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Qi W, Gundogan F, Gilligan J, Monte SDL. Dietary Soy Prevents Fetal Demise, Intrauterine Growth Restriction, Craniofacial Dysmorphic Features, and Impairments in Placentation Linked to Gestational Alcohol Exposure: Pivotal Role of Insulin and Insulin-Like Growth Factor Signaling Networks. Alcohol 2023:S0741-8329(23)00026-5. [PMID: 36898643 DOI: 10.1016/j.alcohol.2023.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 03/11/2023]
Abstract
INTRODUCTION Prenatal alcohol exposure can impair placentation and cause intrauterine growth restriction (IUGR), fetal demise, and fetal alcohol spectrum disorder (FASD). Previous studies showed that ethanol's inhibition of placental insulin and insulin-like growth factor, type 1 (IGF-1) signaling compromises trophoblastic cell motility and maternal vascular transformation at the implantation site. Since soy isolate supports insulin responsiveness, we hypothesized that dietary soy could be used to normalize placentation and fetal growth in an experimental model of FASD METHODS: Pregnant Long Evans rat dams were fed with isocaloric liquid diets containing 0% or 8.2% ethanol (v/v) from gestation day (GD) 6. Dietary protein sources were either 100% soy isolate or 100% casein (standard). Gestational sacs were harvested on GD19 to evaluate fetal resorption, fetal growth parameters, and placental morphology. Placental insulin/IGF-1 signaling through Akt pathways was assessed using commercial bead-based multiplex enzyme-linked immunosorbent assays RESULTS: Dietary soy markedly reduced or prevented the ethanol-associated fetal loss, IUGR, FASD dysmorphic features, and impairments in placentation/maturation. Furthermore, ethanol's inhibitory effects on the placental glycogen cell population at the junctional zone, invasive trophoblast populations at the implantation site, maternal vascular transformation, and signaling through the insulin and IGF1 receptors, Akt and PRAS40 were largely abrogated by co-administration of soy. CONCLUSION Dietary soy may provide an economically feasible and accessible means of reducing adverse pregnancy outcomes linked to gestational ethanol exposure.
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Affiliation(s)
- Wei Qi
- Liver Research Center of the Department of Medicine at Rhode Island Hospital, Providence, Rhode Island, 02905
| | - Fusun Gundogan
- Alpert Medical School at Brown University, Providence, Rhode Island, 02905; Women & Infants Hospital, Providence, Rhode Island, 02905
| | - Jeffrey Gilligan
- Liver Research Center of the Department of Medicine at Rhode Island Hospital, Providence, Rhode Island, 02905
| | - Suzanne de la Monte
- Liver Research Center of the Department of Medicine at Rhode Island Hospital, Providence, Rhode Island, 02905; and Departments of Pathology and Laboratory Medicine at Rhode Island Hospital, Providence, Rhode Island, 02905; Alpert Medical School at Brown University, Providence, Rhode Island, 02905; Women & Infants Hospital, Providence, Rhode Island, 02905.
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Wang P, Yan Z, Zhou PK, Gu Y. The Promising Therapeutic Approaches for Radiation-Induced Pulmonary Fibrosis: Targeting Radiation-Induced Mesenchymal Transition of Alveolar Type II Epithelial Cells. Int J Mol Sci 2022; 23:ijms232315014. [PMID: 36499337 PMCID: PMC9737257 DOI: 10.3390/ijms232315014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/16/2022] [Accepted: 11/26/2022] [Indexed: 12/03/2022] Open
Abstract
Radiation-induced pulmonary fibrosis (RIPF) is a common consequence of radiation for thoracic tumors, and is accompanied by gradual and irreversible organ failure. This severely reduces the survival rate of cancer patients, due to the serious side effects and lack of clinically effective drugs and methods. Radiation-induced pulmonary fibrosis is a dynamic process involving many complicated and varied mechanisms, of which alveolar type II epithelial (AT2) cells are one of the primary target cells, and the epithelial-mesenchymal transition (EMT) of AT2 cells is very relevant in the clinical search for effective targets. Therefore, this review summarizes several important signaling pathways that can induce EMT in AT2 cells, and searches for molecular targets with potential effects on RIPF among them, in order to provide effective therapeutic tools for the clinical prevention and treatment of RIPF.
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Malaguarnera R, Gabriele C, Santamaria G, Giuliano M, Vella V, Massimino M, Vigneri P, Cuda G, Gaspari M, Belfiore A. Comparative proteomic analysis of insulin receptor isoform A and B signaling. Mol Cell Endocrinol 2022; 557:111739. [PMID: 35940390 DOI: 10.1016/j.mce.2022.111739] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 07/17/2022] [Accepted: 07/28/2022] [Indexed: 11/30/2022]
Abstract
The insulin receptor (IR) gene undergoes differential splicing generating two IR isoforms, IR-A and IR-B. The roles of IR-A in cancer and of IR-B in metabolic regulation are well known but the molecular mechanisms responsible for their different biological effects are poorly understood. We aimed to identify different or similar protein substrates and signaling linked to each IR isoforms. We employed mouse fibroblasts lacking IGF1R gene and expressing exclusively either IR-A or IR-B. By proteomic analysis a total of 2530 proteins were identified and quantified. Proteins and pathways mostly associated with insulin-activated IR-A were involved in cancer, stemness and interferon signaling. Instead, proteins and pathways associated with insulin-stimulated IR-B-expressing cells were mostly involved in metabolic or tumor suppressive functions. These results show that IR-A and IR-B recruit partially different multiprotein complexes in response to insulin, suggesting partially different functions of IR isoforms in physiology and in disease.
