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Wang W, Albadari N, Du Y, Fowler JF, Sang HT, Xian W, McKeon F, Li W, Zhou J, Zhang R. MDM2 Inhibitors for Cancer Therapy: The Past, Present, and Future. Pharmacol Rev 2024; 76:414-453. [PMID: 38697854 PMCID: PMC11068841 DOI: 10.1124/pharmrev.123.001026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 11/28/2023] [Accepted: 01/16/2024] [Indexed: 05/05/2024] Open
Abstract
Since its discovery over 35 years ago, MDM2 has emerged as an attractive target for the development of cancer therapy. MDM2's activities extend from carcinogenesis to immunity to the response to various cancer therapies. Since the report of the first MDM2 inhibitor more than 30 years ago, various approaches to inhibit MDM2 have been attempted, with hundreds of small-molecule inhibitors evaluated in preclinical studies and numerous molecules tested in clinical trials. Although many MDM2 inhibitors and degraders have been evaluated in clinical trials, there is currently no Food and Drug Administration (FDA)-approved MDM2 inhibitor on the market. Nevertheless, there are several current clinical trials of promising agents that may overcome the past failures, including agents granted FDA orphan drug or fast-track status. We herein summarize the research efforts to discover and develop MDM2 inhibitors, focusing on those that induce MDM2 degradation and exert anticancer activity, regardless of the p53 status of the cancer. We also describe how preclinical and clinical investigations have moved toward combining MDM2 inhibitors with other agents, including immune checkpoint inhibitors. Finally, we discuss the current challenges and future directions to accelerate the clinical application of MDM2 inhibitors. In conclusion, targeting MDM2 remains a promising treatment approach, and targeting MDM2 for protein degradation represents a novel strategy to downregulate MDM2 without the side effects of the existing agents blocking p53-MDM2 binding. Additional preclinical and clinical investigations are needed to finally realize the full potential of MDM2 inhibition in treating cancer and other chronic diseases where MDM2 has been implicated. SIGNIFICANCE STATEMENT: Overexpression/amplification of the MDM2 oncogene has been detected in various human cancers and is associated with disease progression, treatment resistance, and poor patient outcomes. This article reviews the previous, current, and emerging MDM2-targeted therapies and summarizes the preclinical and clinical studies combining MDM2 inhibitors with chemotherapy and immunotherapy regimens. The findings of these contemporary studies may lead to safer and more effective treatments for patients with cancers overexpressing MDM2.
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Affiliation(s)
- Wei Wang
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Najah Albadari
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Yi Du
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Josef F Fowler
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Hannah T Sang
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Wa Xian
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Frank McKeon
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Wei Li
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Jia Zhou
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
| | - Ruiwen Zhang
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy (W.W., Y.D., J.F.F., H.T.S., R.Z.), Drug Discovery Institute (W.W., R.Z.), Stem Cell Center, Department of Biology and Biochemistry (W.X., F.M.), University of Houston, Houston, Texas; College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee (N.A., W.L.); and Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (J.Z.)
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Cicardi M, Hallgren J, Mawrie D, Krishnamurthy K, Markandaiah S, Nelson A, Kankate V, Anderson E, Pasinelli P, Pandey U, Eischen C, Trotti D. C9orf72 poly(PR) mediated neurodegeneration is associated with nucleolar stress. iScience 2023; 26:107505. [PMID: 37664610 PMCID: PMC10470315 DOI: 10.1016/j.isci.2023.107505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/10/2023] [Accepted: 07/26/2023] [Indexed: 09/05/2023] Open
Abstract
The ALS/FTD-linked intronic hexanucleotide repeat expansion in the C9orf72 gene is aberrantly translated in the sense and antisense directions into dipeptide repeat proteins, among which poly proline-arginine (PR) displays the most aggressive neurotoxicity in-vitro and in-vivo. PR partitions to the nucleus when heterologously expressed in neurons and other cell types. We show that by lessening the nuclear accumulation of PR, we can drastically reduce its neurotoxicity. PR strongly accumulates in the nucleolus, a nuclear structure critical in regulating the cell stress response. We determined that, in neurons, PR caused nucleolar stress and increased levels of the transcription factor p53. Downregulating p53 levels also prevented PR-mediated neurotoxicity both in in-vitro and in-vivo models. We investigated if PR could induce the senescence phenotype in neurons. However, we did not observe any indications of such an effect. Instead, we found evidence for the induction of programmed cell death via caspase-3 activation.
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Affiliation(s)
- M.E. Cicardi
- Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - J.H. Hallgren
- Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - D. Mawrie
- Center for Neuroscience, Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
| | - K. Krishnamurthy
- Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - S.S. Markandaiah
- Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - A.T. Nelson
- Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - V. Kankate
- Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - E.N. Anderson
- Center for Neuroscience, Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
| | - P. Pasinelli
- Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - U.B. Pandey
- Center for Neuroscience, Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
| | - C.M. Eischen
- Sidney Kimmel Cancer Center, Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - D. Trotti
- Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
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Sun SY, Crago A. MDM2 Implications for Potential Molecular Pathogenic Therapies of Soft-Tissue Tumors. J Clin Med 2023; 12:3638. [PMID: 37297833 PMCID: PMC10253559 DOI: 10.3390/jcm12113638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 04/14/2023] [Accepted: 05/03/2023] [Indexed: 06/12/2023] Open
Abstract
Murine double minute 2 (MDM2, gene name MDM2) is an oncogene that mainly codes for a protein that acts as an E3 ubiquitin ligase, which targets the tumor suppressor protein p53 for degradation. Overexpression of MDM2 regulates the p53 protein levels by binding to it and promoting its degradation by the 26S proteasome. This leads to the inhibition of p53's ability to regulate cell cycle progression and apoptosis, allowing for uncontrolled cell growth, and can contribute to the development of soft-tissue tumors. The application of cellular stress leads to changes in the binding of MDM2 to p53, which prevents MDM2 from degrading p53. This results in an increase in p53 levels, which triggers either cell cycle arrest or apoptosis. Inhibiting the function of MDM2 has been identified as a potential therapeutic strategy for treating these types of tumors. By blocking the activity of MDM2, p53 function can be restored, potentially leading to tumor cell death and inhibiting the growth of tumors. However, further research is needed to fully understand the implications of MDM2 inhibition for the treatment of soft-tissue tumors and to determine the safety and efficacy of these therapies in clinical trials. An overview of key milestones and potential uses of MDM2 research is presented in this review.
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Affiliation(s)
- Sylvia Yao Sun
- Sarcoma Biology Laboratory, Department of Surgery, Memorial Sloan Kettering Cancer Center, 417 E 618 St, New York, NY 10065, USA
| | - Aimee Crago
- Gastric and Mixed Tumor Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
- Department of Surgery, Weill Cornell Medical Center, 525 E 68th St M 404, New York, NY 10065, USA
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Giansanti C, Manzini V, Dickmanns A, Dickmanns A, Palumbieri MD, Sanchi A, Kienle SM, Rieth S, Scheffner M, Lopes M, Dobbelstein M. MDM2 binds and ubiquitinates PARP1 to enhance DNA replication fork progression. Cell Rep 2022; 39:110879. [PMID: 35649362 DOI: 10.1016/j.celrep.2022.110879] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 04/15/2022] [Accepted: 05/05/2022] [Indexed: 11/03/2022] Open
Abstract
The MDM2 oncoprotein antagonizes the tumor suppressor p53 by physical interaction and ubiquitination. However, it also sustains the progression of DNA replication forks, even in the absence of functional p53. Here, we show that MDM2 binds, inhibits, ubiquitinates, and destabilizes poly(ADP-ribose) polymerase 1 (PARP1). When cellular MDM2 levels are increased, this leads to accelerated progression of DNA replication forks, much like pharmacological inhibition of PARP1. Conversely, overexpressed PARP1 restores normal fork progression despite elevated MDM2. Strikingly, MDM2 profoundly reduces the frequency of fork reversal, revealed as four-way junctions through electron microscopy. Depletion of RECQ1 or the primase/polymerase (PRIMPOL) reverses the MDM2-mediated acceleration of the nascent DNA elongation rate. MDM2 also increases the occurrence of micronuclei, and it exacerbates camptothecin-induced cell death. In conclusion, high MDM2 levels phenocopy PARP inhibition in modulation of fork restart, representing a potential vulnerability of cancer cells.
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Affiliation(s)
- Celeste Giansanti
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Valentina Manzini
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Antje Dickmanns
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Achim Dickmanns
- Department of Molecular Structural Biology, Institute of Microbiology & Genetics, GZMB, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Maria Dilia Palumbieri
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Andrea Sanchi
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | | | - Sonja Rieth
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Martin Scheffner
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Matthias Dobbelstein
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
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Haronikova L, Bonczek O, Zatloukalova P, Kokas-Zavadil F, Kucerikova M, Coates PJ, Fahraeus R, Vojtesek B. Resistance mechanisms to inhibitors of p53-MDM2 interactions in cancer therapy: can we overcome them? Cell Mol Biol Lett 2021; 26:53. [PMID: 34911439 PMCID: PMC8903693 DOI: 10.1186/s11658-021-00293-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/05/2021] [Indexed: 12/13/2022] Open
Abstract
Since the discovery of the first MDM2 inhibitors, we have gained deeper insights into the cellular roles of MDM2 and p53. In this review, we focus on MDM2 inhibitors that bind to the p53-binding domain of MDM2 and aim to disrupt the binding of MDM2 to p53. We describe the basic mechanism of action of these MDM2 inhibitors, such as nutlin-3a, summarise the determinants of sensitivity to MDM2 inhibition from p53-dependent and p53-independent points of view and discuss the problems with innate and acquired resistance to MDM2 inhibition. Despite progress in MDM2 inhibitor design and ongoing clinical trials, their broad use in cancer treatment is not fulfilling expectations in heterogenous human cancers. We assess the MDM2 inhibitor types in clinical trials and provide an overview of possible sources of resistance to MDM2 inhibition, underlining the need for patient stratification based on these aspects to gain better clinical responses, including the use of combination therapies for personalised medicine.
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Affiliation(s)
- Lucia Haronikova
- RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic.
| | - Ondrej Bonczek
- RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic
- Department of Medical Biosciences, Umea University, 901 87, Umea, Vasterbotten, Sweden
| | - Pavlina Zatloukalova
- RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic
| | - Filip Kokas-Zavadil
- RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic
| | - Martina Kucerikova
- RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Philip J Coates
- RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic
| | - Robin Fahraeus
- RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic
- Department of Medical Biosciences, Umea University, 901 87, Umea, Vasterbotten, Sweden
- Inserm UMRS1131, Institut de Génétique Moléculaire, Université Paris 7, Hôpital St. Louis, 75010, Paris, France
| | - Borivoj Vojtesek
- RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic.
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Chemotherapy of HER2- and MDM2-Enriched Breast Cancer Subtypes Induces Homologous Recombination DNA Repair and Chemoresistance. Cancers (Basel) 2021; 13:cancers13184501. [PMID: 34572735 PMCID: PMC8471926 DOI: 10.3390/cancers13184501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/28/2021] [Accepted: 09/01/2021] [Indexed: 11/25/2022] Open
Abstract
Simple Summary MDM2 is a protein responsible for negative regulation of the p53 tumor suppressor. In addition, MDM2 exhibits chaperone-like properties similar to the HSP90 molecular chaperone. Multiple studies revealed that MDM2 is deeply involved in cancer development and progression. Some recently published results indicate that the role of MDM2 in DNA repair inhibition is more complex than previously thought. We show that MDM2 is directly involved in the homologous recombination DNA repair, and its chaperone-like activity is crucial for this function. The DNA repair inhibition is a result of inefficient MDM2 dissociation from the NBN protein complex. When cancer cells are treated with chemotherapy, MDM2 can be easily released from the interaction and degraded, resulting in effective homologous recombination DNA repair, which translates into the acquisition of a chemoresistant phenotype by the tumor. This knowledge may allow for identification of the patients that are at particular risk of tumor chemoresistance. Abstract Analyzing the TCGA breast cancer database, we discovered that patients with the HER2 cancer subtype and overexpression of MDM2 exhibited decreased post-treatment survival. Inhibition of MDM2 expression in the SKBR3 cell line (HER2 subtype) diminished the survival of cancer cells treated with doxorubicin, etoposide, and camptothecin. Moreover, we demonstrated that inhibition of MDM2 expression diminished DNA repair by homologous recombination (HR) and sensitized SKBR3 cells to a PARP inhibitor, olaparib. In H1299 (TP53−/−) cells treated with neocarzinostatin (NCS), overexpression of MDM2 WT or E3-dead MDM2 C478S variant stimulated the NCS-dependent phosphorylation of ATM, NBN, and BRCA1, proteins involved in HR DNA repair. However, overexpression of chaperone-dead MDM2 K454A variant diminished phosphorylation of these proteins as well as the HR DNA repair. Moreover, we demonstrated that, upon NCS treatment, MDM2 K454A interacted with NBN more efficiently than MDM2 WT and that MDM2 WT was degraded more efficiently than MDM2 K454A. Using a proliferation assay, we showed that overexpression of MDM2 WT, but not MDM2 K454A, led to acquisition of resistance to NCS. The presented results indicate that, following chemotherapy, MDM2 WT was released from MDM2-NBN complex and efficiently degraded, hence allowing extensive HR DNA repair leading to the acquisition of chemoresistance by cancer cells.
