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Broadaway KA, Yin X, Williamson A, Parsons VA, Wilson EP, Moxley AH, Vadlamudi S, Varshney A, Jackson AU, Ahuja V, Bornstein SR, Corbin LJ, Delgado GE, Dwivedi OP, Fernandes Silva L, Frayling TM, Grallert H, Gustafsson S, Hakaste L, Hammar U, Herder C, Herrmann S, Højlund K, Hughes DA, Kleber ME, Lindgren CM, Liu CT, Luan J, Malmberg A, Moissl AP, Morris AP, Perakakis N, Peters A, Petrie JR, Roden M, Schwarz PEH, Sharma S, Silveira A, Strawbridge RJ, Tuomi T, Wood AR, Wu P, Zethelius B, Baldassarre D, Eriksson JG, Fall T, Florez JC, Fritsche A, Gigante B, Hamsten A, Kajantie E, Laakso M, Lahti J, Lawlor DA, Lind L, März W, Meigs JB, Sundström J, Timpson NJ, Wagner R, Walker M, Wareham NJ, Watkins H, Barroso I, O'Rahilly S, Grarup N, Parker SC, Boehnke M, Langenberg C, Wheeler E, Mohlke KL. Loci for insulin processing and secretion provide insight into type 2 diabetes risk. Am J Hum Genet 2023; 110:284-299. [PMID: 36693378 PMCID: PMC9943750 DOI: 10.1016/j.ajhg.2023.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 01/03/2023] [Indexed: 01/25/2023] Open
Abstract
Insulin secretion is critical for glucose homeostasis, and increased levels of the precursor proinsulin relative to insulin indicate pancreatic islet beta-cell stress and insufficient insulin secretory capacity in the setting of insulin resistance. We conducted meta-analyses of genome-wide association results for fasting proinsulin from 16 European-ancestry studies in 45,861 individuals. We found 36 independent signals at 30 loci (p value < 5 × 10-8), which validated 12 previously reported loci for proinsulin and ten additional loci previously identified for another glycemic trait. Half of the alleles associated with higher proinsulin showed higher rather than lower effects on glucose levels, corresponding to different mechanisms. Proinsulin loci included genes that affect prohormone convertases, beta-cell dysfunction, vesicle trafficking, beta-cell transcriptional regulation, and lysosomes/autophagy processes. We colocalized 11 proinsulin signals with islet expression quantitative trait locus (eQTL) data, suggesting candidate genes, including ARSG, WIPI1, SLC7A14, and SIX3. The NKX6-3/ANK1 proinsulin signal colocalized with a T2D signal and an adipose ANK1 eQTL signal but not the islet NKX6-3 eQTL. Signals were enriched for islet enhancers, and we showed a plausible islet regulatory mechanism for the lead signal in the MADD locus. These results show how detailed genetic studies of an intermediate phenotype can elucidate mechanisms that may predispose one to disease.
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Affiliation(s)
- K Alaine Broadaway
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | - Xianyong Yin
- Department of Biostatistics, University of Michigan, Ann Arbor, MI, USA; Center for Statistical Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Alice Williamson
- MRC Epidemiology Unit, Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, UK; University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Department of Clinical Biochemistry, University of Cambridge, Cambridge, UK
| | - Victoria A Parsons
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | - Emma P Wilson
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | - Anne H Moxley
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | | | - Arushi Varshney
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Anne U Jackson
- Center for Statistical Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Vasudha Ahuja
- Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland
| | - Stefan R Bornstein
- Department of Internal Medicine, Metabolic and Vascular Medicine, MedicCal Faculty Carl Gustav Carus, Dresden, Germany; Helmholtz Zentrum München, Paul Langerhans Institute Dresden, University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Laura J Corbin
- Medical Research Council Integrative Epidemiology Unit at the University of Bristol, Bristol, UK; Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | | | - Om P Dwivedi
- University of Helsinki, Helsinki, Finland; Folkhälsan Research Center, Helsinki, Finland
| | | | | | - Harald Grallert
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany; Institute of Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Stefan Gustafsson
- Department of Medical Sciences, Clinical Epidemiology, Uppsala University, Uppsala, Sweden
| | - Liisa Hakaste
- Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland
| | - Ulf Hammar
- Department of Medical Sciences, Molecular Epidemiology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Christian Herder
- German Center for Diabetes Research, Neuherberg, Germany; Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Department of Endocrinology and Diabetology, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sandra Herrmann
- Department of Internal Medicine, Prevention and Care of Diabetes, Medical Faculty Carl Gustav Carus, Dresden, Germany; Helmholtz Zentrum München, Paul Langerhans Institute Dresden, University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany
| | | | - David A Hughes
- Medical Research Council Integrative Epidemiology Unit at the University of Bristol, Bristol, UK; Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Marcus E Kleber
- Medical Faculty Mannheim, Heidelberg University, Mannheim, BW, Germany; SYNLAB MVZ Humangenetik Mannheim, Mannheim, BW, Germany
| | - Cecilia M Lindgren
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK; Nuffield Department of Population Health, University of Oxford, Oxford, UK; Wellcome Trust Centre Human Genetics, University of Oxford, Oxford, UK; Broad Institute, Cambridge, MA, USA
| | - Ching-Ti Liu
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Jian'an Luan
- MRC Epidemiology Unit, Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, UK
| | - Anni Malmberg
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Angela P Moissl
- Institute of Nutritional Sciences, Friedrich-Schiller-University, Jena, Germany; Competence Cluster for Nutrition and Cardiovascular Health, Halle-Jena-Leipzig, Germany; Medical Faculty Mannheim, Heidelberg University, Mannheim, BW, Germany
| | - Andrew P Morris
- Centre for Genetics and Genomics Versus Arthritis, Centre for Musculoskeletal Research, The University of Manchester, Manchester, UK
| | - Nikolaos Perakakis
- Department of Internal Medicine, Metabolic and Vascular Medicine, MedicCal Faculty Carl Gustav Carus, Dresden, Germany; Helmholtz Zentrum München, Paul Langerhans Institute Dresden, University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Annette Peters
- Institute of Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - John R Petrie
- School of Health and Wellbeing, University of Glasgow, Glasgow, UK
| | - Michael Roden
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Department of Endocrinology and Diabetology, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Peter E H Schwarz
- Department of Internal Medicine, Prevention and Care of Diabetes, Medical Faculty Carl Gustav Carus, Dresden, Germany; Helmholtz Zentrum München, Paul Langerhans Institute Dresden, University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Sapna Sharma
- German Center for Diabetes Research, Neuherberg, Germany; Research Unit of Molecular Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany; Institute of Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany; Chair of Food Chemistry and Molecular Sensory Science, Technische Universität München, Freising, Germany
| | - Angela Silveira
- Department of Medicine Solna, Division of Cardiovascular Medicine, Karolinska Institutet, Stockholm, Sweden; Oxford Biomedical Research Centre, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Rona J Strawbridge
