1
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Garcia-Cuellar MP, Akan S, Slany RK. A C/ebpα isoform specific differentiation program in immortalized myelocytes. Leukemia 2023; 37:1850-1859. [PMID: 37532789 PMCID: PMC10457184 DOI: 10.1038/s41375-023-01989-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/18/2023] [Accepted: 07/25/2023] [Indexed: 08/04/2023]
Abstract
The transcription factor CCAAT-enhancer binding factor alpha (C/ebpα) is a master controller of myeloid differentiation that is expressed as long (p42) and short (p30) isoform. Mutations within the CEBPA gene selectively deleting p42 are frequent in human acute myeloid leukemia. Here we investigated the individual genomics and transcriptomics of p42 and p30. Both proteins bound to identical sites across the genome. For most targets, they induced a highly similar transcriptional response with the exception of a few isoform specific genes. Amongst those we identified early growth response 1 (Egr1) and tribbles1 (Trib1) as key targets selectively induced by p42 that are also underrepresented in CEBPA-mutated AML. Egr1 executed a program of myeloid differentiation and growth arrest. Oppositely, Trib1 established a negative feedback loop through activation of Erk1/2 kinase thus placing differentiation under control of signaling. Unexpectedly, differentiation elicited either by removal of an oncogenic input or by G-CSF did not peruse C/ebpα as mediator but rather directly affected the cell cycle core by upregulation of p21/p27 inhibitors. This points to functions downstream of C/ebpα as intersection point where transforming and differentiation stimuli converge and this finding offers a new perspective for therapeutic intervention.
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Affiliation(s)
| | - Selin Akan
- Department of Genetics, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Robert K Slany
- Department of Genetics, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.
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2
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Camargo-Forero N, Orozco-Arias S, Perez Agudelo JM, Guyot R. HERV-K (HML-2) insertion polymorphisms in the 8q24.13 region and their potential etiological associations with acute myeloid leukemia. Arch Virol 2023; 168:125. [PMID: 36988711 DOI: 10.1007/s00705-023-05747-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 02/03/2023] [Indexed: 03/30/2023]
Abstract
Human endogenous retroviruses (HERVs) are LTR retrotransposons that are present in the human genome. Among them, members of the HERV-K (HML-2) group are suspected to play a role in the development of different types of cancer, including lung, ovarian, and prostate cancer, as well as leukemia. Acute myeloid leukemia (AML) is an important disease that causes 1% of cancer deaths in the United States and has a survival rate of 28.7%. Here, we describe a method for assessing the statistical association between HERV-K (HML-2) transposable element insertion polymorphisms (or TIPs) and AML, using whole-genome sequencing and read mapping using TIP_finder software. Our results suggest that 101 polymorphisms involving HERV-K (HML-2) elements were correlated with AML, with a percentage between 44.4 to 56.6%, most of which (70) were located in the region from 8q24.13 to 8q24.21. Moreover, it was found that the TRIB1, LRATD2, POU5F1B, MYC, PCAT1, PVT1, and CCDC26 genes could be displaced or fragmented by TIPs. Furthermore, a general method was devised to facilitate analysis of the correlation between transposable element insertions and specific diseases. Finally, although the relationship between HERV-K (HML-2) TIPs and AML remains unclear, the data reported in this study indicate a statistical correlation, as supported by the χ2 test with p-values < 0.05.
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Affiliation(s)
- Nicolás Camargo-Forero
- School of Biology, Universidad Industrial de Santander, Bucaramanga, Santander, Colombia
| | - Simon Orozco-Arias
- Department of Computer Science, Universidad Autónoma de Manizales, Manizales, Caldas, Colombia.
- Department of Systems and Informatics, Universidad de Caldas, Manizales, Caldas, Colombia.
| | | | - Romain Guyot
- UMR DIADE, Université de Montpellier, Institut de recherche pour le développement, CIRAD, Montpellier, France
- Department of Electronics and Automation, Universidad Autónoma de Manizales, Manizales, Caldas, Colombia
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3
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Liu YR, Song DD, Liang DM, Li YJ, Yan YF, Sun HF, Zhang ML, Hu JX, Zhao YL, Liang Y, Li YM, Yang Z, Wang RR, Zheng HF, Wang P, Xie SY. Oncogenic TRIB2 interacts with and regulates PKM2 to promote aerobic glycolysis and lung cancer cell procession. Cell Death Dis 2022; 8:306. [PMID: 35790734 PMCID: PMC9256704 DOI: 10.1038/s41420-022-01095-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 06/14/2022] [Accepted: 06/17/2022] [Indexed: 12/15/2022]
Abstract
PKM2 is an important regulator of the aerobic glycolysis that plays a vital role in cancer cell metabolic reprogramming. In general, Trib2 is considered as a “pseudokinase”, contributing to different kinds of cancer. However, the detailed roles of TRIB2 in regulating cancer metabolism by PKM2 remain unclear. This study demonstrated that TRIB2, not a “pseudokinase”, has the kinase activity to directly phosphorylate PKM2 at serine 37 in cancer cells. The elevated pSer37-PKM2 would subsequently promote the PKM2 dimers to enter into nucleus and increase the expression of LDHA, GLUT1, and PTBP1. The aerobic glycolysis is then elevated to promote cancer cell proliferation and migration in TRIB2- or PKM2-overexpressed cultures. The glucose uptake and lactate production increased, but the ATP content decreased in TRIB2- or PKM2-treated cultures. Experiments of TRIB2−/− mice further supported that TRIB2 could regulate aerobic glycolysis by PKM2. Thus, these results reveal the new kinase activity of TRIB2 and its mechanism in cancer metabolism may be related to regulating PKM2 to promote lung cancer cell proliferation in vitro and in vivo, suggesting promising therapeutic targets for cancer therapy by controlling cancer metabolism.
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4
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Zhang M, Qi T, Yang L, Kolarich D, Heisterkamp N. Multi-Faceted Effects of ST6Gal1 Expression on Precursor B-Lineage Acute Lymphoblastic Leukemia. Front Oncol 2022; 12:828041. [PMID: 35371997 PMCID: PMC8967368 DOI: 10.3389/fonc.2022.828041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/07/2022] [Indexed: 12/20/2022] Open
Abstract
Normal early human B-cell development from lymphoid progenitors in the bone marrow depends on instructions from elements in that microenvironment that include stromal cells and factors secreted by these cells including the extracellular matrix. Glycosylation is thought to play a key role in such interactions. The sialyltransferase ST6Gal1, with high expression in specific hematopoietic cell types, is the only enzyme thought to catalyze the terminal addition of sialic acids in an α2-6-linkage to galactose on N-glycans in such cells. Expression of ST6Gal1 increases as B cells undergo normal B-lineage differentiation. B-cell precursor acute lymphoblastic leukemias (BCP-ALLs) with differentiation arrest at various stages of early B-cell development have widely different expression levels of ST6GAL1 at diagnosis, with high ST6Gal1 in some but not in other relapses. We analyzed the consequences of increasing ST6Gal1 expression in a diagnosis sample using lentiviral transduction. NSG mice transplanted with these BCP-ALL cells were monitored for survival. Compared to mice transplanted with leukemia cells expressing original ST6Gal1 levels, increased ST6Gal1 expression was associated with significantly reduced survival. A cohort of mice was also treated for 7 weeks with vincristine chemotherapy to induce remission and then allowed to relapse. Upon vincristine discontinuation, relapse was detected in both groups, but mice transplanted with ST6Gal1 overexpressing BCP-ALL cells had an increased leukemia burden and shorter survival than controls. The BCP-ALL cells with higher ST6Gal1 were more resistant to long-term vincristine treatment in an ex vivo tissue co-culture model with OP9 bone marrow stromal cells. Gene expression analysis using RNA-seq showed a surprisingly large number of genes with significantly differential expression, of which approximately 60% increased mRNAs, in the ST6Gal1 overexpressing BCP-ALL cells. Pathways significantly downregulated included those involved in immune cell migration. However, ST6Gal1 knockdown cells also showed increased insensitivity to chemotherapy. Our combined results point to a context-dependent effect of ST6Gal1 expression on BCP-ALL cells, which is discussed within the framework of its activity as an enzyme with many N-linked glycoprotein substrates.
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Affiliation(s)
- Mingfeng Zhang
- Department of Systems Biology, Beckman Research Institute City of Hope, Duarte, CA, United States
| | - Tong Qi
- Department of Systems Biology, Beckman Research Institute City of Hope, Duarte, CA, United States
| | - Lu Yang
- Department of Systems Biology, Beckman Research Institute City of Hope, Duarte, CA, United States
| | - Daniel Kolarich
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia.,Australian Research Council (ARC) Centre of Excellence for Nanoscale BioPhotonics, Griffith University, Gold Coast, QLD, Australia
| | - Nora Heisterkamp
- Department of Systems Biology, Beckman Research Institute City of Hope, Duarte, CA, United States
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5
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Mickevicius T, Vilkeviciute A, Glebauskiene B, Kriauciuniene L, Liutkeviciene R. Do TRIB1 and IL-9 Gene Polymorphisms Impact the Development and Manifestation of Pituitary Adenoma? In Vivo 2021; 34:2499-2505. [PMID: 32871778 DOI: 10.21873/invivo.12066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 05/29/2020] [Accepted: 05/31/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND/AIM To evaluate the association between TRIB1(rs6987702) and IL-9(rs1859430, rs2069870) genotypes with the development and manifestation of pituitary adenoma (PA). MATERIALS AND METHODS The study group included 141 patients with PA and the control group consisted of 287 healthy people. The genotyping of rs6987702, rs1859430 and rs2069870 was carried out using a real-time polymerase chain reaction. RESULTS Statistically significant results were obtained regarding the rs1859430, but there were no significant results regarding rs6987702. We found that the rs1859430 A/A genotype increased the odds of having recurrent PA six times (p=0.006) under the co-dominant model and four times (p=0.021) under the recessive model. Furthermore, the analysis showed that the G/A genotype increased the odds of having recurrent PA 2.3 times (p=0.003) under the co-dominant model, while G/A and A/A genotypes increased the odds 2.7 times (p=0.011) under the over-dominant model. CONCLUSION Certain genotypes of rs1859430 can be associated with PA recurrence.
