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  • 1
    In: Blood, American Society of Hematology, Vol. 125, No. 13 ( 2015-03-26), p. 2101-2110
    Abstract: LMP1 expression in post germinal center B cells results in downregulation of shelterin proteins, telomeric aggregates, and multinuclearity. LMP1 targets TRF1, TRF2, and POT1 reversibly at the transcriptional/translational level, and TRF2 is essential to block multinuclearity.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2015
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  • 2
    In: BMC Cell Biology, Springer Science and Business Media LLC, Vol. 11, No. 1 ( 2010-12)
    Type of Medium: Online Resource
    ISSN: 1471-2121
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2010
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  • 3
    Online Resource
    Online Resource
    American Society of Hematology ; 2010
    In:  Blood Vol. 116, No. 21 ( 2010-11-19), p. 745-745
    In: Blood, American Society of Hematology, Vol. 116, No. 21 ( 2010-11-19), p. 745-745
    Abstract: Abstract 745 Introduction: Innovative 3D telomere q-FISH allows a mechanistic understanding of the transition from the mononuclear Hodgkin (H) to the multinuclear Reed-Sternberg (RS) cell in in Hodgkin's lymphoma (HL) derived cell lines and diagnostic patient biopsies (Leukemia. 2009; 23:565-573). In RS-cells the telomere protecting shelterin complex appears to be disrupted and deregulation of DNA repair mechanisms is observed. These changes occur in both, classical EBV negative and EBV-associated, LMP1 expressing HL (Lab Invest. 2010; 90:611-619). However, it is not known whether the 3D telomere profile at diagnostic biopsy is different in patients entering rapid remission after initiation of standard chemotherapy (ABVD) compared to that-one of patients with relapsing or refractory disease. In order to answer this question we analyzed by 3D telomere q-FISH diagnostic biopsies of HL patients entering rapid complete remission and compared them to diagnostic biopsies of patients with relapsing or refractory disease. Patients and methods: Rapid remission group (after 1–4 cycles of ABVD): 7 diagnostic biopsies of 7 patients, 19–57 years old, 5 male, 3 LMP1 expressing, 4 nodular sclerosis subtype, 3 mixed cellularity subtype, stages IA, IIA, IIIA × 2, IIIB x2, IVA. Relapse group: 7 diagnostic biopsies of 4 patients, 40–77 years old, 2 male, 1 LMP1 expressing, 3 nodular sclerosis subtype, 1 mixed cellularity subtype, stages IIA bulky, IIIB × 2, IVB; first remission after 6–8 cycles of ABVD in 3 patients, 1 patient died from progressive disease after 11 months. 3D telomere q-FISH was performed as described (Lab Invest. 2010; 90:611-619) and statistical analysis was performed using nested or two-way analysis of variance. Results: Bi- or multinuclear RS-cells of all patients from both groups showed a significant increase of very short telomeres and telomere aggregates when compared to the mononuclear precursor H-cells. However, most importantly, all diagnostic biopsies of the relapse group contained a very high percentage of very small telomeres, including so-called “t-stumps”, in both, H-cells (76,8 ± 11,8%) and RS-cells (87,9 ± 7,3%). Compared to the percentage of very small telomeres identified in both, H-cells (33,7 ± 9,4%) and RS-cells (54,6 ± 15,0%) of the rapid remission group, this increase is highly significant (p 〈 0.001). Moreover, analogous findings are observed for the number of telomere aggregates. In the relapse group the average numbers of telomere aggregates per cell were 4,3 ± 2,4 aggregates per H-cell and 5,4 ± 3.0 aggregates per RS-cell, compared to 1,2 ± 0,7 aggregates per H-cell and 3,3 ± 1,1 aggregates per RS-cell in the rapid remission group. Discussion: The 3D nuclear telomere organization of H- and RS- cells in diagnostic biopsies of relapsing or refractory HL is characterized by both, H- and RS-cells with abundant “t-stumps” and numerous telomere aggregates. Very short telomeres, including t-stumps, and telomere aggregates, both, are characteristics of aggressiveness in cancer biology (Mol Cell. 2007;28:315-327; J Cell Biochem. 2010; 109:1095-1102). Thus, H- and RS-cells of refractory or relapsing HL show significant differences in the 3D telomere dynamics already at first, diagnostic biopsy when compared to H- and RS-cells of HL entering rapid remissions. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2010
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  • 4
    In: Laboratory Investigation, Elsevier BV, Vol. 90, No. 4 ( 2010-04), p. 611-619
    Type of Medium: Online Resource
    ISSN: 0023-6837
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    Language: English
    Publisher: Elsevier BV
    Publication Date: 2010
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  • 5
    In: Translational Oncology, Elsevier BV, Vol. 5, No. 4 ( 2012-08), p. 269-277
    Type of Medium: Online Resource
    ISSN: 1936-5233
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2012
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  • 6
