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Park JB, Moon GH, Cho A, Kwon M, Park JW, Yi EC, Kim H, Fukuda J, Kwak C, Ko YG, Chun YS. Neddylation of insulin receptor substrate acts as a bona fide regulator of insulin signaling and its implications for cancer cell migration. Cancer Gene Ther 2024; 31:599-611. [PMID: 38272982 PMCID: PMC11016467 DOI: 10.1038/s41417-024-00729-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/03/2024] [Accepted: 01/09/2024] [Indexed: 01/27/2024]
Abstract
Irregularities in insulin signaling have significantly increased the risk of various cancers, yet the precise underlying mechanisms remain unclear. Within our study, we observed that inhibiting neddylation enhances cancer cell migration across different cancer types by activating both insulin receptor substrates 1 and 2 (IRS1 and IRS2), along with the PI3K/AKT signaling pathway. Notably, in the context of high-grade serous carcinoma (HGSC) patients, whether they had type 2 diabetes mellitus or not, IRS1 and IRS2 displayed a parallel relationship with each other while exhibiting an inverse relationship with NEDD8. We also identified C-CBL as an E3 ligase responsible for neddylating IRS1 and IRS2, with clinical evidence further confirming a reciprocal relationship between C-CBL and pAKT, thereby reinforcing the tumor suppressive role of C-CBL. Altogether, these findings suggest that neddylation genuinely participates in IRS1 and IRS2-dependent insulin signaling, effectively suppressing cancer cell migration. Thus, caution is advised when considering neddylation inhibitors as a treatment option for cancer patients, particularly those presenting with insulin signaling dysregulations linked to conditions like obesity-related type 2 diabetes or hyperinsulinemia.
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Affiliation(s)
- Jun Bum Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Geon Ho Moon
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Ara Cho
- Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, and Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Minji Kwon
- Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Jong-Wan Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Eugene C Yi
- Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, and Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Haeryoung Kim
- Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Junji Fukuda
- Faculty of Engineering, Yokohama National University, Yokohama, 240-8501, Japan
| | - Cheol Kwak
- Department of Urology, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Young-Gyu Ko
- Division of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Yang-Sook Chun
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
- Department of Physiology, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
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Morel M, Long W. FBXL16 promotes cell growth and drug resistance in lung adenocarcinomas with KRAS mutation by stabilizing IRS1 and upregulating IRS1/AKT signaling. Mol Oncol 2024; 18:762-777. [PMID: 37983945 PMCID: PMC10920083 DOI: 10.1002/1878-0261.13554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/17/2023] [Accepted: 11/15/2023] [Indexed: 11/22/2023] Open
Abstract
Lung cancer is the leading cause of cancer-related deaths worldwide. Lung adenocarcinomas (LUADs) are a major subtype of non-small-cell lung cancers (NSCLCs). About 25% of LUADs harbor GTPase KRAS mutations associated with poor prognosis and limited treatment options. While encouraging tumor response to novel covalent inhibitors specifically targeting KRASG12C has been shown in the clinic, either intrinsic resistance exists or acquired therapeutic resistance arises upon treatment. There is an unmet need to identify new therapeutic targets for treating LUADs with activating KRAS mutations, particularly those with resistance to KRASG12C inhibitor(s). In this study, we have revealed that F-box/LRR-repeat protein 16 (FBXL16) is selectively upregulated in LUAD with KRAS mutations. It promotes LUAD cell growth and transforms lung epithelial cells. Importantly, FBXL16 depletion greatly enhances sensitivity to the KRASG12C inhibitor (sotorasib) in resistant cells by downregulating phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB; also known as AKT) signaling. Mechanistically, FBXL16 upregulates insulin receptor substrate 1 (IRS1) protein stability, leading to an increase of IGF1/AKT signaling, thereby promoting cell growth and migration. Taken together, our study highlights the potential of FBXL16 as a therapeutic target for treating LUAD with KRAS activating mutations.
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Affiliation(s)
- Marion Morel
- Department of Biochemistry and Molecular Biology, Boonshoft School of MedicineWright State UniversityDaytonOHUSA
| | - Weiwen Long
- Department of Biochemistry and Molecular Biology, Boonshoft School of MedicineWright State UniversityDaytonOHUSA
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3
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Weina T, Ying L, Yiwen W, Huan-Huan Q. What we have learnt from Drosophila model organism: the coordination between insulin signaling pathway and tumor cells. Heliyon 2022; 8:e09957. [PMID: 35874083 PMCID: PMC9304707 DOI: 10.1016/j.heliyon.2022.e09957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/25/2022] [Accepted: 07/11/2022] [Indexed: 02/08/2023] Open
Abstract
Cancer development is related to a variety of signaling pathways which mediate various cellular processes including growth, survival, division and competition of cells, as well as cell-cell interaction. The insulin signaling pathway interacts with different pathways and plays a core role in the regulations of all these processes. In this study, we reviewed recent studies on the relationship between the insulin signaling pathway and tumors using the Drosophila melanogaster model. We found that on one hand, the insulin pathway is normally hyperactive in tumor cells, which promotes tumor growth, and on the other hand, tumor cells can suppress the growth of healthy tissues via inhibition of their insulin pathway. Moreover, systematic disruption in glucose homeostasis also facilitates cancer development by different mechanisms. The studies on how the insulin network regulates the behaviors of cancer cells may help to discover new therapeutic treatments for cancer.
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Affiliation(s)
- Tang Weina
- School of Pharmaceutical Science and Technology, Tianjin University, 300072, Tianjin, China
| | - Li Ying
- School of Pharmaceutical Science and Technology, Tianjin University, 300072, Tianjin, China
| | - Wang Yiwen
- School of Pharmaceutical Science and Technology, Tianjin University, 300072, Tianjin, China
| | - Qiao Huan-Huan
- Academy of Medical Engineering and Translational Medicine, Tianjin University, 300072, Tianjin, China
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Lautherbach N, Gonçalves DAP, Silveira WA, Paula-Gomes S, Valentim RR, Zanon NM, Pereira MG, Miyabara EH, Navegantes LCC, Kettelhut IC. Urocortin 2 promotes hypertrophy and enhances skeletal muscle function through cAMP and insulin/IGF-1 signaling pathways. Mol Metab 2022; 60:101492. [PMID: 35390501 PMCID: PMC9035725 DOI: 10.1016/j.molmet.2022.101492] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 02/27/2022] [Accepted: 03/29/2022] [Indexed: 11/28/2022] Open
Abstract
Objective Although it is well established that urocortin 2 (Ucn2), a peptide member of the corticotrophin releasing factor (CRF) family, and its specific corticotrophin-releasing factor 2 receptor (CRF2R) are highly expressed in skeletal muscle, the role of this peptide in the regulation of skeletal muscle mass and protein metabolism remains elusive. Methods To elucidate the mechanisms how Ucn2 directly controls protein metabolism in skeletal muscles of normal mice, we carried out genetic tools, physiological and molecular analyses of muscles in vivo and in vitro. Results Here, we demonstrated that Ucn2 overexpression activated cAMP signaling and promoted an expressive muscle hypertrophy associated with higher rates of protein synthesis and activation of Akt/mTOR and ERK1/2 signaling pathways. Furthermore, Ucn2 induced a decrease in mRNA levels of atrogin-1 and in autophagic flux inferred by an increase in the protein content of LC3-I, LC3-II and p62. Accordingly, Ucn2 reduced both the transcriptional activity of FoxO in vivo and the overall protein degradation in vitro through an inhibition of lysosomal proteolytic activity. In addition, we demonstrated that Ucn2 induced a fast-to-slow fiber type shift and improved fatigue muscle resistance, an effect that was completely blocked in muscles co-transfected with mitogen-activated protein kinase phosphatase 1 (MKP-1), but not with dominant-negative Akt mutant (Aktmt). Conclusions These data suggest that Ucn2 triggers an anabolic and anti-catabolic response in skeletal muscle of normal mice probably through the activation of cAMP cascade and participation of Akt and ERK1/2 signaling. These findings open new perspectives in the development of therapeutic strategies to cope with the loss of muscle mass. Ucn2 overexpression promotes muscle growth due to an increase in protein synthesis. Ucn2 inhibits FoxO activity and autophagic-lysosomal system. Ucn2-induced skeletal muscle phenotype is dependent on Akt and ERK1/2. Ucn2 induces a fast-to-slow fiber type shift and improves fatigue resistance. The increase in muscle fatigue resistance is dependent on ERK1/2.
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Affiliation(s)
- Natalia Lautherbach
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; Department of Biochemistry/Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
| | - Dawit A P Gonçalves
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
| | - Wilian A Silveira
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; Department of Biochemistry, Pharmacology and Physiology, Institute of Biological and Natural Sciences, Federal University of Triângulo Mineiro, Uberaba, MG, Brazil.
| | - Sílvia Paula-Gomes
- Department of Biochemistry/Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil.
| | - Rafael Rossi Valentim
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
| | - Neuza M Zanon
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
| | - Marcelo G Pereira
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
| | - Elen H Miyabara
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
| | - Luiz C C Navegantes
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
| | - Isis C Kettelhut
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; Department of Biochemistry/Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
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Abstract
The molecular mechanisms of cellular insulin action have been the focus of much investigation since the discovery of the hormone 100 years ago. Insulin action is impaired in metabolic syndrome, a condition known as insulin resistance. The actions of the hormone are initiated by binding to its receptor on the surface of target cells. The receptor is an α2β2 heterodimer that binds to insulin with high affinity, resulting in the activation of its tyrosine kinase activity. Once activated, the receptor can phosphorylate a number of intracellular substrates that initiate discrete signaling pathways. The tyrosine phosphorylation of some substrates activates phosphatidylinositol-3-kinase (PI3K), which produces polyphosphoinositides that interact with protein kinases, leading to activation of the kinase Akt. Phosphorylation of Shc leads to activation of the Ras/MAP kinase pathway. Phosphorylation of SH2B2 and of Cbl initiates activation of G proteins such as TC10. Activation of Akt and other protein kinases produces phosphorylation of a variety of substrates, including transcription factors, GTPase-activating proteins, and other kinases that control key metabolic events. Among the cellular processes controlled by insulin are vesicle trafficking, activities of metabolic enzymes, transcriptional factors, and degradation of insulin itself. Together these complex processes are coordinated to ensure glucose homeostasis.
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40 Years of RAS-A Historic Overview. Genes (Basel) 2021; 12:genes12050681. [PMID: 34062774 PMCID: PMC8147265 DOI: 10.3390/genes12050681] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 12/12/2022] Open
Abstract
It has been over forty years since the isolation of the first human oncogene (HRAS), a crucial milestone in cancer research made possible through the combined efforts of a few selected research groups at the beginning of the 1980s. Those initial discoveries led to a quantitative leap in our understanding of cancer biology and set up the onset of the field of molecular oncology. The following four decades of RAS research have produced a huge pool of new knowledge about the RAS family of small GTPases, including how they regulate signaling pathways controlling many cellular physiological processes, or how oncogenic mutations trigger pathological conditions, including developmental syndromes or many cancer types. However, despite the extensive body of available basic knowledge, specific effective treatments for RAS-driven cancers are still lacking. Hopefully, recent advances involving the discovery of novel pockets on the RAS surface as well as highly specific small-molecule inhibitors able to block its interaction with effectors and/or activators may lead to the development of new, effective treatments for cancer. This review intends to provide a quick, summarized historical overview of the main milestones in RAS research spanning from the initial discovery of the viral RAS oncogenes in rodent tumors to the latest attempts at targeting RAS oncogenes in various human cancers.