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Affiliation(s)
- Tomas Mickevicius
- Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Alvita Vilkeviciute
- Neuroscience Institute, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Brigita Glebauskiene
- Neuroscience Institute, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Loresa Kriauciuniene
- Neuroscience Institute, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Rasa Liutkeviciene
- Neuroscience Institute, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
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6
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Mayoral-Varo V, Jiménez L, Link W. The Critical Role of TRIB2 in Cancer and Therapy Resistance. Cancers (Basel) 2021; 13:cancers13112701. [PMID: 34070799 PMCID: PMC8198994 DOI: 10.3390/cancers13112701] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 05/24/2021] [Accepted: 05/27/2021] [Indexed: 12/13/2022] Open
Abstract
Simple Summary The Tribbles proteins are members of CAMK Ser/Thr protein kinase family. They are evolutionary conserved pseudokinases found in most tissues of eukaryotic organisms. This ubiquitously expressed protein family is characterized by containing a catalytically deficient kinase domain which lacks amino acid residues required for the productive interaction with ATP and metal ions. Tribbles proteins exert their biological functions mainly through direct interaction with MAPKK and AKT proteins, therefore regulating important pathways involved in cell proliferation, apoptosis and differentiation. Due to the role of MAPKK and AKT signalling in the context of cancer development, Tribbles proteins have been recently considered as biomarkers of cancer progression. Furthermore, as the atypical pseudokinase domain retains a binding platform for substrates, Tribbles targeting provides an attractive opportunity for drug development. Abstract The Tribbles pseudokinases family consists of TRIB1, TRIB2, TRIB3 and STK40 and, although evolutionarily conserved, they have distinctive characteristics. Tribbles members are expressed in a context and cell compartment-dependent manner. For example, TRIB1 and TRIB2 have potent oncogenic activities in vertebrate cells. Since the identification of Tribbles proteins as modulators of multiple signalling pathways, recent studies have linked their expression with several pathologies, including cancer. Tribbles proteins act as protein adaptors involved in the ubiquitin-proteasome degradation system, as they bridge the gap between substrates and E3 ligases. Between TRIB family members, TRIB2 is the most ancestral member of the family. TRIB2 is involved in protein homeostasis regulation of C/EBPα, β-catenin and TCF4. On the other hand, TRIB2 interacts with MAPKK, AKT and NFkB proteins, involved in cell survival, proliferation and immune response. Here, we review the characteristic features of TRIB2 structure and signalling and its role in many cancer subtypes with an emphasis on TRIB2 function in therapy resistance in melanoma, leukemia and glioblastoma. The strong evidence between TRIB2 expression and chemoresistance provides an attractive opportunity for targeting TRIB2.
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7
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Trib1 promotes acute myeloid leukemia progression by modulating the transcriptional programs of Hoxa9. Blood 2021; 137:75-88. [PMID: 32730594 DOI: 10.1182/blood.2019004586] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 07/13/2020] [Indexed: 12/13/2022] Open
Abstract
The pseudokinase Trib1 functions as a myeloid oncogene that recruits the E3 ubiquitin ligase COP1 to C/EBPα and interacts with MEK1 to enhance extracellular signal-regulated kinase (ERK) phosphorylation. A close genetic effect of Trib1 on Hoxa9 has been observed in myeloid leukemogenesis, where Trib1 overexpression significantly accelerates Hoxa9-induced leukemia onset. However, the mechanism underlying how Trib1 functionally modulates Hoxa9 transcription activity is unclear. Herein, we provide evidence that Trib1 modulates Hoxa9-associated super-enhancers. Chromatin immunoprecipitation sequencing analysis identified increased histone H3K27Ac signals at super-enhancers of the Erg, Spns2, Rgl1, and Pik3cd loci, as well as increased messenger RNA expression of these genes. Modification of super-enhancer activity was mostly achieved via the degradation of C/EBPα p42 by Trib1, with a slight contribution from the MEK/ERK pathway. Silencing of Erg abrogated the growth advantage acquired by Trib1 overexpression, indicating that Erg is a critical downstream target of the Trib1/Hoxa9 axis. Moreover, treatment of acute myeloid leukemia (AML) cells with the BRD4 inhibitor JQ1 showed growth inhibition in a Trib1/Erg-dependent manner both in vitro and in vivo. Upregulation of ERG by TRIB1 was also observed in human AML cell lines, suggesting that Trib1 is a potential therapeutic target of Hoxa9-associated AML. Taken together, our study demonstrates a novel mechanism by which Trib1 modulates chromatin and Hoxa9-driven transcription in myeloid leukemogenesis.
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8
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Control of Cell Growth and Proliferation by the Tribbles Pseudokinase: Lessons from Drosophila. Cancers (Basel) 2021; 13:cancers13040883. [PMID: 33672471 PMCID: PMC7923445 DOI: 10.3390/cancers13040883] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/09/2021] [Accepted: 02/14/2021] [Indexed: 12/13/2022] Open
Abstract
Simple Summary Tribbles pseudokinases represent a sub-branch of the CAMK (Ca2+/calmodulin-dependent protein kinase) subfamily and are associated with disease-associated signaling pathways associated with various cancers, including melanoma, lung, liver, and acute leukemia. The ability of this class of molecules to regulate cell proliferation was first recognized in the model organism Drosophila and the fruit fly genetic model and continues to provide insight into the molecular mechanism by which this family of adapter molecules regulates both normal development and disease associated with corruption of their proper regulation and function. Abstract The Tribbles (Trib) family of pseudokinase proteins regulate cell growth, proliferation, and differentiation during normal development and in response to environmental stress. Mutations in human Trib isoforms (Trib1, 2, and 3) have been associated with metabolic disease and linked to leukemia and the formation of solid tumors, including melanomas, hepatomas, and lung cancers. Drosophila Tribbles (Trbl) was the first identified member of this sub-family of pseudokinases and shares a conserved structure and similar functions to bind and direct the degradation of key mediators of cell growth and proliferation. Common Trib targets include Akt kinase (also known as protein kinase B), C/EBP (CAAT/enhancer binding protein) transcription factors, and Cdc25 phosphatases, leading to the notion that Trib family members stand athwart multiple pathways modulating their growth-promoting activities. Recent work using the Drosophila model has provided important insights into novel facets of conserved Tribbles functions in stem cell quiescence, tissue regeneration, metabolism connected to insulin signaling, and tumor formation linked to the Hippo signaling pathway. Here we highlight some of these recent studies and discuss their implications for understanding the complex roles Tribs play in cancers and disease pathologies.
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TRIB3 destabilizes tumor suppressor PPARα expression through ubiquitin-mediated proteasome degradation in acute myeloid leukemia. Life Sci 2020; 257:118021. [PMID: 32621919 DOI: 10.1016/j.lfs.2020.118021] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 06/17/2020] [Accepted: 06/24/2020] [Indexed: 12/23/2022]
Abstract
AIMS Tribbles homolog 3 (TRIB3) is emerging as a multifunctional oncoprotein associated with various cellular events in different tumors. However, the regulatory mechanism of TRIB3 in acute myeloid leukemia (AML) remains unknown. This study aims to investigate the molecular mechanisms and uncover the functions of TRIB3 in AML. METHODS Western blotting and quantitative real-time PCR were used to analyze the expression levels of TRIB3, peroxisome proliferator-activated receptor α (PPARα), apoptosis markers and autophagy markers in AML cells. Flow cytometry was used to assess cell apoptosis. The interaction of TRIB3 and PPARα was evaluated by immunofluorescence, coimmunoprecipitation, and in vivo ubiquitination assays. KEY FINDINGS We demonstrated that downregulating TRIB3 in leukemic cells effectively induced apoptosis and autophagy by regulating the degradation of PPARα. Mechanistically, TRIB3 interacted with PPARα and contributed to its destabilization by promoting its ubiquitination. When PPARα was activated by its specific agonist clofibrate, the apoptosis and autophagy of AML cells were significantly enhanced. These results were confirmed by rescue experiments. Blocking PPARα expression using the PPARα inhibitor GW6471 reversed the functional influence of TRIB3 on AML cells. SIGNIFICANCE The aim of this study is to provide evidence of the degradation of PPARα by TRIB3 via ubiquitin-dependent proteasomal degradation. This process meditates the progression of AML and prolongs the survival of leukemic cells. As a result, these data indicate that TRIB3 is a novel and promising therapeutic target for AML treatment.
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10
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Conte M, Dell'Aversana C, Sgueglia G, Carissimo A, Altucci L. HDAC2-dependent miRNA signature in acute myeloid leukemia. FEBS Lett 2019; 593:2574-2584. [PMID: 31254352 PMCID: PMC6790563 DOI: 10.1002/1873-3468.13521] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/11/2019] [Accepted: 06/27/2019] [Indexed: 12/14/2022]
Abstract
Acute myeloid leukemia (AML) arises from a complex sequence of biological and finely orchestrated events that are still poorly understood. Increasingly, epigenetic studies are providing exciting findings that may be exploited in promising and personalized cutting‐edge therapies. A more appropriate and broader screening of possible players in cancer could identify a master molecular mechanism in AML. Here, we build on our previously published study by evaluating a histone deacetylase (HDAC)2‐mediated miRNA regulatory network in U937 leukemic cells. Following a comparative miRNA profiling analysis in genetically and enzymatically HDAC2‐downregulated AML cells, we identified miR‐96‐5p and miR‐92a‐3p as potential regulators in AML etiopathology by targeting defined genes. Our findings support the potentially beneficial role of alternative physiopathological interventions.