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Voutsadakis IA. Mutations of p53 associated with pancreatic cancer and therapeutic implications. Ann Hepatobiliary Pancreat Surg 2021; 25:315-327. [PMID: 34402431 PMCID: PMC8382872 DOI: 10.14701/ahbps.2021.25.3.315] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/19/2021] [Accepted: 05/31/2021] [Indexed: 12/30/2022] Open
Abstract
Pancreatic adenocarcinoma is a malignancy with rising incidence and grim prognosis. Despite improvements in therapeutics for treating metastatic pancreatic cancer, this disease is invariably fatal with survival time less than a few years. New molecular understanding of the pathogenesis of pancreatic adenocarcinoma based on efforts led by The Cancer Genome Atlas and other groups has elucidated the landscape of this disease and started to produce therapeutic results, leading to the first introduction of targeted therapies for subsets of pancreatic cancers bearing specific molecular lesions such as BRCA mutations. These efforts have highlighted that subsets of pancreatic cancers are particularly sensitive to chemotherapy. The most common molecular lesions in pancreatic adenocarcinomas are mutations in an oncogene KRAS and the TP53 gene that encodes for tumor suppressor protein p53. This paper will review the landscape of pancreatic cancers, focusing on mutations of p53, a major tumor suppressor protein, in pancreatic cancers and possible therapeutic repercussions.
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Affiliation(s)
- Ioannis A Voutsadakis
- Algoma District Cancer Program, Sault Area Hospital, Sault Ste. Marie, ON, Canada.,Section of Internal Medicine, Division of Clinical Sciences, Northern Ontario School of Medicine, Sudbury, ON, Canada
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Miles X, Vandevoorde C, Hunter A, Bolcaen J. MDM2/X Inhibitors as Radiosensitizers for Glioblastoma Targeted Therapy. Front Oncol 2021; 11:703442. [PMID: 34307171 PMCID: PMC8296304 DOI: 10.3389/fonc.2021.703442] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 06/24/2021] [Indexed: 12/24/2022] Open
Abstract
Inhibition of the MDM2/X-p53 interaction is recognized as a potential anti-cancer strategy, including the treatment of glioblastoma (GB). In response to cellular stressors, such as DNA damage, the tumor suppression protein p53 is activated and responds by mediating cellular damage through DNA repair, cell cycle arrest and apoptosis. Hence, p53 activation plays a central role in cell survival and the effectiveness of cancer therapies. Alterations and reduced activity of p53 occur in 25-30% of primary GB tumors, but this number increases drastically to 60-70% in secondary GB. As a result, reactivating p53 is suggested as a treatment strategy, either by using targeted molecules to convert the mutant p53 back to its wild type form or by using MDM2 and MDMX (also known as MDM4) inhibitors. MDM2 down regulates p53 activity via ubiquitin-dependent degradation and is amplified or overexpressed in 14% of GB cases. Thus, suppression of MDM2 offers an opportunity for urgently needed new therapeutic interventions for GB. Numerous small molecule MDM2 inhibitors are currently undergoing clinical evaluation, either as monotherapy or in combination with chemotherapy and/or other targeted agents. In addition, considering the major role of both p53 and MDM2 in the downstream signaling response to radiation-induced DNA damage, the combination of MDM2 inhibitors with radiation may offer a valuable therapeutic radiosensitizing approach for GB therapy. This review covers the role of MDM2/X in cancer and more specifically in GB, followed by the rationale for the potential radiosensitizing effect of MDM2 inhibition. Finally, the current status of MDM2/X inhibition and p53 activation for the treatment of GB is given.
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Affiliation(s)
- Xanthene Miles
- Radiobiology, Radiation Biophysics Division, Nuclear Medicine Department, iThemba LABS, Cape Town, South Africa
| | - Charlot Vandevoorde
- Radiobiology, Radiation Biophysics Division, Nuclear Medicine Department, iThemba LABS, Cape Town, South Africa
| | - Alistair Hunter
- Radiobiology Section, Division of Radiation Oncology, Department of Radiation Medicine, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa
| | - Julie Bolcaen
- Radiobiology, Radiation Biophysics Division, Nuclear Medicine Department, iThemba LABS, Cape Town, South Africa
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Salomao N, Karakostis K, Hupp T, Vollrath F, Vojtesek B, Fahraeus R. What do we need to know and understand about p53 to improve its clinical value? J Pathol 2021; 254:443-453. [DOI: 10.1002/path.5677] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/25/2021] [Accepted: 04/01/2021] [Indexed: 12/19/2022]
Affiliation(s)
- Norman Salomao
- Inserm UMRS1131, Institut de Génétique Moléculaire, Université Paris 7, Hôpital St Louis Paris France
| | - Konstantinos Karakostis
- Inserm UMRS1131, Institut de Génétique Moléculaire, Université Paris 7, Hôpital St Louis Paris France
| | - Ted Hupp
- University of Gdansk, International Centre for Cancer Vaccine Science Gdansk Poland
- University of Edinburgh, Institute of Genetics and Molecular Medicine Edinburgh UK
| | - Friz Vollrath
- Department of Zoology, Zoology Research and Administration Building University of Oxford Oxford UK
| | | | - Robin Fahraeus
- Inserm UMRS1131, Institut de Génétique Moléculaire, Université Paris 7, Hôpital St Louis Paris France
- University of Gdansk, International Centre for Cancer Vaccine Science Gdansk Poland
- RECAMO, Masaryk Memorial Cancer Institute Brno Czech Republic
- Department of Medical Biosciences Building 6M, Umeå University Umeå Sweden
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10
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Dobbelstein M, Levine AJ. Mdm2: Open questions. Cancer Sci 2020; 111:2203-2211. [PMID: 32335977 PMCID: PMC7385351 DOI: 10.1111/cas.14433] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/16/2020] [Accepted: 04/18/2020] [Indexed: 12/16/2022] Open
Abstract
The Mdm2 oncoprotein and its association with p53 were discovered 30 years ago, and a cornucopia of activities and regulatory pathways have been associated with it. In this review, we will raise questions about Mdm2 and its cousin Mdm4 that we consider worth pursuing in future research, reaching from molecular structures and intracellular activities all the way to development, evolution, and cancer therapy. We anticipate that such research will not only close a few gaps in our knowledge but could add new dimensions to our current view. This compilation of questions contributes to the preparation for the 10th Mdm2 Workshop in Tokyo.
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Affiliation(s)
- Matthias Dobbelstein
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, Göttingen, Germany
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11
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Wohlberedt K, Klusmann I, Derevyanko PK, Henningsen K, Choo JAMY, Manzini V, Magerhans A, Giansanti C, Eischen CM, Jochemsen AG, Dobbelstein M. Mdm4 supports DNA replication in a p53-independent fashion. Oncogene 2020; 39:4828-4843. [PMID: 32427989 PMCID: PMC7521021 DOI: 10.1038/s41388-020-1325-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 01/09/2023]
Abstract
The Mdm4 (alias MdmX) oncoprotein, like its paralogue and interaction partner Mdm2, antagonizes the tumor suppressor p53. p53-independent roles of the Mdm proteins are emerging, and we have reported the ability of Mdm2 to modify chromatin and to support DNA replication by suppressing the formation of R-loops (DNA/RNA-hybrids). We show here that the depletion of Mdm4 in p53-deficient cells compromises DNA replication fork progression as well. Among various deletion mutants, only full-length Mdm4 was able to support DNA replication fork progression. Co-depletion of Mdm4 and Mdm2 further impaired DNA replication, and the overexpression of each partially compensated for the other's loss. Despite impairing replication, Mdm4 depletion only marginally hindered cell proliferation, likely due to compensation through increased firing of replication origins. However, depleting Mdm4 sensitized p53-/- cells to the nucleoside analog gemcitabine, raising the future perspective of using Mdm4 inhibitors as chemosensitizers. Mechanistically, Mdm4 interacts with members of the Polycomb Repressor Complexes and supports the ubiquitination of H2A, thereby preventing the accumulation of DNA/RNA-hybrids. Thus, in analogy to previously reported activities of Mdm2, Mdm4 enables unperturbed DNA replication through the avoidance of R-loops.
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Affiliation(s)
- Kai Wohlberedt
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany
| | - Ina Klusmann
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany
| | - Polina K Derevyanko
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany
| | - Kester Henningsen
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany
| | - Josephine Ann Mun Yee Choo
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany
| | - Valentina Manzini
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany
| | - Anna Magerhans
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany
| | - Celeste Giansanti
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany
| | - Christine M Eischen
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States
| | - Aart G Jochemsen
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Matthias Dobbelstein
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, D-37077, Göttingen, Germany.
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12
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Li W, Peng X, Lang J, Xu C. Targeting Mouse Double Minute 2: Current Concepts in DNA Damage Repair and Therapeutic Approaches in Cancer. Front Pharmacol 2020; 11:631. [PMID: 32477121 PMCID: PMC7232544 DOI: 10.3389/fphar.2020.00631] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/21/2020] [Indexed: 01/14/2023] Open
Abstract
Defects in DNA damage repair may cause genome instability and cancer development. The tumor suppressor gene p53 regulates cell cycle arrest to allow time for DNA repair. The oncoprotein mouse double minute 2 (MDM2) promotes cell survival, proliferation, invasion, and therapeutic resistance in many types of cancer. The major role of MDM2 is to inhibit p53 activity and promote its degradation. In this review, we describe the influence of MDM2 on genomic instability, the role of MDM2 on releasing p53 and binding DNA repair proteins to inhibit repair, and the regulation network of MDM2 including its transcriptional modifications, protein stability, and localization following DNA damage in genome integrity maintenance and in MDM2-p53 axis control. We also discuss p53-dependent and p53 independent oncogenic function of MDM2 and the outcomes of clinical trials that have been used with clinical inhibitors targeting p53-MDM2 to treat certain cancers.
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Affiliation(s)
- Wen Li
- Cancer Clinical Research Center & Integrative Cancer Center, Sichuan Cancer Hospital & Institute Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Xinhao Peng
- Cancer Clinical Research Center & Integrative Cancer Center, Sichuan Cancer Hospital & Institute Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China.,Radiation Oncology Key Laboratory of Sichuan Province, Sichuan Cancer Hospital & Institute Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Jinyi Lang
- Cancer Clinical Research Center & Integrative Cancer Center, Sichuan Cancer Hospital & Institute Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China.,Radiation Oncology Key Laboratory of Sichuan Province, Sichuan Cancer Hospital & Institute Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Chuan Xu
- Cancer Clinical Research Center & Integrative Cancer Center, Sichuan Cancer Hospital & Institute Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
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13
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Magnussen HM, Ahmed SF, Sibbet GJ, Hristova VA, Nomura K, Hock AK, Archibald LJ, Jamieson AG, Fushman D, Vousden KH, Weissman AM, Huang DT. Structural basis for DNA damage-induced phosphoregulation of MDM2 RING domain. Nat Commun 2020; 11:2094. [PMID: 32350255 PMCID: PMC7190642 DOI: 10.1038/s41467-020-15783-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 03/27/2020] [Indexed: 01/30/2023] Open
Abstract
Phosphorylation of MDM2 by ATM upon DNA damage is an important mechanism for deregulating MDM2, thereby leading to p53 activation. ATM phosphorylates multiple residues near the RING domain of MDM2, but the underlying molecular basis for deregulation remains elusive. Here we show that Ser429 phosphorylation selectively enhances the ubiquitin ligase activity of MDM2 homodimer but not MDM2-MDMX heterodimer. A crystal structure of phospho-Ser429 (pS429)-MDM2 bound to E2-ubiquitin reveals a unique 310-helical feature present in MDM2 homodimer that allows pS429 to stabilize the closed E2-ubiquitin conformation and thereby enhancing ubiquitin transfer. In cells Ser429 phosphorylation increases MDM2 autoubiquitination and degradation upon DNA damage, whereas S429A substitution protects MDM2 from auto-degradation. Our results demonstrate that Ser429 phosphorylation serves as a switch to boost the activity of MDM2 homodimer and promote its self-destruction to enable rapid p53 stabilization and resolve a long-standing controversy surrounding MDM2 auto-degradation in response to DNA damage.
