1
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Kim H. Regulation of Med1 protein by overexpression of BAP1 in breast cancer cells. Mol Cell Oncol 2024; 11:2347827. [PMID: 38708315 PMCID: PMC11067983 DOI: 10.1080/23723556.2024.2347827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/23/2024] [Indexed: 05/07/2024]
Abstract
Med1 binds to a nuclear receptor and regulates transcription. Elevated Med1 protein expression promotes cancer growth in hormone-dependent breast and prostate cancers. Med1 protein expression was investigated by deubiquitinating enzymes (DUBs) overexpression in breast cancer cell lines. Various DNA constructs of SRT-DUBs were overexpressed in the MCF7 cell line, and Med1 protein expression was investigated by western blotting. The cell growth and in vitro invasion assay were performed in BRCA1-associated protein 1 (BAP1) wild type and mutant (C91A) overexpressed cells. Ubiquitination of the Med1 protein was observed, and Med1 protein expression and transcriptional activity were verified by various DUBs overexpressed. Although Med1 protein expression increased upon the overexpression of BAP1, it was not affected by the overexpression of BAP1 mutant (C91A). BAP1 was increased by the E2 treatment, which has an important effect on the breast cancer growth, and cell growth was decreased by BAP1 C91A overexpression. However, metastatic capacities were decreased by BAP1. In addition, the binding between the Med1 and the BAP1 protein was observed. These data suggested that BAP1 regulated Med1 protein expression in breast cancer cells and involved in cancer cell growth and metastasis by binding to Med1 protein.
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Affiliation(s)
- Hyunju Kim
- Department of Health Sciences, The Graduate School of Dong-A University, Busan, South Korea
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2
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Bick G, Zhang J, Lower EE, Zhang X. Transcriptional coactivator MED1 in the interface of anti-estrogen and anti-HER2 therapeutic resistance. Cancer Drug Resist 2022; 5:498-510. [PMID: 35800368 PMCID: PMC9255246 DOI: 10.20517/cdr.2022.33] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/30/2022] [Accepted: 04/02/2022] [Indexed: 11/18/2022]
Abstract
Breast cancer is one of the most common cancer and leading causes of death in women in the United States and Worldwide. About 90% of breast cancers belong to ER+ or HER2+ subtypes and are driven by key breast cancer genes Estrogen Receptor and HER2, respectively. Despite the advances in anti-estrogen (endocrine) and anti-HER2 therapies for the treatment of these breast cancer subtypes, unwanted side effects, frequent recurrence and resistance to these treatments remain major clinical challenges. Recent studies have identified ER coactivator MED1 as a key mediator of ER functions and anti-estrogen treatment resistance. Interestingly, MED1 is also coamplified with HER2 and activated by the HER2 signaling cascade, and plays critical roles in HER2-mediated tumorigenesis and response to anti-HER2 treatment as well. Thus, MED1 represents a novel crosstalk point of the HER2 and ER pathways and a highly promising new therapeutic target for ER+ and HER2+ breast cancer treatment. In this review, we will discuss the recent progress on the role of this key ER/HER2 downstream effector MED1 in breast cancer therapy resistance and our development of an innovative RNA nanotechnology-based approach to target MED1 for potential future breast cancer therapy to overcome treatment resistance.
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Affiliation(s)
- Gregory Bick
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Jasmine Zhang
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Elyse E. Lower
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA. ,University of Cincinnati Cancer Center, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Xiaoting Zhang
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.,Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA. ,University of Cincinnati Cancer Center, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.,Correspondence to: Prof. Xiaoting Zhang, Professor and Thomas Boat Endowed Chair, Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, 3125 Eden Avenue, Cincinnati, OH 45267, USA. E-mail:
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3
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Maldonado E, Morales-Pison S, Urbina F, Jara L, Solari A. Role of the Mediator Complex and MicroRNAs in Breast Cancer Etiology. Genes (Basel) 2022; 13:234. [PMID: 35205279 DOI: 10.3390/genes13020234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 12/16/2022] Open
Abstract
Transcriptional coactivators play a key role in RNA polymerase II transcription and gene regulation. One of the most important transcriptional coactivators is the Mediator (MED) complex, which is an evolutionary conserved large multiprotein complex. MED transduces the signal between DNA-bound transcriptional activators (gene-specific transcription factors) to the RNA polymerase II transcription machinery to activate transcription. It is known that MED plays an essential role in ER-mediated gene expression mainly through the MED1 subunit, since estrogen receptor (ER) can interact with MED1 by specific protein–protein interactions; therefore, MED1 plays a fundamental role in ER-positive breast cancer (BC) etiology. Additionally, other MED subunits also play a role in BC etiology. On the other hand, microRNAs (miRNAs) are a family of small non-coding RNAs, which can regulate gene expression at the post-transcriptional level by binding in a sequence-specific fashion at the 3′ UTR of the messenger RNA. The miRNAs are also important factors that influence oncogenic signaling in BC by acting as both tumor suppressors and oncogenes. Moreover, miRNAs are involved in endocrine therapy resistance of BC, specifically to tamoxifen, a drug that is used to target ER signaling. In metazoans, very little is known about the transcriptional regulation of miRNA by the MED complex and less about the transcriptional regulation of miRNAs involved in BC initiation and progression. Recently, it has been shown that MED1 is able to regulate the transcription of the ER-dependent miR-191/425 cluster promoting BC cell proliferation and migration. In this review, we will discuss the role of MED1 transcriptional coactivator in the etiology of BC and in endocrine therapy-resistance of BC and also the contribution of other MED subunits to BC development, progression and metastasis. Lastly, we identified miRNAs that potentially can regulate the expression of MED subunits.
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4
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Nagalingam A, Siddharth S, Parida S, Muniraj N, Avtanski D, Kuppusamy P, Elsey J, Arbiser JL, Győrffy B, Sharma D. Hyperleptinemia in obese state renders luminal breast cancers refractory to tamoxifen by coordinating a crosstalk between Med1, miR205 and ErbB. NPJ Breast Cancer 2021; 7:105. [PMID: 34389732 PMCID: PMC8363746 DOI: 10.1038/s41523-021-00314-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 07/26/2021] [Indexed: 12/17/2022] Open
Abstract
Obese women with hormone receptor-positive breast cancer exhibit poor response to therapy and inferior outcomes. However, the underlying molecular mechanisms by which obesity/hyperleptinemia may reduce the efficacy of hormonal therapy remain elusive. Obese mice with hyperleptinemia exhibit increased tumor progression and respond poorly to tamoxifen compared to non-obese mice. Exogenous leptin abrogates tamoxifen-mediated growth inhibition and potentiates breast tumor growth even in the presence of tamoxifen. Mechanistically, leptin induces nuclear translocation of phosphorylated-ER and increases the expression of ER-responsive genes, while reducing tamoxifen-mediated gene repression by abrogating tamoxifen-induced recruitment of corepressors NCoR, SMRT, and Mi2 and potentiating coactivator binding. Furthermore, in silico analysis revealed that coactivator Med1 potentially associates with 48 (out of 74) obesity-signature genes. Interestingly, leptin upregulates Med1 expression by decreasing miR-205, and increases its functional activation via phosphorylation, which is mediated by activation of Her2 and EGFR. It is important to note that Med1 silencing abrogates the negative effects of leptin on tamoxifen efficacy. In addition, honokiol or adiponectin treatment effectively inhibits leptin-induced Med1 expression and improves tamoxifen efficacy in hyperleptinemic state. These studies uncover the mechanistic insights how obese/hyperleptinemic state may contribute to poor response to tamoxifen implicating leptin-miR205-Med1 and leptin-Her2-EGFR-Med1 axes, and present bioactive compound honokiol and adipocytokine adiponectin as agents that can block leptin’s negative effect on tamoxifen.
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Affiliation(s)
- Arumugam Nagalingam
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Sumit Siddharth
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Sheetal Parida
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Nethaji Muniraj
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Dimiter Avtanski
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA.,Division of Endocrinology, Department of Medicine, Lenox Hill Hospital, New York, NY, USA
| | | | - Justin Elsey
- Department of Dermatology, Emory School of Medicine, Atlanta Veterans Administration Medical Center, Atlanta, GA, USA
| | - Jack L Arbiser
- Department of Dermatology, Emory School of Medicine, Atlanta Veterans Administration Medical Center, Atlanta, GA, USA
| | - Balázs Győrffy
- MTA TTK Momentum Cancer Biomarker Research Group, Budapest, Hungary.,Semmelweis University, Department of Bioinformatics and 2nd Department of Pediatrics, Budapest, Hungary
| | - Dipali Sharma
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA.
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5
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Nguyen TH, Vemu PL, Hoy GE, Boudjadi S, Chatterjee B, Shern JF, Khan J, Sun W, Barr FG. Serine hydroxymethyltransferase 2 expression promotes tumorigenesis in rhabdomyosarcoma with 12q13-q14 amplification. J Clin Invest 2021; 131:e138022. [PMID: 34166228 DOI: 10.1172/jci138022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 06/16/2021] [Indexed: 12/11/2022] Open
Abstract
The 12q13-q14 chromosomal region is recurrently amplified in 25% of fusion-positive (FP) rhabdomyosarcoma (RMS) cases and is associated with a poor prognosis. To identify amplified oncogenes in FP RMS, we compared the size, gene composition, and expression of 12q13-q14 amplicons in FP RMS with those of other cancer categories (glioblastoma multiforme, lung adenocarcinoma, and liposarcoma) in which 12q13-q14 amplification frequently occurs. We uncovered a 0.2 Mb region that is commonly amplified across these cancers and includes CDK4 and 6 other genes that are overexpressed in amplicon-positive samples. Additionally, we identified a 0.5 Mb segment that is only recurrently amplified in FP RMS and includes 4 genes that are overexpressed in amplicon-positive RMS. Among these genes, only serine hydroxymethyltransferase 2 (SHMT2) was overexpressed at the protein level in an amplicon-positive RMS cell line. SHMT2 knockdown in amplicon-positive RMS cells suppressed growth, transformation, and tumorigenesis, whereas overexpression in amplicon-negative RMS cells promoted these phenotypes. High SHMT2 expression reduced sensitivity of FP RMS cells to SHIN1, a direct SHMT2 inhibitor, but sensitized cells to pemetrexed, an inhibitor of the folate cycle. In conclusion, our study demonstrates that SHMT2 contributes to tumorigenesis in FP RMS and that SHMT2 amplification predicts differential response to drugs targeting this metabolic pathway.
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Affiliation(s)
| | | | | | | | | | | | - Javed Khan
- Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
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6
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Łukasik P, Załuski M, Gutowska I. Cyclin-Dependent Kinases (CDK) and Their Role in Diseases Development-Review. Int J Mol Sci 2021; 22:ijms22062935. [PMID: 33805800 PMCID: PMC7998717 DOI: 10.3390/ijms22062935] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/07/2021] [Accepted: 03/09/2021] [Indexed: 12/13/2022] Open
Abstract
Cyclin-dependent kinases (CDKs) are involved in many crucial processes, such as cell cycle and transcription, as well as communication, metabolism, and apoptosis. The kinases are organized in a pathway to ensure that, during cell division, each cell accurately replicates its DNA, and ensure its segregation equally between the two daughter cells. Deregulation of any of the stages of the cell cycle or transcription leads to apoptosis but, if uncorrected, can result in a series of diseases, such as cancer, neurodegenerative diseases (Alzheimer’s or Parkinson’s disease), and stroke. This review presents the current state of knowledge about the characteristics of cyclin-dependent kinases as potential pharmacological targets.
