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Bonsor DA, Simanshu DK. RAS and SHOC2 Roles in RAF Activation and Therapeutic Considerations. ANNUAL REVIEW OF CANCER BIOLOGY 2024; 8:97-113. [PMID: 38882927 PMCID: PMC11178279 DOI: 10.1146/annurev-cancerbio-062822-030450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Mutations in RAS proteins play a pivotal role in the development of human cancers, driving persistent RAF activation and deregulating the Mitogen-Activated Protein Kinase (MAPK) signaling pathway. While progress has been made in targeting specific oncogenic RAS proteins, effective drug-based therapies for the majority of RAS mutations remain limited. Recent investigations on RAS-RAF complexes and the SHOC2-MRAS-PP1C holoenzyme complex have provided crucial insights into the structural and functional aspects of RAF activation within the MAPK signaling pathway. Moreover, these studies have also unveiled new blueprints for developing inhibitors allowing us to think beyond the current RAS and MEK inhibitors. In this review, we explore the roles of RAS and SHOC2 in activating RAF and discuss potential therapeutic strategies to target these proteins. A comprehensive understanding of the molecular interactions involved in RAF activation and their therapeutic implications holds the potential to drive innovative approaches in combating RAS/RAF-driven cancers.
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Affiliation(s)
- Daniel A. Bonsor
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dhirendra K. Simanshu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
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2
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Sanchez C, Ramirez A, Hodgson L. Unravelling molecular dynamics in living cells: Fluorescent protein biosensors for cell biology. J Microsc 2024. [PMID: 38357769 DOI: 10.1111/jmi.13270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 01/11/2024] [Accepted: 01/22/2024] [Indexed: 02/16/2024]
Abstract
Genetically encoded, fluorescent protein (FP)-based Förster resonance energy transfer (FRET) biosensors are microscopy imaging tools tailored for the precise monitoring and detection of molecular dynamics within subcellular microenvironments. They are characterised by their ability to provide an outstanding combination of spatial and temporal resolutions in live-cell microscopy. In this review, we begin by tracing back on the historical development of genetically encoded FP labelling for detection in live cells, which lead us to the development of early biosensors and finally to the engineering of single-chain FRET-based biosensors that have become the state-of-the-art today. Ultimately, this review delves into the fundamental principles of FRET and the design strategies underpinning FRET-based biosensors, discusses their diverse applications and addresses the distinct challenges associated with their implementation. We place particular emphasis on single-chain FRET biosensors for the Rho family of guanosine triphosphate hydrolases (GTPases), pointing to their historical role in driving our understanding of the molecular dynamics of this important class of signalling proteins and revealing the intricate relationships and regulatory mechanisms that comprise Rho GTPase biology in living cells.
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Affiliation(s)
- Colline Sanchez
- Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Andrea Ramirez
- Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Louis Hodgson
- Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA
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3
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Trebino TE, Markusic B, Nan H, Banerjee S, Wang Z. Unveiling the domain-specific and RAS isoform-specific details of BRAF kinase regulation. eLife 2023; 12:RP88836. [PMID: 38150000 PMCID: PMC10752582 DOI: 10.7554/elife.88836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023] Open
Abstract
BRAF is a key member in the MAPK signaling pathway essential for cell growth, proliferation, and differentiation. Mutant BRAF is often the underlying cause of various types of cancer and mutant RAS, the upstream regulator of BRAF, is a driver of up to one-third of all cancers. BRAF interacts with RAS and undergoes a conformational change from an inactive, autoinhibited monomer to an active dimer, which propagates downstream signaling. Because of BRAF's complex regulation mechanism, the exact order and magnitude of its activation steps have yet to be confirmed experimentally. By studying the inter- and intramolecular interactions of BRAF, we unveil the domain-specific and isoform-specific details of BRAF regulation through pulldown assays, open surface plasmon resonance (OpenSPR), and hydrogen-deuterium exchange mass spectrometry (HDX-MS). We demonstrate that the BRAF specific region (BSR) and cysteine rich domain (CRD) play a crucial role in regulating the activation of BRAF in a RAS isoform-specific manner. Moreover, we quantified the binding affinities between BRAF N-terminal and kinase domains (KD) to reveal their individual roles in autoinhibition. Our findings also indicate that oncogenic BRAF-KDD594G mutant has a lower affinity for the N-terminal domains, implicating that pathogenic BRAF acts through decreased propensity for autoinhibition. Collectively, our study provides valuable insight into the activation mechanism of BRAF kinase to guide the development of new therapeutic strategies for cancer treatment.
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Affiliation(s)
| | - Borna Markusic
- Rowan UniversityGlassboroUnited States
- Max Planck Institute of BiophysicsFrankfurt am MainGermany
| | - Haihan Nan
- Rowan UniversityGlassboroUnited States
- School of Laboratory Medicine and Life Science, Wenzhou Medical UniversityWenzhouChina
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Gladkikh BP, Danilov DV, D’yachenko VS, Butov GM. 1,3-Dichloroadamantyl-Containing Ureas as Potential Triple Inhibitors of Soluble Epoxide Hydrolase, p38 MAPK and c-Raf. Int J Mol Sci 2023; 25:338. [PMID: 38203510 PMCID: PMC10779153 DOI: 10.3390/ijms25010338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/21/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Soluble epoxide hydrolase (sEH) is an enzyme involved in the metabolism of bioactive lipid signaling molecules. sEH converts epoxyeicosatrienoic acids (EET) to virtually inactive dihydroxyeicosatrienoic acids (DHET). The first acids are "medicinal" molecules, the second increase the inflammatory infiltration of cells. Mitogen-activated protein kinases (p38 MAPKs) are key protein kinases involved in the production of inflammatory mediators, including tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2). p38 MAPK signaling plays an important role in the regulation of cellular processes, especially inflammation. The proto-oncogenic serine/threonine protein kinase Raf (c-Raf) is a major component of the mitogen-activated protein kinase (MAPK) pathway: ERK1/2 signaling. Normal cellular Raf genes can also mutate and become oncogenes, overloading the activity of MEK1/2 and ERK1/2. The development of multitarget inhibitors is a promising strategy for the treatment of socially dangerous diseases. We synthesized 1,3-disubstituted ureas and diureas containing a dichloroadamantyl moiety. The results of computational methods show that soluble epoxide hydrolase inhibitors can act on two more targets in different signaling pathways of mitogen-activated protein kinases p38 MAPK and c-Raf. The two chlorine atoms in the adamantyl moiety may provide additional Cl-π interactions in the active site of human sEH. Molecular dynamics studies have shown that the stability of ligand-protein complexes largely depends on the "spacer effect." The compound containing a bridge between the chloroadamantyl fragment and the ureide group forms more stable ligand-protein complexes with sEH and p38 MAPK, which indicates a better conformational ability of the molecule in the active sites of these targets. In turn, a compound containing two chlorine atoms forms a more stable complex with c-Raf, probably due to the presence of additional halogen bonds of chlorine atoms with amino acid residues.
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Affiliation(s)
- Boris P. Gladkikh
- Department of Technology of Organic and Petrochemical Synthesis, Volgograd State Technical University, Volgograd 400005, Russia; (B.P.G.); (D.V.D.); (G.M.B.)
| | - Dmitry V. Danilov
- Department of Technology of Organic and Petrochemical Synthesis, Volgograd State Technical University, Volgograd 400005, Russia; (B.P.G.); (D.V.D.); (G.M.B.)
| | - Vladimir S. D’yachenko
- Department of Technology of Organic and Petrochemical Synthesis, Volgograd State Technical University, Volgograd 400005, Russia; (B.P.G.); (D.V.D.); (G.M.B.)
- Department of Chemistry, Technology and Equipment of Chemical Industry, Volzhsky Polytechnic Institute (Branch), Volgograd State Technical University (VSTU), Volzhsky 404121, Russia
| | - Gennady M. Butov
- Department of Technology of Organic and Petrochemical Synthesis, Volgograd State Technical University, Volgograd 400005, Russia; (B.P.G.); (D.V.D.); (G.M.B.)
- Department of Chemistry, Technology and Equipment of Chemical Industry, Volzhsky Polytechnic Institute (Branch), Volgograd State Technical University (VSTU), Volzhsky 404121, Russia
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5
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Yu DM, Zhao J, Lee EE, Kim D, Mahapatra R, Rose EK, Zhou Z, Hosler C, El Kurdi A, Choe JY, Abel ED, Hoxhaj G, Westover KD, Cho RJ, Cheng JB, Wang RC. GLUT3 promotes macrophage signaling and function via RAS-mediated endocytosis in atopic dermatitis and wound healing. J Clin Invest 2023; 133:e170706. [PMID: 37721853 PMCID: PMC10617774 DOI: 10.1172/jci170706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 09/08/2023] [Indexed: 09/20/2023] Open
Abstract
The facilitative GLUT1 and GLUT3 hexose transporters are expressed abundantly in macrophages, but whether they have distinct functions remains unclear. We confirmed that GLUT1 expression increased after M1 polarization stimuli and found that GLUT3 expression increased after M2 stimulation in macrophages. Conditional deletion of Glut3 (LysM-Cre Glut3fl/fl) impaired M2 polarization of bone marrow-derived macrophages. Alternatively activated macrophages from the skin of patients with atopic dermatitis showed increased GLUT3 expression, and a calcipotriol-induced model of atopic dermatitis was rescued in LysM-Cre Glut3fl/fl mice. M2-like macrophages expressed GLUT3 in human wound tissues as assessed by transcriptomics and costaining, and GLUT3 expression was significantly decreased in nonhealing, compared with healing, diabetic foot ulcers. In an excisional wound healing model, LysM-Cre Glut3fl/fl mice showed significantly impaired M2 macrophage polarization and delayed wound healing. GLUT3 promoted IL-4/STAT6 signaling, independently of its glucose transport activity. Unlike plasma membrane-localized GLUT1, GLUT3 was localized primarily to endosomes and was required for the efficient endocytosis of IL-4Rα subunits. GLUT3 interacted directly with GTP-bound RAS in vitro and in vivo through its intracytoplasmic loop domain, and this interaction was required for efficient STAT6 activation and M2 polarization. PAK activation and macropinocytosis were also impaired without GLUT3, suggesting broader roles for GLUT3 in the regulation of endocytosis. Thus, GLUT3 is required for efficient alternative macrophage polarization and function, through a glucose transport-independent, RAS-mediated role in the regulation of endocytosis and IL-4/STAT6 activation.
