterization by fluorescence in situ hybridization. We demonstrated first in cell lines and then in two clinical case studies the potential of this method to perform quantitative copy number measurement and clinical scoring of the amplification of the ERBB2 gene, a decisive biomarker for the prescription of HER2+ related targeted therapies. This validation was performed in a blind protocol in two clinical case studies, in reference to the gold standard and clinically used method based on glass slides. We obtained a comparable reproducibility and a minor difference in apparent amplification, which can be corrected by internal calibration. The method thus reaches the standard of robustness needed for clinical use. The protocol can be fully automated, and its consumption of samples and DNA probes is reduced as compared to glass slide protocols by a factor of at least 10. The total duration of the assay is divided by two.

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Stéphane Terry, Ihsan Y El-Sayed, Damien Destouches, Pascale Maillé, Nathalie Nicolaiew, Guillaume Ploussard, Fannie Semprez, Cynthia Pimpie, Himisha Beltran, Arturo Londono-Vallejo, Yves Allory, Alexandre de la Taille, David S Salomon, Francis Vacherot (2014 Aug 15)

CRIPTO overexpression promotes mesenchymal differentiation in prostate carcinoma cells through parallel regulation of AKT and FGFR activities.

Oncotarget : 11994-2008 En savoir plus
Résumé

Members of the EGF-CFC (Cripto, FRL-1, Cryptic) protein family are increasingly recognized as key mediators of cell movement and cell differentiation during vertebrate embryogenesis. The founding member of this protein family, CRIPTO, is overexpressed in various human carcinomas. Yet, the biological role of CRIPTO in this setting remains unclear. Here, we find CRIPTO expression as especially high in a subgroup of primary prostate carcinomas with poorer outcome, wherein resides cancer cell clones with mesenchymal traits. Experimental studies in PCa models showed that one notable function of CRIPTO expression in prostate carcinoma cells may be to augment PI3K/AKT and FGFR1 signaling, which promotes epithelial-mesenchymal transition and sustains a mesenchymal state. In the observed signaling events, FGFR1 appears to function parallel to AKT, and the two pathways act cooperatively to enhance migratory, invasive and transformation properties specifically in the CRIPTO overexpressing cells. Collectively, these findings suggest a novel molecular network, involving CRIPTO, AKT, and FGFR signaling, in favor of the emergence of mesenchymal-like cancer cells during the development of aggressive prostate tumors.

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Irena Draskovic, Arturo Londono-Vallejo (2014 Jul 1)

Telomere recombination and the ALT pathway: a therapeutic perspective for cancer.

Current pharmaceutical design : 6466-71 En savoir plus
Résumé

Telomeres are essential for cell proliferation and tumor cell immortalization requires the presence of a telomere maintenance mechanism. Thus, interfering with this mechanism constitutes a potential means to impede cell proliferation and tumor progression. Many cancer cells rely on telomerase activity to ensure indefinite proliferation capacity and developing therapeutic approaches that target telomerase has attracted much attention in the last couple of decades. Nevertheless, a non-negligible proportion of tumors utilize telomerase- independent, alternative mechanisms to lengthen telomeres (ALT). Here we briefly discuss both our current understanding of ALT mechanisms and the potential to develop a therapeutic approach targeting ALT.

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N S Zhdanova, I Draskovic, J M Minina, T V Karamysheva, C L Novo, W-Y Liu, R M Porreca, A Gibaud, M E Zvereva, D A Skvortsov, N B Rubtsov, A Londoño-Vallejo (2014 May 21)

Recombinogenic telomeres in diploid Sorex granarius (Soricidae, Eulipotyphla) fibroblast cells.

Molecular and cellular biology : 2786-99 : DOI : 10.1128/MCB.01697-13 En savoir plus
Résumé

The telomere structure in the Iberian shrew Sorex granarius is characterized by unique, striking features, with short arms of acrocentric chromosomes carrying extremely long telomeres (up to 300 kb) with interspersed ribosomal DNA (rDNA) repeat blocks. In this work, we investigated the telomere physiology of S. granarius fibroblast cells and found that telomere repeats are transcribed on both strands and that there is no telomere-dependent senescence mechanism. Although telomerase activity is detectable throughout cell culture and appears to act on both short and long telomeres, we also discovered that signatures of a recombinogenic activity are omnipresent, including telomere-sister chromatid exchanges, formation of alternative lengthening of telomeres (ALT)-associated PML-like bodies, production of telomere circles, and a high frequency of telomeres carrying marks of a DNA damage response. Our results suggest that recombination participates in the maintenance of the very long telomeres in normal S. granarius fibroblasts. We discuss the possible interplay between the interspersed telomere and rDNA repeats in the stabilization of the very long telomeres in this organism.

