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Radhakrishnan A, Gangopadhyay R, Sharma C, Kapardar RK, Sharma NK, Srivastav R. Unwinding Helicase MCM Functionality for Diagnosis and Therapeutics of Replication Abnormalities Associated with Cancer: A Review. Mol Diagn Ther 2024; 28:249-264. [PMID: 38530633 DOI: 10.1007/s40291-024-00701-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/28/2024] [Indexed: 03/28/2024]
Abstract
The minichromosome maintenance (MCM) protein is a component of an active helicase that is essential for the initiation of DNA replication. Dysregulation of MCM functions contribute to abnormal cell proliferation and genomic instability. The interactions of MCM with cellular factors, including Cdc45 and GINS, determine the formation of active helicase and functioning of helicase. The functioning of MCM determines the fate of DNA replication and, thus, genomic integrity. This complex is upregulated in precancerous cells and can act as an important tool for diagnostic applications. The MCM protein complex can be an important broad-spectrum therapeutic target in various cancers. Investigations have supported the potential and applications of MCM in cancer diagnosis and its therapeutics. In this article, we discuss the physiological roles of MCM and its associated factors in DNA replication and cancer pathogenesis.
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Affiliation(s)
| | - Ritwik Gangopadhyay
- Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India
| | | | | | - Nilesh Kumar Sharma
- Cancer and Translational Research Lab, Dr. DY Patil Biotechnology and Bioinformatics Institute, Dr. DY Patil Vidyapeeth, Pune, Maharashtra, India
| | - Rajpal Srivastav
- Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India.
- Department of Science and Technology, Ministry of Science and Technology, New Delhi, India.
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2
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Khamidullina AI, Abramenko YE, Bruter AV, Tatarskiy VV. Key Proteins of Replication Stress Response and Cell Cycle Control as Cancer Therapy Targets. Int J Mol Sci 2024; 25:1263. [PMID: 38279263 PMCID: PMC10816012 DOI: 10.3390/ijms25021263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/14/2024] [Accepted: 01/17/2024] [Indexed: 01/28/2024] Open
Abstract
Replication stress (RS) is a characteristic state of cancer cells as they tend to exchange precision of replication for fast proliferation and increased genomic instability. To overcome the consequences of improper replication control, malignant cells frequently inactivate parts of their DNA damage response (DDR) pathways (the ATM-CHK2-p53 pathway), while relying on other pathways which help to maintain replication fork stability (ATR-CHK1). This creates a dependency on the remaining DDR pathways, vulnerability to further destabilization of replication and synthetic lethality of DDR inhibitors with common oncogenic alterations such as mutations of TP53, RB1, ATM, amplifications of MYC, CCNE1 and others. The response to RS is normally limited by coordination of cell cycle, transcription and replication. Inhibition of WEE1 and PKMYT1 kinases, which prevent unscheduled mitosis entry, leads to fragility of under-replicated sites. Recent evidence also shows that inhibition of Cyclin-dependent kinases (CDKs), such as CDK4/6, CDK2, CDK8/19 and CDK12/13 can contribute to RS through disruption of DNA repair and replication control. Here, we review the main causes of RS in cancers as well as main therapeutic targets-ATR, CHK1, PARP and their inhibitors.
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Affiliation(s)
- Alvina I. Khamidullina
- Laboratory of Molecular Oncobiology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia; (A.I.K.); (Y.E.A.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia
| | - Yaroslav E. Abramenko
- Laboratory of Molecular Oncobiology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia; (A.I.K.); (Y.E.A.)
| | - Alexandra V. Bruter
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia
| | - Victor V. Tatarskiy
- Laboratory of Molecular Oncobiology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia; (A.I.K.); (Y.E.A.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia
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3
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Braden WA, McClendon AK, Knudsen ES. Retraction Note: Cyclin-dependent kinase 4/6 activity is a critical determinant of pre-replication complex assembly. Oncogene 2023; 42:1332. [PMID: 36949240 DOI: 10.1038/s41388-023-02663-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Affiliation(s)
- W A Braden
- Department of Cancer Biology and the Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - A K McClendon
- Department of Cancer Biology and the Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - E S Knudsen
- Department of Cancer Biology and the Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA.
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Oshi M, Takahashi H, Tokumaru Y, Yan L, Rashid OM, Nagahashi M, Matsuyama R, Endo I, Takabe K. The E2F Pathway Score as a Predictive Biomarker of Response to Neoadjuvant Therapy in ER+/HER2- Breast Cancer. Cells 2020; 9:E1643. [PMID: 32650578 PMCID: PMC7407968 DOI: 10.3390/cells9071643] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/28/2020] [Accepted: 07/07/2020] [Indexed: 12/20/2022] Open
Abstract
E2F transcription factors play critical roles in the cell cycle. Therefore, their activity is expected to reflect tumor aggressiveness and responsiveness to therapy. We scored 3905 tumors of nine breast cancer cohorts for this activity based on their gene expression for the Hallmark E2F targets gene set. As expected, tumors with a high score had an increased expression of cell proliferation-related genes. A high score was significantly associated with shorter patient survival, greater MKI67 expression, histological grade, stage, and genomic aberrations. Furthermore, metastatic tumors had higher E2F scores than the primary tumors from which they arose. Although tumors with a high score had greater infiltration by both pro- and anti-cancerous immune cells, they had an increased expression of immune checkpoint genes. Estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative cancer with a high E2F score achieved a significantly higher pathological complete response (pCR) rate to neoadjuvant chemotherapy. The E2F score was significantly associated with the expression of cyclin-dependent kinase (CDK)-related genes and strongly correlated with sensitivity to CDK inhibition in cell lines. In conclusion, the E2F score is a marker of breast cancer aggressiveness and predicts the responsiveness of ER-positive/HER2-negative patients to neoadjuvant chemotherapy and possibly to CDK and immune checkpoint inhibitors.
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Affiliation(s)
- Masanori Oshi
- Department of Surgical Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA; (M.O.); (H.T.); (Y.T.)
- Department of Gastroenterological Surgery, Yokohama City University School of Medicine, Yokohama 2360004, Japan; (R.M.); (I.E.)
| | - Hideo Takahashi
- Department of Surgical Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA; (M.O.); (H.T.); (Y.T.)
| | - Yoshihisa Tokumaru
- Department of Surgical Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA; (M.O.); (H.T.); (Y.T.)
- Department of Surgical Oncology, Graduate School of Medicine, Gifu University, Gifu 501-1194, Japan
| | - Li Yan
- Department of Biostatistics & Bioinformatics, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA;
| | - Omar M. Rashid
- Department of Surgery, Holy Cross Hospital, Michael and Dianne Bienes Comprehensive Cancer Center, Fort Lauderdale, FL 33308, USA;
- Department of Surgery, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Masayuki Nagahashi
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata 9518520, Japan;
| | - Ryusei Matsuyama
- Department of Gastroenterological Surgery, Yokohama City University School of Medicine, Yokohama 2360004, Japan; (R.M.); (I.E.)
| | - Itaru Endo
- Department of Gastroenterological Surgery, Yokohama City University School of Medicine, Yokohama 2360004, Japan; (R.M.); (I.E.)
| | - Kazuaki Takabe
- Department of Surgical Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA; (M.O.); (H.T.); (Y.T.)
