1
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Conformation-locking antibodies for the discovery and characterization of KRAS inhibitors. Nat Biotechnol 2022; 40:769-778. [PMID: 34992247 DOI: 10.1038/s41587-021-01126-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 10/07/2021] [Indexed: 11/08/2022]
Abstract
Small molecules that stabilize inactive protein conformations are an underutilized strategy for drugging dynamic or otherwise intractable proteins. To facilitate the discovery and characterization of such inhibitors, we created a screening platform to identify conformation-locking antibodies for molecular probes (CLAMPs) that distinguish and induce rare protein conformational states. Applying the approach to KRAS, we discovered CLAMPs that recognize the open conformation of KRASG12C stabilized by covalent inhibitors. One CLAMP enables the visualization of KRASG12C covalent modification in vivo and can be used to investigate response heterogeneity to KRASG12C inhibitors in patient tumors. A second CLAMP enhances the affinity of weak ligands binding to the KRASG12C switch II region (SWII) by stabilizing a specific conformation of KRASG12C, thereby enabling the discovery of such ligands that could serve as leads for the development of drugs in a high-throughput screen. We show that combining the complementary properties of antibodies and small molecules facilitates the study and drugging of dynamic proteins.
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2
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Kameda M, Mikawa T, Yokode M, Inagaki N, Kondoh H. Senescence research from historical theory to future clinical application. Geriatr Gerontol Int 2020; 21:125-130. [PMID: 33372374 DOI: 10.1111/ggi.14121] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/20/2020] [Accepted: 12/05/2020] [Indexed: 12/18/2022]
Abstract
Historically, the findings from cellular lifespan studies have greatly affected aging research. The discovery of replicative senescence by Hayflick developed into research on telomeres and telomerase, while stress-induced senescence became known as a telomere-independent event. Senescence-inducing signals comprise several tumor suppressors or cell cycle inhibitors, e.g., p53, cyclin-dependent kinase inhibitor p16 Ink4a and others. Stress-induced senescence serves as a physiological barrier to oncogenesis in vivo, while it activates senescence-associated secretary phenotype, inducing chronic inflammation. Thus, beside telomere length, p16, p53 and inflammatory cytokines have been utilized as biomarkers for cellular senescence. Telomere lengths in human leukocytes correlate well with events of aging-related lifestyle diseases, indicating the importance of cellular senescence in organismal aging. As such, the development of senescence research will have significant future clinical applications, e.g., senolysis. Geriatr Gerontol Int 2021; 21: 125-130.
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Affiliation(s)
- Masahiro Kameda
- Geriatric unit, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takumi Mikawa
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masayuki Yokode
- Geriatric unit, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroshi Kondoh
- Geriatric unit, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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3
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Mestach L, Polubothu S, Calder A, Denayer E, Gholam K, Legius E, Levtchenko E, Van Laethem A, Brems H, Kinsler VA, Morren MA. Keratinocytic epidermal nevi associated with localized fibro-osseous lesions without hypophosphatemia. Pediatr Dermatol 2020; 37:890-895. [PMID: 32662096 DOI: 10.1111/pde.14254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 05/07/2020] [Accepted: 05/30/2020] [Indexed: 11/28/2022]
Abstract
Keratinocytic epidermal nevi (KEN) are characterized clinically by permanent hyperkeratosis in the distribution of Blaschko's lines and histologically by hyperplasia of epidermal keratinocytes. KEN with underlying RAS mutations have been associated with hypophosphatemic rickets and dysplastic bone lesions described as congenital cutaneous skeletal hypophosphatemia syndrome. Here, we describe two patients with keratinocytic epidermal nevi, in one associated with a papular nevus spilus, who presented with distinct localized congenital fibro-osseous lesions in the lower leg, diagnosed on both radiology and histology as osteofibrous dysplasia, in the absence of hypophosphatemia or rickets, or significantly raised FGF23 levels but with distinct mosaic HRAS mutations. This expands the spectrum of cutaneous/skeletal mosaic RASopathies and alerts clinicians to the importance of evaluating for bony disease even in the absence of bone profile abnormalities.
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Affiliation(s)
- Lien Mestach
- Department of Dermatology, University Hospitals of Leuven, Leuven, Belgium
| | - Satyamaanasa Polubothu
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health, London, UK.,Paediatric Dermatology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Alistair Calder
- Paediatric Radiology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Ellen Denayer
- Center for Human Genetics, University Hospital Leuven, Leuven, Belgium
| | - Karolina Gholam
- Paediatric Dermatology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Eric Legius
- Center for Human Genetics, University Hospital Leuven, Leuven, Belgium.,Department of Human Genetics, KU Leuven - University of Leuven, Leuven, Belgium
| | - Elena Levtchenko
- Pediatric Nephrology, University Hospitals of Leuven, Leuven, Belgium.,Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - An Van Laethem
- Department of Dermatology, University Hospitals of Leuven, Leuven, Belgium
| | - Hilde Brems
- Center for Human Genetics, University Hospital Leuven, Leuven, Belgium.,Department of Human Genetics, KU Leuven - University of Leuven, Leuven, Belgium
| | - Veronica A Kinsler
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health, London, UK.,Paediatric Dermatology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Marie-Anne Morren
- Department of Dermatology, University Hospitals of Leuven, Leuven, Belgium
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4
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Muñoz-Maldonado C, Zimmer Y, Medová M. A Comparative Analysis of Individual RAS Mutations in Cancer Biology. Front Oncol 2019; 9:1088. [PMID: 31681616 PMCID: PMC6813200 DOI: 10.3389/fonc.2019.01088] [Citation(s) in RCA: 136] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 10/02/2019] [Indexed: 01/15/2023] Open
Abstract
In human cells, three closely related RAS genes, termed HRAS, KRAS, and NRAS, encode four highly homologous proteins. RAS proteins are small GTPases involved in a broad spectrum of key molecular and cellular activities, including proliferation and survival among others. Gain-of-function missense mutations, mostly located at codons 12, 13, and 61, constitutively activate RAS proteins and can be detected in various types of human cancers. KRAS is the most frequently mutated, followed by NRAS and HRAS. However, each isoform exhibits distinctive mutation frequency at each codon, supporting the hypothesis that different RAS mutants may lead to distinct biologic manifestations. This review is focused on the differences in signaling and phenotype, as well as on transcriptomics, proteomics, and metabolomics profiles related to individual RAS-mutated variants. Additionally, association of these mutants with particular targeted outcomes and rare mutations at additional RAS codons are discussed.
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Affiliation(s)
- Carmen Muñoz-Maldonado
- Department of Radiation Oncology, Inselspital, Bern University Hospital, Bern, Switzerland.,Radiation Oncology, Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Yitzhak Zimmer
- Department of Radiation Oncology, Inselspital, Bern University Hospital, Bern, Switzerland.,Radiation Oncology, Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Michaela Medová
- Department of Radiation Oncology, Inselspital, Bern University Hospital, Bern, Switzerland.,Radiation Oncology, Department for BioMedical Research, University of Bern, Bern, Switzerland
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5
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Bera AK, Lu J, Wales TE, Gondi S, Gurbani D, Nelson A, Engen JR, Westover KD. Structural basis of the atypical activation mechanism of KRAS V14I. J Biol Chem 2019; 294:13964-13972. [PMID: 31341022 PMCID: PMC6755796 DOI: 10.1074/jbc.ra119.009131] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/18/2019] [Indexed: 01/20/2023] Open
Abstract
RAS regulation and signaling are largely accomplished by direct protein-protein interactions, making RAS protein dynamics a critical determinant of RAS function. Here, we report a crystal structure of GDP-bound KRASV14I, a mutated KRAS variant associated with the developmental RASopathy disorder Noonan syndrome (NS), at 1.5-1.6 Å resolution. The structure is notable for revealing a marked extension of switch 1 away from the G-domain and nucleotide-binding site of the KRAS protein. We found that this extension is associated with a loss of the magnesium ion and a tilt in the position of the guanine base because of the additional carbon introduced by the isoleucine substitution. Hydrogen-deuterium exchange MS analysis confirmed that this conformation occurs in solution, but also disclosed a difference in kinetics when compared with KRASA146T, another RAS mutant that displays a nearly identical conformation in previously reported crystal structures. This conformational change contributed to a high rate of guanine nucleotide-exchange factor (GEF)-dependent and -independent nucleotide exchange and to an increase in affinity for SOS Ras/Rac GEF 1 (SOS1), which appears to be the major mode of activation for this RAS variant. These results highlight a mechanistic connection between KRASA146T and KRASV14I that may have implications for the regulation of these variants and for the development of therapeutic strategies to manage KRAS variant-associated disorders.
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Affiliation(s)
- Asim K Bera
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Jia Lu
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Thomas E Wales
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Masachusetts 02115
| | - Sudershan Gondi
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Deepak Gurbani
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Andrew Nelson
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Masachusetts 02115
| | - Kenneth D Westover
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
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6
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Abstract
Genetic mosaicism arises when a zygote harbors two or more distinct genotypes, typically due to de novo, somatic mutation during embryogenesis. The clinical manifestations largely depend on the differentiation status of the mutated cell; earlier mutations target pluripotent cells and generate more widespread disease affecting multiple organ systems. If gonadal tissue is spared-as in somatic genomic mosaicism-the mutation and its effects are limited to the proband, whereas mosaicism also affecting the gametes, such as germline or gonosomal mosaicism, is transmissible. Mosaicism is easily appreciated in cutaneous disorders, as phenotypically distinct mutant cells often give rise to lesions in patterns determined by the affected cell type. Genetic investigation of cutaneous mosaic disorders has identified pathways central to disease pathogenesis, revealing novel therapeutic targets. In this review, we discuss examples of cutaneous mosaicism, approaches to gene discovery in these disorders, and insights into molecular pathobiology that have potential for clinical translation.
