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Lim JH, Kim DG, Yu DY, Kang HM, Noh KH, Kim DS, Park D, Chang TK, Im DS, Jung CR. Stabilization of E2-EPF UCP protein is implicated in hepatitis B virus-associated hepatocellular carcinoma progression. Cell Mol Life Sci 2019; 76:2647-2662. [PMID: 30903204 PMCID: PMC6586911 DOI: 10.1007/s00018-019-03066-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 02/18/2019] [Accepted: 03/07/2019] [Indexed: 12/19/2022]
Abstract
Hepatitis B virus (HBV) X protein (HBx) is associated with hepatocarcinogenesis. E2-EPF ubiquitin carrier protein (UCP) catalyzes ubiquitination of itself and von Hippel-Lindau protein (pVHL) for degradation and associates with tumor growth and metastasis. However, it remains unknown whether HBx modulates the enzyme activity of UCP and thereby influences hepatocarcinogenesis. Here, we show that UCP is highly expressed in liver tissues of HBx-transgenic mice, but not non-transgenic mice. UCP was more frequently expressed in HBV-positive liver cancers than in HBV-negative liver cancers. HBx binds to UCP specifically and serotype independently, and forms a ternary complex with UCP and pVHL. HBx inhibits self-ubiquitination of UCP, but enhances UCP-mediated pVHL ubiquitination, resulting in stabilization of hypoxia-inducible factor-1α and -2α. HBx and UCP stabilize each other by mutually inhibiting their ubiquitination. HBx promotes cellular proliferation and metastasis via UCP. Our findings suggest that UCP plays a key role in HBV-related hepatocarcinogenesis.
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Affiliation(s)
- Jung Hwa Lim
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Dae-Ghon Kim
- Research Institute of Clinical Medicine, Chonbuk National University Medical School and Hospital, Jeonju, Republic of Korea
| | - Dae-Yeul Yu
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Hyun Mi Kang
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Kyung Hee Noh
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Dae-Soo Kim
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Dongmin Park
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Tae Kyung Chang
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Dong-Soo Im
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.
| | - Cho-Rok Jung
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.
- University of Science and Technology, Daejeon, Republic of Korea.
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2
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Chen DG, Zhu B, Lv SQ, Zhu H, Tang J, Huang C, Li Q, Zhou P, Wang DL, Li GH. Inhibition of EGR1 inhibits glioma proliferation by targeting CCND1 promoter. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2017; 36:186. [PMID: 29246166 PMCID: PMC5732438 DOI: 10.1186/s13046-017-0656-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 11/30/2017] [Indexed: 11/10/2022]
Abstract
Background Gliomas are the most common primary tumors in central nervous system. The prognosis of the patients with glioma is poor regardless of the development of therapeutic strategies. Its aggressive behavior mainly depends on the potent ability of proliferation. The transcription factor EGR1 (early growth response 1) is a member of a zinc finger transcription factor family which plays an essential role in cell growth and proliferation. Methods EGR1 expression levels in 39 glioma tissues and 10 normal brain tissues were tested by RT-qPCR and Western-blotting. The effects of EGR1 on U251 cells, U251 stem-like cells (GSCs), and U87 cells proliferation were assessed using in vitro and in vivo cell proliferation assays. The specific binding between EGR1 and CCND1 promoter was confirmed by CHIP assay. EGF was used to improve EGR1 expression in this assay. Results EGR1 expression levels in human gliomas are decreased compared with normal brain tissues, however, the patients with low EGR1 expression level showed significantly enhanced patient survival in all glioma patients. EGR1 silencing inhibited proliferation and induced G1 phase arrest in glioma cells. EGR1 contributed to proliferation by directly raising CCND1. Meanwhile, EGR1 overexpression induced by EGF was able to promote the proliferation of glioma cells. Conclusions Our results show that stable knockdown EGR1 would inhibit glioma proliferation. The results suggest EGR1 showing lower expression in cancer tissues compared with normal tissues maybe still play an important role in tumor proliferation. Electronic supplementary material The online version of this article (10.1186/s13046-017-0656-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dian-Gang Chen
- Institute for Cancer Research in People's Liberation Army, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Bo Zhu
- Institute for Cancer Research in People's Liberation Army, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Sheng-Qing Lv
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Hongfan Zhu
- Institute for Cancer Research in People's Liberation Army, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Jinliang Tang
- Department of Pathology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Changlin Huang
- Institute for Cancer Research in People's Liberation Army, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Qingrui Li
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Pu Zhou
- Institute for Cancer Research in People's Liberation Army, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Dong-Lin Wang
- Department of Oncology, Cancer Hospital of Chongqing City, Chongqing, 400037, China
| | - Guang-Hui Li
- Institute for Cancer Research in People's Liberation Army, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China.
