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Purwada A, Jaiswal MK, Ahn H, Nojima T, Kitamura D, Gaharwar AK, Cerchietti L, Singh A. Ex vivo engineered immune organoids for controlled germinal center reactions. Biomaterials 2015; 63:24-34. [PMID: 26072995 DOI: 10.1016/j.biomaterials.2015.06.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 06/01/2015] [Indexed: 01/15/2023]
Abstract
Ex vivo engineered three-dimensional organotypic cultures have enabled the real-time study and control of biological functioning of mammalian tissues. Organs of broad interest where its architectural, cellular, and molecular complexity has prevented progress in ex vivo engineering are the secondary immune organs. Ex vivo immune organs can enable mechanistic understanding of the immune system and more importantly, accelerate the translation of immunotherapies as well as a deeper understanding of the mechanisms that lead to their malignant transformation into a variety of B and T cell malignancies. However, till date, no modular ex vivo immune organ has been developed with an ability to control the rate of immune reaction through tunable design parameter. Here we describe a B cell follicle organoid made of nanocomposite biomaterials, which recapitulates the anatomical microenvironment of a lymphoid tissue that provides the basis to induce an accelerated germinal center (GC) reaction by continuously providing extracellular matrix (ECM) and cell-cell signals to naïve B cells. Compared to existing co-cultures, immune organoids provide a control over primary B cell proliferation with ∼100-fold higher and rapid differentiation to the GC phenotype with robust antibody class switching.
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Affiliation(s)
- Alberto Purwada
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Manish K Jaiswal
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Haelee Ahn
- Division of Hematology and Medical Oncology, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA
| | - Takuya Nojima
- Division of Molecular Biology, Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Noda, Chiba 278-0022, Japan
| | - Daisuke Kitamura
- Division of Molecular Biology, Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Noda, Chiba 278-0022, Japan
| | - Akhilesh K Gaharwar
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; Department of Materials Science & Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Leandro Cerchietti
- Division of Hematology and Medical Oncology, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA
| | - Ankur Singh
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853, USA.
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Haery L, Thompson RC, Gilmore TD. Histone acetyltransferases and histone deacetylases in B- and T-cell development, physiology and malignancy. Genes Cancer 2015; 6:184-213. [PMID: 26124919 PMCID: PMC4482241 DOI: 10.18632/genesandcancer.65] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 05/12/2015] [Indexed: 12/31/2022] Open
Abstract
The development of B and T cells from hematopoietic precursors and the regulation of the functions of these immune cells are complex processes that involve highly regulated signaling pathways and transcriptional control. The signaling pathways and gene expression patterns that give rise to these developmental processes are coordinated, in part, by two opposing classes of broad-based enzymatic regulators: histone acetyltransferases (HATs) and histone deacetylases (HDACs). HATs and HDACs can modulate gene transcription by altering histone acetylation to modify chromatin structure, and by regulating the activity of non-histone substrates, including an array of immune-cell transcription factors. In addition to their role in normal B and T cells, dysregulation of HAT and HDAC activity is associated with a variety of B- and T-cell malignancies. In this review, we describe the roles of HATs and HDACs in normal B- and T-cell physiology, describe mutations and dysregulation of HATs and HDACs that are implicated lymphoma and leukemia, and discuss HAT and HDAC inhibitors that have been explored as treatment options for leukemias and lymphomas.
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Affiliation(s)
- Leila Haery
- Department of Biology, Boston University, Boston, MA, USA
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Shahinas D, Debnath A, Benedict C, McKerrow JH, Pillai DR. Heat shock protein 90 inhibitors repurposed against Entamoeba histolytica. Front Microbiol 2015; 6:368. [PMID: 26029171 PMCID: PMC4429810 DOI: 10.3389/fmicb.2015.00368] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/11/2015] [Indexed: 11/13/2022] Open
Abstract
Hsp90 is an essential chaperone responsible for trafficking a vast array of client proteins, which are substrates that Hsp90 regulates in eukaryotic cells under stress conditions. The ATP-binding N-terminal domain of Hsp90 (also known as a GHKL type ATPase domain) can serve as a specific drug target, because sufficient structural diversity in the ATP-binding pocket of Hsp90 allows for ortholog selectivity of Hsp90 inhibitors. The primary objective of this study is to identify inhibitors specific for the ATP-binding domain of Entamoeba histolytica Hsp90 (EhHsp90). An additional aim, using a combination of site-directed mutagenesis and a protein in vitro assay, is to show that the antiparasitic activity of Hsp90 inhibitors is dependent on specific residues within the ATP-binding domain. Here, we tested the activity of 43 inhibitors of Hsp90 that we previously identified using a high-throughput screen. Of the 43 compounds tested, 19 competed for binding of the EhHsp90 ATP-binding domain. Five out of the 19 EhHsp90 protein hits demonstrated activity against E. histolytica in vitro culture: rifabutin, rutilantin, cetylpyridinium chloride, pararosaniline pamoate and gentian violet. These five top E. histolytica Hsp90 inhibitors showed 30-100% inhibition of E. histolytica in culture in the micromolar range. These data suggest that E. histolytica-specific Hsp90 inhibitors are possible to identify and provide important lead compounds for the development of novel antiamebic drugs.
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Affiliation(s)
- Dea Shahinas
- Department of Laboratory Medicine and Pathobiology, University of Toronto Toronto, ON, Canada
| | - Anjan Debnath
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
| | - Christan Benedict
- Department of Laboratory Medicine and Pathobiology, University of Toronto Toronto, ON, Canada
| | - James H McKerrow
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
| | - Dylan R Pillai
- Department of Pathology and Laboratory Medicine, University of Calgary Calgary, AB, Canada
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Abstract
The pathogenesis of diffuse large B-cell lymphoma (DLBCL) is strongly linked to perturbation of epigenetic mechanisms. The germinal center (GC) B cells from which DLBCLs arise are prone to instability in their cytosine methylation patterns. DLBCLs inherit this epigenetic instability and display variable degrees of epigenetic heterogeneity. Greater epigenetic heterogeneity is linked with poor clinical outcome. Somatic mutations of histone-modifying proteins have also emerged as a hallmark of DLBCL. The effect of these somatic mutations may be to disrupt epigenetic switches that control the GC phenotype and "lock in" certain oncogenic features of GC B cells, resulting in malignant transformation. DNA methyltransferase and histone methyltransferase inhibitors are emerging as viable therapeutic approaches to erase aberrant epigenetic programming, suppress DLBCL growth, and overcome chemotherapy resistance. This review will discuss these recent advances and their therapeutic implications.