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Affiliation(s)
- Young H Lim
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut 06520, USA; .,Departments of Pathology and Genetics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Zoe Moscato
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut 06520, USA;
| | - Keith A Choate
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut 06520, USA; .,Departments of Pathology and Genetics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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7
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Viel A, De Pascale L, Toffoli G, Tumiotto L, Miotto E, Boiocchi M. Frequent Occurrence of Ha-rasl Allelic Deletion in Human Ovarian Adenocarcinomas. TUMORI JOURNAL 2018; 77:16-20. [PMID: 1708177 DOI: 10.1177/030089169107700104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Fourteen human adenocarcinoma specimens were analyzed for somatic abnormalities affecting genes of the ras family. No amplification of the 3 ras genes was detected. Allelic deletion of the Ha-rasl gene (11p15.5) was found to be a very common abnormality in human ovarian adenocarcinomas (4 out of 7 informative cases). However, in these neoplasm deletion of a presumed normal Ha-rasl allele is not a contributory factor in strengthening the tumorigenic effect of a mutated allele. More probably, Ha-rasl allelic losses are markers of larger chromosomal deletions. Analyses at γ globin loci (11p15.5) and int-2 locus (11q13) provided evidence that the deletions may extend from Ha-rasl locus towards the centromere but never involve loss of the entire chromosome 11. These findings may suggest that a putative tumor suppressor gene closely linked to Ha-rasl in 11p15.5 is involved in ovarian cancerogenesis.
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Affiliation(s)
- A Viel
- Division of Experimental Oncology 1, Centro di Riferimento Oncologico, Aviano, Pordenone, Italy
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8
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Lu J, Harrison RA, Li L, Zeng M, Gondi S, Scott D, Gray NS, Engen JR, Westover KD. KRAS G12C Drug Development: Discrimination between Switch II Pocket Configurations Using Hydrogen/Deuterium-Exchange Mass Spectrometry. Structure 2017; 25:1442-1448.e3. [PMID: 28781083 DOI: 10.1016/j.str.2017.07.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/26/2017] [Accepted: 07/06/2017] [Indexed: 11/29/2022]
Abstract
KRAS G12C, the most common RAS mutation found in non-small-cell lung cancer, has been the subject of multiple recent covalent small-molecule inhibitor campaigns including efforts directed at the guanine nucleotide pocket and separate work focused on an inducible pocket adjacent to the switch motifs. Multiple conformations of switch II have been observed, suggesting that switch II pocket (SIIP) binders may be capable of engaging a range of KRAS conformations. Here we report the use of hydrogen/deuterium-exchange mass spectrometry (HDX MS) to discriminate between conformations of switch II induced by two chemical classes of SIIP binders. We investigated the structural basis for differences in HDX MS using X-ray crystallography and discovered a new SIIP configuration in response to binding of a quinazoline chemotype. These results have implications for structure-guided drug design targeting the RAS SIIP.
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Affiliation(s)
- Jia Lu
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Rane A Harrison
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Lianbo Li
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Mei Zeng
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Sudershan Gondi
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - David Scott
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Nathanael S Gray
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA.
| | - Kenneth D Westover
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
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9
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Genotype and phenotype spectrum of NRAS germline variants. Eur J Hum Genet 2017; 25:823-831. [PMID: 28594414 DOI: 10.1038/ejhg.2017.65] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/14/2017] [Accepted: 03/28/2017] [Indexed: 12/20/2022] Open
Abstract
RASopathies comprise a group of disorders clinically characterized by short stature, heart defects, facial dysmorphism, and varying degrees of intellectual disability and cancer predisposition. They are caused by germline variants in genes encoding key components or modulators of the highly conserved RAS-MAPK signalling pathway that lead to dysregulation of cell signal transmission. Germline changes in the genes encoding members of the RAS subfamily of GTPases are rare and associated with variable phenotypes of the RASopathy spectrum, ranging from Costello syndrome (HRAS variants) to Noonan and Cardiofaciocutaneous syndromes (KRAS variants). A small number of RASopathy cases with disease-causing germline NRAS alterations have been reported. Affected individuals exhibited features fitting Noonan syndrome, and the observed germline variants differed from the typical oncogenic NRAS changes occurring as somatic events in tumours. Here we describe 19 new cases with RASopathy due to disease-causing variants in NRAS. Importantly, four of them harbored missense changes affecting Gly12, which was previously described to occur exclusively in cancer. The phenotype in our cohort was variable but well within the RASopathy spectrum. Further, one of the patients (c.35G>A; p.(Gly12Asp)) had a myeloproliferative disorder, and one subject (c.34G>C; p.(Gly12Arg)) exhibited an uncharacterized brain tumour. With this report, we expand the genotype and phenotype spectrum of RASopathy-associated germline NRAS variants and provide evidence that NRAS variants do not spare the cancer-associated mutation hotspots.
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10
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Bertola D, Buscarilli M, Stabley DL, Baker L, Doyle D, Bartholomew DW, Sol-Church K, Gripp KW. Phenotypic spectrum of Costello syndrome individuals harboring the rare HRAS mutation p.Gly13Asp. Am J Med Genet A 2017; 173:1309-1318. [PMID: 28371260 DOI: 10.1002/ajmg.a.38178] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 12/12/2016] [Accepted: 01/18/2017] [Indexed: 12/19/2022]
Abstract
Costello syndrome is part of the RASopathies, a group of neurocardiofaciocutaneous syndromes caused by deregulation of the RAS mitogen-activated protein kinase pathway. Heterozygous mutations in HRAS are responsible for Costello syndrome, with more than 80% of the patients harboring the specific p.Gly12Ser variant. These individuals show a homogeneous phenotype. The clinical characteristics of the Costello syndrome individuals harboring rarer HRAS mutations are less understood, due to the small number of reported cases. Here, we describe the phenotypic spectrum of five additional individuals with HRAS c.38G>A; p.Gly13Asp, including one with somatic mosaicism, and review five previously described cases. The facial and hair abnormalities of the HRAS p.Gly13Asp individuals differ from the typical pattern observed in those showing the common HRAS (p.Gly12Ser) mutation, with less coarse facial features and slow growing, sparse hair with abnormal texture, the latter resembling the pattern observed in Noonan syndrome-like disorder with loose anagen hair and individuals harboring another amino acid substitution in HRAS (p.Gly13Cys). Although some individuals with HRAS p.Gly13Asp developed papillomata and vascular proliferation lesions, no malignant tumors occurred, similar to what was reported for individuals harboring the HRAS p.Gly13Cys. The fact that no malignant tumors were described in these individuals does not allow definitive conclusions about the risk for cancer development. It remains to be determined if substitutions of amino acid 13 in HRAS (p.Gly13Asp and p.Gly13Cys) increase the risk of tumor development.
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Affiliation(s)
- Débora Bertola
- Unidade de Genética Clínica, Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.,Instituto de Biociências da Universidade de São Paulo, São Paulo, Brazil
| | - Michelle Buscarilli
- Unidade de Genética Clínica, Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Deborah L Stabley
- Center for Applied Clinical Genomics, A. I. duPont Hospital for Children/Nemours, Wilmington, Delaware
| | - Laura Baker
- Division of Medical Genetics, A. I. duPont Hospital for Children/Nemours, Wilmington, Delaware
| | - Daniel Doyle
- Division of Endocrinology, A. I. duPont Hospital for Children/Nemours, Wilmington, Delaware
| | - Dennis W Bartholomew
- Division of Molecular and Human Genetics, Nationwide Children's Hospital, Columbus, Ohio
| | - Katia Sol-Church
- Center for Applied Clinical Genomics, A. I. duPont Hospital for Children/Nemours, Wilmington, Delaware
| | - Karen W Gripp
- Center for Applied Clinical Genomics, A. I. duPont Hospital for Children/Nemours, Wilmington, Delaware.,Division of Medical Genetics, A. I. duPont Hospital for Children/Nemours, Wilmington, Delaware
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11
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Ostrem JML, Shokat KM. Direct small-molecule inhibitors of KRAS: from structural insights to mechanism-based design. Nat Rev Drug Discov 2016; 15:771-785. [PMID: 27469033 DOI: 10.1038/nrd.2016.139] [Citation(s) in RCA: 400] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
KRAS is the most frequently mutated oncogene in human cancer. In addition to holding this distinction, unsuccessful attempts to target this protein have led to the characterization of RAS as 'undruggable'. However, recent advances in technology and novel approaches to drug discovery have renewed hope that a direct KRAS inhibitor may be on the horizon. In this Review, we provide an in-depth analysis of the structure, dynamics, mutational activation and inactivation, and signalling mechanisms of RAS. From this perspective, we then consider potential mechanisms of action for effective RAS inhibitors. Finally, we examine each of the many recent reports of direct RAS inhibitors and discuss promising avenues for further development.
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Affiliation(s)
- Jonathan M L Ostrem
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, California 94143, USA
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12
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Hartung AM, Swensen J, Uriz IE, Lapin M, Kristjansdottir K, Petersen USS, Bang JMV, Guerra B, Andersen HS, Dobrowolski SF, Carey JC, Yu P, Vaughn C, Calhoun A, Larsen MR, Dyrskjøt L, Stevenson DA, Andresen BS. The Splicing Efficiency of Activating HRAS Mutations Can Determine Costello Syndrome Phenotype and Frequency in Cancer. PLoS Genet 2016; 12:e1006039. [PMID: 27195699 PMCID: PMC4873146 DOI: 10.1371/journal.pgen.1006039] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/18/2016] [Indexed: 12/25/2022] Open
Abstract
Costello syndrome (CS) may be caused by activating mutations in codon 12/13 of the HRAS proto-oncogene. HRAS p.Gly12Val mutations have the highest transforming activity, are very frequent in cancers, but very rare in CS, where they are reported to cause a severe, early lethal, phenotype. We identified an unusual, new germline p.Gly12Val mutation, c.35_36GC>TG, in a 12-year-old boy with attenuated CS. Analysis of his HRAS cDNA showed high levels of exon 2 skipping. Using wild type and mutant HRAS minigenes, we confirmed that c.35_36GC>TG results in exon 2 skipping by simultaneously disrupting the function of a critical Exonic Splicing Enhancer (ESE) and creation of an Exonic Splicing Silencer (ESS). We show that this vulnerability of HRAS exon 2 is caused by a weak 3' splice site, which makes exon 2 inclusion dependent on binding of splicing stimulatory proteins, like SRSF2, to the critical ESE. Because the majority of cancer- and CS- causing mutations are located here, they affect splicing differently. Therefore, our results also demonstrate that the phenotype in CS and somatic cancers is not only determined by the different transforming potentials of mutant HRAS proteins, but also by the efficiency of exon 2 inclusion resulting from the different HRAS mutations. Finally, we show that a splice switching oligonucleotide (SSO) that blocks access to the critical ESE causes exon 2 skipping and halts proliferation of cancer cells. This unravels a potential for development of new anti-cancer therapies based on SSO-mediated HRAS exon 2 skipping.
