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Sample records for lipid phosphatase pten

  1. Assays to Measure PTEN Lipid Phosphatase Activity In Vitro from Purified Enzyme or Immunoprecipitates.

    PubMed

    Spinelli, Laura; Leslie, Nicholas R

    2016-01-01

    PTEN is a one of the most frequently mutated tumor suppressors in human cancers. It is essential for regulating diverse biological processes and through its lipid phosphatase activity regulates the PI 3-Kinase signaling pathway. Sensitive phosphatase assays are employed to study the catalytic activity of PTEN against phospholipid substrates. Here we describe protocols to assay PTEN lipid phosphatase activity using either purified enzyme (purified PTEN lipid phosphatase assay) or PTEN immunopurified from tissues or cultured cells (cellular IP PTEN lipid phosphatase assay) against vesicles containing radiolabeled PIP3 substrate. PMID:27514802

  2. Differential Requirement for Pten Lipid and Protein Phosphatase Activity during Zebrafish Embryonic Development

    PubMed Central

    Stumpf, Miriam; den Hertog, Jeroen

    2016-01-01

    The lipid- and protein phosphatase PTEN is one of the most frequently mutated tumor suppressor genes in human cancers and many mutations found in tumor samples directly affect PTEN phosphatase activity. In order to understand the functional consequences of these mutations in vivo, the aim of our study was to dissect the role of Pten phosphatase activities during zebrafish embryonic development. As in other model organisms, zebrafish mutants lacking functional Pten are embryonically lethal. Zebrafish have two pten genes and pten double homozygous zebrafish embryos develop a severe pleiotropic phenotype around 4 days post fertilization, which can be largely rescued by re-introduction of pten mRNA at the one-cell stage. We used this assay to characterize the rescue-capacity of Pten and variants with mutations that disrupt lipid, protein or both phosphatase activities. The pleiotropic phenotype at 4dpf could only be rescued by wild type Pten, indicating that both phosphatase activities are required for normal zebrafish embryonic development. An earlier aspect of the phenotype, hyperbranching of intersegmental vessels, however, was rescued by Pten that retained lipid phosphatase activity, independent of protein phosphatase activity. Lipid phosphatase activity was also required for moderating pAkt levels at 4 dpf. We propose that the role of Pten during angiogenesis mainly consists of suppressing PI3K signaling via its lipid phosphatase activity, whereas the complex process of embryonic development requires lipid and protein phosphatase of Pten. PMID:26848951

  3. Suppression of cellular proliferation and invasion by the concerted lipid and protein phosphatase activities of PTEN

    PubMed Central

    Davidson, Lindsay; Maccario, Helene; Perera, Nevin M.; Yang, Xuesong; Spinelli, Laura; Tibarewal, Priyanka; Glancy, Ben; Gray, Alex; Weijer, Cornelis J.; Downes, C. Peter; Leslie, Nick R.

    2009-01-01

    PTEN is a tumour suppressor with phosphatase activity in vitro against both lipids and proteins and other potential non-enzymatic mechanisms of action. Although the importance of PTEN’s lipid phosphatase activity in regulating the PI3K signalling pathway is recognised, the significance of PTEN’s other mechanisms of action is currently unclear. Here, we describe the systematic identification of a PTEN mutant, PTEN Y138L, with activity against lipid, but not soluble substrates. Using this mutant we provide evidence for the interfacial activation of PTEN against lipid substrates. We also show that when re-expressed at physiological levels in PTEN null U87MG glioblastoma cells the protein phosphatase activity of PTEN is not required to regulate cellular PtdInsP3 levels or the downstream protein kinase Akt/PKB. Finally, in 3D Matrigel cultures of U87MG cells similarly re-expressing PTEN mutants, both the protein and lipid phosphatase activities were required to inhibit invasion, but either activity alone significantly inhibited proliferation, albeit only weakly for the protein phosphatase activity. Our data provides a novel tool to address the significance of PTEN’s separable lipid and protein phosphatase activities and suggest that both activities act to suppress proliferation and act together to suppress invasion. PMID:19915616

  4. ZN2+ INDUCES COX-2 EXPRESSION THROUGH DOWNREGULATION OF LIPID PHOSPHATASE PTEN

    EPA Science Inventory

    Zn2+ Induces COX-2 Expression through Downregulation of Lipid Phosphatase PTEN
    Weidong Wu*, James M. Samet, Philip A. Bromberg*?, Young E. Whang?, and Lee M. Graves* ?
    *CEMALB, ?Department of Medicine, and ?Department of Pharmacology, UNC-Chapel Hill, NC27599; Human Studie...

  5. PTEN Increases Autophagy and Inhibits the Ubiquitin-Proteasome Pathway in Glioma Cells Independently of its Lipid Phosphatase Activity

    PubMed Central

    Errafiy, Rajaa; Aguado, Carmen; Ghislat, Ghita; Esteve, Juan M.; Gil, Anabel; Loutfi, Mohammed; Knecht, Erwin

    2013-01-01

    Two major mechanisms of intracellular protein degradation, autophagy and the ubiquitin-proteasome pathway, operate in mammalian cells. PTEN, which is frequently mutated in glioblastomas, is a tumor suppressor gene that encodes a dual specificity phosphatase that antagonizes the phosphatidylinositol 3-kinase class I/AKT/mTOR pathway, which is a key regulator of autophagy. Here, we investigated in U87MG human glioma cells the role of PTEN in the regulation of autophagy and the ubiquitin-proteasome pathway, because both are functionally linked and are relevant in cancer progression. Since U87MG glioma cells lack a functional PTEN, we used stable clones that express, under the control of a tetracycline-inducible system (Tet-on), wild-type PTEN and two of its mutants, G129E-PTEN and C124S-PTEN, which, respectively, lack the lipid phosphatase activity only and both the lipid and the protein phosphatase activities of this protein. Expression of PTEN in U87MG glioma cells decreased proteasome activity and also reduced protein ubiquitination. On the contrary, expression of PTEN increased the autophagic flux and the lysosomal mass. Interestingly, and although PTEN negatively regulates the phosphatidylinositol 3-kinase class I/AKT/mTOR signaling pathway by its lipid phosphatase activity, both effects in U87MG cells were independent of this activity. These results suggest a new mTOR-independent signaling pathway by which PTEN can regulate in opposite directions the main mechanisms of intracellular protein degradation. PMID:24349488

  6. Mutational spectra of PTEN/MMAC1 gene: a tumor suppressor with lipid phosphatase activity.

    PubMed

    Ali, I U; Schriml, L M; Dean, M

    1999-11-17

    PTEN/MMAC1 (phosphatase, tensin homologue/mutated in multiple advanced cancers) is a tumor suppressor protein that has sequence homology with dual-specificity phosphatases, which are capable of dephosphorylating both tyrosine phosphate and serine/threonine phosphate residues on proteins. The in vivo function of PTEN/MMAC1 appears to be dephosphorylation of phosphotidylinositol 3,4, 5-triphosphate. The PTEN/MMAC1 gene is mutated in the germline of patients with rare autosomal dominant cancer syndromes and in subsets of specific cancers. Here we review the mutational spectra of the PTEN/MMAC1 gene in tumors from various tissues, especially endometrium, brain, prostate, and ovary, in which the gene is inactivated very frequently. Germline and somatic mutations in the PTEN/MMAC1 gene occur mostly in the protein coding region and involve the phosphatase domain and poly(A)(6) stretches. Compared with germline alterations found in the PTEN/MMAC1 gene, there is a substantially increased frequency of frameshift mutations in tumors. Glioblastomas and endometrial carcinomas appear to have distinct mutational spectra, probably reflecting differences in the underlying mechanisms of inactivation of the PTEN/MMAC1 gene in the two tissue types. Also, depending on the tissue type, the gene appears to be involved in the initiation or the progression of cancers. Further understanding of PTEN/MMAC1 gene mutations in different tumors and the physiologic consequences of these mutations is likely to open up new therapeutic opportunities for targeting this critical gene.

  7. Pten (phosphatase and tensin homologue gene) haploinsufficiency promotes insulin hypersensitivity

    PubMed Central

    Wong, J. T.; Kim, P. T. W.; Peacock, J. W.; Yau, T. Y.; Mui, A. L.-F.; Chung, S. W.; Sossi, V.; Doudet, D.; Green, D.; Ruth, T. J.; Parsons, R.; Verchere, C. B.

    2006-01-01

    Aims/hypothesis Insulin controls glucose metabolism via multiple signalling pathways, including the phosphatidylinositol 3-kinase (PI3K) pathway in muscle and adipose tissue. The protein/lipid phosphatase Pten (phosphatase and tensin homologue deleted on chromosome 10) attenuates PI3K signalling by dephosphorylating the phosphatidylinositol 3,4,5-trisphosphate generated by PI3K. The current study was aimed at investigating the effect of haploinsufficiency for Pten on insulin-stimulated glucose uptake. Materials and methods Insulin sensitivity in Pten heterozygous (Pten+/−) mice was investigated in i.p. insulin challenge and glucose tolerance tests. Glucose uptake was monitored in vitro in primary cultures of myocytes from Pten+/− mice, and in vivo by positron emission tomography. The phosphorylation status of protein kinase B (PKB/Akt), a downstream signalling protein in the PI3K pathway, and glycogen synthase kinase 3β (GSK3β), a substrate of PKB/Akt, was determined by western immunoblotting. Results Following i.p. insulin challenge, blood glucose levels in Pten+/− mice remained depressed for up to 120 min, whereas glucose levels in wild-type mice began to recover after approximately 30 min. After glucose challenge, blood glucose returned to normal about twice as rapidly in Pten+/− mice. Enhanced glucose uptake was observed both in Pten+/− myocytes and in skeletal muscle of Pten+/− mice by PET. PKB and GSK3β phosphorylation was enhanced and prolonged in Pten+/− myocytes. Conclusions/interpretation Pten is a key negative regulator of insulin-stimulated glucose uptake in vitro and in vivo. The partial reduction of Pten due to Pten haploinsufficiency is enough to elicit enhanced insulin sensitivity and glucose tolerance in Pten+/− mice. PMID:17195063

  8. PTEN

    PubMed Central

    Garcia-Junco-Clemente, Pablo; Golshani, Peyman

    2014-01-01

    PTEN (phosphatase and tensin homolog on chromosome ten) is a dual protein/lipid phosphatase that dephosphorylates PIP3, thereby inhibiting the AKT/mTOR pathway. This inhibition ultimately decreases protein translation, cell proliferation and cell growth. In the central nervous system, inhibition of PTEN leads to increased stem cell proliferation, somatic, dendritic and axonal growth, accelerated spine maturation, diminished synaptic plasticity, and altered intrinsic excitability. In agreement with these findings, patients carrying single-copy inactivating mutations of PTEN suffer from autism, macrocephaly, mental retardation, and epilepsy.1-9 Understanding the mechanisms through which PTEN modulates the structure, function, and plasticity of cortical networks is a major focus of study. Preventing and reversing the changes induced by loss of Pten in model animals will pave the way for treatments in humans. PMID:24778766

  9. Fine-Tuning of Pten Localization and Phosphatase Activity Is Essential for Zebrafish Angiogenesis.

    PubMed

    Stumpf, Miriam; Blokzijl-Franke, Sasja; den Hertog, Jeroen

    2016-01-01

    The lipid- and protein phosphatase PTEN is an essential tumor suppressor that is highly conserved among all higher eukaryotes. As an antagonist of the PI3K/Akt cell survival and proliferation pathway, it exerts its most prominent function at the cell membrane, but (PIP3-independent) functions of nuclear PTEN have been discovered as well. PTEN subcellular localization is tightly controlled by its protein conformation. In the closed conformation, PTEN localizes predominantly to the cytoplasm. Opening up of the conformation of PTEN exposes N-terminal and C-terminal regions of the protein that are required for both interaction with the cell membrane and translocation to the nucleus. Lack of Pten leads to hyperbranching of the intersegmental vessels during zebrafish embryogenesis, which is rescued by expression of exogenous Pten. Here, we observed that expression of mutant PTEN with an open conformation rescued the hyperbranching phenotype in pten double homozygous embryos and suppressed the increased p-Akt levels that are characteristic for embryos lacking Pten. In addition, in pten mutant and wild type embryos alike, open conformation PTEN induced stalled intersegmental vessels, which fail to connect with the dorsal longitudinal anastomotic vessel. Functional hyperactivity of open conformation PTEN in comparison to wild type PTEN seems to result predominantly from its enhanced recruitment to the cell membrane. Enhanced recruitment of phosphatase inactive mutants to the membrane did not induce the stalled vessel phenotype nor did it rescue the hyperbranching phenotype in pten double homozygous embryos, indicating that PTEN phosphatase activity is indispensable for its regulatory function during angiogenesis. Taken together, our data suggest that PTEN phosphatase activity needs to be carefully fine-tuned for normal embryogenesis and that the control of its subcellular localization is a key mechanism in this process. PMID:27138341

  10. Fine-Tuning of Pten Localization and Phosphatase Activity Is Essential for Zebrafish Angiogenesis

    PubMed Central

    Stumpf, Miriam; Blokzijl-Franke, Sasja; den Hertog, Jeroen

    2016-01-01

    The lipid- and protein phosphatase PTEN is an essential tumor suppressor that is highly conserved among all higher eukaryotes. As an antagonist of the PI3K/Akt cell survival and proliferation pathway, it exerts its most prominent function at the cell membrane, but (PIP3-independent) functions of nuclear PTEN have been discovered as well. PTEN subcellular localization is tightly controlled by its protein conformation. In the closed conformation, PTEN localizes predominantly to the cytoplasm. Opening up of the conformation of PTEN exposes N-terminal and C-terminal regions of the protein that are required for both interaction with the cell membrane and translocation to the nucleus. Lack of Pten leads to hyperbranching of the intersegmental vessels during zebrafish embryogenesis, which is rescued by expression of exogenous Pten. Here, we observed that expression of mutant PTEN with an open conformation rescued the hyperbranching phenotype in pten double homozygous embryos and suppressed the increased p-Akt levels that are characteristic for embryos lacking Pten. In addition, in pten mutant and wild type embryos alike, open conformation PTEN induced stalled intersegmental vessels, which fail to connect with the dorsal longitudinal anastomotic vessel. Functional hyperactivity of open conformation PTEN in comparison to wild type PTEN seems to result predominantly from its enhanced recruitment to the cell membrane. Enhanced recruitment of phosphatase inactive mutants to the membrane did not induce the stalled vessel phenotype nor did it rescue the hyperbranching phenotype in pten double homozygous embryos, indicating that PTEN phosphatase activity is indispensable for its regulatory function during angiogenesis. Taken together, our data suggest that PTEN phosphatase activity needs to be carefully fine-tuned for normal embryogenesis and that the control of its subcellular localization is a key mechanism in this process. PMID:27138341

  11. Controlling PTEN (Phosphatase and Tensin Homolog) Stability: A DOMINANT ROLE FOR LYSINE 66.

    PubMed

    Gupta, Amit; Leslie, Nicholas R

    2016-08-26

    Phosphatase and tensin homolog (PTEN) is a phosphoinositide lipid phosphatase and one of the most frequently disrupted tumor suppressors in many forms of cancer, with even small reductions in the expression levels of PTEN promoting cancer development. Although the post-translational ubiquitination of PTEN can control its stability, activity, and localization, a detailed understanding of how PTEN ubiquitination integrates with other cellular regulatory processes and may be dysregulated in cancer has been hampered by a poor understanding of the significance of ubiquitination at individual sites. Here we show that Lys(66) is not required for cellular activity, yet dominates over other PTEN ubiquitination sites in the regulation of protein stability. Notably, combined mutation of other sites (Lys(13), Lys(80), and Lys(289)) has relatively little effect on protein expression, protein stability, or PTEN polyubiquitination. The present work identifies a key role for Lys(66) in the regulation of PTEN expression and provides both an opportunity to improve the stability of PTEN as a protein therapy and a mechanistic basis for efforts to stabilize endogenous PTEN. PMID:27405757

  12. Controlling PTEN (Phosphatase and Tensin Homolog) Stability: A DOMINANT ROLE FOR LYSINE 66.

    PubMed

    Gupta, Amit; Leslie, Nicholas R

    2016-08-26

    Phosphatase and tensin homolog (PTEN) is a phosphoinositide lipid phosphatase and one of the most frequently disrupted tumor suppressors in many forms of cancer, with even small reductions in the expression levels of PTEN promoting cancer development. Although the post-translational ubiquitination of PTEN can control its stability, activity, and localization, a detailed understanding of how PTEN ubiquitination integrates with other cellular regulatory processes and may be dysregulated in cancer has been hampered by a poor understanding of the significance of ubiquitination at individual sites. Here we show that Lys(66) is not required for cellular activity, yet dominates over other PTEN ubiquitination sites in the regulation of protein stability. Notably, combined mutation of other sites (Lys(13), Lys(80), and Lys(289)) has relatively little effect on protein expression, protein stability, or PTEN polyubiquitination. The present work identifies a key role for Lys(66) in the regulation of PTEN expression and provides both an opportunity to improve the stability of PTEN as a protein therapy and a mechanistic basis for efforts to stabilize endogenous PTEN.

  13. Molecular Features of Phosphatase and Tensin Homolog (PTEN) Regulation by C-terminal Phosphorylation.

    PubMed

    Chen, Zan; Dempsey, Daniel R; Thomas, Stefani N; Hayward, Dawn; Bolduc, David M; Cole, Philip A

    2016-07-01

    PTEN is a tumor suppressor that functions to negatively regulate the PI3K/AKT pathway as the lipid phosphatase for phosphatidylinositol 3,4,5-triphosphate. Phosphorylation of a cluster of Ser/Thr residues (amino acids 380-385) on the C-terminal tail serves to alter the conformational state of PTEN from an open active state to a closed inhibited state, resulting in a reduction of plasma membrane localization and inhibition of enzyme activity. The relative contribution of each phosphorylation site to PTEN autoinhibition and the structural basis for the conformational closure is still unclear. To further the structural understanding of PTEN regulation by C-terminal tail phosphorylation, we used protein semisynthesis to insert stoichiometric and site-specific phospho-Ser/Thr(s) in the C-terminal tail of PTEN. Additionally, we employed photo-cross-linking to map the intramolecular PTEN interactions of the phospho-tail. Systematic evaluation of the PTEN C-tail phospho-cluster showed autoinhibition, and conformational closure was influenced by the aggregate effect of multiple phospho-sites rather than dominated by a single phosphorylation site. Moreover, photo-cross-linking suggested a direct interaction between the PTEN C-tail and a segment in the N-terminal region of the catalytic domain. Mutagenesis experiments provided additional insights into how the PTEN phospho-tail interacts with both the C2 and catalytic domains.

  14. Redox Modulation of PTEN Phosphatase Activity by Hydrogen Peroxide and Bisperoxidovanadium Complexes.

    PubMed

    Lee, Chang-Uk; Hahne, Gernot; Hanske, Jonas; Bange, Tanja; Bier, David; Rademacher, Christoph; Hennig, Sven; Grossmann, Tom N

    2015-11-01

    PTEN is a dual-specificity protein tyrosine phosphatase. As one of the central tumor suppressors, a thorough regulation of its activity is essential for proper cellular homeostasis. The precise implications of PTEN inhibition by reactive oxygen species (e.g. H2 O2 ) and the subsequent structural consequences remain elusive. To study the effects of PTEN inhibition, bisperoxidovanadium (bpV) complexes serve as important tools with the potential for the treatment of nerve injury or cardiac ischemia. However, their mode of action is unknown, hampering further optimization and preventing therapeutic applications. Based on protein crystallography, mass spectrometry, and NMR spectroscopy, we elucidate the molecular basis of PTEN inhibition by H2O2 and bpV complexes. We show that both molecules inhibit PTEN via oxidative mechanisms resulting in the formation of the same intramolecular disulfide, therefore enabling the reactivation of PTEN under reductive conditions.

  15. Redox Modulation of PTEN Phosphatase Activity by Hydrogen Peroxide and Bisperoxidovanadium Complexes

    PubMed Central

    Lee, Chang-Uk; Hahne, Gernot; Hanske, Jonas; Bange, Tanja; Bier, David; Rademacher, Christoph; Hennig, Sven; Grossmann, Tom N

    2015-01-01

    PTEN is a dual-specificity protein tyrosine phosphatase. As one of the central tumor suppressors, a thorough regulation of its activity is essential for proper cellular homeostasis. The precise implications of PTEN inhibition by reactive oxygen species (e.g. H2O2) and the subsequent structural consequences remain elusive. To study the effects of PTEN inhibition, bisperoxidovanadium (bpV) complexes serve as important tools with the potential for the treatment of nerve injury or cardiac ischemia. However, their mode of action is unknown, hampering further optimization and preventing therapeutic applications. Based on protein crystallography, mass spectrometry, and NMR spectroscopy, we elucidate the molecular basis of PTEN inhibition by H2O2 and bpV complexes. We show that both molecules inhibit PTEN via oxidative mechanisms resulting in the formation of the same intramolecular disulfide, therefore enabling the reactivation of PTEN under reductive conditions. PMID:26418532

  16. PTEN Phosphatase-Independent Maintenance of Glandular Morphology in a Predictive Colorectal Cancer Model System1

    PubMed Central

    Jagan, Ishaan C; Deevi, Ravi K; Fatehullah, Aliya; Topley, Rebecca; Eves, Joshua; Stevenson, Michael; Loughrey, Maurice; Arthur, Kenneth; Campbell, Frederick Charles

    2013-01-01

    Organotypic models may provide mechanistic insight into colorectal cancer (CRC) morphology. Three-dimensional (3D) colorectal gland formation is regulated by phosphatase and tensin homologue deleted on chromosome 10 (PTEN) coupling of cell division cycle 42 (cdc42) to atypical protein kinase C (aPKC). This study investigated PTEN phosphatase-dependent and phosphatase-independent morphogenic functions in 3D models and assessed translational relevance in human studies. Isogenic PTEN-expressing or PTEN-deficient 3D colorectal cultures were used. In translational studies, apical aPKC activity readout was assessed against apical membrane (AM) orientation and gland morphology in 3D models and human CRC. We found that catalytically active or inactive PTEN constructs containing an intact C2 domain enhanced cdc42 activity, whereas mutants of the C2 domain calcium binding region 3 membrane-binding loop (M-CBR3) were ineffective. The isolated PTEN C2 domain (C2) accumulated in membrane fractions, but C2 M-CBR3 remained in cytosol. Transfection of C2 but not C2 M-CBR3 rescued defective AM orientation and 3D morphogenesis of PTEN-deficient Caco-2 cultures. The signal intensity of apical phospho-aPKC correlated with that of Na+/H+ exchanger regulatory factor-1 (NHERF-1) in the 3D model. Apical NHERF-1 intensity thus provided readout of apical aPKC activity and associated with glandular morphology in the model system and human colon. Low apical NHERF-1 intensity in CRC associated with disruption of glandular architecture, high cancer grade, and metastatic dissemination. We conclude that the membrane-binding function of the catalytically inert PTEN C2 domain influences cdc42/aPKC-dependent AM dynamics and gland formation in a highly relevant 3D CRC morphogenesis model system. PMID:24348097

  17. PTEN regulates angiogenesis and VEGF expression through phosphatase-dependent and -independent mechanisms in HepG2 cells.

    PubMed

    Tian, Tao; Nan, Ke-Jun; Wang, Shu-Hong; Liang, Xuan; Lu, Chuang-Xin; Guo, Hui; Wang, Wen-Juan; Ruan, Zhi-Ping

    2010-07-01

    Hepatocellular carcinoma (HCC) is a typical hypervascular tumor, and increased levels of vascular endothelial growth factor (VEGF) are associated with progression of HCC. Tumor suppression gene PTEN (phosphatase and tensin homolog deleted on chromosome 10), an important antagonist of the phosphoinositide-3-kinase (PI3K)/adenosine triphosphate-dependent tyrosine kinase (Akt) pathway, is also commonly lost or mutated in HCC. However, the effect of PTEN on VEGF-mediated angiogenesis in HCC remains unknown. To explore this relationship, we expressed a panel of PTEN mutants in human HCC cells with low expression of PTEN (HepG2 cells). Overexpression of PTEN in HepG2 cells resulted in the downregulation of proliferation and migration of cocultured endothelial cells and decreased expression of hypoxia-inducible factor 1 (HIF-1) and VEGF. Similarly, using a nude mouse model, we demonstrated that PTEN decreased expression of HIF-1 and VEGF and suppressed HepG2-induced angiogenesis. This inhibitory effect was not observed in cells expressing a phosphatase-deficient PTEN mutant, suggesting that PTEN inhibits angiogenesis and VEGF through a phosphatase-dependent pathway. Strikingly, reintroducing the C2 domain of PTEN also resulted in a significant decrease in angiogenesis and VEGF expression, although it did not affect Akt phosphorylation or HIF-1 expression. In summary, this study suggests the novel viewpoint that PTEN suppresses angiogenesis and VEGF expression in HCC through both phosphatase-dependent and -independent mechanisms.

  18. PTEN interaction with tethered bilayer lipid membranes containing PI(4,5)P2

    NASA Astrophysics Data System (ADS)

    Moldovan, R.; Shenoy, S.; Shekhar, P.; Kalinowski, A.; Gericke, A.; Heinrich, F.; Loesche, M.

    2009-03-01

    Synthetic lipid membrane models are frequently used for the study of biophysical processes at cell membranes. We use a robust membrane model, the tethered bilayer lipid membrane (tBLM), based on a (C14)2-(PEO)6-thiol anchor, WC14 [1]. Such membranes can be prepared to contain single phospholipids or complex lipid mixtures [2], including functional lipids involved in cell signaling, such as the highly charged phosphatidylinositol phosphates (PIPs). To study the interaction between the tumor suppressor PTEN (phosphatase and tensin homologue deleted on chromosome 10) and model membranes we have incorporated phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) in tBLMs and use fluorescence correlation spectroscopy (FCS), neutron reflectometry (NR) and surface plasmon resonance (SPR) for their characterization. NR shows that tBLMs formed with PI(4,5)P2 are complete. FCS of labeled PI(4,5)P2 shows that diffusion occurs at the time scale characteristic of membrane-incorporated lipid. Finally, SPR shows specific binding of PTEN to the model membrane thus confirming the incorporation of PI(4,5)P2 into the tBLM. [1] McGillivray et al, Biointerphases 2, 21-33 (2007) [2] Heinrich et al, Langmuir, submitted

  19. Focus on PTEN Regulation

    PubMed Central

    Bermúdez Brito, Miriam; Goulielmaki, Evangelia; Papakonstanti, Evangelia A.

    2015-01-01

    The role of phosphatase and tensin homolog on chromosome 10 (PTEN) as a tumor suppressor has been for a long time attributed to its lipid phosphatase activity against PI(3,4,5)P3, the phospholipid product of the class I PI3Ks. Besides its traditional role as a lipid phosphatase at the plasma membrane, a wealth of data has shown that PTEN can function independently of its phosphatase activity and that PTEN also exists and plays a role in the nucleus, in cytoplasmic organelles, and extracellularly. Accumulating evidence has shed light on diverse physiological functions of PTEN, which are accompanied by a complex regulation of its expression and activity. PTEN levels and function are regulated transcriptionally, post-transcriptionally, and post-translationally. PTEN is also sensitive to regulation by its interacting proteins and its localization. Herein, we summarize the current knowledge on mechanisms that regulate the expression and enzymatic activity of PTEN and its role in human diseases. PMID:26284192

  20. Nuclear PTEN regulates the APC-CDH1 tumor-suppressive complex in a phosphatase-independent manner.

    PubMed

    Song, Min Sup; Carracedo, Arkaitz; Salmena, Leonardo; Song, Su Jung; Egia, Ainara; Malumbres, Marcos; Pandolfi, Pier Paolo

    2011-01-21

    PTEN is a frequently mutated tumor suppressor gene that opposes the PI3K/AKT pathway through dephosphorylation of phosphoinositide-3,4,5-triphosphate. Recently, nuclear compartmentalization of PTEN was found as a key component of its tumor-suppressive activity; however its nuclear function remains poorly defined. Here we show that nuclear PTEN interacts with APC/C, promotes APC/C association with CDH1, and thereby enhances the tumor-suppressive activity of the APC-CDH1 complex. We find that nuclear exclusion but not phosphatase inactivation of PTEN impairs APC-CDH1. This nuclear function of PTEN provides a straightforward mechanistic explanation for the fail-safe cellular senescence response elicited by acute PTEN loss and the tumor-suppressive activity of catalytically inactive PTEN. Importantly, we demonstrate that PTEN mutant and PTEN null states are not synonymous as they are differentially sensitive to pharmacological inhibition of APC-CDH1 targets such as PLK1 and Aurora kinases. This finding identifies a strategy for cancer patient stratification and, thus, optimization of targeted therapies. PAPERCLIP:

  1. Nuclear PTEN regulates the APC-CDH1 tumor suppressive complex in a phosphatase-independent manner

    PubMed Central

    Song, Min Sup; Carracedo, Arkaitz; Salmena, Leonardo; Song, Su Jung; Egia, Ainara; Malumbres, Marcos; Pandolfi, Pier Paolo

    2011-01-01

    SUMMARY PTEN is a frequently mutated tumor suppressor gene that opposes the PI3K-AKT pathway through dephosphorylation of phosphoinositide-3,4,5-triphosphate. Recently, nuclear compartmentalization of PTEN was found as a key component of its tumor suppressive activity, however its nuclear function remains poorly defined. Here we show that nuclear PTEN interacts with APC/C, promotes APC/C association with CDH1, and thereby enhances the tumor suppressive activity of the APC-CDH1 complex. We find that nuclear exclusion but not phosphatase inactivation of PTEN impairs APC-CDH1. This nuclear function of PTEN provides a straightforward mechanistic explanation for the fail-safe cellular senescence response elicited by acute PTEN loss and the tumor suppressive activity of catalytically-inactive PTEN. Importantly, we demonstrate that PTEN-mutant and PTEN-null states are not synonymous since they are differentially sensitive to pharmacological inhibition of APC-CDH1 targets such as PLK1 and Aurora Kinases. This finding identifies a strategy for cancer patient stratification and thus, optimization of targeted therapies. PMID:21241890

  2. Therapeutic targeting of cancers with loss of PTEN function

    PubMed Central

    Dillon, Lloye M.; Miller, Todd W.

    2015-01-01

    Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is one of the most frequently disrupted tumor suppressors in cancer. The lipid phosphatase activity of PTEN antagonizes the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathway to repress tumor cell growth and survival. In the nucleus, PTEN promotes chromosome stability and DNA repair. Consequently, loss of PTEN function increases genomic instability. PTEN deficiency is caused by inherited germline mutations, somatic mutations, epigenetic and transcriptional silencing, post-translational modifications, and protein-protein interactions. Given the high frequency of PTEN deficiency across cancer subtypes, therapeutic approaches that exploit PTEN loss-of-function could provide effective treatment strategies. Herein, we discuss therapeutic strategies aimed at cancers with loss of PTEN function, and the challenges involved in treating patients afflicted with such cancers. We review preclinical and clinical findings, and highlight novel strategies under development to target PTEN-deficient cancers. PMID:24387334

  3. Catalysis by the tumor-suppressor enzymes PTEN and PTEN-L.

    PubMed

    Johnston, Sean B; Raines, Ronald T

    2015-01-01

    Phosphatase and tensin homologue deleted from chromosome ten (PTEN) is a lipid phosphatase tumor suppressor that is lost or inactivated in most human tumors. The enzyme catalyzes the hydrolysis of phosphatidylinositol-(3,4,5)-trisphosphate (PIP3) to form phosphatidylinositol-(4,5)-bisphosphate (PIP2) and inorganic phosphate. Here, we report on the first continuous assay for the catalytic activity of PTEN. Using this assay, we demonstrate that human PTEN is activated by the reaction product PIP2, as well as in solutions of low salt concentration. This activation is abrogated in the K13A variant, which has a disruption in a putative binding site for PIP2. We also demonstrate that PTEN-L, which derives from alternative translation of the PTEN mRNA, is activated constitutively. These findings have implications for catalysis by PTEN in physiological environments and could expedite the development of PTEN-based chemotherapeutic agents.

  4. Cellular prostatic acid phosphatase, a PTEN-functional homologue in prostate epithelia, functions as a prostate-specific tumor suppressor

    PubMed Central

    Muniyan, Sakthivel; Ingersoll, Matthew A.; Batra, Surinder K.; Lin, Ming-Fong

    2014-01-01

    The inactivation of tumor suppressor genes (TSGs) plays a vital role in the progression of human cancers. Nevertheless, those ubiquitous TSGs have been shown with limited roles in various stages of diverse carcinogenesis. Investigation on identifying unique TSG, especially for early stage of carcinogenesis, is imperative. As such, the search for organ-specific TSGs has emerged as a major strategy in cancer research. Prostate cancer (PCa) has the highest incidence in solid tumors in US males. Cellular prostatic acid phosphatase (cPAcP) is a prostate-specific differentiation antigen. Despite intensive studies over the past several decades on PAcP as a PCa biomarker, the role of cPAcP as a PCa-specific tumor suppressor has only recently been emerged and validated. The mechanism underlying the pivotal role of cPAcP as a prostate-specific TSG is, in part, due to its function as a protein tyrosine phosphatase (PTP) as well as a phosphoinositide phosphatase (PIP), an apparent functional homologue to Phosphatase and tensin homolog (PTEN) in PCa cells. This review is focused on discussing the function of this authentic prostate-specific tumor suppressor and the mechanism behind the loss of cPAcP expression leading to prostate carcinogenesis. We review other phosphatases’ roles as TSGs which regulate oncogenic PI3K signaling in PCa and discuss the functional similarity between cPAcP and PTEN in prostate carcinogenesis. PMID:24747769

  5. PTEN: Multiple Functions in Human Malignant Tumors

    PubMed Central

    Milella, Michele; Falcone, Italia; Conciatori, Fabiana; Cesta Incani, Ursula; Del Curatolo, Anais; Inzerilli, Nicola; Nuzzo, Carmen M. A.; Vaccaro, Vanja; Vari, Sabrina; Cognetti, Francesco; Ciuffreda, Ludovica

    2015-01-01

    PTEN is the most important negative regulator of the PI3K signaling pathway. In addition to its canonical, PI3K inhibition-dependent functions, PTEN can also function as a tumor suppressor in a PI3K-independent manner. Indeed, the PTEN network regulates a broad spectrum of biological functions, modulating the flow of information from membrane-bound growth factor receptors to nuclear transcription factors, occurring in concert with other tumor suppressors and oncogenic signaling pathways. PTEN acts through its lipid and protein phosphatase activity and other non-enzymatic mechanisms. Studies conducted over the past 10 years have expanded our understanding of the biological role of PTEN, showing that in addition to its ability to regulate proliferation and cell survival, it also plays an intriguing role in regulating genomic stability, cell migration, stem cell self-renewal, and tumor microenvironment. Changes in PTEN protein levels, location, and enzymatic activity through various molecular mechanisms can generate a continuum of functional PTEN levels in inherited syndromes, sporadic cancers, and other diseases. PTEN activity can indeed, be modulated by mutations, epigenetic silencing, transcriptional repression, aberrant protein localization, and post-translational modifications. This review will discuss our current understanding of the biological role of PTEN, how PTEN expression and activity are regulated, and the consequences of PTEN dysregulation in human malignant tumors. PMID:25763354

  6. Protean PTEN: Form and Function

    PubMed Central

    Waite, Kristin A.; Eng, Charis

    2002-01-01

    Germline mutations distributed across the PTEN tumor-suppressor gene have been found to result in a wide spectrum of phenotypic features. Originally shown to be a major susceptibility gene for both Cowden syndrome (CS), which is characterized by multiple hamartomas and an increased risk of breast, thyroid, and endometrial cancers, and Bannayan-Riley-Ruvalcaba syndrome, which is characterized by lipomatosis, macrocephaly, and speckled penis, the PTEN hamartoma tumor syndrome spectrum has broadened to include Proteus syndrome and Proteus-like syndromes. Exon 5, which encodes the core motif, is a hotspot for mutations likely due to the biology of the protein. PTEN is a major lipid 3-phosphatase, which signals down the PI3 kinase/AKT pro-apoptotic pathway. Furthermore, PTEN is a protein phosphatase, with the ability to dephosphorylate both serine and threonine residues. The protein-phosphatase activity has also been shown to regulate various cell-survival pathways, such as the mitogen-activated kinase (MAPK) pathway. Although it is well established that PTEN’s lipid-phosphatase activity, via the PI3K/AKT pathway, mediates growth suppression, there is accumulating evidence that the protein-phosphatase/MAPK pathway is equally important in the mediation of growth arrest and other crucial cellular functions. PMID:11875759

  7. Identification of novel PTEN-binding partners: PTEN interaction with fatty acid binding protein FABP4.

    PubMed

    Gorbenko, O; Panayotou, G; Zhyvoloup, A; Volkova, D; Gout, I; Filonenko, V

    2010-04-01

    PTEN is a tumor suppressor with dual protein and lipid-phosphatase activity, which is frequently deleted or mutated in many human advanced cancers. Recent studies have also demonstrated that PTEN is a promising target in type II diabetes and obesity treatment. Using C-terminal PTEN sequence in pEG202-NLS as bait, yeast two-hybrid screening on Mouse Embryo, Colon Cancer, and HeLa cDNA libraries was carried out. Isolated positive clones were validated by mating assay and identified through automated DNA sequencing and BLAST database searches. Sequence analysis revealed a number of PTEN-binding proteins linking this phosphatase to a number of different signaling cascades, suggesting that PTEN may perform other functions besides tumor-suppressing activity in different cell types. In particular, the interplay between PTEN function and adipocyte-specific fatty-acid-binding protein FABP4 is of notable interest. The demonstrable tautology of PTEN to FABP4 suggested a role for this phosphatase in the regulation of lipid metabolism and adipocyte differentiation. This interaction was further studied using coimmunoprecipitation and gel-filtration assays. Finally, based on Biacore assay, we have calculated the K(D) of PTEN-FABP4 complex, which is around 2.8 microM.

  8. The mitogen-activated protein kinase (MAPK) cascade controls phosphatase and tensin homolog (PTEN) expression through multiple mechanisms.