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Affiliation(s)
- Helge M Magnussen
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Syed F Ahmed
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Gary J Sibbet
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Ventzislava A Hristova
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Koji Nomura
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Andreas K Hock
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
- AstraZeneca, AstraZeneca R&D, Innovative Medicines, Discovery Sciences, Darwin (Building 310), Cambridge Science Park, Milton Road, Cambridge, CB4 0WG, UK
| | - Lewis J Archibald
- School of Chemistry, University of Glasgow, Joseph Black Building, G12 8QQ, Glasgow, UK
| | - Andrew G Jamieson
- School of Chemistry, University of Glasgow, Joseph Black Building, G12 8QQ, Glasgow, UK
| | - David Fushman
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD, 20742, USA
| | | | - Allan M Weissman
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Danny T Huang
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK.
- Institute of Cancer Sciences, University of Glasgow, Glasgow, G61 1QH, UK.
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14
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Zhang R, Ma J, Avery JT, Sambandam V, Nguyen TH, Xu B, Suto MJ, Boohaker RJ. GLI1 Inhibitor SRI-38832 Attenuates Chemotherapeutic Resistance by Downregulating NBS1 Transcription in BRAF V600E Colorectal Cancer. Front Oncol 2020; 10:241. [PMID: 32185127 PMCID: PMC7058788 DOI: 10.3389/fonc.2020.00241] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 02/12/2020] [Indexed: 12/13/2022] Open
Abstract
Resistance to radiation and chemotherapy in colorectal cancer (CRC) patients contribute significantly to refractory disease and disease progression. Herein, we provide mechanistic rationale for acquired or inherent chemotherapeutic resistance to the anti-tumor effects of 5-fluorouracil (5-FU) that is linked to oncogenic GLI1 transcription activity and NBS1 overexpression. Patients with high levels of GLI1 also expressed high levels of NBS1. Non-canonical activation of GLI1 is driven through oncogenic pathways in CRC, like the BRAFV600E mutation. GLI1 was identified as a novel regulator of NBS1 and discovered that by knocking down GLI1 levels in vitro, diminished NBS1 expression, increased DNA damage/apoptosis, and re-sensitization of 5-FU resistant cancer to treatment was observed. Furthermore, a novel GLI1 inhibitor, SRI-38832, which exhibited pharmacokinetic properties suitable for in vivo testing, was identified. GLI1 inhibition in a murine BRAFV600E variant xenograft model of CRC resulted in the same down-regulation of NBS1 observed in vitro as well as significant reduction of tumor growth/burden. GLI1 inhibition could therefore be a therapeutic option for 5-FU resistant and BRAFV600E variant CRC patients.
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Affiliation(s)
- Ruowen Zhang
- Southern Research, Division of Drug Discovery, Birmingham, AL, United States
| | - Jinlu Ma
- Department of Radiation Oncology, First Affiliated Hospital, Xian Jiaotong University, Xi'an, China
| | - Justin T. Avery
- Southern Research, Division of Drug Discovery, Birmingham, AL, United States
| | - Vijaya Sambandam
- Southern Research, Division of Drug Discovery, Birmingham, AL, United States
| | - Theresa H. Nguyen
- Southern Research, Division of Drug Discovery, Birmingham, AL, United States
| | - Bo Xu
- Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Mark J. Suto
- Southern Research, Division of Drug Discovery, Birmingham, AL, United States
| | - Rebecca J. Boohaker
- Southern Research, Division of Drug Discovery, Birmingham, AL, United States
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15
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Mdm2 and MdmX RING Domains Play Distinct Roles in the Regulation of p53 Responses: A Comparative Study of Mdm2 and MdmX RING Domains in U2OS Cells. Int J Mol Sci 2020; 21:ijms21041309. [PMID: 32075226 PMCID: PMC7072982 DOI: 10.3390/ijms21041309] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/07/2020] [Accepted: 02/09/2020] [Indexed: 12/22/2022] Open
Abstract
Dysfunction of the tumor suppressor p53 occurs in most human cancers. Mdm2 and MdmX are homologous proteins from the Mdm (Murine Double Minute) protein family, which play a critical role in p53 inactivation and degradation. The two proteins interact with one another via the intrinsic RING (Really Interesting New Gene) domains to achieve the negative regulation of p53. The downregulation of p53 is accomplished by Mdm2-mediated p53 ubiquitination and proteasomal degradation through the ubiquitin proteolytic system and by Mdm2 and MdmX mediated inhibition of p53 transactivation. To investigate the role of the RING domain of Mdm2 and MdmX, an analysis of the distinct functionalities of individual RING domains of the Mdm proteins on p53 regulation was conducted in human osteosarcoma (U2OS) cell line. Mdm2 RING domain was observed mainly localized in the cell nucleus, contrasting the localization of MdmX RING domain in the cytoplasm. Mdm2 RING was found to possess an endogenous E3 ligase activity, whereas MdmX RING did not. Both Mdm2 and MdmX RING domains were able to dimerize with endogenous full-length Mdm2 and MdmX protein and affect their cellular function. The results showed that overexpression of the Mdm2 or MdmX RING domains interfered with the endogenous full-length Mdm2 and MdmX activity and resulted in p53 stabilization and p53 target gene activation. However, both Mdm RING domains showed oncogenic activity in a colony formation assay, suggesting that the Mdm RING domains possess p53-independent oncogenic properties. This study highlights the distinct structural and functional traits of the RING domain of Mdm2 and MdmX and characterized their role in cellular responses through interfering with p53 dependent signaling pathway.
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16
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Wang W, Qin JJ, Rajaei M, Li X, Yu X, Hunt C, Zhang R. Targeting MDM2 for novel molecular therapy: Beyond oncology. Med Res Rev 2019; 40:856-880. [PMID: 31587329 DOI: 10.1002/med.21637] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 08/20/2019] [Accepted: 08/21/2019] [Indexed: 12/14/2022]
Abstract
The murine double minute 2 (MDM2) oncogene exerts major oncogenic activities in human cancers; it is not only the best-documented negative regulator of the p53 tumor suppressor, but also exerts p53-independent activities. There is an increasing interest in developing MDM2-based targeted therapies. Several classes of MDM2 inhibitors have been evaluated in preclinical models, with a few entering clinical trials, mainly for cancer therapy. However, noncarcinogenic roles for MDM2 have also been identified, demonstrating that MDM2 is involved in many chronic diseases and conditions such as inflammation and autoimmune diseases, dementia and neurodegenerative diseases, heart failure and cardiovascular diseases, nephropathy, diabetes, obesity, and sterility. MDM2 inhibitors have been shown to have promising therapeutic efficacy for treating inflammation and other nonmalignant diseases in preclinical evaluations. Therefore, targeting MDM2 may represent a promising approach for treating and preventing these nonmalignant diseases. In addition, a better understanding of how MDM2 works in nonmalignant diseases may provide new biomarkers for their diagnosis, prognostic prediction, and monitoring of therapeutic outcome. In this review article, we pay special attention to the recent findings related to the roles of MDM2 in the pathogenesis of several nonmalignant diseases, the therapeutic potential of its downregulation or inhibition, and its use as a biomarker.
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Affiliation(s)
- Wei Wang
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas.,Drug Discovery Institute, University of Houston, Houston, Texas
| | - Jiang-Jiang Qin
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Mehrdad Rajaei
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Xin Li
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Xiaoyi Yu
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Courtney Hunt
- Drug Discovery Institute, University of Houston, Houston, Texas
| | - Ruiwen Zhang
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas.,Drug Discovery Institute, University of Houston, Houston, Texas
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17
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Zhou Z, Wang L, Ge F, Gong P, Wang H, Wang F, Chen L, Liu L. Pold3 is required for genomic stability and telomere integrity in embryonic stem cells and meiosis. Nucleic Acids Res 2019; 46:3468-3486. [PMID: 29447390 PMCID: PMC6283425 DOI: 10.1093/nar/gky098] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 02/01/2018] [Indexed: 12/29/2022] Open
Abstract
Embryonic stem cells (ESCs) and meiosis are featured by relatively higher frequent homologous recombination associated with DNA double strand breaks (DSB) repair. Here, we show that Pold3 plays important roles in DSB repair, telomere maintenance and genomic stability of both ESCs and spermatocytes in mice. By attempting to generate Pold3 deficient mice using CRISPR/Cas9 or transcription activator-like effector nucleases, we show that complete loss of Pold3 (Pold3−/−) resulted in early embryonic lethality at E6.5. Rapid DNA damage response and massive apoptosis occurred in both outgrowths of Pold3-null (Pold3−/−) blastocysts and Pold3 inducible knockout (iKO) ESCs. While Pold3−/− ESCs were not achievable, Pold3 iKO led to increased DNA damage response, telomere loss and chromosome breaks accompanied by extended S phase. Meanwhile, loss of Pold3 resulted in replicative stress, micronucleation and aneuploidy. Also, DNA repair was impaired in Pold3+/− or Pold3 knockdown ESCs. Moreover, Pold3 mediates DNA replication and repair by regulating 53BP1, RIF1, ATR and ATM pathways. Furthermore, spermatocytes of Pold3 haploinsufficient (Pold3+/−) mice with increasing age displayed impaired DSB repair, telomere shortening and loss, and chromosome breaks, like Pold3 iKO ESCs. These data suggest that Pold3 maintains telomere integrity and genomic stability of both ESCs and meiosis by suppressing replicative stress.
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Affiliation(s)
- Zhongcheng Zhou
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.,Department of Cell Biology and Genetics, The Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Lingling Wang
- Department of Cell Biology and Genetics, The Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Feixiang Ge
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.,Department of Cell Biology and Genetics, The Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Peng Gong
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.,Department of Cell Biology and Genetics, The Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Hua Wang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.,Department of Cell Biology and Genetics, The Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Feng Wang
- Department of Genetics, School of basic Medical Sciences, Tianjin Medical University, Tianjin 300070, China
| | - Lingyi Chen
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.,Department of Cell Biology and Genetics, The Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.,Department of Cell Biology and Genetics, The Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
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18
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Sawada R, Maehara R, Oshikiri T, Nakamura T, Itoh T, Kodama Y, Kakeji Y, Zen Y. MDM2 copy number increase: a poor prognostic, molecular event in esophageal squamous cell carcinoma. Hum Pathol 2019; 89:1-9. [PMID: 31004651 DOI: 10.1016/j.humpath.2019.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/07/2019] [Accepted: 04/08/2019] [Indexed: 12/09/2022]
Abstract
The present study aimed to elucidate the clinicopathological significance of molecular alterations in MDM2 in esophageal squamous cell carcinoma (ESCC). A total of 399 resected cases of ESCC were examined by dual-color in situ hybridization for MDM2 and immunohistochemistry for p53 using tissue microarrays. Clinicopathological features were correlated with the MDM2 status. Among 362 cases with a successful dual-color in situ hybridization analysis, 19 (5%) and 13 (4%) had MDM2 amplification and chromosome 12 polysomy, respectively, and these were examined as an MDM2-positive group. A comparison between amplified and polysomic cases revealed that the latter were more strongly associated with preoperative chemotherapy than the former. Sixteen (50%) of 32 MDM2-positive cases had positive results in all tissue cores examined, indicating diffuse MDM2 alterations. Cases with the diffuse alteration of MDM2 were characterized by an advanced pT stage and extensive vascular infiltration. The relationship between MDM2 copy number increases and p53 mutations was weak, with the overexpression of p53 being similarly detected in MDM2-positive and MDM2-negative cases (59% versus 49%; P = .267). Overall survival was shorter in patients with MDM2-positive ESCC than in those without MDM2 alterations (P = .033). The poor prognostic value of MDM2 alterations became more obvious when only diffusely altered cases were counted (P = .005). In conclusion, the present study revealed that MDM2 copy number increases occurred in 9% of ESCC cases, and MDM2 alterations, particularly diffuse abnormalities, were associated with a poor prognosis. MDM2-altered ESCC may achieve beneficial effects from MDM2-targeted therapy.