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Affiliation(s)
- Anne-Mette Hartung
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Jeff Swensen
- Caris Life Sciences, Phoenix, Arizona, United States of America
- Department of Pathology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- ARUP Laboratories, Salt Lake City, Utah, United States of America
| | - Inaki E. Uriz
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Morten Lapin
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Karen Kristjansdottir
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Ulrika S. S. Petersen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Jeanne Mari V. Bang
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Barbara Guerra
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Henriette Skovgaard Andersen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Steven F. Dobrowolski
- Department of Pathology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - John C. Carey
- Department of Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Ping Yu
- ARUP Laboratories, Salt Lake City, Utah, United States of America
| | - Cecily Vaughn
- ARUP Laboratories, Salt Lake City, Utah, United States of America
| | - Amy Calhoun
- Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Martin R. Larsen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Lars Dyrskjøt
- Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - David A. Stevenson
- Division of Medical Genetics, Stanford University, Stanford, California, United States of America
| | - Brage S. Andresen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
- * E-mail:
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13
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Hair Follicle Miniaturization in a Woolly Hair Nevus: A Novel "Root" Perspective for a Mosaic Hair Disorder. Am J Dermatopathol 2016; 38:239-43. [PMID: 26894777 DOI: 10.1097/dad.0000000000000525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Woolly hair nevus is a mosaic disorder characterized by unruly, tightly curled hair in a circumscribed area of the scalp. This condition may be associated with epidermal nevi. We describe an 11-year-old boy who initially presented with multiple patches of woolly hair and with epidermal nevi on his left cheek and back. He had no nail, teeth, eye, or cardiac abnormalities. Analysis of plucked hairs from patches of woolly hair showed twisting of the hair shaft and an abnormal hair cuticle. Histopathology of a woolly hair patch showed diffuse hair follicle miniaturization with increased vellus hairs.
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Wey M, Lee J, Kim HS, Jeong SS, Kim J, Heo J. Kinetic Mechanism of Formation of Hyperactive Embryonic Ras in Cells. Biochemistry 2016; 55:543-59. [PMID: 26765051 DOI: 10.1021/acs.biochem.5b00902] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Embryonic Ras (ERas)--a new subset of Ras proteins--are characterized by a unique p-loop residue, unique Switch II residues, and an unusual extended N-terminus. When expressed, both murine and human ERas are highly populated in their GTP-bound forms. The expression of murine ERas is linked to the development of murine embryonic cells, and the expression of human ERas is correlated to certain human cancers. Mutation-based kinetic analyses, in combination with assessments of the kinetic parameter-based calculation of the fraction of the GTP-bound active form of ERas proteins, explain the kinetic mechanism that produces the unprecedented hyperactive ERas. The ERas-specific p-loop residue contributes ERas proteins to intrinsically populate their GTP-bound form in cells. Furthermore, the ERas-specific Switch II residues block the catalytic action of p120GAP on ERas proteins. This blockage sustains the previously mentioned GTP-bound ERas proteins. In essence, the combined work of the ERas-specific p-loop and Switch II residues populates the exceedingly high GTP-bound form of ERas in cells. This study also rules out any kinetic function of the unique ERas-specific N-terminus in the production of the hyperactive GTP-bound ERas in cells. The biological role of this N-terminus remains uninvestigated. Intriguingly, the ERas-specific p-loop residue matches the mutated Ser residue of the Costello Syndrome G12S HRas mutant that also intrinsically populates its GTP-bound form in cells. However, because the effector protein of ERas differs from that of G12S HRas, this kinetic similarity does not confer on ERas biological and/or pathophysiological similarity to G12S HRas.
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Affiliation(s)
- Michael Wey
- Department of Chemistry and Biochemistry, The University of Texas at Arlington , Arlington, Texas 76019, United States
| | - Jungwoon Lee
- Department of Life Science, Sogang University , Seoul 121-742, Korea
| | - Hyo Sun Kim
- Department of Life Science, Sogang University , Seoul 121-742, Korea
| | - Soon Seog Jeong
- Humanzyme , 2201 West Campbell Park Drive, Chicago, Illinois 60612, United States
| | - Jungho Kim
- Department of Life Science, Sogang University , Seoul 121-742, Korea
| | - Jongyun Heo
- Department of Chemistry and Biochemistry, The University of Texas at Arlington , Arlington, Texas 76019, United States
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15
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Gripp KW, Sol-Church K, Smpokou P, Graham GE, Stevenson DA, Hanson H, Viskochil DH, Baker LC, Russo B, Gardner N, Stabley DL, Kolbe V, Rosenberger G. An attenuated phenotype of Costello syndrome in three unrelated individuals with a HRAS c.179G>A (p.Gly60Asp) mutation correlates with uncommon functional consequences. Am J Med Genet A 2015; 167A:2085-97. [PMID: 25914166 DOI: 10.1002/ajmg.a.37128] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 04/06/2015] [Indexed: 12/20/2022]
Abstract
Heterozygous germline mutations in the proto-oncogene HRAS cause Costello syndrome (CS), an intellectual disability condition with severe failure to thrive, cardiac abnormalities, predisposition to tumors, and neurologic abnormalities. More than 80% of patients share the HRAS mutation c.34G>A (p.Gly12Ser) associated with the typical, relatively homogeneous phenotype. Rarer mutations occurred in individuals with an attenuated phenotype and less characteristic facial features. Most pathogenic HRAS alterations affect hydrolytic HRAS activity resulting in constitutive activation. "Gain-of-function" and "hyperactivation" concerning downstream pathways are widely used to explain the molecular basis and dysregulation of the RAS-MAPK pathway is the biologic mechanism shared amongst rasopathies. Panel testing for rasopathies identified a novel HRAS mutation (c.179G>A; p.Gly60Asp) in three individuals with attenuated features of Costello syndrome. De novo paternal origin occurred in two, transmission from a heterozygous mother in the third. Individuals showed subtle facial features; curly hair and relative macrocephaly were seen in three; atrial tachycardia and learning difficulties in two, and pulmonic valve dysplasia and mildly thickened left ventricle in one. None had severe failure to thrive, intellectual disability or cancer, underscoring the need to consider HRAS mutations in individuals with an unspecific rasopathy phenotype. Functional studies revealed strongly increased HRAS(Gly60Asp) binding to RAF1, but not to other signaling effectors. Hyperactivation of the MAPK downstream signaling pathways was absent. Our results indicate that an increase in the proportion of activated RAS downstream signaling components does not entirely explain the molecular basis of CS. We conclude that the phenotypic variability in CS recapitulates variable qualities of molecular dysfunction.
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Affiliation(s)
- Karen W Gripp
- Division of Medical Genetics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | - Katia Sol-Church
- Center for Applied Clinical Genomics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | - Patroula Smpokou
- Division of Genetics and Metabolism, Children's National Health System, Washington, District of Columbia
| | - Gail E Graham
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - David A Stevenson
- Division of Medical Genetics, Stanford University, Stanford, California
| | - Heather Hanson
- Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, Utah
| | - David H Viskochil
- Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, Utah
| | - Laura C Baker
- Division of Medical Genetics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | - Bridget Russo
- Center for Applied Clinical Genomics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | - Nick Gardner
- Center for Applied Clinical Genomics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | - Deborah L Stabley
- Center for Applied Clinical Genomics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | - Verena Kolbe
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Georg Rosenberger
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Alamo P, Gallardo A, Di Nicolantonio F, Pavón MA, Casanova I, Trias M, Mangues MA, Lopez-Pousa A, Villaverde A, Vázquez E, Bardelli A, Céspedes MV, Mangues R. Higher metastatic efficiency of KRas G12V than KRas G13D in a colorectal cancer model. FASEB J 2014; 29:464-76. [PMID: 25359494 DOI: 10.1096/fj.14-262303] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although all KRas (protein that in humans is encoded by the KRas gene) point mutants are considered to have a similar prognostic capacity, their transformation and tumorigenic capacities vary widely. We compared the metastatic efficiency of KRas G12V (Kirsten rat sarcoma viral oncogene homolog with valine mutation at codon 12) and KRas G13D (Kirsten rat sarcoma viral oncogene homolog with aspartic mutation at codon 13) oncogenes in an orthotopic colorectal cancer (CRC) model. Following subcutaneous preconditioning, recombinant clones of the SW48 CRC cell line [Kras wild-type (Kras WT)] expressing the KRas G12V or KRas G13D allele were microinjected in the mouse cecum. The percentage of animals developing lymph node metastasis was higher in KRas G12V than in KRas G13D mice. Microscopic, macroscopic, and visible lymphatic foci were 1.5- to 3.0-fold larger in KRas G12V than in KRas G13D mice (P < 0.05). In the lung, only microfoci were developed in both groups. KRas G12V primary tumors had lower apoptosis (7.0 ± 1.2 vs. 7.4 ± 1.0 per field, P = 0.02), higher tumor budding at the invasion front (1.2 ± 0.2 vs. 0.6 ± 0.1, P = 0.04), and a higher percentage of C-X-C chemokine receptor type 4 (CXCR4)-overexpressing intravasated tumor emboli (49.8 ± 9.4% vs. 12.8 ± 4.4%, P < 0.001) than KRas G13D tumors. KRas G12V primary tumors showed Akt activation, and β5 integrin, vascular endothelial growth factor A (VEGFA), and Serpine-1 overexpression, whereas KRas G13D tumors showed integrin β1 and angiopoietin 2 (Angpt2) overexpression. The increased cell survival, invasion, intravasation, and specific molecular regulation observed in KRas G12V tumors is consistent with the higher aggressiveness observed in patients with CRC expressing this oncogene.