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Affiliation(s)
| | - Caterina Gabriele
- Research Centre for Advanced Biochemistry and Molecular Biology, Department of Experimental and Clinical Medicine, "Magna Græcia" University of Catanzaro, 88100, Catanzaro, Italy.
| | - Gianluca Santamaria
- Research Centre for Advanced Biochemistry and Molecular Biology, Department of Experimental and Clinical Medicine, "Magna Græcia" University of Catanzaro, 88100, Catanzaro, Italy; Klinikum rechts der Isar, Department of Medicine and Molecular Cardiology, Technical University of Munich, Germany.
| | - Marika Giuliano
- Unit of Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122, Catania, Italy.
| | - Veronica Vella
- Unit of Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122, Catania, Italy.
| | - Michele Massimino
- Department of Clinical and Experimental Medicine, Oncology Unit, University of Catania, 95100, Catania, Italy.
| | - Paolo Vigneri
- Department of Clinical and Experimental Medicine, Oncology Unit, University of Catania, 95100, Catania, Italy.
| | - Giovanni Cuda
- Research Centre for Advanced Biochemistry and Molecular Biology, Department of Experimental and Clinical Medicine, "Magna Græcia" University of Catanzaro, 88100, Catanzaro, Italy.
| | - Marco Gaspari
- Research Centre for Advanced Biochemistry and Molecular Biology, Department of Experimental and Clinical Medicine, "Magna Græcia" University of Catanzaro, 88100, Catanzaro, Italy.
| | - Antonino Belfiore
- Unit of Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122, Catania, Italy.
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Chekmarev J, Azad MG, Richardson DR. The Oncogenic Signaling Disruptor, NDRG1: Molecular and Cellular Mechanisms of Activity. Cells 2021; 10:cells10092382. [PMID: 34572031 PMCID: PMC8465210 DOI: 10.3390/cells10092382] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 09/03/2021] [Accepted: 09/06/2021] [Indexed: 12/12/2022] Open
Abstract
NDRG1 is an oncogenic signaling disruptor that plays a key role in multiple cancers, including aggressive pancreatic tumors. Recent studies have indicated a role for NDRG1 in the inhibition of multiple tyrosine kinases, including EGFR, c-Met, HER2 and HER3, etc. The mechanism of activity of NDRG1 remains unclear, but to impart some of its functions, NDRG1 binds directly to key effector molecules that play roles in tumor suppression, e.g., MIG6. More recent studies indicate that NDRG1s-inducing drugs, such as novel di-2-pyridylketone thiosemicarbazones, not only inhibit tumor growth and metastasis but also fibrous desmoplasia, which leads to chemotherapeutic resistance. The Casitas B-lineage lymphoma (c-Cbl) protein may be regulated by NDRG1, and is a crucial E3 ligase that regulates various protein tyrosine and receptor tyrosine kinases, primarily via ubiquitination. The c-Cbl protein can act as a tumor suppressor by promoting the degradation of receptor tyrosine kinases. In contrast, c-Cbl can also promote tumor development by acting as a docking protein to mediate the oncogenic c-Met/Crk/JNK and PI3K/AKT pathways. This review hypothesizes that NDRG1 could inhibit the oncogenic function of c-Cbl, which may be another mechanism of its tumor-suppressive effects.
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Affiliation(s)
- Jason Chekmarev
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane, QLD 4111, Australia; (J.C.); (M.G.A.)
| | - Mahan Gholam Azad
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane, QLD 4111, Australia; (J.C.); (M.G.A.)
| | - Des R. Richardson
- Centre for Cancer Cell Biology and Drug Discovery, Griffith Institute for Drug Discovery, Griffith University, Nathan, Brisbane, QLD 4111, Australia; (J.C.); (M.G.A.)