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Solsona R, Pavlin L, Bernardi H, Sanchez AMJ. Molecular Regulation of Skeletal Muscle Growth and Organelle Biosynthesis: Practical Recommendations for Exercise Training. Int J Mol Sci 2021; 22:2741. [PMID: 33800501 PMCID: PMC7962973 DOI: 10.3390/ijms22052741] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 12/18/2022] Open
Abstract
The regulation of skeletal muscle mass and organelle homeostasis is dependent on the capacity of cells to produce proteins and to recycle cytosolic portions. In this investigation, the mechanisms involved in skeletal muscle mass regulation-especially those associated with proteosynthesis and with the production of new organelles-are presented. Thus, the critical roles of mammalian/mechanistic target of rapamycin complex 1 (mTORC1) pathway and its regulators are reviewed. In addition, the importance of ribosome biogenesis, satellite cells involvement, myonuclear accretion, and some major epigenetic modifications related to protein synthesis are discussed. Furthermore, several studies conducted on the topic of exercise training have recognized the central role of both endurance and resistance exercise to reorganize sarcomeric proteins and to improve the capacity of cells to build efficient organelles. The molecular mechanisms underlying these adaptations to exercise training are presented throughout this review and practical recommendations for exercise prescription are provided. A better understanding of the aforementioned cellular pathways is essential for both healthy and sick people to avoid inefficient prescriptions and to improve muscle function with emergent strategies (e.g., hypoxic training). Finally, current limitations in the literature and further perspectives, notably on epigenetic mechanisms, are provided to encourage additional investigations on this topic.
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Affiliation(s)
- Robert Solsona
- Laboratoire Interdisciplinaire Performance Santé Environnement de Montagne (LIPSEM), Faculty of Sports Sciences, University of Perpignan Via Domitia, UR 4640, 7 Avenue Pierre de Coubertin, 66120 Font-Romeu, France;
| | - Laura Pavlin
- DMEM, University of Montpellier, INRAE UMR866, 2 Place Pierre Viala, 34060 Montpellier, France; (L.P.); (H.B.)
| | - Henri Bernardi
- DMEM, University of Montpellier, INRAE UMR866, 2 Place Pierre Viala, 34060 Montpellier, France; (L.P.); (H.B.)
| | - Anthony MJ Sanchez
- Laboratoire Interdisciplinaire Performance Santé Environnement de Montagne (LIPSEM), Faculty of Sports Sciences, University of Perpignan Via Domitia, UR 4640, 7 Avenue Pierre de Coubertin, 66120 Font-Romeu, France;
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8
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Dragano NRV, Fernø J, Diéguez C, López M, Milbank E. Reprint of: Recent Updates on Obesity Treatments: Available Drugs and Future Directions. Neuroscience 2020; 447:191-215. [PMID: 33046217 DOI: 10.1016/j.neuroscience.2020.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In the last thirty years, obesity has reached epidemic proportions and is now regarded as a major health issue in contemporary society trending to serious economic and social burdens. The latest projections of the World Health Organization are alarming. By 2030, nearly 60% of the worldwide population could be either obese or overweight, highlighting the needs to find innovative treatments. Currently, bariatric surgery is the most effective way to efficiently lower body mass. Although great improvements in terms of recovery and patient care were made in these surgical procedures, bariatric surgery remains an option for extreme forms of obesity and seems unable to tackle obesity pandemic expansion. Throughout the last century, numerous pharmacological strategies targeting either peripheral or central components of the energy balance regulatory system were designed to reduce body mass, some of them reaching sufficient levels of efficiency and safety. Nevertheless, obesity drug therapy remains quite limited on its effectiveness to actually overcome the obesogenic environment. Thus, innovative unimolecular polypharmacology strategies, able to simultaneously target multiple actors involved in the obesity initiation and expansion, were developed during the last ten years opening a new promising avenue in the pharmacological management of obesity. In this review, we first describe the clinical features of obesity-associated conditions and then focus on the outcomes of currently approved drug therapies for obesity as well as new ones expecting to reach the clinic in the near future.
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Affiliation(s)
- Nathalia R V Dragano
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 15706, Spain.
| | - Johan Fernø
- Hormone Laboratory, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Carlos Diéguez
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 15706, Spain
| | - Miguel López
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 15706, Spain
| | - Edward Milbank
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 15706, Spain.
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9
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Zacharewicz E, Kalanon M, Murphy RM, Russell AP, Lamon S. MicroRNA-99b-5p downregulates protein synthesis in human primary myotubes. Am J Physiol Cell Physiol 2020; 319:C432-C440. [PMID: 32608991 DOI: 10.1152/ajpcell.00172.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
microRNAs (miRNAs) are important regulators of cellular homeostasis and exert their effect by directly controlling protein expression. We have previously reported an age-dependent negative association between microRNA-99b (miR-99b-5p) expression and muscle protein synthesis in human muscle in vivo. Here we investigated the role of miR-99b-5p as a potential negative regulator of protein synthesis via inhibition of mammalian target for rapamycin (MTOR) signaling in human primary myocytes. Overexpressing miR-99b-5p in human primary myotubes from young and old subjects significantly decreased protein synthesis with no effect of donor age. A binding interaction between miR-99b-5p and its putative binding site within the MTOR 3'-untranslated region (UTR) was confirmed in C2C12 myoblasts. The observed decline in protein synthesis was, however, not associated with a suppression of the MTOR protein but of its regulatory associated protein of mTOR complex 1 (RPTOR). These results demonstrate that modulating the expression levels of a miRNA can regulate protein synthesis in human muscle cells and provide a potential mechanism for muscle wasting in vivo.
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Affiliation(s)
- Evelyn Zacharewicz
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Ming Kalanon
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Robyn M Murphy
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - Aaron P Russell
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Séverine Lamon
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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10
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Dragano NRV, Fernø J, Diéguez C, López M, Milbank E. Recent Updates on Obesity Treatments: Available Drugs and Future Directions. Neuroscience 2020; 437:215-239. [PMID: 32360593 DOI: 10.1016/j.neuroscience.2020.04.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 12/12/2022]
Abstract
In the last thirty years, obesity has reached epidemic proportions and is now regarded as a major health issue in contemporary society trending to serious economic and social burdens. The latest projections of the World Health Organization are alarming. By 2030, nearly 60% of the worldwide population could be either obese or overweight, highlighting the needs to find innovative treatments. Currently, bariatric surgery is the most effective way to efficiently lower body mass. Although great improvements in terms of recovery and patient care were made in these surgical procedures, bariatric surgery remains an option for extreme forms of obesity and seems unable to tackle obesity pandemic expansion. Throughout the last century, numerous pharmacological strategies targeting either peripheral or central components of the energy balance regulatory system were designed to reduce body mass, some of them reaching sufficient levels of efficiency and safety. Nevertheless, obesity drug therapy remains quite limited on its effectiveness to actually overcome the obesogenic environment. Thus, innovative unimolecular polypharmacology strategies, able to simultaneously target multiple actors involved in the obesity initiation and expansion, were developed during the last ten years opening a new promising avenue in the pharmacological management of obesity. In this review, we first describe the clinical features of obesity-associated conditions and then focus on the outcomes of currently approved drug therapies for obesity as well as new ones expecting to reach the clinic in the near future.
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Affiliation(s)
- Nathalia R V Dragano
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 15706, Spain.
| | - Johan Fernø
- Hormone Laboratory, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Carlos Diéguez
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 15706, Spain
| | - Miguel López
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 15706, Spain
| | - Edward Milbank
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 15706, Spain.
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11
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Leiphrakpam PD, Lazenby AJ, Chowdhury S, Smith LM, Mathiesen M, Brattain MG, Wang J, Black JD, Are C. Prognostic and therapeutic implications of NHERF1 expression and regulation in colorectal cancer. J Surg Oncol 2019; 121:547-560. [PMID: 31867736 DOI: 10.1002/jso.25805] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 11/22/2019] [Indexed: 12/20/2022]
Abstract
BACKGROUND Na+ /H+ exchanger regulatory factor 1 (NHERF1) has been implicated in the tumorigenesis of several cancer types and is a potential therapeutic target. The current study evaluated the relationship between NHERF1 expression and clinical outcome in colorectal cancer (CRC). METHODS NHERF1 expression was evaluated by immunohistochemistry in 167 patients with CRC primary tumors, 37 patients with no disease, and 27 patients with metastatic CRC (mCRC); and in the orthotopically implanted tumors in mice. NHERF1 expression was manipulated in CRC cells using inducible short hairpin RNAs to determine its biological functions. RESULTS High expression of NHERF1 correlated with CRC progression and metastasis, as well as significantly worse overall survival, recurrence-free survival, and disease-specific survival. Orthotopic implantation studies demonstrated increased NHERF1 expression in liver metastases. Treatment of CRC xenografts with insulin-like growth factor 1 receptor (IGF1R) inhibitors downregulated NHERF1 expression, indicating NHERF1 is downstream of IGF1R signaling. Knockdown of NHERF1 increased apoptosis and reduced X-linked inhibitor of apoptosis protein (XIAP) and survivin expression, indicating NHERF1 is critical for CRC cell survival. CONCLUSION NHERF1 expression levels correlated with worse prognosis in patients with CRC and plays a critical role in CRC cell survival. Together, our findings establish NHERF1 as a novel potential marker for increased risk of CRC-specific mortality and identify NHERF1 as an attractive therapeutic target for mCRC treatment.
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Affiliation(s)
- Premila D Leiphrakpam
- Department of Surgery, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Audrey J Lazenby
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Sanjib Chowdhury
- Section of Gastroenterology, College of Medicine, Boston University Medical Center, Boston, Massachusetts
| | - Lynette M Smith
- Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska
| | - Michelle Mathiesen
- Diagnostic Laboratory, Phibro Animal Health Corporation, Omaha, Nebraska
| | - Michael G Brattain
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska
| | - Jing Wang
- Department of Cancer Biology and Genetics, College of Medicine, Ohio State University, Columbus, Ohio
| | - Jennifer D Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska
| | - Chandrakanth Are
- Division of Surgical Oncology, Department of Surgery, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska
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12
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Machado-Neto JA, Fenerich BA, Rodrigues Alves APN, Fernandes JC, Scopim-Ribeiro R, Coelho-Silva JL, Traina F. Insulin Substrate Receptor (IRS) proteins in normal and malignant hematopoiesis. Clinics (Sao Paulo) 2018; 73:e566s. [PMID: 30328953 PMCID: PMC6169455 DOI: 10.6061/clinics/2018/e566s] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 07/30/2018] [Indexed: 12/31/2022] Open
Abstract
The insulin receptor substrate (IRS) proteins are a family of cytoplasmic proteins that integrate and coordinate the transmission of signals from the extracellular to the intracellular environment via transmembrane receptors, thus regulating cell growth, metabolism, survival and proliferation. The PI3K/AKT/mTOR and MAPK signaling pathways are the best-characterized downstream signaling pathways activated by IRS signaling (canonical pathways). However, novel signaling axes involving IRS proteins (noncanonical pathways) have recently been identified in solid tumor and hematologic neoplasm models. Insulin receptor substrate-1 (IRS1) and insulin receptor substrate-2 (IRS2) are the best-characterized IRS proteins in hematologic-related processes. IRS2 binds to important cellular receptors involved in normal hematopoiesis (EPOR, MPL and IGF1R). Moreover, the identification of IRS1/ABL1 and IRS2/JAK2V617F interactions and their functional consequences has opened a new frontier for investigating the roles of the IRS protein family in malignant hematopoiesis. Insulin receptor substrate-4 (IRS4) is absent in normal hematopoietic tissues but may be expressed under abnormal conditions. Moreover, insulin receptor substrate-5 (DOK4) and insulin receptor substrate-6 (DOK5) are linked to lymphocyte regulation. An improved understanding of the signaling pathways mediated by IRS proteins in hematopoiesis-related processes, along with the increased development of agonists and antagonists of these signaling axes, may generate new therapeutic approaches for hematological diseases. The scope of this review is to recapitulate and review the evidence for the functions of IRS proteins in normal and malignant hematopoiesis.