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Affiliation(s)
| | - Carmela Dell'Aversana
- Department of Precision Medicine, University of Campania "L. Vanvitelli", Naples, Italy
| | - Giulia Sgueglia
- Department of Precision Medicine, University of Campania "L. Vanvitelli", Naples, Italy
| | - Annamaria Carissimo
- Department of Precision Medicine, University of Campania "L. Vanvitelli", Naples, Italy
| | - Lucia Altucci
- Department of Precision Medicine, University of Campania "L. Vanvitelli", Naples, Italy
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11
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Uncovering Potential Therapeutic Targets in Colorectal Cancer by Deciphering Mutational Status and Expression of Druggable Oncogenes. Cancers (Basel) 2019; 11:cancers11070983. [PMID: 31337155 PMCID: PMC6679198 DOI: 10.3390/cancers11070983] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 06/28/2019] [Accepted: 07/11/2019] [Indexed: 12/26/2022] Open
Abstract
Background: Numerous driver mutations have been identified in colorectal cancer (CRC), but their relevance to the development of targeted therapies remains elusive. The secondary effects of pathogenic driver mutations on downstream signaling pathways offer a potential approach for the identification of therapeutic targets. We aimed to identify differentially expressed genes as potential drug targets linked to driver mutations. Methods: Somatic mutations and the gene expression data of 582 CRC patients were utilized, incorporating the mutational status of 39,916 and the expression levels of 20,500 genes. To uncover candidate targets, the expression levels of various genes in wild-type and mutant cases for the most frequent disruptive mutations were compared with a Mann–Whitney test. A survival analysis was performed in 2100 patients with transcriptomic gene expression data. Up-regulated genes associated with worse survival were filtered for potentially actionable targets. The most significant hits were validated in an independent set of 171 CRC patients. Results: Altogether, 426 disruptive mutation-associated upregulated genes were identified. Among these, 95 were linked to worse recurrence-free survival (RFS). Based on the druggability filter, 37 potentially actionable targets were revealed. We selected seven genes and validated their expression in 171 patient specimens. The best independently validated combinations were DUSP4 (p = 2.6 × 10−12) in ACVR2A mutated (7.7%) patients; BMP4 (p = 1.6 × 10−04) in SOX9 mutated (8.1%) patients; TRIB2 (p = 1.35 × 10−14) in ACVR2A mutated patients; VSIG4 (p = 2.6 × 10−05) in ANK3 mutated (7.6%) patients, and DUSP4 (p = 7.1 × 10−04) in AMER1 mutated (8.2%) patients. Conclusions: The results uncovered potentially druggable genes in colorectal cancer. The identified mutations could enable future patient stratification for targeted therapy.
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12
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Highlights of the 2nd International Symposium on Tribbles and Diseases: tribbles tremble in therapeutics for immunity, metabolism, fundamental cell biology and cancer. Acta Pharm Sin B 2019. [DOI: 10.1016/j.apsb.2018.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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13
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Foulkes DM, Byrne DP, Yeung W, Shrestha S, Bailey FP, Ferries S, Eyers CE, Keeshan K, Wells C, Drewry DH, Zuercher WJ, Kannan N, Eyers PA. Covalent inhibitors of EGFR family protein kinases induce degradation of human Tribbles 2 (TRIB2) pseudokinase in cancer cells. Sci Signal 2018; 11:11/549/eaat7951. [PMID: 30254057 DOI: 10.1126/scisignal.aat7951] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A major challenge associated with biochemical and cellular analysis of pseudokinases is a lack of target-validated small-molecule compounds with which to probe function. Tribbles 2 (TRIB2) is a cancer-associated pseudokinase with a diverse interactome, including the canonical AKT signaling module. There is substantial evidence that human TRIB2 promotes survival and drug resistance in solid tumors and blood cancers and therefore is of interest as a therapeutic target. The unusual TRIB2 pseudokinase domain contains a unique cysteine-rich C-helix and interacts with a conserved peptide motif in its own carboxyl-terminal tail, which also supports its interaction with E3 ubiquitin ligases. We found that TRIB2 is a target of previously described small-molecule protein kinase inhibitors, which were originally designed to inhibit the canonical kinase domains of epidermal growth factor receptor tyrosine kinase family members. Using a thermal shift assay, we discovered TRIB2-binding compounds within the Published Kinase Inhibitor Set (PKIS) and used a drug repurposing approach to classify compounds that either stabilized or destabilized TRIB2 in vitro. TRIB2 destabilizing agents, including the covalent drug afatinib, led to rapid TRIB2 degradation in human AML cancer cells, eliciting tractable effects on signaling and survival. Our data reveal new drug leads for the development of TRIB2-degrading compounds, which will also be invaluable for unraveling the cellular mechanisms of TRIB2-based signaling. Our study highlights that small molecule-induced protein down-regulation through drug "off-targets" might be relevant for other inhibitors that serendipitously target pseudokinases.
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Affiliation(s)
- Daniel M Foulkes
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Dominic P Byrne
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Wayland Yeung
- Institute of Bioinformatics and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Safal Shrestha
- Institute of Bioinformatics and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Fiona P Bailey
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Samantha Ferries
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.,Centre for Proteome Research, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Claire E Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.,Centre for Proteome Research, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Karen Keeshan
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, Scotland, UK
| | - Carrow Wells
- Structural Genomics Consortium, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - David H Drewry
- Structural Genomics Consortium, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - William J Zuercher
- Structural Genomics Consortium, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Natarajan Kannan
- Institute of Bioinformatics and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
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14
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Salomé M, Hopcroft L, Keeshan K. Inverse and correlative relationships between TRIBBLES genes indicate non-redundant functions during normal and malignant hemopoiesis. Exp Hematol 2018; 66:63-78.e13. [PMID: 30031847 DOI: 10.1016/j.exphem.2018.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/11/2018] [Accepted: 07/12/2018] [Indexed: 01/31/2023]
Abstract
TRIBBLES pseudokinases (TRIB1, TRIB2, and TRIB3) are important regulators of normal and malignant hemopoiesis. The relative abundance of each TRIBBLES family member may be important for distinct oncogenic or tumor suppressor functions. We map the expression profiles of TRIB1, TRIB2, and TRIB3 in human and murine hemopoietic stem, progenitor and mature cells, and in human leukemia datasets. Our data show that TRIB1-TRIB2 have an inverse expression relationship in normal hemopoiesis, whereas TRIB1-TRIB3 have a positive correlation. We reveal that TRIB3 expression is high in the dormant hemopoietic stem cell (HSC) population, implicating a novel role for TRIB3 in stem cell quiescence. These analyses support a non-redundant role for each TRIBBLES member during normal hemopoietic differentiation. We show that TRIB1-TRIB2 display a significant negative correlation in myelodysplastic syndrome and acute myeloid leukemia (AML) subtypes, but not in acute lymphoid leukemia. This inverse relationship is specific to certain subtypes of AML. A positive correlation exists in different leukemia subtypes between TRIB1-TRIB3. The TRIB1-TRIB2 and TRIB1-TRIB3 correlations are consistent with a correlative relationship with C/EBP transcription factor family members. Our results have implications for the development of strategies to therapeutically target these genes in different types of leukemia.
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Affiliation(s)
- Mara Salomé
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, Scotland, UK
| | - Lisa Hopcroft
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, Scotland, UK
| | - Karen Keeshan
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, Scotland, UK.
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15
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A Trib2-p38 axis controls myeloid leukaemia cell cycle and stress response signalling. Cell Death Dis 2018; 9:443. [PMID: 29670085 PMCID: PMC5906628 DOI: 10.1038/s41419-018-0467-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/28/2018] [Accepted: 03/02/2018] [Indexed: 01/18/2023]
Abstract
Trib2 pseudokinase is involved in the etiology of a number of cancers including leukaemia, melanoma, ovarian, lung and liver cancer. Both high and low Trib2 expression levels correlate with different types of cancer. Elevated Trib2 expression has oncogenic properties in both leukaemia and lung cancer dependent on interactions with proteasome machinery proteins and degradation of transcription factors. Here, we demonstrated that Trib2 deficiency conferred a growth and survival advantage both at steady state and in stress conditions in leukaemia cells. In response to stress, wild type leukaemia cells exited the cell cycle and underwent apoptosis. In contrast, Trib2 deficient leukaemia cells continued to enter mitosis and survive. We showed that Trib2 deficient leukaemia cells had defective MAPK p38 signalling, which associated with a reduced γ-H2Ax and Chk1 stress signalling response, and continued proliferation following stress, associated with inefficient activation of cell cycle inhibitors p21, p16 and p19. Furthermore, Trib2 deficient leukaemia cells were more resistant to chemotherapy than wild type leukaemia cells, having less apoptosis and continued propagation. Trib2 re-expression or pharmacological activation of p38 in Trib2 deficient leukaemia cells sensitised the cells to chemotherapy-induced apoptosis comparable with wild type leukaemia cells. Our data provide evidence for a tumour suppressor role of Trib2 in myeloid leukaemia via activation of p38 stress signalling. This newly identified role indicates that Trib2 may counteract the propagation and chemotherapy resistance of leukaemia cells.
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16
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Abstract
Colorectal cancer (CRC) is the third most common cancer in the world and distant metastasis is the leading cause of death among CRC patients. However, the underlying mechanisms of distant metastasis remain largely unknown. Amplification of 8q24 is a common chromosomal abnormality in CRC. In the present study, a putative oncogene at 8q24, TRIB1, was characterized for its role in CRC metastasis and underlying molecular mechanisms. Higher expression of TRIB1 protein was detected in 58/83 (69.9%) of CRC tissues, compared with adjacent non-tumor tissues. Moreover, the expression of TRIB1 was significantly associated with distant metastasis (P=0.043) and advanced staging (P=0.008) in CRC tissues. TRIB1 overexpression was also correlated with poor prognosis in CRC patients as analyzed in PrognoScan database. In addition, elevated expression of TRIB1 promoted CRC cell motility and adhesive ability, while silencing of TRIB1 reduced those effects. Further study revealed that TRIB1-mediated migration and invasion of CRC cells required up-regulation of MMP-2 through the activation of FAK/Src and ERK pathway. Collectively, the results suggest that TRIB1 promotes CRC cell motility by activation MMP-2 via the FAK/Src and ERK pathways. It may provide a potential diagnostic and therapeutic target for CRC.
