1
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Discovery proteomics defines androgen-regulated glycoprotein networks in prostate cancer cells, as well as putative biomarkers of prostatic diseases. Sci Rep 2021; 11:22208. [PMID: 34782677 PMCID: PMC8592995 DOI: 10.1038/s41598-021-01554-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 10/20/2021] [Indexed: 12/05/2022] Open
Abstract
Supraphysiologic androgen (SPA) inhibits cell proliferation in prostate cancer (PCa) cells by transcriptional repression of DNA replication and cell-cycle genes. In this study, quantitative glycoprotein profiling identified androgen-regulated glycoprotein networks associated with SPA-mediated inhibition of PCa cell proliferation, and androgen-regulated glycoproteins in clinical prostate tissues. SPA-regulated glycoprotein networks were enriched for translation factors and ribosomal proteins, proteins that are known to be O-GlcNAcylated in response to various cellular stresses. Thus, androgen-regulated glycoproteins are likely to be targeted for O-GlcNAcylation. Comparative analysis of glycosylated proteins in PCa cells and clinical prostate tissue identified androgen-regulated glycoproteins that are differentially expressed prostate tissues at various stages of cancer. Notably, the enzyme ectonucleoside triphosphate diphosphohydrolase 5 was found to be an androgen-regulated glycoprotein in PCa cells, with higher expression in cancerous versus non-cancerous prostate tissue. Our glycoproteomics study provides an experimental framework for characterizing androgen-regulated proteins and glycoprotein networks, toward better understanding how this subproteome leads to physiologic and supraphysiologic proliferation responses in PCa cells, and their potential use as druggable biomarkers of dysregulated AR-dependent signaling in PCa cells.
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2
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Parrish PCR, Thomas JD, Gabel AM, Kamlapurkar S, Bradley RK, Berger AH. Discovery of synthetic lethal and tumor suppressor paralog pairs in the human genome. Cell Rep 2021; 36:109597. [PMID: 34469736 PMCID: PMC8534300 DOI: 10.1016/j.celrep.2021.109597] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 06/17/2021] [Accepted: 08/03/2021] [Indexed: 01/26/2023] Open
Abstract
CRISPR screens have accelerated the discovery of important cancer vulnerabilities. However, single-gene knockout phenotypes can be masked by redundancy among related genes. Paralogs constitute two-thirds of the human protein-coding genome, so existing methods are likely inadequate for assaying a large portion of gene function. Here, we develop paired guide RNAs for paralog genetic interaction mapping (pgPEN), a pooled CRISPR-Cas9 single- and double-knockout approach targeting more than 2,000 human paralogs. We apply pgPEN to two cell types and discover that 12% of human paralogs exhibit synthetic lethality in at least one context. We recover known synthetic lethal paralogs MEK1/MEK2, important drug targets CDK4/CDK6, and other synthetic lethal pairs including CCNL1/CCNL2. Additionally, we identify ten tumor suppressor paralog pairs whose compound loss promotes cell proliferation. These findings nominate drug targets and suggest that paralog genetic interactions could shape the landscape of positive and negative selection in cancer.
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Affiliation(s)
- Phoebe C R Parrish
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - James D Thomas
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Austin M Gabel
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Medical Scientist Training Program, University of Washington, Seattle, WA 98195, USA
| | - Shriya Kamlapurkar
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Robert K Bradley
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Alice H Berger
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.
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3
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Zhang N, Coutinho LE, Pati D. PDS5A and PDS5B in Cohesin Function and Human Disease. Int J Mol Sci 2021; 22:ijms22115868. [PMID: 34070827 PMCID: PMC8198109 DOI: 10.3390/ijms22115868] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/21/2021] [Accepted: 05/22/2021] [Indexed: 01/02/2023] Open
Abstract
Precocious dissociation of sisters 5 (PDS5) is an associate protein of cohesin that is conserved from yeast to humans. It acts as a regulator of the cohesin complex and plays important roles in various cellular processes, such as sister chromatid cohesion, DNA damage repair, gene transcription, and DNA replication. Vertebrates have two paralogs of PDS5, PDS5A and PDS5B, which have redundant and unique roles in regulating cohesin functions. Herein, we discuss the molecular characteristics and functions of PDS5, as well as the effects of its mutations in the development of diseases and their relevance for novel therapeutic strategies.
