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Klinge CM. miRNAs regulated by estrogens, tamoxifen, and endocrine disruptors and their downstream gene targets. Mol Cell Endocrinol 2015; 418 Pt 3:273-97. [PMID: 25659536 PMCID: PMC4523495 DOI: 10.1016/j.mce.2015.01.035] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 01/22/2015] [Accepted: 01/23/2015] [Indexed: 02/07/2023]
Abstract
MicroRNAs (miRNAs) are short (22 nucleotides), single-stranded, non-coding RNAs that form complimentary base-pairs with the 3' untranslated region of target mRNAs within the RNA-induced silencing complex (RISC) and block translation and/or stimulate mRNA transcript degradation. The non-coding miRBase (release 21, June 2014) reports that human genome contains ∼ 2588 mature miRNAs which regulate ∼ 60% of human protein-coding mRNAs. Dysregulation of miRNA expression has been implicated in estrogen-related diseases including breast cancer and endometrial cancer. The mechanism for estrogen regulation of miRNA expression and the role of estrogen-regulated miRNAs in normal homeostasis, reproduction, lactation, and in cancer is an area of great research and clinical interest. Estrogens regulate miRNA transcription through estrogen receptors α and β in a tissue-specific and cell-dependent manner. This review focuses primarily on the regulation of miRNA expression by ligand-activated ERs and their bona fide gene targets and includes miRNA regulation by tamoxifen and endocrine disrupting chemicals (EDCs) in breast cancer and cell lines.
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Affiliation(s)
- Carolyn M Klinge
- Department of Biochemistry & Molecular Biology, Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, KY 40292, USA.
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Alqahtani H, Gopal K, Gupta N, Jung K, Alshareef A, Ye X, Wu F, Li L, Lai R. DDX17 (P72), a Sox2 binding partner, promotes stem-like features conferred by Sox2 in a small cell population in estrogen receptor-positive breast cancer. Cell Signal 2015; 28:42-50. [PMID: 26569340 DOI: 10.1016/j.cellsig.2015.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 11/09/2015] [Indexed: 12/20/2022]
Abstract
We have previously demonstrated the existence of two phenotypically distinct cell subsets in estrogen receptor (ER)-positive breast cancer (BC) based on their differential response to a Sox2 reporter (SRR2), with reporter responsive (RR) cells being more tumorigenic and stem-like than reporter unresponsive (RU) cells. To delineate the molecular mechanisms underlying this phenotypic dichotomy, we tested our hypothesis that Sox2, which is a key regulator of the RR phenotype, is under the control of its binding partners. In this study, we focused on DDX17, known to be a transcription co-activator and found to be a Sox2 binding partner by liquid chromatography-mass spectrometry. Using immunoprecipitation, we confirmed the binding between DDX17 and Sox2, although this interaction was largely restricted to RR cells. While DDX17 was found in both the cytoplasm and nuclei in RU cells, it is confined to the nuclei in RR cells. siRNA knockdown of DDX17 in RR cells substantially decreased the Sox2-SRR2 binding and significantly decreased the SRR2 reporter activity without affecting the protein level of Sox2. Using ChIP-PCR, DDX17 knockdown also significantly decreased the binding of Sox2 to genomic SRR2, as well as 3 of its specific gene targets including MUC15, CCND1 and CD133. Correlating with these findings, siRNA knockdown of DDX17 significantly reduced soft agar colony formation and mammosphere formation in RR cells but not RU cells. To conclude, DDX17 is a Sox2-binding protein in ER-positive BC. In RR but not RU cells, DDX17 enhances the tumorigenic and stem-like features of Sox2 by promoting its binding to its target genes.
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Affiliation(s)
- H Alqahtani
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - K Gopal
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - N Gupta
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - K Jung
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - A Alshareef
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - X Ye
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - F Wu
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - L Li
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - R Lai
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada; Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.
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Wang Z, Liu W, Zhou N, Wang H, Li P, Wang M, Zhang Q. Molecular characterization, origin, and evolution of teleost p68 gene family: Insights from Japanese flounder, Paralichthys olivaceus. Mar Genomics 2015; 24 Pt 3:363-70. [PMID: 26388449 DOI: 10.1016/j.margen.2015.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 11/26/2022]
Abstract
Two rounds of whole-genome duplication occurred in the common ancestor of vertebrates. Later, a third round genome duplication occurred in the teleost fishes. As a prototype member of DEAD-box RNA helicases, the function of p68 helicase in development has been well investigated in human, however, limited information is available regarding the regulatory function of this gene in the development of teleosts. In this study, being an important farmed fish in North China, Japanese flounder (Paralichthys olivaceus) was used as model fish to investigate the role of p68 gene in teleost development. Two p68 genes were first identified from Japanese flounder. Molecular characterization of them was performed by analyzing the exon-intron boundaries. Then, we confirmed that such two teleost p68 genes originated from teleost-specific genome duplication through phylogenetic and synteny analyses. Additionally, comparative analyses of amino acid sequences, variation in selective pressure, and expression profiles of p68 genes revealed probable sub-functionalization fate of teleost p68 genes after the duplication. Therefore, this study supplements the evolutionary properties of teleost p68 gene family and provides the groundwork for further studying the regulatory function of p68 genes in the development of teleosts.
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Affiliation(s)
- Zhongkai Wang
- Key Laboratory for Sustainable Utilization of Marine Fisheries Resources of Chinese Department of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, China; Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Wei Liu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Nayu Zhou
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Huizhen Wang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Peizhen Li
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Mengxun Wang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Quanqi Zhang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
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54
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Redmond AM, Byrne C, Bane FT, Brown GD, Tibbitts P, O'Brien K, Hill ADK, Carroll JS, Young LS. Genomic interaction between ER and HMGB2 identifies DDX18 as a novel driver of endocrine resistance in breast cancer cells. Oncogene 2015; 34:3871-80. [PMID: 25284587 DOI: 10.1038/onc.2014.323] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 08/04/2014] [Accepted: 08/24/2014] [Indexed: 01/01/2023]
Abstract
Breast cancer resistance to endocrine therapies such as tamoxifen and aromatase inhibitors is a significant clinical problem. Steroid receptor coactivator-1 (SRC-1), a coregulatory protein of the oestrogen receptor (ER), has previously been shown to have a significant role in the progression of breast cancer. The chromatin protein high mobility group box 2 (HMGB2) was identified as an SRC-1 interacting protein in the endocrine-resistant setting. We investigated the expression of HMGB2 in a cohort of 1068 breast cancer patients and found an association with increased disease-free survival time in patients treated with endocrine therapy. However, it was also verified that HMGB2 expression could be switched on in endocrine-resistant tumours from breast cancer patients. To explore the function of this poorly characterized protein, we performed HMGB2 ChIPseq and found distinct binding patterns between the two contexts. In the resistant setting, the HMGB2, SRC-1 and ER complex are enriched at promoter regions of target genes, with bioinformatic analysis indicating a switch in binding partners between the sensitive and resistant phenotypes. Integration of binding and gene expression data reveals a concise set of target genes of this complex including the RNA helicase DDX18. Modulation of DDX18 directly affects growth of tamoxifen-resistant cells, suggesting that it may be a critical downstream effector of the HMGB2:ER complex. This study defines HMGB2 interactions with the ER complex at specific target genes in the tamoxifen-resistant setting.