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17
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Soon MSF, Haque A. Recent Insights into CD4+Th Cell Differentiation in Malaria. THE JOURNAL OF IMMUNOLOGY 2018; 200:1965-1975. [DOI: 10.4049/jimmunol.1701316] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/08/2018] [Indexed: 02/06/2023]
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18
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O'Connor C, Yalla K, Salomé M, Moka HA, Castañeda EG, Eyers PA, Keeshan K. Trib2 expression in granulocyte-monocyte progenitors drives a highly drug resistant acute myeloid leukaemia linked to elevated Bcl2. Oncotarget 2018; 9:14977-14992. [PMID: 29599919 PMCID: PMC5871090 DOI: 10.18632/oncotarget.24525] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 02/10/2018] [Indexed: 12/13/2022] Open
Abstract
Trib2 pseudokinase has oncogenic and tumour suppressive functions depending on the cellular context. We investigated the ability of Trib2 to transform different haemopoietic stem and progenitor cells (HSPCs). Our study identified the granulocyte-macrophage progenitor (GMP) subpopulation as a potent leukaemia initiating cell of Trib2-driven AML in vivo. Trib2 transformed GMPs generated a fully penetrant and short latency AML. AML cells expressing elevated Trib2 led to a chemoresistant phenotype following chemotherapy treatment. We show that Trib2 overexpression results in an increase in BCL2 expression, and high Trib2 expressing cells are highly sensitive to cell killing by BCL2 inhibition (ABT199). Combined treatment with chemotherapeutic agents and BCL2 inhibition resulted in synergistic killing of Trib2+ AML cells. Trib2 transformed GMP AML cells showed more chemoresistance compared with HSPC derived Trib2 AML cells associated with higher Bcl2 expression. There is significant correlation of high TRIB2 and BCL2 expression in patient derived human AML cells. These data demonstrate that the cell of origin influences the leukaemic profile and chemotherapeutic response of Trib2+ AML. Combined TRIB2 and BCL2 expression in AML cells may have clinical utility relevant for monitoring drug resistance and disease relapse.
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Affiliation(s)
- Caitriona O'Connor
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 0XB, UK
| | - Krishna Yalla
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 0XB, UK
| | - Mara Salomé
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 0XB, UK
| | - Hothri Ananyambica Moka
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 0XB, UK
| | - Eduardo Gómez Castañeda
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 0XB, UK
| | - Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Karen Keeshan
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 0XB, UK
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19
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Liang Y, Yu D, Perez-Soler R, Klostergaard J, Zou Y. TRIB2 contributes to cisplatin resistance in small cell lung cancer. Oncotarget 2017; 8:109596-109608. [PMID: 29312632 PMCID: PMC5752545 DOI: 10.18632/oncotarget.22741] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 08/28/2017] [Indexed: 01/06/2023] Open
Abstract
Small cell lung cancer (SCLC) is the most aggressive lung-cancer subtype and so far, no favorable therapeutic strategy has been established for chemo-resistant SCLC. Cisplatin is one of the most important components among all standard poly-chemotherapeutic regimens for SCLC; therefore, this study focused on revealing Cisplatin-resistance mechanism(s) in this disease. Cisplatin-resistant SCLC cells were generated in the NCI-H69 xenograft model in nude mice by continuous intravenous administration of Cisplatin; Cisplatin resistance of the tumor cells was confirmed by in vitro and in vivo tests, and the gene expression profile of the resistant cells was determined using microarray analysis. A significantly higher expression of tribbles pseudokinase 2 (TRIB2) mRNA in the Cisplatin-resistant cells was found compared to parental H69 cells. Further, the Cisplatin-resistance level was decreased when TRIB2 expression was knocked down. The mRNA and protein levels of CCAAT/enhancer binding protein alpha (CEBPA), known to be a transcription factor regulating cell differentiation and a target for degradation by TRIB2, as well as selected cancer stem cell makers in the Cisplatin-resistant cells, were measured. We found that CEBPA protein levels could be upregulated by knocking down the overexpressed TRIB2, which also reversed the Cisplatin-resistance of these cells; further, the Cisplatin-resistant SCLC cells demonstrated certain cancer stem cell-like properties. Similar patterns were also observed in limited human tumor specimens of chemo-resistant SCLC patients: namely, overexpressed TRIB2 and undetected CEBPA proteins. Our study revealed a possible molecular mechanism for Cisplatin-resistant SCLC involving induced TRIB2 overexpression and downregulation of CEBPA protein. We propose that this mechanism is a potential therapeutic target to circumvent chemo-resistance in SCLC.
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Affiliation(s)
- Yuanxin Liang
- Department of Medicine/Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA.,Department of Pathology, Tufts Medical Center, Boston, MA, USA
| | - Dong Yu
- Department of Respiratory and Oncology, Hubei Provincial Corps Hospital, Wuhan, China
| | - Roman Perez-Soler
- Department of Medicine/Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Jim Klostergaard
- Department of Molecular and Cellular Oncology, MD Anderson Cancer Center, Houston, TX, USA
| | - Yiyu Zou
- Department of Medicine/Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
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20
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Li K, Wang F, Hu ZW. Targeting pseudokinase TRIB3 brings about a new therapeutic option for acute promyelocytic leukemia. Mol Cell Oncol 2017; 4:e1337547. [PMID: 28868348 DOI: 10.1080/23723556.2017.1337547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 05/26/2017] [Accepted: 05/26/2017] [Indexed: 10/19/2022]
Abstract
Pseudokinase tribbles (Trib) family, Trib1 and Trib2, but not Trib3, act as oncogene to drive acute leukemia by destabilizing the myeloid transcription factor CCAAT/enhancer-binding protein α (C/EBPα) and inhibiting myeloid differentiation. A recent study identifies pseudokinase TRIB3 as an important factor in acute promyelocytic leukemia (APL) progression and therapy resistance. Targeting TRIB3 may provide a novel therapeutic approach for APL.
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Affiliation(s)
- Ke Li
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Feng Wang
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Zhuo-Wei Hu
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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21
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Li K, Wang F, Cao WB, Lv XX, Hua F, Cui B, Yu JJ, Zhang XW, Shang S, Liu SS, Yu JM, Han MZ, Huang B, Zhang TT, Li X, Jiang JD, Hu ZW. TRIB3 Promotes APL Progression through Stabilization of the Oncoprotein PML-RARα and Inhibition of p53-Mediated Senescence. Cancer Cell 2017; 31:697-710.e7. [PMID: 28486108 DOI: 10.1016/j.ccell.2017.04.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 12/10/2016] [Accepted: 04/12/2017] [Indexed: 12/19/2022]
Abstract
Acute promyelocytic leukemia (APL) is driven by the oncoprotein PML-RARα, which antagonizes myeloid differentiation and promotes APL-initiating cell self-renewal. Combined all-trans retinoic acid (ATRA) with arsenic trioxide (As2O3) or chemotherapy dramatically improves the prognosis of APL patients. Here we report that expression of pseudokinase Tribble 3 (TRIB3) associates positively with APL progression and therapeutic resistance. The elevated TRIB3 expression promotes APL by interacting with PML-RARα and suppressing its sumoylation, ubiquitylation, and degradation. This represses PML nuclear body assembly, p53-mediated senescence, and cell differentiation, and supports cellular self-renewal. Genetically inhibiting TRIB3 expression or combination of a peptide disturbing TRIB3/PML-RARα interaction with ATRA/As2O3 eradicates APL by accelerating PML-RARα degradation. Our study provides insight into APL pathogenesis and a potential therapeutic option against APL.
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MESH Headings
- Animals
- Antineoplastic Combined Chemotherapy Protocols/pharmacology
- Arsenic Trioxide
- Arsenicals/pharmacology
- Cell Cycle Proteins/deficiency
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Cell Differentiation/drug effects
- Cell Line, Tumor
- Cell Proliferation
- Cellular Senescence
- Disease Progression
- Drug Resistance, Neoplasm
- Female
- Gene Expression Regulation
- Gene Fusion
- HEK293 Cells
- Humans
- Leukemia, Promyelocytic, Acute/drug therapy
- Leukemia, Promyelocytic, Acute/genetics
- Leukemia, Promyelocytic, Acute/metabolism
- Leukemia, Promyelocytic, Acute/pathology
- Male
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Inbred NOD
- Mice, SCID
- Mice, Transgenic
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Oxides/pharmacology
- Peptides/pharmacology
- Protein Serine-Threonine Kinases/antagonists & inhibitors
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Protein Stability
- Proteolysis
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Signal Transduction
- Sumoylation
- Time Factors
- Transfection
- Tretinoin/pharmacology
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- Ubiquitination
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Ke Li
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Feng Wang
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Wen-Bin Cao
- Hematopoietic Stem Cell Transplantation Center, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, P.R. China
| | - Xiao-Xi Lv
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Fang Hua
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Bing Cui
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Jiao-Jiao Yu
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Xiao-Wei Zhang
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Shuang Shang
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Shan-Shan Liu
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Jin-Mei Yu
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Ming-Zhe Han
- Hematopoietic Stem Cell Transplantation Center, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, P.R. China
| | - Bo Huang
- Institute of Basic Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, P.R. China
| | - Ting-Ting Zhang
- Department of Pharmacy, Marine College, Shandong University, Weihai 264209, P.R. China
| | - Xia Li
- Department of Pharmacy, Marine College, Shandong University, Weihai 264209, P.R. China
| | - Jian-Dong Jiang
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China; Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China
| | - Zhuo-Wei Hu
- Immunology and Cancer Pharmacology Group, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, P.R. China.