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Affiliation(s)
- João Agostinho Machado-Neto
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
- Departamento de Farmacologia do Instituto de Ciencias Biomedicas da Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Bruna Alves Fenerich
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Ana Paula Nunes Rodrigues Alves
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Jaqueline Cristina Fernandes
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Renata Scopim-Ribeiro
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Juan Luiz Coelho-Silva
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Fabiola Traina
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
- *Corresponding author. E-mail:
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13
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Liu X, Bauman WA, Cardozo CP. Myostatin inhibits glucose uptake via suppression of insulin-dependent and -independent signaling pathways in myoblasts. Physiol Rep 2018; 6:e13837. [PMID: 30252210 PMCID: PMC6121119 DOI: 10.14814/phy2.13837] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/19/2018] [Accepted: 07/25/2018] [Indexed: 11/24/2022] Open
Abstract
The glucose transporter 4 (Glut4) mediates insulin-dependent glucose uptake. Glut4 expression levels are correlated with whole-body glucose homeostasis. Insulin signaling is known to recruit Glut4 to the cell surface. Expression of Glut4 is subject to tissue-specific hormonal and metabolic regulation. The molecular mechanisms regulating skeletal muscle Glut4 expression remain to be elucidated. Myostatin (Mstn) is reported to be involved in the regulation of energy metabolism. While elevated Mstn levels in muscle are associated with obesity and type-2 diabetes in both human and mouse models, Mstn null mice exhibit immunity to dietary-induced obesity and insulin resistance. The molecular mechanisms by which Mstn initiates the development of insulin resistance and disorders of glucose disposal are not well delineated. Here we investigated effects of Mstn on insulin action in C2C12 cells. Mstn significantly reduced basal and insulin-induced IRS-1 tyrosine (Tyr495) phosphorylation, and expression and activation of PI3K, associated with diminished AKT phosphorylation and elevated GSK3β phosphorylation at Ser9. In addition, Mstn inhibited Glut4 mRNA and protein expression, and reduced insulin-induced Glut4 membrane translocation and glucose uptake. Conversely, SB431542, a Smad2/3 inhibitor, significantly increased cellular response to insulin. Mstn decreased AMP-activated protein kinase (AMPK) activity accompanied by reduced Glut4 gene expression and glucose uptake, which were partially reversed by AICAR, an AMPK activator. These data suggest that Mstn inhibits Glut4 expression and insulin-induced Glut4 integration into cytoplasmic membranes and glucose uptake and that these changes are mediated by direct insulin-desensitizing effect and indirect suppression of AMPK activation.
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Affiliation(s)
- Xin‐Hua Liu
- National Center for the Medical Consequences of Spinal Cord InjuryJames J. Peter VA Medical CenterBronxNew York
- Department of MedicineMount Sinai School of MedicineNew YorkNew York
| | - William A. Bauman
- National Center for the Medical Consequences of Spinal Cord InjuryJames J. Peter VA Medical CenterBronxNew York
- Department of MedicineMount Sinai School of MedicineNew YorkNew York
- Department of Rehabilitation MedicineMount Sinai School of MedicineNew YorkNew York
| | - Christopher P. Cardozo
- National Center for the Medical Consequences of Spinal Cord InjuryJames J. Peter VA Medical CenterBronxNew York
- Department of MedicineMount Sinai School of MedicineNew YorkNew York
- Department of Rehabilitation MedicineMount Sinai School of MedicineNew YorkNew York
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14
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Stone TW, McPherson M, Gail Darlington L. Obesity and Cancer: Existing and New Hypotheses for a Causal Connection. EBioMedicine 2018; 30:14-28. [PMID: 29526577 PMCID: PMC5952217 DOI: 10.1016/j.ebiom.2018.02.022] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 02/12/2018] [Accepted: 02/23/2018] [Indexed: 02/07/2023] Open
Abstract
Existing explanations of obesity-associated cancer emphasise direct mutagenic effects of dietary components or hormonal imbalance. Some of these hypotheses are reviewed briefly, but recent evidence suggests a major role for chronic inflammation in cancer risk, possibly involving dietary content. These ideas include the inflammation-induced activation of the kynurenine pathway and its role in feeding and metabolism by activation of the aryl hydrocarbon receptor (AHR) and by modulating synaptic transmission in the brain. Evidence for a role of the kynurenine pathway in carcinogenesis then provides a potentially major link between obesity and cancer. A second new hypothesis is based on evidence that serine proteases can deplete cells of the tumour suppressors Deleted in Colorectal Cancer (DCC) and neogenin. These enzymes include mammalian chymotryptic proteases released by pro-inflammatory neutrophils and macrophages. Blood levels of chymotrypsin itself increase in parallel with food intake. The mechanistically similar bacterial enzyme subtilisin is widespread in the environment, animal probiotics, meat processing and cleaning products. Simple public health schemes in these areas, with selective serine protease inhibitors and AHR antagonists and could prevent a range of intestinal and other cancers.
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Affiliation(s)
- Trevor W Stone
- The Kennedy Institute, University of Oxford, Oxford OX3 7FY, UK; Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
| | - Megan McPherson
- School of Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Differential Binding of Human ApoE Isoforms to Insulin Receptor is Associated with Aberrant Insulin Signaling in AD Brain Samples. Neuromolecular Med 2018; 20:124-132. [PMID: 29450841 DOI: 10.1007/s12017-018-8480-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 02/03/2018] [Indexed: 01/26/2023]
Abstract
Apolipoprotein E4 (ApoE4) is the strongest genetic risk factor for sporadic Alzheimer's disease (AD), where inheritance of this isoform predisposes development of AD in a gene dose-dependent manner. Although the mode of action of ApoE4 on AD onset and progression remains unknown, we have previously shown that ApoE4, and not ApoE3 expression, resulted in insulin signaling deficits in the presence of amyloid beta (Aβ). However, these reports were not conducted with clinical samples that more accurately reflect human disease. In this study, we investigated the effect of ApoE genotype on the insulin signaling pathway in control and AD human brain samples. We found that targets of the insulin signaling pathway were attenuated in AD cases, regardless of ApoE isoform. We also found a decrease in GluR1 subunit expression, and an increase NR2B subunit expression in AD cases, regardless of ApoE isoform. Lastly, we observed that more insulin receptor (IR) was immunoprecipitated in control cases, and more Aβ was immunoprecipitated with AD cases. But, when comparing among AD cases, we found that more IR was immunoprecipitated with ApoE3 than ApoE4, and more Aβ was immunoprecipitated with ApoE4 than ApoE3. Our results suggest that the difference in IR binding and effect on protein expression downstream of the IR may affect onset and progression of AD.
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16
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The Roles of Insulin-Like Growth Factors in Mesenchymal Stem Cell Niche. Stem Cells Int 2017; 2017:9453108. [PMID: 28298931 PMCID: PMC5337393 DOI: 10.1155/2017/9453108] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 12/22/2016] [Accepted: 01/18/2017] [Indexed: 12/12/2022] Open
Abstract
Many tissues contain adult mesenchymal stem cells (MSCs), which may be used in tissue regeneration therapies. However, the MSC availability in most tissues is limited which demands expansion in vitro following isolation. Like many developing cells, the state of MSCs is affected by the surrounding microenvironment, and mimicking this natural microenvironment that supports multipotent or differentiated state in vivo is essential to understand for the successful use of MSC in regenerative therapies. Many researchers are, therefore, optimizing cell culture conditions in vitro by altering growth factors, extracellular matrices, chemicals, oxygen tension, and surrounding pH to enhance stem cells self-renewal or differentiation. Insulin-like growth factors (IGFs) system has been demonstrated to play an important role in stem cell biology to either promote proliferation and self-renewal or enhance differentiation onset and outcome, depending on the cell culture conditions. In this review, we will describe the importance of IGFs, IGF-1 and IGF-2, in development and in the MSC niche and how they affect the pluripotency or differentiation towards multiple lineages of the three germ layers.
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17
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Abstract
A continuous supply of glucose is necessary to ensure proper function and survival of all organs. Plasma glucose levels are thus maintained in a narrow range around 5 mM, which is considered the physiological set point. Glucose homeostasis is controlled primarily by the liver, fat, and skeletal muscle. Following a meal, most glucose disposals occur in the skeletal muscle, whereas fasting plasma glucose levels are determined primarily by glucose output from the liver. The balance between the utilization and production of glucose is primarily maintained at equilibrium by two opposing hormones, insulin and glucagon. In response to an elevation in plasma glucose and amino acids (after consumption of a meal), insulin is released from the beta cells of the islets of Langerhans in the pancreas. When plasma glucose falls (during fasting or exercise), glucagon is secreted by α cells, which surround the beta cells in the pancreas. Both cell types are extremely sensitive to glucose concentrations, can regulate hormone synthesis, and are released in response to small changes in plasma glucose levels. At the same time, insulin serves as the major physiological anabolic agent, promoting the synthesis and storage of glucose, lipids, and proteins and inhibiting their degradation and release back into the circulation. This chapter will focus mainly on signal transduction mechanisms by which insulin exerts its plethora of effects in liver, muscle, and fat cells, focusing on those pathways that are crucial in the control of glucose and lipid homeostasis.
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Affiliation(s)
- Alan R Saltiel
- Life Sciences Institute, University of Michigan, AnnArbor, MI, USA.
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18
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Schwarz JJ, Wiese H, Tölle RC, Zarei M, Dengjel J, Warscheid B, Thedieck K. Functional Proteomics Identifies Acinus L as a Direct Insulin- and Amino Acid-Dependent Mammalian Target of Rapamycin Complex 1 (mTORC1) Substrate. Mol Cell Proteomics 2015; 14:2042-55. [PMID: 25907765 DOI: 10.1074/mcp.m114.045807] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Indexed: 12/31/2022] Open
Abstract
The serine/threonine kinase mammalian target of rapamycin (mTOR) governs growth, metabolism, and aging in response to insulin and amino acids (aa), and is often activated in metabolic disorders and cancer. Much is known about the regulatory signaling network that encompasses mTOR, but surprisingly few direct mTOR substrates have been established to date. To tackle this gap in our knowledge, we took advantage of a combined quantitative phosphoproteomic and interactomic strategy. We analyzed the insulin- and aa-responsive phosphoproteome upon inhibition of the mTOR complex 1 (mTORC1) component raptor, and investigated in parallel the interactome of endogenous mTOR. By overlaying these two datasets, we identified acinus L as a potential novel mTORC1 target. We confirmed acinus L as a direct mTORC1 substrate by co-immunoprecipitation and MS-enhanced kinase assays. Our study delineates a triple proteomics strategy of combined phosphoproteomics, interactomics, and MS-enhanced kinase assays for the de novo-identification of mTOR network components, and provides a rich source of potential novel mTOR interactors and targets for future investigation.
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Affiliation(s)
- Jennifer Jasmin Schwarz
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg
| | - Heike Wiese
- §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany
| | - Regine Charlotte Tölle
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany
| | - Mostafa Zarei
- ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Jörn Dengjel
- ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg; ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Bettina Warscheid
- §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany;
| | - Kathrin Thedieck
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; ‡‡Department of Pediatrics, University of Groningen, University Medical Center Groningen (UMCG), 9713 AV Groningen, The Netherlands; §§Department for Neurosciences, Faculty VI - School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129 Oldenburg, Germany
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19
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Heberle AM, Prentzell MT, van Eunen K, Bakker BM, Grellscheid SN, Thedieck K. Molecular mechanisms of mTOR regulation by stress. Mol Cell Oncol 2015; 2:e970489. [PMID: 27308421 PMCID: PMC4904989 DOI: 10.4161/23723548.2014.970489] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 09/12/2014] [Accepted: 09/13/2014] [Indexed: 04/12/2023]
Abstract
Tumors are prime examples of cell growth in unfavorable environments that elicit cellular stress. The high metabolic demand and insufficient vascularization of tumors cause a deficiency of oxygen and nutrients. Oncogenic mutations map to signaling events via mammalian target of rapamycin (mTOR), metabolic pathways, and mitochondrial function. These alterations have been linked with cellular stresses, in particular endoplasmic reticulum (ER) stress, hypoxia, and oxidative stress. Yet tumors survive these challenges and acquire highly energy-demanding traits, such as overgrowth and invasiveness. In this review we focus on stresses that occur in cancer cells and discuss them in the context of mTOR signaling. Of note, many tumor traits require mTOR complex 1 (mTORC1) activity, but mTORC1 hyperactivation eventually sensitizes cells to apoptosis. Thus, mTORC1 activity needs to be balanced in cancer cells. We provide an overview of the mechanisms contributing to mTOR regulation by stress and suggest a model wherein stress granules function as guardians of mTORC1 signaling, allowing cancer cells to escape stress-induced cell death.