- Department of Gastroenterological Surgery, Yokohama City University School of Medicine, Yokohama 2360004, Japan; (R.M.); (I.E.)
- Department of Gastrointestinal Tract Surgery, Fukushima Medical University School of Medicine, Fukushima 9601295, Japan
- Department of Surgery, Jacobs School of Medicine and Biomedical Sciences, State University of New York, Buffalo, NY 14263, USA
- Department of Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata 9518510, Japan
- Department of Breast Surgery and Oncology, Tokyo Medical University, Tokyo 1608402, Japan
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Mughal MJ, Mahadevappa R, Kwok HF. DNA replication licensing proteins: Saints and sinners in cancer. Semin Cancer Biol 2018; 58:11-21. [PMID: 30502375 DOI: 10.1016/j.semcancer.2018.11.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/08/2018] [Accepted: 11/26/2018] [Indexed: 12/12/2022]
Abstract
DNA replication is all-or-none process in the cell, meaning, once the DNA replication begins it proceeds to completion. Hence, to achieve maximum control of DNA replication, eukaryotic cells employ a multi-subunit initiator protein complex known as "pre-replication complex or DNA replication licensing complex (DNA replication LC). This complex involves multiple proteins which are origin-recognition complex family proteins, cell division cycle-6, chromatin licensing and DNA replication factor 1, and minichromosome maintenance family proteins. Higher-expression of DNA replication LC proteins appears to be an early event during development of cancer since it has been a common hallmark observed in a wide variety of cancers such as oesophageal, laryngeal, pulmonary, mammary, colorectal, renal, urothelial etc. However, the exact mechanisms leading to the abnormally high expression of DNA replication LC have not been clearly deciphered. Increased expression of DNA replication LC leads to licensing and/or firing of multiple origins thereby inducing replication stress and genomic instability. Therapeutic approaches where the reduction in the activity of DNA replication LC was achieved either by siRNA or shRNA techniques, have shown increased sensitivity of cancer cell lines towards the anti-cancer drugs such as cisplatin, 5-Fluorouracil, hydroxyurea etc. Thus, the expression level of DNA replication LC within the cell determines a cell's fate thereby creating a paradox where DNA replication LC acts as both "Saint" and "Sinner". With a potential to increase sensitivity to chemotherapy drugs, DNA replication LC proteins have prospective clinical importance in fighting cancer. Hence, in this review, we will shed light on importance of DNA replication LC with an aim to use DNA replication LC in diagnosis and prognosis of cancer in patients as well as possible therapeutic targets for cancer therapy.
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Affiliation(s)
- Muhammad Jameel Mughal
- Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau
| | - Ravikiran Mahadevappa
- Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau
| | - Hang Fai Kwok
- Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau.
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Witkiewicz AK, Chung S, Brough R, Vail P, Franco J, Lord CJ, Knudsen ES. Targeting the Vulnerability of RB Tumor Suppressor Loss in Triple-Negative Breast Cancer. Cell Rep 2018; 22:1185-1199. [PMID: 29386107 PMCID: PMC5967622 DOI: 10.1016/j.celrep.2018.01.022] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 12/14/2017] [Accepted: 01/08/2018] [Indexed: 02/06/2023] Open
Abstract
Approximately 30% of triple-negative breast cancers (TNBCs) exhibit functional loss of the RB tumor suppressor, suggesting a target for precision intervention. Here, we use drug screens to identify agents specifically antagonized by the retinoblastoma tumor suppressor (RB) using CDK4/6 inhibitors. A number of candidate RB-synthetic lethal small molecules were identified, including anti-helmenthics, chemotherapeutic agents, and small-molecule inhibitors targeting DNA-damage checkpoints (e.g., CHK) and chromosome segregation (e.g., PLK1). Counter-screens using isogenic TNBC tumor cell lines and cell panels with varying endogenous RB statuses confirmed that therapeutic effects were robust and selective for RB loss of function. By analyzing TNBC clinical specimens, RB-deficient tumors were found to express high levels of CHK1 and PLK1. Loss of RB specifically resulted in loss of checkpoint functions governing DNA replication, yielding increased drug sensitivity. Xenograft models demonstrated RB-selective efficacy of CHK inhibitors. This study supports the possibility of selectively targeting RB loss in the treatment of TNBC.
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Affiliation(s)
- Agnieszka K Witkiewicz
- University of Arizona Cancer Center, Tucson, AZ 85724, USA; Department of Pathology, University of Arizona, Tucson, AZ 85724, USA.
| | - Sejin Chung
- University of Arizona Cancer Center, Tucson, AZ 85724, USA
| | - Rachel Brough
- CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Paris Vail
- University of Arizona Cancer Center, Tucson, AZ 85724, USA
| | - Jorge Franco
- University of Arizona Cancer Center, Tucson, AZ 85724, USA; Department of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Christopher J Lord
- CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Erik S Knudsen
- University of Arizona Cancer Center, Tucson, AZ 85724, USA; Department of Medicine, University of Arizona, Tucson, AZ 85724, USA.
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Ishak CA, Coschi CH, Roes MV, Dick FA. Disruption of CDK-resistant chromatin association by pRB causes DNA damage, mitotic errors, and reduces Condensin II recruitment. Cell Cycle 2017; 16:1430-1439. [PMID: 28723239 DOI: 10.1080/15384101.2017.1338984] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Organization of chromatin structure is indispensible to the maintenance of genome integrity. The retinoblastoma tumor suppressor protein (pRB) mediates both transcriptional repression and chromatin organization, but the independent contributions of these functions have been difficult to study. Here, we utilize a synthetic Rb1 mutant allele (F832A) that maintains pRB association at cell cycle gene promoters, but disrupts a cyclin-dependent kinase (CDK)-resistant interaction with E2F1 to reduce occupancy of pRB on intergenic chromatin. Reduced pRB chromatin association increases spontaneous γH2AX deposition and aneuploidy. Our data indicates that the CDK-resistant pRB-E2F1 scaffold recruits Condensin II to major satellite repeats to stabilize chromatin structure in interphase and mitosis through mechanisms that are distinct from silencing of repetitive sequence expression.
