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Zhao G, Liu C, Wen X, Luan G, Xie L, Guo X. The translational values of TRIM family in pan-cancers: From functions and mechanisms to clinics. Pharmacol Ther 2021; 227:107881. [PMID: 33930453 DOI: 10.1016/j.pharmthera.2021.107881] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 04/21/2021] [Accepted: 04/22/2021] [Indexed: 02/08/2023]
Abstract
Cancer is the second leading cause of human death across the world. Tripartite motif (TRIM) family, with E3 ubiquitin ligase activities in majority of its members, is reported to be involved in multiple cellular processes and signaling pathways. TRIM proteins have critical effects in the regulation of biological behaviors of cancer cells. Here, we discussed the current understanding of the molecular mechanism of TRIM proteins regulation of cancer cells. We also comprehensively reviewed published studies on TRIM family members as oncogenes or tumor suppressors in the oncogenesis, development, and progression of a variety of types of human cancers. Finally, we highlighted that certain TRIM family members are potential molecular biomarkers for cancer diagnosis and prognosis, and potential therapeutic targets.
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Affiliation(s)
- Guo Zhao
- Department of Preventive Medicine, Institute of Biomedical Informatics, Bioinformatics Center, Henan Provincial Engineering Center for Tumor Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Chuan Liu
- Department of Preventive Medicine, Institute of Biomedical Informatics, Bioinformatics Center, Henan Provincial Engineering Center for Tumor Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Xin Wen
- Department of Preventive Medicine, Institute of Biomedical Informatics, Bioinformatics Center, Henan Provincial Engineering Center for Tumor Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Gan Luan
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Longxiang Xie
- Department of Preventive Medicine, Institute of Biomedical Informatics, Bioinformatics Center, Henan Provincial Engineering Center for Tumor Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China.
| | - Xiangqian Guo
- Department of Preventive Medicine, Institute of Biomedical Informatics, Bioinformatics Center, Henan Provincial Engineering Center for Tumor Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China.
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Alhazmi N, Pai CP, Albaqami A, Wang H, Zhao X, Chen M, Hu P, Guo S, Starost K, Hajihassani O, Miyagi M, Kao HY. The promyelocytic leukemia protein isoform PML1 is an oncoprotein and a direct target of the antioxidant sulforaphane (SFN). BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2020; 1867:118707. [PMID: 32243901 DOI: 10.1016/j.bbamcr.2020.118707] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 03/18/2020] [Accepted: 03/21/2020] [Indexed: 01/30/2023]
Abstract
The gene encoding promyelocytic leukemia protein (PML) generates several spliced isoforms. Ectopic expression of PML1 promotes the proliferation of ERα-positive MCF-7 breast cancer (BC) cells, while a loss of PML by knockdown or overexpression of PML4 does the opposite. PML is an essential constituent of highly dynamic particles called PML nuclear bodies (NBs). PML NBs are heterogenous multiprotein subnuclear structures that are part of cellular stress sensing machinery. The antioxidant sulforaphane (SFN) inhibits the proliferation of BC cells and causes a redistribution of the subcellular localization of PML, a disruption of disulfide-bond linkages in nuclear PML-containing complexes, and a reduction in the number and size of PML NBs. Mechanistically, SFN modifies several cysteine residues, including C204, located in the RBCC domain of PML. PML is sumoylated and contains a Sumo-interacting motif, and a significant fraction of Sumo1 and Sumo2/3 co-localizes with PML NBs. Ectopic expression of the mutant C204A selectively inhibits the biogenesis of endogenous PML NBs but not PML-less Sumo1-, Sumo2/3, or Daxx-containing nuclear speckles. Importantly, PML1 (C204A) functions as a dominant-negative mutant over endogenous PML protein and promotes anti-proliferation activity. Together, we conclude that SFN elicits its cytotoxic activity in part by inactivating PML1's pro-tumorigenic activity.
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Affiliation(s)
- Nada Alhazmi
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Chun-Peng Pai
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Aljawharah Albaqami
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Han Wang
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Xuan Zhao
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Minyue Chen
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Po Hu
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Shuang Guo
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Kyle Starost
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Omid Hajihassani
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Masaru Miyagi
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Hung-Ying Kao
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH 44106, USA; The Comprehensive Cancer Center of CWRU, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
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Sachini N, Arampatzi P, Klonizakis A, Nikolaou C, Makatounakis T, Lam EWF, Kretsovali A, Papamatheakis J. Promyelocytic leukemia protein (PML) controls breast cancer cell proliferation by modulating Forkhead transcription factors. Mol Oncol 2019; 13:1369-1387. [PMID: 30927552 PMCID: PMC6547613 DOI: 10.1002/1878-0261.12486] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 01/17/2019] [Accepted: 03/29/2019] [Indexed: 12/27/2022] Open
Abstract
The multitasking promyelocytic leukemia (PML) protein was originally recognized as a tumor‐suppressive factor, but more recent evidence has implicated PML in tumor cell prosurvival actions and poor patient prognosis in specific cancer settings. Here, we report that inducible PMLIV expression inhibits cell proliferation as well as self‐renewal and impairs cell cycle progression of breast cancer cell lines in a reversible manner. Transcriptomic profiling identified a large number of PML‐deregulated genes associated with various cell processes. Among them, cell cycle‐ and division‐related genes and their cognitive regulators are highly ranked. In this study, we focused on previously unknown PML targets, namely the Forkhead transcription factors. PML suppresses the Forkhead box subclass M1 (FOXM1) transcription factor at both the RNA and protein levels, along with many of its gene targets. We show that FOXM1 interacts with PMLIV primarily via its DNA‐binding domain and dynamically colocalizes in PML nuclear bodies. In parallel, PML modulates the activity of Forkhead box O3 (FOXO3), a factor opposing certain FOXM1 activities, to promote cell survival and stress resistance. Thus, PMLIV affects the balance of FOXO3 and FOXM1 transcriptional programs by acting on discrete gene subsets to favor both growth inhibition and survival. Interestingly, PMLIV‐specific knockdown mimicked ectopic expression vis‐à‐vis loss of proliferative ability and self‐renewal, but also led to loss of survival ability as shown by increased apoptosis. We propose that divergent or similar effects on cell physiology may be elicited by high or low PMLIV levels dictated by other concurrent genetic or epigenetic cancer cell states that may additionally account for its disparate effects in various cancer types.
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Affiliation(s)
- Nikoleta Sachini
- Department of Biology, University of Crete, Heraklion, Greece.,Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas (FORTH), Heraklion, Greece.,Department of Surgery and Cancer, Imperial College London, UK
| | - Panagiota Arampatzi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas (FORTH), Heraklion, Greece
| | | | | | - Takis Makatounakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas (FORTH), Heraklion, Greece
| | - Eric W-F Lam
- Department of Surgery and Cancer, Imperial College London, UK
| | - Androniki Kretsovali
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas (FORTH), Heraklion, Greece
| | - Joseph Papamatheakis
- Department of Biology, University of Crete, Heraklion, Greece.,Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas (FORTH), Heraklion, Greece
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Chen X, Wu QS, Meng FC, Tang ZH, Chen X, Lin LG, Chen P, Qiang WA, Wang YT, Zhang QW, Lu JJ. Chikusetsusaponin IVa methyl ester induces G1 cell cycle arrest, triggers apoptosis and inhibits migration and invasion in ovarian cancer cells. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2016; 23:1555-1565. [PMID: 27823619 DOI: 10.1016/j.phymed.2016.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/20/2016] [Accepted: 09/04/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Panacis Japonici Rhizoma (PJR) is one of the most famous Chinese medical herbs that is known for exhibiting potential anti-cancer effects. PURPOSE This study aims to isolate and investigate the anti-cancer potential of saponins from PJR in ovarian cancer cells. METHODS The compounds were separated by comprehensive chromatographic methods. By comparison of the 1H- and 13C NMR data, as well as the HR-ESI-MS data, with the corresponding references, the structures of compounds were determined. MTT assay was performed to evaluate cell viability, along with flow cytometry for cell cycle analysis. JC-1 staining, Annexin V-PI double staining as well as Hoechst 33; 342 staining were used for detecting cell apoptosis. Western blot analysis was conducted to determine the relative protein level. Transwell assays were performed to investigate the effect of the saponin on cell migration and invasion and zymography experiments were used to detect the enzymatic activities. RESULTS Eleven saponins were isolated from PJR and their anti-proliferative effects were evaluated in human ovarian cancer cells. Chikusetsusaponin IVa methyl ester (1) exhibited the highest anti-proliferative potential among these isolates with the IC50 values at less than 10 µM in both ovarian cancer A2780 and HEY cell lines. Compound 1 induced G1 cell cycle arrest accompanied with an S phase decrease, and down-regulated the expression of cyclin D1, CDK2, and CDK6. Further study showed that compound 1 effectively decreased the cell mitochondrial membrane potential, increased the annexin V positive cells and nuclear chromatin condensation, as well as enhanced the expression of cleaved PARP, Bax and cleaved-caspase 3 while decreasing that of Bcl-2. Moreover, compound 1 suppressed the migration and invasion of HEY and A2780 cells, down-regulated the expression of Cdc42, Rac, RohA, MMP2 and MMP9, and decreased the enzymatic activities of MMP2 and MMP9. CONCLUSION These results provide a comprehensive evaluation of compound 1 as a potential agent for the treatment of ovarian cancer.
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Affiliation(s)
- Xin Chen
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Qiu-Shuang Wu
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Fan-Cheng Meng
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Zheng-Hai Tang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Xiuping Chen
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Li-Gen Lin
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Ping Chen
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| | - Wen-An Qiang
- Department of Obstetrics and Gynecology-Division of Reproductive Science in Medicine, Department of Pathology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Yi-Tao Wang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Qing-Wen Zhang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
| | - Jin-Jian Lu
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
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TRIMming p53's anticancer activity. Oncogene 2016; 35:5577-5584. [PMID: 26898759 DOI: 10.1038/onc.2016.33] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 01/11/2016] [Accepted: 01/12/2016] [Indexed: 12/11/2022]
Abstract
Several TRIM proteins control abundance and activity of p53. Along this route, TRIM proteins have a serious impact on carcinogenesis and prognosis for cancer patients. In the past years, a significant increase has been made in our understanding of how the TRIM protein family controls p53 activity.