    PubMed

    Ciuffreda, Ludovica; Di Sanza, Cristina; Cesta Incani, Ursula; Eramo, Adriana; Desideri, Marianna; Biagioni, Francesca; Passeri, Daniela; Falcone, Italia; Sette, Giovanni; Bergamo, Paola; Anichini, Andrea; Sabapathy, Kanaga; McCubrey, James A; Ricciardi, Maria Rosaria; Tafuri, Agostino; Blandino, Giovanni; Orlandi, Augusto; De Maria, Ruggero; Cognetti, Francesco; Del Bufalo, Donatella; Milella, Michele

    2012-06-01

    The mitogen-activated protein kinase (MAPK) and PI3K pathways are regulated by extensive crosstalk, occurring at different levels. In tumors, transactivation of the alternate pathway is a frequent "escape" mechanism, suggesting that combined inhibition of both pathways may achieve synergistic antitumor activity. Here we show that, in the M14 melanoma model, simultaneous inhibition of both MEK and mammalian target of rapamycin (mTOR) achieves synergistic effects at suboptimal concentrations, but becomes frankly antagonistic in the presence of relatively high concentrations of MEK inhibitors. This observation led to the identification of a novel crosstalk mechanism, by which either pharmacologic or genetic inhibition of constitutive MEK signaling restores phosphatase and tensin homolog (PTEN) expression, both in vitro and in vivo, and inhibits downstream signaling through AKT and mTOR, thus bypassing the need for double pathway blockade. This appears to be a general regulatory mechanism and is mediated by multiple mechanisms, such as MAPK-dependent c-Jun and miR-25 regulation. Finally, PTEN upregulation appears to be a major effector of MEK inhibitors' antitumor activity, as cancer cells in which PTEN is inactivated are consistently more resistant to the growth inhibitory and anti-angiogenic effects of MEK blockade. PMID:22215152

  9. Tailor-Made Protein Tyrosine Phosphatases: In Vitro Site-Directed Mutagenesis of PTEN and PTPRZ-B.

    PubMed

    Luna, Sandra; Mingo, Janire; Aurtenetxe, Olaia; Blanco, Lorena; Amo, Laura; Schepens, Jan; Hendriks, Wiljan J; Pulido, Rafael

    2016-01-01

    In vitro site-directed mutagenesis (SDM) of protein tyrosine phosphatases (PTPs) is a commonly used approach to experimentally analyze PTP functions at the molecular and cellular level and to establish functional correlations with PTP alterations found in human disease. Here, using the tumor-suppressor PTEN and the receptor-type PTPRZ-B (short isoform from PTPRZ1 gene) phosphatases as examples, we provide a brief insight into the utility of specific mutations in the experimental analysis of PTP functions. We describe a standardized, rapid, and simple method of mutagenesis to perform single and multiple amino acid substitutions, as well as deletions of short nucleotide sequences, based on one-step inverse PCR and DpnI restriction enzyme treatment. This method of SDM is generally applicable to any other protein of interest. PMID:27514801

  10. PTEN inhibitors: an evaluation of current compounds.

    PubMed

    Spinelli, Laura; Lindsay, Yvonne E; Leslie, Nicholas R

    2015-01-01

    Small molecule inhibitors of many classes of enzymes, including phosphatases, have widespread use as experimental tools and as therapeutics. Efforts to develop inhibitors against the lipid phosphatase and tumour suppressor, PTEN, was for some time limited by concerns that their use as therapy could result in increased risk of cancer. However, the accumulation of evidence that short term PTEN inhibition may be valuable in conditions such as nerve injury has raised interest. Here we investigate the inhibition of PTEN by four available PTEN inhibitors, bpV(phen), bpV(pic), VO-OHpic and SF1670 and compared this inhibition with that of only 3 other related enzymes, the tyrosine phosphatase SHP1 and the phosphoinositide phosphatases INPP4A and INPP4B. Even with this very small number of comparators, for all compounds, inhibition of multiple enzymes was observed and with all three vanadate compounds, this was similar or more potent than the inhibition of PTEN. In particular, the bisperoxovanadate compounds were found to inhibit PTEN poorly in the presence of reducing agents including the cellular redox buffer glutathione.

  11. PTEN modulates EGFR late endocytic trafficking and degradation by dephosphorylating Rab7

    PubMed Central

    Shinde, Swapnil Rohidas; Maddika, Subbareddy

    2016-01-01

    Tumour suppressor phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a lipid phosphatase that negatively regulates growth factor-induced survival signalling. Here, we demonstrate that PTEN attenuates epidermal growth factor receptor (EGFR) signalling by promoting late endosome maturation by virtue of its protein phosphatase activity. Loss of PTEN impairs the transition of ligand-bound EGFR from early to late endosomes. We unveil Rab7, a critical GTPase for endosome maturation, as a functional PTEN interacting partner. PTEN dephosphorylates Rab7 on two conserved residues S72 and Y183, which are necessary for GDP dissociation inhibitor (GDI)-dependent recruitment of Rab7 on to late endosomes and subsequent maturation. Thus, our findings reveal PTEN-dependent endosome maturation through phosphoregulation of Rab7 as an important route of controlling EGFR signalling. PMID:26869029

  12. PTEN modulates EGFR late endocytic trafficking and degradation by dephosphorylating Rab7.

    PubMed

    Shinde, Swapnil Rohidas; Maddika, Subbareddy

    2016-01-01

    Tumour suppressor phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a lipid phosphatase that negatively regulates growth factor-induced survival signalling. Here, we demonstrate that PTEN attenuates epidermal growth factor receptor (EGFR) signalling by promoting late endosome maturation by virtue of its protein phosphatase activity. Loss of PTEN impairs the transition of ligand-bound EGFR from early to late endosomes. We unveil Rab7, a critical GTPase for endosome maturation, as a functional PTEN interacting partner. PTEN dephosphorylates Rab7 on two conserved residues S72 and Y183, which are necessary for GDP dissociation inhibitor (GDI)-dependent recruitment of Rab7 on to late endosomes and subsequent maturation. Thus, our findings reveal PTEN-dependent endosome maturation through phosphoregulation of Rab7 as an important route of controlling EGFR signalling. PMID:26869029

  13. Cdh1, a Substrate-recruiting Component of Anaphase-promoting Complex/Cyclosome (APC/C) Ubiquitin E3 Ligase, Specifically Interacts with Phosphatase and Tensin Homolog (PTEN) and Promotes Its Removal from Chromatin*

    PubMed Central

    Choi, Byeong Hyeok; Pagano, Michele; Huang, Chaunshu; Dai, Wei

    2014-01-01

    A pool of PTEN localizes to the nucleus. However, the exact mechanism by which nuclear PTEN is regulated remains unclear. We have recently reported that Plk1 specifically phosphorylates PTEN on Ser-380 during mitosis. Here we report that PTEN also localized to chromatin and that chromatin PTEN was removed by a proteasome-dependent process during mitotic exit. Pulldown analysis revealed that Cdh1, but not Cdc20, was significantly associated with PTEN. Cdh1 interacted with PTEN via two separate domains, and their interaction was enhanced by MG132, a proteasome inhibitor. Cdh1 negatively controlled the stability of chromatin PTEN by polyubiquitination. Phosphorylation of PTEN on Ser-380 impaired its interaction with Cdh1, thus positively regulating PTEN stability on chromatin. Significantly, the PTEN interaction with Cdh1 was phosphatase-independent, and Cdh1 knockdown via RNAi led to significant accumulation of chromatin PTEN, delaying mitotic exit. Combined, our studies identify Cdh1 as an important regulator of nuclear/chromatin PTEN during mitosis. PMID:24811168

  14. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) reduces vascular endothelial growth factor expression in allergen-induced airway inflammation.

    PubMed

    Lee, Kyung Sun; Kim, So Ri; Park, Seoung Ju; Lee, Ho Kyung; Park, Hee Sun; Min, Kyung Hoon; Jin, Sun Mi; Lee, Yong Chul

    2006-06-01

    Vascular endothelial growth factor (VEGF) plays a pivotal role in the pathogenesis of bronchial asthma. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has been implicated in regulating cell survival signaling through the phosphoinositide 3-kinase (PI3K)/Akt pathway. The key role of PI3K in VEGF-mediated signal transduction is established. However, the effects of PTEN on VEGF-mediated signaling in asthma are unknown. This study aimed to determine the effect of PI3K inhibitors and PTEN on VEGF expression in allergen-induced airway inflammation. We have used a female C57BL/6 mouse model for asthma to determine the role of PTEN in allergen-induced airway inflammation, specifically in the expression of VEGF. Allergen-induced airway inflammation leads to increased activity of PI3K in lung tissue. These mice develop the following typical pathophysiological features of asthma in the lungs: increased numbers of inflammatory cells of the airways; airway hyper-responsiveness; increased expression of interleukin (IL)-4, IL-5, IL-13, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, regulated on activation normal T cell expressed and secreted (RANTES), and eotaxin; increased vascular permeability; and increased levels of VEGF. Administration of PI3K inhibitors or adenoviruses carrying PTEN cDNA reduced the symptoms of asthma and decreased the increased levels of plasma extravasation and VEGF in allergen-induced asthmatic lungs. These results indicate that PTEN reduces VEGF expression in allergen-induced airway inflammation.

  15. PNUTS functions as a proto-oncogene by sequestering PTEN.

    PubMed

    Kavela, Sridhar; Shinde, Swapnil R; Ratheesh, Raman; Viswakalyan, Kotapalli; Bashyam, Murali D; Gowrishankar, Swarnalata; Vamsy, Mohana; Pattnaik, Sujit; Rao, Subramanyeshwar; Sastry, Regulagadda A; Srinivasulu, Mukta; Chen, Junjie; Maddika, Subbareddy

    2013-01-01

    PTEN is a well-defined tumor suppressor gene that antagonizes the PI3K/Akt pathway to regulate a multitude of cellular processes, such as survival, growth, motility, invasiveness, and angiogenesis. While the functions of PTEN have been studied extensively, the regulation of its activity during normal and disease conditions still remains incompletely understood. In this study, we identified the protein phosphatase-1 nuclear targeting subunit PNUTS (PPP1R10) as a PTEN-associated protein. PNUTS directly interacted with the lipid-binding domain (C2 domain) of PTEN and sequestered it in the nucleus. Depletion of PNUTS leads to increased apoptosis and reduced cellular proliferation in a PTEN-dependent manner. PNUTS expression was elevated in certain cancers compared with matched normal tissues. Collectively, our studies reveal PNUTS as a novel PTEN regulator and a likely oncogene.

  16. PNUTS functions as a proto-oncogene by sequestering PTEN

    PubMed Central

    Kavela, Sridhar; Shinde, Swapnil R; Ratheesh, Raman; Viswakalyan, Kotapalli; Bashyam, Murali D; Gowrishankar, Swarnalata; Vamsy, Mohana; Pattnaik, Sujit; Rao, Subramanyeshwar; Sastry, Regulagadda A; Srinivasulu, Mukta; Chen, Junjie; Maddika, Subbareddy

    2012-01-01

    PTEN is a well-defined tumor suppressor gene that antagonizes the PI3K/Akt pathway to regulate a multitude of cellular processes such as survival, growth, motility, invasiveness and angiogenesis. While the functions of PTEN have been studied extensively, the regulation of its activity during normal and disease conditions still remains incompletely understood. In this study, we identified the protein phosphatase-1 nuclear targeting subunit PNUTS (PPP1R10) as a PTEN associated protein. PNUTS directly interacted with the lipid-binding domain (C2 domain) of PTEN and sequestered it in the nucleus. Depletion of PNUTS leads to increased apoptosis and reduced cellular proliferation in a PTEN-dependent manner. PNUTS expression was elevated in certain cancers compared to matched normal tissues. Collectively, our studies reveal PNUTS as a novel PTEN regulator and a likely oncogene. PMID:23117887

  17. Selective deletion of Pten in pancreatic beta cells leads to increased islet mass and resistance to STZ-induced diabetes.

    PubMed

    Stiles, Bangyan L; Kuralwalla-Martinez, Christine; Guo, Wei; Gregorian, Caroline; Wang, Ying; Tian, Jide; Magnuson, Mark A; Wu, Hong

    2006-04-01

    Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a lipid phosphatase. PTEN inhibits the action of phosphatidylinositol-3-kinase and reduces the levels of phosphatidylinositol triphosphate, a crucial second messenger for cell proliferation and survival, as well as insulin signaling. In this study, we deleted Pten specifically in the insulin producing beta cells during murine pancreatic development. Pten deletion leads to increased cell proliferation and decreased cell death, without significant alteration of beta-cell differentiation. Consequently, the mutant pancreas generates more and larger islets, with a significant increase in total beta-cell mass. PTEN loss also protects animals from developing streptozotocin-induced diabetes. Our data demonstrate that PTEN loss in beta cells is not tumorigenic but beneficial. This suggests that modulating the PTEN-controlled signaling pathway is a potential approach for beta-cell protection and regeneration therapies. PMID:16537919

  18. Selective deletion of Pten in pancreatic beta cells leads to increased islet mass and resistance to STZ-induced diabetes.

    PubMed

    Stiles, Bangyan L; Kuralwalla-Martinez, Christine; Guo, Wei; Gregorian, Caroline; Wang, Ying; Tian, Jide; Magnuson, Mark A; Wu, Hong

    2006-04-01

    Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a lipid phosphatase. PTEN inhibits the action of phosphatidylinositol-3-kinase and reduces the levels of phosphatidylinositol triphosphate, a crucial second messenger for cell proliferation and survival, as well as insulin signaling. In this study, we deleted Pten specifically in the insulin producing beta cells during murine pancreatic development. Pten deletion leads to increased cell proliferation and decreased cell death, without significant alteration of beta-cell differentiation. Consequently, the mutant pancreas generates more and larger islets, with a significant increase in total beta-cell mass. PTEN loss also protects animals from developing streptozotocin-induced diabetes. Our data demonstrate that PTEN loss in beta cells is not tumorigenic but beneficial. This suggests that modulating the PTEN-controlled signaling pathway is a potential approach for beta-cell protection and regeneration therapies.

  19. Identification of nucleolus-localized PTEN and its function in regulating ribosome biogenesis.

    PubMed

    Li, Pingdong; Wang, Danni; Li, Haiyang; Yu, Zhenkun; Chen, Xiaohong; Fang, Jugao

    2014-10-01

    The tumor suppressor PTEN is a lipid phosphatase that is found mutated in different types of human cancers. PTEN suppresses cell proliferation by inhibiting the PI3K-Akt signaling pathway at the cell membrane. However, PTEN is also demonstrated to localize in the cell nucleus where it exhibits tumor suppressive activity via a different, unknown mechanism. In this study we report that PTEN also localizes to the nucleolus and that nucleolar PTEN plays an important role in regulating nucleolar homeostasis and maintaining nucleolar morphology. Overexpression of nuclear PTEN in PTEN null cells inhibits Akt phosphorylation and reduces cell size. Knockdown of PTEN in PTEN positive cells leads to nucleolar morphologic changes and an increase in the proportion of cells with a greater number of nucleoli. In addition, knockdown of PTEN in PTEN positive cells increased ribosome biogenesis. These findings expand current understanding of function and relevance of nuclear localized PTEN and provide a foundation for the development of novel therapies targeting PTEN.

  20. Phosphatase and tensin homolog (PTEN) gene mutations and autism: literature review and a case report of a patient with Cowden syndrome, autistic disorder, and epilepsy.

    PubMed

    Conti, Sara; Condò, Maria; Posar, Annio; Mari, Francesca; Resta, Nicoletta; Renieri, Alessandra; Neri, Iria; Patrizi, Annalisa; Parmeggiani, Antonia

    2012-03-01

    Phosphatase and tensin homolog (PTEN) gene mutations are associated with a spectrum of clinical disorders characterized by skin lesions, macrocephaly, hamartomatous overgrowth of tissues, and an increased risk of cancers. Autism has rarely been described in association with these variable clinical features. At present, 24 patients with phosphatase and tensin homolog gene mutation, autism, macrocephaly, and some clinical findings described in phosphatase and tensin homolog syndromes have been reported in the literature. We describe a 14-year-old boy with autistic disorder, focal epilepsy, severe and progressive macrocephaly, and multiple papular skin lesions and palmoplantar punctate keratoses, characteristic of Cowden syndrome. The boy has a de novo phosphatase and tensin homolog gene mutation. Our patient is the first case described to present a typical Cowden syndrome and autism associated with epilepsy.

  1. TPIP: a novel phosphoinositide 3-phosphatase.

    PubMed Central

    Walker, S M; Downes, C P; Leslie, N R

    2001-01-01

    The PTEN (phosphatase and tensin homologue deleted on chromosome 10) tumour suppressor is a phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P(3)] 3-phosphatase that plays a critical role in regulating many cellular processes by antagonizing the phosphoinositide 3-kinase signalling pathway. We have identified and characterized two human homologues of PTEN, which differ with respect to their subcellular localization and lipid phosphatase activities. The previously cloned, but uncharacterized, TPTE (transmembrane phosphatase with tensin homology) is localized to the plasma membrane, but lacks detectable phosphoinositide 3-phosphatase activity. TPIP (TPTE and PTEN homologous inositol lipid phosphatase) is a novel phosphatase that occurs in several differentially spliced forms of which two, TPIP alpha and TPIP beta, appear to be functionally distinct. TPIP alpha displays similar phosphoinositide 3-phosphatase activity compared with PTEN against PtdIns(3,4,5)P(3), PtdIns(3,5)P(2), PtdIns(3,4)P(2) and PtdIns(3)P, has N-terminal transmembrane domains and appears to be localized on the endoplasmic reticulum. This is unusual as most signalling-lipid-metabolizing enzymes are not integral membrane proteins. TPIP beta, however, lacks detectable phosphatase activity and is cytosolic. TPIP has a wider tissue distribution than the testis-specific TPTE, with specific splice variants being expressed in testis, brain and stomach. TPTE and TPIP do not appear to be functional orthologues of the Golgi-localized and more distantly related murine PTEN2. We suggest that TPIP alpha plays a role in regulating phosphoinositide signalling on the endoplasmic reticulum, and might also represent a tumour suppressor and functional homologue of PTEN in some tissues. PMID:11716755

  2. A comprehensive functional analysis of PTEN mutations: implications in tumor- and autism-related syndromes.

    PubMed

    Rodríguez-Escudero, Isabel; Oliver, María D; Andrés-Pons, Amparo; Molina, María; Cid, Víctor J; Pulido, Rafael

    2011-11-01

    The PTEN (phosphatase and tensin homolog) phosphatase is unique in mammals in terms of its tumor suppressor activity, exerted by dephosphorylation of the lipid second messenger PIP(3) (phosphatidylinositol 3,4,5-trisphosphate), which activates the phosphoinositide 3-kinase/Akt/mTOR (mammalian target of rapamycin) oncogenic pathway. Loss-of-function mutations in the PTEN gene are frequent in human cancer and in the germline of patients with PTEN hamartoma tumor-related syndromes (PHTSs). In addition, PTEN is mutated in patients with autism spectrum disorders (ASDs), although no functional information on these mutations is available. Here, we report a comprehensive in vivo functional analysis of human PTEN using a heterologous yeast reconstitution system. Ala-scanning mutagenesis at the catalytic loops of PTEN outlined the critical role of residues within the P-catalytic loop for PIP(3) phosphatase activity in vivo. PTEN mutations that mimic the P-catalytic loop of mammalian PTEN-like proteins (TPTE, TPIP, tensins and auxilins) affected PTEN function variably, whereas tumor- or PHTS-associated mutations targeting the PTEN P-loop produced complete loss of function. Conversely, Ala-substitutions, as well as tumor-related mutations at the WPD- and TI-catalytic loops, displayed partial activity in many cases. Interestingly, a tumor-related D92N mutation was partially active, supporting the notion that the PTEN Asp92 residue might not function as the catalytic general acid. The analysis of a panel of ASD-associated hereditary PTEN mutations revealed that most of them did not substantially abrogate PTEN activity in vivo, whereas most of PHTS-associated mutations did. Our findings reveal distinctive functional patterns among PTEN mutations found in tumors and in the germline of PHTS and ASD patients, which could be relevant for therapy.

  3. PTEN posttranslational inactivation and hyperactivation of the PI3K/Akt pathway sustain primary T cell leukemia viability

    PubMed Central

    Silva, Ana; Yunes, J. Andrés; Cardoso, Bruno A.; Martins, Leila R.; Jotta, Patrícia Y.; Abecasis, Miguel; Nowill, Alexandre E.; Leslie, Nick R.; Cardoso, Angelo A.; Barata, Joao T.

    2008-01-01

    Mutations in the phosphatase and tensin homolog (PTEN) gene leading to PTEN protein deletion and subsequent activation of the PI3K/Akt signaling pathway are common in cancer. Here we show that PTEN inactivation in human T cell acute lymphoblastic leukemia (T-ALL) cells is not always synonymous with PTEN gene lesions and diminished protein expression. Samples taken from patients with T-ALL at the time of diagnosis very frequently showed constitutive hyperactivation of the PI3K/Akt pathway. In contrast to immortalized cell lines, most primary T-ALL cells did not harbor PTEN gene alterations, displayed normal PTEN mRNA levels, and expressed higher PTEN protein levels than normal T cell precursors. However, PTEN overexpression was associated with decreased PTEN lipid phosphatase activity, resulting from casein kinase 2 (CK2) overexpression and hyperactivation. In addition, T-ALL cells had constitutively high levels of ROS, which can also downmodulate PTEN activity. Accordingly, both CK2 inhibitors and ROS scavengers restored PTEN activity and impaired PI3K/Akt signaling in T-ALL cells. Strikingly, inhibition of PI3K and/or CK2 promoted T-ALL cell death without affecting normal T cell precursors. Overall, our data indicate that T-ALL cells inactivate PTEN mostly in a nondeletional, posttranslational manner. Pharmacological manipulation of these mechanisms may open new avenues for T-ALL treatment. PMID:18830414

  4. Hematopoietic Stem Cell Activity Is Regulated by Pten Phosphorylation Through a Niche-Dependent Mechanism.

    PubMed

    Li, Jing; Zhang, Jun; Tang, Minghui; Xin, Junping; Xu, Yan; Volk, Andrew; Hao, Caiqin; Hu, Chenglong; Sun, Jiewen; Wei, Wei; Cao, Quichan; Breslin, Peter; Zhang, Jiwang

    2016-08-01

    The phosphorylated form of Pten (p-Pten) is highly expressed in >70% of acute myeloid leukemia samples. However, the role of p-Pten in normal and abnormal hematopoiesis has not been studied. We found that Pten protein levels are comparable among long-term (LT) hematopoietic stem cells (HSCs), short-term (ST) HSCs, and multipotent progenitors (MPPs); however, the levels of p-Pten are elevated during the HSC-to-MPP transition. To study whether p-Pten is involved in regulating self-renewal and differentiation in HSCs, we compared the effects of overexpression of p-Pten and nonphosphorylated Pten (non-p-Pten) on the hematopoietic reconstitutive capacity (HRC) of HSCs. We found that overexpression of non-p-Pten enhances the LT-HRC of HSCs, whereas overexpression of p-Pten promotes myeloid differentiation and compromises the LT-HRC of HSCs. Such phosphorylation-regulated Pten functioning is mediated by repressing the cell:cell contact-induced activation of Fak/p38 signaling independent of Pten's lipid phosphatase activity because both p-Pten and non-p-Pten have comparable activity in repressing PI3K/Akt signaling. Our studies suggest that, in addition to repressing PI3K/Akt/mTor signaling, non-p-Pten maintains HSCs in bone marrow niches via a cell-contact inhibitory mechanism by inhibiting Fak/p38 signaling-mediated proliferation and differentiation. In contrast, p-Pten promotes the proliferation and differentiation of HSCs by enhancing the cell contact-dependent activation of Src/Fak/p38 signaling. Stem Cells 2016;34:2130-2144.

  5. Hematopoietic Stem Cell Activity Is Regulated by Pten Phosphorylation Through a Niche-Dependent Mechanism.

    PubMed

    Li, Jing; Zhang, Jun; Tang, Minghui; Xin, Junping; Xu, Yan; Volk, Andrew; Hao, Caiqin; Hu, Chenglong; Sun, Jiewen; Wei, Wei; Cao, Quichan; Breslin, Peter; Zhang, Jiwang

    2016-08-01

    The phosphorylated form of Pten (p-Pten) is highly expressed in >70% of acute myeloid leukemia samples. However, the role of p-Pten in normal and abnormal hematopoiesis has not been studied. We found that Pten protein levels are comparable among long-term (LT) hematopoietic stem cells (HSCs), short-term (ST) HSCs, and multipotent progenitors (MPPs); however, the levels of p-Pten are elevated during the HSC-to-MPP transition. To study whether p-Pten is involved in regulating self-renewal and differentiation in HSCs, we compared the effects of overexpression of p-Pten and nonphosphorylated Pten (non-p-Pten) on the hematopoietic reconstitutive capacity (HRC) of HSCs. We found that overexpression of non-p-Pten enhances the LT-HRC of HSCs, whereas overexpression of p-Pten promotes myeloid differentiation and compromises the LT-HRC of HSCs. Such phosphorylation-regulated Pten functioning is mediated by repressing the cell:cell contact-induced activation of Fak/p38 signaling independent of Pten's lipid phosphatase activity because both p-Pten and non-p-Pten have comparable activity in repressing PI3K/Akt signaling. Our studies suggest that, in addition to repressing PI3K/Akt/mTor signaling, non-p-Pten maintains HSCs in bone marrow niches via a cell-contact inhibitory mechanism by inhibiting Fak/p38 signaling-mediated proliferation and differentiation. In contrast, p-Pten promotes the proliferation and differentiation of HSCs by enhancing the cell contact-dependent activation of Src/Fak/p38 signaling. Stem Cells 2016;34:2130-2144. PMID:27096933

  6. The PTEN tumor suppressor gene and its role in lymphoma pathogenesis

    PubMed Central

    Wang, Xiaoxiao; Huang, Huiqiang; Young, Ken H.

    2015-01-01

    The phosphatase and tensin homolog gene PTEN is one of the most frequently mutated tumor suppressor genes in human cancer. Loss of PTEN function occurs in a variety of human cancers via its mutation, deletion, transcriptional silencing, or protein instability. PTEN deficiency in cancer has been associated with advanced disease, chemotherapy resistance, and poor survival. Impaired PTEN function, which antagonizes phosphoinositide 3-kinase (PI3K) signaling, causes the accumulation of phosphatidylinositol (3,4,5)-triphosphate and thereby the suppression of downstream components of the PI3K pathway, including the protein kinase B and mammalian target of rapamycin kinases. In addition to having lipid phosphorylation activity, PTEN has critical roles in the regulation of genomic instability, DNA repair, stem cell self-renewal, cellular senescence, and cell migration. Although PTEN deficiency in solid tumors has been studied extensively, rare studies have investigated PTEN alteration in lymphoid malignancies. However, genomic or epigenomic aberrations of PTEN and dysregulated signaling are likely critical in lymphoma pathogenesis and progression. This review provides updated summary on the role of PTEN deficiency in human cancers, specifically in lymphoid malignancies; the molecular mechanisms of PTEN regulation; and the distinct functions of nuclear PTEN. Therapeutic strategies for rescuing PTEN deficiency in human cancers are proposed. PMID:26655726

  7. Plk1 Protein Phosphorylates Phosphatase and Tensin Homolog (PTEN) and Regulates Its Mitotic Activity during the Cell Cycle*

    PubMed Central

    Choi, Byeong Hyeok; Pagano, Michele; Dai, Wei

    2014-01-01

    PTEN is a well known tumor suppressor through the negative regulation of the PI3K signaling pathway. Here we report that PTEN plays an important role in regulating mitotic timing, which is associated with increased PTEN phosphorylation in the C-terminal tail and its localization to chromatin. Pulldown analysis revealed that Plk1 physically interacted with PTEN. Biochemical studies showed that Plk1 phosphorylates PTEN in vitro in a concentration-dependent manner and that the phosphorylation was inhibited by Bi2635, a Plk1-specific inhibitor. Deletional and mutational analyses identified that Plk1 phosphorylated Ser-380, Thr-382, and Thr-383, but not Ser-385, a cluster of residues known to affect the PTEN stability. Interestingly, a combination of molecular and genetic analyses revealed that only Ser-380 was significantly phosphorylated in vivo and that Plk1 regulated the phosphorylation, which was associated with the accumulation of PTEN on chromatin. Moreover, expression of phospho-deficient mutant, but not wild-type PTEN, caused enhanced mitotic exit. Taken together, our studies identify Plk1 as an important regulator of PTEN during the cell cycle. PMID:24706748

  8. MicroRNA-214 Inhibits Left Ventricular Remodeling in an Acute Myocardial Infarction Rat Model by Suppressing Cellular Apoptosis via the Phosphatase and Tensin Homolog (PTEN).

    PubMed

    Yang, Xingwei; Qin, Yanjun; Shao, Suxia; Yu, Yueqing; Zhang, Chongyang; Dong, Hua; Lv, Guangwei; Dong, Shimin

    2016-01-01

    The aims of the present study were to determine the role of miR-214 on left ventricular remodeling of rat heart with acute myocardial infarction (AMI) and to further investigate the underlying mechanism of miR-214-mediated myocardial protection. AMI was induced in which adenovirus-expressing miR-214 (Ad-miR-214), anti-miR-214, or Ad-GFP had been delivered into rats hearts 4 days prior, while a phosphatase and tensin homolog (PTEN) inhibitor was administered via intra-peritoneal injection 30 minutes prior to AMI. Changes in hemodynamic parameters were detected and recorded. Left ventricular (LV) dimensions and LV/BW were measured. Quantitative RT-PCR was used to determine the miR-214 expression levels of the myocytes in the infarcted, border, and non-infarcted areas of the LV. Myocardial infarct size was also measured. Flow cytometry analysis was performed to examine cellular apoptosis. Western blot analysis was performed to examine PTEN expression. The results showed that miR-214 was upregulated in both border and infarcted areas. Myocardial cell apoptosis was decreased in the Ad-miR-214 group, but was increased in the anti-miR-214 group, while there were no differences among the Ad-GFP-group, PTEN-ad-miR-214 group, or PTEN-anti-miR-214 group. Myocardial infarct size, LV dimensions, heart rate (HR), and LV end-diastolic pressure (LVEDP) were decreased while the maximal rates of rise or decline in blood pressure in the ventricular chamber (± dp/dt) and LV systolic pressure (LVSP) were increased in the Ad-miR-214 group, all of which exhibited opposite changes in the anti-miR-214 group. PTEN was downregulated in the Ad-miR-214 group and upregulated in the anti-miR-214 group. PTEN was decreased in both the border and infarcted areas compared with non-infarcted areas. The study results suggest that Ad-miR-214 improves LV remodeling and decreases the apoptosis of myocardial cells through PTEN, suggesting a possible mechanism by which Ad-miR-214 functions in protecting

  9. PTEN mediates Notch-dependent stalk cell arrest in angiogenesis.

    PubMed

    Serra, Helena; Chivite, Iñigo; Angulo-Urarte, Ana; Soler, Adriana; Sutherland, James D; Arruabarrena-Aristorena, Amaia; Ragab, Anan; Lim, Radiance; Malumbres, Marcos; Fruttiger, Marcus; Potente, Michael; Serrano, Manuel; Fabra, Àngels; Viñals, Francesc; Casanovas, Oriol; Pandolfi, Pier Paolo; Bigas, Anna; Carracedo, Arkaitz; Gerhardt, Holger; Graupera, Mariona

    2015-07-31

    Coordinated activity of VEGF and Notch signals guides the endothelial cell (EC) specification into tip and stalk cells during angiogenesis. Notch activation in stalk cells leads to proliferation arrest via an unknown mechanism. By using gain- and loss-of-function gene-targeting approaches, here we show that PTEN is crucial for blocking stalk cell proliferation downstream of Notch, and this is critical for mouse vessel development. Endothelial deletion of PTEN results in vascular hyperplasia due to a failure to mediate Notch-induced proliferation arrest. Conversely, overexpression of PTEN reduces vascular density and abrogates the increase in EC proliferation induced by Notch blockade. PTEN is a lipid/protein phosphatase that also has nuclear phosphatase-independent functions. We show that both the catalytic and non-catalytic APC/C-Fzr1/Cdh1-mediated activities of PTEN are required for stalk cells' proliferative arrest. These findings define a Notch-PTEN signalling axis as an orchestrator of vessel density and implicate the PTEN-APC/C-Fzr1/Cdh1 hub in angiogenesis.

  10. Dysregulation of AKT Pathway by SMYD2-Mediated Lysine Methylation on PTEN.

    PubMed

    Nakakido, Makoto; Deng, Zhenzhong; Suzuki, Takehiro; Dohmae, Naoshi; Nakamura, Yusuke; Hamamoto, Ryuji

    2015-04-01

    Phosphatase and tensin homologue (PTEN), one of the well-characterized tumor suppressor proteins, counteracts the phosphatidylinositol 3-kinase-AKT pathway through its unique lipid phosphatase activity. The functions of PTEN are regulated by a variety of posttranslational modifications such as acetylation, oxidation, ubiquitylation, phosphorylation, and SUMOylation. However, methylation of PTEN has not been reported so far. In this study, we demonstrated that the oncogenic protein lysine methyltransferase SET and MYND domain containing 2 (SMYD2) methylates PTEN at lysine 313 in vitro and in vivo. Knockdown of SMYD2 suppressed the cell growth of breast cancer cells and attenuated phosphorylation levels of AKT, indicating that SMYD2-mediated methylation negatively regulates PTEN tumor suppressor activity and results in activation of the phosphatidylinositol 3-kinase-AKT pathway. Furthermore, PTEN protein with lysine 313 substitution diminished phosphorylation of PTEN at serine 380, which is known to inactivate tumor suppressor functions of PTEN. Taken together, our findings unveil a novel mechanism of PTEN dysregulation regulated by lysine methylation in human cancer. PMID:25925379

  11. Comparative phytohormone profiles, lipid kinase and lipid phosphatase activities in barley aleurone, coleoptile, and root tissues.

    PubMed

    Meringer, Maria V; Villasuso, Ana L; Pasquaré, Susana J; Giusto, Norma M; Machado, Estela E; Racagni, Graciela E

    2012-09-01

    We analyzed lipid kinase and lipid phosphatase activities and determined endogenous phytohormone levels by liquid chromatography-tandem mass spectrometry in root and coleoptile tissues following germination of barley (Hordeum vulgare) seeds. The enzymes showing highest activity in aleurone cells were diacylglycerol kinase (DAG-k, EC 2.7.1.107) and phosphatidate kinase (PA-k). The ratio of gibberellins (GAs) to abscisic acid (ABA) was 2-fold higher in aleurone than in coleoptile or root tissues. In coleoptiles, phosphatidylinositol 4-kinase (PI4-k, EC 2.7.1.67) showed the highest enzyme activity, and jasmonic acid (JA) level was higher than in aleurone. In roots, activities of PI4-k, DAG-k, and PA-k were similar, and salicylic acid (SA) showed the highest concentration. In the assays to evaluate the hydrolysis of DGPP (diacylglycerol pyrophosphate) and PA (phosphatidic acid) we observed that PA hydrolysis by LPPs (lipid phosphate phosphatases) was not modified; however, the diacylglycerol pyrophosphate phosphatase (DGPPase) was strikingly higher in coleoptile and root tissues than to aleurone. Relevance of these findings in terms of signaling responses and seedling growth is discussed.

  12. Lipid phosphate phosphatases regulate lysophosphatidic acid production and signaling in platelets: studies using chemical inhibitors of lipid phosphate phosphatase activity.

    PubMed

    Smyth, Susan S; Sciorra, Vicki A; Sigal, Yury J; Pamuklar, Zehra; Wang, Zuncai; Xu, Yong; Prestwich, Glenn D; Morris, Andrew J

    2003-10-31

    Blood platelets play an essential role in ischemic heart disease and stroke contributing to acute thrombotic events by release of potent inflammatory agents within the vasculature. Lysophosphatidic acid (LPA) is a bioactive lipid mediator produced by platelets and found in the blood and atherosclerotic plaques. LPA receptors on platelets, leukocytes, endothelial cells, and smooth muscle cells regulate growth, differentiation, survival, motility, and contractile activity. Definition of the opposing pathways of synthesis and degradation that control extracellular LPA levels is critical to understanding how LPA bioactivity is regulated. We show that intact platelets and platelet membranes actively dephosphorylate LPA and identify the major enzyme responsible as lipid phosphate phosphatase 1 (LPP1). Localization of LPP1 to the platelet surface is increased by exposure to LPA. A novel receptor-inactive sn-3-substituted difluoromethylenephosphonate analog of phosphatidic acid that is a potent competitive inhibitor of LPP1 activity potentiates platelet aggregation and shape change responses to LPA and amplifies LPA production by agonist-stimulated platelets. Our results identify LPP1 as a pivotal regulator of LPA signaling in the cardiovascular system. These findings are consistent with genetic and cell biological evidence implicating LPPs as negative regulators of lysophospholipid signaling and suggest that the mechanisms involve both attenuation of lysophospholipid actions at cell surface receptors and opposition of lysophospholipid production. PMID:12909631

  13. Association between TLR4 and PTEN Involved in LPS-TLR4 Signaling Response.

    PubMed

    Yin, Huahua; Tan, Yan; Wu, Xiaofeng; Yan, Hong; Liu, Feng; Yao, Yuanzhang; Jiang, Jianxin; Wan, Qi; Li, Lei

    2016-01-01

    In this study, we explored the potential mechanisms of how PTEN regulating LPS induced TLR4 signaling pathway. The initial findings from ELISA demonstrate that PTEN influences TNF-α secretion by its lipid phosphatase activity. Subsequently, western blot, immunoprecipitation assay, and immunofluorescence were performed to explore the activation process of PTEN by stimulation with LPS. As early as 20 minutes after LPS stimulation, reduced phosphorylation of PTEN was found obviously. Accordingly, the whole cell-scattered PTEN translocated towards the cell membrane 20 minutes after stimulating with LPS. Moreover, the weak physical association between PTEN and TLR4 in resting RAW264.7 cells increased gradually after the stimulation of LPS. Furthermore, our study showed PTEN decreased LPS-induced Akt activity and upregulated NF-κB-dependent gene transcription, identifying indirectly that the PTEN could regulate the activation of NF-κB by its downstream Akt kinase. In summary, our study illustrates the potential signal transduction process of PTEN while stimulated by LPS: by increasing the association of TLR4, PTEN recruits to its phosphoinositide substrate PI(3,4,5)P3 located on the cell membrane and exerts its dephosphorylated function and subsequently depresses the activity of downstream molecule Akt and results in activation of NF-κB, followed by the secretion of inflammatory mediators TNF-α. PMID:27563672

  14. Association between TLR4 and PTEN Involved in LPS-TLR4 Signaling Response

    PubMed Central

    Yin, Huahua; Tan, Yan; Wu, Xiaofeng; Yan, Hong; Liu, Feng; Yao, Yuanzhang; Jiang, Jianxin; Wan, Qi

    2016-01-01

    In this study, we explored the potential mechanisms of how PTEN regulating LPS induced TLR4 signaling pathway. The initial findings from ELISA demonstrate that PTEN influences TNF-α secretion by its lipid phosphatase activity. Subsequently, western blot, immunoprecipitation assay, and immunofluorescence were performed to explore the activation process of PTEN by stimulation with LPS. As early as 20 minutes after LPS stimulation, reduced phosphorylation of PTEN was found obviously. Accordingly, the whole cell-scattered PTEN translocated towards the cell membrane 20 minutes after stimulating with LPS. Moreover, the weak physical association between PTEN and TLR4 in resting RAW264.7 cells increased gradually after the stimulation of LPS. Furthermore, our study showed PTEN decreased LPS-induced Akt activity and upregulated NF-κB-dependent gene transcription, identifying indirectly that the PTEN could regulate the activation of NF-κB by its downstream Akt kinase. In summary, our study illustrates the potential signal transduction process of PTEN while stimulated by LPS: by increasing the association of TLR4, PTEN recruits to its phosphoinositide substrate PI(3,4,5)P3 located on the cell membrane and exerts its dephosphorylated function and subsequently depresses the activity of downstream molecule Akt and results in activation of NF-κB, followed by the secretion of inflammatory mediators TNF-α. PMID:27563672

  15. PTEN recruitment controls synaptic and cognitive function in Alzheimer's models.

    PubMed

    Knafo, Shira; Sánchez-Puelles, Cristina; Palomer, Ernest; Delgado, Igotz; Draffin, Jonathan E; Mingo, Janire; Wahle, Tina; Kaleka, Kanwardeep; Mou, Liping; Pereda-Perez, Inmaculada; Klosi, Edvin; Faber, Erik B; Chapman, Heidi M; Lozano-Montes, Laura; Ortega-Molina, Ana; Ordóñez-Gutiérrez, Lara; Wandosell, Francisco; Viña, Jose; Dotti, Carlos G; Hall, Randy A; Pulido, Rafael; Gerges, Nashaat Z; Chan, Andrew M; Spaller, Mark R; Serrano, Manuel; Venero, César; Esteban, José A

    2016-03-01

    Dyshomeostasis of amyloid-β peptide (Aβ) is responsible for synaptic malfunctions leading to cognitive deficits ranging from mild impairment to full-blown dementia in Alzheimer's disease. Aβ appears to skew synaptic plasticity events toward depression. We found that inhibition of PTEN, a lipid phosphatase that is essential to long-term depression, rescued normal synaptic function and cognition in cellular and animal models of Alzheimer's disease. Conversely, transgenic mice that overexpressed PTEN displayed synaptic depression that mimicked and occluded Aβ-induced depression. Mechanistically, Aβ triggers a PDZ-dependent recruitment of PTEN into the postsynaptic compartment. Using a PTEN knock-in mouse lacking the PDZ motif, and a cell-permeable interfering peptide, we found that this mechanism is crucial for Aβ-induced synaptic toxicity and cognitive dysfunction. Our results provide fundamental information on the molecular mechanisms of Aβ-induced synaptic malfunction and may offer new mechanism-based therapeutic targets to counteract downstream Aβ signaling.