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: ; Tel.: +61-7-3735-7549
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Cheng Q, Li YW, Yang CF, Zhong YJ, Li L. Ethanol-Induced Hepatic Insulin Resistance is Ameliorated by Methyl Ferulic Acid Through the PI3K/AKT Signaling Pathway. Front Pharmacol 2019; 10:949. [PMID: 31555134 PMCID: PMC6726842 DOI: 10.3389/fphar.2019.00949] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 07/25/2019] [Indexed: 12/13/2022] Open
Abstract
One of the key events during the development of alcoholic liver disease (ALD) is that alcohol inhibits the insulin signaling pathway in liver and leads to disorders of glucose and lipid metabolism. Methyl ferulic acid (MFA) is a biologically active monomer isolated from the root of Securidaca inappendiculata Hasskarl. It has been reported that MFA has a hepatoprotective effect against alcohol-induced liver injury in vivo and in vitro. However, the effect of MFA on ethanol-induced insulin resistance in ALD remains unclear. In this study, we investigated whether MFA could exert protective effects against hepatic insulin resistance in ethanol-induced L-02 cells and ALD rats. ALD was induced in vivo by feeding Lieber-DeCarli diet containing 5% (w/v) alcohol for 16 weeks to Sprague-Dawley rats. Insulin resistance was induced in vitro in human hepatocyte L-02 cells with 200 mM ethanol for 24 h followed by 10-7 nM insulin for 30 min. MFA exhibited the effects of inhibited insulin resistance, reduced enzymatic capacity for hepatic gluconeogenesis, and increased hepatic glycogen synthesis both in vivo and in vitro. In addition, the results of transcriptome sequencing of liver tissues in the ethanol- and MFA-treated groups indicated that "pyruvate metabolism," "glycolysis/gluconeogenesis," and "fatty acid metabolism" were significantly different between ethanol- and MFA-treated groups. Further studies suggested that MFA activated the hepatic phosphatidylinositol 3-kinase (PI3K)/AKT pathway in vivo and in vitro. Taken together, these findings suggested that MFA effectively ameliorated hepatic insulin resistance in ALD at least partially by acting on the PI3K/AKT pathway.
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Affiliation(s)
- Qi Cheng
- College of Pharmacy, Guilin Medical University, Guilin, China
| | - Yong Wen Li
- College of Pharmacy, Guilin Medical University, Guilin, China
| | - Cheng Fang Yang
- College of Pharmacy, Guilin Medical University, Guilin, China
| | - Yu Juan Zhong
- College of Pharmacy, Guilin Medical University, Guilin, China
| | - Li Li
- College of Pharmacy, Guilin Medical University, Guilin, China
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Ito Y, Hart JR, Vogt PK. Isoform-specific activities of the regulatory subunits of phosphatidylinositol 3-kinases - potentially novel therapeutic targets. Expert Opin Ther Targets 2018; 22:869-877. [PMID: 30205700 DOI: 10.1080/14728222.2018.1522302] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION The main regulatory subunits of Class IA phosphatidylinositol 3-kinase (PI3K), p85α and p85β, initiate diverse cellular activities independent of binding to the catalytic subunit p110. Several of these signaling processes directly or indirectly contribute to a regulation of PI3K and could become targets for therapeutic efforts. Areas covered: This review will highlight two general areas of p85 activity: (1) direct interaction with regulatory proteins and with determinants of the cytoskeleton, and (2) a genetic analysis by deletion and domain switches identifying new functions for p85 domains. Expert Opinion: Isoform-specific activities of regulatory subunits have long been at the periphery of the PI3K field. Our understanding of these unique functions of the regulatory subunits is fragmentary and raises many important questions. At this time, there is insufficient information to translate this knowledge into the clinic, but some tempting targets have emerged that could move the field forward with the help of novel technologies in drug design and identification.
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Affiliation(s)
- Yoshihiro Ito
- a Department of Molecular Medicine , The Scripps Research Institute , La Jolla , CA , USA
| | - Jonathan R Hart
- a Department of Molecular Medicine , The Scripps Research Institute , La Jolla , CA , USA
| | - Peter K Vogt
- a Department of Molecular Medicine , The Scripps Research Institute , La Jolla , CA , USA
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Pulido R. PTEN Inhibition in Human Disease Therapy. Molecules 2018; 23:molecules23020285. [PMID: 29385737 PMCID: PMC6017825 DOI: 10.3390/molecules23020285] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 01/26/2018] [Accepted: 01/28/2018] [Indexed: 12/19/2022] Open
Abstract
The tumor suppressor PTEN is a major homeostatic regulator, by virtue of its lipid phosphatase activity against phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], which downregulates the PI3K/AKT/mTOR prosurvival signaling, as well as by its protein phosphatase activity towards specific protein targets. PTEN catalytic activity is crucial to control cell growth under physiologic and pathologic situations, and it impacts not only in preventing tumor cell survival and proliferation, but also in restraining several cellular regeneration processes, such as those associated with nerve injury recovery, cardiac ischemia, or wound healing. In these conditions, inhibition of PTEN catalysis is being explored as a potentially beneficial therapeutic intervention. Here, an overview of human diseases and conditions in which PTEN inhibition could be beneficial is presented, together with an update on the current status of specific small molecule inhibitors of PTEN enzymatic activity, their use in experimental models, and their limitations as research or therapeutic drugs.
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Affiliation(s)
- Rafael Pulido
- Biomarkers in Cancer Unit, Biocruces Health Research Institute, 48903 Barakaldo, Spain.
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
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The metastatic suppressor NDRG1 inhibits EMT, migration and invasion through interaction and promotion of caveolin-1 ubiquitylation in human colorectal cancer cells. Oncogene 2017; 36:4323-4335. [PMID: 28346422 PMCID: PMC5537633 DOI: 10.1038/onc.2017.74] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 01/15/2017] [Accepted: 02/14/2017] [Indexed: 02/07/2023]
Abstract
N-myc downstream-regulated gene 1 (NDRG1) has been reported to act as a key regulatory molecule in tumor progression-related signaling pathways, especially in tumor metastasis. However, the related mechanism has not been fully discovered yet. Herein we demonstrated that the novel molecule of cell migration and invasion, caveolin-1, has direct interaction with NDRG1 in human colorectal cancer (CRC) cells. Moreover, we discovered that NDRG1 reduces caveolin-1 protein expression through promoting its ubiquitylation and subsequent degradation via the proteasome in CRC cells. In addition, caveolin-1 mediates the suppressive function of NDRG1 in epithelial–mesenchymal transition, migration and invasion in vitro and metastasis in vivo. These results help to fulfill the potential mechanisms of NDRG1 in anti-metastatic treatment for human colorectal cancer.