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Affiliation(s)
- Alexander Martin Heberle
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
| | - Mirja Tamara Prentzell
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
- Faculty of Biology; Institute for Biology 3; Albert-Ludwigs-University Freiburg; Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM); University of Freiburg; Freiburg, Germany
| | - Karen van Eunen
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
- Top Institute Food and Nutrition; Wageningen, The Netherlands
| | - Barbara Marleen Bakker
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
| | | | - Kathrin Thedieck
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
- Faculty of Biology; Institute for Biology 3; Albert-Ludwigs-University Freiburg; Freiburg, Germany
- School of Medicine and Health Sciences; Carl von Ossietzky University Oldenburg; Oldenburg, Germany
- BIOSS Centre for Biological Signaling Studies; Albert-Ludwigs-University Freiburg; Freiburg, Germany
- Correspondence to: Kathrin Thedieck; E-mail: ;
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20
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Vishwamitra D, Curry CV, Alkan S, Song YH, Gallick GE, Kaseb AO, Shi P, Amin HM. The transcription factors Ik-1 and MZF1 downregulate IGF-IR expression in NPM-ALK⁺ T-cell lymphoma. Mol Cancer 2015; 14:53. [PMID: 25884514 PMCID: PMC4415347 DOI: 10.1186/s12943-015-0324-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 02/17/2015] [Indexed: 01/18/2023] Open
Abstract
Background The type I insulin-like growth factor receptor (IGF-IR) tyrosine kinase promotes the survival of an aggressive subtype of T-cell lymphoma by interacting with nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) oncogenic protein. NPM-ALK+ T-cell lymphoma exhibits much higher levels of IGF-IR than normal human T lymphocytes. The mechanisms underlying increased expression of IGF-IR in this lymphoma are not known. We hypothesized that upregulation of IGF-IR could be attributed to previously unrecognized defects that inherently exist in the transcriptional machinery in NPM-ALK+ T-cell lymphoma. Methods and results Screening studies showed substantially lower levels of the transcription factors Ikaros isoform 1 (Ik-1) and myeloid zinc finger 1 (MZF1) in NPM-ALK+ T-cell lymphoma cell lines and primary tumor tissues from patients than in human T lymphocytes. A luciferase assay supported that Ik-1 and MZF1 suppress IGF-IR gene promoter. Furthermore, ChIP assay showed that these transcription factors bind specific sites located within the IGF-IR gene promoter. Forced expression of Ik-1 or MZF1 in the lymphoma cells decreased IGF-IR mRNA and protein. This decrease was associated with downregulation of pIGF-IR, and the phosphorylation of its interacting proteins IRS-1, AKT, and NPM-ALK. In addition, overexpression of Ik-1 and MZF1 decreased the viability, proliferation, migration, and anchorage-independent colony formation of the lymphoma cells. Conclusions Our results provide novel evidence that the aberrant decreases in Ik-1 and MZF1 contribute significantly to the pathogenesis of NPM-ALK+ T-cell lymphoma through the upregulation of IGF-IR expression. These findings could be exploited to devise new strategies to eradicate this lymphoma. Electronic supplementary material The online version of this article (doi:10.1186/s12943-015-0324-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Deeksha Vishwamitra
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas, USA. .,The University of Texas Graduate School of Biomedical Sciences, Houston, TX, 77030, USA.
| | - Choladda V Curry
- Department of Pathology and Immunology, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA.
| | - Serhan Alkan
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA.
| | - Yao-Hua Song
- Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, First Affiliated Hospital, Collaborative Innovation Center of Hematology, Soochow University, Suzhou, China.
| | - Gary E Gallick
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, 77030, USA. .,Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
| | - Ahmed O Kaseb
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
| | - Ping Shi
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.
| | - Hesham M Amin
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas, USA. .,The University of Texas Graduate School of Biomedical Sciences, Houston, TX, 77030, USA.
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21
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Liu X, Wang L, Chen J, Ling Q, Wang H, Li S, Li L, Yang S, Xia M, Jing L. Estrogen receptor β agonist enhances temozolomide sensitivity of glioma cells by inhibiting PI3K/AKT/mTOR pathway. Mol Med Rep 2014; 11:1516-22. [PMID: 25351348 DOI: 10.3892/mmr.2014.2811] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 09/19/2014] [Indexed: 11/05/2022] Open
Abstract
Glioma is the most common primary brain tumor among adults. Temozolomide (TMZ) is widely used as the first‑line postsurgical drug for malignant glioma. However, the therapeutic efficacy of TMZ remains ineffective as inherited or acquired drug resistance is frequently observed. Estrogen receptor β (ERβ) has emerged as a tumor suppressor and a key regulator of signal transduction in glioma cells. However, little is known about the role of ERβ in regulating the chemotherapeutic response to TMZ. In the current study, the TMZ‑resistant U138 glioma cells were treated with the novel ERβ agonist liquiritigenin (Liq). It was observed that Liq significantly enhanced ERβ expression and sensitized glioma cells to TMZ‑induced proliferation inhibition. As a potential mechanism, it was noted that Liq treatment significantly inhibited the activity of the PI3K/AKT/mTOR pathway, which played a protective role against the TMZ‑induced cytotoxicity. In addition, it was demonstrated that ERβ knockdown or activation of the phosphatidylinositol‑4,5‑bisphosphate 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway by insulin‑like growth factor 1 both eradicated the function of Liq. These results suggest that Liq treatment enhances glioma cell susceptibility to TMZ by inhibiting the PI3K/AKT/mTOR pathway. As hyperactivation of the PI3K/AKT/mTOR pathway is frequently observed in gliomas, the combined use of ERβ agonists may become a feasible therapy option to overcome chemoresistance to TMZ.
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Affiliation(s)
- Xiaoyang Liu
- School of Pharmaceutical Sciences, Jilin University, Changchun, Jilin 130021, P.R. China
| | - Libo Wang
- China‑Japan Union Hospital, Jilin University, Changchun, Jilin 130033, P.R. China
| | - Jiajun Chen
- China‑Japan Union Hospital, Jilin University, Changchun, Jilin 130033, P.R. China
| | - Qi Ling
- Jilin Medical College, Jilin, Jilin 132013, P.R. China
| | - Hongfei Wang
- Department of Vascular Surgery, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Shilin Li
- MOE Key Laboratory of Contemporary Anthropology and State Key Laboratory of Genetic Engineering and School of Life Sciences, Fudan University, Shanghai 200433, P.R. China
| | - Liming Li
- MOE Key Laboratory of Contemporary Anthropology and State Key Laboratory of Genetic Engineering and School of Life Sciences, Fudan University, Shanghai 200433, P.R. China
| | - Shuping Yang
- MOE Key Laboratory of Contemporary Anthropology and State Key Laboratory of Genetic Engineering and School of Life Sciences, Fudan University, Shanghai 200433, P.R. China
| | - Mingying Xia
- MOE Key Laboratory of Contemporary Anthropology and State Key Laboratory of Genetic Engineering and School of Life Sciences, Fudan University, Shanghai 200433, P.R. China
| | - Ling Jing
- School of Pharmaceutical Sciences, Jilin University, Changchun, Jilin 130021, P.R. China
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22
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Kim HK, Lee JS, Park MH, Cho JS, Yoon JH, Kim SJ, Kang HC. Tumorigenesis of papillary thyroid cancer is not BRAF-dependent in patients with acromegaly. PLoS One 2014; 9:e110241. [PMID: 25329702 PMCID: PMC4201528 DOI: 10.1371/journal.pone.0110241] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/12/2014] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Several studies have reported a high frequency of papillary thyroid cancer (PTC) in patients with acromegaly. The aim of this study was to determine the prevalence and predictors of thyroid cancer in patients with acromegaly and to investigate the frequency of the BRAFV600E mutation in PTC patients with and without acromegaly. MATERIALS AND METHODS We conducted a retrospective study of 60 patients with acromegaly. Thyroid ultrasonography (US) and US-guided fine needle aspiration were performed on nodules with sonographic features of malignancy. We selected 16 patients with non-acromegalic PTC as a control group. The BRAFV600E mutation was analyzed in paraffin-embedded surgical specimens of PTC by real-time polymerase chain reaction, and tumor specimens from patients with PTC were stained immunohistochemically with an antibody against insulin-like growth factor-1 receptor β (IGF-1Rβ). RESULTS Thyroid cancer was found in 15 (25.0%) patients. No differences in age, sex, initial growth hormone (GH) and IGF-1 percentage of the upper limit of normal values or treatment modalities were observed between patients with and without PTC. Acromegaly was active in 12 of 15 patients at the time of PTC diagnosis; uncontrolled acromegaly had a significantly higher frequency in the PTC group (60%) than in the non-PTC group (28.9%) (p = 0.030). The BRAFV600E mutation was present in only 9.1% (1/11) of PTC patients with acromegaly, although 62.5% (10/16) of control patients with PTC had the mutation (p = 0.007). IGF-1Rβ immunostaining showed moderate-to-strong staining in all malignant PTC cells in patients with and without acromegaly. Significantly less staining for IGF-1Rβ was observed in normal adjacent thyroid tissues of PTC patients with acromegaly compared with those without (p = 0.014). CONCLUSION The prevalence of PTC in acromegalic patients was high (25%). An uncontrolled hyperactive GH-IGF-1 axis may play a dominant role in the development of PTC rather than the BRAFV600E mutation in patients with acromegaly.
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Affiliation(s)
- Hee Kyung Kim
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Ji Shin Lee
- Department of Pathology, Chonnam National University Medical School, Gwangju, Korea
| | - Min Ho Park
- Department of Surgery, Chonnam National University Medical School, Gwangju, Korea
| | - Jin Seong Cho
- Department of Surgery, Chonnam National University Medical School, Gwangju, Korea
| | - Jee Hee Yoon
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Soo Jeong Kim
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Ho-Cheol Kang
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
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Ureshino RP, Rocha KK, Lopes GS, Bincoletto C, Smaili SS. Calcium signaling alterations, oxidative stress, and autophagy in aging. Antioxid Redox Signal 2014; 21:123-37. [PMID: 24512092 DOI: 10.1089/ars.2013.5777] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
SIGNIFICANCE Aging is a multi-factorial process that may be associated with several functional and structural deficits which can evolve into degenerative diseases. In this review, we present data that may depict an expanded view of molecular aging theories, beginning with the idea that reactive oxygen species (ROS) are the major effectors in this process. In addition, we have correlated the importance of autophagy as a neuroprotective mechanism and discussed a link between age-related molecules, Ca(2+) signaling, and oxidative stress. RECENT ADVANCES There is evidence suggesting that alterations in Ca(2+) homeostasis, including mitochondrial Ca(2+) overload and alterations in electron transport chain (ETC) complexes, which increase cell vulnerability, are linked to oxidative stress in aging. As much as Ca(2+) signaling is altered in aged cells, excess ROS can be produced due to an ineffective coupling of mitochondrial respiration. Damaged mitochondria might not be removed by the macroautophagic system, which is hampered in aging by lipofuscin accumulation, boosting ROS generation, damaging DNA, and, ultimately, leading to apoptosis. CRITICAL ISSUES This process can lead to altered protein expression (such as p53, Sirt1, and IGF-1) and progress to cell death. This cycle can lead to increased cell vulnerability in aging and contribute to an increased susceptibility to degenerative processes. FUTURE DIRECTIONS A better understanding of Ca(2+) signaling and molecular aging alterations is important for preventing apoptosis in age-related diseases. In addition, caloric restriction, resveratrol and autophagy modulation appear to be predominantly cytoprotective, and further studies of this process are promising in age-related disease therapeutics.
