1
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ARAF protein kinase activates RAS by antagonizing its binding to RASGAP NF1. Mol Cell 2022; 82:2443-2457.e7. [PMID: 35613620 DOI: 10.1016/j.molcel.2022.04.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 03/02/2022] [Accepted: 04/26/2022] [Indexed: 12/13/2022]
Abstract
RAF protein kinases are effectors of the GTP-bound form of small guanosine triphosphatase RAS and function by phosphorylating MEK. We showed here that the expression of ARAF activated RAS in a kinase-independent manner. Binding of ARAF to RAS displaced the GTPase-activating protein NF1 and antagonized NF1-mediated inhibition of RAS. This reduced ERK-dependent inhibition of RAS and increased RAS-GTP. By this mechanism, ARAF regulated the duration and consequences of RTK-induced RAS activation and supported the RAS output of RTK-dependent tumor cells. In human lung cancers with EGFR mutation, amplification of ARAF was associated with acquired resistance to EGFR inhibitors, which was overcome by combining EGFR inhibitors with an inhibitor of the protein tyrosine phosphatase SHP2 to enhance inhibition of nucleotide exchange and RAS activation.
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2
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Zhao J, Luo Z. Discovery of Raf Family Is a Milestone in Deciphering the Ras-Mediated Intracellular Signaling Pathway. Int J Mol Sci 2022; 23:ijms23095158. [PMID: 35563547 PMCID: PMC9101324 DOI: 10.3390/ijms23095158] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/02/2022] [Accepted: 05/03/2022] [Indexed: 01/27/2023] Open
Abstract
The Ras-Raf-MEK-ERK signaling pathway, the first well-established MAPK pathway, plays essential roles in cell proliferation, survival, differentiation and development. It is activated in over 40% of human cancers owing to mutations of Ras, membrane receptor tyrosine kinases and other oncogenes. The Raf family consists of three isoforms, A-Raf, B-Raf and C-Raf. Since the first discovery of a truncated mutant of C-Raf as a transforming oncogene carried by a murine retrovirus, forty years of extensive studies have provided a wealth of information on the mechanisms underlying the activation, regulation and biological functions of the Raf family. However, the mechanisms by which activation of A-Raf and C-Raf is accomplished are still not completely understood. In contrast, B-Raf can be easily activated by binding of Ras-GTP, followed by cis-autophosphorylation of the activation loop, which accounts for the fact that this isoform is frequently mutated in many cancers, especially melanoma. The identification of oncogenic B-Raf mutations has led to accelerated drug development that targets Raf signaling in cancer. However, the effort has not proved as effective as anticipated, inasmuch as the mechanism of Raf activation involves multiple steps, factors and phosphorylation of different sites, as well as complex interactions between Raf isoforms. In this review, we will focus on the physiological complexity of the regulation of Raf kinases and their connection to the ERK phosphorylation cascade and then discuss the role of Raf in tumorigenesis and the clinical application of Raf inhibitors in the treatment of cancer.
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Affiliation(s)
- Jingtong Zhao
- Queen Mary School, Nanchang University, Nanchang 330031, China;
| | - Zhijun Luo
- Queen Mary School, Nanchang University, Nanchang 330031, China;
- Provincial Key Laboratory of Tumor Pathogens and Molecular Pathology, Nanchang University, Nanchang 330031, China
- NCU-QMUL Joint Research Institute of Precision Medical Science, Nanchang 330031, China
- Correspondence:
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3
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Venkatanarayan A, Liang J, Yen I, Shanahan F, Haley B, Phu L, Verschueren E, Hinkle TB, Kan D, Segal E, Long JE, Lima T, Liau NPD, Sudhamsu J, Li J, Klijn C, Piskol R, Junttila MR, Shaw AS, Merchant M, Chang MT, Kirkpatrick DS, Malek S. CRAF dimerization with ARAF regulates KRAS-driven tumor growth. Cell Rep 2022; 38:110351. [PMID: 35139374 DOI: 10.1016/j.celrep.2022.110351] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 09/21/2021] [Accepted: 01/19/2022] [Indexed: 02/07/2023] Open
Abstract
KRAS, which is mutated in ∼30% of all cancers, activates the RAF-MEK-ERK signaling cascade. CRAF is required for growth of KRAS mutant lung tumors, but the requirement for CRAF kinase activity is unknown. Here, we show that subsets of KRAS mutant tumors are dependent on CRAF for growth. Kinase-dead but not dimer-defective CRAF rescues growth inhibition, suggesting that dimerization but not kinase activity is required. Quantitative proteomics demonstrates increased levels of CRAF:ARAF dimers in KRAS mutant cells, and depletion of both CRAF and ARAF rescues the CRAF-loss phenotype. Mechanistically, CRAF depletion causes sustained ERK activation and induction of cell-cycle arrest, while treatment with low-dose MEK or ERK inhibitor rescues the CRAF-loss phenotype. Our studies highlight the role of CRAF in regulating MAPK signal intensity to promote tumorigenesis downstream of mutant KRAS and suggest that disrupting CRAF dimerization or degrading CRAF may have therapeutic benefit.
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Affiliation(s)
| | - Jason Liang
- Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA; Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Ivana Yen
- Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Frances Shanahan
- Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Benjamin Haley
- Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Lilian Phu
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Erik Verschueren
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Trent B Hinkle
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - David Kan
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Ehud Segal
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jason E Long
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Tony Lima
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Nicholas P D Liau
- Department of Structural Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jawahar Sudhamsu
- Department of Structural Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jason Li
- Department of Bioinformatics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Christiaan Klijn
- Department of Bioinformatics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Robert Piskol
- Department of Bioinformatics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Melissa R Junttila
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Andrey S Shaw
- Department of Research Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Mark Merchant
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Matthew T Chang
- Department of Bioinformatics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Donald S Kirkpatrick
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Shiva Malek
- Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
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4
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Abstract
The RASopathies are a group of disorders caused by a germline mutation in one of the genes encoding a component of the RAS/MAPK pathway. These disorders, including neurofibromatosis type 1, Noonan syndrome, cardiofaciocutaneous syndrome, Costello syndrome and Legius syndrome, among others, have overlapping clinical features due to RAS/MAPK dysfunction. Although several of the RASopathies are very rare, collectively, these disorders are relatively common. In this Review, we discuss the pathogenesis of the RASopathy-associated genetic variants and the knowledge gained about RAS/MAPK signaling that resulted from studying RASopathies. We also describe the cell and animal models of the RASopathies and explore emerging RASopathy genes. Preclinical and clinical experiences with targeted agents as therapeutics for RASopathies are also discussed. Finally, we review how the recently developed drugs targeting RAS/MAPK-driven malignancies, such as inhibitors of RAS activation, direct RAS inhibitors and RAS/MAPK pathway inhibitors, might be leveraged for patients with RASopathies.
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Affiliation(s)
- Katie E Hebron
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Edjay Ralph Hernandez
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Marielle E Yohe
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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5
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Ullah R, Yin Q, Snell AH, Wan L. RAF-MEK-ERK pathway in cancer evolution and treatment. Semin Cancer Biol 2021; 85:123-154. [PMID: 33992782 DOI: 10.1016/j.semcancer.2021.05.010] [Citation(s) in RCA: 134] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/03/2021] [Accepted: 05/06/2021] [Indexed: 12/13/2022]
Abstract
The RAF-MEK-ERK signaling cascade is a well-characterized MAPK pathway involved in cell proliferation and survival. The three-layered MAPK signaling cascade is initiated upon RTK and RAS activation. Three RAF isoforms ARAF, BRAF and CRAF, and their downstream MEK1/2 and ERK1/2 kinases constitute a coherently orchestrated signaling module that directs a range of physiological functions. Genetic alterations in this pathway are among the most prevalent in human cancers, which consist of numerous hot-spot mutations such as BRAFV600E. Oncogenic mutations in this pathway often override otherwise tightly regulated checkpoints to open the door for uncontrolled cell growth and neoplasia. The crosstalk between the RAF-MEK-ERK axis and other signaling pathways further extends the proliferative potential of this pathway in human cancers. In this review, we summarize the molecular architecture and physiological functions of the RAF-MEK-ERK pathway with emphasis on its dysregulations in human cancers, as well as the efforts made to target the RAF-MEK-ERK module using small molecule inhibitors.
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Affiliation(s)
- Rahim Ullah
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Qing Yin
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Aidan H Snell
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Lixin Wan
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA; Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA.
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6
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Impairment of the neurotrophic signaling hub B-Raf contributes to motoneuron degeneration in spinal muscular atrophy. Proc Natl Acad Sci U S A 2021; 118:2007785118. [PMID: 33931501 DOI: 10.1073/pnas.2007785118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a motoneuron disease caused by deletions of the Survival of Motoneuron 1 gene (SMN1) and low SMN protein levels. SMN restoration is the concept behind a number of recently approved drugs which result in impressive yet limited effects. Since SMN has already been enhanced in treated patients, complementary SMN-independent approaches are needed. Previously, a number of altered signaling pathways which regulate motoneuron degeneration have been identified as candidate targets. However, signaling pathways form networks, and their connectivity is still unknown in SMA. Here, we used presymptomatic SMA mice to elucidate the network of altered signaling in SMA. The SMA network is structured in two clusters with AKT and 14-3-3 ζ/δ in their centers. Both clusters are connected by B-Raf as a major signaling hub. The direct interaction of B-Raf with 14-3-3 ζ/δ is important for an efficient neurotrophic activation of the MEK/ERK pathway and crucial for motoneuron survival. Further analyses in SMA mice revealed that both proteins were down-regulated in motoneurons and the spinal cord with B-Raf being reduced at presymptomatic stages. Primary fibroblasts and iPSC-derived motoneurons from SMA patients both showed the same pattern of down-regulation. This mechanism is conserved across species since a Caenorhabditis elegans SMA model showed less expression of the B-Raf homolog lin-45 Accordingly, motoneuron survival was rescued by a cell autonomous lin-45 expression in a C. elegans SMA model resulting in improved motor functions. This rescue was effective even after the onset of motoneuron degeneration and mediated by the MEK/ERK pathway.
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7
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Drosten M, Barbacid M. Targeting the MAPK Pathway in KRAS-Driven Tumors. Cancer Cell 2020; 37:543-550. [PMID: 32289276 DOI: 10.1016/j.ccell.2020.03.013] [Citation(s) in RCA: 260] [Impact Index Per Article: 65.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/26/2020] [Accepted: 03/16/2020] [Indexed: 12/19/2022]
Abstract
KRAS mutations occur in a quarter of all of human cancers, yet no selective drug has been approved to treat these tumors. Despite the recent development of drugs that block KRASG12C, the majority of KRAS oncoproteins remain undruggable. Here, we review recent efforts to validate individual components of the mitogen-activated protein kinase (MAPK) pathway as targets to treat KRAS-mutant cancers by comparing genetic information derived from experimental mouse models of KRAS-driven lung and pancreatic tumors with the outcome of selective MAPK inhibitors in clinical trials. We also review the potential of RAF1 as a key target to block KRAS-mutant cancers.