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22
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Abstract
The t(15;17) translocation generates a PML-RARα fusion protein causative for acute promyelocytic leukemia (APL). Li et al. now identify the pseudokinase stress protein TRIB3 as an important factor in APL disease progression and therapy resistance. Targeting the interaction of TRIB3 and PML-RARα using peptide technology provides a novel therapeutic approach.
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Affiliation(s)
- Ruaidhrí Carmody
- Centre for Immunobiology, Institute of Infection, Immunity and Inflammation, College of Medicine, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - Karen Keeshan
- Paul O'Gorman Leukaemia Research Centre, College of Medicine, Veterinary and Life Sciences, Institute of Cancer Sciences, University of Glasgow, Glasgow, G12 0XB, UK.
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23
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Eyers PA, Keeshan K, Kannan N. Tribbles in the 21st Century: The Evolving Roles of Tribbles Pseudokinases in Biology and Disease. Trends Cell Biol 2016; 27:284-298. [PMID: 27908682 PMCID: PMC5382568 DOI: 10.1016/j.tcb.2016.11.002] [Citation(s) in RCA: 156] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/01/2016] [Accepted: 11/03/2016] [Indexed: 11/26/2022]
Abstract
The Tribbles (TRIB) pseudokinases control multiple aspects of eukaryotic cell biology and evolved unique features distinguishing them from all other protein kinases. The atypical pseudokinase domain retains a regulated binding platform for substrates, which are ubiquitinated by context-specific E3 ligases. This plastic configuration has also been exploited as a scaffold to support the modulation of canonical MAPK and AKT modules. In this review, we discuss the evolution of TRIBs and their roles in vertebrate cell biology. TRIB2 is the most ancestral member of the family, whereas the emergence of TRIB3 homologs in mammals supports additional biological roles, many of which are currently being dissected. Given their pleiotropic role in diseases, the unusual TRIB pseudokinase conformation provides a highly attractive opportunity for drug design. Pseudoenzymes are inactive counterparts of classical enzymes and have evolved in all kingdoms of life, where they regulate a vast array of biological processes. The pseudokinases are one of the best-studied families of human pseudoenzymes. Eukaryotic TRIB pseudokinases evolved from a common ancestor (the human TRIB2 homolog), and contain a highly atypical pseudokinase domain fused to a unique docking site in an extended C tail that binds to ubiquitin E3 ligases. TRIB evolution has led to the appearance of three mammalian TRIB pseudokinases, termed TRIB1, TRIB2, and TRIB3, which contain both unique and shared features. In cells, TRIB pseudokinases act as modulators of substrate ubiquitination and as molecular scaffolds for the assembly and regulation of signaling modules, including the C/EBPα transcription factor and AKT and ERK networks. TRIB1 and TRIB2 have potent oncogenic activities in vertebrate cells, and recent evidence also suggests that TRIB2 acts as a tumour suppressor, consistent with the requirement for balanced TRIB signaling in the regulation of transcription, differentiation, proliferation, and apoptosis.
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Affiliation(s)
- Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK.
| | - Karen Keeshan
- Paul O'Gorman Leukemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 0YN, UK.
| | - Natarajan Kannan
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA; Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
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24
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Velasco G. The complex relationship of Tribbles pseudokinase 1, PML/RARA and C/EBPα in leukemia: two possible couples but not a trio. Haematologica 2016; 101:1129-1130. [PMID: 27694499 DOI: 10.3324/haematol.2016.151654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Guillermo Velasco
- Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, Madrid, Spain Instituto de Investigaciones Sanitarias San Carlos (IdISSC), Madrid, Spain
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25
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Guan H, Shuaib A, Leon DDD, Angyal A, Salazar M, Velasco G, Holcombe M, Dower SK, Kiss-Toth E. Competition between members of the tribbles pseudokinase protein family shapes their interactions with mitogen activated protein kinase pathways. Sci Rep 2016; 6:32667. [PMID: 27600771 PMCID: PMC5013389 DOI: 10.1038/srep32667] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/11/2016] [Indexed: 02/07/2023] Open
Abstract
Spatio-temporal regulation of intracellular signalling networks is key to normal cellular physiology; dysregulation of which leads to disease. The family of three mammalian tribbles proteins has emerged as an important controller of signalling via regulating the activity of mitogen activated protein kinases (MAPK), the PI3-kinase induced signalling network and E3 ubiquitin ligases. However, the importance of potential redundancy in the action of tribbles and how the differences in affinities for the various binding partners may influence signalling control is currently unclear. We report that tribbles proteins can bind to an overlapping set of MAPK-kinases (MAPKK) in live cells and dictate the localisation of the complexes. Binding studies in transfected cells reveal common regulatory mechanisms and suggest that tribbles and MAPKs may interact with MAPKKs in a competitive manner. Computational modelling of the impact of tribbles on MAPK activation suggests a high sensitivity of this system to changes in tribbles levels, highlighting that these proteins are ideally placed to control the dynamics and balance of activation of concurrent signalling pathways.
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Affiliation(s)
- Hongtao Guan
- Department of Infection, Immunity &Cardiovascular Disease, University of Sheffield, Beech Hill road, Sheffield, S10 2RX, United Kingdom
| | - Aban Shuaib
- Department of Infection, Immunity &Cardiovascular Disease, University of Sheffield, Beech Hill road, Sheffield, S10 2RX, United Kingdom
| | - David Davila De Leon
- Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, Madrid, Spain
| | - Adrienn Angyal
- Department of Infection, Immunity &Cardiovascular Disease, University of Sheffield, Beech Hill road, Sheffield, S10 2RX, United Kingdom
| | - Maria Salazar
- Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, Madrid, Spain
| | - Guillermo Velasco
- Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Mike Holcombe
- Department of Computer Science, University of Sheffield, Beech Hill road, Sheffield, S10 2RX, United Kingdom
| | - Steven K Dower
- Department of Infection, Immunity &Cardiovascular Disease, University of Sheffield, Beech Hill road, Sheffield, S10 2RX, United Kingdom.,Bio21 Biotechnology Institute, University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia.,CSL Limited, 45 Poplar Rd, Parkville, Victoria 3052, Australia
| | - Endre Kiss-Toth
- Department of Infection, Immunity &Cardiovascular Disease, University of Sheffield, Beech Hill road, Sheffield, S10 2RX, United Kingdom
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26
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Abstract
The protein tribbles-1, encoded by the gene TRIB1, is increasingly recognized as a major regulator of multiple cellular and physiological processes in humans. Recent human genetic studies, as well as molecular biological approaches, have implicated this intriguing protein in the aetiology of multiple human diseases, including myeloid leukaemia, Crohn's disease, non-alcoholic fatty liver disease (NAFLD), dyslipidaemia and coronary artery disease (CAD). Genome-wide association studies (GWAS) have repeatedly identified variants at the genomic TRIB1 locus as being significantly associated with multiple plasma lipid traits and cardiovascular disease (CVD) in humans. The involvement of TRIB1 in hepatic lipid metabolism has been validated through viral-mediated hepatic overexpression of the gene in mice; increasing levels of TRIB1 decreased plasma lipids in a dose-dependent manner. Additional studies have implicated TRIB1 in the regulation of hepatic lipogenesis and NAFLD. The exact mechanisms of TRIB1 regulation of both plasma lipids and hepatic lipogenesis remain undetermined, although multiple signalling pathways and transcription factors have been implicated in tribbles-1 function. Recent reports have been aimed at developing TRIB1-based lipid therapeutics. In summary, tribbles-1 is an important modulator of human energy metabolism and metabolic syndromes and worthy of future studies aimed at investigating its potential as a therapeutic target.
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27
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Abstract
The pseudo-kinase family of tribbles (TRIB) proteins has been linked to a variety of cell signalling pathways and appears to have functionally divergent roles with respect to intracellular protein degradation and the ability to regulate signal transduction pathways. In the arthritides, inflammation and a wide variety of pro-inflammatory pathways have been implicated to drive the cartilage destruction and consequent disability associated with both rheumatoid arthritis (RA) and osteoarthritis (OA). Despite burgeoning evidence linking the TRIB to inflammation-related pathologies such as diabetes, multiple sclerosis and cancer, very little is known about their roles in arthritis. The present review discusses current knowledge of the impact of TRIB on pro-inflammatory cellular mechanisms and pathways known to be important in the pathogenesis of RA and OA.
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28
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Abstract
The tribbles protein family, an evolutionarily conserved group of pseudokinases, have been shown to regulate multiple cellular events including those involved in normal and malignant haematopoiesis. The three mammalian Tribbles homologues, Trib1, Trib2 and Trib3 are characterized by conserved motifs, including a pseudokinase domain and a C-terminal E3 ligase-binding domain. In this review, we focus on the role of Trib (mammalian Tribbles homologues) proteins in mammalian haematopoiesis and leukaemia. The Trib proteins show divergent expression in haematopoietic cells, probably indicating cell-specific functions. The roles of the Trib proteins in oncogenesis are also varied and appear to be tissue-specific. Finally, we discuss the potential mechanisms by which the Trib proteins preferentially regulate these processes in multiple cell types.
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29
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Abstract
TRIB1, a homolog of Drosophila Tribbles, regulates the stability of transcription factors through physical interaction with the ubiquitin E3 ligase COP1. In this issue of Structure, Murphy et al. (2015) report the first X-ray analysis of the TRIB1 pseudokinase domain and its C-terminal COP1-binding extension.