- Institute of Health and Wellbeing, Mental Health and Wellbeing, University of Glasgow, Glasgow, UK; Department of Medicine Solna, Division of Cardiovascular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Tiinamaija Tuomi
- Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland; Folkhälsan Research Center, Helsinki, Finland; Abdominal Center, Endocrinology, Helsinki University Hospital, Helsinki, Finland
| | - Andrew R Wood
- Genetics of Complex Traits, College of Medicine and Health, University of Exeter, Exeter, UK
| | - Peitao Wu
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Björn Zethelius
- Department of Geriatrics, Uppsala University, Uppsala, Sweden
| | - Damiano Baldassarre
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy; Cardiovascular Prevention Area, Centro Cardiologico Monzino I.R.C.C.S., Milan, Italy
| | - Johan G Eriksson
- Department of General Practice and Primary Health Care, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Folkhälsan Research Centre, Helsinki, Finland; Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore
| | - Tove Fall
- Department of Medical Sciences, Molecular Epidemiology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Jose C Florez
- Diabetes Unit and Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA; Programs in Metabolism and Medical & Population Genetics, Broad Institute, Cambridge, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Andreas Fritsche
- Department of Internal Medicine, Diabetology, Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University of Tübingen, Tübingen, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Bruna Gigante
- Department of Medicine Solna, Division of Cardiovascular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Anders Hamsten
- Department of Medicine Solna, Division of Cardiovascular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Eero Kajantie
- Population Health Unit, Finnish Institute for Health and Welfare, Helsinki, Finland; PEDEGO Research Unit, MRC Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland; Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway; Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Markku Laakso
- Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
| | - Jari Lahti
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Deborah A Lawlor
- Medical Research Council Integrative Epidemiology Unit at the University of Bristol, Bristol, UK; Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Lars Lind
- Department of Medical Sciences, Clinical Epidemiology, Uppsala University, Uppsala, Sweden
| | - Winfried März
- Synlab Academy, SYNLAB Holding Deutschland GmbH, Mannheim, BW, Germany; Medical Faculty Mannheim, Heidelberg University, Mannheim, BW, Germany
| | - James B Meigs
- Department of Medicine, Division of General Internal Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA; Program in Medical and Population Genetics, Broad Institute, Cambridge, MA, USA
| | - Johan Sundström
- Department of Medical Sciences, Clinical Epidemiology, Uppsala University, Uppsala, Sweden
| | - Nicholas J Timpson
- Medical Research Council Integrative Epidemiology Unit at the University of Bristol, Bristol, UK; Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Robert Wagner
- Department of Internal Medicine, Diabetology, Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University of Tübingen, Tübingen, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Mark Walker
- Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Nicholas J Wareham
- MRC Epidemiology Unit, Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, UK; Health Data Research UK, Gibbs Building, London, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Inês Barroso
- Exeter Centre of Excellence for Diabetes Research, Genetics of Complex Traits, University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Stephen O'Rahilly
- MRC Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | - Niels Grarup
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stephen Cj Parker
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA; Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA; Department of Biostatistics, University of Michigan, Ann Arbor, MI, USA
| | - Michael Boehnke
- Department of Biostatistics, University of Michigan, Ann Arbor, MI, USA; Center for Statistical Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Claudia Langenberg
- MRC Epidemiology Unit, Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, UK; Computational Medicine, Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Berlin, Germany; Precision Healthcare University Research Institute, Queen Mary University of London, London, UK
| | - Eleanor Wheeler
- MRC Epidemiology Unit, Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, UK.
| | - Karen L Mohlke
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA.
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Hong KW, Kim SH, Zhang X, Park S. Interactions among the variants of insulin-related genes and nutrients increase the risk of type 2 diabetes. Nutr Res 2018; 51:82-92. [PMID: 29673546 DOI: 10.1016/j.nutres.2017.12.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 12/27/2017] [Accepted: 12/29/2017] [Indexed: 01/14/2023]
Abstract
Asians easily develops type 2 diabetes (T2DM) since they have insufficient glucose-stimulated insulin secretion (GSIS) in insulin resistant states. Since this may be associated with genetic background, the hypothesis of this study was that inter-genetic and gene-nutrient interactions may explain the low insulin secretory capacity of Asians. Accordingly, we identified the best gene-gene and gene-nutrient interactions using generalized multifactor dimensionality reduction (GMDR) in a large Korean cohort (n=8,842). Initially, we used 105 genetic variants associated with GSIS to identify the best gene-gene interaction model using the GMDR method. The best model included six SNPs, FNBP1L-rs4847428, FNBP1L-rs23766, GLIS3-rs2027393, GLIS3-rs3892354, GLIS3-rs486163 and DLC1-rs17093957. For each individual, we obtained the genetic risk scores based on the best model (GRSBM) to predict the GSIS levels. The GRSBM were divided into low, medium and high groups, and the association between T2DM and the GRSBM was measured using logistic regression. We analyzed the interaction between the GRSBM and the nutrition intakes. The adjusted odds ratios for T2DM risk increased by 1.701 fold in the high-score group compared to the low-score group. HOMA-B, an index of insulin secretion capacity, but not insulin resistance index was much lower in the high-score group than the low-score group. The association between the GRSBM and T2DM risk was greater in subjects with high energy intakes and low Ca intake, than those with low energy intake and high Ca intake. The high-score group was susceptible to T2DM incidence due to lower GSIS than the low-score group especially in subjects with high energy intake. In conclusion, the hypothesis of the study was accepted. These findings suggested that individuals with high GRSBM of the 6 genes in the model should avoid diets in high energy and low in calcium (<500 mg/day) to protect against T2DM.
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Affiliation(s)
- Kyung-Won Hong
- Division of Personal Genome Service, Theragen Etex Bio Institute Co., Ltd., Suwon, Gyeonggi, South Korea
| | - Sung Hoon Kim
- Division of Endocrinology & Metabolism, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, South Korea
| | - Xin Zhang
- Dept. of Food and Nutrition, Obesity/Diabetes Research Center, Hoseo University, Asan, South Korea
| | - Sunmin Park
- Dept. of Food and Nutrition, Obesity/Diabetes Research Center, Hoseo University, Asan, South Korea.