  16. Enzymatic Analysis of PTEN Ubiquitylation by WWP2 and NEDD4-1 E3 Ligases.

    PubMed

    Chen, Zan; Thomas, Stefani N; Bolduc, David M; Jiang, Xuejun; Zhang, Xiangbin; Wolberger, Cynthia; Cole, Philip A

    2016-07-01

    PTEN is a lipid phosphatase that converts phosphatidylinositol 3,4,5-phosphate (PIP3) to phosphatidylinositol 4,5-phosphate (PIP2) and plays a critical role in the regulation of tumor growth. PTEN is subject to regulation by a variety of post-translational modifications, including phosphorylation on a C-terminal cluster of four Ser/Thr residues (380, 382, 383, and 385) and ubiquitylation by various E3 ligases, including NEDD4-1 and WWP2. It has previously been shown that C-terminal phosphorylation of PTEN can increase its cellular half-life. Using in vitro ubiquitin transfer assays, we show that WWP2 is more active than NEDD4-1 in ubiquitylating unphosphorylated PTEN. The mapping of ubiquitylation sites in PTEN by mass spectrometry showed that both NEDD4-1 and WWP2 can target a broad range of Lys residues in PTEN, although NEDD4-1 versus WWP2 showed a stronger preference for ubiquitylating PTEN's C2 domain. Whereas tetraphosphorylation of PTEN did not significantly affect its ubiquitylation by NEDD4-1, it inhibited PTEN ubiquitylation by WWP2. Single-turnover and pull-down experiments suggested that tetraphosphorylation of PTEN appears to weaken its interaction with WWP2. These studies reveal how the PTEN E3 ligases WWP2 and NEDD4-1 exhibit distinctive properties in Lys selectivity and sensitivity to PTEN phosphorylation. Our findings also provide a molecular mechanism for the connection between PTEN Ser/Thr phosphorylation and PTEN's cellular stability.

  17. Rapid estrogen signaling negatively regulates PTEN activity through phosphorylation in endometrial cancer cells

    PubMed Central

    Scully, Melanie M.; Palacios-Helgeson, Leslie K.; Wah, Lah S.; Jackson, Twila A.

    2014-01-01

    Hyperestrogenicity is a risk factor for endometrial cancer. 17β-estradiol (E2) is known to stimulate both genomic and nongenomic estrogen receptor-α (ERα) actions in a number of reproductive tissues. However, the contributions of transcription-independent ERα signaling on normal and malignant endometrium are not fully understood. Phosphatase and tensin homolog (PTEN) is a tumor suppressor that decreases cellular mitosis primarily through negative regulation of the phosphoinositide 3-kinase/AKT signaling axis. PTEN levels are elevated during the E2 dominated, mitotically active, proliferative phase of the menstrual cycle, indicating possible hormonal regulation of PTEN in the uterus. In order to determine if rapid E2 signaling regulates PTEN, we used ERα positive, PTEN positive, endometrial cells. We show that cytosolic E2/ERα signaling leads to increased phosphorylation of PTEN at key regulatory residues. Importantly, E2 stimulation decreased PTEN lipid phosphatase activity and caused consequent increases in phospho-AKT. We further demonstrate that cytosolic ERα forms a complex with PTEN in an E2-dependent manner, and that ERα constitutively complexes with protein kinase2-α (CK2α), a kinase previously shown to phosphorylate the C-terminal tail of PTEN. These results provide mechanistic support for an E2-dependent, ERα cytosolic signaling complex that negatively regulates PTEN activity through carboxy terminus phosphorylation. Using an animal model, we show that sustained E2 signaling results in increased phospho-PTEN (S380, T382, T383), total PTEN and phospho-AKT (S473). Taken together, we provide a novel mechanism in which transcription-independent E2/ERα signaling may promote a pro-tumorigenic environment in the endometrium. PMID:24844349

  18. Allosteric substrate switching in a voltage sensing lipid phosphatase

    PubMed Central

    Grimm, Sasha S.; Isacoff, Ehud Y.

    2016-01-01

    Allostery provides a critical control over enzyme activity, biasing the catalytic site between inactive and active states. We find the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP), which modifies phosphoinositide signaling lipids (PIPs), to have not one but two sequential active states with distinct substrate specificities, whose occupancy is allosterically controlled by sequential conformations of the voltage sensing domain (VSD). Using fast FRET reporters of PIPs to monitor enzyme activity and voltage clamp fluorometry to monitor conformational changes in the VSD, we find that Ci-VSP switches from inactive to a PIP3-preferring active state when the VSD undergoes an initial voltage sensing motion and then into a second PIP2-preferring active state when the VSD activates fully. This novel 2-step allosteric control over a dual specificity enzyme enables voltage to shape PIP concentrations in time, and provides a mechanism for the complex modulation of PIP-regulated ion channels, transporters, cell motility and endo/exocytosis. PMID:26878552

  19. Allosteric substrate switching in a voltage-sensing lipid phosphatase.

    PubMed

    Grimm, Sasha S; Isacoff, Ehud Y

    2016-04-01

    Allostery provides a critical control over enzyme activity, biasing the catalytic site between inactive and active states. We found that the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP), which modifies phosphoinositide signaling lipids (PIPs), has not one but two sequential active states with distinct substrate specificities, whose occupancy is allosterically controlled by sequential conformations of the voltage-sensing domain (VSD). Using fast fluorescence resonance energy transfer (FRET) reporters of PIPs to monitor enzyme activity and voltage-clamp fluorometry to monitor conformational changes in the VSD, we found that Ci-VSP switches from inactive to a PIP3-preferring active state when the VSD undergoes an initial voltage-sensing motion and then into a second PIP2-preferring active state when the VSD activates fully. This two-step allosteric control over a dual-specificity enzyme enables voltage to shape PIP concentrations in time, and provides a mechanism for the complex modulation of PIP-regulated ion channels, transporters, cell motility, endocytosis and exocytosis. PMID:26878552

  20. Ginkgetin Blocks Constitutive STAT3 Activation and Induces Apoptosis through Induction of SHP-1 and PTEN Tyrosine Phosphatases.

    PubMed

    Baek, Seung Ho; Lee, Jae Hwi; Ko, Jeong-Hyeon; Lee, Hanwool; Nam, Dongwoo; Lee, Seok Geun; Yang, Woong Mo; Um, Jae-Young; Lee, Junhee; Kim, Sung-Hoon; Shim, Bum Sang; Ahn, Kwang Seok

    2016-04-01

    Ginkgetin, a biflavone from Ginkgo biloba leaves, is known to exhibit antiinflammatory, antifungal, neuroprotective, and antitumor activities, but its precise mechanism of action has not been fully elucidated. Because the aberrant activation of STAT3 has been linked with regulation of inflammation, proliferation, invasion, and metastasis of tumors, we hypothesized that ginkgetin modulates the activation of STAT3 in tumor cells. We found that ginkgetin clearly suppressed constitutive phosphorylation of STAT3 through inhibition of the activation of upstream JAK1 and c-Src kinases and nuclear translocation of STAT3 on both A549 and FaDu cells. Treatment with sodium pervanadate reversed the ginkgetin-induced down-modulation of STAT3, thereby indicating a critical role for a PTP. We also found that ginkgetin strongly induced the expression of the SHP-1 and PTEN proteins and its mRNAs. Further, deletion of SHP-1 and PTEN genes by siRNA suppressed the induction of SHP-1 and PTEN, and reversed the inhibition of STAT3 activation. Ginkgetin induced apoptosis as characterized by an increased accumulation of cells in subG1 phase, positive Annexin V binding, loss of mitochondrial membrane potential, down-regulation of STAT3-regulated gene products, and cleavage of PARP. Overall, ginkgetin abrogates STAT3 signaling pathway through induction of SHP-1 and PTEN proteins, thus attenuating STAT3 phosphorylation and tumorigenesis. PMID:27059688

  1. AIF inhibits tumor metastasis by protecting PTEN from oxidation.

    PubMed

    Shen, Shao-Ming; Guo, Meng; Xiong, Zhong; Yu, Yun; Zhao, Xu-Yun; Zhang, Fei-Fei; Chen, Guo-Qiang

    2015-11-01

    Apoptosis-inducing factor (AIF) exerts dual roles on cell death and survival, but its substrates as a putative oxidoreductase and roles in tumorigenesis remain elusive. Here, we report that AIF physically interacts with and inhibits the oxidation of phosphatase and tensin homolog on chromosome ten (PTEN), a tumor suppressor susceptible for oxidation-mediated inactivation. More intriguingly, we also identify PTEN as a mitochondrial protein and the ectopic expression of mitochondrial targeting sequence-carrying PTEN almost completely inhibits Akt phosphorylation in PTEN-deficient cells. AIF knockdown causes oxidation-mediated inactivation of the lipid phosphatase activity of PTEN, with ensuing activation of Akt kinase, phosphorylation of the Akt substrate GSK-3β, and activation of β-catenin signaling in cancer cells. Through its effect on β-catenin signaling, AIF inhibits epithelial-mesenchymal transition (EMT) and metastasis of cancer cells in vitro and in orthotopically implanted xenografts. Accordingly, the expression of AIF is correlated with the survival of human patients with cancers of multiple origins. These results identify PTEN as the substrate of AIF oxidoreductase and reveal a novel function for AIF in controlling tumor metastasis.

  2. PTEN is involved in modulation of vasculogenesis in early chick embryos.

    PubMed

    Li, Yan; Wang, Xiao-Yu; Wu, Ting; Chuai, Manli; Lee, Kenneth Ka Ho; Wang, Li-Jing; Yang, Xuesong

    2013-06-15

    PTEN is a tumor suppressor gene that is mutated and/or deleted in many types of tumor. This gene also plays a very distinct role in the early stages of embryonic development such as cell migration, proliferation and migration. Nevertheless, little is known of the function of PTEN in vasculogenesis during chick embryonic development. In this study, we used in situ hybridization to first demonstrate the expression pattern of PTEN during gastrulation. PTEN was found mainly expressed in the blood islands of area opaca, the neural tube and mesodermal structures. Overexpression of PTEN obstructed the epithelial-mesenchymal transition (EMT) process in the primitive streak. EMT is the first prerequisite required for the emigration of hemangioblasts during vasculogenesis. When PTEN expression was silenced, we observed that it produced an adverse effect on mesodermal cell emigration to the extra-embryonic blood islands. In addition, we also demonstrated that even if the perturbed-PTEN cells did not affect the formation of blood islands, migrant mesodermal cells overexpressing wt PTEN-GFP had difficulties integrating into the blood islands. Instead, these cells were either localized on the periphery of the blood islands or induced to differentiate into endothelial cells if they managed to integrate into blood islands. Development of the intra-embryonic primary vascular plexus was also affected by overexpression of PTEN. We proposed that it was elevated PTEN lipid phosphatase activity that was responsible for the morphogenetic defects induced by PTEN overexpression. In this context, we did not find PTEN affecting VEGF signaling. In sum, our study has provided evidence that PTEN is involved in vasculogenesis during the early stages of chick embryo development.

  3. Cloning and characterization of three Eimeria tenella lipid phosphate phosphatases.

    PubMed

    Guo, Aijiang; Cai, Jianping; Luo, Xuenong; Zhang, Shaohua; Hou, Junling; Li, Hui; Cai, Xuepeng

    2015-01-01

    Although lipid phosphate phosphatases (LPPs) play an important role in cellular signaling in addition to lipid biosynthesis, little is thus far known about parasite LPPs. In this study, we characterized three Eimeria tenella cDNA clones encoding LPP named EtLPP1, EtLPP2 and EtLPP3. Key structural features previously described in LPPs, including the three conserved domains proposed as catalytic sites, a single conserved N-glycosylation site, and putative transmembrane domains were discovered in the three resulting EtLPP amino acid sequences. Expression of His6-tagged EtLPP1, -2, and -3 in HEK293 cells produced immunoreactive proteins with variable molecular sizes, suggesting the presence of multiple forms of each of the three EtLPPs. The two faster-migrating protein bands below each of the three EtLPP proteins were found to be very similar to the porcine 35-kDa LPP enzyme in their molecular size and the extent of their N-glycosylation, suggesting that the three EtLPPs are partially N-glycosylated. Kinetic analyses of the activity of the three enzymes against PA, LPA, C1P and S1P showed that Km values for each of the substrates were (in μM) 284, 46, 28, and 22 for EtLPP1; 369, 179, 237, and 52 for EtLPP2; and 355, 83, and 260 for EtLPP3. However, EtLPP3 showed negligible activity on S1P. These results confirmed that the three EtLPPs have broad substrate specificity. The results also indicated that despite structural similarities, the three EtLPPs may play distinct functions through their different models of substrate preference. Furthermore, particularly high expression levels of the three EtLPP genes were detected in the sporozoite stage of the E. tenella life cycle (p<0.001), suggesting that their encoded proteins might play an important biological function in the sporozoite stage. PMID:25861032

  4. Benefit to neoadjuvant anti-human epidermal growth factor receptor 2 (HER2)-targeted therapies in HER2-positive primary breast cancer is independent of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) status

    PubMed Central

    Nuciforo, P. G.; Aura, C.; Holmes, E.; Prudkin, L.; Jimenez, J.; Martinez, P.; Ameels, H.; de la Peña, L.; Ellis, C.; Eidtmann, H.; Piccart-Gebhart, M. J.; Scaltriti, M.; Baselga, J.

    2015-01-01

    Background Assessment of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) might be an important tool in identifying human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients unlikely to derive benefit from anti-HER2 therapies. However, studies to date have failed to demonstrate its predictive role in any treatment setting. Patients and methods Prospectively collected baseline core biopsies from 429 early-stage HER2-positive breast cancer patients treated with trastuzumab, lapatinib, or their combination in the Neo-ALTTO study were stained using two anti-PTEN monoclonal antibodies (CST and DAKO). The association of PTEN status and PI3K pathway activation (defined as either PTEN loss and/or PIK3CA mutation) with total pathological complete response (tpCR) at surgery, event-free survival (EFS), and overall survival (OS) was evaluated. Results PTEN loss was observed in 27% and 29% of patients (all arms, n = 361 and n = 363) for CST and DAKO, respectively. PTEN loss was more frequently observed in hormone receptor (HR)-negative (33% and 36% with CST and DAKO, respectively) compared with HR-positive tumours (20% and 22% with CST and DAKO, respectively). No significant differences in tpCR rates were observed according to PTEN status. PI3K pathway activation was found in 47% and 48% of patients (all arms, n = 302 and n = 301) for CST and DAKO, respectively. Similarly, tpCR rates were not significantly different for those with or without PI3K pathway activation. Neither PTEN status nor PI3K pathway activation were predictive of tpCR, EFS, or OS, independently of treatment arm or HR status. High inter-antibody and inter-observer agreements were found (>90%). Modification of scoring variables significantly affected the correlation between PTEN and HR status but not with tpCR. Conclusion These data show that PTEN status determination is not a useful biomarker to predict resistance to trastuzumab and lapatinib-based therapies. The lack of

  5. Inhibition of phosphatase and tensin homologue (PTEN) in human ovary in vitro results in increased activation of primordial follicles but compromises development of growing follicles.

    PubMed

    McLaughlin, Marie; Kinnell, Hazel L; Anderson, Richard A; Telfer, Evelyn E

    2014-08-01

    In the mammalian ovary a small number of follicles are steadily recruited from the quiescent pool to undergo development. Follicle loss, maintenance and growth are strictly controlled by complex molecular interactions including the phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt) signalling pathway. Stimulation of PI3K promotes phosphorylation of Akt resulting in follicle survival and activation of growth whereas this pathway is suppressed by the actions of the phosphatase and tensin homologue (PTEN). The aim of this study was to determine the effect of dipotassium bisperoxo(5-hydroxypyridine-2-carboxyl)oxovanadate (bpV), a reversible inhibitor of PTEN, on the activation, survival and development of human ovarian follicles in vitro. Biopsied ovarian tissue fragments were obtained from 17 women aged 23-46 years and exposed to 1 µM bpV(HOpic) (n = 146) or control medium (n = 128) for 24 h. Media were then replaced with control medium and all tissue incubated for a further 5 days. Ovarian tissue from each treatment group was fixed after the initial 24 h culture period and phosphorylated Akt was quantified by western blotting. After 6 days incubation all tissue fragments were inspected under light microscopy and any secondary follicles ≥100 µm isolated. Isolated follicles were cultured individually in control medium supplemented with 100 ng/ml recombinant human activin A. Tissue fragments without follicles suitable for isolation were fixed and processed for histological and immunohistochemical analysis. During 6 days culture, follicle activation occurred in tissue samples from both treatment groups but with significantly more follicles progressing to the secondary stage of development in the presence of 1 µM bpV(HOpic) compared with control (31 versus 16%; P < 0.05). Increased activation was associated with increased Akt phosphorylation and increased nuclear export of FOXO3. However isolated and cultured follicles that had been exposed to bpV(HOpic) showed

  6. Inhibition of phosphatase and tensin homologue (PTEN) in human ovary in vitro results in increased activation of primordial follicles but compromises development of growing follicles

    PubMed Central

    McLaughlin, Marie; Kinnell, Hazel L.; Anderson, Richard A.; Telfer, Evelyn E.

    2014-01-01

    In the mammalian ovary a small number of follicles are steadily recruited from the quiescent pool to undergo development. Follicle loss, maintenance and growth are strictly controlled by complex molecular interactions including the phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt) signalling pathway. Stimulation of PI3K promotes phosphorylation of Akt resulting in follicle survival and activation of growth whereas this pathway is suppressed by the actions of the phosphatase and tensin homologue (PTEN). The aim of this study was to determine the effect of dipotassium bisperoxo(5-hydroxypyridine-2-carboxyl)oxovanadate (bpV), a reversible inhibitor of PTEN, on the activation, survival and development of human ovarian follicles in vitro. Biopsied ovarian tissue fragments were obtained from 17 women aged 23–46 years and exposed to 1 µM bpV(HOpic) (n = 146) or control medium (n = 128) for 24 h. Media were then replaced with control medium and all tissue incubated for a further 5 days. Ovarian tissue from each treatment group was fixed after the initial 24 h culture period and phosphorylated Akt was quantified by western blotting. After 6 days incubation all tissue fragments were inspected under light microscopy and any secondary follicles ≥100 µm isolated. Isolated follicles were cultured individually in control medium supplemented with 100 ng/ml recombinant human activin A. Tissue fragments without follicles suitable for isolation were fixed and processed for histological and immunohistochemical analysis. During 6 days culture, follicle activation occurred in tissue samples from both treatment groups but with significantly more follicles progressing to the secondary stage of development in the presence of 1 µM bpV(HOpic) compared with control (31 versus 16%; P < 0.05). Increased activation was associated with increased Akt phosphorylation and increased nuclear export of FOXO3. However isolated and cultured follicles that had been exposed to bp

  7. Inhibition of PTEN and activation of Akt by menadione.

    PubMed

    Yoshikawa, Kyoko; Nigorikawa, Kiyomi; Tsukamoto, Mariko; Tamura, Namiko; Hazeki, Kaoru; Hazeki, Osamu

    2007-04-01

    Menadione (vitamin K(3)) has been shown to activate Erk in several cell lines. This effect has been shown to be due to the activation of EGF receptors (EGFR) as a result of inhibition of some protein tyrosine phosphatases. In the present study, we examined the effects of menadione on Akt in Chinese hamster ovary cells. The phosphorylation of Akt by menadione was not inhibited by AG1478, an inhibitor of EGFR. Menadione inhibited the lipid phosphatase activity of PTEN in a cell-free system. In an intact cell system, menadione inhibited the effect of transfected PTEN on Akt. Thus, one mechanism of its action was considered the accelerated activation of Akt through inhibition of PTEN. This was not the sole mechanism responsible for the EGFR-independent activation of Akt, because menadione attenuated the rate of Akt dephosphorylation even in PTEN-null PC3 cells. The decelerated inactivation of Akt, probably through inhibition of some tyrosine phosphatases, was considered another mechanism of its action.

  8. Sphingosylphosphorylcholine protects cardiomyocytes against ischemic apoptosis via lipid raft/PTEN/Akt1/mTOR mediated autophagy.

    PubMed

    Yue, Hong-Wei; Liu, Jing; Liu, Ping-Ping; Li, Wen-Jing; Chang, Fen; Miao, Jun-Ying; Zhao, Jing

    2015-09-01

    Autophagy, evoked by diverse stresses including myocardial ischemia/reperfusion (I/R), profoundly affects the development of heart failure. However, the specific molecular basis of autophagy remains to be elucidated. Here we report that sphingosylphosphorylcholine (SPC), a bioactive sphingolipid, significantly suppressed apoptosis and induced autophagy in cardiomyocytes. Blocking this SPC evoked autophagy by 3-methyladenine (3MA)-sensitized cardiomyocytes to serum deprivation-induced apoptosis. Subsequent studies revealed that SPC downregulated the phosphorylation of p70S6K and 4EBP1 (two substrates of mTOR) but enhanced that of JNK when inducing autophagy. We identified SPC as a switch for the activity of Akt1, a supposed upstream modulator of both mTOR and JNK. Furthermore, β-cyclodextrin, which destroys membrane cholesterol, abolished the SPC-reduced phosphorylation of both Akt and PTEN, thus inhibiting SPC-induced autophagy. In conclusion, SPC is a novel molecule protecting cardiomyocytes against apoptosis by promoting autophagy. The lipid raft/PTEN/Akt1/mTOR signal pathway is the underlying mechanism and might provide novel targets for cardiac failure therapy.

  9. PTEN regulates cilia through Dishevelled

    PubMed Central

    Shnitsar, Iryna; Bashkurov, Mikhail; Masson, Glenn R.; Ogunjimi, Abiodun A.; Mosessian, Sherly; Cabeza, Eduardo Aguiar; Hirsch, Calley L.; Trcka, Daniel; Gish, Gerald; Jiao, Jing; Wu, Hong; Winklbauer, Rudolf; Williams, Roger L.; Pelletier, Laurence; Wrana, Jeffrey L.; Barrios-Rodiles, Miriam

    2015-01-01

    Cilia are hair-like cellular protrusions important in many aspects of eukaryotic biology. For instance, motile cilia enable fluid movement over epithelial surfaces, while primary (sensory) cilia play roles in cellular signalling. The molecular events underlying cilia dynamics, and particularly their disassembly, are not well understood. Phosphatase and tensin homologue (PTEN) is an extensively studied tumour suppressor, thought to primarily act by antagonizing PI3-kinase signalling. Here we demonstrate that PTEN plays an important role in multicilia formation and cilia disassembly by controlling the phosphorylation of Dishevelled (DVL), another ciliogenesis regulator. DVL is a central component of WNT signalling that plays a role during convergent extension movements, which we show here are also regulated by PTEN. Our studies identify a novel protein substrate for PTEN that couples PTEN to regulation of cilia dynamics and WNT signalling, thus advancing our understanding of potential underlying molecular etiologies of PTEN-related pathologies. PMID:26399523

  10. PTEN regulates PLK1 and controls chromosomal stability during cell division.

    PubMed

    Zhang, Zhong; Hou, Sheng-Qi; He, Jinxue; Gu, Tingting; Yin, Yuxin; Shen, Wen H

    2016-09-16

    PTEN functions as a guardian of the genome through multiple mechanisms. We have previously established that PTEN maintains the structural integrity of chromosomes. In this report, we demonstrate a fundamental role of PTEN in controlling chromosome inheritance to prevent gross genomic alterations. Disruption of PTEN or depletion of PTEN protein phosphatase activity causes abnormal chromosome content, manifested by enlarged or polyploid nuclei. We further identify polo-like kinase 1 (PLK1) as a substrate of PTEN phosphatase. PTEN can physically associate with PLK1 and reduce PLK1 phosphorylation in a phosphatase-dependent manner. We show that PTEN deficiency leads to PLK1 phosphorylation and that a phospho-mimicking PLK1 mutant causes polyploidy, imitating functional deficiency of PTEN phosphatase. Inhibition of PLK1 activity or overexpression of a non-phosphorylatable PLK1 mutant reduces the polyploid cell population. These data reveal a new mechanism by which PTEN controls genomic stability during cell division.

  11. Regulation of the activity of the tumor suppressor PTEN by thioredoxin in Drosophila melanogaster

    SciTech Connect

    Song, Zuohe; Saghafi, Negin; Gokhale, Vijay; Brabant, Marc; Meuillet, Emmanuelle J. . E-mail: emeuillet@azcc.arizona.edu

    2007-04-01

    Human Thioredoxin-1 (hTrx-1) is a small redox protein with a molecular weight of 12 kDa that contains two cysteine residues found in its catalytic site. HTrx-1 plays an important role in cell growth, apoptosis, and cancer patient prognosis. Recently, we have demonstrated that hTrx-1 binds to the C2 domain of the human tumor suppressor, PTEN, in a redox dependent manner. This binding leads to the inhibition of PTEN lipid phosphatase activity in mammalian tissue culture systems. In this study, we show that over-expression of hTrx-1 in Drosophila melanogaster promotes cell growth and proliferation during eye development as measured by eye size and ommatidia size. Furthermore, hTrx-1 rescues the small eye phenotype induced by the over-expression of PTEN. We demonstrate that this rescue of the PTEN-induced eye size phenotype requires cysteine-218 in the C2 domain of PTEN. We also show that hTrx-1 over-expression results in increased Akt phosphorylation in fly head extracts supporting our observations that the hTrx-1-induced eye size increase results from the inhibition of PTEN activity. Our study confirms the redox regulation of PTEN through disulfide bond formation with the hTrx-1 in Drosophila and suggests conserved mechanisms for thioredoxins and their interactions with the phosphatidylinositol-3-kinase signaling pathway in humans and fruit flies.

  12. PTEN-induction in U251 glioma cells decreases the expression of insulin-like growth factor binding protein-2

    SciTech Connect

    Levitt, Randy J.; Georgescu, Maria-Magdalena; Pollak, Michael . E-mail: michael.pollak@mcgill.ca

    2005-11-04

    PTEN is a tumor suppressor gene whose loss of function is observed in {approx}40-50% of human cancers. Although insulin-like growth factor binding protein-2 (IGFBP-2) was classically described as a growth inhibitor, multiple recent reports have shown an association of overexpression and/or high serum levels of IGFBP-2 with poor prognosis of several malignancies, including gliomas. Using an inducible PTEN expression system in the PTEN-null glioma cell line U251, we demonstrate that PTEN-induction is associated with reduced proliferation, increased apoptosis, and a substantial reduction of the high levels of IGFBP-2 expression. The PTEN-induced decrease in IGFBP-2 expression could be mimicked with the PI3-kinase inhibitor LY294002, indicating that the lipid phosphatase activity of PTEN is responsible for the observed effect. However, the rapamycin analog CCI-779 did not affect IGFBP-2 expression, suggesting that the PTEN-induced decrease in IGFBP-2 expression is not attributable to decreased mTOR signalling. Recombinant human IGFBP-2 was unable to rescue U251-PTEN cells from the antiproliferative effects of PTEN, and IGFBP-2 siRNA did not affect the IGF-dependent or -independent growth of this cell line. These results suggest that the clinical data linking IGFBP-2 expression to poor prognosis may arise, at least in part, because high levels of IGFBP-2 expression correlate with loss of function of PTEN, which is well known to lead to aggressive behavior of gliomas. Our results motivate translational research regarding the relationship between IGFBP-2 expression and loss of function of PTEN.

  13. Attenuated virulence of a Francisella mutant lacking the lipid A 4′-phosphatase

    PubMed Central

    Wang, Xiaoyuan; Ribeiro, Anthony A.; Guan, Ziqiang; Abraham, Soman N.; Raetz, Christian R. H.

    2007-01-01

    Francisella tularensis causes tularemia, a highly contagious disease of animals and humans, but the virulence features of F. tularensis are poorly defined. F. tularensis and the related mouse pathogen Francisella novicida synthesize unusual lipid A molecules lacking the 4′-monophosphate group typically found in the lipid A of Gram-negative bacteria. LpxF, a selective phosphatase located on the periplasmic surface of the inner membrane, removes the 4′-phosphate moiety in the late stages of F. novicida lipid A assembly. To evaluate the relevance of the 4′-phosphatase to pathogenesis, we constructed a deletion mutant of lpxF and compared its virulence with wild-type F. novicida. Intradermal injection of 106 wild-type but not 108 mutant F. novicida cells is lethal to mice. The rapid clearance of the lpxF mutant is associated with a stronger local cytokine response and a greater influx of neutrophils compared with wild-type. The F. novicida mutant was highly susceptible to the cationic antimicrobial peptide polymyxin. LpxF therefore represents a kind of virulence factor that confers a distinct lipid A phenotype, preventing Francisella from activating the host innate immune response and preventing the bactericidal actions of cationic peptides. Francisella lpxF mutants may be useful for immunization against tularemia. PMID:17360489

  14. Simultaneous loss of the DLC1 and PTEN tumor suppressors enhances breast cancer cell migration

    SciTech Connect

    Heering, Johanna; Erlmann, Patrik; Olayioye, Monilola A.

    2009-09-10

    The phosphatase and tensin homolog (PTEN) gene is a tumor suppressor frequently deleted or mutated in sporadic tumors of the breast, prostate, endometrium and brain. The protein acts as a dual specificity phosphatase for lipids and proteins. PTEN loss confers a growth advantage to cells, protects from apoptosis and favors cell migration. The deleted in liver cancer 1 (DLC1) gene has emerged as a novel tumor suppressor downregulated in a variety of tumor types including those of the breast. DLC1 contains a Rho GTPase activating domain that is involved in the inhibition of cell proliferation, migration and invasion. To investigate how simultaneous loss of PTEN and DLC1 contributes to cell transformation, we downregulated both proteins by RNA interference in the non-invasive MCF7 breast carcinoma cell line. Joint depletion of PTEN and DLC1 resulted in enhanced cell migration in wounding and chemotactic transwell assays. Interestingly, both proteins were found to colocalize at the plasma membrane and interacted physically in biochemical pulldowns and coimmunoprecipitations. We therefore postulate that the concerted local inactivation of signaling pathways downstream of PTEN and DLC1, respectively, is required for the tight control of cell migration.

  15. Ethnic differences in pre-adipocyte intracellular lipid accumulation and alkaline phosphatase activity.

    PubMed

    Ali, Aus T; Chirambo, George; Penny, Clement; Paiker, Janice E; Ikram, Faisel; Psaras, George; Crowther, Nigel J

    2015-01-01

    Alkaline phosphatase (ALP) increases lipid accumulation in human pre-adipocytes. This study was performed to assess whether ethnic differences in the prevalence of obesity in African and European females are related to differences in pre-adipocyte lipid accretion and ALP activity. Pre-adipocytes were isolated from 13 black and 14 white females. Adipogenesis was quantified using the lipid dye, Oil red O, whilst ALP activity was assayed in cell extracts on day zero and 12days after initiating adipogenesis. Lipid levels (OD units/mg protein) were lower in pre-adipocytes from white than black females on day 0 (0.36±0.05 versus 0.44±0.03, respectively; p<0.0005) and day 12 (1.18±0.14 versus 1.80±0.22, respectively; p<0.0005), as was ALP activity (mU/mg protein) on day zero (36.5±5.8 versus 136.4±10.9, respectively; p<0.0005) and day 12 (127±16 versus 278±27, respectively; p<0.0005). Treatment of pre-adipocytes with histidine, an ALP inhibitor, blocked lipid accumulation. Thus, lipid uptake is higher in pre-adipocytes isolated from black compared to white females which parallels the obesity prevalence rates in these population groups. The reason for higher fat accumulation in pre-adipocytes isolated from black females may be related to higher ALP activity.

  16. PTEN recruitment controls synaptic and cognitive function in Alzheimer's models.

    PubMed

    Knafo, Shira; Sánchez-Puelles, Cristina; Palomer, Ernest; Delgado, Igotz; Draffin, Jonathan E; Mingo, Janire; Wahle, Tina; Kaleka, Kanwardeep; Mou, Liping; Pereda-Perez, Inmaculada; Klosi, Edvin; Faber, Erik B; Chapman, Heidi M; Lozano-Montes, Laura; Ortega-Molina, Ana; Ordóñez-Gutiérrez, Lara; Wandosell, Francisco; Viña, Jose; Dotti, Carlos G; Hall, Randy A; Pulido, Rafael; Gerges, Nashaat Z; Chan, Andrew M; Spaller, Mark R; Serrano, Manuel; Venero, César; Esteban, José A

    2016-03-01

    Dyshomeostasis of amyloid-β peptide (Aβ) is responsible for synaptic malfunctions leading to cognitive deficits ranging from mild impairment to full-blown dementia in Alzheimer's disease. Aβ appears to skew synaptic plasticity events toward depression. We found that inhibition of PTEN, a lipid phosphatase that is essential to long-term depression, rescued normal synaptic function and cognition in cellular and animal models of Alzheimer's disease. Conversely, transgenic mice that overexpressed PTEN displayed synaptic depression that mimicked and occluded Aβ-induced depression. Mechanistically, Aβ triggers a PDZ-dependent recruitment of PTEN into the postsynaptic compartment. Using a PTEN knock-in mouse lacking the PDZ motif, and a cell-permeable interfering peptide, we found that this mechanism is crucial for Aβ-induced synaptic toxicity and cognitive dysfunction. Our results provide fundamental information on the molecular mechanisms of Aβ-induced synaptic malfunction and may offer new mechanism-based therapeutic targets to counteract downstream Aβ signaling. PMID:26780512

  17. PTEN expression in ovine granulosa cells increases during terminal follicular growth.

    PubMed

    Froment, Pascal; Bontoux, Martine; Pisselet, Claudine; Monget, Philippe; Dupont, Joëlle

    2005-04-25

    In the present paper, we have studied the expression of the Phosphatase and TENsin homolog deleted on chromosome 10 (PTEN) and its putative biological role in the sheep ovary. We found by Northern-blot, immunohistochemistry and immunoblot that PTEN is highly expressed in granulosa cells from large differentiated follicles (LF) in comparison with small proliferating follicles (SF) (P < 0.001), with no clear effect of follicle quality. Moreover, the PTEN lipid phosphatase activity is also higher in LF than in SF (P < 0.01). In contrast, levels of the phosphorylated form of AKT (pAKT) are lower in LF than in SF (P < 0.0001). IGF-I and insulin but not FSH, LH or forskolin are able to stimulate the expression of PTEN mRNA (P < 0.001) and protein by ovine granulosa cells after 48 h of culture in vitro. An IGF-1 time course analysis showed that expression of PTEN protein appeared after 12h of culture, concomitant with the fall of the pAKT levels, which peaked after 6h of stimulation with IGF-I. Moreover, transfection experiments showed that overexpression of PTEN in ovine granulosa cells induced a decrease and an increase in E2F and p27 promoter activity, respectively (P < 0.05). Overall, our present data show for the first time that the expression of PTEN increases during terminal follicular growth. This increase, that might be induced by IGF-I but not FSH, would participate in the proliferation/differentiation transition of ovine granulosa cells in differentiating follicles.

  18. Lipid A biosynthesis in Rhizobium leguminosarum: Role of a 2-keto-3-deoxyoctulosonate-activated 4{prime} phosphatase

    SciTech Connect

    Price, N.P.J.; Jeyaretnam, B.; Carlson, R.W.

    1995-08-01

    Lipid A from several strains of the N{sub 2}-fixing bacterium Rhizobium leguminosarum displays significant structural differences from Escherichia coli lipid A, one of which is the complete absence of phosphate groups. However, the first seven enzymes of E. coli lipid A biosynthesis, leading from UDP-GlcNAc to the phosphorylated intermediate, 2-keto-3-deoxyoctulosonate (Kdo{sub 2})-lipid IV{sub A}, are present in R. leguminosarum. We now describe a membrane-bound phosphatase in R. leguminosarum extracts that removes the 4{prime} phosphate of Kdo{sub 2}-lipid IV{sub A}. The 4{prime} phosphatase is selective for substrates containing the Kdo domain. It is present in extracts of R. leguminosarum biovars phaseoli, viciae, and trifolii but is not detectable in E. coli and Rhizobium meliloti. A nodulation-defective strain (24AR) of R. leguminosarum bovar trifolii, known to contain a 4{prime} phosphate residue on its lipid A, also lacks measurable 4{prime} phosphatase activity. the Kdo-dependent 4{prime} phosphatase appears to be a key reaction in a pathway for generating phosphate-deficient lipid A.

