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Alfano L, Iannuzzi CA, Barone D, Forte IM, Ragosta MC, Cuomo M, Mazzarotti G, Dell'Aquila M, Altieri A, Caporaso A, Roma C, Marra L, Boffo S, Indovina P, De Laurentiis M, Giordano A. CDK9-55 guides the anaphase-promoting complex/cyclosome (APC/C) in choosing the DNA repair pathway choice. Oncogene 2024; 43:1263-1273. [PMID: 38433256 DOI: 10.1038/s41388-024-02982-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 02/08/2024] [Accepted: 02/13/2024] [Indexed: 03/05/2024]
Abstract
DNA double-strand breaks (DSBs) contribute to genome instability, a key feature of cancer. DSBs are mainly repaired by homologous recombination (HR) and non-homologous end-joining (NHEJ). We investigated the role of an isoform of the multifunctional cyclin-dependent kinase 9, CDK9-55, in DNA repair, by generating CDK9-55-knockout HeLa clones (through CRISPR-Cas9), which showed potential HR dysfunction. A phosphoproteomic screening in these clones treated with camptothecin revealed that CDC23 (cell division cycle 23), a component of the E3-ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome), is a new substrate of CDK9-55, with S588 being its putative phosphorylation site. Mutated non-phosphorylatable CDC23(S588A) affected the repair pathway choice by impairing HR and favouring error-prone NHEJ. This CDK9 role should be considered when designing CDK-inhibitor-based cancer therapies.
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Affiliation(s)
- Luigi Alfano
- Cell Biology and Biotherapy Unit, Istituto Nazionale Tumori-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS)-Fondazione G. Pascale, Napoli, Italy.
| | - Carmelina Antonella Iannuzzi
- Cell Biology and Biotherapy Unit, Istituto Nazionale Tumori-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS)-Fondazione G. Pascale, Napoli, Italy
| | - Daniela Barone
- Cell Biology and Biotherapy Unit, Istituto Nazionale Tumori-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS)-Fondazione G. Pascale, Napoli, Italy
| | - Iris Maria Forte
- Breast Unit, Istituto Nazionale Tumori-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS)-Fondazione G. Pascale, Napoli, Italy
| | | | - Maria Cuomo
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Giulio Mazzarotti
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Milena Dell'Aquila
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA
| | - Angela Altieri
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA
| | - Antonella Caporaso
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA
| | - Cristin Roma
- Cell Biology and Biotherapy Unit, Istituto Nazionale Tumori-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS)-Fondazione G. Pascale, Napoli, Italy
| | - Laura Marra
- Cell Biology and Biotherapy Unit, Istituto Nazionale Tumori-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS)-Fondazione G. Pascale, Napoli, Italy
| | - Silvia Boffo
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA
| | - Paola Indovina
- Sbarro Research Health Organization, Candiolo, Torino, Italy
| | - Michelino De Laurentiis
- Breast Unit, Istituto Nazionale Tumori-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS)-Fondazione G. Pascale, Napoli, Italy
| | - Antonio Giordano
- Department of Medical Biotechnologies, University of Siena, Siena, Italy.
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA.
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2
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Koirala M, DiPaola M. Targeting CDK9 in Cancer: An Integrated Approach of Combining In Silico Screening with Experimental Validation for Novel Degraders. Curr Issues Mol Biol 2024; 46:1713-1730. [PMID: 38534727 DOI: 10.3390/cimb46030111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/08/2024] [Accepted: 02/20/2024] [Indexed: 03/28/2024] Open
Abstract
The persistent threat of cancer remains a significant hurdle for global health, prompting the exploration of innovative approaches in the quest for successful therapeutic interventions. Cyclin-dependent kinase 9 (CDK9), a central player in transcription regulation and cell cycle progression, has emerged as a promising target to combat cancer. Its pivotal role in oncogenic pathways and the pressing need for novel cancer treatments has propelled CDK9 into the spotlight of drug discovery efforts. This article presents a comprehensive study that connects a multidisciplinary approach, combining computational methodologies, experimental validation, and the transformative Proteolysis-Targeting Chimera (PROTAC) technology. By uniting these diverse techniques, we aim to identify, characterize, and optimize a new class of degraders targeting CDK9. We explore these compounds for targeted protein degradation, offering a novel and potentially effective approach to cancer therapy. This cohesive strategy utilizes the combination of computational predictions and experimental insights, with the goal of advancing the development of effective anticancer therapeutics, targeting CDK9.