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MESH Headings
- Animals
- Antineoplastic Agents, Hormonal/pharmacology
- Antineoplastic Agents, Hormonal/therapeutic use
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Cell Line, Tumor
- Cell Proliferation/genetics
- DEAD-box RNA Helicases/genetics
- DEAD-box RNA Helicases/metabolism
- Drug Resistance, Neoplasm/genetics
- Female
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic
- HMGB2 Protein/genetics
- HMGB2 Protein/metabolism
- Humans
- Kaplan-Meier Estimate
- MCF-7 Cells
- Mice, Inbred BALB C
- Mice, SCID
- Nuclear Receptor Coactivator 1/genetics
- Nuclear Receptor Coactivator 1/metabolism
- Oligonucleotide Array Sequence Analysis
- Promoter Regions, Genetic/genetics
- Protein Binding
- RNA Interference
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Tamoxifen/pharmacology
- Tamoxifen/therapeutic use
- Xenograft Model Antitumor Assays
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Affiliation(s)
- A M Redmond
- 1] Endocrine Oncology Research Group, Department of Surgery, Royal College of Surgeons in Ireland, Dublin, Ireland [2] Cancer Research UK, Cambridge Institute, University of Cambridge, Cambridge, UK
| | - C Byrne
- Endocrine Oncology Research Group, Department of Surgery, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - F T Bane
- Endocrine Oncology Research Group, Department of Surgery, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - G D Brown
- Cancer Research UK, Cambridge Institute, University of Cambridge, Cambridge, UK
| | - P Tibbitts
- Endocrine Oncology Research Group, Department of Surgery, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - K O'Brien
- Endocrine Oncology Research Group, Department of Surgery, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - A D K Hill
- Endocrine Oncology Research Group, Department of Surgery, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - J S Carroll
- Cancer Research UK, Cambridge Institute, University of Cambridge, Cambridge, UK
| | - L S Young
- Endocrine Oncology Research Group, Department of Surgery, Royal College of Surgeons in Ireland, Dublin, Ireland
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55
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Lentiviral DDX46 knockdown inhibits growth and induces apoptosis in human colorectal cancer cells. Gene 2015; 560:237-44. [DOI: 10.1016/j.gene.2015.02.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 01/26/2015] [Accepted: 02/08/2015] [Indexed: 12/11/2022]
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Abstract
miRNAs are important regulatory elements for gene expression that are involved in diverse physiologic and pathologic processes. Canonical miRNA biogenesis consists of a two-step processing, from primary transcripts (pri-miRNA) to precursor miRNAs (pre-miRNA) mediated by Drosha in the nucleus and from pre-miRNAs to mature miRNAs mediated by Dicer in the cytoplasm. Various routes of miRNA maturation that are tightly regulated by signaling cascades and specific to an individual or a subclass of miRNAs have been recently identified. Here, we review the current findings in signaling-mediated miRNA processing as well as their potential clinical relevance in cancer.
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Affiliation(s)
- Jia Shen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas
| | - Mien-Chie Hung
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas. Center for Molecular Medicine and Graduate Institute of Cancer Biology, China Medical University, Taichung, Taiwan. Asia University, Taichung, Taiwan.
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57
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Zhang Y, Baysac KC, Yee LF, Saporita AJ, Weber JD. Elevated DDX21 regulates c-Jun activity and rRNA processing in human breast cancers. Breast Cancer Res 2014; 16:449. [PMID: 25260534 PMCID: PMC4303128 DOI: 10.1186/s13058-014-0449-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 09/19/2014] [Indexed: 12/21/2022] Open
Abstract
INTRODUCTION The DDX21 RNA helicase has been shown to be a nucleolar and nuclear protein involved in ribosome RNA processing and AP-1 transcription. DDX21 is highly expressed in colon cancer, lymphomas, and some breast cancers, but little is known about how DDX21 might promote tumorigenesis. METHODS Immunohistochemistry was performed on a breast cancer tissue array of 187 patients. In order to study the subcellular localization of DDX21 in both tumor tissue and tumor cell lines, indirect immunofluorescence was applied. The effect of DDX21 knockdown was measured by cellular apoptosis, rRNA processing assays, soft agar growth and mouse xenograft imaging. AP-1 transcriptional activity was analyzed with a luciferase reporter and bioluminescence imaging, as well as qRT-PCR analysis of downstream target, cyclin D1, to determine the mechanism of action for DDX21 in breast tumorigenesis. RESULTS Herein, we show that DDX21 is highly expressed in breast cancer tissues and established cell lines. A significant number of mammary tumor tissues and established breast cancer cell lines exhibit nuclear but not nucleolar localization of DDX21. The protein expression level of DDX21 correlates with cell proliferation rate and is markedly induced by EGF signaling. Mechanistically, DDX21 is required for the phosphorylation of c-Jun on Ser73 and DDX21 deficiency markedly reduces the transcriptional activity of AP-1. Additionally, DDX21 promotes rRNA processing in multiple breast cancer cell lines. Tumor cells expressing high levels of endogenous DDX21 undergo apoptosis after acute DDX21 knockdown, resulting in significant reduction of tumorigenicity in vitro and in vivo. CONCLUSIONS Our findings indicate that DDX21 expression in breast cancer cells can promote AP-1 activity and rRNA processing, and thus, promote tumorigenesis by two independent mechanisms. DDX21 could serve as a marker for a subset of breast cancer patients with higher proliferation potential and may be used as a therapeutic target for a subset of breast cancer patients.
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58
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Dai TY, Cao L, Yang ZC, Li YS, Tan L, Ran XZ, Shi CM. P68 RNA helicase as a molecular target for cancer therapy. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2014; 33:64. [PMID: 25150365 PMCID: PMC4431487 DOI: 10.1186/s13046-014-0064-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/16/2014] [Indexed: 12/23/2022]
Abstract
The DEAD-box family of RNA helicase is known to be required in virtually all cellular processes involving RNA, and p68 is a prototypic one of the family. Reports have indicated that in addition to ATPase and RNA helicase ability, p68 can also function as a co-activator for transcription factors such as estrogen receptor alpha, tumor suppressor p53 and beta-catenin. More than that, post-translational modification of p68 including phosphorylation, acetylation, sumoylation, and ubiquitylation can regulate the coactivation effect. Furthermore, aberrant expression of p68 in cancers highlights that p68 plays an important role for tumorgenesis and development. In this review, we briefly introduce the function and modulation of p68 in cancer cells, and put forward envisagement about future study about p68.
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Affiliation(s)
- Ting-Yu Dai
- Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing Engineering Research Center for Nanomedicine, Department of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.
| | - Liu Cao
- Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing Engineering Research Center for Nanomedicine, Department of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.
| | - Zi-Chen Yang
- Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing Engineering Research Center for Nanomedicine, Department of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.
| | - Ya-Shu Li
- Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing Engineering Research Center for Nanomedicine, Department of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.
| | - Li Tan
- Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing Engineering Research Center for Nanomedicine, Department of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.
| | - Xin-Ze Ran
- Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing Engineering Research Center for Nanomedicine, Department of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.
| | - Chun-Meng Shi
- Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing Engineering Research Center for Nanomedicine, Department of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.
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59
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Mazurek A, Park Y, Miething C, Wilkinson JE, Gillis J, Lowe SW, Vakoc CR, Stillman B. Acquired dependence of acute myeloid leukemia on the DEAD-box RNA helicase DDX5. Cell Rep 2014; 7:1887-99. [PMID: 24910429 DOI: 10.1016/j.celrep.2014.05.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 04/15/2014] [Accepted: 05/09/2014] [Indexed: 12/27/2022] Open
Abstract
Acute myeloid leukemia (AML) therapy involves compounds that are cytotoxic to both normal and cancer cells, and relapsed AML is resistant to subsequent chemotherapy. Thus, agents are needed that selectively kill AML cells with minimal toxicity. Here, we report that AML is dependent on DDX5 and that inhibiting DDX5 expression slows AML cell proliferation in vitro and AML progression in vivo but is not toxic to cells from normal bone marrow. Inhibition of DDX5 expression in AML cells induces apoptosis via induction of reactive oxygen species (ROS). This apoptotic response can be blocked either by BCL2 overexpression or treatment with the ROS scavenger N-acetyl-L-cysteine. Combining DDX5 knockdown with a BCL2 family inhibitor cooperates to induce cell death in AML cells. By inhibiting DDX5 expression in vivo, we show that DDX5 is dispensable for normal hematopoiesis and tissue homeostasis. These results validate DDX5 as a potential target for blocking AML.