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ATP directed agent, 8-chloro-adenosine, induces AMP activated protein kinase activity, leading to autophagic cell death in breast cancer cells. J Hematol Oncol 2014; 7:23. [PMID: 24628795 PMCID: PMC4007639 DOI: 10.1186/1756-8722-7-23] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 03/11/2014] [Indexed: 12/25/2022] Open
Abstract
Background 8-chloro-adenosine (8-Cl-Ado) is a unique ribonucleoside analog which is currently in a phase I clinical trial for hematological malignancies. Previously, we demonstrated in breast cancer cells that a 3-day treatment with 10 μM 8-Cl-Ado causes a 90% loss of clonogenic survival. In contrast, there was only a modest induction of apoptosis under these conditions, suggesting an alternative mechanism for the tumoricidal activity of 8-Cl-Ado. Methods Cellular metabolism, AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathway signaling, as well as autophagy induction was evaluated in breast cancer cell lines treated with 8-Cl-Ado. The effects of knocking down essential autophagy factors with small interfering RNA on 8-Cl-Ado-inhibited cell survival was assessed in breast cancer cells by examining apoptosis induction and clonogenic survival. In vivo efficacy of 8-Cl-Ado was measured in two breast cancer orthotopic model systems. Results We demonstrate that in breast cancer cell lines, the metabolism of 8-Cl-Ado results in depletion of endogenous ATP that subsequently induces the phosphorylation and activation of the energy sensor, AMPK. This was associated with an attenuation of mTOR signaling and an induction of the phosphorylation of the autophagy factor, Unc51-like kinase 1 on Ser555. 8-Cl-Ado-mediated induction of autophagy was evident by increased aggregates of microtubule-associated protein 1 light chain 3B (LC3B) which was associated with its conversion to its lipidated form, LC3B-II, p62 degradative flux, and increased formation of acidic vesicular organelles. Additionally, transfection of MCF-7 cells with siRNA to ATG7 or beclin 1 provided partial protection of the cells to 8-Cl-Ado cytotoxicity as measured by clonogenicity. In vivo, 8-Cl-Ado inhibited growth of both MCF-7 and BT-474 xenograft tumors. Moreover, in 9 of 22 BT-474 tumors treated with 100 mg/kg/day 3 times a week, there was an absence of macroscopically detectable tumor after 3 weeks of treatment. Conclusions Our data demonstrates that 8-Cl-Ado treatment activates the AMPK pathway leading to autophagy induction of in breast cancer cells, eliciting, in part, its tumoricidal effects. Additionally, 8-Cl-Ado effectively inhibited in vivo tumor growth in mice. Based on this biological activity, we are planning to test 8-Cl-Ado in the clinic for patients with breast cancer.
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Talluri S, Dick FA. The retinoblastoma protein and PML collaborate to organize heterochromatin and silence E2F-responsive genes during senescence. Cell Cycle 2013; 13:641-51. [PMID: 24351540 DOI: 10.4161/cc.27527] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cellular senescence is characterized by silencing of genes involved in DNA replication and cell cycle progression. Stable repression is crucial for preventing inappropriate DNA synthesis and the maintenance of a prolonged senescent state. Many of these genes are targets for E2F transcription factors. The pRB pathway plays a major role in senescence by directly repressing E2Fs and also by regulating chromatin at the promoters of E2F target genes using its LXCXE cleft-dependent interactions. In this study, we sought to investigate the mechanisms by which pRB stably silences E2F target gene transcription during cellular senescence. We report that in mouse embryonic fibroblasts, endogenous promyelocytic leukemia protein (PML) associates with E2F target genes in a pRB LXCXE-dependent manner during HrasV12-induced senescence. Furthermore, using a PML-IV-induced senescence model, we show that the pRB LXCXE binding cleft is essential for PML association with gene promoters, silencing of E2F target genes, and stable cell cycle exit. Binding assays show that pRB can interact with PML specifically during senescence, suggesting that signaling events in senescence regulate assembly of PML and pRB to establish heterochromatin and create a permanent cell cycle arrest.
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Affiliation(s)
- Srikanth Talluri
- London Regional Cancer Program; Western University; London, Ontario, Canada; Department of Biochemistry; Western University; London, Ontario, Canada
| | - Frederick A Dick
- London Regional Cancer Program; Western University; London, Ontario, Canada; Department of Biochemistry; Western University; London, Ontario, Canada; Children's Health Research Institute; Western University; London, Ontario, Canada
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Acquaah-Mensah GK, Malhotra D, Vulimiri M, McDermott JE, Biswal S. Suppressed expression of T-box transcription factors is involved in senescence in chronic obstructive pulmonary disease. PLoS Comput Biol 2012; 8:e1002597. [PMID: 22829758 PMCID: PMC3400575 DOI: 10.1371/journal.pcbi.1002597] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 05/02/2012] [Indexed: 01/13/2023] Open
Abstract
Chronic obstructive pulmonary disease (COPD) is a major global health problem. The etiology of COPD has been associated with apoptosis, oxidative stress, and inflammation. However, understanding of the molecular interactions that modulate COPD pathogenesis remains only partly resolved. We conducted an exploratory study on COPD etiology to identify the key molecular participants. We used information-theoretic algorithms including Context Likelihood of Relatedness (CLR), Algorithm for the Reconstruction of Accurate Cellular Networks (ARACNE), and Inferelator. We captured direct functional associations among genes, given a compendium of gene expression profiles of human lung epithelial cells. A set of genes differentially expressed in COPD, as reported in a previous study were superposed with the resulting transcriptional regulatory networks. After factoring in the properties of the networks, an established COPD susceptibility locus and domain-domain interactions involving protein products of genes in the generated networks, several molecular candidates were predicted to be involved in the etiology of COPD. These include COL4A3, CFLAR, GULP1, PDCD1, CASP10, PAX3, BOK, HSPD1, PITX2, and PML. Furthermore, T-box (TBX) genes and cyclin-dependent kinase inhibitor 2A (CDKN2A), which are in a direct transcriptional regulatory relationship, emerged as preeminent participants in the etiology of COPD by means of senescence. Contrary to observations in neoplasms, our study reveals that the expression of genes and proteins in the lung samples from patients with COPD indicate an increased tendency towards cellular senescence. The expression of the anti-senescence mediators TBX transcription factors, chromatin modifiers histone deacetylases, and sirtuins was suppressed; while the expression of TBX-regulated cellular senescence markers such as CDKN2A, CDKN1A, and CAV1 was elevated in the peripheral lung tissue samples from patients with COPD. The critical balance between senescence and anti-senescence factors is disrupted towards senescence in COPD lungs.
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Affiliation(s)
- George K Acquaah-Mensah
- Department of Pharmaceutical Sciences, Massachusetts College of Pharmacy and Health Sciences, Worcester, Massachusetts, United States of America.
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Kim MK, Yang S, Lee KH, Um JH, Liu M, Kang H, Park SJ, Chung JH. Promyelocytic leukemia inhibits adipogenesis, and loss of promyelocytic leukemia results in fat accumulation in mice. Am J Physiol Endocrinol Metab 2011; 301:E1130-42. [PMID: 21846906 PMCID: PMC3233778 DOI: 10.1152/ajpendo.00092.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The function of the tumor suppressor promyelocytic leukemia (PML) protein is disrupted in promyelocytic leukemia. PML has been reported to function as a negative regulator of mTOR (mammalian target of rapamycin) and nuclear Akt under some conditions. mTOR and Akt pathways regulate a diverse array of pathways, including those that control insulin signaling, energy metabolism, growth, cellular survival, and lifespan. Although the PML-mTOR/Akt link suggests that PML may have metabolic functions in the whole organism, very little is known about the metabolic functions of PML. Here we report that PML(-/-) mice did not show any significant metabolic defects. There was no impairment in the mTOR/Akt or AMPK signaling in white adipose tissue, liver, or muscle. However, despite having normal food intake and activity levels, PML(-/-) mice gained body weight faster and had more fat mass, particularly subcutaneous fat mass, in the diet-induced obesity model. Using in vitro adipogenesis models, we discovered that PML is a suppressor of adipogenesis. PML expression decreased during adipogenesis and was undetectable in fully differentiated adipocytes. Loss of PML increased expression of the adipogenic transcription factors CCAAT/enhancer binding protein-α and peroxisome proliferator-activated receptor-γ. We found that the Sirt1-NCor-SMRT corepressor complex, which represses pparg transcription, does not bind to the pparg promoter efficiently upon PML depletion. On the basis of these findings, we propose that PML is a negative regulator of the adipogenic transcription factors and that, in times of energy excess, PML may limit fat accumulation by suppressing the differentiation of preadipocytes into adipocytes.
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Affiliation(s)
- Myung K Kim
- Laboratory of Obesity and Aging Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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PML contributes to p53-independent p21 up-regulation in gamma-irradiation induced DNA damage responses. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s11434-011-4566-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Le XF, Mao W, He G, Claret FX, Xia W, Ahmed AA, Hung MC, Siddik ZH, Bast RC. The role of p27(Kip1) in dasatinib-enhanced paclitaxel cytotoxicity in human ovarian cancer cells. J Natl Cancer Inst 2011; 103:1403-22. [PMID: 21813412 DOI: 10.1093/jnci/djr280] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Less than 50% of ovarian cancers respond to paclitaxel. Effective strategies are needed to enhance paclitaxel sensitivity. METHODS A library of silencing RNAs (siRNAs) was used to identify kinases that regulate paclitaxel sensitivity in human ovarian cancer SKOv3 cells. The effect of dasatinib, an inhibitor of Src and Abl kinases, on paclitaxel sensitivity was measured in ovarian cancer cells and HEY xenografts. The roles of p27(Kip1), Bcl-2, and Cdk1 in apoptosis induced by dasatinib and paclitaxel were assessed using a terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, siRNA knockdown of gene expression, transfection with Bcl-2 and Cdk1 expression vectors, and flow cytometry. All statistical tests were two-sided. RESULTS Src family and Abl kinases were identified as modulators of paclitaxel sensitivity in SKOv3 cells. The siRNA knockdown of Src, Fyn, or Abl1 enhanced paclitaxel-mediated growth inhibition in ovarian cancer cells compared with a control siRNA. HEY cells treated with dasatinib plus paclitaxel formed fewer colonies than did cells treated with either agent alone. Treatment of HEY xenograft-bearing mice with dasatinib plus paclitaxel inhibited tumor growth more than treatment with either agent alone (average tumor volume per mouse, dasatinib + paclitaxel vs paclitaxel: 0.28 vs. 0.81 cm3, difference = 0.53 cm3, 95% confidence interval [CI] = 0.44 to 0.62 cm3, P = .014); dasatinib + paclitaxel vs. dasatinib: 0.28 vs. 0.55 cm3, difference = 0.27 cm3, 95% CI = 0.21 to 0.33 cm3, P = .035). Combined treatment induced more TUNEL-positive apoptotic cells than did either agent alone. The siRNA knockdown of p27(Kip1) decreased dasatinib- and paclitaxel-induced apoptosis compared with a negative control siRNA (sub-G1 fraction, control siRNA vs. p27(Kip1) siRNA: 42.5% vs. 20.1%, difference = 22.4%, 95% CI = 20.1% to 24.7%, P = .017). Studies with forced expression and siRNA knockdown of Bcl-2 and Cdk1 suggest that dasatinib-mediated induction of p27(Kip1) enhanced paclitaxel-induced apoptosis by negatively regulating Bcl-2 and Cdk1 expression. CONCLUSION Inhibition of Src family and Abl kinases with either siRNAs or dasatinib enhances paclitaxel sensitivity of ovarian cancer cells through p27(Kip1)-mediated suppression of Bcl-2 and Cdk1 expression.