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Affiliation(s)
- Ryuichiro Sawada
- Department of Diagnostic Pathology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan; Department of Gastrointestinal Surgery, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
| | - Ritsuko Maehara
- Department of Gastrointestinal Surgery, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
| | - Taro Oshikiri
- Department of Gastrointestinal Surgery, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
| | - Tetsu Nakamura
- Department of Gastrointestinal Surgery, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
| | - Tomoo Itoh
- Department of Diagnostic Pathology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
| | - Yuzo Kodama
- Department of Gastroenterology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
| | - Yoshihiro Kakeji
- Department of Gastrointestinal Surgery, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
| | - Yoh Zen
- Department of Diagnostic Pathology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan; Institute of Liver Studies, King's College Hospital & King's College London, London SE5 9RS, United Kingdom.
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19
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Cao Z, Xue J, Cheng Y, Wang J, Liu Y, Li H, Jiang W, Li G, Gui Y, Zhang X. MDM2 promotes genome instability by ubiquitinating the transcription factor HBP1. Oncogene 2019; 38:4835-4855. [PMID: 30816344 PMCID: PMC6756050 DOI: 10.1038/s41388-019-0761-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 12/09/2018] [Accepted: 02/10/2019] [Indexed: 12/26/2022]
Abstract
Genome instability is a common feature of tumor cells, and the persistent presence of genome instability is a potential mechanism of tumorigenesis. The E3 ubiquitin ligase MDM2 is intimately involved in genome instability, but its mechanisms are unclear. Our data demonstrated that the transcription factor HBP1 is a target of MDM2. MDM2 facilitates HBP1 proteasomal degradation by ubiquitinating HBP1, regardless of p53 status, thus attenuating the transcriptional inhibition of HBP1 in the expression of its target genes, such as the DNA methyltransferase DNMT1 and histone methyltransferase EZH2, which results in global DNA hypermethylation and histone hypermethylation and ultimately genome instability. The repression of HBP1 by MDM2 finally promotes cell growth and tumorigenesis. Next, we thoroughly explored the regulatory mechanism of the MDM2/HBP1 axis in DNA damage repair following ionizing radiation. Our data indicated that MDM2 overexpression-mediated repression of HBP1 delays DNA damage repair and causes cell death in a p53-independent manner. This investigation elucidated the mechanism of how MDM2 promotes genome instability and enhances tumorigenesis in the absence of p53, thus providing a theoretical and experimental basis for targeting MDM2 as a cancer therapy.
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Affiliation(s)
- Zhengyi Cao
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China
| | - Junhui Xue
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China
| | - Yuning Cheng
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China
| | - Jiyin Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China
| | - Yujuan Liu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China
| | - Hui Li
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China
| | - Wei Jiang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China
| | - Gang Li
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China
| | - Yaoting Gui
- Guangdong and Shenzhen Key Laboratory of Male Reproductive Medicine and Genetics, Institute of Urology, Peking University Shenzhen Hospital, Shenzhen-Peking University-the Hong Kong University of Science and Technology Medical Center, Shenzhen, 518000, P. R. China
| | - Xiaowei Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Peking University Health Science Center, Beijing, 100191, P. R. China.
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20
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Puccetti MV, Adams CM, Kushinsky S, Eischen CM. Smarcal1 and Zranb3 Protect Replication Forks from Myc-Induced DNA Replication Stress. Cancer Res 2019; 79:1612-1623. [PMID: 30610086 DOI: 10.1158/0008-5472.can-18-2705] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/08/2018] [Accepted: 12/27/2018] [Indexed: 02/01/2023]
Abstract
The cellular DNA replication stress response functions to stabilize DNA replication forks and inhibits genome instability and tumorigenesis induced by oncogenes. However, the specific proteins required for resolving oncogenic stress remain poorly understood. Here we report that Smarcal1 and Zranb3, closely related replication fork-remodeling proteins, have nonredundant functions in resolving Myc-induced DNA replication stress. In Myc-overexpressing primary cells, significant differences in replication fork stalling, collapse, and DNA damage were detected between cells deficient in Smarcal1 or Zranb3, leading to changes in proliferation and apoptosis. These differences were also reflected in Myc-induced lymphoma development; haploinsufficiency of Smarcal1 resulted in accelerated lymphomagenesis, whereas haploinsufficiency of Zranb3 inhibited lymphoma development. Complete loss of either protein resulted in disparate survival outcomes. Our results reveal that endogenous replication stress from Myc in primary cells requires both alleles of Smarcal1 and Zranb3 and demonstrate the requirement of both proteins to stabilize replication forks upon Myc dysregulation in a nonredundant manner. SIGNIFICANCE: Smarcal1 and Zranb3 are essential, but nonredundant, for responding to DNA replication stress and stabilizing replication forks following Myc overexpression.See related commentary by Sotiriou and Halazonetis, p. 1297.
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Affiliation(s)
- Matthew V Puccetti
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania.,Medical Scientist Training Program, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Clare M Adams
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Saul Kushinsky
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Christine M Eischen
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania.
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21
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Chromatin modifiers Mdm2 and RNF2 prevent RNA:DNA hybrids that impair DNA replication. Proc Natl Acad Sci U S A 2018; 115:E11311-E11320. [PMID: 30413623 DOI: 10.1073/pnas.1809592115] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The p53-Mdm2 system is key to tumor suppression. We have recently reported that p53 as well as Mdm2 are capable of supporting DNA replication fork progression. On the other hand, we found that Mdm2 is a modifier of chromatin, modulating polycomb repressor complex (PRC)-driven histone modifications. Here we show that, similar to Mdm2 knockdown, the depletion of PRC members impairs DNA synthesis, as determined in fiber assays. In particular, the ubiquitin ligase and PRC1 component RNF2/Ring1B is required to support DNA replication, similar to Mdm2. Moreover, the Ring finger domain of Mdm2 is not only essential for its ubiquitin ligase activity, but also for proper DNA replication. Strikingly, Mdm2 overexpression can rescue RNF2 depletion with regard to DNA replication fork progression, and vice versa, strongly suggesting that the two ubiquitin ligases perform overlapping functions in this context. H2A overexpression also rescues fork progression upon depletion of Mdm2 or RNF2, but only when the ubiquitination sites K118/K119 are present. Depleting the H2A deubiquitinating enzyme BAP1 reduces the fork rate, suggesting that both ubiquitination and deubiquitination of H2A are required to support fork progression. The depletion of Mdm2 elicits the accumulation of RNA/DNA hybrids, suggesting R-loop formation as a mechanism of impaired DNA replication. Accordingly, RNase H overexpression or the inhibition of the transcription elongation kinase CDK9 each rescues DNA replication upon depletion of Mdm2 or RNF2. Taken together, our results suggest that chromatin modification by Mdm2 and PRC1 ensures smooth DNA replication through the avoidance of R-loop formation.
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22
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Zhao Y, Tan M, Liu X, Xiong X, Sun Y. Inactivation of ribosomal protein S27-like confers radiosensitivity via the Mdm2-p53 and Mdm2-MRN-ATM axes. Cell Death Dis 2018; 9:145. [PMID: 29396424 PMCID: PMC5833388 DOI: 10.1038/s41419-017-0192-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 11/27/2017] [Accepted: 11/28/2017] [Indexed: 01/21/2023]
Abstract
RPS27L (ribosomal protein S27-like) is an evolutionarily conserved ribosomal protein and a direct p53 target. We recently reported that Rps27l disruption triggers ribosomal stress to induce p53, causing postnatal death, which can be rescued by Trp53+/−. Whether and how Rps27l modulates radiosensitivity is unknown. Here we report that Rps27l−/−; Trp53+/− mice are extremely sensitive to radiation due to reduced proliferation and massive induction of apoptosis in radiation-sensitive organs. Mechanistically, the radiation sensitivity is mediated by two signaling pathways: (1) activated p53 pathway due to imbalanced Mdm2/Mdm4 levels and reduced E3 ligase activity; and (2) reduced DNA damage response due to reduced MRN/Atm signal as a result of elevated Mdm2 binding of Nbs1 to inhibit Nbs1–Atm binding and subsequent Atm activation. Indeed, heterozygous deletion of Mdm2 restores the MRN/Atm signal. Collectively, our study revealed a physiological condition under which Rps27l regulates the Mdm2/p53 and MRN/Atm axes to maintain DNA damage response and to confer radioprotection in vivo.
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Affiliation(s)
- Yongchao Zhao
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China. .,Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA. .,Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
| | - Mingjia Tan
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Xia Liu
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiufang Xiong
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China. .,Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
| | - Yi Sun
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China. .,Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA. .,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China.
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23
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Kim JH, Grosbart M, Anand R, Wyman C, Cejka P, Petrini JHJ. The Mre11-Nbs1 Interface Is Essential for Viability and Tumor Suppression. Cell Rep 2017; 18:496-507. [PMID: 28076792 DOI: 10.1016/j.celrep.2016.12.035] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 11/04/2016] [Accepted: 12/12/2016] [Indexed: 02/02/2023] Open
Abstract
The Mre11 complex (Mre11, Rad50, and Nbs1) is integral to both DNA repair and ataxia telangiectasia mutated (ATM)-dependent DNA damage signaling. All three Mre11 complex components are essential for viability at the cellular and organismal levels. To delineate essential and non-essential Mre11 complex functions that are mediated by Nbs1, we used TALEN-based genome editing to derive Nbs1 mutant mice (Nbs1mid mice), which harbor mutations in the Mre11 interaction domain of Nbs1. Nbs1mid alleles that abolished interaction were incompatible with viability. Conversely, a 108-amino-acid Nbs1 fragment comprising the Mre11 interface was sufficient to rescue viability and ATM activation in cultured cells and support differentiation of hematopoietic cells in vivo. These data indicate that the essential role of Nbs1 is via its interaction with Mre11 and that most of the Nbs1 protein is dispensable for Mre11 complex functions and suggest that Mre11 and Rad50 directly activate ATM.
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Affiliation(s)
- Jun Hyun Kim
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10021, USA
| | - Malgorzata Grosbart
- Department of Molecular Genetics, Erasmus University Medical Center, 3000 Rotterdam, the Netherlands; Department of Radiation Oncology, Erasmus University Medical Center, 3000 Rotterdam, the Netherlands
| | - Roopesh Anand
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Via Vincenzo Vela 6, 6500 Bellinzona, Switzerland
| | - Claire Wyman
- Department of Molecular Genetics, Erasmus University Medical Center, 3000 Rotterdam, the Netherlands; Department of Radiation Oncology, Erasmus University Medical Center, 3000 Rotterdam, the Netherlands
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Via Vincenzo Vela 6, 6500 Bellinzona, Switzerland
| | - John H J Petrini
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10021, USA.
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24
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Saadatzadeh MR, Elmi AN, Pandya PH, Bijangi-Vishehsaraei K, Ding J, Stamatkin CW, Cohen-Gadol AA, Pollok KE. The Role of MDM2 in Promoting Genome Stability versus Instability. Int J Mol Sci 2017; 18:ijms18102216. [PMID: 29065514 PMCID: PMC5666895 DOI: 10.3390/ijms18102216] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/06/2017] [Accepted: 10/11/2017] [Indexed: 02/07/2023] Open
Abstract
In cancer, the mouse double minute 2 (MDM2) is an oncoprotein that contributes to the promotion of cell growth, survival, invasion, and therapeutic resistance. The impact of MDM2 on cell survival versus cell death is complex and dependent on levels of MDM2 isoforms, p53 status, and cellular context. Extensive investigations have demonstrated that MDM2 protein–protein interactions with p53 and other p53 family members (p63 and p73) block their ability to function as transcription factors that regulate cell growth and survival. Upon genotoxic insults, a dynamic and intricately regulated DNA damage response circuitry is activated leading to release of p53 from MDM2 and activation of cell cycle arrest. What ensues following DNA damage, depends on the extent of DNA damage and if the cell has sufficient DNA repair capacity. The well-known auto-regulatory loop between p53-MDM2 provides an additional layer of control as the cell either repairs DNA damage and survives (i.e., MDM2 re-engages with p53), or undergoes cell death (i.e., MDM2 does not re-engage p53). Furthermore, the decision to live or die is also influenced by chromatin-localized MDM2 which directly interacts with the Mre11-Rad50-Nbs1 complex and inhibits DNA damage-sensing giving rise to the potential for increased genome instability and cellular transformation.
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Affiliation(s)
- M Reza Saadatzadeh
- Department of Pediatrics (Division of Hematology/Oncology), Indianapolis, IN 46202, USA.