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Osorio EY, Travi BL, da Cruz AM, Saldarriaga OA, Medina AA, Melby PC. Growth factor and Th2 cytokine signaling pathways converge at STAT6 to promote arginase expression in progressive experimental visceral leishmaniasis. PLoS Pathog 2014; 10:e1004165. [PMID: 24967908 PMCID: PMC4072777 DOI: 10.1371/journal.ppat.1004165] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 04/21/2014] [Indexed: 12/26/2022] Open
Abstract
Host arginase 1 (arg1) expression is a significant contributor to the pathogenesis of progressive visceral leishmaniasis (VL), a neglected tropical disease caused by the intracellular protozoan Leishmania donovani. Previously we found that parasite-induced arg1 expression in macrophages was dependent on STAT6 activation. Arg1 expression was amplified by, but did not require, IL-4, and required de novo synthesis of unknown protein(s). To further explore the mechanisms involved in arg1 regulation in VL, we screened a panel of kinase inhibitors and found that inhibitors of growth factor signaling reduced arg1 expression in splenic macrophages from hamsters with VL. Analysis of growth factors and their signaling pathways revealed that the Fibroblast Growth Factor Receptor 1 (FGFR-1) and Insulin-like Growth Factor 1 Receptor (IGF-1R) and a number of downstream signaling proteins were activated in splenic macrophages isolated from hamsters infected with L. donovani. Recombinant FGF-2 and IGF-1 increased the expression of arg1 in L. donovani infected hamster macrophages, and this induction was augmented by IL-4. Inhibition of FGFR-1 and IGF-1R decreased arg1 expression and restricted L. donovani replication in both in vitro and ex vivo models of infection. Inhibition of the downstream signaling molecules JAK and AKT also reduced the expression of arg1 in infected macrophages. STAT6 was activated in infected macrophages exposed to either FGF-2 or IGF-1, and STAT6 was critical to the FGFR-1- and IGF-1R-mediated expression of arg1. The converse was also true as inhibition of FGFR-1 and IGF-1R reduced the activation of STAT6 in infected macrophages. Collectively, these data indicate that the FGFR/IGF-1R and IL-4 signaling pathways converge at STAT6 to promote pathologic arg1 expression and intracellular parasite survival in VL. Targeted interruption of these pathological processes offers an approach to restrain this relentlessly progressive disease. Visceral leishmaniasis (VL), caused by the intracellular protozoan Leishmania donovani, is a progressive infection that is particularly common in impoverished populations of the world. People die from this disease unless it is treated. We used an experimental infection model that mimics the clinical and pathological features of human VL to study how the parasite causes this severe disease. We found that host macrophages infected with Leishmania donovani are activated in a way that leads to the expression of arginase, an enzyme that counteracts the cell's mechanisms that control the infection. This disease-promoting activation pathway was driven by the convergence of growth factor and cytokine signaling pathways and activation of the transcription factor STAT6. Chemical inhibition of signaling through the fibroblast growth factor receptor-1 (FGFR-1) or insulin-like growth factor-1 receptor (IGF-IR), or genetic knockdown of STAT6 led to reduced expression of arginase and enhanced control of the infection by macrophages. This indicates that the growth factor signaling pathways together with the cytokine pathways promote this disease. Interventions designed to disrupt this signaling could help in the treatment of VL.
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Affiliation(s)
- E Yaneth Osorio
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America; Laboratório Interdisciplinar de Pesquisas Médicas (LIPMED), Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, Brazil
| | - Bruno L Travi
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America; Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Alda M da Cruz
- Laboratório Interdisciplinar de Pesquisas Médicas (LIPMED), Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, Brazil
| | - Omar A Saldarriaga
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Audrie A Medina
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Peter C Melby
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America; Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America; Center for Tropical Diseases, and Institute for Human Infection and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America; Department of Pathology, and Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, United States of America
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Leiphrakpam PD, Rajput A, Mathiesen M, Agarwal E, Lazenby AJ, Are C, Brattain MG, Chowdhury S. Ezrin expression and cell survival regulation in colorectal cancer. Cell Signal 2014; 26:868-79. [PMID: 24462708 PMCID: PMC3974425 DOI: 10.1016/j.cellsig.2014.01.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 01/09/2014] [Accepted: 01/13/2014] [Indexed: 12/24/2022]
Abstract
Colorectal cancer (CRC) is the second largest cause of cancer deaths in the United States. A key barrier that prevents better outcomes for this type of cancer as well as other solid tumors is the lack of effective therapies against the metastatic disease. Thus there is an urgent need to fill this gap in cancer therapy. We utilized a 2D-DIGE proteomics approach to identify and characterize proteins that are differentially regulated between primary colon tumor and liver metastatic deposits of the IGF1R-dependent GEO human CRC xenograft, orthotopically implanted in athymic nude mice that may serve as potential therapeutic targets against CRC metastasis. We observed increased expression of ezrin in liver metastasis in comparison to the primary colonic tumor. Increased ezrin expression was further confirmed by western blot and microarray analyses. Ezrin, a cytoskeletal protein belonging to Ezrin-Radixin-Moesin (ERM) family plays important roles in cell motility, invasion and metastasis. However, its exact function in colorectal cancer is not well characterized. Establishment of advanced GEO cell lines with enhanced liver-metastasizing ability showed a significant increase in ezrin expression in liver metastasis. Increased phosphorylation of ezrin at the T567 site (termed here as p-ezrin T567) was observed in liver metastasis. IHC studies of human CRC patient specimens showed an increased expression of p-ezrin T567 in liver metastasis compared to the primary tumors of the same patient. Ezrin modulation by siRNA, inhibitors and T567A/D point mutations significantly downregulated inhibitors of apoptosis (IAP) proteins XIAP and survivin that have been linked to increased aberrant cell survival and metastasis and increased cell death. Inhibition of the IGF1R signaling pathway by humanized recombinant IGF1R monoclonal antibody MK-0646 in athymic mouse subcutaneous xenografts resulted in inhibition of p-ezrin T567 indicating ezrin signaling is downstream of the IGF1R signaling pathway. We identified increased expression of p-ezrin T567 in CRC liver metastasis in both orthotopically implanted GEO tumors as well as human patient specimens. We report for the first time that p-ezrin T567 is downstream of the IGF1R signaling and demonstrate that ezrin regulates cell survival through survivin/XIAP modulation.
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Affiliation(s)
- Premila D Leiphrakpam
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, 985950 Nebraska Medical Center, Omaha, NE 68198-5950, United States
| | - Ashwani Rajput
- Department of Surgery, University of New Mexico Health Science Center, 1 University of New Mexico, Albuquerque, NM 87131-0001, United States
| | - Michelle Mathiesen
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, 985950 Nebraska Medical Center, Omaha, NE 68198-5950, United States
| | - Ekta Agarwal
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, 985950 Nebraska Medical Center, Omaha, NE 68198-5950, United States
| | - Audrey J Lazenby
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 983515 Nebraska Medical Center, Omaha, NE 68198-3135, United States
| | - Chandrakanth Are
- Department of Surgical Oncology, University of Nebraska Medical Center, 984533 Nebraska Medical Center, Omaha, NE 68198-4533, United States
| | - Michael G Brattain
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, 985950 Nebraska Medical Center, Omaha, NE 68198-5950, United States.
| | - Sanjib Chowdhury
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, 985950 Nebraska Medical Center, Omaha, NE 68198-5950, United States.
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26
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Youssef A, Iosef C, Han VKM. Low-oxygen tension and IGF-I promote proliferation and multipotency of placental mesenchymal stem cells (PMSCs) from different gestations via distinct signaling pathways. Endocrinology 2014; 155:1386-97. [PMID: 24506070 DOI: 10.1210/en.2013-1842] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The microenvironment of placental mesenchymal stem cells (PMSCs) is dynamic throughout gestation and determines changes in cell fate. In vivo, PMSCs initially develop in low-oxygen tension and low IGF-I concentrations, and both increase gradually with gestation. The impact of varying concentrations of IGF-I and changing oxygen tension on PMSC signaling and multipotency was investigated in PMSCs from early (preterm) and late (term) gestation human placentae. Preterm PMSCs had greater proliferative response to IGF-I, which was further enhanced by low-oxygen tension. Low-oxygen tension alone was sufficient to induce ERK1/2 phosphorylation, whereas IGF-I was required for AKT (protein kinase B) phosphorylation. Low-oxygen tension prolonged ERK1/2 and AKT phosphorylation with a slowed phosphorylation decay even in presence of IGF-I. Low-oxygen tension maintained higher levels of IGF-I receptor and insulin receptor substrate 1 that were otherwise decreased by exposure to IGF-I and induced a differential phosphorylation pattern on IGF-I receptorβ and insulin receptor substrate 1. Phosphorylation of ERK1/2 and AKT was different between the preterm and term PMSCs, and phospho-AKT, and not phospho-ERK1/2, was the major determinant of PMSC proliferation and octamer-4 levels. These studies demonstrate that low-oxygen tension regulates the fate of PMSCs from early and late gestations in response to IGF-I, both independently and dependently, via specific signal transduction mechanisms.
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Affiliation(s)
- Amer Youssef
- Departments of Biochemistry (A.Y., V.K.M.H.) and Paediatrics (C.I., V.K.M.H.), Schulich School of Medicine and Dentistry; Children's Health Research Institute (A.Y., C.I., V.K.M.H.); and Lawson Health Research Institute (A.Y., C.I., V.K.M.H.); Western University, London, Ontario, Canada N6C 2V5
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27
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Leiphrakpam PD, Agarwal E, Mathiesen M, Haferbier KL, Brattain MG, Chowdhury S. In vivo analysis of insulin-like growth factor type 1 receptor humanized monoclonal antibody MK-0646 and small molecule kinase inhibitor OSI-906 in colorectal cancer. Oncol Rep 2013; 31:87-94. [PMID: 24173770 PMCID: PMC3868504 DOI: 10.3892/or.2013.2819] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 09/20/2013] [Indexed: 01/15/2023] Open
Abstract
The development and characterization of effective anticancer drugs against colorectal cancer (CRC) is of urgent need since it is the second most common cause of cancer death. The study was designed to evaluate the effects of two IGF-1R antagonists, MK-0646, a recombinant fully humanized monoclonal antibody and OSI-906, a small molecule tyrosine kinase inhibitor on CRC cells. Xenograft study was performed on IGF-1R-dependent CRC cell lines for analyzing the antitumor activity of MK-0646 and OSI-906. Tumor proliferation and apoptosis were assessed using Ki67 and TUNEL assays, respectively. We also performed in vitro characterization of MK-0646 and OSI-906 treatment on CRC cells to identify mechanisms associated with drug-induced cell death. Exposure of the GEO and CBS tumor xenografts to MK-0646 or OSI-906 led to a decrease in tumor growth. TUNEL analysis showed an increase of approximately 45-55% in apoptotic cells in both MK-0646 and OSI-906 treated tumor samples. We report the novel finding that treatment with IGF-1R antagonists led to downregulation of X-linked inhibitor of apoptosis (XIAP) protein involved in cell survival and inhibition of cell death. In conclusion, IGF-1R antagonists (MK-0646 and OSI-906) demonstrated single agent inhibition of subcutaneous CRC xenograft growth. This was coupled to pro-apoptotic effects resulting in downregulation of XIAP and inhibition of cell survival. We report a novel mechanism by which MK-0646 and OSI-906 elicits cell death in vivo and in vitro. Moreover, these results indicate that MK-0646 and OSI-906 may be potential anticancer candidates for the treatment of patients with IGF-1R-dependent CRC.
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Affiliation(s)
- Premila D Leiphrakpam
- Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-5950, USA
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28
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Maga JA, Zhou J, Kambampati R, Peng S, Wang X, Bohnsack RN, Thomm A, Golata S, Tom P, Dahms NM, Byrne BJ, LeBowitz JH. Glycosylation-independent lysosomal targeting of acid α-glucosidase enhances muscle glycogen clearance in pompe mice. J Biol Chem 2012. [PMID: 23188827 PMCID: PMC3548456 DOI: 10.1074/jbc.m112.438663] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We have used a peptide-based targeting system to improve lysosomal delivery of acid α-glucosidase (GAA), the enzyme deficient in patients with Pompe disease. Human GAA was fused to the glycosylation-independent lysosomal targeting (GILT) tag, which contains a portion of insulin-like growth factor II, to create an active, chimeric enzyme with high affinity for the cation-independent mannose 6-phosphate receptor. GILT-tagged GAA was taken up by L6 myoblasts about 25-fold more efficiently than was recombinant human GAA (rhGAA). Once delivered to the lysosome, the mature form of GILT-tagged GAA was indistinguishable from rhGAA and persisted with a half-life indistinguishable from rhGAA. GILT-tagged GAA was significantly more effective than rhGAA in clearing glycogen from numerous skeletal muscle tissues in the Pompe mouse model. The GILT-tagged GAA enzyme may provide an improved enzyme replacement therapy for Pompe disease patients.