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Affiliation(s)
- Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
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Keeshan K, Vieugué P, Chaudhury S, Rishi L, Gaillard C, Liang L, Garcia E, Nakamura T, Omidvar N, Kogan SC. Co-operative leukemogenesis in acute myeloid leukemia and acute promyelocytic leukemia reveals C/EBPα as a common target of TRIB1 and PML/RARA. Haematologica 2016; 101:1228-1236. [PMID: 27390356 DOI: 10.3324/haematol.2015.138503] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 06/24/2016] [Indexed: 12/22/2022] Open
Abstract
The PML/RARA fusion protein occurs as a result of the t(15;17) translocation in the acute promyelocytic leukemia subtype of human acute myeloid leukemia. Gain of chromosome 8 is the most common chromosomal gain in human acute myeloid leukemia, including acute promyelocytic leukemia. We previously demonstrated that gain of chromosome 8-containing MYC is of central importance in trisomy 8, but the role of the nearby TRIB1 gene has not been experimentally addressed in this context. We have now tested the hypothesis that both MYC and TRIB1 have functional roles underlying leukemogenesis of trisomy 8 by using retroviral vectors to express MYC and TRIB1 in wild-type bone marrow and in marrow that expressed a PML/RARA transgene. Interestingly, although MYC and TRIB1 readily co-operated in leukemogenesis for wild-type bone marrow, TRIB1 provided no selective advantage to cells expressing PML/RARA. We hypothesized that this lack of co-operation between PML/RARA and TRIB1 reflected a common pathway for their effect: both proteins targeting the myeloid transcription factor C/EBPα. In support of this idea, TRIB1 expression abrogated the all-trans retinoic acid response of acute promyelocytic leukemia cells in vitro and in vivo Our data delineate the common and redundant inhibitory effects of TRIB1 and PML/RARA on C/EBPα providing a potential explanation for the lack of selection of TRIB1 in human acute promyelocytic leukemia, and highlighting the key role of C/EBPs in acute promyelocytic leukemia pathogenesis and therapeutic response. In addition, the co-operativity we observed between MYC and TRIB1 in the absence of PML/RARA show that, outside of acute promyelocytic leukemia, gain of both genes may drive selection for trisomy 8.
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Affiliation(s)
- Karen Keeshan
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, UK
| | - Pauline Vieugué
- Department of Laboratory Medicine, University of California San Francisco, CA, USA
| | - Shahzya Chaudhury
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, UK
| | - Loveena Rishi
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, UK
| | - Coline Gaillard
- Department of Laboratory Medicine, University of California San Francisco, CA, USA
| | - Lu Liang
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, UK
| | - Elaine Garcia
- Department of Laboratory Medicine, University of California San Francisco, CA, USA
| | - Takuro Nakamura
- Division of Carcinogenesis, The Cancer Institute, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Nader Omidvar
- Department of Haematology, School of Medicine, Cardiff University, UK
| | - Scott C Kogan
- Department of Laboratory Medicine, University of California San Francisco, CA, USA
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Miyajima C, Itoh Y, Inoue Y, Hayashi H. Positive Regulation of Interleukin-2 Expression by a Pseudokinase, Tribbles 1, in Activated T Cells. Biol Pharm Bull 2016; 38:1126-33. [PMID: 26235576 DOI: 10.1248/bpb.b15-00002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tribbles 1 (TRB1), a member of the Tribbles family, is a pseudokinase that is conserved among species and implicated in various human diseases including leukemia, cardiovascular diseases, and metabolic disorders. However, the role of TRB1 in the immune response is not understood. To evaluate this role, we examined regulation of TRB1 expression and the function of TRB1 in interleukin-2 (IL-2) induction in Jurkat cells, a human acute T cell leukemia cell line. We found that TRB1 was strongly induced by phorbol 12-myristate 13-acetate (PMA) and ionomycin in these cells. IL-2 expression was induced in Jurkat cells activated by PMA and ionomycin; however, knockdown of TRB1 resulted in decreased induction of IL-2. TRB1 null Jurkat cells established using the CRISPR/Cas9 system also showed reduction of IL-2 expression on PMA/ionomycin stimulation. TRB1 knockdown also markedly inhibited IL-2 promoter activation. To determine the mechanism of the stimulatory effect on IL-2 induction, we focused on histone deacetylases (HDACs), and found that HDAC1 preferentially interacts with TRB1. TRB1 suppressed the interaction of HDAC1 with nuclear factor of activated T cells 2 (NFAT2), which is a crucial transcription factor for IL-2 induction. These results indicate that TRB1 is a positive regulator of IL-2 induction in activated T cells.
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Affiliation(s)
- Chiharu Miyajima
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences, Nagoya City University
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Liang KL, O'Connor C, Veiga JP, McCarthy TV, Keeshan K. TRIB2 regulates normal and stress-induced thymocyte proliferation. Cell Discov 2016; 2:15050. [PMID: 27462446 PMCID: PMC4860960 DOI: 10.1038/celldisc.2015.50] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 12/10/2015] [Indexed: 12/12/2022] Open
Abstract
TRIB2, a serine/threonine pseudokinase identified as an oncogene, is expressed at high levels in the T-cell compartment of hematopoiesis. The proliferation of developing thymocytes is tightly controlled to prevent leukemic transformation of T cells. Here we examine Trib2 loss in murine hematopoiesis under steady state and proliferative stress conditions, including genotoxic and oncogenic stress. Trib2−/− developing thymocytes show increased proliferation, and Trib2−/− mice have significantly higher thymic cellularity at steady state. During stress hematopoiesis, Trib2−/− developing thymocytes undergo accelerated proliferation and demonstrate hypersensitivity to 5-fluorouracil (5-FU)-induced cell death. Despite the increased cell death post 5-FU-induced proliferative stress, Trib2−/− mice exhibit accelerated thymopoietic recovery post treatment due to increased cell division kinetics of developing thymocytes. The increased proliferation in Trib2−/− thymocytes was exacerbated under oncogenic stress. In an experimental murine T-cell acute lymphoblastic leukemia (T-ALL) model, Trib2−/− mice had reduced latency in vivo, which associated with impaired MAP kinase (MAPK) activation. High and low expression levels of Trib2 correlate with immature and mature subtypes of human T-ALL, respectively, and associate with MAPK. Thus, TRIB2 emerges as a novel regulator of thymocyte cellular proliferation, important for the thymopoietic response to genotoxic and oncogenic stress, and possessing tumor suppressor function.
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Affiliation(s)
- Kai Ling Liang
- Paul O'Gorman Leukemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK; School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Caitriona O'Connor
- Paul O'Gorman Leukemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow , Glasgow, UK
| | - J Pedro Veiga
- Paul O'Gorman Leukemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow , Glasgow, UK
| | - Tommie V McCarthy
- School of Biochemistry and Cell Biology, University College Cork , Cork, Ireland
| | - Karen Keeshan
- Paul O'Gorman Leukemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow , Glasgow, UK
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Inhibition of tribbles protein-1 attenuates radioresistance in human glioma cells. Sci Rep 2015; 5:15961. [PMID: 26521947 PMCID: PMC4629151 DOI: 10.1038/srep15961] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 10/05/2015] [Indexed: 12/21/2022] Open
Abstract
Radiotherapy is one of the remedies in the treatment of glioma. The radioresistance is a major drawback, of which the mechanism is unclear. Tribble protein and histone deacetylase are involved in the cancer pathogenesis. This study aims to test a hypothesis that the histone deacetylase inhibitors attenuate the radioresistance in human glioma cells. In this study, human glioma cells were cultured. The cells were treated with irradiation with or without a histone deacetylase inhibitor, butyrate. Apoptosis of the glioma cells was assessed by flow cytometry. The results showed that human glioma cells expressed a low level of Trib1, which was significantly up regulated by exposure to small doses (2 Gy/day for 4 days) of irradiation. Trib1-deficient glioma cells showed an enhanced response to irradiation-induced apoptosis. Exposure to small doses of irradiation, Trib1 formed a complex with pHDAC1 (phosphor histone deacetylase-1) to inhibit p53 expression in glioma cells. The presence of HDAC1 inhibitor, butyrate or parthenolide, significantly enforced irradiation-induced glioma cell apoptosis. In conclusion, the Trib1 plays a critical role in the development of radioresistance of glioma cells. The data suggest that inhibition of Trib1 or HDAC1 has the potential to prevent or attenuate the radioresistance.
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Tribbles pseudokinases: novel targets for chemical biology and drug discovery? Biochem Soc Trans 2015; 43:1095-103. [DOI: 10.1042/bst20150109] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tribbles (TRIB) proteins are pseudokinase mediators of eukaryotic signalling that have evolved important roles in lipoprotein metabolism, immune function and cellular differentiation and proliferation. In addition, an evolutionary-conserved modulation of PI3K/AKT signalling pathways highlights them as novel and rather unusual pharmaceutical targets. The three human TRIB family members are uniquely defined by an acidic pseudokinase domain containing a ‘broken’ α C-helix and a MEK (MAPK/ERK)-binding site at the end of the putative C-lobe and a distinct C-terminal peptide motif that interacts directly with a small subset of cellular E3 ubiquitin ligases. This latter interaction drives proteasomal-dependent degradation of networks of transcription factors, whose rate of turnover determines the biological attributes of individual TRIB family members. Defining the function of individual Tribs has been made possible through evaluation of individual TRIB knockout mice, siRNA/overexpression approaches and genetic screening in flies, where the single TRIB gene was originally described 15 years ago. The rapidly maturing TRIB field is primed to exploit chemical biology approaches to evaluate endogenous TRIB signalling events in intact cells. This will help define how TRIB-driven protein–protein interactions and the atypical TRIB ATP-binding site, fit into cellular signalling modules in experimental scenarios where TRIB-signalling complexes remain unperturbed. In this mini-review, we discuss how small molecules can reveal rate-limiting signalling outputs and functions of Tribs in cells and intact organisms, perhaps serving as guides for the development of new drugs. We predict that appropriate small molecule TRIB ligands will further accelerate the transition of TRIB pseudokinase analysis into the mainstream of cell signalling.