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Affiliation(s)
| | | | - Debananda Pati
- Correspondence: ; Tel.: +1-832-824-4575; Fax: +1-832-825-4651
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4
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Mohammad OS, Nyquist MD, Schweizer MT, Balk SP, Corey E, Plymate S, Nelson PS, Mostaghel EA. Supraphysiologic Testosterone Therapy in the Treatment of Prostate Cancer: Models, Mechanisms and Questions. Cancers (Basel) 2017; 9:E166. [PMID: 29210989 PMCID: PMC5742814 DOI: 10.3390/cancers9120166] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/28/2017] [Accepted: 11/29/2017] [Indexed: 12/13/2022] Open
Abstract
Since Huggins defined the androgen-sensitive nature of prostate cancer (PCa), suppression of systemic testosterone (T) has remained the most effective initial therapy for advanced disease although progression inevitably occurs. From the inception of clinical efforts to suppress androgen receptor (AR) signaling by reducing AR ligands, it was also recognized that administration of T in men with castration-resistant prostate cancer (CRPC) could result in substantial clinical responses. Data from preclinical models have reproducibly shown biphasic responses to T administration, with proliferation at low androgen concentrations and growth inhibition at supraphysiological T concentrations. Many questions regarding the biphasic response of PCa to androgen treatment remain, primarily regarding the mechanisms driving these responses and how best to exploit the biphasic phenomenon clinically. Here we review the preclinical and clinical data on high dose androgen growth repression and discuss cellular pathways and mechanisms likely to be involved in mediating this response. Although meaningful clinical responses have now been observed in men with PCa treated with high dose T, not all men respond, leading to questions regarding which tumor characteristics promote response or resistance, and highlighting the need for studies designed to determine the molecular mechanism(s) driving these responses and identify predictive biomarkers.
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Affiliation(s)
- Osama S Mohammad
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
- Faculty of Medicine, Benha University, Benha 13518, Egypt.
| | | | - Michael T Schweizer
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
- School of Medicine, University of Washington, Seattle, WA 98195, USA.
| | - Stephen P Balk
- Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
| | - Eva Corey
- Department of Urology, University of Washington, Seattle, WA 98195, USA.
| | - Stephen Plymate
- School of Medicine, University of Washington, Seattle, WA 98195, USA.
| | - Peter S Nelson
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
| | - Elahe A Mostaghel
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
- School of Medicine, University of Washington, Seattle, WA 98195, USA.
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5
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Pezic D, Weeks SL, Hadjur S. More to cohesin than meets the eye: complex diversity for fine-tuning of function. Curr Opin Genet Dev 2017; 43:93-100. [PMID: 28189962 DOI: 10.1016/j.gde.2017.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/13/2017] [Accepted: 01/16/2017] [Indexed: 11/28/2022]
Abstract
Recent years have witnessed a dramatic expansion in our understanding of gene control. It is now widely appreciated that the spatial organization of the genome and the manner in which genes and regulatory elements are embedded therein has a critical role in facilitating the regulation of gene expression. The loop structures that underlie chromosome organization are anchored by cohesin complexes. Several components of the cohesin complex have multiple paralogs, leading to different levels of cohesin complex variants in cells. Here we review the current literature around cohesin variants and their known functions. We further discuss how variation in cohesin complex composition can result in functional differences that can impact genome organization and determine cell fate.
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Affiliation(s)
- Dubravka Pezic
- Research Department of Cancer Biology, Cancer Institute, University College London, 72 Huntley Street, London WC1E 6BT, United Kingdom
| | - Samuel L Weeks
- Research Department of Cancer Biology, Cancer Institute, University College London, 72 Huntley Street, London WC1E 6BT, United Kingdom
| | - Suzana Hadjur
- Research Department of Cancer Biology, Cancer Institute, University College London, 72 Huntley Street, London WC1E 6BT, United Kingdom.