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Affiliation(s)
- Anthony Mazurek
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Youngkyu Park
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Cornelius Miething
- Memorial Sloan-Kettering Cancer Center, 415 E. 68(th) Street, Box 373, New York, NY 10065, USA
| | - John E Wilkinson
- Unit for Laboratory Animal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jesse Gillis
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Scott W Lowe
- Memorial Sloan-Kettering Cancer Center, 415 E. 68(th) Street, Box 373, New York, NY 10065, USA
| | - Christopher R Vakoc
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Bruce Stillman
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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60
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HAGE (DDX43) is a biomarker for poor prognosis and a predictor of chemotherapy response in breast cancer. Br J Cancer 2014; 110:2450-61. [PMID: 24755885 PMCID: PMC4021517 DOI: 10.1038/bjc.2014.168] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/28/2014] [Accepted: 03/05/2014] [Indexed: 01/10/2023] Open
Abstract
Background: HAGE protein is a known immunogenic cancer-specific antigen. Methods: The biological, prognostic and predictive values of HAGE expression was studied using immunohistochemistry in three cohorts of patients with BC (n=2147): early primary (EP-BC; n=1676); primary oestrogen receptor-negative (PER-BC; n=275) treated with adjuvant anthracycline-combination therapies (Adjuvant-ACT); and primary locally advanced disease (PLA-BC) who received neo-adjuvant anthracycline-combination therapies (Neo-adjuvant-ACT; n=196). The relationship between HAGE expression and the tumour-infiltrating lymphocytes (TILs) in matched prechemotherapy and postchemotherapy samples were investigated. Results: Eight percent of patients with EP-BC exhibited high HAGE expression (HAGE+) and was associated with aggressive clinico-pathological features (Ps<0.01). Furthermore, HAGE+expression was associated with poor prognosis in both univariate and multivariate analysis (Ps<0.001). Patients with HAGE+did not benefit from hormonal therapy in high-risk ER-positive disease. HAGE+and TILs were found to be independent predictors for pathological complete response to neoadjuvant-ACT; P<0.001. A statistically significant loss of HAGE expression following neoadjuvant-ACT was found (P=0.000001), and progression-free survival was worse in those patients who had HAGE+residual disease (P=0.0003). Conclusions: This is the first report to show HAGE to be a potential prognostic marker and a predictor of response to ACT in patients with BC.
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61
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Regulation of estrogen receptor signaling in breast carcinogenesis and breast cancer therapy. Cell Mol Life Sci 2014; 71:1549. [PMID: 25031550 PMCID: PMC3962223 DOI: 10.1007/s00018-013-1376-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 05/15/2013] [Accepted: 05/16/2013] [Indexed: 12/19/2022]
Abstract
Estrogen and estrogen receptors (ERs) are critical regulators of breast epithelial cell proliferation, differentiation, and apoptosis. Compromised signaling vis-à-vis the estrogen receptor is believed to be a major contributing factor in the malignancy of breast cells. Targeting the ER signaling pathway has been a focal point in the development of breast cancer therapy. Although approximately 75 % of breast cancer patients are classified as luminal type (ER(+)), which predicts for response to endocrine-based therapy; however, innate or acquired resistance to endocrine-based drugs remains a serious challenge. The complexity of regulation for estrogen signaling coupled with the crosstalk of other oncogenic signaling pathways is a reason for endocrine therapy resistance. Alternative strategies that target novel molecular mechanisms are necessary to overcome this current and urgent gap in therapy. A thorough analysis of estrogen-signaling regulation is critical. In this review article, we will summarize current insights into the regulation of estrogen signaling as related to breast carcinogenesis and breast cancer therapy.
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62
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Iyer RS, Nicol SM, Quinlan PR, Thompson AM, Meek DW, Fuller-Pace FV. The RNA helicase/transcriptional co-regulator, p68 (DDX5), stimulates expression of oncogenic protein kinase, Polo-like kinase-1 (PLK1), and is associated with elevated PLK1 levels in human breast cancers. Cell Cycle 2014; 13:1413-23. [PMID: 24626184 PMCID: PMC4050139 DOI: 10.4161/cc.28415] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/03/2014] [Accepted: 03/03/2014] [Indexed: 12/12/2022] Open
Abstract
p68 (DDX5) acts both as an ATP-dependent RNA helicase and as a transcriptional co-activator of several cancer-associated transcription factors, including the p53 tumor suppressor. p68 is aberrantly expressed in a high proportion of cancers, but the oncogenic drive for, or the consequences of, these expression changes remain unclear. Here we show that elevated p68 expression in a cohort of human breast cancers is associated significantly with elevated levels of the oncogenic protein kinase, Polo-like kinase-1 (PLK1). Patients expressing detectable levels of both p68 and PLK1 have a poor prognosis, but only if they also have mutation in the TP53 gene (encoding p53), suggesting that p68 can regulate PLK1 levels in a manner that is suppressed by p53. In support of this hypothesis, we show that p68 stimulates expression from the PLK1 promoter, and that silencing of endogenous p68 expression downregulates endogenous PLK1 gene expression. In the absence of functional p53, p68 stimulates the expression of PLK1 both at basal levels and in response to the clinically relevant drug, etoposide. In keeping with a role as a transcriptional activator/co-activator, chromatin immuno-precipitation analysis shows that p68 is associated with the PLK1 promoter, irrespective of the p53 status. However, its recruitment is stimulated by etoposide in cells lacking p53, suggesting that p53 can oppose association of p68 with the PLK1 promoter. These data provide a model in which p68 and p53 interplay regulates PLK1 expression, and which describes the behavior of these molecules, and the outcome of their interaction, in human breast cancer.
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Affiliation(s)
| | | | - Philip R Quinlan
- Division of Cancer Research; University of Dundee; Ninewells Hospital & Medical School; Dundee, UK
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63
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Prep1 and Meis1 competition for Pbx1 binding regulates protein stability and tumorigenesis. Proc Natl Acad Sci U S A 2014; 111:E896-905. [PMID: 24578510 DOI: 10.1073/pnas.1321200111] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pbx-regulating protein-1 (Prep1) is a tumor suppressor, whereas myeloid ecotropic viral integration site-1 (Meis1) is an oncogene. We show that, to perform these activities in mouse embryonic fibroblasts, both proteins competitively heterodimerize with pre-B-cell leukemia homeobox-1 (Pbx1). Meis1 alone transforms Prep1-deficient fibroblasts, whereas Prep1 overexpression inhibits Meis1 tumorigenicity. Pbx1 can, therefore, alternatively act as an oncogene or tumor suppressor. Prep1 posttranslationally controls the level of Meis1, decreasing its stability by sequestering Pbx1. The different levels of Meis1 and the presence of Prep1 are followed at the transcriptional level by the induction of specific transcriptional signatures. The decrease of Meis1 prevents Meis1 interaction with Ddx3x and Ddx5, which are essential for Meis1 tumorigenesis, and modifies the growth-promoting DNA binding landscape of Meis1 to the growth-controlling landscape of Prep1. Hence, the key feature of Prep1 tumor-inhibiting activity is the control of Meis1 stability.
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64
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Samaan S, Tranchevent LC, Dardenne E, Polay Espinoza M, Zonta E, Germann S, Gratadou L, Dutertre M, Auboeuf D. The Ddx5 and Ddx17 RNA helicases are cornerstones in the complex regulatory array of steroid hormone-signaling pathways. Nucleic Acids Res 2013; 42:2197-207. [PMID: 24275493 PMCID: PMC3936752 DOI: 10.1093/nar/gkt1216] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Estrogen and androgen receptors (ER and AR) play key roles in breast and prostate cancers, respectively, where they regulate the transcription of large arrays of genes. The activities of ER and AR are controlled by large networks of protein kinases and transcriptional coregulators, including Ddx5 and its highly related paralog Ddx17. The Ddx5 and Ddx17 RNA helicases are also splicing regulators. Here, we report that Ddx5 and Ddx17 are master regulators of the estrogen- and androgen-signaling pathways by controlling transcription and splicing both upstream and downstream of the receptors. First, Ddx5 and Ddx17 are required downstream of ER and AR for the transcriptional and splicing regulation of a large number of steroid hormone target genes. Second, Ddx5 and Ddx17 act upstream of ER and AR by controlling the expression, at the splicing level, of several key regulators of ER and AR activities. Of particular interest, we demonstrate that Ddx5 and Ddx17 control alternative splicing of the GSK3β kinase, which impacts on both ER and AR protein stability. We also provide a freely available online resource which gives information regarding splicing variants of genes involved in the estrogen- and androgen-signaling pathways.