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Affiliation(s)
- Charles A Ishak
- a London Regional Cancer Program , London , Ontario , Canada.,b Department of Biochemistry , Western University , London , Ontario , Canada
| | - Courtney H Coschi
- a London Regional Cancer Program , London , Ontario , Canada.,b Department of Biochemistry , Western University , London , Ontario , Canada
| | - Michael V Roes
- a London Regional Cancer Program , London , Ontario , Canada.,b Department of Biochemistry , Western University , London , Ontario , Canada
| | - Frederick A Dick
- a London Regional Cancer Program , London , Ontario , Canada.,b Department of Biochemistry , Western University , London , Ontario , Canada.,c Children's Health Research Institute , London , Ontario , Canada
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8
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Evans DL, Zhang H, Ham H, Pei H, Lee S, Kim J, Billadeau DD, Lou Z. MMSET is dynamically regulated during cell-cycle progression and promotes normal DNA replication. Cell Cycle 2016; 15:95-105. [PMID: 26771714 DOI: 10.1080/15384101.2015.1121323] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The timely and precise duplication of cellular DNA is essential for maintaining genome integrity and is thus tightly-regulated. During mitosis and G1, the Origin Recognition Complex (ORC) binds to future replication origins, coordinating with multiple factors to load the minichromosome maintenance (MCM) complex onto future replication origins as part of the pre-replication complex (pre-RC). The pre-RC machinery, in turn, remains inactive until the subsequent S phase when it is required for replication fork formation, thereby initiating DNA replication. Multiple myeloma SET domain-containing protein (MMSET, a.k.a. WHSC1, NSD2) is a histone methyltransferase that is frequently overexpressed in aggressive cancers and is essential for normal human development. Several studies have suggested a role for MMSET in cell-cycle regulation; however, whether MMSET is itself regulated during cell-cycle progression has not been examined. In this study, we report that MMSET is degraded during S phase in a cullin-ring ligase 4-Cdt2 (CRL4(Cdt2)) and proteasome-dependent manner. Notably, we also report defects in DNA replication and a decreased association of pre-RC factors with chromatin in MMSET-depleted cells. Taken together, our results suggest a dynamic regulation of MMSET levels throughout the cell cycle, and further characterize the role of MMSET in DNA replication and cell-cycle progression.
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Affiliation(s)
- Debra L Evans
- a Mayo Graduate School, Biochemistry and Molecular Biology (BMB) Track, Mayo Clinic , Rochester , MN , USA
| | - Haoxing Zhang
- b Division of Oncology Research , Department of Oncology, Mayo Clinic , Rochester , MN , USA.,c School of life sciences, Southwest University , Chongqing , China
| | - Hyoungjun Ham
- d Mayo Graduate School, Immunology Track, Mayo Clinic , Rochester , MN , USA
| | - Huadong Pei
- b Division of Oncology Research , Department of Oncology, Mayo Clinic , Rochester , MN , USA.,e State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine , Beijing , China
| | - SeungBaek Lee
- b Division of Oncology Research , Department of Oncology, Mayo Clinic , Rochester , MN , USA
| | - JungJin Kim
- b Division of Oncology Research , Department of Oncology, Mayo Clinic , Rochester , MN , USA
| | - Daniel D Billadeau
- b Division of Oncology Research , Department of Oncology, Mayo Clinic , Rochester , MN , USA.,d Mayo Graduate School, Immunology Track, Mayo Clinic , Rochester , MN , USA
| | - Zhenkun Lou
- b Division of Oncology Research , Department of Oncology, Mayo Clinic , Rochester , MN , USA
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Tonsing-Carter E, Bailey BJ, Saadatzadeh MR, Ding J, Wang H, Sinn AL, Peterman KM, Spragins TK, Silver JM, Sprouse AA, Georgiadis TM, Gunter TZ, Long EC, Minto RE, Marchal CC, Batuello CN, Safa AR, Hanenberg H, Territo PR, Sandusky GE, Mayo LD, Eischen CM, Shannon HE, Pollok KE. Potentiation of Carboplatin-Mediated DNA Damage by the Mdm2 Modulator Nutlin-3a in a Humanized Orthotopic Breast-to-Lung Metastatic Model. Mol Cancer Ther 2015; 14:2850-63. [PMID: 26494859 DOI: 10.1158/1535-7163.mct-15-0237] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 09/30/2015] [Indexed: 12/31/2022]
Abstract
Triple-negative breast cancers (TNBC) are typically resistant to treatment, and strategies that build upon frontline therapy are needed. Targeting the murine double minute 2 (Mdm2) protein is an attractive approach, as Mdm2 levels are elevated in many therapy-refractive breast cancers. The Mdm2 protein-protein interaction inhibitor Nutlin-3a blocks the binding of Mdm2 to key signaling molecules such as p53 and p73α and can result in activation of cell death signaling pathways. In the present study, the therapeutic potential of carboplatin and Nutlin-3a to treat TNBC was investigated, as carboplatin is under evaluation in clinical trials for TNBC. In mutant p53 TMD231 TNBC cells, carboplatin and Nutlin-3a led to increased Mdm2 and was strongly synergistic in promoting cell death in vitro. Furthermore, sensitivity of TNBC cells to combination treatment was dependent on p73α. Following combination treatment, γH2AX increased and Mdm2 localized to a larger degree to chromatin compared with single-agent treatment, consistent with previous observations that Mdm2 binds to the Mre11/Rad50/Nbs1 complex associated with DNA and inhibits the DNA damage response. In vivo efficacy studies were conducted in the TMD231 orthotopic mammary fat pad model in NOD.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ (NSG) mice. Using an intermittent dosing schedule of combined carboplatin and Nutlin-3a, there was a significant reduction in primary tumor growth and lung metastases compared with vehicle and single-agent treatments. In addition, there was minimal toxicity to the bone marrow and normal tissues. These studies demonstrate that Mdm2 holds promise as a therapeutic target in combination with conventional therapy and may lead to new clinical therapies for TNBC.
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Affiliation(s)
- Eva Tonsing-Carter
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Barbara J Bailey
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana. Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - M Reza Saadatzadeh
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana. Goodman Campbell Brain and Spine, Department of Neurosurgery, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jixin Ding
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana. Goodman Campbell Brain and Spine, Department of Neurosurgery, Indiana University School of Medicine, Indianapolis, Indiana
| | - Haiyan Wang
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Anthony L Sinn
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana
| | - Kacie M Peterman
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana
| | - Tiaishia K Spragins
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jayne M Silver
- In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana
| | - Alyssa A Sprouse
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Taxiarchis M Georgiadis
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - T Zachary Gunter
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Eric C Long
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Robert E Minto
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Christophe C Marchal
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Christopher N Batuello
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ahmad R Safa
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Helmut Hanenberg
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana. Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana. Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, Düsseldorf, Germany
| | - Paul R Territo
- Indiana Institute for Biomedical Sciences Imaging, Department of Radiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - George E Sandusky
- Department of Pathology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Lindsey D Mayo
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana. Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Christine M Eischen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Harlan E Shannon
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Karen E Pollok
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana. In Vivo Therapeutics Core, Indiana University Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana. Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana.
