51
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Essential Roles of E3 Ubiquitin Ligases in p53 Regulation. Int J Mol Sci 2017; 18:ijms18020442. [PMID: 28218667 PMCID: PMC5343976 DOI: 10.3390/ijms18020442] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 02/10/2017] [Accepted: 02/11/2017] [Indexed: 01/30/2023] Open
Abstract
The ubiquitination pathway and proteasomal degradation machinery dominantly regulate p53 tumor suppressor protein stability, localization, and functions in both normal and cancerous cells. Selective E3 ubiquitin ligases dominantly regulate protein levels and activities of p53 in a large range of physiological conditions and in response to cellular changes induced by exogenous and endogenous stresses. The regulation of p53’s functions by E3 ubiquitin ligases is a complex process that can lead to positive or negative regulation of p53 protein in a context- and cell type-dependent manner. Accessory proteins bind and modulate E3 ubiquitin ligases, adding yet another layer of regulatory control for p53 and its downstream functions. This review provides a comprehensive understanding of p53 regulation by selective E3 ubiquitin ligases and their potential to be considered as a new class of biomarkers and therapeutic targets in diverse types of cancers.
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Sarkar A, Iwasa H, Hossain S, Xu X, Sawada T, Shimizu T, Maruyama J, Arimoto-Matsuzaki K, Hata Y. Domain analysis of Ras-association domain family member 6 upon interaction with MDM2. FEBS Lett 2017; 591:260-272. [DOI: 10.1002/1873-3468.12551] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 12/08/2016] [Accepted: 12/28/2016] [Indexed: 01/02/2023]
Affiliation(s)
- Aradhan Sarkar
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
| | - Hiroaki Iwasa
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
| | - Shakhawoat Hossain
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
- Department of Biochemistry and Molecular Biology; University of Rajshahi; Bangladesh
| | - Xiaoyin Xu
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
- Department of Breast Oncology Surgery; The Second Affiliated Hospital of Wenzhou Medical University; China
| | - Takeru Sawada
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
| | - Takanobu Shimizu
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
| | - Junichi Maruyama
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
| | - Kyoko Arimoto-Matsuzaki
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
| | - Yutaka Hata
- Department of Medical Biochemistry; Graduate School of Medical and Dental Sciences; Tokyo Medical and Dental University; Japan
- Center for Brain Integration Research; Tokyo Medical and Dental University; Japan
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53
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Laptenko O, Tong DR, Manfredi J, Prives C. The Tail That Wags the Dog: How the Disordered C-Terminal Domain Controls the Transcriptional Activities of the p53 Tumor-Suppressor Protein. Trends Biochem Sci 2016; 41:1022-1034. [PMID: 27669647 DOI: 10.1016/j.tibs.2016.08.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/19/2016] [Accepted: 08/22/2016] [Indexed: 01/22/2023]
Abstract
The p53 tumor suppressor is a transcription factor (TF) that exerts antitumor functions through its ability to regulate the expression of multiple genes. Within the p53 protein resides a relatively short unstructured C-terminal domain (CTD) that remarkably participates in virtually every aspect of p53 performance as a TF. Because these aspects are often interdependent and it is not always possible to dissect them experimentally, there has been a great deal of controversy about the CTD. In this review we evaluate the significance and key features of this interesting region of p53 and its impact on the many aspects of p53 function in light of previous and more recent findings.
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Affiliation(s)
- Oleg Laptenko
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - David R Tong
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - James Manfredi
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Carol Prives
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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54
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Abstract
It is poorly understood how a single protein, p53, can be responsive to so many stress signals and orchestrates very diverse cell responses to maintain/restore cell/tissue functions. The uncovering that TP53 gene physiologically expresses, in a tissue-dependent manner, several p53 splice variants (isoforms) provides an explanation to its pleiotropic biological activities. Here, we summarize a decade of research on p53 isoforms. The clinical studies and the diverse cellular and animal models of p53 isoforms (zebrafish, Drosophila, and mouse) lead us to realize that a p53-mediated cell response is, in fact, the sum of the intrinsic activities of the coexpressed p53 isoforms and that unbalancing expression of different p53 isoforms leads to cancer, premature aging, (neuro)degenerative diseases, inflammation, embryo malformations, or defects in tissue regeneration. Cracking the p53 isoforms' code is, thus, a necessary step to improve cancer treatment. It also opens new exciting perspectives in tissue regeneration.
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Affiliation(s)
- Sebastien M Joruiz
- Dundee Cancer Centre, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, United Kingdom
| | - Jean-Christophe Bourdon
- Dundee Cancer Centre, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, United Kingdom
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55
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Allosteric Interactions by p53 mRNA Govern HDM2 E3 Ubiquitin Ligase Specificity under Different Conditions. Mol Cell Biol 2016; 36:2195-205. [PMID: 27215386 DOI: 10.1128/mcb.00113-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/20/2016] [Indexed: 11/20/2022] Open
Abstract
HDM2 and HDMX are key negative regulatory factors of the p53 tumor suppressor under normal conditions by promoting its degradation or preventing its trans activity, respectively. It has more recently been shown that both proteins can also act as positive regulators of p53 after DNA damage. This involves phosphorylation by ATM on serine residues HDM2(S395) and HDMX(S403), promoting their respective interaction with the p53 mRNA. However, the underlying molecular mechanisms of how these phosphorylation events switch HDM2 and HDMX from negative to positive regulators of p53 is not known. Our results show that these phosphorylation events reside within intrinsically disordered domains and change the conformation of the proteins. The modifications promote the exposition of N-terminal interfaces that support the formation of a new HDMX-HDM2 heterodimer independent of the C-terminal RING-RING interaction. The E3 ubiquitin ligase activity of this complex toward p53 is prevented by the p53 mRNA ligand but, interestingly, does not affect the capacity to ubiquitinate HDMX and HDM2. These results show how ATM-mediated modifications of HDMX and HDM2 switch HDM2 E3 ubiquitin ligase activity away from p53 but toward HDMX and itself and illustrate how the substrate specificity of HDM2 E3 ligase activity is regulated.
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56
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Wei SJ, Chee S, Yurlova L, Lane D, Verma C, Brown C, Ghadessy F. Avoiding drug resistance through extended drug target interfaces: a case for stapled peptides. Oncotarget 2016; 7:32232-46. [PMID: 27057630 PMCID: PMC5078010 DOI: 10.18632/oncotarget.8572] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 03/18/2016] [Indexed: 11/25/2022] Open
Abstract
Cancer drugs often fail due to the emergence of clinical resistance. This can manifest through mutations in target proteins that selectively exclude drug binding whilst retaining aberrant function. A priori knowledge of resistance-inducing mutations is therefore important for both drug design and clinical surveillance. Stapled peptides represent a novel class of antagonists capable of inhibiting therapeutically relevant protein-protein interactions. Here, we address the important question of potential resistance to stapled peptide inhibitors. HDM2 is the critical negative regulator of p53, and is often overexpressed in cancers that retain wild-type p53 function. Interrogation of a large collection of randomly mutated HDM2 proteins failed to identify point mutations that could selectively abrogate binding by a stapled peptide inhibitor (PM2). In contrast, the same interrogation methodology has previously uncovered point mutations that selectively inhibit binding by Nutlin, the prototypical small molecule inhibitor of HDM2. Our results demonstrate both the high level of structural p53 mimicry employed by PM2 to engage HDM2, and the potential resilience of stapled peptide antagonists to mutations in target proteins. This inherent feature could reduce clinical resistance should this class of drugs enter the clinic.
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Affiliation(s)
- Siau Jia Wei
- P53 Laboratory (A*STAR), #06-04/05 Neuros, 138648, Singapore
| | - Sharon Chee
- P53 Laboratory (A*STAR), #06-04/05 Neuros, 138648, Singapore
| | | | - David Lane
- P53 Laboratory (A*STAR), #06-04/05 Neuros, 138648, Singapore
| | - Chandra Verma
- Bioinformatics Institute (A*STAR), 07-01 Matrix, 138671, Singapore
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore
- Department of Biological Sciences, National University of Singapore, 117543, Singapore
| | | | - Farid Ghadessy
- P53 Laboratory (A*STAR), #06-04/05 Neuros, 138648, Singapore
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57
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Laptenko O, Shiff I, Freed-Pastor W, Zupnick A, Mattia M, Freulich E, Shamir I, Kadouri N, Kahan T, Manfredi J, Simon I, Prives C. The p53 C terminus controls site-specific DNA binding and promotes structural changes within the central DNA binding domain. Mol Cell 2016; 57:1034-1046. [PMID: 25794615 DOI: 10.1016/j.molcel.2015.02.015] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/23/2014] [Accepted: 02/06/2015] [Indexed: 11/19/2022]
Abstract
DNA binding by numerous transcription factors including the p53 tumor suppressor protein constitutes a vital early step in transcriptional activation. While the role of the central core DNA binding domain (DBD) of p53 in site-specific DNA binding has been established, the contribution of the sequence-independent C-terminal domain (CTD) is still not well understood. We investigated the DNA-binding properties of a series of p53 CTD variants using a combination of in vitro biochemical analyses and in vivo binding experiments. Our results provide several unanticipated and interconnected findings. First, the CTD enables DNA binding in a sequence-dependent manner that is drastically altered by either its modification or deletion. Second, dependence on the CTD correlates with the extent to which the p53 binding site deviates from the canonical consensus sequence. Third, the CTD enables stable formation of p53-DNA complexes to divergent binding sites via DNA-induced conformational changes within the DBD itself.
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Affiliation(s)
- Oleg Laptenko
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Idit Shiff
- Department of Microbiology and Molecular Genetics, Hebrew University Medical School, IMRIC, Jerusalem 91120, Israel
| | - Will Freed-Pastor
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Andrew Zupnick
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Melissa Mattia
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Ella Freulich
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Inbal Shamir
- Department of Microbiology and Molecular Genetics, Hebrew University Medical School, IMRIC, Jerusalem 91120, Israel
| | - Noam Kadouri
- Department of Microbiology and Molecular Genetics, Hebrew University Medical School, IMRIC, Jerusalem 91120, Israel
| | - Tamar Kahan
- Department of Microbiology and Molecular Genetics, Hebrew University Medical School, IMRIC, Jerusalem 91120, Israel
| | - James Manfredi
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY 10029, USA
| | - Itamar Simon
- Department of Microbiology and Molecular Genetics, Hebrew University Medical School, IMRIC, Jerusalem 91120, Israel.
| | - Carol Prives
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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58
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Karni-Schmidt O, Lokshin M, Prives C. The Roles of MDM2 and MDMX in Cancer. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2016; 11:617-44. [PMID: 27022975 DOI: 10.1146/annurev-pathol-012414-040349] [Citation(s) in RCA: 200] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
For more than 25 years, MDM2 and its homolog MDMX (also known as MDM4) have been shown to exert oncogenic activity. These two proteins are best understood as negative regulators of the p53 tumor suppressor, although they may have additional p53-independent roles. Understanding the dysregulation of MDM2 and MDMX in human cancers and how they function either together or separately in tumorigenesis may improve methods of diagnosis and for assessing prognosis. Targeting the proteins themselves, or their regulators, may be a promising therapeutic approach to treating some forms of cancer.
