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Timofeev O, Giron P, Lawo S, Pichler M, Noeparast M. ERK pathway agonism for cancer therapy: evidence, insights, and a target discovery framework. NPJ Precis Oncol 2024; 8:70. [PMID: 38485987 PMCID: PMC10940698 DOI: 10.1038/s41698-024-00554-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 02/16/2024] [Indexed: 03/18/2024] Open
Abstract
At least 40% of human cancers are associated with aberrant ERK pathway activity (ERKp). Inhibitors targeting various effectors within the ERKp have been developed and explored for over two decades. Conversely, a substantial body of evidence suggests that both normal human cells and, notably to a greater extent, cancer cells exhibit susceptibility to hyperactivation of ERKp. However, this vulnerability of cancer cells remains relatively unexplored. In this review, we reexamine the evidence on the selective lethality of highly elevated ERKp activity in human cancer cells of varying backgrounds. We synthesize the insights proposed for harnessing this vulnerability of ERK-associated cancers for therapeutical approaches and contextualize these insights within established pharmacological cancer-targeting models. Moreover, we compile the intriguing preclinical findings of ERK pathway agonism in diverse cancer models. Lastly, we present a conceptual framework for target discovery regarding ERKp agonism, emphasizing the utilization of mutual exclusivity among oncogenes to develop novel targeted therapies for precision oncology.
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Affiliation(s)
- Oleg Timofeev
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps University, 35043, Marburg, Germany
| | - Philippe Giron
- Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Clinical Sciences, Research group Genetics, Reproduction and Development, Centre for Medical Genetics, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Steffen Lawo
- CRISPR Screening Core Facility, Max Planck Institute for Biology of Ageing, 50931, Cologne, Germany
| | - Martin Pichler
- Translational Oncology, II. Med Clinics Hematology and Oncology, 86156, Augsburg, Germany
| | - Maxim Noeparast
- Translational Oncology, II. Med Clinics Hematology and Oncology, 86156, Augsburg, Germany.
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2
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Permin D, Postnikova O, Balabanov S, Belyaev A, Koshkin V, Timofeev O, Li J. Influence of SHS Precursor Composition on the Properties of Yttria Powders and Optical Ceramics. Materials (Basel) 2022; 16:260. [PMID: 36614599 PMCID: PMC9822065 DOI: 10.3390/ma16010260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/22/2022] [Accepted: 12/24/2022] [Indexed: 06/17/2023]
Abstract
This study looked at optimizing the composition of precursors for yttria nanopowder glycine-nitrate self-propagating high-temperature synthesis (SHS). Based on thermodynamic studies, six different precursor compositions were selected, including with excesses of either oxidant or fuel. The powders from the precursors of all selected compositions were highly dispersed and had specific surface areas ranging from 22 to 57 m2/g. They were consolidated by hot pressing (HP) with lithium-fluoride sintering additive and subsequent hot isostatic pressing (HIP). The 1 mm thick HPed ceramics had transmittance in the range of 74.5% to 80.1% @ 1μm, which was limited by optical inhomogeneity due to incomplete evaporation of the sintering additive. Two-stage HIP significantly improves optical homogeneity of the ceramics. It was shown that an excess of oxidizer in the precursor decreases the powders' agglomeration degree, which forms large pore clusters in the ceramics.
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Affiliation(s)
- Dmitry Permin
- Faculty of Chemistry, N.I. Lobachevsky National Research University, 23 Gagarin Ave., 603022 Nizhny Novgorod, Russia
- G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, 49 Tropinin Str., 603137 Nizhny Novgorod, Russia
| | - Olga Postnikova
- Faculty of Chemistry, N.I. Lobachevsky National Research University, 23 Gagarin Ave., 603022 Nizhny Novgorod, Russia
- G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, 49 Tropinin Str., 603137 Nizhny Novgorod, Russia
| | - Stanislav Balabanov
- Faculty of Chemistry, N.I. Lobachevsky National Research University, 23 Gagarin Ave., 603022 Nizhny Novgorod, Russia
- G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, 49 Tropinin Str., 603137 Nizhny Novgorod, Russia
| | - Alexander Belyaev
- Faculty of Chemistry, N.I. Lobachevsky National Research University, 23 Gagarin Ave., 603022 Nizhny Novgorod, Russia
- G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, 49 Tropinin Str., 603137 Nizhny Novgorod, Russia
| | - Vitaliy Koshkin
- Faculty of Chemistry, N.I. Lobachevsky National Research University, 23 Gagarin Ave., 603022 Nizhny Novgorod, Russia