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Mandal R, Becker S, Strebhardt K. Targeting CDK9 for Anti-Cancer Therapeutics. Cancers (Basel) 2021; 13:2181. [PMID: 34062779 PMCID: PMC8124690 DOI: 10.3390/cancers13092181] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 12/23/2022] Open
Abstract
Cyclin Dependent Kinase 9 (CDK9) is one of the most important transcription regulatory members of the CDK family. In conjunction with its main cyclin partner-Cyclin T1, it forms the Positive Transcription Elongation Factor b (P-TEFb) whose primary function in eukaryotic cells is to mediate the positive transcription elongation of nascent mRNA strands, by phosphorylating the S2 residues of the YSPTSPS tandem repeats at the C-terminus domain (CTD) of RNA Polymerase II (RNAP II). To aid in this process, P-TEFb also simultaneously phosphorylates and inactivates a number of negative transcription regulators like 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) Sensitivity-Inducing Factor (DSIF) and Negative Elongation Factor (NELF). Significantly enhanced activity of CDK9 is observed in multiple cancer types, which is universally associated with significantly shortened Overall Survival (OS) of the patients. In these cancer types, CDK9 regulates a plethora of cellular functions including proliferation, survival, cell cycle regulation, DNA damage repair and metastasis. Due to the extremely critical role of CDK9 in cancer cells, inhibiting its functions has been the subject of intense research, resulting the development of multiple, increasingly specific small-molecule inhibitors, some of which are presently in clinical trials. The search for newer generation CDK9 inhibitors with higher specificity and lower potential toxicities and suitable combination therapies continues. In fact, the Phase I clinical trials of the latest, highly specific CDK9 inhibitor BAY1251152, against different solid tumors have shown good anti-tumor and on-target activities and pharmacokinetics, combined with manageable safety profile while the phase I and II clinical trials of another inhibitor AT-7519 have been undertaken or are undergoing. To enhance the effectiveness and target diversity and reduce potential drug-resistance, the future of CDK9 inhibition would likely involve combining CDK9 inhibitors with inhibitors like those against BRD4, SEC, MYC, MCL-1 and HSP90.
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Affiliation(s)
- Ranadip Mandal
- Department of Gynecology and Obstetrics, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; (R.M.); (S.B.)
| | - Sven Becker
- Department of Gynecology and Obstetrics, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; (R.M.); (S.B.)
| | - Klaus Strebhardt
- Department of Gynecology and Obstetrics, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; (R.M.); (S.B.)
- German Cancer Consortium (DKTK), 69120 Heidelberg, Germany
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4
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Riess C, Irmscher N, Salewski I, Strüder D, Classen CF, Große-Thie C, Junghanss C, Maletzki C. Cyclin-dependent kinase inhibitors in head and neck cancer and glioblastoma-backbone or add-on in immune-oncology? Cancer Metastasis Rev 2021; 40:153-171. [PMID: 33161487 PMCID: PMC7897202 DOI: 10.1007/s10555-020-09940-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022]
Abstract
Cyclin-dependent kinases (CDK) control the cell cycle and play a crucial role in oncogenesis. Pharmacologic inhibition of CDK has contributed to the recent clinical approval of dual CDK4/6 inhibitors for the treatment of breast and small cell lung cancer. While the anticancer cell effects of CDK inhibitors are well-established, preclinical and early clinical studies describe additional mechanisms of action such as chemo- and radiosensitization or immune stimulation. The latter offers great potential to incorporate CDK inhibitors in immune-based treatments. However, dosing schedules and accurate timing of each combination partner need to be respected to prevent immune escape and resistance. In this review, we provide a detailed summary of CDK inhibitors in the two solid cancer types head and neck cancer and glioblastoma multiforme; it describes the molecular mechanisms of response vs. resistance and covers strategies to avoid resistance by the combination of immunotherapy or targeted therapy.
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Affiliation(s)
- Christin Riess
- Department of Medicine, Clinic III - Hematology, Oncology and Palliative Care, Rostock University Medical Center, Rostock, Germany
- University Children's and Adolescents' Hospital, Rostock University Medical Center, Rostock, Germany
| | - Nina Irmscher
- Department of Medicine, Clinic III - Hematology, Oncology and Palliative Care, Rostock University Medical Center, Rostock, Germany
| | - Inken Salewski
- Department of Medicine, Clinic III - Hematology, Oncology and Palliative Care, Rostock University Medical Center, Rostock, Germany
| | - Daniel Strüder
- Department of Oto-Rhino-Laryngology, Head and Neck Surgery "Otto Körner", Rostock University Medical Center, Rostock, Germany
| | - Carl-Friedrich Classen
- University Children's and Adolescents' Hospital, Rostock University Medical Center, Rostock, Germany
| | - Christina Große-Thie
- Department of Medicine, Clinic III - Hematology, Oncology and Palliative Care, Rostock University Medical Center, Rostock, Germany
| | - Christian Junghanss
- Department of Medicine, Clinic III - Hematology, Oncology and Palliative Care, Rostock University Medical Center, Rostock, Germany
| | - Claudia Maletzki
- Department of Medicine, Clinic III - Hematology, Oncology and Palliative Care, Rostock University Medical Center, Rostock, Germany.