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Affiliation(s)
- Dong-Min Yu
- Department of Dermatology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Jiawei Zhao
- Division of Hematology/Oncology, Boston Children’s Hospital and Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Eunice E. Lee
- Department of Dermatology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Dohun Kim
- Children’s Medical Center Research Institute and
| | - Ruchika Mahapatra
- Department of Dermatology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Elysha K. Rose
- Department of Dermatology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Zhiwei Zhou
- Departments of Biochemistry and Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Calvin Hosler
- Department of Dermatology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Abdullah El Kurdi
- Department of Biochemistry and Molecular Genetics, American University of Beirut, Beirut, Lebanon
| | - Jun-Yong Choe
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | - E. Dale Abel
- Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - Gerta Hoxhaj
- Children’s Medical Center Research Institute and
| | - Kenneth D. Westover
- Departments of Biochemistry and Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Raymond J. Cho
- Department of Dermatology, UCSF, San Francisco, California, USA
| | | | - Richard C. Wang
- Department of Dermatology, UT Southwestern Medical Center, Dallas, Texas, USA
- Harold C. Simmons Cancer Center, UT Southwestern Medical Center, Dallas, Texas, USA
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Trebino T, Markusic B, Nan H, Banerjee S, Wang Z. Unveiling the Domain-Specific and RAS Isoform-Specific Details of BRAF Regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538112. [PMID: 37163002 PMCID: PMC10168249 DOI: 10.1101/2023.04.24.538112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
BRAF is a key member in the MAPK signaling pathway essential for cell growth, proliferation, and differentiation. Dysregulation or mutation of BRAF is often the underlying cause of various types of cancer. RAS, a small GTPase protein that acts upstream of BRAF, has been identified as a driver of up to one-third of all cancers. When BRAF interacts with RAS via the RAS binding domain (RBD) and membrane recruitment, BRAF undergoes a conformational change from an inactive, autoinhibited monomer to an active dimer and subsequently phosphorylates MEK to propagate the signal. Despite the central role of BRAF in cellular signaling, the exact order and magnitude of its activation steps has yet to be confirmed experimentally. By studying the inter- and intramolecular interactions of BRAF, we unveil the domain-specific and isoform-specific details of BRAF regulation. We employed pulldown assays, open surface plasmon resonance (OpenSPR), and hydrogen-deuterium exchange mass spectrometry (HDX-MS) to investigate the roles of the regulatory regions in BRAF activation and autoinhibition. Our results demonstrate that the BRAF specific region (BSR) and cysteine rich domain (CRD) play a crucial role in regulating the activity of BRAF. Moreover, we quantified the autoinhibitory binding affinities between the N-terminal domains and the kinase domain (KD) of BRAF and revealed the individual roles of the BRAF regulatory domains. Additionally, our findings provide evidence that the BSR negatively regulates BRAF activation in a RAS isoform-specific manner. Our findings also indicate that oncogenic BRAF-KDD594G mutant has a lower affinity for the regulatory domains, implicating that pathogenic BRAF acts through decreased propensity for autoinhibition. Collectively, our study provides valuable insights into the activation mechanism of BRAF kinase and may help to guide the development of new therapeutic strategies for cancer treatment.
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Affiliation(s)
- Tarah Trebino
- Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, USA
| | - Borna Markusic
- Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, USA
- Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany
| | - Haihan Nan
- Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, USA
- School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Shrhea Banerjee
- Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, USA
| | - Zhihong Wang
- Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, USA
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7
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Chen PY, Huang BJ, Harris M, Boone C, Wang W, Carias H, Mesiona B, Mavrici D, Kohler AC, Bollag G, Zhang C, Zhang Y, Shannon K. Structural and functional analyses of a germline KRAS T50I mutation provide insights into Raf activation. JCI Insight 2023; 8:e168445. [PMID: 37681415 PMCID: PMC10544224 DOI: 10.1172/jci.insight.168445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 08/02/2023] [Indexed: 09/09/2023] Open
Abstract
A T50I substitution in the K-Ras interswitch domain causes Noonan syndrome and emerged as a third-site mutation that restored the in vivo transforming activity and constitutive MAPK pathway activation by an attenuated KrasG12D,E37G oncogene in a mouse leukemia model. Biochemical and crystallographic data suggested that K-RasT50I increases MAPK signal output through a non-GTPase mechanism, potentially by promoting asymmetric Ras:Ras interactions between T50 and E162. We generated a "switchable" system in which K-Ras mutant proteins expressed at physiologic levels supplant the fms like tyrosine kinase 3 (FLT3) dependency of MOLM-13 leukemia cells lacking endogenous KRAS and used this system to interrogate single or compound G12D, T50I, D154Q, and E162L mutations. These studies support a key role for the asymmetric lateral assembly of K-Ras in a plasma membrane-distal orientation that promotes the formation of active Ras:Raf complexes in a membrane-proximal conformation. Disease-causing mutations such as T50I are a valuable starting point for illuminating normal Ras function, elucidating mechanisms of disease, and identifying potential therapeutic opportunities for Rasopathy disorders and cancer.
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Affiliation(s)
- Pan-Yu Chen
- Department of Pediatrics, UCSF, San Francisco, California, USA
| | | | - Max Harris
- Department of Pediatrics, UCSF, San Francisco, California, USA
| | | | - Weijie Wang
- Department of Pediatrics, UCSF, San Francisco, California, USA
| | - Heidi Carias
- Plexxikon Inc., South San Francisco, California, USA
| | - Brian Mesiona
- Plexxikon Inc., South San Francisco, California, USA
| | | | | | - Gideon Bollag
- Plexxikon Inc., South San Francisco, California, USA
| | - Chao Zhang
- Plexxikon Inc., South San Francisco, California, USA
| | - Ying Zhang
- Plexxikon Inc., South San Francisco, California, USA
| | - Kevin Shannon
- Department of Pediatrics, UCSF, San Francisco, California, USA
- Helen Diller Family Comprehensive Cancer Center, UCSF, San Francisco, California, USA
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8
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Wilhelm T, Toledo MAS, Simons I, Stuth C, Mohta V, Mülfarth R, Nitsche M, Maschke-Neuß K, Schmitz S, Kaiser A, Panse J, Christen D, Arock M, Zenke M, Huber M. Capitalizing on paradoxical activation of the mitogen-activated protein kinase pathway for treatment of Imatinib-resistant mast cell leukemia. Hematol Oncol 2023; 41:520-534. [PMID: 36383121 DOI: 10.1002/hon.3100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 08/29/2022] [Accepted: 11/14/2022] [Indexed: 11/17/2022]
Abstract
Prevention of fatal side effects during cancer therapy of cancer patients with high-dosed pharmacological inhibitors is to date a major challenge. Moreover, the development of drug resistance poses severe problems for the treatment of patients with leukemia or solid tumors. Particularly drug-mediated dimerization of RAF kinases can be the cause of acquired resistance, also called "paradoxical activation." In the present work we re-analyzed the effects of different tyrosine kinase inhibitors (TKIs) on the proliferation, metabolic activity, and survival of the Imatinib-resistant, KIT V560G, D816V-expressing human mast cell (MC) leukemia (MCL) cell line HMC-1.2. We observed that low concentrations of the TKIs Nilotinib and Ponatinib resulted in enhanced proliferation, suggesting paradoxical activation of the MAPK pathway. Indeed, these TKIs caused BRAF-CRAF dimerization, resulting in ERK1/2 activation. The combination of Ponatinib with the MEK inhibitor Trametinib, at nanomolar concentrations, effectively suppressed HMC-1.2 proliferation, metabolic activity, and induced apoptotic cell death. Effectiveness of this drug combination was recapitulated in the human KIT D816V MC line ROSAKIT D816V and in KIT D816V hematopoietic progenitors obtained from patient-derived induced pluripotent stem cells (iPS cells) and systemic mastocytosis patient samples. In conclusion, mutated KIT-driven Imatinib resistance and possible TKI-induced paradoxical activation can be efficiently overcome by a low concentration Ponatinib and Trametinib co-treatment, potentially reducing the negative side effects associated with MCL therapy.
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Affiliation(s)
- Thomas Wilhelm
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Marcelo A S Toledo
- Department of Cell Biology, Institute for Biomedical Engineering, RWTH Aachen University Medical School, Aachen, Germany
- Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University Medical School, Aachen, Germany
- Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Ilka Simons
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Christian Stuth
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Vrinda Mohta
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Ronja Mülfarth
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Marcus Nitsche
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Karin Maschke-Neuß
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Susanne Schmitz
- Department of Cell Biology, Institute for Biomedical Engineering, RWTH Aachen University Medical School, Aachen, Germany
- Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Anne Kaiser
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University Medical School, Aachen, Germany
- Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Jens Panse
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University Medical School, Aachen, Germany
- Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Deborah Christen
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University Medical School, Aachen, Germany
- Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Michel Arock
- Department of Hematological Biology, Pitié-Salpêtrière Hospital, Pierre et Marie Curie University (UPMC), Paris, France
| | - Martin Zenke
- Department of Cell Biology, Institute for Biomedical Engineering, RWTH Aachen University Medical School, Aachen, Germany
- Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University Medical School, Aachen, Germany
- Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Michael Huber
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
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9
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Chen L, Li Y, Chen Y. KLHL7 promotes hepatocellular carcinoma progression and molecular therapy resistance by degrading RASA2. iScience 2023; 26:106914. [PMID: 37378318 PMCID: PMC10291331 DOI: 10.1016/j.isci.2023.106914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 12/27/2022] [Accepted: 05/14/2023] [Indexed: 06/29/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is a common aggressive tumor with a poor prognosis, and patients often seem to be refractory to the use of therapeutic drugs. In this study, we found that the KLHL7 expression was upregulated in HCC that was associated with poor patient prognosis. KLHL7 has been found to promote HCC development in both in vitro and in vivo experiments. Mechanistically, RASA2, a RAS GAP, was identified as a substrate of KLHL7. Upregulation of KLHL7 by growth factors promotes K48-linked polyubiquitination of RASA2 for degradation via the proteasomal pathway. Our in vivo experiments revealed that inhibition of KLHL7 in combination with lenvatinib treatment resulted in efficient killing of HCC cells. Together, these findings demonstrate a role for KLHL7 in HCC and reveal a mechanism by which growth factors regulate the RAS-MAPK pathway. It represents a potential therapeutic target for HCC.
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Affiliation(s)
- Lin Chen
- Department of Oncology, NHC Key Laboratory of Cancer Proteomics, State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Yun Li
- Department of Oncology, NHC Key Laboratory of Cancer Proteomics, State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Yongheng Chen
- Department of Oncology, NHC Key Laboratory of Cancer Proteomics, State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
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10
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Spencer-Smith R, Terrell EM, Insinna C, Agamasu C, Wagner ME, Ritt DA, Stauffer J, Stephen AG, Morrison DK. RASopathy mutations provide functional insight into the BRAF cysteine-rich domain and reveal the importance of autoinhibition in BRAF regulation. Mol Cell 2022; 82:4262-4276.e5. [PMID: 36347258 PMCID: PMC9677513 DOI: 10.1016/j.molcel.2022.10.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/16/2022] [Accepted: 10/14/2022] [Indexed: 11/09/2022]
Abstract
BRAF is frequently mutated in human cancer and the RASopathy syndromes, with RASopathy mutations often observed in the cysteine-rich domain (CRD). Although the CRD participates in phosphatidylserine (PS) binding, the RAS-RAF interaction, and RAF autoinhibition, the impact of these activities on RAF function in normal and disease states is not well characterized. Here, we analyze a panel of CRD mutations and show that they increase BRAF activity by relieving autoinhibition and/or enhancing PS binding, with relief of autoinhibition being the major factor determining mutation severity. Further, we show that CRD-mediated autoinhibition prevents the constitutive plasma membrane localization of BRAF that causes increased RAS-dependent and RAS-independent function. Comparison of the BRAF- and CRAF-CRDs also indicates that the BRAF-CRD is a stronger mediator of autoinhibition and PS binding, and given the increased catalytic activity of BRAF, our studies reveal a more critical role for CRD-mediated autoinhibition in BRAF regulation.
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Affiliation(s)
- Russell Spencer-Smith
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Elizabeth M Terrell
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Christine Insinna
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Constance Agamasu
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702 USA
| | - Morgan E Wagner
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702 USA
| | - Daniel A Ritt
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Jim Stauffer
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Andrew G Stephen
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702 USA
| | - Deborah K Morrison
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA.