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Zhang X, Zhao F, Zhang S, Song Y. Ectopic High Expression of E2-EPF Ubiquitin Carrier Protein Indicates a More Unfavorable Prognosis in Brain Glioma. Genet Test Mol Biomarkers 2017; 21:242-247. [PMID: 28384045 DOI: 10.1089/gtmb.2016.0281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Xiaohui Zhang
- Pathology Department, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Fangbo Zhao
- School of Material Science and Chemical Engineering, Harbin Engineering University, Harbin, China
| | - Shujun Zhang
- Pathology Department, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yichun Song
- Pathology Department, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China
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4
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Zhang X, Liu Q, Zhao F, Guo D. WITHDRAWN: Production of a novel UBE2S anti-body and significance of its expression in some tumors. Pathol Res Pract 2014:S0344-0338(14)00383-5. [PMID: 25613697 DOI: 10.1016/j.prp.2014.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/22/2014] [Indexed: 10/24/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Affiliation(s)
- Xiaohui Zhang
- Pathology Department, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, Heilongjiang 150001, China.
| | - Qinfang Liu
- Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, Heilongjiang 150001, China
| | - Fangbo Zhao
- Key Laboratory of Superlight Material and Surface Modification, Ministry of Education, Harbin Engineering University, Harbin, Heilongjiang 150090, China.
| | - Dongwei Guo
- Harbin Biotechnology Incubators Management Co. Ltd, Harbin, Heilongjiang 150001, China
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Deacon K, Onion D, Kumari R, Watson SA, Knox AJ. Elevated SP-1 transcription factor expression and activity drives basal and hypoxia-induced vascular endothelial growth factor (VEGF) expression in non-small cell lung cancer. J Biol Chem 2012; 287:39967-81. [PMID: 22992725 PMCID: PMC3501049 DOI: 10.1074/jbc.m112.397042] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
VEGF plays a central role in angiogenesis in cancer. Non-small cell lung cancer (NSCLC) tumors have increased microvascular density, localized hypoxia, and high VEGF expression levels; however, there is a lack of understanding of how oncogenic and tumor microenvironment changes such as hypoxia lead to greater VEGF expression in lung and other cancers. We show that NSCLC cells secreted higher levels of VEGF than normal airway epithelial cells. Actinomycin D inhibited all NSCLC VEGF secretion, and VEGF minimal promoter-luciferase reporter constructs were constitutively active until the last 85 base pairs before the transcription start site containing three SP-1 transcription factor-binding sites; mutation of these VEGF promoter SP-1-binding sites eliminated VEGF promoter activity. Furthermore, dominant negative SP-1, mithramycin A, and SP-1 shRNA decreased VEGF promoter activity, whereas overexpression of SP-1 increased VEGF promoter activity. Chromatin immunoprecipitation assays demonstrated SP-1, p300, and PCA/F histone acetyltransferase binding and histone H4 hyperacetylation at the VEGF promoter in NSCLC cells. Cultured NSCLC cells expressed higher levels of SP-1 protein than normal airway epithelial cells, and double-fluorescence immunohistochemistry showed a strong correlation between SP-1 and VEGF in human NSCLC tumors. In addition, hypoxia-driven VEGF expression in NSCLC cells was SP-1-dependent, with hypoxia increasing SP-1 activity and binding to the VEGF promoter. These studies are the first to demonstrate that overexpression of SP-1 plays a central role in hypoxia-induced VEGF secretion.