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Affiliation(s)
- Samaan Samaan
- Université de Paris Diderot-Paris 7, F-75013 Paris, France, Inserm U1052, F-69008 Lyon, France, CNRS UMR5286, F-69008 Lyon, France, Centre de Recherche en Cancérologie de Lyon, 69008 Lyon, France and Université de Lyon 1, F-69100 Villeurbanne, France
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65
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Geißler V, Altmeyer S, Stein B, Uhlmann-Schiffler H, Stahl H. The RNA helicase Ddx5/p68 binds to hUpf3 and enhances NMD of Ddx17/p72 and Smg5 mRNA. Nucleic Acids Res 2013; 41:7875-88. [PMID: 23788676 PMCID: PMC3763533 DOI: 10.1093/nar/gkt538] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Non-sense-mediated mRNA decay (NMD) is a mechanism of translation-dependent mRNA surveillance in eukaryotes: it degrades mRNAs with premature termination codons (PTCs) and contributes to cellular homeostasis by downregulating a number of physiologically important mRNAs. In the NMD pathway, Upf proteins, a set of conserved factors of which Upf1 is the central regulator, recruit decay enzymes to promote RNA cleavage. In mammals, the degradation of PTC-containing mRNAs is triggered by the exon–junction complex (EJC) through binding of its constituents Upf2 and Upf3 to Upf1. The complex formed eventually induces translational repression and recruitment of decay enzymes. Mechanisms by which physiological mRNAs are targeted by the NMD machinery in the absence of an EJC have been described but still are discussed controversially. Here, we report that the DEAD box proteins Ddx5/p68 and its paralog Ddx17/p72 also bind the Upf complex by physical interaction with Upf3, thereby interfering with the binding of EJC. By activating the NMD machinery, Ddx5 is shown to regulate the expression of its own, Ddx17 and Smg5 mRNAs. For NMD triggering, the adenosine triphosphate-binding activity of Ddx5 and the 3′-untranslated region of substrate mRNAs are essential.
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Affiliation(s)
- Verena Geißler
- Department of Medical Biochemistry and Molecular Biology, University of Saarland, Medical Center, Building 45, 66421 Homburg, Germany
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66
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Lorgeoux RP, Pan Q, Le Duff Y, Liang C. DDX17 promotes the production of infectious HIV-1 particles through modulating viral RNA packaging and translation frameshift. Virology 2013; 443:384-92. [PMID: 23769241 DOI: 10.1016/j.virol.2013.05.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 03/24/2013] [Accepted: 05/18/2013] [Indexed: 01/13/2023]
Abstract
RNA helicases are a large family of proteins that rearrange RNA structures and remodel ribonucleic protein complexes using energy derived from hydrolysis of nucleotide triphosphates. They have been shown to participate in every step of RNA metabolism. In the past decade, an increasing number of helicases were shown to promote or inhibit the replication of different viruses, including human immunodeficiency virus type 1. Among these helicases, the DEAD-box RNA helicase DDX17 was recently reported to modulate HIV-1 RNA stability and export. In this study, we further show that the helicase activity of DDX17 is required for the production of infectious HIV-1 particles. Over expression of the DDX17 mutant DQAD in HEK293 cells reduces the amount of packaged viral genomic RNA and diminishes HIV-1 Gag-Pol frameshift. Altogether, these data demonstrate that DDX17 promotes the production of HIV-1 infectious particles by modulating HIV-1 RNA metabolism.
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67
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Fuller-Pace FV. The DEAD box proteins DDX5 (p68) and DDX17 (p72): multi-tasking transcriptional regulators. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:756-63. [PMID: 23523990 DOI: 10.1016/j.bbagrm.2013.03.004] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 03/09/2013] [Indexed: 02/04/2023]
Abstract
Members of the DEAD box family of RNA helicases, which are characterised by the presence of twelve conserved motifs (including the signature D-E-A-D motif) within a structurally conserved 'helicase' core, are involved in all aspects of RNA metabolism. Apart from unwinding RNA duplexes, which established these proteins as RNA helicases, DEAD box proteins have been shown to also catalyse RNA annealing and to displace proteins from RNA. DEAD box proteins generally act as components of large multi-protein complexes and it is thought that interactions, via their divergent N- and C-terminal extensions, with other factors in the complexes may be responsible for the many different functions attributed to these proteins. In addition to their established crucial roles in the manipulation of RNA structure, it is becoming increasingly clear that several members of the DEAD box family act as regulators of transcription. In this review I shall focus on DDX5 (p68) and the highly related DDX17 (p72), two proteins for which there is a large body of evidence demonstrating that they function in transcriptional regulation. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.
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68
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Manavathi B, Dey O, Gajulapalli VNR, Bhatia RS, Bugide S, Kumar R. Derailed estrogen signaling and breast cancer: an authentic couple. Endocr Rev 2013; 34:1-32. [PMID: 22947396 PMCID: PMC3565105 DOI: 10.1210/er.2011-1057] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 07/09/2012] [Indexed: 02/06/2023]
Abstract
Estrogen or 17β-estradiol, a steroid hormone, plays a critical role in the development of mammary gland via acting through specific receptors. In particular, estrogen receptor-α (ERα) acts as a transcription factor and/or a signal transducer while participating in the development of mammary gland and breast cancer. Accumulating evidence suggests that the transcriptional activity of ERα is altered by the action of nuclear receptor coregulators and might be responsible, at least in part, for the development of breast cancer. In addition, this process is driven by various posttranslational modifications of ERα, implicating active participation of the upstream receptor modifying enzymes in breast cancer progression. Emerging studies suggest that the biological outcome of breast cancer cells is also influenced by the cross talk between microRNA and ERα signaling, as well as by breast cancer stem cells. Thus, multiple regulatory controls of ERα render mammary epithelium at risk for transformation upon deregulation of normal homeostasis. Given the importance that ERα signaling has in breast cancer development, here we will highlight how the activity of ERα is controlled by various regulators in a spatial and temporal manner, impacting the progression of the disease. We will also discuss the possible therapeutic value of ERα modulators as alternative drug targets to retard the progression of breast cancer.
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Affiliation(s)
- Bramanandam Manavathi
- Department of Biochemistry, School of Life Sciences, Gachibowli, Prof. CR Rao Road, University of Hyderabad, Hyderabad 500046, India.
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69
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Clark EL, Hadjimichael C, Temperley R, Barnard A, Fuller-Pace FV, Robson CN. p68/DdX5 supports β-catenin & RNAP II during androgen receptor mediated transcription in prostate cancer. PLoS One 2013; 8:e54150. [PMID: 23349811 PMCID: PMC3547877 DOI: 10.1371/journal.pone.0054150] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 12/07/2012] [Indexed: 11/18/2022] Open
Abstract
The DEAD box RNA helicase p68 (Ddx5) is an important androgen receptor (AR) transcriptional co-activator in prostate cancer (PCa) and is over-expressed in late stage disease. β-Catenin is a multifunctional protein with important structural and signalling functions which is up-regulated in PCa and similar to p68, interacts with the AR to co-activate expression of AR target genes. Importantly, p68 forms complexes with nuclear β-Catenin and promotes gene transcription in colon cancer indicating a functional interplay between these two proteins in cancer progression. In this study, we explore the relationship of p68 and β-Catenin in PCa to assess their potential co-operation in AR-dependent gene expression, which may be of importance in the development of castrate resistant prostate cancer (CRPCa). We use immunoprecipitation to demonstrate a novel interaction between p68 and β-Catenin in the nucleus of PCa cells, which is androgen dependent in LNCaP cells but androgen independent in a hormone refractory derivative of the same cell line (representative of the CRPCa disease type). Enhanced AR activity is seen in androgen-dependent luciferase reporter assays upon transient co-transfection of p68 and β-Catenin as an additive effect, and p68-depleted Chromatin-Immunoprecipitation (ChIP) showed a decrease in the recruitment of the AR and β-Catenin to androgen responsive promoter regions. In addition, we found p68 immunoprecipitated with the processive and non-processive form of RNA polymerase II (RNAP II) and show p68 recruited to elongating regions of the AR mediated PSA gene, suggesting a role for p68 in facilitating RNAP II transcription of AR mediated genes. These results suggest p68 is important in facilitating β-Catenin and AR transcriptional activity in PCa cells.
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Affiliation(s)
- Emma L. Clark
- Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Richard Temperley
- Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Amy Barnard
- Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Frances V. Fuller-Pace
- Division of Cancer Research, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom
| | - Craig N. Robson
- Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, United Kingdom
- * E-mail:
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70
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Abstract
Members of the DEAD box family of RNA helicases are known to be involved in most cellular processes that require manipulation of RNA structure and, in many cases, exhibit other functions in addition to their established ATP-dependent RNA helicase activities. They thus play critical roles in cellular metabolism and in many cases have been implicated in cellular proliferation and/or neoplastic transformation. These proteins generally act as components of multi-protein complexes; therefore their precise role is likely to be influenced by their interacting partners and to be highly context-dependent. This may also provide an explanation for the sometimes conflicting reports suggesting that DEAD box proteins have both pro- and anti-proliferative roles in cancer.
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Affiliation(s)
- Frances V Fuller-Pace
- Division of Cancer Research, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland.