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Affiliation(s)
- Xiao-Feng Le
- Department of Experimental Therapeutics, the University of Texas M. D. Anderson Cancer Center, Unit 354, Rm Y6.5343, 1515 Holcombe Blvd, Houston, TX, USA.
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Salomoni P, Betts-Henderson J. The role of PML in the nervous system. Mol Neurobiol 2010; 43:114-23. [PMID: 21161613 DOI: 10.1007/s12035-010-8156-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Accepted: 11/24/2010] [Indexed: 11/25/2022]
Abstract
The promyeloctic leukemia protein PML is a tumor suppressor that was originally identified due to its involvement in the (15;17) translocation of acute promyelocytic leukemia. While the majority of early research has focused upon the role of PML in the pathogenesis of leukemia, more recent evidence has identified important roles for PML in tissues outside the hemopoietic system, including the central nervous system (CNS). Here, we review recent literature on the role of PML in the CNS, with particular focus on the processes of neurodevelopment and neurodegeneration, and propose new lines of investigation.
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Affiliation(s)
- Paolo Salomoni
- Samantha Dickson Brain Cancer Unit, UCL Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6BT, UK.
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Virador VM, Flores-Obando RE, Berry A, Patel R, Zakhari J, Lo YC, Strain K, Anders J, Cataisson C, Hansen LA, Yuspa SH. The human promyelocytic leukemia protein is a tumor suppressor for murine skin carcinogenesis. Mol Carcinog 2009; 48:599-609. [PMID: 19058256 DOI: 10.1002/mc.20498] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Expression of the PMLRARalpha fusion dominant-negative oncogene in the epidermis of transgenic mice resulted in spontaneous skin tumors attributed to changes in both the PML and RAR pathways [Hansen et al., Cancer Res 2003; 63:5257-5265]. To determine the contribution of PML to skin tumor susceptibility, transgenic mice were generated on an FVB/N background, that overexpressed the human PML protein in epidermis and hair follicles under the control of the bovine keratin 5 promoter. PML was highly expressed in the epidermis and hair follicles of these mice and was also increased in cultured keratinocytes where it was confined to nuclear bodies. While an overt skin phenotype was not detected in young transgenic mice, expression of keratin 10 (K10) was increased in epidermis and hair follicles and cultured keratinocytes. As mice aged, they exhibited extensive alopecia that was accentuated on the C57BL/6J background. Following skin tumor induction with 7, 12-dimethylbenz[a]anthracene (DMBA) as initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as promoter, papilloma multiplicity and size were decreased in the transgenic mice by 35%, and the conversion of papillomas to carcinomas was delayed. Cultured transgenic keratinocytes underwent premature senescence and upregulated transcripts for p16 and Rb but not p19 and p53. Together, these changes suggest that PML participates in regulating the growth and differentiation of keratinocytes that likely influence its activity as a suppressor for tumor development.
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Affiliation(s)
- Victoria M Virador
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research. National Cancer Institute, NIH, Bethesda, Maryland 20892-4255, USA
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14
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15
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Abstract
The promyelocytic leukemia protein (PML) is a tumor suppressor identified in acute PML and implicated in the pathogenesis of a variety of tumors. PML is essential for the proper assembly of a nuclear macromolecular structure called the PML nuclear body (PML-NB). PML and PML-NBs are functionally promiscuous and have been associated with the regulation of several cellular functions. Above all these is the control of apoptosis, a function of PML whose physiological relevance is emphasized by in vivo studies that demonstrate that mice and cells lacking Pml are resistant to a vast variety of apoptotic stimuli. The function of PML in regulating apoptosis is not confined to a linear pathway; rather, PML works within a regulatory network that finely tunes various apoptotic pathways, depending on the cellular context and the apoptotic stimulus. Here, we will summarize earlier and recent advances on the molecular mechanisms by which PML regulates apoptosis and the implication of these findings for cancer pathogenesis.
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Affiliation(s)
- R Bernardi
- Cancer Genetics Program, Beth Israel Deaconess Cancer Center, Harvard Medical School, Boston, MA 02115, USA
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16
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Salomoni P, Ferguson BJ, Wyllie AH, Rich T. New insights into the role of PML in tumour suppression. Cell Res 2008; 18:622-40. [PMID: 18504460 DOI: 10.1038/cr.2008.58] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The PML gene is involved in the t(15;17) translocation of acute promyelocytic leukaemia (APL), which generates the oncogenic fusion protein PML (promyelocytic leukaemia protein)-retinoic acid receptor alpha. The PML protein localises to a subnuclear structure called the PML nuclear domain (PML-ND), of which PML is the essential structural component. In APL, PML-NDs are disrupted, thus implicating these structures in the pathogenesis of this leukaemia. Unexpectedly, recent studies indicate that PML and the PML-ND play a tumour suppressive role in several different types of human neoplasms in addition to APL. Because of PML's extreme versatility and involvement in multiple cellular pathways, understanding the mechanisms underlying its function, and therefore role in tumour suppression, has been a challenging task. In this review, we attempt to critically appraise the more recent advances in this field and propose new avenues of investigation.
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Affiliation(s)
- P Salomoni
- MRC Toxicology Unit, Lancaster Road Box 138, Leicester, LE 9HN, UK.
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17
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Borden KLB. Pondering the puzzle of PML (promyelocytic leukemia) nuclear bodies: can we fit the pieces together using an RNA regulon? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2145-54. [PMID: 18616965 DOI: 10.1016/j.bbamcr.2008.06.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 06/03/2008] [Accepted: 06/10/2008] [Indexed: 12/26/2022]
Abstract
The promyelocytic leukemia protein PML and its associated nuclear bodies are hot topics of investigation. This interest arises for multiple reasons including the tight link between the integrity of PML nuclear bodies and several disease states and the impact of the PML protein and PML nuclear bodies on proliferation, apoptosis and viral infection. Unfortunately, an understanding of the molecular underpinnings of PML nuclear body function remains elusive. Here, a general overview of the PML field is provided and is extended to discuss whether some of the basic tenets of "PML-ology" are still valid. For instance, recent findings suggest that some components of PML nuclear bodies form bodies in the absence of the PML protein. Also, a new model for PML nuclear body function is proposed which provides a unifying framework for its effects on diverse biochemical pathways such as Akt signaling and the p53-Mdm2 axis. In this model, the PML protein acts as an inhibitor of gene expression post-transcriptionally via inhibiting a network node in the eIF4E RNA regulon. An example is given for how the PML RNA regulon model provided the basis for the development of a new anti-cancer strategy being tested in the clinic.
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Affiliation(s)
- Katherine L B Borden
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell Biology, Université de Montréal, Montréal, Québec, Canada H4M 1J6.
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18
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Degradation of the tumor suppressor PML by Pin1 contributes to the cancer phenotype of breast cancer MDA-MB-231 cells. Mol Cell Biol 2007; 28:997-1006. [PMID: 18039859 DOI: 10.1128/mcb.01848-07] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Promyelocytic leukemia protein (PML) is an important regulator due to its role in numerous cellular processes including apoptosis, viral infection, senescence, DNA damage repair, and cell cycle regulation. Despite the role of PML in many cellular functions, little is known about the regulation of PML itself. We show that PML stability is regulated through interaction with the peptidyl-prolyl cis-trans isomerase Pin1. This interaction is mediated through four serine-proline motifs in the C terminus of PML. Binding to Pin1 results in degradation of PML in a phosphorylation-dependent manner. Furthermore, our data indicate that sumoylation of PML blocks the interaction, thus preventing degradation of PML by this pathway. Functionally, we show that in the MDA-MB-231 breast cancer cell line modulating levels of Pin1 affects steady-state levels of PML. Furthermore, degradation of PML due to Pin1 acts both to protect these cells from hydrogen peroxide-induced death and to increase the rate of proliferation. Taken together, our work defines a novel mechanism by which sumoylation of PML prevents Pin1-dependent degradation. This interaction likely occurs in numerous cell lines and may be a pathway for oncogenic transformation.
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19
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Son SH, Yu E, Ahn Y, Choi EK, Lee H, Choi J. Retinoic acid attenuates promyelocytic leukemia protein-induced cell death in breast cancer cells by activation of the ubiquitin–proteasome pathway. Cancer Lett 2007; 247:213-23. [PMID: 16740359 DOI: 10.1016/j.canlet.2006.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 03/28/2006] [Accepted: 04/24/2006] [Indexed: 02/07/2023]
Abstract
All-trans-retinoic acid and the tumor suppressor promyelocytic leukemia protein (PML) are potent regulators of the growth of cancer cells. This study investigates the individual and combined effects of PML, when overexpressed by the recombinant PML adenovirus, and all-trans-retinoic acid on the proliferation of human estrogen-receptor negative SKBR-3 and estrogen-receptor positive MCF-7 breast cancer cell lines. All-trans-retinoic acid caused a significant degree of cell death in SKBR-3 cells and MCF-7 cells, and PML elicited a similar incidence of or slightly more cell death in MCF-7 cells. Dual-treated cells displayed significantly less cell death than did single-treated cells in the same cell line. We concluded that PML and all-trans-retinoic acid cause cell death by different pathways: PML activates ERK1/2, p38 MAPK, and p21; arrests the cell cycle; and later causes cell death; and all-trans-retinoic acid activates proteasome function, caspase cleavage, and apoptosis. The combined use of all-trans-retinoic acid and PML gene therapy may not be the best treatment for patients with cancer, because the ubiquitinylation of PML and its subsequent proteasome-dependent degradation by retinoic acids occur before overexpressed PML exhibits tumor-suppressive activity.