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Affiliation(s)
- Yanwen Jiang
- Institute for Computational Biomedicine, Weill Cornell Medical College, New York, NY, USA; Department of Medicine, Weill Cornell Medical College, New York, NY, USA; Sandra and Edward Meyer Cancer Center, Weill Cornell Medical College, New York, NY, USA
| | - Ari Melnick
- Department of Medicine, Weill Cornell Medical College, New York, NY, USA; Sandra and Edward Meyer Cancer Center, Weill Cornell Medical College, New York, NY, USA.
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Bose P, Dai Y, Grant S. Histone deacetylase inhibitor (HDACI) mechanisms of action: emerging insights. Pharmacol Ther 2014; 143:323-36. [PMID: 24769080 PMCID: PMC4117710 DOI: 10.1016/j.pharmthera.2014.04.004] [Citation(s) in RCA: 204] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/10/2014] [Indexed: 02/05/2023]
Abstract
Initially regarded as "epigenetic modifiers" acting predominantly through chromatin remodeling via histone acetylation, HDACIs, alternatively referred to as lysine deacetylase or simply deacetylase inhibitors, have since been recognized to exert multiple cytotoxic actions in cancer cells, often through acetylation of non-histone proteins. Some well-recognized mechanisms of HDACI lethality include, in addition to relaxation of DNA and de-repression of gene transcription, interference with chaperone protein function, free radical generation, induction of DNA damage, up-regulation of endogenous inhibitors of cell cycle progression, e.g., p21, and promotion of apoptosis. Intriguingly, this class of agents is relatively selective for transformed cells, at least in pre-clinical studies. In recent years, additional mechanisms of action of these agents have been uncovered. For example, HDACIs interfere with multiple DNA repair processes, as well as disrupt cell cycle checkpoints, critical to the maintenance of genomic integrity in the face of diverse genotoxic insults. Despite their pre-clinical potential, the clinical use of HDACIs remains restricted to certain subsets of T-cell lymphoma. Currently, it appears likely that the ultimate role of these agents will lie in rational combinations, only a few of which have been pursued in the clinic to date. This review focuses on relatively recently identified mechanisms of action of HDACIs, with particular emphasis on those that relate to the DNA damage response (DDR), and discusses synergistic strategies combining HDACIs with several novel targeted agents that disrupt the DDR or antagonize anti-apoptotic proteins that could have implications for the future use of HDACIs in patients with cancer.
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Affiliation(s)
- Prithviraj Bose
- Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA; Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Yun Dai
- Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA; Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Steven Grant
- Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA; Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA; Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA; Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA, USA; Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, USA; Institute of Molecular Medicine, Virginia Commonwealth University, Richmond, VA, USA.
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Lin G, LaPensee CR, Qin ZS, Schwartz J. Reciprocal occupancy of BCL6 and STAT5 on Growth Hormone target genes: contrasting transcriptional outcomes and promoter-specific roles of p300 and HDAC3. Mol Cell Endocrinol 2014; 395:19-31. [PMID: 25088465 PMCID: PMC4176921 DOI: 10.1016/j.mce.2014.07.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 06/30/2014] [Accepted: 07/28/2014] [Indexed: 12/30/2022]
Abstract
Expression of the Growth Hormone (GH)-stimulated gene Socs2 (Suppressor of Cytokine Signaling 2) is mediated by the transcription activator STAT5 (Signal Transducer and Activator of Transcription 5) and the transcription repressor BCL6 (B-Cell Lymphoma 6). ChIP-Sequencing identified Cish (Cytokine-Inducible SH2-containing protein) and Bcl6 as having similar patterns of reciprocal occupancy by BCL6 and STAT5 in response to GH, though GH stimulates Cish and inhibits Bcl6 expression. The co-activator p300 occupied Socs2, Cish and Bcl6 promoters, and enhanced STAT5-mediated activation of Socs2 and Cish. In contrast, on Bcl6, p300 functioned as a repressor and inhibited in conjunction with STAT5 or BCL6. The co-repressor HDAC3 (Histone deacetylase 3) inhibited the Socs2, Cish and Bcl6 promoters in the presence of STAT5. Thus transcriptional outcomes on GH-regulated genes occupied by BCL6 and STAT5 are determined in a promoter-specific fashion by co-regulatory proteins which mediate the distinction between activating and repressive transcription factors.
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Affiliation(s)
- Grace Lin
- Cellular & Molecular Biology Program, University of Michigan, Ann Arbor, MI, USA; Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Christopher R LaPensee
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Zhaohui S Qin
- Department of Biostatistics and Bioinformatics, Emory University, Atlanta, GA, USA
| | - Jessica Schwartz
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, USA.
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Cerchietti L, Melnick A. Targeting BCL6 in diffuse large B-cell lymphoma: what does this mean for the future treatment? Expert Rev Hematol 2014; 6:343-5. [PMID: 23991920 DOI: 10.1586/17474086.2013.826928] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Hatzi K, Melnick A. Breaking bad in the germinal center: how deregulation of BCL6 contributes to lymphomagenesis. Trends Mol Med 2014; 20:343-52. [PMID: 24698494 DOI: 10.1016/j.molmed.2014.03.001] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 02/28/2014] [Accepted: 03/04/2014] [Indexed: 01/06/2023]
Abstract
The B cell lymphoma 6 (BCL6) transcriptional repressor is a master regulator of the germinal center (GC) B cell program, required for their unique proliferative and stress tolerant phenotype. Most B cell lymphomas arise from GC B cells and are dependent on the continued or deregulated expression of BCL6 to maintain their survival. The actions of BCL6 in B cells involve formation of distinct chromatin modifying complexes that silence specific promoter and enhancer networks, respectively. The same biochemical mechanisms are maintained in malignant lymphoma cells. Targeted inhibition of these BCL6 functions has emerged as the basis for rational design of lymphoma therapies and combinatorial regimens. In this review, we summarize recent advances on BCL6 mechanisms of action and the deregulation of its target gene networks in lymphoma.
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Affiliation(s)
- Katerina Hatzi
- Division of Hematology and Medical Oncology, Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA; Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Ari Melnick
- Division of Hematology and Medical Oncology, Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA; Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA.