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10
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Carrillo AM, Bouska A, Arrate MP, Eischen CM. Mdmx promotes genomic instability independent of p53 and Mdm2. Oncogene 2015; 34:846-56. [PMID: 24608433 PMCID: PMC4160436 DOI: 10.1038/onc.2014.27] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 12/02/2013] [Accepted: 12/18/2013] [Indexed: 12/26/2022]
Abstract
The oncogene Mdmx is overexpressed in many human malignancies, and together with Mdm2, negatively regulates the p53 tumor suppressor. However, a p53-independent function of Mdmx that impacts genome stability has been described, but this function is not well understood. In the present study, we determined that of the 13 different cancer types evaluated, 6-90% of those that had elevated levels of Mdmx had concurrent inactivation (mutated or deleted) of p53. We show elevated levels of Mdmx-inhibited double-strand DNA break repair and induced chromosome and chromatid breaks independent of p53, leading to genome instability. Mdmx impaired early DNA damage-response signaling, such as phosphorylation of the serine/threonine-glutamine motif, mediated by the ATM kinase. Moreover, we identified Mdmx associated with Nbs1 of the Mre11-Rad50-Nbs1 (MRN) DNA repair complex, and this association increased upon DNA damage and was detected at chromatin. Elevated Mdmx levels also increased cellular transformation in a p53-independent manner. Unexpectedly, all Mdmx-mediated phenotypes also occurred in cells lacking Mdm2 and were independent of the Mdm2-binding domain (RING) of Mdmx. Therefore, Mdmx-mediated inhibition of the DNA damage response resulted in delayed DNA repair and increased genome instability and transformation independent of p53 and Mdm2. Our results reveal a novel p53- and Mdm2-independent oncogenic function of Mdmx that provides new insight into the many cancers that overexpress Mdmx.
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Affiliation(s)
- Alexia M. Carrillo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Alyssa Bouska
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE
| | - Maria Pia Arrate
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Christine M. Eischen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
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11
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Stolovich-Rain M, Enk J, Vikesa J, Nielsen FC, Saada A, Glaser B, Dor Y. Weaning triggers a maturation step of pancreatic β cells. Dev Cell 2015; 32:535-45. [PMID: 25662175 DOI: 10.1016/j.devcel.2015.01.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 11/26/2014] [Accepted: 12/31/2014] [Indexed: 01/22/2023]
Abstract
Because tissue regeneration deteriorates with age, it is generally assumed that the younger the animal, the better it compensates for tissue damage. We have examined the effect of young age on compensatory proliferation of pancreatic β cells in vivo. Surprisingly, β cells in suckling mice fail to enter the cell division cycle in response to a diabetogenic injury or increased glycolysis. The potential of β cells for compensatory proliferation is acquired following premature weaning to normal chow, but not to a diet mimicking maternal milk. In addition, weaning coincides with enhanced glucose-stimulated oxidative phosphorylation and insulin secretion from islets. Transcriptome analysis reveals that weaning increases the expression of genes involved in replication licensing, suggesting a mechanism for increased responsiveness to the mitogenic activity of high glucose. We propose that weaning triggers a discrete maturation step of β cells, elevating both the mitogenic and secretory response to glucose.
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Affiliation(s)
- Miri Stolovich-Rain
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Jonatan Enk
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Jonas Vikesa
- Center for Genomic Medicine, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Finn Cilius Nielsen
- Center for Genomic Medicine, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Ann Saada
- Monique and Jacques Roboh Department of Genetic Research and the Department of Genetics and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Benjamin Glaser
- Endocrinology and Metabolism Service, Department of Internal Medicine, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Yuval Dor
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
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12
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The Mcm2-7 replicative helicase: a promising chemotherapeutic target. BIOMED RESEARCH INTERNATIONAL 2014; 2014:549719. [PMID: 25243149 PMCID: PMC4163376 DOI: 10.1155/2014/549719] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/08/2014] [Accepted: 08/10/2014] [Indexed: 02/05/2023]
Abstract
Numerous eukaryotic replication factors have served as chemotherapeutic targets. One replication factor that has largely escaped drug development is the Mcm2-7 replicative helicase. This heterohexameric complex forms the licensing system that assembles the replication machinery at origins during initiation, as well as the catalytic core of the CMG (Cdc45-Mcm2-7-GINS) helicase that unwinds DNA during elongation. Emerging evidence suggests that Mcm2-7 is also part of the replication checkpoint, a quality control system that monitors and responds to DNA damage. As the only replication factor required for both licensing and DNA unwinding, Mcm2-7 is a major cellular regulatory target with likely cancer relevance. Mutations in at least one of the six MCM genes are particularly prevalent in squamous cell carcinomas of the lung, head and neck, and prostrate, and MCM mutations have been shown to cause cancer in mouse models. Moreover various cellular regulatory proteins, including the Rb tumor suppressor family members, bind Mcm2-7 and inhibit its activity. As a preliminary step toward drug development, several small molecule inhibitors that target Mcm2-7 have been recently discovered. Both its structural complexity and essential role at the interface between DNA replication and its regulation make Mcm2-7 a potential chemotherapeutic target.
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13
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KMTase Set7/9 is a critical regulator of E2F1 activity upon genotoxic stress. Cell Death Differ 2014; 21:1889-99. [PMID: 25124555 DOI: 10.1038/cdd.2014.108] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 05/01/2014] [Accepted: 06/09/2014] [Indexed: 12/20/2022] Open
Abstract
During the recent years lysine methyltransferase Set7/9 ((Su(var)-3-9, Enhancer-of-Zeste, Trithorax) domain containing protein 7/9) has emerged as an important regulator of different transcription factors. In this study, we report a novel function for Set7/9 as a critical co-activator of E2 promoter-binding factor 1 (E2F1)-dependent transcription in response to DNA damage. By means of various biochemical, cell biology, and bioinformatics approaches, we uncovered that cell-cycle progression through the G1/S checkpoint of tumour cells upon DNA damage is defined by the threshold of expression of both E2F1 and Set7/9. The latter affects the activity of E2F1 by indirectly modulating histone modifications in the promoters of E2F1-dependent genes. Moreover, Set7/9 differentially affects E2F1 transcription targets: it promotes cell proliferation via expression of the CCNE1 gene and represses apoptosis by inhibiting the TP73 gene. Our biochemical screening of the panel of lung tumour cell lines suggests that these two factors are critically important for transcriptional upregulation of the CCNE1 gene product and hence successful progression through cell cycle. These findings identify Set7/9 as a potential biomarker in tumour cells with overexpressed E2F1 activity.