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6
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Couturier AM, Fleury H, Patenaude AM, Bentley VL, Rodrigue A, Coulombe Y, Niraj J, Pauty J, Berman JN, Dellaire G, Di Noia JM, Mes-Masson AM, Masson JY. Roles for APRIN (PDS5B) in homologous recombination and in ovarian cancer prediction. Nucleic Acids Res 2016; 44:10879-10897. [PMID: 27924011 PMCID: PMC5159559 DOI: 10.1093/nar/gkw921] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 09/11/2016] [Accepted: 10/22/2016] [Indexed: 12/28/2022] Open
Abstract
APRIN (PDS5 cohesin associated factor B) interacts with both the cohesin complex and the BRCA2 tumor suppressor. How APRIN influences cohesion and DNA repair processes is not well understood. Here, we show that APRIN is recruited to DNA damage sites. We find that APRIN interacts directly with RAD51, PALB2 and BRCA2. APRIN stimulates RAD51-mediated DNA strand invasion. APRIN also binds DNA with an affinity for D-loop structures and single-strand (ss) DNA. APRIN is a new homologous recombination (HR) mediator as it counteracts the RPA inhibitory effect on RAD51 loading to ssDNA. We show that APRIN strongly improves the annealing of complementary-strand DNA and that it can stimulate this process in synergy with BRCA2. Unlike cohesin constituents, its depletion has no impact on class switch recombination, supporting a specific role for this protein in HR. Furthermore, we show that low APRIN expression levels correlate with a better survival in ovarian cancer patients and that APRIN depletion sensitizes cells to the PARP inhibitor Olaparib in xenografted zebrafish. Our findings establish APRIN as an important and specific actor of HR, with cohesin-independent functions.
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Affiliation(s)
- Anthony M Couturier
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Québec City, QC G1V 0A6, Canada
| | - Hubert Fleury
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, Canada; Institut du cancer de Montréal, Montréal, QC H2X 0A9, Canada.,Department of Medicine, Université de Montréal, Montréal, QC H2X 0A9, Canada
| | - Anne-Marie Patenaude
- Institut de Recherches Cliniques de Montréal and Department of Medicine, Université de Montréal, Montréal, Québec H2W 1R7, Canada
| | - Victoria L Bentley
- Dalhousie University, Faculty of Medicine, Department of Pathology, Halifax, NS B3H 4R2, Canada
| | - Amélie Rodrigue
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Québec City, QC G1V 0A6, Canada
| | - Yan Coulombe
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Québec City, QC G1V 0A6, Canada
| | - Joshi Niraj
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Québec City, QC G1V 0A6, Canada
| | - Joris Pauty
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Québec City, QC G1V 0A6, Canada
| | - Jason N Berman
- Dalhousie University, Faculty of Medicine, Departments of Microbiology and Immunology, Pediatrics and Pathology, Halifax, NS B3H 4R2, Canada
| | - Graham Dellaire
- Dalhousie University, Faculty of Medicine, Department of Pathology, Halifax, NS B3H 4R2, Canada
| | - Javier M Di Noia
- Institut de Recherches Cliniques de Montréal and Department of Medicine, Université de Montréal, Montréal, Québec H2W 1R7, Canada
| | - Anne-Marie Mes-Masson
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, Canada; Institut du cancer de Montréal, Montréal, QC H2X 0A9, Canada.,Department of Medicine, Université de Montréal, Montréal, QC H2X 0A9, Canada
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada .,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Québec City, QC G1V 0A6, Canada
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7