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Steinhardt JJ, Gartenhaus RB. Epigenetic approaches for chemosensitization of refractory diffuse large B-cell lymphomas. Cancer Discov 2014; 3:968-70. [PMID: 24019329 DOI: 10.1158/2159-8290.cd-13-0358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma, with the greatest challenge for improving patient survival being the management of chemorefractory disease upon relapse. Epigenetic dysregulation has been correlated with more-aggressive malignancies and chemoresistance. In this issue of Cancer Discovery, Clozel and colleagues show the potential for low-dose DNA methyltransferase inhibitors as both a rational and an effective neoadjuvant approach for chemosensitization in DLBCL.
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Affiliation(s)
- James J Steinhardt
- 1Marlene & Stewart Greenebaum Cancer Center, Department of Medicine, University of Maryland; and 2Veterans Administration Medical Center, Baltimore, Maryland
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61
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Evans SE, Goult BT, Fairall L, Jamieson AG, Ko Ferrigno P, Ford R, Schwabe JWR, Wagner SD. The ansamycin antibiotic, rifamycin SV, inhibits BCL6 transcriptional repression and forms a complex with the BCL6-BTB/POZ domain. PLoS One 2014; 9:e90889. [PMID: 24595451 PMCID: PMC3942486 DOI: 10.1371/journal.pone.0090889] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Accepted: 02/05/2014] [Indexed: 11/22/2022] Open
Abstract
BCL6 is a transcriptional repressor that is over-expressed due to chromosomal translocations, or other abnormalities, in ∼40% of diffuse large B-cell lymphoma. BCL6 interacts with co-repressor, SMRT, and this is essential for its role in lymphomas. Peptide or small molecule inhibitors, which prevent the association of SMRT with BCL6, inhibit transcriptional repression and cause apoptosis of lymphoma cells in vitro and in vivo. In order to discover compounds, which have the potential to be developed into BCL6 inhibitors, we screened a natural product library. The ansamycin antibiotic, rifamycin SV, inhibited BCL6 transcriptional repression and NMR spectroscopy confirmed a direct interaction between rifamycin SV and BCL6. To further determine the characteristics of compounds binding to BCL6-POZ we analyzed four other members of this family and showed that rifabutin, bound most strongly. An X-ray crystal structure of the rifabutin-BCL6 complex revealed that rifabutin occupies a partly non-polar pocket making interactions with tyrosine58, asparagine21 and arginine24 of the BCL6-POZ domain. Importantly these residues are also important for the interaction of BLC6 with SMRT. This work demonstrates a unique approach to developing a structure activity relationship for a compound that will form the basis of a therapeutically useful BCL6 inhibitor.
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Affiliation(s)
- Sian E. Evans
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
- Department of Cancer Studies and Molecular Medicine and MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Benjamin T. Goult
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Louise Fairall
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Andrew G. Jamieson
- Department of Chemistry, University of Leicester, Leicester, United Kingdom
| | - Paul Ko Ferrigno
- Section of Experimental Therapeutics, Leeds Institute of Molecular Medicine, University of Leeds, Leeds, United Kingdom
| | - Robert Ford
- Section of Experimental Therapeutics, Leeds Institute of Molecular Medicine, University of Leeds, Leeds, United Kingdom
| | - John W. R. Schwabe
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Simon D. Wagner
- Department of Cancer Studies and Molecular Medicine and MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- * E-mail:
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Haery L, Lugo-Picó JG, Henry RA, Andrews AJ, Gilmore TD. Histone acetyltransferase-deficient p300 mutants in diffuse large B cell lymphoma have altered transcriptional regulatory activities and are required for optimal cell growth. Mol Cancer 2014; 13:29. [PMID: 24529102 PMCID: PMC3930761 DOI: 10.1186/1476-4598-13-29] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 02/05/2014] [Indexed: 11/10/2022] Open
Abstract
Background Recent genome-wide studies have shown that approximately 30% of diffuse large B-cell lymphoma (DLBCL) cases harbor mutations in the histone acetyltransferase (HAT) coactivators p300 or CBP. The majority of these mutations reduce or eliminate the catalytic HAT activity. We previously demonstrated that the human DLBCL cell line RC-K8 expresses a C-terminally truncated, HAT-defective p300 protein (p300ΔC-1087), whose expression is essential for cell proliferation. Methods Using results from large-scale DLBCL studies, we have identified and characterized a second C-terminally truncated, HAT-defective p300 mutant, p300ΔC-820, expressed in the SUDHL2 DLBCL cell line. Properties of p300ΔC-820 were characterized in the SUDHL2 DLBCL cell line by Western blotting, co-immunoprecipitation, and shRNA gene knockdown, as well by using cDNA expression vectors for p300ΔC-820 in pull-down assays, transcriptional reporter assays, and immunofluorescence experiments. A mass spectrometry-based method was used to compare the histone acetylation profile of DLBCL cell lines expressing various levels of wild-type p300. Results We show that the SUDHL2 cell line expresses a C-terminally truncated, HAT-defective form of p300 (p300ΔC-820), but no wild-type p300. The p300ΔC-820 protein has a wild-type ability to localize to subnuclear “speckles,” but has a reduced ability to enhance transactivation by transcription factor REL. Knockdown of p300ΔC-820 in SUDHL2 cells reduced their proliferation and soft agar colony-forming ability. In RC-K8 cells, knockdown of p300ΔC-1087 resulted in increased expression of mRNA and protein for REL target genes A20 and IκBα, two genes that have been shown to limit the growth of RC-K8 cells when overexpressed. Among a panel of B-lymphoma cell lines, low-level expression of full-length p300 protein, which is characteristic of the SUDHL2 and RC-K8 cells, was associated with decreased acetylation of histone H3 at lysines 14 and 18. Conclusions The high prevalence of p300 mutations in DLBCL suggests that HAT-deficient p300 activity defines a subtype of DLBCL, which we have investigated using human DLBCL cell lines RC-K8 and SUDHL2. Our results suggest that truncated p300 proteins contribute to DLBCL cell growth by affecting the expression of specific genes, perhaps through a mechanism that involves alterations in global histone acetylation.
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Affiliation(s)
| | | | | | | | - Thomas D Gilmore
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA.