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14
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Grieb BC, Gramling MW, Arrate MP, Chen X, Beauparlant SL, Haines DS, Xiao H, Eischen CM. Oncogenic protein MTBP interacts with MYC to promote tumorigenesis. Cancer Res 2014; 74:3591-602. [PMID: 24786788 DOI: 10.1158/0008-5472.can-13-2149] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Despite its involvement in most human cancers, MYC continues to pose a challenge as a readily tractable therapeutic target. Here we identify the MYC transcriptional cofactors TIP48 and TIP49 and MYC as novel binding partners of Mdm2-binding protein (MTBP), a functionally undefined protein that we show is oncogenic and overexpressed in many human cancers. MTBP associated with MYC at promoters and increased MYC-mediated transcription, proliferation, neoplastic transformation, and tumor development. In breast cancer specimens, we determined overexpression of both MYC and MTBP was associated with a reduction in 10-year patient survival compared with MYC overexpression alone. MTBP was also frequently co-amplified with MYC in many human cancers. Mechanistic investigations implicated associations with TIP48/TIP49 as well as MYC in MTBP function in cellular transformation and the growth of human breast cancer cells. Taken together, our findings show MTBP functions with MYC to promote malignancy, identifying this protein as a novel general therapeutic target in human cancer.
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Affiliation(s)
- Brian C Grieb
- Authors' Affiliations: Departments of Pathology, Microbiology and Immunology and
| | - Mark W Gramling
- Authors' Affiliations: Departments of Pathology, Microbiology and Immunology and
| | - Maria Pia Arrate
- Authors' Affiliations: Departments of Pathology, Microbiology and Immunology and
| | - Xi Chen
- Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Stephen L Beauparlant
- Department of Biochemistry, Temple University; Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania; and
| | - Dale S Haines
- Department of Biochemistry, Temple University; Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania; and
| | - Hua Xiao
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Christine M Eischen
- Authors' Affiliations: Departments of Pathology, Microbiology and Immunology and
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15
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Bourgo RJ, Ehmer U, Sage J, Knudsen ES. RB deletion disrupts coordination between DNA replication licensing and mitotic entry in vivo. Mol Biol Cell 2011; 22:931-9. [PMID: 21289097 PMCID: PMC3069018 DOI: 10.1091/mbc.e10-11-0895] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The retinoblastoma tumor suppressor (RB) is functionally inactivated at high frequency in nearly all tumor types. Herein the acute deletion of RB in the liver reveals an immediate and profound dysregulation of spatiotemporal coordination in cell-cycle phases, resulting in robust DNA damage and aneuploidy that is not found in other tissues. The integrity of the retinoblastoma tumor suppressor (RB) pathway is critical for restraining inappropriate proliferation and suppressing tumor development in a plethora of tissues. Here adenovirus-mediated RB deletion in the liver of adult mice led to DNA replication in the absence of productive mitotic condensation. The replication induced by RB loss was E2F-mediated and associated with the induction of DNA damage and a nontranscriptional G2/M checkpoint that targeted the accumulation of Cyclin B1. In the context of RB deletion or E2F activation, there was an increase in hepatocyte ploidy that was accompanied by hyperphysiological assembly of prereplication complexes. In keeping with this dysregulation, initiation of DNA replication was readily observed in hepatocytes that were phenotypically in G2/M. Under such conditions, uncoupling of replication initiation from mitotic progression led to altered genome ploidy in the liver. Interestingly, these findings in hepatocytes were not recapitulated in the basally proliferative tissues of the gastrointestinal tract, where RB deletion, while increasing DNA replication, did not lead to a profound uncoupling from mitosis. Combined, these findings demonstrate the critical role of RB in controlling cell-cycle transitions and underscore the importance of intrinsic tissue environments in resultant phenotypes.
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Affiliation(s)
- Ryan J Bourgo
- Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
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16
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Masai H, Matsumoto S, You Z, Yoshizawa-Sugata N, Oda M. Eukaryotic chromosome DNA replication: where, when, and how? Annu Rev Biochem 2010; 79:89-130. [PMID: 20373915 DOI: 10.1146/annurev.biochem.052308.103205] [Citation(s) in RCA: 370] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA replication is central to cell proliferation. Studies in the past six decades since the proposal of a semiconservative mode of DNA replication have confirmed the high degree of conservation of the basic machinery of DNA replication from prokaryotes to eukaryotes. However, the need for replication of a substantially longer segment of DNA in coordination with various internal and external signals in eukaryotic cells has led to more complex and versatile regulatory strategies. The replication program in higher eukaryotes is under a dynamic and plastic regulation within a single cell, or within the cell population, or during development. We review here various regulatory mechanisms that control the replication program in eukaryotes and discuss future directions in this dynamic field.
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Affiliation(s)
- Hisao Masai
- Genome Dynamics Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan.
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17
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Bourgo RJ, Braden WA, Wells SI, Knudsen ES. Activation of the retinoblastoma tumor suppressor mediates cell cycle inhibition and cell death in specific cervical cancer cell lines. Mol Carcinog 2009; 48:45-55. [PMID: 18506774 DOI: 10.1002/mc.20456] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
High-risk human papilloma virus (HPV) encodes two oncoproteins, E6 and E7, which are vital to viral replication and contribute to the development of cervical cancer. HPV16 E7 can target over 20 cellular proteins, but is best known for inactivating the retinoblastoma (RB) tumor suppressor. RB functions by restraining cells from entering S-phase of the cell cycle, thus preventing aberrant proliferation. While it is well established that HPV16 E7 facilitates the degradation of the RB protein, the ability of the RB pathway to overcome E7 action is less well understood. In this study the RB-pathway was activated via the overexpression of the p16ink4a tumor suppressor or ectopic expression of an active allele of RB (PSM-RB). While p16ink4a had no influence on cell cycle progression, PSM-RB expression was sufficient to induce a cell cycle arrest in both SiHa and HeLa cells, HPV positive cervical cancer cell lines. Strikingly, this arrest led to the downregulation of E2F target gene expression, which was antagonized via enhanced HPV-E7 expression. Since downmodulation of E7 function is associated with chronic growth arrest and senescence, the effect of PSM-RB on proliferation and survival was evaluated. Surprisingly, sustained PSM-RB expression impeded the proliferation of SiHa cells, resulting in both cell cycle inhibition and cell death. From these studies we conclude that active RB expression can sensitize specific cervical cancer cells to cell cycle inhibition and cell death. Thus, targeted therapies involving activation of RB function may be effective in inducing cell death in cervical cancer.