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
- Herman B. Wells Center for Pediatric Research, Indiana University Simon Cancer Center, 1044 West Walnut Street R4 302, Indianapolis, IN 46202-5525, USA.
| | - Adily N Elmi
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
| | - Pankita H Pandya
- Department of Pediatrics (Division of Hematology/Oncology), Indianapolis, IN 46202, USA.
| | | | - Jixin Ding
- Department of Pediatrics (Division of Hematology/Oncology), Indianapolis, IN 46202, USA.
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
- Herman B. Wells Center for Pediatric Research, Indiana University Simon Cancer Center, 1044 West Walnut Street R4 302, Indianapolis, IN 46202-5525, USA.
| | - Christopher W Stamatkin
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
- Herman B. Wells Center for Pediatric Research, Indiana University Simon Cancer Center, 1044 West Walnut Street R4 302, Indianapolis, IN 46202-5525, USA.
| | | | - Karen E Pollok
- Department of Pediatrics (Division of Hematology/Oncology), Indianapolis, IN 46202, USA.
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
- Herman B. Wells Center for Pediatric Research, Indiana University Simon Cancer Center, 1044 West Walnut Street R4 302, Indianapolis, IN 46202-5525, USA.
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25
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Wienken M, Moll UM, Dobbelstein M. Mdm2 as a chromatin modifier. J Mol Cell Biol 2017; 9:74-80. [PMID: 27927750 PMCID: PMC5439376 DOI: 10.1093/jmcb/mjw046] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Accepted: 10/30/2016] [Indexed: 12/21/2022] Open
Abstract
Mdm2 is the key negative regulator of the tumour suppressor p53, making it an attractive target for anti-cancer drug design. We recently identified a new role of Mdm2 in gene repression through its direct interaction with several proteins of the polycomb group (PcG) family. PcG proteins form polycomb repressive complexes PRC1 and PRC2. PRC2 (via EZH2) mediates histone 3 lysine 27 (H3K27) trimethylation, and PRC1 (via RING1B) mediates histone 2A lysine 119 (H2AK119) monoubiquitination. Both PRCs mostly support a compact and transcriptionally silent chromatin structure. We found that Mdm2 regulates a gene expression profile similar to that of PRC2 independent of p53. Moreover, Mdm2 promotes the stemness of murine induced pluripotent stem cells and human mesenchymal stem cells, and supports the survival of tumour cells. Mdm2 is recruited to target gene promoters by the PRC2 member and histone methyltransferase EZH2, and enhances PRC-dependent repressive chromatin modifications, specifically H3K27me3 and H2AK119ub1. Mdm2 also cooperates in gene repression with the PRC1 protein RING1B, a H2AK119 ubiquitin ligase. Here we discuss the possible implications of these p53-independent functions of Mdm2 in chromatin dynamics and in the stem cell phenotype. We propose that the p53-independent functions of Mdm2 should be taken into account for cancer drug design. So far, the majority of clinically tested Mdm2 inhibitors target its binding to p53 but do not affect the new functions of Mdm2 described here. However, when targeting the E3 ligase activity of Mdm2, a broader spectrum of its oncogenic activities might become druggable.
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Affiliation(s)
- Magdalena Wienken
- Institute of Molecular Oncology, Göttingen Center for Molecular Biosciences (GZMB), University Medical Center Göttingen, Göttingen 37077, Germany
| | - Ute M Moll
- Institute of Molecular Oncology, Göttingen Center for Molecular Biosciences (GZMB), University Medical Center Göttingen, Göttingen 37077, Germany.,Department of Pathology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Matthias Dobbelstein
- Institute of Molecular Oncology, Göttingen Center for Molecular Biosciences (GZMB), University Medical Center Göttingen, Göttingen 37077, Germany
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26
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Comiskey DF, Jacob AG, Sanford BL, Montes M, Goodwin AK, Steiner H, Matsa E, Tapia-Santos AS, Bebee TW, Grieves J, La Perle K, Boyaka P, Chandler DS. A novel mouse model of rhabdomyosarcoma underscores the dichotomy of MDM2-ALT1 function in vivo. Oncogene 2017; 37:95-106. [PMID: 28892044 PMCID: PMC5756115 DOI: 10.1038/onc.2017.282] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 05/29/2017] [Accepted: 06/19/2017] [Indexed: 12/18/2022]
Abstract
Alternative splicing of the oncogene murine double minute 2 (MDM2) is induced in response to genotoxic stress. MDM2-ALT1, the major splice variant generated, is known to activate the p53 pathway and impede full-length MDM2's negative regulation of p53. Despite this perceptible tumor-suppressive role, MDM2-ALT1 is also associated with several cancers. Furthermore, expression of MDM2-ALT1 has been observed in aggressive metastatic disease in pediatric rhabdomyosarcoma (RMS), irrespective of histological subtype. Therefore, we generated a transgenic MDM2-ALT1 mouse model that would allow us to investigate the effects of this splice variant on the progression of tumorigenesis. Here we show that when MDM2-ALT1 is ubiquitously expressed in p53 null mice it leads to increased incidence of spindle cell sarcomas, including RMS. Our data provide evidence that constitutive MDM2-ALT1 expression is itself an oncogenic lesion that aggravates the tumorigenesis induced by p53 loss. On the contrary, when MDM2-ALT1 is expressed solely in B-cells in the presence of homozygous wild-type p53 it leads to significantly increased lymphomagenesis (56%) when compared with control mice (27%). However, this phenotype is observable only at later stages in life (⩾18 months). Moreover, flow cytometric analyses for B-cell markers revealed an MDM2-ALT1-associated decrease in the B-cell population of the spleens of these animals. Our data suggest that the B-cell loss is p53 dependent and is a response mounted to persistent MDM2-ALT1 expression in a wild-type p53 background. Overall, our findings highlight the importance of an MDM2 splice variant as a critical modifier of both p53-dependent and -independent tumorigenesis, underscoring the complexity of MDM2 posttranscriptional regulation in cancer. Furthermore, MDM2-ALT1-expressing p53 null mice represent a novel mouse model of fusion-negative RMS.
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Affiliation(s)
- D F Comiskey
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.,Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - A G Jacob
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.,Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - B L Sanford
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - M Montes
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.,Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - A K Goodwin
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - H Steiner
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - E Matsa
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - A S Tapia-Santos
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.,Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - T W Bebee
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.,Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - J Grieves
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA.,Takeda California, Inc., Drug Safety Research & Evaluation 10410 Science Center Drive, San Diego, CA 92121, USA
| | - K La Perle
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - P Boyaka
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - D S Chandler
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.,Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA
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27
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Mdm2 selectively suppresses DNA damage arising from inhibition of topoisomerase II independent of p53. Oncogene 2017; 36:6085-6096. [PMID: 28692049 DOI: 10.1038/onc.2017.229] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 05/10/2017] [Accepted: 05/25/2017] [Indexed: 12/20/2022]
Abstract
Mdm2 is often overexpressed in tumors that retain wild-type TP53 but may affect therapeutic response independently of p53. Herein is shown that tumor cells with MDM2 amplification are selectively resistant to treatment with topoisomerase II poisons but not other DNA damaging agents. Tumor cells that overexpress Mdm2 have reduced DNA double-strand breaks in response to doxorubicin or etoposide. This latter result is not due to altered drug uptake. The selective attenuation of DNA damage in response to these agents is dependent on both Mdm2 levels and an intact ubiquitin ligase function. These findings reveal a novel, p53-independent activity of Mdm2 and have important implications for the choice of chemotherapeutic agents in the treatment of Mdm2-overexpressing tumors.
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28
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Feeley KP, Adams CM, Mitra R, Eischen CM. Mdm2 Is Required for Survival and Growth of p53-Deficient Cancer Cells. Cancer Res 2017; 77:3823-3833. [PMID: 28576884 DOI: 10.1158/0008-5472.can-17-0809] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/15/2017] [Accepted: 05/24/2017] [Indexed: 02/06/2023]
Abstract
p53 deletion prevents the embryonic lethality of normal tissues lacking Mdm2, suggesting that cells can survive without Mdm2 if p53 is also absent. Here we report evidence challenging this view, with implications for therapeutically targeting Mdm2. Deletion of Mdm2 in T-cell lymphomas or sarcomas lacking p53 induced apoptosis and G2 cell-cycle arrest, prolonging survival of mice with these tumors. p53-/- fibroblasts showed similar results, indicating that the effects of Mdm2 loss extend to premalignant cells. Mdm2 deletion in p53-/- cells upregulated p53 transcriptional target genes that induce apoptosis and cell-cycle arrest. Mdm2 deletion also increased levels of p73, a p53 family member. RNAi-mediated attenuation of p73 rescued the transcriptional and biological effects of Mdm2 loss, indicating that p73 mediates the consequences of Mdm2 deletion. In addition, Mdm2 deletion differed from blocking Mdm2 interaction with p53 family members, as Nutlin-3 induced G1 arrest but did not activate apoptosis in p53-/- sarcoma cells. Our results indicate that, in contrast to current dogma, Mdm2 expression is required for cell survival even in the absence of p53. Moreover, our results suggest that p73 compensates for loss of p53 and that targeting Mdm2 in p53-deficient cancers has therapeutic potential. Cancer Res; 77(14); 3823-33. ©2017 AACR.
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Affiliation(s)
- Kyle P Feeley
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Clare M Adams
- Department of Cancer Biology, Thomas Jefferson University, Sidney Kimmel Cancer Center, Philadelphia, Pennsylvania
| | - Ramkrishna Mitra
- Department of Cancer Biology, Thomas Jefferson University, Sidney Kimmel Cancer Center, Philadelphia, Pennsylvania
| | - Christine M Eischen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee. .,Department of Cancer Biology, Thomas Jefferson University, Sidney Kimmel Cancer Center, Philadelphia, Pennsylvania
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29
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Eischen CM. Role of Mdm2 and Mdmx in DNA repair. J Mol Cell Biol 2017; 9:69-73. [PMID: 27932484 PMCID: PMC5439402 DOI: 10.1093/jmcb/mjw052] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/07/2016] [Accepted: 12/02/2016] [Indexed: 11/21/2022] Open
Abstract
Mdm2 and Mdmx are critical regulators of the p53 tumour suppressor and are overexpressed in many human malignancies. However, in recent years, their impact on genome instability was shown to be at least, in part, independent of p53. Both Mdm2 and Mdmx inhibit DNA break repair through their association with the Mre11/Rad50/Nbs1 DNA repair complex. Recent evidence indicates that harnessing Mdm2 and/or Mdmx-mediated inhibition of DNA break repair in cancer cells could provide a therapeutic opportunity, particularly for those malignancies that have lost functional p53.
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Affiliation(s)
- Christine M. Eischen
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA19107, USA
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30
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Defective replication stress response inhibits lymphomagenesis and impairs lymphocyte reconstitution. Oncogene 2016; 36:2553-2564. [PMID: 27797382 PMCID: PMC5562353 DOI: 10.1038/onc.2016.408] [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: 06/03/2016] [Revised: 08/31/2016] [Accepted: 09/23/2016] [Indexed: 12/14/2022]
Abstract
DNA replication stress promotes genome instability in cancer. However, the contribution of the replication stress response to the development of malignancies remains unresolved. The DNA replication stress response protein SMARCAL1 stabilizes DNA replication forks and prevents replication fork collapse, a cause of DNA breaks and apoptosis. While the fork regression/remodeling functions of SMARCAL1 have been investigated, its in vivo functions in replication stress and cancer are unclear. Using a gamma radiation (IR)-induced replication stress T-cell lymphoma mouse model, we observed a significant inhibition of lymphomagenesis in mice lacking one or both alleles of Smarcal1. Notably, a quarter of the Smarcal1-deficient mice did not develop tumors. Moreover, hematopoietic stem/progenitor cells (HSPCs) and developing thymocytes in Smarcal1-deficient mice showed increased DNA damage and apoptosis during the proliferation burst following IR and an impaired ability to repopulate the thymus after IR. Additionally, mice lacking Smarcal1 showed significant HSPC defects when challenged to respond to other replication stress stimuli. Thus, our data reveal the critical function of the DNA replication stress response and specifically, Smarcal1 in hematopoietic cell survival and tumor development. Our results also provide important insight into the immunodeficiency observed in individuals with mutations in SMARCAL1 by suggesting that it is an HSPC defect.