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Affiliation(s)
- Orit Karni-Schmidt
- Department of Biological Sciences, Columbia University, New York, NY 10027;
| | - Maria Lokshin
- Department of Biological Sciences, Columbia University, New York, NY 10027;
| | - Carol Prives
- Department of Biological Sciences, Columbia University, New York, NY 10027;
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59
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Zhuo X, Ye H, Li Q, Xiang Z, Zhang X. Is MDM2 SNP309 Variation a Risk Factor for Head and Neck Carcinoma?: An Updated Meta-Analysis Based on 11,552 Individuals. Medicine (Baltimore) 2016; 95:e2948. [PMID: 26945408 PMCID: PMC4782892 DOI: 10.1097/md.0000000000002948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Murine double minute-2 (MDM2) is a negative regulator of P53, and its T309G polymorphism has been suggested as a risk factor for a variety of cancers. Increasing evidence has shown the association of MDM2 T309G polymorphism with head and neck carcinoma (HNC) risk. However, the results are inconsistent. Thus, we performed a meta-analysis to elucidate the association. The meta-analysis retrieved studies published up to August 2015, and essential information was extracted for analysis. Separate analyses on ethnicity, source of controls, sample size, detection method, and cancer types were also conducted. Odds ratios (ORs) and their 95% confidence intervals (CIs) were used to estimate the association. Pooled data from 16 case-control studies including 4625 cases and 6927 controls failed to indicate a significant association. However, in the subgroup analysis of sample sizes, an increased risk was observed in the largest sample size group (>1000) under a recessive model (OR = 1.52; 95% CI = 1.08-2.13). Increased risks were also found in the nasopharyngeal cancer in the subgroup analysis of cancer types (GG vs TT: OR = 2.07; 95% CI = 1.38-3.12; dominant model: OR = 1.48; 95% CI = 1.13-1.93; recessive model: OR = 1.76; 95% CI = 1.17-2.65). The results suggest that homozygote GG alleles of MDM2 SNP309 may be a low-penetrant risk factor for HNC, and G allele may confer nasopharyngeal cancer susceptibility.
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Affiliation(s)
- Xianlu Zhuo
- From the Department of Otolaryngology, Southwest Hospital, Third Military Medical University, Chongqing (XZ, QL, ZX, XZ); and Affiliated Hospital of Guiyang Medical University, Guiyang, China (XZ, HY)
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60
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Nim S, Jeon J, Corbi-Verge C, Seo MH, Ivarsson Y, Moffat J, Tarasova N, Kim PM. Pooled screening for antiproliferative inhibitors of protein-protein interactions. Nat Chem Biol 2016; 12:275-81. [PMID: 26900867 PMCID: PMC5756068 DOI: 10.1038/nchembio.2026] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 01/04/2016] [Indexed: 11/30/2022]
Abstract
Protein-protein interactions (PPIs) are emerging as a promising new class of drug targets. Here, we present a novel high-throughput approach to screen inhibitors of PPIs in cells. We designed a library of 50,000 human peptide binding motifs and used a pooled lentiviral system to express them intracellularly and screen for their effects on cell proliferation. We thereby identified inhibitors that drastically reduced the viability of a pancreas cancer line (RWP1) while leaving a control line virtually unaffected. We identified their target interactions computationally, and validated a subset in experiments. We also discovered their potential mechanisms of action including apoptosis and cell cycle arrest. Finally, we confirmed that synthetic lipopeptide versions of our inhibitors have similarly specific and dosage dependent effects on cancer cell growth. Our screen reveals new drug targets and peptide drug leads and it provides a rich dataset covering phenotypes for inhibition of thousands of interactions.
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Affiliation(s)
- Satra Nim
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Jouhyun Jeon
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Carles Corbi-Verge
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Moon-Hyeong Seo
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Ylva Ivarsson
- Department of Chemistry, Biomedical Center (BMC), Uppsala University, Uppsala, Sweden
| | - Jason Moffat
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.,Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Nadya Tarasova
- Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, Maryland, USA
| | - Philip M Kim
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.,Department of Computer Science, University of Toronto, Toronto, Ontario, Canada
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61
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The E3 ubiquitin protein ligase MDM2 dictates all-trans retinoic acid-induced osteoblastic differentiation of osteosarcoma cells by modulating the degradation of RARα. Oncogene 2016; 35:4358-67. [DOI: 10.1038/onc.2015.503] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 11/30/2015] [Accepted: 12/04/2015] [Indexed: 12/15/2022]
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62
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Multiplex detection of protein-protein interactions using a next generation luciferase reporter. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:284-92. [PMID: 26646257 DOI: 10.1016/j.bbamcr.2015.11.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/24/2015] [Accepted: 11/26/2015] [Indexed: 11/21/2022]
Abstract
Cell-based assays of protein-protein interactions (PPIs) using split reporter proteins can be used to identify PPI agonists and antagonists. Generally, such assays measure one PPI at a time, and thus counterscreens for on-target activity must be run in parallel or at a subsequent stage; this increases both the cost and time during screening. Split luciferase systems offer advantages over those that use split fluorescent proteins (FPs). This is since split luciferase offers a greater signal:noise ratio and, unlike split FPs, the PPI can be reversed upon small molecule treatment. While multiplexed PPI assays using luciferase have been reported, they suffer from low signal:noise and require fairly complex spectral deconvolution during analysis. Furthermore, the luciferase enzymes used are large, which limits the range of PPIs that can be interrogated due to steric hindrance from the split luciferase fragments. Here, we report a multiplexed PPI assay based on split luciferases from Photinus pyralis (firefly luciferase, FLUC) and the deep-sea shrimp, Oplophorus gracilirostris (NanoLuc, NLUC). Specifically, we show that the binding of the p53 tumor suppressor to its two major negative regulators, MDM2 and MDM4, can be simultaneously measured within the same sample, without the requirement for complex filters or deconvolution. We provide chemical and genetic validation of this system using MDM2-targeted small molecules and mutagenesis, respectively. Combined with the superior signal:noise and smaller size of split NanoLuc, this multiplexed PPI assay format can be exploited to study the induction or disruption of pairwise interactions that are prominent in many cell signaling pathways.
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63
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p53 regulates the mevalonate pathway in human glioblastoma multiforme. Cell Death Dis 2015; 6:e1909. [PMID: 26469958 PMCID: PMC4632304 DOI: 10.1038/cddis.2015.279] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 08/04/2015] [Accepted: 08/09/2015] [Indexed: 11/30/2022]
Abstract
The mevalonate (MVA) pathway is an important metabolic pathway implicated in multiple aspects of tumorigenesis. In this study, we provided evidence that p53 induces the expression of a group of enzymes of the MVA pathway including 3′-hydroxy-3′-methylglutaryl-coenzyme A reductase, MVA kinase, farnesyl diphosphate synthase and farnesyl diphosphate farnesyl transferase 1, in the human glioblastoma multiforme cell line, U343 cells, and in normal human astrocytes, NHAs. Genetic and pharmacologic perturbation of p53 directly influences the expression of these genes. Furthermore, p53 is recruited to the gene promoters in designated p53-responsive elements, thereby increasing their transcription. Such effect was abolished by site-directed mutagenesis in the p53-responsive element of promoter of the genes. These findings highlight another aspect of p53 functions unrelated to tumor suppression and suggest p53 as a novel regulator of the MVA pathway providing insight into the role of this pathway in cancer progression.
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64
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The cholesterol metabolite 27-hydroxycholesterol regulates p53 activity and increases cell proliferation via MDM2 in breast cancer cells. Mol Cell Biochem 2015; 410:187-95. [PMID: 26350565 DOI: 10.1007/s11010-015-2551-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 09/02/2015] [Indexed: 01/04/2023]
Abstract
Estrogen is synthesized from cholesterol and high cholesterol levels are suggested to be associated with increased risk of estrogen receptor(ER)-positive breast cancer. The cholesterol metabolite 27-hydroxycholesterol (27-OHC) was recently identified as a selective estrogen receptor modulator (SERM) and may therefore impact breast cancer progression. However, the mechanisms by which 27-OHC may contribute to breast cancer are not all known. We determined the extent to which 27-OHC regulates cell proliferation in MCF7 ER-positive breast cancer cell line involving the tumor suppressor protein p53. We found that treatment of MCF7 cells with 27-OHC resulted reduced p53 transcriptional activity. Conversely, treatment of the ER-negative MDA-MB 231 cells with 27-OHC induced no significant change in p53 activity. Exposure of MCF7 cells to 27-OHC was also associated with increased protein levels of the E3 ubiquitin protein ligase MDM2 and decreased levels of p53. Moreover, 27-OHC also enhanced physical interaction between p53 and MDM2. Furthermore, 27-OHC-induced proliferation was attenuated using either the p53 activator Tenovin-1 or the MDM2 inhibitor Nutlin-3 and Mdm2 siRNA. Taken together, our results indicate that 27-OHC may contribute to ER-positive breast cancer progression by disrupting constitutive p53 signaling in an MDM2-dependent manner.
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65
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Zhang F, Li M, Wu X, Hu Y, Cao Y, Wang X, Xiang S, Li H, Jiang L, Tan Z, Lu W, Weng H, Shu Y, Gong W, Wang X, Zhang Y, Shi W, Dong P, Gu J, Liu Y. 20(S)-ginsenoside Rg3 promotes senescence and apoptosis in gallbladder cancer cells via the p53 pathway. Drug Des Devel Ther 2015; 9:3969-87. [PMID: 26309394 PMCID: PMC4539091 DOI: 10.2147/dddt.s84527] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Gallbladder cancer (GBC), the most frequent malignancy of the biliary tract, is associated with high mortality and extremely poor prognosis. 20(S)-ginsenoside Rg3 (20(S)-Rg3) is a steroidal saponin with high pharmacological activity. However, the anticancer effect of 20(S)-Rg3 in human GBC has not yet been determined. In this study, we primarily found that 20(S)-Rg3 exposure suppressed the survival of both NOZ and GBC-SD cell lines in a concentration-dependent manner. Moreover, induction of cellular senescence and G0/G1 arrest by 20(S)-Rg3 were accompanied by a large accumulation of p53 and p21 as a result of murine double minute 2 (MDM2) inhibition. 20(S)-Rg3 also caused a remarkable increase in apoptosis via the activation of the mitochondrial-mediated intrinsic caspase pathway. Furthermore, intraperitoneal injection of 20(S)-Rg3 (20 or 40 mg/kg) for 3 weeks markedly inhibited the growth of xenografts in nude mice. Our results demonstrated that 20(S)-Rg3 potently inhibited growth and survival of GBC cells both in vitro and in vivo. 20(S)-Rg3 attenuated GBC growth probably via activation of the p53 pathway, and subsequent induction of cellular senescence and mitochondrial-dependent apoptosis. Therefore, 20(S)-Rg3 may be a potential chemotherapeutic agent for GBC therapy.