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Maya Jeitany, Jose Ramon Pineda, Qingyuan Liu, Rosa Maria Porreca, Françoise Hoffschir, Chantal Desmaze, David C Silvestre, Patrick Mailliet, Marie-Pierre Junier, Arturo Londoño-Vallejo, Evelyne Ségal-Bendirdjian, Hervé Chneiweiss, François D Boussin (2014 Apr 30)

A preclinical mouse model of glioma with an alternative mechanism of telomere maintenance (ALT).

International journal of cancer : 1546-58 : DOI : 10.1002/ijc.29171 En savoir plus
Résumé

Glioblastoma multiforme is the most aggressive primary tumor of the central nervous system. Glioma stem cells (GSCs), a small population of tumor cells with stem-like properties, are supposedly responsible for glioblastoma multiforme relapse after current therapies. In approximately thirty percent of glioblastoma multiforme tumors, telomeres are not maintained by telomerase but through an alternative mechanism, termed alternative lengthening of telomere (ALT), suggesting potential interest in developing specific therapeutic strategies. However, no preclinical model of ALT glioma was available until the isolation of TG20 cells from a human ALT glioma. Herein, we show that TG20 cells exhibit a high level of telomeric recombination but a stable karyotype, indicating that their telomeres retain their protective function against chromosomal instability. TG20 cells possess all of the characteristic features of GSCs: the expression of neural stem cell markers, the generation of intracerebral tumors in NOD-SCID-IL2Rγ (NSG) mice as well as in nude mice, and the ability to sustain serial intracerebral transplantations without expressing telomerase, demonstrating the stability of the ALT phenotype in vivo. Furthermore, we also demonstrate that 360B, a G-quadruplex ligand of the pyridine derivative series that impairs telomere replication and mitotic progression in cancer cells, prevents the development of TG20 tumors. Together, our results show that intracerebral grafts of TG20 cells in immunodeficient mice constitute an efficient preclinical model of ALT glioblastoma multiforme and that G-quadruplex ligands are a potential therapy for this specific type of tumor.

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Harikleia Episkopou, Irena Draskovic, Amandine Van Beneden, Gaëlle Tilman, Marina Mattiussi, Matthieu Gobin, Nausica Arnoult, Arturo Londoño-Vallejo, Anabelle Decottignies (2014 Feb 5)

Alternative Lengthening of Telomeres is characterized by reduced compaction of telomeric chromatin.

Nucleic acids research : 4391-405 : DOI : 10.1093/nar/gku114 En savoir plus
Résumé

Proper telomeric chromatin configuration is thought to be essential for telomere homeostasis and stability. Previous studies in mouse suggested that loss of heterochromatin marks at telomeres might favor onset of Alternative Lengthening of Telomeres (ALT) pathway, by promoting homologous recombination. However, analysis of chromatin status at human ALT telomeres has never been reported. Here, using isogenic human cell lines and cellular hybrids, which rely either on telomerase or ALT to maintain telomeres, we show that chromatin compaction is reduced at ALT telomeres and this is associated with a global decrease in telomeric H3K9me3. This, subsequently, leads to upregulation of telomere transcription. Accordingly, restoration of a more condensed telomeric chromatin through telomerase-dependent elongation of short ALT telomeres reduces telomere transcription. We further show that loss of ATRX chromatin remodeler function, a frequent characteristic of ALT cells, is not sufficient to decrease chromatin condensation at telomeres nor to increase the expression of telomeric RNA species. These results offer new insight on telomeric chromatin properties in ALT cells and support the hypothesis that telomeric chromatin decondensation is important for ALT pathway.