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11
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Nguyen K, López CA, Neale C, Van QN, Carpenter TS, Di Natale F, Travers T, Tran TH, Chan AH, Bhatia H, Frank PH, Tonelli M, Zhang X, Gulten G, Reddy T, Burns V, Oppelstrup T, Hengartner N, Simanshu DK, Bremer PT, Chen D, Glosli JN, Shrestha R, Turbyville T, Streitz FH, Nissley DV, Ingólfsson HI, Stephen AG, Lightstone FC, Gnanakaran S. Exploring CRD mobility during RAS/RAF engagement at the membrane. Biophys J 2022; 121:3630-3650. [PMID: 35778842 PMCID: PMC9617161 DOI: 10.1016/j.bpj.2022.06.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 06/21/2022] [Accepted: 06/28/2022] [Indexed: 11/25/2022] Open
Abstract
During the activation of mitogen-activated protein kinase (MAPK) signaling, the RAS-binding domain (RBD) and cysteine-rich domain (CRD) of RAF bind to active RAS at the plasma membrane. The orientation of RAS at the membrane may be critical for formation of the RAS-RBDCRD complex and subsequent signaling. To explore how RAS membrane orientation relates to the protein dynamics within the RAS-RBDCRD complex, we perform multiscale coarse-grained and all-atom molecular dynamics (MD) simulations of KRAS4b bound to the RBD and CRD domains of RAF-1, both in solution and anchored to a model plasma membrane. Solution MD simulations describe dynamic KRAS4b-CRD conformations, suggesting that the CRD has sufficient flexibility in this environment to substantially change its binding interface with KRAS4b. In contrast, when the ternary complex is anchored to the membrane, the mobility of the CRD relative to KRAS4b is restricted, resulting in fewer distinct KRAS4b-CRD conformations. These simulations implicate membrane orientations of the ternary complex that are consistent with NMR measurements. While a crystal structure-like conformation is observed in both solution and membrane simulations, a particular intermolecular rearrangement of the ternary complex is observed only when it is anchored to the membrane. This configuration emerges when the CRD hydrophobic loops are inserted into the membrane and helices α3-5 of KRAS4b are solvent exposed. This membrane-specific configuration is stabilized by KRAS4b-CRD contacts that are not observed in the crystal structure. These results suggest modulatory interplay between the CRD and plasma membrane that correlate with RAS/RAF complex structure and dynamics, and potentially influence subsequent steps in the activation of MAPK signaling.
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Affiliation(s)
- Kien Nguyen
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Cesar A López
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Chris Neale
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Que N Van
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Timothy S Carpenter
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California
| | - Francesco Di Natale
- Applications, Simulations, and Quality, Lawrence Livermore National Laboratory, Livermore, California
| | | | - Timothy H Tran
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Albert H Chan
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Harsh Bhatia
- Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, Livermore, California
| | - Peter H Frank
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Marco Tonelli
- National Magnetic Resonance Facility at Madison, Biochemistry Department, University of Wisconsin-Madison, Madison, Wisconsin
| | - Xiaohua Zhang
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California
| | - Gulcin Gulten
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Tyler Reddy
- CCS-7, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Violetta Burns
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Tomas Oppelstrup
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California
| | - Nick Hengartner
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Dhirendra K Simanshu
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Peer-Timo Bremer
- Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, Livermore, California
| | - De Chen
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - James N Glosli
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California
| | - Rebika Shrestha
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Thomas Turbyville
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Frederick H Streitz
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California
| | - Dwight V Nissley
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Helgi I Ingólfsson
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California
| | - Andrew G Stephen
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Felice C Lightstone
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California
| | - Sandrasegaram Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico.
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12
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Chow A, Khan ZM, Marsiglia WM, Dar AC. Conformational control and regulation of the pseudokinase KSR via small molecule binding interactions. Methods Enzymol 2022; 667:365-402. [PMID: 35525547 PMCID: PMC9150438 DOI: 10.1016/bs.mie.2022.03.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pseudokinases often operate through functionally related enzymes and receptors. A prime example is the pseudokinase KSR (Kinase Suppressor of RAS), which can act as both an amplifier and inhibitor of members in the RAS-MAPK (Mitogen Activated Protein Kinase) signaling pathway. KSR is structurally related to the active RAF kinases over multiple domains; moreover, the pseudokinase domain of KSR forms physical and regulatory complexes with both RAF and MEK through distinct interfaces. Characterization of small molecule interactions on KSR has been used to uncover novel chemical tools and understand the mechanism of action of clinical drugs. Here, we elaborate on assays and structural methods for measuring binding at orthosteric and interfacial binding sites on KSR. These distinct small molecule pockets provide therapeutic paths for targeting KSR1 and KSR2 pseudokinases in disease, including in RAS and RAF mutant cancers.
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Affiliation(s)
- Arthur Chow
- Department of Oncological Sciences, Department of Pharmacological Sciences, The Tisch Cancer Institute, Mount Sinai Centre for Therapeutic Discovery, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Zaigham M Khan
- Department of Oncological Sciences, Department of Pharmacological Sciences, The Tisch Cancer Institute, Mount Sinai Centre for Therapeutic Discovery, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - William M Marsiglia
- Department of Oncological Sciences, Department of Pharmacological Sciences, The Tisch Cancer Institute, Mount Sinai Centre for Therapeutic Discovery, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Arvin C Dar
- Department of Oncological Sciences, Department of Pharmacological Sciences, The Tisch Cancer Institute, Mount Sinai Centre for Therapeutic Discovery, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
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13
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Johnson CW, Seo HS, Terrell EM, Yang MH, KleinJan F, Gebregiworgis T, Gasmi-Seabrook GMC, Geffken EA, Lakhani J, Song K, Bashyal P, Popow O, Paulo JA, Liu A, Mattos C, Marshall CB, Ikura M, Morrison DK, Dhe-Paganon S, Haigis KM. Regulation of GTPase function by autophosphorylation. Mol Cell 2022; 82:950-968.e14. [PMID: 35202574 PMCID: PMC8986090 DOI: 10.1016/j.molcel.2022.02.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 11/29/2021] [Accepted: 02/04/2022] [Indexed: 10/19/2022]
Abstract
A unifying feature of the RAS superfamily is a conserved GTPase cycle by which these proteins transition between active and inactive states. We demonstrate that autophosphorylation of some GTPases is an intrinsic regulatory mechanism that reduces nucleotide hydrolysis and enhances nucleotide exchange, altering the on/off switch that forms the basis for their signaling functions. Using X-ray crystallography, nuclear magnetic resonance spectroscopy, binding assays, and molecular dynamics on autophosphorylated mutants of H-RAS and K-RAS, we show that phosphoryl transfer from GTP requires dynamic movement of the switch II region and that autophosphorylation promotes nucleotide exchange by opening the active site and extracting the stabilizing Mg2+. Finally, we demonstrate that autophosphorylated K-RAS exhibits altered effector interactions, including a reduced affinity for RAF proteins in mammalian cells. Thus, autophosphorylation leads to altered active site dynamics and effector interaction properties, creating a pool of GTPases that are functionally distinct from their non-phosphorylated counterparts.
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Affiliation(s)
- Christian W Johnson
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Hyuk-Soo Seo
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Elizabeth M Terrell
- Laboratory of Cell and Developmental Signaling, NCI-Frederick, Frederick, MD 21702, USA
| | - Moon-Hee Yang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Fenneke KleinJan
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada
| | - Teklab Gebregiworgis
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada
| | | | - Ezekiel A Geffken
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Jimit Lakhani
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Kijun Song
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Puspalata Bashyal
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Olesja Popow
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Andrea Liu
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Carla Mattos
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | | | - Mitsuhiko Ikura
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada
| | - Deborah K Morrison
- Laboratory of Cell and Developmental Signaling, NCI-Frederick, Frederick, MD 21702, USA
| | - Sirano Dhe-Paganon
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Kevin M Haigis
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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14
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Brown MA, Ried T. Shifting the Focus of Signaling Abnormalities in Colon Cancer. Cancers (Basel) 2022; 14:cancers14030784. [PMID: 35159051 PMCID: PMC8834070 DOI: 10.3390/cancers14030784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 01/26/2022] [Accepted: 01/30/2022] [Indexed: 12/12/2022] Open
Abstract
Simple Summary The major signaling pathways in colon cancer are WNT, RAS, and TGF-β. Components of these pathways are mutated in the majority of colon cancers, resulting in aberrantly high or low activity of the pathway. The functional consequences of the mutations reflect the behavior of these signaling pathways in intestinal stem cells. To better understand the roles of each pathway, we cover the basic function as well as points of intersection between the different pathways, to describe how they function individually, as well as together, to regulate cell proliferation. Abstract Colon cancer tumorigenesis occurs incrementally. The process involves the acquisition of mutations which typically follow an established pattern: activation of WNT signaling, activation of RAS signaling, and inhibition of TGF-β signaling. This arrangement recapitulates, to some degree, the stem cell niche of the intestinal epithelium, which maintains WNT and EGF activity while suppressing TGF-β. The resemblance between the intestinal stem cell environment and colon cancer suggests that the concerted activity of these pathways generates and maintains a potent growth-inducing stimulus. However, each pathway has a myriad of downstream targets, making it difficult to identify which aspects of these pathways are drivers. To address this, we utilize the cell cycle, the ultimate regulator of cell proliferation, as a foundation for cross-pathway integration. We attempt to generate an overview of colon cancer signaling patterns by integrating the major colon cancer signaling pathways in the context of cell replication, specifically, the entrance from G1 into S-phase.
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15
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Fan G, Lou L, Song Z, Zhang X, Xiong XF. Targeting mutated GTPase KRAS in tumor therapies. Eur J Med Chem 2021; 226:113816. [PMID: 34520956 DOI: 10.1016/j.ejmech.2021.113816] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/24/2021] [Accepted: 08/29/2021] [Indexed: 12/13/2022]
Abstract
Kirsten rat sarcoma virus oncogene (KRAS) mutation accounts for approximately 85% of RAS-driven cancers, and participates in multiple signaling pathways and mediates cell proliferation, differentiation and metabolism. KRAS has been considered as an "undruggable" target due to the lack of effective direct inhibitors, although high frequency of KRAS mutations have been identified in multiple carcinomas in the past decades. Encouragingly, the KRASG12C inhibitor AMG510 (sotorasib), which has been approved for treating NSCLC and CRC recently, makes directly targeting KRAS the most promising strategy for cancer therapy. To better understand the current state of KRAS inhibitors, this review summarizes the biological functions of KRAS, the structure-activity relationship studies of the small-molecule inhibitors that directly target KRAS, and highlights the therapeutic agents with improved selectivity, bioavailability and physicochemical properties. Furthermore, the combined medication that can enhance efficacy and overcome drug resistance of KRAS covalent inhibitors is also reviewed.
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Affiliation(s)
- Guangjin Fan
- Guangdong Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Linlin Lou
- Guangdong Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Zhendong Song
- Guangdong Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.
| | - Xiaolei Zhang
- Guangdong Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.
| | - Xiao-Feng Xiong
- Guangdong Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.