- G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, 49 Tropinin Str., 603137 Nizhny Novgorod, Russia
| | - Oleg Timofeev
- Faculty of Chemistry, N.I. Lobachevsky National Research University, 23 Gagarin Ave., 603022 Nizhny Novgorod, Russia
- G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, 49 Tropinin Str., 603137 Nizhny Novgorod, Russia
| | - Jiang Li
- Transparent Ceramics Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China
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Merle N, Elmshäuser S, Strassheimer F, Wanzel M, König AM, Funk J, Neumann M, Kochhan K, Helmprobst F, Pagenstecher A, Nist A, Mernberger M, Schneider A, Braun T, Borggrefe T, Savai R, Timofeev O, Stiewe T. Monitoring autochthonous lung tumors induced by somatic CRISPR gene editing in mice using a secreted luciferase. Mol Cancer 2022; 21:191. [PMID: 36192757 PMCID: PMC9531476 DOI: 10.1186/s12943-022-01661-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 09/22/2022] [Indexed: 12/04/2022] Open
Abstract
Background In vivo gene editing of somatic cells with CRISPR nucleases has facilitated the generation of autochthonous mouse tumors, which are initiated by genetic alterations relevant to the human disease and progress along a natural timeline as in patients. However, the long and variable, orthotopic tumor growth in inner organs requires sophisticated, time-consuming and resource-intensive imaging for longitudinal disease monitoring and impedes the use of autochthonous tumor models for preclinical studies. Methods To facilitate a more widespread use, we have generated a reporter mouse that expresses a Cre-inducible luciferase from Gaussia princeps (GLuc), which is secreted by cells in an energy-consuming process and can be measured quantitatively in the blood as a marker for the viable tumor load. In addition, we have developed a flexible, complementary toolkit to rapidly assemble recombinant adenoviruses (AVs) for delivering Cre recombinase together with CRISPR nucleases targeting cancer driver genes. Results We demonstrate that intratracheal infection of GLuc reporter mice with CRISPR-AVs efficiently induces lung tumors driven by mutations in the targeted cancer genes and simultaneously activates the GLuc transgene, resulting in GLuc secretion into the blood by the growing tumor. GLuc blood levels are easily and robustly quantified in small-volume blood samples with inexpensive equipment, enable tumor detection already several months before the humane study endpoint and precisely mirror the kinetics of tumor development specified by the inducing gene combination. Conclusions Our study establishes blood-based GLuc monitoring as an inexpensive, rapid, high-throughput and animal-friendly method to longitudinally monitor autochthonous tumor growth in preclinical studies. Supplementary Information The online version contains supplementary material available at 10.1186/s12943-022-01661-2.
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Affiliation(s)
- Nastasja Merle
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Sabrina Elmshäuser
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Florian Strassheimer
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Michael Wanzel
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Alexander M König
- Clinic of Diagnostic and Interventional Radiology, Philipps-University, Core Facility 7T-small animal MRI, Marburg, Germany
| | - Julianne Funk
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Michelle Neumann
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Katharina Kochhan
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Frederik Helmprobst
- Mouse Pathology and Electron Microscopy Core Facility, Department of Neuropathology, Philipps-University, Marburg, Germany
| | - Axel Pagenstecher
- Mouse Pathology and Electron Microscopy Core Facility, Department of Neuropathology, Philipps-University, Marburg, Germany
| | - Andrea Nist
- Genomics Core Facility, Philipps-University, Marburg, Germany
| | - Marco Mernberger
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - André Schneider
- Department of Cardiac Development and Remodeling, Member of the German Center for Lung Research (DZL), Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Thomas Braun
- Department of Cardiac Development and Remodeling, Member of the German Center for Lung Research (DZL), Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Tilman Borggrefe
- Department of Biochemistry, Justus Liebig University, Giessen, Germany
| | - Rajkumar Savai
- Max-Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Member of the Cardio-Pulmonary Institute (CPI), Bad Nauheim, Germany.,Institute for Lung Health (ILH), Justus Liebig University, Giessen, Germany
| | - Oleg Timofeev
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany. .,Genomics Core Facility, Philipps-University, Marburg, Germany. .,Institute for Lung Health (ILH), Justus Liebig University, Giessen, Germany.