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5
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van den Heuvel D, Spruijt CG, González-Prieto R, Kragten A, Paulsen MT, Zhou D, Wu H, Apelt K, van der Weegen Y, Yang K, Dijk M, Daxinger L, Marteijn JA, Vertegaal ACO, Ljungman M, Vermeulen M, Luijsterburg MS. A CSB-PAF1C axis restores processive transcription elongation after DNA damage repair. Nat Commun 2021; 12:1342. [PMID: 33637760 PMCID: PMC7910549 DOI: 10.1038/s41467-021-21520-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 01/28/2021] [Indexed: 02/06/2023] Open
Abstract
Bulky DNA lesions in transcribed strands block RNA polymerase II (RNAPII) elongation and induce a genome-wide transcriptional arrest. The transcription-coupled repair (TCR) pathway efficiently removes transcription-blocking DNA lesions, but how transcription is restored in the genome following DNA repair remains unresolved. Here, we find that the TCR-specific CSB protein loads the PAF1 complex (PAF1C) onto RNAPII in promoter-proximal regions in response to DNA damage. Although dispensable for TCR-mediated repair, PAF1C is essential for transcription recovery after UV irradiation. We find that PAF1C promotes RNAPII pause release in promoter-proximal regions and subsequently acts as a processivity factor that stimulates transcription elongation throughout genes. Our findings expose the molecular basis for a non-canonical PAF1C-dependent pathway that restores transcription throughout the human genome after genotoxic stress. The transcription-coupled repair pathway removes transcription-blocking DNA lesions, but how transcription is restored following DNA repair is not clear. Here the authors reveal that the PAF1 complex, while dispensable for the repair process, restores transcription after DNA damage.
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Affiliation(s)
- Diana van den Heuvel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Cornelia G Spruijt
- Radboud Institute for Molecular Life Sciences, Oncode Institute, Radboud University Nijmegen, Nijmegen, The Netherlands.,Prinses Maxima Center, Utrecht, The Netherlands
| | - Román González-Prieto
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Angela Kragten
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Michelle T Paulsen
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Di Zhou
- Department of Molecular Genetics, Oncode Institute, Rotterdam, The Netherlands
| | - Haoyu Wu
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Katja Apelt
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Yana van der Weegen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Kevin Yang
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.,Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Madelon Dijk
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Lucia Daxinger
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Jurgen A Marteijn
- Department of Molecular Genetics, Oncode Institute, Rotterdam, The Netherlands
| | - Alfred C O Vertegaal
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Mats Ljungman
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.,Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Michiel Vermeulen
- Radboud Institute for Molecular Life Sciences, Oncode Institute, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Martijn S Luijsterburg
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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6
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Cellular and Molecular Mechanisms of R/S-Roscovitine and CDKs Related Inhibition under Both Focal and Global Cerebral Ischemia: A Focus on Neurovascular Unit and Immune Cells. Cells 2021; 10:cells10010104. [PMID: 33429982 PMCID: PMC7827530 DOI: 10.3390/cells10010104] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/29/2020] [Accepted: 01/05/2021] [Indexed: 12/29/2022] Open
Abstract
Ischemic stroke is the second leading cause of death worldwide. Following ischemic stroke, Neurovascular Unit (NVU) inflammation and peripheral leucocytes infiltration are major contributors to the extension of brain lesions. For a long time restricted to neurons, the 10 past years have shown the emergence of an increasing number of studies focusing on the role of Cyclin-Dependent Kinases (CDKs) on the other cells of NVU, as well as on the leucocytes. The most widely used CDKs inhibitor, (R)-roscovitine, and its (S) isomer both decreased brain lesions in models of global and focal cerebral ischemia. We previously showed that (S)-roscovitine acted, at least, by modulating NVU response to ischemia. Interestingly, roscovitine was shown to decrease leucocytes-mediated inflammation in several inflammatory models. Specific inhibition of roscovitine majors target CDK 1, 2, 5, 7, and 9 showed that these CDKs played key roles in inflammatory processes of NVU cells and leucocytes after brain lesions, including ischemic stroke. The data summarized here support the investigation of roscovitine as a potential therapeutic agent for the treatment of ischemic stroke, and provide an overview of CDK 1, 2, 5, 7, and 9 functions in brain cells and leucocytes during cerebral ischemia.