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Affiliation(s)
- Fei Zhang
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Maolan Li
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Xiangsong Wu
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Yunping Hu
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Yang Cao
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Xu'an Wang
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Shanshan Xiang
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Huaifeng Li
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Lin Jiang
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Zhujun Tan
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Wei Lu
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Hao Weng
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Yijun Shu
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Wei Gong
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Xuefeng Wang
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Yong Zhang
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Weibin Shi
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Ping Dong
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Jun Gu
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Yingbin Liu
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Institute of Biliary Tract Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
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Chakraborty R, Li Y, Zhou L, Golic KG. Corp Regulates P53 in Drosophila melanogaster via a Negative Feedback Loop. PLoS Genet 2015; 11:e1005400. [PMID: 26230084 PMCID: PMC4521751 DOI: 10.1371/journal.pgen.1005400] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 06/26/2015] [Indexed: 01/08/2023] Open
Abstract
The tumor suppressor P53 is a critical mediator of the apoptotic response to DNA double-strand breaks through the transcriptional activation of pro-apoptotic genes. This mechanism is evolutionarily conserved from mammals to lower invertebrates, including Drosophila melanogaster. P53 also transcriptionally induces its primary negative regulator, Mdm2, which has not been found in Drosophila. In this study we identified the Drosophila gene companion of reaper (corp) as a gene whose overexpression promotes survival of cells with DNA damage in the soma but reduces their survival in the germline. These disparate effects are shared by p53 mutants, suggesting that Corp may be a negative regulator of P53. Confirming this supposition, we found that corp negatively regulates P53 protein level. It has been previously shown that P53 transcriptionally activates corp; thus, Corp produces a negative feedback loop on P53. We further found that Drosophila Corp shares a protein motif with vertebrate Mdm2 in a region that mediates the Mdm2:P53 physical interaction. In Corp, this motif mediates physical interaction with Drosophila P53. Our findings implicate Corp as a functional analog of vertebrate Mdm2 in flies.
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Affiliation(s)
- Riddhita Chakraborty
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - Ying Li
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Lei Zhou
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Kent G. Golic
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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Heyne K, Kölsch K, Bruand M, Kremmer E, Grässer FA, Mayer J, Roemer K. Np9, a cellular protein of retroviral ancestry restricted to human, chimpanzee and gorilla, binds and regulates ubiquitin ligase MDM2. Cell Cycle 2015; 14:2619-33. [PMID: 26103464 DOI: 10.1080/15384101.2015.1064565] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Humans and primates are long-lived animals with long reproductive phases. One factor that appears to contribute to longevity and fertility in humans, as well as to cancer-free survival, is the transcription factor and tumor suppressor p53, controlled by its main negative regulator MDM2. However, p53 and MDM2 homologs are found throughout the metazoan kingdom from Trichoplacidae to Hominidae. Therefore the question arises, if p53/MDM2 contributes to the shaping of primate features, then through which mechanisms. Previous findings have indicated that the appearances of novel p53-regulated genes and wild-type p53 variants during primate evolution are important in this context. Here, we report on another mechanism of potential relevance. Human endogenous retrovirus K subgroup HML-2 (HERV-K(HML-2)) type 1 proviral sequences were formed in the genomes of the predecessors of contemporary Hominoidea and can be identified in the genomes of Nomascus leucogenys (gibbon) up to Homo sapiens. We previously reported on an alternative splicing event in HERV-K(HML-2) type 1 proviruses that can give rise to nuclear protein of 9 kDa (Np9). We document here the evolution of Np9-coding capacity in human, chimpanzee and gorilla, and show that the C-terminal half of Np9 binds directly to MDM2, through a domain of MDM2 that is known to be contacted by various cellular proteins in response to stress. Np9 can inhibit the MDM2 ubiquitin ligase activity toward p53 in the cell nucleus, and can support the transactivation of genes by p53. Our findings point to the possibility that endogenous retrovirus protein Np9 contributes to the regulation of the p53-MDM2 pathway specifically in humans, chimpanzees and gorillas.
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Affiliation(s)
- Kristina Heyne
- a José Carreras Center and Internal Medicine I; University of Saarland Medical Center ; Homburg , Germany
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Rehman SU, Husain MA, Sarwar T, Ishqi HM, Tabish M. Modulation of alternative splicing by anticancer drugs. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 6:369-79. [DOI: 10.1002/wrna.1283] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 03/20/2015] [Accepted: 03/20/2015] [Indexed: 01/04/2023]
Affiliation(s)
- Sayeed Ur Rehman
- Department of Biochemistry, Faculty of Life Sciences; Aligarh Muslim University; Aligarh India
| | - Mohammed Amir Husain
- Department of Biochemistry, Faculty of Life Sciences; Aligarh Muslim University; Aligarh India
| | - Tarique Sarwar
- Department of Biochemistry, Faculty of Life Sciences; Aligarh Muslim University; Aligarh India
| | - Hassan Mubarak Ishqi
- Department of Biochemistry, Faculty of Life Sciences; Aligarh Muslim University; Aligarh India
| | - Mohammad Tabish
- Department of Biochemistry, Faculty of Life Sciences; Aligarh Muslim University; Aligarh India
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69
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Lv J, Zhu B, Zhang L, Xie Q, Zhuo W. MDM2 SNP309 variation confers the susceptibility to hepatocellular cancer: a meta-analysis based on 4271 subjects. Int J Clin Exp Med 2015; 8:5822-5830. [PMID: 26131172 PMCID: PMC4483806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 04/03/2015] [Indexed: 06/04/2023]
Abstract
Previous reports have indicated that MDM2 T309G polymorphism might be a risk factor for various cancers. Increasing studies have been conducted on the association of MDM2 T309G polymorphism with hepatocellular carcinoma (HCC) risk. However, the results remain inconclusive. Thus, the present study aimed to address this controversy by meta-analysis. Relevant literature up to Oct 2014 was searched and screened. Necessary information was rigorously extracted for data pooling and analyzing. Separate analyses on ethnicity, source of controls, sample size and P53 polymorphism status were also performed. As a result, eleven case-control studies were selected and the overall data indicated a significant association of MDM2 T309G polymorphism with HCC risk (GG vs. TT: OR=2.31; 95% CI=1.66-3.20; dominant model: OR=1.83; 95% CI=1.36-2.47; recessive model: OR=1.73; 95% CI=1.49-2.00). Similar results could be shown in the subgroups regarding ethnicity, source of controls and sample size. Interestingly, in the subgroup analysis regarding P53 codon 72 polymorphism, increased HCC risk could be observed in the Pro/Pro+Pro/Arg subgroup under a recessive model (OR=1.78; 95% CI=1.29-2.44). In conclusion, the results of the present study suggest that MDM2 T309G polymorphism might be a low-penetrant risk factor for HCC. Homozygous GG alleles might interact with Pro of P53 and thus confer the susceptibility to HCC.
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Affiliation(s)
- Jinli Lv
- Institute of Cancer, Xinqiao Hospital, Third Military Medical UniversityChongqing 400037, China
- Department of General Surgery, 153 Central Hospital of PLAZhengzhou 450007, Henan, China
| | - Bo Zhu
- Institute of Cancer, Xinqiao Hospital, Third Military Medical UniversityChongqing 400037, China
| | - Liang Zhang
- Institute of Cancer, Xinqiao Hospital, Third Military Medical UniversityChongqing 400037, China
| | - Qichao Xie
- Institute of Cancer, Xinqiao Hospital, Third Military Medical UniversityChongqing 400037, China
| | - Wenlei Zhuo
- Institute of Cancer, Xinqiao Hospital, Third Military Medical UniversityChongqing 400037, China
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Katzman B, Vyazmensky M, Press O, Volokita M, Engel S. Tethered ribozyme ligation enables detection of molecular proximity in homogeneous solutions. Biotechnol J 2015; 10:379-85. [DOI: 10.1002/biot.201400551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/04/2014] [Accepted: 12/11/2014] [Indexed: 11/06/2022]
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He X, Chen P, Yang K, Liu B, Zhang Y, Wang F, Guo Z, Liu X, Lou J, Chen H. Association of MDM2 polymorphism with risk and prognosis of leukemia: a meta-analysis. Acta Haematol 2015; 133:365-371. [PMID: 25790771 DOI: 10.1159/000369522] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/02/2014] [Indexed: 01/10/2023]
Abstract
OBJECTIVE In this study, we performed an updated meta-analysis by summarizing all available relevant association studies to evaluate whether the murine double minute-2 (MDM2) T309G polymorphism is associated with risk of leukemia and to determine its prognostic effect. MATERIAL AND METHODS Studies published in PubMed, Embase and the Cochrane Controlled Trial Register were searched till June 2014 using the search terms 'MDM2', 'polymorphism' and 'leukemia'. RESULTS Eleven studies were included in this meta-analysis, with a total of 2,478 patients accrued. There were 8 studies providing data on single nucleotide polymorphism at position 309 (SNP309) and risk of leukemia and 7 studies providing data on SNP309 and overall survival. Our analysis showed that patients having G/G mutations had a significantly higher risk of developing leukemia (HR 1.90, 95% CI 1.56-2.31, p < 0.00001), while the association between G/T and leukemia was not significant (HR 1.18, 95% CI 0.96-1.45, p = 0.11). In addition, SNP309 was not significantly associated with patient survival (HR 1.29, 95% CI 0.79-2.13, p = 0.31). CONCLUSIONS Our meta-analysis showed that the MDM2 T309G variation, especially homozygous G/G, might be associated with an increased risk of leukemia. Additional studies are needed to confirm the findings as well as to understand the underlying mechanisms.
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72
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Wu GC, Zhang ZT. Genetic association of single nucleotide polymorphisms in P53 pathway with gastric cancer risk in a Chinese Han population. Med Oncol 2014; 32:401. [PMID: 25479941 DOI: 10.1007/s12032-014-0401-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 11/21/2014] [Indexed: 12/11/2022]
Abstract
The tumor suppressor gene P53 plays an important role in carcinogenesis, and the P53 pathway is central both in reducing cancer frequency and in mediating the response of cancer therapies. MDM2, MDM4 and Hausp genes are all critical regulators of the tumor suppressor P53. Many studies have evaluated the association of single nucleotide polymorphisms (SNPs) in P53 pathway with the risk of common cancers. However, the results are still inconclusive. In this work, we analyzed the association of SNPs in P53 (rs1042522), MDM2 (rs2279744), MDM4 (rs1380576) and Hausp (rs1529916) genes with gastric cancer in a hospital-based Chinese Han population (642 cases and 720 cancer-free controls). We found that the polymorphisms of P53 (rs1042522) and MDM2 (rs2279744) are associated with gastric cancer risk, whereas no significant association was observed between variant genotype of other two polymorphisms (MDM4 rs1380576 and Hausp rs1529916) and gastric cancer risk.