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16
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Tawfeeq N, Jin Y, Lamango NS. Synthetic Optimization and MAPK Pathway Activation Anticancer Mechanism of Polyisoprenylated Cysteinyl Amide Inhibitors. Cancers (Basel) 2021; 13:cancers13225757. [PMID: 34830912 PMCID: PMC8616522 DOI: 10.3390/cancers13225757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/14/2021] [Accepted: 11/15/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary RAS G-protein genes are frequently mutated and drive the progression of about 30% of human cancers. Polyisoprenylated cysteinyl amide inhibitors (PCAIs) offer a novel approach to address the decades-long anti-RAS drug development challenge. This manuscript reports on the continuous development of the PCAIs and their anticancer molecular mechanisms that involve strong activation of MAP kinase pathway enzymes. Abstract Abnormalities of the MAPK pathway play vital roles in cancer initiation and progression. RAS GTPases that are key upstream mediators of the pathway are mutated in 30% of human cancers. Polyisoprenylated cysteinyl amide inhibitors (PCAIs) were designed as potential targeted therapies against the RAS-driven cancers. The current study reports on the optimization of the PCAIs and the determination of their mechanisms of action in KRAS-mutant cancer cells. They display ClogP values ranging from 3.01 to 6.35, suppressing the viabilities of KRAS-mutant MDA-MB-231, A549, MIA PaCa-2, and NCI-H1299 cells in 2D and 3D cultures with EC50 values of 2.2 to 6.8, 2.2 to 7.6, 2.3 to 6.5 and 5.0 to 14 µM, respectively. When A549 cells were treated with the PCAIs, NSL-YHJ-2-27, for 48 h, no significant difference was observed in the levels of total or phosphorylated B- and C-Raf proteins. However, at 5 µM, it stimulated the phosphorylation of MEK1/2, ERK1/2, and p90RSK by 84%, 59%, and 160%, respectively, relative to controls. A non-farnesylated analog, NSL-YHJ-2-62, did not elicit similar effects. These data reveal that effects on the RAS-MAPK signaling axis most likely contribute to the anticancer effects of the PCAIs, possibly through the proapoptotic isoforms of p90RSK. The PCAIs may thus have the potential to serve the unmet therapeutic needs of patients with aberrant hyperactive G-protein signaling.
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17
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Zang Y, Kahsai AW, Pakharukova N, Huang LY, Lefkowitz RJ. The GPCR-β-arrestin complex allosterically activates C-Raf by binding its amino terminus. J Biol Chem 2021; 297:101369. [PMID: 34757127 PMCID: PMC8633562 DOI: 10.1016/j.jbc.2021.101369] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 10/20/2021] [Accepted: 10/27/2021] [Indexed: 12/22/2022] Open
Abstract
G protein-coupled receptors (GPCRs) convert external stimuli into cellular signals through heterotrimeric guanine nucleotide-binding proteins (G-proteins) and β-arrestins (βarrs). In a βarr-dependent signaling pathway, βarrs link GPCRs to various downstream signaling partners, such as the Raf-mitogen-activated protein kinase extracellular signal-regulated kinase-extracellular signal-regulated kinase cascade. Agonist-stimulated GPCR-βarr complexes have been shown to interact with C-Raf and are thought to initiate the mitogen-activated protein kinase pathway through simple tethering of these signaling partners. However, recent evidence shows that in addition to canonical scaffolding functions, βarrs can allosterically activate downstream targets, such as the nonreceptor tyrosine kinase Src. Here, we demonstrate the direct allosteric activation of C-Raf by GPCR-βarr1 complexes in vitro. Furthermore, we show that βarr1 in complex with a synthetic phosphopeptide mimicking the human V2 vasopressin receptor tail that binds and functionally activates βarrs also allosterically activates C-Raf. We reveal that the interaction between the phosphorylated GPCR C terminus and βarr1 is necessary and sufficient for C-Raf activation. Interestingly, the interaction between βarr1 and C-Raf was considerably reduced in the presence of excess activated H-Ras, a small GTPase known to activate C-Raf, suggesting that H-Ras and βarr1 bind to the same region on C-Raf. Furthermore, we found that βarr1 interacts with the Ras-binding domain of C-Raf. Taken together, these data suggest that in addition to canonical scaffolding functions, GPCR-βarr complexes directly allosterically activate C-Raf by binding to its amino terminus. This work provides novel insights into how βarrs regulate effector molecules to activate downstream signaling pathways.
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Affiliation(s)
- Yunxiang Zang
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA; Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Alem W Kahsai
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Natalia Pakharukova
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Li-Yin Huang
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Robert J Lefkowitz
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA; Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina, USA; Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, USA.
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18
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Nomura TK, Heishima K, Sugito N, Sugawara R, Ueda H, Yukihiro A, Honda R. Specific inhibition of oncogenic RAS using cell-permeable RAS-binding domains. Cell Chem Biol 2021; 28:1581-1589.e6. [PMID: 33964212 DOI: 10.1016/j.chembiol.2021.04.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 03/17/2021] [Accepted: 04/20/2021] [Indexed: 10/21/2022]
Abstract
Oncogenic RAS proteins, common oncogenic drivers in many human cancers, have been refractory to conventional small-molecule and macromolecule inhibitors due to their intracellular localization and the lack of druggable pockets. Here, we present a feasible strategy for designing RAS inhibitors that involves intracellular delivery of RAS-binding domain (RBD), a nanomolar-affinity specific ligand of RAS. Screening of 51 different combinations of RBD and cell-permeable peptides has identified Pen-cRaf-v1 as a cell-permeable pan-RAS inhibitor capable of targeting both G12C and non-G12C RAS mutants. Pen-cRaf-v1 crosses the cell membrane via endocytosis, competitively inhibits RAS-effector interaction, and thereby exerts anticancer activity against several KRAS-mutant cancer cell lines. Moreover, Pen-cRaf-v1 exhibits excellent activity comparable with a leading pan-RAS inhibitor (BI-2852), as well as high target specificity in transcriptome analysis and alanine mutation analysis. These findings demonstrate that specific inhibition of oncogenic RAS, and possibly treatment of RAS-mutant cancer, is feasible by intracellular delivery of RBD.
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Affiliation(s)
- Teiko Komori Nomura
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Kazuki Heishima
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Nobuhiko Sugito
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Ryota Sugawara
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Hiroshi Ueda
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Akao Yukihiro
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Ryo Honda
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan.
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19
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Han CW, Jeong MS, Jang SB. Understand KRAS and the Quest for Anti-Cancer Drugs. Cells 2021; 10:cells10040842. [PMID: 33917906 PMCID: PMC8068306 DOI: 10.3390/cells10040842] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/06/2021] [Accepted: 04/06/2021] [Indexed: 12/30/2022] Open
Abstract
The KRAS oncogene is mutated in approximately ~30% of human cancers, and the targeting of KRAS has long been highlighted in many studies. Nevertheless, attempts to target KRAS directly have been ineffective. This review provides an overview of the structure of KRAS and its characteristic signaling pathways. Additionally, we examine the problems associated with currently available KRAS inhibitors and discuss promising avenues for drug development.
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Affiliation(s)
- Chang Woo Han
- Institute of Systems Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 46241, Korea;
| | - Mi Suk Jeong
- Institute for Plastic Information and Energy Materials and Sustainable Utilization of Photovoltaic Energy Research Center, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 46241, Korea
- Correspondence: (M.S.J.); (S.B.J.); Tel.: +82-51-510-2523 (M.S.J. & S.B.J.)
| | - Se Bok Jang
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 46241, Korea
- Correspondence: (M.S.J.); (S.B.J.); Tel.: +82-51-510-2523 (M.S.J. & S.B.J.)
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20
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Cook FA, Cook SJ. Inhibition of RAF dimers: it takes two to tango. Biochem Soc Trans 2021; 49:237-251. [PMID: 33367512 PMCID: PMC7924995 DOI: 10.1042/bst20200485] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/17/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023]
Abstract
The RAS-regulated RAF-MEK1/2-ERK1/2 pathway promotes cell proliferation and survival and RAS and BRAF proteins are commonly mutated in cancer. This has fuelled the development of small molecule kinase inhibitors including ATP-competitive RAF inhibitors. Type I and type I½ ATP-competitive RAF inhibitors are effective in BRAFV600E/K-mutant cancer cells. However, in RAS-mutant cells these compounds instead promote RAS-dependent dimerisation and paradoxical activation of wild-type RAF proteins. RAF dimerisation is mediated by two key regions within each RAF protein; the RKTR motif of the αC-helix and the NtA-region of the dimer partner. Dimer formation requires the adoption of a closed, active kinase conformation which can be induced by RAS-dependent activation of RAF or by the binding of type I and I½ RAF inhibitors. Binding of type I or I½ RAF inhibitors to one dimer partner reduces the binding affinity of the other, thereby leaving a single dimer partner uninhibited and able to activate MEK. To overcome this paradox two classes of drug are currently under development; type II pan-RAF inhibitors that induce RAF dimer formation but bind both dimer partners thus allowing effective inhibition of both wild-type RAF dimer partners and monomeric active class I mutant RAF, and the recently developed "paradox breakers" which interrupt BRAF dimerisation through disruption of the αC-helix. Here we review the regulation of RAF proteins, including RAF dimers, and the progress towards effective targeting of the wild-type RAF proteins.
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Affiliation(s)
- Frazer A. Cook
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, U.K
| | - Simon J. Cook
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, U.K
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21
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KRAS interaction with RAF1 RAS-binding domain and cysteine-rich domain provides insights into RAS-mediated RAF activation. Nat Commun 2021; 12:1176. [PMID: 33608534 PMCID: PMC7895934 DOI: 10.1038/s41467-021-21422-x] [Citation(s) in RCA: 103] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 01/26/2021] [Indexed: 12/12/2022] Open
Abstract
The first step of RAF activation involves binding to active RAS, resulting in the recruitment of RAF to the plasma membrane. To understand the molecular details of RAS-RAF interaction, we present crystal structures of wild-type and oncogenic mutants of KRAS complexed with the RAS-binding domain (RBD) and the membrane-interacting cysteine-rich domain (CRD) from the N-terminal regulatory region of RAF1. Our structures reveal that RBD and CRD interact with each other to form one structural entity in which both RBD and CRD interact extensively with KRAS. Mutations at the KRAS-CRD interface result in a significant reduction in RAF1 activation despite only a modest decrease in binding affinity. Combining our structures and published data, we provide a model of RAS-RAF complexation at the membrane, and molecular insights into RAS-RAF interaction during the process of RAS-mediated RAF activation. The molecular details of the RAS-RAF interaction are still not fully understood. Here, the authors present crystal structures of wild-type and mutant KRAS in complex with the RAS-binding and membrane-interacting cysteine-rich domains of RAF1, and propose a model of the membrane-bound RAS-RAF complex.
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22
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Travers T, López CA, Agamasu C, Hettige JJ, Messing S, García AE, Stephen AG, Gnanakaran S. Anionic Lipids Impact RAS-Binding Site Accessibility and Membrane Binding Affinity of CRAF RBD-CRD. Biophys J 2020; 119:525-538. [PMID: 32649863 PMCID: PMC7399501 DOI: 10.1016/j.bpj.2020.06.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 06/12/2020] [Accepted: 06/18/2020] [Indexed: 11/25/2022] Open
Abstract
CRAF activation requires binding to membrane-anchored and active GTP-bound RAS. Whereas its RAS-binding domain (RBD) contains the main binding interface to the RAS G domain, its cysteine-rich domain (CRD) is responsible for association to anionic lipid-rich membranes. Both RAF domains are connected by a short linker, and it remains unclear if the two domains act independently or if one domain can impact the function of the other. Here, we used a combination of coarse-grained and all-atom molecular dynamics simulations of a CRAF RBD-CRD construct to investigate the dynamics of the RBD when it is tethered to CRD that is anchored to a POPC:POPS model membrane. First, we show that the RBD positioning is very dynamic with a preferential localization near the membrane surface. Next, we show that membrane-localized RBD has its RAS-binding interface mostly inaccessible because of its proximity to the membrane. Several positively charged residues in this interface were identified from simulations as important for driving RBD association to the membrane. Surface plasmon resonance (SPR) measurements confirmed that mutations of these RBD residues reduced the liposome partitioning of RBD-CRD. Last, simulations indicated that the presence of RBD near the membrane led to a local enrichment of anionic lipids that could potentially enhance the membrane affinity of the entire RBD-CRD construct. This was supported by SPR measurements that showed stronger liposome partitioning of RBD-CRD relative to CRD alone. These findings thus suggest that the RBD and CRD have synergistic effects on their membrane dynamics, with CRD bringing RBD closer to the membrane that impacts its accessibility to RAS and with RBD causing local anionic lipid enrichment that enhances the overall affinity between the membrane and RBD-CRD. These mechanisms have potential implications on the order of events of the interactions between RAS and CRAF at the membrane.