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Tripathi BK, Grant T, Qian X, Zhou M, Mertins P, Wang D, Papageorge AG, Tarasov SG, Hunter KW, Carr SA, Lowy DR. Receptor tyrosine kinase activation of RhoA is mediated by AKT phosphorylation of DLC1. J Cell Biol 2017; 216:4255-4270. [PMID: 29114068 PMCID: PMC5716279 DOI: 10.1083/jcb.201703105] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 07/26/2017] [Accepted: 09/01/2017] [Indexed: 01/04/2023] Open
Abstract
A new common mechanism for increasing RhoA-GTP is identified in Tripathi et al. The increased RhoA-GTP results from signaling mechanisms that phosphorylate and attenuate the DLC1 tumor suppressor, which encodes RhoGAP. The potentially reversible nature of this attenuation may have therapeutic relevance in cancer. We report several receptor tyrosine kinase (RTK) ligands increase RhoA–guanosine triphosphate (GTP) in untransformed and transformed cell lines and determine this phenomenon depends on the RTKs activating the AKT serine/threonine kinase. The increased RhoA-GTP results from AKT phosphorylating three serines (S298, S329, and S567) in the DLC1 tumor suppressor, a Rho GTPase-activating protein (RhoGAP) associated with focal adhesions. Phosphorylation of the serines, located N-terminal to the DLC1 RhoGAP domain, induces strong binding of that N-terminal region to the RhoGAP domain, converting DLC1 from an open, active dimer to a closed, inactive monomer. That binding, which interferes with the interaction of RhoA-GTP with the RhoGAP domain, reduces the hydrolysis of RhoA-GTP, the binding of other DLC1 ligands, and the colocalization of DLC1 with focal adhesions and attenuates tumor suppressor activity. DLC1 is a critical AKT target in DLC1-positive cancer because AKT inhibition has potent antitumor activity in the DLC1-positive transgenic cancer model and in a DLC1-positive cancer cell line but not in an isogenic DLC1-negative cell line.
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Affiliation(s)
- Brajendra K Tripathi
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Tiera Grant
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Xiaolan Qian
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Ming Zhou
- Laboratory of Proteomics and Analytical Technologies, Frederick National Laboratory for Cancer Research, Frederick, MD
| | | | - Dunrui Wang
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Alex G Papageorge
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Sergey G Tarasov
- Structural Biophysics Laboratory, National Cancer Institute, Frederick, MD
| | - Kent W Hunter
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | | | - Douglas R Lowy
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
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Chai R, Fu H, Zheng Z, Liu T, Ji S, Li G. Resveratrol inhibits proliferation and migration through SIRT1 mediated post‑translational modification of PI3K/AKT signaling in hepatocellular carcinoma cells. Mol Med Rep 2017; 16:8037-8044. [PMID: 28983625 PMCID: PMC5779887 DOI: 10.3892/mmr.2017.7612] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 09/12/2017] [Indexed: 01/29/2023] Open
Abstract
Resveratrol (RES), a polyphenolic compound present in grapes and red wine, has potential anticancer properties. The present study aimed to examine the effects of resveratrol and its underlying mechanism on hepatocellular carcinoma (HCC) cell lines HepG2, Bel‑7402 and SMMC‑7721. It was demonstrated that resveratrol inhibited the viability and proliferation of HCC cells assessed by MTT and EdU assays. TUNEL assay revealed that resveratrol induced cell apoptosis by increasing HCC apoptosis rate from 3±0.78% to 16±1.12% with upregulation of B‑cell lymphoma (Bcl)‑2 associated X, apoptosis regulator and cleaved‑poly (ADP‑Ribose) polymerase 1 (PARP), and downregulation of Bcl‑2, caspase‑3, caspase‑7 and PARP. As a sirtuin (SIRT) 1 activator, resveratrol elevated SIRT1 protein expression and its enzyme activity and decreased expression levels of phosphorylated (p)‑phosphoinositide‑3‑kinase (PI3K), p‑AKT Serine/Threonine Kinase 1 (AKT), and its downstream target p‑Forkhead Box O3a in HepG2 cells. Furthermore, inhibition of SIRT1 enzymatic activity by EX527 resulted in increased phosphorylation levels of PI3K and AKT. This demonstrated that resveratrol inhibited the PI3K/AKT pathway by SIRT1 activation. In addition to inhibition of cancer cell migration, tumor suppressor gene DLC1 Rho GTPase activating protein level was upregulated and its phosphorylation was enhanced by AKT with resveratrol treatment. These findings suggested that resveratrol inhibits proliferation and migration through SIRT1 mediated post‑translational modification of PI3K/AKT pathway in HCC cells.
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Affiliation(s)
- Rongfei Chai
- Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, P.R. China
| | - Huiling Fu
- Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, P.R. China
| | - Zhaodi Zheng
- Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, P.R. China
| | - Tingting Liu
- Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, P.R. China
| | - Shuhua Ji
- Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, P.R. China
| | - Guorong Li
- Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, P.R. China
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Ko FCF, Ping Yam JW. Regulation of deleted in liver cancer 1 tumor suppressor by protein-protein interactions and phosphorylation. Int J Cancer 2013; 135:264-9. [DOI: 10.1002/ijc.28505] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 09/16/2013] [Indexed: 12/26/2022]
Affiliation(s)
- Frankie Chi Fat Ko
- Department of Pathology and Centre for Cancer Research; Li Ka Shing Faculty of Medicine, State Key Laboratory for Liver Research, The University of Hong Kong; Hong Kong
| | - Judy Wai Ping Yam
- Department of Pathology and Centre for Cancer Research; Li Ka Shing Faculty of Medicine, State Key Laboratory for Liver Research, The University of Hong Kong; Hong Kong
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Dai Z, Jin Y. Promoter methylation of the DLC‑1 gene and its inhibitory effect on human colon cancer. Oncol Rep 2013; 30:1511-7. [PMID: 23783552 DOI: 10.3892/or.2013.2551] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Accepted: 06/07/2013] [Indexed: 11/05/2022] Open
Abstract
Deleted in liver cancer‑1 (DLC‑1), a candidate tumor suppressor gene which is inactive in liver carcinogenesis, is located at 8p21.3, where deletions are frequently found in several types of human cancer. Promoter hypermethylation is an epigenetic mechanism leading to silencing of the gene expression, which may be the primary cause for the absence of DLC‑1. We investigated the expression of the DLC‑1 gene and the methylation of the DLC‑1 gene in colon cancer cell lines (Caco‑2, LoVo and HT‑29). The data showed that reduced or undetectable levels of DLC‑1 mRNA were found in HT‑29 by reverse transcription-polymerase chain reaction (RT‑PCR). By contrast, the DLC‑1 gene was significantly expressed in Caco‑2 and LoVo cells. These findings were in agreement with the data obtained from western blot analysis. To further determine whether aberrant methylation is a contributing factor to transcriptional inactivation of DLC‑1 in HT‑29, the methylation of promoter was examined using methylation‑specific PCR and sodium bisulfite genomic sequencing in LoVo and HT‑29 cells, which suggests that promoter hypermethylation accounts for silencing of the DLC‑1 gene in HT‑29 cells. Since DLC‑1 is a candidate tumor suppressor gene, we sought to determine whether DLC‑1 expression is associated with cell proliferation in colon cancer cell lines. RNA interference techniques were adopted to inhibit DLC‑1 expression in the LoVo cell line and resulted in inhibition of cell growth and reduced colony formation. Collectively, our observations suggest that hypermethylation is responsible for abrogating the function of the DLC‑1 gene in colon cancer and indicate a role of DLC‑1 in colon carcinogenesis.