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Affiliation(s)
- Paweł Łukasik
- Department of Medical Chemistry, Pomeranian Medical University in Szczecin, Powstancow Wlkp. 72 Av., 70-111 Szczecin, Poland;
| | - Michał Załuski
- Department of Pharmaceutical Chemistry, Pomeranian Medical University in Szczecin, Powstancow Wlkp. 72 Av., 70-111 Szczecin, Poland;
| | - Izabela Gutowska
- Department of Medical Chemistry, Pomeranian Medical University in Szczecin, Powstancow Wlkp. 72 Av., 70-111 Szczecin, Poland;
- Correspondence:
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7
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Shukla A, Srivastava S, Darokar J, Kulshreshtha R. HIF1α and p53 Regulated MED30, a Mediator Complex Subunit, is Involved in Regulation of Glioblastoma Pathogenesis and Temozolomide Resistance. Cell Mol Neurobiol 2020; 41:1521-1535. [PMID: 32705436 DOI: 10.1007/s10571-020-00920-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 07/10/2020] [Indexed: 10/23/2022]
Abstract
Glioblastoma (GBM) is the most common, malignant, and aggressive form of glial cell cancer with unfavorable clinical outcomes. It is believed that a better understanding of the mechanisms of gene deregulation may lead to novel therapeutic approaches for this yet incurable cancer. Mediator complex is a crucial component of enhancer-based gene expression and works as a transcriptional co-activator. Many of the mediator complex subunits are found to be deregulated/mutated in various malignancies; however, their status and role in GBM remains little studied. We report that MED30, a core subunit of the head module, is overexpressed in GBM tissues and cell lines. MED30 was found to be induced by conditions present in the tumor microenvironment such as hypoxia, serum, and glucose deprivation. MED30 harbors hypoxia response elements (HREs) and p53 binding site in its promoter and is induced in a HIF1α and p53 dependent manner. Further, MED30 levels also significantly positively correlated with p53 and HIF1α levels in GBM tissues. Using both MED30 overexpression and knockdown approach, we show that MED30 promotes cell proliferation while reduces the migration capabilities in GBM cell lines. Notably, MED30 was also found to confer sensitivity to chemodrug, temozolomide, in GBM cells and modulate the level of p53 in vitro. Overall, this is the first report showing MED30 overexpression in GBM and its involvement in GBM pathogenesis suggesting its diagnostic and therapeutic potential urging the need for further systematic exploration of MED30 interactome and target networks.
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Affiliation(s)
- Anubha Shukla
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Srishti Srivastava
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Jayant Darokar
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Ritu Kulshreshtha
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, 110016, India.
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8
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Abstract
Estrogen receptor α (ERα) is closely associated with both hormone-dependent and hormone-independent tumors, and it is also essential for the development of these cancers. The functions of ERα are bi-faceted; it can contribute to cancer progression as well as cancer inhibition. Therefore, understanding ERα is vital for the treatment of those cancers that are closely associated with its expression. Here, we will elaborate on ERα based on its structure, localization, activation, modification, and mutation. Also, we will look at co-activators of ERα, elucidate the signaling pathway activated by ERα, and identify cancers related to its activation. A comprehensive understanding of ERα could help us to find new ways to treat cancers.
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Affiliation(s)
- Yanfang Liu
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, People's Republic of China
| | - Hong Ma
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, People's Republic of China
| | - Jing Yao
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, People's Republic of China
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9
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Shrinivas K, Sabari BR, Coffey EL, Klein IA, Boija A, Zamudio AV, Schuijers J, Hannett NM, Sharp PA, Young RA, Chakraborty AK. Enhancer Features that Drive Formation of Transcriptional Condensates. Mol Cell 2020; 75:549-561.e7. [PMID: 31398323 DOI: 10.1016/j.molcel.2019.07.009] [Citation(s) in RCA: 212] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 03/31/2019] [Accepted: 07/08/2019] [Indexed: 12/12/2022]
Abstract
Enhancers are DNA elements that are bound by transcription factors (TFs), which recruit coactivators and the transcriptional machinery to genes. Phase-separated condensates of TFs and coactivators have been implicated in assembling the transcription machinery at particular enhancers, yet the role of DNA sequence in this process has not been explored. We show that DNA sequences encoding TF binding site number, density, and affinity above sharply defined thresholds drive condensation of TFs and coactivators. A combination of specific structured (TF-DNA) and weak multivalent (TF-coactivator) interactions allows for condensates to form at particular genomic loci determined by the DNA sequence and the complement of expressed TFs. DNA features found to drive condensation promote enhancer activity and transcription in cells. Our study provides a framework to understand how the genome can scaffold transcriptional condensates at specific loci and how the universal phenomenon of phase separation might regulate this process.
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Affiliation(s)
- Krishna Shrinivas
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Benjamin R Sabari
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Eliot L Coffey
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Isaac A Klein
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Ann Boija
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Alicia V Zamudio
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jurian Schuijers
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Nancy M Hannett
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Phillip A Sharp
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Richard A Young
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Arup K Chakraborty
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02139, USA; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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10
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Leonard M, Zhang X. Estrogen receptor coactivator Mediator Subunit 1 (MED1) as a tissue-specific therapeutic target in breast cancer. J Zhejiang Univ Sci B 2019; 20:381-390. [PMID: 31090264 DOI: 10.1631/jzus.b1900163] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Breast cancer, one of the most frequent cancer types, is a leading cause of death in women worldwide. Estrogen receptor (ER) α is a nuclear hormone receptor that plays key roles in mammary gland development and breast cancer. About 75% of breast cancer cases are diagnosed as ER-positive; however, nearly half of these cancers are either intrinsically or inherently resistant to the current anti-estrogen therapies. Recent studies have identified an ER coactivator, Mediator Subunit 1 (MED1), as a unique, tissue-specific cofactor that mediates breast cancer metastasis and treatment resistance. MED1 is overexpressed in over 50% of human breast cancer cases and co-amplifies with another important breast cancer gene, receptor tyrosine kinase HER2. Clinically, MED1 expression highly correlates with poor disease-free survival of breast cancer patients, and recent studies have reported an increased frequency of MED1 mutations in the circulating tumor cells of patients after treatment. In this review, we discuss the biochemical characterization of MED1 and its associated MED1/Mediator complex, its crosstalk with HER2 in anti-estrogen resistance, breast cancer stem cell formation, and metastasis both in vitro and in vivo. Furthermore, we elaborate on the current advancements in targeting MED1 using state-of-the-art RNA nanotechnology and discuss the future perspectives as well.
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Affiliation(s)
- Marissa Leonard
- Department of Cancer Biology, University of Cincinnati College of Medicine, 3125 Eden Avenue, Cincinnati, OH 45267, USA
| | - Xiaoting Zhang
- Department of Cancer Biology, University of Cincinnati College of Medicine, 3125 Eden Avenue, Cincinnati, OH 45267, USA
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11
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Brückmann NH, Bennedsen SN, Duijf PHG, Terp MG, Thomassen M, Larsen M, Pedersen CB, Kruse T, Alcaraz N, Ditzel HJ, Gjerstorff MF. A functional genetic screen identifies the Mediator complex as essential for SSX2-induced senescence. Cell Death Dis 2019; 10:841. [PMID: 31695025 PMCID: PMC6834653 DOI: 10.1038/s41419-019-2068-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 10/14/2019] [Accepted: 10/16/2019] [Indexed: 01/03/2023]
Abstract
The senescence response to oncogenes is believed to be a barrier to oncogenic transformation in premalignant lesions, and describing the mechanisms by which tumor cells evade this response is important for early diagnosis and treatment. The male germ cell-associated protein SSX2 is ectopically expressed in many types of cancer and is functionally involved in regulating chromatin structure and supporting cell proliferation. Similar to many well-characterized oncogenes, SSX2 has the ability to induce senescence in cells. In this study, we performed a functional genetic screen to identify proteins implicated in SSX2-induced senescence and identified several subunits of the Mediator complex, which is central in regulating RNA polymerase-mediated transcription. Further experiments showed that reduced levels of MED1, MED4, and MED14 perturbed the development of senescence in SSX2-expressing cells. In contrast, knockdown of MED1 did not prevent development of B-Raf- and Epirubicin-induced senescence, suggesting that Mediator may be specifically linked to the cellular functions of SSX2 that may lead to development of senescence or be central in a SSX2-specific senescence response. Indeed, immunostaining of melanoma tumors, which often express SSX proteins, exhibited altered levels of MED1 compared to benign nevi. Similarly, RNA-seq analysis suggested that MED1, MED4, and MED14 were downregulated in some tumors, while upregulated in others. In conclusion, our study reveals the Mediator complex as essential for SSX2-induced senescence and suggests that changes in Mediator activity could be instrumental for tumorigenesis.
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Affiliation(s)
- Nadine H Brückmann
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Sofie N Bennedsen
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Pascal H G Duijf
- Institute of Health and Biomedical Innovation, Faculty of Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia.,University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, 37 Kent Street, Brisbane, QLD, 4102, Australia
| | - Mikkel G Terp
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Mads Thomassen
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
| | - Martin Larsen
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
| | - Christina B Pedersen
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Torben Kruse
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
| | - Nicolas Alcaraz
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Henrik J Ditzel
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Oncology, Odense University Hospital, Odense, Denmark.,Academy of Geriatric Cancer Research (AgeCare), Odense University Hospital, Odense, Denmark
| | - Morten F Gjerstorff
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark. .,Department of Oncology, Odense University Hospital, Odense, Denmark. .,Academy of Geriatric Cancer Research (AgeCare), Odense University Hospital, Odense, Denmark.
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12
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Becker F, Joerg V, Hupe MC, Roth D, Krupar R, Lubczyk V, Kuefer R, Sailer V, Duensing S, Kirfel J, Merseburger AS, Brägelmann J, Perner S, Offermann A. Increased mediator complex subunit CDK19 expression associates with aggressive prostate cancer. Int J Cancer 2019; 146:577-588. [PMID: 31271443 DOI: 10.1002/ijc.32551] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/07/2019] [Accepted: 06/24/2019] [Indexed: 12/23/2022]
Abstract
The Mediator complex is a transcriptional regulator interacting with transcription factors and RNA-polymerase-II. Recently, we identified its subunit CDK19 to be specifically expressed in prostate cancer (PCa) and to be functionally implicated in PCa aggressiveness. Aim of our study was to comprehensively characterize the protein expression of CDK19 and its paralog CDK8 in PCa. We performed immunohistochemistry (IHC) for CDK19/CDK8 on a large cohort including needle biopsies from 202 patients, 799 primary tumor foci of radical prostatectomy specimens from 415 patients, 120 locally advanced tumor foci obtained by palliative transurethral resection, 140 lymph node metastases, 67 distant metastases and 82 benigns. Primary tumors were stained for the proliferation marker Ki67, androgen receptor (AR) and ERG. For 376 patients, clinic-pathologic data were available. Primary endpoint was disease-recurrence-free survival (DFS). Nuclear CDK19 and CDK8 expression increases during progression showing the highest intensity in metastatic and castration-resistant tumors. High CDK19 expression on primary tumors correlates with DFS independently from Gleason grade and PSA. Five-year-DFS rates of patients with primary tumors expressing no, moderate and high CDK19 are 73.7, 56.9 and 30.4%, respectively. CDK19 correlates with Gleason grade, T-stage, Ki67 proliferation-index, nuclear AR expression and ERG-status. Therapeutic options for metastatic and castration-resistant PCa remain limited. In the current study, we confirmed an important role of the Mediator subunit CDK19 in advanced PCa supporting current developments to target CDK19 and its paralog CDK8. Furthermore, CDK19 protein expression has the potential to predict disease recurrence independently from established biomarkers thus contributing to individual management for PCa patients.