  19. Recent advances in targeting the autotaxin-lysophosphatidate-lipid phosphate phosphatase axis in vivo.

    PubMed

    Benesch, Matthew G K; Tang, Xiaoyun; Venkatraman, Ganesh; Bekele, Raie T; Brindley, David N

    2016-07-01

    Extracellular lysophosphatidate (LPA) is a potent bioactive lipid that signals through six G-protein-coupled receptors. This signaling is required for embryogenesis, tissue repair and remodeling processes. LPA is produced from circulating lysophosphatidylcholine by autotaxin (ATX), and is degraded outside cells by a family of three enzymes called the lipid phosphate phosphatases (LPPs). In many pathological conditions, particularly in cancers, LPA concentrations are increased due to high ATX expression and low LPP activity. In cancers, LPA signaling drives tumor growth, angiogenesis, metastasis, resistance to chemotherapy and decreased efficacy of radiotherapy. Hence, targeting the ATX-LPA-LPP axis is an attractive strategy for introducing novel adjuvant therapeutic options. In this review, we will summarize current progress in targeting the ATX-LPA-LPP axis with inhibitors of autotaxin activity, LPA receptor antagonists, LPA monoclonal antibodies, and increasing low LPP expression. Some of these agents are already in clinical trials and have applications beyond cancer, including chronic inflammatory diseases. PMID:27533936

  20. Recent advances in targeting the autotaxin-lysophosphatidate-lipid phosphate phosphatase axis in vivo

    PubMed Central

    Benesch, Matthew G.K.; Tang, Xiaoyun; Venkatraman, Ganesh; Bekele, Raie T.; Brindley, David N.

    2016-01-01

    Abstract Extracellular lysophosphatidate (LPA) is a potent bioactive lipid that signals through six G-protein-coupled receptors. This signaling is required for embryogenesis, tissue repair and remodeling processes. LPA is produced from circulating lysophosphatidylcholine by autotaxin (ATX), and is degraded outside cells by a family of three enzymes called the lipid phosphate phosphatases (LPPs). In many pathological conditions, particularly in cancers, LPA concentrations are increased due to high ATX expression and low LPP activity. In cancers, LPA signaling drives tumor growth, angiogenesis, metastasis, resistance to chemotherapy and decreased efficacy of radiotherapy. Hence, targeting the ATX-LPA-LPP axis is an attractive strategy for introducing novel adjuvant therapeutic options. In this review, we will summarize current progress in targeting the ATX-LPA-LPP axis with inhibitors of autotaxin activity, LPA receptor antagonists, LPA monoclonal antibodies, and increasing low LPP expression. Some of these agents are already in clinical trials and have applications beyond cancer, including chronic inflammatory diseases. PMID:27533936

  1. Impact of PTEN on the expression of insulin-like growth factors (IGFs) and IGF-binding proteins in human gastric adenocarcinoma cells

    SciTech Connect

    Yi, Ho-Keun; Kim, Sun-Young; Hwang, Pyoung-Han; Kim, Chan-Young; Yang, Doo-Hyun; Oh, Youngman; Lee, Dae-Yeol . E-mail: leedy@chonbuk.ac.kr

    2005-05-13

    PTEN is a tumor suppressor gene that is frequently mutated or deleted in a variety of human cancers including human gastric cancer. PTEN functions primarily as a lipid phosphatase and plays a key role in the regulation of the PI3 kinase/Akt pathway, thereby modulating cell proliferation and cell survival. On the other hand, the IGF system plays an important role in cell proliferation and cell survival via the PI3 kinase/Akt and MAP kinase pathways in many cancer cells. To characterize the impact of PTEN on the IGF-IGFR-IGFBP axis in gastric cancer, we overexpressed PTEN using an adenovirus gene transfer system in human gastric adenocarcinoma cells, SNU-484 and SNU-663, which lack PTEN. Overexpression of PTEN inhibited serum-induced as well as IGF-I-induced cell proliferation as compared to control cells. PTEN overexpression resulted in a significant decrease in the expression of IGF-I, -II, and IGF-IR. Interestingly, amongst the six IGFBPs, only IGFBP-3 was upregulated by PTEN, whereas IGFBP-4 and -6 were reduced. The IGFBP-3 promoter activity assay and Western immunoblotting demonstrate that PTEN regulates IGFBP-3 at the transcriptional level. In addition, the PI3 kinase inhibitor, LY294002, upregulates IGFBP-3 expression but downregulates IGF-I and IGF-II, indicating that PTEN controls IGFBP-3 and IGFs by an Akt-dependent pathway. These findings suggest that PTEN may inhibit antiapoptotic IGF actions not only by blocking the IGF-IGFR-induced Akt activity, but also by regulating expression of components of the IGF system, in particular, upregulation of IGFBP-3, which is known to exert antiproliferative effects through IGF-dependent and IGF-independent mechanisms in cancer cells.

  2. Genetic alterations of PTEN in human melanoma.

    PubMed

    Aguissa-Touré, Almass-Houd; Li, Gang

    2012-05-01

    The PTEN gene is one of the most frequently inactivated tumor suppressor genes in sporadic cancers. Inactivating mutations and deletions of the PTEN gene are found in many types of cancers, including melanoma. However, the exact frequency of PTEN alteration in melanoma is unknown. In this study, we comprehensively reviewed 16 studies on PTEN genetic changes in melanoma cell lines and tumor biopsies. To date, 76 PTEN alterations have been reported in melanoma cell lines and 38 PTEN alterations in melanoma biopsies. The rate of PTEN alterations in melanoma cell lines, primary melanoma, and metastatic melanoma is 27.6, 7.3, and 15.2%, respectively. Three mutations were found in both melanoma cell lines and biopsies. These mutations are scattered throughout the gene, with the exception of exon 9. A mutational hot spot is found in exon 5, which encodes the phosphatase activity domain. Evidence is also presented to suggest that numerous homozygous deletions and missense variants exist in the PTEN transcript. Studying PTEN functions and implications of its mutations and other genes could provide insights into the precise nature of PTEN function in melanoma and additional targets for new therapeutic approaches. PMID:22076652

  3. Modulation of Symbiont Lipid A Signaling by Host Alkaline Phosphatases in the Squid-Vibrio Symbiosis

    PubMed Central

    Rader, Bethany A.; Kremer, Natacha; Apicella, Michael A.; Goldman, William E.; McFall-Ngai, Margaret J.

    2012-01-01

    ABSTRACT The synergistic activity of Vibrio fischeri lipid A and the peptidoglycan monomer (tracheal cytotoxin [TCT]) induces apoptosis in the superficial cells of the juvenile Euprymna scolopes light organ during the onset of the squid-vibrio symbiosis. Once the association is established in the epithelium-lined crypts of the light organ, the host degrades the symbiont’s constitutively produced TCT by the amidase activity of a peptidoglycan recognition protein (E. scolopes peptidoglycan recognition protein 2 [EsPGRP2]). In the present study, we explored the role of alkaline phosphatases in transforming the lipid A of the symbiont into a form that changes its signaling properties to host tissues. We obtained full-length open reading frames for two E. scolopes alkaline phosphatase (EsAP) mRNAs (esap1 and esap2); transcript levels suggested that the dominant light organ isoform is EsAP1. Levels of total EsAP activity increased with symbiosis, but only after the lipid A-dependent morphogenetic induction at 12 h, and were regulated over the day-night cycle. Inhibition of total EsAP activity impaired normal colonization and persistence by the symbiont. EsAP activity localized to the internal regions of the symbiotic juvenile light organ, including the lumina of the crypt spaces where the symbiont resides. These data provide evidence that EsAPs work in concert with EsPGRPs to change the signaling properties of bacterial products and thereby promote persistent colonization by the mutualistic symbiont. PMID:22550038

  4. Nuclear PTEN controls DNA repair and sensitivity to genotoxic stress

    PubMed Central

    Bassi, C; Ho, J; Srikumar, T; Dowling, RJO; Gorrini, C; Miller, SJ; Mak, TW; Neel, BG; Raught, B; Stambolic, V

    2016-01-01

    Loss of function of the Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) tumor suppressor gene is associated with many human cancers. In the cytoplasm, PTEN antagonizes the Phosphatidylinositol 3′ kinase (PI3K) signaling pathway. PTEN also accumulates in the nucleus, where its function remains poorly understood. We demonstrate that SUMOylation (SUMO) of PTEN controls its nuclear localization. In cells exposed to genotoxic stress, SUMO-PTEN was rapidly excluded from the nucleus dependent on the protein kinase Ataxia telangiectasia mutated (ATM). Cells lacking nuclear PTEN were hypersensitive to DNA damage, while PTEN-deficient cells were susceptible to killing by a combination of genotoxic stress and a small molecule PI3K inhibitor both in vitro and in vivo. Our findings may have implications for individualized therapy for patients with PTEN-deficient tumors. PMID:23888040

  5. A tumor suppressor function for the lipid phosphatase INPP4B in melanocytic neoplasms.

    PubMed

    Perez-Lorenzo, Rolando; Gill, Kamraan Z; Shen, Che-Hung; Zhao, Feng X; Zheng, Bin; Schulze, Hans-Joachim; Silvers, David N; Brunner, Georg; Horst, Basil A

    2014-05-01

    The phosphoinositide-3 kinase (PI3K) pathway is deregulated in a significant proportion of melanomas, and PI3K pathway activation in combination with constitutively active mitogen-activated protein kinase signaling shows synergistic effects in the process of melanoma tumorigenesis. Recently, a tumor suppressor function for the lipid phosphatase inositol polyphosphate 4-phosphatase type II (INPP4B) has been described in breast and prostate cancers, with impact on PI3K signaling output. Given the importance of PI3K pathway activity for melanoma formation and growth, we aimed to assess the role of INPP4B in melanocytic tumors. Our studies in native tumors suggest that decreased INPP4B expression is an event correlating with tumor progression in melanocytic neoplasms. We further demonstrate that INPP4B regulates PI3K/Akt signaling and exerts a tumor suppressor effect, impacting the proliferative, invasive, and tumorigenic capacity of melanoma cells. INPP4B expression in melanocytic neoplasms may therefore have potential as a biomarker for disease progression and as a modulator for the prediction of treatment outcome.

  6. Transcript Abundance of Putative Lipid Phosphate Phosphatases During Development of Trypanosoma brucei in the Tsetse Fly.

    PubMed

    Alves e Silva, Thiago Luiz; Savage, Amy F; Aksoy, Serap

    2016-04-01

    African trypanosomes (Trypanosoma brucei spp.) cause devastating diseases in sub-Saharan Africa. Trypanosomes differentiate repeatedly during development in tsetse flies before gaining mammalian infectivity in fly salivary glands. Lipid phosphate phosphatases (LPPs) are involved in diverse biological processes, such as cell differentiation and cell migration. Gene sequences encoding two putative T. brucei LPP proteins were used to search the T. brucei genome, revealing two additional putative family members. Putative structural features and transcript abundance during parasite development in tsetse fly were characterized. Three of the four LPP proteins are predicted to have six transmembrane domains, while the fourth shows only one. Semiquantitative gene expression revealed differential regulation of LPPs during parasite development. Transcript abundance for three of the four putative LPP genes was elevated in parasites infecting salivary glands, but not mammalian-infective metacyclic cells in fly saliva, indicating a potential role of this family in parasite establishment in tsetse salivary glands.

  7. Behavioral abnormalities in mice lacking mesenchyme-specific Pten.

    PubMed

    Borniger, Jeremy C; Cissé, Yasmine M; Cantemir-Stone, Carmen Z; Bolon, Brad; Nelson, Randy J; Marsh, Clay B

    2016-05-01

    Phosphatase and tensin homolog (Pten) is a negative regulator of cell proliferation and growth. Using a Cre-recombinase approach with Lox sequences flanking the fibroblast-specific protein 1 (Fsp1 aka S100A4; a mesenchymal marker), we probed sites of expression using a β-galactosidase Rosa26(LoxP) reporter allele; the transgene driving deletion of Pten (exons 4-5) was found throughout the brain parenchyma and pituitary, suggesting that deletion of Pten in Fsp1-positive cells may influence behavior. Because CNS-specific deletion of Pten influences social and anxiety-like behaviors and S100A4 is expressed in astrocytes, we predicted that loss of Pten in Fsp1-expressing cells would result in deficits in social interaction and increased anxiety. We further predicted that environmental enrichment would compensate for genetic deficits in these behaviors. We conducted a battery of behavioral assays on Fsp1-Cre;Pten(LoxP/LoxP) male and female homozygous knockouts (Pten(-/-)) and compared their behavior to Pten(LoxP/LoxP) (Pten(+/+)) conspecifics. Despite extensive physical differences (including reduced hippocampal size) and deficits in sensorimotor function, Pten(-/-) mice behaved remarkably similar to control mice on nearly all behavioral tasks. These results suggest that the social and anxiety-like phenotypes observed in CNS-specific Pten(-/-) mice may depend on neuronal Pten, as lack of Pten in Fsp1-expressing cells of the CNS had little effect on these behaviors.

  8. Tetracyclines increase lipid phosphate phosphatase expression on plasma membranes and turnover of plasma lysophosphatidate.

    PubMed

    Tang, Xiaoyun; Zhao, Yuan Y; Dewald, Jay; Curtis, Jonathan M; Brindley, David N

    2016-04-01

    Extracellular lysophosphatidate and sphingosine 1-phosphate (S1P) are important bioactive lipids, which signal through G-protein-coupled receptors to stimulate cell growth and survival. The lysophosphatidate and S1P signals are terminated partly by degradation through three broad-specificity lipid phosphate phosphatases (LPPs) on the cell surface. Significantly, the expression of LPP1 and LPP3 is decreased in many cancers, and this increases the impact of lysophosphatidate and S1P signaling. However, relatively little is known about the physiological or pharmacological regulation of the expression of the different LPPs. We now show that treating several malignant and nonmalignant cell lines with 1 μg/ml tetracycline, doxycycline, or minocycline significantly increased the extracellular degradation of lysophosphatidate. S1P degradation was also increased in cells that expressed high LPP3 activity. These results depended on an increase in the stabilities of the three LPPs and increased expression on the plasma membrane. We tested the physiological significance of these results and showed that treating rats with doxycycline accelerated the clearance of lysophosphatidate, but not S1P, from the circulation. However, administering 100 mg/kg/day doxycycline to mice decreased plasma concentrations of lysophosphatidate and S1P. This study demonstrates a completely new property of tetracyclines in increasing the plasma membrane expression of the LPPs.

  9. High concentrations of H2O2 trigger hypertrophic cascade and phosphatase and tensin homologue (PTEN) glutathionylation in H9c2 cardiomyocytes.

    PubMed

    Panera, Nadia; Gnani, Daniela; Piermarini, Emanuela; Petrini, Stefania; Bertini, Enrico; Nobili, Valerio; Pastore, Anna; Piemonte, Fiorella; Alisi, Anna

    2016-02-01

    Cardiac hypertrophy occurs in response to different stimuli and is mainly characterized by an enlargement of cardiomyocyte size. During hypertrophy, cardiomyocytes undergo not only radical changes of the cellular architecture but also activation of signaling cascades that counteract the atrophy genes. Experimental studies highlighted that chronic low concentrations of H2O2, induce a hypertrophic phenotype, while higher levels of H2O2 promote apoptosis. In this study, we explored the early and long-term hypertrophic effects of high concentrations of H2O2 on H9c2 rat cardiomyocytes. We found that 2-h stimulation with 200μM H2O2 caused an early dramatic reduction of cell viability, accompanied, 5-days later, by increased cell size and up-regulation of atrial natriuretic peptide transcription. This hypertrophic phenotype is associated to increased Akt phosphorylation and a consequent reduction of the FOXO3a and atrogin-1 gene expression. Moreover, we observed that H2O2 caused the overexpression of miR-212/miR-132 cluster concomitantly to a down-regulation of PTEN transcript without changes in its protein expression. Noteworthy, we found that the treatment of cardiomyocytes with H2O2 further led to an increase of oxidized glutathione and glutathionylation of proteins, including PTEN. In conclusion, our results permit to reconstruct the molecular cascade triggering the cardiomyocyte hypertrophy upon high concentrations of H2O2.

  10. High concentrations of H2O2 trigger hypertrophic cascade and phosphatase and tensin homologue (PTEN) glutathionylation in H9c2 cardiomyocytes.

    PubMed

    Panera, Nadia; Gnani, Daniela; Piermarini, Emanuela; Petrini, Stefania; Bertini, Enrico; Nobili, Valerio; Pastore, Anna; Piemonte, Fiorella; Alisi, Anna

    2016-02-01

    Cardiac hypertrophy occurs in response to different stimuli and is mainly characterized by an enlargement of cardiomyocyte size. During hypertrophy, cardiomyocytes undergo not only radical changes of the cellular architecture but also activation of signaling cascades that counteract the atrophy genes. Experimental studies highlighted that chronic low concentrations of H2O2, induce a hypertrophic phenotype, while higher levels of H2O2 promote apoptosis. In this study, we explored the early and long-term hypertrophic effects of high concentrations of H2O2 on H9c2 rat cardiomyocytes. We found that 2-h stimulation with 200μM H2O2 caused an early dramatic reduction of cell viability, accompanied, 5-days later, by increased cell size and up-regulation of atrial natriuretic peptide transcription. This hypertrophic phenotype is associated to increased Akt phosphorylation and a consequent reduction of the FOXO3a and atrogin-1 gene expression. Moreover, we observed that H2O2 caused the overexpression of miR-212/miR-132 cluster concomitantly to a down-regulation of PTEN transcript without changes in its protein expression. Noteworthy, we found that the treatment of cardiomyocytes with H2O2 further led to an increase of oxidized glutathione and glutathionylation of proteins, including PTEN. In conclusion, our results permit to reconstruct the molecular cascade triggering the cardiomyocyte hypertrophy upon high concentrations of H2O2. PMID:26772165

  11. Discovery and optimization of new benzimidazole- and benzoxazole-pyrimidone selective PI3Kβ inhibitors for the treatment of phosphatase and TENsin homologue (PTEN)-deficient cancers.

    PubMed

    Certal, Victor; Halley, Frank; Virone-Oddos, Angela; Delorme, Cécile; Karlsson, Andreas; Rak, Alexey; Thompson, Fabienne; Filoche-Rommé, Bruno; El-Ahmad, Youssef; Carry, Jean-Christophe; Abecassis, Pierre-Yves; Lejeune, Pascale; Vincent, Loic; Bonnevaux, Hélène; Nicolas, Jean-Paul; Bertrand, Thomas; Marquette, Jean-Pierre; Michot, Nadine; Benard, Tsiala; Below, Peter; Vade, Isabelle; Chatreaux, Fabienne; Lebourg, Gilles; Pilorge, Fabienne; Angouillant-Boniface, Odile; Louboutin, Audrey; Lengauer, Christoph; Schio, Laurent

    2012-05-24

    Most of the phosphoinositide-3 kinase (PI3K) kinase inhibitors currently in clinical trials for cancer treatment exhibit pan PI3K isoform profiles. Single PI3K isoforms differentially control tumorigenesis, and PI3Kβ has emerged as the isoform involved in the tumorigenicity of PTEN-deficient tumors. Herein we describe the discovery and optimization of a new series of benzimidazole- and benzoxazole-pyrimidones as small molecular mass PI3Kβ-selective inhibitors. Starting with compound 5 obtained from a one-pot reaction via a novel intermediate 1, medicinal chemistry optimization led to the discovery of compound 8, which showed a significant activity and selectivity for PI3Kβ and adequate in vitro pharmacokinetic properties. The X-ray costructure of compound 8 in PI3Kδ showed key interactions and structural features supporting the observed PI3Kβ isoform selectivity. Compound 8 achieved sustained target modulation and tumor growth delay at well tolerated doses when administered orally to SCID mice implanted with PTEN-deficient human tumor xenografts.

  12. The role of phosphoinositide-3 kinase and PTEN in cardiovascular physiology and disease.

    PubMed

    Oudit, Gavin Y; Sun, Hui; Kerfant, Benoit-Gilles; Crackower, Michael A; Penninger, Josef M; Backx, Peter H

    2004-08-01

    Phosphoinositide-3 kinases (PI3Ks) are a family of evolutionary conserved lipid kinases that mediate many cellular responses in both physiologic and pathophysiologic states. Class I PI3K can be activated by either receptor tyrosine kinase (RTK)/cytokine receptor activation (class I(A)) or G-protein-coupled receptors (GPCR) (class I(B)). Once activated PI3Ks generate phosphatidylinositols (PtdIns) (3,4,5)P(3) leading to the recruitment and activation of Akt/protein kinase B (PKB), PDK1 and monomeric G-proteins (e.g. Rac-GTPases), which then activate a range of downstream targets including glycogen synthase kinase-3beta (GSK-3beta), mammalian target of rapamycin (mTOR), p70S6 kinase, endothelial nitric oxide synthase (eNOS) and several anti-apoptotic effectors. Class I(A) (PI3Kalpha, beta and delta) and class I(B) (PI3Kgamma) PI3Ks mediate distinct phenotypes in the heart and under negative control by the 3'-lipid phosphatase, phosphatase and tensin homolog on chromosome ten (PTEN) which dephosphorylate PtdIns(3,4,5)P(3) into PtdIns(4,5)P(2). PI3Kalpha, gamma and PTEN are expressed in cardiomyocytes, fibroblasts, endothelial cells and vascular smooth muscle cells where they modulate cell survival/apoptosis, hypertrophy, contractility, metabolism and mechanotransduction. Several transgenic and knockout models support a fundamental role of PI3K/PTEN signaling in the regulation of myocardial contractility and hypertrophy. Consequently the PI3K/PTEN signaling pathways are involved in a wide variety of diseases including cardiac hypertrophy, heart failure, preconditioning and hypertension. In this review, we discuss the biochemistry and molecular biology of PI3K (class I isoforms) and PTEN and their critical role in cardiovascular physiology and diseases.

  13. LipA, a Tyrosine and Lipid Phosphatase Involved in the Virulence of Listeria monocytogenes ▿ †

    PubMed Central

    Kastner, Renate; Dussurget, Olivier; Archambaud, Cristel; Kernbauer, Elisabeth; Soulat, Didier; Cossart, Pascale; Decker, Thomas

    2011-01-01

    Intracellular bacterial pathogens manipulate host cell functions by producing enzymes that stimulate or antagonize signal transduction. The Listeria monocytogenes genome contains a gene, lmo1800, encoding a protein with a conserved motif of conventional tyrosine phosphatases. Here, we report that the lmo1800-encoded protein LipA is secreted by Listeria and displays tyrosine as well as lipid phosphatase activity in vitro. Bacteria lacking LipA are severely attenuated in virulence in vivo, thus revealing a so-far-undescribed enzymatic activity involved in Listeria infection. PMID:21444667

  14. Quantitative and dynamic analysis of PTEN phosphorylation by NMR.

    PubMed

    Cordier, Florence; Chaffotte, Alain; Wolff, Nicolas

    2015-05-01

    The dual lipid and protein phosphatase PTEN is a tumor suppressor controlling key biological processes, such as cell growth, proliferation and neuro-survival. Its activity and intracellular trafficking is finely regulated notably by multi-site phosphorylation of its C-terminal tail. The reversible and highly dynamic character of these regulatory events confers a temporal dimension to the cell for triggering crucial decisions. In this review, we describe how a recently developed time-resolved NMR spectroscopy approach unveils the dynamic establishment of the phosphorylation events of PTEN C-terminal tail controlled by CK2 and GSK3β kinases. Two cascades of reactions have been identified, in vitro and in extracts of human neuroblastoma cells. They are triggered independently on two nearby clusters of sites (S380-S385 and S361-S370) and occur on different timescales. In each cascade, the reactions follow an ordered model with a distributive kinetic mechanism. The vision of these cascades as two delay timers activating distinct or time-delayed regulatory responses gives a temporal dimension on PTEN regulation and is discussed in relation to the known functional roles of each cluster. PMID:25449899

  15. Nuclear PTEN tumor-suppressor functions through maintaining heterochromatin structure.

    PubMed

    Gong, Lili; Govan, Jeane M; Evans, Elizabeth B; Dai, Hui; Wang, Edward; Lee, Szu-Wei; Lin, Hui-Kuan; Lazar, Alexander J; Mills, Gordon B; Lin, Shiaw-Yih

    2015-01-01

    The tumor suppressor, PTEN, is one of the most commonly mutated genes in cancer. Recently, PTEN has been shown to localize in the nucleus and is required to maintain genomic stability. Here, we show that nuclear PTEN, independent of its phosphatase activity, is essential for maintaining heterochromatin structure. Depletion of PTEN leads to loss of heterochromatic foci, decreased chromatin compaction, overexpression of heterochromatic genes, and reduced protein stability of heterochromatin protein 1 α. We found that the C-terminus of PTEN is required to maintain heterochromatin structure. Additionally, cancer-associated PTEN mutants lost their tumor-suppressor function when their heterochromatin structure was compromised. We propose that this novel role of PTEN accounts for its function in guarding genomic stability and suppressing tumor development. PMID:25946202

  16. Nuclear PTEN tumor-suppressor functions through maintaining heterochromatin structure

    PubMed Central

    Gong, Lili; Govan, Jeane M; Evans, Elizabeth B; Dai, Hui; Wang, Edward; Lee, Szu-Wei; Lin, Hui-Kuan; Lazar, Alexander J; Mills, Gordon B; Lin, Shiaw-Yih

    2015-01-01

    The tumor suppressor, PTEN, is one of the most commonly mutated genes in cancer. Recently, PTEN has been shown to localize in the nucleus and is required to maintain genomic stability. Here, we show that nuclear PTEN, independent of its phosphatase activity, is essential for maintaining heterochromatin structure. Depletion of PTEN leads to loss of heterochromatic foci, decreased chromatin compaction, overexpression of heterochromatic genes, and reduced protein stability of heterochromatin protein 1 α. We found that the C-terminus of PTEN is required to maintain heterochromatin structure. Additionally, cancer-associated PTEN mutants lost their tumor-suppressor function when their heterochromatin structure was compromised. We propose that this novel role of PTEN accounts for its function in guarding genomic stability and suppressing tumor development. PMID:25946202

  17. Brain patterning perturbations following PTEN loss

    PubMed Central

    Veleva-Rotse, Biliana O.; Barnes, Anthony P.

    2014-01-01

    This review will consider the impact of compromised PTEN signaling in brain patterning. We approach understanding the contribution of PTEN to nervous system development by surveying the findings from the numerous genetic loss-of-function models that have been generated as well as other forms of PTEN inactivation. By exploring the developmental programs influenced by this central transduction molecule, we can begin to understand the molecular mechanisms that shape the developing brain. A wealth of data indicates that PTEN plays critical roles in a variety of stages during brain development. Many of them are considered here including: stem cell proliferation, fate determination, polarity, migration, process outgrowth, myelination and somatic hypertrophy. In many of these contexts, it is clear that PTEN phosphatase activity contributes to the observed effects of genetic deletion or depletion, however recent studies have also ascribed non-catalytic functions to PTEN in regulating cell function. We also explore the potential impact this alternative pool of PTEN may have on the developing brain. Together, these elements begin to form a clearer picture of how PTEN contributes to the emergence of brain structure and binds form and function in the nervous system. PMID:24860420

  18. Altered Lipid Synthesis by Lack of Yeast Pah1 Phosphatidate Phosphatase Reduces Chronological Life Span.

    PubMed

    Park, Yeonhee; Han, Gil-Soo; Mileykovskaya, Eugenia; Garrett, Teresa A; Carman, George M

    2015-10-16

    In Saccharomyces cerevisiae, Pah1 phosphatidate phosphatase, which catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol, plays a crucial role in the synthesis of the storage lipid triacylglycerol. This evolutionarily conserved enzyme also plays a negative regulatory role in controlling de novo membrane phospholipid synthesis through its consumption of phosphatidate. We found that the pah1Δ mutant was defective in the utilization of non-fermentable carbon sources but not in oxidative phosphorylation; the mutant did not exhibit major changes in oxygen consumption rate, mitochondrial membrane potential, F1F0-ATP synthase activity, or gross mitochondrial morphology. The pah1Δ mutant contained an almost normal complement of major mitochondrial phospholipids with some alterations in molecular species. Although oxidative phosphorylation was not compromised in the pah1Δ mutant, the cellular levels of ATP in quiescent cells were reduced by 2-fold, inversely correlating with a 4-fold increase in membrane phospholipids. In addition, the quiescent pah1Δ mutant cells had 3-fold higher levels of mitochondrial superoxide and cellular lipid hydroperoxides, had reduced activities of superoxide dismutase 2 and catalase, and were hypersensitive to hydrogen peroxide. Consequently, the pah1Δ mutant had a shortened chronological life span. In addition, the loss of Tsa1 thioredoxin peroxidase caused a synthetic growth defect with the pah1Δ mutation. The shortened chronological life span of the pah1Δ mutant along with its growth defect on non-fermentable carbon sources and hypersensitivity to hydrogen peroxide was suppressed by the loss of Dgk1 diacylglycerol kinase, indicating that the underpinning of pah1Δ mutant defects was the excess synthesis of membrane phospholipids. PMID:26338708

  19. Phosphatase and Tensin Homolog Is a Growth Repressor of Both Rhizoid and Gametophore Development in the Moss Physcomitrella patens.

    PubMed

    Saavedra, Laura; Catarino, Rita; Heinz, Tobias; Heilmann, Ingo; Bezanilla, Magdalena; Malhó, Rui

    2015-12-01

    Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a lipid phosphatase implicated in cellular proliferation and survival. In animal cells, loss of PTEN leads to increased levels of phosphatidylinositol (3,4,5)-trisphosphate, stimulation of glucose and lipid metabolism, cellular growth, and morphological changes (related to adaptation and survival). Intriguingly, in plants, phosphatidylinositol (3,4,5)-trisphosphate has not been detected, and the enzymes that synthesize it were never reported. In this study we performed a genetic, biochemical, and functional characterization of the moss Physcomitrella patens PTEN gene family. P. patens has four PTENs, which are ubiquitously expressed during the entire moss life cycle. Using a knock-in approach, we show that all four genes are expressed in growing tissues, namely caulonemal and rhizoid cells. At the subcellular level, PpPTEN-green fluorescent protein fusions localized to the cytosol and the nucleus. Analysis of single and double knockouts revealed no significant phenotypes at different developmental stages, indicative of functional redundancy. However, compared with wild-type triple and quadruple pten knockouts, caulonemal cells grew faster, switched from the juvenile protonemal stage to adult gametophores earlier, and produced more rhizoids. Furthermore, analysis of lipid content and quantitative real-time polymerase chain reaction data performed in quadruple mutants revealed altered phosphoinositide levels [increase in phosphatidylinositol (3,5)-bisphosphate and decrease in phosphatidylinositol 3-phosphate] and up-regulation of marker genes from the synthesis phase of the cell cycle (e.g. P. patens proliferating cell nuclear antigen, ribonucleotide reductase, and minichromosome maintenance) and of the retinoblastoma-related protein gene P. patens retinoblastoma-related protein1. Together, these results suggest that PpPTEN is a suppressor of cell growth and morphogenic development in plants.

  20. Dynamic formation of ER-PM junctions presents a lipid phosphatase to regulate phosphoinositides.

    PubMed

    Dickson, Eamonn J; Jensen, Jill B; Vivas, Oscar; Kruse, Martin; Traynor-Kaplan, Alexis E; Hille, Bertil

    2016-04-11

    Endoplasmic reticulum-plasma membrane (ER-PM) contact sites play an integral role in cellular processes such as excitation-contraction coupling and store-operated calcium entry (SOCE). Another ER-PM assembly is one tethered by the extended synaptotagmins (E-Syt). We have discovered that at steady state, E-Syt2 positions the ER and Sac1, an integral ER membrane lipid phosphatase, in discrete ER-PM junctions. Here, Sac1 participates in phosphoinositide homeostasis by limiting PM phosphatidylinositol 4-phosphate (PI(4)P), the precursor of PI(4,5)P2 Activation of G protein-coupled receptors that deplete PM PI(4,5)P2disrupts E-Syt2-mediated ER-PM junctions, reducing Sac1's access to the PM and permitting PM PI(4)P and PI(4,5)P2to recover. Conversely, depletion of ER luminal calcium and subsequent activation of SOCE increases the amount of Sac1 in contact with the PM, depleting PM PI(4)P. Thus, the dynamic presence of Sac1 at ER-PM contact sites allows it to act as a cellular sensor and controller of PM phosphoinositides, thereby influencing many PM processes. PMID:27044890

  1. Proposed carrier lipid-binding site of undecaprenyl pyrophosphate phosphatase from Escherichia coli.

    PubMed

    Chang, Hsin-Yang; Chou, Chia-Cheng; Hsu, Min-Feng; Wang, Andrew H J

    2014-07-01

    Undecaprenyl pyrophosphate phosphatase (UppP), an integral membrane protein, catalyzes the dephosphorylation of undecaprenyl pyrophosphate to undecaprenyl phosphate, which is an essential carrier lipid in the bacterial cell wall synthesis. Sequence alignment reveals two consensus regions, containing glutamate-rich (E/Q)XXXE plus PGXSRSXXT motifs and a histidine residue, specific to the bacterial UppP enzymes. The predicted topological model suggests that both of these regions are localized near the aqueous interface of UppP and face the periplasm, implicating that its enzymatic function is on the outer side of the plasma membrane. The mutagenesis analysis demonstrates that most of the mutations (E17A/E21A, H30A, S173A, R174A, and T178A) within the consensus regions are completely inactive, indicating that the catalytic site of UppP is constituted by these two regions. Enzymatic analysis also shows an absolute requirement of magnesium or calcium ions in enzyme activity. The three-dimensional structural model and molecular dynamics simulation studies have shown a plausible structure of the catalytic site of UppP and thus provides insights into the molecular basis of the enzyme-substrate interaction in membrane bilayers. PMID:24855653

  2. Dynamic formation of ER–PM junctions presents a lipid phosphatase to regulate phosphoinositides

    PubMed Central

    Jensen, Jill B.; Vivas, Oscar; Kruse, Martin; Traynor-Kaplan, Alexis E.; Hille, Bertil

    2016-01-01

    Endoplasmic reticulum–plasma membrane (ER–PM) contact sites play an integral role in cellular processes such as excitation–contraction coupling and store-operated calcium entry (SOCE). Another ER–PM assembly is one tethered by the extended synaptotagmins (E-Syt). We have discovered that at steady state, E-Syt2 positions the ER and Sac1, an integral ER membrane lipid phosphatase, in discrete ER–PM junctions. Here, Sac1 participates in phosphoinositide homeostasis by limiting PM phosphatidylinositol 4-phosphate (PI(4)P), the precursor of PI(4,5)P2. Activation of G protein–coupled receptors that deplete PM PI(4,5)P2 disrupts E-Syt2–mediated ER–PM junctions, reducing Sac1’s access to the PM and permitting PM PI(4)P and PI(4,5)P2 to recover. Conversely, depletion of ER luminal calcium and subsequent activation of SOCE increases the amount of Sac1 in contact with the PM, depleting PM PI(4)P. Thus, the dynamic presence of Sac1 at ER–PM contact sites allows it to act as a cellular sensor and controller of PM phosphoinositides, thereby influencing many PM processes. PMID:27044890

  3. Lipid phosphate phosphatase-1 expression in cancer cells attenuates tumor growth and metastasis in mice.

    PubMed

    Tang, Xiaoyun; Benesch, Matthew G K; Dewald, Jay; Zhao, Yuan Y; Patwardhan, Neeraj; Santos, Webster L; Curtis, Jonathan M; McMullen, Todd P W; Brindley, David N

    2014-11-01

    Lipid phosphate phosphatase-1 (LPP1) degrades lysophosphatidate (LPA) and attenuates receptor-mediated signaling. LPP1 expression is low in many cancer cells and tumors compared with normal tissues. It was hypothesized from studies with cultured cells that increasing LPP1 activity would decrease tumor growth and metastasis. This hypothesis has never been tested in vivo. To do this, we inducibly expressed LPP1 or a catalytically inactive mutant in cancer cells. Expressing active LPP1 increased extracellular LPA degradation by 5-fold. It also decreased the stimulation of Ca(2+) transients by LPA, a nondephosphorylatable LPA1/2 receptor agonist and a protease-activated receptor-1 peptide. The latter results demonstrate that LPP1 has effects downstream of receptor activation. Decreased Ca(2+) mobilization and Rho activation contributed to the effects of LPP1 in attenuating the LPA-induced migration of MDA-MB-231 breast cancer cells and their growth in 3D culture. Increasing LPP1 expression in breast and thyroid cancer cells decreased tumor growth and the metastasis by up to 80% compared with expression of inactive LPP1 or green fluorescent protein in syngeneic and xenograft mouse models. The present work demonstrates for the first time that increasing the LPP1 activity in three lines of aggressive cancer cells decreases their abilities to produce tumors and metastases in mice. PMID:25210149

  4. The First Transmembrane Domain of Lipid Phosphatase SAC1 Promotes Golgi Localization

    PubMed Central

    Wang, Jinzhi; Chen, Juxing; Enns, Caroline A.; Mayinger, Peter

    2013-01-01

    The lipid phosphatase Sac1 cycles between endoplasmic reticulum and cisternal Golgi compartments. In proliferating mammalian cells, a canonical dilysine motif at the C-terminus of Sac1 is required for coatomer complex-I (COP-I)-binding and continuous retrieval to the ER. Starvation triggers accumulation of Sac1 at the Golgi. The mechanism responsible for Golgi retention of Sac1 is unknown. Here we show that the first of the two transmembrane regions in human SAC1 (TM1) functions in Golgi localization. A minimal construct containing only TM1 and the adjacent flanking sequences is concentrated at the Golgi. Transplanting TM1 into transferrin receptor 2 (TfR2) induces Golgi accumulation of this normally plasma membrane and endosomal protein, indicating that TM1 is sufficient for Golgi localization. In addition, we determined that the N-terminal cytoplasmic domain of SAC1 also promotes Golgi localization, even when TM1 is mutated or absent. We conclude that the distribution of SAC1 within the Golgi is controlled via both passive membrane thickness-dependent partitioning of TM1 and a retention mechanism that requires the N-terminal cytoplasmic region. PMID:23936490

  5. PTEN functions by recruitment to cytoplasmic vesicles.

    PubMed

    Naguib, Adam; Bencze, Gyula; Cho, Hyejin; Zheng, Wu; Tocilj, Ante; Elkayam, Elad; Faehnle, Christopher R; Jaber, Nadia; Pratt, Christopher P; Chen, Muhan; Zong, Wei-Xing; Marks, Michael S; Joshua-Tor, Leemor; Pappin, Darryl J; Trotman, Lloyd C

    2015-04-16

    PTEN is proposed to function at the plasma membrane, where receptor tyrosine kinases are activated. However, the majority of PTEN is located throughout the cytoplasm. Here, we show that cytoplasmic PTEN is distributed along microtubules, tethered to vesicles via phosphatidylinositol 3-phosphate (PI(3)P), the signature lipid of endosomes. We demonstrate that the non-catalytic C2 domain of PTEN specifically binds PI(3)P through the CBR3 loop. Mutations render this loop incapable of PI(3)P binding and abrogate PTEN-mediated inhibition of PI 3-kinase/AKT signaling. This loss of function is rescued by fusion of the loop mutant PTEN to FYVE, the canonical PI(3)P binding domain, demonstrating the functional importance of targeting PTEN to endosomal membranes. Beyond revealing an upstream activation mechanism of PTEN, our data introduce the concept of PI 3-kinase signal activation on the vast plasma membrane that is contrasted by PTEN-mediated signal termination on the small, discrete surfaces of internalized vesicles. PMID:25866245

  6. Structural Insight into Substrate Selection and Catalysis of Lipid Phosphate Phosphatase PgpB in the Cell Membrane.

    PubMed

    Tong, Shuilong; Lin, Yibin; Lu, Shuo; Wang, Meitian; Bogdanov, Mikhail; Zheng, Lei

    2016-08-26

    PgpB belongs to the lipid phosphate phosphatase protein family and is one of three bacterial integral membrane phosphatases catalyzing dephosphorylation of phosphatidylglycerol phosphate (PGP) to generate phosphatidylglycerol. Although the structure of its apo form became recently available, the mechanisms of PgpB substrate binding and catalysis are still unclear. We found that PgpB was inhibited by phosphatidylethanolamine (PE) in a competitive mode in vitro Here we report the crystal structure of the lipid-bound form of PgpB. The structure shows that a PE molecule is stabilized in a membrane-embedded tunnel formed by TM3 and the "PSGH" fingerprint peptide near the catalytic site, providing structural insight into PgpB substrate binding mechanism. Noteworthy, in silico docking of varied lipid phosphates exhibited similar substrate binding modes to that of PE, and the residues in the lipid tunnel appear to be important for PgpB catalysis. The catalytic triad in the active site is essential for dephosphorylating substrates lysophosphatidic acid, phosphatidic acid, or sphingosine-1-phosphate but surprisingly not for the native substrate PGP. Remarkably, residue His-207 alone is sufficient to hydrolyze PGP, indicating a specific catalytic mechanism for PgpB in PG biosynthesis. We also identified two novel sensor residues, Lys-93 and Lys-97, on TM3. Our data show that Lys-97 is essential for the recognition of lyso-form substrates. Modification at the Lys-93 position may alter substrate specificity of lipid phosphate phosphatase proteins in prokaryotes versus eukaryotes. These studies reveal new mechanisms of lipid substrate selection and catalysis by PgpB and suggest that the enzyme rests in a PE-stabilized state in the bilayer. PMID:27405756

  7. High-resolution Structures of Protein-Membrane Complexes by Neutron Reflection and MD Simulation: Membrane Association of the PTEN Tumor Suppressor

    NASA Astrophysics Data System (ADS)

    Lösche, Matthias

    2012-02-01

    The lipid matrix of biomembranes is an in-plane fluid, thermally and compositionally disordered leaflet of 5 nm thickness and notoriously difficult to characterize in structural terms. Yet, biomembranes are ubiquitous in the cell, and membrane-bound proteins are implicated in a variety of signaling pathways and intra-cellular transport. We developed methodology to study proteins associated with model membranes using neutron reflection measurements and showed recently that this approach can resolve the penetration depth and orientation of membrane proteins with ångstrom resolution if their crystal or NMR structure is known. Here we apply this technology to determine the membrane bindung and unravel functional details of the PTEN phosphatase, a key player in the PI3K apoptosis pathway. PTEN is an important regulatory protein and tumor suppressor that performs its phosphatase activity as an interfacial enzyme at the plasma membrane-cytoplasm boundary. Acting as an antagonist to phosphoinositide-3-kinase (PI3K) in cell signaling, it is deleted in many human cancers. Despite its importance in regulating the levels of the phosphoinositoltriphosphate PI(3,4,5)P3, there is little understanding of how PTEN binds to membranes, is activated and then acts as a phosphatase. We investigated the structure and function of PTEN by studying its membrane affinity and localization on in-plane fluid, thermally disordered synthetic membrane models. The membrane association of the protein depends strongly on membrane composition, where phosphatidylserine (PS) and phosphatidylinositol diphosphate (PI(4,5)P2) act synergetically in attracting the enzyme to the membrane surface. Membrane affinities depend strongly on membrane fluidity, which suggests multiple binding sites on the protein for PI(4,5)P2. Neutron reflection measurements show that the PTEN phosphatase ``scoots'' along the membrane surface (penetration < 5 å) but binds the membrane tightly with its two major domains, the C2 and

  8. A functional dissection of PTEN N-terminus: implications in PTEN subcellular targeting and tumor suppressor activity.

    PubMed

    Gil, Anabel; Rodríguez-Escudero, Isabel; Stumpf, Miriam; Molina, María; Cid, Víctor J; Pulido, Rafael

    2015-01-01

    Spatial regulation of the tumor suppressor PTEN is exerted through alternative plasma membrane, cytoplasmic, and nuclear subcellular locations. The N-terminal region of PTEN is important for the control of PTEN subcellular localization and function. It contains both an active nuclear localization signal (NLS) and an overlapping PIP2-binding motif (PBM) involved in plasma membrane targeting. We report a comprehensive mutational and functional analysis of the PTEN N-terminus, including a panel of tumor-related mutations at this region. Nuclear/cytoplasmic partitioning in mammalian cells and PIP3 phosphatase assays in reconstituted S. cerevisiae defined categories of PTEN N-terminal mutations with distinct PIP3 phosphatase and nuclear accumulation properties. Noticeably, most tumor-related mutations that lost PIP3 phosphatase activity also displayed impaired nuclear localization. Cell proliferation and soft-agar colony formation analysis in mammalian cells of mutations with distinctive nuclear accumulation and catalytic activity patterns suggested a contribution of both properties to PTEN tumor suppressor activity. Our functional dissection of the PTEN N-terminus provides the basis for a systematic analysis of tumor-related and experimentally engineered PTEN mutations.