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31
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Vogel KU, Bell LS, Galloway A, Ahlfors H, Turner M. The RNA-Binding Proteins Zfp36l1 and Zfp36l2 Enforce the Thymic β-Selection Checkpoint by Limiting DNA Damage Response Signaling and Cell Cycle Progression. THE JOURNAL OF IMMUNOLOGY 2016; 197:2673-2685. [PMID: 27566829 DOI: 10.4049/jimmunol.1600854] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/26/2016] [Indexed: 11/19/2022]
Abstract
The RNA-binding proteins Zfp36l1 and Zfp36l2 act redundantly to enforce the β-selection checkpoint during thymopoiesis, yet their molecular targets remain largely unknown. In this study, we identify these targets on a genome-wide scale in primary mouse thymocytes and show that Zfp36l1/l2 regulate DNA damage response and cell cycle transcripts to ensure proper β-selection. Double-negative 3 thymocytes lacking Zfp36l1/l2 share a gene expression profile with postselected double-negative 3b cells despite the absence of intracellular TCRβ and reduced IL-7 signaling. Our findings show that in addition to controlling the timing of proliferation at β-selection, posttranscriptional control by Zfp36l1/l2 limits DNA damage responses, which are known to promote thymocyte differentiation. Zfp36l1/l2 therefore act as posttranscriptional safeguards against chromosomal instability and replication stress by integrating pre-TCR and IL-7 signaling with DNA damage and cell cycle control.
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Affiliation(s)
| | - Lewis S Bell
- Dept. of Medicine, University of Cambridge, MRC-Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Alison Galloway
- Centre for Gene Regulation and Expression, School of Life Science, University of Dundee, Dundee DD1 5EH, UK
| | - Helena Ahlfors
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Martin Turner
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
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32
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Xu X, Xiong X, Sun Y. The role of ribosomal proteins in the regulation of cell proliferation, tumorigenesis, and genomic integrity. SCIENCE CHINA-LIFE SCIENCES 2016; 59:656-72. [DOI: 10.1007/s11427-016-0018-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 04/06/2016] [Indexed: 01/29/2023]
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Abstract
It is now clear that functional p53 is critical to protect the genome from alterations that lead to tumorigenesis. However, with the myriad of cellular stresses and pathways linked to p53 activation, much remains unknown about how p53 maintains genome stability and the proteins involved. The current understanding of the multiple ways p53 contributes to genome stability and how two of its negative regulators, Mdm2 and Mdmx, induce genome instability will be described.
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Affiliation(s)
- Christine M Eischen
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37212
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Wang H, Cai S, Bailey BJ, Reza Saadatzadeh M, Ding J, Tonsing-Carter E, Georgiadis TM, Zachary Gunter T, Long EC, Minto RE, Gordon KR, Sen SE, Cai W, Eitel JA, Waning DL, Bringman LR, Wells CD, Murray ME, Sarkaria JN, Gelbert LM, Jones DR, Cohen-Gadol AA, Mayo LD, Shannon HE, Pollok KE. Combination therapy in a xenograft model of glioblastoma: enhancement of the antitumor activity of temozolomide by an MDM2 antagonist. J Neurosurg 2016; 126:446-459. [PMID: 27177180 DOI: 10.3171/2016.1.jns152513] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Improvement in treatment outcome for patients with glioblastoma multiforme (GBM) requires a multifaceted approach due to dysregulation of numerous signaling pathways. The murine double minute 2 (MDM2) protein may fulfill this requirement because it is involved in the regulation of growth, survival, and invasion. The objective of this study was to investigate the impact of modulating MDM2 function in combination with front-line temozolomide (TMZ) therapy in GBM. METHODS The combination of TMZ with the MDM2 protein-protein interaction inhibitor nutlin3a was evaluated for effects on cell growth, p53 pathway activation, expression of DNA repair proteins, and invasive properties. In vivo efficacy was assessed in xenograft models of human GBM. RESULTS In combination, TMZ/nutlin3a was additive to synergistic in decreasing growth of wild-type p53 GBM cells. Pharmacodynamic studies demonstrated that inhibition of cell growth following exposure to TMZ/nutlin3a correlated with: 1) activation of the p53 pathway, 2) downregulation of DNA repair proteins, 3) persistence of DNA damage, and 4) decreased invasion. Pharmacokinetic studies indicated that nutlin3a was detected in human intracranial tumor xenografts. To assess therapeutic potential, efficacy studies were conducted in a xenograft model of intracranial GBM by using GBM cells derived from a recurrent wild-type p53 GBM that is highly TMZ resistant (GBM10). Three 5-day cycles of TMZ/nutlin3a resulted in a significant increase in the survival of mice with GBM10 intracranial tumors compared with single-agent therapy. CONCLUSIONS Modulation of MDM2/p53-associated signaling pathways is a novel approach for decreasing TMZ resistance in GBM. To the authors' knowledge, this is the first study in a humanized intracranial patient-derived xenograft model to demonstrate the efficacy of combining front-line TMZ therapy and an inhibitor of MDM2 protein-protein interactions.
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Affiliation(s)
- Haiyan Wang
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health
| | - Shanbao Cai
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health.,Anhui Provincial Cancer Hospital, Hefei, Anhui, China; and
| | - Barbara J Bailey
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health
| | - M Reza Saadatzadeh
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health.,Goodman Campbell Brain and Spine, Department of Neurosurgery
| | - Jixin Ding
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health.,Goodman Campbell Brain and Spine, Department of Neurosurgery
| | - Eva Tonsing-Carter
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health.,Indiana University Simon Cancer Center.,Department of Pharmacology and Toxicology
| | - Taxiarchis M Georgiadis
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis
| | - T Zachary Gunter
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis
| | - Eric C Long
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis
| | - Robert E Minto
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis
| | - Kevin R Gordon
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis
| | - Stephanie E Sen
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis
| | - Wenjing Cai
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health
| | - Jacob A Eitel
- Department of Radiology and Imaging Science, Indiana University, Indianapolis, Indiana
| | - David L Waning
- Indiana University Simon Cancer Center.,Department of Medicine, Division of Endocrinology
| | - Lauren R Bringman
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine
| | - Clark D Wells
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine
| | - Mary E Murray
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health
| | - Jann N Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Lawrence M Gelbert
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health
| | | | - Aaron A Cohen-Gadol
- Indiana University Simon Cancer Center.,Goodman Campbell Brain and Spine, Department of Neurosurgery
| | - Lindsey D Mayo
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health.,Indiana University Simon Cancer Center
| | - Harlan E Shannon
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health
| | - Karen E Pollok
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health.,Indiana University Simon Cancer Center.,Department of Pharmacology and Toxicology
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Ranjan A, Bera K, Iwakuma T. Murine double minute 2, a potential p53-independent regulator of liver cancer metastasis. HEPATOMA RESEARCH 2016; 2:114-121. [PMID: 28944296 PMCID: PMC5609474 DOI: 10.20517/2394-5079.2015.67] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hepatocellular carcinoma (HCC) has emerged as one of the most commonly diagnosed forms of human cancer; yet, the mechanisms underlying HCC progression remain unclear. Unlike other cancers, systematic chemotherapy is not effective for HCC patients, while surgical resection and liver transplantation are the most viable treatment options. Thus, identifying factors or pathways that suppress HCC progression would be crucial for advancing treatment strategies for HCC. The murine double minute 2 (MDM2)-p53 pathway is impaired in most of the cancer types, including HCC, and MDM2 is overexpressed in approximately 30% of HCC. Overexpression of MDM2 is reported to be well correlated with metastasis, drug resistance, and poor prognosis of multiple cancer types, including HCC. Importantly, these correlations are observed even when p53 is mutated. Indeed, p53-independent functions of overexpressed MDM2 in cancer progression have been suitably demonstrated. In this review article, we summarize potential effectors of MDM2 that promote or suppress cancer metastasis and discuss the p53-independent roles of MDM2 in liver cancer metastasis from clinical as well as biological perspectives.
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Affiliation(s)
- Atul Ranjan
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Kaustav Bera
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Tomoo Iwakuma
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
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Adams CM, Hiebert SW, Eischen CM. Myc Induces miRNA-Mediated Apoptosis in Response to HDAC Inhibition in Hematologic Malignancies. Cancer Res 2015; 76:736-48. [PMID: 26676759 DOI: 10.1158/0008-5472.can-15-1751] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/12/2015] [Indexed: 12/26/2022]
Abstract
Alterations in the expression or function of histone deacetylases (HDAC) contribute to the development and progression of hematologic malignancies. Consequently, the development and implementation of HDAC inhibitors has proven to be therapeutically beneficial, particularly for hematologic malignancies. However, the molecular mechanisms by which HDAC inhibition (HDACi) induces tumor cell death remain unresolved. Here, we investigated the effects of HDACi in Myc-driven B-cell lymphoma and five other hematopoietic malignancies. We determined that Myc-mediated transcriptional repression of the miR-15 and let-7 families in malignant cells was relieved upon HDACi, and Myc was required for their upregulation. The miR-15 and let-7 families then targeted and downregulated the antiapoptotic genes Bcl-2 and Bcl-xL, respectively, to induce HDACi-mediated apoptosis. Notably, Myc also transcriptionally upregulated these miRNA in untransformed cells, indicating that this Myc-induced miRNA-mediated apoptotic pathway is suppressed in malignant cells, but becomes reactivated upon HDACi. Taken together, our results reveal a previously unknown mechanism by which Myc induces apoptosis independent of the p53 pathway and as a response to HDACi in malignant hematopoietic cells.
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Affiliation(s)
- Clare M Adams
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Scott W Hiebert
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Christine M Eischen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee.
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Edmonds MD, Boyd KL, Moyo T, Mitra R, Duszynski R, Arrate MP, Chen X, Zhao Z, Blackwell TS, Andl T, Eischen CM. MicroRNA-31 initiates lung tumorigenesis and promotes mutant KRAS-driven lung cancer. J Clin Invest 2015; 126:349-64. [PMID: 26657862 DOI: 10.1172/jci82720] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 11/06/2015] [Indexed: 01/12/2023] Open
Abstract
MicroRNA (miR) are important regulators of gene expression, and aberrant miR expression has been linked to oncogenesis; however, little is understood about their contribution to lung tumorigenesis. Here, we determined that miR-31 is overexpressed in human lung adenocarcinoma and this overexpression independently correlates with decreased patient survival. We developed a transgenic mouse model that allows for lung-specific expression of miR-31 to test the oncogenic potential of miR-31 in the lung. Using this model, we observed that miR-31 induction results in lung hyperplasia, followed by adenoma formation and later adenocarcinoma development. Moreover, induced expression of miR-31 in mice cooperated with mutant KRAS to accelerate lung tumorigenesis. We determined that miR-31 regulates lung epithelial cell growth and identified 6 negative regulators of RAS/MAPK signaling as direct targets of miR-31. Our study distinguishes miR-31 as a driver of lung tumorigenesis that promotes mutant KRAS-mediated oncogenesis and reveals that miR-31 directly targets and reduces expression of negative regulators of RAS/MAPK signaling.
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Yu ZC, Huang YF, Shieh SY. Requirement for human Mps1/TTK in oxidative DNA damage repair and cell survival through MDM2 phosphorylation. Nucleic Acids Res 2015; 44:1133-50. [PMID: 26531827 PMCID: PMC4756815 DOI: 10.1093/nar/gkv1173] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/21/2015] [Indexed: 01/25/2023] Open
Abstract
Human Mps1 (hMps1) is a protein kinase essential for mitotic checkpoints and the DNA damage response. Here, we present new evidence that hMps1 also participates in the repair of oxidative DNA lesions and cell survival through the MDM2-H2B axis. In response to oxidative stress, hMps1 phosphorylates MDM2, which in turn promotes histone H2B ubiquitination and chromatin decompaction. These events facilitate oxidative DNA damage repair and ATR-CHK1, but not ATM-CHK2 signaling. Depletion of hMps1 or MDM2 compromised H2B ubiquitination, DNA repair and cell survival. The impairment could be rescued by re-expression of WT but not the phospho-deficient MDM2 mutant, supporting the involvement of hMps1-dependent MDM2 phosphorylation in the oxidative stress response. In line with these findings, localization of RPA and base excision repair proteins to damage foci also requires MDM2 and hMps1. Significantly, like MDM2, hMps1 is upregulated in human sarcoma, suggesting high hMps1 and MDM2 expression may be beneficial for tumors constantly challenged by an oxidative micro-environment. Our study therefore identified an hMps1-MDM2-H2B signaling axis that likely plays a relevant role in tumor progression.