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Affiliation(s)
- Patricia Alamo
- Oncogenesis and Antitumor Drug Group, Biomedical Research Institute Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain
| | - Alberto Gallardo
- CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain; Department of Pathology, Clínica Girona, Girona, Spain
| | - Federica Di Nicolantonio
- Department of Oncology, University of Torino, Torino, Italy; Candiolo Cancer Institute-Fondazione del Piemonte per l'Oncologia, Istituto Di Ricovero e Cura a Carattere Scientifico, Torino, Italy
| | - Miguel Angel Pavón
- Oncogenesis and Antitumor Drug Group, Biomedical Research Institute Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain
| | - Isolda Casanova
- Oncogenesis and Antitumor Drug Group, Biomedical Research Institute Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain
| | - Manuel Trias
- CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain; Departments of General and Digestive Surgery
| | | | - Antonio Lopez-Pousa
- CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain; Medical Oncology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Antonio Villaverde
- CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain; Institut de Biotecnologia i de Biomedicina, and
| | - Esther Vázquez
- CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain; Institut de Biotecnologia i de Biomedicina, and
| | - Alberto Bardelli
- Department of Oncology, University of Torino, Torino, Italy; Candiolo Cancer Institute-Fondazione del Piemonte per l'Oncologia, Istituto Di Ricovero e Cura a Carattere Scientifico, Torino, Italy; Department de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain; and FIRC Institute of Molecular Oncology, Milan, Italy
| | - María Virtudes Céspedes
- Oncogenesis and Antitumor Drug Group, Biomedical Research Institute Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain
| | - Ramón Mangues
- Oncogenesis and Antitumor Drug Group, Biomedical Research Institute Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain;
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17
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Yoon HH, Tougeron D, Shi Q, Alberts SR, Mahoney MR, Nelson GD, Nair SG, Thibodeau SN, Goldberg RM, Sargent DJ, Sinicrope FA. KRAS codon 12 and 13 mutations in relation to disease-free survival in BRAF-wild-type stage III colon cancers from an adjuvant chemotherapy trial (N0147 alliance). Clin Cancer Res 2014; 20:3033-43. [PMID: 24687927 DOI: 10.1158/1078-0432.ccr-13-3140] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE We examined the prognostic impact of specific KRAS mutations in patients with stage III colon adenocarcinoma receiving adjuvant FOLFOX alone or combined with cetuximab in a phase III trial (N0147). Analysis was restricted to BRAF-wild-type tumors, because BRAF mutation was associated with poor prognosis, and BRAF and KRAS mutations are mutually exclusive. EXPERIMENTAL DESIGN The seven most common KRAS mutations in codon 12 and codon 13 were examined in 2,478 BRAF-wild-type tumors. Because KRAS mutations in codon 12 (n = 779) or 13 (n = 220) were not predictive of adjuvant cetuximab benefit, study arms were pooled for analysis. Disease-free survival (DFS) was evaluated by HRs using Cox models. RESULTS KRAS mutations in codon 12 (multivariate HR, 1.52; 95% confidence interval, CI, 1.28-1.80; P < 0.0001) or codon 13 (multivariate HR, 1.36; 95% CI, 1.04-1.77; P = 0.0248) were significantly associated with shorter DFS compared with patients with wild-type KRAS/BRAF tumors, independent of covariates. KRAS codon 12 mutations were independently associated with proficient mismatch repair (P < 0.0001), proximal tumor site (P < 0.0001), low grade, age, and sex, whereas codon 13 mutations were associated with proximal site (P < 0.0001). CONCLUSION KRAS mutations in either codon 12 or 13 are associated with inferior survival in patients with resected stage III colon cancer. These data highlight the importance of accurate molecular characterization and the significant role of KRAS mutations in both codons in the progression of this malignancy in the adjuvant setting. Clin Cancer Res; 20(11); 3033-43. ©2014 AACR.
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Affiliation(s)
- Harry H Yoon
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - David Tougeron
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Qian Shi
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Steven R Alberts
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Michelle R Mahoney
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Garth D Nelson
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Suresh G Nair
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Stephen N Thibodeau
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Richard M Goldberg
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Daniel J Sargent
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
| | - Frank A Sinicrope
- Authors' Affiliations: Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota; Lehigh Valley Hospital, Allentown, Pennsylvania; and Ohio State University, Columbus, Ohio
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18
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Nicole Weaver K, Wang D, Cnota J, Gardner N, Stabley D, Sol-Church K, Gripp KW, Witte DP, Bove KE, Hopkin RJ. Early-lethal Costello syndrome due to rare HRAS Tandem Base substitution (c.35_36GC>AA; p.G12E)-associated pulmonary vascular disease. Pediatr Dev Pathol 2014; 17:421-30. [PMID: 25133308 PMCID: PMC4294968 DOI: 10.2350/14-05-1488-oa.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Costello syndrome is a rare, autosomal-dominant syndrome caused by activating missense mutations in the Harvey rat sarcoma viral oncogene homolog (HRAS), most often p.G12S. Several rare mutations have consistently been associated with a more severe phenotype that is often lethal in infancy. Cause of death is most often respiratory failure, with hypertrophic cardiomyopathy playing a significant role in morbidity. Impaired fibroblast elastogenesis is thought to contribute to the Costello phenotype, but reports of histologic evidence of disordered elastogenesis at autopsy are limited. We report a patient with Costello syndrome due to a rare tandem base substitution (c.35_36GC>AA) resulting in the p.G12E missense change. The proband died at the age of 3 months from respiratory failure, with minimal evidence of cardiomyopathy. The autopsy disclosed pulmonary vascular dysplasia affecting small arteries and veins associated with abnormal elastin distribution in tortuous dilated arteries and veins, with nonuniform wall thickness and semiobstructive lesions at artery branch points typical of early pulmonary hypertensive vascular disease. Elastic fibers in the dermis were abnormally short and fragmented. This case suggests that disordered elastogenesis in the pulmonary vasculature and undiagnosed (or underdiagnosed) pulmonary hypertension may contribute to morbidity in patients with Costello syndrome.
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Affiliation(s)
- K. Nicole Weaver
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
| | - Dehua Wang
- Division of Pathology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
| | - James Cnota
- The Heart Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
| | - Nicholas Gardner
- Biomedical Research, A. I. duPont Hospital for Children, 1600 Rockland Road, Wilmington, Delaware, 19803
| | - Deborah Stabley
- Biomedical Research, A. I. duPont Hospital for Children, 1600 Rockland Road, Wilmington, Delaware, 19803
| | - Katia Sol-Church
- Biomedical Research, A. I. duPont Hospital for Children, 1600 Rockland Road, Wilmington, Delaware, 19803
| | - Karen W. Gripp
- Division of Medical Genetics, A. I. duPont Hospital for Children, 1600 Rockland Road, Wilmington, Delaware, 19803
| | - David P. Witte
- Division of Pathology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
| | - Kevin E. Bove
- Division of Pathology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
| | - Robert J. Hopkin
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
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Contributions of intrinsic mutation rate and selfish selection to levels of de novo HRAS mutations in the paternal germline. Proc Natl Acad Sci U S A 2013; 110:20152-7. [PMID: 24259709 DOI: 10.1073/pnas.1311381110] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The RAS proto-oncogene Harvey rat sarcoma viral oncogene homolog (HRAS) encodes a small GTPase that transduces signals from cell surface receptors to intracellular effectors to control cellular behavior. Although somatic HRAS mutations have been described in many cancers, germline mutations cause Costello syndrome (CS), a congenital disorder associated with predisposition to malignancy. Based on the epidemiology of CS and the occurrence of HRAS mutations in spermatocytic seminoma, we proposed that activating HRAS mutations become enriched in sperm through a process akin to tumorigenesis, termed selfish spermatogonial selection. To test this hypothesis, we quantified the levels, in blood and sperm samples, of HRAS mutations at the p.G12 codon and compared the results to changes at the p.A11 codon, at which activating mutations do not occur. The data strongly support the role of selection in determining HRAS mutation levels in sperm, and hence the occurrence of CS, but we also found differences from the mutation pattern in tumorigenesis. First, the relative prevalence of mutations in sperm correlates weakly with their in vitro activating properties and occurrence in cancers. Second, specific tandem base substitutions (predominantly GC>TT/AA) occur in sperm but not in cancers; genomewide analysis showed that this same mutation is also overrepresented in constitutional pathogenic and polymorphic variants, suggesting a heightened vulnerability to these mutations in the germline. We developed a statistical model to show how both intrinsic mutation rate and selfish selection contribute to the mutational burden borne by the paternal germline.
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20
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Wey M, Lee J, Jeong SS, Kim J, Heo J. Kinetic mechanisms of mutation-dependent Harvey Ras activation and their relevance for the development of Costello syndrome. Biochemistry 2013; 52:8465-79. [PMID: 24224811 DOI: 10.1021/bi400679q] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Costello syndrome is linked to activating mutations of a residue in the p-loop or the NKCD/SAK motifs of Harvey Ras (HRas). More than 10 HRas mutants that induce Costello syndrome have been identified; G12S HRas is the most prevalent of these. However, certain HRas p-loop mutations also are linked to cancer formation that are exemplified with G12V HRas. Despite these relations, specific links between types of HRas mutations and diseases evade definition because some Costello syndrome HRas p-loop mutations, such as G12S HRas, also often cause cancer. This study established novel kinetic parameter-based equations that estimate the value of the cellular fractions of the GTP-bound active form of HRas mutant proteins. Such calculations differentiate between two basic kinetic mechanisms that populate the GTP-bound form of Ras in cells. (i) The increase in the level of GTP-bound Ras is caused by the HRas mutation-mediated perturbation of the intrinsic kinetic characteristics of Ras. This generates a broad spectrum of the population of the GTP-bound form of HRas that typically causes Costello syndrome. The upper end of this spectrum of HRas mutants, as exemplified by G12S HRas, can also cause cancer. (ii) The increase in the level of GTP-bound Ras occurs because the HRas mutations perturb the action of p120GAP on Ras. This causes production of a significantly high population of the only GTP-bound form of HRas linked merely to cancer formation. HRas mutant G12V belongs to this category.
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Affiliation(s)
- Michael Wey
- Department of Chemistry and Biochemistry, The University of Texas at Arlington , Arlington, Texas 76019, United States
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22
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Mitrofanov VG, Chekunova AI, Proshakov PA, Barsukov MI. Universal intracellular transducer ras and its role in the development of drosophila. Russ J Dev Biol 2013. [DOI: 10.1134/s1062360413040073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Liu Y, Wang Z, Li H, Wu Z, Wei F, Wang H. Role of the ERas gene in gastric cancer cells. Oncol Rep 2013; 30:50-6. [PMID: 23612786 PMCID: PMC3729207 DOI: 10.3892/or.2013.2417] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 03/21/2013] [Indexed: 01/06/2023] Open
Abstract
As a novel member of the Ras family, ERas, found in murine embryonic stem (ES) cells in 2003, was considered a pseudogene. To date, there are a few reports on the relationship between ERas and tumors. It was recently suggested that ERas could affect gastric carcinoma (GC) metastasis, but no significant relationship was found with tumor proliferation. Since ERas plays an important role in tumor-like growth of ES cells subcutaneously injected into nude mice, we hypothesized that ERas plays a role in tumor proliferation. In this experiment, we selected 7 GC strains from different sources with different differentiation degrees, we detected the expression of full length ERas transcript, and selected two ERas highly expressing GC strains, MKN-28 and BGC-823. After knocking down the ERas gene by siRNA, we observed that there was a significant decrease in proliferation, metastasis as well as clonality. Therefore, ERas is confirmed to be an important gene in affecting tumor proliferation and metastasis. Furthermore, the significance of the ERas mechanism and signaling pathway is shown.