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Tong K, Skibbens RV. Pds5 regulators segregate cohesion and condensation pathways in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2015; 112:7021-6. [PMID: 25986377 PMCID: PMC4460518 DOI: 10.1073/pnas.1501369112] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cohesins are required both for the tethering together of sister chromatids (termed cohesion) and subsequent condensation into discrete structures-processes fundamental for faithful chromosome segregation into daughter cells. Differentiating between cohesin roles in cohesion and condensation would provide an important advance in studying chromatin metabolism. Pds5 is a cohesin-associated factor that is essential for both cohesion maintenance and condensation. Recent studies revealed that ELG1 deletion suppresses the temperature sensitivity of pds5 mutant cells. However, the mechanisms through which Elg1 may regulate cohesion and condensation remain unknown. Here, we report that ELG1 deletion from pds5-1 mutant cells results in a significant rescue of cohesion, but not condensation, defects. Based on evidence that Elg1 unloads the DNA replication clamp PCNA from DNA, we tested whether PCNA overexpression would similarly rescue pds5-1 mutant cell cohesion defects. The results indeed reveal that elevated levels of PCNA rescue pds5-1 temperature sensitivity and cohesion defects, but do not rescue pds5-1 mutant cell condensation defects. In contrast, RAD61 deletion rescues the condensation defect, but importantly, neither the temperature sensitivity nor cohesion defects exhibited by pds5-1 mutant cells. In combination, these findings reveal that cohesion and condensation are separable pathways and regulated in nonredundant mechanisms. These results are discussed in terms of a new model through which cohesion and condensation are spatially regulated.
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Affiliation(s)
- Kevin Tong
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015
| | - Robert V Skibbens
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015
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8
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Tong K, Skibbens RV. Cohesin without cohesion: a novel role for Pds5 in Saccharomyces cerevisiae. PLoS One 2014; 9:e100470. [PMID: 24963665 PMCID: PMC4070927 DOI: 10.1371/journal.pone.0100470] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 05/18/2014] [Indexed: 11/18/2022] Open
Abstract
High fidelity chromosome segregation during mitosis requires that cells identify the products of DNA replication during S-phase and then maintain that identity until anaphase onset. Sister chromatid identity is achieved through cohesin complexes (Smc1, Smc3, and Mcd1 and Irr1/Scc3), but the structure through which cohesins perform this task remains enigmatic. In the absence of unambiguous data, a popular model is that a subset of cohesin subunits form a huge ring-like structure that embraces both sister chromatids. This 'one-ring two-sister chromatid embrace' model makes clear predictions--including that premature cohesion loss in mitotic cells must occur through a substantial reduction in cohesin-DNA associations. We used chromatin immunoprecipitation to directly test for cohesin dissociation from well-established cohesin binding sites in mitotic cells inactivated for Pds5--a key cohesin regulatory protein. The results reveal little if any chromatin dissociation from cohesins, despite a regimen that produces both massive loss of sister chromatid tethering and cell inviability. We further excluded models that cohesion loss in mitotic cells inactivated for Pds5 arises through either cohesin subunit degradation, premature Hos1-dependent Smc3 de-acetylation or Rad61/WAPL-dependent regulation of cohesin dynamics. In combination, our findings support a model that cohesin complexes associate with each sister and that sister chromatid cohesion likely results from cohesin-cohesin interactions. We further assessed the role that Pds5 plays in cohesion establishment during S-phase. The results show that Pds5 inactivation can result in establishment defects despite normal cohesion loading and Smc3 acetylation, revealing a novel establishment role for Pds5 that is independent of these processes. The combination of findings provides important new insights that significantly impact current models of both cohesion establishment reactions and maintenance.