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Affiliation(s)
- Matthias Drosten
- Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
| | - Mariano Barbacid
- Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
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8
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Wei J, Zhao Z, Gao J, Wang Y, Ma L, Meng X, Wang Z. Polyacrylamide/Phytic Acid/Polydopamine Hydrogel as an Efficient Substrate for Electrochemical Enrichment of Circulating Cell-Free DNA from Blood Plasma. ACS OMEGA 2020; 5:5365-5371. [PMID: 32201826 PMCID: PMC7081438 DOI: 10.1021/acsomega.9b04397] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 02/20/2020] [Indexed: 05/26/2023]
Abstract
A facile method has been developed for the rapid and efficient enrichment of DNAs from different media including synthetic single-strand DNAs (ssDNAs) from buffer solutions and cell-free DNAs (cfDNAs) from blood plasma through electric field-driven adsorption and desorption of DNAs by a polyacrylamide/phytic acid/polydopamine (PAAM/PA/PDA) hydrogel. The as-prepared PAAM/PA/PDA hydrogel possesses regular porosity with a large surface area, strong electric field responsiveness/good conductivity, and a rich aromatic structure, which can be used as an ideal adsorbent for DNA enrichment under a positive electric field. The enriched DNAs can be released efficiently when the positive electric field is converted to a negative electric field. The PAAM/PA/PDA hydrogel-based electrochemical method enables the completion of the process of DNA adsorption and release within 5 min and exhibits reasonable enrichment efficiencies and recovery rates of various DNAs. For instance, the high enrichment sensitivity (0.1 pmol L-1) together with the excellent recovery (>75%) of an ssDNA with 78 nucleotides is obtained. Combined with the PCR amplification technique, the practicability of the as-proposed method is demonstrated by the screening of circulating tumor DNAs (ctDNAs) with a BRAFV600E mutation in cfDNAs from the blood plasma samples of patients with papillary thyroid cancer or thyroid nodule and random patients from a clinical laboratory.
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Affiliation(s)
- Jia Wei
- Department
of Thyroid Surgery, The First Hospital of
Jilin University, Changchun, Jilin 130021, P. R. China
| | - Zhen Zhao
- State
Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Jiaxue Gao
- State
Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Yaoqi Wang
- Department
of Thyroid Surgery, The First Hospital of
Jilin University, Changchun, Jilin 130021, P. R. China
| | - Lina Ma
- State
Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Xianying Meng
- Department
of Thyroid Surgery, The First Hospital of
Jilin University, Changchun, Jilin 130021, P. R. China
| | - Zhenxin Wang
- State
Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
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9
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Degirmenci U, Wang M, Hu J. Targeting Aberrant RAS/RAF/MEK/ERK Signaling for Cancer Therapy. Cells 2020; 9:E198. [PMID: 31941155 PMCID: PMC7017232 DOI: 10.3390/cells9010198] [Citation(s) in RCA: 296] [Impact Index Per Article: 74.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 12/29/2019] [Accepted: 01/10/2020] [Indexed: 12/13/2022] Open
Abstract
The RAS/RAF/MEK/ERK (MAPK) signaling cascade is essential for cell inter- and intra-cellular communication, which regulates fundamental cell functions such as growth, survival, and differentiation. The MAPK pathway also integrates signals from complex intracellular networks in performing cellular functions. Despite the initial discovery of the core elements of the MAPK pathways nearly four decades ago, additional findings continue to make a thorough understanding of the molecular mechanisms involved in the regulation of this pathway challenging. Considerable effort has been focused on the regulation of RAF, especially after the discovery of drug resistance and paradoxical activation upon inhibitor binding to the kinase. RAF activity is regulated by phosphorylation and conformation-dependent regulation, including auto-inhibition and dimerization. In this review, we summarize the recent major findings in the study of the RAS/RAF/MEK/ERK signaling cascade, particularly with respect to the impact on clinical cancer therapy.
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Affiliation(s)
- Ufuk Degirmenci
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescent, Singapore 169610, Singapore
| | - Mei Wang
- Cancer and Stem Cell Biology Program, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Jiancheng Hu
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescent, Singapore 169610, Singapore
- Cancer and Stem Cell Biology Program, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
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10
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Zaballos MA, Acuña-Ruiz A, Morante M, Crespo P, Santisteban P. Regulators of the RAS-ERK pathway as therapeutic targets in thyroid cancer. Endocr Relat Cancer 2019; 26:R319-R344. [PMID: 30978703 DOI: 10.1530/erc-19-0098] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/30/2022]
Abstract
Thyroid cancer is mostly an ERK-driven carcinoma, as up to 70% of thyroid carcinomas are caused by mutations that activate the RAS/ERK mitogenic signaling pathway. The incidence of thyroid cancer has been steadily increasing for the last four decades; yet, there is still no effective treatment for advanced thyroid carcinomas. Current research efforts are focused on impairing ERK signaling with small-molecule inhibitors, mainly at the level of BRAF and MEK. However, despite initial promising results in animal models, the clinical success of these inhibitors has been limited by the emergence of tumor resistance and relapse. The RAS/ERK pathway is an extremely complex signaling cascade with multiple points of control, offering many potential therapeutic targets: from the modulatory proteins regulating the activation state of RAS proteins to the scaffolding proteins of the pathway that provide spatial specificity to the signals, and finally, the negative feedbacks and phosphatases responsible for inactivating the pathway. The aim of this review is to give an overview of the biology of RAS/ERK regulators in human cancer highlighting relevant information on thyroid cancer and future areas of research.
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Affiliation(s)
- Miguel A Zaballos
- Instituto de Investigaciones Biomédicas 'Alberto Sols', Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Instituto de Salud Carlos III, Madrid, Spain
| | - Adrián Acuña-Ruiz
- Instituto de Investigaciones Biomédicas 'Alberto Sols', Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Instituto de Salud Carlos III, Madrid, Spain
| | - Marta Morante
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Instituto de Salud Carlos III, Madrid, Spain
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Cantabria, Santander, Spain
| | - Piero Crespo
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Instituto de Salud Carlos III, Madrid, Spain
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Cantabria, Santander, Spain
| | - Pilar Santisteban
- Instituto de Investigaciones Biomédicas 'Alberto Sols', Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Instituto de Salud Carlos III, Madrid, Spain
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11
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Pfeiffer V, Götz R, Camarero G, Heinsen H, Blum R, Rapp UR. Impaired neuronal maturation of hippocampal neural progenitor cells in mice lacking CRAF. PLoS One 2018; 13:e0192067. [PMID: 29590115 PMCID: PMC5873938 DOI: 10.1371/journal.pone.0192067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 01/16/2018] [Indexed: 11/19/2022] Open
Abstract
RAF kinases are major constituents of the mitogen activated signaling pathway, regulating cell proliferation, differentiation and cell survival of many cell types, including neurons. In mammals, the family of RAF proteins consists of three members, ARAF, BRAF, and CRAF. Ablation of CRAF kinase in inbred mouse strains causes major developmental defects during fetal growth and embryonic or perinatal lethality. Heterozygous germline mutations in CRAF result in Noonan syndrome, which is characterized by neurocognitive impairment that may involve hippocampal physiology. The role of CRAF signaling during hippocampal development and generation of new postnatal hippocampal granule neurons has not been examined and may provide novel insight into the cause of hippocampal dysfunction in Noonan syndrome. In this study, by crossing CRAF-deficiency to CD-1 outbred mice, a CRAF mouse model was established which enabled us to investigate the interplay of neural progenitor proliferation and postmitotic differentiation during adult neurogenesis in the hippocampus. Albeit the general morphology of the hippocampus was unchanged, CRAF-deficient mice displayed smaller granule cell layer (GCL) volume at postnatal day 30 (P30). In CRAF-deficient mice a substantial number of abnormal, chromophilic, fast dividing cells were found in the subgranular zone (SGZ) and hilus of the dentate gyrus (DG), indicating that CRAF signaling contributes to hippocampal neural progenitor proliferation. CRAF-deficient neural progenitor cells showed an increased cell death rate and reduced neuronal maturation. These results indicate that CRAF function affects postmitotic neural cell differentiation and points to a critical role of CRAF-dependent growth factor signaling pathway in the postmitotic development of adult-born neurons.
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Affiliation(s)
- Verena Pfeiffer
- University of Würzburg, Institute of Anatomy and Cell Biology, Koellikerstraße 6, Würzburg, Germany
- University of Würzburg, Institute for Medical Radiation and Cell Research (MSZ), Versbacher Strasse 5, Würzburg, Germany
- * E-mail:
| | - Rudolf Götz
- University of Würzburg, Institute for Medical Radiation and Cell Research (MSZ), Versbacher Strasse 5, Würzburg, Germany
- Institute for Clinical Neurobiology, University Hospital Würzburg, Versbacher Strasse 5, Würzburg, Germany
| | - Guadelupe Camarero
- University of Würzburg, Institute for Medical Radiation and Cell Research (MSZ), Versbacher Strasse 5, Würzburg, Germany
| | - Helmut Heinsen
- University of Würzburg, Department of Psychiatry, Psychosomatics and Psychotherapy, Margarethe-Höppel-Platz 1, Würzburg, Germany
- Universidade de Sao Paulo Faculdade de Medicina, Pathology—LIM 44 Sao Paulo, SP, Brazil
| | - Robert Blum
- Institute for Clinical Neurobiology, University Hospital Würzburg, Versbacher Strasse 5, Würzburg, Germany
| | - Ulf Rüdiger Rapp
- University of Würzburg, Institute for Medical Radiation and Cell Research (MSZ), Versbacher Strasse 5, Würzburg, Germany
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, Parkstr.1, Bad Nauheim, Germany
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12
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Papaioannou G, Petit ET, Liu ES, Baccarini M, Pritchard C, Demay MB. Raf Kinases Are Essential for Phosphate Induction of ERK1/2 Phosphorylation in Hypertrophic Chondrocytes and Normal Endochondral Bone Development. J Biol Chem 2017; 292:3164-3171. [PMID: 28073913 PMCID: PMC5336153 DOI: 10.1074/jbc.m116.763342] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/04/2017] [Indexed: 01/18/2023] Open
Abstract
Hypophosphatemia causes rickets by impairing hypertrophic chondrocyte apoptosis. Phosphate induction of MEK1/2-ERK1/2 phosphorylation in hypertrophic chondrocytes is required for phosphate-mediated apoptosis and growth plate maturation. MEK1/2 can be activated by numerous molecules including Raf isoforms. A- and B-Raf ablation in chondrocytes does not alter skeletal development, whereas ablation of C-Raf decreases hypertrophic chondrocyte apoptosis and impairs vascularization of the growth plate. However, ablation of C-Raf does not impair phosphate-induced ERK1/2 phosphorylation in vitro, but leads to rickets by decreasing VEGF protein stability. To determine whether Raf isoforms are required for phosphate-induced hypertrophic chondrocyte apoptosis, mice lacking all three Raf isoforms in chondrocytes were generated. Raf deletion caused neonatal death and a significant expansion of the hypertrophic chondrocyte layer of the growth plate, accompanied by decreased cleaved caspase-9. This was associated with decreased phospho-ERK1/2 immunoreactivity in the hypertrophic chondrocyte layer and impaired vascular invasion. These data further demonstrated that Raf kinases are required for phosphate-induced ERK1/2 phosphorylation in cultured hypertrophic chondrocytes and perform essential, but partially redundant roles in growth plate maturation.