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Affiliation(s)
- Timothy Travers
- Theoretical Biology and Biophysics Group, Los Alamos, New Mexico; Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Cesar A López
- Theoretical Biology and Biophysics Group, Los Alamos, New Mexico
| | - Constance Agamasu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Reseach, Inc., Frederick, Maryland
| | | | - Simon Messing
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Reseach, Inc., Frederick, Maryland
| | - Angel E García
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Reseach, Inc., Frederick, Maryland
| | - S Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos, New Mexico.
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23
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Analysis of RAS protein interactions in living cells reveals a mechanism for pan-RAS depletion by membrane-targeted RAS binders. Proc Natl Acad Sci U S A 2020; 117:12121-12130. [PMID: 32424096 DOI: 10.1073/pnas.2000848117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
HRAS, NRAS, and KRAS4A/KRAS4B comprise the RAS family of small GTPases that regulate signaling pathways controlling cell proliferation, differentiation, and survival. RAS pathway abnormalities cause developmental disorders and cancers. We found that KRAS4B colocalizes on the cell membrane with other RAS isoforms and a subset of prenylated small GTPase family members using a live-cell quantitative split luciferase complementation assay. RAS protein coclustering is mainly mediated by membrane association-facilitated interactions (MAFIs). Using the RAS-RBD (CRAF RAS binding domain) interaction as a model system, we showed that MAFI alone is not sufficient to induce RBD-mediated RAS inhibition. Surprisingly, we discovered that high-affinity membrane-targeted RAS binding proteins inhibit RAS activity and deplete RAS proteins through an autophagosome-lysosome-mediated degradation pathway. Our results provide a mechanism for regulating RAS activity and protein levels, a more detailed understanding of which should lead to therapeutic strategies for inhibiting and depleting oncogenic RAS proteins.
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24
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Multivalent assembly of KRAS with the RAS-binding and cysteine-rich domains of CRAF on the membrane. Proc Natl Acad Sci U S A 2020; 117:12101-12108. [PMID: 32414921 DOI: 10.1073/pnas.1914076117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Membrane anchoring of farnesylated KRAS is critical for activation of RAF kinases, yet our understanding of how these proteins interact on the membrane is limited to isolated domains. The RAS-binding domain (RBD) and cysteine-rich domain (CRD) of RAF engage KRAS and the plasma membrane, unleashing the kinase domain from autoinhibition. Due to experimental challenges, structural insight into this tripartite KRAS:RBD-CRD:membrane complex has relied on molecular dynamics simulations. Here, we report NMR studies of the KRAS:CRAF RBD-CRD complex. We found that the nucleotide-dependent KRAS-RBD interaction results in transient electrostatic interactions between KRAS and CRD, and we mapped the membrane interfaces of the CRD, RBD-CRD, and the KRAS:RBD-CRD complex. RBD-CRD exhibits dynamic interactions with the membrane through the canonical CRD lipid-binding site (CRD β7-8), as well as an alternative interface comprising β6 and the C terminus of CRD and β2 of RBD. Upon complex formation with KRAS, two distinct states were observed by NMR: State A was stabilized by membrane association of CRD β7-8 and KRAS α4-α5 while state B involved the C terminus of CRD, β3-5 of RBD, and part of KRAS α5. Notably, α4-α5, which has been proposed to mediate KRAS dimerization, is accessible only in state B. A cancer-associated mutation on the state B membrane interface of CRAF RBD (E125K) stabilized state B and enhanced kinase activity and cellular MAPK signaling. These studies revealed a dynamic picture of the assembly of the KRAS-CRAF complex via multivalent and dynamic interactions between KRAS, CRAF RBD-CRD, and the membrane.
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25
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Nussinov R, Jang H, Zhang M, Tsai CJ, Sablina AA. The Mystery of Rap1 Suppression of Oncogenic Ras. Trends Cancer 2020; 6:369-379. [PMID: 32249186 PMCID: PMC7211489 DOI: 10.1016/j.trecan.2020.02.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 12/11/2022]
Abstract
Decades ago, Rap1, a small GTPase very similar to Ras, was observed to suppress oncogenic Ras phenotype, reverting its transformation. The proposed reason, persisting since, has been competition between Ras and Rap1 for a common target. Yet, none was found. There was also Rap1's puzzling suppression of Raf-1 versus activation of BRAF. Reemerging interest in Rap1 envisages capturing its Ras suppression action by inhibitors. Here, we review the literature and resolve the enigma. In vivo oncogenic Ras exists in isoform-distinct nanoclusters. The presence of Rap1 within the nanoclusters reduces the number of the clustered oncogenic Ras molecules, thus suppressing Raf-1 activation and mitogen-activated protein kinase (MAPK) signaling. Nanoclustering suggests that Rap1 suppression is Ras isoform dependent. Altogether, a potent Rap1-like inhibitor appears unlikely.
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Affiliation(s)
- Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA; Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Mingzhen Zhang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Chung-Jung Tsai
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Anna A Sablina
- VIB Center for the Biology of Disease and KU Leuven Department of Oncology, Leuven Cancer Institute, Leuven, Belgium
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26
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Zhang Z, Shokat KM. Bifunctional Small-Molecule Ligands of K-Ras Induce Its Association with Immunophilin Proteins. Angew Chem Int Ed Engl 2019; 58:16314-16319. [PMID: 31557383 PMCID: PMC6980260 DOI: 10.1002/anie.201910124] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Indexed: 12/20/2022]
Abstract
Here we report the design, synthesis, and characterization of bifunctional chemical ligands that induce the association of Ras with ubiquitously expressed immunophilin proteins such as FKBP12 and cyclophilin A. We show this approach is applicable to two distinct Ras ligand scaffolds, and that both the identity of the immunophilin ligand and the linker chemistry affect compound efficacy in biochemical and cellular contexts. These ligands bind to Ras in an immunophilin-dependent fashion and mediate the formation of tripartite complexes of Ras, immunophilin, and the ligand. The recruitment of cyclophilin A to GTP-bound Ras blocks its interaction with B-Raf in biochemical assays. Our study demonstrates the feasibility of ligand-induced association of Ras with intracellular proteins and suggests it as a promising therapeutic strategy for Ras-driven cancers.
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Affiliation(s)
- Ziyang Zhang
- Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, 600 16th Street, San Francisco, CA, 94143, USA
| | - Kevan M Shokat
- Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, 600 16th Street, San Francisco, CA, 94143, USA
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27
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Zhang Z, Shokat KM. Bifunctional Small‐Molecule Ligands of K‐Ras Induce Its Association with Immunophilin Proteins. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201910124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Ziyang Zhang
- Cellular and Molecular PharmacologyHoward Hughes Medical InstituteUniversity of California, San Francisco 600 16th Street San Francisco CA 94143 USA
| | - Kevan M. Shokat
- Cellular and Molecular PharmacologyHoward Hughes Medical InstituteUniversity of California, San Francisco 600 16th Street San Francisco CA 94143 USA
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28
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Boned Del Río I, Young LC, Sari S, Jones GG, Ringham-Terry B, Hartig N, Rejnowicz E, Lei W, Bhamra A, Surinova S, Rodriguez-Viciana P. SHOC2 complex-driven RAF dimerization selectively contributes to ERK pathway dynamics. Proc Natl Acad Sci U S A 2019; 116:13330-13339. [PMID: 31213532 PMCID: PMC6613145 DOI: 10.1073/pnas.1902658116] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Despite the crucial role of RAF kinases in cell signaling and disease, we still lack a complete understanding of their regulation. Heterodimerization of RAF kinases as well as dephosphorylation of a conserved "S259" inhibitory site are important steps for RAF activation but the precise mechanisms and dynamics remain unclear. A ternary complex comprised of SHOC2, MRAS, and PP1 (SHOC2 complex) functions as a RAF S259 holophosphatase and gain-of-function mutations in SHOC2, MRAS, and PP1 that promote complex formation are found in Noonan syndrome. Here we show that SHOC2 complex-mediated S259 RAF dephosphorylation is critically required for growth factor-induced RAF heterodimerization as well as for MEK dissociation from BRAF. We also uncover SHOC2-independent mechanisms of RAF and ERK pathway activation that rely on N-region phosphorylation of CRAF. In DLD-1 cells stimulated with EGF, SHOC2 function is essential for a rapid transient phase of ERK activation, but is not required for a slow, sustained phase that is instead driven by palmitoylated H/N-RAS proteins and CRAF. Whereas redundant SHOC2-dependent and -independent mechanisms of RAF and ERK activation make SHOC2 dispensable for proliferation in 2D, KRAS mutant cells preferentially rely on SHOC2 for ERK signaling under anchorage-independent conditions. Our study highlights a context-dependent contribution of SHOC2 to ERK pathway dynamics that is preferentially engaged by KRAS oncogenic signaling and provides a biochemical framework for selective ERK pathway inhibition by targeting the SHOC2 holophosphatase.
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Affiliation(s)
- Isabel Boned Del Río
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms
| | - Lucy C Young
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms
| | - Sibel Sari
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms
| | - Greg G Jones
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms
| | - Benjamin Ringham-Terry
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms
| | - Nicole Hartig
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms
| | - Ewa Rejnowicz
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms
| | - Winnie Lei
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms
| | - Amandeep Bhamra
- Proteomics Research Core Facility, University College London Cancer Institute, WC1E 6DD London, United Kingdom
| | - Silvia Surinova
- Proteomics Research Core Facility, University College London Cancer Institute, WC1E 6DD London, United Kingdom
| | - Pablo Rodriguez-Viciana
- University College London Cancer Institute, University College London, WC1E 6DD London, United Kingdoms;
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29
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Three distinct regions of cRaf kinase domain interact with membrane. Sci Rep 2019; 9:2057. [PMID: 30765804 PMCID: PMC6375958 DOI: 10.1038/s41598-019-38770-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/19/2018] [Indexed: 12/18/2022] Open
Abstract
Raf kinases are downstream effectors of small GTPase Ras. Mutations in Ras and Raf are associated with a variety of cancers and genetic disorders. Of the three Raf isoforms, cRaf is most frequently involved in tumor initiation by Ras. Cytosolic Raf is auto-inhibited and becomes active upon recruitment to the plasma membrane. Since the catalytic domain of Raf is its kinase domain, we ask the following: does the kinase domain of Raf has potential to interact with membrane and if yes, what role does the membrane interaction play? We present a model of cRaf kinase domain in complex with a heterogeneous membrane bilayer using atomistic molecular dynamics simulation. We show that the kinase domain of cRaf has three distinct membrane-interacting regions: a polybasic motif (R.RKTR) from the regulatory αC-helix, an aromatic/hydrophobic cluster from the N-terminal acidic region (NtA) and positively charged/aromatic cluster from the activation segment (AS). We show that residues from these regions form an extended membrane-interacting surface that resembles the membrane-interacting residues from known membrane-binding domains. Activating phosphorylatable regions (NtA and AS), make direct contact with the membrane whereas R.RKTR forms specific multivalent salt bridges with PA. PA lipids dwell for longer times around the R.RKTR motif. Our results suggest that membrane interaction of monomeric cRaf kinase domain likely orchestrates the Raf activation process and modulates its function. We show that R.RKTR is a hotspot that interacts with membrane when cRaf is monomeric and becomes part of the interface upon Raf dimerization. We propose that in terms of utilizing a specific hotspot to form membrane interaction and dimer formation, both Raf and its upstream binding partner KRas, are similar.