    In: Blood, American Society of Hematology, Vol. 116, No. 21 ( 2010-11-19), p. 3625-3625
    Abstract: Abstract 3625 Introduction: Tumour cells in classical Hodgkin's lymphoma (HL) and Burkitt's lymphoma (BL) are derived from germinal center B-cells and may or may not harbour the EBV genome. In both, EBV-negative and EBV-associated HL, the 3D nuclear organization of telomeres marks the transition from mononuclear Hodgkin (H-cell) to diagnostic multinuclear Reed-Sternberg (RS-cell) cells. Moreover, transient expression of the EBV-encoded oncoprotein LMP1 in the HL cell lines L-428 and HD-MyZ significantly increases the percentage of RS cells. However, the molecular mechanisms through which this selective LMP1 oncoprotein expression promotes the transition from H- to RS-cells is still unknown. In order to answer this question we analyzed the 3D telomere dynamics and the expression of key shelterin proteins at the transcriptional, translational and topographical localization level in the EBV-negative Burkitt cell line BJAB, stably transfected with an inducible LMP1 system (tetracycline on/off system). To mimic the permanent LMP1 expression as observed in tumour cells of EBV-associated Hodgkin's lymphoma, we extended the period of LMP1 expression up to 21 days and examined key proteins of the shelterin complex, 3D telomere dynamics and formation of multinuclear cells in interphase nuclei of BJAB Burkitt's lymphoma cells at day 1, 3, 7, 10, 14 and 21. Statistical analysis was performed using nested or two-way analysis of variance. Results: Already at day 3 LMP1 induced substantial down regulation of the shelterin key-components TRF1, TRF2 and POT1 at the transcriptional and protein level. This down regulation was reversible after LMP1 suppression; in particular, suppression of LMP1 induction at day 7 returned shelterin-key components to the initial level of expression at day 14. Massive LMP1 mediated down regulation of shelterin proteins was also confirmed by immunofluorescence. At day 7, stable LMP1 expression led to a significant increase of 3D telomere aggregates, nuclear volume and polyploid cells, most of them multinucleated, when compared to non-LMP1 expressing BJAB controls (p 〈 0.02). These changes progressed over time and at day 21 LMP1 expressing BJAB cells were characterized by highly significant increase of 3D telomere aggregates (p = 0.0005) and increased nuclear volume (p 〈 0.0001), compared to the LMP1-suppressed control. Discussion: In an experimental setting mimicking the in vivo conditions of EBV-associated HL, i.e. a permanent LMP1 expression in the H-cells, the LMP1 oncoprotein deregulates shelterin-expression, leads to telomere aggregates and mediates multinuclearity. Our findings point to a shelterin/telomere related key function of LMP1 in Reed-Sternberg cell formation in EBV-associated Hodgkin's lymphoma and may explain the four fold increased risk to develop HL within a median incubation time of four years after symptomatic EBV infection. The LMP1-dependent mechanisms involved are probably unprotected telomeres (shelterin down regulation) favouring chromosomal rearrangements as a result of telomeric aggregate formation and ongoing bridge-fusion- bridge cycles which lead to disturbed cytokinesis and finally multinuclearity. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2010
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  • 7
    In: Gynecologic Oncology, Elsevier BV, Vol. 161, No. 3 ( 2021-06), p. 769-778
    Type of Medium: Online Resource
    ISSN: 0090-8258
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
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  • 8
    In: Cancers, MDPI AG, Vol. 12, No. 3 ( 2020-02-25), p. 531-
    Abstract: Chromosome instability (CIN), or progressive changes in chromosome numbers, is an enabling feature of many cancers; however, the mechanisms giving rise to CIN remain poorly understood. To expand our mechanistic understanding of the molecular determinants of CIN in humans, we employed a cross-species approach to identify 164 human candidates to screen. Using quantitative imaging microscopy (QuantIM), we show that silencing 148 genes resulted in significant changes in CIN-associated phenotypes in two distinct cellular contexts. Ten genes were prioritized for validation based on cancer patient datasets revealing frequent gene copy number losses and associations with worse patient outcomes. QuantIM determined silencing of each gene-induced CIN, identifying novel roles for each as chromosome stability genes. SKP1 was selected for in-depth analyses as it forms part of SCF (SKP1, CUL1, FBox) complex, an E3 ubiquitin ligase that targets proteins for proteolytic degradation. Remarkably, SKP1 silencing induced increases in replication stress, DNA double strand breaks and chromothriptic events that were ascribed to aberrant increases in Cyclin E1 levels arising from reduced SKP1 expression. Collectively, these data reveal a high degree of evolutionary conservation between human and budding yeast CIN genes and further identify aberrant mechanisms associated with increases in chromothriptic events.