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Affiliation(s)
- Garyfallia Papaioannou
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114; Harvard Medical School, Boston, Massachusetts 02115
| | - Elizabeth T Petit
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Eva S Liu
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114; Harvard Medical School, Boston, Massachusetts 02115; Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Manuela Baccarini
- Department of Microbiology, Immunobiology and Genetics, Center of Molecular Biology, Max F. Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, Vienna 1030, Austria
| | - Catrin Pritchard
- Department of Molecular and Cell Biology, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Marie B Demay
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114; Harvard Medical School, Boston, Massachusetts 02115.
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13
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Wicki A, Mandalà M, Massi D, Taverna D, Tang H, Hemmings BA, Xue G. Acquired Resistance to Clinical Cancer Therapy: A Twist in Physiological Signaling. Physiol Rev 2016; 96:805-29. [DOI: 10.1152/physrev.00024.2015] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Although modern therapeutic strategies have brought significant progress to cancer care in the last 30 years, drug resistance to targeted monotherapies has emerged as a major challenge. Aberrant regulation of multiple physiological signaling pathways indispensable for developmental and metabolic homeostasis, such as hyperactivation of pro-survival signaling axes, loss of suppressive regulations, and impaired functionalities of the immune system, have been extensively investigated aiming to understand the diversity of molecular mechanisms that underlie cancer development and progression. In this review, we intend to discuss the molecular mechanisms of how conventional physiological signal transduction confers to acquired drug resistance in cancer patients. We will particularly focus on protooncogenic receptor kinase inhibition-elicited tumor cell adaptation through two major core downstream signaling cascades, the PI3K/Akt and MAPK pathways. These pathways are crucial for cell growth and differentiation and are frequently hyperactivated during tumorigenesis. In addition, we also emphasize the emerging roles of the deregulated host immune system that may actively promote cancer progression and attenuate immunosurveillance in cancer therapies. Understanding these mechanisms may help to develop more effective therapeutic strategies that are able to keep the tumor in check and even possibly turn cancer into a chronic disease.
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Affiliation(s)
- Andreas Wicki
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland; Department of Oncology and Hematology, Papa Giovanni XXIII Hospital, Bergamo, Italy; Department of Surgery and Translational Medicine, University of Florence, Florence, Italy; Department of Molecular Biotechnology and Health Sciences, University of Turin, Torino, Italy; Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China; and Department of Mechanisms of Cancer, Friedrich Miescher Institute for
| | - Mario Mandalà
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland; Department of Oncology and Hematology, Papa Giovanni XXIII Hospital, Bergamo, Italy; Department of Surgery and Translational Medicine, University of Florence, Florence, Italy; Department of Molecular Biotechnology and Health Sciences, University of Turin, Torino, Italy; Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China; and Department of Mechanisms of Cancer, Friedrich Miescher Institute for
| | - Daniela Massi
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland; Department of Oncology and Hematology, Papa Giovanni XXIII Hospital, Bergamo, Italy; Department of Surgery and Translational Medicine, University of Florence, Florence, Italy; Department of Molecular Biotechnology and Health Sciences, University of Turin, Torino, Italy; Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China; and Department of Mechanisms of Cancer, Friedrich Miescher Institute for
| | - Daniela Taverna
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland; Department of Oncology and Hematology, Papa Giovanni XXIII Hospital, Bergamo, Italy; Department of Surgery and Translational Medicine, University of Florence, Florence, Italy; Department of Molecular Biotechnology and Health Sciences, University of Turin, Torino, Italy; Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China; and Department of Mechanisms of Cancer, Friedrich Miescher Institute for
| | - Huifang Tang
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland; Department of Oncology and Hematology, Papa Giovanni XXIII Hospital, Bergamo, Italy; Department of Surgery and Translational Medicine, University of Florence, Florence, Italy; Department of Molecular Biotechnology and Health Sciences, University of Turin, Torino, Italy; Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China; and Department of Mechanisms of Cancer, Friedrich Miescher Institute for
| | - Brian A. Hemmings
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland; Department of Oncology and Hematology, Papa Giovanni XXIII Hospital, Bergamo, Italy; Department of Surgery and Translational Medicine, University of Florence, Florence, Italy; Department of Molecular Biotechnology and Health Sciences, University of Turin, Torino, Italy; Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China; and Department of Mechanisms of Cancer, Friedrich Miescher Institute for
| | - Gongda Xue
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland; Department of Oncology and Hematology, Papa Giovanni XXIII Hospital, Bergamo, Italy; Department of Surgery and Translational Medicine, University of Florence, Florence, Italy; Department of Molecular Biotechnology and Health Sciences, University of Turin, Torino, Italy; Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China; and Department of Mechanisms of Cancer, Friedrich Miescher Institute for
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14
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Bondurand N, Southard-Smith EM. Mouse models of Hirschsprung disease and other developmental disorders of the enteric nervous system: Old and new players. Dev Biol 2016; 417:139-57. [PMID: 27370713 DOI: 10.1016/j.ydbio.2016.06.042] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/27/2016] [Accepted: 06/27/2016] [Indexed: 12/18/2022]
Abstract
Hirschsprung disease (HSCR, intestinal aganglionosis) is a multigenic disorder with variable penetrance and severity that has a general population incidence of 1/5000 live births. Studies using animal models have contributed to our understanding of the developmental origins of HSCR and the genetic complexity of this disease. This review summarizes recent progress in understanding control of enteric nervous system (ENS) development through analyses in mouse models. An overview of signaling pathways that have long been known to control the migration, proliferation and differentiation of enteric neural progenitors into and along the developing gut is provided as a framework for the latest information on factors that influence enteric ganglia formation and maintenance. Newly identified genes and additional factors beyond discrete genes that contribute to ENS pathology including regulatory sequences, miRNAs and environmental factors are also introduced. Finally, because HSCR has become a paradigm for complex oligogenic diseases with non-Mendelian inheritance, the importance of gene interactions, modifier genes, and initial studies on genetic background effects are outlined.
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Affiliation(s)
- Nadege Bondurand
- INSERM, U955, Equipe 6, F-94000 Creteil, France; Universite Paris-Est, UPEC, F-94000 Creteil, France.
| | - E Michelle Southard-Smith
- Vanderbilt University Medical Center, Department of Medicine, 2215 Garland Ave, Nashville, TN 37232, USA.
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15
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Abstract
RAF family kinases were among the first oncoproteins to be described more than 30 years ago. They primarily act as signalling relays downstream of RAS, and their close ties to cancer have fuelled a large number of studies. However, we still lack a systems-level understanding of their regulation and mode of action. The recent discovery that the catalytic activity of RAF depends on an allosteric mechanism driven by kinase domain dimerization is providing a vital new piece of information towards a comprehensive model of RAF function. The fact that current RAF inhibitors unexpectedly induce ERK signalling by stimulating RAF dimerization also calls for a deeper structural characterization of this family of kinases.
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16
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Hernández-Porras I, Jiménez-Catalán B, Schuhmacher AJ, Guerra C. The impact of the genetic background in the Noonan syndrome phenotype induced by K-Ras(V14I). Rare Dis 2015; 3:e1045169. [PMID: 26458870 PMCID: PMC4590006 DOI: 10.1080/21675511.2015.1045169] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/02/2015] [Accepted: 04/21/2015] [Indexed: 12/12/2022] Open
Abstract
Noonan syndrome (NS) is an autosomal dominant genetic disorder characterized by short stature, craniofacial dysmorphism, and congenital heart defects. A significant fraction of NS-patients also develop myeloproliferative disorders. The penetrance of these defects varies considerably among patients. In this study, we have examined the effect of 2 genetic backgrounds (C57BL/6J.OlaHsd and 129S2/SvPasCrl) on the phenotypes displayed by a mouse model of NS induced by germline expression of the mutated K-RasV14I allele, one of the most frequent NS-KRAS mutations. Our results suggest the presence of genetic modifiers associated to the genetic background that are essential for heart development and function at early stages of postnatal life as well as in the severity of the haematopoietic alterations.
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Affiliation(s)
| | | | - Alberto J Schuhmacher
- Molecular Oncology; Centro Nacional de Investigaciones Oncológicas (CNIO) ; Madrid, Spain
| | - Carmen Guerra
- Molecular Oncology; Centro Nacional de Investigaciones Oncológicas (CNIO) ; Madrid, Spain
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17
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de Iriarte Rodríguez R, Magariños M, Pfeiffer V, Rapp UR, Varela-Nieto I. C-Raf deficiency leads to hearing loss and increased noise susceptibility. Cell Mol Life Sci 2015; 72:3983-98. [PMID: 25975225 PMCID: PMC4575698 DOI: 10.1007/s00018-015-1919-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 04/21/2015] [Accepted: 04/27/2015] [Indexed: 12/20/2022]
Abstract
The family of RAF kinases transduces extracellular information to the nucleus, and their activation is crucial for cellular regulation on many levels, ranging from embryonic development to carcinogenesis. B-RAF and C-RAF modulate neurogenesis and neuritogenesis during chicken inner ear development. C-RAF deficiency in humans is associated with deafness in the rare genetic insulin-like growth factor 1 (IGF-1), Noonan and Leopard syndromes. In this study, we show that RAF kinases are expressed in the developing inner ear and in adult mouse cochlea. A homozygous C-Raf deletion in mice caused profound deafness with no evident cellular aberrations except for a remarkable reduction of the K+ channel Kir4.1 expression, a trait that suffices as a cause of deafness. To explore the role of C-Raf in cellular protection and repair, heterozygous C-Raf+/− mice were exposed to noise. A reduced C-RAF level negatively affected hearing preservation in response to noise through mechanisms involving the activation of JNK and an exacerbated apoptotic response. Taken together, these results strongly support a role for C-RAF in hearing protection.