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Affiliation(s)
- Finn Becker
- Pathology of the University Hospital Schleswig-Holstein, Campus Luebeck, Luebeck, Germany.,Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Vincent Joerg
- Pathology of the University Hospital Schleswig-Holstein, Campus Luebeck, Luebeck, Germany.,Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Marie C Hupe
- Department of Urology, University Hospital Schleswig-Holstein, Luebeck, Germany
| | - Doris Roth
- Pathology of the University Hospital Schleswig-Holstein, Campus Luebeck, Luebeck, Germany.,Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | | | - Verena Lubczyk
- Department of Pathology, Klinik am Eichert Alb Fils Kliniken, Goeppingen, Germany
| | - Rainer Kuefer
- Department of Urology, Klinik am Eichert Alb Fils Kliniken, Goeppingen, Germany
| | - Verena Sailer
- Pathology of the University Hospital Schleswig-Holstein, Campus Luebeck, Luebeck, Germany
| | - Stefan Duensing
- Molecular Urooncology, Department of Urology, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Jutta Kirfel
- Pathology of the University Hospital Schleswig-Holstein, Campus Luebeck, Luebeck, Germany
| | - Axel S Merseburger
- Department of Urology, University Hospital Schleswig-Holstein, Luebeck, Germany
| | - Johannes Brägelmann
- Molecular Pathology, Institute of Pathology, University Hospital of Cologne, Cologne, Germany.,Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, Medical Faculty, University of Cologne, Cologne, Germany
| | - Sven Perner
- Pathology of the University Hospital Schleswig-Holstein, Campus Luebeck, Luebeck, Germany.,Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Anne Offermann
- Pathology of the University Hospital Schleswig-Holstein, Campus Luebeck, Luebeck, Germany.,Research Center Borstel, Leibniz Lung Center, Borstel, Germany
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13
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Saha T, Makar S, Swetha R, Gutti G, Singh SK. Estrogen signaling: An emanating therapeutic target for breast cancer treatment. Eur J Med Chem 2019; 177:116-143. [PMID: 31129450 DOI: 10.1016/j.ejmech.2019.05.023] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/29/2019] [Accepted: 05/06/2019] [Indexed: 12/15/2022]
Abstract
Breast cancer, a most common malignancy in women, was known to be associated with steroid hormone estrogen. The discovery of estrogen receptor (ER) gave us not only a powerful predictive and prognostic marker, but also an efficient target for the treatment of hormone-dependent breast cancer with various estrogen ligands. ER consists of two subtypes i.e. ERα and ERβ, that are mostly G-protein-coupled receptors and activated by estrogen, specially 17β-estradiol. The activation is followed by translocation into the nucleus and binding with DNA to modulate activities of different genes. ERs can manage synthesis of RNA through genomic actions without directly binding to DNA. Receptors are tethered by protein-protein interactions to a transcription factor complex to communicate with DNA. Estrogens also exhibit nongenomic actions, a characteristic feature of steroid hormones, which are so rapid to be considered by the activation of RNA and translation. These are habitually related to stimulation of different protein kinase cascades. Majority of post-menopausal breast cancer is estrogen dependent, mostly potent biological estrogen (E2) for continuous growth and proliferation. Estrogen helps in regulating the differentiation and proliferation of normal breast epithelial cells. In this review we have investigated the important role of ER in development and progression of breast cancer, which is complicated by receptor's interaction with co-regulatory proteins, cross-talk with other signal transduction pathways and development of treatment strategies viz. selective estrogen receptor modulators (SERMs), selective estrogen receptor down regulators (SERDs), aromatase and sulphatase inhibitors.
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Affiliation(s)
- Tanmay Saha
- Pharmaceutical Chemistry Research Laboratory, Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (BHU), Varanasi, 221005, U.P, India
| | - Subhajit Makar
- Pharmaceutical Chemistry Research Laboratory, Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (BHU), Varanasi, 221005, U.P, India
| | - Rayala Swetha
- Pharmaceutical Chemistry Research Laboratory, Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (BHU), Varanasi, 221005, U.P, India
| | - Gopichand Gutti
- Pharmaceutical Chemistry Research Laboratory, Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (BHU), Varanasi, 221005, U.P, India
| | - Sushil K Singh
- Pharmaceutical Chemistry Research Laboratory, Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (BHU), Varanasi, 221005, U.P, India.
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14
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Nagpal N, Sharma S, Maji S, Durante G, Ferracin M, Thakur JK, Kulshreshtha R. Essential role of MED1 in the transcriptional regulation of ER-dependent oncogenic miRNAs in breast cancer. Sci Rep 2018; 8:11805. [PMID: 30087366 PMCID: PMC6081450 DOI: 10.1038/s41598-018-29546-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 07/12/2018] [Indexed: 01/24/2023] Open
Abstract
Mediator complex has been extensively shown to regulate the levels of several protein-coding genes; however, its role in the regulation of miRNAs in humans remains unstudied so far. Here we show that MED1, a Mediator subunit in the Middle module of Mediator complex, is overexpressed in breast cancer and is a negative prognostic factor. The levels of several miRNAs (miR-100-5p, -191-5p, -193b-3p, -205-5p, -326, -422a and -425-5p) were found to be regulated by MED1. MED1 induces miR-191/425 cluster in an estrogen receptor-alpha (ER-α) dependent manner. Occupancy of MED1 on estrogen response elements (EREs) upstream of miR-191/425 cluster is estrogen and ER-α-dependent and ER-α-induced expression of these miRNAs is MED1-dependent. MED1 mediates induction of cell proliferation and migration and the genes associated with it (JUN, FOS, EGFR, VEGF, MMP1, and ERBB4) in breast cancer, which is abrogated when used together with miR-191-inhibition. Additionally, we show that MED1 also regulates the levels of direct miR-191 target genes such as SATB1, CDK6 and BDNF. Overall, the results show that MED1/ER-α/miR-191 axis promotes breast cancer cell proliferation and migration and may serve as a novel target for therapy.
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Affiliation(s)
- Neha Nagpal
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, 110016, India.,Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Shivani Sharma
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Sourobh Maji
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Giorgio Durante
- Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, 40126, Bologna, Italy
| | - Manuela Ferracin
- Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, 40126, Bologna, Italy
| | - Jitendra K Thakur
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
| | - Ritu Kulshreshtha
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, 110016, India.
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15
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Cottone E, Orso F, Biglia N, Sismondi P, De Bortoli M. Role of Coactivators and Corepressors in Steroid and Nuclear Receptor Signaling: Potential Markers of Tumor Growth and Drug Sensitivity. Int J Biol Markers 2018; 16:151-66. [PMID: 11605727 DOI: 10.1177/172460080101600301] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Nuclear receptors regulate target gene expression in response to steroid and thyroid hormones, retinoids, vitamin D and other ligands. These ligand-dependent transcription factors function by contacting various nuclear cooperating proteins, called coactivators and corepressors, which mediate local chromatin remodeling as well as communication with the basal transcriptional apparatus. Nuclear receptors and their coregulatory proteins play a role in cancer and other diseases, one leading example being the estrogen receptor pathway in breast cancer. Coregulators are often present in limiting amounts in cell nuclei and modifications of their level of expression and/or structure lead to alterations in nuclear receptor functioning, which may be as pronounced as a complete inversion of signaling, i.e. from stimulating to repressing certain genes in response to an identical stimulus. In addition, hemizygous knock-out of certain coactivator genes has been demonstrated to produce cancer-prone phenotypes in mice. Thus, assessment of coactivator and corepressor expression and structure in tumors may turn out to be essential to determine the role of nuclear receptors in cancer and to predict prognosis and response to therapy.
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Affiliation(s)
- E Cottone
- Department of Animal and Human Biology, University of Turin, Italy
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16
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Yang Y, Leonard M, Zhang Y, Zhao D, Mahmoud C, Khan S, Wang J, Lower EE, Zhang X. HER2-Driven Breast Tumorigenesis Relies upon Interactions of the Estrogen Receptor with Coactivator MED1. Cancer Res 2017; 78:422-435. [PMID: 29187405 DOI: 10.1158/0008-5472.can-17-1533] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/18/2017] [Accepted: 11/20/2017] [Indexed: 12/21/2022]
Abstract
Studies of the estrogen receptor (ER) coactivator protein Mediator subunit 1 (MED1) have revealed its specific roles in pubertal mammary gland development and potential contributions to breast tumorigenesis, based on coamplification of MED1 and HER2 in certain breast cancers. In this study, we generated a mouse model of mammary tumorigenesis harboring the MMTV-HER2 oncogene and mutation of MED1 to evaluate its role in HER2-driven tumorigenesis. MED1 mutation in its ER-interacting LxxLL motifs was sufficient to delay tumor onset and to impair tumor growth, metastasis, and cancer stem-like cell formation in this model. Mechanistic investigations revealed that MED1 acted directly to regulate ER signaling through the downstream IGF1 pathway but not the AREG pathway. Our findings show that MED1 is critical for HER2-driven breast tumorigenesis, suggesting its candidacy as a disease-selective therapeutic target.Significance: These findings identify an estrogen receptor-binding protein as a critical mediator of HER2-driven breast tumorigenesis, suggesting its candidacy as a disease-selective therapeutic target. Cancer Res; 78(2); 422-35. ©2017 AACR.
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Affiliation(s)
- Yongguang Yang
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Marissa Leonard
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio.,Graduate Program in Cancer and Cell Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Yijuan Zhang
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Dan Zhao
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Charif Mahmoud
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Shugufta Khan
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Jiang Wang
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Elyse E Lower
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Xiaoting Zhang
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio. .,Graduate Program in Cancer and Cell Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio
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17
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Abstract
The multisubunit Mediator is an evolutionary conserved transcriptional coregulatory complex in eukaryotes. It is needed for the transcriptional regulation of gene expression in general as well as in a gene specific manner. Mediator complex subunits interact with different transcription factors as well as components of RNA Pol II transcription initiation complex and in doing so act as a bridge between gene specific transcription factors and general Pol II transcription machinery. Specific interaction of various Mediator subunits with nuclear receptors (NRs) and other transcription factors involved in metabolism has been reported in different studies. Evidences indicate that ligand-activated NRs recruit Mediator complex for RNA Pol II-dependent gene transcription. These NRs have been explored as therapeutic targets in different metabolic diseases; however, they show side-effects as targets due to their overlapping involvement in different signaling pathways. Here we discuss the interaction of various Mediator subunits with transcription factors involved in metabolism and whether specific interaction of these transcription factors with Mediator subunits could be potentially utilized as therapeutic strategy in a variety of metabolic diseases.
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Affiliation(s)
- Amol Ranjan
- Stowers Institute for Medical Research, 1000 E, 50th Street, Kansas City, MO, 64110, USA
| | - Suraiya A Ansari
- Department of Biochemistry, College of Medicine and Health Sciences, UAE University, AlAin, Abu Dhabi, United Arab Emirates.
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18
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Alexe G, Dalgin G, Ramaswamy R, Delisi C, Bhanot G. Data Perturbation Independent Diagnosis and Validation of Breast Cancer Subtypes Using Clustering and Patterns. Cancer Inform 2017. [DOI: 10.1177/117693510600200006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Molecular stratification of disease based on expression levels of sets of genes can help guide therapeutic decisions if such classifications can be shown to be stable against variations in sample source and data perturbation. Classifications inferred from one set of samples in one lab should be able to consistently stratify a different set of samples in another lab. We present a method for assessing such stability and apply it to the breast cancer (BCA) datasets of Sorlie et al. 2003 and Ma et al. 2003. We find that within the now commonly accepted BCA categories identified by Sorlie et al. Luminal A and Basal are robust, but Luminal B and ERBB2+ are not. In particular, 36% of the samples identified as Luminal B and 55% identified as ERBB2+ cannot be assigned an accurate category because the classification is sensitive to data perturbation. We identify a “core cluster” of samples for each category, and from these we determine “patterns” of gene expression that distinguish the core clusters from each other. We find that the best markers for Luminal A and Basal are (ESR1, LIV1, GATA-3) and (CCNE1, LAD1, KRT5), respectively. Pathways enriched in the patterns regulate apoptosis, tissue remodeling and the immune response. We use a different dataset (Ma et al. 2003) to test the accuracy with which samples can be allocated to the four disease subtypes. We find, as expected, that the classification of samples identified as Luminal A and Basal is robust but classification into the other two subtypes is not.