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Année de publication : 2013

Tangui Le Guen, Laurent Jullien, Mike Schertzer, Axelle Lefebvre, Laetitia Kermasson, Jean-Pierre de Villartay, Arturo Londoño-Vallejo, Patrick Revy (2013 Dec 21)

[RTEL1 (regulator of telomere elongation helicase 1), a DNA helicase essential for genome stability].

Médecine sciences : M/S : 1138-44 : DOI : 10.1051/medsci/20132912018 En savoir plus
Résumé

RTEL1 (regulator of telomere length helicase 1) is a DNA helicase that has been identified more than 10 years ago. Many works since, mainly in the nematode Caenorhabditis elegans and the mouse, have highlighted its role in chromosomal stability, maintenance of telomere length, and DNA repair. Recently, four laboratories have characterized RTEL1 mutations in patients with dyskeratosis congenita (DC) and Hoyeraal-Hreidarsson (HH) syndrome, a rare and severe variant of DC. We here summarize the current knowledge on RTEL1 and discuss the possible other functions that RTEL1 could play.

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Guilhem Faure, Patrick Revy, Michael Schertzer, Arturo Londono-Vallejo, Isabelle Callebaut (2013 Oct 17)

The C-terminal extension of human RTEL1, mutated in Hoyeraal-Hreidarsson syndrome, contains harmonin-N-like domains.

Proteins : 897-903 : DOI : 10.1002/prot.24438 En savoir plus
Résumé

Several studies have recently shown that germline mutations in RTEL1, an essential DNA helicase involved in telomere regulation and DNA repair, cause Hoyeraal-Hreidarsson syndrome (HHS), a severe form of dyskeratosis congenita. Using original new softwares, facilitating the delineation of the different domains of the protein and the identification of remote relationships for orphan domains, we outline here that the C-terminal extension of RTEL1, downstream of its catalytic domain and including several HHS-associated mutations, contains a yet unidentified tandem of harmonin-N-like domains, which may serve as a hub for partner interaction. This finding highlights the potential critical role of this region for the function of RTEL1 and gives insights into the impact that the identified mutations would have on the structure and function of these domains.

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Zhong Deng, Galina Glousker, Aliah Molczan, Alan J Fox, Noa Lamm, Jayaraju Dheekollu, Orr-El Weizman, Michael Schertzer, Zhuo Wang, Olga Vladimirova, Jonathan Schug, Memet Aker, Arturo Londoño-Vallejo, Klaus H Kaestner, Paul M Lieberman, Yehuda Tzfati (2013 Aug 21)

Inherited mutations in the helicase RTEL1 cause telomere dysfunction and Hoyeraal-Hreidarsson syndrome.

Proceedings of the National Academy of Sciences of the United States of America : E3408-16 : DOI : 10.1073/pnas.1300600110 En savoir plus
Résumé

Telomeres repress the DNA damage response at the natural chromosome ends to prevent cell-cycle arrest and maintain genome stability. Telomeres are elongated by telomerase in a tightly regulated manner to ensure a sufficient number of cell divisions throughout life, yet prevent unlimited cell division and cancer development. Hoyeraal-Hreidarsson syndrome (HHS) is characterized by accelerated telomere shortening and a broad range of pathologies, including bone marrow failure, immunodeficiency, and developmental defects. HHS-causing mutations have previously been found in telomerase and the shelterin component telomeric repeat binding factor 1 (TRF1)-interacting nuclear factor 2 (TIN2). We identified by whole-genome exome sequencing compound heterozygous mutations in four siblings affected with HHS, in the gene encoding the regulator of telomere elongation helicase 1 (RTEL1). Rtel1 was identified in mouse by its genetic association with telomere length. However, its mechanism of action and whether it regulates telomere length in human remained unknown. Lymphoblastoid cell lines obtained from a patient and from the healthy parents carrying heterozygous RTEL1 mutations displayed telomere shortening, fragility and fusion, and growth defects in culture. Ectopic expression of WT RTEL1 suppressed the telomere shortening and growth defect, confirming the causal role of the RTEL1 mutations in HHS and demonstrating the essential function of human RTEL1 in telomere protection and elongation. Finally, we show that human RTEL1 interacts with the shelterin protein TRF1, providing a potential recruitment mechanism of RTEL1 to telomeres.

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