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Affiliation(s)
- Guo-Cong Wu
- Department of General Surgery, Beijing Friendship Hospital Affiliated with Capital Medical University, Beijing, 100050, China,
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73
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Battle against cancer: an everlasting saga of p53. Int J Mol Sci 2014; 15:22109-27. [PMID: 25470027 PMCID: PMC4284697 DOI: 10.3390/ijms151222109] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 10/23/2014] [Accepted: 11/25/2014] [Indexed: 02/07/2023] Open
Abstract
Cancer is one of the most life-threatening diseases characterized by uncontrolled growth and spread of malignant cells. The tumor suppressor p53 is the master regulator of tumor cell growth and proliferation. In response to various stress signals, p53 can be activated and transcriptionally induces a myriad of target genes, including both protein-encoding and non-coding genes, controlling cell cycle progression, DNA repair, senescence, apoptosis, autophagy and metabolism of tumor cells. However, around 50% of human cancers harbor mutant p53 and, in the majority of the remaining cancers, p53 is inactivated through multiple mechanisms. Herein, we review the recent progress in understanding the molecular basis of p53 signaling, particularly the newly identified ribosomal stress—p53 pathway, and the development of chemotherapeutics via activating wild-type p53 or restoring mutant p53 functions in cancer. A full understanding of p53 regulation will aid the development of effective cancer treatments.
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74
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Zhou X, Hao Q, Zhang Q, Liao JM, Ke JW, Liao P, Cao B, Lu H. Ribosomal proteins L11 and L5 activate TAp73 by overcoming MDM2 inhibition. Cell Death Differ 2014; 22:755-66. [PMID: 25301064 DOI: 10.1038/cdd.2014.167] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 09/09/2014] [Accepted: 09/10/2014] [Indexed: 01/08/2023] Open
Abstract
Over the past decade, a number of ribosomal proteins (RPs) have been found to have a role in activating the tumor suppressor p53 by directly binding to MDM2 and impeding its activity toward p53. Herein, we report that RPL5 and RPL11 can also enhance the transcriptional activity of a p53 homolog TAp73, but through a distinct mechanism. Interestingly, even though RPL5 and RPL11 were not shown to bind to p53, they were able to directly associate with the transactivation domain of TAp73 independently of MDM2 in response to RS. This association led to perturbation of the MDM2-TAp73 interaction, consequently preventing MDM2 from its association with TAp73 target gene promoters. Furthermore, ectopic expression of RPL5 or RPL11 markedly induced TAp73 transcriptional activity by antagonizing MDM2 suppression. Conversely, ablation of either of the RPs compromised TAp73 transcriptional activity, as evident by the reduction of p21 and Puma expression, in response to 5-fluorouracil (5-FU). Consistently, overexpression of RPL5 or RPL11 enhanced, but knockdown of either of them hampered, TAp73-mediated apoptosis. Intriguingly, simultaneous knockdown of TAp73 and either of the RPs was required for rescuing the 5-FU-triggered S-phase arrest of p53-null tumor cells. These results demonstrate a novel mechanism underlying the inhibition of tumor cell proliferation and growth by these two RPs via TAp73 activation.
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Affiliation(s)
- X Zhou
- Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA
| | - Q Hao
- Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA
| | - Q Zhang
- Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA
| | - J-M Liao
- Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA
| | - J-W Ke
- 1] Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA [2] Department of Laboratory Medicine; Jiangxi Children's Hospital, Nanchang, Jiangxi, China
| | - P Liao
- Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA
| | - B Cao
- Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA
| | - H Lu
- Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA
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Abstract
The ubiquitin proteasome pathway is critical in restraining the activities of the p53 tumor suppressor. This review by Pant and Lozano focuses on ubiquitination as a mechanism for regulating p53 stability and function and reviews current findings from in vivo models that evaluate the importance of the ubiquitin proteasome system in regulating p53. The ubiquitin proteasome pathway is critical in restraining the activities of the p53 tumor suppressor. Numerous E3 and E4 ligases regulate p53 levels. Additionally, deubquitinating enzymes that modify p53 directly or indirectly also impact p53 function. When alterations of these proteins result in increased p53 activity, cells arrest in the cell cycle, senesce, or apoptose. On the other hand, alterations that result in decreased p53 levels yield tumor-prone phenotypes. This review focuses on the physiological relevance of these important regulators of p53 and their therapeutic implications.
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Affiliation(s)
- Vinod Pant
- Department of Genetics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
| | - Guillermina Lozano
- Department of Genetics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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76
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Yan YL, Han F, Tan WM, Wu CP, Qin X. Association between the MDM2 T309G polymorphism and leukemia risk: a meta-analysis. Asian Pac J Cancer Prev 2014; 15:6767-72. [PMID: 25169523 DOI: 10.7314/apjcp.2014.15.16.6767] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Several studies have suggested associations between MDM2 (mouse double minute 2 homolog) polymorphisms and leukemia risk, but they reported contradictory results. For better understanding of the effect of MDM2 T309G polymorphism on leukemia risk, we performed a meta-analysis. All eligible studies were identified through a search of PubMed, Web of Science, EMBASE, and Chinese Biomedical Literature (CBM) databases before May 2014. Assessment of associations between the MDM2 T309G polymorphism and leukemia risk was conducted by odds ratios (ORs) and 95% confidence intervals (95% CIs). Finally, a total of 11 publications covering 12 case-control studies with 2, 362 cases and 5, 562 controls concerning MDM2 T309G polymorphism with respect to leukemia were included in the meta-analysis. Significant associations were found between MDM2 T309G polymorphism and leukemia risk in four models in overall populations (G vs T: OR=1.29, 95% CI=1.11- 1.49, p=0.001; GG vs TT: OR=1.67, 95% CI=1.21-2.30, p=0.002; GG vs TG/TT: OR=1.56, 95% CI=1.21-2.00, p=0.001; GG/TG vs TT: OR=1.28, 95% CI=1.05-1.57, p=0.015). In the sub-group analysis according to ethnicity, increased leukemia risks were observed in three genetic models among Asians but not Caucasians. In conclusion, the results of our meta-analysis suggest that the MDM2 T309G polymorphism can increase the risk of leukemia, especially among Asian populations.
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Affiliation(s)
- Yu-Lan Yan
- Department of Clinical Laboratory, Affiliated Hospital of Hainan Medical College, Haikou, Hainan, China E-mail :
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Ireno IC, Wiehe RS, Stahl AI, Hampp S, Aydin S, Troester MA, Selivanova G, Wiesmüller L. Modulation of the poly (ADP-ribose) polymerase inhibitor response and DNA recombination in breast cancer cells by drugs affecting endogenous wild-type p53. Carcinogenesis 2014; 35:2273-82. [PMID: 25085902 DOI: 10.1093/carcin/bgu160] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Synthetic lethal interactions between poly (ADP-ribose) polymerase (PARP) and homologous recombination (HR) repair pathways have been exploited for the development of novel mono- and combination cancer therapies. The tumor suppressor p53 was demonstrated to exhibit indirect and direct regulatory activities in DNA repair, particularly in DNA double-strand break (DSB)-induced and replication-associated HR. In this study, we tested a potential influence of the p53 status on the response to PARP inhibition, which is known to cause replication stress. Silencing endogenous or inducibly expressing p53 we found a protective effect of p53 on PARP inhibitor (PARPi)-mediated cytotoxicities. This effect was specific for wild-type versus mutant p53 and observed in cancer but not in non-transformed cell lines. Enhanced cytotoxicities after treatment with the p53-inhibitory drug Pifithrinα further supported p53-mediated resistance to PARP inhibition. Surprisingly, we equally observed increased PARPi sensitivity in the presence of the p53-activating compound Nutlin-3. As a common denominator, both drug responses correlated with decreased HR activities: Pifithrinα downregulated spontaneous HR resulting in damage accumulation. Nutlin-3 induced a decrease of DSB-induced HR, which was accompanied by a severe drop in RAD51 protein levels. Thus, we revealed a novel link between PARPi responsiveness and p53-controlled HR activities. These data expand the concept of cell and stress type-dependent healer and killer functions of wild-type p53 in response to cancer therapeutic treatment. Our findings have implications for the individualized design of cancer therapies using PARPi and the potentially combined use of p53-modulatory drugs.
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Affiliation(s)
| | - Rahel Stephanie Wiehe
- Department of Obstetrics and Gynecology, Ulm University, Prittwitzstrasse 43, D-89075 Ulm, Germany,
| | - Andreea Iulia Stahl
- Department of Obstetrics and Gynecology, Ulm University, Prittwitzstrasse 43, D-89075 Ulm, Germany
| | - Stephanie Hampp
- Department of Obstetrics and Gynecology, Ulm University, Prittwitzstrasse 43, D-89075 Ulm, Germany
| | - Sevtap Aydin
- Department of Obstetrics and Gynecology, Ulm University, Prittwitzstrasse 43, D-89075 Ulm, Germany, Department of Toxicology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey
| | | | - Galina Selivanova
- Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm 17177, Sweden
| | - Lisa Wiesmüller
- Department of Obstetrics and Gynecology, Ulm University, Prittwitzstrasse 43, D-89075 Ulm, Germany,
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Allen MA, Andrysik Z, Dengler VL, Mellert HS, Guarnieri A, Freeman JA, Sullivan KD, Galbraith MD, Luo X, Kraus WL, Dowell RD, Espinosa JM. Global analysis of p53-regulated transcription identifies its direct targets and unexpected regulatory mechanisms. eLife 2014; 3:e02200. [PMID: 24867637 PMCID: PMC4033189 DOI: 10.7554/elife.02200] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The p53 transcription factor is a potent suppressor of tumor growth. We report here an analysis of its direct transcriptional program using Global Run-On sequencing (GRO-seq). Shortly after MDM2 inhibition by Nutlin-3, low levels of p53 rapidly activate ∼200 genes, most of them not previously established as direct targets. This immediate response involves all canonical p53 effector pathways, including apoptosis. Comparative global analysis of RNA synthesis vs steady state levels revealed that microarray profiling fails to identify low abundance transcripts directly activated by p53. Interestingly, p53 represses a subset of its activation targets before MDM2 inhibition. GRO-seq uncovered a plethora of gene-specific regulatory features affecting key survival and apoptotic genes within the p53 network. p53 regulates hundreds of enhancer-derived RNAs. Strikingly, direct p53 targets harbor pre-activated enhancers highly transcribed in p53 null cells. Altogether, these results enable the study of many uncharacterized p53 target genes and unexpected regulatory mechanisms.DOI: http://dx.doi.org/10.7554/eLife.02200.001.