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Regulatory role of the 90-kDa-heat-shock protein (Hsp90) and associated factors on gene expression. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:71-87. [DOI: 10.1016/j.bbagrm.2013.12.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 12/23/2013] [Accepted: 12/26/2013] [Indexed: 12/31/2022]
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Targeting the epigenome and other new strategies in diffuse large B-cell lymphoma: beyond R-CHOP. Hematology 2013; 2013:591-5. [DOI: 10.1182/asheducation-2013.1.591] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Diffuse large B-cell lymphoma, the most common lymphoma subtype, is curable in the majority of patients. However, one of the greatest unmet needs in lymphoma treatment remains novel approaches to prevent relapsed or refractory disease. Genomic profiling has provided important prognostic information that is being used in the development of novel therapeutic strategies currently in clinical trials. It is clear, however, that epigenetic alterations provide an additional series of targets that can be pharmacologically modified and offer great potential to improving patient outcomes. Greater understanding of this area is providing important new insights that are now being explored in the clinical setting. Demethylating agents and drugs that disrupt histone modifiers are in early clinical trials with promising results, and other approaches targeting epigenetic pathways are in active preclinical and early clinical development.
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Abstract
PURPOSE OF REVIEW Diffuse large B-cell lymphoma (DLBCL) is an aggressive disease featuring heterogeneous genetic, phenotypic, and clinical characteristics. Understanding the basis for this heterogeneity represents a critical step toward further progress in the management of this disease, which remains a clinical challenge in approximately one-third of patients. This review summarizes current knowledge about the molecular pathogenesis of DLBCL, and describes how recent advances in the genomic characterization of this cancer have provided new insights into its biology, revealing several potential targets for improved diagnosis and therapy. RECENT FINDINGS In the past few years, the development of high-resolution technologies has provided significant help in identifying genetic lesions and/or disrupted signaling pathways that are required for DLBCL initiation and progression. These studies uncovered the involvement of cellular programs that had not been previously appreciated, including histone/chromatin remodeling and immune recognition. Alterations in these pathways could favor epigenetic reprogramming and escape from cellular immunity. SUMMARY The identification of genetic alterations that contribute to the malignant transformation of a B cell into a DLBCL is helping to better understand the biology of this disease and to identify critical nodes driving tumor progression or resistance to therapy. The rapid pace at which these discoveries are taking place is poised to have significant impact for patient stratification based on molecular predictors and for the development of rational targeted therapies.
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Tula-Sanchez AA, Havas AP, Alonge PJ, Klein ME, Doctor SR, Pinkston W, Glinsmann-Gibson BJ, Rimsza LM, Smith CL. A model of sensitivity and resistance to histone deacetylase inhibitors in diffuse large B cell lymphoma: Role of cyclin-dependent kinase inhibitors. Cancer Biol Ther 2013; 14:949-61. [PMID: 23982416 PMCID: PMC3926892 DOI: 10.4161/cbt.25941] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Diffuse large B cell lymphoma (DLBCL) is an aggressive form of non-Hodgkin lymphoma. While the initial treatment strategy is highly effective, relapse occurs in 40% of cases. Histone deacetylase inhibitors (HDACi) are a promising class of anti-cancer drugs but their single agent efficacy against relapsed DLBCL has been variable, ranging from few complete/partial responses to some stable disease. However, most patients showed no response to HDACi monotherapy for unknown reasons. Here we show that sensitivity and resistance to the hydroxamate HDACi, PXD101, can be modeled in DLBCL cell lines. Sensitivity is characterized by G2/M arrest and apoptosis and resistance by reversible G1 growth arrest. These responses to PXD101 are independent of several negative prognostic indicators such as DLBCL subtype, BCL2 and MYC co-expression, and p53 mutation, suggesting that HDACi might be used effectively against highly aggressive DLBCL tumors if they are combined with other therapeutics that overcome HDACi resistance. Our investigation of mechanisms underlying HDACi resistance showed that cyclin-dependent kinase inhibitors (CKIs), p21 and p27, are upregulated by PXD101 in a sustained fashion in resistant cell lines concomitant with decreased activity of the cyclin E/cdk2 complex and decreased Rb phosphorylation. PXD101 treatment results in increased association of CKI with the cyclin E/cdk2 complex in resistant cell lines but not in a sensitive line, indicating that the CKIs play a key role in G1 arrest. The results suggest several treatment strategies that might increase the efficacy of HDACi against aggressive DLBCL.
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Affiliation(s)
- Ana A Tula-Sanchez
- Department of Pharmacology and Toxicology; College of Pharmacy; University of Arizona; Tucson, AZ USA
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Hatzi K, Jiang Y, Huang C, Garrett-Bakelman F, Gearhart MD, Giannopoulou EG, Zumbo P, Kirouac K, Bhaskara S, Polo JM, Kormaksson M, MacKerell AD, Xue F, Mason CE, Hiebert SW, Prive GG, Cerchietti L, Bardwell VJ, Elemento O, Melnick A. A hybrid mechanism of action for BCL6 in B cells defined by formation of functionally distinct complexes at enhancers and promoters. Cell Rep 2013; 4:578-88. [PMID: 23911289 DOI: 10.1016/j.celrep.2013.06.016] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 05/13/2013] [Accepted: 06/11/2013] [Indexed: 11/28/2022] Open
Abstract
The BCL6 transcriptional repressor is required for the development of germinal center (GC) B cells and diffuse large B cell lymphomas (DLBCLs). Although BCL6 can recruit multiple corepressors, its transcriptional repression mechanism of action in normal and malignant B cells is unknown. We find that in B cells, BCL6 mostly functions through two independent mechanisms that are collectively essential to GC formation and DLBCL, both mediated through its N-terminal BTB domain. These are (1) the formation of a unique ternary BCOR-SMRT complex at promoters, with each corepressor binding to symmetrical sites on BCL6 homodimers linked to specific epigenetic chromatin features, and (2) the "toggling" of active enhancers to a poised but not erased conformation through SMRT-dependent H3K27 deacetylation, which is mediated by HDAC3 and opposed by p300 histone acetyltransferase. Dynamic toggling of enhancers provides a basis for B cells to undergo rapid transcriptional and phenotypic changes in response to signaling or environmental cues.