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Pulido R. PTEN: a yin-yang master regulator protein in health and disease. Methods 2016; 77-78:3-10. [PMID: 25843297 DOI: 10.1016/j.ymeth.2015.02.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 02/19/2015] [Indexed: 01/16/2023] Open
Abstract
The PTEN gene is a tumor suppressor gene frequently mutated in human tumors, which encodes a ubiquitous protein whose major activity is to act as a lipid phosphatase that counteracts the action of the oncogenic PI3K. In addition, PTEN displays protein phosphatase- and catalytically-independent activities. The physiologic control of PTEN function, and its inactivation in cancer and other human diseases, including some neurodevelopmental disorders, is upon the action of multiple regulatory mechanisms. This provides a wide spectrum of potential therapeutic approaches to reconstitute PTEN activity. By contrast, inhibition of PTEN function may be beneficial in a different group of human diseases, such as type 2 diabetes or neuroregeneration-related pathologies. This makes PTEN a functionally dual yin-yang protein with high potential in the clinics. Here, a brief overview on PTEN and its relation with human disease is presented.
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Affiliation(s)
- Rafael Pulido
- BioCruces Health Research Institute, Barakaldo, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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10
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He M, Zheng B, Zhang Y, Zhang XH, Wang C, Yang Z, Sun Y, Wu XL, Wen JK. KLF4 mediates the link between TGF-β1-induced gene transcription and H3 acetylation in vascular smooth muscle cells. FASEB J 2015; 29:4059-70. [PMID: 26082460 DOI: 10.1096/fj.15-272658] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/02/2015] [Indexed: 11/11/2022]
Abstract
Transcriptional activation by transcription factors is coupled with histone acetylation and chromatin remodeling. However, the relationship between TGF-β1-induced gene transcription by Krüppel-like factor (KLF)-4 and histone acetylation remains unknown. In our study, KLF4 overexpression or knockdown, respectively increased or decreased H3 acetylation and p300 occupancy, which is concentrated in the region containing TGF-β1 control elements (TCEs) of the genes by TGF-β1 regulation during vascular smooth muscle cell (VSMC) differentiation. Coimmunoprecipitation and glutathione S-transferase pull-down assays showed that phosphatase and tensin homolog (PTEN) formed a complex with KLF4 to inhibit the phosphorylation of the latter in basal conditions. After TGF-β1 signaling activation, PTEN was phosphorylated by p38 MAPK or PI3K/Akt signaling, phosphorylated PTEN lost its ability to dephosphorylate KLF4, and the cofactors interacting with KLF4 switched from PTEN to p300. Then, KLF4-p300 complexes were recruited to KLF4-binding sites of the gene promoter of VSMCs, to acetylate histone H3 and activate transcription. In addition, phosphorylated KLF4 enhanced p300 histone acetyltransferase (HAT) activity via the p38 MAPK pathway, which may be responsible for H3 acetylation. Taken together, the results of our study reveal a novel mechanism whereby KLF4 mediates the link between TGF-β1-induced gene transcription activation and H3 acetylation during VSMC differentiation.
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Affiliation(s)
- Ming He
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Bin Zheng
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Yu Zhang
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Xin-Hua Zhang
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Chang Wang
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Zhan Yang
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Yan Sun
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Xiao-Li Wu
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Jin-Kun Wen
- *Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, China Administration of Education, Hebei Medical University, Shijiazhuang, China; and Institute of Chinese Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
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Oncogenic activity of the regulatory subunit p85β of phosphatidylinositol 3-kinase (PI3K). Proc Natl Acad Sci U S A 2014; 111:16826-9. [PMID: 25385636 DOI: 10.1073/pnas.1420281111] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Expression of the regulatory subunit p85β of PI3K induces oncogenic transformation of primary avian fibroblasts. The transformed cells proliferate at an increased rate compared with nontransformed controls and show elevated levels of PI3K signaling. The oncogenic activity of p85β requires an active PI3K-TOR signaling cascade and is mediated by the p110α and p110β isoforms of the PI3K catalytic subunit. The data suggest that p85β is a less effective inhibitor of the PI3K catalytic subunit than p85α and that this reduced level of p110 inhibition accounts for the oncogenic activity of p85β.