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Affiliation(s)
- Rocío de Iriarte Rodríguez
- Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Arturo Duperier 4, 28029, Madrid, Spain.,Centre for Biomedical Network Research (CIBERER), Institute of Health Carlos III (ISCIII), Madrid, Spain
| | - Marta Magariños
- Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Arturo Duperier 4, 28029, Madrid, Spain. .,Centre for Biomedical Network Research (CIBERER), Institute of Health Carlos III (ISCIII), Madrid, Spain. .,Departamento de Biología, Universidad Autónoma de Madrid, Darwin 2, 28049, Madrid, Spain.
| | - Verena Pfeiffer
- Institute for Medical Radiation and Cell Research (MSZ), University of Würzburg, Versbacher Strasse 5, 97078, Würzburg, Germany.,Institute for Anatomy and Cell Biology, University of Würzburg, Koellikerstraße 6, 97070, Würzburg, Germany
| | - Ulf R Rapp
- Institute for Medical Radiation and Cell Research (MSZ), University of Würzburg, Versbacher Strasse 5, 97078, Würzburg, Germany.,Molecular Mechanisms of Lung Cancer, Max Planck Institute for Heart and Lung Research, Parkstr. 1, 61231, Bad Nauheim, Germany
| | - Isabel Varela-Nieto
- Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Arturo Duperier 4, 28029, Madrid, Spain.,Centre for Biomedical Network Research (CIBERER), Institute of Health Carlos III (ISCIII), Madrid, Spain.,Hospital La Paz Institute for Health Research (IdiPAZ), Madrid, Spain
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18
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Mooz J, Oberoi-Khanuja TK, Harms GS, Wang W, Jaiswal BS, Seshagiri S, Tikkanen R, Rajalingam K. Dimerization of the kinase ARAF promotes MAPK pathway activation and cell migration. Sci Signal 2014; 7:ra73. [PMID: 25097033 DOI: 10.1126/scisignal.2005484] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The RAF family of kinases mediates RAS signaling, and RAF inhibitors can be effective for treating tumors with BRAF(V600E) mutant protein. However, RAF inhibitors paradoxically accelerate metastasis in RAS-mutant tumors and become ineffective in BRAF(V600E) tumors because of reactivation of downstream mitogen-activated protein kinase (MAPK) signaling. We found that the RAF isoform ARAF has an obligatory role in promoting MAPK activity and cell migration in a cell type-dependent manner. Knocking down ARAF prevented the activation of MAPK kinase 1 (MEK1) and extracellular signal-regulated kinase 1 and 2 (ERK1/2) and decreased the number of protrusions from tumor cell spheroids in three-dimensional culture that were induced by BRAF(V600E)-specific or BRAF/CRAF inhibitors (GDC-0879 and sorafenib, respectively). RAF inhibitors induced the homodimerization of ARAF and the heterodimerization of BRAF with CRAF and the scaffolding protein KSR1. In a purified protein solution, recombinant proteins of the three RAF isoforms competed for binding to MEK1. In cells in culture, overexpressing mutants of ARAF that could not homodimerize impaired the interaction between ARAF and endogenous MEK1 and thus prevented the subsequent activation of MEK1 and ERK1/2. Our findings reveal a new role for ARAF in directly activating the MAPK cascade and promoting tumor cell invasion and suggest a new therapeutic target for RAS- and RAF-mediated cancers.
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Affiliation(s)
- Juliane Mooz
- Cell death signalling group, Institute of Biochemistry II, Goethe University Medical School, Frankfurt 60590, Germany. Institute for Immunology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, Building 708, Mainz 55131, Germany
| | - Tripat Kaur Oberoi-Khanuja
- Cell death signalling group, Institute of Biochemistry II, Goethe University Medical School, Frankfurt 60590, Germany
| | - Gregory S Harms
- Stark Learning Center, Department of Biology and Health Sciences, Wilkes University, Wilkes-Barre, Pennsylvania, PA 18766, USA
| | - Weiru Wang
- Department of Protein Engineering, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Bijay S Jaiswal
- Department of Molecular Biology, Genentech Inc., South San Francisco, CA 94080, USA
| | - Somasekar Seshagiri
- Department of Molecular Biology, Genentech Inc., South San Francisco, CA 94080, USA
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Giessen 35392, Germany
| | - Krishnaraj Rajalingam
- Cell death signalling group, Institute of Biochemistry II, Goethe University Medical School, Frankfurt 60590, Germany. Institute for Immunology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, Building 708, Mainz 55131, Germany.
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19
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"RAF" neighborhood: protein-protein interaction in the Raf/Mek/Erk pathway. FEBS Lett 2014; 588:2398-406. [PMID: 24937142 PMCID: PMC4099524 DOI: 10.1016/j.febslet.2014.06.025] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/05/2014] [Accepted: 06/06/2014] [Indexed: 12/19/2022]
Abstract
The Raf/Mek/Erk signaling pathway, activated downstream of Ras primarily to promote proliferation, represents the best studied of the evolutionary conserved MAPK cascades. The investigation of the pathway has continued unabated since its discovery roughly 30 years ago. In the last decade, however, the identification of unexpected in vivo functions of pathway components, as well as the discovery of Raf mutations in human cancer, the ensuing quest for inhibitors, and the efforts to understand their mechanism of action, have boosted interest tremendously. From this large body of work, protein-protein interaction has emerged as a recurrent, crucial theme. This review focuses on the role of protein complexes in the regulation of the Raf/Mek/Erk pathway and in its cross-talk with other signaling cascades. Mapping these interactions and finding a way of exploiting them for therapeutic purposes is one of the challenges of future molecule-targeted therapy.
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20
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Watanabe-Takano H, Takano K, Sakamoto A, Matsumoto K, Tokuhisa T, Endo T, Hatano M. DA-Raf-dependent inhibition of the Ras-ERK signaling pathway in type 2 alveolar epithelial cells controls alveolar formation. Proc Natl Acad Sci U S A 2014; 111:E2291-300. [PMID: 24843139 PMCID: PMC4050578 DOI: 10.1073/pnas.1321574111] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Alveolar formation is coupled to the spatiotemporally regulated differentiation of alveolar myofibroblasts (AMYFs), which contribute to the morphological changes of interalveolar walls. Although the Ras-ERK signaling pathway is one of the key regulators for alveolar formation in developing lungs, the intrinsic molecular and cellular mechanisms underlying its role remain largely unknown. By analyzing the Ras-ERK signaling pathway during postnatal development of lungs, we have identified a critical role of DA-Raf1 (DA-Raf)-a dominant-negative antagonist for the Ras-ERK signaling pathway-in alveolar formation. DA-Raf-deficient mice displayed alveolar dysgenesis as a result of the blockade of AMYF differentiation. DA-Raf is predominantly expressed in type 2 alveolar epithelial cells (AEC2s) in developing lungs, and DA-Raf-dependent MEK1/2 inhibition in AEC2s suppresses expression of tissue inhibitor of matalloprotienase 4 (TIMP4), which prevents a subsequent proteolytic cascade matrix metalloproteinase (MMP)14-MMP2. Furthermore, MMP14-MMP2 proteolytic cascade regulates AMYF differentiation and alveolar formation. Therefore, DA-Raf-dependent inhibition of the Ras-ERK signaling pathway in AEC2s is required for alveolar formation via triggering MMP2 activation followed by AMYF differentiation. These findings reveal a pivotal role of the Ras-ERK signaling pathway in the dynamic regulation of alveolar development.
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Affiliation(s)
- Haruko Watanabe-Takano
- Departments of Biomedical Science andDepartment of Biology, Graduate School of Science andJapan Society for the Promotion of Science, Chiyoda-ku, Tokyo 102-0083, Japan; and
| | - Kazunori Takano
- Department of Biology, Graduate School of Science andGraduate School of Advanced Integration Science, Chiba University, Yayoicho, Inage-ku, Chiba 263-8522, Japan
| | - Akemi Sakamoto
- Developmental Genetics, Graduate School of Medicine, Chiba University, Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Kenji Matsumoto
- Department of Allergy and Immunology, National Research Institute for Child Health and Development, Setagaya-ku, Tokyo 157-8535, Japan
| | - Takeshi Tokuhisa
- Developmental Genetics, Graduate School of Medicine, Chiba University, Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Takeshi Endo
- Department of Biology, Graduate School of Science andGraduate School of Advanced Integration Science, Chiba University, Yayoicho, Inage-ku, Chiba 263-8522, Japan;
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21
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Increased BRAF heterodimerization is the common pathogenic mechanism for noonan syndrome-associated RAF1 mutants. Mol Cell Biol 2012; 32:3872-90. [PMID: 22826437 DOI: 10.1128/mcb.00751-12] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Noonan syndrome (NS) is a relatively common autosomal dominant disorder characterized by congenital heart defects, short stature, and facial dysmorphia. NS is caused by germ line mutations in several components of the RAS-RAF-MEK-extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway, including both kinase-activating and kinase-impaired alleles of RAF1 (∼3 to 5%), which encodes a serine-threonine kinase for MEK1/2. To investigate how kinase-impaired RAF1 mutants cause NS, we generated knock-in mice expressing Raf1(D486N). Raf1(D486N/+) (here D486N/+) female mice exhibited a mild growth defect. Male and female D486N/D486N mice developed concentric cardiac hypertrophy and incompletely penetrant, but severe, growth defects. Remarkably, Mek/Erk activation was enhanced in Raf1(D486N)-expressing cells compared with controls. RAF1(D486N), as well as other kinase-impaired RAF1 mutants, showed increased heterodimerization with BRAF, which was necessary and sufficient to promote increased MEK/ERK activation. Furthermore, kinase-activating RAF1 mutants also required heterodimerization to enhance MEK/ERK activation. Our results suggest that an increased heterodimerization ability is the common pathogenic mechanism for NS-associated RAF1 mutations.
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22
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Selvy PE, Lavieri RR, Lindsley CW, Brown HA. Phospholipase D: enzymology, functionality, and chemical modulation. Chem Rev 2011; 111:6064-119. [PMID: 21936578 PMCID: PMC3233269 DOI: 10.1021/cr200296t] [Citation(s) in RCA: 269] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Paige E Selvy
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37064, USA
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23
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Opioid Receptor Trafficking and Signaling: What Happens After Opioid Receptor Activation? Cell Mol Neurobiol 2011; 32:167-84. [DOI: 10.1007/s10571-011-9755-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 09/04/2011] [Indexed: 01/14/2023]
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24
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Chung E, Kondo M. Role of Ras/Raf/MEK/ERK signaling in physiological hematopoiesis and leukemia development. Immunol Res 2011; 49:248-68. [PMID: 21170740 DOI: 10.1007/s12026-010-8187-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recent research on hematological malignancies has shown that malignant cells often co-opt physiological pathways to promote their growth and development. Bone marrow homeostasis requires a fine balance between cellular differentiation and self-renewal; cell survival and apoptosis; and cellular proliferation and senescence. The Ras/Raf/MEK/ERK pathway has been shown to be important in regulating these biological functions. Moreover, the Ras/Raf/MEK/ERK pathway has been estimated to be mutated in 30% of all cancers, thus making it the focus of many scientific studies which have lead to a deeper understanding of cancer development and help to elucidate potential weaknesses that can be targeted by pharmacological agents [1]. In this review, we specifically focus on the role of this pathway in physiological hematopoiesis and how augmentation of the pathway may lead to hematopoietic malignancies. We also discuss the challenges and success of targeting this pathway.