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Affiliation(s)
- Katerina Hatzi
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, Cornell University, New York, NY 10065, USA
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Bunting KL, Melnick AM. New effector functions and regulatory mechanisms of BCL6 in normal and malignant lymphocytes. Curr Opin Immunol 2013; 25:339-46. [PMID: 23725655 PMCID: PMC4075446 DOI: 10.1016/j.coi.2013.05.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 04/26/2013] [Accepted: 05/04/2013] [Indexed: 02/06/2023]
Abstract
The BCL6 oncogenic repressor is a master regulator of humoral immunity and B-cell lymphoma survival. Whereas much research has focused on its regulation and function in germinal center B-cells, its role in other mature lymphoid cell compartments is less clear. A novel role for BCL6 in follicular T helper cell development was recently uncovered. The latest discoveries reveal that BCL6 is also an important regulator of other specialized helper T-cell subsets within germinal centers, pre-germinal center events, and peripheral T-cell effector functions. Here, we review newly discovered roles for BCL6 in lymphocyte subsets residing within and outside of germinal centers, and discuss their implications with respect to the molecular mechanisms of BCL6 regulation and potential links to B and T-cell lymphomas.
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Affiliation(s)
- Karen L Bunting
- Division of Hematology and Medical Oncology, Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA
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70
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Abstract
Genetic analysis of hematologic malignancies over the past 5 years has revealed abundant mutations in epigenetic regulators in all classes of disorders. Here, we summarize the observations made within our review series on the role of epigenetics in hematology. We highlight the clinical implications of mutations in epigenetic regulators and outline what we envision are some of the major areas that merit future research. Recent findings may have immediate prognostic value, but also offer new targets for drug development. However, the pleiotropic action of these regulators indicates caution is warranted and argues for investment in understanding of their underlying mechanisms of action as we proceed to exploit these findings for the benefit of patients.
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71
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Abstract
Histone deacetylase inhibitors (HDACIs) are epigenetically acting agents that modify chromatin structure and by extension, gene expression. However, they may influence the behavior and survival of transformed cells by diverse mechanisms, including promoting expression of death- or differentiation-inducing genes while downregulating the expression of prosurvival genes; acting directly to increase oxidative injury and DNA damage; acetylating and disrupting the function of multiple proteins, including DNA repair and chaperone proteins; and interfering with the function of corepressor complexes. Notably, HDACIs have been shown in preclinical studies to target transformed cells selectively, and these agents have been approved in the treatment of certain hematologic malignancies, for example, cutaneous T-cell lymphoma and peripheral T-cell lymphoma. However, attempts to extend the spectrum of HDACI activity to other malignancies, for example, solid tumors, have been challenging. This has led to the perception that HDACIs may have limited activity as single agents. Because of the pleiotropic actions of HDACIs, combinations with other antineoplastic drugs, particularly other targeted agents, represent a particularly promising avenue of investigation. It is likely that emerging insights into mechanism(s) of HDACI activity will allow optimization of this approach, and hopefully, will expand HDACI approvals to additional malignancies in the future.
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Affiliation(s)
- Steven Grant
- Division of Hematology/Oncology, Virginia Commonwealth University Health Sciences Center, Richmond, Virginia, USA.
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72
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Lineage-specific functions of Bcl-6 in immunity and inflammation are mediated by distinct biochemical mechanisms. Nat Immunol 2013; 14:380-8. [PMID: 23455674 PMCID: PMC3604075 DOI: 10.1038/ni.2543] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 01/10/2013] [Indexed: 01/08/2023]
Abstract
The transcription factor Bcl-6 orchestrates germinal center (GC) reactions through its actions in B cells and T cells and regulates inflammatory signaling in macrophages. Here we found that genetic replacement with mutated Bcl6 encoding Bcl-6 that cannot bind corepressors to its BTB domain resulted in disruption of the formation of GCs and affinity maturation of immunoglobulins due to a defect in the proliferation and survival of B cells. In contrast, loss of function of the BTB domain had no effect on the differentiation and function of follicular helper T cells or that of other helper T cell subsets. Bcl6-null mice had a lethal inflammatory phenotype, whereas mice with a mutant BTB domain had normal healthy lives with no inflammation. The repression of inflammatory responses by Bcl-6 in macrophages was accordingly independent of the repressor function of the BTB domain. Bcl-6 thus mediates its actions through lineage-specific biochemical functions.
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73
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Lee JG, Ye Y. Bag6/Bat3/Scythe: a novel chaperone activity with diverse regulatory functions in protein biogenesis and degradation. Bioessays 2013; 35:377-85. [PMID: 23417671 DOI: 10.1002/bies.201200159] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Upon emerging from the ribosome exiting tunnel, polypeptide folding occurs immediately with the assistance of both ribosome-associated and free chaperones. While many chaperones known to date are dedicated folding catalysts, recent studies have revealed a novel chaperoning system that functions at the interface of protein biogenesis and quality control by using a special "holdase" activity in order to sort and channel client proteins to distinct destinations. The key component, Bag6/Bat3/Scythe, can effectively shield long hydrophobic segments exposed on the surface of a polypeptide, preventing aggregation or inappropriate interactions before a triaging decision is made. The biological consequences of Bag6-mediated chaperoning are divergent for different substrates, ranging from membrane integration to proteasome targeting and destruction. Accordingly, Bag6 can act in various cellular contexts in order to execute many essential cellular functions, while dysfunctions in the Bag6 system can cause severe cellular abnormalities that may be associated with some pathological conditions.
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Affiliation(s)
- Jin-Gu Lee
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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74
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Shahinas D, Folefoc A, Pillai DR. Targeting Plasmodium falciparum Hsp90: Towards Reversing Antimalarial Resistance. Pathogens 2013; 2:33-54. [PMID: 25436880 PMCID: PMC4235713 DOI: 10.3390/pathogens2010033] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 01/18/2013] [Accepted: 01/23/2013] [Indexed: 12/29/2022] Open
Abstract
Malaria continues to exact a great human toll in tropical settings. Antimalarial resistance is rife and the parasite inexorably develops mechanisms to outwit our best drugs, including the now first-line choice, artesunate. Novel strategies to circumvent resistance are needed. Here we detail drug development focusing on heat shock protein 90 and its central role as a chaperone. A growing body of evidence supports the role for Hsp90 inhibitors as adjunctive drugs able to restore susceptibility to traditionally efficacious compounds like chloroquine.
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Affiliation(s)
- Dea Shahinas
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Canada.
| | - Asongna Folefoc
- Department of Pathology & Laboratory Medicine, The University of Calgary, Calgary, AB, Canada.
| | - Dylan R Pillai
- Department of Pathology & Laboratory Medicine, The University of Calgary, Calgary, AB, Canada.