  9. A Functional Dissection of PTEN N-Terminus: Implications in PTEN Subcellular Targeting and Tumor Suppressor Activity

    PubMed Central

    Gil, Anabel; Rodríguez-Escudero, Isabel; Stumpf, Miriam; Molina, María; Cid, Víctor J.; Pulido, Rafael

    2015-01-01

    Spatial regulation of the tumor suppressor PTEN is exerted through alternative plasma membrane, cytoplasmic, and nuclear subcellular locations. The N-terminal region of PTEN is important for the control of PTEN subcellular localization and function. It contains both an active nuclear localization signal (NLS) and an overlapping PIP2-binding motif (PBM) involved in plasma membrane targeting. We report a comprehensive mutational and functional analysis of the PTEN N-terminus, including a panel of tumor-related mutations at this region. Nuclear/cytoplasmic partitioning in mammalian cells and PIP3 phosphatase assays in reconstituted S. cerevisiae defined categories of PTEN N-terminal mutations with distinct PIP3 phosphatase and nuclear accumulation properties. Noticeably, most tumor-related mutations that lost PIP3 phosphatase activity also displayed impaired nuclear localization. Cell proliferation and soft-agar colony formation analysis in mammalian cells of mutations with distinctive nuclear accumulation and catalytic activity patterns suggested a contribution of both properties to PTEN tumor suppressor activity. Our functional dissection of the PTEN N-terminus provides the basis for a systematic analysis of tumor-related and experimentally engineered PTEN mutations. PMID:25875300

  10. Effects of mir-21 on Cardiac Microvascular Endothelial Cells After Acute Myocardial Infarction in Rats: Role of Phosphatase and Tensin Homolog (PTEN)/Vascular Endothelial Growth Factor (VEGF) Signal Pathway

    PubMed Central

    Yang, Feng; Liu, Wenwei; Yan, Xiaojuan; Zhou, Hanyun; Zhang, Hongshen; Liu, Jianfei; Yu, Ming; Zhu, Xiaoshan; Ma, Kezhong

    2016-01-01

    Background This study investigated how miR-21 expression is reflected in acute myocardial infarction and explored the role of miR-21 and the PTEN/VEGF signaling pathway in cardiac microvascular endothelial cells. Material/Methods We used an in vivo LAD rat model to simulate acute myocardial infarction. MiR-21 mimics and miR-21 inhibitors were injected and transfected into model rats in order to alter miR-21 expression. Cardiac functions were evaluated using echocardiographic measurement, ELISA, and Masson staining. In addition, lenti-PTEN and VEGF siRNA were transfected into CMEC cells using standard procedures for assessing the effect of PTEN and VEGE on cell proliferation, apoptosis, and angiogenesis. MiR-21, PTEN, and VEGF expressions were examined by RT-PCR and Western blot. The relationship between miR-21 and PTEN was determined by the luciferase activity assay. Results We demonstrated that miR-21 bonded with the 3′-UTR of PTEN and suppressed PTEN expressions. Established models significantly induced cardiac infarct volume and endothelial injury marker expressions as well as miR-21 and PTEN expressions (P<0.05). MiR-21 mimics exhibited significantly protective effects since they down-regulated both infarction size and injury marker expressions by increasing VEGF expression and inhibiting PTEN expression (P<0.05). In addition, results from in vitro research show that lenti-PTEN and VEGF siRNA can notably antagonize the effect of miR-21 on cell proliferation, apoptosis, and angiogenesis (P<0.05). Conclusions MiR-21 exerts protective effects on endothelial injury through the PTEN/VEGF pathway after acute myocardial infarction. PMID:27708252

  11. Phosphatase and Tensin Homolog Is a Growth Repressor of Both Rhizoid and Gametophore Development in the Moss Physcomitrella patens1[OPEN

    PubMed Central

    Saavedra, Laura; Heilmann, Ingo

    2015-01-01

    Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a lipid phosphatase implicated in cellular proliferation and survival. In animal cells, loss of PTEN leads to increased levels of phosphatidylinositol (3,4,5)-trisphosphate, stimulation of glucose and lipid metabolism, cellular growth, and morphological changes (related to adaptation and survival). Intriguingly, in plants, phosphatidylinositol (3,4,5)-trisphosphate has not been detected, and the enzymes that synthesize it were never reported. In this study we performed a genetic, biochemical, and functional characterization of the moss Physcomitrella patens PTEN gene family. P. patens has four PTENs, which are ubiquitously expressed during the entire moss life cycle. Using a knock-in approach, we show that all four genes are expressed in growing tissues, namely caulonemal and rhizoid cells. At the subcellular level, PpPTEN-green fluorescent protein fusions localized to the cytosol and the nucleus. Analysis of single and double knockouts revealed no significant phenotypes at different developmental stages, indicative of functional redundancy. However, compared with wild-type triple and quadruple pten knockouts, caulonemal cells grew faster, switched from the juvenile protonemal stage to adult gametophores earlier, and produced more rhizoids. Furthermore, analysis of lipid content and quantitative real-time polymerase chain reaction data performed in quadruple mutants revealed altered phosphoinositide levels [increase in phosphatidylinositol (3,5)-bisphosphate and decrease in phosphatidylinositol 3-phosphate] and up-regulation of marker genes from the synthesis phase of the cell cycle (e.g. P. patens proliferating cell nuclear antigen, ribonucleotide reductase, and minichromosome maintenance) and of the retinoblastoma-related protein gene P. patens retinoblastoma-related protein1. Together, these results suggest that PpPTEN is a suppressor of cell growth and morphogenic development in plants. PMID

  12. Membrane Association of the PTEN Tumor Suppressor: Molecular Details of the Protein-Membrane Complex from SPR Binding Studies and Neutron Reflection

    PubMed Central

    Shenoy, Siddharth; Shekhar, Prabhanshu; Heinrich, Frank; Daou, Marie-Claire; Gericke, Arne; Ross, Alonzo H.; Lösche, Mathias

    2012-01-01

    The structure and function of the PTEN phosphatase is investigated by studying its membrane affinity and localization on in-plane fluid, thermally disordered synthetic membrane models. The membrane association of the protein depends strongly on membrane composition, where phosphatidylserine (PS) and phosphatidylinositol diphosphate (PI(4,5)P2) act pronouncedly synergistic in pulling the enzyme to the membrane surface. The equilibrium dissociation constants for the binding of wild type (wt) PTEN to PS and PI(4,5)P2 were determined to be Kd∼12 µM and 0.4 µM, respectively, and Kd∼50 nM if both lipids are present. Membrane affinities depend critically on membrane fluidity, which suggests multiple binding sites on the protein for PI(4,5)P2. The PTEN mutations C124S and H93R show binding affinities that deviate strongly from those measured for the wt protein. Both mutants bind PS more strongly than wt PTEN. While C124S PTEN has at least the same affinity to PI(4,5)P2 and an increased apparent affinity to PI(3,4,5)P3, due to its lack of catalytic activity, H93R PTEN shows a decreased affinity to PI(4,5)P2 and no synergy in its binding with PS and PI(4,5)P2. Neutron reflection measurements show that the PTEN phosphatase “scoots" along the membrane surface (penetration <5 Å) but binds the membrane tightly with its two major domains, the C2 and phosphatase domains, as suggested by the crystal structure. The regulatory C-terminal tail is most likely displaced from the membrane and organized on the far side of the protein, ∼60 Å away from the bilayer surface, in a rather compact structure. The combination of binding studies and neutron reflection allows us to distinguish between PTEN mutant proteins and ultimately may identify the structural features required for membrane binding and activation of PTEN. PMID:22505997

  13. Purification and Characterization of the Lipid A 1-Phosphatase LpxE of Rhizobium leguminosarum*S⃞

    PubMed Central

    Karbarz, Mark J.; Six, David A.; Raetz, Christian R. H.

    2009-01-01

    LpxE, a membrane-bound phosphatase found in Rhizobium leguminosarum and some other Gram-negative bacteria, selectively dephosphorylates the 1-position of lipid A on the outer surface of the inner membrane. LpxE belongs to the family of lipid phosphate phosphatases that contain a tripartite active site motif and six predicted transmembrane helices. Here we report the purification and characterization of R. leguminosarum LpxE. A modified lpxE gene, encoding a protein with an N-terminal His6 tag, was expressed in Escherichia coli. The protein was solubilized with Triton X-100 and purified to near-homogeneity. Gel electrophoresis reveals a molecular weight consistent with the predicted 31 kDa. LpxE activity is dependent upon Triton X-100, optimal near pH 6.5, and Mg2+-independent. The H197A and R133A substitutions inactivate LpxE, as does treatment with diethyl pyrocarbonate. In a mixed micelle assay system, the apparent Km for the precursor lipid IVA is 11 μm. Substrates containing the 3-deoxy-d-manno-oct-2-ulosonic acid disaccharide are dephosphorylated at similar rates to lipid IVA, whereas glycerophospholipids like phosphatidic acid or phosphatidylglycerol phosphate are very poor substrates. However, an LpxE homologue present in Agrobacterium tumefaciens is selective for phosphatidylglycerol phosphate, demonstrating the importance of determining substrate specificity before assigning the functions of LpxE-related proteins. The availability of purified LpxE will facilitate the preparation of novel 1-dephosphorylated lipid A molecules that are not readily accessible by chemical methods. PMID:18984595

  14. PTEN-PDZ domain interactions: binding of PTEN to PDZ domains of PTPN13.

    PubMed

    Sotelo, Natalia S; Schepens, Jan T G; Valiente, Miguel; Hendriks, Wiljan J A J; Pulido, Rafael

    2015-05-01

    Protein modular interactions mediated by PDZ domains are essential for the establishment of functional protein networks controlling diverse cellular functions. The tumor suppressor PTEN possesses a C-terminal PDZ-binding motif (PDZ-BM) that is recognized by a specific set of PDZ domains from scaffolding and regulatory proteins. Here, we review the current knowledge on PTEN-PDZ domain interactions and tumor suppressor networks, describe methodology suitable to analyze these interactions, and report the binding of PTEN and the PDZ domain-containing protein tyrosine phosphatase PTPN13. Yeast two-hybrid and GST pull-down analyses showed that PTEN binds to PDZ2/PTPN13 domain in a manner that depends on the specific PTPN13 PDZ domain arrangement involving the interdomain region between PDZ1 and PDZ2. Furthermore, a specific binding profile of PTEN to PDZ2/PTPN13 domain was observed by mutational analysis of the PTEN PDZ-BM. Our results disclose a PDZ-mediated physical interaction of PTEN and PTPN13 with potential relevance in tumor suppression and cell homeostasis.

  15. Phosphorylation of Yeast Pah1 Phosphatidate Phosphatase by Casein Kinase II Regulates Its Function in Lipid Metabolism.

    PubMed

    Hsieh, Lu-Sheng; Su, Wen-Min; Han, Gil-Soo; Carman, George M

    2016-05-01

    Pah1 phosphatidate phosphatase in Saccharomyces cerevisiae catalyzes the penultimate step in the synthesis of triacylglycerol (i.e. the production of diacylglycerol by dephosphorylation of phosphatidate). The enzyme playing a major role in lipid metabolism is subject to phosphorylation (e.g. by Pho85-Pho80, Cdc28-cyclin B, and protein kinases A and C) and dephosphorylation (e.g. by Nem1-Spo7) that regulate its cellular location, catalytic activity, and stability/degradation. In this work, we show that Pah1 is a substrate for casein kinase II (CKII); its phosphorylation was time- and dose-dependent and was dependent on the concentrations of Pah1 (Km = 0.23 μm) and ATP (Km = 5.5 μm). By mass spectrometry, truncation analysis, site-directed mutagenesis, phosphopeptide mapping, and phosphoamino acid analysis, we identified that >90% of its phosphorylation occurs on Thr-170, Ser-250, Ser-313, Ser-705, Ser-814, and Ser-818. The CKII-phosphorylated Pah1 was a substrate for the Nem1-Spo7 protein phosphatase and was degraded by the 20S proteasome. The prephosphorylation of Pah1 by protein kinase A or protein kinase C reduced its subsequent phosphorylation by CKII. The prephosphorylation of Pah1 by CKII reduced its subsequent phosphorylation by protein kinase A but not by protein kinase C. The expression of Pah1 with combined mutations of S705D and 7A, which mimic its phosphorylation by CKII and lack of phosphorylation by Pho85-Pho80, caused an increase in triacylglycerol content and lipid droplet number in cells expressing the Nem1-Spo7 phosphatase complex. PMID:27044741

  16. PTEN-inhibition by zinc ions augments interleukin-2-mediated Akt phosphorylation.

    PubMed

    Plum, Laura Marie; Brieger, Anne; Engelhardt, Gabriela; Hebel, Silke; Nessel, Andreas; Arlt, Marcus; Kaltenberg, Jennifer; Schwaneberg, Ulrich; Huber, Michael; Rink, Lothar; Haase, Hajo

    2014-07-01

    Free zinc ions (Zn(2+)) participate in several signaling pathways. The aim of the present study was to investigate a potential involvement of Zn(2+) in the PI3K/Akt pathway of interleukin (IL)-2 signaling in T-cells. The IL-2 receptor triggers three major pathways, ERK1/2, JAK/STAT5, and PI3K/Akt. We have previously shown that an IL-2-mediated release of lysosomal Zn(2+) into the cytoplasm activates ERK1/2, but not STAT5. In the present study, Akt phosphorylation in response to IL-2 was abrogated by the Zn(2+) chelator N,N,N',N'-tetrakis-2(pyridyl-methyl)ethylenediamine, and was induced by treatment with Zn(2+) and the ionophore pyrithione. The latter were ineffective in cells that were treated with siRNA against the phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a phosphatase that degrades the lipid second messenger PI(3,4,5)P3, which is produced by PI3K and leads to activation of Akt. Inhibition of recombinant PTEN by Zn(2+)in vitro yielded an IC50 of 0.59 nM. Considering a resting free cytoplasmic Zn(2+) level of 0.2 nM in the T-cell line CTLL-2, this seems ideally suited for dynamic regulation by cellular Zn(2+). Oxidation with H2O2 and supplementation with Zn(2+) led to similar changes in the CD spectrum of PTEN. Moreover, Zn(2+) partially prevented the oxidation of cysteines 71 and 124. Hence, we hypothesize that zinc signals affect the IL-2-dependent PI3K/Akt pathway by inhibiting the negative regulator PTEN through binding with a sub-nanomolar affinity to cysteine residues that are essential for its catalytic activity. PMID:24759986

  17. Decreased aggression and increased repetitive behavior in Pten haploinsufficient mice.

    PubMed

    Clipperton-Allen, A E; Page, D T

    2015-02-01

    Aggression is an aspect of social behavior that can be elevated in some individuals with autism spectrum disorder (ASD) and a concern for peers and caregivers. Mutations in Phosphatase and tensin homolog (PTEN), one of several ASD risk factors encoding negative regulators of the PI3K-Akt-mTOR pathway, have been reported in individuals with ASD and comorbid macrocephaly. We previously showed that a mouse model of Pten germline haploinsufficiency (Pten(+/-) ) has selective deficits, primarily in social behavior, along with broad overgrowth of the brain. Here, we further examine the social behavior of Pten(+/-) male mice in the resident-intruder test of aggression, using a comprehensive behavioral analysis to obtain an overall picture of the agonistic, non-agonistic and non-social behavior patterns of Pten(+/-) mice during a free interaction with a novel conspecific. Pten(+/-) male mice were involved in less aggression than their wild-type littermates. Pten(+/-) mice also performed less social investigation, including anogenital investigation and approaching and/or attending to the intruder, which is consistent with our previous finding of decreased sociability in the social approach test. In contrast to these decreases in social behaviors, Pten(+/-) mice showed increased digging. In summary, we report decreased aggression and increased repetitive behavior in Pten(+/-) mice, thus extending our characterization of this model of an ASD risk factor that features brain overgrowth and social deficits.

  18. DNMT1-mediated PTEN hypermethylation confers hepatic stellate cell activation and liver fibrogenesis in rats

    SciTech Connect

    Bian, Er-Bao; Huang, Cheng; Ma, Tao-Tao; Tao, Hui; Zhang, Hui; Cheng, Chang; Lv, Xiong-Wen; Li, Jun

    2012-10-01

    Hepatic stellate cell (HSC) activation is an essential event during liver fibrogenesis. Phosphatase and tension homolog deleted on chromosome 10 (PTEN), a tumor suppressor, is a negative regulator of this process. PTEN promoter hypermethylation is a major epigenetic silencing mechanism in tumors. The present study aimed to investigate whether PTEN promoter methylation was involved in HSC activation and liver fibrosis. Treatment of activated HSCs with the DNA methylation inhibitor 5-aza-2′-deoxycytidine (5-azadC) decreased aberrant hypermethylation of the PTEN gene promoter and prevented the loss of PTEN expression that occurred during HSC activation. Silencing DNA methyltransferase 1 (DNMT1) gene also decreased the PTEN gene promoter methylation and upregulated the PTEN gene expression in activated HSC-T6 cells. In addition, knockdown of DNMT1 inhibited the activation of both ERK and AKT pathways in HSC-T6 cells. These results suggest that DNMT1-mediated PTEN hypermethylation caused the loss of PTEN expression, followed by the activation of the PI3K/AKT and ERK pathways, resulting in HSC activation. Highlights: ► PTEN methylation status and loss of PTEN expression ► DNMT1 mediated PTEN hypermethylation. ► Hypermethylation of PTEN contributes to the activation of ERK and AKT pathways.

  19. PTEN protein expression correlates with PTEN gene molecular changes but not with VEGF expression in astrocytomas.

    PubMed

    Idoate, M A; Soria, E; Lozano, M D; Sola, J J; Panizo, A; de Alava, E; Manrique, M; Pardo-Mindán, F J

    2003-09-01

    PTEN gene (10q23) is a relevant tumor suppressor gene whose protein is a phosphatase involved in the control of angiogenesis of some tumors including astrocytomas. There are no studies correlating molecular changes of PTEN and the immunohistochemical expression of its protein (pPTEN) with the expression of vascular endothelial growth factor (VEGF) in astrocytomas. Fifty-six surgically resected brain gliomas, 10 grade 2, 16 grade 3, and 30 grade 4, were studied by a combined approach, consisting of (1) PCR analysis using four microsatellite markers against the PTEN gene region (10q23), (2) the FISH technique to test chromosome 10 using a pericentromeric probe, and (3) immunohistochemical evaluation of pPTEN and VEGF. Loss of heterozygosity (LOH) of PTEN was observed in 10% of fibrillary grade 2 astrocytomas and all gemistocytic ones. In high-grade tumors, LOH was more frequent in grade 4 than in grade 3 (> or =2 loci deleted, 83% and 56%, respectively). Monosomy for chromosome 10 was observed especially in high-grade tumors (6% of grade 3 and 50% of grade 4) and in 20% of grade 2 tumors, corresponding to gemistocytic astrocytomas. Results with both antibodies against PTEN were concordant: loss of cytoplasmic immunoreactivity was frequently observed according to homogeneous or heterogeneous patterns in 70% and 50% of grades 4 and 3, respectively, but not in grade 2. Immunonegativity of pPTEN was associated with PTEN gene deletion (> or =2 loci deleted) (P = 0.04) but not with monosomy. Cytoplasmic immunoreactivity against VEGF was observed in high-grade and in gemistocytic astrocytomas, but not in conventional grade 2 tumors. Tumor expression of pPTEN was not associated with immunoreactivity against VEGF when the same areas were considered. In conclusion, loss of PTEN expression is frequent in high-grade astrocytomas, but not in grade 2 tumors, and correlates with PTEN deletion and loss of chromosome 10. PTEN immunoreactivity does not correlate with VEGF expression

  20. Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization

    SciTech Connect

    Meng, Zhen; Gan, Ye-Hua

    2015-05-01

    Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocation and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation. - Highlights: • COX-2 inhibitor, celecoxib, could enhance radiosensitization. • Radiation induced PTEN inactivation (phosphorylation) and AKT activation. • COX-2 inhibitor induced PTEN expression and activation, and inactivated AKT. • COX-2 inhibitor enhanced radiosensitization through activating PTEN.

  1. Imbalanced PTEN and PI3K Signaling Impairs Class Switch Recombination.

    PubMed

    Chen, Zhangguo; Getahun, Andrew; Chen, Xiaomi; Dollin, Yonatan; Cambier, John C; Wang, Jing H

    2015-12-01

    Class switch recombination (CSR) generates isotype-switched Abs with distinct effector functions. B cells express phosphatase and tensin homolog (PTEN) and multiple isoforms of class IA PI3K catalytic subunits, including p110α and p110δ, whose roles in CSR remain unknown or controversial. In this article, we demonstrate a direct effect of PTEN on CSR signaling by acute deletion of Pten specifically in mature B cells, thereby excluding the developmental impact of Pten deletion. We show that mature B cell-specific PTEN overexpression enhances CSR. More importantly, we establish a critical role for p110α in CSR. Furthermore, we identify a cooperative role for p110α and p110δ in suppressing CSR. Mechanistically, dysregulation of p110α or PTEN inversely affects activation-induced deaminase expression via modulating AKT activity. Thus, our study reveals that a signaling balance between PTEN and PI3K isoforms is essential to maintain normal CSR.

  2. Relation of fatty acid composition in lead-exposed mallards to fat mobilization, lipid peroxidation and alkaline phosphatase activity

    USGS Publications Warehouse

    Mateo, R.; Beyer, W.N.; Spann, J.W.; Hoffman, D.J.

    2003-01-01

    The increase of n-6 polyunsaturated fatty acids (PUFA) in animal tissues has been proposed as a mechanism of Pb poisoning through lipid peroxidation or altered eicosanoids metabolism. We have studied fatty acid (FA) composition in liver and brain of mallards (Anas platyrhynchos) feeding for three weeks on diets containing combinations of low or high levels of vitamin E (20 or 200 UI/kg) and Pb (0 or 2 g/kg). Saturated FA, n-6 PUFA and total concentrations of FA were higher in livers of Pb-exposed mallards, but not in their brains. The percentage of n-6 PUFA in liver and brain was slightly higher in Pb-exposed mallards. The increase of n-6 PUFA in liver was associated with increased triglycerides and cholesterol in plasma, thus could be in part attributed to feed refusal and fat mobilization. The hepatic ratios between adrenic acid (22:4 n-6) and arachidonic acid (20:4 n-6) or between adrenic acid and linoleic acid (18:2 n-6) were higher in Pb exposed birds, supporting the existing hypothesis of increased fatty acid elongation by Pb. Among the possible consequences of increased n-6 PUFA concentration in tissues, we found increased lipid peroxidation in liver without important histopathological changes, and decreased plasma alkaline phosphatase activity that may reflect altered bone metabolism in birds.

  3. Nonalcoholic Fatty Liver Disease Progression in Rats is Accelerated by Splenic Regulation of Liver PTEN/AKT

    PubMed Central

    Wang, Ziming; Li, Naishu; Wang, Biao; Lin, Jianhua

    2015-01-01

    Background/Aim: The spleen has been reported to participate in the development of nonalcoholic fatty liver disease (NAFLD), but the mechanism has not been fully characterized. This study aims to elucidate how the spleen affects the development of NAFLD in a rat model. Materials and Methods: Following either splenectomy or sham operation, male Sprague–Dawley (SD) rats were fed a high-fat diet to drive the development of NAFLD; animals fed a normal diet were used as controls. Two months after surgery, livers and blood samples were collected. Serum lipids were measured; liver histology, phosphatase and tensin homologue deleted on chromosome 10 (PTEN) gene expression, and the ratio of pAkt/Akt were determined. Results: Splenectomy increased serum lipids, except triglyceride (TG) and high-density lipoprotein (HDL), in animals fed either a high-fat or normal diet. Furthermore, splenectomy significantly accelerated hepatic steatosis. Western blot analysis and real-time polymerase chain reaction showed splenectomy induced significant downregulation of PTEN expression and a high ratio of pAkt/Akt in the livers. Conclusions: The spleen appears to play a role in the development of NAFLD, via a mechanism involving downregulation of hepatic PTEN expression. PMID:26228367

  4. Loss of Catalytically Inactive Lipid Phosphatase Myotubularin-related Protein 12 Impairs Myotubularin Stability and Promotes Centronuclear Myopathy in Zebrafish

    PubMed Central

    Gupta, Vandana A.; Hnia, Karim; Smith, Laura L.; Gundry, Stacey R.; McIntire, Jessica E.; Shimazu, Junko; Bass, Jessica R.; Talbot, Ethan A.; Amoasii, Leonela; Goldman, Nathaniel E.; Laporte, Jocelyn; Beggs, Alan H.

    2013-01-01

    X-linked myotubular myopathy (XLMTM) is a congenital disorder caused by mutations of the myotubularin gene, MTM1. Myotubularin belongs to a large family of conserved lipid phosphatases that include both catalytically active and inactive myotubularin-related proteins (i.e., “MTMRs”). Biochemically, catalytically inactive MTMRs have been shown to form heteroligomers with active members within the myotubularin family through protein-protein interactions. However, the pathophysiological significance of catalytically inactive MTMRs remains unknown in muscle. By in vitro as well as in vivo studies, we have identified that catalytically inactive myotubularin-related protein 12 (MTMR12) binds to myotubularin in skeletal muscle. Knockdown of the mtmr12 gene in zebrafish resulted in skeletal muscle defects and impaired motor function. Analysis of mtmr12 morphant fish showed pathological changes with central nucleation, disorganized Triads, myofiber hypotrophy and whorled membrane structures similar to those seen in X-linked myotubular myopathy. Biochemical studies showed that deficiency of MTMR12 results in reduced levels of myotubularin protein in zebrafish and mammalian C2C12 cells. Loss of myotubularin also resulted in reduction of MTMR12 protein in C2C12 cells, mice and humans. Moreover, XLMTM mutations within the myotubularin interaction domain disrupted binding to MTMR12 in cell culture. Analysis of human XLMTM patient myotubes showed that mutations that disrupt the interaction between myotubularin and MTMR12 proteins result in reduction of both myotubularin and MTMR12. These studies strongly support the concept that interactions between myotubularin and MTMR12 are required for the stability of their functional protein complex in normal skeletal muscles. This work highlights an important physiological function of catalytically inactive phosphatases in the pathophysiology of myotubular myopathy and suggests a novel therapeutic approach through identification of

  5. Mutations of the KIT gene and loss of heterozygosity of the PTEN region in a primary malignant melanoma arising from a mature cystic teratoma of the ovary.

    PubMed

    Tate, Genshu; Tajiri, Takuma; Suzuki, Takao; Mitsuya, Toshiyuki

    2009-04-01

    A tumor suppressor gene at 10q23.3, designated PTEN, encoding a dual-specificity phosphatase with lipid and protein phosphatase activity, has been shown to play a pivotal role in the pathogenesis of a variety of human cancers. A frequent loss of heterozygosity (LOH) at 10q is found in melanoma; however, little is known about the role of PTEN in the pathogenesis of a primary malignant melanoma derived from ovarian mature cystic teratoma, which is an extremely rare melanoma. This study examined the genetic alterations involved in the mitogen-activated protein kinase and phosphatidylinositol 3 kinase pathways in an ovarian malignant melanoma. A LOH analysis revealed hemizygous deletion around and in the PTEN gene not only in the ovarian melanoma but also in a mature cystic teratoma. Another case of ovarian mature cystic teratomas in the absence of melanoma also showed allelic loss of the PTEN region. To date, mutations of BRAF, NRAS, and KIT genes have been reported in malignant melanomas. In the present study, D816H and K558E mutations of the KIT gene were revealed in the melanoma arising from a mature cystic teratoma, but not in a mature cystic teratoma. No mutations of the BRAF and NRAS genes were found in the melanoma. These results indicate that LOH of the PTEN region is one of the molecular alterations of an ovarian mature cystic teratoma and a KIT mutation is an additional promotional event associated with the oncogenesis of a melanoma arising from an ovarian mature cystic teratoma.

  6. AKT activation promotes PTEN hamartoma tumor syndrome-associated cataract development.

    PubMed

    Sellitto, Caterina; Li, Leping; Gao, Junyuan; Robinson, Michael L; Lin, Richard Z; Mathias, Richard T; White, Thomas W

    2013-12-01

    Mutations in the human phosphatase and tensin homolog (PTEN) gene cause PTEN hamartoma tumor syndrome (PHTS), which includes cataract development among its diverse clinical pathologies. Currently, it is not known whether cataract formation in PHTS patients is secondary to other systemic problems, or the result of the loss of a critical function of PTEN within the lens. We generated a mouse line with a lens-specific deletion of Pten (PTEN KO) and identified a regulatory function for PTEN in lens ion transport. Specific loss of PTEN in the lens resulted in cataract. PTEN KO lenses exhibited a progressive age-related increase in intracellular hydrostatic pressure, along with, increased intracellular sodium concentrations, and reduced Na+/K+-ATPase activity. Collectively, these defects lead to lens swelling, opacities and ultimately organ rupture. Activation of AKT was highly elevated in PTEN KO lenses compared to WT mice. Additionally, pharmacological inhibition of AKT restored normal Na+/K+-ATPase activity in primary cultured lens cells and reduced lens pressure in intact lenses from PTEN KO animals. These findings identify a direct role for PTEN in the regulation of lens ion transport through an AKT-dependent modulation of Na+/K+-ATPase activity, and provide a new animal model to investigate cataract development in PHTS patients. PMID:24270425

  7. Modulation of specific protein expression levels by PTEN: identification of AKAP121, DHFR, G3BP, Rap1, and RCC1 as potential targets of PTEN.

    PubMed

    Huang, Yanping; Wernyj, Roman P; Norton, Darrell D; Precht, Patricia; Seminario, Maria-Cristina; Wange, Ronald L

    2005-05-26

    The tumor suppressor PTEN is mutated in a high percentage of human cancers, and is implicated in pathways regulating cell growth, proliferation, survival, and migration. Despite significant advances, our understanding of its mechanisms of action remains incomplete. We have used a high-throughput proteomic immunoblotting approach to identify proteins whose expression levels are modulated by PTEN. Out of over 800 proteins screened, 22 proteins showed significant changes in expression. Five proteins that exhibited two-fold or greater changes in expression level were further characterized. AKAP121 and G3BP expression was reduced, while dihydrofolate reductase (DHFR), Rap1 and RCC1 expression was elevated in response to PTEN expression in a PTEN-null T-cell leukemia line. The phosphatase activity of PTEN was required for these effects. However, direct inhibition of PI-3 Kinase could mimic PTEN in modulating expression of DHFR, G3BP, Rap1 and RCC1, but not AKAP121. Real-time PCR showed that the effects of PTEN were primarily post-transcriptional, and would not have been revealed by mRNA-based screens. We conclude from these data that PTEN can modulate the expression level of a number of different proteins. The identified proteins have the potential to serve as previously unrecognized effectors of PTEN, and suggest the existence of additional complexity in the modes by which PTEN can regulate cellular biology.

  8. TBX2 represses PTEN in rhabdomyosarcoma and skeletal muscle.

    PubMed

    Zhu, B; Zhang, M; Williams, E M; Keller, C; Mansoor, A; Davie, J K

    2016-08-11

    Rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma in children that shares many features of developing skeletal muscle. TBX2, a T-box family member, is highly upregulated in tumor cells of both major RMS subtypes where it functions as an oncogene. TBX2 is a repressor that is often overexpressed in cancer cells and functions in bypassing cell growth control, including the repression of the cell cycle regulators p14 and p21. We have found that TBX2 directly represses the tumor-suppressor phosphatase and tensin homolog (PTEN) in both RMS and normal muscle. Exogenous expression of TBX2 in normal muscle cells downregulates PTEN, and depletion or interference with TBX2 in RMS cells upregulates PTEN. Human RMS tumors show high levels of TBX2 and correspondingly low levels of PTEN. The expression of PTEN in clinical RMS samples is relatively uncharacterized, and we establish that suppression of PTEN is a frequent event in both subtypes of RMS. TBX2 represses PTEN by directly binding to the promoter and recruiting the histone deacetylase, HDAC1. RMS cells have high levels of activated AKT owing to the deregulation of phosphoinositide-3 kinase (PI3K) signaling, and depletion or interference with TBX2, which upregulates PTEN, results in a reduction of phospho-AKT. We have also found that the highly related T-box family member TBX3 does not repress PTEN in the muscle lineage. This work suggests that TBX2 is a central component of the PTEN/PI3K/AKT signaling pathway deregulation in RMS cells and that targeting TBX2 in RMS tumors may offer a novel therapeutic approach for RMS.