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Saldanha SN, Tollefsbol TO. Pathway modulations and epigenetic alterations in ovarian tumorbiogenesis. J Cell Physiol 2014; 229:393-406. [PMID: 24105793 DOI: 10.1002/jcp.24466] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 09/06/2013] [Indexed: 12/23/2022]
Abstract
Cellular pathways are numerous and are highly integrated in function in the control of cellular systems. They collectively regulate cell division, proliferation, survival and apoptosis of cells and mutagenesis of key genes that control these pathways can initiate neoplastic transformations. Understanding these pathways is crucial to future therapeutic and preventive strategies of the disease. Ovarian cancers are of three major types; epithelial, germ-cell, and stromal. However, ovarian cancers of epithelial origin, arising from the mesothelium, are the predominant form. Of the subtypes of ovarian cancer, the high-grade serous tumors are fatal, with low survival rate due to late detection and poor response to treatments. Close examination of preserved ovarian tissues and in vitro studies have provided insights into the mechanistic changes occurring in cells mediated by a few key genes. This review will focus on pathways and key genes of the pathways that are mutated or have aberrant functions in the pathology of ovarian cancer. Non-genetic mechanisms that are gaining prominence in the pathology of ovarian cancer, miRNAs and epigenetics, will also be discussed in the review.
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Affiliation(s)
- Sabita N Saldanha
- Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama; Department of Biological Sciences, Alabama State University, Montgomery, Alabama
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Fang BA, Kovačević Ž, Park KC, Kalinowski DS, Jansson PJ, Lane DJR, Sahni S, Richardson DR. Molecular functions of the iron-regulated metastasis suppressor, NDRG1, and its potential as a molecular target for cancer therapy. Biochim Biophys Acta Rev Cancer 2013; 1845:1-19. [PMID: 24269900 DOI: 10.1016/j.bbcan.2013.11.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/11/2013] [Accepted: 11/13/2013] [Indexed: 12/11/2022]
Abstract
N-myc down-regulated gene 1 (NDRG1) is a known metastasis suppressor in multiple cancers, being also involved in embryogenesis and development, cell growth and differentiation, lipid biosynthesis and myelination, stress responses and immunity. In addition to its primary role as a metastasis suppressor, NDRG1 can also influence other stages of carcinogenesis, namely angiogenesis and primary tumour growth. NDRG1 is regulated by multiple effectors in normal and neoplastic cells, including N-myc, histone acetylation, hypoxia, cellular iron levels and intracellular calcium. Further, studies have found that NDRG1 is up-regulated in neoplastic cells after treatment with novel iron chelators, which are a promising therapy for effective cancer management. Although the pathways by which NDRG1 exerts its functions in cancers have been documented, the relationship between the molecular structure of this protein and its functions remains unclear. In fact, recent studies suggest that, in certain cancers, NDRG1 is post-translationally modified, possibly by the activity of endogenous trypsins, leading to a subsequent alteration in its metastasis suppressor activity. This review describes the role of this important metastasis suppressor and discusses interesting unresolved issues regarding this protein.
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Affiliation(s)
- Bernard A Fang
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Blackburn Building (D06), The University of Sydney, Sydney, NSW 2006, Australia
| | - Žaklina Kovačević
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Blackburn Building (D06), The University of Sydney, Sydney, NSW 2006, Australia
| | - Kyung Chan Park
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Blackburn Building (D06), The University of Sydney, Sydney, NSW 2006, Australia
| | - Danuta S Kalinowski
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Blackburn Building (D06), The University of Sydney, Sydney, NSW 2006, Australia
| | - Patric J Jansson
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Blackburn Building (D06), The University of Sydney, Sydney, NSW 2006, Australia
| | - Darius J R Lane
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Blackburn Building (D06), The University of Sydney, Sydney, NSW 2006, Australia
| | - Sumit Sahni
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Blackburn Building (D06), The University of Sydney, Sydney, NSW 2006, Australia
| | - Des R Richardson
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Blackburn Building (D06), The University of Sydney, Sydney, NSW 2006, Australia.
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Gao Y, Su P, Wang C, Zhu K, Chen X, Liu S, He J. The role of PTEN in chronic growth hormone-induced hepatic insulin resistance. PLoS One 2013; 8:e68105. [PMID: 23840818 PMCID: PMC3695944 DOI: 10.1371/journal.pone.0068105] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 05/24/2013] [Indexed: 11/25/2022] Open
Abstract
Chronic growth hormone (GH) therapy has been shown to cause insulin resistance, but the mechanism remains unknown. PTEN, a tumor suppressor gene, is a major negative regulator of insulin signaling. In this study, we explored the effect of chronic GH on insulin signaling in the context of PTEN function. Balb/c healthy mice were given recombinant human or bovine GH intraperitoneally for 3 weeks. We found that phosphorylation of Akt was significantly decreased in chronic GH group and the expression of PTEN was significantly increased. We further examined this effect in the streptozotocin-induced Type I diabetic mouse model, in which endogenous insulin secretion was disrupted. Insulin/PI3K/Akt signaling was impaired. However, different from the observation in healthy mice, the expression of PTEN did not increase. Similarly, PTEN expression did not significantly increase in chronic GH-treated mice with hypoinsulinemia induced by prolonged fasting. We conducted in-vitro experiments in HepG2 cells to validate our in-vivo findings. Long-term exposure to GH caused similar resistance of insulin/PI3K/Akt signaling in HepG2 cells; and over-expression of PTEN enhanced the impairment of insulin signaling. On the other hand, disabling the PTEN gene by transfecting the mutant PTEN construct C124S or siPTEN, disrupted the chronic GH induced insulin resistance. Our data demonstrate that PTEN plays an important role in chronic-GH-induced insulin resistance. These findings may have implication in other pathological insulin resistance.