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75
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Dyer MJS, Vogler M, Samuel J, Jayne S, Wagner S, Pritchard C, Macip S. Precision medicines for B-cell leukaemias and lymphomas; progress and potential pitfalls. Br J Haematol 2013; 160:725-33. [DOI: 10.1111/bjh.12219] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Martin J. S. Dyer
- Departments of Cancer Studies and Molecular Medicine; University of Leicester; Leicester UK
| | - Meike Vogler
- Departments of Cancer Studies and Molecular Medicine; University of Leicester; Leicester UK
| | - Jesvin Samuel
- Department of Biochemistry; University of Leicester; Leicester UK
| | | | - Simon Wagner
- Departments of Cancer Studies and Molecular Medicine; University of Leicester; Leicester UK
| | - Catrin Pritchard
- Department of Biochemistry; University of Leicester; Leicester UK
| | - Salvador Macip
- Department of Biochemistry; University of Leicester; Leicester UK
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76
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Taylor KH, Briley A, Wang Z, Cheng J, Shi H, Caldwell CW. Aberrant Epigenetic Gene Regulation in Lymphoid Malignancies. Semin Hematol 2013; 50:38-47. [DOI: 10.1053/j.seminhematol.2013.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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77
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Fontan L, Yang C, Kabaleeswaran V, Volpon L, Osborne MJ, Beltran E, Garcia M, Cerchietti L, Shaknovich R, Yang SN, Fang F, Gascoyne RD, Martinez-Climent JA, Glickman JF, Borden K, Wu H, Melnick A. MALT1 small molecule inhibitors specifically suppress ABC-DLBCL in vitro and in vivo. Cancer Cell 2012; 22:812-24. [PMID: 23238016 PMCID: PMC3984478 DOI: 10.1016/j.ccr.2012.11.003] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 10/26/2012] [Accepted: 11/12/2012] [Indexed: 12/14/2022]
Abstract
MALT1 cleavage activity is linked to the pathogenesis of activated B cell-like diffuse large B cell lymphoma (ABC-DLBCL), a chemoresistant form of DLBCL. We developed a MALT1 activity assay and identified chemically diverse MALT1 inhibitors. A selected lead compound, MI-2, featured direct binding to MALT1 and suppression of its protease function. MI-2 concentrated within human ABC-DLBCL cells and irreversibly inhibited cleavage of MALT1 substrates. This was accompanied by NF-κB reporter activity suppression, c-REL nuclear localization inhibition, and NF-κB target gene downregulation. Most notably, MI-2 was nontoxic to mice, and displayed selective activity against ABC-DLBCL cell lines in vitro and xenotransplanted ABC-DLBCL tumors in vivo. The compound was also effective against primary human non-germinal center B cell-like DLBCLs ex vivo.
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Affiliation(s)
- Lorena Fontan
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, New York, NY 10021, USA
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10021, USA
- Division of Oncology, Center for Applied Medical Research, University of Navarra, 31008 Pamplona, Navarra, Spain
| | - Chenghua Yang
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10021, USA
| | - Venkataraman Kabaleeswaran
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10021, USA
- Program in Cellular and Molecular Medicine, Children’s Hospital Boston, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Laurent Volpon
- Institute for Research in Immunology and Cancer, University of Montreal, Montreal QC H3C 3J7, Canada
| | - Michael J. Osborne
- Institute for Research in Immunology and Cancer, University of Montreal, Montreal QC H3C 3J7, Canada
| | - Elena Beltran
- Division of Oncology, Center for Applied Medical Research, University of Navarra, 31008 Pamplona, Navarra, Spain
| | - Monica Garcia
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, New York, NY 10021, USA
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10021, USA
| | - Leandro Cerchietti
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, New York, NY 10021, USA
| | - Rita Shaknovich
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, New York, NY 10021, USA
- Division of Immunopathology, Department of Pathology, Weill Cornell Medical College, New York, NY 10021, USA
| | - Shao Ning Yang
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, New York, NY 10021, USA
| | - Fang Fang
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, New York, NY 10021, USA
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10021, USA
| | - Randy D. Gascoyne
- Centre for Lymphoid Cancer, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Jose Angel Martinez-Climent
- Division of Oncology, Center for Applied Medical Research, University of Navarra, 31008 Pamplona, Navarra, Spain
| | - J. Fraser Glickman
- High-Throughput Screening Resource Center, The Rockefeller University, New York, NY 10065, USA
| | - Katherine Borden
- Institute for Research in Immunology and Cancer, University of Montreal, Montreal QC H3C 3J7, Canada
| | - Hao Wu
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10021, USA
- Program in Cellular and Molecular Medicine, Children’s Hospital Boston, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Correspondence: (H.W.), (A.M.)
| | - Ari Melnick
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, New York, NY 10021, USA
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10021, USA
- Correspondence: (H.W.), (A.M.)
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78
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Abstract
BCL6 is a transcriptional repressor required in mature B cells during the germinal center (GC) reaction. Multiple mechanisms act coordinately to timely modulate BCL6 expression at transcriptional and post-transcriptional levels. BCL6 prevents premature activation and differentiation of GC B cells and provides an environment tolerant of the DNA breaks associated with immunoglobulin gene remodeling mechanisms involved in the production of high-affinity antibodies of different isotypes. The critical functions exerted by BCL6 during normal B-cell development can be hijacked by the malignant transformation process. Indeed, BCL6 is targeted by genetic aberrations and acts as an oncogene in GC-derived lymphomas. The aberrations affecting BCL6 interfere with the multiple levels of regulation that grant a fine tuning of BCL6 expression and activity in physiologic conditions. This review summarizes the current knowledge on BCL6 function and its role in lymphomagenesis.
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Affiliation(s)
- Katia Basso
- Department of Pathology and Cell Biology, Institute for Cancer Genetics, the Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY 10032, USA
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79
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Steinhardt JJ, Gartenhaus RB. Promising personalized therapeutic options for diffuse large B-cell Lymphoma Subtypes with oncogene addictions. Clin Cancer Res 2012; 18:4538-48. [PMID: 22745106 DOI: 10.1158/1078-0432.ccr-12-0217] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Currently, two major classification systems segregate diffuse large B-cell lymphoma (DLBCL) into subtypes based on gene expression profiles and provide great insights about the oncogenic mechanisms that may be crucial for lymphomagenesis as well as prognostic information regarding response to current therapies. However, these current classification systems primarily look at expression and not dependency and are thus limited to inductive or probabilistic reasoning when evaluating alternative therapeutic options. The development of a deductive classification system that identifies subtypes in which all patients with a given phenotype require the same oncogenic drivers, and would therefore have a similar response to a rational therapy targeting the essential drivers, would significantly advance the treatment of DLBCL. This review highlights the putative drivers identified as well as the work done to identify potentially dependent populations. These studies integrated genomic analysis and functional screens to provide a rationale for targeted therapies within defined populations. Personalizing treatments by identifying patients with oncogenic dependencies via genotyping and specifically targeting the responsible drivers may constitute a novel approach for the treatment of DLBCL.