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Affiliation(s)
- Zhensheng Dai
- Department of Hematology‑Oncology, Shanghai Pudong Hospital Affiliated to Fudan University, Shanghai 201399, P.R. China
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Zimonjic DB, Popescu NC. Role of DLC1 tumor suppressor gene and MYC oncogene in pathogenesis of human hepatocellular carcinoma: potential prospects for combined targeted therapeutics (review). Int J Oncol 2012; 41:393-406. [PMID: 22580498 PMCID: PMC3583004 DOI: 10.3892/ijo.2012.1474] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 02/17/2012] [Indexed: 02/07/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is the third leading cause of cancer death, and its incidence is increasing worldwide in an alarming manner. The development of curative therapy for advanced and metastatic HCC is a high clinical priority. The HCC genome is complex and heterogeneous; therefore, the identification of recurrent genomic and related gene alterations is critical for developing clinical applications for diagnosis, prognosis and targeted therapy of the disease. This article focuses on recent research progress and our contribution in identifying and deciphering the role of defined genetic alterations in the pathogenesis of HCC. A significant number of genes that promote or suppress HCC cell growth have been identified at the sites of genomic reorganization. Notwithstanding the accumulation of multiple genetic alterations, highly recurrent changes on a single chromosome can alter the expression of oncogenes and tumor suppressor genes (TSGs) whose deregulation may be sufficient to drive the progression of normal hepatocytes to malignancy. A distinct and highly recurrent pattern of genomic imbalances in HCC includes the loss of DNA copy number (associated with loss of heterozygosity) of TSG-containing chromosome 8p and gain of DNA copy number or regional amplification of protooncogenes on chromosome 8q. Even though 8p is relatively small, it carries an unusually large number of TSGs, while, on the other side, several oncogenes are dispersed along 8q. Compelling evidence demonstrates that DLC1, a potent TSG on 8p, and MYC oncogene on 8q play a critical role in the pathogenesis of human HCC. Direct evidence for their role in the genesis of HCC has been obtained in a mosaic mouse model. Knockdown of DLC1 helps MYC in the induction of hepatoblast transformation in vitro, and in the development of HCC in vivo. Therapeutic interventions, which would simultaneously target signaling pathways governing both DLC1 and MYC functions in hepatocarcinogenesis, could result in progress in the treatment of liver cancer.
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Affiliation(s)
- Drazen B Zimonjic
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Chan LK, Ko FCF, Sze KMF, Ng IOL, Yam JWP. Nuclear-targeted deleted in liver cancer 1 (DLC1) is less efficient in exerting its tumor suppressive activity both in vitro and in vivo. PLoS One 2011; 6:e25547. [PMID: 21966542 PMCID: PMC3180446 DOI: 10.1371/journal.pone.0025547] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 09/06/2011] [Indexed: 01/01/2023] Open
Abstract
Background Deleted in liver cancer 1 (DLC1) serves as an important RhoGTPase activating protein (RhoGAP) protein that terminates active RhoA signaling in human cancers. Increasing evidence has demonstrated that the tumor suppressive activity of DLC1 depends not only on RhoGAP activity, but also relies on proper focal adhesion localization through its interaction with tensin family proteins. Recently, there are reports showing that DLC1 can also be found in the nucleus; however, the existence and the relative tumor suppressive activity of nuclear DLC1 have never been clearly addressed. Methodology and Principal Findings We herein provide new evidence that DLC1 protein, which predominantly associated with focal adhesions and localized in cytosol, dynamically shuttled between cytoplasm and nucleus. Treatment of cells with nuclear export blocker, Leptomycin B (LMB), retained DLC1 in the nucleus. To understand the nuclear entry of DLC1, we identified amino acids 600–700 of DLC1 as a novel region that is important for its nuclear localization. The tumor suppressive activity of nuclear DLC1 was directly assessed by employing a nuclear localization signal (NLS) fusion variant of DLC1 (NLS-DLC1) with preferential nuclear localization. In SMMC-7721 HCC cells, expression of NLS-DLC1 failed to suppress colony formation and actin stress fiber formation in vitro. The abrogated tumor suppressive activity of nuclear DLC1 was demonstrated for the first time in vivo by subcutaneously injecting p53−/− RasV12 hepatoblasts with stable NLS-DLC1 expression in nude mice. The injected hepatoblasts with NLS-DLC1 expression effectively formed tumors when compared with the non-nuclear targeted DLC1. Conclusions/Significance Our study identified a novel region responsible for the nuclear entry of DLC1 and demonstrated the functional difference of DLC1 in different cellular compartments both in vitro and in vivo.
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Affiliation(s)
- Lo-Kong Chan
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong
- Centre for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Frankie Chi Fat Ko
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong
- Centre for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Karen Man-Fong Sze
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong
| | - Irene Oi-Lin Ng
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong
- Centre for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- * E-mail: (JWPY); (IO-LN)
| | - Judy Wai Ping Yam
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong
- Centre for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- * E-mail: (JWPY); (IO-LN)
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9
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Hers I, Vincent EE, Tavaré JM. Akt signalling in health and disease. Cell Signal 2011; 23:1515-27. [PMID: 21620960 DOI: 10.1016/j.cellsig.2011.05.004] [Citation(s) in RCA: 1078] [Impact Index Per Article: 82.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 05/09/2011] [Indexed: 11/25/2022]
Abstract
Akt (also known as protein kinase B or PKB) comprises three closely related isoforms Akt1, Akt2 and Akt3 (or PKBα/β/γ respectively). We have a very good understanding of the mechanisms by which Akt isoforms are activated by growth factors and other extracellular stimuli as well as by oncogenic mutations in key upstream regulatory proteins including Ras, PI3-kinase subunits and PTEN. There are also an ever increasing number of Akt substrates being identified that play a role in the regulation of the diverse array of biological effects of activated Akt; this includes the regulation of cell proliferation, survival and metabolism. Dysregulation of Akt leads to diseases of major unmet medical need such as cancer, diabetes, cardiovascular and neurological diseases. As a result there has been substantial investment in the development of small molecular Akt inhibitors that act competitively with ATP or phospholipid binding, or allosterically. In this review we will briefly discuss our current understanding of how Akt isoforms are regulated, the substrate proteins they phosphorylate and how this integrates with the role of Akt in disease. We will furthermore discuss the types of Akt inhibitors that have been developed and are in clinical trials for human cancer, as well as speculate on potential on-target toxicities, such as disturbances of heart and vascular function, metabolism, memory and mood, which should be monitored very carefully during clinical trial.