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Schrade A, Kyrönlahti A, Akinrinade O, Pihlajoki M, Häkkinen M, Fischer S, Alastalo TP, Velagapudi V, Toppari J, Wilson DB, Heikinheimo M. GATA4 is a key regulator of steroidogenesis and glycolysis in mouse Leydig cells. Endocrinology 2015; 156:1860-72. [PMID: 25668067 PMCID: PMC4398762 DOI: 10.1210/en.2014-1931] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Transcription factor GATA4 is expressed in somatic cells of the mammalian testis. Gene targeting studies in mice have shown that GATA4 is essential for proper differentiation and function of Sertoli cells. The role of GATA4 in Leydig cell development, however, remains controversial, because targeted mutagenesis experiments in mice have not shown a consistent phenotype, possibly due to context-dependent effects or compensatory responses. We therefore undertook a reductionist approach to study the function of GATA4 in Leydig cells. Using microarray analysis and quantitative RT-PCR, we identified a set of genes that are down-regulated or up-regulated after small interfering RNA (siRNA)-mediated silencing of Gata4 in the murine Leydig tumor cell line mLTC-1. These same genes were dysregulated when primary cultures of Gata4(flox/flox) adult Leydig cells were subjected to adenovirus-mediated cre-lox recombination in vitro. Among the down-regulated genes were enzymes of the androgen biosynthetic pathway (Cyp11a1, Hsd3b1, Cyp17a1, and Srd5a). Silencing of Gata4 expression in mLTC-1 cells was accompanied by reduced production of sex steroid precursors, as documented by mass spectrometric analysis. Comprehensive metabolomic analysis of GATA4-deficient mLTC-1 cells showed alteration of other metabolic pathways, notably glycolysis. GATA4-depleted mLTC-1 cells had reduced expression of glycolytic genes (Hk1, Gpi1, Pfkp, and Pgam1), lower intracellular levels of ATP, and increased extracellular levels of glucose. Our findings suggest that GATA4 plays a pivotal role in Leydig cell function and provide novel insights into metabolic regulation in this cell type.
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Affiliation(s)
- Anja Schrade
- Children's Hospital (A.S., A.K., O.A., M.P., T.-P.A., M.H.), University of Helsinki, Helsinki 00014, Finland; Institute of Biomedicine (O.A.), University of Helsinki, Helsinki 00014, Finland; School of Pharmacy (M.H.), University of Eastern Finland, Kuopio 70211, Finland; Institute of Applied Biotechnology (S.F.), University of Applied Sciences Biberach, Biberach 88400, Germany; Metabolomics Unit (V.V.), Institute for Molecular Medicine Finland, University of Helsinki 00014, Helsinki, Finland; Departments of Physiology and Pediatrics (J.T.), University of Turku, Turku 20520, Finland; and Departments of Pediatrics (A.S., M.P., D.B.W., M.H.) and Developmental Biology (D.B.W.), Washington University in St. Louis, St. Louis, Missouri 63110
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Modulators of hepatic lipoprotein metabolism identified in a search for small-molecule inducers of tribbles pseudokinase 1 expression. PLoS One 2015; 10:e0120295. [PMID: 25811180 PMCID: PMC4374785 DOI: 10.1371/journal.pone.0120295] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 01/28/2015] [Indexed: 12/04/2022] Open
Abstract
Recent genome wide association studies have linked tribbles pseudokinase 1 (TRIB1) to the risk of coronary artery disease (CAD). Based on the observations that increased expression of TRIB1 reduces secretion of VLDL and is associated with lower plasma levels of LDL cholesterol and triglycerides, higher plasma levels of HDL cholesterol and reduced risk for myocardial infarction, we carried out a high throughput phenotypic screen based on quantitative RT-PCR assay to identify compounds that induce TRIB1 expression in human HepG2 hepatoma cells. In a screen of a collection of diversity-oriented synthesis (DOS)-derived compounds, we identified a series of benzofuran-based compounds that upregulate TRIB1 expression and phenocopy the effects of TRIB1 cDNA overexpression, as they inhibit triglyceride synthesis and apoB secretion in cells. In addition, the compounds downregulate expression of MTTP and APOC3, key components of the lipoprotein assembly pathway. However, CRISPR-Cas9 induced chromosomal disruption of the TRIB1 locus in HepG2 cells, while confirming its regulatory role in lipoprotein metabolism, demonstrated that the effects of benzofurans persist in TRIB1-null cells indicating that TRIB1 is sufficient but not necessary to transmit the effects of the drug. Remarkably, active benzofurans, as well as natural products capable of TRIB1 upregulation, also modulate hepatic cell cholesterol metabolism by elevating the expression of LDLR transcript and LDL receptor protein, while reducing the levels of PCSK9 transcript and secreted PCSK9 protein and stimulating LDL uptake. The effects of benzofurans are not masked by cholesterol depletion and are independent of the SREBP-2 regulatory circuit, indicating that these compounds represent a novel class of chemically tractable small-molecule modulators that shift cellular lipoprotein metabolism in HepG2 cells from lipogenesis to scavenging.
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Friedman AD. C/EBPα in normal and malignant myelopoiesis. Int J Hematol 2015; 101:330-41. [PMID: 25753223 DOI: 10.1007/s12185-015-1764-6] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 02/18/2015] [Accepted: 02/19/2015] [Indexed: 12/22/2022]
Abstract
CCAAT/enhancer binding protein α (C/EBPα) dimerizes via its leucine zipper (LZ) domain to bind DNA via its basic region and activate transcription via N-terminal trans-activation domains. The activity of C/EBPα is modulated by several serine/threonine kinases and via sumoylation, its gene is activated by RUNX1 and additional transcription factors, its mRNA stability is modified by miRNAs, and its mRNA is subject to translation control that affects AUG selection. In addition to inducing differentiation, C/EBPα inhibits cell cycle progression and apoptosis. Within hematopoiesis, C/EBPα levels increase as long-term stem cells progress to granulocyte-monocyte progenitors (GMP). Absence of C/EBPα prevents GMP formation, and higher levels are required for granulopoiesis compared to monopoiesis. C/EBPα interacts with AP-1 proteins to bind hybrid DNA elements during monopoiesis, and induction of Gfi-1, C/EBPε, KLF5, and miR-223 by C/EBPα enables granulopoiesis. The CEBPA ORF is mutated in approximately 10 % of acute myeloid leukemias (AML), leading to expression of N-terminally truncated C/EBPαp30 and C-terminal, in-frame C/EBPαLZ variants, which inhibit C/EBPα activities but also play additional roles during myeloid transformation. RUNX1 mutation, CEBPA promoter methylation, Trib1 or Trib2-mediated C/EBPαp42 degradation, and signaling pathways leading to C/EBPα serine 21 phosphorylation reduce C/EBPα expression or activity in additional AML cases.
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Affiliation(s)
- Alan D Friedman
- Division of Pediatric Oncology, Johns Hopkins University, Cancer Research Building I, Room 253, 1650 Orleans Street, Baltimore, MD, 21231, USA,
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Kuivenhoven JA, Groen AK. Beyond the genetics of HDL: why is HDL cholesterol inversely related to cardiovascular disease? Handb Exp Pharmacol 2015; 224:285-300. [PMID: 25522992 DOI: 10.1007/978-3-319-09665-0_8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
There is unequivocal evidence that high-density lipoprotein (HDL) cholesterol levels in plasma are inversely associated with the risk of cardiovascular disease (CVD). Studies of families with inherited HDL disorders and genetic association studies in general (and patient) population samples have identified a large number of factors that control HDL cholesterol levels. However, they have not resolved why HDL cholesterol and CVD are inversely related. A growing body of evidence from nongenetic studies shows that HDL in patients at increased risk of CVD has lost its protective properties and that increasing the cholesterol content of HDL does not result in the desired effects. Hopefully, these insights can help improve strategies to successfully intervene in HDL metabolism. It is clear that there is a need to revisit the HDL hypothesis in an unbiased manner. True insights into the molecular mechanisms that regulate plasma HDL cholesterol and triglycerides or control HDL function could provide the handholds that are needed to develop treatment for, e.g., type 2 diabetes and the metabolic syndrome. Especially genome-wide association studies have provided many candidate genes for such studies. In this review we have tried to cover the main molecular studies that have been produced over the past few years. It is clear that we are only at the very start of understanding how the newly identified factors may control HDL metabolism. In addition, the most recent findings underscore the intricate relations between HDL, triglyceride, and glucose metabolism indicating that these parameters need to be studied simultaneously.
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Affiliation(s)
- J A Kuivenhoven
- Department of Pediatrics, Section Molecular Genetics, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713GZ, Groningen, The Netherlands,
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Palagani A, Op de Beeck K, Naulaerts S, Diddens J, Sekhar Chirumamilla C, Van Camp G, Laukens K, Heyninck K, Gerlo S, Mestdagh P, Vandesompele J, Berghe WV. Ectopic microRNA-150-5p transcription sensitizes glucocorticoid therapy response in MM1S multiple myeloma cells but fails to overcome hormone therapy resistance in MM1R cells. PLoS One 2014; 9:e113842. [PMID: 25474406 PMCID: PMC4256227 DOI: 10.1371/journal.pone.0113842] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 11/01/2014] [Indexed: 11/18/2022] Open
Abstract
Glucocorticoids (GCs) selectively trigger cell death in the multiple myeloma cell line MM1S which express NR3C1/Glucocorticoid Receptor (GR) protein, but fail to kill MM1R cells which lack GR protein. Given recent demonstrations of altered microRNA profiles in a diverse range of haematological malignancies and drug resistance, we characterized GC inducible mRNA and microRNA transcription profiles in GC sensitive MM1S as compared to GC resistant MM1R cells. Transcriptome analysis revealed that GCs regulate expression of multiple genes involved in cell cycle control, cell organization, cell death and immunological disease in MM1S cells, which remain unaffected in MM1R cells. With respect to microRNAs, mir-150-5p was identified as the most time persistent GC regulated microRNA, out of 5 QPCR validated microRNAs (mir-26b, mir-125a-5p, mir-146-5p, mir-150-5p, and mir-184), which are GC inducible in MM1S but not in MM1R cells. Functional studies further revealed that ectopic transfection of a synthetic mir-150-5p mimics GR dependent gene expression changes involved in cell death and cell proliferation pathways. Remarkably, despite the gene expression changes observed, overexpression of mir-150-5p in absence of GCs did not trigger significant cytotoxicity in MM1S or MM1R cells. This suggests the requirement of additional steps in GC induced cell death, which can not be mimicked by mir-150-5p overexpression alone. Interestingly, a combination of mir-150-5p transfection with low doses GC in MM1S cells was found to sensitize therapy response, whereas opposite effects could be observed with a mir-150-5p specific antagomir. Although mir-150-5p overexpression did not substantially change GR expression levels, it was found that mir-150-5p evokes GR specific effects through indirect mRNA regulation of GR interacting transcription factors and hormone receptors, GR chaperones, as well as various effectors of unfolded protein stress and chemokine signalling. Altogether GC-inducible mir-150-5p adds another level of regulation to GC specific therapeutic responses in multiple myeloma.