  9. PTEN induces apoptosis and cavitation via HIF-2-dependent Bnip3 upregulation during epithelial lumen formation

    PubMed Central

    Qi, Y; Liu, J; Saadat, S; Tian, X; Han, Y; Fong, G-H; Pandolfi, P P; Lee, L Y; Li, S

    2015-01-01

    The tumor suppressor phosphatase and tensin homolog (PTEN) dephosphorylates PIP3 and antagonizes the prosurvival PI3K-Akt pathway. Targeted deletion of PTEN in mice led to early embryonic lethality. To elucidate its role in embryonic epithelial morphogenesis and the underlying mechanisms, we used embryonic stem cell-derived embryoid body (EB), an epithelial cyst structurally similar to the periimplantation embryo. PTEN is upregulated during EB morphogenesis in parallel with apoptosis of core cells, which mediates EB cavitation. Genetic ablation of PTEN causes Akt overactivation, apoptosis resistance and cavitation blockade. However, rescue experiments using mutant PTEN and pharmacological inhibition of Akt suggest that the phosphatase activity of PTEN and Akt are not involved in apoptosis-mediated cavitation. Instead, hypoxia-induced upregulation of Bnip3, a proapoptotic BH3-only protein, mediates PTEN-dependent apoptosis and cavitation. PTEN inactivation inhibits hypoxia- and reactive oxygen species-induced Bnip3 elevation. Overexpression of Bnip3 in PTEN-null EBs rescues apoptosis of the core cells. Mechanistically, suppression of Bnip3 following PTEN loss is likely due to reduction of hypoxia-inducible factor-2α (HIF-2α) because forced expression of an oxygen-stable HIF-2α mutant rescues Bnip3 expression and apoptosis. Lastly, we show that HIF-2α is upregulated by PTEN at both transcriptional and posttranscriptional levels. Ablation of prolyl hydroxylase domain-containing protein 2 (PHD2) in normal EBs or inhibition of PHD activities in PTEN-null EBs stabilizes HIF-2α and induces Bnip3 and caspase-3 activation. Altogether, these results suggest that PTEN is required for apoptosis-mediated cavitation during epithelial morphogenesis by regulating the expression of HIF-2α and Bnip3. PMID:25394489

  10. Combined PDGFR and HDAC Inhibition Overcomes PTEN Disruption in Chordoma

    PubMed Central

    Kassam, Amin B.; Park, Myung-Jin; Gardner, Paul; Prevedello, Daniel; Henry, Stephanie; Horbinski, Craig; Beumer, Jan H.; Tawbi, Hussein; Williams, Brian J.; Shaffrey, Mark E.; Egorin, Merrill J.; Abounader, Roger; Park, Deric M.

    2015-01-01

    Background The majority of chordomas show activation of the platelet-derived growth factor receptor (PDGFR). Based on in vitro intertumoral variation in response to recombinant PDGF protein and PDGFR inhibition, and variable tumor response to imatinib, we hypothesized that chordomas resistant to PDGFR inhibition may possess downstream activation of the pathway. Methods Molecular profiling was performed on 23 consecutive chordoma primary tissue specimens. Primary cultures established from 20 of the 23 specimens, and chordoma cell lines, UCH-1 and UCH-2, were used for in vitro experiments. Results Loss of heterozygosity (LOH) at the phosphatase and tensin homolog (PTEN) locus was observed in 6 specimens (26%). PTEN disruption statistically correlated with increased Ki-67 proliferation index, an established marker of poor outcome for chordoma. Compared to wild type, PTEN deficient chordomas displayed increased proliferative rate, and responded less favorably to PDGFR inhibition. PTEN gene restoration abrogated this growth advantage. Chordomas are characterized by intratumoral hypoxia and local invasion, and histone deacetylase (HDAC) inhibitors are capable of attenuating both hypoxic signaling and cell migration. The combination of PDGFR and HDAC inhibition effectively disrupted growth and invasion of PTEN deficient chordoma cells. Conclusions Loss of heterozygosity of the PTEN gene seen in a subset of chordomas is associated with aggressive in vitro behavior and strongly correlates with increased Ki-67 proliferative index. Combined inhibition of PDGFR and HDAC attenuates proliferation and invasion in chordoma cells deficient for PTEN. PMID:26247786

  11. Analysis of PTEN ubiquitylation and SUMOylation using molecular traps.

    PubMed

    Lang, Valérie; Aillet, Fabienne; Da Silva-Ferrada, Elisa; Xolalpa, Wendy; Zabaleta, Lorea; Rivas, Carmen; Rodriguez, Manuel S

    2015-05-01

    The function of the tumour suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is tightly controlled by post-translational modifications (PTMs) including ubiquitin or Small Ubiquitin-related MOdifiers (SUMO). It is known that SUMOylation by SUMO-1, SUMO-2/-3, mono- or polyubiquitylation have a distinct impact on PTEN activity, localisation and/or stability, however the molecular mechanisms governing these processes are still unclear. Studying PTM regulated events has always been a difficult task due to their labile nature. Here, we propose an update on the role of these PTMs on PTEN function, as well as a methodological overview on the use of molecular traps named SUMO Binding Entities (SUBEs) or Tandem Ubiquitin Binding Entities (TUBEs) to capture SUMOylated or Ubiquitylated forms of PTEN respectively. When combined with in vitro SUMOylation or Ubiquitylation assays, the use of molecular traps facilitate the detection of modified forms of PTEN. SUMO and ubiquitin-traps are also suitable to capture endogenously modified forms of PTEN after expression of E3 ligases or treatment with chemical inhibitors. This versatile approach represents an interesting alternative to explore PTEN regulation by SUMO and ubiquitin under physiological or pathological conditions.

  12. Physical Foundations of PTEN/Phosphoinositide Interaction

    NASA Astrophysics Data System (ADS)

    Gericke, Arne; Jiang, Zhiping; Redfern, Roberta E.; Kooijman, Edgar E.; Ross, Alonzo H.

    2009-03-01

    Phosphoinositides act as signaling molecules by recruiting critical effectors to specific subcellular membranes to regulate cell proliferation, apoptosis and cytoskeletal reorganization, which requires a tight regulation of phosphoinositide generation and turnover as well as a high degree of compartmentalization. PTEN is a phosphatase specific for the 3 position of the phosophoinositide ring that is deleted or mutated in many different disease states. PTEN association with membranes requires the interaction of its C2 domain with phosphatidylserine and the interaction of its N-terminal end with phosphatidylinositol-4,5-bisphophate (PI(4,5)P2). We have investigated PTEN/PI(4,5)P2 interaction and found that Lys13 is crucial for the observed binding. We also found that the presence of cholesterol enhances PTEN binding to mixed PI(4,5)P2/POPC vesicles. Fluorescence microscopy experiments utilizing GUVs yielded results consistent with enhanced phosphoinositide domain formation in the presence of cholesterol. These experiments were accompanied by zeta potential measurements and solid state MAS ^31P-NMR experiments aimed at investigating the ionization behavior of phosphoinositides.

  13. [Pten gene expression in the endometrial mucosa].

    PubMed

    Bakiewicz, Anna; Goździk, Jarosław; Sporny, Stanisław

    2006-04-01

    The opinions about the causes of the endometrial carcinoma have changed since 1995, due to molecular biology progress. The findings concerning the recently discovered suppressor PTEN gene localized on the chromosome 10 -10q23.3, the product of which is a specific phosphatase are especially valuable. The loss of the gene function is directly linked with the genesis and progression of endometrial carcinoma, as well as cancers of other tissues and organs, including thyroid, breast, ovary, prostate or skin. Immunohistochemical studies with the use of the 6H2.1 antibody directed against the protein coded by the PTEN gene indicate that the protein cannot be found in more than half of the patients with endometrial carcinoma and its precursor--EIN. Mutations of the PTEN gene have also been detected in many young women with normal microscopic structure of the endometrial mucosa. Thus, a test for the absence of the PTEN gene product in the endometrial cells may be used for precise identification of early stages of carcinogenesis.

  14. MMAC/PTEN gene expression in endometrial cancer: RT-PCR studies.

    PubMed

    Sobczuk, Anna; Smolarz, Beata; Romanowicz-Makowska, Hanna; Pertyński, Tomasz

    2006-01-01

    Mutations in the MMAC/PTEN (phosphatase and tensin homologue deleted on chromosome 10) gene are documented in cancers of the breast, prostate, ovary, colon, melanoma, glioblastoma, lymphoma and endometrium. In the present work MMAC/PTEN gene expression in women with endometrial adenocarcinoma (n=70) in RNA samples obtained from cancer tissue were investigated. Control DNA was obtained from 68 normal endometrial tissue. The MMAC/PTEN expression was determined by RT-PCR analysis. The expression of MMAC/PTEN gene in endometrial adenocarcinoma cases was significantly reduced compared to the expression in the normal samples (P < 0.05). Furthermore the significant difference (P < 0.05) was observed between the expression of MMAC/PTEN in stage III versus lower stages of endometrial cancer. The results support the hypothesis that the MMAC/PTEN gene expression may be associated with the incidence of endometrial cancer.

  15. RNA interference mediated pten knock-down inhibit the formation of polycystic ovary.

    PubMed

    Ouyang, Jie-Xiu; Luo, Tao; Sun, Hui-Yun; Huang, Jian; Tang, Dan-Feng; Wu, Lei; Zheng, Yue-Hui; Zheng, Li-Ping

    2013-08-01

    Pten (phosphatase and tensin homolog deleted on chromosome 10), a kind of tumor suppressor gene, plays important roles in female reproductive system. But its expression and roles in the formation of polycystic ovaries are yet to be known. In this study, we constructed a rat model of PCOS using norethindrone and HCG injections and found the expressions of pten mRNA and PTEN protein increased significantly in the polycystic ovary tissue by immunohistochemistry, RT-PCR, and western blot. Furthermore, the results showed that in vivo ovaries could be effectively transfected by lentiviral vectors through the ovarian microinjection method and indicated that pten shRNA may inhibit the formation of polycystic ovaries by pten down-regulation. Our study provides new information regarding the role of PTEN in female reproductive disorders, such as polycystic ovary syndrome.

  16. PTEN knockdown alters dendritic spine/protrusion morphology, not density

    PubMed Central

    Haws, Michael E.; Jaramillo, Thomas C.; Espinosa-Becerra, Felipe; Widman, Allie; Stuber, Garret D.; Sparta, Dennis R.; Tye, Kay M.; Russo, Scott J.; Parada, Luis F.; Kaplitt, Michael; Bonci, Antonello; Powell, Craig M.

    2014-01-01

    Mutations in phosphatase and tensin homolog deleted on chromosome ten (PTEN) are implicated in neuropsychiatric disorders including autism. Previous studies report that PTEN knockdown in neurons in vivo leads to increased spine density and synaptic activity. To better characterize synaptic changes in neurons lacking PTEN, we examined the effects of shRNA knockdown of PTEN in basolateral amygdala neurons on synaptic spine density and morphology using fluorescent dye confocal imaging. Contrary to previous studies in dentate gyrus, we find that knockdown of PTEN in basolateral amygdala leads to a significant decrease in total spine density in distal dendrites. Curiously, this decreased spine density is associated with increased miniature excitatory post-synaptic current frequency and amplitude, suggesting an increase in number and function of mature spines. These seemingly contradictory findings were reconciled by spine morphology analysis demonstrating increased mushroom spine density and size with correspondingly decreased thin protrusion density at more distal segments. The same analysis of PTEN conditional deletion in dentate gyrus demonstrated that loss of PTEN does not significantly alter total density of dendritic protrusions in the dentate gyrus, but does decrease thin protrusion density and increases density of more mature mushroom spines. These findings suggest that, contrary to previous reports, PTEN knockdown may not induce de novo spinogenesis, but instead may increase synaptic activity by inducing morphological and functional maturation of spines. Furthermore, behavioral analysis of basolateral amygdala PTEN knockdown suggests that these changes limited only to the basolateral amygdala complex may not be sufficient to induce increased anxiety-related behaviors. PMID:24264880

  17. Inhibition of lipid phosphate phosphatase activity by VPC32183 suppresses the ability of diacylglycerol pyrophosphate to activate ERK(1/2) MAP kinases.

    PubMed

    Violet, Pierre-Christian; Billon-Denis, Emmanuelle; Robin, Philippe

    2012-11-01

    The lipidic metabolite, diacylglycerol pyrophosphate (DGPP), in its dioctanoyl form (DGPP 8:0), has been described as an antagonist for mammalian lysophosphatidic acid (LPA) receptors LPA1 and LPA3. In this study we show that DGPP 8:0 does not antagonize LPA dependent activation of ERK(1/2) MAP kinases but strongly stimulated them in various mammalian cell lines. LPA and DGPP 8:0 stimulation of ERK(1/2) occurred through different pathways. The DGPP 8:0 effect appeared to be dependent on PKC, Raf and MEK but was insensitive to pertussis toxin and did not involve G protein activation. Finally we showed that DGPP 8:0 effect on ERK(1/2) was dependent on its dephosphorylation by a phosphatase activity sharing lipid phosphate phosphatase properties. The inhibition of this phosphatase activity by VPC32183, a previously characterized LPA receptor antagonist, blocked the DGPP 8:0 effect on ERK(1/2) activation. Moreover, down-regulation of lipid phosphate phosphatase 1 (LPP1) expression by RNA interference technique also reduced DGPP 8:0-induced ERK(1/2) activation. Consistently, over expression of LPP1 in HEK293 cells increases DGPP 8:0 hydrolysis and this increased activity was inhibited by VPC32183. In conclusion, DGPP 8:0 does not exert its effect by acting on a G protein coupled receptor, but through its dephosphorylation by LPP1, generating dioctanoyl phosphatidic acid which in turn activates PKC. These results suggest that LPP1 could have a positive regulatory function on cellular signaling processes such as ERK(1/2) activation.

  18. PTEN inhibition and axon regeneration and neural repair

    PubMed Central

    Ohtake, Yosuke; Hayat, Umar; Li, Shuxin

    2015-01-01

    The intrinsic growth ability of all the neurons declines during development although some may grow better than others. Numerous intracellular signaling proteins and transcription factors have been shown to regulate the intrinsic growth capacity in mature neurons. Among them, PI3 kinase/Akt pathway is important for controlling axon elongation. As a negative regulator of this pathway, the tumor suppressor phosphatase and tensin homolog (PTEN) appears critical to control the regenerative ability of young and adult neurons. This review will focus on recent research progress in axon regeneration and neural repair by PTEN inhibition and therapeutic potential of blocking this phosphatase for neurological disorders. Inhibition of PTEN by deletion in conditional knockout mice, knockdown by short-hairpin RNA, or blockade by pharmacological approaches, including administration of selective PTEN antagonist peptides, stimulates various degrees of axon regrowth in juvenile or adult rodents with central nervous system injuries. Importantly, post-injury PTEN suppression could enhance axonal growth and functional recovery in adult central nervous system after injury. PMID:26604880

  19. PTEN modulates vascular endothelial growth factor-mediated signaling and angiogenic effects.

    PubMed

    Huang, Jianhua; Kontos, Christopher D

    2002-03-29

    Phosphatidylinositol 3-kinase is activated by vascular endothelial growth factor (VEGF), and many of the angiogenic cellular responses of VEGF are regulated by the lipid products of phosphatidylinositol 3-kinase. The tumor suppressor PTEN has been shown to down-regulate phosphatidylinositol 3-kinase signaling, yet the effects of PTEN on VEGF-mediated signaling and angiogenesis are unknown. Inhibition of endogenous PTEN in cultured endothelial cells by adenovirus-mediated overexpression of a dominant negative PTEN mutant (PTEN-C/S) enhanced VEGF-mediated Akt phosphorylation, and this effect correlated with decreases in caspase-3 cleavage, caspase-3 activity, and DNA degradation after induction of apoptosis with tumor necrosis factor-alpha. Overexpression of PTEN-C/S also enhanced VEGF-mediated endothelial cell proliferation and migration. In contrast, overexpression of wild-type PTEN inhibited the anti-apoptotic, proliferative, and chemotactic effects of VEGF. Moreover, PTEN-C/S increased the length of vascular sprouts in the rat aortic ring assay and modulated VEGF-mediated tube formation in an in vitro angiogenesis assay, whereas PTEN-wild type inhibited these effects. Taken together, these findings demonstrate that PTEN potently modulates VEGF-mediated signaling and function and that PTEN is a viable target in therapeutic approaches to promote or inhibit angiogenesis.

  20. The C-terminal tail inhibitory phosphorylation sites of PTEN regulate its intrinsic catalytic activity and the kinetics of its binding to phosphatidylinositol-4,5-bisphosphate.

    PubMed

    Chia, Yeong-Chit Joel; Catimel, Bruno; Lio, Daisy Sio Seng; Ang, Ching-Seng; Peng, Benjamin; Wu, Hong; Zhu, Hong-Jian; Cheng, Heung-Chin

    2015-12-01

    Dephosphorylation of four major C-terminal tail sites and occupancy of the phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]-binding site of PTEN cooperate to activate its phospholipid phosphatase activity and facilitate its recruitment to plasma membrane. Our investigation of the mechanism by which phosphorylation of these C-terminal sites controls the PI(4,5)P2-binding affinity and catalytic activity of PTEN resulted in the following findings. First, dephosphorylation of all four sites leads to full activation; and phosphorylation of any one site significantly reduces the intrinsic catalytic activity of PTEN. These findings suggest that coordinated inhibition of the upstream protein kinases and activation of the protein phosphatases targeting the four sites are needed to fully activate PTEN phosphatase activity. Second, PI(4,5)P2 cannot activate the phosphopeptide phosphatase activity of PTEN, suggesting that PI(4,5)P2 can only activate the phospholipid phosphatase activity but not the phosphoprotein phosphatase activity of PTEN. Third, dephosphorylation of all four sites significantly decreases the affinity of PTEN for PI(4,5)P2. Since PI(4,5)P2 is a major phospholipid co-localizing with the phospholipid- and phosphoprotein-substrates in plasma membrane, we hypothesise that the reduced affinity facilitates PTEN to "hop" on the plasma membrane to dephosphorylate these substrates. PMID:26471078

  1. PTEN's regulation of VEGF and VEGFR1 expression and its clinical significance in myeloid leukemia.

    PubMed

    Zhiyong, Cheng; Wentong, Liang; Xiaoyang, Yang; Ling, Pan

    2012-06-01

    Phosphatase and tensin homolog (PTEN) acts as a novel tumor suppressor gene. PTEN protein plays an important role in regulating proliferation, apoptosis, invasion, and migration of many cancer cells. PTEN also modulates angiogenesis mediated by vascular endothelial growth factor (VEGF) via down-regulating PI3K/Akt pathway in many solid tumors. However, the effects of PTEN on VEGF and VEGFR1 (FLT1)-mediated angiogenesis, migration, invasion of leukemia cells, and its clinical significance are still unknown in myeloid leukemia. Therefore, we investigated the effect of PTEN on PI3K/Akt and VEGF/FLT1 pathways by transfecting wild-type PTEN gene to induce high expression of wild-type PTEN gene and protein in chronic myelogenous leukemia cell line K562 cells. We also observed the correlation between the expression levels of PTEN and VEGF/FLT1 and its clinical significance in myeloid leukemia patients. We found that the expression reconstitution of wild-type PTEN had significant effect on inhibiting proliferation, migration, and invasion abilities of K562 cells via down-regulation of Akt phosphorylation and inhibition of VEGF/FLT1 expression. In myeloid leukemia patients, a negative correlation was found between the expression level of PTEN mRNA and that of VEGF and FLT1 mRNA. Down-regulation of PTEN expression accompanied by up-regulation of VEGF and FLT1 mRNA indicated a higher tendency of extramedullary disease in acute myeloid leukemia patients. In conclusion, PTEN could modulate the function of VEGF/VEGFR signaling pathway down-regulation of Akt phosphorylation and that PTEN would be a candidate target to be addressed for inhibiting angiogenesis along with the treatment of myeloid leukemia.

  2. Fatty acids increase neuronal hypertrophy of Pten knockdown neurons

    PubMed Central

    Fricano, Catherine J.; DeSpenza, Tyrone; Frazel, Paul W.; Li, Meijie; O'Malley, A. James; Westbrook, Gary L.; Luikart, Bryan W.

    2014-01-01

    Phosphatase and tensin homolog (Pten) catalyzes the reverse reaction of PI3K by dephosphorylating PIP3 to PIP2. This negatively regulates downstream Akt/mTOR/S6 signaling resulting in decreased cellular growth and proliferation. Co-injection of a lentivirus knocking Pten down with a control lentivirus allows us to compare the effects of Pten knockdown between individual neurons within the same animal. We find that knockdown of Pten results in neuronal hypertrophy by 21 days post-injection. This neuronal hypertrophy is correlated with increased p-S6 and p-mTOR in individual neurons. We used this system to test whether an environmental factor that has been implicated in cellular hypertrophy could influence the severity of the Pten knockdown-induced hypertrophy. Implantation of mini-osmotic pumps delivering fatty acids results in increased neuronal hypertrophy and p-S6/p-mTOR staining. These hypertrophic effects were reversed in response to rapamycin treatment. However, we did not observe a similar increase in hypertrophy in response to dietary manipulations of fatty acids. Thus, we conclude that by driving growth signaling with fatty acids and knocking down a critical regulator of growth, Pten, we are able to observe an additive morphological phenotype of increased soma size mediated by the mTOR pathway. PMID:24795563

  3. Phosphatase and Tensin Homologue: Novel Regulation by Developmental Signaling

    PubMed Central

    Jerde, Travis J.

    2015-01-01

    Phosphatase and tensin homologue (PTEN) is a critical cell endogenous inhibitor of phosphoinositide signaling in mammalian cells. PTEN dephosphorylates phosphoinositide trisphosphate (PIP3), and by so doing PTEN has the function of negative regulation of Akt, thereby inhibiting this key intracellular signal transduction pathway. In numerous cell types, PTEN loss-of-function mutations result in unopposed Akt signaling, producing numerous effects on cells. Numerous reports exist regarding mutations in PTEN leading to unregulated Akt and human disease, most notably cancer. However, less is commonly known about nonmutational regulation of PTEN. This review focuses on an emerging literature on the regulation of PTEN at the transcriptional, posttranscriptional, translational, and posttranslational levels. Specifically, a focus is placed on the role developmental signaling pathways play in PTEN regulation; this includes insulin-like growth factor, NOTCH, transforming growth factor, bone morphogenetic protein, wnt, and hedgehog signaling. The regulation of PTEN by developmental mediators affects critical biological processes including neuronal and organ development, stem cell maintenance, cell cycle regulation, inflammation, response to hypoxia, repair and recovery, and cell death and survival. Perturbations of PTEN regulation consequently lead to human diseases such as cancer, chronic inflammatory syndromes, developmental abnormalities, diabetes, and neurodegeneration. PMID:26339505

  4. Triple-negative breast cancer and PTEN (phosphatase and tensin homologue)loss are predictors of BRCA1 germline mutations in women with early-onset and familial breast cancer, but not in women with isolated late-onset breast cancer

    PubMed Central

    2012-01-01

    Introduction Given that breast cancers in germline BRCA1 carriers are predominantly estrogen-negative and triple-negative, it has been suggested that women diagnosed with triple-negative breast cancer (TNBC) younger than 50 years should be offered BRCA1 testing, regardless of family cancer characteristics. However, the predictive value of triple-negative breast cancer, when taken in the context of personal and family cancer characteristics, is unknown. The aim of this study was to determine whether TNBC is a predictor of germline BRCA1 mutations, in the context of multiple predictive factors. Methods Germline mutations in BRCA1 and BRCA2 were analyzed by Sanger sequencing and multiple ligation-dependent probe amplification (MLPA) analysis in 431 women from the Malaysian Breast Cancer Genetic Study, including 110 women with TNBC. Logistic regression was used to identify and to estimate the predictive strength of major determinants. Estrogen receptor (ER) and phosphatase and tensin homologue (PTEN) status were assessed and included in a modified Manchester scoring method. Results Our study in an Asian series of TNBC patients demonstrated that 27 (24.5%) of 110 patients have germline mutations in BRCA1 (23 of 110) and BRCA2 (four of 110). We found that among women diagnosed with breast cancer aged 36 to 50 years but with no family history of breast or ovarian cancer, the prevalence of BRCA1 and BRCA2 mutations was similar in TNBC (8.5%) and non-TNBC patients (6.7%). By contrast, in women diagnosed with breast cancer, younger than 35 years, with no family history of these cancers, and in women with a family history of breast cancer, the prevalence of mutations was higher in TNBC compared with non-TNBC (28.0% and 9.9%; P = 0.045; and 42.1% and 14.2%; P < 0.0001, respectively]. Finally, we found that incorporation of estrogen-receptor and TNBC status improves the sensitivity of the Manchester Scoring method (42.9% to 64.3%), and furthermore, incorporation of PTEN status

  5. Nongenomic Mechanisms of PTEN Regulation

    PubMed Central

    Fata, Jimmie E.; Debnath, Shawon; Jenkins, Edmund C.; Fournier, Marcia V.

    2012-01-01

    A large amount of data supports the view that PTEN is a bona fide tumor suppressor gene. However, recent evidence suggests that derailment of cellular localization and expression levels of functional nonmutated PTEN is a determining force in inducing abnormal cellular and tissue outcomes. As the cellular mechanisms that regulate normal PTEN enzymatic activity resolve, it is evident that deregulation of these mechanisms can alter cellular processes and tissue architecture and ultimately lead to oncogenic transformation. Here we discuss PTEN ubiquitination, PTEN complex formation with components of the adherens junction, PTEN nuclear localization, and microRNA regulation of PTEN as essential regulatory mechanisms that determine PTEN function independent of gene mutations and epigenetic events. PMID:22536248

  6. [Relationship between PTEN mutations and protein kinase B phosphorylation caused by insulin or recombinant human epidermal growth factor stimulation].

    PubMed

    Zhong, Hailan; Hu, Xianfu; Lin, Jianhua

    2016-08-01

    Objective To study the effect of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) mutations on protein kinase B (Akt) phosphorylation of CNE-1 nasopharyngeal carcinoma cell line. Methods CNE-1 cells were cultured in RPMI1640 medium containing 100 mL/L fetal calf serum, and then transfected with wild-type PTEN (wtPTEN), mutant PTEN C124S and mutant PTEN G129E plasmid separately. After overnight serum starvation, the cells were stimulated with 0.15 IU/mL insulin or 0.3 μg/mL recombinant human epidermal growth factor (rhEGF). At last, Akt phosphorylation was evaluated by Western blotting. Results Insulin or rhEGF stimulation led to Akt activation in CNE-1 cells. The wtPTEN inhibited insulin- or rhEGF-stimulated phosphorylation of Akt. PTEN C124S mutant activated insulin-stimulated phosphorylation of Akt, but not rhEGF-stimulated phosphorylation of Akt. PTEN G129E mutant inhibited insulin-stimulated phosphorylation of Akt. Conclusion The wtPTEN inhibited insulin- or rhEGF-stimulated phosphorylation of Akt, while PTEN C124S and G129E mutants failed to activate the phosphorylation of Akt consistently. This suggested PTEN mutations might not be correlated with activated Akt.

  7. Adenovirus-mediated transfer of the PTEN gene inhibits human colorectal cancer growth in vitro and in vivo.

    PubMed

    Saito, Y; Swanson, X; Mhashilkar, A M; Oida, Y; Schrock, R; Branch, C D; Chada, S; Zumstein, L; Ramesh, R

    2003-11-01

    The tumor-suppressor gene PTEN encodes a multifunctional phosphatase that is mutated in a variety of human cancers. PTEN inhibits the phosphatidylinositol 3-kinase pathway and downstream functions, including activation of Akt/protein kinase B (PKB), cell survival, and cell proliferation in tumor cells carrying mutant- or deletion-type PTEN. In such tumor cells, enforced expression of PTEN decreases cell proliferation through cell-cycle arrest at G1 phase accompanied, in some cases, by induction of apoptosis. More recently, the tumor-suppressive effect of PTEN has been reported in ovarian and thyroid tumors that are wild type for PTEN. In the present study, we examined the tumor-suppressive effect of PTEN in human colorectal cancer cells that are wild type for PTEN. Adenoviral-mediated transfer of PTEN (Ad-PTEN) suppressed cell growth and induced apoptosis significantly in colorectal cancer cells (DLD-1, HT29, and SW480) carrying wtPTEN than in normal colon fibroblast cells (CCD-18Co) carrying wtPTEN. This suppression was induced through downregulation of the Akt/PKB pathway, dephosphorylation of focal adhesion kinase (FAK) and mitogen-activated protein kinase (MAPK) and cell-cycle arrest at the G2/M phase, but not the G1 phase. Furthermore, treatment of human colorectal tumor xenografts (HT-29, and SW480) with Ad-PTEN resulted in significant (P=0.01) suppression of tumor growth. These results indicate that Ad-PTEN exerts its tumor-suppressive effect on colorectal cancer cells through inhibition of cell-cycle progression and induction of cell death. Thus Ad-PTEN may be a potential therapeutic for treatment of colorectal cancers. PMID:14528320

  8. Endothelial lipid phosphate phosphatase-3 deficiency that disrupts the endothelial barrier function is a modifier of cardiovascular development

    PubMed Central

    Chatterjee, Ishita; Baruah, Jugajyoti; Lurie, Erin E.; Wary, Kishore K.

    2016-01-01

    Aims Lipid phosphate phosphatase-3 (LPP3) is expressed at high levels in endothelial cells (ECs). Although LPP3 is known to hydrolyse the phosphate group from lysolipids such as spingosine-1-phosphate and its structural homologues, the function of Lpp3 in ECs is not completely understood. In this study, we investigated how tyrosine-protein kinase receptor (TEK or Tie2) promoter–dependent deletion of Lpp3 alters EC activities. Methods and results Lpp3fl/fl mice were crossed with the tg.Tie2Cre transgenic line. Vasculogenesis occurred normally in embryos with Tie2Cre-mediated deletion of Lpp3 (called Lpp3ECKO), but embryonic lethality occurred in two waves, the first wave between E8.5 and E10.5, while the second between E11.5 and E13.5. Lethality in Lpp3ECKO embryos after E11.5 was accompanied by vascular leakage and haemorrhage, which likely resulted in insufficient cardiovascular development. Analyses of haematoxylin- and eosin-stained heart sections from E11.5 Lpp3ECKO embryos showed insufficient heart growth associated with decreased trabeculation, reduced growth of the compact wall, and absence of cardiac cushions. Staining followed by microscopic analyses of Lpp3ECKO embryos revealed the presence of apoptotic ECs. Furthermore, Lpp3-deficient ECs showed decreased gene expression and protein levels of Cyclin-D1, VE-cadherin, Fibronectin, Klf2, and Klf4. To determine the underlying mechanisms of vascular leakage and barrier disruption, we performed knockdown and rescue experiments in cultured ECs. LPP3 knockdown decreased transendothelial electrical resistance and increased permeability. Re-expression of β-catenin cDNA in LPP3-knockdown ECs partially restored the effect of the LPP3 loss, whereas re-expression of p120ctn cDNA did not. Conclusion These findings demonstrate the essential roles of LPP3 in the maturation of EC barrier integrity and normal cardiovascular development. PMID:27125875

  9. Selective neuronal PTEN deletion: can we take the brakes off of growth without losing control?

    PubMed Central

    Gutilla, Erin A.; Steward, Oswald

    2016-01-01

    The limited ability for injured adult axons to regenerate is a major cause for limited functional recovery after injury to the nervous system, motivating numerous efforts to uncover mechanisms capable of enhancing regeneration potential. One promising strategy involves deletion or knockdown of the phosphatase and tensin (PTEN) gene. Conditional genetic deletion of PTEN before, immediately following, or several months after spinal cord injury enables neurons of the corticospinal tract (CST) to regenerate their axons across the lesion, which is accompanied by enhanced recovery of skilled voluntary motor functions mediated by the CST. Although conditional genetic deletion or knockdown of PTEN in neurons enables axon regeneration, PTEN is a well-known tumor suppressor and mutations of the PTEN gene disrupt brain development leading to neurological abnormalities including macrocephaly, seizures, and early mortality. The long-term consequences of manipulating PTEN in the adult nervous system, as would be done for therapeutic intervention after injury, are only now being explored. Here, we summarize evidence indicating that long-term deletion of PTEN in mature neurons does not cause evident pathology; indeed, cortical neurons that have lived without PTEN for over 1 year appear robust and healthy. Studies to date provide only a first look at potential negative consequences of PTEN deletion or knockdown, but the absence of any detectable neuropathology supports guarded optimism that interventions to enable axon regeneration after injury are achievable. PMID:27651754

  10. Selective neuronal PTEN deletion: can we take the brakes off of growth without losing control?

    PubMed

    Gutilla, Erin A; Steward, Oswald

    2016-08-01

    The limited ability for injured adult axons to regenerate is a major cause for limited functional recovery after injury to the nervous system, motivating numerous efforts to uncover mechanisms capable of enhancing regeneration potential. One promising strategy involves deletion or knockdown of the phosphatase and tensin (PTEN) gene. Conditional genetic deletion of PTEN before, immediately following, or several months after spinal cord injury enables neurons of the corticospinal tract (CST) to regenerate their axons across the lesion, which is accompanied by enhanced recovery of skilled voluntary motor functions mediated by the CST. Although conditional genetic deletion or knockdown of PTEN in neurons enables axon regeneration, PTEN is a well-known tumor suppressor and mutations of the PTEN gene disrupt brain development leading to neurological abnormalities including macrocephaly, seizures, and early mortality. The long-term consequences of manipulating PTEN in the adult nervous system, as would be done for therapeutic intervention after injury, are only now being explored. Here, we summarize evidence indicating that long-term deletion of PTEN in mature neurons does not cause evident pathology; indeed, cortical neurons that have lived without PTEN for over 1 year appear robust and healthy. Studies to date provide only a first look at potential negative consequences of PTEN deletion or knockdown, but the absence of any detectable neuropathology supports guarded optimism that interventions to enable axon regeneration after injury are achievable.

  11. Propofol Prevents Hippocampal Neuronal Loss and Memory Impairment in Cerebral Ischemia Injury Through Promoting PTEN Degradation.

    PubMed

    Chen, Xin; Du, Ye-Mu; Xu, Feng; Liu, Dai; Wang, Yuan-Lin

    2016-09-01

    Neuroprotective effect of propofol against cerebral ischemia injury was widely investigated. However, its mechanisms remain unclear. Phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway is supposed as a cell survival pathway, and phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a negative regulator of AKT phosphorylation. Whether PTEN was involved in the protective effect of propofol against cerebral ischemia injury was not elucidated. In this study, the function of PTEN in the acute phase of cerebral ischemia injury was investigated. Our data showed that propofol promoted the PTEN degradation in the acute phase of cerebral ischemia injury and concurrently activated AKT phosphorylation. The increase of ubiquitinated PTEN caused by cerebral ischemia injury were degraded in propofol-pretreated rats. Moreover, we evidenced that proteasome activity was stimulated in propofol-treated rats. These data pointed that PTEN degradation was facilitated in the acute phase after propofol treatment possibly through activating ubiquitin-proteasome system. Therefore, we applied PTEN inhibitor-bpV before cerebral ischemia injury. Like propofol, bpV pretreatment also mitigated cerebral ischemia injury-induced cell loss in CA1 region and memory impairment. Taken together, our data suggest that PTEN degradation is neuroprotective against cerebral ischemia injury and propofol facilitates PTEN degradation to prevent hippocampal neuronal loss and memory deficit in cerebral ischemia injury.

  12. Selective neuronal PTEN deletion: can we take the brakes off of growth without losing control?

    PubMed Central

    Gutilla, Erin A.; Steward, Oswald

    2016-01-01

    The limited ability for injured adult axons to regenerate is a major cause for limited functional recovery after injury to the nervous system, motivating numerous efforts to uncover mechanisms capable of enhancing regeneration potential. One promising strategy involves deletion or knockdown of the phosphatase and tensin (PTEN) gene. Conditional genetic deletion of PTEN before, immediately following, or several months after spinal cord injury enables neurons of the corticospinal tract (CST) to regenerate their axons across the lesion, which is accompanied by enhanced recovery of skilled voluntary motor functions mediated by the CST. Although conditional genetic deletion or knockdown of PTEN in neurons enables axon regeneration, PTEN is a well-known tumor suppressor and mutations of the PTEN gene disrupt brain development leading to neurological abnormalities including macrocephaly, seizures, and early mortality. The long-term consequences of manipulating PTEN in the adult nervous system, as would be done for therapeutic intervention after injury, are only now being explored. Here, we summarize evidence indicating that long-term deletion of PTEN in mature neurons does not cause evident pathology; indeed, cortical neurons that have lived without PTEN for over 1 year appear robust and healthy. Studies to date provide only a first look at potential negative consequences of PTEN deletion or knockdown, but the absence of any detectable neuropathology supports guarded optimism that interventions to enable axon regeneration after injury are achievable.

  13. Prognostic value of PTEN loss in men with conservatively managed localised prostate cancer

    PubMed Central

    Cuzick, J; Yang, Z H; Fisher, G; Tikishvili, E; Stone, S; Lanchbury, J S; Camacho, N; Merson, S; Brewer, D; Cooper, C S; Clark, J; Berney, D M; Møller, H; Scardino, P; Sangale, Z

    2013-01-01

    Background: The natural history of prostate cancer is highly variable and difficult to predict. We report on the prognostic value of phosphatase and tensin homologue (PTEN) loss in a cohort of 675 men with conservatively managed prostate cancer diagnosed by transurethral resection of the prostate. Methods: The PTEN status was assayed by immunohistochemistry (PTEN IHC) and fluorescent in situ hybridisation (PTEN FISH). The primary end point was death from prostate cancer. Results: The PTEN IHC loss was observed in 18% cases. This was significantly associated with prostate cancer death in univariate analysis (hazard ratio (HR)=3.51; 95% CI 2.60–4.73; P=3.1 × 10−14). It was highly predictive of prostate cancer death in the 50% of patients with a low risk score based on Gleason score, PSA, Ki-67 and extent of disease (HR=7.4; 95% CI 2.2–24.6; P=0.012) ), but had no prognostic value in the higher risk patients. The PTEN FISH loss was only weakly associated with PTEN IHC loss (κ=0.5). Both PTEN FISH loss and amplification were univariately predictive of death from prostate cancer, but this was not maintained in the multivariate analyses. Conclusion: In low-risk patients, PTEN IHC loss adds prognostic value to Gleason score, PSA, Ki-67 and extent of disease. PMID:23695019

  14. Propofol Prevents Hippocampal Neuronal Loss and Memory Impairment in Cerebral Ischemia Injury Through Promoting PTEN Degradation.

    PubMed

    Chen, Xin; Du, Ye-Mu; Xu, Feng; Liu, Dai; Wang, Yuan-Lin

    2016-09-01

    Neuroprotective effect of propofol against cerebral ischemia injury was widely investigated. However, its mechanisms remain unclear. Phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway is supposed as a cell survival pathway, and phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a negative regulator of AKT phosphorylation. Whether PTEN was involved in the protective effect of propofol against cerebral ischemia injury was not elucidated. In this study, the function of PTEN in the acute phase of cerebral ischemia injury was investigated. Our data showed that propofol promoted the PTEN degradation in the acute phase of cerebral ischemia injury and concurrently activated AKT phosphorylation. The increase of ubiquitinated PTEN caused by cerebral ischemia injury were degraded in propofol-pretreated rats. Moreover, we evidenced that proteasome activity was stimulated in propofol-treated rats. These data pointed that PTEN degradation was facilitated in the acute phase after propofol treatment possibly through activating ubiquitin-proteasome system. Therefore, we applied PTEN inhibitor-bpV before cerebral ischemia injury. Like propofol, bpV pretreatment also mitigated cerebral ischemia injury-induced cell loss in CA1 region and memory impairment. Taken together, our data suggest that PTEN degradation is neuroprotective against cerebral ischemia injury and propofol facilitates PTEN degradation to prevent hippocampal neuronal loss and memory deficit in cerebral ischemia injury. PMID:27480093

  15. Selective neuronal PTEN deletion: can we take the brakes off of growth without losing control?

    PubMed

    Gutilla, Erin A; Steward, Oswald

    2016-08-01

    The limited ability for injured adult axons to regenerate is a major cause for limited functional recovery after injury to the nervous system, motivating numerous efforts to uncover mechanisms capable of enhancing regeneration potential. One promising strategy involves deletion or knockdown of the phosphatase and tensin (PTEN) gene. Conditional genetic deletion of PTEN before, immediately following, or several months after spinal cord injury enables neurons of the corticospinal tract (CST) to regenerate their axons across the lesion, which is accompanied by enhanced recovery of skilled voluntary motor functions mediated by the CST. Although conditional genetic deletion or knockdown of PTEN in neurons enables axon regeneration, PTEN is a well-known tumor suppressor and mutations of the PTEN gene disrupt brain development leading to neurological abnormalities including macrocephaly, seizures, and early mortality. The long-term consequences of manipulating PTEN in the adult nervous system, as would be done for therapeutic intervention after injury, are only now being explored. Here, we summarize evidence indicating that long-term deletion of PTEN in mature neurons does not cause evident pathology; indeed, cortical neurons that have lived without PTEN for over 1 year appear robust and healthy. Studies to date provide only a first look at potential negative consequences of PTEN deletion or knockdown, but the absence of any detectable neuropathology supports guarded optimism that interventions to enable axon regeneration after injury are achievable. PMID:27651754

  16. Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization.