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Affiliation(s)
- Eva Chung
- Department of Immunology, Duke University Medical Center, 101 Jones Building, DUMC Box 3010, Research Drive, Durham, NC 27710, USA
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25
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Matallanas D, Birtwistle M, Romano D, Zebisch A, Rauch J, von Kriegsheim A, Kolch W. Raf family kinases: old dogs have learned new tricks. Genes Cancer 2011; 2:232-60. [PMID: 21779496 PMCID: PMC3128629 DOI: 10.1177/1947601911407323] [Citation(s) in RCA: 272] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
First identified in the early 1980s as retroviral oncogenes, the Raf proteins have been the objects of intense research. The discoveries 10 years later that the Raf family members (Raf-1, B-Raf, and A-Raf) are bona fide Ras effectors and upstream activators of the ubiquitous ERK pathway increased the interest in these proteins primarily because of the central role that this cascade plays in cancer development. The important role of Raf in cancer was corroborated in 2002 with the discovery of B-Raf genetic mutations in a large number of tumors. This led to intensified drug development efforts to target Raf signaling in cancer. This work yielded not only recent clinical successes but also surprising insights into the regulation of Raf proteins by homodimerization and heterodimerization. Surprising insights also came from the hunt for new Raf targets. Although MEK remains the only widely accepted Raf substrate, new kinase-independent roles for Raf proteins have emerged. These include the regulation of apoptosis by suppressing the activity of the proapoptotic kinases, ASK1 and MST2, and the regulation of cell motility and differentiation by controlling the activity of Rok-α. In this review, we discuss the regulation of Raf proteins and their role in cancer, with special focus on the interacting proteins that modulate Raf signaling. We also describe the new pathways controlled by Raf proteins and summarize the successes and failures in the development of efficient anticancer therapies targeting Raf. Finally, we also argue for the necessity of more systemic approaches to obtain a better understanding of how the Ras-Raf signaling network generates biological specificity.
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Affiliation(s)
- David Matallanas
- Systems Biology Ireland, University College Dublin, Dublin, Ireland
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26
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Calcineurin increases glucose activation of ERK1/2 by reversing negative feedback. Proc Natl Acad Sci U S A 2010; 107:22314-9. [PMID: 21135229 DOI: 10.1073/pnas.1016630108] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In pancreatic β cells, ERK1 and ERK2 participate in nutrient sensing, and their activities rise and fall as a function of glucose concentration over the physiologic range. Glucose metabolism triggers calcium influx and release of calcium from intracellular stores to activate ERK1/2. Calcium influx also activates the calcium-dependent phosphatase calcineurin, which is required for maximal ERK1/2 activation by glucose. Calcineurin controls insulin gene expression by ERK1/2-dependent and -independent mechanisms. Here, we show that, in β cells, glucose activates the ERK1/2 cascade primarily through B-Raf. Glucose activation of B-Raf, like that of ERK1/2, is calcineurin-sensitive. Calcineurin binds to B-Raf in both unstimulated and stimulated cells. We show that B-Raf is a calcineurin substrate; among calcineurin target residues on B-Raf is T401, a site of negative feedback phosphorylation by ERK1/2. Blocking calcineurin activity in β cells prevents dephosphorylation of B-Raf T401 and decreases B-Raf and ERK1/2 activities. We conclude that the major calcineurin-dependent event in glucose sensing by ERK1/2 is the activation of B-Raf.
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27
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Tartaglia M, Gelb BD. Disorders of dysregulated signal traffic through the RAS-MAPK pathway: phenotypic spectrum and molecular mechanisms. Ann N Y Acad Sci 2010; 1214:99-121. [PMID: 20958325 PMCID: PMC3010252 DOI: 10.1111/j.1749-6632.2010.05790.x] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
RAS GTPases control a major signaling network implicated in several cellular functions, including cell fate determination, proliferation, survival, differentiation, migration, and senescence. Within this network, signal flow through the RAF-MEK-ERK pathway-the first identified mitogen-associated protein kinase (MAPK) cascade-mediates early and late developmental processes controlling morphology determination, organogenesis, synaptic plasticity, and growth. Signaling through the RAS-MAPK cascade is tightly controlled; and its enhanced activation represents a well-known event in oncogenesis. Unexpectedly, in the past few years, inherited dysregulation of this pathway has been recognized as the cause underlying a group of clinically related disorders sharing facial dysmorphism, cardiac defects, reduced postnatal growth, ectodermal anomalies, variable cognitive deficits, and susceptibility to certain malignancies as major features. These disorders are caused by heterozygosity for mutations in genes encoding RAS proteins, regulators of RAS function, modulators of RAS interaction with effectors, or downstream signal transducers. Here, we provide an overview of the phenotypic spectrum associated with germline mutations perturbing RAS-MAPK signaling, the unpredicted molecular mechanisms converging toward the dysregulation of this signaling cascade, and major genotype-phenotype correlations.
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Affiliation(s)
- Marco Tartaglia
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy.
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28
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Carnahan J, Beltran PJ, Babij C, Le Q, Rose MJ, Vonderfecht S, Kim JL, Smith AL, Nagapudi K, Broome MA, Fernando M, Kha H, Belmontes B, Radinsky R, Kendall R, Burgess TL. Selective and potent Raf inhibitors paradoxically stimulate normal cell proliferation and tumor growth. Mol Cancer Ther 2010; 9:2399-410. [PMID: 20663930 DOI: 10.1158/1535-7163.mct-10-0181] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Raf inhibitors are under clinical investigation, specifically in patients with tumor types harboring frequent activating mutations in B-Raf. Here, we show that cell lines and tumors harboring mutant B-Raf were sensitive to a novel series of Raf inhibitors (e.g., (V600E)B-Raf A375, IC(50) on cells = 2 nmol/L; ED(50) on tumor xenografts = 1.3 mg/kg). However, in cells and tumors with wild-type B-Raf, exposure to Raf inhibitors resulted in a dose-dependent and sustained activation of mitogen-activated protein kinase signaling. In some of these cell lines, Raf inhibition led to entry into the cell cycle, enhanced proliferation, and significantly stimulated tumor growth in vivo. Inhibition with structurally distinct Raf inhibitors or isoform-specific small interfering RNA knockdown of Raf showed that these effects were mediated directly through Raf. Either A-Raf or C-Raf mediated the Raf inhibitor-induced mitogen-activated protein kinase pathway activation in an inhibitor-specific manner. These paradoxical effects of Raf inhibition were seen in malignant and normal cells in vitro and in vivo. Hyperplasia of normal epithelial cells in the esophagus and the stomach was evident in mice with all efficacious Raf inhibitors (n = 8) tested. An implication of these results is that Raf inhibitors may induce unexpected normal cell and tumor tissue proliferation in patients.
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Affiliation(s)
- Josette Carnahan
- Department of Hematology, Amgen, Inc., One Amgen Center Drive, Thousand Oaks, CA 91320, USA.
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29
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Rho O, Kim DJ, Kiguchi K, Digiovanni J. Growth factor signaling pathways as targets for prevention of epithelial carcinogenesis. Mol Carcinog 2010; 50:264-79. [PMID: 20648549 DOI: 10.1002/mc.20665] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 06/09/2010] [Accepted: 06/10/2010] [Indexed: 10/24/2022]
Abstract
Growth factor receptor (GFR) signaling controls epithelial cell growth by responding to various endogenous or exogenous stimuli and subsequently activating downstream signaling pathways including Stat3, PI3K/Akt/mTOR, MAPK, and c-Src. Environmental chemical toxicants and UVB irradiation cause enhanced and prolonged activation of GFR signaling and downstream pathways that contributes to epithelial cancer development including skin cancer. Recent studies, especially those with tissue-specific transgenic mouse models, have demonstrated that GFRs and their downstream signaling pathways contribute to all three stages of epithelial carcinogenesis by regulating a wide variety of biological functions including proliferation, apoptosis, angiogenesis, cell adhesion, and migration. Inhibiting these signaling pathways early in the carcinogenic process results in reduced cell proliferation and survival, leading to decreased tumor formation. Collectively, these studies suggest that GFR signaling and subsequent downstream signaling pathways are potential targets for the prevention of epithelial cancers including skin cancer.
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Affiliation(s)
- Okkyung Rho
- Division of Pharmacology & Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78723-3092, USA
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30
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Hoogwater FJH, Nijkamp MW, Smakman N, Steller EJA, Emmink BL, Westendorp BF, Raats DAE, Sprick MR, Schaefer U, Van Houdt WJ, De Bruijn MT, Schackmann RCJ, Derksen PWB, Medema JP, Walczak H, Borel Rinkes IHM, Kranenburg O. Oncogenic K-Ras turns death receptors into metastasis-promoting receptors in human and mouse colorectal cancer cells. Gastroenterology 2010; 138:2357-67. [PMID: 20188103 DOI: 10.1053/j.gastro.2010.02.046] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 02/04/2010] [Accepted: 02/17/2010] [Indexed: 01/27/2023]
Abstract
BACKGROUND & AIMS Death receptors expressed on tumor cells can prevent metastasis formation by inducing apoptosis, but they also can promote migration and invasion. The determinants of death receptor signaling output are poorly defined. Here we investigated the role of oncogenic K-Ras in determining death receptor function and metastatic potential. METHODS Isogenic human and mouse colorectal cancer cell lines differing only in the presence or absence of the K-Ras oncogene were tested in apoptosis and invasion assays using CD95 ligand and tumor necrois factor-related apoptosis-inducing ligand (TRAIL) as stimuli. Metastatic potential was assessed by intrasplenic injections of green fluorescent protein- or luciferase-expressing tumor cells, followed by intravital fluorescence microscopy or bioluminescence imaging, and confocal microscopy and immunohistochemistry. Ras-effector pathway control of CD95 output was assessed by an RNA-interference and inhibitor-based approach. RESULTS CD95 ligand and TRAIL stimulated invasion of colorectal tumor cells and liver metastases in a K-Ras-dependent fashion. Loss of mutant K-Ras switched CD95 and TRAIL receptors back into apoptosis mode and abrogated metastatic potential. Raf1 was essential for the switch in CD95 function, for tumor cell survival in the liver, and for K-Ras-driven formation of liver metastases. K-Ras and Raf1 suppressed Rho kinase (ROCK)/LIM kinase-mediated phosphorylation of the actin-severing protein cofilin. Overexpression of ROCK or LIM kinase allowed CD95L to induce apoptosis in K-Ras-proficient cells and prevented metastasis formation, whereas their suppression protected K-Ras-deficient cells against apoptosis. CONCLUSIONS Oncogenic K-Ras and its effector Raf1 convert death receptors into invasion-inducing receptors by suppressing the ROCK/LIM kinase pathway, and this is essential for K-Ras/Raf1-driven metastasis formation.