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Affiliation(s)
- John A Maga
- ZyStor Therapeutics, Milwaukee, Wisconsin 53226-4838, USA
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29
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The insulin and igf-I pathway in endocrine glands carcinogenesis. JOURNAL OF ONCOLOGY 2012; 2012:635614. [PMID: 22927847 PMCID: PMC3423951 DOI: 10.1155/2012/635614] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 06/20/2012] [Indexed: 12/26/2022]
Abstract
Endocrine cancers are a heterogeneous group of diseases that may arise from endocrine cells in any gland of the endocrine system. These malignancies may show an aggressive behavior and resistance to the common anticancer therapies. The etiopathogenesis of these tumors remains mostly unknown. The normal embryological development and differentiation of several endocrine glands are regulated by specific pituitary tropins, which, in adult life, control the function and trophism of the endocrine gland. Pituitary tropins act in concert with peptide growth factors, including the insulin-like growth factors (IGFs), which are considered key regulators of cell growth, proliferation, and apoptosis. While pituitary TSH is regarded as tumor-promoting factor for metastatic thyroid cancer, the role of other pituitary hormones in endocrine cancers is uncertain. However, multiple molecular abnormalities of the IGF system frequently occur in endocrine cancers and may have a role in tumorigenesis as well as in tumor progression and resistance to therapies. Herein, we will review studies indicating a role of IGF system dysregulation in endocrine cancers and will discuss the possible implications of these findings for tumor prevention and treatment, with a major focus on cancers from the thyroid, adrenal, and ovary, which are the most extensively studied.
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30
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Dalle Pezze P, Sonntag AG, Thien A, Prentzell MT, Gödel M, Fischer S, Neumann-Haefelin E, Huber TB, Baumeister R, Shanley DP, Thedieck K. A dynamic network model of mTOR signaling reveals TSC-independent mTORC2 regulation. Sci Signal 2012; 5:ra25. [PMID: 22457331 DOI: 10.1126/scisignal.2002469] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The kinase mammalian target of rapamycin (mTOR) exists in two multiprotein complexes (mTORC1 and mTORC2) and is a central regulator of growth and metabolism. Insulin activation of mTORC1, mediated by phosphoinositide 3-kinase (PI3K), Akt, and the inhibitory tuberous sclerosis complex 1/2 (TSC1-TSC2), initiates a negative feedback loop that ultimately inhibits PI3K. We present a data-driven dynamic insulin-mTOR network model that integrates the entire core network and used this model to investigate the less well understood mechanisms by which insulin regulates mTORC2. By analyzing the effects of perturbations targeting several levels within the network in silico and experimentally, we found that, in contrast to current hypotheses, the TSC1-TSC2 complex was not a direct or indirect (acting through the negative feedback loop) regulator of mTORC2. Although mTORC2 activation required active PI3K, this was not affected by the negative feedback loop. Therefore, we propose an mTORC2 activation pathway through a PI3K variant that is insensitive to the negative feedback loop that regulates mTORC1. This putative pathway predicts that mTORC2 would be refractory to Akt, which inhibits TSC1-TSC2, and, indeed, we found that mTORC2 was insensitive to constitutive Akt activation in several cell types. Our results suggest that a previously unknown network structure connects mTORC2 to its upstream cues and clarifies which molecular connectors contribute to mTORC2 activation.
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Affiliation(s)
- Piero Dalle Pezze
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, UK
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31
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Grierson PM, Lillard K, Behbehani GK, Combs KA, Bhattacharyya S, Acharya S, Groden J. BLM helicase facilitates RNA polymerase I-mediated ribosomal RNA transcription. Hum Mol Genet 2011; 21:1172-83. [PMID: 22106380 DOI: 10.1093/hmg/ddr545] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bloom's syndrome (BS) is an autosomal recessive disorder that is invariably characterized by severe growth retardation and cancer predisposition. The Bloom's syndrome helicase (BLM), mutations of which lead to BS, localizes to promyelocytic leukemia protein bodies and to the nucleolus of the cell, the site of RNA polymerase I-mediated ribosomal RNA (rRNA) transcription. rRNA transcription is fundamental for ribosome biogenesis and therefore protein synthesis, cellular growth and proliferation; its inhibition limits cellular growth and proliferation as well as bodily growth. We report that nucleolar BLM facilitates RNA polymerase I-mediated rRNA transcription. Immunofluorescence studies demonstrate the dependance of BLM nucleolar localization upon ongoing RNA polymerase I-mediated rRNA transcription. In vivo protein co-immunoprecipitation demonstrates that BLM interacts with RPA194, a subunit of RNA polymerase I. (3)H-uridine pulse-chase assays demonstrate that BLM expression is required for efficient rRNA transcription. In vitro helicase assays demonstrate that BLM unwinds GC-rich rDNA-like substrates that form in the nucleolus and normally inhibit progression of the RNA polymerase I transcription complex. These studies suggest that nucleolar BLM modulates rDNA structures in association with RNA polymerase I to facilitate RNA polymerase I-mediated rRNA transcription. Given the intricate relationship between rDNA metabolism and growth, our data may help in understanding the etiology of proportional dwarfism in BS.
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Affiliation(s)
- Patrick M Grierson
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, OH 43210-2207, USA
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Ammoun S, Hanemann CO. Emerging therapeutic targets in schwannomas and other merlin-deficient tumors. Nat Rev Neurol 2011; 7:392-9. [DOI: 10.1038/nrneurol.2011.82] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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33
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Heskamp S, van Laarhoven HWM, Molkenboer-Kuenen JDM, Franssen GM, Versleijen-Jonkers YMH, Oyen WJG, van der Graaf WTA, Boerman OC. ImmunoSPECT and immunoPET of IGF-1R expression with the radiolabeled antibody R1507 in a triple-negative breast cancer model. J Nucl Med 2010; 51:1565-72. [PMID: 20847162 DOI: 10.2967/jnumed.110.075648] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
UNLABELLED The insulinlike growth factor 1 receptor (IGF-1R) is a new target for the treatment of breast cancer. Patients with breast cancer lesions that express IGF-1R may benefit from treatment with anti-IGF-1R antibodies. Therefore, the aim of the present study was to develop a noninvasive, in vivo imaging method, using radiolabeled antibodies, to visualize IGF-1R expression. METHODS R1507 is a monoclonal antibody directed against the IGF-1R. In vitro, the affinity and internalization kinetics of (111)In-R1507 were determined using the IGF-1R-expressing triple-negative breast cancer cell line SUM149. In vivo, the pharmacodynamics of (111)In-R1507 and (125)I-R1507 were determined in mice with subcutaneous SUM149 tumors. (111)In-R1507 SPECT and (89)Zr-R1507 PET images of mice with subcutaneous SUM149 tumors were acquired at 1, 3, and 7 d after injection. RESULTS (111)In-R1507 (concentration required to inhibit binding by 50%, 0.1 nM) was slowly internalized by SUM149 cells. (111)In-R1507 specifically and efficiently accumulated in the SUM149 xenografts: the tumor uptake was 20 percentage injected dose per gram (%ID/g), 33 %ID/g, and 31 %ID/g at 1, 3, and 7 d after injection, respectively. (125)I-R1507 accumulated in the tumor less efficiently. Small-animal SPECT and small-animal PET of mice clearly visualized the subcutaneous SUM149 xenograft, with increasing contrast at later time points. CONCLUSION (111)In-R1507 and (89)Zr-R1507 are new tracers to noninvasively determine IGF-1R expression in vivo in breast cancer xenografts using SPECT and PET. In the future, these techniques may enable patient selection for IGF-1R-targeted therapy.
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Affiliation(s)
- Sandra Heskamp
- Department of Medical Oncology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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34
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Ikushima M, Ishii M, Ohishi M, Yamamoto K, Ogihara T, Rakugi H, Kurachi Y. ANG II inhibits insulin-mediated production of PI 3,4,5-trisphosphates via a Ca2+-dependent but PKC-independent pathway in the cardiomyocytes. Am J Physiol Heart Circ Physiol 2010; 299:H680-9. [DOI: 10.1152/ajpheart.00220.2009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Insulin resistance (IR) is a condition where different organs are refractory to insulin stimulation of glucose uptake. ANG II has been suggested to be involved in the development of IR in the heart. The precise mechanism by which this occurs is still unknown. Here we have used dynamic fluorescent imaging techniques to show that ANG II inhibits insulin production of phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] in cardiac myocytes. Fluorophore (Venus)-conjugated cAMP-dependent protein kinase-pleckstrin homology domain, which specifically binds to PI(3,4,5)P3, was transfected in neonatal rat cardiac myocytes. Insulin induced a robust increase in the fluorescence intensity at the cell surface, which was diminished by application of ANG II. The inhibitory action of ANG II was antagonized by RNH-6270 (an angiotensin type 1 receptor antagonist) but not by PD-122370 (an angiotensin type 2 receptor antagonist). BAPTA-AM (Ca2+ chelator) largely attenuated the ANG II effect, whereas K-252b (PKC inhibitor) did not. Furthermore, an elevation of intracellular Ca2+ induced by ionomycin mimicked the ANG II effect. Therefore, it is suggested that ANG II antagonizes insulin-mediated production of PI(3,4,5)P3 via a Ca2+-dependent but PKC-independent pathway in cardiac myocytes.
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Affiliation(s)
- Masashi Ikushima
- Departments of 1Pharmacology and
- Geriatric Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
| | | | - Mitsuru Ohishi
- Geriatric Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Koichi Yamamoto
- Geriatric Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Toshio Ogihara
- Geriatric Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hiromi Rakugi
- Geriatric Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
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DeAngelis T, Morrione A, Baserga R. Mutual interaction and reciprocal down-regulation between c-met and insulin receptor substrate-1. J Cell Physiol 2010; 224:658-63. [PMID: 20578241 DOI: 10.1002/jcp.22164] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The insulin receptor substrate-1 (IRS-1) and c-met, the receptor for the hepatocyte growth factor (HGF) co-immuno-precipitate from lysates treated with the respective antibodies. The interaction between IRS-1 and c-met requires a tyrosyl phosphorylated IRS-1 and results in reciprocal down-regulation. IRS-1 inhibits cell motility, while the activated c-met promotes it. These and other results suggest an explanation for reports in the literature indicating that c-met levels are high and IRS-1 levels are low in human cancer metastases.
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Affiliation(s)
- Tiziana DeAngelis
- Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Gridelli C, Rossi A, Bareschino MA, Schettino C, Sacco PC, Maione P. The potential role of insulin-like growth factor receptor inhibitors in the treatment of advanced non-small cell lung cancer. Expert Opin Investig Drugs 2010; 19:631-9. [PMID: 20367288 DOI: 10.1517/13543781003767434] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
IMPORTANCE OF THE FIELD Lung cancer is the leading cause of cancer-related mortality worldwide. NSCLC accounts for > 80% of all lung cancers. The treatment of advanced fit NSCLC patients seems to have reached a plateau. Considerable efforts have been initiated to identify new biological agents. AREAS COVERED IN THIS REVIEW Diagnosis of NSCLC histotype is becoming extremely important to address treatment. While non-squamous histology could start to benefit from the administration of several new drugs only recently, non-adenocarcinoma subtype seems to benefit from the administration of figitumumab (CP-751,871) a fully human anti-IGF 1 receptor (IGF-1R) mAb. In this paper, we reviewed the IGF-1R pathway and its inhibitors. WHAT THE READER WILL GAIN Approaches targeting IGF-1R include small-molecule IGF-1R tyrosine kinase inhibitors (TKIs), which are in preclinical and early clinical phases of development, and the mAbs, among which figitumumab is being investigated in Phase III trials of advanced NSCLC. TAKE HOME MESSAGE Figitumumab reported interesting results in the treatment of advanced non-adenocarcinoma NSCLC patients. Overall, in order to administer the optimal treatment to patients, a more definite histological diagnosis is mandatory.
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Affiliation(s)
- Cesare Gridelli
- SG Moscati Hospital, Division of Medical Oncology, Avellino, Italy.