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Affiliation(s)
- Ryan J Bourgo
- Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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18
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Rizwani W, Alexandrow M, Chellappan S. Prohibitin physically interacts with MCM proteins and inhibits mammalian DNA replication. Cell Cycle 2009; 8:1621-9. [PMID: 19377303 DOI: 10.4161/cc.8.10.8578] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Prohibitin, a tumor suppressor protein, has been shown to repress E2F-mediated transcription and arrest cell cycle progression. while prohibitin has been proposed to regulate cell cycle progression by repressing transcriptional targets of E2F1, it is not clear whether other mechanisms are also involved in mediating the growth arrest. Here we demonstrate that prohibitin can function as a potent inhibitor of DNA replication by interacting with members of Minichromosome maintenance complex of proteins (MCM2-7). The data presented here indicates that prohibitin can physically interact with MCM2, MCM5 and MCM7 in in vitro GST binding assays as well as in MCF-7 cells as seen by immunoprecipitation-western blot experiments. The association was cell cycle dependent, and more pronounced 4-8 hours after serum stimulation of quiescent cells. Prohibitin associated more robustly with MCM2 and MCM5 compared to MCM7, suggesting that prohibitin mainly interacts with the regulatory subunits of the MCM complex. Confirming these results, prohibitin was found to co-localize with MCM2, MCM5 and MCM7 in MCF-7 cells, as seen by double immunofluorescence experiments. Further, Prohibitin strongly inhibited DNA replication in an in vitro replication assay. These results strongly suggest that prohibitin effectively represses replication by interacting with the components of mammalian replication machinery and this might contribute to the growth regulatory properties of prohibitin.
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Affiliation(s)
- Wasia Rizwani
- Department of Oncologic Sciences, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA
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19
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Haferkamp S, Tran SL, Becker TM, Scurr LL, Kefford RF, Rizos H. The relative contributions of the p53 and pRb pathways in oncogene-induced melanocyte senescence. Aging (Albany NY) 2009; 1:542-56. [PMID: 20157537 PMCID: PMC2806033 DOI: 10.18632/aging.100051] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Accepted: 05/15/2009] [Indexed: 02/06/2023]
Abstract
Oncogene-induced
senescence acts as a barrier against tumour formation and has been
implicated as the mechanism preventing the transformation of benign
melanocytic lesions that frequently harbour oncogenic B-RAF or N-RAS mutations.
In
the present study we systematically assessed the relative importance
of the tumour suppressor proteins p53, p21Waf1, pRb
and p16INK4a in mediating oncogene-induced senescence in human
melanocytes.
We now show
that oncogenic N-RAS induced senescence in melanocytes is
associated with DNA damage, a potent DNA damage response and the activation
of both the p16INK4a/pRb and p53/p21Waf1 tumour
suppressor pathways. Surprisingly neither the
pharmacological inhibition of the DNA damage response pathway nor silencing of
p53 expression had any detectable impact on oncogene-induced senescence in
human melanocytes. Our data indicate that the pRb pathway is
the dominant effector of senescence in these cells, as its specific
inactivation delays the onset of senescence and weakens oncogene-induced
proliferative arrest. Furthermore, we show that although both p16INK4a
and p21Waf1 are upregulated in response to N-RASQ61K,
the activities of these CDK inhibitors are clearly distinct and only the
loss of p16INK4a weakens senescence. We propose that the ability
of p16INK4a to inhibit the cyclin D-dependent kinases and DNA
replication, functions not shared by p21Waf1, contribute to its
role in senescence. Thus, in melanocytes with oncogenic signalling only p16INK4a
can fully engage the pRb pathway to alter chromatin structure and
silence the genes that are required for proliferation.
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Affiliation(s)
- Sebastian Haferkamp
- Westmead Institute for Cancer Research and Melanoma Institute of Australia, University of Sydney at Westmead, Westmead NSW 2145, Australia
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20
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Mammalian MCM loading in late-G(1) coincides with Rb hyperphosphorylation and the transition to post-transcriptional control of progression into S-phase. PLoS One 2009; 4:e5462. [PMID: 19421323 PMCID: PMC2674209 DOI: 10.1371/journal.pone.0005462] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Accepted: 04/15/2009] [Indexed: 01/19/2023] Open
Abstract
Background Control of the onset of DNA synthesis in mammalian cells requires the coordinated assembly and activation of the pre-Replication Complex. In order to understand the regulatory events controlling preRC dynamics, we have investigated how the timing of preRC assembly relates temporally to other biochemical events governing progress into S-phase. Methodology/Principal Finding In murine and Chinese hamster (CHO) cells released from quiescence, the loading of the replicative MCM helicase onto chromatin occurs in the final 3–4 hrs of G1. Cdc45 and PCNA, both of which are required for G1-S transit, bind to chromatin at the G1-S transition or even earlier in G1, when MCMs load. An RNA polymerase II inhibitor (DRB) was added to synchronized murine keratinocytes to show that they are no longer dependent on new mRNA synthesis 3–4 hrs prior to S-phase entry, which is also true for CHO and human cells. Further, CHO cells can progress into S-phase on time, and complete S-phase, under conditions where new mRNA synthesis is significantly compromised, and such mRNA suppression causes no adverse effects on preRC dynamics prior to, or during, S-phase progression. Even more intriguing, hyperphosphorylation of Rb coincides with the start of MCM loading and, paradoxically, with the time in late-G1 when de novo mRNA synthesis is no longer rate limiting for progression into S-phase. Conclusions/Significance MCM, Cdc45, and PCNA loading, and the subsequent transit through G1-S, do not depend on concurrent new mRNA synthesis. These results indicate that mammalian cells pass through a distinct transition in late-G1 at which time Rb becomes hyperphosphorylated and MCM loading commences, but that after this transition the control of MCM, Cdc45, and PCNA loading and the onset of DNA replication are regulated at the post-transcriptional level.
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21
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Deng M, Li F, Ballif BA, Li S, Chen X, Guo L, Ye X. Identification and functional analysis of a novel cyclin e/cdk2 substrate ankrd17. J Biol Chem 2009; 284:7875-88. [PMID: 19150984 DOI: 10.1074/jbc.m807827200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Cyclin E/Cdk2 is a key regulator in G(1)-S transition. We have identified a novel cyclin E/Cdk2 substrate called Ankrd17 (ankyrin repeat protein 17) using the TAP tag purification technique. Ankrd17 protein contains two clusters of a total 25 ankyrin repeats at its N terminus, one NES (nuclear exporting signal) and one NLS (nuclear localization signal) in the middle, and one RXL motif at its C terminus. Ankrd17 is expressed in various tissues and associates with cyclin E/Cdk2 in an RXL-dependent manner. It can be phosphorylated by cyclin E/Cdk2 at 3 phosphorylation sites (Ser(1791), Ser(1794), and Ser(2150)). Overexpression of Ankrd17 promotes S phase entry, whereas depletion of Ankrd17 expression by small interfering RNA inhibits DNA replication and blocks cell cycle progression as well as up-regulates the expression of p53 and p21. Ankrd17 is localized to the nucleus and interacts with DNA replication factors including MCM family members, Cdc6 and PCNA. Depletion of Ankrd17 results in decreased loading of Cdc6 and PCNA onto DNA suggesting that Ankrd17 may be directly involved in the DNA replication process. Taken together, these data indicate that Ankrd17 is an important downstream effector of cyclin E/Cdk2 and positively regulates G(1)/S transition.