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Klimovich B, Meyer L, Merle N, Neumann M, König AM, Ananikidis N, Keber CU, Elmshäuser S, Timofeev O, Stiewe T. Partial p53 reactivation is sufficient to induce cancer regression. J Exp Clin Cancer Res 2022; 41:80. [PMID: 35232479 PMCID: PMC8889716 DOI: 10.1186/s13046-022-02269-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 01/20/2022] [Indexed: 01/21/2023]
Abstract
Background Impaired p53 function is one of the central molecular features of a tumor cell and even a partial reduction in p53 activity can increase the cancer risk in mice and men. From a therapeutic perspective it is noteworthy that tumor cells often become addicted to the absence of p53 providing a rationale for developing p53 reactivating compounds to treat cancer patients. Unfortunately, many of the compounds that are currently undergoing preclinical and clinical testing fail to fully reactivate mutant p53 proteins, raising the crucial question: how much p53 activity is needed to elicit a therapeutic effect? Methods We have genetically modelled partial p53 reactivation using knock-in mice with inducible expression of the p53 variant E177R. This variant has a reduced ability to bind and transactivate target genes and consequently causes moderate cancer susceptibility. We have generated different syngeneically transplanted and autochthonous mouse models of p53-deficient acute myeloid leukemia and B or T cell lymphoma. After cancer manifestation we have activated E177R expression and analyzed the in vivo therapy response by bioluminescence or magnetic resonance imaging. The molecular response was further characterized in vitro by assays for gene expression, proliferation, senescence, differentiation, apoptosis and clonogenic growth. Results We report the conceptually intriguing observation that the p53 variant E177R, which promotes de novo leukemia and lymphoma formation, inhibits proliferation and viability, induces immune cell infiltration and triggers cancer regression in vivo when introduced into p53-deficient leukemia and lymphomas. p53-deficient cancer cells proved to be so addicted to the absence of p53 that even the low-level activity of E177R is detrimental to cancer growth. Conclusions The observation that a partial loss-of-function p53 variant promotes tumorigenesis in one setting and induces regression in another, underlines the highly context-specific effects of individual p53 mutants. It further highlights the exquisite sensitivity of cancer cells to even small changes in p53 activity and reveals that changes in activity level are more important than the absolute level. As such, the study encourages ongoing research efforts into mutant p53 reactivating drugs by providing genetic proof-of-principle evidence that incomplete p53 reactivation may suffice to elicit a therapeutic response. Supplementary Information The online version contains supplementary material available at 10.1186/s13046-022-02269-6.
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Affiliation(s)
- Boris Klimovich
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Philipps-University, Marburg, Germany
| | - Laura Meyer
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Philipps-University, Marburg, Germany
| | - Nastasja Merle
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Philipps-University, Marburg, Germany
| | - Michelle Neumann
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Philipps-University, Marburg, Germany
| | - Alexander M König
- Clinic of Diagnostic and Interventional Radiology, Core Facility 7T-small animal MRI, Philipps-University, Marburg, Germany
| | - Nikolaos Ananikidis
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Philipps-University, Marburg, Germany
| | - Corinna U Keber
- Institute for Pathology, University Hospital Marburg, Philipps-University, Marburg, Germany
| | - Sabrina Elmshäuser
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Philipps-University, Marburg, Germany
| | - Oleg Timofeev
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Philipps-University, Marburg, Germany. .,German Center for Lung Research (DZL), Philipps-University, Marburg, Germany.
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Philipps-University, Marburg, Germany. .,German Center for Lung Research (DZL), Philipps-University, Marburg, Germany. .,Genomics Core Facility, Philipps-University, Marburg, Germany.
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5
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Affiliation(s)
- Oleg Timofeev
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
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6
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Timofeev O, Stiewe T. Rely on Each Other: DNA Binding Cooperativity Shapes p53 Functions in Tumor Suppression and Cancer Therapy. Cancers (Basel) 2021; 13:2422. [PMID: 34067731 PMCID: PMC8155944 DOI: 10.3390/cancers13102422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/14/2021] [Accepted: 05/15/2021] [Indexed: 12/24/2022] Open
Abstract
p53 is a tumor suppressor that is mutated in half of all cancers. The high clinical relevance has made p53 a model transcription factor for delineating general mechanisms of transcriptional regulation. p53 forms tetramers that bind DNA in a highly cooperative manner. The DNA binding cooperativity of p53 has been studied by structural and molecular biologists as well as clinical oncologists. These experiments have revealed the structural basis for cooperative DNA binding and its impact on sequence specificity and target gene spectrum. Cooperativity was found to be critical for the control of p53-mediated cell fate decisions and tumor suppression. Importantly, an estimated number of 34,000 cancer patients per year world-wide have mutations of the amino acids mediating cooperativity, and knock-in mouse models have confirmed such mutations to be tumorigenic. While p53 cancer mutations are classically subdivided into "contact" and "structural" mutations, "cooperativity" mutations form a mechanistically distinct third class that affect the quaternary structure but leave DNA contacting residues and the three-dimensional folding of the DNA-binding domain intact. In this review we discuss the concept of DNA binding cooperativity and highlight the unique nature of cooperativity mutations and their clinical implications for cancer therapy.