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37
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Zhang TT, Li H, Cheung SM, Costantini JL, Hou S, Al-Alwan M, Marshall AJ. Phosphoinositide 3-kinase-regulated adapters in lymphocyte activation. Immunol Rev 2010; 232:255-72. [PMID: 19909369 DOI: 10.1111/j.1600-065x.2009.00838.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Signaling via phosphoinositide 3-kinases (PI3Ks) has emerged as a central component of lymphocyte activation via immunoreceptors, costimulatory receptors, cytokine receptors, and chemokine receptors. The discovery of phosphoinositide-binding pleckstrin homology (PH) domains has substantially increased understanding of how PI3Ks activate cellular responses. Accumulating evidence indicates that PH-domain containing adapter molecules provide important links between PI3K and lymphocyte function. Here, we review data on PI3K-regulated adapter proteins of the Grb-associated binder (GAB), Src kinase-associated phosphoprotein (SKAP), and B-lymphocyte adapter molecule of 32 kDa (Bam32)/ dual-adapter for phosphotyrosine and 3-phosphoinositides (DAPP)/TAPP families, with a focus on the latter group. Current data support the model that recruitment of these adapters to the plasma membrane of activated lymphocytes is driven by the phosphoinositides phosphatidylinositol-3,4,5-tris-phosphate and phosphatidylinositol-3,4-bisphosphate, generated through the action of PI3Ks and under the regulatory control of lipid phosphatases Src homology 2 domain-containing inositol phosphatase (SHIP), phosphatase and tensin homolog, and inositol polyphosphate 4-phosphatase. At the plasma membrane, these adapters serve to assemble distinct protein complexes. Bam32/DAPP1 and SKAPs function to promote activation of monomeric guanosine triphosphatases, including Rac and Rap, and promote integrin activation, lymphocyte adhesion to matrix proteins, and cell:cell interactions between B and T lymphocytes. GABs can provide feedforward amplification or feedback inhibition of PI3K signaling. Current work is further defining the molecular interactions driven by these molecules and identifying the functions of TAPP adapters, which also appear to be involved in lymphocyte adhesion and are specific effectors downstream of the SHIP product phosphatidylinositol-3,4-bisphosphate.
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Affiliation(s)
- Ting-Ting Zhang
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
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Mardilovich K, Pankratz SL, Shaw LM. Expression and function of the insulin receptor substrate proteins in cancer. Cell Commun Signal 2009; 7:14. [PMID: 19534786 PMCID: PMC2709114 DOI: 10.1186/1478-811x-7-14] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2009] [Accepted: 06/17/2009] [Indexed: 12/13/2022] Open
Abstract
The Insulin Receptor Substrate (IRS) proteins are cytoplasmic adaptor proteins that function as essential signaling intermediates downstream of activated cell surface receptors, many of which have been implicated in cancer. The IRS proteins do not contain any intrinsic kinase activity, but rather serve as scaffolds to organize signaling complexes and initiate intracellular signaling pathways. As common intermediates of multiple receptors that can influence tumor progression, the IRS proteins are positioned to play a pivotal role in regulating the response of tumor cells to many different microenvironmental stimuli. Limited studies on IRS expression in human tumors and studies on IRS function in human tumor cell lines and in mouse models have provided clues to the potential function of these adaptor proteins in human cancer. A general theme arises from these studies; IRS-1 and IRS-4 are most often associated with tumor growth and proliferation and IRS-2 is most often associated with tumor motility and invasion. In this review, we discuss the mechanisms by which IRS expression and function are regulated and how the IRS proteins contribute to tumor initiation and progression.
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Affiliation(s)
- Katerina Mardilovich
- Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
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Menzies KK, Lefèvre C, Macmillan KL, Nicholas KR. Insulin regulates milk protein synthesis at multiple levels in the bovine mammary gland. Funct Integr Genomics 2008; 9:197-217. [PMID: 19107532 DOI: 10.1007/s10142-008-0103-x] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 11/25/2008] [Accepted: 11/25/2008] [Indexed: 01/24/2023]
Abstract
The role of insulin in milk protein synthesis is unresolved in the bovine mammary gland. This study examined the potential role of insulin in the presence of two lactogenic hormones, hydrocortisone and prolactin, in milk protein synthesis. Insulin was shown to stimulate milk protein gene expression, casein synthesis and (14)C-lysine uptake in mammary explants from late pregnant cows. A global assessment of changes in gene expression in mammary explants in response to insulin was undertaken using Affymetrix microarray. The resulting data provided insight into the molecular mechanisms stimulated by insulin and showed that the hormone stimulated the expression of 28 genes directly involved in protein synthesis. These genes included the milk protein transcription factor, ELF5, translation factors, the folate metabolism genes, FOLR1 and MTHFR, as well as several genes encoding enzymes involved in catabolism of essential amino acids and biosynthesis of non-essential amino acids. These data show that insulin is not only essential for milk protein gene expression, but stimulates milk protein synthesis at multiple levels within bovine mammary epithelial cells.
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Affiliation(s)
- Karensa K Menzies
- Department of Zoology, University of Melbourne, Parkville, VIC, Australia.
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40
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Adenylyl cyclases types 1 and 8 promote pro-survival pathways after ethanol exposure in the neonatal brain. Neurobiol Dis 2008; 33:111-8. [PMID: 18992344 DOI: 10.1016/j.nbd.2008.09.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 09/24/2008] [Accepted: 09/26/2008] [Indexed: 12/31/2022] Open
Abstract
Although a wide range of developmental disabilities following fetal alcohol exposure are observed clinically, the molecular factors that determine the severity of these sequelae remain undefined. In mice exposed to ethanol, deletion of adenylyl cyclases (ACs) 1 and 8 exacerbates the neuroapoptosis that occurs in a prolonged post-treatment period; however, it remains unclear whether AC1 and AC8 are critical to the primary or secondary mechanisms underlying ethanol-induced neurodegeneration. Here we demonstrate that mice lacking AC1 and AC8 (DKO) display significantly increased apoptosis in the striatum, a region sensitive to neuroapoptosis in the acute post-treatment period, compared to WT controls. The enhanced neuroapoptotic response observed in the striatum of DKO mice is accompanied by significant reductions in phosphorylation of known pro-survival proteins, insulin receptor substrate-1 (IRS-1), Akt and extracellular signal-regulated kinases (ERKs). These data suggest that AC1/AC8 are crucial activators of cell survival signaling pathways acutely following ethanol exposure and represent molecular factors that may directly modulate the severity of symptoms associated with Fetal Alcohol Syndrome.
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Evolution of the phospho-tyrosine signaling machinery in premetazoan lineages. Proc Natl Acad Sci U S A 2008; 105:9680-4. [PMID: 18599463 DOI: 10.1073/pnas.0803161105] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multicellular animals use a three-part molecular toolkit to mediate phospho-tyrosine signaling: Tyrosine kinases (TyrK), protein tyrosine phosphatases (PTP), and Src Homology 2 (SH2) domains function, respectively, as "writers," "erasers," and "readers" of phospho-tyrosine modifications. How did this system of three components evolve, given their interdependent function? Here, we examine the usage of these components in 41 eukaryotic genomes, including the newly sequenced genome of the choanoflagellate, Monosiga brevicollis, the closest known unicellular relative to metazoans. This analysis indicates that SH2 and PTP domains likely evolved earliest-a handful of these domains are found in premetazoan eukaryotes lacking tyrosine kinases, most likely to deal with limited tyrosine phosphorylation cross-catalyzed by promiscuous Ser/Thr kinases. Modern TyrK proteins, however, are only observed in two lineages, metazoans and choanoflagellates. These two lineages show a dramatic coexpansion of all three domain families. Concurrent expansion of the three domain families is consistent with a stepwise evolutionary model in which preexisting SH2 and PTP domains were of limited utility until the appearance of the TyrK domain in the last common ancestor of metazoans and choanoflagellates. The emergence of the full three-component signaling system, with its dramatically increased encoding potential, may have contributed to the advent of metazoan multicellularity.
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Sutherland BW, Knoblaugh SE, Kaplan-Lefko PJ, Wang F, Holzenberger M, Greenberg NM. Conditional Deletion of Insulin-like Growth Factor-I Receptor in Prostate Epithelium. Cancer Res 2008; 68:3495-504. [DOI: 10.1158/0008-5472.can-07-6531] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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43
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Quesada A, Lee BY, Micevych PE. PI3 kinase/Akt activation mediates estrogen and IGF-1 nigral DA neuronal neuroprotection against a unilateral rat model of Parkinson's disease. Dev Neurobiol 2008; 68:632-44. [PMID: 18278798 PMCID: PMC2667142 DOI: 10.1002/dneu.20609] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Recently, using the medial forebrain bundle (MFB) 6-hydroxydopmaine (6-OHDA) lesion rat model of Parkinson's disease (PD), we have demonstrated that blockade of central IGF-1 receptors (IGF-1R) attenuated estrogen neuroprotection of substantia nigra pars compacta (SNpc) DA neurons, but exacerbated 6-OHDA lesions in IGF-1 only treated rats (Quesada and Micevych [2004]: J Neurosci Res 75:107-116). This suggested that the IGF-1 system is a central mechanism through which estrogen acts to protect the nigrostriatal DA system. Moreover, these results also suggest that IGF-1R-induced intracellular signaling pathways are involved in the estrogen mechanism that promotes neuronal survival. In vitro, two convergent intracellular signaling pathways used by estrogen and IGF-1, the mitogen-activated protein kinase (MAPK/ERK), and phosphatidyl-inositol-3-kinase/Akt (PI3K/Akt), have been demonstrated to be neuroprotective. Continuous central infusions of MAPK/ERK and PI3K/Akt inhibitors were used to test the hypothesis that one or both of these signal transduction pathways mediates estrogen and/or IGF-1 neuroprotection of SNpc DA neurons after a unilateral administration of 6-OHDA into the MFB of rats. Motor behavior tests and tyrosine hydroxylase immunoreactivity revealed that the inhibitor of the PI3K/Akt pathway (LY294002) blocked the survival effects of both estrogen and IGF-1, while an inhibitor of the MAPK/ERK signaling (PD98059) was ineffective. Western blot analyses showed that estrogen and IGF-1 treatments increased PI3K/Akt activation in the SN; however, MAPK/ERK activation was decreased in the SN. Indeed, continuous infusions of inhibitors blocked phosphorylation of PI3K/Akt and MAPK/ERK. These findings indicate that estrogen and IGF-1-mediated SNpc DA neuronal protection is dependent on PI3K/Akt signaling, but not on the MAPK/ERK pathway.
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Affiliation(s)
- Arnulfo Quesada
- Department of Neurobiology, Brain Research Institute, David Geffen School of Medicine, UCLA, Los Angeles, California, USA.
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44
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RUBIN RAPHAEL, ARZUMANYAN ALLA, SOLIERA ANGELARACHELE, ROSS BRIAN, PERUZZI FRANCESCA, PRISCO MARCO. Insulin receptor substrate (IRS)-1 regulates murine embryonic stem (mES) cells self-renewal. J Cell Physiol 2008; 213:445-53. [PMID: 17620314 PMCID: PMC3760688 DOI: 10.1002/jcp.21185] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mouse embryonic stem (mES) cells are pluripotent cells that can be propagated in vitro with leukemia inhibitory factor (LIF) and serum. Intracellular signaling by LIF is principally mediated by activation of STAT-3, although additional pathways for self-renewal have been described. Here, we identified a novel role for Insulin receptor substrate-1 (IRS-1) as a critical factor in mES cells self-renewal and differentiation. IRS-1 is expressed and tyrosyl phosphorylated during mES cells self-renewal. Differentiation of mES cells, by LIF withdrawal, is associated with a marked reduction in IRS-1 expression. Targeting of IRS-1 by si-IRS-1 results in a severe reduction of Oct-4 protein expression and alkaline phosphatase activity, markers of undifferentiated mES cells. IRS-1 targeting does not interfere with LIF-induced STAT-3 phosphorylation, but negatively affects protein kinase B (PKB/AKT) and glycogen synthase kinase-3 (GSK-3beta) phosphorylation, which are downstream effectors of the LIF-mediated PI3K signaling cascade. Targeting of IRS-1 also results in a marked down regulation of Id-1 and Id-2 proteins expression, which are important components for self-renewal of ES cells. Conversely, over expression of IRS-1 inhibits mES cell differentiation. Taken together, these results suggest that expression and activity of IRS-1 are critical to the maintenance of the self-renewal program in mES cells.