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CDK4/6 Inhibitors in Breast Cancer Treatment: Potential Interactions with Drug, Gene, and Pathophysiological Conditions. Int J Mol Sci 2020; 21:ijms21176350. [PMID: 32883002 PMCID: PMC7504705 DOI: 10.3390/ijms21176350] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/11/2020] [Accepted: 08/26/2020] [Indexed: 12/14/2022] Open
Abstract
Palbociclib, ribociclib, and abemaciclib belong to the third generation of cyclin-dependent kinases inhibitors (CDKis), an established therapeutic class for advanced and metastatic breast cancer. Interindividual variability in the therapeutic response of CDKis has been reported and some individuals may experience increased and unexpected toxicity. This narrative review aims at identifying the factors potentially concurring at this variability for driving the most appropriate and tailored use of CDKis in the clinic. Specifically, concomitant medications, pharmacogenetic profile, and pathophysiological conditions could influence absorption, distribution, metabolism, and elimination pharmacokinetics. A personalized therapeutic approach taking into consideration all factors potentially contributing to an altered pharmacokinetic/pharmacodynamic profile could better drive safe and effective clinical use.
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Iorfida M, Mazza M, Munzone E. Fulvestrant in Combination with CDK4/6 Inhibitors for HER2- Metastatic Breast Cancers: Current Perspectives. BREAST CANCER-TARGETS AND THERAPY 2020; 12:45-56. [PMID: 32256106 PMCID: PMC7090187 DOI: 10.2147/bctt.s196240] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/08/2020] [Indexed: 11/23/2022]
Abstract
The development of CDK 4/6 inhibitors has dramatically changed the therapeutic management of hormone receptor-positive (HR+) and HER2 negative metastatic breast cancer (MBC). In combination with fulvestrant, palbociclib, ribociclib and abemaciclib have each been approved for HR+/HER2- MBC following the results of randomized Phase III studies (PALOMA-3, MONALEESA-3, MONARCH-2) and shown a significant advantage in PFS. Data from clinical trials support the combination with aromatase inhibitors in the first line setting and with fulvestrant in the second line. Each agent is well tolerated, and most of the toxicities observed with this class of drugs are generally easily manageable and free from particular complications. The latest evidence from MONARCH-2 and MONALEESA-3 trials shows benefits in terms of overall survival (OS), suggesting an option of using fulvestrant in combination with CDK 4/6 inhibitors in the first line setting. Additional research is needed to determine optimal treatment sequencing, understand the mechanisms of resistance, and develop novel therapeutic strategies to overcome clinical resistance and further improve the outcomes of patients with HR+/HER- MBC. Key questions in the field include the further impact on progression-free survival, overall survival, and the role of continuing CDK 4/6 blockade beyond progression. The purpose of this review is to describe the clinical relevance of fulvestrant in combination with CDK 4/6 inhibitors in HR+/HER2- MBC patients, as well as to discuss the current controversies and evolving research areas.
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Affiliation(s)
- Monica Iorfida
- Division of Medical Senology, European Institute of Oncology, IRCCS, Milano 20141, Italy
| | - Manuelita Mazza
- Division of Medical Senology, European Institute of Oncology, IRCCS, Milano 20141, Italy
| | - Elisabetta Munzone
- Division of Medical Senology, European Institute of Oncology, IRCCS, Milano 20141, Italy
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9
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P-TEFb as A Promising Therapeutic Target. Molecules 2020; 25:molecules25040838. [PMID: 32075058 PMCID: PMC7070488 DOI: 10.3390/molecules25040838] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 01/19/2023] Open
Abstract
The positive transcription elongation factor b (P-TEFb) was first identified as a general factor that stimulates transcription elongation by RNA polymerase II (RNAPII), but soon afterwards it turned out to be an essential cellular co-factor of human immunodeficiency virus (HIV) transcription mediated by viral Tat proteins. Studies on the mechanisms of Tat-dependent HIV transcription have led to radical advances in our knowledge regarding the mechanism of eukaryotic transcription, including the discoveries that P-TEFb-mediated elongation control of cellular transcription is a main regulatory step of gene expression in eukaryotes, and deregulation of P-TEFb activity plays critical roles in many human diseases and conditions in addition to HIV/AIDS. P-TEFb is now recognized as an attractive and promising therapeutic target for inflammation/autoimmune diseases, cardiac hypertrophy, cancer, infectious diseases, etc. In this review article, I will summarize our knowledge about basic P-TEFb functions, the regulatory mechanism of P-TEFb-dependent transcription, P-TEFb’s involvement in biological processes and diseases, and current approaches to manipulating P-TEFb functions for the treatment of these diseases.