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30
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Structural snapshots of RAF kinase interactions. Biochem Soc Trans 2018; 46:1393-1406. [PMID: 30381334 DOI: 10.1042/bst20170528] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 07/25/2018] [Accepted: 07/30/2018] [Indexed: 02/07/2023]
Abstract
RAF (rapidly accelerated fibrosarcoma) Ser/Thr kinases (ARAF, BRAF, and CRAF) link the RAS (rat sarcoma) protein family with the MAPK (mitogen-activated protein kinase) pathway and control cell growth, differentiation, development, aging, and tumorigenesis. Their activity is specifically modulated by protein-protein interactions, post-translational modifications, and conformational changes in specific spatiotemporal patterns via various upstream regulators, including the kinases, phosphatase, GTPases, and scaffold and modulator proteins. Dephosphorylation of Ser-259 (CRAF numbering) and dissociation of 14-3-3 release the RAF regulatory domains RAS-binding domain and cysteine-rich domain for interaction with RAS-GTP and membrane lipids. This, in turn, results in RAF phosphorylation at Ser-621 and 14-3-3 reassociation, followed by its dimerization and ultimately substrate binding and phosphorylation. This review focuses on structural understanding of how distinct binding partners trigger a cascade of molecular events that induces RAF kinase activation.
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31
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Luhtala N, Hunter T. Failure to detect functional transfer of active K-Ras protein from extracellular vesicles into recipient cells in culture. PLoS One 2018; 13:e0203290. [PMID: 30192821 PMCID: PMC6128481 DOI: 10.1371/journal.pone.0203290] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 08/17/2018] [Indexed: 12/14/2022] Open
Abstract
Exosomes, extracellular nanovesicles that carry nucleic acids, lipids, and proteins, have been the subject of several studies to assess their ability to transfer functional cargoes to cells. We recently characterized extracellular nanovesicles released from glioblastoma cells that carry active Ras in complex with proteins regulating exosome biogenesis. Here, we investigated whether a functional transfer of Ras from exosomes to other cells can initiate intercellular signaling. We observed that treatment of serum-starved, cultured glioblastoma cells with exogenous glioblastoma exosomes caused a significant increase in cellular viability over time. Moreover, we detected fluorescent signal transfer from lipophilic dye-labeled exogenous glioblastoma exosomes into cultured glioblastoma cells. To probe possible signaling from cell-to-cell, we utilized bimolecular luciferase complementation to examine the ability of K-Ras in exosomes to interact with the Raf-Ras Binding domain (Raf-RBD) expressed in a recipient cell line. Although the K-Ras/Raf-RBD interaction was readily detectable upon co-expression in a single cell line, or following lysis of co-cultured cell lines separately expressing K-Ras and RBD, bearing in mind the limitations of our assay, we were unable to detect the interaction in the intact, co-cultured cell lines or upon treatment of the Raf-RBD-expressing cells with exosomes containing K-Ras. Furthermore, HA-Tag-BFP fused to the K-Ras hypervariable region and CAAX sequence failed to be transferred at significant levels from extracellular vesicles into recipient cells, but remained detectable in the cell supernatants even after 96 hours of culture of naïve cells with extracellular vesicles. We conclude that if transfer of functional K-Ras from extracellular vesicles into the cytoplasm of recipient cells occurs, it must do so at an extremely low efficiency and therefore is unlikely to initiate Ras-ERK MAP kinase pathway signaling. These results suggest that studies claiming functional transfer of protein cargoes from exosomes should be interpreted with caution.
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Affiliation(s)
- Natalie Luhtala
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States of America
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States of America
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32
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Travers T, López CA, Van QN, Neale C, Tonelli M, Stephen AG, Gnanakaran S. Molecular recognition of RAS/RAF complex at the membrane: Role of RAF cysteine-rich domain. Sci Rep 2018; 8:8461. [PMID: 29855542 PMCID: PMC5981303 DOI: 10.1038/s41598-018-26832-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/18/2018] [Indexed: 01/14/2023] Open
Abstract
Activation of RAF kinase involves the association of its RAS-binding domain (RBD) and cysteine-rich domain (CRD) with membrane-anchored RAS. However, the overall architecture of the RAS/RBD/CRD ternary complex and the orientations of its constituent domains at the membrane remain unclear. Here, we have combined all-atom and coarse-grained molecular dynamics (MD) simulations with experimental data to construct and validate a model of membrane-anchored CRD, and used this as a basis to explore models of membrane-anchored RAS/RBD/CRD complex. First, simulations of the CRD revealed that it anchors to the membrane via insertion of its two hydrophobic loops, which is consistent with our NMR measurements of CRD bound to nanodiscs. Simulations of the CRD in the context of membrane-anchored RAS/RBD then show how CRD association with either RAS or RBD could play an unexpected role in guiding the membrane orientations of RAS/RBD. This finding has implications for the formation of RAS-RAS dimers, as different membrane orientations of RAS expose distinct putative dimerization interfaces.
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Affiliation(s)
- Timothy Travers
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States
| | - Cesar A López
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States
| | - Que N Van
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland, 21702, United States
| | - Chris Neale
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States
| | - Marco Tonelli
- National Magnetic Resource Facility at Madison, Biochemistry Department, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States
| | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland, 21702, United States
| | - S Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States.
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33
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Li ZL, Prakash P, Buck M. A "Tug of War" Maintains a Dynamic Protein-Membrane Complex: Molecular Dynamics Simulations of C-Raf RBD-CRD Bound to K-Ras4B at an Anionic Membrane. ACS CENTRAL SCIENCE 2018; 4:298-305. [PMID: 29532030 PMCID: PMC5832993 DOI: 10.1021/acscentsci.7b00593] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Indexed: 06/11/2023]
Abstract
Association of Raf kinase with activated Ras triggers downstream signaling cascades toward regulating transcription in the cells' nucleus. Dysregulation of Ras-Raf signaling stimulates cancers. We investigate the C-Raf RBD and CRD regions when bound to oncogenic K-Ras4B at the membrane. All-atom molecular dynamics simulations suggest that the membrane plays an integral role in regulating the configurational ensemble of the complex. Remarkably, the complex samples a few states dynamically, reflecting a competition between C-Raf CRD- and K-Ras4B- membrane interactions. This competition arises because the interaction between the RBD and K-Ras is strong while the linker between the RBD and CRD is short. Such a mechanism maintains a modest binding for the overall complex at the membrane and is expected to facilitate fast signaling processes. Competition of protein-membrane contacts is likely a common mechanism for other multiprotein complexes, if not multidomain proteins at membranes.
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Affiliation(s)
- Zhen-Lu Li
- Department of Physiology and Biophysics, Department of Neurosciences, Department of Pharmacology, Case Comprehensive
Cancer Center and Center for Proteomics and Bioinformatics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Priyanka Prakash
- Department
of Integrative Biology and Pharmacology, University of Texas Health Science at Houston, Houston, Texas 77225, United States
| | - Matthias Buck
- Department of Physiology and Biophysics, Department of Neurosciences, Department of Pharmacology, Case Comprehensive
Cancer Center and Center for Proteomics and Bioinformatics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
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34
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Lim CS, Wen C, Sheng Y, Wang G, Zhou Z, Wang S, Zhang H, Ye A, Zhu JJ. Piconewton-Scale Analysis of Ras-BRaf Signal Transduction with Single-Molecule Force Spectroscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:10.1002/smll.201701972. [PMID: 28809097 PMCID: PMC6272124 DOI: 10.1002/smll.201701972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/10/2017] [Indexed: 06/07/2023]
Abstract
Intermolecular interactions dominate the behavior of signal transduction in various physiological and pathological cell processes, yet assessing these interactions remains a challenging task. Here, this study reports a single-molecule force spectroscopic method that enables functional delineation of two interaction sites (≈35 pN and ≈90 pN) between signaling effectors Ras and BRaf in the canonical mitogen-activated protein kinase (MAPK) pathway. This analysis reveals mutations on BRaf at Q257 and A246, two sites frequently linked to cardio-faciocutaneous syndrome, result in ≈10-30 pN alterations in RasBRaf intermolecular binding force. The magnitude of changes in RasBRaf binding force correlates with the size of alterations in protein affinity and in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-sensitive glutamate receptor (-R)-mediated synaptic transmission in neurons expressing replacement BRaf mutants, and predicts the extent of learning impairments in animals expressing replacement BRaf mutants. These results establish single-molecule force spectroscopy as an effective platform for evaluating the piconewton-level interaction of signaling molecules and predicting the behavior outcome of signal transduction.
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Affiliation(s)
- Chae-Seok Lim
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Cheng Wen
- School of Electronic Engineering and Computer Science, Peking University, Beijing, 100871, China
| | - Yanghui Sheng
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Undergraduate Class of 2011, Yuanpei Honors College, Peking University, Beijing, 100871, China
- Institute of Molecular Medicine, Peking University, Beijing, 100871, China
- School of Life Sciences, Peking University, Beijing, 100871, China
| | - Guangfu Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Zhuan Zhou
- Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Shiqiang Wang
- School of Life Sciences, Peking University, Beijing, 100871, China
| | - Huaye Zhang
- Department of Microbiology and Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Anpei Ye
- School of Electronic Engineering and Computer Science, Peking University, Beijing, 100871, China
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Institute of Neuroscience, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6525, EN, Nijmegen, Netherlands
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Jinesh GG, Kamat AM. The Blebbishield Emergency Program Overrides Chromosomal Instability and Phagocytosis Checkpoints in Cancer Stem Cells. Cancer Res 2017; 77:6144-6156. [PMID: 28855211 DOI: 10.1158/0008-5472.can-17-0522] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 06/13/2017] [Accepted: 08/22/2017] [Indexed: 11/16/2022]
Abstract
Genomic instability and immune evasion are hallmarks of cancer. Apoptotic cancer stem cells can evade cell death by undergoing cellular transformation by constructing "blebbishields" from apoptotic bodies. In this study, we report a novel linkage between genomic instability and phagocytosis evasion that is coordinated by the blebbishield emergency program. Blebbishield emergency program evaded genomic instability checkpoint, expressed genomic instability-associated genes at distinct phases of cellular transformation, exhibited chromosomal instability, and promoted increase in nuclear size. Blebbishields fused with immune cells to evade phagocytosis, and the resultant hybrid cells exhibited increased migration, tumorigenesis, metastasis, red blood cell recruitment to tumors, and induced hepatosplenomegaly with signatures of genomic instability, blebbishield emergency program, and phagocytosis evasion to offer poor prognosis. Overall, our data demonstrate that the blebbishield emergency program drives evasion of chromosomal instability and phagocytosis checkpoints by apoptotic cancer stem cells. Cancer Res; 77(22); 6144-56. ©2017 AACR.
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Affiliation(s)
- Goodwin G Jinesh
- Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
| | - Ashish M Kamat
- Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
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78495111110.3390/cancers9050052" />
Abstract
The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is commonly upregulated in cancers such as in non-small-cell lung cancer, metastatic colorectal cancer, glioblastoma, head and neck cancer, pancreatic cancer, and breast cancer. Various mechanisms mediate the upregulation of EGFR activity, including common mutations and truncations to its extracellular domain, such as in the EGFRvIII truncations, as well as to its kinase domain, such as the L858R and T790M mutations, or the exon 19 truncation. These EGFR aberrations over-activate downstream pro-oncogenic signaling pathways, including the RAS-RAF-MEK-ERK MAPK and AKT-PI3K-mTOR pathways. These pathways then activate many biological outputs that are beneficial to cancer cell proliferation, including their chronic initiation and progression through the cell cycle. Here, we review the molecular mechanisms that regulate EGFR signal transduction, including the EGFR structure and its mutations, ligand binding and EGFR dimerization, as well as the signaling pathways that lead to G1 cell cycle progression. We focus on the induction of CYCLIN D expression, CDK4/6 activation, and the repression of cyclin-dependent kinase inhibitor proteins (CDKi) by EGFR signaling pathways. We also discuss the successes and challenges of EGFR-targeted therapies, and the potential for their use in combination with CDK4/6 inhibitors.