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71
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Dardenne E, Pierredon S, Driouch K, Gratadou L, Lacroix-Triki M, Espinoza MP, Zonta E, Germann S, Mortada H, Villemin JP, Dutertre M, Lidereau R, Vagner S, Auboeuf D. Splicing switch of an epigenetic regulator by RNA helicases promotes tumor-cell invasiveness. Nat Struct Mol Biol 2012; 19:1139-46. [PMID: 23022728 DOI: 10.1038/nsmb.2390] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 08/24/2012] [Indexed: 12/11/2022]
Abstract
Both epigenetic and splicing regulation contribute to tumor progression, but the potential links between these two levels of gene-expression regulation in pathogenesis are not well understood. Here, we report that the mouse and human RNA helicases Ddx17 and Ddx5 contribute to tumor-cell invasiveness by regulating alternative splicing of several DNA- and chromatin-binding factors, including the macroH2A1 histone. We show that macroH2A1 splicing isoforms differentially regulate the transcription of a set of genes involved in redox metabolism. In particular, the SOD3 gene that encodes the extracellular superoxide dismutase and plays a part in cell migration is regulated in an opposite manner by macroH2A1 splicing isoforms. These findings reveal a new regulatory pathway in which splicing factors control the expression of histone variant isoforms that in turn drive a transcription program to switch tumor cells to an invasive phenotype.
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Affiliation(s)
- Etienne Dardenne
- Institut National de la Santé et de la Recherche Médicale, U1052, Centre de Recherche en Cancérologie de Lyon, Lyon, France
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72
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Nicol SM, Bray SE, Black HD, Lorimore SA, Wright EG, Lane DP, Meek DW, Coates PJ, Fuller-Pace FV. The RNA helicase p68 (DDX5) is selectively required for the induction of p53-dependent p21 expression and cell-cycle arrest after DNA damage. Oncogene 2012; 32:3461-9. [PMID: 22986526 PMCID: PMC3556166 DOI: 10.1038/onc.2012.426] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 07/06/2012] [Accepted: 07/31/2012] [Indexed: 01/02/2023]
Abstract
The RNA helicase p68 (DDX5) is an established co-activator of the p53 tumour suppressor that itself has a pivotal role in orchestrating the cellular response to DNA damage. Although several factors influence the biological outcome of p53 activation, the mechanisms governing the choice between cell-cycle arrest and apoptosis remain to be elucidated. In the present study, we show that, while p68 is critical for p53-mediated transactivation of the cell-cycle arrest gene p21(WAF1/CIP1), it is dispensable for induction of several pro-apoptotic genes in response to DNA damage. Moreover, p68 depletion results in a striking inhibition of recruitment of p53 and RNA Pol II to the p21 promoter but not to the Bax or PUMA promoters, providing an explanation for the selective effect on p21 induction. Importantly, these findings are mirrored in a novel inducible p68 knockout mouse model in which p68 depletion results in a selective inhibition of p21 induction in several tissues. Moreover, in the bone marrow, p68 depletion results in an increased sensitivity to γ-irradiation, consistent with an increased level of apoptosis. These data highlight a novel function of p68 as a modulator of the decision between p53-mediated growth arrest and apoptosis in vitro and in vivo.
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Affiliation(s)
- S M Nicol
- Division of Cancer Research, University of Dundee, Ninewells Hospital & Medical School, Dundee, UK
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73
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Kanno Y, Serikawa T, Inajima J, Inouye Y. DP97, a DEAD box DNA/RNA helicase, is a target gene-selective co-regulator of the constitutive androstane receptor. Biochem Biophys Res Commun 2012; 426:38-42. [PMID: 22910411 DOI: 10.1016/j.bbrc.2012.08.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 08/07/2012] [Indexed: 01/09/2023]
Abstract
The constitutive androstane receptor (CAR) plays a key role in the expression of xenobiotic/steroid and drug metabolizing enzymes and their transporters. In this study, we demonstrated that DP97, a member of the DEAD box DNA/RNA helicase protein family, is a novel CAR-interacting protein. Using HepG2 cells expressing human CAR in the presence of tetracycline, we showed that knockdown of DP97 with small interfering RNAs suppressed tetracycline-inducible mRNA expression of CYP2B6 and UGT1A1 but not CYP3A4. Thus, DP97 was found to be a gene (or promoter)-selective co-activator for hCAR. DP97-mediated CAR transactivation was synergistically enhanced by the co-expression of SRC-1 or PGC1α, therefore it might act as mediator between hCAR and appropriate co-activators.
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Affiliation(s)
- Yuichiro Kanno
- Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan.
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74
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Wang R, Jiao Z, Li R, Yue H, Chen L. p68 RNA helicase promotes glioma cell proliferation in vitro and in vivo via direct regulation of NF-κB transcription factor p50. Neuro Oncol 2012; 14:1116-24. [PMID: 22810421 DOI: 10.1093/neuonc/nos131] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The DEAD-box RNA helicase p68 plays a very important role in early organ development and maturation. However, the role of p68 in glioma is unclear. In this study, we showed that p68 protein levels were significantly elevated in high-grade gliomas compared to low-grade gliomas and normal adjacent brain tissues. Importantly, the expression of p68 was significantly associated with poorer overall survival and enhanced resistance to treatment with radiotherapy plus temozolomide for glioma patients. Ectopic expression of p68 enhanced glioma cell proliferation both in vitro and in vivo. In contrast, knockdown of endogenous p68 prevented glioma cell proliferation. Using a tandem affinity purification assay, we found a new p68-binding protein, nuclear factor (NF)-κB p50. We found that p68 bound with the N-terminal of NF-κB p50, and the mutant of p68 lacking the p50-interaction domain failed to stimulate glioma cell proliferation and tumor growth. Moreover, p68 induced NF-κB p50 accumulation in the nucleus through release of NF-κB p50 from IκBα and increased NF-κB p50 target luciferase transcription activity. Knockdown of NF-κB p50 rescued the phenotypes induced by p68 both in vitro and in vivo. We concluded that p68 induces glioma tumor growth through binding with NF-κB p50, regulating NF-κB p50 nucleus accumulation and transcription activity.
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Affiliation(s)
- Rui Wang
- Second Affiliated Hospital of Harbin Medical University, Harbin, China
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75
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Mazurek A, Luo W, Krasnitz A, Hicks J, Powers RS, Stillman B. DDX5 regulates DNA replication and is required for cell proliferation in a subset of breast cancer cells. Cancer Discov 2012; 2:812-25. [PMID: 22750847 DOI: 10.1158/2159-8290.cd-12-0116] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
UNLABELLED Understanding factors required for DNA replication will enrich our knowledge of this important process and potentially identify vulnerabilities that can be exploited in cancer therapy. We applied an assay that measures the stability of maintenance of an episomal plasmid in human tissue culture cells to screen for new DNA replication factors. We identify an important role for DDX5 in G(1)-S-phase progression where it directly regulates DNA replication factor expression by promoting the recruitment of RNA polymerase II to E2F-regulated gene promoters. We find that the DDX5 locus is frequently amplified in breast cancer and that breast cancer-derived cells with amplification of DDX5 are much more sensitive to its depletion than breast cancer cells and a breast epithelial cell line that lacks DDX5 amplification. Our results show a novel role for DDX5 in cancer cell proliferation and suggest DDX5 as a therapeutic target in breast cancer treatment. SIGNIFICANCE DDX5 is required for cell proliferation by controlling the transcription of genes expressing DNA replication proteins in cancer cells in which the DDX5 locus is amplified, and this has uncovered a dependence on DDX5 for cell proliferation. Given the high frequency of DDX5 amplification in breast cancer, our results highlight DDX5 as a promising candidate for targeted therapy of breast tumors with DDX5 amplification, and indeed we show that DDX5 inhibition sensitizes a subset of breast cancer cells to trastuzumab.