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Affiliation(s)
- Ingeborg Hers
- School of Physiology and Pharmacology, University of Bristol, UK
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10
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Ko FCF, Chan LK, Tung EKK, Lowe SW, Ng IOL, Yam JWP. Akt phosphorylation of deleted in liver cancer 1 abrogates its suppression of liver cancer tumorigenesis and metastasis. Gastroenterology 2010; 139:1397-407. [PMID: 20600027 DOI: 10.1053/j.gastro.2010.06.051] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 05/18/2010] [Accepted: 06/17/2010] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Deleted in liver cancer 1 (DLC1), which encodes a Rho GTPase activating protein, is a bona fide tumor suppressor in hepatocellular carcinoma. Underexpression of DLC1 in cancer has been attributed to genomic deletion and epigenetic silencing. However, the regulatory mechanism of the tumor suppressive activity of DLC1 remains elusive. In this study, we elucidated a novel post-translational modification by which the activity of DLC1 is functionally regulated. METHODS Molecular and biochemical approaches were employed to study Akt phosphorylation of DLC1. In vitro and in vivo functional assays were performed to elucidate the functional significance of Akt phosphorylation of DLC1. RESULTS Phosphorylation of ectopically expressed and endogenous DLC1 was enhanced upon insulin induction or with Akt expression in liver cancer cell lines. Conversely, addition of a phosphatidylinositol 3-kinase/Akt pathway inhibitor or silencing of Akt attenuated the phosphorylation level of DLC1. Site-directed mutagenesis was employed to replace the serine residue of the consensus Akt substrate motifs of DLC1 with alanine. S567 of DLC1 was identified as the only target of Akt phosphorylation. S567 is well conserved in all DLC family members. DLC2 was phosphorylated by Akt at the corresponding residue. Functional assays demonstrated that the S567D phosphomimetic DLC1 mutant lost its inhibitory activities in tumorigenesis and metastasis of oncogenically transformed hepatoblasts in a mouse model. CONCLUSIONS This study has revealed a novel post-translational modification that functionally deregulates the biologic activities of DLC1. Phosphorylation of DLC1 and DLC2 by Akt at the conserved residue points to a common regulatory mechanism of the DLC tumor suppressor family.
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Affiliation(s)
- Frankie Chi Fat Ko
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
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11
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Frau M, Biasi F, Feo F, Pascale RM. Prognostic markers and putative therapeutic targets for hepatocellular carcinoma. Mol Aspects Med 2010; 31:179-93. [PMID: 20176048 DOI: 10.1016/j.mam.2010.02.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Accepted: 02/16/2010] [Indexed: 02/08/2023]
Abstract
Hepatocellular carcinoma (HCC) is the fifth most frequent human cancer and a fatal disease. Therapies with pharmacological agents do not improve the prognosis of patients with unresectable HCC. This emphasizes the need to identify new targets for early diagnosis, chemoprevention, and treatment of the disease. Available evidence indicates that clinical outcome of HCC could reflect the genetic predisposition to cancer development and progression. Numerous loci controlling HCC progression have been identified in rodents. In this review, we describe results of recent studies on effector mechanisms of susceptibility/resistance genes, responsible for HCC progression, aimed at identifying new putative prognostic markers and therapeutic targets of this tumor. Highest c-myc amplification and overexpression, alterations of iNOS crosstalk with IKK/NF-kB and RAS/ERK signaling, ubiquitination of ERK and cell cycle inhibitors, and deregulation of FOXM1 and cell cycle key genes occur in rapidly progressing dysplastic nodules and HCC, induced in genetic susceptible rat strains, compared to the lesions of resistant rats. Notably, alterations of these mechanisms in human HCC subtypes with poorer or better prognosis, are similar to those present in genetically susceptible and resistant rats, respectively, and function as prognostic markers and therapeutic targets. Attempts to cure advanced HCC by molecular therapy directed against specific targets led to modest survival benefit. Thus, efforts are necessary to identify and test, in pre-clinical and clinical studies, new therapeutic targets for combined molecular treatments of HCC. They may take advantage from the comparative analysis of signal transduction in HCCs differently prone to progress, in rats and humans.
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Affiliation(s)
- Maddalena Frau
- Department of Biomedical Sciences, Division of Experimental Pathology and Oncology, University of Sassari, 07100 Sassari, Italy
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12
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Hall EH, Daugherty AE, Choi CK, Horwitz AF, Brautigan DL. Tensin1 requires protein phosphatase-1alpha in addition to RhoGAP DLC-1 to control cell polarization, migration, and invasion. J Biol Chem 2009; 284:34713-22. [PMID: 19826001 DOI: 10.1074/jbc.m109.059592] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Tensin is a family of multidomain scaffold proteins that bind the cytoplasmic tail of beta-integrins and localize to adhesions that anchor stress fibers in cells. Tensin expression is suppressed in cancer, especially metastatic cancer. The N-terminal domain of tensin1 associates with protein phosphatase-1alpha (PP1alpha) and mediates PP1alpha localization to adhesions. Here, we show F302A mutation in a KVXF motif of tensin1 abrogates binding to PP1alpha. The SH2 domain in tensin family member c-ten requires R474 to bind a RhoGAP called DLC-1 (deleted in liver cancer). We mutated the corresponding residue in tensin1, R1488A, and showed this reduces association with DLC-1. Unexpectedly, tensin1 F302A also had reduced association with DLC-1. Expression of tensin1 F302A or R1488A showed similar dominant phenotypes, with reduced cell polarization, lowered MLC20 phosphorylation and reduced levels of RhoA(GTP) compared with cells expressing tensin1 WT. However, migration and invasion of metastatic MDA MB 231 breast cancer cells were differentially affected by tensin1 mutated at F302A or R1488A. Cancer cells stably expressing F302A tensin1 showed increased migration and invasion compared with cells stably expressing either R1488A tensin1 or WT tensin1. This suggests that PP1alpha bound to tensin1 has additional effects in reducing migration and invasion that are not mediated through DLC-1. Our results show the importance of PP1alpha binding to tensin1 for the regulation of cell polarization, migration, and invasion.
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Affiliation(s)
- Emily H Hall
- Center for Cell Signaling and Department of Microbiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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13
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Chan LK, Ko FCF, Ng IOL, Yam JWP. Deleted in liver cancer 1 (DLC1) utilizes a novel binding site for Tensin2 PTB domain interaction and is required for tumor-suppressive function. PLoS One 2009; 4:e5572. [PMID: 19440389 PMCID: PMC2680019 DOI: 10.1371/journal.pone.0005572] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 04/15/2009] [Indexed: 12/24/2022] Open
Abstract
Background Deleted in liver cancer 1 (DLC1) is a Rho GTPase-activating protein (RhoGAP) frequently deleted and underexpressed in hepatocellular carcinoma (HCC) as well as in other cancers. Recent independent studies have shown interaction of DLC1 with members of the tensin focal adhesion protein family in a Src Homology 2 (SH2) domain-dependent mechanism. DLC1 and tensins interact and co-localize to punctate structures at focal adhesions. However, the mechanisms underlying the interaction between DLC1 and various tensins remain controversial. Methodology/Principal Findings We used a co-immunoprecipitation assay to identify a previously undocumented binding site at 375–385 of DLC1 that predominantly interacted with the phosphotyrosine binding (PTB) domain of tensin2. DLC1-tensin2 interaction is completely abolished in a DLC1 mutant lacking this novel PTB binding site (DLC1ΔPTB). However, as demonstrated by immunofluorescence and co-immunoprecipitation, neither the focal adhesion localization nor the interaction with tensin1 and C-terminal tensin-like (cten) were affected. Interestingly, the functional significance of this novel site was exhibited by the partial reduction of the RhoGAP activity, which, in turn, attenuated the growth-suppressive activity of DLC1 upon its removal from DLC1. Conclusions/Significance This study has provided new evidence that DLC1 also interacts with tensin2 in a PTB domain-dependent manner. In addition to properly localizing focal adhesions and preserving RhoGAP activity, DLC1 interaction with tensin2 through this novel focal adhesion binding site contributes to the growth-suppressive activity of DLC1.