    Type of Medium: Online Resource
    ISSN: 2072-6694
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
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  • 9
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2016
    In:  Cancer Research Vol. 76, No. 14_Supplement ( 2016-07-15), p. 3585-3585
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 76, No. 14_Supplement ( 2016-07-15), p. 3585-3585
    Abstract: Chromosome Instability (CIN) is defined as an increase in the rate at which whole chromosomes or large parts are gained or lost. CIN is not only associated with virtually all tumor types, but it is associated with aggressive tumors, the acquisition of multi-drug resistance and consequently poor patient prognosis. Despite these associations, the genes and molecular defects that contribute to CIN are only poorly understood. Recently, we performed a high content screen that identified KIF11, a microtubule associated motor protein, as a candidate CIN gene. Here, we couple RNAi-based gene silencing with biochemistry and cell biology to show that diminished KIF11 expression and/or function induce CIN. HCT116 cells were employed, as they are a karyotypically stable colorectal cancer cell line of epithelial origin that has been used for similar CIN studies. KIF11 was either silenced (both individual and pooled siRNA duplexes) or inhibited (Monostrol) and expression levels were determined by Western blots. To determine whether KIF11 silencing or inhibition affects DNA content, two phenotypes frequently associated with CIN, namely increases in nuclear area and micronucleus formation were evaluated. Fluorescence microscopy was employed on DAPI-counterstained samples and revealed statistically significant increases both nuclear area and micronucleus formation following KIF11 silencing and inhibition relative to controls. Next, flow cytometry was performed on propidium iodide labeled samples to assess whether increases in DNA content were associated with the changes in nuclear area. As predicted, increases in the proportion of cells with & gt;G2/M DNA content occurred within the KIF11 silenced populations. Finally, mitotic chromosome spreads were generated and chromosomes were manually enumerated from 100 spreads per condition/control. Subsequent Kolmogorov-Smirnov tests identified statistically significant increases in the cumulative distribution frequencies of mitotic chromosome numbers within the spreads generated from the KIF11 silenced cells relative to controls. To extend our findings beyond the colorectal cancer cell context employed above, analogous studies were performed in hTERT cells (karyotypically stable fibroblast cell line) with very similar results. Collectively, these data indicate that KIF11 expression and function are normally required to maintain genome integrity. They further suggest that the loss of KIF11 expression and/or function may be a contributing factor in the etiology of tumorigenesis in colorectal cancer and perhaps other tumor types as well. Citation Format: Yasamin Asbaghi, Zelda Lichtensztejn, Laura Thompson, Kirk McManus. KIF11 silencing or inhibition induces chromosome instability. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3585.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2016
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  • 10
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2020
    In:  Clinical Cancer Research Vol. 26, No. 13_Supplement ( 2020-07-01), p. A20-A20
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 26, No. 13_Supplement ( 2020-07-01), p. A20-A20
    Abstract: High-grade serous ovarian cancer (HGSOC) is the most aggressive epithelial ovarian cancer subtype, and & gt;75% of patients experience tumor recurrence following initial treatment, often with drug-resistant disease. Unfortunately, the aberrant events driving tumor progression, recurrence, and multidrug resistance in HGSOC remain largely unknown. Chromosome instability (CIN) is defined as an increased rate at which whole chromosomes (or large fragments) are gained or lost, and in many cancer types CIN is associated with tumor initiation, disease recurrence, multidrug resistance, and poor patient prognosis. Conceptually, the ongoing chromosome changes associated with CIN promote the production of genetically distinct daughter cells and drive cell-to-cell heterogeneity. As CIN remains largely unstudied in HGSOC, we now seek to characterize the prevalence and dynamics of CIN in chemonaïve, chemosensitive, and chemoresistant HGSOC patient samples, including samples isolated from ascites (metastatic cells) and solid tumors (primary tumor). Using single-cell quantitative imaging techniques, we evaluated CIN by assessing CIN phenotypes, including changes in nuclear areas and chromosome numbers. Changes in nuclear areas and increases in cell-to-cell heterogeneity are suggestive of CIN. Next, we employed fluorescence in situ hybridization and chromosome enumeration probes (CEPs) recognizing pericentric regions of chromosomes 8, 11, and 17 to quantify changes in chromosome numbers. Deviations from the expected number of two CEP foci/chromosome/nucleus (i.e., diploid state) are indicative of CIN. CEP specificity was validated within diploid and aneuploid fallopian tube (FT) secretory epithelial cell lines, a cell type of origin for HGSOC. The diploid FT cell lines show two CEPs/chromosome/nucleus and the aneuploid FT cell lines show an aberrant number of CEPs/chromosome/nucleus. CEPs are now being employed in HGSOC ascites samples and solid tumors within a HGSOC tissue microarray. Preliminary data show that nuclear areas and CEP numbers are heterogeneous and dynamic over time. More specifically, our data show CIN is highly prevalent in HGSOC cells isolated from ascites, increases with disease progression and drug resistance, and decreases in response to treatment. Additionally, we show that solid tumor samples (primary tumor) typically contain more frequent gains and/or losses in CEP foci (i.e., higher level of CIN) compared to the ascites samples (metastatic cells). Importantly, characterizing the prevalence of CIN in HGSOC will help researchers understand the association between CIN and tumor development, progression, response, and acquisition of drug resistance. Citation Format: Claire Morden, Ally Farrell, Mirka Sliwowski, Zelda Lichtensztejn, Mark Nachtigal, Kirk McManus. Characterizing chromosome instability in chemonaïve, chemosensitive, and chemoresistant high-grade serous ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A20.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2020
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