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Schneeberger PE, Bierhals T, Neu A, Hempel M, Kutsche K. de novo MEPCE nonsense variant associated with a neurodevelopmental disorder causes disintegration of 7SK snRNP and enhanced RNA polymerase II activation. Sci Rep 2019; 9:12516. [PMID: 31467394 PMCID: PMC6715695 DOI: 10.1038/s41598-019-49032-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 08/19/2019] [Indexed: 02/06/2023] Open
Abstract
In eukaryotes, the elongation phase of transcription by RNA polymerase II (RNAP II) is regulated by the transcription elongation factor b (P-TEFb), composed of Cyclin-T1 and cyclin-dependent kinase 9. The release of RNAP II is mediated by phosphorylation through P-TEFb that in turn is under control by the inhibitory 7SK small nuclear ribonucleoprotein (snRNP) complex. The 7SK snRNP consists of the 7SK non-coding RNA and the proteins MEPCE, LARP7, and HEXIM1/2. Biallelic LARP7 loss-of-function variants underlie Alazami syndrome characterized by growth retardation and intellectual disability. We report a boy with global developmental delay and seizures carrying the de novo MEPCE nonsense variant c.1552 C > T/p.(Arg518*). mRNA and protein analyses identified nonsense-mediated mRNA decay to underlie the decreased amount of MEPCE in patient fibroblasts followed by LARP7 and 7SK snRNA downregulation and HEXIM1 upregulation. Reduced binding of HEXIM1 to Cyclin-T1, hyperphosphorylation of the RNAP II C-terminal domain, and upregulated expression of ID2, ID3, MRPL11 and snRNAs U1, U2 and U4 in patient cells are suggestive of enhanced activation of P-TEFb. Flavopiridol treatment and ectopic MEPCE protein expression in patient fibroblasts rescued increased expression of six RNAP II-sensitive genes and suggested a possible repressive effect of MEPCE on P-TEFb-dependent transcription of specific genes.
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Affiliation(s)
- Pauline E Schneeberger
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tatjana Bierhals
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Axel Neu
- Childrens Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maja Hempel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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11
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Marra A, Curigliano G. Are all cyclin-dependent kinases 4/6 inhibitors created equal? NPJ Breast Cancer 2019; 5:27. [PMID: 31482107 PMCID: PMC6715721 DOI: 10.1038/s41523-019-0121-y] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 07/19/2019] [Indexed: 02/06/2023] Open
Abstract
The harnessing in clinical practice of cyclin-dependent kinases 4/6 inhibitors, namely palbociclib, ribociclib, and abemaciclib, has substantially changed the therapeutic approach for hormone receptor-positive metastatic breast cancer (BC). Phase II-III clinical trials evaluating the addition of these agents to standard endocrine therapy reported consistent improvements in response rates and progression-free survival as well as manageable toxicity profiles and excellent impact on patients' quality of life. Hence, pivotal trials provided comparable results among different cyclin-dependent kinases 4/6 inhibitors, there is an increasing interest in finding substantial differences in order to implement their use in clinical practice. The aim of this paper is to summarize the current evidences raised from preclinical and clinical studies on cyclin-dependent kinases 4/6 inhibitors in BC, focusing on differences in terms of pharmacological properties, toxicity profile, and patients' quality of life.
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Affiliation(s)
- Antonio Marra
- Division of Early Drug Development for Innovative Therapies, IEO, European Institute of Oncology IRCCS, Milan, Italy
- Department of Oncology and Hematology, University of Milan, Milan, Italy
| | - Giuseppe Curigliano
- Division of Early Drug Development for Innovative Therapies, IEO, European Institute of Oncology IRCCS, Milan, Italy
- Department of Oncology and Hematology, University of Milan, Milan, Italy
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12
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Stretton C, Lipina C, Hyde R, Cwiklinski E, Hoffmann TM, Taylor PM, Hundal HS. CDK7 is a component of the integrated stress response regulating SNAT2 (SLC38A2)/System A adaptation in response to cellular amino acid deprivation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:978-991. [PMID: 30857869 PMCID: PMC6456927 DOI: 10.1016/j.bbamcr.2019.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 12/31/2022]
Abstract
Extracellular amino acid (AA) withdrawal/restriction invokes an integrated stress response (ISR) that induces global suppression of protein synthesis whilst allowing transcription and translation of a select group of genes, whose protein products facilitate cellular adaptation to AA insufficiency. Transcriptional induction of the System A/SNAT2 AA transporter represents a classic adaptation response and crucially depends upon activation of the General Control Nonderepressible-2 kinase/Activating transcription factor 4 (GCN2/ATF4) pathway. However, the ISR may also include additional signalling inputs operating in conjunction or independently of GCN2/ATF4 to upregulate SNAT2. Herein, we show that whilst pharmacological inhibition of MEK-ERK, mTORC1 and p38 MAP kinase signalling has no detectable effect on System A upregulation, inhibitors targeting GSK3 (e.g. SB415286) caused significant repression of the SNAT2 adaptation response. Strikingly, the effects of SB415286 persist in cells in which GSK3α/β have been stably silenced indicating an off-target effect. We show that SB415286 can also inhibit cyclin-dependent kinases (CDK) and that roscovitine and flavopiridol (two pan CDK inhibitors) are effective repressors of the SNAT2 adaptive response. In particular, our work reveals that CDK7 activity is upregulated in AA-deprived cells in a GCN-2-dependent manner and that a potent and selective CDK7 inhibitor, THZ-1, not only attenuates the increase in ATF4 expression but blocks System A adaptation. Importantly, the inhibitory effects of THZ-1 on System A adaptation are mitigated in cells expressing a doxycycline-inducible drug-resistant form of CDK7. Our data identify CDK7 as a novel component of the ISR regulating System A adaptation in response to AA insufficiency. Roscovitine and flavopiridol (CDK inhibitors) block the System A adaptive response. Extracellular amino acid (AA) withdrawal induces CDK7 activation. Pharmacological inhibition of GCN2 represses CDK7 activation in AA-deprived cells. Targeted suppression of CDK7 represses ATF4 expression and System A adaptation.