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Affiliation(s)
- Se-Hee Son
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
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20
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Liu CWY, Wang RH, Berndt N. Protein phosphatase 1alpha activity prevents oncogenic transformation. Mol Carcinog 2006; 45:648-56. [PMID: 16550609 DOI: 10.1002/mc.20191] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cyclin-dependent kinase 2 (Cdk2) phosphorylates Thr320 of protein phosphatase 1alpha (PP1alpha) in late G(1), thereby inhibiting its activity. Phosphorylation-resistant PP1alphaT320A, acting as a constitutively active (CA) mutant, causes a late G(1) arrest by preventing the phosphorylation and inactivation of the retinoblastoma protein (pRb). Both PP1alpha-mediated G(1) arrest and PP1alpha phosphorylation in late G(1) require the presence of pRb, indicating that PP1alpha is a crucial regulator of the pRb pathway, which is almost invariably mutated in human cancer. These findings prompted us to investigate whether PP1alpha interferes with oncogenic transformation. The ability of NIH 3T3 cells to form foci after transformation with ras/cyclin D1 was significantly inhibited by co-transfection with PP1alphaT320A, but not PP1alpha. Likewise, cells expressing PP1alphaT320A or PP1alphaT320A fused to green fluorescent protein (GFP) were unable to form colonies in soft agar, regardless of whether PP1alpha constructs were co-transfected with ras/cyclin D1 or transfected into stably transformed cells. Overexpressed wild-type (Wt) PP1alpha and GFP-PP1alpha were phosphorylated in Thr320, most likely explaining its lack of effect. Expression of GFP-PP1alphaT320A was associated with caspase-cleaved pRb in Western blots (WB) and morphological signs of cell death. These findings demonstrate that PP1alpha activity can override oncogenic signaling by causing cell-cycle arrest and/or apoptosis rather than restoring contact inhibition or anchorage dependence.
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Affiliation(s)
- Cathy W Y Liu
- Division of Hematology/Oncology, Childrens Hospital Los Angeles, The University of Southern California Keck School of Medicine, Los Angeles, 90027, USA
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21
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Wen XF, Yang G, Mao W, Thornton A, Liu J, Bast RC, Le XF. HER2 signaling modulates the equilibrium between pro- and antiangiogenic factors via distinct pathways: implications for HER2-targeted antibody therapy. Oncogene 2006; 25:6986-96. [PMID: 16715132 DOI: 10.1038/sj.onc.1209685] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We determined the impact of HER2 signaling on two proangiogenic factors, vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8), and on an antiangiogenic factor, thrombospondin-1 (TSP-1). Re-expression of HER2 in MCF-7 and T-47D breast cancer cells that endogenously express low levels of HER2 resulted in elevated expression of VEGF and IL-8 and decreased expression of TSP-1. Inhibition of HER2 with a humanized anti-HER2 antibody (trastuzumab, or Herceptin) or a retrovirus-mediated small interfering RNA against HER2 (siHER2) decreased VEGF and IL-8 expression, but increased TSP-1 expression in BT474 breast cancer cells that express high levels of HER2. These in vitro results were further evaluated by treatment of BT474 xenografts in immunosuppressed mice with trastuzumab. Trastuzumab inhibited growth of BT474 xenografts and decreased microvascular density associated with downregulation of VEGF and IL-8 and with upregulation of TSP-1 expression. Inhibiting the PI3K-AKT pathway decreased VEGF and IL-8 expression. AKT1 overexpession increased VEGF and IL-8 expression, but did not increase TSP-1 expression. A p38 kinase inhibitor, SB203580, instead blocked TSP-1 expression and a p38 activator, MKK6, increased TSP-1 expression. Trastuzumab stimulated sustained p38 activation and SB203580 attenuated the TSP-1 upregulation induced by trastuzumab. HER2 signaling therefore influences the equilibrium between pro- and antiangiogenic factors via distinct signaling pathways. Trastuzumab inhibits angiogenesis and tumor growth, at least in part, through activation of the HER2-p38-TSP-1 pathway and inhibition of the HER2-PI3K-AKT-VEGF/IL-8 pathway.
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MESH Headings
- Animals
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal, Humanized
- Antineoplastic Agents/pharmacology
- Blotting, Western
- Female
- Humans
- Immunohistochemistry
- Interleukin-8/metabolism
- Mammary Neoplasms, Experimental/blood supply
- Mammary Neoplasms, Experimental/drug therapy
- Mammary Neoplasms, Experimental/metabolism
- Mice
- Mice, Nude
- Neovascularization, Pathologic/metabolism
- Oncogene Protein v-akt/metabolism
- Phosphatidylinositol 3-Kinases/metabolism
- Receptor, ErbB-2/antagonists & inhibitors
- Receptor, ErbB-2/immunology
- Receptor, ErbB-2/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Thrombospondin 1/metabolism
- Transfection
- Trastuzumab
- Vascular Endothelial Growth Factor A/metabolism
- p38 Mitogen-Activated Protein Kinases/drug effects
- p38 Mitogen-Activated Protein Kinases/metabolism
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Affiliation(s)
- X-F Wen
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030-4009, USA.
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22
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Iki S, Yokota SI, Okabayashi T, Yokosawa N, Nagata K, Fujii N. Serum-dependent expression of promyelocytic leukemia protein suppresses propagation of influenza virus. Virology 2005; 343:106-15. [PMID: 16154611 DOI: 10.1016/j.virol.2005.08.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 06/23/2005] [Accepted: 08/09/2005] [Indexed: 11/20/2022]
Abstract
The rate of propagation of influenza virus in human adenocarcinoma Caco-2 cells was found to negatively correlate with the concentration of fetal bovine serum (FBS) in the culture medium. Virus replicated more rapidly at lower FBS concentrations (0 or 2%) than at higher concentrations (10 or 20%) during an early stage of infection. Basal and interferon (IFN)-induced levels of typical IFN-inducible anti-viral proteins, such as 2',5'-oligoadenylate synthetase, dsRNA-activated protein kinase and MxA, were unaffected by variation in FBS concentrations. But promyelocytic leukemia protein (PML) was expressed in a serum-dependent manner. In particular, the 65 to 70 kDa isoform of PML was markedly upregulated following the addition of serum. In contrast, other isoforms were induced by IFN treatment, and weakly induced by FBS concentrations. Immunofluorescence microscopy indicated that PML was mainly formed nuclear bodies in Caco-2 cells at various FBS concentrations, and the levels of the PML-nuclear bodies were upregulated by FBS. Overexpression of PML isoform consisting of 560 or 633 amino acid residues by transfection of expression plasmid results in significantly delayed viral replication rate in Caco-2 cells. On the other hand, downregulation of PML expression by RNAi enhanced viral replication. These results indicate that PML isoforms which are expressed in a serum-dependent manner suppress the propagation of influenza virus at an early stage of infection.
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Affiliation(s)
- Shigeo Iki
- Department of Microbiology, Sapporo Medical University School of Medicine, and Hokkaido Institute of Public Health, Kita-ku, Sapporo 060-0819, Japan
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23
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Li L, He DL. Transfection of promyelocytic leukemia in retrovirus vector inhibits growth of human bladder cancer cells. Acta Pharmacol Sin 2005; 26:610-5. [PMID: 15842782 DOI: 10.1111/j.1745-7254.2005.00065.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
AIM To construct a recombinant retrovirus vector carrying human promyelocytic leukemia (PML) cDNA and identify its expression and biology role in bladder cancer UM-UC-2 cells for future gene therapy. METHODS PML full-length cDNA was inserted into the EcoR I and BamH I site of pLXSN vector containing the long terminal repeat (LTR) promoter. The vector was identified by restriction enzyme digestion and then transfected into PA317 packaging cell line by calcium phosphate coprecipitation. PML cDNA was detected by polymerase chain reaction (PCR) and the protein was identified by laser confocal microscopy and Western blot in bladder cancer cells, respectively. The morphology was observed by inverted phase contrast microscope, and MTT assay determined growth curve of the bladder cancer cells. RESULTS Restriction enzyme digestion proved that a 2.1 kb PML cDNA was inserted into the pLXSN vector. PCR assay demonstrated that 304 bp fragments were found in UM-UC-2/pLPMLSN transfects. Laser confocal microscopy showed speck dots fluorescence in the UM-UC-2/pLPMLSN nucleus. A 90 kD specific brand was found by Western blot. MTT assay demonstrated the UM-UC-2/pLPMLSN bladder cancer growth inhibition. CONCLUSION The retrovirus pLPMLSN vector was successfully constructed and could generate high effective expression of human PML in bladder cancer cell UM-UC-2, suggesting that PML recombinant retrovirus have potential utility in the gene therapy for bladder cancer.
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Affiliation(s)
- Lei Li
- Institute of Urology, First Hospital of Xi'an Jiaotong University, China
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24
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Son SH, Yu E, Choi EK, Lee H, Choi J. Promyelocytic leukemia protein-induced growth suppression and cell death in liver cancer cells. Cancer Gene Ther 2005; 12:1-11. [PMID: 15529177 DOI: 10.1038/sj.cgt.7700755] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The promyelocytic leukemia protein (PML), involved in the pathogenesis of acute promyelocytic leukemia, is a coactivator of p53 tumor suppressive functions. The ability of PML to inhibit growth and induce cell death in solid tumor cells, however, has not been determined. We therefore assayed the tumor suppressor activities of PML and compared them with those of p53 in four liver cancer cell lines. Following infection of cells with replication-deficient recombinant PML adenovirus, the exogenous PML localized in the nucleus and formed abnormally enlarged PML-nuclear bodies after 24 hours. In vitro growth curve analysis showed that the overexpressed PML initially induced a substantial G1 cell cycle arrest and triggered massive cell death in all tested cell lines, irrespective of their p53 status. PML-induced cell death decreased by about 30% in the presence of a broad caspase inhibitor, zVAD. The cell death effect of PML was higher than that induced by p53 over a longer period of time. As with p53, overexpression of PML was closely related to upregulation of p21 and decrease of cyclin D1 expression. Unexpectedly, retinoic acid (RA) antagonized rather than enhanced PML-triggered cell death. RA enhanced the expression of adenovirus-cytomegalovirus-promoted PML at both transcription and protein levels within 12 hours after treatment; however, the PML protein was significantly degraded in the presence of RA at days 3-5 postinfection. PML degradation was also observed in SK-BR3 breast cancer cells treated with RA. Taken together, our findings strongly support the hypothesis that PML acts as a strong independent cell death inducer and that RA conversely abolishes the therapeutic effects of the PML proteins through proteasomal degradation of the protein.
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Affiliation(s)
- Se-Hee Son
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
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25
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Xu ZX, Zou WX, Lin P, Chang KS. A Role for PML3 in Centrosome Duplication and Genome Stability. Mol Cell 2005; 17:721-32. [PMID: 15749021 DOI: 10.1016/j.molcel.2005.02.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Revised: 12/22/2004] [Accepted: 02/09/2005] [Indexed: 11/25/2022]
Abstract
The promyelocytic leukemia gene (PML), which is disrupted by the chromosomal translocation t(15;17) in acute promyelocytic leukemia (APL), encodes a multifunctional protein involved in several important cellular functions. Herein, we demonstrate that PML is localized to centrosomes and that PML deficiency leads to centrosome amplification. By using PML isoform-specific antibodies, we found PML3-specific association with the centrosome and the pole of the mitotic spindle. PML3 deficiency leads to dysregulation of the centrosome duplication checkpoint. Furthermore, PML3 physically interacts with Aurora A and regulates its kinase activity. Specific knockdown of PML3 activates Cdk2/cyclin kinase activity. The results of this study implicate a direct role for PML3 in the control of centrosome duplication through suppression of Aurora A activation to prevent centrosome reduplication.