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Affiliation(s)
- RAPHAEL RUBIN
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - ALLA ARZUMANYAN
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - ANGELA RACHELE SOLIERA
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Laboratorio di Oncogenesi Molecolare, Istituto Regina Elena, Roma, Italy
| | - BRIAN ROSS
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - FRANCESCA PERUZZI
- Department of Neuroscience and Center for Neurovirology, School of Medicine Temple University, Philadelphia, Pennsylvania
| | - MARCO PRISCO
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
- Correspondence to: Marco Prisco, Department of Cancer Biology, Thomas Jefferson University, 233 S 10th St, BLSB 630B, Philadelphia, PA 19107.
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45
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Sun H, Baserga R. The role of insulin receptor substrate-1 in transformation by v-src. J Cell Physiol 2008; 215:725-32. [PMID: 18064649 DOI: 10.1002/jcp.21352] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Hongzhi Sun
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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46
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Lin SJ, Chang C, Ng AK, Wang SH, Li JJ, Hu CP. Prevention of TGF-beta-induced apoptosis by interlukin-4 through Akt activation and p70S6K survival signaling pathways. Apoptosis 2007; 12:1659-70. [PMID: 17624592 DOI: 10.1007/s10495-007-0085-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, we demonstrate that interleukin-4 (IL-4) protects human hepatocellular carcinoma (HCC) cell line Hep3B from apoptosis induced by transforming growth factor-beta (TGF-beta). Further investigation of IL-4-transduced signaling pathways revealed that both insulin response substrate 1 and 2 (IRS-1/-2) and extracellular signal-regulated kinase (ERK) pathways were activated after IL-4 stimulation. The IRS-1/-2 activation was accompanied by the activation of phosphotidylinositol-3-kinase (PI3K), leading to Akt and p70 ribosomal protein S6 kinase (p70S6K). Interestingly, a protein kinase C (PKC) inhibitor, Gö6976, inhibited the phosphorylation of Akt, suggesting that the Akt activation was PKC-dependent. Using specific inhibitors for PI3K or ERK, we demonstrated that the PI3K pathway, but not the ERK pathway, was required for protection. The constitutively active form of PI3K almost completely rescued TGF-beta-induced apoptosis, further supporting the importance of the PI3K pathway in the protective effect of IL-4. Furthermore, a dominant negative Akt and/or Gö6976 only partially blocked the anti-apoptotic effect of IL-4. Similarly, rapamycin, which interrupted the activation of p70S6K, also only partially blocked the protective effect of IL-4. However, in the presence of both rapamycin and dominant negative Akt with or without Gö6976, IL-4 almost completely lost the anti-apoptotic effect, suggesting that both Akt and p70S6K pathways were required for the protective effect of IL-4 against TGF-beta-induced apoptosis.
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Affiliation(s)
- Sue-Jane Lin
- Institute of Microbiology & Immunology, National Yang-Ming University, Taipei, Taiwan, Republic of China
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47
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Liu M, Tu X, Ferrari-Amorotti G, Calabretta B, Baserga R. Downregulation of the upstream binding factor1 by glycogen synthase kinase3beta in myeloid cells induced to differentiate. J Cell Biochem 2007; 100:1154-69. [PMID: 17063482 DOI: 10.1002/jcb.21103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The upstream binding factor 1 (UBF1), one of the proteins that regulate the activity of RNA polymerase I, is downregulated in 32D myeloid cells induced to differentiate into granulocytes, either by the type 1 insulin-like growth factor (IGF-1) or the granulocytic colony stimulating factor (G-CSF). Downregulation of UBF1 is largely due to protein degradation, while mRNA levels are not affected. Inhibition of UBF1 degradation by lithium chloride (LiCl)and lactacystin suggest a role of glycogen synthase kinase beta (GSK3beta) in a proteasome-dependent degradation of UBF. GSK3beta phosphorylates in vitro and in vivo the UBF protein, which has five putative motifs for phosphorylation by GSK3beta. Elimination and/or mutations of these motifs stabilize the UBF1 protein even in cells induced to differentiate. Conversely, a stably transfected, constitutively active GSK3beta accelerates the downregulation of UBF1. We show further that activation of the differentiating protein C/EPBalpha in 32D cells transformed by the oncogenic BCR/ABL protein causes downregulation of UBF1. Finally, inhibition of differentiation of myeloid cells by a dominant negative mutant of Stat3 stabilizes the UBF1 protein, while rapamycin-induced differentiation of myeloid cells downregulates UBF1 levels. Taken together, our results indicate that the induction of granulocytic differentiation in 32D murine myeloid cells causes the degradation of UBF1, via GSK3beta and the proteasome pathway.
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Affiliation(s)
- Mingli Liu
- Kimmel Cancer Center, Thomas Jefferson University, 624 Bluemle, Life Sciences Building, Philadelphia, Pennsylvania 19107, USA
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48
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Niu XL, Li J, Hakim ZS, Rojas M, Runge MS, Madamanchi NR. Leukocyte antigen-related deficiency enhances insulin-like growth factor-1 signaling in vascular smooth muscle cells and promotes neointima formation in response to vascular injury. J Biol Chem 2007; 282:19808-19. [PMID: 17500057 DOI: 10.1074/jbc.m610452200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Increase in the expression of leukocyte antigen-related (LAR) protein causes insulin resistance, an important contributor to atherosclerosis. However, the function of LAR in atherosclerosis is not known. To address whether LAR is important in the response of vascular cells to atherogenic stimuli, we investigated cell proliferation, migration, and insulin-like growth factor-1 receptor (IGF-1R) signaling in wild-type and LAR(-/-) mouse vascular smooth muscle cells (VSMC) treated with IGF-1. Absence of LAR significantly enhanced proliferation and migration of VSMC compared with wild-type cells after IGF-1 treatment. U0126 and LY249002, specific inhibitors of MAPK/ERK kinase (MEK) and phosphoinositide 3-kinase, respectively, inhibited IGF-1-induced DNA synthesis and migration in both wild-type and LAR(-/-) VSMC. IGF-1 markedly enhanced IGF-1R phosphorylation in both wild-type and LAR(-/-) VSMC, but the phosphorylation was 90% higher in knock-out cells compared with wild-type cells. Absence of LAR enhanced phosphorylation of insulin receptor substrate-1 and insulin receptor substrate-1-associated phosphoinositide 3-kinase activity in VSMC treated with IGF-1. IGF-1-induced phosphorylation of ERK1/2 also increased significantly in LAR(-/-) VSMC compared with wild-type cells. Furthermore, LAR directly binds to IGF-1R in glutathione S-transferase-LAR pull-down and IGF-1R immunoprecipitation experiments and recombinant LAR dephosphorylates IGF-1R in vitro. Neointima formation in response to arterial injury and IGF-1R phosphorylation in neointima increased significantly in LAR(-/-) mice compared with wild-type mice. A significant decrease in body weight, fasting insulin, and IGF-1 levels were observed in LAR(-/-) mice compared with wild-type mice. Together, these data indicate that LAR regulates IGF-1R signaling in VSMC and dysregulation of this phosphatase may lead to VSMC hyperplasia.
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MESH Headings
- Animals
- Arteries/injuries
- Arteries/metabolism
- Arteries/pathology
- Atherosclerosis/genetics
- Atherosclerosis/metabolism
- Atherosclerosis/pathology
- Butadienes/pharmacology
- Cell Movement/drug effects
- Cell Proliferation/drug effects
- Cells, Cultured
- Enzyme Inhibitors/pharmacology
- Humans
- Hyperplasia/genetics
- Hyperplasia/metabolism
- Hyperplasia/pathology
- Insulin Resistance/genetics
- Insulin-Like Growth Factor I/metabolism
- Insulin-Like Growth Factor I/pharmacology
- MAP Kinase Kinase Kinases/antagonists & inhibitors
- MAP Kinase Kinase Kinases/metabolism
- MAP Kinase Signaling System/drug effects
- MAP Kinase Signaling System/genetics
- Male
- Mice
- Mice, Knockout
- Nitriles/pharmacology
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphoinositide-3 Kinase Inhibitors
- Phosphorylation/drug effects
- Protein Binding/drug effects
- Protein Binding/genetics
- Protein Processing, Post-Translational/drug effects
- Protein Processing, Post-Translational/genetics
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Protein Tyrosine Phosphatases/deficiency
- Protein Tyrosine Phosphatases/metabolism
- Receptor, IGF Type 1/genetics
- Receptor, IGF Type 1/metabolism
- Receptor-Like Protein Tyrosine Phosphatases, Class 4
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/metabolism
- Tunica Media/metabolism
- Tunica Media/pathology
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Affiliation(s)
- Xi-Lin Niu
- Department of Medicine, Carolina Cardiovascular Biology Center, University of North Carolina, Chapel Hill, North Carolina 27599-7126, USA
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Samani AA, Yakar S, LeRoith D, Brodt P. The role of the IGF system in cancer growth and metastasis: overview and recent insights. Endocr Rev 2007; 28:20-47. [PMID: 16931767 DOI: 10.1210/er.2006-0001] [Citation(s) in RCA: 730] [Impact Index Per Article: 42.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
IGF-I receptor (IGF-IR) signaling and functions are mediated through the activities of a complex molecular network of positive (e.g., type I IGF) and negative (e.g., the type II IGF receptor, IGF-IIR) effectors. Under normal physiological conditions, the balance between the expression and activities of these molecules is tightly controlled. Changes in this delicate balance (e.g., overexpression of one effector) may trigger a cascade of molecular events that can ultimately lead to malignancy. In recent years, evidence has been mounting that the IGF axis may be involved in human cancer progression and can be targeted for therapeutic intervention. Here we review old and more recent evidence on the role the IGF system in malignancy and highlight experimental and clinical studies that provide novel insights into the complex mechanisms that contribute to its oncogenic potential. Controversies arising from conflicting evidence on the relevance of IGF-IR and its ligands to human cancer are discussed. Our review highlights the importance of viewing the IGF axis as a complex multifactorial system and shows that changes in the expression levels of any one component of the axis, in a given malignancy, should be interpreted with caution and viewed in a wider context that takes into account the expression levels, state of activation, accessibility, and functionality of other interacting components. Because IGF targeting for anticancer therapy is rapidly becoming a clinical reality, an understanding of this complexity is timely because it is likely to have an impact on the design, mode of action, and clinical outcomes of newly developed drugs.
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Affiliation(s)
- Amir Abbas Samani
- Department of Medicine, McGill University Health Center, Royal Victoria Hospital, Room H6.25687, Pine Avenue West, Montreal, Québec, Canada H3A 1A1
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50
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Ma Z, Gibson SL, Byrne MA, Zhang J, White MF, Shaw LM. Suppression of insulin receptor substrate 1 (IRS-1) promotes mammary tumor metastasis. Mol Cell Biol 2006; 26:9338-51. [PMID: 17030605 PMCID: PMC1698550 DOI: 10.1128/mcb.01032-06] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The insulin receptor substrate (IRS) proteins are cytoplasmic adaptors that organize signaling complexes downstream of activated cell surface receptors. Here, we show that IRS-1 and IRS-2, despite significant homology, play critical yet distinct functions in breast cancer, and we identify specific signaling pathways that are influenced by IRS-1 using the polyoma virus middle-T (PyV-MT) transgenic mouse model of mammary carcinoma and Irs-1 null (Irs1(-/-)) mice. The absence of Irs-1 expression enhanced metastatic spread significantly without a significant effect on primary tumor growth. Orthotopic transplant studies revealed that the increased metastatic potential of Irs1-deficient tumor cells is cell autonomous. Mammary tumors that developed in PyV-MT::Irs1(-/-) mice exhibited elevated Irs-2 function and enhanced phosphatidylinositol 3-kinase/Akt/mTor activity, suggesting that one mechanism by which Irs-1 impedes metastasis is to suppress Irs-2-dependent signaling. In support of this mechanism, reduction of Irs-2 expression in Irs1(-/-) tumor cells restored mTor signaling to wild-type levels. PyV-MT::Irs1(-/-) tumors also exhibited a significant increase in vascular endothelial growth factor expression and microvessel density, which could facilitate their dissemination. The significance of our findings for human breast cancer is heightened by our observation that Irs-1 is inactivated in wild-type, metastatic mammary tumors by serine phosphorylation. Collectively, our findings reveal that inactivation of IRS-1 enhances breast cancer metastasis and support the novel hypothesis that IRS-1 has metastasis suppressor functions for breast cancer.
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Affiliation(s)
- Zhefu Ma
- Department of Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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