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Affiliation(s)
- Lo-Kong Chan
- Liver Cancer and Hepatitis Research Laboratory and SH Ho Foundation Research Laboratories, Department of Pathology, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Frankie Chi Fat Ko
- Liver Cancer and Hepatitis Research Laboratory and SH Ho Foundation Research Laboratories, Department of Pathology, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Irene Oi-Lin Ng
- Liver Cancer and Hepatitis Research Laboratory and SH Ho Foundation Research Laboratories, Department of Pathology, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Judy Wai Ping Yam
- Liver Cancer and Hepatitis Research Laboratory and SH Ho Foundation Research Laboratories, Department of Pathology, The University of Hong Kong, Pokfulam, Hong Kong, China
- Centre for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
- * E-mail:
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14
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Zhong D, Zhang J, Yang S, Soh UJK, Buschdorf JP, Zhou YT, Yang D, Low BC. The SAM domain of the RhoGAP DLC1 binds EF1A1 to regulate cell migration. J Cell Sci 2009; 122:414-24. [PMID: 19158340 DOI: 10.1242/jcs.027482] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Deleted in liver cancer 1 (DLC1) is a multi-modular Rho-GTPase-activating protein (RhoGAP) and a tumor suppressor. Besides its RhoGAP domain, functions of other domains in DLC1 remain largely unknown. By protein precipitation and mass spectrometry, we identified eukaryotic elongation factor 1A1 (EF1A1) as a novel partner for the sterile alpha motif (SAM) domain of DLC1 but not the SAM domain of DLC2. The solution structure of DLC1 SAM revealed a new monomeric fold with four parallel helices, similar to that of DLC2 SAM but distinct from other SAM domains. Mutating F38, L39 and F40 within a hydrophobic patch retained its overall structure but abolished its interaction with EF1A1 with F38 and L39 forming an indispensable interacting motif. DLC1 SAM did not localize to and was not required for DLC1 to suppress the turnover of focal adhesions. Instead, DLC1 SAM facilitated EF1A1 distribution to the membrane periphery and ruffles upon growth factor stimulation. Compared with wild-type DLC1, the non-interactive DLC1 mutant is less potent in suppressing cell migration, whereas overexpression of the DLC1 SAM domain alone, but not the non-interactive mutant SAM or DLC2 SAM, greatly enhanced cell migration. This finding reveals a novel contribution of the SAM-EF1A1 interaction as a potentially important GAP-independent modulation of cell migration by DLC1.
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Affiliation(s)
- Dandan Zhong
- Cell Signaling and Developmental Biology Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore
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15
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Abe Y, Yoon SO, Kubota K, Mendoza MC, Gygi SP, Blenis J. p90 ribosomal S6 kinase and p70 ribosomal S6 kinase link phosphorylation of the eukaryotic chaperonin containing TCP-1 to growth factor, insulin, and nutrient signaling. J Biol Chem 2009; 284:14939-48. [PMID: 19332537 DOI: 10.1074/jbc.m900097200] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chaperonin containing TCP-1 (CCT) is a large multisubunit complex that mediates protein folding in eukaryotic cells. CCT participates in the folding of newly synthesized polypeptides, including actin, tubulin, and several cell cycle regulators; therefore, CCT plays an important role in cytoskeletal organization and cell division. Here we identify the chaperonin CCT as a novel physiological substrate for p90 ribosomal S6 kinase (RSK) and p70 ribosomal S6 kinase (S6K). RSK phosphorylates the beta subunit of CCT in response to tumor promoters or growth factors that activate the Ras-mitogen-activated protein kinase (MAPK) pathway. CCTbeta Ser-260 was identified as the RSK site by mass spectrometry and confirmed by site-directed mutagenesis. RSK-dependent Ser-260 phosphorylation was sensitive to the MEK inhibitor UO126 and the RSK inhibitor BID-1870. Insulin weakly activates RSK but strongly activates the phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) pathway and utilizes S6K to regulate CCTbeta phosphorylation. Thus, the Ras-MAPK and PI3K-mTOR pathways converge on CCTbeta Ser-260 phosphorylation in response to multiple agonists in various mammalian cells. We also show that RNA interference-mediated knockdown of endogenous CCTbeta causes impaired cell proliferation that can be rescued with ectopically expressed murine CCTbeta wild-type or phosphomimetic mutant S260D, but not the phosphorylation-deficient mutant S260A. Although the molecular mechanism of CCTbeta regulation remains unclear, our findings demonstrate a link between oncogene and growth factor signaling and chaperonin CCT-mediated cellular activities.
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Affiliation(s)
- Yuki Abe
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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16
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Scholz RP, Regner J, Theil A, Erlmann P, Holeiter G, Jähne R, Schmid S, Hausser A, Olayioye MA. DLC1 interacts with 14-3-3 proteins to inhibit RhoGAP activity and block nucleocytoplasmic shuttling. J Cell Sci 2008; 122:92-102. [PMID: 19066281 DOI: 10.1242/jcs.036251] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Deleted in liver cancer 1 (DLC1) is a Rho-GTPase-activating protein (GAP) that is downregulated in various tumor types. In vitro, DLC1 specifically inactivates the small GTPases RhoA, RhoB and RhoC through its GAP domain and this appears to contribute to its tumor suppressor function in vivo. Molecular mechanisms that control DLC1 activity have not so far been investigated. Here, we show that phorbol-ester-induced activation of protein kinase C and protein kinase D stimulates association of DLC1 with the phosphoserine/phosphothreonine-binding 14-3-3 adaptor proteins via recognition motifs that involve Ser327 and Ser431. Association with 14-3-3 proteins inhibits DLC1 GAP activity and facilitates signaling by active Rho. We further show that treatment of cells with phorbol ester or coexpression of 14-3-3 proteins, blocks DLC1 nucleocytoplasmic shuttling, probably by masking a previously unrecognized nuclear localization sequence. The binding to 14-3-3 proteins is thus a newly discovered mechanism by which DLC1 activity is regulated and compartmentalized.