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Affiliation(s)
- Clare Stretton
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Christopher Lipina
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Russell Hyde
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Emma Cwiklinski
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Thorsten M Hoffmann
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Peter M Taylor
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Harinder S Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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13
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Kadia TM, Kantarjian HM, Konopleva M. Myeloid cell leukemia-1 dependence in acute myeloid leukemia: a novel approach to patient therapy. Oncotarget 2019; 10:1250-1265. [PMID: 30815228 PMCID: PMC6383813 DOI: 10.18632/oncotarget.26579] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 12/16/2018] [Indexed: 12/15/2022] Open
Abstract
Acute myeloid leukemia (AML) is the most common form of acute leukemia in adults, affecting approximately 21,000 people annually (nearly 11,000 deaths) in the United States. B-cell lymphoma 2 (BCL-2) family proteins, notably myeloid cell leukemia-1 (MCL-1), have been associated with both the development and persistence of AML. MCL-1 is one of the predominant BCL-2 family members expressed in samples from patients with untreated AML. MCL-1 is a critical cell survival factor for cancer and contributes to chemotherapy resistance by directly affecting cell death pathways. Here, we review the role of MCL-1 in AML and the mechanisms by which the potent cyclin-dependent kinase 9 inhibitor alvocidib, through regulation of MCL-1, may serve as a rational therapeutic approach against the disease.
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Affiliation(s)
| | | | - Marina Konopleva
- The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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14
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Zhang H, Pandey S, Travers M, Sun H, Morton G, Madzo J, Chung W, Khowsathit J, Perez-Leal O, Barrero CA, Merali C, Okamoto Y, Sato T, Pan J, Garriga J, Bhanu NV, Simithy J, Patel B, Huang J, Raynal NJM, Garcia BA, Jacobson MA, Kadoch C, Merali S, Zhang Y, Childers W, Abou-Gharbia M, Karanicolas J, Baylin SB, Zahnow CA, Jelinek J, Graña X, Issa JPJ. Targeting CDK9 Reactivates Epigenetically Silenced Genes in Cancer. Cell 2018; 175:1244-1258.e26. [PMID: 30454645 PMCID: PMC6247954 DOI: 10.1016/j.cell.2018.09.051] [Citation(s) in RCA: 153] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 09/19/2018] [Accepted: 09/24/2018] [Indexed: 12/31/2022]
Abstract
Cyclin-dependent kinase 9 (CDK9) promotes transcriptional elongation through RNAPII pause release. We now report that CDK9 is also essential for maintaining gene silencing at heterochromatic loci. Through a live cell drug screen with genetic confirmation, we discovered that CDK9 inhibition reactivates epigenetically silenced genes in cancer, leading to restored tumor suppressor gene expression, cell differentiation, and activation of endogenous retrovirus genes. CDK9 inhibition dephosphorylates the SWI/SNF protein BRG1, which contributes to gene reactivation. By optimization through gene expression, we developed a highly selective CDK9 inhibitor (MC180295, IC50 = 5 nM) that has broad anti-cancer activity in vitro and is effective in in vivo cancer models. Additionally, CDK9 inhibition sensitizes to the immune checkpoint inhibitor α-PD-1 in vivo, making it an excellent target for epigenetic therapy of cancer.