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Affiliation(s)
- Kevin Tong
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America
| | - Robert V. Skibbens
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America
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9
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Vandenberg LN. Non-monotonic dose responses in studies of endocrine disrupting chemicals: bisphenol a as a case study. Dose Response 2013; 12:259-76. [PMID: 24910584 DOI: 10.2203/dose-response.13-020.vandenberg] [Citation(s) in RCA: 237] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Non-monotonic dose response curves (NMDRCs) have been demonstrated for natural hormones and endocrine disrupting chemicals (EDCs) in a variety of biological systems including cultured cells, whole organ cultures, laboratory animals and human populations. The mechanisms responsible for these NMDRCs are well known, typically related to the interactions between the ligand (hormone or EDC) and a hormone receptor. Although there are hundreds of examples of NMDRCs in the EDC literature, there are claims that they are not 'common enough' to influence the use of high-to-low dose extrapolations in risk assessments. Here, we chose bisphenol A (BPA), a well-studied EDC, to assess the frequency of non-monotonic responses. Our results indicate that NMDRCs are common in the BPA literature, occurring in greater than 20% of all experiments and in at least one endpoint in more than 30% of all studies we examined. We also analyzed the types of endpoints that produce NMDRCs in vitro and factors related to study design that influence the ability to detect these kinds of responses. Taken together, these results provide strong evidence for NMDRCs in the EDC literature, specifically for BPA, and question the current risk assessment practice where 'safe' low doses are predicted from high dose exposures.
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10
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Zhou X, Kong X, Xu W, Chen J. Overexpression of APRIN inhibits differentiation and proliferation and promotes apoptosis in P19 embryonal carcinoma cells. Mol Biol Rep 2012; 40:491-5. [PMID: 23054015 DOI: 10.1007/s11033-012-2085-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Accepted: 10/03/2012] [Indexed: 11/25/2022]
Abstract
We have previously demonstrated that androgen-induced proliferation inhibitor (APRIN) expression was upregulated in ventricular septum tissues from patients with ventricular septal defect (VSD). The present study was designed to investigate the effects of APRIN on P19 cell differentiation, proliferation and apoptosis. In this study, we established a stable APRIN-overexpressing P19 embryonal carcinoma cell line that can differentiate into myocardial cells when treated with 1 % dimethyl sulfoxide. Our data showed that mRNA expressions of myocardial cell differentiation-related genes (such as cTnT, α-MHC, GATA4, and MEF2C) in the APRIN-overexpressing P19 cells were downregulated compared to the empty-vector controls. Our findings also indicated that P19 cells overexpressing APRIN had a reduced growth rate and a decreased S phase of the cell cycle. Moreover, the apoptotic rate in P19 cells overexpressing APRIN was significantly higher than that in the controls. In conclusion, our study demonstrates that overexpression of APRIN inhibits differentiation and proliferation and promotes apoptosis in P19 cells, suggesting that APRIN may be involved in the pathogenesis of VSD.
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Affiliation(s)
- Xiang Zhou
- Department of Cardiology, The Second Affiliated Hospital of Soochow University, No. 1055 Sanxiang Road, Suzhou 215004, China
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11
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Vandenberg LN, Colborn T, Hayes TB, Heindel JJ, Jacobs DR, Lee DH, Shioda T, Soto AM, vom Saal FS, Welshons WV, Zoeller RT, Myers JP. Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses. Endocr Rev 2012; 33:378-455. [PMID: 22419778 PMCID: PMC3365860 DOI: 10.1210/er.2011-1050] [Citation(s) in RCA: 1967] [Impact Index Per Article: 163.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 02/07/2012] [Indexed: 02/08/2023]
Abstract
For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.
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Affiliation(s)
- Laura N Vandenberg
- Tufts University, Center for Regenerative and Developmental Biology, Department of Biology, 200 Boston Avenue, Suite 4600, Medford, Massachusetts 02155, USA.