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Affiliation(s)
- Karl Deacon
- Centre for Respiratory Research, University of Nottingham, Nottingham, NG5 1PB, United Kingdom.
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Banning A, Ockenga W, Finger F, Siebrasse P, Tikkanen R. Transcriptional regulation of flotillins by the extracellularly regulated kinases and retinoid X receptor complexes. PLoS One 2012; 7:e45514. [PMID: 23029064 PMCID: PMC3445523 DOI: 10.1371/journal.pone.0045514] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 08/21/2012] [Indexed: 11/25/2022] Open
Abstract
Flotillin-1 and flotillin-2 are important regulators of signal transduction pathways such as growth factor signaling. Flotillin expression is increased under pathological conditions such as neurodegenerative disorders and cancer. Despite their importance for signal transduction, very little is known about the transcriptional regulation of flotillins. Here, we analyzed the expression of flotillins at transcriptional level and identified flotillins as downstream targets of the mitogen activated kinases ERK1/2. The promoter activity of flotillins was increased upon growth factor stimulation in a MAPK dependent manner. Overexpression of serum response factor or early growth response gene 1 resulted in increased flotillin mRNA and protein expression. Furthermore, both promoter activity and expression of endogenous flotillins were increased upon treatment with retinoic acid or by overexpression of the retinoid X receptor and its binding partners RARα and PPARγ. Our data indicate that the expression of flotillins, which can be detected in all cultured cells, is fine-tuned in response to various external stimuli. This regulation may be critical for the outcome of signaling cascades in which flotillins are known to be involved.
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Affiliation(s)
- Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
| | - Wymke Ockenga
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
| | - Fabian Finger
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
| | - Philipp Siebrasse
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen, Germany
- * E-mail:
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7
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LIANG JING, NISHI HIROTAKA, BIAN MEILU, HIGUMA CHINATSU, SASAKI TORU, ITO HIROE, ISAKA KEIICHI. The ubiquitin-conjugating enzyme E2-EPF is overexpressed in cervical cancer and associates with tumor growth. Oncol Rep 2012; 28:1519-25. [DOI: 10.3892/or.2012.1949] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 07/11/2012] [Indexed: 11/05/2022] Open
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8
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Lim JH, Shin HJ, Park KS, Lee CH, Jung CR, Im DS. Adenovirus-mediated E2-EPF UCP gene transfer prevents autoamputation in a mouse model of hindlimb ischemia. Mol Ther 2012; 20:778-87. [PMID: 22294149 PMCID: PMC3321605 DOI: 10.1038/mt.2011.302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 12/18/2011] [Indexed: 12/13/2022] Open
Abstract
E2-EPF ubiquitin carrier protein (UCP) stabilizes hypoxia-inducible factor-1α (HIF-1α) inducing ischemic vascular responses. Here, we investigated the effect of UCP gene transfer on therapeutic angiogenesis. Adenovirus-encoded UCP (Ad-F-UCP) increased the expression of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) in cells and mice. Conditioned media from UCP-overexpressing cells promoted proliferation, tubule formation, and invasion of human umbilical-vascular-endothelial cells (HUVECs), and vascularization in chorioallantoic membrane (CAM) assay. Ad-F-UCP increased the vessel density in the Martigel plug assay, and generated copious vessel-like structures in the explanted muscle. The UCP effect on angiogenesis was dependent on VEGF and FGF-2. In mouse hindlimb ischemia model (N = 30/group), autoamputation (limb loss) occurred in 87% and 68% of the mice with saline and Ad encoding β-galactosidase (Ad-LacZ), respectively, whereas only 23% of the mice injected with Ad-F-UCP showed autoamputation after 21 days of treatment. Ad-F-UCP increased protein levels of HIF-1α, platelet-endothelial cell adhesion molecule-1 (PECAM-1), smooth muscle cell actin (SMA) in the ischemic muscle, and augmented blood vessels doubly positive for PECAM-1 and SMA. Consequently, UCP gene transfer prevented muscle degeneration and autoamputation of ischemic limb. The results suggest that E2-EPF UCP may be a target for therapeutic angiogenesis.