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Affiliation(s)
- Zhi-Xiang Xu
- Department of Molecular Pathology, Division of Pathology and Laboratory Medicine, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA
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26
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Le XF, Lammayot A, Gold D, Lu Y, Mao W, Chang T, Patel A, Mills GB, Bast RC. Genes affecting the cell cycle, growth, maintenance, and drug sensitivity are preferentially regulated by anti-HER2 antibody through phosphatidylinositol 3-kinase-AKT signaling. J Biol Chem 2004; 280:2092-104. [PMID: 15504738 DOI: 10.1074/jbc.m403080200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular mechanisms by which the anti-HER2 antibodies trastuzumab and its murine equivalent 4D5 inhibit tumor growth and potentiate chemotherapy are not fully understood. Inhibition of signaling through the phosphatidylinositol 3-kinase (PI3K)-AKT pathway may be particularly important. Treatment of breast cancer cells that overexpress HER2 with trastuzumab inhibited HER2-HER3 association, decreased PDK1 activity, reduced Thr-308 and Ser-473 phosphorylation of AKT, and reduced AKT enzymatic activity. To place the role of PI3K-AKT in perspective, gene expression was studied by using Affymetrix microarrays and real time reverse transcription-PCR. Sixteen genes were consistently down-regulated 2.0-4.9-fold in two antibody-treated breast cancer cell lines. Fourteen of the 16 genes were involved in three major functional areas as follows: 7 in cell cycle regulation, particularly of the G(2)-M; 5 in DNA repair/replication; and 2 in modifying chromatin structure. Of the 16 antibody-regulated genes, 64% had roles in cell growth/maintenance and 52% contributed to the cell cycle. Direct inhibition of PI3K with an inhibitor markedly reduced expression of 14 genes that were also affected by the antibody. Constitutive activation of AKT1 blocked the effect of the anti-HER2 antibody on cell cycle arrest and on eight differentially expressed genes. The antibody enhanced docetaxel-induced growth inhibition but did not increase the fraction of apoptotic cells induced with docetaxel alone. In contrast, the antibody plus docetaxel markedly down-regulated two genes, HEC and DEEPEST, required for passage through G(2)-M. Thus, anti-HER2 antibody preferentially affects genes contributing to cell cycle progression and cell growth/maintenance, in part through the PI3K-AKT signaling. Transcriptional regulation by anti-HER2 antibody through PI3K-AKT pathway may potentiate the growth inhibitory activity of docetaxel by affecting cell cycle progression.
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Affiliation(s)
- Xiao-Feng Le
- Department of Experimental Therapeutics, the University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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27
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Puccetti E, Ruthardt M. Acute promyelocytic leukemia: PML/RARalpha and the leukemic stem cell. Leukemia 2004; 18:1169-75. [PMID: 15103387 DOI: 10.1038/sj.leu.2403367] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acute promyelocytic leukemia (APL) is distinguished from other acute myeloid leukemias (AMLs) by cytogenetic, clinical, as well as biological characteristics. The hallmark of APL is the t(15;17), which leads to the expression of the PML/RARalpha fusion protein. PML/RARalpha is the central leukemia-inducing lesion in APL and is directly targeted by all trans retinoic acid (t-RA) as well as by arsenic, both compounds able to induce complete remissions. This review focuses on potential stem cell involvement in APL outlining the knowledge about the APL-initiating stem cell and the influence of PML/RARalpha on the biology of the hematopoietic stem cell. Moreover, the importance of the blockage of t-RA signaling by the PML/RARalpha for the pathogenesis of APL is discussed, taking the relevance of the t-RA signaling pathway for the global hematopoiesis into account.
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Affiliation(s)
- E Puccetti
- Med. Klinik III/Abtl. Hämatologie, Labor für Experimentelle Hämatologie, Johann Wolfgang Goethe-Universität, Frankfurt, Germany
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28
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Hayakawa F, Privalsky ML. Phosphorylation of PML by mitogen-activated protein kinases plays a key role in arsenic trioxide-mediated apoptosis. Cancer Cell 2004; 5:389-401. [PMID: 15093545 DOI: 10.1016/s1535-6108(04)00082-0] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Revised: 02/05/2004] [Accepted: 03/01/2004] [Indexed: 12/13/2022]
Abstract
The promyelocytic leukemia (PML) protein is a potent growth suppressor and proapototic factor, whereas aberrant fusions of PML and retinoic acid receptor (RAR)-alpha are causal agents in human acute promyelocytic leukemia. Arsenic trioxide (As(2)O(3)) treatment induces apoptosis in acute promyelocytic leukemia cells through an incompletely understood mechanism. We report here that As(2)O(3) treatment induces phosphorylation of the PML protein through a mitogen-activated protein (MAP) kinase pathway. Increased PML phosphorylation is associated with increased sumoylation of PML and increased PML-mediated apoptosis. Conversely, MAP kinase cascade inhibitors, or the introduction of phosphorylation or sumoylation-defective mutations of PML, impair As(2)O(3)-mediated apoptosis by PML. We conclude that phosphorylation by MAP kinase cascades potentiates the antiproliferative functions of PML and helps mediate the proapoptotic effects of As(2)O(3).
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Affiliation(s)
- Fumihiko Hayakawa
- Section of Microbiology, Division of Biological Sciences, University of California at Davis, Davis, CA 95616, USA
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29
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Yang L, Yeh SD, Xie S, Altuwaijri S, Ni J, Hu YC, Chen YT, Bao BY, Su CH, Chang C. Androgen suppresses PML protein expression in prostate cancer CWR22R cells. Biochem Biophys Res Commun 2004; 314:69-75. [PMID: 14715247 DOI: 10.1016/j.bbrc.2003.12.060] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ability of PML to modulate key suppressive pathways in tumor cells suggests that PML may act as a tumor suppressor. The detailed mechanism of how PML functions in prostate cancer progression, however, remains unknown. Here we demonstrate that in the presence of androgen, PML protein expression can be suppressed in CWR22R prostate cancer cells. Further studies reveal that PML can selectively suppress AR transactivation and PML protein expression positively correlates with increased p21 protein level and enhances p53 transcription ability in CWR22R cells. We also found that PML strongly inhibits CWR22R cell colony formation, while PML siRNA enhances AR activity and CWR22R cell colony formation. Together our results suggest that PML may suppress prostate cancer cell growth by inhibiting AR transactivation and/or enhancing p53 activity.
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Affiliation(s)
- Lin Yang
- George Whipple Lab for Cancer Research, Department of Pathology, The Cancer Center, University of Rochester Medical Center, Rochester, NY 14642, USA
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30
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Xu ZX, Zhao RX, Ding T, Tran TT, Zhang W, Pandolfi PP, Chang KS. Promyelocytic leukemia protein 4 induces apoptosis by inhibition of survivin expression. J Biol Chem 2003; 279:1838-44. [PMID: 14597622 DOI: 10.1074/jbc.m310987200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The promyelocytic leukemia protein (PML) plays an essential role in multiple pathways of apoptosis. Our previous study showed that PML enhances tumor necrosis factor-induced apoptosis by inhibiting the NFkappaB survival pathway. To continue exploring the mechanism of PML-induced apoptosis, we performed a DNA microarray screening of PML target genes using a PML-inducible stable cell line. We found that Survivin was one of the downstream target genes of PML. Cotransfection experiments demonstrated that PML4 repressed transactivation of the Survivin promoter in an isoform-specific manner. Western blot analysis demonstrated that induced PML expression down-regulated Survivin. Inversely, PML knockdown by siRNA up-regulated Survivin expression. A substantial increase in Survivin expression was found in PML-deficient cells. Re-expression of PML in PML-/- mouse embryo fibroblasts down-regulated the expression of Survivin. Furthermore, cells arrested at the G2/M cell cycle phase expressed a high level of Survivin and a significantly lower level of PML. Overexpression of PML in A549 cells reduced Survivin expression leading to massive apoptotic cell death associated with activation of procaspase 9, caspase 3, and caspase 7. Together, our results demonstrate a novel mechanism of PML-induced apoptosis by down-regulation of Survivin.
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Affiliation(s)
- Zhi-Xiang Xu
- Department of Molecular Pathology and Department of Pathology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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31
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Tomasini R, Samir AA, Carrier A, Isnardon D, Cecchinelli B, Soddu S, Malissen B, Dagorn JC, Iovanna JL, Dusetti NJ. TP53INP1s and homeodomain-interacting protein kinase-2 (HIPK2) are partners in regulating p53 activity. J Biol Chem 2003; 278:37722-9. [PMID: 12851404 DOI: 10.1074/jbc.m301979200] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The TP53INP1 gene encodes two protein isoforms, TP53INP1alpha and TP53INP1beta, located into the nucleus. Their synthesis is increased during cellular stress by p53-mediated activation of transcription. Overexpression of these isoforms induces apoptosis, suggesting an involvement of TP53INP1s in p53-mediated cell death. It was recently shown that p53-dependent apoptosis is promoted by homeodomain-interacting protein kinase-2 (HIPK2), which is known to bind p53 and induce its phosphorylation in promyelocytic leukemia protein nuclear bodies (PML-NBs). In this work we show that TP53INP1s localize with p53, PML-IV, and HIPK2 into the PML-NBs. In addition, we show that TP53INP1s interact physically with HIPK2 and p53. In agreement with these results we demonstrate that TP53INP1s, in association with HIPK2, regulate p53 transcriptional activity on p21, mdm2, pig3, and bax promoters. Furthermore, TP53INP1s overexpression induces G1 arrest and increases p53-mediated apoptosis. Although a TP53INP1s and HIPK2 additive effect was observed on apoptosis, G1 arrest was weaker when HIPK2 was transfected together with TP53INP1. These results indicate that TP53INP1s and HIPK2 could be partners in regulating p53 activity.