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MESH Headings
- Animals
- Cattle
- Cell Line, Tumor
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/physiopathology
- Disease Models, Animal
- Fasting/metabolism
- Growth Hormone/metabolism
- Hep G2 Cells
- Humans
- Insulin/metabolism
- Insulin Resistance/physiology
- Liver/metabolism
- Liver/physiology
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- PTEN Phosphohydrolase/metabolism
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphorylation/physiology
- Proto-Oncogene Proteins c-akt/metabolism
- Signal Transduction/physiology
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Affiliation(s)
- Yuan Gao
- Department of Gastroenterology, Guangdong Provincial Key Laboratory of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Peizhu Su
- Department of Gastroenterology, Guangdong Provincial Key Laboratory of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Chuqiong Wang
- Department of Gastroenterology, Guangdong Provincial Key Laboratory of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Kongqin Zhu
- Department of Gastroenterology, Guangdong Provincial Key Laboratory of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xiaolan Chen
- Department of Gastroenterology, Guangdong Provincial Key Laboratory of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Side Liu
- Department of Gastroenterology, Guangdong Provincial Key Laboratory of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- * E-mail: (JH); (SL)
| | - Jiman He
- Department of Gastroenterology, Guangdong Provincial Key Laboratory of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Liver Research Center, Brown University, Providence, Rhode Island, United States of America
- * E-mail: (JH); (SL)
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15
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Horita H, Furgeson SB, Ostriker A, Olszewski KA, Sullivan T, Villegas LR, Levine M, Parr JE, Cool CD, Nemenoff RA, Weiser-Evans MCM. Selective inactivation of PTEN in smooth muscle cells synergizes with hypoxia to induce severe pulmonary hypertension. J Am Heart Assoc 2013; 2:e000188. [PMID: 23727701 PMCID: PMC3698782 DOI: 10.1161/jaha.113.000188] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Background Pulmonary vascular remodeling in pulmonary hypertension (PH) is characterized by increased vascular smooth muscle cell (SMC) and adventitial fibroblast proliferation, small vessel occlusion, and inflammatory cell accumulation. The underlying molecular mechanisms driving progression remain poorly defined. We have focused on loss of the phosphatase PTEN in SMCs as a major driver of pathological vascular remodeling. Our goal was to define the role of PTEN in human PH and in hypoxia‐induced PH using a mouse model with inducible deletion of PTEN in SMCs. Methods and Results Staining of human biopsies demonstrated enhanced inactive PTEN selectively in the media from hypertensive patients compared to controls. Mice with induced deletion of PTEN in SMCs were exposed to normoxia or hypoxia for up to 4 weeks. Under normoxia, SMC PTEN depletion was sufficient to induce features of PH similar to those observed in wild‐type mice exposed to chronic hypoxia. Under hypoxia, PTEN depletion promoted an irreversible progression of PH characterized by increased pressure, extensive pulmonary vascular remodeling, formation of complex vascular lesions, and increased macrophage accumulation associated with synergistic increases in proinflammatory cytokines and proliferation of both SMCs and nonSMCs. Conclusions Chronic inactivation of PTEN selectively in SMC represents a critical mediator of PH progression, leading to cell autonomous events and increased production of factors correlated to proliferation and recruitment of adventitial and inflammatory cells, resulting in irreversible progression of the disease.
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Affiliation(s)
- Henrick Horita
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA
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16
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Sun J, Zhang D, Bae DH, Sahni S, Jansson P, Zheng Y, Zhao Q, Yue F, Zheng M, Kovacevic Z, Richardson DR. Metastasis suppressor, NDRG1, mediates its activity through signaling pathways and molecular motors. Carcinogenesis 2013; 34:1943-54. [PMID: 23671130 DOI: 10.1093/carcin/bgt163] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The metastasis suppressor, N-myc downstream regulated gene 1 (NDRG1), is negatively correlated with tumor progression in multiple neoplasms, being a promising new target for cancer treatment. However, the precise molecular effects of NDRG1 remain unclear. Herein, we summarize recent advances in understanding the impact of NDRG1 on cancer metastasis with emphasis on its interactions with the key oncogenic nuclear factor-kappaB, phosphatidylinositol-3 kinase/phosphorylated AKT/mammalian target of rapamycin and Ras/Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling pathways. Recent studies demonstrating the inhibitory effects of NDRG1 on the epithelial-mesenchymal transition, a key initial step in metastasis, TGF-β pathway and the Wnt/β-catenin pathway are also described. Furthermore, NDRG1 was also demonstrated to regulate molecular motors in cancer cells, leading to inhibition of F-actin polymerization, stress fiber formation and subsequent reduction of cancer cell migration. Collectively, this review summarizes the underlying molecular mechanisms of the antimetastatic effects of NDRG1 in cancer cells.