    PubMed

    Meng, Zhen; Gan, Ye-Hua

    2015-05-01

    Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocation and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation.

  17. Lipid Emulsion Inhibits Vasodilation Induced by a Toxic Dose of Bupivacaine via Attenuated Dephosphorylation of Myosin Phosphatase Target Subunit 1 in Isolated Rat Aorta.

    PubMed

    Ok, Seong-Ho; Byon, Hyo-Jin; Kwon, Seong-Chun; Park, Jungchul; Lee, Youngju; Hwang, Yeran; Baik, Jiseok; Choi, Mun-Jeoung; Sohn, Ju-Tae

    2015-01-01

    Lipid emulsions are widely used for the treatment of systemic toxicity that arises from local anesthetics. The goal of this in vitro study was to examine the cellular mechanism associated with the lipid emulsion-mediated attenuation of vasodilation induced by a toxic dose of bupivacaine in isolated endothelium-denuded rat aorta. The effects of lipid emulsion on vasodilation induced by bupivacaine, mepivacaine, and verapamil were assessed in isolated aorta precontracted with phenylephrine, the Rho kinase stimulant NaF, and the protein kinase C activator phorbol 12,13-dibutyrate (PDBu). The effects of Rho kinase inhibitor Y-27632 on contraction induced by phenylephrine or NaF were assessed. The effects of bupivacaine on intracellular calcium concentrations ([Ca(2+)]i) and tension induced by NaF were simultaneously measured. The effects of bupivacaine alone and lipid emulsion plus bupivacaine on myosin phosphatase target subunit 1 (MYPT1) phosphorylation induced by NaF were examined in rat aortic vascular smooth muscle cells. In precontracted aorta, the lipid emulsion attenuated bupivacaine-induced vasodilation but had no effect on mepivacaine-induced vasodilation. Y-27632 attenuated contraction induced by either phenylephrine or NaF. The lipid emulsion attenuated verapamil-induced vasodilation. Compared with phenylephrine-induced precontracted aorta, bupivacaine-induced vasodilation was slightly attenuated in NaF-induced precontracted aorta. The magnitude of the bupivacaine-induced vasodilation was higher than that of a bupivacaine-induced decrease in [Ca(2+)]i. Bupivacaine attenuated NaF-induced MYPT1 phosphorylation, whereas lipid emulsion pretreatment attenuated the bupivacaine-induced inhibition of MYPT1 phosphorylation induced by NaF. Taken together, these results suggest that lipid emulsions attenuate bupivacaine-induced vasodilation via the attenuation of inhibition of MYPT1 phosphorylation evoked by NaF.

  18. Lipid rafts regulate PCB153-induced disruption of occludin and brain endothelial barrier function through protein phosphatase 2A and matrix metalloproteinase-2

    PubMed Central

    Eum, Sung Yong; Jaraki, Dima; András, Ibolya E.; Toborek, Michal

    2015-01-01

    Occludin is an essential integral transmembrane protein regulating tight junction (TJ) integrity in brain endothelial cells. Phosphorylation of occludin is associated with its localization to TJ sites and incorporation into intact TJ assembly. The present study is focused on the role of lipid rafts in polychlorinated biphenyl (PCB)-induced disruption of occludin and endothelial barrier function. Exposure of human brain endothelial cells to 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB153) induced dephosphorylation of threonine residues of occludin and displacement of occludin from detergent-resistant membrane (DRM)/lipid raft fractions within 1 h. Moreover, lipid rafts modulated the reduction of occludin level through activation of matrix metalloproteinase 2 (MMP-2) after 24 h h PCB153 treatment. Inhibition of protein phosphatase 2A (PP2A) activity by okadaic acid or fostriecin markedly protected against PCB153-induced displacement of occludin and increased permeability of endothelial cells. The implication of lipid rafts and PP2A signaling in these processes was further defined by co-immunoprecipitation of occludin with PP2A and caveolin-1, a marker protein of lipid rafts. Indeed, a significant MMP-2 activity was observed in lipid rafts and was increased by exposure to PCB153. The pretreatment of MMP-2 inhibitors protected against PCB153-induced loss of occludin and disruption of lipid raft structure prevented the increase of endothelial permeability. Overall, these results indicate that lipid raft-associated processes, such as PP2A and MMP-2 activation, participate in PCB153-induced disruption of occludin function in brain endothelial barrier. This study contributes to a better understanding of the mechanisms leading to brain endothelial barrier dysfunction in response to exposure to environmental pollutants, such as ortho-substituted PCBs. PMID:26080028

  19. Lipid rafts regulate PCB153-induced disruption of occludin and brain endothelial barrier function through protein phosphatase 2A and matrix metalloproteinase-2.

    PubMed

    Eum, Sung Yong; Jaraki, Dima; András, Ibolya E; Toborek, Michal

    2015-09-15

    Occludin is an essential integral transmembrane protein regulating tight junction (TJ) integrity in brain endothelial cells. Phosphorylation of occludin is associated with its localization to TJ sites and incorporation into intact TJ assembly. The present study is focused on the role of lipid rafts in polychlorinated biphenyl (PCB)-induced disruption of occludin and endothelial barrier function. Exposure of human brain endothelial cells to 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) induced dephosphorylation of threonine residues of occludin and displacement of occludin from detergent-resistant membrane (DRM)/lipid raft fractions within 1h. Moreover, lipid rafts modulated the reduction of occludin level through activation of matrix metalloproteinase 2 (MMP-2) after 24h PCB153 treatment. Inhibition of protein phosphatase 2A (PP2A) activity by okadaic acid or fostriecin markedly protected against PCB153-induced displacement of occludin and increased permeability of endothelial cells. The implication of lipid rafts and PP2A signaling in these processes was further defined by co-immunoprecipitation of occludin with PP2A and caveolin-1, a marker protein of lipid rafts. Indeed, a significant MMP-2 activity was observed in lipid rafts and was increased by exposure to PCB153. The pretreatment of MMP-2 inhibitors protected against PCB153-induced loss of occludin and disruption of lipid raft structure prevented the increase of endothelial permeability. Overall, these results indicate that lipid raft-associated processes, such as PP2A and MMP-2 activation, participate in PCB153-induced disruption of occludin function in brain endothelial barrier. This study contributes to a better understanding of the mechanisms leading to brain endothelial barrier dysfunction in response to exposure to environmental pollutants, such as ortho-substituted PCBs.

  20. Inhibition of autophagy induced by PTEN loss promotes intrinsic breast cancer resistance to trastuzumab therapy.

    PubMed

    Ning, Liao; Guo-Chun, Zhang; Sheng-Li, An; Xue-Rui, Li; Kun, Wang; Jian, Zu; Chong-Yang, Ren; Ling-Zhu, Wen; Hai-Tong, Lv

    2016-04-01

    This study aims to explore the effects of the phosphatase and tension homolog (PTEN) expression level on autophagic status and on the resistance of breast cancer to trastuzumab treatment. PTEN and LC3I/II were knocked down with shRNA expression vectors, which were transfected into estrogen receptor (ER)-positive breast cancer cell lines. After trastuzumab treatment, the changes in the autophagy signal transduction pathways and autophagic proteins (LC3I/II, p62, LAMP, and cathepsin B) in these stably transfected cells were detected using western blot. The cells were also orthotopically implanted into nude mice to explore the influence of PTEN knockdown on tumor size, cell viability, and autophagic proteins after trastuzumab treatment. Similar determinations were performed using the LC3I/II overexpressed shPTEN breast cancer cells (LC3I/II-shPTEN). Downregulation of PTEN and autophagic proteins LC3-I and LC3-II was observed in resistant human breast cancer samples. Knockdown of PTEN and PTEN+ LC3I/II with shRNA in breast cancer cells resulted in increased resistance to trastuzumab. Consistently, trastuzumab treatment could not effectively reduce tumor size. Significant decreases in the levels of autophagic proteins LC3I/II, LAMP, p62, cathepsin B, and PI3K-Akt-mTOR and the signaling pathway protein Akt were found in PTEN knockdown cells, compared to the PTEN normal group, after trastuzumab administration, both in vitro and in vivo. However, these findings were reversed with the LC3I/II-shPTEN treatment. Therefore, the loss of PTEN may promote the development of primary resistance to trastuzumab in breast cancer via autophagy defects.

  1. PTEN Phosphorylation and Nuclear Export Mediate Free Fatty Acid-Induced Oxidative Stress

    PubMed Central

    Wu, Yong; Zhou, Hillary; Wu, Ke; Lee, Sangkyu; Li, Ruijin

    2014-01-01

    Abstract Aim: Oxidative stress induced by free fatty acids (FFA) contributes to metabolic syndrome-associated development of cardiovascular diseases, yet molecular mechanisms remain poorly understood. This study aimed at establishing whether phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and its subcellular location play a role in FFA-induced endothelial oxidative stress. Results: Exposing human endothelial cells (ECs) with FFA activated mammalian target of rapamycin (mTOR)/S6K pathway, and upon activation, S6K directly phosphorylated PTEN at S380. Phosphorylation of PTEN increased its interaction with its deubiquitinase USP7 in the nucleus, leading to PTEN deubiquitination and nuclear export. The reduction of PTEN in the nucleus, in turn, decreased p53 acetylation and transcription, reduced the expression of the p53 target gene glutathione peroxidase-1 (GPX1), resulting in reactive oxygen species (ROS) accumulation and endothelial damage. Finally, C57BL/6J mice fed with high-fat atherogenic diet (HFAD) showed PTEN nuclear export, decreased p53 and GPX1 protein expressions, elevated levels of ROS, and significant lesions in aortas. Importantly, inhibition of mTOR or S6K effectively blocked these effects, suggesting that mTOR/S6K pathway mediates HFAD-induced oxidative stress and vascular damage via PTEN/p53/GPX1 inhibition in vivo. Innovation: Our study demonstrated for the first time that S6K directly phosphorylated PTEN at S380 under high FFA conditions, and this phosphorylation mediated FFA-induced endothelial oxidative stress. Furthermore, we showed that S380 phosphorylation affected PTEN monoubiquitination and nuclear localization, providing the first example of coordinated regulation of PTEN nuclear localization via phosphorylation and ubiquitination. Conclusion: Our studies provide a novel mechanism by which hyperlipidemia causes vascular oxidative damage through the phosphorylation of PTEN, blocking of PTEN nuclear function, and inhibition

  2. Lipid rafts regulate PCB153-induced disruption of occludin and brain endothelial barrier function through protein phosphatase 2A and matrix metalloproteinase-2

    SciTech Connect

    Eum, Sung Yong Jaraki, Dima; András, Ibolya E.; Toborek, Michal

    2015-09-15

    Occludin is an essential integral transmembrane protein regulating tight junction (TJ) integrity in brain endothelial cells. Phosphorylation of occludin is associated with its localization to TJ sites and incorporation into intact TJ assembly. The present study is focused on the role of lipid rafts in polychlorinated biphenyl (PCB)-induced disruption of occludin and endothelial barrier function. Exposure of human brain endothelial cells to 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB153) induced dephosphorylation of threonine residues of occludin and displacement of occludin from detergent-resistant membrane (DRM)/lipid raft fractions within 1 h. Moreover, lipid rafts modulated the reduction of occludin level through activation of matrix metalloproteinase 2 (MMP-2) after 24 h PCB153 treatment. Inhibition of protein phosphatase 2A (PP2A) activity by okadaic acid or fostriecin markedly protected against PCB153-induced displacement of occludin and increased permeability of endothelial cells. The implication of lipid rafts and PP2A signaling in these processes was further defined by co-immunoprecipitation of occludin with PP2A and caveolin-1, a marker protein of lipid rafts. Indeed, a significant MMP-2 activity was observed in lipid rafts and was increased by exposure to PCB153. The pretreatment of MMP-2 inhibitors protected against PCB153-induced loss of occludin and disruption of lipid raft structure prevented the increase of endothelial permeability. Overall, these results indicate that lipid raft-associated processes, such as PP2A and MMP-2 activation, participate in PCB153-induced disruption of occludin function in brain endothelial barrier. This study contributes to a better understanding of the mechanisms leading to brain endothelial barrier dysfunction in response to exposure to environmental pollutants, such as ortho-substituted PCBs. - Highlights: • PCB153 disturbed human brain endothelial barrier through disruption of occludin. • Lipid raft-associated PP

  3. Effects of PTEN gene alteration in patients with gallbladder cancer.

    PubMed

    Ali, Asgar; Mishra, Pramod Kumar; Sharma, Sadhana; Arora, Asit; Saluja, Sundeep Singh

    2015-12-01

    Gallbladder cancer (GBC) is an aggressive malignancy usually diagnosed in an advanced stage. We investigated the effects of alterations of the phosphatase and tensin homologue (PTEN) gene on the occurrence and development of GBC, which has not been previously reported. A total 141 cases of GBC were analyzed for mutation, expression, and methylation across the nine exons of the PTEN gene. DNA sequencing methods were applied for mutation detection, whereas protein expression and methylation status were evaluated by immunohistochemical and methylation-specific PCR analysis, respectively. Novel PTEN mutations were observed in 6.3% of cases (9/141), and they included two silent mutations. In mutant cases, according to changes in codons, the respective amino acid sequences were also changed, which caused of proteins. A high percentage (72%) of loss of protein expression was observed more often in cases than in control samples. Interestingly, all nine cases with mutations showed loss of PTEN expression, whereas four of these nine cases showed positive promoter methylation. Hypermethylation was significantly more common in older patients than in younger ones (P<0.02). These findings suggest that PTEN mutations and inactivation may play an important role in the development and progression of gallbladder carcinoma. PMID:26586294

  4. Noncatalytic PTEN missense mutation predisposes to organ-selective cancer development in vivo

    PubMed Central

    Caserta, Enrico; Egriboz, Onur; Wang, Hui; Martin, Chelsea; Koivisto, Christopher; Pecót, Thierry; Kladney, Raleigh D.; Shen, Changxian; Shim, Kang-Sup; Pham, Thac; Karikomi, Matthew K.; Mauntel, Melissa J.; Majumder, Sarmila; Cuitino, Maria C.; Tang, Xing; Srivastava, Arunima; Yu, Lianbo; Wallace, Julie; Mo, Xiaokui; Park, Morag; Fernandez, Soledad A.; Pilarski, Robert; La Perle, Krista M.D.; Rosol, Thomas J.; Coppola, Vincenzo; Castrillon, Diego H.; Timmers, Cynthia; Cohn, David E.; O'Malley, David M.; Backes, Floor; Suarez, Adrian A.; Goodfellow, Paul; Chamberlin, Helen M.; Macrae, Erin R.; Shapiro, Charles L.; Ostrowski, Michael C.; Leone, Gustavo

    2015-01-01

    Inactivation of phosphatase and tensin homology deleted on chromosome 10 (PTEN) is linked to increased PI3K–AKT signaling, enhanced organismal growth, and cancer development. Here we generated and analyzed Pten knock-in mice harboring a C2 domain missense mutation at phenylalanine 341 (PtenFV), found in human cancer. Despite having reduced levels of PTEN protein, homozygous PtenFV/FV embryos have intact AKT signaling, develop normally, and are carried to term. Heterozygous PtenFV/+ mice develop carcinoma in the thymus, stomach, adrenal medulla, and mammary gland but not in other organs typically sensitive to Pten deficiency, including the thyroid, prostate, and uterus. Progression to carcinoma in sensitive organs ensues in the absence of overt AKT activation. Carcinoma in the uterus, a cancer-resistant organ, requires a second clonal event associated with the spontaneous activation of AKT and downstream signaling. In summary, this PTEN noncatalytic missense mutation exposes a core tumor suppressor function distinct from inhibition of canonical AKT signaling that predisposes to organ-selective cancer development in vivo. PMID:26302789

  5. In prostate cancer needle biopsies, detections of PTEN loss by fluorescence in situ hybridization (FISH) and by immunohistochemistry (IHC) are concordant and show consistent association with upgrading.

    PubMed

    Picanço-Albuquerque, C G; Morais, C L; Carvalho, F L F; Peskoe, S B; Hicks, J L; Ludkovski, O; Vidotto, T; Fedor, H; Humphreys, E; Han, M; Platz, E A; De Marzo, A M; Berman, D M; Lotan, T L; Squire, J A

    2016-05-01

    The prognostic value of phosphatase and tensin homolog (PTEN) loss in prostate cancer has primarily been evaluated by either fluorescence in situ hybridization (FISH) or immunohistochemistry (IHC). Previously, we found that PTEN loss by IHC was associated with increased risk of upgrading from biopsy (Gleason 3 + 3) to prostatectomy (Gleason 7+). Now, using an evaluable subset of 111 patients with adjacent biopsy sections, we analyzed the association between PTEN deletion in cancer and the odds of upgrading by a highly sensitive and specific four-color FISH assay. We also compared the concordance of PTEN loss by IHC and PTEN deletion by FISH. PTEN deletion was found in 27 % (12/45) of upgraded cases compared with 11 % (7/66) of controls (P = 0.03). Cancers with PTEN deletions were more likely to be upgraded than those without deletions (adjusting for age odds ratio = 3.40, 95 % confidence interval 1.14-10.11). With respect to concordance, of 93 biopsies with PTEN protein detected by IHC, 89 (96 %) had no PTEN deletion by FISH, and of 18 biopsies without PTEN protein by IHC, 15 had homozygous or hemizygous PTEN deletion by FISH. Only 4 biopsies of the 93 (4 %) with PTEN protein intact had PTEN deletion by FISH. When the regions of uncertainty in these biopsies were systematically studied by FISH, intra-tumoral variation of PTEN deletion was found, which could account for variation in immunoreactivity. Thus, FISH provides a different approach to determining PTEN loss when IHC is uncertain. Both FISH and IHC are concordant, showing consistent positive associations between PTEN loss and upgrading.

  6. Loss of NDRG2 expression activates PI3K-AKT signalling via PTEN phosphorylation in ATLL and other cancers

    PubMed Central

    Nakahata, Shingo; Ichikawa, Tomonaga; Maneesaay, Phudit; Saito, Yusuke; Nagai, Kentaro; Tamura, Tomohiro; Manachai, Nawin; Yamakawa, Norio; Hamasaki, Makoto; Kitabayashi, Issay; Arai, Yasuhito; Kanai, Yae; Taki, Tomohiko; Abe, Takaya; Kiyonari, Hiroshi; Shimoda, Kazuya; Ohshima, Koichi; Horii, Akira; Shima, Hiroshi; Taniwaki, Masafumi; Yamaguchi, Ryoji; Morishita, Kazuhiro

    2014-01-01

    Constitutive phosphatidylinositol 3-kinase (PI3K)-AKT activation has a causal role in adult T-cell leukaemia-lymphoma (ATLL) and other cancers. ATLL cells do not harbour genetic alterations in PTEN and PI3KCA but express high levels of PTEN that is highly phosphorylated at its C-terminal tail. Here we report a mechanism for the N-myc downstream-regulated gene 2 (NDRG2)-dependent regulation of PTEN phosphatase activity via the dephosphorylation of PTEN at the Ser380, Thr382 and Thr383 cluster within the C-terminal tail. We show that NDRG2 is a PTEN-binding protein that recruits protein phosphatase 2A (PP2A) to PTEN. The expression of NDRG2 is frequently downregulated in ATLL, resulting in enhanced phosphorylation of PTEN at the Ser380/Thr382/Thr383 cluster and enhanced activation of the PI3K-AKT pathway. Given the high incidence of T-cell lymphoma and other cancers in NDRG2-deficient mice, PI3K-AKT activation via enhanced PTEN phosphorylation may be critical for the development of cancer. PMID:24569712

  7. Endothelial Cell Surface Expressed Chemotaxis and Apoptosis Regulator (ECSCR) Regulates Lipolysis in White Adipocytes via the PTEN/AKT Signaling Pathway

    PubMed Central

    Kilari, Sreenivasulu; Cossette, Stephanie; Pooya, Shabnam; Bordas, Michelle; Huang, Yi-Wen

    2015-01-01

    Elevated plasma triglycerides are associated with increased susceptibility to heart disease and stroke, but the mechanisms behind this relationship are unclear. A clearer understanding of gene products which influence plasma triglycerides might help identify new therapeutic targets for these diseases. The Endothelial Cell Surface expressed Chemotaxis and apoptosis Regulator (ECSCR) was initially studied as an endothelial cell marker, but has recently been identified in white adipocytes, the primary storage cell type for triglycerides. Here we confirm ECSCR expression in white adipocytes and show that Ecscr knockout mice show elevated fasting plasma triglycerides. At a cellular level, cultured 3T3-L1 adipocytes silenced for Ecscr show a blunted Akt phosphorylation response. Additionally we show that the phosphatase and tensin homology containing (PTEN) lipid phosphatase association with ECSCR is increased by insulin stimulation. These data suggest a scenario by which ECSCR contributes to control of white adipocyte lipolysis. In this scenario, white adipocytes lacking Ecscr display elevated PTEN activity, thereby reducing AKT activation and impairing insulin-mediated suppression of lipolysis. Collectively, these results suggest that ECSCR plays a critical function in regulating lipolysis in white adipose tissue. PMID:26692198

  8. Direct modification and regulation of a nuclear receptor-PIP2 complex by the nuclear inositol-lipid kinase IPMK

    PubMed Central

    Blind, Raymond D.; Suzawa, Miyuki; Ingraham, Holly A.

    2012-01-01

    Phosphatidylinositol (4,5)-bisphosphate (PIP2) is best known as a plasma membrane-bound regulatory lipid. While PIP2 and phosphoinositide-modifying enzymes coexist in the nucleus, their roles in the nucleus remain unclear. Here we show that the nuclear inositol polyphosphate multikinase (IPMK), which functions both as an inositol- and a PI3-kinase, interacts with the nuclear receptor SF-1 (NR5A1) and phosphorylates its bound ligand, PIP2. IPMK failed to recognize SF-1/PIP2 after blocking or displacing PIP2 from SF-1’s large hydrophobic pocket. In contrast to IPMK, p110 catalytic subunits of type 1 PI3-kinases were inactive on SF-1/PIP2. These and other in vitro analyses demonstrated specificity of IPMK for the SF-1/PIP2 protein/lipid complex. Once generated, SF-1/PIP3 is readily dephosphorylated by the lipid phosphatase PTEN. Importantly, decreasing IPMK or increasing PTEN expression greatly reduced SF-1 transcriptional activity. This ability of lipid kinases and phosphatases to alter the activity and directly remodel a non-membrane protein/lipid complex such SF-1/PIP2, establishes a new pathway for promoting lipid-mediated signaling in the nucleus. PMID:22715467

  9. Relationship between PTEN, DNA mismatch repair, and tumor histotype in endometrial carcinoma: retained positive expression of PTEN preferentially identifies sporadic non-endometrioid carcinomas.

    PubMed

    Djordjevic, Bojana; Barkoh, Bedia A; Luthra, Rajyalakshmi; Broaddus, Russell R

    2013-10-01

    Loss of PTEN (phosphatase and tensin homolog) expression and microsatellite instability are two of the more common molecular alterations in endometrial carcinoma. From the published literature, it is controversial as to whether there is a relationship between these different molecular mechanisms. Therefore, a cohort of 187 pure endometrioid and non-endometrioid endometrial carcinomas, carefully characterized as to clinical and pathological features, was examined for PTEN sequence abnormalities and the immunohistochemical expression of PTEN and the DNA mismatch repair proteins MLH1, MSH2, MSH6, and PMS2. MLH1 methylation analysis was performed when tumors had loss of MLH1 protein. Mismatch repair protein loss was more frequent in endometrioid carcinomas compared with non-endometrioid carcinomas, a difference primarily attributable to the presence of MLH1 methylation in a greater proportion of endometrioid tumors. Among the non-endometrioid group, mixed endometrioid/non-endometrioid carcinomas were the histotype that most commonly had loss of a mismatch repair protein. In endometrioid tumors, the frequency of PTEN loss measured by immunohistochemistry and mutation did not differ significantly between the mismatch repair protein intact or mismatch repair protein loss groups, suggesting that PTEN loss is independent of mismatch protein repair status in this group. However, in non-endometrioid carcinomas, both intact positive PTEN immunohistochemical expression and PTEN wild type were highly associated with retained positive expression of mismatch repair proteins in the tumor. Relevant to screening endometrial cancers for Lynch Syndrome, an initial PTEN immunohistochemistry determination may be able to replace the use of four mismatch repair immunohistochemical markers in 63% of patients with non-endometrioid endometrial carcinoma. Therefore, PTEN immunohistochemistry, in combination with tumor histotype, is a useful adjunct in the clinical evaluation of endometrial

  10. EGFR- and AKT-mediated reduction in PTEN expression contributes to tyrphostin resistance and is reversed by mTOR inhibition in endometrial cancer cells.

    PubMed

    Li, Tian; Yang, Yuebo; Li, Xiaomao; Xu, Chengfang; Meng, Lirong

    2012-02-01

    Loss or mutation of the PTEN (phosphatase and tensin homologue deleted on chromosome 10) gene is associated with resistance to epidermal growth factor receptor (EGFR) inhibitors. However, the mechanism underlying remains elusive. In this study, we aimed to explore whether sensitivity to the EGFR tyrosine kinase inhibitor (TKI) is affected by PTEN status in endometrial cancer cells. PTEN siRNA and the PTEN gene were transfected into HEC-1A and Ishikawa endometrial cancer cells using lentiviral vectors. Cells were treated under various concentrations of RG14620 and rapamycin, which are EGFR and mammalian target of rapamycin (mTOR) inhibitors, respectively. The IC(50) of RG16420 was determined by using the MTT method. Cell apoptosis and the cell cycle were studied, and activation of EGFR, AKT, and p70S6 were detected by Western blot analysis. Loss of PTEN promoted cell proliferation and led to significant increases in the levels of EGFR, phospho-EGFR, AKT, phospho-AKT, and phospho-mTOR proteins. Ishikawa and HEC-1A(PTENkd) cells that displayed loss and inactivation of PTEN function were resistant to RG14620. HEC-1A and Ishikawa(PTEN) cells with intact PTEN were sensitive to RG14620. The combination of two inhibitors was more effective than both monotherapies, particularly in carcinoma cells with PTEN dysfunction. Decreased phospho-EGFR protein expression was observed in all cell lines that were sensitive to RG14620. Decreased phospho-AKT and phospho-p70S6 protein expression was observed in PTEN-intact cells that were sensitive to RG14620. PTEN loss results in resistance to EGFR TKI, which was reversed by PTEN reintroduction or mTOR inhibitor treatment. The combined treatment of EGFR TKI and the mTOR inhibitor provided a synergistic effect by promoting cell death in PTEN-deficient and PTEN-intact endometrial cancer cells, particularly in PTEN-deficient carcinoma cells with up-regulated EGFR activation.

  11. Upregulation of PTEN suppresses invasion in Tca8113 tongue cancer cells through repression of epithelial-mesenchymal transition (EMT).

    PubMed

    Xie, Siming; Lu, Zhiyuan; Lin, Yanzhu; Shen, Lijia; Yin, Cao

    2016-05-01

    We previously discovered that the expression of the tumor suppressor phosphatase and tensin homolog (PTEN) was downregulated in the majority patients with tongue squamous cell carcinoma (TSCC). The aim of this study was to investigate the role of PTEN overexpression in the regulation of epithelial-mesenchymal transition (EMT) of the tongue squamous carcinoma cell line Tca8113 as well as explore the underlying mechanism. GV230 (containing the PTEN gene) and empty vectors were transfected into Tca8113 cells. After stable transfection, the messenger RNA (mRNA) and protein levels of PTEN were validated using quantitative real-time PCR (qPCR) and Western blot analysis. The growth and cell cycle were analyzed using Cell Counting Kit-8 (CCK-8) and flow cytometry, respectively. The invasion ability was measured with a transwell assay. The effects of PTEN overexpression on EMT and Hedgehog signaling were assessed by comparing Tca8113-PTEN cells with control and negative control cell groups. We found that PTEN expression was significantly upregulated after transfection. Meanwhile, upregulated PTEN inhibited the proliferation and invasion of Tca8113 cells. In addition, we observed changes in the EMT- and Hedgehog-associated proteins. These data demonstrated that PTEN upregulation could reduce invasion by inhibiting the process of EMT in Tca8113 cells, which might be related to the Hedgehog signaling pathway.

  12. Upregulation of PTEN suppresses invasion in Tca8113 tongue cancer cells through repression of epithelial-mesenchymal transition (EMT).

    PubMed

    Xie, Siming; Lu, Zhiyuan; Lin, Yanzhu; Shen, Lijia; Yin, Cao

    2016-05-01

    We previously discovered that the expression of the tumor suppressor phosphatase and tensin homolog (PTEN) was downregulated in the majority patients with tongue squamous cell carcinoma (TSCC). The aim of this study was to investigate the role of PTEN overexpression in the regulation of epithelial-mesenchymal transition (EMT) of the tongue squamous carcinoma cell line Tca8113 as well as explore the underlying mechanism. GV230 (containing the PTEN gene) and empty vectors were transfected into Tca8113 cells. After stable transfection, the messenger RNA (mRNA) and protein levels of PTEN were validated using quantitative real-time PCR (qPCR) and Western blot analysis. The growth and cell cycle were analyzed using Cell Counting Kit-8 (CCK-8) and flow cytometry, respectively. The invasion ability was measured with a transwell assay. The effects of PTEN overexpression on EMT and Hedgehog signaling were assessed by comparing Tca8113-PTEN cells with control and negative control cell groups. We found that PTEN expression was significantly upregulated after transfection. Meanwhile, upregulated PTEN inhibited the proliferation and invasion of Tca8113 cells. In addition, we observed changes in the EMT- and Hedgehog-associated proteins. These data demonstrated that PTEN upregulation could reduce invasion by inhibiting the process of EMT in Tca8113 cells, which might be related to the Hedgehog signaling pathway. PMID:26649861

  13. In Vitro and In Vivo Effects of Tumor Suppressor Gene PTEN on Endometriosis: An Experimental Study

    PubMed Central

    Lv, Juan; Zhu, Qiaoying; Jia, Xuemei; Yu, Ningzhu; Li, Qian

    2016-01-01

    Background Endometriosis can cause dysmenorrhea and infertility. Its pathogenesis has not yet been clarified and its treatment continues to pose enormous challenges. The protein tyrosine phosphatase (PTEN) gene is a tumor suppressor gene. The aim of this study was to investigate the role and significance of PTEN protein in the occurrence, development, and treatment of endometriosis through changes in apoptosis rate, cell cycle, and angiogenesis. Material/Methods PTEN was overexpressed and silenced in lentiviral vectors and inserted into primary endometrial cells. The changes in cell cycle and apoptosis in the different PTEN expression groups were evaluated using flow cytometry. Vessel growth mimicry was observed using 3-dimensional culture. A human-mouse chimeric endometriosis model was constructed using SCID mice. Hematoxylin and eosin staining and immunohistochemistry were used to detect pathological changes in ectopic endometrial tissues and the expression of VEGF protein in a human-mouse chimeric endometriosis mouse model. Results PTEN overexpression significantly increased apoptosis and inhibited the cell cycle compared with the silenced and control groups. Furthermore, cells expressing low PTEN levels were better able to undergo vasculogenic mimicry, and exhibited significantly increased angiogenesis compared to cells overexpressing PTEN. We found that ectopic foci were more easily formed in the endometrial tissue of SCID mice with low PTEN expression, and the VEGF expression in this group was relatively high. Conclusions PTEN inhibits the occurrence and development of endometriosis by regulating angiogenesis and the apoptosis and cell cycle of endometrial cells; therefore, we propose that the PTEN gene can be used to treat endometriosis. PMID:27744455

  14. Synergistic tumor suppression by adenovirus-mediated ING4/PTEN double gene therapy for gastric cancer.

    PubMed

    Zhang, H; Zhou, X; Xu, C; Yang, J; Xiang, J; Tao, M; Xie, Y

    2016-01-01

    Both inhibitor of growth 4 (ING4) and phosphatase and tensin homolog (PTEN) have been shown to be strong candidate tumor suppressors. However, the combined efficacy of ING4 and PTEN for human gastric cancer remains to be determined. In this report, we constructed a multiple promoter expression cassette-based recombinant adenovirus coexpressing ING4 and PTEN (AdVING4/PTEN), assessed the combined effects of AdVING4/PTEN on gastric cancer using wild-type p53 AGS and SNU-1 human gastric cancer cell lines, and elucidated its underlying mechanisms. We found that AdVING4/PTEN-induced synergistic growth inhibition and apoptosis in vitro AGS or SNU-1 tumor cells and in vivo AGS xenografted tumors subcutaneously inoculated in athymic BALB/c nude mice. Mechanistically, AdVING4/PTEN exhibited an enhanced effect on upregulation of p53, Ac-p53 (K382), P21, Bax, PUMA, Noxa, cleaved Caspase-9, cleaved Caspase-3 and cleaved PARP as well as downregulation of Bcl-2 in vitro and in vivo. In addition, AdVING4/PTEN synergistically downregulated tumor vessel CD34 expression and reduced microvessel density, and additively inhibited vascular endothelial growth factor (VEGF) expression in vivo. The synergistic tumor suppression elicited by AdVING4/PTEN was closely associated with the synergistic induction of apoptosis possibly via enhancement of endogenous p53 responses through cooperatively facilitating p53's stability and acetylation, and the synergistic inhibition of tumor angiogenesis probably via overlapping reduction of VEGF through cooperatively downregulating hypoxia inducible factor-1α's level and transcription activity. Thus, our results indicate that cancer gene therapy combining ING4 and PTEN may constitute a novel and effective therapeutic modality for human gastric cancer and other cancers.

  15. Long-term consequences of conditional genetic deletion of PTEN in the sensorimotor cortex of neonatal mice.

    PubMed

    Gutilla, Erin A; Buyukozturk, Melda M; Steward, Oswald

    2016-05-01

    Targeted deletion of the phosphatase and tensin homolog on chromosome ten (PTEN) gene in the sensorimotor cortex of neonatal mice enables robust regeneration of corticospinal tract (CST) axons following spinal cord injury as adults. Here, we assess the consequences of long-term conditional genetic PTEN deletion on cortical structure and neuronal morphology and screen for neuropathology. Mice with a LoxP-flanked exon 5 of the PTEN gene (PTENf/f mice) received AAV-Cre injections into the sensorimotor cortex at postnatal day 1 (P1) and were allowed to survive for up to 18months. As adults, mice were assessed for exploratory activity (open field), and motor coordination using the Rotarod®. Some mice received injections of Fluorogold into the spinal cord to retrogradely label the cells of origin of the CST. Brains were prepared for neurohistology and immunostained for PTEN and phospho-S6, which is a downstream marker of mammalian target of rapamycin (mTOR) activation. Immunostaining revealed a focal area of PTEN deletion affecting neurons in all cortical layers, although in some cases PTEN expression was maintained in many small-medium sized neurons in layers III-IV. Neurons lacking PTEN were robustly stained for pS6. Cortical thickness was significantly increased and cortical lamination was disrupted in the area of PTEN deletion. PTEN-negative layer V neurons that give rise to the CST, identified by retrograde labeling, were larger than neurons with maintained PTEN expression, and the relative area occupied by neuropil vs. cell bodies was increased. There was no evidence of tumor formation or other neuropathology. Mice with PTEN deletion exhibited open field activity comparable to controls and there was a trend for impaired Rotarod performance (not statistically significant). Our findings indicate that early postnatal genetic deletion of PTEN that is sufficient to enable axon regeneration by adult neurons causes neuronal hypertrophy but no other detectable

  16. Targeted deletion of PTEN in cardiomyocytes renders cardiac contractile dysfunction through interruption of Pink1-AMPK signaling and autophagy.

    PubMed

    Roe, Nathan D; Xu, Xihui; Kandadi, Machender R; Hu, Nan; Pang, Jiaojiao; Weiser-Evans, Mary C M; Ren, Jun

    2015-02-01

    Phosphatase and tensin homolog (PTEN) deleted from chromosome 10 has been implicated in the maintenance of cardiac homeostasis although the underlying mechanism(s) remains elusive. We generated a murine model of cardiomyocyte-specific knockout of PTEN to evaluate cardiac geometry and contractile function, as well as the effect of metformin on PTEN deficiency-induced cardiac anomalies, if any. Cardiac histology, autophagy and related signaling molecules were evaluated. Cardiomyocyte-specific PTEN deletion elicited cardiac hypertrophy and contractile anomalies (echocardiographic and cardiomyocyte contractile dysfunction) associated with compromised intracellular Ca(2+) handling. PTEN deletion-induced cardiac hypertrophy and contractile anomalies were associated with dampened phosphorylation of PTEN-inducible kinase 1 (Pink1) and AMPK. Interestingly, administration of AMPK activator metformin (200mg/kg/d, in drinking H2O for 4weeks) rescued against PTEN deletion-induced geometric and functional defects as well as interrupted autophagy and autophagic flux in the heart. Moreover, metformin administration partially although significantly attenuated PTEN deletion-induced accumulation of superoxide. RNA interference against Pink1 in H9C2 myoblasts overtly increased intracellular ATP levels and suppressed AMPK phosphorylation, confirming the role of AMPK as a downstream target for PTEN-Pink1. Further scrutiny revealed that activation of AMPK and autophagy using metformin and rapamycin, respectively, rescued against PTEN deletion-induced mechanical anomalies with little additive effect. These data demonstrated that cardiomyocyte-specific deletion of PTEN leads to the loss of Pink1-AMPK signaling, development of cardiac hypertrophy and contractile defect. Activation of AMPK rescued against PTEN deletion-induced cardiac anomalies associated with restoration of autophagy and autophagic flux. This article is part of a Special Issue entitled: Autophagy and protein quality control

  17. The association of PTEN hypermethylation and breast cancer: a meta-analysis

    PubMed Central

    Luo, Shanshan; Chen, Jiansi; Mo, Xianwei

    2016-01-01

    Objective Phosphatase and tensin homolog (PTEN) deleted on chromosome 10, as a tumor suppressor gene, is crucial for the development of both familial and sporadic breast cancer (BC). The aim of this study was to perform a meta-analysis to evaluate the clinicopathological significance of PTEN promoter hypermethylation in BC. Methods A comprehensive literature search was made in PubMed, Embase, Google Scholar, Chinese database (China National Knowledge Infrastructure [CNKI]), and Web of Science. The analysis of pooled data was performed with Review Manager 5.2. The fixed-effects or random-effects models were used to evaluate odds ratios (ORs) and 95% confidence intervals (CIs). Results The meta-analysis included eight studies and a total of 923 patients. The frequency of PTEN promoter hypermethylation was significantly increased in ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) compared to normal breast tissues (OR =22.53, P=0.0002 and OR =22.86, P<0.00001, respectively). However, the frequency of PTEN promoter hypermethylation was similar between IDC and DCIS. Additionally, PTEN methylation was not significantly correlated to estrogen receptor (ER) or human epidermal growth factor type 2 (HER-2) status in patients with BC. Conclusion PTEN promoter hypermethylation is significantly associated with the risk of DCIS and IDC, suggesting PTEN promoter hypermethylation is a valuable biomarker for diagnosis of BC.