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Affiliation(s)
- Mary Ann Allen
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States BioFrontiers Institute, Boulder, United States Computational Biosciences Program, University of Colorado, Denver-Anschutz Medical Campus, Aurora, United States
| | - Zdenek Andrysik
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Veronica L Dengler
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Hestia S Mellert
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Anna Guarnieri
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Justin A Freeman
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Kelly D Sullivan
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Matthew D Galbraith
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Xin Luo
- Signalling and Gene Regulation Laboratory, Cecil H and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, United States
| | - W Lee Kraus
- Signalling and Gene Regulation Laboratory, Cecil H and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, United States
| | - Robin D Dowell
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States BioFrontiers Institute, Boulder, United States
| | - Joaquin M Espinosa
- Howard Hughes Medical Institute, University of Colorado, Boulder, Boulder, United States Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, United States
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79
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Wilking MJ, Singh C, Nihal M, Zhong W, Ahmad N. SIRT1 deacetylase is overexpressed in human melanoma and its small molecule inhibition imparts anti-proliferative response via p53 activation. Arch Biochem Biophys 2014; 563:94-100. [PMID: 24751483 DOI: 10.1016/j.abb.2014.04.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 04/03/2014] [Accepted: 04/05/2014] [Indexed: 11/30/2022]
Abstract
Melanoma causes more deaths than any other skin cancer, and its incidence in the US continues to rise. Current medical therapies are insufficient to control this deadly neoplasm, necessitating the development of new target-based approaches. The objective of this study was to determine the role and functional significance of the class III histone deacetylase SIRT1 in melanoma. We have found that SIRT1 is overexpressed in clinical human melanoma tissues and human melanoma cell lines (Sk-Mel-2, WM35, G361, A375, and Hs294T) compared to normal skin and normal melanocytes, respectively. In addition, treatment of melanoma cell lines A375, Hs294T, and G361 with Tenovin-1, a small molecule SIRT1 inhibitor, resulted in a significant decrease in cell growth and cell viability. Further, Tenovin-1 treatment also resulted in a marked decrease in the clonogenic survival of melanoma cells. Further experiments showed that the anti-proliferative response of Tenovin-1 was accompanied by an increase in the protein as well as activity of the tumor suppressor p53. This increase in p53 activity was substantiated by an increase in the protein level of its downstream target p21. Overall, these data suggest that small molecule inhibition of SIRT1 causes anti-proliferative effects in melanoma cells. SIRT1 appears to be acting through the activity of the tumor suppressor p53, which is not mutated in the majority of melanomas. However, future detailed studies are needed to further explore the role and mechanism of SIRT1 in melanoma development and progression and its usefulness in melanoma treatment.
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Affiliation(s)
- Melissa J Wilking
- Department of Dermatology, University of Wisconsin, Madison, WI 53706, USA
| | - Chandra Singh
- Department of Dermatology, University of Wisconsin, Madison, WI 53706, USA
| | - Minakshi Nihal
- Department of Dermatology, University of Wisconsin, Madison, WI 53706, USA
| | - Weixiong Zhong
- Department of Pathology, University of Wisconsin, Madison, WI 53705, USA
| | - Nihal Ahmad
- Department of Dermatology, University of Wisconsin, Madison, WI 53706, USA; William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA.
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80
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Read ML, Seed RI, Fong JCW, Modasia B, Ryan GA, Watkins RJ, Gagliano T, Smith VE, Stratford AL, Kwan PK, Sharma N, Dixon OM, Watkinson JC, Boelaert K, Franklyn JA, Turnell AS, McCabe CJ. The PTTG1-binding factor (PBF/PTTG1IP) regulates p53 activity in thyroid cells. Endocrinology 2014; 155:1222-34. [PMID: 24506068 PMCID: PMC4759943 DOI: 10.1210/en.2013-1646] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The PTTG1-binding factor (PBF/PTTG1IP) has an emerging repertoire of roles, especially in thyroid biology, and functions as a protooncogene. High PBF expression is independently associated with poor prognosis and lower disease-specific survival in human thyroid cancer. However, the precise role of PBF in thyroid tumorigenesis is unclear. Here, we present extensive evidence demonstrating that PBF is a novel regulator of p53, a tumor suppressor protein with a key role in maintaining genetic stability, which is infrequently mutated in differentiated thyroid cancer. By coimmunoprecipitation and proximity-ligation assays, we show that PBF binds specifically to p53 in thyroid cells and significantly represses transactivation of responsive promoters. Further, we identify that PBF decreases p53 stability by enhancing ubiquitination, which appears dependent on the E3 ligase activity of Mdm2. Impaired p53 function was evident in a transgenic mouse model with thyroid-specific PBF overexpression (transgenic PBF mice), which had significantly increased genetic instability as indicated by fluorescent inter simple sequence repeat-PCR analysis. Consistent with this, approximately 40% of all DNA repair genes examined were repressed in transgenic PBF primary cultures, including genes with critical roles in maintaining genomic integrity such as Mgmt, Rad51, and Xrcc3. Our data also revealed that PBF induction resulted in up-regulation of the E2 enzyme Rad6 in murine thyrocytes and was associated with Rad6 expression in human thyroid tumors. Overall, this work provides novel insights into the role of the protooncogene PBF as a negative regulator of p53 function in thyroid tumorigenesis, in which PBF is generally overexpressed and p53 mutations are rare compared with other tumor types.
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Affiliation(s)
- Martin L Read
- School of Clinical and Experimental Medicine (M.L.R., R.I.S., J.C.W.F., B.M., G.A.R., R.J.W., V.E.S., P.K.K., N.S., O.M.D., K.B., J.A.F., C.J.M.) and School of Cancer Sciences (A.S.T.), University of Birmingham, Birmingham, United Kingdom; Department of Medical Sciences (T.G.), University of Ferrara, Ferrara, Italy; Department of Pediatrics (A.L.S.), University of British Columbia, Vancouver, British Columbia, Canada; and University Hospitals Birmingham National Health Service Foundation Trust (J.C.W.), Birmingham, United Kingdom
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81
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Nicholson J, Scherl A, Way L, Blackburn EA, Walkinshaw MD, Ball KL, Hupp TR. A systems wide mass spectrometric based linear motif screen to identify dominant in-vivo interacting proteins for the ubiquitin ligase MDM2. Cell Signal 2014; 26:1243-57. [PMID: 24583282 DOI: 10.1016/j.cellsig.2014.02.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 02/21/2014] [Indexed: 12/24/2022]
Abstract
Linear motifs mediate protein-protein interactions (PPI) that allow expansion of a target protein interactome at a systems level. This study uses a proteomics approach and linear motif sub-stratifications to expand on PPIs of MDM2. MDM2 is a multi-functional protein with over one hundred known binding partners not stratified by hierarchy or function. A new linear motif based on a MDM2 interaction consensus is used to select novel MDM2 interactors based on Nutlin-3 responsiveness in a cell-based proteomics screen. MDM2 binds a subset of peptide motifs corresponding to real proteins with a range of allosteric responses to MDM2 ligands. We validate cyclophilin B as a novel protein with a consensus MDM2 binding motif that is stabilised by Nutlin-3 in vivo, thus identifying one of the few known interactors of MDM2 that is stabilised by Nutlin-3. These data invoke two modes of peptide binding at the MDM2 N-terminus that rely on a consensus core motif to control the equilibrium between MDM2 binding proteins. This approach stratifies MDM2 interacting proteins based on the linear motif feature and provides a new biomarker assay to define clinically relevant Nutlin-3 responsive MDM2 interactors.
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Affiliation(s)
- Judith Nicholson
- Edinburgh Cancer Research Centre, Cell Signalling Unit, University of Edinburgh, EH4 2XR, United Kingdom; Department of Radiation Oncology and Biology, University of Oxford, OX3 7DQ, United Kingdom
| | - Alex Scherl
- Proteomics Core Facility, University of Geneva, Switzerland
| | - Luke Way
- Edinburgh Cancer Research Centre, Cell Signalling Unit, University of Edinburgh, EH4 2XR, United Kingdom
| | - Elizabeth A Blackburn
- Edinburgh Centre for Chemical Biology, University of Edinburgh, EH9 3JG, United Kingdom
| | - Malcolm D Walkinshaw
- Edinburgh Centre for Chemical Biology, University of Edinburgh, EH9 3JG, United Kingdom
| | - Kathryn L Ball
- Edinburgh Cancer Research Centre, Cell Signalling Unit, University of Edinburgh, EH4 2XR, United Kingdom
| | - Ted R Hupp
- Edinburgh Cancer Research Centre, Cell Signalling Unit, University of Edinburgh, EH4 2XR, United Kingdom.
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82
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Zhao Z, Wu L, Shi H, Wu C. p53 N‑terminal binding and stabilisation by PIAS3 inhibits MDM2‑induced p53 ubiquitination and regulates cell growth. Mol Med Rep 2014; 9:1903-8. [PMID: 24584189 DOI: 10.3892/mmr.2014.1993] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 02/17/2014] [Indexed: 11/06/2022] Open
Abstract
Mouse double minute 2 homolog (MDM2) binds to p53 through the 1-52 amino acid region of p53, in order to ubiquitinate p53. MDM2 thus destabilises p53 and inhibits the effect of p53 on cell cycle arrest and apoptosis. In the present study, the 1-52 amino acid region of the wild-type (wt) p53 protein was stably expressed in H1299 cells. The lysate of the transfected cells was then analysed using co-immunoprecipitation. A specific fraction of the precipitate was subjected to mass spectrometry analysis, which revealed that p53 bound to protein inhibitor of activated STAT3 (PIAS3). To the best of our knowledge, the present study is the first to report that the interaction of PIAS3 with p53 occurs through the 1-52 amino acid region of p53. Overexpression of PIAS3 in the A549 wt p53-expressing cell line was found to significantly increase the half‑life of p53 in the presence of cycloheximide, an inhibitor of protein synthesis. However, PIAS3 overexpression did not affect p53 mRNA levels. Furthermore, PIAS3 overexpression was observed to decrease p53 ubiquitination. Protein-protein interaction analysis revealed that PIAS3 binds to the 1-52 amino acid region of p53, thus disrupts the formation of the p53‑MDM2 complex. In addition, overexpression of PIAS3 in A549 cells was found to enhance the transcription of the p53‑transactivated target p21/waf1, due to p53 accumulation, which led to an increase in p53 binding to the p21 gene promoter. These findings indicate that this newly identified p53‑PIAS3 interaction through the 1-52 amino acid region of p53, reduces p53‑MDM2 complex formation, which not only increases the half-life of p53, but also its transactivation of target genes.