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Affiliation(s)
- Yang Liu
- Experimental Research Center, First People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200080, P.R. China
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24
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Figueras A, Arbos MA, Quiles MT, Viñals F, Germà JR, Capellà G. The impact of KRAS mutations on VEGF-A production and tumour vascular network. BMC Cancer 2013; 13:125. [PMID: 23506169 PMCID: PMC3610256 DOI: 10.1186/1471-2407-13-125] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 03/08/2013] [Indexed: 11/15/2022] Open
Abstract
Background The malignant potential of tumour cells may be influenced by the molecular nature of KRAS mutations being codon 13 mutations less aggressive than codon 12 ones. Their metabolic profile is also different, with an increased anaerobic glycolytic metabolism in cells harbouring codon 12 KRAS mutations compared with cells containing codon 13 mutations. We hypothesized that this distinct metabolic behaviour could be associated with different HIF-1α expression and a distinct angiogenic profile. Methods Codon13 KRAS mutation (ASP13) or codon12 KRAS mutation (CYS12) NIH3T3 transfectants were analyzed in vitro and in vivo. Expression of HIF-1α, and VEGF-A was studied at RNA and protein levels. Regulation of VEGF-A promoter activity was assessed by means of luciferase assays using different plasmid constructs. Vascular network was assessed in tumors growing after subcutaneous inoculation. Non parametric statistics were used for analysis of results. Results Our results show that in normoxic conditions ASP13 transfectants exhibited less HIF-1α protein levels and activity than CYS12. In contrast, codon 13 transfectants exhibited higher VEGF-A mRNA and protein levels and enhanced VEGF-A promoter activity. These differences were due to a differential activation of Sp1/AP2 transcription elements of the VEGF-A promoter associated with increased ERKs signalling in ASP13 transfectants. Subcutaneous CYS12 tumours expressed less VEGF-A and showed a higher microvessel density (MVD) than ASP13 tumours. In contrast, prominent vessels were only observed in the latter. Conclusion Subtle changes in the molecular nature of KRAS oncogene activating mutations occurring in tumour cells have a major impact on the vascular strategy devised providing with new insights on the role of KRAS mutations on angiogenesis.
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Affiliation(s)
- Agnès Figueras
- Translational Research Laboratory, Institut Català d'Oncologia-IDIBELL, Gran Via 199-203, 08908 L'Hospitalet del Llobregat, Barcelona, Spain
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Lorenz S, Lissewski C, Simsek-Kiper PO, Alanay Y, Boduroglu K, Zenker M, Rosenberger G. Functional analysis of a duplication (p.E63_D69dup) in the switch II region of HRAS: new aspects of the molecular pathogenesis underlying Costello syndrome. Hum Mol Genet 2013; 22:1643-53. [PMID: 23335589 DOI: 10.1093/hmg/ddt014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Costello syndrome is a congenital disorder comprising a characteristic face, severe feeding difficulties, skeletal, cardiac and skin abnormalities, intellectual disability and predisposition to malignancies. It is caused by heterozygous germline HRAS mutations mostly affecting Gly(12) or Gly(13), which impair HRAS-GTPase activity and result in increased downstream signal flow independent of incoming signals. Functional analyses of rarer HRAS mutations identified in individuals with attenuated Costello syndrome phenotypes revealed altered GDP/GTP nucleotide affinities (p.K117R) and inefficient effector binding (p.E37dup). Thus, both phenotypic and functional variability associated with HRAS mutations are evident. Here, we report on a novel heterozygous HRAS germline mutation (c.187_207dup, p.E63_D69dup) in a girl presenting with a phenotype at the milder end of the Costello syndrome spectrum. The p.E63_D69dup mutation impaired co-precipitation of recombinant HRAS with NF1 GTPase-activating protein (GAP) suggesting constitutive HRAS(E63_D69dup) activation due to GAP insensitivity. Indeed, we identified strongly augmented active HRAS(E63_D69dup) that co-precipitated with effectors RAF1, RAL guanine nucleotide dissociation stimulator and phospholipase C1. However, we could not pull down active HRAS(E63_D69dup) using the target protein PIK3CA, indicating a compromised association between active HRAS(E63_D69dup) and PIK3CA. Accordingly, overexpression of HRAS(E63_D69dup) increased steady-state phosphorylation of MEK1/2 and ERK1/2 downstream of RAF, whereas AKT phosphorylation downstream of phosphoinositide 3-kinase (PI3K) was not enhanced. By analyzing signaling dynamics, we found that HRAS(E63_D69dup) has impaired reagibility to stimuli resulting in reduced and disrupted capacity to transduce incoming signals to the RAF-MAPK and PI3K-AKT cascade, respectively. We suggest that disrupted HRAS reagibility, as we demonstrate for the p.E63_D69dup mutation, is a previously unappreciated molecular pathomechanism underlying Costello syndrome.
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Affiliation(s)
- Sybille Lorenz
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
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Johnson CW, Mattos C. The Allosteric Switch and Conformational States in Ras GTPase Affected by Small Molecules. INHIBITORS OF THE RAS SUPERFAMILY G-PROTEINS, PART A 2013; 33 Pt A:41-67. [DOI: 10.1016/b978-0-12-416749-0.00003-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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27
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Gripp KW, Bifeld E, Stabley DL, Hopkins E, Meien S, Vinette K, Sol-Church K, Rosenberger G. A novel HRAS substitution (c.266C>G; p.S89C) resulting in decreased downstream signaling suggests a new dimension of RAS pathway dysregulation in human development. Am J Med Genet A 2012; 158A:2106-18. [PMID: 22821884 DOI: 10.1002/ajmg.a.35449] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 04/08/2012] [Indexed: 12/13/2022]
Abstract
Costello syndrome is caused by HRAS germline mutations affecting Gly(12) or Gly(13) in >90% of cases and these are associated with a relatively homogeneous phenotype. Rarer mutations in other HRAS codons were reported in patients with an attenuated or mild phenotype. Disease-associated HRAS missense mutations result in constitutive HRAS activation and increased RAF-MEK-ERK and PI3K-AKT signal flow. Here we report on a novel heterozygous HRAS germline alteration, c.266C>G (p.S89C), in a girl presenting with severe fetal hydrops and pleural effusion, followed by a more benign postnatal course. A sibling with the same mutation and fetal polyhydramnios showed a Dandy-Walker malformation; his postnatal course was complicated by severe feeding difficulties. Their apparently asymptomatic father is heterozygous for the c.266C>G change. By functional analyses we identified reduced levels of active HRAS(S89C) and diminished MEK, ERK and AKT phosphorylation in cells overexpressing HRAS(S89C) , which represent novel consequences of disease-associated HRAS mutations. Given our patients' difficult neonatal course and presence of this change in their asymptomatic father, we hypothesize that its harmful consequences may be time limited, with the late fetal stage being most sensitive. Alternatively, the phenotype may develop only in the presence of an additional as-yet-unknown genetic modifier. While the pathogenicity of the HRAS c.266C>G change remains unproven, our data may illustrate wide functional and phenotypic variability of germline HRAS mutations.
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Affiliation(s)
- Karen W Gripp
- Division of Medical Genetics, A. I. duPont Hospital for Children, Wilmington, Delaware, USA
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28
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de Pontual L, Kettaneh D, Gordon CT, Oufadem M, Boddaert N, Lees M, Balu L, Lachassinne E, Petros A, Mollet J, Wilson LC, Munnich A, Brugière L, Delattre O, Vekemans M, Etchevers H, Lyonnet S, Janoueix-Lerosey I, Amiel J. Germline gain-of-function mutations of ALK disrupt central nervous system development. Hum Mutat 2012; 32:272-6. [PMID: 21972109 DOI: 10.1002/humu.21442] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Neuroblastoma (NB) is a frequent embryonal tumor of sympathetic ganglia and adrenals with extremely variable outcome. Recently, somatic amplification and gain-of-function mutations of the anaplastic lymphoma receptor tyrosine kinase (ALK) gene, either somatic or germline, were identified in a significant proportion of NB cases. Here we report a novel syndromic presentation associating congenital NB with severe encephalopathy and abnormal shape of the brainstem on brain MRI in two unrelated sporadic cases harboring de novo, germline, heterozygous ALK gene mutations. Both mutations are gain-of-function mutations that have been reported in NB and NB cell lines. These observations further illustrate the role of oncogenes in both tumour predisposition and normal development, and shed light on the pleiotropic and activity-dependent role of ALK in humans. More generally, missing germline mutations relative to the spectrum of somatic mutations reported for a given oncogene may be a reflection of severe effects during embryonic development, and may prompt mutation screening in patients with extreme phenotypes.
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Paternal age effect mutations and selfish spermatogonial selection: causes and consequences for human disease. Am J Hum Genet 2012; 90:175-200. [PMID: 22325359 DOI: 10.1016/j.ajhg.2011.12.017] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 12/05/2011] [Accepted: 12/26/2011] [Indexed: 12/25/2022] Open
Abstract
Advanced paternal age has been associated with an increased risk for spontaneous congenital disorders and common complex diseases (such as some cancers, schizophrenia, and autism), but the mechanisms that mediate this effect have been poorly understood. A small group of disorders, including Apert syndrome (caused by FGFR2 mutations), achondroplasia, and thanatophoric dysplasia (FGFR3), and Costello syndrome (HRAS), which we collectively term "paternal age effect" (PAE) disorders, provides a good model to study the biological and molecular basis of this phenomenon. Recent evidence from direct quantification of PAE mutations in sperm and testes suggests that the common factor in the paternal age effect lies in the dysregulation of spermatogonial cell behavior, an effect mediated molecularly through the growth factor receptor-RAS signal transduction pathway. The data show that PAE mutations, although arising rarely, are positively selected and expand clonally in normal testes through a process akin to oncogenesis. This clonal expansion, which is likely to take place in the testes of all men, leads to the relative enrichment of mutant sperm over time-explaining the observed paternal age effect associated with these disorders-and in rare cases to the formation of testicular tumors. As regulation of RAS and other mediators of cellular proliferation and survival is important in many different biological contexts, for example during tumorigenesis, organ homeostasis and neurogenesis, the consequences of selfish mutations that hijack this process within the testis are likely to extend far beyond congenital skeletal disorders to include complex diseases, such as neurocognitive disorders and cancer predisposition.