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Affiliation(s)
- Oleg Timofeev
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, 35037 Marburg, Germany
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Philipps-University, 35037 Marburg, Germany
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Gremke N, Polo P, Dort A, Schneikert J, Elmshäuser S, Brehm C, Klingmüller U, Schmitt A, Reinhardt HC, Timofeev O, Wanzel M, Stiewe T. mTOR-mediated cancer drug resistance suppresses autophagy and generates a druggable metabolic vulnerability. Nat Commun 2020; 11:4684. [PMID: 32943635 PMCID: PMC7499183 DOI: 10.1038/s41467-020-18504-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 08/25/2020] [Indexed: 12/17/2022] Open
Abstract
Cancer cells have a characteristic metabolism, mostly caused by alterations in signal transduction networks rather than mutations in metabolic enzymes. For metabolic drugs to be cancer-selective, signaling alterations need to be identified that confer a druggable vulnerability. Here, we demonstrate that many tumor cells with an acquired cancer drug resistance exhibit increased sensitivity to mechanistically distinct inhibitors of cancer metabolism. We demonstrate that this metabolic vulnerability is driven by mTORC1, which promotes resistance to chemotherapy and targeted cancer drugs, but simultaneously suppresses autophagy. We show that autophagy is essential for tumor cells to cope with therapeutic perturbation of metabolism and that mTORC1-mediated suppression of autophagy is required and sufficient for generating a metabolic vulnerability leading to energy crisis and apoptosis. Our study links mTOR-induced cancer drug resistance to autophagy defects as a cause of a metabolic liability and opens a therapeutic window for the treatment of otherwise therapy-refractory tumor patients. mTORC1 is a key mediator of drug resistance and also regulates autophagy. In this study, the authors demonstrate that cancer cells with acquired drug resistance exibit metabolic vulnerabilities mediated by high levels of mTORC1 and the consequent inhibition of autophagy.
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Affiliation(s)
- Niklas Gremke
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | | | - Aaron Dort
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | - Jean Schneikert
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | | | - Corinna Brehm
- Institute of Pathology, Philipps-University, Marburg, Germany
| | - Ursula Klingmüller
- Division Systems Biology of Signal Transduction, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), Heidelberg, Germany
| | - Anna Schmitt
- Clinic for Hematology and Stem Cell Transplantation, West German Cancer Center, University Hospital Essen, German Cancer Consortium (DKTK), Essen, Germany
| | - Hans Christian Reinhardt
- Clinic for Hematology and Stem Cell Transplantation, West German Cancer Center, University Hospital Essen, German Cancer Consortium (DKTK), Essen, Germany
| | - Oleg Timofeev
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | - Michael Wanzel
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany.,Universities of Giessen and Marburg Lung Center, German Center for Lung Research (DZL), Marburg, Germany
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany. .,Universities of Giessen and Marburg Lung Center, German Center for Lung Research (DZL), Marburg, Germany. .,Genomics Core Facility, Philipps-University, Marburg, Germany.
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Timofeev O, Koch L, Niederau C, Tscherne A, Schneikert J, Klimovich M, Elmshäuser S, Zeitlinger M, Mernberger M, Nist A, Osterburg C, Dötsch V, Hrabé de Angelis M, Stiewe T. Phosphorylation Control of p53 DNA-Binding Cooperativity Balances Tumorigenesis and Aging. Cancer Res 2020; 80:5231-5244. [PMID: 32873634 DOI: 10.1158/0008-5472.can-20-2002] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/30/2020] [Accepted: 08/26/2020] [Indexed: 11/16/2022]
Abstract
Posttranslational modifications are essential for regulating the transcription factor p53, which binds DNA in a highly cooperative manner to control expression of a plethora of tumor-suppressive programs. Here we show at the biochemical, cellular, and organismal level that the cooperative nature of DNA binding is reduced by phosphorylation of highly conserved serine residues (human S183/S185, mouse S180) in the DNA-binding domain. To explore the role of this inhibitory phosphorylation in vivo, new phosphorylation-deficient p53-S180A knock-in mice were generated. Chromatin immunoprecipitation sequencing and RNA sequencing studies of S180A knock-in cells demonstrated enhanced DNA binding and increased target gene expression. In vivo, this translated into a tissue-specific vulnerability of the bone marrow that caused depletion of hematopoietic stem cells and impaired proper regeneration of hematopoiesis after DNA damage. Median lifespan was significantly reduced by 20% from 709 days in wild type to only 568 days in S180A littermates. Importantly, lifespan was reduced by a loss of general fitness and increased susceptibility to age-related diseases, not by increased cancer incidence as often seen in other p53-mutant mouse models. For example, S180A knock-in mice showed markedly reduced spontaneous tumorigenesis and increased resistance to Myc-driven lymphoma and Eml4-Alk-driven lung cancer. Preventing phosphorylation of S183/S185 in human cells boosted p53 activity and allowed tumor cells to be killed more efficiently. Together, our data identify p53 DNA-binding domain phosphorylation as a druggable mechanism that balances tumorigenesis and aging. SIGNIFICANCE: These findings demonstrate that p53 tumor suppressor activity is reduced by DNA-binding domain phosphorylation to prevent aging and identify this phosphorylation as a potential target for cancer therapy.See related commentary by Horikawa, p. 5164.