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Affiliation(s)
- Ziyi Zhao
- Key Laboratory of Bioresources and Ecoenvironment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan 610064, P.R. China
| | - Lan Wu
- Key Laboratory of Bioresources and Ecoenvironment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan 610064, P.R. China
| | - Huimin Shi
- Key Laboratory of Bioresources and Ecoenvironment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan 610064, P.R. China
| | - Chuanfang Wu
- Key Laboratory of Bioresources and Ecoenvironment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan 610064, P.R. China
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83
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Heyne K, Förster J, Schüle R, Roemer K. Transcriptional repressor NIR interacts with the p53-inhibiting ubiquitin ligase MDM2. Nucleic Acids Res 2014; 42:3565-79. [PMID: 24413661 PMCID: PMC3973334 DOI: 10.1093/nar/gkt1371] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
NIR (novel INHAT repressor) can bind to p53 at promoters and inhibit p53-mediated gene transactivation by blocking histone acetylation carried out by p300/CBP. Like NIR, the E3 ubiquitin ligase MDM2 can also bind and inhibit p53 at promoters. Here, we present data indicating that NIR, which shuttles between the nucleolus and nucleoplasm, not only binds to p53 but also directly to MDM2, in part via the central acidic and zinc finger domain of MDM2 that is also contacted by several other nucleolus-based MDM2/p53-regulating proteins. Like some of these, NIR was able to inhibit the ubiquitination of MDM2 and stabilize MDM2; however, unlike these nucleolus-based MDM2 regulators, NIR did not inhibit MDM2 to activate p53. Rather, NIR cooperated with MDM2 to repress p53-induced transactivation. This cooperative repression may at least in part involve p300/CBP. We show that NIR can block the acetylation of p53 and MDM2. Non-acetylated p53 has been documented previously to more readily associate with inhibitory MDM2. NIR may thus help to sustain the inhibitory p53:MDM2 complex, and we present evidence suggesting that all three proteins can indeed form a ternary complex. In sum, our findings suggest that NIR can support MDM2 to suppress p53 as a transcriptional activator.
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Affiliation(s)
- Kristina Heyne
- José Carreras Research Center and Internal Medicine I, University of Saarland Medical Center, 66421 Homburg/Saar, Germany and Department of Urology, Center for Clinical Research, University of Freiburg, 79106 Freiburg, Germany
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84
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Nag S, Zhang X, Srivenugopal K, Wang MH, Wang W, Zhang R. Targeting MDM2-p53 interaction for cancer therapy: are we there yet? Curr Med Chem 2014; 21:553-74. [PMID: 24180275 PMCID: PMC6690199 DOI: 10.2174/09298673113206660325] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 10/02/2013] [Accepted: 10/22/2013] [Indexed: 11/22/2022]
Abstract
Inactivation of the tumor suppressor p53 and/or overexpression of the oncogene MDM2 frequently occur in human cancers, and are associated with poor prognosis, advanced forms of the disease, and chemoresistance. MDM2, the major negative regulator of p53, induces p53 degradation and inactivates its tumor suppressing activity. In turn, p53 regulates MDM2 expression. This MDM2-p53 negative feedback loop has been widely studied and presents an attractive target for cancer therapy, with a few of the inhibitors of this interaction already having advanced into clinical trials. Additionally, there is an increasing interest in understanding MDM2's p53-independent activities in carcinogenesis and cancer progression, which may also have implications for cancer therapy. This review aims to highlight the various roles that the MDM2-p53 interaction plays in cancer, the p53 independent oncogenic activities of MDM2 and the various strategies that may be used to target MDM2 and the MDM2-p53 interaction. We will summarize the major preclinical and clinical evidences of MDM2 inhibitors for human cancer treatment and make suggestions to further improve efficacy and safety of this interesting class of cancer therapeutics.
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Affiliation(s)
- S. Nag
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - X. Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - K.S. Srivenugopal
- Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
- Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - M.-H. Wang
- Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
- Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - W. Wang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
- Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - R. Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
- Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
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85
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Sonnemann J, Marx C, Becker S, Wittig S, Palani CD, Krämer OH, Beck JF. p53-dependent and p53-independent anticancer effects of different histone deacetylase inhibitors. Br J Cancer 2013; 110:656-67. [PMID: 24281001 PMCID: PMC3915118 DOI: 10.1038/bjc.2013.742] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/28/2013] [Accepted: 10/30/2013] [Indexed: 12/17/2022] Open
Abstract
Background: Histone deacetylase inhibitors (HDACi) are promising antineoplastic agents, but their precise mechanisms of actions are not well understood. In particular, the relevance of p53 for HDACi-induced effects has not been fully elucidated. We investigated the anticancer effects of four structurally distinct HDACi, vorinostat, entinostat, apicidin and valproic acid, using isogenic HCT-116 colon cancer cell lines differing in p53 status. Methods: Effects were assessed by MTT assay, flow-cytometric analyses of propidium iodide uptake, mitochondrial depolarisation and cell-cycle distribution, as well as by gene expression profiling. Results: Vorinostat was equally effective in p53 wild-type and null cells, whereas entinostat was less effective in p53 null cells. Histone deacetylase inhibitors treatment suppressed the expression of MDM2 and increased the abundance of p53. Combination treatments showed that vorinostat enhanced the cytotoxic activity of TRAIL and bortezomib, independent of the cellular p53 status. Investigations into the effects of an inhibitor of the sirtuin class of HDAC, tenovin-1, revealed that tenovin-1-mediated cell death hinged on p53. Conclusion: These results demonstrate that vorinostat activates p53, but does not require p53 for inducing its anticancer action. Yet they also demonstrate that entinostat-induced cytotoxic effects partially depend on p53, indicating that different HDACi have a different requirement for p53.
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Affiliation(s)
- J Sonnemann
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
| | - C Marx
- Department of Biochemistry, Center for Molecular Biomedicine, Institute for Biochemistry and Biophysics, Friedrich Schiller University of Jena, Jena, Germany
| | - S Becker
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
| | - S Wittig
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
| | - C D Palani
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
| | - O H Krämer
- Department of Biochemistry, Center for Molecular Biomedicine, Institute for Biochemistry and Biophysics, Friedrich Schiller University of Jena, Jena, Germany
| | - J F Beck
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
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Hamard PJ, Barthelery N, Hogstad B, Mungamuri SK, Tonnessen CA, Carvajal LA, Senturk E, Gillespie V, Aaronson SA, Merad M, Manfredi JJ. The C terminus of p53 regulates gene expression by multiple mechanisms in a target- and tissue-specific manner in vivo. Genes Dev 2013; 27:1868-85. [PMID: 24013501 PMCID: PMC3778241 DOI: 10.1101/gad.224386.113] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The C terminus of the tumor suppressor p53 is subjected to multiple post-translational modifications, suggesting that differing sets of modifications determine distinct cellular outcomes. Hamard et al. address this question by generating a Trp53 mutant mouse that constitutively expresses truncated p53. Intriguingly, the C terminus acts via three distinct mechanisms to control p53-dependent gene expression depending on the tissue. This study reconciles contradictory reports and delineates how regulation of target gene selectivity by p53 leads to alternate cellular outcomes. The p53 tumor suppressor is a transcription factor that mediates varied cellular responses. The C terminus of p53 is subjected to multiple and diverse post-translational modifications. An attractive hypothesis is that differing sets of combinatorial modifications therein determine distinct cellular outcomes. To address this in vivo, a Trp53ΔCTD/ΔCTD mouse was generated in which the endogenous p53 is targeted and replaced with a truncated mutant lacking the C-terminal 24 amino acids. These Trp53ΔCTD/ΔCTD mice die within 2 wk post-partum with hematopoietic failure and impaired cerebellar development. Intriguingly, the C terminus acts via three distinct mechanisms to control p53-dependent gene expression depending on the tissue. First, in the bone marrow and thymus, the C terminus dampens p53 activity. Increased senescence in the Trp53ΔCTD/ΔCTD bone marrow is accompanied by up-regulation of Cdkn1 (p21). In the thymus, the C-terminal domain negatively regulates p53-dependent gene expression by inhibiting promoter occupancy. Here, the hyperactive p53ΔCTD induces apoptosis via enhanced expression of the proapoptotic Bbc3 (Puma) and Pmaip1 (Noxa). In the liver, a second mechanism prevails, since p53ΔCTD has wild-type DNA binding but impaired gene expression. Thus, the C terminus of p53 is needed in liver cells at a step subsequent to DNA binding. Finally, in the spleen, the C terminus controls p53 protein levels, with the overexpressed p53ΔCTD showing hyperactivity for gene expression. Thus, the C terminus of p53 regulates gene expression via multiple mechanisms depending on the tissue and target, and this leads to specific phenotypic effects in vivo.
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87
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Peng Q, Mo C, Qin A, Lao X, Chen Z, Sui J, Wu J, Zhai L, Yang S, Qin X, Li S. MDM2 SNP309 polymorphism contributes to endometrial cancer susceptibility: evidence from a meta-analysis. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2013; 32:85. [PMID: 24423195 PMCID: PMC4029393 DOI: 10.1186/1756-9966-32-85] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 10/28/2013] [Indexed: 12/31/2022]
Abstract
OBJECTIVE The SNP309 polymorphism (T-G) in the promoter of MDM2 gene has been reported to be associated with enhanced MDM2 expression and tumor development. Studies investigating the association between MDM2 SNP309 polymorphism and endometrial cancer risk reported conflicting results. We performed a meta-analysis of all available studies to explore this association. METHODS All studies published up to August 2013 on the association between MDM2 SNP309 polymorphism and endometrial cancer risk were identified by searching electronic databases PubMed, Web of Science, EMBASE, and Chinese Biomedical Literature database (CBM). The association between the MDM2 SNP309 polymorphism and endometrial cancer risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). RESULTS Eight case-control studies with 2069 endometrial cancer cases and 4546 controls were identified. Overall, significant increase of endometrial cancer risk was found when all studies were pooled in the meta-analysis (GG vs. TT: OR = 1.464, 95% CI 1.246-1.721, P < 0.001; GG vs. TG + TT: OR = 1.726, 95% CI 1.251-2.380, P = 0.001; GG + TG vs. TT: OR = 1.169, 95% CI 1.048-1.304, P = 0.005). In subgroup analysis by ethnicity and HWE in controls, significant increase of endometrial cancer risks were observed in Caucasians and studies consistent with HWE. In subgroup analysis according to study quality, significant associations were observed in both high quality studies and low quality studies. CONCLUSIONS This meta-analysis suggests that MDM2 SNP309 polymorphism contributes to endometrial cancer susceptibility, especially in Caucasian populations. Further large and well-designed studies are needed to confirm this association.