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31
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Fendler JP, Malavaud B, Gimel P, Duclos B, Chevreau C, Pignot G. [Renal cell carcinoma: antiangiogenic therapies and management of the complications. A case report]. Prog Urol 2010; 20 Suppl 1:S27-32. [PMID: 20493440 DOI: 10.1016/s1166-7087(10)70022-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Direct side effects of the inhibition of activation of VEGF receptors are well known and could be easily explained (HTA). The indirect toxicity of the inhibitors of tyrosinekinases is much less known and several hypotheses appear. Usually, the common side effects of the inhibitors of tyrosine-kinases can be easily managed and are reversible when the treatment is stopped. Their management is essentially based on prevention measures. It is necessary to stop definitively or temporarily the treatment in case of intensification of pre-existing comorbidities or side effects of rank 3 or 4. There is no predictive factor of treatment toxicity and, at the moment, there is thus no indication in a previous dose adaptation.
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Affiliation(s)
- J-P Fendler
- Service d'Urologie, Centre Hospitalier Saint-Joseph/Saint-Luc, quai Claude-Bernard, Lyon cedex 7, France
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32
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Genetic analysis of Ras signalling pathways in cell proliferation, migration and survival. EMBO J 2010; 29:1091-104. [PMID: 20150892 DOI: 10.1038/emboj.2010.7] [Citation(s) in RCA: 245] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 01/18/2010] [Indexed: 02/08/2023] Open
Abstract
We have used mouse embryonic fibroblasts (MEFs) devoid of Ras proteins to illustrate that they are essential for proliferation and migration, but not for survival, at least in these cells. These properties are unique to the Ras subfamily of proteins because ectopic expression of other Ras-like small GTPases, even when constitutively active, could not compensate for the absence of Ras proteins. Only constitutive activation of components of the Raf/Mek/Erk pathway was sufficient to sustain normal proliferation and migration of MEFs devoid of Ras proteins. Activation of the phosphatidylinositol 3-kinase (PI3K)/PTEN/Akt and Ral guanine exchange factor (RalGEF)/Ral pathways, either alone or in combination, failed to induce proliferation or migration of Rasless cells, although they cooperated with Raf/Mek/Erk signalling to reproduce the full response mediated by Ras signalling. In contrast to current hypotheses, Ras signalling did not induce proliferation by inducing expression of D-type Cyclins. Rasless MEFs had normal levels of Cyclin D1/Cdk4 and Cyclin E/Cdk2. However, these complexes were inactive. Inactivation of the pocket proteins or knock down of pRb relieved MEFs from their dependence on Ras signalling to proliferate.
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33
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Rauch J, O'Neill E, Mack B, Matthias C, Munz M, Kolch W, Gires O. Heterogeneous nuclear ribonucleoprotein H blocks MST2-mediated apoptosis in cancer cells by regulating A-Raf transcription. Cancer Res 2010; 70:1679-88. [PMID: 20145135 DOI: 10.1158/0008-5472.can-09-2740] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A-Raf belongs to the family of oncogenic Raf kinases that are involved in mitogenic signaling by activating the mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK pathway. Low kinase activity of A-Raf toward MEK suggested that A-Raf might have alternative functions. Here, we show that A-Raf prevents cancer cell apoptosis contingent on the expression of the heterogeneous nuclear ribonucleoprotein H (hnRNP H) splice factor, which is required for the correct transcription and expression of a-raf. Apoptosis was prevented by A-Raf through sequestration and inactivation of the proapoptotic MST2 kinase. Small interfering RNA-mediated knockdown of hnRNP H or A-Raf resulted in MST2-dependent apoptosis. In contrast, enforced expression of either hnRNP H or A-Raf partially counteracted apoptosis induced by etoposide. In vivo expression studies of colon specimens corroborated the overexpression of hnRNP H in malignant tissues and its correlation with A-Raf levels. Our findings define a novel mechanism that is usurped in tumor cells to escape naturally imposed apoptotic signals.
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Affiliation(s)
- Jens Rauch
- Department of Head and Neck Research, Ludwig-Maximilians-Universität München, D-81377 Munich, Germany
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34
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Tartaglia M, Zampino G, Gelb BD. Noonan syndrome: clinical aspects and molecular pathogenesis. Mol Syndromol 2010; 1:2-26. [PMID: 20648242 DOI: 10.1159/000276766] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 10/30/2009] [Indexed: 01/20/2023] Open
Abstract
Noonan syndrome (NS) is a relatively common, clinically variable and genetically heterogeneous developmental disorder characterized by postnatally reduced growth, distinctive facial dysmorphism, cardiac defects and variable cognitive deficits. Other associated features include ectodermal and skeletal defects, cryptorchidism, lymphatic dysplasias, bleeding tendency, and, rarely, predisposition to hematologic malignancies during childhood. NS is caused by mutations in the PTPN11, SOS1, KRAS, RAF1, BRAF and MEK1 (MAP2K1) genes, accounting for approximately 70% of affected individuals. SHP2 (encoded by PTPN11), SOS1, BRAF, RAF1 and MEK1 positively contribute to RAS-MAPK signaling, and possess complex autoinhibitory mechanisms that are impaired by mutations. Similarly, reduced GTPase activity or increased guanine nucleotide release underlie the aberrant signal flow through the MAPK cascade promoted by most KRAS mutations. More recently, a single missense mutation in SHOC2, which encodes a cytoplasmic scaffold positively controlling RAF1 activation, has been discovered to cause a closely related phenotype previously termed Noonan-like syndrome with loose anagen hair. This mutation promotes aberrantly acquired N-myristoylation of the protein, resulting in its constitutive targeting to the plasma membrane and dysregulated function. PTPN11, BRAF and RAF1 mutations also account for approximately 95% of LEOPARD syndrome, a condition which resembles NS phenotypically but is characterized by multiple lentigines dispersed throughout the body, café-au-lait spots, and a higher prevalence of electrocardiographic conduction abnormalities, obstructive cardiomyopathy and sensorineural hearing deficits. These recent discoveries demonstrate that the substantial phenotypic variation characterizing NS and related conditions can be ascribed, in part, to the gene mutated and even the specific molecular lesion involved.
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Affiliation(s)
- M Tartaglia
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy
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35
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Can BAD pores be good? New insights from examining BAD as a target of RAF kinases. ACTA ACUST UNITED AC 2009; 50:147-59. [PMID: 19895838 DOI: 10.1016/j.advenzreg.2009.10.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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36
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Bloethner S, Scherer D, Drechsel M, Hemminki K, Kumar R. Malignant Melanoma–a Genetic Overview. ACTAS DERMO-SIFILIOGRAFICAS 2009. [DOI: 10.1016/s0001-7310(09)73167-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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37
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Robinson JP, VanBrocklin MW, Guilbeault AR, Signorelli DL, Brandner S, Holmen SL. Activated BRAF induces gliomas in mice when combined with Ink4a/Arf loss or Akt activation. Oncogene 2009; 29:335-44. [PMID: 19855433 DOI: 10.1038/onc.2009.333] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mutations in receptor tyrosine kinase (RTK) growth factor receptors (epidermal growth factor receptor, platelet-derived growth factor receptor, MET and ERBB2), which result in downstream activation of the RAS/RAF/MEK/ERK mitogen-activated protein kinase (MAPK) pathway and PI(3)K/Akt pathway, are found in almost all high-grade gliomas and MAPK signaling is necessary for continued glioma maintenance. In addition, BRAF is mutated in the majority of low-grade gliomas and its expression and activity is significantly increased in the majority of high-grade gliomas. Although the importance of RTKs and RAS signaling in glioma development has been shown, the role of BRAF has yet to be characterized. We evaluated the effect of activated BRAF in glioma formation using the retroviral replication-competent avian leukosis virus long terminal repeat, splice acceptor (RCAS)/TVA system to transfer genes encoding activated forms of BRAF, KRas, Akt and Cre to nestin-expressing neural progenitor cells in Ink4a/Arf(lox/lox) mice in vivo. Although expression of activated BRAF alone is not sufficient for tumorigenesis, the combination of activated BRAF and Akt or BRAF with Ink4a/Arf loss is transforming. Interestingly, activated BRAF generates gliomas with characteristics similar to activated KRas in the context of Akt but not Ink4a/Arf loss. Our studies show a role for BRAF activation and signaling in glioma development and as potential target for glioma therapy.
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Affiliation(s)
- J P Robinson
- Drug Development Department, Nevada Cancer Institute, Las Vegas, NV 89135, USA
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Liu L, Channavajhala PL, Rao VR, Moutsatsos I, Wu L, Zhang Y, Lin LL, Qiu Y. Proteomic characterization of the dynamic KSR-2 interactome, a signaling scaffold complex in MAPK pathway. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1485-95. [PMID: 19563921 DOI: 10.1016/j.bbapap.2009.06.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Revised: 06/11/2009] [Accepted: 06/12/2009] [Indexed: 12/01/2022]
Abstract
KSR-1 is a scaffold protein that is essential for Ras-induced activation of the highly conserved RAF-MEK-ERK kinase module. Previously, we identified a close homolog of KSR-1, called KSR-2, through structural homology-based data mining. In order to further understand the role of KSR-2 in MAPK signaling, we undertook a functional proteomics approach to elucidate the dynamic composition of the KSR-2 functional complex in HEK-293 cells under conditions with and without TNF-alpha stimulation. We found nearly 100 proteins that were potentially associated with KSR-2 complex and 43 proteins that were likely recruited to the super molecular complex after TNF-alpha treatment. Our results indicate that KSR-2 may act as a scaffold protein similar as KSR-1 to mediate the MAPK core (RAF-MEK-ERK) signaling but with a distinct RAF isoform specificity, namely KSR-2 may only mediate the A-RAF signaling while KSR-1 is responsible for transducing signals only from c-RAF. In addition, KSR-2 may be involved in the activation of many MAPK downstream signaling molecules such as p38 MAPK, IKAP, AIF, and proteins involved in ubiquitin-proteasome, apoptosis, cell cycle control, and DNA synthesis and repair pathways, as well as mediating crosstalks between MAPK and several other signaling pathways, including PI3K and insulin signaling. While interactions with these molecules are not known for KSR-1, it's reasonable to hypothesize that KSR-1 may also play a similar role in mediating these downstream signaling pathways.