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Affiliation(s)
- G. Alexe
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, U.S.A
- The Simons Center for Systems Biology, Institute for Advanced Study, Princeton NJ 08540, U.S.A
| | - G.S. Dalgin
- Molecular Biology, Cell Biology and Biochemistry Program, Boston University, 2 Cummington Street, Boston, MA 02215, U.S.A
| | - R. Ramaswamy
- The Simons Center for Systems Biology, Institute for Advanced Study, Princeton NJ 08540, U.S.A
- School of Information Technology, Jawaharlal Nehru University, New Delhi 110 067, India
| | - C. Delisi
- Biomedical Engineering, Boston University, 44 Cummington Street, Boston, MA 02215, U.S.A
| | - G. Bhanot
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, U.S.A
- The Simons Center for Systems Biology, Institute for Advanced Study, Princeton NJ 08540, U.S.A
- Biomedical Engineering, Boston University, 44 Cummington Street, Boston, MA 02215, U.S.A
- Department of Biomedical Engineering and BioMaPS Institute, Rutgers University, Piscataway, NJ 08854
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19
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Abstract
Mediator complex subunit 1 (Med1)/Thyroid hormone receptor-associated protein 220 (TRAP220), an essential component of thyroid hormone receptor-associated proteins (TRAP)/mediator, plays important roles in hormone responses and tumorigenesis. However, the role of Med1 in the DNA damage response has not been studied. In this study, we found that DNA damage, resulted from γ-irradiation, ultraviolet (UV)-irradiation, or hydroxyurea, induced phosphorylation of Med1 in vivo. Phosphorylation of Med1 was abrogated by either caffeine or wortmannin treatment, suggesting that Med1 is phosphorylated through the DNA damage checkpoint pathway. A checkpoint kinase 1 (Chk1)/checkpoint kinase 2 (Chk2) consensus phosphorylation motif was identified at Serine 671 of Med1 and Ser671 motif was primarily phosphorylated by Chk2 in vitro. Moreover, the in vivo phosphorylation of Med1 was abrogated by a Chk2 inhibitor, and physical interaction between Chk2 and Med1 was observed, confirming that Chk2 is responsible for Med1 phosphorylation upon DNA damage. These results suggest that Med1 is a novel target for the DNA damage checkpoint pathway and may participate in the DNA damage response. Consistent with this notion, knockdown of Med1 expression caused a significant increase in cellular sensitivity to UV irradiation. Moreover, microarray analysis revealed that the UV-induced activation of the transcription of important regulators of cell cycle control and DNA repair, including p21, Gadd45, Rad50, DnaJ, and RecQL, was impaired upon Med1 knockdown. Taken together, our data suggest that Med1 is a novel target for Chk2-mediated phosphorylation and may play a role in cellular DNA damage responses by mediating proper induction of gene transcription upon DNA damage.
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Affiliation(s)
- Hyun-Ju Kim
- Peripheral Neuropathy Research Center, College of Medicine, Dong-A University, Busan 49201, Korea
- Department of Biochemistry, College of Medicine, Dong-A University, Busan 49201, Korea
| | - Jeanho Yun
- Peripheral Neuropathy Research Center, College of Medicine, Dong-A University, Busan 49201, Korea
- Department of Biochemistry, College of Medicine, Dong-A University, Busan 49201, Korea
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20
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Zhang Y, Leonard M, Shu Y, Yang Y, Shu D, Guo P, Zhang X. Overcoming Tamoxifen Resistance of Human Breast Cancer by Targeted Gene Silencing Using Multifunctional pRNA Nanoparticles. ACS Nano 2017; 11:335-346. [PMID: 27966906 PMCID: PMC5488869 DOI: 10.1021/acsnano.6b05910] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Most breast cancers express estrogen receptor (ER) α, and the antiestrogen drug tamoxifen has been widely used for their treatment. Unfortunately, up to half of all ERα-positive tumors have intrinsic or acquired endocrine therapy resistance. Our recent studies revealed that the ER coactivator Mediator Subunit 1 (MED1) plays a critical role in tamoxifen resistance through cross-talk with HER2. Herein, we assembled a three-way junction (3-WJ) pRNA-HER2apt-siMED1 nanoparticle to target HER2-overexpressing human breast cancer via an HER2 RNA aptamer to silence MED1 expression. We found that these ultracompact RNA nanoparticles are very stable under RNase A, serum, and 8 M urea conditions. These nanoparticles specifically bound to HER2-overexpressing breast cancer cells, efficiently depleted MED1 expression, and significantly decreased ERα-mediated gene transcription, whereas point mutations of the HER2 RNA aptamer on these nanoparticles abolished such functions. The RNA nanoparticles not only reduced the growth, metastasis, and mammosphere formation of the HER2-overexpressing breast cancer cells but also sensitized them to tamoxifen treatment. These biosafe nanoparticles efficiently targeted and penetrated into HER2-overexpressing tumors after systemic administration in orthotopic xenograft mouse models. In addition to their ability to greatly inhibit tumor growth and metastasis, these nanoparticles also led to a dramatic reduction in the stem cell content of breast tumors when combined with tamoxifen treatment in vivo. Overall, we have generated multifunctional RNA nanoparticles that specifically targeted HER2-overexpressing human breast cancer, silenced MED1, and overcame tamoxifen resistance.
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Affiliation(s)
- Yijuan Zhang
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
| | - Marissa Leonard
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
- Graduate Program in Cancer and Cell Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
| | - Yi Shu
- College of Pharmacy, Department of Physiology & Cell Biology, College of Medicine, and Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, United States
| | - Yongguang Yang
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
| | - Dan Shu
- College of Pharmacy, Department of Physiology & Cell Biology, College of Medicine, and Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, United States
| | - Peixuan Guo
- College of Pharmacy, Department of Physiology & Cell Biology, College of Medicine, and Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, United States
| | - Xiaoting Zhang
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
- Graduate Program in Cancer and Cell Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
- Corresponding Author: Tel: 513-558-3017. Fax: 513-558-4454.
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21
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Chen Q, Weng Z, Lu Y, Jia Y, Ding L, Bai F, Ge M, Lin Q, Wu K. An Experimental Analysis of the Molecular Effects of Trastuzumab (Herceptin) and Fulvestrant (Falsodex), as Single Agents or in Combination, on Human HR+/HER2+ Breast Cancer Cell Lines and Mouse Tumor Xenografts. PLoS One 2017; 12:e0168960. [PMID: 28045951 PMCID: PMC5207527 DOI: 10.1371/journal.pone.0168960] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 12/08/2016] [Indexed: 11/28/2022] Open
Abstract
Purpose To investigate the effects of trastuzumab (herceptin) and fulvestrant (falsodex) either in combination or alone, on downstream cell signaling pathways in lab-cultured human HR+/HER2+ breast cancer cell lines ZR-75-1 and BT-474, as well as on protein expression levels in mouse xenograft tissue. Methods Cells were cultivated in the presence of trastuzumab or fulvestrant or both. Molecular events that resulted in an inhibition of cell proliferation and cell cycle progression or in an increased rate of apoptosis were studied. The distribution and abundance of the proteins p-Akt and p-Erk expressed in these cells in response to single agents or combinatorial treatment were also investigated. In addition, the effects of trastuzumab and fulvestrant, either as single agents or in combination on tumor growth as well as on expression of the protein p-MED1 expressed in in vivo mouse xenograft models was also examined. Results Cell proliferation was increasingly inhibited by trastuzumab or fulvestrant or both, with a CI<1 and DRI>1 in both human cell lines. The rate of apoptosis increased only in the BT-474 cell line and not in the ZR-75-1 cell line upon treatment with fulvestrant and not trastuzumab as a single agent (P<0.05). Interestingly, fulvestrant, in combination with trastuzumab, did not significantly alter the rate of apoptosis (in comparison with fulvestrant alone), in the BT-474 cell line (P>0.05). Cell accumulation in the G1 phase of cell cycle was investigated in all treatment groups (P<0.05), and the combination of trastuzumab and fulvestrant reversed the effects of fulvestrant alone on p-Akt and p-Erk protein expression levels. Using ZR-75-1 or BT-474 to generate in vivo tumor xenografts in BALB/c athymic mouse models, we showed that a combination of both drugs resulted in a stronger inhibition of tumor growth (P<0.05) and a greater decrease in the levels of activated MED1 (p-MED1) expressed in tumor issues compared with the use of either drug as a single agent. Conclusions We demonstrate that the administration of trastuzumab and fulvestrant in combination results in positive synergistic effects on both, ZR-75-1 and BT-474 cell lines. This combinatorial approach is likely to reduce physiological side effects of both drugs, thus providing a theoretical basis for the use of such combination treatment in order to resolve HR+/HER2+ triple positive breast cancer that has previously been shown to be resistant to endocrine treatment alone.
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Affiliation(s)
- Qing Chen
- Department of General Surgery, XinHua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ziyi Weng
- Department of General Surgery, Shanghai International Medical Center, Shanghai, China
| | - Yunshu Lu
- Department of General Surgery, XinHua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yijun Jia
- Department of General Surgery, XinHua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Longlong Ding
- Department of General Surgery, XinHua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fang Bai
- Department of General Surgery, XinHua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Meixin Ge
- Department of General Surgery, XinHua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qing Lin
- Department of Radiation Oncology, The Shanghai Tenth People's Hospital of Tongji University, Shanghai, China
- * E-mail: (KW); (QL)
| | - Kejin Wu
- Department of Breast Surgery, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China
- * E-mail: (KW); (QL)
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22
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Jia Y, Chang HC, Schipma MJ, Liu J, Shete V, Liu N, Sato T, Thorp EB, Barger PM, Zhu YJ, Viswakarma N, Kanwar YS, Ardehali H, Thimmapaya B, Reddy JK. Cardiomyocyte-Specific Ablation of Med1 Subunit of the Mediator Complex Causes Lethal Dilated Cardiomyopathy in Mice. PLoS One 2016; 11:e0160755. [PMID: 27548259 PMCID: PMC4993490 DOI: 10.1371/journal.pone.0160755] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 07/25/2016] [Indexed: 11/19/2022] Open
Abstract
Mediator, an evolutionarily conserved multi-protein complex consisting of about 30 subunits, is a key component of the polymerase II mediated gene transcription. Germline deletion of the Mediator subunit 1 (Med1) of the Mediator in mice results in mid-gestational embryonic lethality with developmental impairment of multiple organs including heart. Here we show that cardiomyocyte-specific deletion of Med1 in mice (csMed1-/-) during late gestational and early postnatal development by intercrossing Med1fl/fl mice to α-MyHC-Cre transgenic mice results in lethality within 10 days after weaning due to dilated cardiomyopathy-related ventricular dilation and heart failure. The csMed1-/- mouse heart manifests mitochondrial damage, increased apoptosis and interstitial fibrosis. Global gene expression analysis revealed that loss of Med1 in heart down-regulates more than 200 genes including Acadm, Cacna1s, Atp2a2, Ryr2, Pde1c, Pln, PGC1α, and PGC1β that are critical for calcium signaling, cardiac muscle contraction, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy and peroxisome proliferator-activated receptor regulated energy metabolism. Many genes essential for oxidative phosphorylation and proper mitochondrial function such as genes coding for the succinate dehydrogenase subunits of the mitochondrial complex II are also down-regulated in csMed1-/- heart contributing to myocardial injury. Data also showed up-regulation of about 180 genes including Tgfb2, Ace, Atf3, Ctgf, Angpt14, Col9a2, Wisp2, Nppa, Nppb, and Actn1 that are linked to cardiac muscle contraction, cardiac hypertrophy, cardiac fibrosis and myocardial injury. Furthermore, we demonstrate that cardiac specific deletion of Med1 in adult mice using tamoxifen-inducible Cre approach (TmcsMed1-/-), results in rapid development of cardiomyopathy and death within 4 weeks. We found that the key findings of the csMed1-/- studies described above are highly reproducible in TmcsMed1-/- mouse heart. Collectively, these observations suggest that Med1 plays a critical role in the maintenance of heart function impacting on multiple metabolic, compensatory and reparative pathways with a likely therapeutic potential in the management of heart failure.