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Affiliation(s)
- Hanghang Zhang
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Somnath Pandey
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Meghan Travers
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21231, USA
| | - Hongxing Sun
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - George Morton
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Jozef Madzo
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Woonbok Chung
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Jittasak Khowsathit
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA; Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
| | - Oscar Perez-Leal
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Carlos A Barrero
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Carmen Merali
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Yasuyuki Okamoto
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Takahiro Sato
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Joshua Pan
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA
| | - Judit Garriga
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Natarajan V Bhanu
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Johayra Simithy
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Bela Patel
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Jian Huang
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Noël J-M Raynal
- Département de pharmacologie et physiologie, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Benjamin A Garcia
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marlene A Jacobson
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Cigall Kadoch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA
| | - Salim Merali
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Yi Zhang
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Wayne Childers
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Magid Abou-Gharbia
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - John Karanicolas
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Stephen B Baylin
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21231, USA
| | - Cynthia A Zahnow
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21231, USA
| | - Jaroslav Jelinek
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Xavier Graña
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Jean-Pierre J Issa
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA.
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15
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CDKI-73: an orally bioavailable and highly efficacious CDK9 inhibitor against acute myeloid leukemia. Invest New Drugs 2018; 37:625-635. [PMID: 30194564 DOI: 10.1007/s10637-018-0661-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 08/20/2018] [Indexed: 12/13/2022]
Abstract
Acute myeloid leukemia (AML) is the most common form of acute leukemia with dismal long-term prognosis with age. The most aggressive subtype of AML is MLL-AML that is characterized by translocations of the mixed-lineage leukemia gene (MLL) and resistance to conventional chemotherapy. Cyclin dependent kinase 9 (CDK9) plays a crucial role in the MLL-driven oncogenic transcription, and hence, inhibiting activity of CDK9 has been proposed as a promising strategy for treatment of AML. We investigated the therapeutic potential of CDKI-73, one of the most potent CDK9 inhibitors, against a panel of AML cell lines and samples derived from 97 patients. CDKI-73 induced cancer cells undergoing apoptosis through transcriptional downregulation of anti-apoptotic proteins Bcl-2, Mcl-1 and XIAP by majorly targeting CDK9. Contrastively, it was relatively low toxic to the bone marrow cells of healthy donors. In MV4-11 xenograft mouse models, oral administration of CDKI-73 resulted in a marked inhibition of tumor growth (p < 0.0001) and prolongation of animal life span (P < 0.001) without causing body weight loss and other overt toxicities. The study suggests that CDKI-73 can be developed as a highly efficacious and orally deliverable therapeutic agent for treatment of AML.
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16
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Gamage AM, Lee KO, Gan YH. Anti-Cancer Drug HMBA Acts as an Adjuvant during Intracellular Bacterial Infections by Inducing Type I IFN through STING. THE JOURNAL OF IMMUNOLOGY 2017; 199:2491-2502. [PMID: 28827286 DOI: 10.4049/jimmunol.1602162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 07/26/2017] [Indexed: 01/06/2023]
Abstract
The anti-proliferative agent hexamethylene bisacetamide (HMBA) belongs to a class of hybrid bipolar compounds developed more than 30 y ago for their ability to induce terminal differentiation of transformed cells. Recently, HMBA has also been shown to trigger HIV transcription from latently infected cells, via a CDK9/HMBA inducible protein-1 dependent process. However, the effect of HMBA on the immune response has not been explored. We observed that pretreatment of human peripheral blood mononuclear cells with HMBA led to a markedly increased production of IL-12 and IFN-γ, but not of TNF-α, IL-6, and IL-8 upon subsequent infection with Burkholderia pseudomallei and Salmonella enterica HMBA treatment was also associated with better intracellular bacterial control. HMBA significantly improved IL-12p70 production from CD14+ monocytes during infection partly via the induction of type I IFN in these cells, which primed an increased transcription of the p35 subunit of IL-12p70 during infection. HMBA also increased early type I IFN transcription in human monocytic and epithelial cell lines, but this was surprisingly independent of its previously reported effects on positive transcription elongation factor b and HMBA inducible protein-1. Instead, the effect of HMBA was downstream of a calcium influx, and required the pattern recognition receptor and adaptor STING but not cGAS. Our work therefore links the STING-IRF3 axis to enhanced IL-12 production and intracellular bacterial control in primary monocytes. This raises the possibility that HMBA or related small molecules may be explored as therapeutic adjuvants to improve disease outcomes during intracellular bacterial infections.