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Affiliation(s)
- Oleg Timofeev
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany.
| | - Lukas Koch
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany
| | - Constantin Niederau
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany
| | - Alina Tscherne
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany
| | - Jean Schneikert
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany
| | - Maria Klimovich
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany
| | - Sabrina Elmshäuser
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany
| | - Marie Zeitlinger
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany
| | - Marco Mernberger
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany
| | - Andrea Nist
- Genomics Core Facility, Philipps-University Marburg, Marburg, Germany
| | | | | | - Martin Hrabé de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany.,Chair of Experimental Genetics, School of Life Science Weihenstephan, Technische Universität München, Freising, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany. .,Genomics Core Facility, Philipps-University Marburg, Marburg, Germany
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Abstract
TP53 mutations are found in 50% of all cancers and mutated TP53 status is considered poor for treatment. However, some TP53 mutations exhibit only partial loss-of-function (LOF), meaning they retain residual transcriptional and non-transcriptional activities that are potentially beneficial for therapy. Earlier we have characterized a knock-in mouse model for the partial LOF mutant Trp53E177R (p53RR). Reduced DNA binding cooperativity of this mutant led to the loss of p53-dependent apoptosis, while p53 functions in cell cycle control, senescence, metabolism, and antioxidant defense remained intact. Concomitantly, tumor suppression was evident but strongly compromised compared to wild-type mice. Here we used the Trp53E177R mouse as a model to investigate whether residual functions of mutant p53 can be engaged to induce cell death, which is considered the most desirable outcome of tumor therapy. We made use of Mdm2 knock-out in developing embryos as a sensitive tool for detecting remaining p53 activities. Genetic ablation of Mdm2 led to embryonic lethality in Trp53E177R/E177R homozygotes at days 9.5-11.5. This effect was not rescued by concomitant p21-knockout, indicating its independence of p21-mediated cell cycle arrest. Instead, immunohistochemical analysis showed widespread apoptosis in tissues of defective embryos accompanied by persistent accumulation of p53RR protein. This led to partial restoration of the mutant's proficiency in transcriptional induction of the pro-apoptotic genes Bbc3 (Puma) and Bax. These data indicate that increased quantity can compensate for qualitative defects of p53 mutants and suggest that Mdm2-targeting (potentially in combination with other drugs) might be effective against cells bearing p53 partial LOF mutants.
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Affiliation(s)
- Boris Klimovich
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
| | - Oleg Timofeev
- Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University, Marburg, Germany
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10
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Timofeev O, Klimovich B, Schneikert J, Wanzel M, Pavlakis E, Noll J, Mutlu S, Elmshäuser S, Nist A, Mernberger M, Lamp B, Wenig U, Brobeil A, Gattenlöhner S, Köhler K, Stiewe T. Residual apoptotic activity of a tumorigenic p53 mutant improves cancer therapy responses. EMBO J 2019; 38:e102096. [PMID: 31483066 PMCID: PMC6792016 DOI: 10.15252/embj.2019102096] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 07/30/2019] [Accepted: 08/05/2019] [Indexed: 12/19/2022] Open
Abstract
Engineered p53 mutant mice are valuable tools for delineating p53 functions in tumor suppression and cancer therapy. Here, we have introduced the R178E mutation into the Trp53 gene of mice to specifically ablate the cooperative nature of p53 DNA binding. Trp53R178E mice show no detectable target gene regulation and, at first sight, are largely indistinguishable from Trp53−/− mice. Surprisingly, stabilization of p53R178E in Mdm2−/− mice nevertheless triggers extensive apoptosis, indicative of residual wild‐type activities. Although this apoptotic activity suffices to trigger lethality of Trp53R178E;Mdm2−/− embryos, it proves insufficient for suppression of spontaneous and oncogene‐driven tumorigenesis. Trp53R178E mice develop tumors indistinguishably from Trp53−/− mice and tumors retain and even stabilize the p53R178E protein, further attesting to the lack of significant tumor suppressor activity. However, Trp53R178E tumors exhibit remarkably better chemotherapy responses than Trp53−/− ones, resulting in enhanced eradication of p53‐mutated tumor cells. Together, this provides genetic proof‐of‐principle evidence that a p53 mutant can be highly tumorigenic and yet retain apoptotic activity which provides a survival benefit in the context of cancer therapy.