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Affiliation(s)
- Zheng-Cheng Yu
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, No 1, Sec. 1, Jen-Ai Road, Taipei 100, Taiwan Institute of Biomedical Sciences, Academia Sinica, 128 Sec. 2, Academia Road, Taipei 115, Taiwan
| | - Yi-Fu Huang
- Institute of Biomedical Sciences, Academia Sinica, 128 Sec. 2, Academia Road, Taipei 115, Taiwan
| | - Sheau-Yann Shieh
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, No 1, Sec. 1, Jen-Ai Road, Taipei 100, Taiwan Institute of Biomedical Sciences, Academia Sinica, 128 Sec. 2, Academia Road, Taipei 115, Taiwan
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Tonsing-Carter E, Bailey BJ, Saadatzadeh MR, Ding J, Wang H, Sinn AL, Peterman KM, Spragins TK, Silver JM, Sprouse AA, Georgiadis TM, Gunter TZ, Long EC, Minto RE, Marchal CC, Batuello CN, Safa AR, Hanenberg H, Territo PR, Sandusky GE, Mayo LD, Eischen CM, Shannon HE, Pollok KE. Potentiation of Carboplatin-Mediated DNA Damage by the Mdm2 Modulator Nutlin-3a in a Humanized Orthotopic Breast-to-Lung Metastatic Model. Mol Cancer Ther 2015; 14:2850-63. [PMID: 26494859 DOI: 10.1158/1535-7163.mct-15-0237] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 09/30/2015] [Indexed: 12/31/2022]
Abstract
Triple-negative breast cancers (TNBC) are typically resistant to treatment, and strategies that build upon frontline therapy are needed. Targeting the murine double minute 2 (Mdm2) protein is an attractive approach, as Mdm2 levels are elevated in many therapy-refractive breast cancers. The Mdm2 protein-protein interaction inhibitor Nutlin-3a blocks the binding of Mdm2 to key signaling molecules such as p53 and p73α and can result in activation of cell death signaling pathways. In the present study, the therapeutic potential of carboplatin and Nutlin-3a to treat TNBC was investigated, as carboplatin is under evaluation in clinical trials for TNBC. In mutant p53 TMD231 TNBC cells, carboplatin and Nutlin-3a led to increased Mdm2 and was strongly synergistic in promoting cell death in vitro. Furthermore, sensitivity of TNBC cells to combination treatment was dependent on p73α. Following combination treatment, γH2AX increased and Mdm2 localized to a larger degree to chromatin compared with single-agent treatment, consistent with previous observations that Mdm2 binds to the Mre11/Rad50/Nbs1 complex associated with DNA and inhibits the DNA damage response. In vivo efficacy studies were conducted in the TMD231 orthotopic mammary fat pad model in NOD.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ (NSG) mice. Using an intermittent dosing schedule of combined carboplatin and Nutlin-3a, there was a significant reduction in primary tumor growth and lung metastases compared with vehicle and single-agent treatments. In addition, there was minimal toxicity to the bone marrow and normal tissues. These studies demonstrate that Mdm2 holds promise as a therapeutic target in combination with conventional therapy and may lead to new clinical therapies for TNBC.
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Affiliation(s)
- Eva Tonsing-Carter
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Barbara J Bailey
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana. Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - M Reza Saadatzadeh
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana. Goodman Campbell Brain and Spine, Department of Neurosurgery, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jixin Ding
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana. Goodman Campbell Brain and Spine, Department of Neurosurgery, Indiana University School of Medicine, Indianapolis, Indiana
| | - Haiyan Wang
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Anthony L Sinn
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana
| | - Kacie M Peterman
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana
| | - Tiaishia K Spragins
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jayne M Silver
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana
| | - Alyssa A Sprouse
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Taxiarchis M Georgiadis
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - T Zachary Gunter
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Eric C Long
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Robert E Minto
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Christophe C Marchal
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Christopher N Batuello
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ahmad R Safa
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Helmut Hanenberg
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana. Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana. Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, Düsseldorf, Germany
| | - Paul R Territo
- Indiana Institute for Biomedical Sciences Imaging, Department of Radiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - George E Sandusky
- Department of Pathology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Lindsey D Mayo
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana. Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Christine M Eischen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Harlan E Shannon
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Karen E Pollok
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana. In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana. Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana.
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Werner LR, Huang S, Francis DM, Armstrong EA, Ma F, Li C, Iyer G, Canon J, Harari PM. Small Molecule Inhibition of MDM2-p53 Interaction Augments Radiation Response in Human Tumors. Mol Cancer Ther 2015; 14:1994-2003. [PMID: 26162687 DOI: 10.1158/1535-7163.mct-14-1056-t] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 06/27/2015] [Indexed: 11/16/2022]
Abstract
MDM2-p53 interaction and downstream signaling affect cellular response to DNA damage. AMG 232 is a potent small molecule inhibitor that blocks the interaction of MDM2 and p53. We examined the capacity of AMG 232 to augment radiation response across a spectrum of human tumor cell lines and xenografts. AMG 232 effectively inhibited proliferation and enhanced radiosensitivity via inhibition of damage repair signaling. Combined AMG 232 and radiation treatment resulted in the accumulation of γH2AX-related DNA damage and induction of senescence with promotion of apoptotic and/or autophagic cell death. Several molecules involved in senescence, autophagy, and apoptosis were specifically modulated following the combined AMG 232/radiation treatment, including FoxM1, ULK-1, DRAM, and BAX. In vivo xenograft studies confirmed more potent antitumor and antiangiogenesis efficacy with combined AMG 232/radiation treatment than treatment with drug or radiation alone. Taken together, these data identify the capacity of AMG 232 to augment radiation response across a variety of tumor types harboring functional p53.
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Affiliation(s)
- Lauryn R Werner
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Shyhmin Huang
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - David M Francis
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Eric A Armstrong
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Fang Ma
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Chunrong Li
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Gopal Iyer
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Jude Canon
- Oncology Research Amgen, Inc., Thousand Oaks, California
| | - Paul M Harari
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
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Carrillo AM, Hicks M, Khabele D, Eischen CM. Pharmacologically Increasing Mdm2 Inhibits DNA Repair and Cooperates with Genotoxic Agents to Kill p53-Inactivated Ovarian Cancer Cells. Mol Cancer Res 2015; 13:1197-205. [PMID: 25964101 DOI: 10.1158/1541-7786.mcr-15-0089] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/02/2015] [Indexed: 11/16/2022]
Abstract
UNLABELLED The Mdm2 oncogene is a negative regulator of the p53 tumor suppressor and recently identified inhibitor of DNA break repair. Nutlin-3 is a small-molecule inhibitor of Mdm2-p53 interaction that can induce apoptosis in cancer cells through activation of p53. Although this is a promising therapy for those cancers with wild-type p53, half of all human cancers have inactivated p53. Here, we reveal that a previously unappreciated effect of Nutlin is inhibition of DNA break repair, stemming from its ability to increase Mdm2 protein levels. The Nutlin-induced increase in Mdm2 inhibited DNA double-strand break repair and prolonged DNA damage response signaling independent of p53. Mechanistically, this effect of Nutlin required Mdm2 and acted through Nbs1 of the Mre11-Rad50-Nbs1 DNA repair complex. In ovarian cancer cells, where >90% have inactivated p53, Nutlin combined with the genotoxic agents, cisplatin or etoposide, had a cooperative lethal effect resulting in increased DNA damage and apoptosis. Therefore, these data demonstrate an unexpected consequence of pharmacologically increasing Mdm2 levels that when used in combination with genotoxic agents induces synthetic lethality in ovarian cancer cells, and likely other malignant cell types, that have inactivated p53. IMPLICATIONS Data reveal a therapeutically beneficial effect of pharmacologically increasing Mdm2 levels combined with chemotherapeutic agents for malignancies that have lost functional p53.
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Affiliation(s)
- Alexia M Carrillo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Mellissa Hicks
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dineo Khabele
- Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Christine M Eischen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee.
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Davis WJ, Lehmann PZ, Li W. Nuclear PI3K signaling in cell growth and tumorigenesis. Front Cell Dev Biol 2015; 3:24. [PMID: 25918701 PMCID: PMC4394695 DOI: 10.3389/fcell.2015.00024] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 03/27/2015] [Indexed: 12/12/2022] Open
Abstract
The PI3K/Akt signaling pathway is a major driving force in a variety of cellular functions. Dysregulation of this pathway has been implicated in many human diseases including cancer. While the activity of the cytoplasmic PI3K/Akt pathway has been extensively studied, the functions of these molecules and their effector proteins within the nucleus are poorly understood. Harboring key cellular processes such as DNA replication and repair as well as nascent messenger RNA transcription, the nucleus provides a unique compartmental environment for protein–protein and protein–DNA/RNA interactions required for cell survival, growth, and proliferation. Here we summarize recent advances made toward elucidating the nuclear PI3K/Akt signaling cascade and its key components within the nucleus as they pertain to cell growth and tumorigenesis. This review covers the spatial and temporal localization of the major nuclear kinases having PI3K activities and the counteracting phosphatases as well as the role of nuclear PI3K/Akt signaling in mRNA processing and exportation, DNA replication and repair, ribosome biogenesis, cell survival, and tumorigenesis.
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Affiliation(s)
- William J Davis
- College of Medical Sciences, Washington State University Spokane, WA, USA
| | - Peter Z Lehmann
- College of Medical Sciences, Washington State University Spokane, WA, USA
| | - Weimin Li
- College of Medical Sciences, Washington State University Spokane, WA, USA
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Homologous Recombination Repair Polymorphisms and the Risk for Osteosarcoma. J Med Biochem 2015; 34:200-206. [PMID: 28356832 PMCID: PMC4922323 DOI: 10.2478/jomb-2014-0031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 01/07/2014] [Indexed: 11/20/2022] Open
Abstract
Background DNA repair mechanisms are essential for maintaining genome stability, and genetic variability in DNA repair genes may contribute to cancer susceptibility. Our aim was to evaluate the influence of polymorphisms in the homologous recombination repair genes XRCC3, RAD51, and NBN on the risk for osteosarcoma. Methods In total, 79 osteosarcoma cases and 373 controls were genotyped for eight single nucleotide polymorphisms (SNPs) in XRCC3, RAD51, and NBN. Logistic regression was used to determine the association of these SNPs with risk for osteosarcoma. Results None of the investigated SNPs was associated with risk for osteosarcoma in the whole cohort of patients, however, in patients diagnosed before the age of thirty years XRCC3 rs861539 C>T and NBN rs1805794 G>C were associated with significantly decreased risk for osteosarcoma (P=0.047, OR=0.54, 95% CI=0.30–0.99 and P=0.036, OR=0.42, 95% CI=0.19–0.94, respectively). Moreover, in the carriers of a combination of polymorphic alleles in both SNPs risk for osteosarcoma was decreased even more significantly (Ptrend=0.007). The risk for developing osteosarcoma was the lowest in patients with no wild-type alleles for both SNPs (P=0.039, OR=0.31, 95% CI=0.10–0.94). Conclusions Our results suggest that polymorphisms in homologous recombination repair genes might contribute to risk for osteosarcoma in patients diagnosed below the age of thirty years.
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Kim TH, Leslie P, Zhang Y. Ribosomal proteins as unrevealed caretakers for cellular stress and genomic instability. Oncotarget 2015; 5:860-71. [PMID: 24658219 PMCID: PMC4011588 DOI: 10.18632/oncotarget.1784] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Ribosomal proteins (RPs) have gained much attention for their extraribosomal functions particularly with respect to p53 regulation. To date, about fourteen RPs have shown to bind to MDM2 and regulate p53. Upon binding to MDM2, the RPs suppress MDM2 E3 ubiquitin ligase activity resulting in the stabilization and activation of p53. Of the RPs that bind to MDM2, RPL5 and RPL11 are the most studied and RPL11 appears to have the most significant role in p53 regulation. Considering that more than 17% of RP species have been shown to interact with MDM2, one of the questions remains unresolved is why so many RPs bind MDM2 and modulate p53. Genes encoding RPs are widely dispersed on different chromosomes in both mice and humans. As components of ribosome, RP expression is tightly regulated to meet the appropriate stoichiometric ratio between RPs and rRNAs. Once genomic instability (e.g. aneuploidy) occurs, transcriptional and translational changes due to change of DNA copy number can result in an imbalance in the expression of RPs including those that bind to MDM2. Such an imbalance in RP expression could lead to failure to assemble functional ribosomes resulting in ribosomal stress. We propose that RPs have evolved ability to regulate MDM2 in response to genomic instability as an additional layer of p53 regulation. Full understanding of the biological roles of RPs could potentially establish RPs as a novel class of therapeutic targets in human diseases such as cancer.