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12
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Rhodes JM, McEwan M, Horsfield JA. Gene regulation by cohesin in cancer: is the ring an unexpected party to proliferation? Mol Cancer Res 2011; 9:1587-607. [PMID: 21940756 DOI: 10.1158/1541-7786.mcr-11-0382] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cohesin is a multisubunit protein complex that plays an integral role in sister chromatid cohesion, DNA repair, and meiosis. Of significance, both over- and underexpression of cohesin are associated with cancer. It is generally believed that cohesin dysregulation contributes to cancer by leading to aneuploidy or chromosome instability. For cancers with loss of cohesin function, this idea seems plausible. However, overexpression of cohesin in cancer appears to be more significant for prognosis than its loss. Increased levels of cohesin subunits correlate with poor prognosis and resistance to drug, hormone, and radiation therapies. However, if there is sufficient cohesin for sister chromatid cohesion, overexpression of cohesin subunits should not obligatorily lead to aneuploidy. This raises the possibility that excess cohesin promotes cancer by alternative mechanisms. Over the last decade, it has emerged that cohesin regulates gene transcription. Recent studies have shown that gene regulation by cohesin contributes to stem cell pluripotency and cell differentiation. Of importance, cohesin positively regulates the transcription of genes known to be dysregulated in cancer, such as Runx1, Runx3, and Myc. Furthermore, cohesin binds with estrogen receptor α throughout the genome in breast cancer cells, suggesting that it may be involved in the transcription of estrogen-responsive genes. Here, we will review evidence supporting the idea that the gene regulation function of cohesin represents a previously unrecognized mechanism for the development of cancer.
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Affiliation(s)
- Jenny M Rhodes
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
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13
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Denes V, Pilichowska M, Makarovskiy A, Carpinito G, Geck P. Loss of a cohesin-linked suppressor APRIN (Pds5b) disrupts stem cell programs in embryonal carcinoma: an emerging cohesin role in tumor suppression. Oncogene 2010; 29:3446-52. [PMID: 20383194 DOI: 10.1038/onc.2010.100] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 02/08/2010] [Accepted: 03/08/2010] [Indexed: 12/21/2022]
Abstract
Cohesins appear to have critical functions beyond mitotic cohesion. Our data on a cohesin-associated Pds5-paralog, APRIN, indicate a novel cohesin role in stem cell differentiation. APRIN/Pds5B is lost in many cancers and it is a putative tumor suppressor. Its mutations in the germ line, however, generate birth defects. We reasoned that as both cancer and birth defects share disrupted stem cell differentiation, the data suggest an APRIN/Pds5B cohesin function in stem cells. We used an embryonal carcinoma stem cell model and show here that (i) APRIN expression is precisely coordinated with stem cell differentiation; (ii) this coordination involves surface-contact and endocrine pathways; and (iii) APRIN/Pds5b coordination is critical in stem/progenitor exit decisions. APRIN knockdown disrupted Oct4, Nanog and SOX2 patterns, differentiation failed and the resulting immature proliferative cells did not progress beyond proneural progenitor phase. Furthermore, the phenotype-blocked progenitor exit (Mash-1(+)); failed E-cadherin exit (E-Cadh(low+)); incomplete N-cadherin transition (N-Cadh(low+)); retained proliferative capacity (c-myc(+)); irregular stemness (SOX2(late++)) and lost response to contact and hormonal cues-shares similarities with cancer-initiating cells. The data suggest novel APRIN/Pds5B-linked cohesin roles in stem/progenitor programs and a new mechanism in tumor suppression.
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Affiliation(s)
- V Denes
- Department of Anatomy and Cell Biology, Tufts University School of Medicine, Boston, MA, USA
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Reeves R. Nuclear functions of the HMG proteins. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1799:3-14. [PMID: 19748605 DOI: 10.1016/j.bbagrm.2009.09.001] [Citation(s) in RCA: 188] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 09/04/2009] [Indexed: 12/12/2022]
Abstract
Although the three families of mammalian HMG proteins (HMGA, HMGB and HMGN) participate in many of the same nuclear processes, each family plays its own unique role in modulating chromatin structure and regulating genomic function. This review focuses on the similarities and differences in the mechanisms by which the different HMG families impact chromatin structure and influence cellular phenotype. The biological implications of having three architectural transcription factor families with complementary, but partially overlapping, nuclear functions are discussed.
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Affiliation(s)
- Raymond Reeves
- School of Molecular Biosciences, Washington State University, Biotechnology/Life Sciences Bldg., Rm. 143, Pullman, WA 99164-7520, USA.
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