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Affiliation(s)
- Anthony Mazurek
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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76
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Fogel BL, Wexler E, Wahnich A, Friedrich T, Vijayendran C, Gao F, Parikshak N, Konopka G, Geschwind DH. RBFOX1 regulates both splicing and transcriptional networks in human neuronal development. Hum Mol Genet 2012; 21:4171-86. [PMID: 22730494 DOI: 10.1093/hmg/dds240] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
RNA splicing plays a critical role in the programming of neuronal differentiation and, consequently, normal human neurodevelopment, and its disruption may underlie neurodevelopmental and neuropsychiatric disorders. The RNA-binding protein, fox-1 homolog (RBFOX1; also termed A2BP1 or FOX1), is a neuron-specific splicing factor predicted to regulate neuronal splicing networks clinically implicated in neurodevelopmental disease, including autism spectrum disorder (ASD), but only a few targets have been experimentally identified. We used RNA sequencing to identify the RBFOX1 splicing network at a genome-wide level in primary human neural stem cells during differentiation. We observe that RBFOX1 regulates a wide range of alternative splicing events implicated in neuronal development and maturation, including transcription factors, other splicing factors and synaptic proteins. Downstream alterations in gene expression define an additional transcriptional network regulated by RBFOX1 involved in neurodevelopmental pathways remarkably parallel to those affected by splicing. Several of these differentially expressed genes are further implicated in ASD and related neurodevelopmental diseases. Weighted gene co-expression network analysis demonstrates a high degree of connectivity among these disease-related genes, highlighting RBFOX1 as a key factor coordinating the regulation of both neurodevelopmentally important alternative splicing events and clinically relevant neuronal transcriptional programs in the development of human neurons.
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Affiliation(s)
- Brent L Fogel
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA.
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77
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Abstract
RNA helicases unwind their RNA substrates in an ATP-dependent reaction, and are central to all cellular processes involving RNA. They have important roles in viral life cycles, where RNA helicases are either virus-encoded or recruited from the host. Vertebrate RNA helicases sense viral infections, and trigger the innate antiviral immune response. RNA helicases have been implicated in protozoic, bacterial and fungal infections. They are also linked to neurological disorders, cancer, and aging processes. Genome-wide studies continue to identify helicase genes that change their expression patterns after infection or disease outbreak, but the mechanism of RNA helicase action has been defined for only a few diseases. RNA helicases are prognostic and diagnostic markers and suitable drug targets, predominantly for antiviral and anti-cancer therapies. This review summarizes the current knowledge on RNA helicases in infection and disease, and their growing potential as drug targets.
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Affiliation(s)
- Lenz Steimer
- University of Muenster, Institute for Physical Chemistry, Muenster, Germany
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78
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Carter CJ. Extensive viral mimicry of 22 AIDS-related autoantigens by HIV-1 proteins and pathway analysis of 561 viral/human homologues suggest an initial treatable autoimmune component of AIDS. ACTA ACUST UNITED AC 2012; 63:254-68. [PMID: 22077229 DOI: 10.1111/j.1574-695x.2011.00848.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
HIV-1 viral proteins, particularly the env protein, are homologous to 22 AIDS autoantigens, suggesting their creation by antiviral antibodies subsequently targeting human homologues. They include antibodies to T-cell receptors, CD4 and CD95, complement components, IgG, TNF and other immune-related proteins. Autoantibodies may compromise the immune system via knockdown of these key proteins, and autoimmune attack on the immune system itself, as supported by immune activation in early stages of infection and during the transition to AIDS. Over 500 human proteins contain pentapeptides or longer consensi, identical to viral peptides. Such homology explains the extensive viral/human interactome, likely related to the ability of viral homologues to compete with human counterparts as binding partners. Pathway analysis of these homologous proteins revealed their involvement in immune-related networks (e.g. natural killer cell toxicity/toll, T-cell/B-cell receptor signalling/antigen processing) and viral and bacterial entry and defence pathways (phagosome/lysosome pathways, DNA sensing/NOD/RIG-1 pathways) relevant to AIDS pathogenesis. At its inception, AIDS may have an autoimmune component selectively targeting the immune system. Immunosuppressive therapy or antibody removal, which has already achieved some success, might be therapeutically beneficial, particularly if targeted at removal of the culpable antibodies, via affinity dialysis.
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Affiliation(s)
- Chris J Carter
- PolygenicPathways, St Leonard's on Sea, East Sussex, UK.
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79
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Abstract
RNA helicase enzymes catalyze the in vivo folding and conformational re-arrangement of RNA. DEAD-box proteins (DBPs) make up the largest family of RNA helicases and are found across all phyla. DBPs are molecular motor proteins that utilize chemical energy in cycles of ATP binding, hydrolysis, and product release to perform mechanical work resulting in reorganization of cellular RNAs. DBPs contain a highly conserved motor domain helicase core. Auxiliary domains, enzymatic adaptations, and regulatory partner proteins contribute to the diversity of DBP function throughout RNA metabolism. In this review we focus on the current understanding of the DBP ATP utilization mechanism in rearranging and unwinding RNA structures. We discuss DBP structural properties, kinetic pathways, and thermodynamic features of nucleotide-dependent interactions with RNA. We highlight recent advances in the DBP field derived from biochemical and molecular biophysical investigations aimed at developing a quantitative mechanistic understanding of DBP molecular motor function.
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Affiliation(s)
- Arnon Henn
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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80
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Germann S, Gratadou L, Zonta E, Dardenne E, Gaudineau B, Fougère M, Samaan S, Dutertre M, Jauliac S, Auboeuf D. Dual role of the ddx5/ddx17 RNA helicases in the control of the pro-migratory NFAT5 transcription factor. Oncogene 2012; 31:4536-49. [PMID: 22266867 DOI: 10.1038/onc.2011.618] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ddx5 and ddx17 are two highly related RNA helicases involved in both transcription and splicing. These proteins coactivate transcription factors involved in cancer such as the estrogen receptor alpha, p53 and beta-catenin. Ddx5 and ddx17 are part of the splicing machinery and can modulate alternative splicing, the main mechanism increasing the proteome diversity. Alternative splicing also has a role in gene expression level regulation when it is coupled to the nonsense-mediated mRNA decay (NMD) pathway. In this work, we report that ddx5 and ddx17 have a dual role in the control of the pro-migratory NFAT5 transcription factor. First, ddx5 and ddx17 act as transcriptional coactivators of NFAT5 and are required for activating NFAT5 target genes involved in tumor cell migration. Second, at the splicing level, ddx5 and ddx17 increase the inclusion of NFAT5 exon 5. As exon 5 contains a pre-mature translation termination codon, its inclusion leads to the regulation of NFAT5 mRNAs by the NMD pathway and to a decrease in NFAT5 protein level. Therefore, we demonstrated for the first time that a transcriptional coregulator can simultaneously regulate the transcriptional activity and alternative splicing of a transcription factor. This dual regulation, where ddx5 and ddx17 enhance the transcriptional activity of NFAT5 although reducing its protein expression level, suggests a critical role for ddx5 and ddx17 in tumor cell migration through the fine regulation of NFAT5 pathway.
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81
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Abstract
It is established that several DEAD box RNA helicases perform multiple functions in the cell, often through interactions with different partner proteins in a context-dependent manner. Several studies have shown that some DEAD box proteins play important roles as regulators of transcription, particularly as coactivators or cosuppressors of transcription factors that are themselves highly regulated. Two such RNA helicases are DDX5 (p68) and DDX17 (p72). These proteins are known to function in RNA processing/alternative splicing, but they have also been shown to interact with, and act as coregulators of, transcription factors that are themselves highly regulated. In this chapter, we shall describe protocols we have used to investigate the factors that influence the function of p68 and p72 in transcriptional regulation. These include the interactions of p68 and p72 with transcription factors and/or components of the transcription machinery and posttranslational modification by the small ubiquitin-related modifier, SUMO.