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Martín-García F, Mendieta-Moreno JI, López-Viñas E, Gómez-Puertas P, Mendieta J. The Role of Gln61 in HRas GTP hydrolysis: a quantum mechanics/molecular mechanics study. Biophys J 2012; 102:152-7. [PMID: 22225809 DOI: 10.1016/j.bpj.2011.11.4005] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/26/2011] [Accepted: 11/29/2011] [Indexed: 11/19/2022] Open
Abstract
Activation of the water molecule involved in GTP hydrolysis within the HRas·RasGAP system is analyzed using a tailored approach based on hybrid quantum mechanics/molecular mechanics (QM/MM) simulation. A new path emerges: transfer of a proton from the attacking water molecule to a second water molecule, then a different proton is transferred from this second water molecule to the GTP. Gln(61) will stabilize the transient OH(-) and H(3)O(+) molecules thus generated. This newly proposed mechanism was generated by using, for the first time to our knowledge, the entire HRas-RasGAP protein complex in a QM/MM simulation context. It also offers a rational explanation for previous experimental results regarding the decrease of GTPase rate found in the HRas Q61A mutant and the increase exhibited by the HRas Q61E mutant.
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Affiliation(s)
- Fernando Martín-García
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Cientificas-Universidad Autónoma de Madrid), Madrid, Spain
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Miller MS, Miller LD. RAS Mutations and Oncogenesis: Not all RAS Mutations are Created Equally. Front Genet 2012; 2:100. [PMID: 22303394 PMCID: PMC3262225 DOI: 10.3389/fgene.2011.00100] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 12/13/2011] [Indexed: 12/28/2022] Open
Abstract
Mutation in RAS proteins is one of the most common genetic alterations observed in human and experimentally induced rodent cancers. In vivo, oncogenic mutations have been shown to occur at exons 12, 13, and 61, resulting in any 1 of 19 possible point mutations in a given tumor for a specific RAS isoform. While some studies have suggested a possible role of different mutant alleles in determining tumor severity and phenotype, no general consensus has emerged on the oncogenicity of different mutant alleles in tumor formation and progression. Part of this may be due to a lack of a single, signature pathway that shows significant alterations between different mutations. Rather, it is likely that subtle differences in the activation, or lack thereof, of downstream effectors by different RAS mutant alleles may determine the eventual outcome in terms of tumor phenotype. This paper reviews our current understanding of the potential role of different RAS mutations on tumorigenesis, highlights studies in model cell culture and in vivo systems, and discusses the potential of expression array and computational network modeling to dissect out differences in activated RAS genes in conferring a transforming phenotype.
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Affiliation(s)
- Mark Steven Miller
- Department of Cancer Biology, Comprehensive Cancer Center, Wake Forest School of MedicineWinston-Salem, NC, USA
| | - Lance D. Miller
- Department of Cancer Biology, Comprehensive Cancer Center, Wake Forest School of MedicineWinston-Salem, NC, USA
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32
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Niihori T, Aoki Y, Okamoto N, Kurosawa K, Ohashi H, Mizuno S, Kawame H, Inazawa J, Ohura T, Arai H, Nabatame S, Kikuchi K, Kuroki Y, Miura M, Tanaka T, Ohtake A, Omori I, Ihara K, Mabe H, Watanabe K, Niijima S, Okano E, Numabe H, Matsubara Y. HRAS mutants identified in Costello syndrome patients can induce cellular senescence: possible implications for the pathogenesis of Costello syndrome. J Hum Genet 2011; 56:707-15. [PMID: 21850009 DOI: 10.1038/jhg.2011.85] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Costello syndrome (CS) is a congenital disease that is characterized by a distinctive facial appearance, failure to thrive, mental retardation and cardiomyopathy. In 2005, we discovered that heterozygous germline mutations in HRAS caused CS. Several studies have shown that CS-associated HRAS mutations are clustered in codons 12 and 13, and mutations in other codons have also been identified. However, a comprehensive comparison of the substitutions identified in patients with CS has not been conducted. In the current study, we identified four mutations (p.G12S, p.G12A, p.G12C and p.G12D) in 21 patients and analyzed the associated clinical manifestations of CS in these individuals. To examine functional differences among the identified mutations, we characterized a total of nine HRAS mutants, including seven distinct substitutions in codons 12 and 13, p.K117R and p.A146T. The p.A146T mutant demonstrated the weakest Raf-binding activity, and the p.K117R and p.A146T mutants had weaker effects on downstream c-Jun N-terminal kinase signaling than did codon 12 or 13 mutants. We demonstrated that these mutant HRAS proteins induced senescence when overexpressed in human fibroblasts. Oncogene-induced senescence is a cellular reaction that controls cell proliferation in response to oncogenic mutation and it has been considered one of the tumor suppression mechanisms in vivo. Our findings suggest that the HRAS mutations identified in CS are sufficient to cause oncogene-induced senescence and that cellular senescence might therefore contribute to the pathogenesis of CS.
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Affiliation(s)
- Tetsuya Niihori
- Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan.
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Gripp KW, Hopkins E, Sol-Church K, Stabley DL, Axelrad ME, Doyle D, Dobyns WB, Hudson C, Johnson J, Tenconi R, Graham GE, Sousa AB, Heller R, Piccione M, Corsello G, Herman GE, Tartaglia M, Lin AE. Phenotypic analysis of individuals with Costello syndrome due to HRAS p.G13C. Am J Med Genet A 2011; 155A:706-16. [PMID: 21438134 DOI: 10.1002/ajmg.a.33884] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 12/14/2010] [Indexed: 11/06/2022]
Abstract
Costello syndrome is characterized by severe failure-to-thrive, short stature, cardiac abnormalities (heart defects, tachyarrhythmia, and hypertrophic cardiomyopathy (HCM)), distinctive facial features, a predisposition to papillomata and malignant tumors, postnatal cerebellar overgrowth resulting in Chiari 1 malformation, and cognitive disabilities. De novo germline mutations in the proto-oncogene HRAS cause Costello syndrome. Most mutations affect the glycine residues in position 12 or 13, and more than 80% of patients share p.G12S. To test the hypothesis that subtle genotype-phenotype differences exist, we report the first cohort comparison between 12 Costello syndrome individuals with p.G13C and individuals with p.G12S. The individuals with p.G13C had many typical findings including polyhydramnios, failure-to-thrive, HCM, macrocephaly with posterior fossa crowding, and developmental delay. Subjectively, their facial features were less coarse. Statistically significant differences included the absence of multifocal atrial tachycardia (P-value = 0.033), ulnar deviation of the wrist (P < 0.001) and papillomata (P = 0.003), and fewer neurosurgical procedures (P = 0.024). Fewer individuals with p.G13C had short stature (height below -2 SD) without use of growth hormone (P < 0.001). The noteworthy absence of malignant tumors did not reach statistical significance. Novel ectodermal findings were noted in individuals with p.G13C, including loose anagen hair resulting in easily pluckable hair with a matted appearance, different from the tight curls typical for most Costello syndrome individuals. Unusually long eye lashes requiring trimming are a novel finding we termed dolichocilia. These distinctive ectodermal findings suggest a cell type specific effect of this particular mutation. Additional patients are needed to validate these findings.
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Affiliation(s)
- Karen W Gripp
- Division of Medical Genetics, A. I. duPont Hospital for Children, Wilmington, Delaware, USA.
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Terhag J, Gottschling K, Hollmann M. The Transmembrane Domain C of AMPA Receptors is Critically Involved in Receptor Function and Modulation. Front Mol Neurosci 2010; 3:117. [PMID: 21206529 PMCID: PMC3009476 DOI: 10.3389/fnmol.2010.00117] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 11/30/2010] [Indexed: 11/13/2022] Open
Abstract
Ionotropic glutamate receptors are major players in synaptic transmission and are critically involved in many cognitive events. Although receptors of different subfamilies serve different functions, they all show a conserved domain topology. For most of these domains, structure–function relationships have been established and are well understood. However, up to date the role of the transmembrane domain C in receptor function has been investigated only poorly. We have constructed a series of receptor chimeras and point mutants designed to shed light on the structural and/or functional importance of this domain. We here present evidence that the role of transmembrane domain C exceeds that of a mere scaffolding domain and that several amino acid residues located within the domain are crucial for receptor gating and desensitization. Furthermore, our data suggest that the domain may be involved in receptor interaction with transmembrane AMPA receptor regulatory proteins.
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Affiliation(s)
- Jan Terhag
- Department of Biochemistry I - Receptor Biochemistry, Ruhr University Bochum Bochum, Germany
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35
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Girard N, Shen R, Guo T, Zakowski MF, Heguy A, Riely GJ, Huang J, Lau C, Lash AE, Ladanyi M, Viale A, Antonescu CR, Travis WD, Rusch VW, Kris MG, Pao W. Comprehensive genomic analysis reveals clinically relevant molecular distinctions between thymic carcinomas and thymomas. Clin Cancer Res 2009; 15:6790-9. [PMID: 19861435 DOI: 10.1158/1078-0432.ccr-09-0644] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
PURPOSE Thymomas and thymic carcinomas are rare intrathoracic malignancies that can be invasive and refractory to conventional treatment. Because these tumors both originate from the thymus, they are often grouped together clinically. However, whether the underlying biology of these tumors warrants such clustering is unclear, and the optimum treatment of either entity is unknown. EXPERIMENTAL DESIGN All thymic tumors were profiled for mutations in genes encoding components of the EGFR and KIT signaling pathways, assessed for EGFR and KIT expression by immunohistochemistry, and analyzed by array-based comparative genomic hybridization. Previously untreated tumors were subjected to global gene expression arrays. RESULTS We analyzed 45 thymic tumors [thymoma, n = 38 (type A, n = 8; type B2, n = 22; type B3, n = 8); thymic carcinoma, n = 7]. One thymoma and one thymic carcinoma harbored KRAS mutations (G12A and G12V, respectively), and one thymoma had a G13V HRAS mutation. Three tumors displayed strong KIT staining. Two thymic carcinomas harbored somatic KIT mutations (V560del and H697Y). In cell viability assays, the V560del mutant was associated with similar sensitivities to imatinib and sunitinib, whereas the H697Y mutant displayed greater sensitivity to sunitinib. Genomic profiling revealed distinct differences between type A to B2 thymomas versus type B3 and thymic carcinomas. Moreover, array-based comparative genomic hybridization could readily distinguish squamous cell carcinomas of the thymus versus the lung, which can often present a diagnostic challenge. CONCLUSIONS Comprehensive genomic analysis suggests that thymic carcinomas are molecularly distinct from thymomas. These data have clinical, pathologic, and therapeutic implications for the treatment of thymic malignancies.