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Affiliation(s)
- Min Deng
- Department of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
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22
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Braden WA, McClendon AK, Knudsen ES. Cyclin-dependent kinase 4/6 activity is a critical determinant of pre-replication complex assembly. Oncogene 2008; 27:7083-93. [PMID: 18776921 DOI: 10.1038/onc.2008.319] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cyclin-dependent kinases (CDKs) are important in regulating cell cycle transitions, particularly in coordinating DNA replication. Although the role of CDK2 activity on the replication apparatus has been extensively studied, the role of CDK4/6 in DNA replication control is less understood. Through targeted inhibition of CDK4/6 activity, we demonstrate that CDK4/6 kinase activity promotes cdc6 and cdt1 expression, and pre-replication complex (pre-RC) assembly in cycling cells. Conversely, CDK2 inhibition had no effect on the pre-RC assembly. The inhibition of pre-RC assembly is dependent on a functional retinoblastoma (RB) protein, which mediates downstream effects. As such, CDK4/6 inhibition has minimal effect on the replication apparatus in the absence of RB. The requirement of CDK4/6 was further interrogated using cells lacking D-type cyclins, in which replication complexes form normally, and correspondingly CDK4/6 inhibition had no effect on cell cycle or replication control. However, in the absence of D-type cyclins, CDK2 inhibition resulted in the attenuation of cdc6 and cdt1 levels, suggesting overlapping roles for CDK4/6 and CDK2 in regulating replication protein activity. Finally, CDK4/6 inhibition prevented the accumulation of cdc6 and cdt1 as cells progressed from mitosis through the subsequent G(1). Combined, these studies indicate that CDK4/6 activity is important in regulating the expression of these critical mediators of DNA replication.
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Affiliation(s)
- W A Braden
- Department of Cancer Biology and the Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
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23
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Dorn ES, Chastain PD, Hall JR, Cook JG. Analysis of re-replication from deregulated origin licensing by DNA fiber spreading. Nucleic Acids Res 2008; 37:60-9. [PMID: 19010964 PMCID: PMC2615611 DOI: 10.1093/nar/gkn912] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A major challenge each human cell-division cycle is to ensure that DNA replication origins do not initiate more than once, a phenomenon known as re-replication. Acute deregulation of replication control ultimately causes extensive DNA damage, cell-cycle checkpoint activation and cell death whereas moderate deregulation promotes genome instability and tumorigenesis. In the absence of detectable increases in cellular DNA content however, it has been difficult to directly demonstrate re-replication or to determine if the ability to re-replicate is restricted to a particular cell-cycle phase. Using an adaptation of DNA fiber spreading we report the direct detection of re-replication on single DNA molecules from human chromosomes. Using this method we demonstrate substantial re-replication within 1 h of S phase entry in cells overproducing the replication factor, Cdt1. Moreover, a comparison of the HeLa cancer cell line to untransformed fibroblasts suggests that HeLa cells produce replication signals consistent with low-level re-replication in otherwise unperturbed cell cycles. Re-replication after depletion of the Cdt1 inhibitor, geminin, in an untransformed fibroblast cell line is undetectable by standard assays but readily quantifiable by DNA fiber spreading analysis. Direct evaluation of re-replicated DNA molecules will promote increased understanding of events that promote or perturb genome stability.
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Affiliation(s)
- Elizabeth S Dorn
- Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7260, USA
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24
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Hall JR, Lee HO, Bunker BD, Dorn ES, Rogers GC, Duronio RJ, Cook JG. Cdt1 and Cdc6 are destabilized by rereplication-induced DNA damage. J Biol Chem 2008; 283:25356-25363. [PMID: 18617514 DOI: 10.1074/jbc.m802667200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The replication factors Cdt1 and Cdc6 are essential for origin licensing, a prerequisite for DNA replication initiation. Mechanisms to ensure that metazoan origins initiate once per cell cycle include degradation of Cdt1 during S phase and inhibition of Cdt1 by the geminin protein. Geminin depletion or overexpression of Cdt1 or Cdc6 in human cells causes rereplication, a form of endogenous DNA damage. Rereplication induced by these manipulations is however uneven and incomplete, suggesting that one or more mechanisms restrain rereplication once it begins. We find that both Cdt1 and Cdc6 are degraded in geminin-depleted cells. We further show that Cdt1 degradation in cells that have rereplicated requires the PCNA binding site of Cdt1 and the Cul4(DDB1) ubiquitin ligase, and Cdt1 can induce its own degradation when overproduced. Cdc6 degradation in geminin-depleted cells requires Huwe1, the ubiquitin ligase that regulates Cdc6 after DNA damage. Moreover, perturbations that specifically disrupt Cdt1 and Cdc6 degradation in response to DNA damage exacerbate rereplication when combined with geminin depletion, and this enhanced rereplication occurs in both human cells and in Drosophila melanogaster cells. We conclude that rereplication-associated DNA damage triggers Cdt1 and Cdc6 ubiquitination and destruction, and propose that this pathway represents an evolutionarily conserved mechanism that minimizes the extent of rereplication.
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Affiliation(s)
- Jonathan R Hall
- Department of Biochemistry and Biophysics, Chapel Hill, North Carolina 27599-7260
| | - Hyun O Lee
- Department of Curriculum in Genetics and Molecular Biology, Chapel Hill, North Carolina 27599-7260
| | - Brandon D Bunker
- Department of Biochemistry and Biophysics, Chapel Hill, North Carolina 27599-7260
| | - Elizabeth S Dorn
- Department of Biochemistry and Biophysics, Chapel Hill, North Carolina 27599-7260
| | - Greg C Rogers
- Department of Biology, Chapel Hill, North Carolina 27599-7260
| | - Robert J Duronio
- Department of Curriculum in Genetics and Molecular Biology, Chapel Hill, North Carolina 27599-7260; Department of Biology, Chapel Hill, North Carolina 27599-7260; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7260
| | - Jeanette Gowen Cook
- Department of Biochemistry and Biophysics, Chapel Hill, North Carolina 27599-7260; Department of Curriculum in Genetics and Molecular Biology, Chapel Hill, North Carolina 27599-7260; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7260.