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Affiliation(s)
- Lin Liu
- Department of Biological Technologies, Wyeth, Cambridge, MA 02140, USA
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39
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Nekhoroshkova E, Albert S, Becker M, Rapp UR. A-RAF kinase functions in ARF6 regulated endocytic membrane traffic. PLoS One 2009; 4:e4647. [PMID: 19247477 PMCID: PMC2645234 DOI: 10.1371/journal.pone.0004647] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 01/13/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND RAF kinases direct ERK MAPK signaling to distinct subcellular compartments in response to growth factor stimulation. METHODOLOGY/PRINCIPAL FINDINGS Of the three mammalian isoforms A-RAF is special in that one of its two lipid binding domains mediates a unique pattern of membrane localization. Specific membrane binding is retained by an N-terminal fragment (AR149) that corresponds to a naturally occurring splice variant termed DA-RAF2. AR149 colocalizes with ARF6 on tubular endosomes and has a dominant negative effect on endocytic trafficking. Moreover actin polymerization of yeast and mammalian cells is abolished. AR149/DA-RAF2 does not affect the internalization step of endocytosis, but trafficking to the recycling compartment. CONCLUSIONS/SIGNIFICANCE A-RAF induced ERK activation is required for this step by activating ARF6, as A-RAF depletion or inhibition of the A-RAF controlled MEK-ERK cascade blocks recycling. These data led to a new model for A-RAF function in endocytic trafficking.
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Affiliation(s)
- Elena Nekhoroshkova
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), University of Würzburg, Würzburg, Germany
| | - Stefan Albert
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), University of Würzburg, Würzburg, Germany
| | - Matthias Becker
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), University of Würzburg, Würzburg, Germany
| | - Ulf R. Rapp
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), University of Würzburg, Würzburg, Germany
- * E-mail:
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40
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Craig EA, Stevens MV, Vaillancourt RR, Camenisch TD. MAP3Ks as central regulators of cell fate during development. Dev Dyn 2009; 237:3102-14. [PMID: 18855897 DOI: 10.1002/dvdy.21750] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The cytoplasmic serine/threonine kinases transduce extracellular signals into regulatory events that impact cellular responses. The induction of one kinase triggers the activation of several downstream kinases, leading to the regulation of transcription factors to affect gene function. This arrangement allows for the kinase cascade to be amplified, and integrated according to the cellular context. An upstream mitogen or growth factor signal initiates a module of three kinases: a mitogen-activated protein (MAP) kinase kinase kinase (MAPKKK; e.g., Raf) that phosphorylates and activates a MAP kinase kinase (MAPKK; e.g., MEK) and finally activation of MAP kinase (MAPK; e.g., ERK). Thus, this MAP3K-MAP2K-MAPK module represents critical effectors that regulate extracellular stimuli into cellular responses, such as differentiation, proliferation, and apoptosis all of which function during development. There are 21 characterized MAP3Ks that activate known MAP2Ks, and they function in many aspects of developmental biology. This review summarizes known transduction routes linked to each MAP3K and highlights mouse models that provide clues to their physiological functions. This perspective reveals that some of these MAP3K effectors may have redundant functions, and also serve as unique nexus depending on the context of the signaling pathway.
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Affiliation(s)
- Evisabel A Craig
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona, USA
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41
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Zang M, Gong J, Luo L, Zhou J, Xiang X, Huang W, Huang Q, Luo X, Olbrot M, Peng Y, Chen C, Luo Z. Characterization of Ser338 phosphorylation for Raf-1 activation. J Biol Chem 2008; 283:31429-37. [PMID: 18775988 DOI: 10.1074/jbc.m802855200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Raf kinases are essential for regulating cell proliferation, survival, and tumorigenesis. However, the mechanisms by which Raf is activated are still incompletely understood. Phosphorylation plays a critical role in Raf activation in response to mitogens. The present study characterizes phosphorylation of Ser338, a crucial event for Raf-1 activation. Here we report that mutation of Lys375 to Met diminishes phosphorylation of Ser338 on both wild type Raf-1 in cells treated with epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA) and a constitutively active mutant in which Tyr340/Tyr341 are replaced by 2 aspartic acids, a conserved substitution present in natural B-Raf. The loss of Ser338 phosphorylation in these Raf mutants is not engendered by a mutation-induced conformational change, inasmuch as mutation of another site (Ser471 to Ala) in the activation segment also abolishes Ser338 phosphorylation, whereas both the kinase-dead mutants of Raf-1 are phosphorylated well by active Pak1. Furthermore, our data demonstrate that EGF-stimulated phosphorylation of Ser338 is inhibited by Sorafenib, a Raf kinase inhibitor, but not by the MEK inhibitor U0126. Interestingly, a kinase-dead mutation and Sorafenib also markedly reduce phosphorylation of Ser445 on B-Raf, a site equivalent to Raf-1 Ser338. Finally, our data reveal that Ser338 is phosphorylated on inactive Raf-1 by an active mutant of Raf-1 when they are dimerized in cells and that artificial dimerization of Raf-1 causes Ser338 phosphorylation, accompanied by activation of ERK1/2. Altogether, our data suggest that Ser338 on Raf-1 is autophosphorylated in response to mitogens.
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Affiliation(s)
- Mengwei Zang
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Borysov SI, Guadagno TM. A novel role for Cdk1/cyclin B in regulating B-raf activation at mitosis. Mol Biol Cell 2008; 19:2907-15. [PMID: 18434602 DOI: 10.1091/mbc.e07-07-0679] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
MAPK activity is important during mitosis for spindle assembly and maintenance of the spindle checkpoint arrest. We previously identified B-Raf as a critical activator of the MAPK cascade during mitosis in Xenopus egg extracts and showed that B-Raf activation is regulated in an M-phase-dependent manner. The mechanism that mediates B-Raf activation at mitosis has not been elucidated. Interestingly, activation of 95-kDa B-Raf at mitosis does not require phosphorylation of Thr-599 and Ser-602 residues (Thr-633 and Ser-636 in Xenopus B-Raf), previously shown to be essential for B-Raf activation by Ras. Instead, we provide evidence for Cdk1/cyclin B in mediating mitotic activation of B-Raf. In particular, Cdk1/cyclin B complexes associate with B-Raf at mitosis in Xenopus egg extracts and contribute to its phosphorylation. Mutagenesis and in vitro kinase assays demonstrated that Cdk1/cyclin B directly phosphorylates B-Raf at Serine-144, which is part of a conserved Cdk1 preferential consensus site (S(144)PQK). Importantly, phosphorylation of Ser-144 is absolutely required for mitotic activation of B-Raf and subsequent activation of the MAPK cascade. However, substitution of a phospho-mimicking amino acid at Ser-144 failed to produce a constitutive active B-Raf indicating that, in addition of Ser-144 phosphorylation, other regulatory events may be needed to activate B-Raf at mitosis. Taken together, our data reveal a novel cell cycle mechanism for activating the B-Raf/MEK/MAPK cascade.
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Affiliation(s)
- Sergiy I Borysov
- Molecular Oncology Program, H. Lee Moffitt Cancer and Research Institute, Tampa, FL 33612, USA
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Tsukamoto H, Irie A, Senju S, Hatzopoulos AK, Wojnowski L, Nishimura Y. B-Raf-mediated signaling pathway regulates T cell development. Eur J Immunol 2008; 38:518-27. [PMID: 18228248 DOI: 10.1002/eji.200737430] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The activities of the Raf kinase family proteins control extracellular signal-regulated kinase (ERK) activation in many aspects of cellular responses. However, the relative contributions of individual isozymes to cellular functions including T cell responses are still unclear. In addition to Raf-1, another Raf family kinase, B-Raf, is expressed in murine thymocytes and peripheral T cells, and its activation was induced by TCR stimulation. Here, we investigated the function of B-Raf in development of T cells by generating chimeric mice in which a T cell-compromised host was reconstituted with fetal liver-derived cells from embryonic lethal B-Raf-deficient mice. Although B-Raf was dispensable for normal T cell lineage differentiation at the CD4(-)CD8(-) double-negative stage, thymocytes in the chimeric mice derived from B-Raf(-/-) cells exhibited a drastic arrest of differentiation at the CD4(+)CD8(+) double-positive stage, suggesting that B-Raf is crucial for T cell development, especially for the transition to CD4(+) and CD8(+) single-positive thymocytes. Regarding intracellular signaling, we found that activation of ERK following TCR stimulation was impaired in the thymocytes from the chimeric mice. In conclusion, we present first evidence for the important role of B-Raf-mediated signaling in T cell development.
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Affiliation(s)
- Hirotake Tsukamoto
- Department of Immunogenetics, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
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A-raf and B-raf are dispensable for normal endochondral bone development, and parathyroid hormone-related peptide suppresses extracellular signal-regulated kinase activation in hypertrophic chondrocytes. Mol Cell Biol 2007; 28:344-57. [PMID: 17967876 DOI: 10.1128/mcb.00617-07] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Parathyroid hormone-related peptide (PTHrP) and the parathyroid hormone-PTHrP receptor increase chondrocyte proliferation and delay chondrocyte maturation in endochondral bone development at least partly through cyclic AMP (cAMP)-dependent signaling pathways. Because data suggest that the ability of cAMP to stimulate cell proliferation involves the mitogen-activated protein kinase kinase kinase B-Raf, we hypothesized that B-Raf might mediate the proliferative action of PTHrP in chondrocytes. Though B-Raf is expressed in proliferative chondrocytes, its conditional removal from cartilage did not affect chondrocyte proliferation and maturation or PTHrP-induced chondrocyte proliferation and PTHrP-delayed maturation. Similar results were obtained by conditionally removing B-Raf from osteoblasts. Because A-raf and B-raf are expressed similarly in cartilage, we speculated that they may fulfill redundant functions in this tissue. Surprisingly, mice with chondrocytes deficient in both A-Raf and B-Raf exhibited normal endochondral bone development. Activated extracellular signal-regulated kinase (ERK) was detected primarily in hypertrophic chondrocytes, where C-raf is expressed, and the suppression of ERK activation in these cells by PTHrP or a MEK inhibitor coincided with a delay in chondrocyte maturation. Taken together, these results demonstrate that B-Raf and A-Raf are dispensable for endochondral bone development and they indicate that the main role of ERK in cartilage is to stimulate not cell proliferation, but rather chondrocyte maturation.