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Affiliation(s)
- Oleg Timofeev
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | - Boris Klimovich
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | - Jean Schneikert
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | - Michael Wanzel
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany.,German Center for Lung Research (DZL), Universities of Giessen and Marburg Lung Center, Marburg, Germany
| | | | - Julia Noll
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | - Samet Mutlu
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | | | - Andrea Nist
- Genomics Core Facility, Philipps University, Marburg, Germany
| | - Marco Mernberger
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany
| | - Boris Lamp
- Genomics Core Facility, Philipps University, Marburg, Germany
| | - Ulrich Wenig
- Institute of Pathology, Justus Liebig University, Giessen, Germany
| | | | | | - Kernt Köhler
- Institute of Veterinary Pathology, Justus Liebig University, Giessen, Germany
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Philipps-University, Marburg, Germany.,German Center for Lung Research (DZL), Universities of Giessen and Marburg Lung Center, Marburg, Germany.,Genomics Core Facility, Philipps University, Marburg, Germany
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11
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Timofeev O, Stiewe T. p53 gain-of-function mutations promote metastasis via ENTPD5 upregulation and enhanced N-glycoprotein folding. Mol Cell Oncol 2017; 4:e1288678. [PMID: 28401189 DOI: 10.1080/23723556.2017.1288678] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 01/25/2017] [Accepted: 01/25/2017] [Indexed: 12/21/2022]
Abstract
Mutations in cancer abolish normal tumor suppressive functions of tumor protein p53 (TP53, best known as p53) and convert it into an oncogene. We recently reported the identification of ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5) as a transcriptional target of mutant p53 that enhances folding of N-glycosylated proteins required for cancer cell migration, invasion, and metastasis.
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Affiliation(s)
- Oleg Timofeev
- Institute of Molecular Oncology, Philipps-University , Marburg, Germany
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Philipps-University , Marburg, Germany
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12
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Vogiatzi F, Brandt DT, Schneikert J, Fuchs J, Grikscheit K, Wanzel M, Pavlakis E, Charles JP, Timofeev O, Nist A, Mernberger M, Kantelhardt EJ, Siebolts U, Bartel F, Jacob R, Rath A, Moll R, Grosse R, Stiewe T. Mutant p53 promotes tumor progression and metastasis by the endoplasmic reticulum UDPase ENTPD5. Proc Natl Acad Sci U S A 2016; 113:E8433-E8442. [PMID: 27956623 PMCID: PMC5206569 DOI: 10.1073/pnas.1612711114] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mutations in the p53 tumor suppressor gene are the most frequent genetic alteration in cancer and are often associated with progression from benign to invasive stages with metastatic potential. Mutations inactivate tumor suppression by p53, and some endow the protein with novel gain of function (GOF) properties that actively promote tumor progression and metastasis. By comparative gene expression profiling of p53-mutated and p53-depleted cancer cells, we identified ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5) as a mutant p53 target gene, which functions as a uridine 5'-diphosphatase (UDPase) in the endoplasmic reticulum (ER) to promote the folding of N-glycosylated membrane proteins. A comprehensive pan-cancer analysis revealed a highly significant correlation between p53 GOF mutations and ENTPD5 expression. Mechanistically, mutp53 is recruited by Sp1 to the ENTPD5 core promoter to induce its expression. We show ENTPD5 to be a mediator of mutant p53 GOF activity in clonogenic growth, architectural tissue remodeling, migration, invasion, and lung colonization in an experimental metastasis mouse model. Our study reveals folding of N-glycosylated membrane proteins in the ER as a mechanism underlying the metastatic progression of tumors with mutp53 that could provide new possibilities for cancer treatment.
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Affiliation(s)
- Fotini Vogiatzi
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany
| | | | - Jean Schneikert
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany
| | - Jeannette Fuchs
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany
| | | | - Michael Wanzel
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany
| | - Evangelos Pavlakis
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany
| | - Joël P Charles
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany
| | - Oleg Timofeev
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany
| | - Andrea Nist
- Genomics Core Facility, Philipps-University, 35043 Marburg, Germany
| | - Marco Mernberger
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany
- Genomics Core Facility, Philipps-University, 35043 Marburg, Germany