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88
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In vitro and in silico studies of MDM2/MDMX isoforms predict Nutlin-3A sensitivity in well/de-differentiated liposarcomas. J Transl Med 2013; 93:1232-40. [PMID: 24018792 DOI: 10.1038/labinvest.2013.107] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 08/04/2013] [Indexed: 12/31/2022] Open
Abstract
The molecular marker of well-differentiated/de-differentiated liposarcomas is MDM2 gene amplification coupled with protein overexpression and wild-type TP53. MDMX is a recently identified MDM2 homolog and its presence in this tumor is unexplored. Our aim was to investigate the role of full-length MDM2 and MDMX proteins and their isoforms in surgical specimens of well-differentiated/de-differentiated liposarcomas in view of Nutlin-3A (a MDM2 inhibitor) treatment. Frozen and matched formalin-fixed, paraffin-embedded material from surgical specimens was examined by means of: (1) fluorescence in situ hybridization to determine MDM2 and MDMX gene copy numbers; (2) RT-PCR and densitometry to analyze alternative splicing forms of mdm2 and mdmx; (3) immunoblotting and immunohistochemistry to assess the corresponding translated proteins; and (4) in vitro and in silico assays to determine their affinity for Nutlin-3A. All these cases showed MDM2 gene amplification with an MDMX disomic pattern. In all cases, the full-length mdm2 transcript was associated with the mdm2-b transcript, with ratios ranging from 0.07 to 5.6, and both were translated into protein; mdmx and mdmx-s were co-transcripted, with ratios ranging from 0.1 to 5.6. MDMX-S was frequently more upregulated than MDMX at both transcriptional and protein level. Each case showed different amounts of mdm2, mdm2-b, mdmx, and mdmx-s transcripts and the corresponding proteins. In vitro assays showed that Nutlin-3A was ineffective against MDM2-B and was unable to disrupt the MDMX/TP53 and MSMX-S/TP53 complexes. Molecular simulations confirmed these in vitro findings by showing that MDM2 has high Nutlin-3A affinity, followed by MDMX-S, MDMX, and MDM2-B. Nutlin-3A is predicted to be a good therapeutic option for well-differentiated/de-differentiated liposarcomas. However, our findings predict heterogeneous responses depending on the relative expression of mdm2, mdm2-b, mdmx, and mdmx-s transcripts and proteins.
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89
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Shahar OD, Gabizon R, Feine O, Alhadeff R, Ganoth A, Argaman L, Shimshoni E, Friedler A, Goldberg M. Acetylation of lysine 382 and phosphorylation of serine 392 in p53 modulate the interaction between p53 and MDC1 in vitro. PLoS One 2013; 8:e78472. [PMID: 24194938 PMCID: PMC3806821 DOI: 10.1371/journal.pone.0078472] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 09/12/2013] [Indexed: 11/18/2022] Open
Abstract
Occurrence of DNA damage in a cell activates the DNA damage response, a survival mechanism that ensures genomics stability. Two key members of the DNA damage response are the tumor suppressor p53, which is the most frequently mutated gene in cancers, and MDC1, which is a central adaptor that recruits many proteins to sites of DNA damage. Here we characterize the in vitro interaction between p53 and MDC1 and demonstrate that p53 and MDC1 directly interact. The p53-MDC1 interaction is mediated by the tandem BRCT domain of MDC1 and the C-terminal domain of p53. We further show that both acetylation of lysine 382 and phosphorylation of serine 392 in p53 enhance the interaction between p53 and MDC1. Additionally, we demonstrate that the p53-MDC1 interaction is augmented upon the induction of DNA damage in human cells. Our data suggests a new role for acetylation of lysine 382 and phosphorylation of serine 392 in p53 in the cellular stress response and offers the first evidence for an interaction involving MDC1 that is modulated by acetylation.
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Affiliation(s)
- Or David Shahar
- The Department of Genetics, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ronen Gabizon
- The Department of Organic Chemistry, the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Oren Feine
- The Department of Genetics, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Raphael Alhadeff
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Assaf Ganoth
- The Interdisciplinary Center (IDC), Herzliya, Israel and Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa-Oranim, Tivon, Israel
| | - Liron Argaman
- The Department of Genetics, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Elee Shimshoni
- The Department of Genetics, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Assaf Friedler
- The Department of Organic Chemistry, the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Michal Goldberg
- The Department of Genetics, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail:
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90
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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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91
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Qin X, Peng Q, Tang W, Lao X, Chen Z, Lai H, Deng Y, Mo C, Sui J, Wu J, Zhai L, Yang S, Li S, Zhao J. An updated meta-analysis on the association of MDM2 SNP309 polymorphism with colorectal cancer risk. PLoS One 2013; 8:e76031. [PMID: 24098760 PMCID: PMC3786895 DOI: 10.1371/journal.pone.0076031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 08/21/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The mouse double minute 2 (MDM2) gene encodes a phosphoprotein that interacts with P53 and negatively regulates its activity. The SNP309 polymorphism (T-G) in the promoter of MDM2 gene has been reported to be associated with enhanced MDM2 expression and tumor development. Studies investigating the association between MDM2 SNP309 polymorphism and colorectal cancer (CRC) risk reported conflicting results. We performed a meta-analysis of all available studies to explore the association of this polymorphism with CRC risk. METHODS All studies published up to July 2013 on the association between MDM2 SNP309 polymorphism and CRC risk were identified by searching electronic databases PubMed, EMBASE, and Chinese Biomedical Literature database (CBM) databases. The association between the MDM2 SNP309 polymorphism and CRC risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). RESULTS A total of 14 case-control studies including 4460 CRC cases and 4828 controls were identified. We did not find a significant association between the MDM2 SNP309 polymorphism and CRC risk in all genetic models in overall population. However, in subgroup analysis by ethnicity, significant associations were found in Asians (TG vs. TT: OR = 1.197, 95% CI = 1.055-1.358, P=0.005; GG+TG vs. TT: OR = 1.246, 95% CI = 1.106-1.404, P=0.000) and Africans. When stratified by HWE in controls, significantly increased risk was also found among the studies consistent with HWE (TG vs. TT: OR = 1.166, 95% CI = 1.037-1.311, P= 0.010). In subgroup analysis according to p53 mutation status, and gender, no any significant association was detected. CONCLUSIONS The present meta-analysis suggests that the MDM2 is a candidate gene for CRC susceptibility. The MDM2 SNP309 polymorphism may be a risk factor for CRC in Asians.
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Affiliation(s)
- Xue Qin
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Qiliu Peng
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Weizhong Tang
- Department of Anal and Colorectal Surgery, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Xianjun Lao
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Zhiping Chen
- Department of Occupational Health and Environmental Health, School of Public Health at Guangxi Medical University, Nanning, Guangxi, China
| | - Hao Lai
- Department of Gastrointestinal Surgery, Tumor Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Yan Deng
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Cuiju Mo
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Jingzhe Sui
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Junrong Wu
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Limin Zhai
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Shi Yang
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Shan Li
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
- * E-mail: (SL); (JZ)
| | - Jinmin Zhao
- Department of Orthopedic Trauma Surgery, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
- * E-mail: (SL); (JZ)
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92
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Lew QJ, Chu KL, Chia YL, Cheong N, Chao SH. HEXIM1, a New Player in the p53 Pathway. Cancers (Basel) 2013; 5:838-56. [PMID: 24202322 PMCID: PMC3795367 DOI: 10.3390/cancers5030838] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 06/24/2013] [Accepted: 06/24/2013] [Indexed: 01/10/2023] Open
Abstract
Hexamethylene bisacetamide-inducible protein 1 (HEXIM1) is best known as the inhibitor of positive transcription elongation factor b (P-TEFb), which controls transcription elongation of RNA polymerase II and Tat transactivation of human immunodeficiency virus. Besides P-TEFb, several proteins have been identified as HEXIM1 binding proteins. It is noteworthy that more than half of the HEXIM1 binding partners are involved in cancers. P53 and two key regulators of the p53 pathway, nucleophosmin (NPM) and human double minute-2 protein (HDM2), are among the factors identified. This review will focus on the functional importance of the interactions between HEXIM1 and p53/NPM/HDM2. NPM and the cytoplasmic mutant of NPM, NPMc+, were found to regulate P-TEFb activity and RNA polymerase II transcription through the interaction with HEXIM1. Importantly, more than one-third of acute myeloid leukemia (AML) patients carry NPMc+, suggesting the involvement of HEXIM1 in tumorigenesis of AML. HDM2 was found to ubiquitinate HEXIM1. The HDM2-mediated ubiquitination of HEXIM1 did not lead to protein degradation of HEXIM1 but enhanced its inhibitory activity on P-TEFb. Recently, HEXIM1 was identified as a novel positive regulator of p53. HEXIM1 prevented p53 ubiquitination by competing with HDM2 in binding to p53. Taken together, the new evidence suggests a role of HEXIM1 in regulating the p53 pathway and tumorigenesis.
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Affiliation(s)
- Qiao Jing Lew
- Expression Engineering Group, Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way, #06-01, Singapore 138668, Singapore.
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93
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Simeonova I, Jaber S, Draskovic I, Bardot B, Fang M, Bouarich-Bourimi R, Lejour V, Charbonnier L, Soudais C, Bourdon JC, Huerre M, Londono-Vallejo A, Toledo F. Mutant mice lacking the p53 C-terminal domain model telomere syndromes. Cell Rep 2013; 3:2046-58. [PMID: 23770245 DOI: 10.1016/j.celrep.2013.05.028] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 04/01/2013] [Accepted: 05/17/2013] [Indexed: 11/29/2022] Open
Abstract
Mutations in p53, although frequent in human cancers, have not been implicated in telomere-related syndromes. Here, we show that homozygous mutant mice expressing p53Δ31, a p53 lacking the C-terminal domain, exhibit increased p53 activity and suffer from aplastic anemia and pulmonary fibrosis, hallmarks of syndromes caused by short telomeres. Indeed, p53Δ31/Δ31 mice had short telomeres and other phenotypic traits associated with the telomere disease dyskeratosis congenita and its severe variant the Hoyeraal-Hreidarsson syndrome. Heterozygous p53+/Δ31 mice were only mildly affected, but decreased levels of Mdm4, a negative regulator of p53, led to a dramatic aggravation of their symptoms. Importantly, several genes involved in telomere metabolism were downregulated in p53Δ31/Δ31 cells, including Dyskerin, Rtel1, and Tinf2, which are mutated in dyskeratosis congenita, and Terf1, which is implicated in aplastic anemia. Together, these data reveal that a truncating mutation can activate p53 and that p53 plays a major role in the regulation of telomere metabolism.