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Affiliation(s)
- Jung Hwa Lim
- Gene Therapy Research Unit, KRIBB, Daejeon, Republic of Korea
| | - Hyo Jung Shin
- Gene Therapy Research Unit, KRIBB, Daejeon, Republic of Korea
| | - Kyeong-Su Park
- Gene Therapy Research Unit, KRIBB, Daejeon, Republic of Korea
- University of Science and Technology, Daejeon, Republic of Korea
| | - Chan Hee Lee
- Department of Microbiology, Chungbuk National University, Chungbuk, Republic of Korea
| | - Cho-Rok Jung
- Gene Therapy Research Unit, KRIBB, Daejeon, Republic of Korea
- University of Science and Technology, Daejeon, Republic of Korea
| | - Dong-Soo Im
- Gene Therapy Research Unit, KRIBB, Daejeon, Republic of Korea
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9
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Roos FC, Evans AJ, Brenner W, Wondergem B, Klomp J, Heir P, Roche O, Thomas C, Schimmel H, Furge KA, Teh BT, Thüroff JW, Hampel C, Ohh M. Deregulation of E2-EPF ubiquitin carrier protein in papillary renal cell carcinoma. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 178:853-60. [PMID: 21281817 DOI: 10.1016/j.ajpath.2010.10.033] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 09/01/2010] [Accepted: 10/13/2010] [Indexed: 01/29/2023]
Abstract
Molecular pathways associated with pathogenesis of sporadic papillary renal cell carcinoma (PRCC), the second most common form of kidney cancer, are poorly understood. We analyzed primary tumor specimens from 35 PRCC patients treated by nephrectomy via gene expression analysis and tissue microarrays constructed from an additional 57 paraffin-embedded PRCC samples via immunohistochemistry. Gene products were validated and further studied by Western blot analyses using primary PRCC tumor samples and established renal cell carcinoma cell lines, and potential associations with pathologic variables and survival in 27 patients with follow-up information were determined. We show that the expression of E2-EPF ubiquitin carrier protein, which targets the principal negative regulator of hypoxia-inducible factor (HIF), von Hippel-Lindau protein, for proteasome-dependent degradation, is markedly elevated in the majority of PRCC tumors exhibiting increased HIF1α expression, and is associated with poor prognosis. In addition, we identified multiple hypoxia-responsive elements within the E2-EPF promoter, and for the first time we demonstrated that E2-EPF is a hypoxia-inducible gene directly regulated via HIF1. These findings reveal deregulation of the oxygen-sensing pathway impinging on the positive feedback mechanism of HIF1-mediated regulation of E2-EPF in PRCC.
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Affiliation(s)
- Frederik C Roos
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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10
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Ritchie MF, Zhou Y, Soboloff J. Transcriptional mechanisms regulating Ca(2+) homeostasis. Cell Calcium 2010; 49:314-21. [PMID: 21074851 DOI: 10.1016/j.ceca.2010.10.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Revised: 09/29/2010] [Accepted: 10/01/2010] [Indexed: 01/08/2023]
Abstract
Ca(2+) is a dynamic cellular secondary messenger which mediates a vast array of cellular responses. Control over these processes is achieved via an extensive combination of pumps and channels which regulate the concentration of Ca(2+) within not only the cytosol but also all intracellular compartments. Precisely how these pumps and channels are regulated is only partially understood, however, recent investigations have identified members of the Early Growth Response (EGR) family of zinc finger transcription factors as critical players in this process. The roles of several other transcription factors in control of Ca(2+) homeostasis have also been demonstrated, including Wilms Tumor Suppressor 1 (WT1), Nuclear Factor of Activated T cells (NFAT) and c-myc. In this review, we will discuss not only how these transcription factors regulate the expression of the major proteins involved in control of Ca(2+) homeostasis, but also how this transcriptional remodeling of Ca(2+) homeostasis affects Ca(2+) dynamics and cellular responses.