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Affiliation(s)
- Akshamal Mihiranga Gamage
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; and
| | - Kok-Onn Lee
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; and
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17
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Chen P, Lee NV, Hu W, Xu M, Ferre RA, Lam H, Bergqvist S, Solowiej J, Diehl W, He YA, Yu X, Nagata A, VanArsdale T, Murray BW. Spectrum and Degree of CDK Drug Interactions Predicts Clinical Performance. Mol Cancer Ther 2016; 15:2273-2281. [DOI: 10.1158/1535-7163.mct-16-0300] [Citation(s) in RCA: 209] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 07/22/2016] [Indexed: 11/16/2022]
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18
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Shan J, Zhang F, Sharkey J, Tang TA, Örd T, Kilberg MS. The C/ebp-Atf response element (CARE) location reveals two distinct Atf4-dependent, elongation-mediated mechanisms for transcriptional induction of aminoacyl-tRNA synthetase genes in response to amino acid limitation. Nucleic Acids Res 2016; 44:9719-9732. [PMID: 27471030 PMCID: PMC5175342 DOI: 10.1093/nar/gkw667] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/19/2016] [Accepted: 07/20/2016] [Indexed: 12/13/2022] Open
Abstract
The response to amino acid (AA) limitation of the entire aminoacyl-tRNA synthetase (ARS) gene family revealed that 16/20 of the genes encoding cytoplasmic-localized enzymes are transcriptionally induced by activating transcription factor 4 (Atf4) via C/ebp-Atf-Response-Element (CARE) enhancers. In contrast, only 4/19 of the genes encoding mitochondrial-localized ARSs were weakly induced. Most of the activated genes have a functional CARE near the transcription start site (TSS), but for others the CARE is downstream. Regardless of the location of CARE enhancer, for all ARS genes there was constitutive association of RNA polymerase II (Pol II) and the general transcription machinery near the TSS. However, for those genes with a downstream CARE, Atf4, C/ebp-homology protein (Chop), Pol II and TATA-binding protein exhibited enhanced recruitment to the CARE during AA limitation. Increased Atf4 binding regulated the association of elongation factors at both the promoter and the enhancer regions, and inhibition of cyclin-dependent kinase 9 (CDK9), that regulates these elongation factors, blocked induction of the AA-responsive ARS genes. Protein pull-down assays indicated that Atf4 directly interacts with CDK9 and its associated protein cyclin T1. The results demonstrate that AA availability modulates the ARS gene family through modulation of transcription elongation.
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Affiliation(s)
- Jixiu Shan
- Department of Biochemistry and Molecular Biology, Shands Cancer Center and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Fan Zhang
- Department of Biochemistry and Molecular Biology, Shands Cancer Center and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Jason Sharkey
- Department of Biochemistry and Molecular Biology, Shands Cancer Center and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Tiffany A Tang
- Department of Biochemistry and Molecular Biology, Shands Cancer Center and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Tönis Örd
- Estonian Biocentre, Riia 23, Tartu, 51010, Estonia
| | - Michael S Kilberg
- Department of Biochemistry and Molecular Biology, Shands Cancer Center and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, FL 32610, USA
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19
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Sonawane YA, Taylor MA, Napoleon JV, Rana S, Contreras JI, Natarajan A. Cyclin Dependent Kinase 9 Inhibitors for Cancer Therapy. J Med Chem 2016; 59:8667-8684. [PMID: 27171036 PMCID: PMC5636177 DOI: 10.1021/acs.jmedchem.6b00150] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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Cyclin dependent kinase (CDK) inhibitors
have been the topic of intense research for nearly 2 decades due to
their widely varied and critical functions within the cell. Recently
CDK9 has emerged as a druggable target for the development of cancer
therapeutics. CDK9 plays a crucial role in transcription regulation;
specifically, CDK9 mediated transcriptional regulation of short-lived
antiapoptotic proteins is critical for the survival of transformed
cells. Focused chemical libraries based on a plethora of scaffolds
have resulted in mixed success with regard to the development of selective
CDK9 inhibitors. Here we review the regulation of CDK9, its cellular
functions, and common core structures used to target CDK9, along with
their selectivity profile and efficacy in vitro and in vivo.
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Affiliation(s)
- Yogesh A Sonawane
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - Margaret A Taylor
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - John Victor Napoleon
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - Sandeep Rana
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - Jacob I Contreras
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - Amarnath Natarajan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
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20
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Abstract
The high mobility group protein A1 (HMGA1) is a master regulator of chromatin structure mediating its major gene regulatory activity by direct interactions with A/T-rich DNA sequences located in the promoter and enhancer regions of a large variety of genes. HMGA1 DNA-binding through three AT-hook motifs results in an open chromatin structure and subsequently leads to changes in gene expression. Apart from its significant expression during development, HMGA1 is over-expressed in virtually every cancer, where HMGA1 expression levels correlate with tumor malignancy. The exogenous overexpression of HMGA1 can lead to malignant cell transformation, assigning the protein a key role during cancerogenesis. Recent studies have unveiled highly specific competitive interactions of HMGA1 with cellular and viral RNAs also through an AT-hook domain of the protein, significantly impacting the HMGA1-dependent gene expression. In this review, we discuss the structure and function of HMGA1-RNA complexes during transcription and epigenomic regulation and their implications in HMGA1-related diseases.
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