| | - Eva J Kantelhardt
- Clinic of Gynecology, Faculty of Medicine, Martin-Luther-University Halle Wittenberg, 06097 Halle/Saale, Germany
| | - Udo Siebolts
- Institute of Pathology, Faculty of Medicine, Martin-Luther-University Halle-Wittenberg, 06112 Halle/Saale, Germany
| | - Frank Bartel
- Institute of Pathology, Faculty of Medicine, Martin-Luther-University Halle-Wittenberg, 06112 Halle/Saale, Germany
| | - Ralf Jacob
- Department of Cell Biology and Cell Pathology, Philipps-University, 35037 Marburg, Germany
| | - Ariane Rath
- Institute of Pathology, Philipps-University, 35043 Marburg, Germany
| | - Roland Moll
- Institute of Pathology, Philipps-University, 35043 Marburg, Germany
| | - Robert Grosse
- Institute of Pharmacology, Philipps-University, 35032 Marburg, Germany
| | - Thorsten Stiewe
- Institute of Molecular Oncology, Philipps-University, 35043 Marburg, Germany;
- Genomics Core Facility, Philipps-University, 35043 Marburg, Germany
- German Center for Lung Research (DZL), Universities of Giessen and Marburg Lung Center, 35392 Giessen, Germany
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13
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Charles J, Fuchs J, Hefter M, Vischedyk J, Kleint M, Vogiatzi F, Nist A, Timofeev O, Wanzel M, Stiewe T. Monitoring the dynamics of clonal tumor evolution in vivo using secreted luciferases. Eur J Cancer 2016. [DOI: 10.1016/s0959-8049(16)61244-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Timofeev O, Schlereth K, Wanzel M, Braun A, Nieswandt B, Pagenstecher A, Rosenwald A, Elsässer HP, Stiewe T. p53 DNA binding cooperativity is essential for apoptosis and tumor suppression in vivo. Cell Rep 2013; 3:1512-25. [PMID: 23665223 DOI: 10.1016/j.celrep.2013.04.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/08/2013] [Accepted: 04/08/2013] [Indexed: 10/26/2022] Open
Abstract
Four molecules of the tumor suppressor p53 assemble to cooperatively bind proapoptotic target genes. The structural basis for cooperativity consists of interactions between adjacent DNA binding domains. Mutations at the interaction interface that compromise cooperativity were identified in cancer patients, suggesting a requirement of cooperativity for tumor suppression. We report on an analysis of cooperativity mutant p53E177R mice. Apoptotic functions of p53 triggered by DNA damage and oncogenes were abolished in these mice, whereas functions in cell-cycle control, senescence, metabolism, and antioxidant defense were retained and were sufficient to suppress development of spontaneous T cell lymphoma. Cooperativity mutant mice are nevertheless highly cancer prone and susceptible to different oncogene-induced tumors. Our data underscore the relevance of DNA binding cooperativity for p53-dependent apoptosis and tumor suppression and highlight cooperativity mutations as a class of p53 mutations that result in a selective loss of apoptotic functions due to an altered quaternary structure of the p53 tetramer.
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Affiliation(s)
- Oleg Timofeev
- Department of Molecular Oncology, University of Marburg, 35032 Marburg, Germany
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15
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Timofeev O, Cizmecioglu O, Settele F, Kempf T, Hoffmann I. Cdc25 phosphatases are required for timely assembly of CDK1-cyclin B at the G2/M transition. J Biol Chem 2010; 285:16978-90. [PMID: 20360007 DOI: 10.1074/jbc.m109.096552] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Progression through mitosis requires the coordinated regulation of Cdk1 kinase activity. Activation of Cdk1 is a multistep process comprising binding of Cdk1 to cyclin B, relocation of cyclin-kinase complexes to the nucleus, activating phosphorylation of Cdk1 on Thr(161) by the Cdk-activating kinase (CAK; Cdk7 in metazoans), and removal of inhibitory Thr(14) and Tyr(15) phosphorylations. This dephosphorylation is catalyzed by the dual specific Cdc25 phosphatases, which occur in three isoforms in mammalian cells, Cdc25A, -B, and -C. We find that expression of Cdc25A leads to an accelerated G(2)/M phase transition. In Cdc25A-overexpressing cells, Cdk1 exhibits high kinase activity despite being phosphorylated on Tyr(15). In addition, Tyr(15)-phosphorylated Cdk1 binds more cyclin B in Cdc25A-overexpressing cells compared with control cells. Consistent with this observation, we demonstrate that in human transformed cells, Cdc25A and Cdc25B, but not Cdc25C phosphatases have an effect on timing and efficiency of cyclin-kinase complex formation. Overexpression of Cdc25A or Cdc25B promotes earlier assembly and activation of Cdk1-cyclin B complexes, whereas repression of these phosphatases by short hairpin RNA has a reverse effect, leading to a substantial decrease in amounts of cyclin B-bound Cdk1 in G(2) and mitosis. Importantly, we find that Cdc25A overexpression leads to an activation of Cdk7 and increase in Thr(161) phosphorylation of Cdk1. In conclusion, our data suggest that complex assembly and dephosphorylation of Cdk1 at G(2)/M is tightly coupled and regulated by Cdc25 phosphatases.