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Affiliation(s)
- James J Steinhardt
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine and Veterans Administration Medical Center, Baltimore, MD 21201, USA
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80
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Popovic R, Licht JD. Emerging epigenetic targets and therapies in cancer medicine. Cancer Discov 2012; 2:405-13. [PMID: 22588878 DOI: 10.1158/2159-8290.cd-12-0076] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
UNLABELLED Abnormalities in the epigenetic regulation of chromatin structure and function can lead to aberrant gene expression and cancer development. Consequently, epigenetic therapies aim to restore normal chromatin modification patterns through the inhibition of various components of the epigenetic machinery. Histone deacetylase and DNA methyltransferase inhibitors represent the first putative epigenetic therapies; however, these agents have pleiotropic effects and it remains unclear how they lead to therapeutic responses. More recently, drugs that inhibit histone methyltransferases were developed, perhaps representing more specific agents. We review emerging epigenetic targets in cancer and present recent models of promising epigenetic therapies. SIGNIFICANCE The use of DNA methyltransferase and histone deacetylase inhibitors in patients has validated the use of drugs targeted to epigenetic enzymes and strengthened the need for development of additional therapies. In this review, we summarize recently discovered epigenetic abnormalities, their implications for cancer, and the approaches taken for discovering small-molecule inhibitors targeting various properties of the epigenetic machinery.
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Affiliation(s)
- Relja Popovic
- Division of Hematology/Oncology, Robert. H. Lurie Comprehensive Cancer Center, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611, USA
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81
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Foon KA, Takeshita K, Zinzani PL. Novel therapies for aggressive B-cell lymphoma. Adv Hematol 2012; 2012:302570. [PMID: 22536253 PMCID: PMC3318210 DOI: 10.1155/2012/302570] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/16/2011] [Indexed: 12/21/2022] Open
Abstract
Aggressive B-cell lymphoma (BCL) comprises a heterogeneous group of malignancies, including diffuse large B-cell lymphoma (DLBCL), Burkitt lymphoma, and mantle cell lymphoma (MCL). DLBCL, with its 3 subtypes, is the most common type of lymphoma. Advances in chemoimmunotherapy have substantially improved disease control. However, depending on the subtype, patients with DLBCL still exhibit substantially different survival rates. In MCL, a mature B-cell lymphoma, the addition of rituximab to conventional chemotherapy regimens has increased response rates, but not survival. Burkitt lymphoma, the most aggressive BCL, is characterized by a high proliferative index and requires more intensive chemotherapy regimens than DLBCL. Hence, there is a need for more effective therapies for all three diseases. Increased understanding of the molecular features of aggressive BCL has led to the development of a range of novel therapies, many of which target the tumor in a tailored manner and are summarized in this paper.
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Affiliation(s)
- Kenneth A. Foon
- Celgene Corporation, 86 Morris Avenue, Summit, NJ 07901, USA
| | | | - Pier L. Zinzani
- Department of Hematology and Oncological Sciences “L. e A. Seràgnoli”, University of Bologna, Via Massarenti, 9-40138 Bologna, Italy
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82
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Wurm T, Wright DG, Polakowski N, Mesnard JM, Lemasson I. The HTLV-1-encoded protein HBZ directly inhibits the acetyl transferase activity of p300/CBP. Nucleic Acids Res 2012; 40:5910-25. [PMID: 22434882 PMCID: PMC3401433 DOI: 10.1093/nar/gks244] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The homologous cellular coactivators p300 and CBP contain intrinsic lysine acetyl transferase (termed HAT) activity. This activity is responsible for acetylation of several sites on the histones as well as modification of transcription factors. In a previous study, we found that HBZ, encoded by the Human T-cell Leukemia Virus type 1 (HTLV-1), binds to multiple domains of p300/CBP, including the HAT domain. In this study, we found that HBZ inhibits the HAT activity of p300/CBP through the bZIP domain of the viral protein. This effect correlated with a reduction of H3K18 acetylation, a specific target of p300/CBP, in cells expressing HBZ. Interestingly, lower levels of H3K18 acetylation were detected in HTLV-1 infected cells compared to non-infected cells. The inhibitory effect of HBZ was not limited to histones, as HBZ also inhibited acetylation of the NF-κB subunit, p65, and the tumor suppressor, p53. Recent studies reported that mutations in the HAT domain of p300/CBP that cause a defect in acetylation are found in certain types of leukemia. These observations suggest that inhibition of the HAT activity by HBZ is important for the development of adult T-cell leukemia associated with HTLV-1 infection.
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Affiliation(s)
- Torsten Wurm
- East Carolina University, Brody School of Medicine, Greenville, NC 27834, USA
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83
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Kroenke MA, Eto D, Locci M, Cho M, Davidson T, Haddad EK, Crotty S. Bcl6 and Maf cooperate to instruct human follicular helper CD4 T cell differentiation. THE JOURNAL OF IMMUNOLOGY 2012; 188:3734-44. [PMID: 22427637 DOI: 10.4049/jimmunol.1103246] [Citation(s) in RCA: 266] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Follicular helper CD4 T (Tfh) cells provide B cells with signals that are important for the generation of high-affinity Abs and immunological memory and, therefore, are critical for the protective immunity elicited by most human vaccines. Transcriptional regulators of human Tfh cell differentiation are poorly understood. In this article, we demonstrate that Bcl6 controls specific gene modules for human Tfh cell differentiation. The introduction of Bcl6 expression in primary human CD4 T cells resulted in the regulation of a core set of migration genes that enable trafficking to germinal centers: CXCR4, CXCR5, CCR7, and EBI2. Bcl6 expression also induced a module of protein expression critical for T-B interactions, including SAP, CD40L, PD-1, ICOS, and CXCL13. This constitutes direct evidence for Bcl6 control of most of these functions and includes three genes known to be loci of severe human genetic immunodeficiencies (CD40L, SH2D1A, and ICOS). Introduction of Bcl6 did not alter the expression of IL-21 or IL-4, the primary cytokines of human Tfh cells. We show in this article that introduction of Maf (c-Maf) does induce the capacity to express IL-21. Surprisingly, Maf also induced CXCR5 expression. Coexpression of Bcl6 and Maf revealed that Bcl6 and Maf cooperate in the induction of CXCR4, PD-1, and ICOS. Altogether, these findings reveal that Bcl6 and Maf collaborate to orchestrate a suite of genes that define core characteristics of human Tfh cell biology.