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MESH Headings
- Animals
- Apoptosis
- Cadherins/genetics
- Cadherins/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Signaling
- Cardiomyopathy, Dilated/genetics
- Cardiomyopathy, Dilated/metabolism
- Cardiomyopathy, Dilated/pathology
- Cyclic Nucleotide Phosphodiesterases, Type 1/genetics
- Cyclic Nucleotide Phosphodiesterases, Type 1/metabolism
- Embryo, Mammalian
- Energy Metabolism
- Female
- Gene Deletion
- Gene Expression Profiling
- Gene Expression Regulation
- Genes, Lethal
- Gestational Age
- Heart Failure/genetics
- Heart Failure/metabolism
- Heart Failure/pathology
- Mediator Complex Subunit 1/deficiency
- Mediator Complex Subunit 1/genetics
- Mice
- Mice, Knockout
- Mitochondria/metabolism
- Mitochondria/pathology
- Myocardial Contraction
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Peroxisome Proliferator-Activated Receptors/genetics
- Peroxisome Proliferator-Activated Receptors/metabolism
- Pregnancy
- Ryanodine Receptor Calcium Release Channel/genetics
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/genetics
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism
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Affiliation(s)
- Yuzhi Jia
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Hsiang-Chun Chang
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Matthew J. Schipma
- Next Generation Sequencing Core Facility, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Jing Liu
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Varsha Shete
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Ning Liu
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Tatsuya Sato
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Edward B. Thorp
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Philip M. Barger
- Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Yi-Jun Zhu
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Navin Viswakarma
- Department of Surgery, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Yashpal S. Kanwar
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Hossein Ardehali
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Bayar Thimmapaya
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail: (JKR); (BT)
| | - Janardan K. Reddy
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail: (JKR); (BT)
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23
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Liu G, Sprenger C, Wu PJ, Sun S, Uo T, Haugk K, Epilepsia KS, Plymate S. MED1 mediates androgen receptor splice variant induced gene expression in the absence of ligand. Oncotarget 2015; 6:288-304. [PMID: 25481872 DOI: 10.18632/oncotarget.2672] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/02/2014] [Indexed: 11/25/2022] Open
Abstract
The appearance of constitutively active androgen receptor splice variants (AR-Vs) has been proposed as one of the causes of castration-resistant prostate cancer (CRPC). However, the underlying mechanism of AR-Vs in CRPC transcriptional regulation has not been defined. A distinct transcriptome enriched with cell cycle genes, e.g. UBE2C, has been associated with AR-Vs, which indicates the possibility of an altered transcriptional mechanism when compared to full-length wild-type AR (ARfl). Importantly, a recent study reported the critical role of p-MED1 in enhancing UBE2C expression through a locus looping pattern, which only occurs in CRPC but not in androgen-dependent prostate cancer (ADPC). To investigate the potential correlation between AR-V and MED1, in the present study we performed protein co-immunoprecipitation, chromatin immunoprecipitation, and cell proliferation assays and found that MED1 is necessary for ARv567es induced UBE2C up-regulation and subsequent prostate cancer cell growth. Furthermore, p-MED1 is bound to ARv567es independent of full-length AR; p-MED1 has higher recruitment to UBE2C promoter and enhancer regions in the presence of ARv567es. Our data indicate that p-MED1 serves as a key mediator in ARv567es induced gene expression and suggests a mechanism by which AR-Vs promote the development and progression of CRPC.
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24
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Lacle MM, Moelans CB, Kornegoor R, van der Pol C, Witkamp AJ, van der Wall E, Rueschoff J, Buerger H, van Diest PJ. Chromosome 17 copy number changes in male breast cancer. Cell Oncol (Dordr) 2015; 38:237-45. [PMID: 25906114 PMCID: PMC4445249 DOI: 10.1007/s13402-015-0227-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Overall, HER2-amplified female breast cancer (FBC) is associated with a high grade, an aggressive phenotype and a poor prognosis. In male breast cancer (MBC) amplification of HER2, located on chromosome 17, occurs at a lower frequency than in FBC, where it is part of complex rearrangements. So far, only few studies have addressed the occurrence of chromosome 17 alterations in small MBC cohorts. METHODS Multiplex ligation-dependent probe amplification (MLPA) and fluorescence in situ hybridization (FISH) were used to detect and characterize copy number changes on chromosome 17 in a cohort of 139 MBC. The results obtained were compared to those in FBC, and were correlated with clinicopathological features and patient outcome data. RESULTS We observed a lower frequency of chromosome 17 copy number changes with less complex rearrangement patterns in MBC compared to FBC. Chromosome 17 changes in MBC included gains of 17q and losses of 17p. Whole chromosome 17 polyploidies were not encountered. Two recurrent chromosome 17 amplicons were detected: on 17q12 (encompassing the NEUROD2, HER2, GRB7 and IKZF3 gens) and on 17q23.1 (encompassing the MIR21 and RPS6KB1 genes). Whole arm copy number gains of 17q were associated with decreased 5 year survival rates (p = 0.010). Amplification of HER2 was associated with a high tumor grade, but did not predict patient survival. Although copy number gains of HER2 and NEUROD2 were associated with a high tumor grade, a high mitotic count and a decreased 5 year survival rate (p = 0.015), only tumor size and NEUROD2 copy number gains emerged as independent prognostic factors. CONCLUSIONS In MBC chromosome 17 shows less complex rearrangements and fewer copy number changes compared to FBC. Frequent gains of 17q, encompassing two distinct amplicons, and losses of 17p were observed, but no whole chromosome 17 polyploidies. Only NEUROD2 gains seem to have an independent prognostic impact. These results suggest different roles of chromosome 17 aberrations in male versus female breast carcinogenesis.
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Affiliation(s)
- Miangela M. Lacle
- />Department of Pathology, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands
| | - Cathy B. Moelans
- />Department of Pathology, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands
| | - Robert Kornegoor
- />Department of Pathology, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands
| | - Carmen van der Pol
- />Department of Surgery, University Medical Center, Utrecht, The Netherlands
| | - Arjen J. Witkamp
- />Department of Surgery, University Medical Center, Utrecht, The Netherlands
| | - Elsken van der Wall
- />Department of Division of Oncology, University Medical Center, Utrecht, The Netherlands
| | | | - Horst Buerger
- />Institute of Pathology Paderborn/Höxter and Brustzentrum, Paderborn, Germany
| | - Paul J. van Diest
- />Department of Pathology, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands
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25
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Abstract
Mediator is a multiprotein complex that is required for gene transcription by RNA polymerase II. Multiple subunits of the complex show specificity in relaying information from signals and transcription factors to the RNA polymerase II machinery, thus enabling control of the expression of specific genes. Recent studies have also provided novel mechanistic insights into the roles of Mediator in epigenetic regulation, transcriptional elongation, termination, mRNA processing, noncoding RNA activation and super enhancer formation. Based on these specific roles in gene regulation, Mediator has emerged as a master coordinator of development and cell lineage determination. Here, we describe the most recent advances in understanding the mechanisms of Mediator function, with an emphasis on its role during development and disease.
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Affiliation(s)
- Jing-wen Yin
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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26
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Abstract
Several nuclear receptors regulate diverse metabolic functions that impact on critical biological processes, such as development, differentiation, cellular regeneration, and neoplastic conversion. In the liver, some members of the nuclear receptor family, such as peroxisome proliferator-activated receptors (PPARs), constitutive androstane receptor (CAR), farnesoid X receptor (FXR), liver X receptor (LXR), pregnane X receptor (PXR), glucocorticoid receptor (GR), and others, regulate energy homeostasis, the formation and excretion of bile acids, and detoxification of xenobiotics. Excess energy burning resulting from increases in fatty acid oxidation systems in liver generates reactive oxygen species, and the resulting oxidative damage influences liver regeneration and liver tumor development. These nuclear receptors are important sensors of exogenous activators as well as receptor-specific endogenous ligands. In this regard, gene knockout mouse models revealed that some lipid-metabolizing enzymes generate PPARα-activating ligands, while others such as ACOX1 (fatty acyl-CoA oxidase1) inactivate these endogenous PPARα activators. In the absence of ACOX1, the unmetabolized ACOX1 substrates cause sustained activation of PPARα, and the resulting increase in energy burning leads to hepatocarcinogenesis. Ligand-activated nuclear receptors recruit the multisubunit Mediator complex for RNA polymerase II-dependent gene transcription. Evidence indicates that the Med1 subunit of the Mediator is essential for PPARα, PPARγ, CAR, and GR signaling in liver. Med1 null hepatocytes fail to respond to PPARα activators in that these cells do not show induction of peroxisome proliferation and increases in fatty acid oxidation enzymes. Med1-deficient hepatocytes show no increase in cell proliferation and do not give rise to liver tumors. Identification of nuclear receptor-specific coactivators and Mediator subunits should further our understanding of the complexities of metabolic diseases associated with increased energy combustion in liver.
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Affiliation(s)
- Yuzhi Jia
- *Department of Pathology, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA
| | - Navin Viswakarma
- †Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago, Maywood, IL, USA
| | - Janardan K. Reddy
- *Department of Pathology, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA
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27
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Yu J, Xiao Y, Liu J, Ji Y, Liu H, Xu J, Jin X, Liu L, Guan MX, Jiang P. Loss of MED1 triggers mitochondrial biogenesis in C2C12 cells. Mitochondrion 2013; 14:18-25. [PMID: 24368311 DOI: 10.1016/j.mito.2013.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Revised: 10/31/2013] [Accepted: 12/12/2013] [Indexed: 01/09/2023]
Abstract
Under stress conditions transcription factors, including their coactivators, play major roles in mitochondrial biogenesis and oxidative phosphorylation. MED1 (Mediator complex subunit 1) functions as a coactivator of several transcription factors and is implicated in adipogenesis of the lipid and glucose metabolism. This suggests that MED1 may play a role in mitochondrial function. In this study, we found that both the mtDNA content and mitochondrial mass were markedly increased and cell proliferation markedly suppressed in MED1-deficient cells. Upon MED1 loss, Nrf1 and its downstream target genes involved in mitochondrial biogenesis (Tfam, Plormt, Tfb1m), were up-regulated as were those genes in the OXPHOS pathway. Moreover, the knockdown of MED1 resulted in significant changes in the profile of mitochondrial respiration, accompanied by a prominent decrease in the generation of ATP. Collectively, these observations strongly suggest that MED1 has an important affect on mitochondrial function. This further elucidates the role of MED1, particularly its role in the energy metabolism.
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Affiliation(s)
- Jialing Yu
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yun Xiao
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Junxia Liu
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yanchun Ji
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hao Liu
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jing Xu
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaofen Jin
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Li Liu
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Min-Xin Guan
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Pingping Jiang
- Department of Genetics, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
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28
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Schiano C, Casamassimi A, Rienzo M, de Nigris F, Sommese L, Napoli C. Involvement of Mediator complex in malignancy. Biochim Biophys Acta Rev Cancer 2013; 1845:66-83. [PMID: 24342527 DOI: 10.1016/j.bbcan.2013.12.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 11/28/2013] [Accepted: 12/09/2013] [Indexed: 12/22/2022]
Abstract
Mediator complex (MED) is an evolutionarily conserved multiprotein, fundamental for growth and survival of all cells. In eukaryotes, the mRNA transcription is dependent on RNA polymerase II that is associated to various molecules like general transcription factors, MED subunits and chromatin regulators. To date, transcriptional machinery dysfunction has been shown to elicit broad effects on cell proliferation, development, differentiation, and pathologic disease induction, including cancer. Indeed, in malignant cells, the improper activation of specific genes is usually ascribed to aberrant transcription machinery. Here, we focus our attention on the correlation of MED subunits with carcinogenesis. To date, many subunits are mutated or display altered expression in human cancers. Particularly, the role of MED1, MED28, MED12, CDK8 and Cyclin C in cancer is well documented, although several studies have recently reported a possible association of other subunits with malignancy. Definitely, a major comprehension of the involvement of the whole complex in cancer may lead to the identification of MED subunits as novel diagnostic/prognostic tumour markers to be used in combination with imaging technique in clinical oncology, and to develop novel anti-cancer targets for molecular-targeted therapy.