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Affiliation(s)
- Oleg Timofeev
- Cell Cycle Control and Carcinogenesis, German Cancer Research Center, F045, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
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16
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Timofeev O, Cizmecioglu O, Hu E, Orlik T, Hoffmann I. Human Cdc25A phosphatase has a non-redundant function in G2 phase by activating Cyclin A-dependent kinases. FEBS Lett 2009; 583:841-7. [PMID: 19192479 DOI: 10.1016/j.febslet.2009.01.044] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 01/18/2009] [Accepted: 01/23/2009] [Indexed: 11/24/2022]
Abstract
Cdc25 phosphatases activate Cdk/Cyclin complexes by dephosphorylation and thus promote cell cycle progression. We observed that the peak activity of Cdc25A precedes the one of Cdc25B in prophase and the maximum of Cyclin/Cdk kinase activity. Furthermore, Cdc25A activates both Cdk1-2/Cyclin A and Cdk1/Cyclin B complexes while Cdc25B seems to be involved only in activation of Cdk1/Cyclin B. Concomitantly, repression of Cdc25A led to a decrease in Cyclin A-associated kinase activity and attenuated Cdk1 activation. Our results indicate that Cdc25A acts before Cdc25B - at least in cancer cells, and has non-redundant functions in late G2/early M-phase as a major regulator of Cyclin A/kinase complexes.
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Affiliation(s)
- Oleg Timofeev
- Cell Cycle Control and Carcinogenesis, German Cancer Research Center, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
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17
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Demidov ON, Kek C, Shreeram S, Timofeev O, Fornace AJ, Appella E, Bulavin DV. The role of the MKK6/p38 MAPK pathway in Wip1-dependent regulation of ErbB2-driven mammary gland tumorigenesis. Oncogene 2006; 26:2502-6. [PMID: 17016428 DOI: 10.1038/sj.onc.1210032] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
There is increasing evidence for the role of wild-type p53 induced phosphatase 1 (Wip1) phosphatase in the regulation of tumorigenesis. To evaluate Wip1 as a breast cancer oncogene, we generated a mouse strain with targeted expression of Wip1 to the breast epithelium. We found that these mice are prone to cancer when intercrossed with transgenics expressing the ErbB2 oncogene but not conditional knockouts for Brca2. This tumor-prone phenotype of Wip1 is fully eliminated through attenuation of proliferation by activating the MKK6/p38 mitogen-activated protein kinases (MAPK) cascade in mice bearing a constitutively active form of MKK6. We propose that Wip1 phosphatase operates within the MKK6/p38 MAPK signaling pathway to promote ErbB2-driven mammary gland tumorigenesis.
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Affiliation(s)
- O N Demidov
- Cell Cycle Control and Tumorigenesis Group, Institute of Molecular and Cell Biology, Proteos, Singapore
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18
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Abstract
Emerging evidence supports a role for p38 MAPK in negative regulation of tumorigenesis. Here we show that a subtle activation of p38 MAPK is sufficient to suppress tumorigenesis as measured by the ability to form tumors when MKK6-inducible cells were explanted into nude mice. On the other hand, this activation of p38 MAPK did not necessarily cause an immediate inhibition of cell growth in vitro as measured by standard MTS assay. This data uncovers a new methodology for anti-cancer drugs screening and suggests that a substantial number of potential anti-tumor compounds, such as activators of MKK6/p38 signaling, was missed out in previous high throughput screens based on conventional growth inhibition assays.
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Affiliation(s)
- Oleg Timofeev
- Cell Cycle Control and Tumorigenesis Group, Institute of Molecular and Cell Biology, Singapore
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19
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Bulavin DV, Phillips C, Nannenga B, Timofeev O, Donehower LA, Anderson CW, Appella E, Fornace AJ. Inactivation of the Wip1 phosphatase inhibits mammary tumorigenesis through p38 MAPK-mediated activation of the p16(Ink4a)-p19(Arf) pathway. Nat Genet 2004; 36:343-50. [PMID: 14991053 DOI: 10.1038/ng1317] [Citation(s) in RCA: 339] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2003] [Accepted: 01/26/2004] [Indexed: 12/13/2022]
Abstract
Modulation of tumor suppressor activities may provide new opportunities for cancer therapy. Here we show that disruption of the gene Ppm1d encoding Wip1 phosphatase activated the p53 and p16 (also called Ink4a)-p19 (also called ARF) pathways through p38 MAPK signaling and suppressed in vitro transformation of mouse embryo fibroblasts (MEFs) by oncogenes. Disruption of the gene Cdkn2a (encoding p16 and p19), but not of Trp53 (encoding p53), reconstituted cell transformation in Ppm1d-null MEFs. In vivo, deletion of Ppm1d in mice bearing mouse mammary tumor virus (MMTV) promoter-driven oncogenes Erbb2 (also called c-neu) or Hras1 impaired mammary carcinogenesis, whereas reduced expression of p16 and p19 by methylation-induced silencing or inactivation of p38 MAPK correlated with tumor appearance. We conclude that inactivation or depletion of the Wip1 phosphatase with resultant p38 MAPK activation suppresses tumor appearance by modulating the Cdkn2a tumor-suppressor locus.
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Affiliation(s)
- Dmitry V Bulavin
- Gene Response Section, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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