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Affiliation(s)
- Richard Tomasini
- Centre de Recherche INSERM, EMI 0116, 163 Avenue de Luminy, BP172, Parc Scientifique et Technologique de Luminy, 13009 Marseille, France
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32
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Kim CJ, Yoon BH, Jun JK, Park JO, Cho SY, Romero R, Kim YM, Yu ES. Promyelocytic leukaemia (PML) protein expression in human placenta and choriocarcinoma. J Pathol 2003; 201:83-9. [PMID: 12950020 DOI: 10.1002/path.1382] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Promyelocytic leukaemia (PML) protein, the product of the pml gene, is heterogeneously expressed in various normal and neoplastic tissues, and the fusion of the pml gene with retinoic acid receptor-alpha is believed to be a central mechanism in acute PML tumourigenesis. As PML is important for controlling major cellular processes, such as growth and differentiation, it is believed that it plays an important role during human gestation. The human placenta is a critical organ for the maintenance of gestation, but the expression pattern and functional significance of PML in the placenta have not been documented. The present study has therefore investigated the expression of PML in the human placenta and in choriocarcinoma, and has observed the biological effects following the overexpression of PML in choriocarcinoma cell lines (BeWo and JEG-3). In the human placenta, PML expression was readily found in villous stromal fibroblasts, capillary endothelial cells, Hofbauer cells, and occasionally in amnion cells. Moreover, immunoblotting of placental lysates demonstrated increased PML expression with increasing gestation. Interestingly, PML expression was confined to intermediate trophoblasts and syncytiotrophoblastic giant cells at the placental site (placental site giant cells) in the trophoblastic cell population. Intermediate trophoblasts at non-placental sites, and villous cytotrophoblasts and syncytiotrophoblasts consistently did not express PML. Further screening of PML expression in hydatidiform moles (n = 4) and choriocarcinomas (n = 7) also revealed selective PML expression in intermediate trophoblastic cells and syncytiotrophoblastic cells, but not in the cytotrophoblastic populations, which corresponds well with observations in the placental bed. Adenoviral transduction of PML resulted in a marked reduction in cell growth in both choriocarcinoma cell lines, which was associated with increased apoptosis. The findings of the present study strongly suggest that PML plays an important role in human placental development and growth, and in the pathobiology of trophoblasts and trophoblastic neoplasia.
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Affiliation(s)
- Chong Jai Kim
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
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33
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Sun Y, Durrin LK, Krontiris TG. Specific interaction of PML bodies with the TP53 locus in Jurkat interphase nuclei. Genomics 2003; 82:250-2. [PMID: 12837275 DOI: 10.1016/s0888-7543(03)00075-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PML bodies play an important role in multiple pathways of growth control, such as transformation suppression, apoptosis, and Ras-induced senescence. However, the molecular and biological bases for these physiological phenomena are not well understood. The findings that viruses transcribe their genomes adjacent to PML bodies and that nascent RNA accumulates at their periphery have suggested that PML bodies are transcription-permissible domains. To investigate the role of PML bodies in regulation of cell transformation and apoptosis-related gene transcription, we employed the immuno-FISH method to examine the relationship between PML bodies and the TP53 and BCL2 gene loci. PML bodies were found to localize specifically with the TP53 locus in about 50% of Jurkat interphase nuclei, but never in proximity with the BCL2 locus. We speculate that PML bodies may interact directly with the TP53 DNA sequence to regulate TP53 gene expression.
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Affiliation(s)
- Yujie Sun
- Division of Molecular Medicine, Beckman Research Institute of City of Hope National Medical Center, 1500 E. Duarte Road, Duarte, CA 91010, USA
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34
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Xu ZX, Timanova-Atanasova A, Zhao RX, Chang KS. PML colocalizes with and stabilizes the DNA damage response protein TopBP1. Mol Cell Biol 2003; 23:4247-56. [PMID: 12773567 PMCID: PMC156140 DOI: 10.1128/mcb.23.12.4247-4256.2003] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2002] [Revised: 01/26/2003] [Accepted: 03/25/2003] [Indexed: 12/16/2022] Open
Abstract
The PML tumor suppressor gene is consistently disrupted by t(15;17) in patients with acute promyelocytic leukemia. Promyelocytic leukemia protein (PML) is a multifunctional protein that plays essential roles in cell growth regulation, apoptosis, transcriptional regulation, and genome stability. Our study here shows that PML colocalizes and associates in vivo with the DNA damage response protein TopBP1 in response to ionizing radiation (IR). Both PML and TopBP1 colocalized with the IR-induced bromodeoxyuridine single-stranded DNA foci. PML and TopBP1 also colocalized with Rad50, Brca1, ATM, Rad9, and BLM. IR and interferon (IFN) coinduce the expression levels of both TopBP1 and PML. In PML-deficient NB4 cells, TopBP1 was unable to form IR-induced foci. All-trans-retinoic acid induced reorganization of the PML nuclear body (NB) and reappearance of the IR-induced TopBP1 foci. Inhibition of PML expression by siRNA is associated with a significant decreased in TopBP1 expression. Furthermore, PML-deficient cells express a low level of TopBP1, and its expression cannot be induced by IR or IFN. Adenovirus-mediated overexpression of PML in PML(-/-) mouse embryo fibroblasts substantially increased TopBP1 expression, which colocalized with the PML NBs. These studies demonstrated a mechanism of PML-dependent expression of TopBP1. PML overexpression induced TopBP1 protein but not the mRNA expression. Pulse-chase labeling analysis demonstrated that PML overexpression stabilized the TopBP1 protein, suggesting that PML plays a role in regulating the stability of TopBP1 in response to IR. Together, our findings demonstrate that PML regulates TopBP1 functions by association and stabilization of the protein in response to IR-induced DNA damage.
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Affiliation(s)
- Zhi-Xiang Xu
- Department of Molecular Pathology, The University of Texas M D Anderson Cancer Center, Houston, Texas 77030, USA
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35
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Wu WS, Xu ZX, Hittelman WN, Salomoni P, Pandolfi PP, Chang KS. Promyelocytic leukemia protein sensitizes tumor necrosis factor alpha-induced apoptosis by inhibiting the NF-kappaB survival pathway. J Biol Chem 2003; 278:12294-304. [PMID: 12540841 DOI: 10.1074/jbc.m211849200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The promyelocytic leukemia protein (PML) is a growth/tumor suppressor essential for induction of apoptosis by diverse apoptotic stimuli. The mechanism by which PML regulates cell death remains unclear. In this study we found that ectopic expression of PML potentiates cell death by apoptosis in the tumor necrosis factor alpha (TNFalpha)-resistant cell line U2OS and other cell lines. Treatment with TNFalpha significantly sensitized these cells to apoptosis in a p53-independent manner. PML/TNFalpha-induced cell death is associated with DNA fragmentation, activation of caspase-3, -7, and -8, and degradation of DNA fragmentation factor/inhibitor of CAD. PML/TNFalpha-induced cell death could be blocked by the caspase-8 inhibitors CrmA and c-FLIP but not by Bcl-2. These findings indicate that this cell death event is initiated through the death receptor-dependent apoptosis pathway. PML is a transcriptional repressor of NF-kappaB by interacting with RelA/p65 and prevents its binding to the cognate enhancer through the C terminus. Coimmunoprecipitation and double-color immunofluorescence staining demonstrated that PML physically interacts with RelA/p65 in vivo and the two proteins colocalized at the endogenous levels. Overexpression of NF-kappaB rescued cell death induced by PML/TNFalpha. Furthermore, PML(-/-) mouse embryo fibroblasts are more resistant to TNFalpha-induced apoptosis. Together this study defines a novel mechanism by which PML induces apoptosis through repression of the NF-kappaB survival pathway.
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Affiliation(s)
- Wen-Shu Wu
- Department of Molecular Pathology, the University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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36
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Yu E, Choi EK, Kim CJ. Expression of promyelocytic leukemia protein increases during the differentiation of human neuroblastoma cells. Virchows Arch 2003; 442:278-83. [PMID: 12647219 DOI: 10.1007/s00428-002-0756-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2002] [Accepted: 10/06/2002] [Indexed: 11/30/2022]
Abstract
The promyelocytic leukemia (PML) protein, whose fusion with retinoic acid receptor alpha is responsible for the tumorigenesis of acute promyelocytic leukemia, acts as a tumor suppressor in various types of human cancers. We analyzed the expression patterns of PML, in both primary neuroblastic tumors ( n=20) and two human neuroblastoma (NB) cell lines, SMS-KCNR (KCNR) and SH-SY5Y (SY5Y). The expression of PML, revealed as speckled or microgranular staining in the nuclei, was positively correlated with the differentiation status of NB cells in vivo, and was upregulated during the differentiation of KCNR and SY5Y cells following retinoic acid treatment. Screening of PML expression in human brain and sympathetic ganglia showed restricted expression of PML in mature neurons and glial cells, a result that was consistent with that in differentiated NB tumors. All these findings strongly suggest that increased PML expression is associated with growth inhibition and differentiation of human NB cells, and that it is of critical significance in the biology of NBs and in human nervous system development.
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Affiliation(s)
- Eunsil Yu
- Department of Diagnostic Pathology, University of Ulsan College of Medicine, Asan Medical Center, 138-736, Seoul, Korea
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37
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Rivera OJ, Song CS, Centonze VE, Lechleiter JD, Chatterjee B, Roy AK. Role of the promyelocytic leukemia body in the dynamic interaction between the androgen receptor and steroid receptor coactivator-1 in living cells. Mol Endocrinol 2003; 17:128-40. [PMID: 12511612 DOI: 10.1210/me.2002-0165] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The dynamic interaction between the androgen receptor (AR) and steroid receptor coactivator-1 (SRC-1) was explored in living cells expressing chimeric forms of the receptor and the coactivator containing two spectral variants of jellyfish fluorescent protein. Laser scanning confocal imaging of transfected cells expressing fluorescently labeled SRC-1 revealed that in an unsynchronized cell population, the coactivator is distributed in approximately 40% cells as nuclear bodies of 0.2-1.0 microm in diameter. Immunostaining of cyan fluorescent protein-labeled SRC-1 (CFP-SRC1)-expressing cells with antibody to promyelocytic leukemia (PML) protein showed significant overlap of the CFP fluorescence with the antibody stain. Cotransfection of cells with a plasmid expressing the CFP conjugate of Sp100 (another marker protein for the PML nuclear body) also showed colocalization of the yellow fluorescent protein (YFP)-SRC1 containing nuclear foci with the PML bodies in living cells. Analysis of the three-dimensional structure revealed that the PML bodies are round to elliptical in shape with multiple satellite bodies on their surface. Some of these satellite bodies contain the SRC-1. Activation and nuclear import of CFP-AR by the agonistic ligand 5alpha-dihydrotestosterone, but not by the antagonist casodex, transferred YFP-SRC1 from the PML bodies to an interlacing filamentous structure. In a single living cell, agonist-activated AR caused a time-dependent movement of YFP-SRC1 from the PML bodies to this filamentous structure. Additionally, coexpression of a constitutively active mutant of AR (AR-deltaligand binding domain) also displaced YFP-SRC1 from the PML bodies to this intranuclear filamentous structure. The fluorescence recovery after photobleaching approach was used to examine changes in the kinetics of movement of YFP-SRC1 during its mobilization from the PML bodies to the intranuclear filamentous structure by the agonist-activated AR. Results of the relative half-times (t(1/2)) of replacement of YFP-SRC1 within the photobleached region of a single PML body from its surrounding nuclear space supported the conclusion that SRC-1 is actively transported from the PML bodies to the intranuclear filamentous structure by the ligand-activated AR. This observation also suggests an interaction between AR and SRC-1 before its binding to the target gene. The PML bodies have been implicated as a cross-road for multiple regulatory pathways that control cell proliferation, cellular senescence, and apoptosis. Our present results along with other recent reports expand the role of this subnuclear structure to include the regulation of steroid hormone action.