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Wee P, Wang Z. Epidermal Growth Factor Receptor Cell Proliferation Signaling Pathways. Cancers (Basel) 2017; 9:cancers9050052. [PMID: 28513565 PMCID: PMC5447962 DOI: 10.3390/cancers9050052] [Citation(s) in RCA: 994] [Impact Index Per Article: 142.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/10/2017] [Accepted: 05/10/2017] [Indexed: 12/12/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is commonly upregulated in cancers such as in non-small-cell lung cancer, metastatic colorectal cancer, glioblastoma, head and neck cancer, pancreatic cancer, and breast cancer. Various mechanisms mediate the upregulation of EGFR activity, including common mutations and truncations to its extracellular domain, such as in the EGFRvIII truncations, as well as to its kinase domain, such as the L858R and T790M mutations, or the exon 19 truncation. These EGFR aberrations over-activate downstream pro-oncogenic signaling pathways, including the RAS-RAF-MEK-ERK MAPK and AKT-PI3K-mTOR pathways. These pathways then activate many biological outputs that are beneficial to cancer cell proliferation, including their chronic initiation and progression through the cell cycle. Here, we review the molecular mechanisms that regulate EGFR signal transduction, including the EGFR structure and its mutations, ligand binding and EGFR dimerization, as well as the signaling pathways that lead to G1 cell cycle progression. We focus on the induction of CYCLIN D expression, CDK4/6 activation, and the repression of cyclin-dependent kinase inhibitor proteins (CDKi) by EGFR signaling pathways. We also discuss the successes and challenges of EGFR-targeted therapies, and the potential for their use in combination with CDK4/6 inhibitors.
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Affiliation(s)
- Ping Wee
- Department of Medical Genetics and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Zhixiang Wang
- Department of Medical Genetics and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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Taoka R, Jinesh GG, Xue W, Safe S, Kamat AM. CF 3DODA-Me induces apoptosis, degrades Sp1, and blocks the transformation phase of the blebbishield emergency program. Apoptosis 2017; 22:719-729. [PMID: 28283889 DOI: 10.1007/s10495-017-1359-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cancer stem cells are capable of undergoing cellular transformation after commencement of apoptosis through the blebbishield emergency program in a VEGF-VEGFR2-dependent manner. Development of therapeutics targeting the blebbishield emergency program would thus be important in cancer therapy. Specificity protein 1 (Sp1) orchestrates the transcription of both VEGF and VEGFR2; hence, Sp1 could act as a therapeutic target. Here, we demonstrate that CF3DODA-Me induced apoptosis, degraded Sp1, inhibited the expression of multiple drivers of the blebbishield emergency program such as VEGFR2, p70S6K, and N-Myc through activation of caspase-3, inhibited reactive oxygen species; and inhibited K-Ras activation to abolish transformation from blebbishields as well as transformation in soft agar. These findings confirm CF3DODA-Me as a potential therapeutic candidate that can induce apoptosis and block transformation from blebbishields.
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Affiliation(s)
- Rikiya Taoka
- Department of Urology, Unit 1373, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX, 77030, USA
| | - Goodwin G Jinesh
- Department of Urology, Unit 1373, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX, 77030, USA.
| | - Wenrui Xue
- Department of Urology, Unit 1373, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX, 77030, USA
| | - Stephen Safe
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
| | - Ashish M Kamat
- Department of Urology, Unit 1373, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX, 77030, USA.
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Luhtala N, Aslanian A, Yates JR, Hunter T. Secreted Glioblastoma Nanovesicles Contain Intracellular Signaling Proteins and Active Ras Incorporated in a Farnesylation-dependent Manner. J Biol Chem 2016; 292:611-628. [PMID: 27909058 DOI: 10.1074/jbc.m116.747618] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 11/11/2016] [Indexed: 12/21/2022] Open
Abstract
Glioblastomas (GBMs) are malignant brain tumors with a median survival of less than 18 months. Redundancy of signaling pathways represented within GBMs contributes to their therapeutic resistance. Exosomes are extracellular nanovesicles released from cells and present in human biofluids that represent a possible biomarker of tumor signaling state that could aid in personalized treatment. Herein, we demonstrate that mouse GBM cell-derived extracellular nanovesicles resembling exosomes from an H-RasV12 myr-Akt mouse model for GBM are enriched for intracellular signaling cascade proteins (GO: 0007242) and Ras protein signal transduction (GO: 0007265), and contain active Ras. Active Ras isolated from human and mouse GBM extracellular nanovesicles lysates using the Ras-binding domain of Raf also coprecipitates with ESCRT (endosomal sorting complex required for transport)-associated exosome proteins Vps4a and Alix. Although we initially hypothesized a role for active Ras protein signaling in exosome biogenesis, we found that GTP binding of K-Ras was dispensable for its packaging within extracellular nanovesicles and for the release of Alix. By contrast, farnesylation of K-Ras was required for its packaging within extracellular nanovesicles, yet expressing a K-Ras farnesylation mutant did not decrease the number of nanovesicles or the amount of Alix protein released per cell. Overall, these results emphasize the primary importance of membrane association in packaging of extracellular nanovesicle factors and indicate that screening nanovesicles within human fluids could provide insight into tissue origin and the wiring of signaling proteins at membranes to predict onset and behavior of cancer and other diseases linked to deregulated membrane signaling states.
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Affiliation(s)
- Natalie Luhtala
- From the Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037 and
| | - Aaron Aslanian
- From the Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037 and.,the Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037
| | - John R Yates
- the Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037
| | - Tony Hunter
- From the Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037 and
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Jinesh GG, Molina JR, Huang L, Laing NM, Mills GB, Bar-Eli M, Kamat AM. Mitochondrial oligomers boost glycolysis in cancer stem cells to facilitate blebbishield-mediated transformation after apoptosis. Cell Death Discov 2016; 2:16003. [PMID: 27551498 PMCID: PMC4979437 DOI: 10.1038/cddiscovery.2016.3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 12/24/2015] [Indexed: 12/02/2022] Open
Abstract
Apoptosis culminates in secondary necrosis due to lack of ATP. Cancer stem cells form spheres after apoptosis by evoking the blebbishield emergency program. Hence, determining how blebbishields avoid secondary necrosis is crucial. Here we demonstrate that N-Myc and VEGFR2 control transformation from blebbishields, during which oligomers of K-Ras, p27, BAD, Bax, and Bak boost glycolysis to avoid secondary necrosis. Non-apoptotic cancer cells also utilize oligomers to boost glycolysis, which differentiates the glycolytic function of oligomers from their apoptotic action. Smac mimetic in combination with TNF-α or TRAIL but not in combination with FasL abrogates transformation from blebbishields by inducing secondary necrosis. Thus blebbishield-mediated transformation is dependent on glycolysis, and Smac mimetics represent potential candidates to abrogate the blebbishield emergency program.
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Affiliation(s)
- G G Jinesh
- Department of Urology, The University of Texas MD Anderson Cancer Center , Houston, TX, USA
| | - J R Molina
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center , Houston, TX, USA
| | - L Huang
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center , Houston, TX, USA
| | | | - G B Mills
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center , Houston, TX, USA
| | - M Bar-Eli
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center , Houston, TX, USA
| | - A M Kamat
- Department of Urology, The University of Texas MD Anderson Cancer Center , Houston, TX, USA
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p27kip1 controls H-Ras/MAPK activation and cell cycle entry via modulation of MT stability. Proc Natl Acad Sci U S A 2015; 112:13916-21. [PMID: 26512117 DOI: 10.1073/pnas.1508514112] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The cyclin-dependent kinase (CDK) inhibitor p27(kip1) is a critical regulator of the G1/S-phase transition of the cell cycle and also regulates microtubule (MT) stability. This latter function is exerted by modulating the activity of stathmin, an MT-destabilizing protein, and by direct binding to MTs. We recently demonstrated that increased proliferation in p27(kip1)-null mice is reverted by concomitant deletion of stathmin in p27(kip1)/stathmin double-KO mice, suggesting that a CDK-independent function of p27(kip1) contributes to the control of cell proliferation. Whether the regulation of MT stability by p27(kip1) impinges on signaling pathway activation and contributes to the decision to enter the cell cycle is largely unknown. Here, we report that faster cell cycle entry of p27(kip1)-null cells was impaired by the concomitant deletion of stathmin. Using gene expression profiling coupled with bioinformatic analyses, we show that p27(kip1) and stathmin conjunctly control activation of the MAPK pathway. From a molecular point of view, we observed that p27(kip1), by controlling MT stability, impinges on H-Ras trafficking and ubiquitination levels, eventually restraining its full activation. Our study identifies a regulatory axis controlling the G1/S-phase transition, relying on the regulation of MT stability by p27(kip1) and finely controlling the spatiotemporal activation of the Ras-MAPK signaling pathway.
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Cromm PM, Spiegel J, Grossmann TN, Waldmann H. Direkte Modulation von Aktivität und Funktion kleiner GTPasen. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201504357] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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43
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Cromm PM, Spiegel J, Grossmann TN, Waldmann H. Direct Modulation of Small GTPase Activity and Function. Angew Chem Int Ed Engl 2015; 54:13516-37. [DOI: 10.1002/anie.201504357] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 12/19/2022]
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Takahashi-Niki K, Kato-Ose I, Murata H, Maita H, Iguchi-Ariga SMM, Ariga H. Epidermal Growth Factor-dependent Activation of the Extracellular Signal-regulated Kinase Pathway by DJ-1 Protein through Its Direct Binding to c-Raf Protein. J Biol Chem 2015; 290:17838-17847. [PMID: 26048984 DOI: 10.1074/jbc.m115.666271] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Indexed: 11/06/2022] Open
Abstract
DJ-1 is an oncogene and also a causative gene for familial Parkinson disease. DJ-1 has various functions, and the oxidative status of cysteine at position 106 (Cys-106) is crucial for determination of the activation level of DJ-1. Although DJ-1 requires activated Ras for its oncogenic activity and although it activates the extracellular signal-regulated kinase (ERK) pathway, a cell growth pathway downstream of Ras, the precise mechanism underlying activation of the ERK pathway by DJ-1 is still not known. In this study, we found that DJ-1 directly bound to the kinase domain of c-Raf but not to Ras and that Cys-106 mutant DJ-1 bound to c-Raf more weakly than did wild-type DJ-1. Co-localization of DJ-1 with c-Raf in the cytoplasm was enhanced in epidermal growth factor (EGF)-treated cells. Knockdown of DJ-1 expression attenuated the phosphorylation level of c-Raf in EGF-treated cells, resulting in reduced activation of MEK and ERK1/2. Although EGF-treated DJ-1 knock-out cells also showed attenuated c-Raf activation, reintroduction of wild-type DJ-1, but not C106S DJ-1, into DJ-1 knock-out cells restored c-Raf activation in a DJ-1 binding activity in a c-Raf-dependent manner. DJ-1 was not responsible for activation of c-Raf in phorbol myristate acetate-treated cells. Furthermore, DJ-1 stimulated self-phosphorylation activity of c-Raf in vitro, but DJ-1 was not a target for Raf kinase. Oxidation of Cys-106 in DJ-1 was not affected by EGF treatment. These findings showed that DJ-1 is a positive regulator of the EGF/Ras/ERK pathway through targeting c-Raf.