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25
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Kinkade R, Dasgupta P, Carie A, Pernazza D, Carless M, Pillai S, Lawrence N, Sebti SM, Chellappan S. A small molecule disruptor of Rb/Raf-1 interaction inhibits cell proliferation, angiogenesis, and growth of human tumor xenografts in nude mice. Cancer Res 2008; 68:3810-8. [PMID: 18483265 DOI: 10.1158/0008-5472.can-07-6672] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although it is well established that cyclin-dependent kinases phosphorylate and inactivate Rb, the Raf-1 kinase physically interacts with Rb and initiates the phosphorylation cascade early in the cell cycle. We have identified an orally active small molecule, Rb/Raf-1 disruptor 251 (RRD-251), that potently and selectively disrupts the Rb/Raf-1 but not Rb/E2F, Rb/prohibitin, Rb/cyclin E, and Rb/HDAC binding. The selective inhibition of Rb/Raf-1 binding suppressed the ability of Rb to recruit Raf-1 to proliferative promoters and inhibited E2F1-dependent transcriptional activity. RRD-251 inhibited anchorage-dependent and anchorage-independent growth of human cancer cells and knockdown of Rb with short hairpin RNA or forced expression of E2F1 rescued cells from RRD-251-mediated growth arrest. P.o. treatment of mice resulted in significant tumor growth suppression only in tumors with functional Rb, and this was accompanied by inhibition of angiogenesis, inhibition of proliferation, decreased phosphorylated Rb levels, and inhibition of Rb/Raf-1 but not Rb/E2F1 binding in vivo. Thus, selective targeting of Rb/Raf-1 interaction seems to be a promising approach for developing novel chemotherapeutic agents.
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Affiliation(s)
- Rebecca Kinkade
- Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
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Souza-Rodrígues E, Estanyol JM, Friedrich-Heineken E, Olmedo E, Vera J, Canela N, Brun S, Agell N, Hübscher U, Bachs O, Jaumot M. Proteomic analysis of p16ink4a-binding proteins. Proteomics 2008; 7:4102-11. [PMID: 17955473 DOI: 10.1002/pmic.200700133] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The p16(ink4a) tumor suppressor protein plays a critical role in cell cycle control, tumorogenesis and senescence. The best known activity for p16(ink4a) is the inhibition of the activity of CDK4 and CDK6 kinases, both playing a key role in cell cycle progression. With the aim to study new p16(ink4a) functions we used affinity chromatography and MS techniques to identify new p16(ink4a)-interacting proteins. We generated p16(ink4a) columns by coupling the protein to activated Sepharose 4B. The proteins from MOLT-4 cell line that bind to p16(ink4a) affinity columns were resolved by SDS-PAGE and identified by MS using a MALDI-TOF. Thirty-one p16(ink4a) -interacting proteins were identified and grouped in functional clusters. The identification of two of them, proliferating cell nuclear antigen (PCNA) and minichromosome maintenance protein 6 (MCM6), was confirmed by Western blotting and their in vivo interactions with p16(ink4a) were demonstrated by immunoprecipitation and immunofluorescence studies. Results also revealed that p16(ink4a) interacts directly with the DNA polymerase delta accessory protein PCNA and thereby inhibits the polymerase activity.
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Affiliation(s)
- Elielson Souza-Rodrígues
- Departament de Biologia Cellular i Anatomia Patològica, Facultat de Medicina, Universitat de Barcelona, Spain
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27
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Abstract
Prostate cancer (PCa) cell proliferation is dependent on activation of the androgen receptor (AR), a ligand-dependent transcription factor. AR activation controls G1-S phase progression through fostering enhanced translation of the D-type cyclins, which promote cell cycle progression through activation of CDK4/6. However, the D-type cyclins harbor additional, CDK4/6 kinase-independent, functions through manipulation of transcription factors, including AR. It was previously established that cyclins D1 and D3 have the potential to modulate AR, and with regard to cyclin D1, disruption of this function occurs in human tumors. Therefore, it was essential to interrogate cyclin D3 function in this tumor type. Here, we show that cyclin D3 is found in association with AR in PCa cells, as mediated through a conserved motif. Cyclin D3 functions to attenuate AR activity through defined mechanisms that include modulation of ligand-dependent conformational changes and modulation of chromatin binding activity. Accumulated cyclin D3 slows cell proliferation in AR-dependent cells, thus suggesting that androgen-induced D-type cyclin production serves to temper the mitogenic response to androgen. Supporting this hypothesis, it is shown that cyclin D3 expression is reduced in primary PCas as a function of tumor grade, and inversely correlates with the proliferative index. In total, these data identify cyclin D3 as a critical modulator of the androgen response, whose deregulation may foster unchecked AR activity in PCa.
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28
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Abstract
Hbo1 is a histone acetyltransferase (HAT) that is required for global histone H4 acetylation, steroid-dependent transcription, and chromatin loading of MCM2-7 during DNA replication licensing. It is the catalytic subunit of protein complexes that include ING and JADE proteins, growth regulatory factors and candidate tumor suppressors. These complexes are thought to act via tumor suppressor p53, but the molecular mechanisms and links between stress signaling and chromatin, are currently unknown. Here, we show that p53 physically interacts with Hbo1 and negatively regulates its HAT activity in vitro and in cells. Two physiological stresses that stabilize p53, hyperosmotic shock and DNA replication fork arrest, also inhibit Hbo1 HAT activity in a p53-dependent manner. Hyperosmotic stress during G(1) phase specifically inhibits the loading of the MCM2-7 complex, providing an example of the chromatin output of this pathway. These results reveal a direct regulatory connection between p53-responsive stress signaling and Hbo1-dependent chromatin pathways.
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29
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Srinivasan SV, Mayhew CN, Schwemberger S, Zagorski W, Knudsen ES. RB loss promotes aberrant ploidy by deregulating levels and activity of DNA replication factors. J Biol Chem 2007; 282:23867-77. [PMID: 17556357 DOI: 10.1074/jbc.m700542200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The retinoblastoma tumor suppressor (RB) is functionally inactivated in many human cancers. Classically, RB functions to repress E2F-mediated transcription and inhibit cell cycle progression. Consequently, RB ablation leads to loss of cell cycle control and aberrant expression of E2F target genes. Emerging evidence indicates a role for RB in maintenance of genomic stability. Here, mouse adult fibroblasts were utilized to demonstrate that aberrant DNA content in RB-deficient cells occurs concomitantly with an increase in levels and chromatin association of DNA replication factors. Furthermore, following exposure to nocodazole, RB-proficient cells arrest with 4 n DNA content, whereas RB-deficient cells bypass the mitotic block, continue DNA synthesis, and accumulate cells with higher ploidy and micronuclei. Under this condition, RB-deficient cells also retain high levels of tethered replication factors, MCM7 and PCNA, indicating that DNA replication occurs in these cells under nonpermissive conditions. Exogenous expression of replication factors Cdc6 or Cdt1 in RB-proficient cells does not recapitulate the RB-deficient cell phenotype. However, ectopic E2F expression in RB-proficient cells elevated ploidy and bypassed the response to nocodazole-induced cessation of DNA replication in a manner analogous to RB loss. Collectively, these results demonstrate that deregulated S phase control is a key mechanism by which RB-deficient cells acquire elevated ploidy.
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Affiliation(s)
- Seetha V Srinivasan
- Department of Cell and Cancer Biology, Vontz Center for Molecular Studies, Ohio 45267, USA
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