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Etchevers HC, Amiel J, Lyonnet S. Molecular bases of human neurocristopathies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 589:213-34. [PMID: 17076285 DOI: 10.1007/978-0-387-46954-6_14] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Heather C Etchevers
- Département de Génétique Médicale, INSERM U393, Hôpital Necker - Enfants Malades, 149 rue de Sèvres, 75743 Paris 15, France.
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McCubrey JA, Steelman LS, Chappell WH, Abrams SL, Wong EWT, Chang F, Lehmann B, Terrian DM, Milella M, Tafuri A, Stivala F, Libra M, Basecke J, Evangelisti C, Martelli AM, Franklin RA. Roles of the Raf/MEK/ERK pathway in cell growth, malignant transformation and drug resistance. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1773:1263-84. [PMID: 17126425 PMCID: PMC2696318 DOI: 10.1016/j.bbamcr.2006.10.001] [Citation(s) in RCA: 1685] [Impact Index Per Article: 99.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 10/02/2006] [Accepted: 10/03/2006] [Indexed: 02/07/2023]
Abstract
Growth factors and mitogens use the Ras/Raf/MEK/ERK signaling cascade to transmit signals from their receptors to regulate gene expression and prevent apoptosis. Some components of these pathways are mutated or aberrantly expressed in human cancer (e.g., Ras, B-Raf). Mutations also occur at genes encoding upstream receptors (e.g., EGFR and Flt-3) and chimeric chromosomal translocations (e.g., BCR-ABL) which transmit their signals through these cascades. Even in the absence of obvious genetic mutations, this pathway has been reported to be activated in over 50% of acute myelogenous leukemia and acute lymphocytic leukemia and is also frequently activated in other cancer types (e.g., breast and prostate cancers). Importantly, this increased expression is associated with a poor prognosis. The Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt pathways interact with each other to regulate growth and in some cases tumorigenesis. For example, in some cells, PTEN mutation may contribute to suppression of the Raf/MEK/ERK cascade due to the ability of activated Akt to phosphorylate and inactivate different Rafs. Although both of these pathways are commonly thought to have anti-apoptotic and drug resistance effects on cells, they display different cell lineage specific effects. For example, Raf/MEK/ERK is usually associated with proliferation and drug resistance of hematopoietic cells, while activation of the Raf/MEK/ERK cascade is suppressed in some prostate cancer cell lines which have mutations at PTEN and express high levels of activated Akt. Furthermore the Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt pathways also interact with the p53 pathway. Some of these interactions can result in controlling the activity and subcellular localization of Bim, Bak, Bax, Puma and Noxa. Raf/MEK/ERK may promote cell cycle arrest in prostate cells and this may be regulated by p53 as restoration of wild-type p53 in p53 deficient prostate cancer cells results in their enhanced sensitivity to chemotherapeutic drugs and increased expression of Raf/MEK/ERK pathway. Thus in advanced prostate cancer, it may be advantageous to induce Raf/MEK/ERK expression to promote cell cycle arrest, while in hematopoietic cancers it may be beneficial to inhibit Raf/MEK/ERK induced proliferation and drug resistance. Thus the Raf/MEK/ERK pathway has different effects on growth, prevention of apoptosis, cell cycle arrest and induction of drug resistance in cells of various lineages which may be due to the presence of functional p53 and PTEN and the expression of lineage specific factors.
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Affiliation(s)
- James A McCubrey
- Department of Microbiology and Immunology, Leo Jenkins Cancer Center, Brody School of Medicine at East Carolina University, Greenville, NC 27858, USA.
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Scholl FA, Dumesic PA, Barragan DI, Harada K, Bissonauth V, Charron J, Khavari PA. Mek1/2 MAPK kinases are essential for Mammalian development, homeostasis, and Raf-induced hyperplasia. Dev Cell 2007; 12:615-29. [PMID: 17419998 DOI: 10.1016/j.devcel.2007.03.009] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 02/26/2007] [Accepted: 03/09/2007] [Indexed: 10/23/2022]
Abstract
The p42/p44 mitogen-activated protein kinase (MAPK) cascade includes Ras, Raf, Mek, and Erk MAPK. To determine the effect of a full knockout at a single level of this signaling pathway in mammals, and to investigate functional redundancy between Mek1 and Mek2, we disrupted these genes in murine and human epidermis. Loss of either protein alone produced no phenotype, whereas combined Mek1/2 deletion in development or adulthood abolished Erk1/2 phosphorylation and led to hypoproliferation, apoptosis, skin barrier defects, and death. Conversely, a single copy of either allele was sufficient for normal development. Combined Mek1/2 loss also abolished Raf-induced hyperproliferation. Human tissue deficient in either Mek isoform was normal, whereas loss of both proteins led to hypoplasia, which was rescued by active Erk2 expression. These data indicate that Mek1/2 are functionally redundant in the epidermis, where they act as a linear relay in the MAPK pathway to mediate development and homeostasis.
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Affiliation(s)
- Florence A Scholl
- Veterans Affairs Palo Alto Healthcare System, Palo Alto, CA 94304, USA
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Leicht DT, Balan V, Kaplun A, Singh-Gupta V, Kaplun L, Dobson M, Tzivion G. Raf kinases: function, regulation and role in human cancer. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1196-212. [PMID: 17555829 PMCID: PMC1986673 DOI: 10.1016/j.bbamcr.2007.05.001] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2006] [Revised: 05/01/2007] [Accepted: 05/02/2007] [Indexed: 12/25/2022]
Abstract
The Ras-Raf-MAPK pathway regulates diverse physiological processes by transmitting signals from membrane based receptors to various nuclear, cytoplasmic and membrane-bound targets, coordinating a large variety of cellular responses. Function of Raf family kinases has been shown to play a role during organism development, cell cycle regulation, cell proliferation and differentiation, cell survival and apoptosis and many other cellular and physiological processes. Aberrations along the Ras-Raf-MAPK pathway play an integral role in various biological processes concerning human health and disease. Overexpression or activation of the pathway components is a common indicator in proliferative diseases such as cancer and contributes to tumor initiation, progression and metastasis. In this review, we focus on the physiological roles of Raf kinases in normal and disease conditions, specifically cancer, and the current thoughts on Raf regulation.
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Affiliation(s)
| | | | | | | | | | | | - Guri Tzivion
- To whom correspondence should be addressed: Karmanos Cancer Institute, Wayne State University, 4100 John R., HWCRC 716, Detroit, MI 48201, Tel: 313-576-8311, Fax: 313-576-8308, E-mail:
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Gerits N, Kostenko S, Moens U. In vivo functions of mitogen-activated protein kinases: conclusions from knock-in and knock-out mice. Transgenic Res 2007; 16:281-314. [PMID: 17219248 DOI: 10.1007/s11248-006-9052-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Accepted: 10/24/2006] [Indexed: 01/09/2023]
Abstract
Multicellular organisms achieve intercellular communication by means of signalling molecules whose effect on the target cell is mediated by signal transduction pathways. Such pathways relay, amplify and integrate signals to elicit appropriate biological responses. Protein kinases form crucial intermediate components of numerous signalling pathways. One group of protein kinases, the mitogen-activated protein kinases (MAP kinases) are kinases involved in signalling pathways that respond primarily to mitogens and stress stimuli. In vitro studies revealed that the MAP kinases are implicated in several cellular processes, including cell division, differentiation, cell survival/apoptosis, gene expression, motility and metabolism. As such, dysfunction of specific MAP kinases is associated with diseases such as cancer and immunological disorders. However, the genuine in vivo functions of many MAP kinases remain elusive. Genetically modified mouse models deficient in a specific MAP kinase or expressing a constitutive active or a dominant negative variant of a particular MAP kinase offer valuable tools for elucidating the biological role of these protein kinases. In this review, we focus on the current status of MAP kinase knock-in and knock-out mouse models and their phenotypes. Moreover, examples of the application of MAP kinase transgenic mice for validating therapeutic properties of specific MAP kinase inhibitors, and for investigating the role of MAP kinase in pathogen-host interactions will be discussed.
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Affiliation(s)
- Nancy Gerits
- Department of Microbiology and Virology, Institute of Medical Biology, University of Tromsø, Tromsø, Norway.
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Chen W, Yang S, Abe Y, Li M, Wang Y, Shao J, Li E, Li YP. Novel pycnodysostosis mouse model uncovers cathepsin K function as a potential regulator of osteoclast apoptosis and senescence. Hum Mol Genet 2007; 16:410-23. [PMID: 17210673 PMCID: PMC3578583 DOI: 10.1093/hmg/ddl474] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Pycnodysostosis is a genetic bone disease featuring the unique bone homeostasis disorders of osteolysis and osteopetrosis in the same organism. The pathomechanism for pycnodysostosis has been largely unknown due to the unavailability of a pycnodysostosis mouse model with all the traits of the disease. We generated cathepsin K(-/-) mouse strains in the 129/Sv and C57BL/6J backgrounds and found that, only in the 129/Sv background, cathepsin K(-/-) mice exhibit many characteristics of the human pycnodysostosis-like phenotype. Our data indicated that 129/Sv cathepsin K(-/-) osteoclasts (OCs) lacked normal apoptosis and senescence and exhibited over-growth both in vitro and in vivo. These abnormalities resulted in an unusually high OC number, which is consistent with a recent case study of human pycnodysostosis. Our results show that cathepsin K function has different effects around the skeleton due to site-specific variations in bone homeostasis, such as phenotypes of osteopetrosis in tibiae and osteolysis in calvariae as a result of cathepsin K mutation. Our data demonstrated that the expression levels of p19, p53 and p21 were significantly reduced in 129/Sv cathepsin K(-/-) OCs and forced expression of cathepsin K in pre-OCs induced premature senescence and increased expression of p19, p53 and p21. This is the first evidence that cathepsin K plays a key role in OC apoptosis and senescence, revealing the importance of OC senescence in bone homeostasis. The finding of this novel cathepsin K function provides insight into the pathomechanism of pycnodysostosis and may provide new drug targets for diseases involved in OC-related abnormal bone homeostasis.
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Affiliation(s)
- Wei Chen
- Department of Cytokine Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
- Harvard-Forsyth Department of Oral Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
| | - Shuying Yang
- Department of Cytokine Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
- Harvard-Forsyth Department of Oral Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
| | - Yoke Abe
- Department of Cytokine Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
| | - Ming Li
- Department of Cytokine Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
| | - Yucheng Wang
- Department of Cytokine Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
| | - Jianzhong Shao
- Department of Cytokine Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
- Life Science College, Zhejiang University, Hangzhou, China
| | - En Li
- Cardiovascular Research Center, Massachusetts General Hospital, Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
| | - Yi-Ping Li
- Department of Cytokine Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
- Harvard-Forsyth Department of Oral Biology, The Forsyth Institute & Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
- To whom correspondence should be addressed: Tel: +1 6178928260; Fax: +1 6172624021;
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