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Affiliation(s)
- Omar J Rivera
- Department of Cellular & Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78245-3207, USA
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38
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Yang S, Kuo C, Bisi JE, Kim MK. PML-dependent apoptosis after DNA damage is regulated by the checkpoint kinase hCds1/Chk2. Nat Cell Biol 2002; 4:865-70. [PMID: 12402044 DOI: 10.1038/ncb869] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2002] [Revised: 07/10/2002] [Accepted: 08/19/2002] [Indexed: 01/08/2023]
Abstract
The promyelocytic leukaemia (PML) gene is translocated in most acute promyelocytic leukaemias and encodes a tumour suppressor protein. PML is involved in multiple apoptotic pathways and is thought to be pivotal in gamma irradiation-induced apoptosis. The DNA damage checkpoint kinase hCds1/Chk2 is necessary for p53-dependent apoptosis after gamma irradiation. In addition, gamma irradiation-induced apoptosis also occurs through p53-independent mechanisms, although the molecular mechanism remains largely unknown. Here, we report that hCds1/Chk2 mediates gamma irradiation-induced apoptosis in a p53-independent manner through an ataxia telangiectasia-mutated (ATM)-hCds1/Chk2-PML pathway. Our results provide the first evidence of a functional relationship between PML and a checkpoint kinase in gamma irradiation-induced apoptosis.
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Affiliation(s)
- Shutong Yang
- Laboratory of Biochemical Genetics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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39
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Ferbeyre G. PML a target of translocations in APL is a regulator of cellular senescence. Leukemia 2002; 16:1918-26. [PMID: 12357343 DOI: 10.1038/sj.leu.2402722] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2002] [Accepted: 06/07/2002] [Indexed: 02/07/2023]
Abstract
PML is the most frequent fusion partner of the RARalpha in the specific translocations associated with acute promyelocytic leukemia (APL). Models to explain the origin of this leukemia propose a block in cell differentiation due to aberrant repression of retinoic acid responsive genes and/or disruption of the function of the PML-containing nuclear bodies. Recently, PML has been identified as a regulator of replicative senescence and the premature senescence that occurs in response to oncogenic ras. This review discusses the idea that senescence is a general tumor suppressor mechanism related to terminal differentiation and disrupted during the establishment of APL and other cancers. According to this idea the PML-RARalpha fusion protein promotes leukemogenesis not only through repression of retinoic acid responsive genes, but also by way of interfering with several tumor suppressor proteins that cooperate to establish senescence. Retinoids and other drugs effective against APL do so by re-establishment of the senescence program, which also includes features of cell differentiation.
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Affiliation(s)
- G Ferbeyre
- Université de Montréal, Département de Biochimie, Canada
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40
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Strudwick S, Borden KLB. Finding a role for PML in APL pathogenesis: a critical assessment of potential PML activities. Leukemia 2002; 16:1906-17. [PMID: 12357342 DOI: 10.1038/sj.leu.2402724] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2001] [Accepted: 04/02/2002] [Indexed: 01/10/2023]
Abstract
In normal mammalian cells the promyelocytic leukemia protein (PML) is primarily localized in multiprotein nuclear complexes called PML nuclear bodies. However, both PML and PML nuclear bodies are disrupted in acute promyelocytic leukemia (APL). The treatment of APL patients with all-trans retinoic acid (ATRA) results in clinical remission associated with blast cell differentiation and reformation of the PML nuclear bodies. These observations imply that the structural integrity of the PML nuclear body is critically important for normal cellular functions. Indeed, PML protein is a negative growth regulator capable of causing growth arrest in the G(1) phase of the cell cycle, transformation suppression, senescence and apoptosis. These PML-mediated, physiological effects can be readily demonstrated. However, a discrete biochemical and molecular model of PML function has yet to be defined. Upon first assessment of the current PML literature there appears to be a seemingly endless list of potential PML partner proteins implicating PML in a variety of regulatory mechanisms at every level of gene expression. The purpose of this review is to simplify this confusing field of research by using strict criteria to deduce which models of PML body function are well supported.
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Affiliation(s)
- S Strudwick
- Structural Biology Program, Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York University, New York 10029, USA
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41
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Wu WS, Xu ZX, Chang KS. The promyelocytic leukemia protein represses A20-mediated transcription. J Biol Chem 2002; 277:31734-9. [PMID: 12080044 DOI: 10.1074/jbc.m201648200] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The promyelocytic leukemia (PML) protein is a tumor suppressor that is disrupted by the chromosomal translocation t(15;17), a consistent cytogenetic feature of acute promyelocytic leukemia. A role of PML in multiple pathways of apoptosis was conclusively demonstrated using PML(-/-) animal and cell culture models. In a previous study, we found that PML sensitizes tumor necrosis factor-induced apoptosis in tumor necrosis factor (TNF)-resistant U2OS cells. This finding helped to explain the mechanism of PML-induced apoptosis. The zinc finger protein A20 is a target gene of NF kappa B inducible by TNF alpha, and it is a potent inhibitor of TNF-induced apoptosis. In the this study, we demonstrated that PML is a transcriptional repressor of the A20 promoter and that PML represses A20 expression induced by TNF alpha. We showed that PML inhibits A20 transactivation through the NF kappa B site by interfering with its binding to the promoter. We also showed that stable overexpression of A20 inhibits apoptosis and caspase activation induced by PML/TNF alpha. The results of this study suggest that A20 is a downstream target of PML-induced apoptosis and supports a role of A20 in modulating cell death induced by PML/TNF alpha in TNF-resistant cells.
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MESH Headings
- Apoptosis
- Base Sequence
- Cadmium/pharmacology
- Chromosomes, Human, Pair 15
- Chromosomes, Human, Pair 17
- DNA-Binding Proteins
- Gene Expression Regulation, Neoplastic
- Humans
- Intracellular Signaling Peptides and Proteins
- Leukemia, Promyelocytic, Acute
- NF-kappa B/metabolism
- Neoplasm Proteins/genetics
- Nuclear Proteins
- Promoter Regions, Genetic
- Promyelocytic Leukemia Protein
- Proteins/genetics
- Transcription Factors/genetics
- Transcription, Genetic
- Transcriptional Activation
- Translocation, Genetic
- Tumor Necrosis Factor alpha-Induced Protein 3
- Tumor Necrosis Factor-alpha/physiology
- Tumor Suppressor Proteins
- Zinc Fingers
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Affiliation(s)
- Wen-Shu Wu
- Department of Molecular Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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42
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Borden KLB. Pondering the promyelocytic leukemia protein (PML) puzzle: possible functions for PML nuclear bodies. Mol Cell Biol 2002; 22:5259-69. [PMID: 12101223 PMCID: PMC133952 DOI: 10.1128/mcb.22.15.5259-5269.2002] [Citation(s) in RCA: 243] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Katherine L B Borden
- Structural Biology Program, Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York University, One Gustave L. Levy Place, New York, NY 10029, USA.
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43
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Bischof O, Kirsh O, Pearson M, Itahana K, Pelicci PG, Dejean A. Deconstructing PML-induced premature senescence. EMBO J 2002; 21:3358-69. [PMID: 12093737 PMCID: PMC126090 DOI: 10.1093/emboj/cdf341] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2002] [Revised: 05/03/2002] [Accepted: 05/07/2002] [Indexed: 01/04/2023] Open
Abstract
In this study, we investigated the subcellular and molecular mechanisms underlying promyelocytic leukemia (PML)-induced premature senescence. We demonstrate that intact PML nuclear bodies are not required for the induction of senescence. We have determined further that of seven known PML isoforms, only PML IV is capable of causing premature senescence, providing the first evidence for functional differences among these isoforms. Of interest is the fact that in contrast to PML(+/+) fibroblasts, PML(-/-) cells are resistant to PML IV-induced senescence. This suggests that although PML IV is necessary for this process to occur, it is not sufficient and requires other components for activity. Finally, we provide evidence that PML IV-induced senescence involves stabilization and activation of p53 through phosphorylation at Ser46 and acetylation at Lys382, and that it occurs independently of telomerase and differs from that elicited by oncogenic Ras. Taken together, our data assign a specific pro-senescent activity to an individual PML isoform that involves p53 activation and is independent from PML nuclear bodies.
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Affiliation(s)
- Oliver Bischof
- Unité de Recombinaison et Expression Génétique, INSERM U 163, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France, European Institute of Oncology, Department of Experimental Oncology, 20141 Milan, Italy and Department of Cell and Molecular Biology, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA Corresponding author e-mail:
| | - Olivier Kirsh
- Unité de Recombinaison et Expression Génétique, INSERM U 163, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France, European Institute of Oncology, Department of Experimental Oncology, 20141 Milan, Italy and Department of Cell and Molecular Biology, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA Corresponding author e-mail:
| | - Mark Pearson
- Unité de Recombinaison et Expression Génétique, INSERM U 163, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France, European Institute of Oncology, Department of Experimental Oncology, 20141 Milan, Italy and Department of Cell and Molecular Biology, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA Corresponding author e-mail:
| | - Koji Itahana
- Unité de Recombinaison et Expression Génétique, INSERM U 163, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France, European Institute of Oncology, Department of Experimental Oncology, 20141 Milan, Italy and Department of Cell and Molecular Biology, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA Corresponding author e-mail:
| | - Pier Giuseppe Pelicci
- Unité de Recombinaison et Expression Génétique, INSERM U 163, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France, European Institute of Oncology, Department of Experimental Oncology, 20141 Milan, Italy and Department of Cell and Molecular Biology, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA Corresponding author e-mail:
| | - Anne Dejean
- Unité de Recombinaison et Expression Génétique, INSERM U 163, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France, European Institute of Oncology, Department of Experimental Oncology, 20141 Milan, Italy and Department of Cell and Molecular Biology, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA Corresponding author e-mail:
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44
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Wu WS, Xu ZX, Ran R, Meng F, Chang KS. Promyelocytic leukemia protein PML inhibits Nur77-mediated transcription through specific functional interactions. Oncogene 2002; 21:3925-33. [PMID: 12032831 DOI: 10.1038/sj.onc.1205491] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2001] [Revised: 03/13/2002] [Accepted: 03/18/2002] [Indexed: 11/08/2022]
Abstract
The promyelocytic leukemia protein PML is a tumor and growth suppressor and plays an important role in a multiple pathways of apoptosis and regulation of cell cycle progression. Our previous studies and others also documented a role of PML in transcriptional regulation through its association with transcription coactivator CBP and transcription corepressor HDAC. Here, we showed that PML is a potent transcriptional repressor of Nur77, an orphan receptor and a member of the steroid receptor superfamily of proteins. We found that PML represses Nur77-mediated transactivation through a physical and functional interaction between the two proteins. PML interacts with Nur-77 in vitro in a GST-pull down assay and in vivo by coimmunoprecipitation assay. PML/Nur77 colocalized in vivo in a double immunofluorescent staining and confocal microscopic analysis. Our study further showed that the coiled-coil domain of PML interacts with the DNA-binding domain of Nur77 (amino acids 267-332). Electrophoretic mobility shift assay demonstrated that PML interferes with Nur77 DNA binding in a dose-dependent manner. This study indicates that PML interacts with the DNA-binding domain of Nur77 and represses transcription by preventing it from binding to the target promoter. This study supports a role of PML/Nur77 interaction in regulating cell growth and apoptosis.