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Affiliation(s)
- Mark A Kroenke
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
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84
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Abstract
The mechanisms that drive normal B cell differentiation and activation are frequently subverted by B cell lymphomas for their unlimited growth and survival. B cells are particularly prone to malignant transformation because the machinery used for antibody diversification can cause chromosomal translocations and oncogenic mutations. The advent of functional and structural genomics has greatly accelerated our understanding of oncogenic mechanisms in lymphomagenesis. The signaling pathways that normal B cells utilize to sense antigens are frequently derailed in B cell malignancies, leading to constitutive activation of prosurvival pathways. These malignancies co-opt transcriptional regulatory systems that characterize their normal B cell counterparts and frequently alter epigenetic regulators of chromatin structure and gene expression. These mechanistic insights are ushering in an era of targeted therapies for these cancers based on the principles of pathogenesis.
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Affiliation(s)
- Arthur L Shaffer
- Metabolism Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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85
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Abstract
Ghrelin O-acyltransferase (GOAT) is responsible for catalyzing the attachment of the eight-carbon fatty acid octanoyl to the Ser3 side chain of the peptide ghrelin to generate the active form of this metabolic hormone. As such, GOAT is viewed as a potential therapeutic target for the treatment of obesity and diabetes mellitus. Here, we review recent progress in the development of cell and in vitro assays to measure GOAT action and the identification of several synthetic GOAT inhibitors. In particular, we discuss the design, synthesis, and characterization of the bisubstrate analog GO-CoA-Tat and its ability to modulate weight and blood glucose in mice. We also highlight current challenges and future research directions in our biomedical understanding of this fascinating ghrelin processing enzyme.
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Affiliation(s)
- Martin S Taylor
- Department of Pharmacology & Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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86
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Xiong Y, Lei QY, Zhao S, Guan KL. Regulation of glycolysis and gluconeogenesis by acetylation of PKM and PEPCK. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2011; 76:285-9. [PMID: 22096030 DOI: 10.1101/sqb.2011.76.010942] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Glycolysis is a catabolic process of glucose hydrolysis needed for energy and biosynthetic intermediates, whereas gluconeogenesis is a glucose production process important for maintaining blood glucose levels during starvation. Although they share many enzymes, these two processes are not simply the reverse of each other and are instead reciprocally regulated. Two key enzymes that regulate irreversible steps in these two processes are pyruvate kinase (PK) and phosphoenolpyruvate carboxy kinase (PEPCK), which catalyze the last and first step of glycolysis and gluconeogenesis, respectively, and are both regulated by lysine acetylation. Acetylation at Lys305 of the PKM (muscle form of PK) decreases its activity and also targets it for chaperone-mediated autophagy and subsequent lysosome degradation. Acetylation of PEPCK, on the other hand, targets it for ubiquitylation by the HECT E3 ligase, UBR5/EDD1, and subsequent proteasomal degradation. These studies established a model in which acetylation regulates metabolic enzymes via different mechanisms and also revealed cross talk between acetylation and ubiquitination. Given that most metabolic enzymes are acetylated, we propose that acetylation is a major posttranslational modifier that regulates cellular metabolism.
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Affiliation(s)
- Y Xiong
- Molecular and Cell Biology Laboratory, Institute of Biomedical Sciences, Shanghai Medical School, Fudan University, Shanghai 20032, China.
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87
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Abstract
PURPOSE OF REVIEW It has only recently become apparent that mutations in epigenetic mechanisms and perturbation of epigenomic patterning are frequent events in B-cell lymphomas. The purpose of this review is to highlight these new findings and provide a conceptual framework for understanding how epigenetic modifications might contribute to lymphomagenesis. RECENT FINDINGS Somatic mutations affecting histone methyltransferases such as enhancer of zeste 2 and mixed lineage leukemia 2, histone demethylases including ubiquitously transcribed X chromosome tetratricopeptide repeat and Jumonji domain-containing 2C, and histone acetyltransferases including CBP and p300 are recurrent and common in lymphomas. These mutations result in disruption of chromatin structure and functions of other proteins, ultimately causing aberrant transcriptional programming affecting multiple gene networks. Widespread perturbation of cytosine methylation patterning now appears to be a hallmark of B-cell lymphomas and occurs in specific patterns that can distinguish disease subtypes. Therapeutic targeting strategies can overcome abnormal epigenetic mechanisms and potently kill lymphoma cells. SUMMARY Newly discovered epigenetic lesions may provide critical insights into the genesis of B-cell lymphomas, but further studies are required to understand how they affect biological mechanism. Epigenetic lesions offer tremendous opportunities for the development of improved biomarkers and treatments.
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88
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Spiegel S, Milstien S, Grant S. Endogenous modulators and pharmacological inhibitors of histone deacetylases in cancer therapy. Oncogene 2011; 31:537-51. [PMID: 21725353 DOI: 10.1038/onc.2011.267] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The class-I histone deacetylases (HDACs) HDAC1 and HDAC2 belong to a family of 11 zinc-dependent human HDACs and are overexpressed in many cancers. Inhibitors of these HDACs now in clinical trials show activity against several types of cancers. This review is focused on recent advances in both clinical and preclinical efforts to understand the basis for the actions of HDACis, with emphasis on implications for rational combinations with conventional or other targeted agents. We will address new perspectives on the molecular mechanisms by which HDACs act and how these actions relate to cancer. We will also review new evidence showing that HDACs are direct intracellular targets of the potent sphingolipid mediator S1P, the first identified endogenous nuclear regulator of these enzymes, linking sphingolipid metabolism in the nucleus to remodeling of chromatin and epigenetic regulation of gene expression. Understanding how endogenous molecules regulate HDAC activity in vivo may facilitate the search for safer and more effective anticancer drugs capable of interfering with HDAC functions in a highly specific manner.
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Affiliation(s)
- S Spiegel
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine Richmond, Richmond, VA 23298, USA.
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