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Affiliation(s)
- Rolf-Peter Scholz
- University of Stuttgart, Institute of Cell Biology and Immunology, Allmandring 31, 70569 Stuttgart, Germany
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17
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Liao YC, Shih YP, Lo SH. Mutations in the focal adhesion targeting region of deleted in liver cancer-1 attenuate their expression and function. Cancer Res 2008; 68:7718-22. [PMID: 18829524 DOI: 10.1158/0008-5472.can-08-2042] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Deleted in liver cancer-1 (DLC-1) is a RhoGTPase-activating protein (RhoGAP) domain containing tumor suppressor that is often down-regulated in various cancer types. Previously, we have shown that DLC-1 is recruited to focal adhesions by binding to the Src homology 2 domains of tensins and the focal adhesion localization is critical for the tumor suppression activity of DLC-1. To investigate whether mutations in the focal adhesion targeting (FAT) region might occur and attenuate the expression, localization, and function of DLC-1, we have first mapped the FAT region to the amino acid residues from 201 to 500, and then sequenced cDNAs and genomic DNAs encoding the FAT region from cancer patients. Several missense and nonsense mutations were detected. All missense mutations were further examined for the potential effect on the function of DLC-1. Although these mutations did not seem to affect the focal adhesion localization of DLC-1, the activities of suppressing tumor cell growth were impaired in two mutants: T301K and S308I. Consistent with the fact that the RhoGAP activity of DLC-1 is essential for inhibiting tumor cell growth, the RhoGAP activities were significantly reduced in these mutants, suggesting that the FAT region also contains a regulatory element for its COOH-terminal RhoGAP domain. Our studies have shown that mutations in DLC-1 may lead to loss of function and contribute to the tumorigenesis, and have revealed an allosteric regulation site for its RhoGAP activity.
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Affiliation(s)
- Yi-Chun Liao
- Department of Biochemistry and Molecular Medicine, Center for Tissue Regeneration and Repair, University of California, Davis, Sacramento, California 95817, USA
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18
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Kakinuma N, Roy BC, Zhu Y, Wang Y, Kiyama R. Kank regulates RhoA-dependent formation of actin stress fibers and cell migration via 14-3-3 in PI3K-Akt signaling. ACTA ACUST UNITED AC 2008; 181:537-49. [PMID: 18458160 PMCID: PMC2364698 DOI: 10.1083/jcb.200707022] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Phosphoinositide-3 kinase (PI3K)/Akt signaling is activated by growth factors such as insulin and epidermal growth factor (EGF) and regulates several functions such as cell cycling, apoptosis, cell growth, and cell migration. Here, we find that Kank is an Akt substrate located downstream of PI3K and a 14-3-3–binding protein. The interaction between Kank and 14-3-3 is regulated by insulin and EGF and is mediated through phosphorylation of Kank by Akt. In NIH3T3 cells expressing Kank, the amount of actin stress fibers is reduced, and the coexpression of 14-3-3 disrupted this effect. Kank also inhibits insulin-induced cell migration via 14-3-3 binding. Furthermore, Kank inhibits insulin and active Akt-dependent activation of RhoA through binding to 14-3-3. Based on these findings, we hypothesize that Kank negatively regulates the formation of actin stress fibers and cell migration through the inhibition of RhoA activity, which is controlled by binding of Kank to 14-3-3 in PI3K–Akt signaling.
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Affiliation(s)
- Naoto Kakinuma
- Signaling Molecules Research Laboratory, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8566, Japan
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19
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Kawai K, Iwamae Y, Yamaga M, Kiyota M, Ishii H, Hirata H, Homma Y, Yagisawa H. Focal adhesion-localization of START-GAP1/DLC1 is essential for cell motility and morphology. Genes Cells 2008; 14:227-41. [PMID: 19170769 DOI: 10.1111/j.1365-2443.2008.01265.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
There is a class of GTPase activating proteins for the Rho family GTPases (RhoGAPs) that contain the steroidogenic acute regulatory protein (STAR)-related lipid transfer (START) domain. In mammals three genes encode such proteins and they are designated START-GAP1-3 or deleted in liver cancer 1-3 (DLC1-3). In this study, we examined the intracellular localization and roles of START-GAP1/DLC1 in cell motility. Immunofluorescence microscopic analysis of NRK cells and HeLa cells revealed that START-GAP1 was localized in focal adhesions. Amino acid residues 265-459 of START-GAP1 were found to be necessary for focal adhesion targeting and we name the region "the focal adhesion-targeting (FAT) domain." It was previously known that ectopic expression of START-GAP1 induced cell rounding. We demonstrated that the FAT domain of START-GAP1 was partially required for this morphological change. Furthermore, expression of this domain in HeLa cells resulted in dissociation of endogenous START-GAP1 from focal adhesions as a dominant negative modulator, reducing cell migration and spreading. Taken together, START-GAP1 is targeted to focal adhesions via the FAT domain and regulates actin rearrangement through down-regulation of active RhoA and Cdc42. Its absence from focal adhesions could, therefore, cause abnormal cell motility and spreading.
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Affiliation(s)
- Katsuhisa Kawai
- University of Hyogo, Harima Science Garden City, Hyogo-ken, Japan
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20
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Durkin ME, Yuan BZ, Zhou X, Zimonjic DB, Lowy DR, Thorgeirsson SS, Popescu NC. DLC-1:a Rho GTPase-activating protein and tumour suppressor. J Cell Mol Med 2008; 11:1185-207. [PMID: 17979893 PMCID: PMC4401278 DOI: 10.1111/j.1582-4934.2007.00098.x] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The deleted in liver cancer 1 (DLC-1) gene encodes a GTPase activating protein that acts as a negative regulator of the Rho family of small GTPases. Rho proteins transduce signals that influence cell morphology and physiology, and their aberrant up-regulation is a key factor in the neoplastic process, including metastasis. Since its discovery, compelling evidence has accumulated that demonstrates a role for DLC-1 as a bona fide tumour suppressor gene in different types of human cancer. Loss of DLC-1 expression mediated by genetic and epigenetic mechanisms has been associated with the development of many human cancers, and restoration of DLC-1 expression inhibited the growth of tumour cells in vivo and in vitro. Two closely related genes, DLC-2 and DLC-3, may also be tumour suppressors. This review presents the current status of progress in understanding the biological functions of DLC-1 and its relatives and their roles in neoplasia.