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Affiliation(s)
- Concetta Schiano
- Institute of Diagnostic and Nuclear Development (SDN), IRCCS, Via E. Gianturco 113, 80143 Naples, Italy
| | - Amelia Casamassimi
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Monica Rienzo
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy
| | - Filomena de Nigris
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy
| | - Linda Sommese
- U.O.C. Immunohematology, Transfusion Medicine and Transplant Immunology [SIMT], Regional Reference Laboratory of Transplant Immunology [LIT], Azienda Universitaria Policlinico (AOU), 1st School of Medicine, Second University of Naples, Piazza Miraglia 2, 80138 Naples, Italy
| | - Claudio Napoli
- Institute of Diagnostic and Nuclear Development (SDN), IRCCS, Via E. Gianturco 113, 80143 Naples, Italy; Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy; U.O.C. Immunohematology, Transfusion Medicine and Transplant Immunology [SIMT], Regional Reference Laboratory of Transplant Immunology [LIT], Azienda Universitaria Policlinico (AOU), 1st School of Medicine, Second University of Naples, Piazza Miraglia 2, 80138 Naples, Italy
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29
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Viswakarma N, Jia Y, Bai L, Gao Q, Lin B, Zhang X, Misra P, Rana A, Jain S, Gonzalez FJ, Zhu YJ, Thimmapaya B, Reddy JK. The Med1 subunit of the mediator complex induces liver cell proliferation and is phosphorylated by AMP kinase. J Biol Chem 2013; 288:27898-911. [PMID: 23943624 DOI: 10.1074/jbc.m113.486696] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mediator, a large multisubunit protein complex, plays a pivotal role in gene transcription by linking gene-specific transcription factors with the preinitiation complex and RNA polymerase II. In the liver, the key subunit of the Mediator complex, Med1, interacts with several nuclear receptors and transcription factors to direct gene-specific transcription. Conditional knock-out of Med1 in the liver showed that hepatocytes lacking Med1 did not regenerate following either partial hepatectomy or treatment with certain nuclear receptor activators and failed to give rise to tumors when challenged with carcinogens. We now report that the adenovirally driven overexpression of Med1 in mouse liver stimulates hepatocyte DNA synthesis with enhanced expression of DNA replication, cell cycle control, and liver-specific genes, indicating that Med1 alone is necessary and sufficient for liver cell proliferation. Importantly, we demonstrate that AMP-activated protein kinase (AMPK), an important cellular energy sensor, interacts with, and directly phosphorylates, Med1 in vitro at serine 656, serine 756, and serine 796. AMPK also phosphorylates Med1 in vivo in mouse liver and in cultured primary hepatocytes and HEK293 and HeLa cells. In addition, we demonstrate that PPARα activators increase AMPK-mediated Med1 phosphorylation in vivo. Inhibition of AMPK by compound C decreased hepatocyte proliferation induced by Med1 and also by the PPARα activators fenofibrate and Wy-14,643. Co-treatment with compound C attenuated PPARα activator-inducible fatty acid β-oxidation in liver. Our results suggest that Med1 phosphorylation by its association with AMPK regulates liver cell proliferation and fatty acid oxidation, most likely as a downstream effector of PPARα and AMPK.
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Affiliation(s)
- Navin Viswakarma
- From the Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
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30
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Zhang L, Cui J, Leonard M, Nephew K, Li Y, Zhang X. Silencing MED1 sensitizes breast cancer cells to pure anti-estrogen fulvestrant in vitro and in vivo. PLoS One 2013; 8:e70641. [PMID: 23936234 PMCID: PMC3728322 DOI: 10.1371/journal.pone.0070641] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 06/19/2013] [Indexed: 12/21/2022] Open
Abstract
Pure anti-estrogen fulvestrant has been shown to be a promising ER antagonist for locally advanced and metastatic breast cancer. Unfortunately, a significant proportion of patients developed resistance to this type of endocrine therapy but the molecular mechanisms governing cellular responsiveness to this agent remain poorly understood. Here, we’ve reported that knockdown of estrogen receptor coactivator MED1 sensitized fulvestrant resistance breast cancer cells to fulvestrant treatment. We found that MED1 knockdown further promoted cell cycle arrest induced by fulvestrant. Using an orthotopic xenograft mouse model, we found that knockdown of MED1 significantly reduced tumor growth in mice. Importantly, knockdown of MED1 further potentiated tumor growth inhibition by fulvestrant. Mechanistic studies indicated that combination of fulvestrant treatment and MED1 knockdown is able to cooperatively inhibit the expression of ER target genes. Chromatin immunoprecipitation experiments further supported a role for MED1 in regulating the recruitment of RNA polymerase II and transcriptional corepressor HDAC1 on endogenous ER target gene promoter in the presence of fulvestrant. These results demonstrate a role for MED1 in mediating resistance to the pure anti-estrogen fulvestrant both in vitro and in vivo.
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Affiliation(s)
- Lijiang Zhang
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- Institute of Biochemistry, College of Life Science, Zhejiang University, Hangzhou City, China
- Center of Safety Evaluation, Zhejiang Academy of Medical Sciences, Hangzhou City, China
| | - Jiajun Cui
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Marissa Leonard
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Kenneth Nephew
- Department of Medical Sciences, Indiana University School of Medicine, Bloomington, Indiana, United States of America
| | - Yongquan Li
- Institute of Biochemistry, College of Life Science, Zhejiang University, Hangzhou City, China
- * E-mail: (XZ); (YL)
| | - Xiaoting Zhang
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- * E-mail: (XZ); (YL)
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31
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Bernardes de Jesus B, Blasco MA. Telomerase at the intersection of cancer and aging. Trends Genet 2013; 29:513-20. [PMID: 23876621 DOI: 10.1016/j.tig.2013.06.007] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 06/07/2013] [Accepted: 06/18/2013] [Indexed: 12/16/2022]
Abstract
Although cancer and aging have been studied as independent diseases, mounting evidence suggests that cancer is an aging-associated disease and that cancer and aging share many molecular pathways. In particular, recent studies validated telomerase activation as a potential therapeutic target for age-related diseases; in addition, abnormal telomerase expression and telomerase mutations have been associated with many different types of human tumor. Here, we revisit the connection between telomerase and cancer and aging in light of recent findings supporting a role for telomerase not only in telomere elongation, but also in metabolic fitness and Wnt activation. Understanding the physiological impact of telomerase regulation is fundamental given the therapeutic strategies that are being developed that involve telomerase modulation.
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Affiliation(s)
- Bruno Bernardes de Jesus
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain
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32
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Wang X, Sun Y, Wong J, Conklin DS. PPARγ maintains ERBB2-positive breast cancer stem cells. Oncogene 2013; 32:5512-21. [PMID: 23770845 PMCID: PMC3898098 DOI: 10.1038/onc.2013.217] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 03/28/2013] [Accepted: 04/01/2013] [Indexed: 12/19/2022]
Abstract
Overexpression of the adverse prognostic marker ERBB2 occurs in 30% of breast cancers and is associated with aggressive disease and poor outcomes. Our recent findings have shown that NR1D1 and the peroxisome proliferator-activated receptor-γ (PPARγ)-binding protein (PBP) act through a common pathway in upregulating several genes in the de novo fatty acid synthesis network, which is highly active in ERBB2-positive breast cancer cells. NR1D1 and PBP are functionally related to PPARγ, a well-established positive regulator of adipogenesis and lipid storage. Here, we report that inhibition of the PPARγ pathway reduces the aldehyde dehydrogenase (ALDH)-positive population in ERBB2-positive breast cancer cells. Results from in vitro tumorsphere formation assays demonstrate that the PPARγ antagonists GW9662 and T0070907 decrease tumorsphere formation in ERBB2-positive cells, but not other breast cells. We show that the mechanism by which GW9662 treatment causes a reduction in ALDH-positive population cells is partially due to ROS, as it can be rescued by treatment with N-acetyl-cysteine. Furthermore, global gene expression analyses show that GW9662 treatment suppresses the expression of several lipogenic genes, including ACLY, MIG12, FASN and NR1D1, and the stem-cell related genes KLF4 and ALDH in BT474 cells. Antagonist treatment also decreases the level of acetylation in histone 3 and histone 4 in BT474 cells, compared with MCF7 cells. In vivo, GW9662 pre-treatment inhibits the tumor-seeding ability of BT474 cells. Together, these results show that the PPARγ pathway is critical for the cancer stem cell properties of ERBB2-positive breast cancer cells.
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Affiliation(s)
- X Wang
- Department of Biomedical Sciences, Cancer Research Center, University at Albany, State University of New York, Rensselaer, NY, USA
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33
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Grueter CE. Mediator complex dependent regulation of cardiac development and disease. Genomics Proteomics Bioinformatics 2013; 11:151-7. [PMID: 23727265 PMCID: PMC4357813 DOI: 10.1016/j.gpb.2013.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 05/09/2013] [Accepted: 05/18/2013] [Indexed: 11/22/2022]
Abstract
Cardiovascular disease (CVD) is a leading cause of morbidity and mortality. The risk factors for CVD include environmental and genetic components. Human mutations in genes involved in most aspects of cardiovascular function have been identified, many of which are involved in transcriptional regulation. The Mediator complex serves as a pivotal transcriptional regulator that functions to integrate diverse cellular signals by multiple mechanisms including recruiting RNA polymerase II, chromatin modifying proteins and non-coding RNAs to promoters in a context dependent manner. This review discusses components of the Mediator complex and the contribution of the Mediator complex to normal and pathological cardiac development and function. Enhanced understanding of the role of this core transcriptional regulatory complex in the heart will help us gain further insights into CVD.
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Affiliation(s)
- Chad E Grueter
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
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34
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Jacot W, Fiche M, Zaman K, Wolfer A, Lamy PJ. The HER2 amplicon in breast cancer: Topoisomerase IIA and beyond. Biochim Biophys Acta Rev Cancer 2013; 1836:146-57. [PMID: 23628726 DOI: 10.1016/j.bbcan.2013.04.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 04/17/2013] [Accepted: 04/19/2013] [Indexed: 12/20/2022]
Abstract
HER2 gene amplification is observed in about 15% of breast cancers. The subgroup of HER2-positive breast cancers appears to be heterogeneous and presents complex patterns of gene amplification at the locus on chromosome 17q12-21. The molecular variations within the chromosome 17q amplicon and their clinical implications remain largely unknown. Besides the well-known TOP2A gene encoding Topoisomerase IIA, other genes might also be amplified and could play functional roles in breast cancer development and progression. This review will focus on the current knowledge concerning the HER2 amplicon heterogeneity, its clinical and biological impact and the pitfalls associated with the evaluation of gene amplifications at this locus, with particular attention to TOP2A and the link between TOP2A and anthracycline benefit. In addition it will discuss the clinical and biological implications of the amplification of ten other genes at this locus (MED1, STARD3, GRB7, THRA, RARA, IGFPB4, CCR7, KRT20, KRT19 and GAST) in breast cancer.