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Affiliation(s)
| | - Izumi Kato-Ose
- Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812
| | - Hiroaki Murata
- Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812
| | - Hiroshi Maita
- Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812
| | | | - Hiroyoshi Ariga
- Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812.
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Leiser D, Medová M, Mikami K, Nisa L, Stroka D, Blaukat A, Bladt F, Aebersold DM, Zimmer Y. KRAS and HRAS mutations confer resistance to MET targeting in preclinical models of MET-expressing tumor cells. Mol Oncol 2015; 9:1434-46. [PMID: 25933688 DOI: 10.1016/j.molonc.2015.04.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 03/23/2015] [Accepted: 04/05/2015] [Indexed: 12/16/2022] Open
Abstract
The MET receptor tyrosine kinase is often deregulated in human cancers and several MET inhibitors are evaluated in clinical trials. Similarly to EGFR, MET signals through the RAS-RAF-ERK/MAPK pathway which plays key roles in cell proliferation and survival. Mutations of genes encoding for RAS proteins, particularly in KRAS, are commonly found in various tumors and are associated with constitutive activation of the MAPK pathway. It was shown for EGFR, that KRAS mutations render upstream EGFR inhibition ineffective in EGFR-positive colorectal cancers. Currently, there are no clinical studies evaluating MET inhibition impairment due to RAS mutations. To test the impact of RAS mutations on MET targeting, we generated tumor cells responsive to the MET inhibitor EMD1214063 that express KRAS G12V, G12D, G13D and HRAS G12V variants. We demonstrate that these MAPK-activating RAS mutations differentially interfere with MET-mediated biological effects of MET inhibition. We report increased residual ERK1/2 phosphorylation indicating that the downstream pathway remains active in presence of MET inhibition. Consequently, RAS variants counteracted MET inhibition-induced morphological changes as well as anti-proliferative and anchorage-independent growth effects. The effect of RAS mutants was reversed when MET inhibition was combined with MEK inhibitors AZD6244 and UO126. In an in vivo mouse xenograft model, MET-driven tumors harboring mutated RAS displayed resistance to MET inhibition. Taken together, our results demonstrate for the first time in details the role of KRAS and HRAS mutations in resistance to MET inhibition and suggest targeting both MET and MEK as an effective strategy when both oncogenic drivers are expressed.
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Affiliation(s)
- Dominic Leiser
- Department of Radiation Oncology, Department of Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Michaela Medová
- Department of Radiation Oncology, Department of Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Kei Mikami
- Department of Radiation Oncology, Department of Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Lluís Nisa
- Department of Radiation Oncology, Department of Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Deborah Stroka
- Department of Visceral Surgery, Department of Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Andree Blaukat
- Merck Serono an Affiliate of Merck Serono Research & Development, Merck KGaA, 64271 Darmstadt, Germany
| | - Friedhelm Bladt
- Merck Serono an Affiliate of Merck Serono Research & Development, Merck KGaA, 64271 Darmstadt, Germany
| | - Daniel M Aebersold
- Department of Radiation Oncology, Department of Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Yitzhak Zimmer
- Department of Radiation Oncology, Department of Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Switzerland.
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Zhang CC, Li R, Jiang H, Lin S, Rogalski JC, Liu K, Kast J. Development and application of a quantitative multiplexed small GTPase activity assay using targeted proteomics. J Proteome Res 2015; 14:967-76. [PMID: 25569337 DOI: 10.1021/pr501010v] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Small GTPases are a family of key signaling molecules that are ubiquitously expressed in various types of cells. Their activity is often analyzed by western blot, which is limited by its multiplexing capability, the quality of isoform-specific antibodies, and the accuracy of quantification. To overcome these issues, a quantitative multiplexed small GTPase activity assay has been developed. Using four different binding domains, this assay allows the binding of up to 12 active small GTPase isoforms simultaneously in a single experiment. To accurately quantify the closely related small GTPase isoforms, a targeted proteomic approach, i.e., selected/multiple reaction monitoring, was developed, and its functionality and reproducibility were validated. This assay was successfully applied to human platelets and revealed time-resolved coactivation of multiple small GTPase isoforms in response to agonists and differential activation of these isoforms in response to inhibitor treatment. This widely applicable approach can be used for signaling pathway studies and inhibitor screening in many cellular systems.
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Affiliation(s)
- Cheng-Cheng Zhang
- The Biomedical Research Centre, ∥The Centre for Blood Research, University of British Columbia , Vancouver, BC V6T 1Z3, Canada
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47
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Deb TB, Barndt RJ, Zuo AH, Sengupta S, Coticchia CM, Johnson MD. PTEN-mediated ERK1/2 inhibition and paradoxical cellular proliferation following Pnck overexpression. Cell Cycle 2014; 13:961-73. [PMID: 24552815 DOI: 10.4161/cc.27837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Pregnancy upregulated non-ubiquitous calmodulin kinase (Pnck), a novel calmodulin kinase, is significantly overexpressed in breast and renal cancers. We present evidence that at high cell density, overexpression of Pnck in HEK 293 cells inhibits serum-induced extracellular signal-regulated kinase (ERK1/ERK2) activation. ERK1/2 inhibition is calcium-dependent and Pnck kinase activity is required for ERK1/2 inhibition, since expression of a kinase-dead (K44A) and a catalytic loop phosphorylation mutant (T171A) Pnck protein is unable to inhibit ERK1/2 activity. Ras is constitutively active at high cell density, and Pnck does not alter Ras activation, suggesting that Pnck inhibition of ERK1/2 activity is independent of Ras activity. Pnck inhibition of serum-induced ERK1/2 activity is lost in cells in which phosphatase and tensin homolog (PTEN) is suppressed, suggesting that Pnck inhibition of ERK1/2 activity is mediated by PTEN. Overexpression of protein phosphatase-active but lipid phosphatase-dead PTEN protein inhibits ERK1/2 activity in control cells and enhances Pnck-mediated ERK1/2 inhibition, suggesting that Pnck increases availability of protein phosphatase active PTEN for ERK1/2 inhibition. Pnck is a stress-responsive kinase; however, serum-induced p38 MAP kinase activity is also downregulated by Pnck in a Pnck kinase- and PTEN-dependent manner, similar to ERK1/2 inhibition. Pnck overexpression increases proliferation, which is inhibited by PTEN knockdown, implying that PTEN acts as a paradoxical promoter of proliferation in ERK1/2 and p38 MAP kinase phosphorylation-inhibited, Pnck-overexpressing cells. Overall, these data reveal a novel function of Pnck in the regulation of ERK1/2 and p38 MAP kinase activity and cell proliferation, which is mediated by paradoxical PTEN functions. The possible biological implications of these data are discussed.
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Affiliation(s)
- Tushar B Deb
- Lombardi Comprehensive Cancer Center and Department of Oncology; Georgetown University Medical Center; Georgetown University; Washington, DC USA
| | - Robert J Barndt
- Lombardi Comprehensive Cancer Center and Department of Oncology; Georgetown University Medical Center; Georgetown University; Washington, DC USA
| | - Annie H Zuo
- Lombardi Comprehensive Cancer Center and Department of Oncology; Georgetown University Medical Center; Georgetown University; Washington, DC USA
| | - Surojeet Sengupta
- Lombardi Comprehensive Cancer Center and Department of Oncology; Georgetown University Medical Center; Georgetown University; Washington, DC USA
| | - Christine M Coticchia
- Lombardi Comprehensive Cancer Center and Department of Oncology; Georgetown University Medical Center; Georgetown University; Washington, DC USA
| | - Michael D Johnson
- Lombardi Comprehensive Cancer Center and Department of Oncology; Georgetown University Medical Center; Georgetown University; Washington, DC USA
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48
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Wen C, Ye A. Single-molecule force measurement via optical tweezers reveals different kinetic features of two BRaf mutants responsible for cardio-facial-cutaneous (CFC) syndrome. BIOMEDICAL OPTICS EXPRESS 2013; 4:2835-2845. [PMID: 24409384 PMCID: PMC3862169 DOI: 10.1364/boe.4.002835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/09/2013] [Accepted: 10/23/2013] [Indexed: 06/03/2023]
Abstract
BRaf (B- Rapid Accelerated Fibrosarcoma) protein is an important serine/threonine-protein kinase. Two domains on BRaf can independently bind its upstream kinase, Ras (Rat Sarcoma) protein. These are the Ras binding domain (RBD) and cysteine-rich-domain (CRD). Herein we use customized optical tweezers to compare the Ras binding process in two pathological mutants of BRaf responsible for CFC syndrome, abbreviated BRaf (A246P) and BRaf (Q257R). The two mutants differ in their kinetics of Ras-binding, though both bind Ras with similar increased overall affinity. BRaf (A246P) exhibits a slightly higher Ras/CRD unbinding force and a significantly higher Ras/RBD unbinding force versus the wild type. The contrary phenomenon is observed in the Q257R mutation. Simulations of the unstressed-off rate, koff (0), yield results in accordance with the changes revealed by the mean unbinding force. Our approach can be applied to rapidly assess other mutated proteins to deduce the effects of mutation on their kinetics compared to wild type proteins and to each other.
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Affiliation(s)
- Cheng Wen
- Key Laboratory for the Physics & Chemistry of Nano-devices, School of Electronic Engineering & Computer Science, Peking University, Beijing 100871,China
- School of Lifescience, Peking University, Beijing 100871, China
| | - Anpei Ye
- Key Laboratory for the Physics & Chemistry of Nano-devices, School of Electronic Engineering & Computer Science, Peking University, Beijing 100871,China
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49
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MEK-1 activates C-Raf through a Ras-independent mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:976-86. [PMID: 23360980 DOI: 10.1016/j.bbamcr.2013.01.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 12/29/2012] [Accepted: 01/15/2013] [Indexed: 12/16/2022]
Abstract
C-Raf is a member of the Ras-Raf-MEK-ERK mitogen-activated protein kinase (MAPK) signaling pathway that plays key roles in diverse physiological processes and is upregulated in many human cancers. C-Raf activation involves binding to Ras, increased phosphorylation and interactions with co-factors. Here, we describe a Ras-independent in vivo pathway for C-Raf activation by its downstream target MEK. Using (32)P-metabolic labeling and 2D-phosphopeptide mapping experiments, we show that MEK increases C-Raf phosphorylation by up-to 10-fold. This increase was associated with C-Raf kinase activation, matching the activity seen with growth factor stimulation. Consequently, coexpression of wildtype C-Raf and MEK was sufficient for full and constitutive activation of ERK. Notably, the ability of MEK to activate C-Raf was completely Ras independent, since mutants impaired in Ras binding that are irresponsive to growth factors or Ras were fully activated by MEK. The ability of MEK to activate C-Raf was only partially dependent on MEK kinase activity but required MEK binding to C-Raf, suggesting that the binding results in a conformational change that increases C-Raf susceptibility to phosphorylation and activation or in the stabilization of the phosphorylated-active form. These findings propose a novel Ras-independent mechanism for activating the C-Raf and the MAPK pathway without the need for mutations in the pathway. This mechanism could be of significance in pathological conditions or cancers overexpressing C-Raf and MEK or in conditions where C-Raf-MEK interaction is enhanced due to the down-regulation of RKIP and MST2.
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50
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Affiliation(s)
- Dhirendra Govender
- Division of Anatomical Pathology, University of Cape Town and National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa.
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