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Affiliation(s)
- Marian E Durkin
- Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
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21
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Yuan BZ, Jefferson AM, Millecchia L, Popescu NC, Reynolds SH. Morphological changes and nuclear translocation of DLC1 tumor suppressor protein precede apoptosis in human non-small cell lung carcinoma cells. Exp Cell Res 2007; 313:3868-80. [PMID: 17888903 DOI: 10.1016/j.yexcr.2007.08.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 07/17/2007] [Accepted: 08/08/2007] [Indexed: 11/19/2022]
Abstract
We have previously shown that reactivation of DLC1, a RhoGAP containing tumor suppressor gene, inhibits tumorigenicity of human non-small cell lung carcinoma cells (NSCLC). After transfection of NSCLC cells with wild type (WT) DLC1, changes in cell morphology were observed. To determine whether such changes have functional implications, we generated several DLC1 mutants and examined their effects on cell morphology, proliferation, migration and apoptosis in a DLC1 deficient NSCLC cell line. We show that WT DLC1 caused actin cytoskeleton-based morphological alterations manifested as cytoplasmic extensions and membrane blebbings in most cells. Subsequently, a fraction of cells exhibiting DLC1 protein nuclear translocation (PNT) underwent caspase 3-dependent apoptosis. We also show that the RhoGAP domain is essential for the occurrence of morphological alterations, PNT and apoptosis, and the inhibition of cell migration. DLC1 PNT is dependent on a bipartite nuclear localizing sequence and most likely is regulated by a serine-rich domain at N-terminal part of the DLC1 protein. Also, we found that DLC1 functions in the cytoplasm as an inhibitor of tumor cell proliferation and migration, but in the nucleus as an inducer of apoptosis. Our analyses provide evidence for a possible link between morphological alterations, PNT and proapoptotic and anti-oncogenic activities of DLC1 in lung cancer.
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Affiliation(s)
- Bao-Zhu Yuan
- Laboratory of Molecular Genetics, Toxicology and Molecular Biology Branch, National Institute for Occupational Safety and Health, CDC, Morgantown, WV 26505, USA.
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Zhao M, Mueller BM, DiScipio RG, Schraufstatter IU. Akt plays an important role in breast cancer cell chemotaxis to CXCL12. Breast Cancer Res Treat 2007; 110:211-22. [PMID: 17687643 DOI: 10.1007/s10549-007-9712-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Accepted: 07/23/2007] [Indexed: 01/22/2023]
Abstract
The chemokine receptor CXCR4 is functionally expressed on the cell surface of various cancer cells, and plays a role in cell proliferation and migration of these cells. Specifically, in breast cancer cells the CXCR4/CXCL12 axis has been implicated in cell migration in vitro and in metastasis in vivo, but the underlying signaling mechanisms are incompletely understood. The xenograft-derived MDA-MB-231 breast cancer cell line (231mfp), which was shown previously to grow more aggressively than the parent cells, showed increased CXCR4 expression at the mRNA, total protein and cell surface expression level. This correlated with an enhanced response to CXCL12, specifically in augmented and prolonged Akt activation in a G(i), Src family kinase and PI-3 kinase dependent fashion. 231mfp cells migrated towards CXCL12--in contrast to the parent cell line--and this chemotaxis was blocked by inhibition of G(i), Src family kinases, PI-3 kinase and interestingly, Akt itself, as could be shown with two pharmacological inhibitors, a dominant negative Akt construct and with Akt shRNA. Collectively, we have demonstrated that prolonged Akt activation is an important signaling pathway for breast cancer cells expressing CXCR4 and is necessary for CXCL12-dependent cell migration.
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Affiliation(s)
- Ming Zhao
- Division of Cancer Biology, La Jolla Institute for Molecular Medicine, San Diego, CA 92121, USA.
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23
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Liao YC, Lo SH. Deleted in liver cancer-1 (DLC-1): a tumor suppressor not just for liver. Int J Biochem Cell Biol 2007; 40:843-7. [PMID: 17521951 PMCID: PMC2323245 DOI: 10.1016/j.biocel.2007.04.008] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 04/10/2007] [Accepted: 04/11/2007] [Indexed: 11/15/2022]
Abstract
Deleted in liver cancer 1 (DLC-1), as its name implied, was originally isolated as a potential tumor suppressor gene often deleted in hepatocellular carcinoma. Further studies have indicated that down-expression of DLC-1 either by genomic deletion or DNA methylation is associated with a variety of cancer types including lung, breast, prostate, kidney, colon, uterus, ovary, and stomach. Re-expression of DLC-1 in cancer cells regulates the structure of actin cytoskeleton and focal adhesions and significantly inhibits cell growth, supporting its role as a tumor suppressor. This tumor suppressive function relies on DLC-1's RhoGTPase activating protein (RhoGAP) activity and steroidogenic acute regulatory (StAR)-related lipid transfer (START) domain, as well as its focal adhesion localization, which is recruited by the Src Homology 2 (SH2) domains of tensins in a phosphotyrosine-independent fashion. Therefore, the expression and subcellular localization of DLC-1 could be a useful molecular marker for cancer prognosis, whereas DLC-1 and its downstream signaling molecules might be therapeutic targets for the treatment of cancer.
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Affiliation(s)
- Yi-Chun Liao
- Lawrence Ellison Center for Tissue Regeneration and Repair, Department of Biochemistry and Molecular Medicine, University of California, Davis, Sacramento, CA 95817, USA
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Durkin ME, Ullmannova V, Guan M, Popescu NC. Deleted in liver cancer 3 (DLC-3), a novel Rho GTPase-activating protein, is downregulated in cancer and inhibits tumor cell growth. Oncogene 2007; 26:4580-9. [PMID: 17297465 DOI: 10.1038/sj.onc.1210244] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Two related Rho GTPase-activating proteins, DLC-1 (deleted in liver cancer 1) and DLC-2, are emerging as bona fide tumor suppressor genes that inhibit cancer cell growth. In this report, we characterized a gene on chromosome Xq13 that encodes DLC-3 (also known as KIAA0189 and STARD8), a third member of the DLC family. The DLC-3 gene has transcripts with alternative 5' ends, one of which, DLC-3alpha, encodes an 1103-amino acid polypeptide highly similar to DLC-1 and DLC-2. A second isoform (DLC-3beta) would yield a protein lacking the N-terminal sterile alpha motif domain. The DLC-3 gene is widely expressed in normal tissues, but DLC-3 mRNA levels were low or absent in a significant number of breast, ovarian, liver and prostate cancer cell lines. Using a cancer profiling array to compare matched tumor and normal human tissues, downregulation of DLC-3 mRNA was observed in kidney, lung, ovarian, uterine and breast cancer samples. By quantitative reverse transcriptase-polymerase chain reaction, DLC-3 expression was reduced in primary prostate carcinomas relative to normal prostate tissue. Transfection of human breast and prostate cancer cells with a DLC-3alpha expression vector inhibited cell proliferation, colony formation and growth in soft agar. These results indicate that deregulation of DLC-3 may contribute to breast and prostate tumorigenesis.
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Affiliation(s)
- M E Durkin
- Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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25
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Abstract
Several members of the extensive family of small GTP-binding proteins are regulated by insulin, and have been implicated in insulin action on glucose uptake. These proteins are themselves negatively regulated by a series of specific GAPs (GTPase-activating proteins). Interestingly, there is increasing evidence to suggest that PKB (protein kinase B)-dependent phosphorylation of some GAPs may relieve this negative regulation and so lead to the activation of the target small GTP-binding protein. We review recent evidence that this may be the case, and place specific emphasis on the role of these pathways in insulin-stimulated glucose uptake.
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