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Affiliation(s)
- Iva Simeonova
- Genetics of Tumor Suppression, Institut Curie, Centre de Recherche, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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94
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S100A4 interacts with p53 in the nucleus and promotes p53 degradation. Oncogene 2013; 32:5531-40. [PMID: 23752197 DOI: 10.1038/onc.2013.213] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Revised: 03/31/2013] [Accepted: 05/03/2013] [Indexed: 11/09/2022]
Abstract
S100A4 is a small calcium-binding protein that is commonly overexpressed in a range of different tumor types, and it is widely accepted that S100A4 has an important role in the process of cancer metastasis. In vitro binding assays has shown that S100A4 interacts with the tumor suppressor protein p53, indicating that S100A4 may have additional roles in tumor development. In the present study, we show that endogenous S100A4 and p53 interact in complex samples, and that the interaction increases after inhibition of MDM2-dependent p53 degradation using Nutlin-3A. Further, using proximity ligation assay, we show that the interaction takes place in the cell nucleus. S100A4 knockdown experiments in two p53 wild-type cell lines, A549 and HeLa, resulted in stabilization of p53 protein, indicating that S100A4 is promoting p53 degradation. Finally, we demonstrate that S100A4 knockdown leads to p53-dependent cell cycle arrest and increased cisplatin-induced apoptosis. Thus, our data add a new layer to the oncogenic properties of S100A4 through its inhibition of p53-dependent processes.
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95
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Nag S, Qin J, Srivenugopal KS, Wang M, Zhang R. The MDM2-p53 pathway revisited. J Biomed Res 2013; 27:254-71. [PMID: 23885265 PMCID: PMC3721034 DOI: 10.7555/jbr.27.20130030] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 04/12/2013] [Indexed: 12/15/2022] Open
Abstract
The p53 tumor suppressor is a key transcription factor regulating cellular pathways such as DNA repair, cell cycle, apoptosis, angiogenesis, and senescence. It acts as an important defense mechanism against cancer onset and progression, and is negatively regulated by interaction with the oncoprotein MDM2. In human cancers, the TP53 gene is frequently mutated or deleted, or the wild-type p53 function is inhibited by high levels of MDM2, leading to downregulation of tumor suppressive p53 pathways. Thus, the inhibition of MDM2-p53 interaction presents an appealing therapeutic strategy for the treatment of cancer. However, recent studies have revealed the MDM2-p53 interaction to be more complex involving multiple levels of regulation by numerous cellular proteins and epigenetic mechanisms, making it imperative to reexamine this intricate interplay from a holistic viewpoint. This review aims to highlight the multifaceted network of molecules regulating the MDM2-p53 axis to better understand the pathway and exploit it for anticancer therapy.
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Affiliation(s)
- Subhasree Nag
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
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96
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Qin JJ, Nag S, Voruganti S, Wang W, Zhang R. Natural product MDM2 inhibitors: anticancer activity and mechanisms of action. Curr Med Chem 2013; 19:5705-25. [PMID: 22830335 DOI: 10.2174/092986712803988910] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Revised: 06/04/2012] [Accepted: 06/04/2012] [Indexed: 12/12/2022]
Abstract
The mdm2 oncogene has recently been suggested to be a valuable target for cancer therapy and prevention. Overexpression of mdm2 is often seen in various human cancers and correlates with high-grade, late-stage, and more treatment-resistant tumors. The MDM2-p53 auto-regulatory loop has been extensively investigated and is an attractive cancer target, which indeed has been the main focus of anti-MDM2 drug discovery. Much effort has been expended in the development of small molecule MDM2 antagonists targeting the MDM2-p53 interaction, and a few of these have advanced into clinical trials. However, MDM2 exerts its oncogenic activity through both p53-dependent and -independent mechanisms. Recently, there is an increasing interest in identifying natural MDM2 inhibitors; some of them have been shown to decrease MDM2 expression and activity in vitro and in vivo. These identified natural MDM2 inhibitors include a plethora of diverse chemical frameworks, ranging from flavonoids, steroids, and sesquiterpenes to alkaloids. In addition to a brief review of synthetic MDM2 inhibitors, this review focuses on natural product MDM2 inhibitors, summarizing their biological activities in vitro and in vivo and the underlying molecular mechanisms of action, targeting MDM2 itself, regulators of MDM2, and/or the MDM2-p53 interaction. These MDM2 inhibitors can be used alone or in combination with conventional treatments, improving the prospects for cancer therapy and prevention. Their complex and unique molecular architectures may provide a stimulus for developing synthetic analogs in the future.
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Affiliation(s)
- J-J Qin
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, 1300 S. Coulter Street, Amarillo, TX 79106, USA
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97
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Yin F, Liu X, Li D, Wang Q, Zhang W, Li L. Tumor suppressor genes associated with drug resistance in ovarian cancer (review). Oncol Rep 2013; 30:3-10. [PMID: 23660957 DOI: 10.3892/or.2013.2446] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 03/29/2013] [Indexed: 11/06/2022] Open
Abstract
Ovarian cancer is a fatal gynecological cancer and a major cause of cancer-related mortality worldwide. The main limitation to a successful treatment for ovarian cancer is the development of drug resistance to combined chemotherapy. Tumor suppressor genes (TSGs) are wild-type alleles of genes which play regulatory roles in diverse cellular activities, and whose loss of function contributes to the development of cancer. It has been demonstrated that TSGs contribute to drug resistance in several types of solid tumors. However, an overview of the contribution of TSGs to drug resistance in ovarian cancer has not previously been reported. In this study, 15 TSGs responding to drug resistance in ovarian cancer were reviewed to determine the relationship of TSGs with ovarian cancer drug resistance. Furthermore, gene/protein-interaction and bio-association analysis were performed to demonstrate the associations of these TSGs and to mine the potential drug resistance-related genes in ovarian cancer. We observed that the 15 TSGs had close interactions with each other, suggesting that they may contribute to drug resistance in ovarian cancer as a group. Five pathways/processes consisting of DNA damage, apoptosis, cell cycle, DNA binding and methylation may be the key ways with which TSGs participate in the regulation of drug resistance. In addition, ubiquitin C (UBC) and six additional TSGs including the adenomatous polyposis coli gene (APC), death associated protein kinase gene (DAPK), pleiomorphic adenoma gene-like 1 (PLAGL1), retinoblastoma susceptibility gene (RB1), a gene encoding an apoptosis-associated speck-like protein (PYCARD/ASC) and tumor protein 63 (TP63), which had close interactions with the 15 TSGs, are potential drug resistance-related genes in ovarian cancer.
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Affiliation(s)
- Fuqiang Yin
- Department of Gynecologic Oncology, Affiliated Tumor Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
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98
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van Leeuwen IMM, Higgins M, Campbell J, McCarthy AR, Sachweh MCC, Navarro AM, Laín S. Modulation of p53 C-terminal acetylation by mdm2, p14ARF, and cytoplasmic SirT2. Mol Cancer Ther 2013; 12:471-80. [PMID: 23416275 DOI: 10.1158/1535-7163.mct-12-0904] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Acetylation of C-terminal lysine residues in the p53 tumor suppressor is associated with increased stability and transcription factor activity. The function, protein level, and acetylation of p53 are downregulated by mdm2, which in its turn is inhibited by the p14(ARF) tumor suppressor. Here, we show that p14(ARF) increases the level of p53 acetylated at lysine 382 in a nuclear chromatin-rich fraction. Unexpectedly, this accumulation of p53AcK382 is dramatically enhanced in the presence of ectopic mdm2. In light of these observations, we propose that p14(ARF) increases the binding of p53-mdm2 complexes to chromatin, thereby limiting the access of protein deacetylases to p53. Supporting this notion, we show that p53AcK382 can be deacetylated in the cytoplasm and that sirtuin SirT2 catalyzes this reaction. These results help understand why inhibition of both SirT1 and SirT2 is needed to achieve effective activation of p53 by small-molecule sirtuin inhibitors.
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Affiliation(s)
- Ingeborg M M van Leeuwen
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobels väg 16, Stockholm 171 77, Sweden
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99
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Lion M, Bisio A, Tebaldi T, De Sanctis V, Menendez D, Resnick MA, Ciribilli Y, Inga A. Interaction between p53 and estradiol pathways in transcriptional responses to chemotherapeutics. Cell Cycle 2013; 12:1211-24. [PMID: 23518503 DOI: 10.4161/cc.24309] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Estrogen receptors (ERs) and p53 can interact via cis-elements to regulate the angiogenesis-related VEGFR-1 (FLT1) gene, as we reported previously. Here, we address cooperation between these transcription factors on a global scale. Human breast adenocarcinoma MCF7 cells were exposed to single or combinatorial treatments with the chemotherapeutic agent doxorubicin and the ER ligand 17β-estradiol (E2). Whole-genome transcriptome changes were measured by expression microarrays. Nearly 200 differentially expressed genes were identified that showed limited responsiveness to either doxorubicin treatment or ER ligand alone but were upregulated in a greater than additive manner following combined treatment. Based on exposure to 5-fuorouracil and nutlin-3a, the combined responses were treatment-specific. Among 16 genes chosen for validation using quantitative real-time PCR, seven (INPP5D, TLR5, KRT15, EPHA2, GDNF, NOTCH1, SOX9) were confirmed to be novel direct targets of p53, based on responses in MCF7 cells silenced for p53 or cooperative targets of p53 and ER. Promoter pattern searches and chromatin IP experiments for the INPP5D, TLR5, KRT15 genes supported direct, cis-mediated p53 and/or ER regulation through canonical and noncanonical p53 and ER response elements. Collectively, we establish that combinatorial activation of p53 and ER can induce novel gene expression programs that have implications for cell-cell communications, adhesion, cell differentiation, development and inflammatory responses as well as cancer treatments.
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Affiliation(s)
- Mattia Lion
- Laboratory of Transcriptional Networks, Centre for Integrative Biology (CIBIO), University of Trento, Mattarello, Trento, Italy
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100
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Abstract
Cancer cells often have high expression of Mdm2. However, in many cancers mdm2 is alternatively spliced, with more than 40 mRNA variants identified. Many of the alternative spliced mdm2 mRNAs have the potential to encode truncated Mdm2 isoforms. These putative Mdm2 isoforms can theoretically increase the diversity of the cancer proteome. The 3 best characterized are Mdm2-A, Mdm2-B, and Mdm2-C. As described in this review, the exogenous expression of these isoforms results in paradoxical phenotypes of transformation-associated growth as well as the inhibition of growth. Interestingly, these Mdm2 isoforms contribute tumor-promoting capacity in p53-null backgrounds. Herein we describe how alternative splicing of mdm2 may result in Mdm2 protein products that alter signal transduction to promote tumorigenesis. The tumor promoting capacity of Mdm2 isoforms is discussed in the context of functions that do not require the inhibition of p53. When N-terminal portions of Mdm2 are missing, the biochemical functions encoded by exon 12 are proposed to become more important. This may result in growth promoting functions when wild-type p53 is absent or compromised. The p53-independent tumor promoting activity of Mdm2 is proposed to result from C-terminal biochemical contributions of DNA binding, RNA binding, nucleolar localization, and nucleotide binding.
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Affiliation(s)
- Danielle R Okoro
- The City University of New York at Hunter College and the Graduate Center, New York, NY, USA
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