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Affiliation(s)
- Ajay Palagani
- Laboratory of Protein Chemistry, Proteomics and Epigenetic Signalling (PPES), Department of Biomedical Sciences, University of Antwerp (UA), Antwerp, Belgium
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Physiology, Ghent University, Ghent, Belgium
| | - Ken Op de Beeck
- Center of Medical Genetics, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- Laboratory of Cancer Research and Clinical Oncology, Department of Medical Oncology, University of Antwerp/Antwerp University Hospital, Antwerp, Belgium
| | - Stefan Naulaerts
- Biomedical Informatics Research Center Antwerp (Biomina), University of Antwerp & University Hospital Antwerp, Antwerp, Belgium
- Advanced Database Research and Modelling (ADReM), Department of Mathematics & Computer sciences, University of Antwerp (UA), Antwerp, Belgium
| | - Jolien Diddens
- Laboratory of Protein Chemistry, Proteomics and Epigenetic Signalling (PPES), Department of Biomedical Sciences, University of Antwerp (UA), Antwerp, Belgium
| | - Chandra Sekhar Chirumamilla
- Laboratory of Protein Chemistry, Proteomics and Epigenetic Signalling (PPES), Department of Biomedical Sciences, University of Antwerp (UA), Antwerp, Belgium
| | - Guy Van Camp
- Center of Medical Genetics, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Kris Laukens
- Biomedical Informatics Research Center Antwerp (Biomina), University of Antwerp & University Hospital Antwerp, Antwerp, Belgium
- Advanced Database Research and Modelling (ADReM), Department of Mathematics & Computer sciences, University of Antwerp (UA), Antwerp, Belgium
| | - Karen Heyninck
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Physiology, Ghent University, Ghent, Belgium
| | - Sarah Gerlo
- VIB-UGent Department of Medical Protein Research, Ghent, Belgium
| | - Pieter Mestdagh
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Joke Vandesompele
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Wim Vanden Berghe
- Laboratory of Protein Chemistry, Proteomics and Epigenetic Signalling (PPES), Department of Biomedical Sciences, University of Antwerp (UA), Antwerp, Belgium
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Physiology, Ghent University, Ghent, Belgium
- * E-mail:
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Novel approaches for targeting kinases: allosteric inhibition, allosteric activation and pseudokinases. Future Med Chem 2014; 6:541-61. [PMID: 24649957 DOI: 10.4155/fmc.13.216] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Protein kinases are involved in many essential cellular processes and their deregulation can lead to a variety of diseases, including cancer. The pharmaceutical industry has invested heavily in the identification of kinase inhibitors to modulate these disease-promoting pathways, resulting in several successful drugs. However, the field is challenging as it is difficult to identify novel selective inhibitors with good pharmacokinetic/pharmacodynamic properties. In addition, resistance to kinase inhibitor treatment frequently arises. The identification of non-ATP site targeting ('allosteric') inhibitors, the identification of kinase activators and the expansion of kinase target space to include the less studied members of the family, including atypical- and pseudo-kinases, are potential avenues to overcome these challenges. In this perspective, the opportunities and challenges of following these approaches and others will be discussed.
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Wong YF, Micklem CN, Taguchi M, Itonaga H, Sawayama Y, Imanishi D, Nishikawa S, Miyazaki Y, Jakt LM. Longitudinal Analysis of DNA Methylation in CD34+ Hematopoietic Progenitors in Myelodysplastic Syndrome. Stem Cells Transl Med 2014; 3:1188-98. [PMID: 25122688 DOI: 10.5966/sctm.2014-0035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Myelodysplastic syndrome (MDS) is a disorder of hematopoietic stem cells (HSCs) that is often treated with DNA methyltransferase 1 (DNMT1) inhibitors (5-azacytidine [AZA], 5-aza-2'-deoxycytidine), suggesting a role for DNA methylation in disease progression. How DNMT inhibition retards disease progression and how DNA methylation contributes to MDS remain unclear. We analyzed global DNA methylation in purified CD34+ hematopoietic progenitors from MDS patients undergoing multiple rounds of AZA treatment. Differential methylation between MDS phenotypes was observed primarily at developmental regulators not expressed within the hematopoietic compartment and was distinct from that observed between healthy hematopoietic cell types. After AZA treatment, we observed only limited DNA demethylation at sites that varied between patients. This suggests that a subset of the stem cell population is resistant to AZA and provides a basis for disease relapse. Using gene expression data from patient samples and an in vitro AZA treatment study, we identified differentially methylated genes that can be activated following treatment and that remain silent in the CD34+ stem cell compartment of high-risk MDS patients. Haploinsufficiency in mice of one of these genes (NR4A2) has been shown to lead to excessive HSC proliferation, and our data suggest that suppression of NR4A2 by DNA methylation may be involved in MDS progression.
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Affiliation(s)
- Yan-Fung Wong
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
| | - Chris N Micklem
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
| | - Masataka Taguchi
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
| | - Hidehiro Itonaga
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
| | - Yasushi Sawayama
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
| | - Daisuke Imanishi
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
| | - Shinichi Nishikawa
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
| | - Yasushi Miyazaki
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
| | - Lars Martin Jakt
- Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; Department of Hematology, Atomic Bomb Disease and Hibakusya Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; The Danish Stem Cell Centre (DanStem), University of Copenhagen, Copenhagen, Denmark; Imperial College London, London, United Kingdom; All About Science Japan, Kobe, Japan; Department of Systems Medicine, Mitsunada Sakaguchi Laboratory, Keio University School of Medicine, Institute of Integrated Medical Research, Tokyo, Japan
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Abstract
The loss of regulation of cell proliferation is a key event in leukemic transformation, and the oncogene tribbles (Trib)2 is emerging as a pivotal target of transcription factors in acute leukemias. Deregulation of the transcription factor E2F1, normally repressed by CCAAT enhancer-binding protein α (C/EBPα)-p42, occurs in acute myeloid leukemia (AML), resulting in the perturbation of cell cycle and apoptosis, emphasizing its importance in the molecular pathogenesis of AML. Here we show that E2F family members directly regulate Trib2 in leukemic cells and identify a feedback regulatory loop for E2F1, C/EBPα, and Trib2 in AML cell proliferation and survival. Further analyses revealed that E2F1-mediated Trib2 expression was repressed by C/EBPα-p42, and in normal granulocyte/macrophage progenitor cells, we detect C/EBPα bound to the Trib2 promoter. Pharmacological inhibition of the cell cycle or Trib2 knockdown resulted in a block in AML cell proliferation. Our work proposes a novel paradigm whereby E2F1 plays a key role in the regulation of Trib2 expression important for AML cell proliferation control. Importantly, we identify the contribution of dysregulated C/EBPα and E2F1 to elevated Trib2 expression and leukemic cell survival, which likely contributes to the initiation and maintenance of AML and may have significant implications for normal and malignant hematopoiesis.
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Abstract
Tribbles are members of the pseudokinase family of proteins, with no associated kinase activity detectable to date. As tribbles appear not to function as kinases, there has been debate surrounding their functional classification. Tribbles have been proposed to function as adaptor molecules facilitating degradation of their target proteins. Tribbles have also been proposed to mediate signalling changes to MAPK (mitogen-activated protein kinase) cascades and also to function as decoy kinases interfering with the activity of known kinases. The present review discusses the functionally divergent roles of tribbles as molecular adaptors mediating degradation, changes to signalling cascades and action as decoy kinases.
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Cunard R. Mammalian tribbles homologs at the crossroads of endoplasmic reticulum stress and Mammalian target of rapamycin pathways. SCIENTIFICA 2013; 2013:750871. [PMID: 24490110 PMCID: PMC3892554 DOI: 10.1155/2013/750871] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 11/20/2013] [Indexed: 05/03/2023]
Abstract
In 2000, investigators discovered Tribbles, a Drosophila protein that coordinates morphogenesis by inhibiting mitosis. Further work has delineated Xenopus (Xtrb2), Nematode (Nipi-3), and mammalian homologs of Drosophila tribbles, which include TRB1, TRB2, and TRB3. The sequences of tribbles homologs are highly conserved, and despite their protein kinase structure, to date they have not been shown to have kinase activity. TRB family members play a role in the differentiation of macrophages, lymphocytes, muscle cells, adipocytes, and osteoblasts. TRB isoforms also coordinate a number of critical cellular processes including glucose and lipid metabolism, inflammation, cellular stress, survival, apoptosis, and tumorigenesis. TRB family members modulate multiple complex signaling networks including mitogen activated protein kinase cascades, protein kinase B/AKT signaling, mammalian target of rapamycin, and inflammatory pathways. The following review will discuss metazoan homologs of Drosophila tribbles, their structure, expression patterns, and functions. In particular, we will focus on TRB3 function in the kidney in podocytes. This review will also discuss the key signaling pathways with which tribbles proteins interact and provide a rationale for developing novel therapeutics that exploit these interactions to provide better treatment options for both acute and chronic kidney disease.
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Affiliation(s)
- Robyn Cunard
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, Mail Code 151, 3350 La Jolla Village Drive, San Diego, CA 92161, USA
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- *Robyn Cunard:
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