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Affiliation(s)
- Michael F Ritchie
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140, United States
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11
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Jung CR, Lim JH, Choi Y, Kim DG, Kang KJ, Noh SM, Im DS. Enigma negatively regulates p53 through MDM2 and promotes tumor cell survival in mice. J Clin Invest 2010; 120:4493-506. [PMID: 21060154 DOI: 10.1172/jci42674] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 09/22/2010] [Indexed: 12/29/2022] Open
Abstract
The human E3 ubiquitin ligase murine double minute 2 (MDM2) targets the tumor suppressor p53 for ubiquitination and degradation but also promotes its own ubiquitination and subsequent degradation. As the balance between MDM2 and p53 levels plays a crucial role in regulating cell proliferation and apoptosis, we sought to identify factors selectively inhibiting MDM2 self-ubiquitination. Here we have shown that the LIM domain protein Enigma directly interacts with MDM2 to form a ternary complex with p53 in vitro and in human hepatoma and colon carcinoma cell lines and mouse embryonic fibroblasts. We found that Enigma elicited p53 degradation by inhibiting MDM2 self-ubiquitination and increasing its ubiquitin ligase activity toward p53 in cells. Moreover, mitogenic stimuli such as serum, FGF, and HGF increased Enigma transcription via induction of serum response factor (SRF), leading to MDM2 stabilization and subsequent p53 degradation. We observed similar results in the livers of mice treated with HGF. In humans, we found SRF and Enigma coexpressed with MDM2 but not p53 in several liver and stomach tumors. Finally, we showed that Enigma promoted cell survival and chemoresistance by suppressing p53-mediated apoptosis in both cell lines and a mouse xenograft model. Our findings suggest a role for Enigma in tumorigenesis and uncover a mechanism whereby mitogens attenuate p53 antiproliferative activity through an SRF/Enigma/MDM2 pathway.
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Affiliation(s)
- Cho-Rok Jung
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
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12
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Kong B, Michalski CW, Hong X, Valkovskaya N, Rieder S, Abiatari I, Streit S, Erkan M, Esposito I, Friess H, Kleeff J. AZGP1 is a tumor suppressor in pancreatic cancer inducing mesenchymal-to-epithelial transdifferentiation by inhibiting TGF-β-mediated ERK signaling. Oncogene 2010; 29:5146-58. [PMID: 20581862 DOI: 10.1038/onc.2010.258] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Epithelial-to-mesenchymal transdifferentiation (EMT) mediated by transforming growth factor-β (TGF-β) signaling leads to aggressive cancer progression. In this study, we identified zinc-α2-glycoprotein (AZGP1, ZAG) as a tumor suppressor in pancreatic ductal adenocarcinoma whose expression is lost due to histone deacetylation. In vitro, ZAG silencing strikingly increased invasiveness of pancreatic cancer cells accompanied by the induction of a mesenchymal phenotype. Expression analysis of a set of EMT markers showed an increase in the expression of mesenchymal markers (vimentin (VIM) and integrin-α5) and a concomitant reduction in the expression of epithelial markers (cadherin 1 (CDH1), desmoplakin and keratin-19). Blockade of endogenous TGF-β signaling inhibited these morphological changes and the downregulation of CDH1, as elicited by ZAG silencing. In a ZAG-negative cell line, human recombinant ZAG (rZAG) specifically inhibited exogenous TGF-β-mediated tumor cell invasion and VIM expression. Furthermore, rZAG blocked TGF-β-mediated ERK2 phosphorylation. PCR array analysis revealed that ZAG-induced epithelial transdifferentiation was accompanied by a series of concerted cellular events including a shift in the energy metabolism and prosurvival signals. Thus, epigenetically regulated ZAG is a novel tumor suppressor essential for maintaining an epithelial phenotype.
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Affiliation(s)
- B Kong
- Department of Surgery, Technische Universität München, Munich, Germany
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