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Affiliation(s)
- Jing Sun
- Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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17
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Kovacevic Z, Chikhani S, Lui GYL, Sivagurunathan S, Richardson DR. The iron-regulated metastasis suppressor NDRG1 targets NEDD4L, PTEN, and SMAD4 and inhibits the PI3K and Ras signaling pathways. Antioxid Redox Signal 2013; 18:874-87. [PMID: 22462691 DOI: 10.1089/ars.2011.4273] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AIMS The metastasis suppressor gene, N-myc downstream regulated gene-1 (NDRG1), is negatively correlated with tumor progression in multiple neoplasms, including pancreatic cancer. Moreover, NDRG1 is an iron-regulated gene that is markedly upregulated by cellular iron-depletion using novel antitumor agents such as the chelator, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), in pancreatic cancer cells. However, the exact function(s) of NDRG1 remain to be established and are important to elucidate. RESULTS In the current study, using gene-array analysis along with NDRG1 overexpression and silencing, we identified the molecular targets of NDRG1 in three pancreatic cancer cell lines. We demonstrate that NDRG1 upregulates neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) and GLI-similar-3 (GLIS3). Further studies examining the downstream effects of NEDD4L led to the discovery that NDRG1 affects the transforming growth factor-β (TGF-β) pathway, leading to the upregulation of two key tumor suppressor proteins, namely phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and mothers against decapentaplegic homolog-4 (SMAD4). Moreover, NDRG1 inhibited the phosphatidylinositol 3-kinase (PI3K) and Ras oncogenic pathways. INNOVATION This study provides significant insights into the mechanisms underlying the antitumor activity of NDRG1. For the first time, a role for NDRG1 is established in regulating the key signaling pathways involved in oncogenesis (TGF-β, PI3K, and Ras pathways). CONCLUSION The identified target genes of NDRG1 and their effect on the TGF-β signaling pathway reveal its molecular function in pancreatic cancer and a novel therapeutic avenue.
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Affiliation(s)
- Zaklina Kovacevic
- Department of Pathology, University of Sydney, Sydney, New South Wales, Australia
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18
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Ramirez T, Longato L, Dostalek M, Tong M, Wands JR, de la Monte SM. Insulin resistance, ceramide accumulation and endoplasmic reticulum stress in experimental chronic alcohol-induced steatohepatitis. Alcohol Alcohol 2012; 48:39-52. [PMID: 22997409 DOI: 10.1093/alcalc/ags106] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
AIMS Chronic alcohol abuse causes steatohepatitis with insulin resistance, which impairs hepatocellular growth, survival and metabolism. However, growing evidence supports the concept that progressive alcohol-related liver injury may be mediated by concurrent mal-signaling through other networks that promote insulin resistance, e.g. pro-inflammatory, pro-ceramide and endoplasmic reticulum (ER) stress cascades. METHODS Using the Long Evans rat model of chronic ethanol feeding, we characterized the histopathologic and ultrastructural features of steatohepatitis in relation to biochemical and molecular indices of tissue injury, inflammation, insulin resistance, dysregulated lipid metabolism and ER stress. RESULTS Chronic steatohepatitis with early chicken-wire fibrosis was associated with enlargement of mitochondria and disruption of ER structure by electron microscopy, elevated indices of lipid storage, lipid peroxidation and DNA damage, increased activation of pro-inflammatory cytokines, impaired signaling through the insulin receptor (InR), InR substrate-1, Akt, ribosomal protein S6 kinase and proline-rich Akt substrate 40 kDa, glycogen synthase kinase 3β activation and constitutive up-regulation of ceramide and ER stress-related genes. Liquid chromatography coupled with tandem mass spectrometry demonstrated altered ceramide profiles with higher levels of C14 and C18, and reduced C16 species in ethanol-exposed livers. CONCLUSION The histopathologic and ultrastructural abnormalities in chronic alcohol-related steatohepatitis are associated with persistent hepatic insulin resistance and pro-inflammatory cytokine activation, dysregulated lipid metabolism with altered ceramide profiles and both ER and oxidative stress. Corresponding increases in lipid peroxidation, DNA damage and protein carbonylation may have contributed to the chronicity and progression of disease. The findings herein suggest that multi-pronged therapeutic strategies may be needed for effective treatment of chronic alcoholic liver disease in humans.
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Affiliation(s)
- Teresa Ramirez
- Liver Research Center, Divisions of Gastroenterology and Neuropathology, Departments of Medicine, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Claverick Street, Providence, RI 02903, USA
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19
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Reddy SDN, Pakala SB, Molli PR, Sahni N, Karanam NK, Mudvari P, Kumar R. Metastasis-associated protein 1/histone deacetylase 4-nucleosome remodeling and deacetylase complex regulates phosphatase and tensin homolog gene expression and function. J Biol Chem 2012; 287:27843-50. [PMID: 22700976 PMCID: PMC3431680 DOI: 10.1074/jbc.m112.348474] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 06/13/2012] [Indexed: 12/11/2022] Open
Abstract
Metastasis-associated protein 1 (MTA1) is widely overexpressed in human cancers and is associated with malignant phenotypic changes contributing to morbidity in the associated diseases. Here we discovered for the first time that MTA1, a master chromatin modifier, transcriptionally represses the expression of phosphatase and tensin homolog (PTEN), a tumor suppressor gene, by recruiting class II histone deacetylase 4 (HDAC4) along with the transcription factor Yin-Yang 1 (YY1) onto the PTEN promoter. We also found evidence of an inverse correlation between the expression levels of MTA1 and PTEN in physiologically relevant breast cancer microarray datasets. We found that MTA1 up-regulation leads to a decreased expression of PTEN protein and stimulation of PI3K as well as phosphorylation of its signaling targets. Accordingly, selective down-regulation of MTA1 in breast cancer cells increases PTEN expression and inhibits stimulation of the PI3K/AKT signaling. Collectively, these findings provide a mechanistic role for MTA1 in transcriptional repression of PTEN, leading to modulation of the resulting signaling pathways.