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MESH Headings
- Apoptosis
- Cell Division
- Cell Line
- Cell Nucleus/metabolism
- DNA, Complementary/metabolism
- DNA-Binding Proteins/metabolism
- Dose-Response Relationship, Drug
- Gene Expression Regulation, Neoplastic
- Glutathione Transferase/metabolism
- Humans
- Luciferases/metabolism
- Microscopy, Fluorescence
- Neoplasm Proteins/metabolism
- Nuclear Proteins
- Nuclear Receptor Subfamily 4, Group A, Member 1
- Plasmids/metabolism
- Precipitin Tests
- Promyelocytic Leukemia Protein
- Protein Binding
- Protein Structure, Tertiary
- Receptors, Cytoplasmic and Nuclear
- Receptors, Steroid
- Recombinant Fusion Proteins/metabolism
- Transcription Factors/metabolism
- Transcription, Genetic
- Transcriptional Activation
- Tumor Cells, Cultured
- Tumor Suppressor Proteins
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Affiliation(s)
- Wen-Shu Wu
- Department of Molecular Pathology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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45
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Scandura JM, Boccuni P, Cammenga J, Nimer SD. Transcription factor fusions in acute leukemia: variations on a theme. Oncogene 2002; 21:3422-44. [PMID: 12032780 DOI: 10.1038/sj.onc.1205315] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The leukemia-associated fusion proteins share several structural or functional similarities, suggesting that they may impart a leukemic phenotype through common modes of transcriptional dysregulation. The fusion proteins generated by these translocations usually contain a DNA-binding domain, domains responsible for homo- or hetero-dimerization, and domains that interact with proteins involved in chromatin remodeling (e.g., co-repressor molecules or co-activator molecules). It is these shared features that constitute the 'variations on the theme' that underling the aberrant growth and differentiation that is the hallmark of acute leukemia cells.
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Affiliation(s)
- Joseph M Scandura
- Laboratory of Molecular Aspects of Hematopoiesis, Sloan-Kettering Institute Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
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46
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Harrington KJ, Melcher AA, Bateman AR, Ahmed A, Vile RG. Cancer gene therapy: Part 2. Candidate transgenes and their clinical development. Clin Oncol (R Coll Radiol) 2002; 14:148-69. [PMID: 12069125 DOI: 10.1053/clon.2001.0004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Kevin J Harrington
- CRC Centre for Cell and Molecular Biology, Institute for Cancer Research, London, UK.
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47
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Abstract
The emerging field of nuclear eIF research has yielded many surprises and led to the dissolution of some dogmatic/ideological viewpoints of the place of translation in the regulation of gene expression. Eukaryotic initiation factors (eIFs) are classically defined by their cytoplasmic location and ability to regulate the initiation phase of protein synthesis. For instance, in the cytoplasm, the m7G cap-binding protein eIF4E plays a distinct role in cap-dependent translation initiation. Disruption of eIF4E's regulatory function drastically effects cell growth and may lead to oncogenic transformation. A growing number of studies indicate that many eIFs, including a substantial fraction of eIF4E, are found in the nucleus. Indeed, nuclear eIF4E participates in a variety of important RNA-processing events including the nucleocytoplasmic transport of specific, growth regulatory mRNAs. Although unexpected, it is possible that some eIFs regulate protein synthesis within the nucleus. This review will focus on the novel, nuclear functions of eIF4E and how they contribute to eIF4E's growth-activating and oncogenic properties. Both the cytoplasmic and nuclear functions of eIF4E appear to be dependent on its intrinsic ability to bind to the 5' m7G cap of mRNA. For example, Promyelocytic Leukemia Protein (PML) potentially acts as a negative regulator of nuclear eIF4E function by decreasing eIF4E's affinity for the m7G cap. Therefore, eIF4E protein is flexible enough to utilize a common biochemical activity, such as m7G cap binding, to participate in divergent processes in different cellular compartments.
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Affiliation(s)
- Stephen Strudwick
- Structural Biology Program, Department of Physiology & Biophysics, Mount Sinai School of Medicine, New York University, One Gustave Levy Place, New York, NY 10029, USA
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48
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Xia H, Qi H, Li Y, Pei J, Barton J, Blackstad M, Xu T, Tao W. LATS1 tumor suppressor regulates G2/M transition and apoptosis. Oncogene 2002; 21:1233-41. [PMID: 11850843 DOI: 10.1038/sj.onc.1205174] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2001] [Revised: 11/02/2001] [Accepted: 11/07/2001] [Indexed: 11/09/2022]
Abstract
The LATS1 gene is a mammalian member of the novel lats tumor suppressor family. Both lats mosaic flies and LATS1 deficient mice spontaneously develop tumors. Our previous studies have shown that inactivation of Drosophila lats leads to up-regulation of cyclin A in the fly, and the human LATS1 protein associates with CDC2 in early mitosis in HeLa cells, suggesting that the lats gene family may negatively regulate cell proliferation by modulating CDC2/Cyclin A activity. We demonstrate here that transduction of the human breast cancer cell MCF-7 with recombinant LATS1 adenovirus (Ad-LATS1), but not with EGFP adenovirus (Ad-EGFP), inhibits in vitro cell proliferation. Ectopic expression of LATS1 in MCF-7 cells specifically down-regulates Cyclin A and Cyclin B protein levels and dramatically reduces CDC2 kinase activity, leading to a G2/M blockade. Furthermore, Ad-LATS1 suppresses anchorage-independent growth of MCF-7 cells in soft agar and tumor formation in athymic nude mice. We also demonstrate that ectopic expression of LATS1 in MCF-7 cells and human lung cancer cell H460 up-regulates the level of BAX proteins and induces apoptosis. Finally, we show that LATS1 kinase activity is required for its ability to inhibit cell growth and induce apoptosis. The results indicate that the LATS1 tumor suppressor may play an important role in the control of human tumor development and that LATS1 suppresses tumorigenesis by negatively regulating cell proliferation and modulating cell survival.
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Affiliation(s)
- Hong Xia
- Stem Cell Institute, Cancer Center, Division of Hematology, Oncology and Transplantation, University of Minnesota, Minneapolis, MN 55455, USA
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49
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Abstract
The PML gene, involved in the t(15;17) chromosomal translocation of acute promyelocytic leukemia (APL), encodes a protein which localizes to the PML-nuclear body, a subnuclear macromolecular structure. PML controls apoptosis, cell proliferation, and senescence. Here, we review the current understanding of its role in tumor suppression.
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Affiliation(s)
- Paolo Salomoni
- Molecular Biology Program and Department of Pathology, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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50
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Le XF, Marcelli M, McWatters A, Nan B, Mills GB, O'Brian CA, Bast RC. Heregulin-induced apoptosis is mediated by down-regulation of Bcl-2 and activation of caspase-7 and is potentiated by impairment of protein kinase C alpha activity. Oncogene 2001; 20:8258-69. [PMID: 11781840 DOI: 10.1038/sj.onc.1205039] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2001] [Revised: 09/06/2001] [Accepted: 10/09/2001] [Indexed: 11/08/2022]
Abstract
Heregulins are a group of growth factors that play diverse and critical roles in the signaling network of the human epidermal growth factor receptor (HER or EGFR) superfamily. Our earlier studies have shown that recombinant heregulinbeta1 (HRG) induces apoptosis in SKBr3 breast cancer cells that overexpress HER2. Here we report molecular mechanisms of HRG-induced apoptosis. HRG treatment of SKBr3 cells for 72 h decreased the level of Bcl-2 protein. HRG treatment led to degradation of poly (ADP-ribose) polymerase (PARP) and activated both caspase-9 and caspase-7. No significant activation of caspase-3, -6, or -8 was detected. Expression of exogenous caspase-7 by adenovirus-caspase-7 (Ad-casp-7) in SKBr3 cells resulted in apoptosis, which mimicked the effect of HRG treatment. Expression of exogenous caspase-7 had no impact on Bcl-2 expression, but promoted PARP degradation. Two highly selective inhibitors of protein kinase C (PKC), GF109203X (GF) and Ro318425 (Ro), significantly enhanced HRG-induced apoptosis as determined by flow cytometric analysis and DNA fragmentation assay. Accordingly, the PKC inhibitor GF further decreased the level of Bcl-2 protein and further degraded PARP in HRG-treated cells. Assay of PKC activity indicated that HRG activated PKC in SKBr3 cells, predominantly affecting the PKCalpha isoform. To confirm which PKC isoform(s) mediated potentiation of HRG-induced apoptosis, the profile of PKC isoforms was measured in SKBr3 cells. Five PKC isoforms, PKCalpha, PKCiota, PKCzeta, PKClambda, and PKCdelta as well as their receptors (RACK1) were expressed in this cell line. Treatment with PKC inhibitors GF and Ro decreased protein levels of both PKCalpha and PKCdelta at 24 h. PKCalpha levels were still depressed at 72 h. GF and Ro had little effect on the expression of other PKC isoforms. An inhibitor of classical PKC isoforms (Go6976) enhanced HRG-induced apoptosis, whereas the PKCdelta selective inhibitor rottlerin did not. As PKCalpha was the only classical isoform expressed in SKBr3 cells, the effect of Go6976 on HRG-induced apoptosis largely related to inhibition of PKCalpha. Constitutive expression of wild-type PKCalpha attenuated the apoptosis produced by HRG and GF. Consequently, HRG-induced apoptosis in SKBr3 cells appeared to involve down-regulation of Bcl-2 protein, activation of caspase-9 and caspase-7, and degradation of PARP. Inhibition of PKC function enhanced HRG-induced apoptosis, leading to synergistic down-regulation of Bcl-2 expression. Impairment of the PKCalpha isoform alone was sufficient to potentiate HRG-induced apoptosis.
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Affiliation(s)
- X F Le
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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