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Affiliation(s)
- Tae-Hyung Kim
- Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC, USA
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45
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Carrillo AM, Bouska A, Arrate MP, Eischen CM. Mdmx promotes genomic instability independent of p53 and Mdm2. Oncogene 2015; 34:846-56. [PMID: 24608433 PMCID: PMC4160436 DOI: 10.1038/onc.2014.27] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 12/02/2013] [Accepted: 12/18/2013] [Indexed: 12/26/2022]
Abstract
The oncogene Mdmx is overexpressed in many human malignancies, and together with Mdm2, negatively regulates the p53 tumor suppressor. However, a p53-independent function of Mdmx that impacts genome stability has been described, but this function is not well understood. In the present study, we determined that of the 13 different cancer types evaluated, 6-90% of those that had elevated levels of Mdmx had concurrent inactivation (mutated or deleted) of p53. We show elevated levels of Mdmx-inhibited double-strand DNA break repair and induced chromosome and chromatid breaks independent of p53, leading to genome instability. Mdmx impaired early DNA damage-response signaling, such as phosphorylation of the serine/threonine-glutamine motif, mediated by the ATM kinase. Moreover, we identified Mdmx associated with Nbs1 of the Mre11-Rad50-Nbs1 (MRN) DNA repair complex, and this association increased upon DNA damage and was detected at chromatin. Elevated Mdmx levels also increased cellular transformation in a p53-independent manner. Unexpectedly, all Mdmx-mediated phenotypes also occurred in cells lacking Mdm2 and were independent of the Mdm2-binding domain (RING) of Mdmx. Therefore, Mdmx-mediated inhibition of the DNA damage response resulted in delayed DNA repair and increased genome instability and transformation independent of p53 and Mdm2. Our results reveal a novel p53- and Mdm2-independent oncogenic function of Mdmx that provides new insight into the many cancers that overexpress Mdmx.
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Affiliation(s)
- Alexia M. Carrillo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Alyssa Bouska
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE
| | - Maria Pia Arrate
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Christine M. Eischen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
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Grieb BC, Gramling MW, Arrate MP, Chen X, Beauparlant SL, Haines DS, Xiao H, Eischen CM. Oncogenic protein MTBP interacts with MYC to promote tumorigenesis. Cancer Res 2014; 74:3591-602. [PMID: 24786788 DOI: 10.1158/0008-5472.can-13-2149] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Despite its involvement in most human cancers, MYC continues to pose a challenge as a readily tractable therapeutic target. Here we identify the MYC transcriptional cofactors TIP48 and TIP49 and MYC as novel binding partners of Mdm2-binding protein (MTBP), a functionally undefined protein that we show is oncogenic and overexpressed in many human cancers. MTBP associated with MYC at promoters and increased MYC-mediated transcription, proliferation, neoplastic transformation, and tumor development. In breast cancer specimens, we determined overexpression of both MYC and MTBP was associated with a reduction in 10-year patient survival compared with MYC overexpression alone. MTBP was also frequently co-amplified with MYC in many human cancers. Mechanistic investigations implicated associations with TIP48/TIP49 as well as MYC in MTBP function in cellular transformation and the growth of human breast cancer cells. Taken together, our findings show MTBP functions with MYC to promote malignancy, identifying this protein as a novel general therapeutic target in human cancer.
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Affiliation(s)
- Brian C Grieb
- Authors' Affiliations: Departments of Pathology, Microbiology and Immunology and
| | - Mark W Gramling
- Authors' Affiliations: Departments of Pathology, Microbiology and Immunology and
| | - Maria Pia Arrate
- Authors' Affiliations: Departments of Pathology, Microbiology and Immunology and
| | - Xi Chen
- Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Stephen L Beauparlant
- Department of Biochemistry, Temple University; Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania; and
| | - Dale S Haines
- Department of Biochemistry, Temple University; Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania; and
| | - Hua Xiao
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Christine M Eischen
- Authors' Affiliations: Departments of Pathology, Microbiology and Immunology and
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47
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Eischen CM, Lozano G. The Mdm network and its regulation of p53 activities: a rheostat of cancer risk. Hum Mutat 2014; 35:728-37. [PMID: 24488925 DOI: 10.1002/humu.22524] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 01/31/2014] [Indexed: 11/07/2022]
Abstract
The potent transcriptional activity of p53 (Trp53, TP53) must be kept in check for normal cell growth and survival. Tumors, which drastically deviate from these parameters, have evolved multiple mechanisms to inactivate TP53, the most prevalent of which is the emergence of TP53 missense mutations, some of which have gain-of-function activities. Another important mechanism by which tumors bypass TP53 functions is via increased levels of two TP53 inhibitors, MDM2, and MDM4. Studies in humans and in mice reveal the complexity of TP53 regulation and the exquisite sensitivity of this pathway to small changes in regulation. Here, we summarize the factors that impinge on TP53 activity and thus cell death/arrest or tumor development.
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Affiliation(s)
- Christine M Eischen
- Vanderbilt University Medical Center, Department of Pathology, Microbiology and Immunology, Nashville, Tennessee
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48
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Wang Y, Hong Y, Li M, Long J, Zhao YP, Zhang JX, Li Q, You H, Tong WM, Jia JD, Huang J. Mutation inactivation of Nijmegen breakage syndrome gene (NBS1) in hepatocellular carcinoma and intrahepatic cholangiocarcinoma. PLoS One 2013; 8:e82426. [PMID: 24349281 PMCID: PMC3862623 DOI: 10.1371/journal.pone.0082426] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 11/04/2013] [Indexed: 11/25/2022] Open
Abstract
Nijmegen breakage syndrome (NBS) with NBS1 germ-line mutation is a human autosomal recessive disease characterized by genomic instability and enhanced cancer predisposition. The NBS1 gene codes for a protein, Nbs1(p95/Nibrin), involved in the processing/repair of DNA double-strand breaks. Hepatocellular carcinoma (HCC) is a complex and heterogeneous tumor with several genomic alterations. Recent studies have shown that heterozygous NBS1 mice exhibited a higher incidence of HCC than did wild-type mice. The objective of the present study is to assess whether NBS1 mutations play a role in the pathogenesis of human primary liver cancer, including HBV-associated HCC and intrahepatic cholangiocarcinoma (ICC). Eight missense NBS1 mutations were identified in six of 64 (9.4%) HCCs and two of 18 (11.1%) ICCs, whereas only one synonymous mutation was found in 89 control cases of cirrhosis and chronic hepatitis B. Analysis of the functional consequences of the identified NBS1 mutations in Mre11-binding domain showed loss of nuclear localization of Nbs1 partner Mre11, one of the hallmarks for Nbs1 deficiency, in one HCC and two ICCs with NBS1 mutations. Moreover, seven of the eight tumors with NBS1 mutations had at least one genetic alteration in the TP53 pathway, including TP53 mutation, MDM2 amplification, p14ARF homozygous deletion and promoter methylation, implying a synergistic effect of Nbs1 disruption and p53 inactivation. Our findings provide novel insight on the molecular pathogenesis of primary liver cancer characterized by mutation inactivation of NBS1, a DNA repair associated gene.
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Affiliation(s)
- Yan Wang
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Yu Hong
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Man Li
- Department of Pathology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Jiang Long
- Minimally Invasive Hepatobiliary Cancer Center, Beijing You-An Hospital, Capital Medical University, Beijing, China
| | - Yan-Ping Zhao
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Jun-Xia Zhang
- Department of Hepatology, Tianjin Infectious Disease Specialty Hospital, Tianjin, China
| | - Qian Li
- Department of Preventive Medicine, Mt. Sinai School of Medicine, New York, New York, United States of America
| | - Hong You
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Wei-Min Tong
- Department of Pathology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Ji-Dong Jia
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Jian Huang
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
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49
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Okoro DR, Arva N, Gao C, Polotskaia A, Puente C, Rosso M, Bargonetti J. Endogenous human MDM2-C is highly expressed in human cancers and functions as a p53-independent growth activator. PLoS One 2013; 8:e77643. [PMID: 24147044 PMCID: PMC3795673 DOI: 10.1371/journal.pone.0077643] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 09/12/2013] [Indexed: 01/22/2023] Open
Abstract
Human cancers over-expressing mdm2, through a T to G variation at a single nucleotide polymorphism at position 309 (mdm2 SNP309), have functionally inactivated p53 that is not effectively degraded. They also have high expression of the alternatively spliced transcript, mdm2-C. Alternatively spliced mdm2 transcripts are expressed in many forms of human cancer and when they are exogenously expressed they transform human cells. However no study to date has detected endogenous MDM2 protein isoforms. Studies with exogenous expression of splice variants have been carried out with mdm2-A and mdm2-B, but the mdm2-C isoform has remained virtually unexplored. We addressed the cellular influence of exogenously expressed MDM2-C, and asked if endogenous MDM2-C protein was present in human cancers. To detect endogenous MDM2-C protein, we created a human MDM2-C antibody to the splice junction epitope of exons four and ten (MDM2 C410) and validated the antibody with in vitro translated full length MDM2 compared to MDM2-C. Interestingly, we discovered that MDM2-C co-migrates with MDM2-FL at approximately 98 kDa. Using the validated C410 antibody, we detected high expression of endogenous MDM2-C in human cancer cell lines and human cancer tissues. In the estrogen receptor positive (ER+) mdm2 G/G SNP309 breast cancer cell line, T47D, we observed an increase in endogenous MDM2-C protein with estrogen treatment. MDM2-C localized to the nucleus and the cytoplasm. We examined the biological activity of MDM2-C by exogenously expressing the protein and observed that MDM2-C did not efficiently target p53 for degradation or reduce p53 transcriptional activity. Exogenous expression of MDM2-C in p53-null human cancer cells increased colony formation, indicating p53-independent tumorigenic properties. Our data indicate a role for MDM2-C that does not require the inhibition of p53 for increasing cancer cell proliferation and survival.
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Affiliation(s)
- Danielle R. Okoro
- Department of Biological Sciences Hunter College and The Graduate Center Departments of Biology and Biochemistry, City University of New York, New York City, United States of America
| | - Nicoleta Arva
- Department of Biological Sciences Hunter College and The Graduate Center Departments of Biology and Biochemistry, City University of New York, New York City, United States of America
| | - Chong Gao
- Department of Biological Sciences Hunter College and The Graduate Center Departments of Biology and Biochemistry, City University of New York, New York City, United States of America
| | - Alla Polotskaia
- Department of Biological Sciences Hunter College and The Graduate Center Departments of Biology and Biochemistry, City University of New York, New York City, United States of America
| | - Cindy Puente
- Department of Biological Sciences Hunter College and The Graduate Center Departments of Biology and Biochemistry, City University of New York, New York City, United States of America
| | - Melissa Rosso
- Department of Biological Sciences Hunter College and The Graduate Center Departments of Biology and Biochemistry, City University of New York, New York City, United States of America
| | - Jill Bargonetti
- Department of Biological Sciences Hunter College and The Graduate Center Departments of Biology and Biochemistry, City University of New York, New York City, United States of America
- * E-mail:
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50
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Fåhraeus R, Olivares-Illana V. MDM2's social network. Oncogene 2013; 33:4365-76. [PMID: 24096477 DOI: 10.1038/onc.2013.410] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/17/2013] [Accepted: 08/17/2013] [Indexed: 12/22/2022]
Abstract
MDM2 is considered a hub protein due to its capacity to interact with a large number of different partners of which p53 is most well described. MDM2 is an E3 ubiquitin ligase, and many, but not all, of its interactions relate directly to this activity, such as substrates, adaptors or bridges, promoters, inhibitors or complementary factors. Some interactions serve regulatory functions that in response to cellular stresses control the localisation and functions of MDM2 including protein kinases, ribosomal proteins and proteases. Moreover, interactions with nucleotides serve other functions such as mRNA to regulate protein synthesis and DNA to control transcription. To perform such a pleiotropic panorama of different functions, MDM2 is subjected to a multitude of post-translational modifications and is expressed in different isoforms. The large and diverse interactome is made possible due to the plasticity of MDM2 and in this review we have listed the MDM2 interactions until now and we will discuss how this multifaceted protein can interact with such a variety of substrates to provide a key intermediary role in different signalling pathways.
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Affiliation(s)
- R Fåhraeus
- Cibles Therapeutiques, Equipe Labellisée Ligue Contre le Cancer, INSERM Unité 940, Institut de Génétique Moléculaire, Université Paris 7, Hôpital St Louis, 27 rue Juliette Dodu, Paris, France
| | - V Olivares-Illana
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava, Zona Universitaria, San Luis Potosí, México
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