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82
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Zhao J, Yu H, Lin L, Tu J, Cai L, Chen Y, Zhong F, Lin C, He F, Yang P. Interactome study suggests multiple cellular functions of hepatoma-derived growth factor (HDGF). J Proteomics 2011; 75:588-602. [DOI: 10.1016/j.jprot.2011.08.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 08/14/2011] [Accepted: 08/25/2011] [Indexed: 02/05/2023]
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83
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Wang D, Huang J, Hu Z. RNA helicase DDX5 regulates microRNA expression and contributes to cytoskeletal reorganization in basal breast cancer cells. Mol Cell Proteomics 2011; 11:M111.011932. [PMID: 22086602 DOI: 10.1074/mcp.m111.011932] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RNA helicase DDX5 (also p68) is involved in all aspects of RNA metabolism and serves as a transcriptional coregulator, but its functional role in breast cancer remains elusive. Here, we report an integrative biology study of DDX5 in breast cancer, encompassing quantitative proteomics, global MicroRNA profiling, and detailed biochemical characterization of cell lines and human tissues. We showed that protein expression of DDX5 increased progressively from the luminal to basal breast cancer cell lines, and correlated positively with that of CD44 in the basal subtypes. Through immunohistochemistry analyses of tissue microarrays containing over 200 invasive human ductal carcinomas, we observed that DDX5 was up-regulated in the majority of malignant tissues, and its expression correlated strongly with those of Ki67 and EGFR in the triple-negative tumors. We demonstrated that DDX5 regulated a subset of MicroRNAs including miR-21 and miR-182 in basal breast cancer cells. Knockdown of DDX5 resulted in reorganization of actin cytoskeleton and reduction of cellular proliferation. The effects were accompanied by up-regulation of tumor suppressor PDCD4 (a known miR-21 target); as well as up-regulation of cofilin and profilin, two key proteins involved in actin polymerization and cytoskeleton maintenance, as a consequence of miR-182 down-regulation. Treatment with miR-182 inhibitors resulted in morphologic phenotypes resembling those induced by DDX5 knockdown. Using bioinformatics tools for pathway and network analyses, we confirmed that the network for regulation of actin cytoskeleton was predominantly enriched for the predicted downstream targets of miR-182. Our results reveal a new functional role of DDX5 in breast cancer via the DDX5→miR-182→actin cytoskeleton pathway, and suggest the potential clinical utility of DDX5 and its downstream MicroRNAs in the theranostics of breast cancer.
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Affiliation(s)
- Daojing Wang
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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84
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Fuller-Pace FV, Moore HC. RNA helicases p68 and p72: multifunctional proteins with important implications for cancer development. Future Oncol 2011; 7:239-51. [PMID: 21345143 DOI: 10.2217/fon.11.1] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The DEAD box RNA helicases p68 (DDX5) and p72 (DDX17) play important roles in multiple cellular processes that are commonly dysregulated in cancers, including transcription, pre-mRNA processing/alternative splicing and miRNA processing. Although p68 and p72 appear to have some overlapping functions, they clearly also have distinct, nonredundant functions. Furthermore, their ability to interact with a variety of different factors and act as multifunctional proteins has the potential to impact on several different processes, and alterations in expression or function of p68 and/or p72 could have profound implications for cancer development. However, their roles are likely to be context-dependent and both proteins have been reported to have pro-proliferation or even oncogenic functions as well as antiproliferative or tumor cosuppressor roles. Therefore, eludicating the precise role of these proteins in cancer is likely to be complex and to depend on the cellular environment and interacting factors. In this article, we review the many functions that have been attributed to p68 and p72 and discuss their potential roles in cancer development.
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Affiliation(s)
- Frances V Fuller-Pace
- Centre for Oncology & Molecular Medicine, University of Dundee, Ninewells Hospital & Medical School, Dundee, UK.
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85
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Karamouzis MV, Papavassiliou AG. Transcription factor networks as targets for therapeutic intervention of cancer: the breast cancer paradigm. Mol Med 2011; 17:1133-6. [PMID: 21912809 DOI: 10.2119/molmed.2011.00315] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 08/25/2011] [Indexed: 11/06/2022] Open
Abstract
It has long been shown that many of the presently used anticancer drugs exert their effects partly through modulating the activity of vital transcription factors. The intricacy of transcriptional regulation still represents the main obstacle for the design of transcription factor-directed agents. Systematic mapping of tumor-specific transcriptional networks and application of new molecular tools have reinforced research interest and efforts in this venue. The case of breast cancer is discussed as a representative example.
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Affiliation(s)
- Michalis V Karamouzis
- Molecular Oncology Unit, Department of Biological Chemistry, University of Athens Medical School, Athens, Greece
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86
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Common genetic polymorphisms of microRNA biogenesis pathway genes and risk of breast cancer: a case-control study in Korea. Breast Cancer Res Treat 2011; 130:939-51. [PMID: 21766210 DOI: 10.1007/s10549-011-1656-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Accepted: 06/22/2011] [Indexed: 10/18/2022]
Abstract
Recent compelling evidence indicates that mutation, aberrant expression, and dysregulation of microRNA (miRNA) biogenesis are implicated in cancer development and progression. Based on the important role of miRNA biogenesis pathway in carcinogenesis, we hypothesized that genetic variations in this pathway genes may play a role as susceptibility factors for breast cancer. To test this hypothesis, we investigated the associations between 41 single nucleotide polymorphisms (SNPs) in 14 genes involved in miRNA biogenesis pathway and breast cancer risk in a case-control study of 559 Korean breast cancer cases and 567 controls frequency-matched by age. In all women, 3 SNPs (AGO1 rs595055, AGO2 rs3864659, and p68 rs1991401) were significantly associated with breast cancer risk. In stratified analysis by menopausal status, altered risk associations were observed for 7 SNPs in postmenopausal breast cancer. When subjects were grouped by the number of high-risk genotypes, we found a progressive increase in gene-dosage effect (P (trend) = 9.46E-7). The protective effects of AGO2 rs3864659 and HIWI rs11060845 were more pronounced in progesterone receptor-positive (PR+) cancer than in progesterone receptor-negative (PR-) cancer (odds ratio (OR), 0.50; 95% confidence interval (CI), 0.30-0.84 vs. OR, 0.94; 95% CI, 0.60-1.84; P (heterogeneity) = 0.04 and OR, 0.57; 95% CI, 0.37-0.88 vs. OR, 0.97; 95% CI, 0.65-1.44; P (heterogeneity) = 0.02, respectively), and the DROSHA rs644236 had stronger association with estrogen receptor-negative (ER-) cancer than for estrogen receptor-positive (ER+) cancer (OR, 1.39; 95% CI, 1.08-1.78 vs. OR, 1.05; 95% CI, 0.85-1.29; P (heterogeneity) = 0.04). Our results suggest that genetic variants in miRNA biogenesis pathway genes may be associated with breast cancer risk, and the modifiable effects might be different according to the menopausal status and hormone receptor status.
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87
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Tanaka T, Ishii T, Mizuno D, Mori T, Yamaji R, Nakamura Y, Kumazawa S, Nakayama T, Akagawa M. (-)-Epigallocatechin-3-gallate suppresses growth of AZ521 human gastric cancer cells by targeting the DEAD-box RNA helicase p68. Free Radic Biol Med 2011; 50:1324-35. [PMID: 21277973 DOI: 10.1016/j.freeradbiomed.2011.01.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 12/13/2010] [Accepted: 01/17/2011] [Indexed: 02/05/2023]
Abstract
(-)-Epigallocatechin-3-gallate (EGCG), the most abundant and biologically active polyphenol in green tea, induces apoptosis and suppresses proliferation of cancer cells by modulating multiple signal transduction pathways. However, the fundamental mechanisms responsible for these cancer-preventive effects have not been clearly elucidated. Recently, we found that EGCG can covalently bind to cysteine residues in proteins through autoxidation and subsequently modulate protein function. In this study, we demonstrate the direct binding of EGCG to cellular proteins in AZ521 human gastric cancer cells by redox-cycle staining. We comprehensively explored the binding targets of EGCG from EGCG-treated AZ521 cells by proteomics techniques combined with the boronate-affinity pull-down method. The DEAD-box RNA helicase p68, which is overexpressed in a variety of tumor cells and plays an important role in cancer development and progression, was identified as a novel EGCG-binding target. Exposure of AZ521 cells to EGCG lowered the p68 level dose dependently. The present findings show that EGCG inhibits AZ521 cell proliferation by preventing β-catenin oncogenic signaling through proteasomal degradation of p68 and provide a new perspective on the molecular mechanism of EGCG action.
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Affiliation(s)
- Tomoko Tanaka
- Department of Biological Chemistry, Division of Applied Life Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Naka-ku, Sakai 599-8531, Japan
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88
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Moore HC, Johnston M, Nicol SM, Bourdon JC, Thompson AM, Hutvagner G, Fuller-Pace FV. An evolutionarily conserved, alternatively spliced, intron in the p68/DDX5 DEAD-box RNA helicase gene encodes a novel miRNA. RNA (NEW YORK, N.Y.) 2011; 17:555-562. [PMID: 21346006 PMCID: PMC3062168 DOI: 10.1261/rna.2591611] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 01/28/2011] [Indexed: 05/27/2023]
Abstract
The DEAD-box RNA helicase p68 (DDX5) plays important roles in several cellular processes, including transcription, pre-mRNA processing, and microRNA (miRNA) processing. p68 expression is growth and developmentally regulated, and alterations in p68 expression and/or function have been implicated in tumor development. The p68 gene encodes an evolutionarily conserved, alternatively spliced, intron the function of which has to date remained unclear. Although the intron-containing p68 RNA does not appear to yield an alternative p68 protein, it is differentially expressed in cell lines and tissues, indicating regulation of expression. Here we show that the p68 conserved intron encodes a novel putative miRNA, suggesting a previously unknown possible regulatory function for the p68 intron. We show that this miRNA (referred to as p68 miRNA) is processed from the intron via the canonical miRNA-processing pathway and that it associates with the Argonaute protein Ago2. Finally we show that the p68 miRNA suppresses an mRNA bearing complementary target sequences, suggesting that it is functional. These findings suggest a novel mechanism by which alterations in p68 expression may impact on the cell.