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Affiliation(s)
- Sirigiri Divijendra Natha Reddy
- From the Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, The George Washington University, Washington, D. C. 20037
| | - Suresh B. Pakala
- From the Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, The George Washington University, Washington, D. C. 20037
| | - Poonam R. Molli
- From the Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, The George Washington University, Washington, D. C. 20037
| | - Neil Sahni
- From the Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, The George Washington University, Washington, D. C. 20037
| | - Narasimha Kumar Karanam
- From the Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, The George Washington University, Washington, D. C. 20037
| | - Prakriti Mudvari
- From the Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, The George Washington University, Washington, D. C. 20037
| | - Rakesh Kumar
- From the Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, The George Washington University, Washington, D. C. 20037
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20
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Cheung LWT, Hennessy BT, Li J, Yu S, Myers AP, Djordjevic B, Lu Y, Stemke-Hale K, Dyer MD, Zhang F, Ju Z, Cantley LC, Scherer SE, Liang H, Lu KH, Broaddus RR, Mills GB. High frequency of PIK3R1 and PIK3R2 mutations in endometrial cancer elucidates a novel mechanism for regulation of PTEN protein stability. Cancer Discov 2011; 1:170-85. [PMID: 21984976 DOI: 10.1158/2159-8290.cd-11-0039] [Citation(s) in RCA: 356] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We demonstrate that phosphatidylinositol 3-kinase (PI3K) pathway aberrations occur in >80% of endometrioid endometrial cancers, with coordinate mutations of multiple PI3K pathway members being more common than predicted by chance. PIK3R1 (p85α) mutations occur at a higher rate in endometrial cancer than in any other tumor lineage, and PIK3R2 (p85β), not previously demonstrated to be a cancer gene, is also frequently mutated. The dominant activation event in the PI3K pathway appears to be PTEN protein loss. However, in tumors with retained PTEN protein, PI3K pathway mutations phenocopy PTEN loss, resulting in pathway activation. KRAS mutations are common in endometrioid tumors activating independent events from PI3K pathway aberrations. Multiple PIK3R1 and PIK3R2 mutations demonstrate gain of function, including disruption of a novel mechanism of pathway regulation wherein p85α dimers bind and stabilize PTEN. Taken together, the PI3K pathway represents a critical driver of endometrial cancer pathogenesis and a novel therapeutic target.
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Affiliation(s)
- Lydia W T Cheung
- Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77054-1942.
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21
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Abstract
PTEN phosphatase is a potent tumor suppressor that regulates multiple cellular functions. In the cytoplasm, PTEN dephosphorylates its primary lipid substrate, phosphatidylinositol 3,4,5-trisphosphate, to antagonize the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway. It has also become increasingly evident that PTEN functions in the nucleus and may play an important part in transcription regulation, but its nuclear targets remain elusive. In this report, we demonstrate the transcription factor cyclic AMP response element-binding protein (CREB) is a protein target of PTEN phosphatase and that PTEN deficiency leads to CREB phosphorylation independent of the PI3K/AKT pathway. Using confocal immunofluorescence and reciprocal immunoprecipitation, we further show that PTEN colocalizes with CREB and physically interacts with CREB. Moreover, we use both in vitro and in vivo experiments to show PTEN can dephosphorylate CREB in a phosphatase-dependent manner, suggesting that CREB is a substrate of PTEN nuclear phosphatase. Loss of Pten results in an elevated RNA level of multiple CREB transcriptional targets and increased cell proliferation, which can be reversed by a nonphosphorylatable CREB mutant or knockdown of CREB. These data reveal a mechanism for PTEN modulation of CREB-mediated gene transcription and cell growth. Our study thus characterizes PTEN as a nuclear phophatase of a transcription factor and identifies CREB as a novel protein target of PTEN phosphatase, which contributes to better understanding of PTEN function in the nucleus.
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Affiliation(s)
- Tingting Gu
- Institute of Systems Biomedicine, Peking University Health Science Center, Beijing, China
| | - Zhong Zhang
- Institute of Systems Biomedicine, Peking University Health Science Center, Beijing, China
| | - Jianli Wang
- Institute of Systems Biomedicine, Peking University Health Science Center, Beijing, China
| | - Junyi Guo
- Institute of Systems Biomedicine, Peking University Health Science Center, Beijing, China
| | - Wen Hong Shen
- Department of Radiation Oncology, Weill Medical College of Cornell University, New York, New York
| | - Yuxin Yin
- Institute of Systems Biomedicine, Peking University Health Science Center, Beijing, China
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