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Affiliation(s)
- Nicolas Girard
- Human Oncology and Pathogenesis Program (HOPP, Weill Medical College of Cornell University, New York, New York, USA
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36
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Paquin A, Hordo C, Kaplan DR, Miller FD. Costello syndrome H-Ras alleles regulate cortical development. Dev Biol 2009; 330:440-51. [PMID: 19371735 DOI: 10.1016/j.ydbio.2009.04.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 03/04/2009] [Accepted: 04/07/2009] [Indexed: 11/16/2022]
Abstract
Genetic mutations in H-Ras cause Costello syndrome (CS), a complex developmental disorder associated with cortical abnormalities and profound mental retardation. Here, we have asked whether there are perturbations in precursor cell proliferation, differentiation, or survival as a consequence of expressing CS H-Ras alleles that could explain the cognitive deficits seen in this disorder. Two different H-Ras alleles encoding mutations present in CS patients, H-RasG12V and H-RasG12S were expressed in cortical progenitors in culture and in vivo by in utero electroporation and their effects on cortical precursor cell fate examined. Expression of both mutants in cultured precursors inhibited neurogenesis and promoted proliferation and astrogenesis. In vivo, expression of either form of CS H-Ras promoted cell proliferation and inhibited neurogenesis. Moreover, these H-Ras mutants promoted premature gliogenesis, causing formation of astrocytes at a time when normal gliogenesis has not yet begun, ultimately leading to an increase in the number of astrocytes postnatally. Thus, aberrant H-Ras activation enhances neural precursor cell proliferation, and perturbs the normal genesis of neurons and glial cells, effects that likely contribute to the cortical abnormalities and cognitive dysfunction seen in CS.
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Affiliation(s)
- Annie Paquin
- Stem Cell Biology Program, Hospital for Sick Children, Toronto, Canada
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37
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Noonan, Costello and cardio–facio–cutaneous syndromes: dysregulation of the Ras–MAPK pathway. Expert Rev Mol Med 2008; 10:e37. [DOI: 10.1017/s1462399408000902] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A class of developmental disorders caused by dysregulation of the Ras-induced mitogen-activated protein kinase (MAPK) cascade (the Ras–MAPK pathway) has emerged. Three of these disorders – Noonan, Costello and cardio–facio–cutaneous syndromes – have overlapping phenotypic features characterised by distinctive facial dysmorphia, cardiac defects, musculoskeletal and cutaneous abnormalities, and neurocognitive delay. The germline mutations associated with these disorders are in genes that encode proteins of the Ras–MAPK pathway. In vitro studies have determined that the overwhelming majority of these mutations result in increased signal transduction down the pathway, but usually to a lesser degree than somatic mutations in the same genes that are associated with cancer. The Ras–MAPK pathway is essential in the regulation of the cell cycle, differentiation, growth and senescence, so it is not surprising that germline mutations that affect its function have profound effects on development. Here we review the clinical consequences of the known molecular lesions associated with Noonan syndrome, Costello syndrome and cardio–facio–cutaneous syndrome, and explore possible therapeutic modalities for treatment.
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38
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Raepple D, von Lintig F, Zemojtel T, Duchniewicz M, Jung A, Lübbert M, Boss GR, Scheele JS. Determination of Ras-GTP and Ras-GDP in patients with acute myelogenous leukemia (AML), myeloproliferative syndrome (MPS), juvenile myelomonocytic leukemia (JMML), acute lymphocytic leukemia (ALL), and malignant lymphoma: assessment of mutational and indirect activation. Ann Hematol 2008; 88:319-24. [PMID: 18784923 PMCID: PMC2755762 DOI: 10.1007/s00277-008-0593-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Accepted: 08/05/2008] [Indexed: 11/30/2022]
Abstract
The 21-kD protein Ras of the low-molecular-weight GTP-binding (LMWG) family plays an important role in transduction of extracellular signals. Ras functions as a ‘molecular switch’ in transduction of signals from the membrane receptors of many growth factors, cytokines, and other second messengers to the cell nucleus. Numerous studies have shown that in multiple malignant tumors and hematopoietic malignancies, faulty signal transduction via the Ras pathway plays a key role in tumorigenesis. In this work, a non-radioactive assay was used to quantify Ras activity in hematologic malignancies. Ras activation was measured in six different cell lines and 24 patient samples, and sequence analysis of N- and K-ras was performed. The 24 patient samples comprised of seven acute myelogenous leukemia (AML) samples, five acute lymphocytic leukemia (ALL) samples, four myeloproliferative disease (MPD) samples, four lymphoma samples, four juvenile myelomonocytic leukemia (JMML) samples, and WBC from a healthy donor. The purpose of this study was to compare Ras activity determined by percentage of Ras-GTP with the mutational status of the Ras gene in the hematopoietic cells of the patients. Mutation analysis revealed ras mutations in two of the seven AML samples, one in codon 12 and one in codon 61; ras mutations were also found in two of the four JMML samples, and in one of the four lymphoma samples (codon 12). We found a mean Ras activation of 23.1% in cell lines with known constitutively activating ras mutations, which was significantly different from cell lines with ras wildtype sequence (Ras activation of 4.8%). Two of the five activating ras mutations in the patient samples correlated with increased Ras activation. In the other three samples, Ras was probably activated through “upstream” or “downstream” mechanisms.
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Affiliation(s)
- D Raepple
- Department of Medicine I, University of Freiburg Medical Center, Hugstetter Str. 55, 79106 Freiburg, Germany
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39
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Aoki Y, Niihori T, Narumi Y, Kure S, Matsubara Y. The RAS/MAPK syndromes: novel roles of the RAS pathway in human genetic disorders. Hum Mutat 2008; 29:992-1006. [DOI: 10.1002/humu.20748] [Citation(s) in RCA: 274] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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40
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The human homolog of fission yeast Rad17 is implicated in tumor growth. Cancer Lett 2008; 266:194-202. [PMID: 18378394 DOI: 10.1016/j.canlet.2008.02.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 02/19/2008] [Accepted: 02/20/2008] [Indexed: 11/21/2022]
Abstract
The Schizosaccharomyces pombe rad17 is a checkpoint protein critical for maintenance of genomic stability. Since the loss of checkpoint control is a common feature of tumor cells, we investigated the biological function of the human homolog hRAD17. Expression of hRAD17 in a fission yeast rad17 deleted strain reduced growth of yeast colonies and caused slower progression through cell cycle. Immunoprecipitated hRad17 exhibited exonuclease activity. hRAD17 delayed growth of NIH3T3 fibroblasts transformed by the H-ras oncogene in nude mice. Our results support that hRAD17, similarly to other human genes involved in checkpoint mechanisms, plays a role in control of tumor growth.
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41
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Genotype-phenotype correlation in cases of juvenile myelomonocytic leukemia with clonal RAS mutations. Blood 2008; 111:966-7; author reply 967-8. [PMID: 18182584 DOI: 10.1182/blood-2007-09-111831] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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42
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Abstract
Costello syndrome (CS) is a complex developmental disorder involving characteristic craniofacial features, failure to thrive, developmental delay, cardiac and skeletal anomalies and a predisposition to develop neoplasia, both benign and malignant. CS is caused by activating germline mutations in HRAS and belongs to an exciting class of genetic syndromes that are caused by perturbation of function through the Ras pathway. Some of these other syndromes include Noonan syndrome, LEOPARD syndrome, neurofibromatosis 1 and cardio-facio-cutaneous syndrome. Ras is a critical signaling hub in the cell and is activated by receptor tyrosine kinases, G-protein-coupled receptors, cytokine receptors and extracellular matrix receptors. The downstream effectors of Ras are many and control vital cellular functions including cell cycle progression, cell survival, motility, transcription, translation and membrane trafficking. Understanding the genetic etiology of CS is the first step in gaining insight to the role Ras plays in human development, cellular signaling and cancer pathogenesis.
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Affiliation(s)
- K A Rauen
- Department of Pediatrics, Division of Medical Genetics, University of California, San Francisco, CA 94115, USA.
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43
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van der Burgt I, Kupsky W, Stassou S, Nadroo A, Barroso C, Diem A, Kratz CP, Dvorsky R, Ahmadian MR, Zenker M. Myopathy caused by HRAS germline mutations: implications for disturbed myogenic differentiation in the presence of constitutive HRas activation. J Med Genet 2007; 44:459-62. [PMID: 17412879 PMCID: PMC2598013 DOI: 10.1136/jmg.2007.049270] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Rare reports on patients with congenital myopathy with excess of muscle spindles (CMEMS), hypertrophic cardiomyopathy and variable features resembling Noonan syndrome have been published, but the genetic basis of this condition is so far unknown. METHODS AND RESULTS We analysed PTPN11 and RAS genes in five unrelated patients with this phenotype, and found HRAS mutations in four of them. Two disease-associated mutations, G12V and G12S, have previously been observed in patients with Costello syndrome (CS), and two other mutations, E63K and Q22K, are novel. All four mutations are predicted to enhance downstream HRas signalling, suggesting that CMEMS is a developmental consequence of sustained HRas activation in skeletal muscle. CONCLUSION This type of myopathy may represent a previously unrecognized manifestation of CS. However, some patients carrying HRAS mutations may exhibit prominent congenital muscular dysfunction, although features of CS may be less obvious, suggesting that germline HRAS mutations may underlie some cases of otherwise unclassified neonatal neuromuscular disorders.