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35
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Jin F, Irshad S, Yu W, Belakavadi M, Chekmareva M, Ittmann MM, Abate-Shen C, Fondell JD. ERK and AKT signaling drive MED1 overexpression in prostate cancer in association with elevated proliferation and tumorigenicity. Mol Cancer Res 2013; 11:736-47. [PMID: 23538858 DOI: 10.1158/1541-7786.mcr-12-0618] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
MED1 is a key coactivator of the androgen receptor (AR) and other signal-activated transcription factors. Whereas MED1 is overexpressed in prostate cancer cell lines and is thought to coactivate distinct target genes involved in cell-cycle progression and castration-resistant growth, the underlying mechanisms by which MED1 becomes overexpressed and its oncogenic role in clinical prostate cancer have remained unclear. Here, we report that MED1 is overexpressed in the epithelium of clinically localized human prostate cancer patients, which correlated with elevated cellular proliferation. In a Nkx3.1:Pten mutant mouse model of prostate cancer that recapitulates the human disease, MED1 protein levels were markedly elevated in the epithelium of both invasive and castration-resistant adenocarcinoma prostate tissues. Mechanistic evidence showed that hyperactivated ERK and/or AKT signaling pathways promoted MED1 overexpression in prostate cancer cells. Notably, ectopic MED1 overexpression in prostate cancer xenografts significantly promoted tumor growth in nude mice. Furthermore, MED1 expression in prostate cancer cells promoted the expression of a number of novel genes involved in inflammation, cell proliferation, and survival. Together, these findings suggest that elevated MED1 is a critical molecular event associated with prostate oncogenesis.
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Affiliation(s)
- Feng Jin
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, UMDNJ, 683 Hoes Lane, Piscataway, New Jersey 08854, USA
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Castellano S, Spannhoff A, Milite C, Dal Piaz F, Cheng D, Tosco A, Viviano M, Yamani A, Cianciulli A, Sala M, Cura V, Cavarelli J, Novellino E, Mai A, Bedford MT, Sbardella G. Identification of small-molecule enhancers of arginine methylation catalyzed by coactivator-associated arginine methyltransferase 1. J Med Chem 2012; 55:9875-90. [PMID: 23095008 PMCID: PMC3508294 DOI: 10.1021/jm301097p] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Arginine methylation is a common post-translational modification that is crucial in modulating gene expression at multiple critical levels. The arginine methyltransferases (PRMTs) are envisaged as promising druggable targets, but their role in physiological and pathological pathways is far from being clear due to the limited number of modulators reported to date. In this effort, enzyme activators can be invaluable tools useful as gain-of-function reagents to interrogate the biological roles in cells and in vivo of PRMTs. Yet the identification of such molecules is rarely pursued. Herein we describe a series of aryl ureido acetamido indole carboxylates (dubbed "uracandolates"), able to increase the methylation of histone (H3) or nonhistone (polyadenylate-binding protein 1, PABP1) substrates induced by coactivator-associated arginine methyltransferase 1 (CARM1), both in in vitro and cellular settings. To the best of our knowledge, this is the first report of compounds acting as CARM1 activators.
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Affiliation(s)
- Sabrina Castellano
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
| | - Astrid Spannhoff
- University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
| | - Ciro Milite
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
| | - Fabrizio Dal Piaz
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
| | - Donghang Cheng
- University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
| | - Alessandra Tosco
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
| | - Monica Viviano
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
| | - Abdellah Yamani
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
| | - Agostino Cianciulli
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
| | - Marina Sala
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
| | - Vincent Cura
- Département de Biologie Structurale Intégrative, IGBMC (Institut de Génétique et Biologie Moléculaire et Cellulaire), UDS, CNRS, INSERM, 67404 Illkirch Cedex, France
| | - Jean Cavarelli
- Département de Biologie Structurale Intégrative, IGBMC (Institut de Génétique et Biologie Moléculaire et Cellulaire), UDS, CNRS, INSERM, 67404 Illkirch Cedex, France
| | - Ettore Novellino
- Dipartimento di Chimica Farmaceutica e Tossicologica, Università di Napoli “Federico II”, Via D. Montesano 49, I-80131 Napoli, Italy
| | - Antonello Mai
- Istituto Pasteur – Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le A. Moro 5, I-00185 Roma, Italy
| | - Mark T. Bedford
- University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
| | - Gianluca Sbardella
- Dipartimento di Scienze Farmaceutiche e Biomediche, Epigenetic Med Chem Lab, Università degli Studi di Salerno, Via Ponte Don Melillo, I-84084 Fisciano (SA), Italy
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Cui J, Germer K, Wu T, Wang J, Luo J, Wang SC, Wang Q, Zhang X. Cross-talk between HER2 and MED1 regulates tamoxifen resistance of human breast cancer cells. Cancer Res 2012; 72:5625-34. [PMID: 22964581 DOI: 10.1158/0008-5472.can-12-1305] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Despite the fact that most breast cancer patients have estrogen receptor (ER) α-positive tumors, up to 50% of the patients are or soon develop resistance to endocrine therapy. It is recognized that HER2 activation is one of the major mechanisms contributing to endocrine resistance. In this study, we report that the ER coactivator MED1 is a novel cross-talk point for the HER2 and ERα pathways. Tissue microarray analysis of human breast cancers revealed that MED1 expression positively correlates most strongly with HER2 status of the tumors. MED1 was highly phosphorylated, in a HER2-dependent manner, at the site known to be critical for its activation. Importantly, RNAi-mediated attenuation of MED1 sensitized HER2-overexpressing cells to tamoxifen treatment. MED1 and its phosphorylated form, but not the corepressors N-CoR and SMRT, were recruited to the ERα target gene promoter by tamoxifen in HER2-overexpressing cells. Significantly, MED1 attenuation or mutation of MED1 phosphorylation sites was sufficient to restore the promoter recruitment of N-CoR and SMRT. Notably, we found that MED1 is required for the expression of not only traditional E2-ERα target genes but also the newly described EGF-ERα target genes. Our results additionally indicated that MED1 is recruited to the HER2 gene and required for its expression. Taken together, these findings support a key role for MED1 in HER2-mediated tamoxifen resistance and suggest its potential usage as a therapeutic target to simultaneously block both ERα and HER2 pathways for the treatment of this type of endocrine resistant breast cancer.
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Affiliation(s)
- Jiajun Cui
- Department of Cancer and Cell Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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Hulf T, Sibbritt T, Wiklund ED, Patterson K, Song JZ, Stirzaker C, Qu W, Nair S, Horvath LG, Armstrong NJ, Kench JG, Sutherland RL, Clark SJ. Epigenetic-induced repression of microRNA-205 is associated with MED1 activation and a poorer prognosis in localized prostate cancer. Oncogene 2013; 32:2891-9. [PMID: 22869146 DOI: 10.1038/onc.2012.300] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Deregulation of microRNA (miRNA) expression can have a critical role in carcinogenesis. Here we show in prostate cancer that miRNA-205 (miR-205) transcription is commonly repressed and the MIR-205 locus is hypermethylated. LOC642587, the MIR-205 host gene of unknown function, is also concordantly inactivated. We show that miR-205 targets mediator 1 (MED1, also called TRAP220 and PPARBP) for transcriptional silencing in normal prostate cells, leading to reduction in MED1 mRNA levels, and in total and active phospho-MED1 protein. Overexpression of miR-205 in prostate cancer cells negatively affects cell viability, consistent with a tumor suppressor function. We found that hypermethylation of the MIR-205 locus was strongly related with a decrease in miR-205 expression and an increase in MED1 expression in primary tumor samples (n=14), when compared with matched normal prostate (n=7). An expanded patient cohort (tumor n=149, matched normal n=30) also showed significant MIR-205 DNA methylation in tumors compared with normal, and MIR-205 hypermethylation is significantly associated with biochemical recurrence (hazard ratio=2.005, 95% confidence interval (1.109, 3.625), P=0.02), in patients with low preoperative prostate specific antigen. In summary, these results suggest that miR-205 is an epigenetically regulated tumor suppressor that targets MED1 and may provide a potential biomarker in prostate cancer management.
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Kim HJ, Roh MS, Son CH, Kim AJ, Jee HJ, Song N, Kim M, Seo SY, Yoo YH, Yun J. Loss of Med1/TRAP220 promotes the invasion and metastasis of human non-small-cell lung cancer cells by modulating the expression of metastasis-related genes. Cancer Lett 2012; 321:195-202. [DOI: 10.1016/j.canlet.2012.02.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 02/06/2012] [Accepted: 02/07/2012] [Indexed: 11/29/2022]
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Hasegawa N, Sumitomo A, Fujita A, Aritome N, Mizuta S, Matsui K, Ishino R, Inoue K, Urahama N, Nose J, Mukohara T, Kamoshida S, Roeder RG, Ito M. Mediator subunits MED1 and MED24 cooperatively contribute to pubertal mammary gland development and growth of breast carcinoma cells. Mol Cell Biol 2012; 32:1483-95. [PMID: 22331469 DOI: 10.1128/MCB.05245-11] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Mediator subunit MED1 is essential for mammary gland development and lactation, whose contribution through direct interaction with estrogen receptors (ERs) is restricted to involvement in pubertal mammary gland development and luminal cell differentiation. Here, we provide evidence that the MED24-containing submodule of Mediator functionally communicates specifically with MED1 in pubertal mammary gland development. Mammary glands from MED1/MED24 double heterozygous knockout mice showed profound retardation in ductal branching during puberty, while single haploinsufficient glands developed normally. DNA synthesis of both luminal and basal cells were impaired in double mutant mice, and the expression of ER-targeted genes encoding E2F1 and cyclin D1, which promote progression through the G(1)/S phase of the cell cycle, was attenuated. Luciferase reporter assays employing double mutant mouse embryonic fibroblasts showed selective impairment in ER functions. Various breast carcinoma cell lines expressed abundant amounts of MED1, MED24, and MED30, and attenuated expression of MED1 and MED24 in breast carcinoma cells led to attenuated DNA synthesis and growth. These results indicate functional communications between the MED1 subunit and the MED24-containing submodule that mediate estrogen receptor functions and growth of both normal mammary epithelial cells and breast carcinoma cells.
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Ries D, Meisterernst M. Control of gene transcription by Mediator in chromatin. Semin Cell Dev Biol 2011; 22:735-40. [PMID: 21864698 DOI: 10.1016/j.semcdb.2011.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/02/2011] [Accepted: 08/08/2011] [Indexed: 01/07/2023]
Abstract
The Mediator complex serves as an adaptor for regulatory factors, recruits and controls RNA polymerase II promotes preinitiation complex formation and functions post initiation. There is increasing evidence for further coordinating roles of the Mediator complex in chromatin. Here we summarize interactions with regulatory, general and accessory factors that function in transcription and chromatin.
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Affiliation(s)
- David Ries
- Institute of Molecular Tumor Biology, Westfalian Wilhelms University, Münster, Germany, Robert-Koch Strasse 43, 48149 Münster, Germany
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Borggrefe T, Yue X. Interactions between subunits of the Mediator complex with gene-specific transcription factors. Semin Cell Dev Biol 2011; 22:759-68. [PMID: 21839847 DOI: 10.1016/j.semcdb.2011.07.022] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 07/26/2011] [Accepted: 07/28/2011] [Indexed: 11/24/2022]
Abstract
The Mediator complex forms the bridge between gene-specific transcription factors and the RNA polymerase II (RNAP II) machinery. Mediator is a large polypetide complex consisting of about thirty polypeptides that are mostly conserved from yeast to human. Mediator coordinates RNAP II recruitment, phosphorylation of the C-terminal domain of RNAP II, enhancer-loop formation and post-initiation events. The focus of the review is to summarize the current knowledge of transcription factor/Mediator interactions in higher eukaryotes and illuminate the physiological and gene-selective roles of Mediator.