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89
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Abstract
DEAD-box RNA helicases play various, often critical, roles in all processes where RNAs are involved. Members of this family of proteins are linked to human disease, including cancer and viral infections. DEAD-box proteins contain two conserved domains that both contribute to RNA and ATP binding. Despite recent advances the molecular details of how these enzymes convert chemical energy into RNA remodeling is unknown. We present crystal structures of the isolated DEAD-domains of human DDX2A/eIF4A1, DDX2B/eIF4A2, DDX5, DDX10/DBP4, DDX18/myc-regulated DEAD-box protein, DDX20, DDX47, DDX52/ROK1, and DDX53/CAGE, and of the helicase domains of DDX25 and DDX41. Together with prior knowledge this enables a family-wide comparative structural analysis. We propose a general mechanism for opening of the RNA binding site. This analysis also provides insights into the diversity of DExD/H- proteins, with implications for understanding the functions of individual family members.
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90
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Mooney SM, Goel A, D'Assoro AB, Salisbury JL, Janknecht R. Pleiotropic effects of p300-mediated acetylation on p68 and p72 RNA helicase. J Biol Chem 2010; 285:30443-52. [PMID: 20663877 DOI: 10.1074/jbc.m110.143792] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Here, we demonstrate that p68 (DDX5) and p72 (DDX17), two homologous RNA helicases and transcriptional cofactors, are substrates for the acetyltransferase p300 in vitro and in vivo. Mutation of acetylation sites affected the binding of p68/p72 to histone deacetylases, but not to p300 or estrogen receptor. Acetylation additionally increased the stability of p68 and p72 RNA helicase and stimulated their ability to coactivate the estrogen receptor, thereby potentially contributing to its aberrant activation in breast tumors. Also, acetylation of p72, but not of p68 RNA helicase, enhanced p53-dependent activation of the MDM2 promoter, pointing at another mechanism of how p72 acetylation may facilitate carcinogenesis by boosting the negative p53-MDM2 feedback loop. Furthermore, blocking p72 acetylation caused cell cycle arrest and apoptosis, revealing an essential role for p72 acetylation. In conclusion, our report has identified for the first time that acetylation modulates RNA helicases and provides multiple mechanisms how acetylation of p68 and p72 may affect normal and tumor cells.
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Affiliation(s)
- Steven M Mooney
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA
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91
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Kim Y, Park H, Park D, Lee YS, Choe J, Hahn JH, Lee H, Kim YM, Jeoung D. Cancer/testis antigen CAGE exerts negative regulation on p53 expression through HDAC2 and confers resistance to anti-cancer drugs. J Biol Chem 2010; 285:25957-68. [PMID: 20534591 DOI: 10.1074/jbc.m109.095950] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The role of the cancer/testis antigen CAGE in drug resistance was investigated. The drug-resistant human melanoma Malme3M (Malme3M(R)) and the human hepatic cancer cell line SNU387 (SNU387(R)) showed in vivo drug resistance and CAGE induction. Induction of CAGE resulted from decreased expression and thereby displacement of DNA methyltransferase 1(DNMT1) from CAGE promoter sequences. Various drugs induce expression of CAGE by decreasing expression of DNMT1, and hypomethylation of CAGE was correlated with the increased expression of CAGE. Down-regulation of CAGE in these cell lines decreased invasion and enhanced drug sensitivity resulting from increased apoptosis. Down-regulation of CAGE also led to decreased anchorage-independent growth. Down-regulation of CAGE led to increased expression of p53, suggesting that CAGE may act as a negative regulator of p53. Down-regulation of p53 enhanced resistance to drugs and prevented drugs from exerting apoptotic effects. In SNU387(R) cells, CAGE induced the interaction between histone deacetylase 2 (HDAC2) and Snail, which exerted a negative effect on p53 expression. Chromatin immunoprecipitation assay showed that CAGE, through interaction with HDAC2, exerted a negative effect on p53 expression in Malme3M(R) cells. These results suggest that CAGE confers drug resistance by regulating expression of p53 through HDAC2. Taken together, these results show the potential value of CAGE as a target for the development of cancer therapeutics.
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Affiliation(s)
- Youngmi Kim
- School of Biological Sciences, College of Natural Sciences, Kangwon National University, Chunchon, Korea
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92
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Germain DR, Graham K, Glubrecht DD, Hugh JC, Mackey JR, Godbout R. DEAD box 1: a novel and independent prognostic marker for early recurrence in breast cancer. Breast Cancer Res Treat 2010; 127:53-63. [PMID: 20499159 DOI: 10.1007/s10549-010-0943-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 05/06/2010] [Indexed: 12/21/2022]
Abstract
Breast cancer is a heterogeneous disease characterized by diverse molecular signatures and a variable response to therapy. Clinical management of breast cancer is guided by the expression of estrogen and progesterone receptors and HER2 amplification. New prognostic and predictive markers, as well as additional targets for therapy, are needed for more effective management of this disease. Gene expression microarrays were probed with RNAs from 176 primary breast cancer samples and tissue microarrays immunostained with anti-DDX1 antibody, an antibody to DEAD box protein DDX1, a putative RNA-RNA and RNA-DNA unwinding protein normally found in the nucleus. Half of the patient cohort had experienced early relapse despite standard adjuvant therapy, but were otherwise matched for estrogen receptor and HER2 status, stage and duration of follow-up. Here, we identify DDX1 RNA overexpression as an independent prognostic marker for early recurrence in primary breast cancer, with a hazard ratio of 4.31 based on logrank analysis of Kaplan-Meier curves. Elevated levels of DDX1 protein in the cytoplasm also independently correlate with early recurrence with a hazard ratio of 1.90. In conclusion, our data indicate a strong and independent association between poor prognosis and deregulation of the DEAD box protein DDX1. We propose that elevated levels of DDX1 RNA or the presence of DDX1 in the cytoplasm could serve as an effective prognostic biomarker for early recurrence in primary breast cancer.
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Affiliation(s)
- Devon R Germain
- Department of Oncology, School of Cancer/Engineering/Imaging Sciences, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
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93
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Janknecht R. Multi-talented DEAD-box proteins and potential tumor promoters: p68 RNA helicase (DDX5) and its paralog, p72 RNA helicase (DDX17). Am J Transl Res 2010; 2:223-234. [PMID: 20589163 PMCID: PMC2892403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Accepted: 05/01/2010] [Indexed: 05/29/2023]
Abstract
P68 (DDX5) and p72 (DDX17) are members of the DEAD-box RNA helicase family. They can unwind double-stranded RNA and also contribute to the remodeling of ribonucleoprotein complexes. These activities of p68/p72 are required for efficient RNA splicing and microRNA processing. In addition, p68/p72 perform functions that are independent of their enzymatic activity. This is especially common to their role in gene regulation, where p68/p72 coactivate various transcription factors, including the tumor suppressor p53, estrogen receptor alpha and beta-catenin. P68/p72 are posttranslationally modified by SUMO attachment and phosphorylation that regulate their coactivation potential, binding to known interactants or protein stability. Knock-out mouse models revealed that both DDX5 and DDX17 are essential genes during development. Furthermore, together with their ability to stimulate cell proliferation and prevent apoptosis, the reported overexpression of p68/p72 in three of the major human cancers (colon, breast, prostate) strongly suggests that p68/p72 promote tumorigenesis and might even represent proto-oncoproteins. If so, their inhibition holds promise as a novel way to contain or cure various carcinomas.
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Affiliation(s)
- Ralf Janknecht
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Biomedical Research Center BRC-1464 975 NE 10 Street, Oklahoma City, OK 73104, USA.
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