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44
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Matsuda K, Shimada A, Yoshida N, Ogawa A, Watanabe A, Yajima S, Iizuka S, Koike K, Yanai F, Kawasaki K, Yanagimachi M, Kikuchi A, Ohtsuka Y, Hidaka E, Yamauchi K, Tanaka M, Yanagisawa R, Nakazawa Y, Shiohara M, Manabe A, Kojima S, Koike K. Spontaneous improvement of hematologic abnormalities in patients having juvenile myelomonocytic leukemia with specific RAS mutations. Blood 2007; 109:5477-80. [PMID: 17332249 DOI: 10.1182/blood-2006-09-046649] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Of 11 children with juvenile myelomonocytic leukemia (JMML) carrying RAS mutations (8 with NRAS mutations, 3 with KRAS2 mutations), 5 had a profound elevation in either or both the white blood cells and spleen size at diagnosis. Three patients had no or modest hepatosplenomegaly and mild leukocytosis at presentation but subsequently showed a marked increase in spleen size with or without hematologic exacerbation, for which nonintensive chemotherapy was initiated. The other three patients with NRAS or KRAS2 glycine to serine substitution received no chemotherapy, but hematologic improvement has been observed during a 2- to 4-year follow up. In the third group, all hematopoietic cell lineages analyzed had the RAS mutations at the time of hematologic improvement, whereas DNA obtained from the nails had the wild type. Additionally, numbers of circulating granulocyte-macrophage progenitors were significantly reduced during the clinical course. Thus, some patients with JMML with specific RAS mutations may have spontaneously improving disease.
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Affiliation(s)
- Kazuyuki Matsuda
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan
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Affiliation(s)
- W Wallace Cleland
- Institute for Enzyme Research and Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA.
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Barral P, Batanero E, Villalba M, Rodríguez R. Expression of the major olive pollen allergen Ole e 10 in the yeast Pichia pastoris: evidence of post-translational modifications. Protein Expr Purif 2006; 44:147-54. [PMID: 15935694 DOI: 10.1016/j.pep.2005.04.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 04/14/2005] [Accepted: 04/18/2005] [Indexed: 11/24/2022]
Abstract
Olive pollen allergy is a clinical disorder that affects around 20% of the population in Mediterranean areas. The major olive pollen allergen, Ole e 10, is involved in cross-reactivity phenomena and asthma induction in allergic patients, and, besides its clinical interest, Ole e 10 is the first member of a new family of plant proteins. Ole e 10-specific cDNA has been cloned in the plasmid pPICZalphaA and expressed in the methylotrophic yeast Pichia pastoris. The recombinant protein has been purified in a two chromatographic-step procedure. N-Terminal sequencing, mass spectrometry, IgG, and IgE binding assays were employed to characterize the recombinant allergen. These analyses revealed that the product undergoes a proteolytic cleavage in the N-terminal end with the loss of the first six residues. Different strategies were used to solve this problem, such as changes in the fermentation conditions and the employment of protease-deficient yeast strains. Proteolytic cleavage was minimized and about 51% of rOle e 10 was obtained as a full-length protein. Moreover, a covalent modification was found in the N-terminal end of the full-length rOle e 10. Peptide mapping and mass spectrometry analyses pointed to the existence of a phosphorylation located in a serine residue of the N-terminal segment of rOle e 10 and it was confirmed after treatment of the sample with alkaline phosphatase. Finally, both full-length and truncated rOle e 10 retained most of the IgG- and IgE-binding capabilities of the natural protein isolated from the pollen.
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Affiliation(s)
- Patricia Barral
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain
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Estep AL, Tidyman WE, Teitell MA, Cotter PD, Rauen KA. HRAS mutations in Costello syndrome: detection of constitutional activating mutations in codon 12 and 13 and loss of wild-type allele in malignancy. Am J Med Genet A 2006; 140:8-16. [PMID: 16372351 DOI: 10.1002/ajmg.a.31078] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Costello syndrome (CS) is a complex developmental disorder involving characteristic craniofacial features, failure to thrive, developmental delay, cardiac and skeletal anomalies, and a predisposition to develop neoplasia. Based on similarities with other cancer syndromes, we previously hypothesized that CS is likely due to activation of signal transduction through the Ras/MAPK pathway [Tartaglia et al., 2003]. In this study, the HRAS coding region was sequenced for mutations in a large, well-characterized cohort of 36 CS patients. Heterogeneous missense point mutations predicting an amino acid substitution were identified in 33/36 (92%) patients. The majority (91%) had a 34G --> A transition in codon 12. Less frequent mutations included 35G --> C (codon 12) and 37G --> T (codon 13). Parental samples did not have an HRAS mutation supporting the hypothesis of de novo heterogeneous mutations. There is phenotypic variability among patients with a 34G --> A transition. The most consistent features included characteristic facies and skin, failure to thrive, developmental delay, musculoskeletal abnormalities, visual impairment, cardiac abnormalities, and generalized hyperpigmentation. The two patients with 35G --> C had cardiac arrhythmias whereas one patient with a 37G --> T transversion had an enlarged aortic root. Of the patients with a clinical diagnosis of CS, neoplasia was the most consistent phenotypic feature for predicating an HRAS mutation. To gain an understanding of the relationship between constitutional HRAS mutations and malignancy, HRAS was sequenced in an advanced biphasic rhabdomyosarcoma/fibrosarcoma from an individual with a 34G --> A mutation. Loss of the wild-type HRAS allele was observed, suggesting tumorigenesis in CS patients is accompanied by additional somatic changes affecting HRAS. Finally, due to phenotypic overlap between CS and cardio-facio-cutaneous (CFC) syndromes, the HRAS coding region was sequenced in a well-characterized CFC cohort. No mutations were found which support a distinct genetic etiology between CS and CFC syndromes.
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Affiliation(s)
- Anne L Estep
- Comprehensive Cancer Center, Cancer Research Institute, University of California-San Francisco, 2340 Sutter Street, San Francisco, CA 94115, USA
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McIntyre GI. Cell hydration as the primary factor in carcinogenesis: A unifying concept. Med Hypotheses 2005; 66:518-26. [PMID: 16271440 DOI: 10.1016/j.mehy.2005.09.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 09/09/2005] [Accepted: 09/12/2005] [Indexed: 11/18/2022]
Abstract
The paper discusses the unifying concept that cell hydration is the primary factor in the mechanism of carcinogenesis. The concept includes the following hypotheses: (1) Increased cell hydration causes cancer not only by promoting cell division and oncogene expression, but also by inactivating genes inducing cell differentiation, and by preventing apoptosis. Conversely, factors that reduce cell hydration prevent cancer by inhibiting cell division and oncogene expression, while activating genes inducing cell differentiation, and by promoting apoptosis. The unique ability of cell hydration to have these opposite effects on cell behavior and gene expression can account for its postulated role as the primary factor in both the promotion and prevention of cancer. (2) A progressive increase in cell hydration, induced by successive mutations and/or epigenetic changes, is the basic mechanism of multi-step carcinogenesis, the degree of malignancy increasing with the degree of cell hydration. (3) The increased hydration of cancer cells accelerates their respiration rate, thereby enhancing their ability to compete for nutrients with their normal counterparts. This effect may play a major role in promoting tumor growth and in the postulated mechanism of multi-step carcinogenesis. (4) Increased cell hydration is also proposed as an alternative or additional explanation of the carcinogenetic effect of inflammatory agents and of hormones. A survey of the literature provides evidence consistent with these hypotheses, but suggestions are included for further investigations to test their validity and their implications. From a clinical perspective, the abnormally high water content of cancer cells permits the use of microwave technology for tumor detection and treatment. Also of considerable therapeutic significance is the increased sensitivity if cancer cells to desiccation, postulated to result from genetic changes induced by increased hydration. This may well be the achilles heel of cancer, and recent investigations indicate that it may be exploited very effectively in the treatment of the disease. In conclusion, I suggest that the need for studies on the molecular biology of cancer to be supplemented by more information on environmental effects on gene expression and on the biochemical and physiological factors that mediate genetic effects at the cellular level. This approach might also be used to assess the validity of the postulated role of cell hydration as a factor of particular significance.
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Aoki Y, Niihori T, Kawame H, Kurosawa K, Ohashi H, Tanaka Y, Filocamo M, Kato K, Suzuki Y, Kure S, Matsubara Y. Germline mutations in HRAS proto-oncogene cause Costello syndrome. Nat Genet 2005; 37:1038-40. [PMID: 16170316 DOI: 10.1038/ng1641] [Citation(s) in RCA: 507] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Accepted: 07/27/2005] [Indexed: 11/09/2022]
Abstract
Costello syndrome is a multiple congenital anomaly and mental retardation syndrome characterized by coarse face, loose skin, cardiomyopathy and predisposition to tumors. We identified four heterozygous de novo mutations of HRAS in 12 of 13 affected individuals, all of which were previously reported as somatic and oncogenic mutations in various tumors. Our observations suggest that germline mutations in HRAS perturb human development and increase susceptibility to tumors.
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Affiliation(s)
- Yoko Aoki
- Department of Medical Genetics, Tohoku University School of Medicine, 1-1 Seiryo-machi, Sendai 980-8574, Japan.
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Vizan P, Boros LG, Figueras A, Capella G, Mangues R, Bassilian S, Lim S, Lee WNP, Cascante M. K-ras codon-specific mutations produce distinctive metabolic phenotypes in NIH3T3 mice [corrected] fibroblasts. Cancer Res 2005; 65:5512-5. [PMID: 15994921 DOI: 10.1158/0008-5472.can-05-0074] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Among K-ras mutations, codon 12 mutations have been identified as those conferring a more aggressive phenotype. This aggressiveness is primarily associated with slow proliferation but greatly increased resistance to apoptosis. Using transfected NIH3T3 fibroblasts with a mutated K-ras minigene either at codon 12 (K12) or at codon 13 (K13), and taking advantage of [1,2-13C2]glucose tracer labeling, we show that codon 12 mutant K-ras (K12)-transformed cells exhibit greatly increased glycolysis with only a slight increase in activity along pathways that produce nucleic acid and lipid synthesis precursors in the oxidative branch of the pentose phosphate pathway and via pyruvate dehydrogenase flux. K13 mutants display a modest increase in anaerobic glycolysis associated with a large increase in oxidative pentose phosphate pathway activity and pyruvate dehydrogenase flux. The distinctive differences in metabolic profiles of K12 and K13 codon mutated cells indicate that a strong correlation exists between the flow of glucose carbons towards either increased anaerobic glycolysis, and resistance to apoptosis (K12), or increased macromolecule synthesis, rapid proliferation, and increased sensitivity to apoptosis.
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Affiliation(s)
- Pedro Vizan
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Spain
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