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Spaeth JM, Kim NH, Boyer TG. Mediator and human disease. Semin Cell Dev Biol 2011; 22:776-87. [PMID: 21840410 DOI: 10.1016/j.semcdb.2011.07.024] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 07/25/2011] [Accepted: 07/28/2011] [Indexed: 01/21/2023]
Abstract
Since the identification of a metazoan counterpart to yeast Mediator nearly 15 years ago, a convergent body of biochemical and molecular genetic studies have confirmed their structural and functional relationship as an integrative hub through which regulatory information conveyed by signal activated transcription factors is transduced to RNA polymerase II. Nonetheless, metazoan Mediator complexes have been shaped during evolution by substantive diversification and expansion in both the number and sequence of their constituent subunits, with important implications for the development of multicellular organisms. The appearance of unique interaction surfaces within metazoan Mediator complexes for transcription factors of diverse species-specific origins extended the role of Mediator to include an essential function in coupling developmentally coded signals with precise gene expression output sufficient to specify cell fate and function. The biological significance of Mediator in human development, suggested by genetic studies in lower metazoans, is emphatically illustrated by an expanding list of human pathologies linked to genetic variation or aberrant expression of its individual subunits. Here, we review our current body of knowledge concerning associations between individual Mediator subunits and specific pathological disorders. When established, molecular etiologies underlying genotype-phenotype correlations are addressed, and we anticipate that future progress in this critical area will help identify therapeutic targets across a range of human pathologies.
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Moelans CB, de Wegers RA, Monsuurs HN, Maess AH, van Diest PJ. Molecular differences between ductal carcinoma in situ and adjacent invasive breast carcinoma: a multiplex ligation-dependent probe amplification study. Cell Oncol (Dordr) 2011; 34:475-82. [PMID: 21547576 DOI: 10.1007/s13402-011-0043-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2010] [Indexed: 11/09/2022] Open
Abstract
Background Ductal carcinoma in situ (DCIS) accounts for approximately 20% of mammographically detected breast cancers. Although DCIS is generally highly curable, some women with DCIS will develop life-threatening invasive breast cancer, but the determinants of progression to infiltrating ductal cancer (IDC) are largely unknown. Methods In the current study, we used multiplex ligation-dependent probe amplification (MLPA), a multiplex PCR-based test, to compare copy numbers of 21 breast cancer related genes between laser-microdissected DCIS and adjacent IDC lesions in 39 patients. Genes included in this study were ESR1, EGFR, FGFR1, ADAM9, IKBKB, PRDM14, MTDH, MYC, CCND1, EMSY, CDH1, TRAF4, CPD, MED1, HER2, CDC6, TOP2A, MAPT, BIRC5, CCNE1 and AURKA. Results There were no significant differences in copy number for the 21 genes between DCIS and adjacent IDC. Low/intermediate-grade DCIS showed on average 6 gains/amplifications versus 8 in high-grade DCIS (p = 0.158). Furthermore, alterations of AURKA and CCNE1 were exclusively found in high-grade DCIS, and HER2, PRDM14 and EMSY amplification was more frequent in high-grade DCIS than in low/intermediate-grade DCIS. In contrast, the average number of alterations in low/intermediate and high grade IDC was similar, and although EGFR alterations were exclusively found in high grade IDC compared to low/intermediate-grade IDC, there were generally fewer differences between low/intermediate-grade and high-grade IDC than between low/intermediate-grade and high-grade DCIS. Conclusion In conclusion, there were no significant differences in copy number for 21 breast cancer related genes between DCIS and adjacent IDC, indicating that DCIS is genetically as advanced as its invasive counterpart. However, high grade DCIS showed more copy number changes than low/intermediate grade DCIS with specifically involved genes, supporting a model in which different histological grades of DCIS are associated with distinct genomic changes that progress to IDC in different routes. These high grade DCIS specific genes may be potential targets for treatment and/or predict progression. Electronic supplementary material The online version of this article (doi:10.1007/s13402-011-0043-7) contains supplementary material, which is available to authorized users.
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Zhang D, Jiang P, Xu Q, Zhang X. Arginine and glutamate-rich 1 (ARGLU1) interacts with mediator subunit 1 (MED1) and is required for estrogen receptor-mediated gene transcription and breast cancer cell growth. J Biol Chem 2011; 286:17746-54. [PMID: 21454576 DOI: 10.1074/jbc.m110.206029] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Estrogen receptor is a nuclear receptor superfamily member of transcriptional activators that regulate gene expression by recruiting diverese transcriptional coregulators. The Mediator complex is a central transcriptional coactivator complex that acts as a bridge between transcriptional activators and RNA polymerase II. MED1 (Mediator subunit 1) is the key Mediator subunit that directly interacts with estrogen receptor to mediate its functions both in vitro and in vivo. Interestingly, our previous biochemical analyses indicated that MED1 exists only in a subpopulation of the Mediator complex that is enriched with a number of distinct Mediator subunits and RNA polymerase II. Here, we report ARGLU1 as a MED1/Mediator-associated protein. We found that ARGLU1 (arginine and glutamate rich 1) not only colocalizes with MED1 in the nucleus, but also directly interacts with a far C-terminal region of MED1. Reporter assays indicate that ARGLU1 is able to cooperate with MED1 to regulate estrogen receptor-mediated gene transcription. Importantly, ARGLU1 is recruited, in a ligand-dependent manner, to endogenous estrogen receptor target gene promoters and is required for their expression. Furthermore, by ChIP-reChIP assay, we confirm that ARGLU1 and MED1 colocalize on the same estrogen receptor target gene promoter upon estrogen induction. Moreover, we found that depletion of ARGLU1 significantly impairs the growth, as well as anchorage-dependent and -independent colony formation of breast cancer cells. Taken together, these results establish ARGLU1 as a new MED1-interacting protein required for estrogen-dependent gene transcription and breast cancer cell growth.
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Affiliation(s)
- Dingxiao Zhang
- Department of Cancer and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267, USA
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Yun J, Son CH, Um SJ, Kwon HC, Lee KE, Choi PJ, Roh MS. A different TRAP220 expression in distinct histologic subtypes of lung adenocarcinoma and the prognostic significance. Lung Cancer 2011; 71:312-8. [DOI: 10.1016/j.lungcan.2010.06.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 04/27/2010] [Accepted: 06/21/2010] [Indexed: 12/01/2022]
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Abstract
The Mediator is an evolutionarily conserved, multiprotein complex that is a key regulator of protein-coding genes. In metazoan cells, multiple pathways that are responsible for homeostasis, cell growth and differentiation converge on the Mediator through transcriptional activators and repressors that target one or more of the almost 30 subunits of this complex. Besides interacting directly with RNA polymerase II, Mediator has multiple functions and can interact with and coordinate the action of numerous other co-activators and co-repressors, including those acting at the level of chromatin. These interactions ultimately allow the Mediator to deliver outputs that range from maximal activation of genes to modulation of basal transcription to long-term epigenetic silencing.
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Affiliation(s)
- Sohail Malik
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, 1230 York Avenue, New York, New York 10065, USA.
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Viswakarma N, Jia Y, Bai L, Vluggens A, Borensztajn J, Xu J, Reddy JK. Coactivators in PPAR-Regulated Gene Expression. PPAR Res. 2010;2010. [PMID: 20814439 PMCID: PMC2929611 DOI: 10.1155/2010/250126] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 07/01/2010] [Indexed: 01/01/2023] Open
Abstract
Peroxisome proliferator-activated receptor (PPAR)alpha, beta (also known as delta), and gamma function as sensors for fatty acids and fatty acid derivatives and control important metabolic pathways involved in the maintenance of energy balance. PPARs also regulate other diverse biological processes such as development, differentiation, inflammation, and neoplasia. In the nucleus, PPARs exist as heterodimers with retinoid X receptor-alpha bound to DNA with corepressor molecules. Upon ligand activation, PPARs undergo conformational changes that facilitate the dissociation of corepressor molecules and invoke a spatiotemporally orchestrated recruitment of transcription cofactors including coactivators and coactivator-associated proteins. While a given nuclear receptor regulates the expression of a prescribed set of target genes, coactivators are likely to influence the functioning of many regulators and thus affect the transcription of many genes. Evidence suggests that some of the coactivators such as PPAR-binding protein (PBP/PPARBP), thyroid hormone receptor-associated protein 220 (TRAP220), and mediator complex subunit 1 (MED1) may exert a broader influence on the functions of several nuclear receptors and their target genes. Investigations into the role of coactivators in the function of PPARs should strengthen our understanding of the complexities of metabolic diseases associated with energy metabolism.
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Li Y, Li Y, Zhang T, Chan WK. The aryl hydrocarbon receptor nuclear translocator-interacting protein 2 suppresses the estrogen receptor signaling via an Arnt-dependent mechanism. Arch Biochem Biophys 2010; 502:121-9. [PMID: 20674540 DOI: 10.1016/j.abb.2010.07.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 07/16/2010] [Accepted: 07/21/2010] [Indexed: 10/19/2022]
Abstract
We explored whether modulation of the estrogen receptor (ER) signaling is possible through an aryl hydrocarbon receptor nuclear translocator (Arnt)-dependent mechanism. We utilized the Arnt-interacting protein 2 (Ainp2) to examine whether the presence of Ainp2 in MCF-7 cells would interfere with the Arnt-mediated ER signaling. We found that Arnt increased the 17 beta-estradiol (E2)-dependent luciferase activity and Ainp2 significantly suppressed this Arnt-mediated luciferase activity. Ainp2 significantly suppressed 25% of the E2- and Arnt-dependent up-regulation of the GREB1 message. No suppression of the ER target gene expression by Ainp2 was detected in Arnt-knockdown MCF-7 cells and in Arnt-independent ER signaling. Although Ainp2 did not interact with ER alpha and ER beta, it suppressed the ER alpha::Arnt interaction and reduced the E2-driven recruitment of Arnt to the GREB1 promoter. We concluded that Ainp2 suppresses the ER signaling by not allowing Arnt to participate in the ER-dependent, Arnt-mediated activation of gene transcription.
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Affiliation(s)
- Yanjie Li
- Department of Pharmaceutics and Medicinal Chemistry, University of the Pacific, Stockton, CA 95211, USA
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Fan J, Traore K, Li W, Amri H, Huang H, Wu C, Chen H, Zirkin B, Papadopoulos V. Molecular mechanisms mediating the effect of mono-(2-ethylhexyl) phthalate on hormone-stimulated steroidogenesis in MA-10 mouse tumor Leydig cells. Endocrinology 2010; 151:3348-62. [PMID: 20463053 PMCID: PMC2903930 DOI: 10.1210/en.2010-0010] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Di-(2-ethylhexyl) phthalate, a widely used plasticizer, and its active metabolite, mono-(2-ethylhexyl) phthalate (MEHP), have been shown to exert adverse effects on the reproductive tract in developing and adult animals. As yet, however, the molecular mechanisms by which they act are uncertain. In the present study, we address the molecular and cellular mechanisms underlying the effects of MEHP on basal and human chorionic gonadotropin (hCG)-stimulated steroid production by MA-10 Leydig cells, using a systems biology approach. MEHP induced dose-dependent decreases in hCG-stimulated steroid formation. Changes in mRNA and protein expression in cells treated with increasing concentrations of MEHP in the presence or absence of hCG were measured by gene microarray and protein high-throughput immunoblotting analyses, respectively. Expression profiling indicated that low concentrations of MEHP induced the expression of a number of genes that also were expressed after hCG stimulation. Cross-comparisons between the hCG and MEHP treatments revealed two genes, Anxa1 and AR1. We suggest that these genes may be involved in a new self-regulatory mechanism of steroidogenesis. The MEHP-induced decreases in hCG-stimulated steroid formation were paralleled by increases in reactive oxygen species generation, with the latter mediated by the Cyp1a1 gene and its network. A model for the mechanism of MEHP action on MA-10 Leydig cell steroidogenesis is proposed.
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Affiliation(s)
- Jinjiang Fan
- The Research Institute of the McGill University Health Centre, Montreal General Hospital, 1650 Cedar Avenue, Room C10-148, Montreal, Quebec, Canada H3G 1A4
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