  18. PTEN opposes negative selection and enables oncogenic transformation of pre-B cells.

    PubMed

    Shojaee, Seyedmehdi; Chan, Lai N; Buchner, Maike; Cazzaniga, Valeria; Cosgun, Kadriye Nehir; Geng, Huimin; Qiu, Yi Hua; von Minden, Marcus Dühren; Ernst, Thomas; Hochhaus, Andreas; Cazzaniga, Giovanni; Melnick, Ari; Kornblau, Steven M; Graeber, Thomas G; Wu, Hong; Jumaa, Hassan; Müschen, Markus

    2016-04-01

    Phosphatase and tensin homolog (PTEN) is a negative regulator of the phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT) signaling pathway and a potent tumor suppressor in many types of cancer. To test a tumor suppressive role for PTEN in pre-B acute lymphoblastic leukemia (ALL), we induced Cre-mediated deletion of Pten in mouse models of pre-B ALL. In contrast to its role as a tumor suppressor in other cancers, loss of one or both alleles of Pten caused rapid cell death of pre-B ALL cells and was sufficient to clear transplant recipient mice of leukemia. Small-molecule inhibition of PTEN in human pre-B ALL cells resulted in hyperactivation of AKT, activation of the p53 tumor suppressor cell cycle checkpoint and cell death. Loss of PTEN function in pre-B ALL cells was functionally equivalent to acute activation of autoreactive pre-B cell receptor signaling, which engaged a deletional checkpoint for the removal of autoreactive B cells. We propose that targeted inhibition of PTEN and hyperactivation of AKT triggers a checkpoint for the elimination of autoreactive B cells and represents a new strategy to overcome drug resistance in human ALL.

  19. The association of PTEN hypermethylation and breast cancer: a meta-analysis

    PubMed Central

    Luo, Shanshan; Chen, Jiansi; Mo, Xianwei

    2016-01-01

    Objective Phosphatase and tensin homolog (PTEN) deleted on chromosome 10, as a tumor suppressor gene, is crucial for the development of both familial and sporadic breast cancer (BC). The aim of this study was to perform a meta-analysis to evaluate the clinicopathological significance of PTEN promoter hypermethylation in BC. Methods A comprehensive literature search was made in PubMed, Embase, Google Scholar, Chinese database (China National Knowledge Infrastructure [CNKI]), and Web of Science. The analysis of pooled data was performed with Review Manager 5.2. The fixed-effects or random-effects models were used to evaluate odds ratios (ORs) and 95% confidence intervals (CIs). Results The meta-analysis included eight studies and a total of 923 patients. The frequency of PTEN promoter hypermethylation was significantly increased in ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) compared to normal breast tissues (OR =22.53, P=0.0002 and OR =22.86, P<0.00001, respectively). However, the frequency of PTEN promoter hypermethylation was similar between IDC and DCIS. Additionally, PTEN methylation was not significantly correlated to estrogen receptor (ER) or human epidermal growth factor type 2 (HER-2) status in patients with BC. Conclusion PTEN promoter hypermethylation is significantly associated with the risk of DCIS and IDC, suggesting PTEN promoter hypermethylation is a valuable biomarker for diagnosis of BC. PMID:27672335

  20. Phosphatase and tensin homolog deleted on chromosome 10 contributes to phenotype transformation of fibroblasts in idiopathic pulmonary fibrosis via multiple pathways

    PubMed Central

    Geng, Jing; Huang, Xiaoxi; Li, Ying; Xu, Xuefeng; Li, Shuhong; Jiang, Dingyuan; Liu, Zheng

    2015-01-01

    Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease and considered as a cancer-like disease. The phosphatase and tensin homologue deleted on chromosome 10 (PTEN) tumor suppressor has drawn attention in the pathogenesis of IPF. However, the role of PTEN in phenotypic transformation of lung fibroblasts, particularly in the migratory and invasive phenotype, is still elusive. Our data showed that PTEN expression was markedly reduced in both fibroblasts and myofibroblasts from IPF patients. Furthermore, loss of PTEN led to the transformation of normal fibroblasts to myofibroblasts and increased proliferation, apoptosis resistance, and migration/invasion activities. PTEN deficiency upregulated hyaluronan synthase 2 expression and thereby enhanced the invasion ability of fibroblasts. Cross-talk between PTEN and the transforming growth factor β1 (TGF-β1) pathway and PTEN reduction by hypoxia were observed. These findings suggest that PTEN is implicated in multiple pathways and plays a crucial role in the pathogenesis of IPF. PMID:26264443

  1. Deletion of PTEN Produces Deficits in Conditioned Fear and Increases Fragile X Mental Retardation Protein

    ERIC Educational Resources Information Center

    Lugo, Joaquin N.; Smith, Gregory D.; Morrison, Jessica B.; White, Jessika

    2013-01-01

    The phosphatase and tensin homolog detected on chromosome 10 (PTEN) gene product modulates activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. The PI3K pathway has been found to be involved in the regulation of the fragile X mental retardation protein, which is important for long-term depression and in the formation of new…

  2. Lipid phosphate phosphatase-1 regulates lysophosphatidic acid-induced calcium release, NF-κB activation and interleukin-8 secretion in human bronchial epithelial cells

    PubMed Central

    2004-01-01

    LPA (lysophosphatidic acid), a potent bioactive phospholipid, elicits diverse cellular responses through activation of the G-protein-coupled receptors LPA1–LPA4. LPA-mediated signalling is partially regulated by LPPs (lipid phosphate phosphatases; LPP-1, -2 and -3) that belong to the phosphatase superfamily. This study addresses the role of LPPs in regulating LPA-mediated cell signalling and IL-8 (interleukin-8) secretion in HBEpCs (human bronchial epithelial cells). Reverse transcription–PCR and Western blotting revealed the presence and expression of LPP-1–3 in HBEpCs. Exogenous [3H]oleoyl LPA was hydrolysed to [3H]-mono-oleoylglycerol. Infection of HBEpCs with an adenoviral construct of human LPP-1 for 48 h enhanced the dephosphorylation of exogenous LPA by 2–3-fold compared with vector controls. Furthermore, overexpression of LPP-1 partially attenuated LPA-induced increases in the intracellular Ca2+ concentration, phosphorylation of IκB (inhibitory κB) and translocation of NF-κB (nuclear factor-κB) to the nucleus, and almost completely prevented IL-8 secretion. Infection of cells with an adenoviral construct of the mouse LPP-1 (R217K) mutant partially attenuated LPA-induced IL-8 secretion without altering LPA-induced changes in intracellular Ca2+ concentration, phosphorylation of IκB, NF-κB activation or IL-8 gene expression. Our results identify LPP-1 as a key regulator of LPA signalling and IL-8 secretion in HBEpCs. Thus LPPs could represent potential targets in regulating leucocyte infiltration and airway inflammation. PMID:15461590

  3. Mitochondrial Dysfunction in Pten Haplo-Insufficient Mice with Social Deficits and Repetitive Behavior: Interplay between Pten and p53

    PubMed Central

    Napoli, Eleonora; Ross-Inta, Catherine; Wong, Sarah; Hung, Connie; Fujisawa, Yasuko; Sakaguchi, Danielle; Angelastro, James; Omanska-Klusek, Alicja; Schoenfeld, Robert; Giulivi, Cecilia

    2012-01-01

    Etiology of aberrant social behavior consistently points to a strong polygenetic component involved in fundamental developmental pathways, with the potential of being enhanced by defects in bioenergetics. To this end, the occurrence of social deficits and mitochondrial outcomes were evaluated in conditional Pten (Phosphatase and tensin homolog) haplo-insufficient mice, in which only one allele was selectively knocked-out in neural tissues. Pten mutations have been linked to Alzheimer's disease and syndromic autism spectrum disorders, among others. By 4–6 weeks of age, Pten insufficiency resulted in the increase of several mitochondrial Complex activities (II–III, IV and V) not accompanied by increases in mitochondrial mass, consistent with an activation of the PI3K/Akt pathway, of which Pten is a negative modulator. At 8–13 weeks of age, Pten haplo-insufficient mice did not show significant behavioral abnormalities or changes in mitochondrial outcomes, but by 20–29 weeks, they displayed aberrant social behavior (social avoidance, failure to recognize familiar mouse, and repetitive self-grooming), macrocephaly, increased oxidative stress, decreased cytochrome c oxidase (CCO) activity (50%) and increased mtDNA deletions in cerebellum and hippocampus. Mitochondrial dysfunction was the result of a downregulation of p53-signaling pathway evaluated by lower protein expression of p21 (65% of controls) and the CCO chaperone SCO2 (47% of controls), two p53-downstream targets. This mechanism was confirmed in Pten-deficient striatal neurons and, HCT 116 cells with different p53 gene dosage. These results suggest a unique pathogenic mechanism of the Pten-p53 axis in mice with aberrant social behavior: loss of Pten (via p53) impairs mitochondrial function elicited by an early defective assembly of CCO and later enhanced by the accumulation of mtDNA deletions. Consistent with our results, (i) SCO2 deficiency and/or CCO activity defects have been reported in patients with

  4. Enhanced lymphocyte interferon (IFN)-γ responses in a PTEN mutation-negative Cowden disease kindred

    PubMed Central

    Stevenson, R; Fatehullah, A; Jagan, I; Deevi, R K; Bingham, V; Irvine, A E; Armstrong, M; Morrison, P J; Dimmick, I; Stewart, R; Campbell, F C

    2011-01-01

    Identification of immune modifiers of inherited cancer syndromes may provide a rationale for preventive therapy. Cowden disease (CD) is a genetically heterogeneous inherited cancer syndrome that arises predominantly from germline phosphatase and tensin homologue deleted on chromosome 10 (PTEN) mutation and increased phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) signalling. However, many patients with classic CD diagnostic features are mutation-negative for PTEN (PTEN M-Neg). Interferon (IFN)-γ can modulate the PI3K/mTOR pathway, but its association with PTEN M-Neg CD remains unclear. This study assessed IFN-γ secretion by multi-colour flow cytometry in a CD kindred that was mutation-negative for PTEN and other known susceptibility genes. Because IFN-γ responses may be regulated by killer cell immunoglobulin-like receptors (KIR) and respective human leucocyte antigen (HLA) ligands, KIR/HLA genotypes were also assessed. Activating treatments induced greater IFN-γ secretion in PTEN M-Neg CD peripheral blood lymphocytes versus healthy controls. Increased frequency of activating KIR genes, potentially activating KIR/HLA compound genotypes and reduced frequency of inhibitory genotypes, were found in the PTEN M-Neg CD kindred. Differences of IFN-γ secretion were observed among PTEN M-Neg CD patients with distinct KIR/HLA compound genotypes. Taken together, these findings show enhanced lymphocyte secretion of IFN-γ that may influence the PI3K/mTOR CD causal molecular pathway in a PTEN mutation-negative CD kindred. PMID:21361912

  5. Restoring E-cadherin-mediated cell-cell adhesion increases PTEN protein level and stability in human breast carcinoma cells

    SciTech Connect

    Li Zengxia; Wang Liying; Zhang Wen; Fu Yi; Zhao Hongbo; Hu Yali; Prins, Bram Peter; Zha Xiliang

    2007-11-09

    The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a well-characterized tumor suppressor that negatively regulates cell growth and survival. Despite the critical role of PTEN in cell signaling, the mechanisms of its regulation are still under investigation. We reported here that PTEN expression could be controlled by overexpression or knock-down of E-cadherin in several mammary carcinoma cell lines. Furthermore, we showed that the accumulation of PTEN protein in E-cadherin overexpressing cells was due to increased PTEN protein stability rather than the regulation of its transcription. The proteasome-dependent PTEN degradation pathway was impaired after restoring E-cadherin expression. Moreover, maintenance of E-cadherin mediated cell-cell adhesion was necessary for its regulating PTEN. Altogether, our results suggested that E-cadherin mediated cell-cell adhesion was essential for preventing the proteasome degradation of PTEN, which might explain how breast carcinoma cells which lost cell-cell contact proliferate rapidly and are prone to metastasis.

  6. Oridonin upregulates PTEN through activating p38 MAPK and inhibits proliferation in human colon cancer cells.

    PubMed

    Wu, Qiu-Xiang; Yuan, Shuang-Xue; Ren, Chun-Mei; Yu, Yu; Sun, Wen-Juan; He, Bai-Cheng; Wu, Ke

    2016-06-01

    Oridonin (ORI) has been reported as an antiproliferation and apoptosis-inducing natural product in various cancer cells. However, the exact molecular mechanism underlying these effects remains unclear. In the present study, we demonstrated the antiproliferation effect of ORI in HCT116 cells, and analyzed the possible molecular mechanism which mediates this effect. We found that ORI inhibits proliferation, induces cell cycle arrest and apoptosis in HCT116 cells, thus also tumor growth. Mechanically, we found that ORI has no substantial effect on mRNA expression of phosphatase and tensin homologue (PTEN), but increases the total protein level of PTEN and markedly reduces the phosphorylation of PTEN; Exogenous expression of PTEN potentiates the anticancer effect of ORI, while knockdown of PTEN attenuates it. ORI also increases the phosphorylation of p38 MAPK, and p38 MAPK-specific inhibitor reduces the antiproliferation effect ORI in HCT116 cells. Moreover, inhibition of p38 MAPK increases the phosphorylation of PTEN, and reverses ORI-induced decrease of PTEN phosphorylation. Our findings suggested that ORI may be a potential anticancer drug for colon cancer, this effect may be mediated by enhancing the function of PTEN through reducing its phosphorylation, which may be resulted from the ORI-induced activation of p38 MAPK.

  7. Testosterone improves the transition of primary oocytes in artificial maturation eels (Anguilla japonica) by altering ovarian PTEN expression.

    PubMed

    Huang, Yung-Sen; Chen, Ya-Mei; Liao, Pei-Chi; Lee, Yan-Horn; Gwo, Jin-Chywan; Chen, Ming-Chyuan; Chang, Ching-Fong

    2012-06-01

    In mammals, androgens appear to enhance the development of primary ovarian follicles, but PI3K (phosphoinositide 3-kinases) pathway is well recognized as one of the critical pathways in early follicular development. Roles of the PI3K were revealed by deletion of PTEN (phosphatase and tensin homolog on chromosome 10). PTEN is demonstrated to play an important role in the early stage of follicle development. In the Japanese eel, two forms of PTEN have been cloned, but what their functions on the development of early ovarian follicles are still not clear. The natural blockage and inducible of ovarian development was a benefit to address this question in the eel. Testosterone (T) shows to ameliorate the early ovarian development in the eel. The aims of this study were to elucidate the two forms of PTEN by cellular and physiological criteria and to study the effects of T on the ovarian PTEN production in the exogenous pituitary extracts-stimulated eel. Our results suggested that two forms of PTEN are existing in the Japanese eel, and eel ovarian development corresponded to the decrease in ovarian PTEN expression, vice versa. In addition, the supplement of T on eel early ovarian development can be attributed to its PTEN inhibitor role.

  8. Inhibition of PTEN expression and activity by angiotensin II induces proliferation and migration of vascular smooth muscle cells.

    PubMed

    Dong, Xue; Yu, Lu-Gang; Sun, Rong; Cheng, Yan-Na; Cao, Hua; Yang, Kang-Min; Dong, Yi-Ning; Wu, Yan; Guo, Xiu-Li

    2013-01-01

    PTEN (phosphatase and tensin homolog deleted on chromosome 10) is a tumor suppressor and has been suggested recently to be involved in the regulation of cardiovascular diseases. The molecular mechanisms of this regulation are however poorly understood. This study shows that down regulation of PTEN expression and activity by angiotensin II (Ang II) increased proliferation and migration of vascular smooth muscle cells (VSMCs). The presence of Ang II induced rapid PTEN phosphorylation and oxidation in accordance with increased AKT and FAK phosphorylation. The Ang II-mediated VSMC proliferation and migration was inhibited when cellular PTEN expression was increased by AT1 inhibitor losartan, PPARγ agonist rosiglitazone, NF-κB inhibitor BAY 11-7082. Over expression of PTEN in VSMCs by adenovirus transduction also resulted in inhibition of cell proliferation and migration in response to Ang II. These results suggest that PTEN down-regulation is involved in proliferation and migration of VSMCs induced by Ang II. This provides insight into the molecular regulation of PTEN in vascular smooth muscle cells and suggests that targeting the action of PTEN may represent an effective therapeutic approach for the treatment of cardiovascular diseases.

  9. Interaction of E-cadherin and PTEN regulates morphogenesis and growth arrest in human mammary epithelial cells

    SciTech Connect

    Fournier, Marcia V.; Fata, Jimmie E.; Martin, Katherine J.; Yaswen, Paul; Bissell, Mina J.

    2009-06-03

    PTEN is a dual function phosphatase with tumor suppressor function compromised in a wide spectrum of cancers. Because tissue polarity and architecture are crucial modulators of normal and malignant behavior, we postulated that PTEN may play a role in maintenance of tissue integrity. We used two non-malignant human mammary epithelial cell lines (HMECs) that form polarized, growth-arrested structures (acini) when cultured in 3-dimensional laminin-rich extracellular matrix gels (3D lrECM). As acini begin to form, PTEN accumulates in both the cytoplasm, and at cell-cell contacts where it colocalizes with E-cadherin/{beta}-catenin complex. Reduction of PTEN levels by shRNA in lrECM prevents formation of organized breast acini and disrupts growth arrest. Importantly, disruption of acinar polarity and cell-cell contact by E-cadherin function-blocking antibodies reduces endogenous PTEN protein levels and inhibits its accumulation at cell-cell contacts. Conversely, in SKBR3 breast cancer cells lacking endogenous E-cadherin expression, exogenous introduction of E-cadherin gene causes induction of PTEN expression and its accumulation at sites of cell interactions. These studies provide evidence that E-cadherin regulates both the PTEN protein levels and its recruitment to cell-cell junctions in 3D lrECM indicating a dynamic reciprocity between architectural integrity and the levels and localization of PTEN. This interaction thus appears to be a critical integrator of proliferative and morphogenetic signaling in breast epithelial cells.

  10. PTEN ameliorates autoimmune arthritis through down-regulating STAT3 activation with reciprocal balance of Th17 and Tregs

    PubMed Central

    Lee, Seung Hoon; Park, Jin-Sil; Byun, Jae-Kyung; Jhun, JooYeon; Jung, KyungAh; Seo, Hyeon-Beom; Moon, Young-Mee; Kim, Ho-Youn; Park, Sung-Hwan; Cho, Mi-La

    2016-01-01

    PTEN is a tyrosine phosphatase with significant function in inhibiting STAT3 activation. Recently, inactivation of STAT3 has been demonstrated as a therapeutic candidate for autoimmune arthritis. The expression of PTEN controlled by p53 regulates autoimmune arthritis through modulating the balance between Th17 and Treg. We hypothesized that PTEN regulated by p53 might reduce CIA severity and inflammatory response via inhibiting STAT3 activation. Our results revealed that PTEN could ameliorate experimental autoimmune arthritis by reducing STAT3 activity and Th17 differentiation. Systemic infusion of PTEN overexpression downregulated CIA severity. In addition, PTEN overexpression decreased the activation of T cells and modulated reciprocal differentiation of Th17 and Treg cells. We observed that PTEN expression downregulated by p53 deficiency induced the activation of STAT3. Loss of p53 exacerbated autoimmune arthritis and dysregulated the population of Th17 and Treg. These data suggest that induction of STAT3-modulatory activity of PTEN may be a therapeutic target for rheumatoid arthritis therapy. PMID:27708408

  11. PI3K isoform dependence of PTEN-deficient tumors can be altered by the genetic context.

    PubMed

    Schmit, Fabienne; Utermark, Tamara; Zhang, Sen; Wang, Qi; Von, Thanh; Roberts, Thomas M; Zhao, Jean J

    2014-04-29

    There has been increasing interest in the use of isoform-selective inhibitors of phosphatidylinositide-3-kinase (PI3K) in cancer therapy. Using conditional deletion of the p110 catalytic isoforms of PI3K to predict sensitivity of cancer types to such inhibitors, we and others have demonstrated that tumors deficient of the phosphatase and tensin homolog (PTEN) are often dependent on the p110β isoform of PI3K. Because human cancers usually arise due to multiple genetic events, determining whether other genetic alterations might alter the p110 isoform requirements of PTEN-null tumors becomes a critical question. To investigate further the roles of p110 isoforms in PTEN-deficient tumors, we used a mouse model of ovarian endometrioid adenocarcinoma driven by concomitant activation of the rat sarcoma protein Kras, which is known to activate p110α, and loss of PTEN. In this model, ablation of p110β had no effect on tumor growth, whereas p110α ablation blocked tumor formation. Because ablation of PTEN alone is often p110β dependent, we wondered if the same held true in the ovary. Because PTEN loss alone in the ovary did not result in tumor formation, we tested PI3K isoform dependence in ovarian surface epithelium (OSE) cells deficient in both PTEN and p53. These cells were indeed p110β dependent, whereas OSEs expressing activated Kras with or without PTEN loss were p110α dependent. Furthermore, isoform-selective inhibitors showed a similar pattern of the isoform dependence in established Kras(G12D)/PTEN-deficient tumors. Taken together, our data suggest that, whereas in some tissues PTEN-null tumors appear to inherently depend on p110β, the p110 isoform reliance of PTEN-deficient tumors may be altered by concurrent mutations that activate p110α.

  12. Prognostic impact and the relevance of PTEN copy number alterations in patients with advanced colorectal cancer (CRC) receiving bevacizumab.

    PubMed

    Price, Timothy J; Hardingham, Jennifer E; Lee, Chee K; Townsend, Amanda R; Wrin, Joseph W; Wilson, Kate; Weickhardt, Andrew; Simes, Robert J; Murone, Carmel; Tebbutt, Niall C

    2013-06-01

    Loss of phosphatase and tensin homologue (PTEN) expression may be prognostic in colorectal cancer (CRC) and may have a correlation with vascular endothelial growth factor (VEGF) expression via hypoxia-inducible factor 1 (HIF-1) alpha, and the PI3K/mTOR pathways. We therefore have explored the prognostic association of PTEN loss and the potential that PTEN loss may be predictive of outcome with bevacizumab. Patients enrolled in the AGITG MAX trial, a randomized Phase III trial of capecitabine (C) +/- bevacizumab (B) (+/- mitomycin C [M]) with available tissues were analyzed for PTEN expression (loss vs. no loss) as assessed using a Taqman® copy number assay (CNA). Of the original 471 patients enrolled, tissues from 302 (64.1%) patients were analyzed. PTEN loss was observed in 38.7% of patients. There was no relationship between PTEN loss and KRAS or BRAF mutation. PTEN status was not prognostic for progression-free survival (PFS) or overall survival (OS) in multivariate analyses adjusting for other baseline factors; loss versus no loss PFS hazard ratio (HR) 0.9 (0.7-1.16), OS HR 1.04 (0.79-1.38). PTEN was not prognostic when assessed by KRAS and BRAF status. By using the comparison of C versus CB+CBM, PTEN status was not significantly predictive of the effectiveness of B for PFS or OS. PTEN status was not prognostic for survival in advanced colorectal cancer, irrespective of KRAS or BRAF status. PTEN status did not significantly predict different benefit with bevacizumb therapy.

  13. Involvement of lysophosphatidic acid, sphingosine 1-phosphate and ceramide 1-phosphate in the metabolization of phosphatidic acid by lipid phosphate phosphatases in bovine rod outer segments.

    PubMed

    Pasquaré, Susana J; Salvador, Gabriela A; Giusto, Norma Maria

    2008-07-01

    The aim of the present research was to evaluate the generation of [2-3H]diacylglycerol ([2-3H]DAG) from [2-3H]-Phosphatidic acid ([2-3H]PA) by lipid phosphate phosphatases (LPPs) at different concentrations of lysophosphatidic acid (LPA), sphingosine 1-phosphate (S1P), and ceramide 1-phosphate (C1P) in purified ROS obtained from dark-adapted retinas (DROS) or light-adapted retinas (BLROS) as well as in ROS membrane preparations depleted of soluble and peripheral proteins. Western blot analysis revealed the presence of LPP3 exclusively in all membrane preparations. Immunoblots of entire ROS and depleted ROS did not show dark-light differences in LPP3 levels. LPPs activities were diminished by 53% in BLROS with respect to DROS. The major competitive effect on PA hydrolysis was exerted by LPA and S1P in DROS and by C1P in BLROS. LPPs activities in depleted ROS were similar to the activity observed in entire DROS and BLROS, respectively. LPA, S1P and C1P competed at different extent in depleted DROS and BLROS. Sphingosine and ceramide inhibited LPPs activities in entire and depleted DROS. Ceramide also inhibited LPPs activities in entire and in depleted BLROS. Our findings are indicative of a different degree of competition between PA and LPA, S1P and C1P by LPPs depending on the illumination state of the retina. PMID:18288612

  14. Pten regulates spindle pole movement through Dlg1-mediated recruitment of Eg5 to centrosomes

    PubMed Central

    van Ree, Janine H.; Nam, Hyun-Ja; Jeganathan, Karthik B.; Kanakkanthara, Arun; van Deursen, Jan M.

    2016-01-01

    Phosphatase and tensin homologue (Pten) suppresses neoplastic growth by negatively regulating PI(3)K signalling through its phosphatase activity1. To gain insight into the actions of non-catalytic Pten domains in normal physiological processes and tumorigenesis2,3, we engineered mice lacking the PDZ-binding domain (PDZ-BD). Here, we show that the PDZ-BD regulates centrosome movement and that its heterozygous or homozygous deletion promotes aneuploidy and tumour formation. We found that Pten is recruited to pre-mitotic centrosomes in a Plk1-dependent fashion to create a docking site for protein complexes containing the PDZ-domain-containing protein Dlg1 (also known as Sap97) and Eg5 (also known as Kif11), a kinesin essential for centrosome movement and bipolar spindle formation4. Docking of Dlg1–Eg5 complexes to Pten depended on Eg5 phosphorylation by the Nek9–Nek6 mitotic kinase cascade and Cdk1. PDZ-BD deletion or Dlg1 ablation impaired loading of Eg5 onto centrosomes and spindle pole motility, yielding asymmetrical spindles that are prone to chromosome missegregation. Collectively, these data demonstrate that Pten, through the Dlg1-binding ability of its PDZ-BD, accumulates phosphorylated Eg5 at duplicated centrosomes to establish symmetrical bipolar spindles that properly segregate chromosomes, and suggest that this function contributes to tumour suppression. PMID:27240320

  15. Glioma cell VEGFR-2 confers resistance to chemotherapeutic and antiangiogenic treatments in PTEN-deficient glioblastoma.

    PubMed

    Kessler, Tobias; Sahm, Felix; Blaes, Jonas; Osswald, Matthias; Rübmann, Petra; Milford, David; Urban, Severino; Jestaedt, Leonie; Heiland, Sabine; Bendszus, Martin; Hertenstein, Anne; Pfenning, Philipp-Niclas; Ruiz de Almodóvar, Carmen; Wick, Antje; Winkler, Frank; von Deimling, Andreas; Platten, Michael; Wick, Wolfgang; Weiler, Markus

    2015-10-13

    Loss of the tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a prerequisite for tumor cell-specific expression of vascular endothelial growth factor receptor (VEGFR)-2 in glioblastoma defining a subgroup prone to develop evasive resistance towards antiangiogenic treatments. Immunohistochemical analysis of human tumor tissues showed VEGFR-2 expression in glioma cells in 19% of specimens examined, mainly in the infiltration zone. Glioma cell VEGFR-2 positivity was restricted to PTEN-deficient tumor specimens. PTEN overexpression reduced VEGFR-2 expression in vitro, as well as knock-down of raptor or rictor. Genetic interference with VEGFR-2 revealed proproliferative, antiinvasive and chemoprotective functions for VEGFR-2 in glioma cells. VEGFR-2-dependent cellular effects were concomitant with activation of 'kappa-light-chain-enhancer' of activated B-cells, protein kinase B, and N-myc downstream regulated gene 1. Two-photon in vivo microscopy revealed that expression of VEGFR-2 in glioma cells hampers antiangiogenesis. Bevacizumab induces a proinvasive response in VEGFR-2-positive glioma cells. Patients with PTEN-negative glioblastomas had a shorter survival after initiation of bevacizumab therapy compared with PTEN-positive glioblastomas. Conclusively, expression of VEGFR-2 in glioma cells indicates an aggressive glioblastoma subgroup developing early resistance to temozolomide or bevacizumab. Loss of PTEN may serve as a biomarker identifying those tumors upfront by routine neuropathological methods.

  16. Myeloid PTEN deficiency protects livers from ischemia reperfusion injury by facilitating M2 macrophage differentiation.

    PubMed

    Yue, Shi; Rao, Jianhua; Zhu, Jianjun; Busuttil, Ronald W; Kupiec-Weglinski, Jerzy W; Lu, Ling; Wang, Xuehao; Zhai, Yuan

    2014-06-01

    Although the role of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in regulating cell proliferation is well established, its function in immune responses remains to be fully appreciated. In the current study, we analyzed myeloid-specific PTEN function in regulating tissue inflammatory immune response in a murine liver partial warm ischemia model. Myeloid-specific PTEN knockout (KO) resulted in liver protection from ischemia reperfusion injury (IRI) by deviating the local innate immune response against ischemia reperfusion toward the regulatory type: expression of proinflammatory genes was selectively decreased and anti-inflammatory IL-10 was simultaneously increased in ischemia reperfusion livers of PTEN KO mice compared with those of wild-type (WT) mice. PI3K inhibitor and IL-10-neutralizing Abs, but not exogenous LPS, recreated liver IRI in these KO mice. At the cellular level, Kupffer cells and peritoneal macrophages isolated from KO mice expressed higher levels of M2 markers and produced lower TNF-α and higher IL-10 in response to TLR ligands than did their WT counterparts. They had enhanced Stat3- and Stat6-signaling pathway activation, but diminished Stat1-signaling pathway activation, in response to TLR4 stimulation. Inactivation of Kupffer cells by gadolinium chloride enhanced proinflammatory immune activation and increased IRI in livers of myeloid PTEN KO mice. Thus, myeloid PTEN deficiency protects livers from IRI by facilitating M2 macrophage differentiation. PMID:24771857

  17. PTEN downregulates p75NTR expression by decreasing DNA-binding activity of Sp1

    SciTech Connect

    Rankin, Sherri L.; Guy, Clifford S.; Mearow, Karen M.

    2009-02-13

    p75NTR is expressed throughout the nervous system and its dysregulation is associated with pathological conditions. We have recently demonstrated a signalling cascade initiated by laminin (LN), which upregulates PTEN and downregulates p75NTR. Here we investigate the mechanism by which PTEN modulates p75NTR. Studies using PTEN mutants show that its protein phosphatase activity directly modulates p75NTR protein expression. Nuclear relocalization of PTEN subsequent to LN stimulation suggests transcriptional control of p75NTR expression, which was confirmed following EMSA and ChIP analysis of Sp1 transcription factor binding activity. LN and PTEN independently decrease the DNA-binding ability of PTEN to the p75NTR promoter. Sp1 regulation of p75NTR occurs via dephosphorylation of Sp1, thus reducing p75NTR transcription and protein expression. This mechanism represents a novel regulatory pathway which controls the expression level of a receptor with broad implications not only for the development of the nervous system but also for progression of pathological conditions.

  18. Is STAT3 and PTEN Expression Altered in Canine Prostate Cancer?

    PubMed

    Lin, H-Y; Palmieri, C

    2016-01-01

    Signal transducer and activator of transcription 3 (STAT3) and phosphatase and tensin homologue (PTEN) are, respectively, an oncogene and tumour suppressor gene whose dysregulated expression in human prostate cancer is associated with increased malignancy and poor prognosis. Both markers were evaluated in 12 samples of canine benign prostatic hyperplasia (BPH) and 17 canine prostatic carcinomas (PCs) by immunohistochemistry, to understand their possible role in canine prostate carcinogenesis. STAT3 was expressed in 25% and 82.35% of BPH and PC, respectively, with a significantly higher number of STAT3-positive cells in malignant compared with hyperplastic lesions. Three PCs had occasional nuclear expression of STAT3. PTEN was expressed in BPH and PC with a similar distribution and percentage of positive cells; however, four PCs were PTEN negative. Solid PCs contained more STAT3-positive and fewer PTEN-positive cells compared with the other subtypes. A reduced number of PTEN-positive cells was observed in PCs with a high Gleason score (GS10), while no association was demonstrated between STAT3 expression and Gleason score. The data suggest that overexpression of STAT3 and downregulation of PTEN may be an important step in canine prostate carcinogenesis and both markers may be related to the histological subtypes of PC and the degree of differentiation of neoplastic cells.

  19. Expression and significance of PTEN and VEGF in canine mammary gland tumours.

    PubMed

    Qiu, C W; Lin, D G; Wang, J Q; Li, C Y; Deng, G Z

    2008-08-01

    To investigate the relationship between the expression of the PTEN (phosphatase and tensin homolog deleted on chromosometen) and VEGF (vascular endothelial growth factor) and the clinicopathological features in canine mammary gland tumours, the expression levels of PTEN and VEGF protein were assessed in 50 cases of canine mammary gland tumours tissues and 4 cases of normal mammary gland tissues with using immunohistochemical method. The over-expression rate of PTEN protein was 100% in normal and well-differentiated mammary gland tissues and 67% in breast cancer cases respectively with a significant difference between the two groups (P<0.01). Expression of PTEN was not related to age and tumour size, but closely correlated to lymph node metastasis (P<0.01). The over-expression rate of VEGF protein was 33.3% in normal mammary gland tissues, and 78% in canine mammary gland tumours with a significant difference between the two groups (P<0.01). Expression of VEGF was not related to age or tumour size, but closely correlated with lymph node metastasis and clinical stage (P<0.05). Therefore the combination detection of PTEN and VEGF could serve as an important index to estimate the biological behavior and prognosis of canine mammary gland tumours. Reduced expression of PTEN might be involved in carcinogenesis and progression of canine breast cancer by up-regulating the VEGF expression to enhance angiogenesis.

  20. Relationship between PTEN and VEGF expression and clinicopathological characteristics in HCC.

    PubMed

    Mi, Denghai; Yi, Jilin; Liu, Enyu; Li, Xingrui

    2006-01-01

    To investigate the expressions and significance of the tumor suppressor gene phosphatase and tensin homolog deleted on chromosome ten protein (PTEN) and vascular endothelial growth factor (VEGF) in hepatocellular carcinoma (HCC), and to analyze the relationship between their expressions and the tumor's invasion and their peri-carcinomatous tissues, the correlation of their expressions with the tumor's clinicopathological characteristics and invasion potential were studied. Our study showed that the expression level of PTEN in HCC was remarkably lower than that in peri-carcinomatous liver tissues, while the expressions of both VEGF and MVD were higher than that in peri-carcinomatous liver tissues. Correlation analysis revealed that the expression of PTEN was negatively related to the progression of the pathological differentiation and invasion of tumor, whereas the expressions of VEGF and MVD were positively related. Moreover, there was a negative relationship between the expression of PTEN and the expressions of VEGF and MVD, and a positive one between VEGF and MVD. The expressions of PTEN and VEGF may reveal the degree of differentiation and the invasive potential of HCC tissues. The mechanism by which the lack of PTEN expression probably induces abnormal hyperexpression of VEGF may play an important role in the invasion and metastasis of HCC.

  1. Cross talk between miR-214 and PTEN attenuates glomerular hypertrophy under diabetic conditions

    PubMed Central

    Wang, Xiaoxia; Shen, E.; Wang, Yanzhe; Li, Junhui; Cheng, Dongsheng; Chen, Yuqiang; Gui, Dingkun; Wang, Niansong

    2016-01-01

    Glomerular mesangial cells (MCs) hypertrophy is one of the earliest pathological abnormalities in diabetic nephropathy (DN), which correlates with eventual glomerulosclerosis. This study aimed to investigate the therapeutic role of miRNA in diabetic glomerular MCs hypertrophy and synthesis of extracellular matrix (ECM). Microarray analysis revealed a significant up-regulation of miR-214 in the renal cortex of diabetic db/db mice, which was confirmed by real-time PCR of isolated glomeruli and primary cultured human MCs. In vitro studies showed that inhibition of miR-214 significantly reduced expression of α-SMA, SM22 and collagen IV, and partially restored phosphatase and tensin homolog (PTEN) protein level in high glucose-stimulated human MCs. Furthermore, we identified PTEN as the target of miR-214 by a luciferase assay in HEK293 cells. Moreover, overexpression of PTEN ameliorated miR-214-mediated diabetic MC hypertrophy while knockdown of PTEN mimicked the MC hypertrophy. In vivo study further confirmed that inhibition of miR-214 significantly decreased the expression of SM22, α-SMA and collagen IV, partially restored PTEN level, and attenuated albuminuria and mesangial expansion in db/db mice. In conclusion, cross talk between miR-214 and PTEN attenuated glomerular hypertrophy under diabetic conditions in vivo and in vitro. Therefore, miR-214 may represent a novel therapeutic target for DN. PMID:27549568

  2. Plk1 Phosphorylation of PTEN Causes a Tumor-Promoting Metabolic State

    PubMed Central

    Li, Zhiguo; Li, Jie; Bi, Pengpeng; Lu, Ying; Burcham, Grant; Elzey, Bennett D.; Ratliff, Timothy; Konieczny, Stephen F.; Ahmad, Nihal; Kuang, Shihuan

    2014-01-01

    One outcome of activation of the phosphatidylinositol 3-kinase (PI3K) pathway is increased aerobic glycolysis, but the upstream signaling events that regulate the PI3K pathway, and thus the Warburg effect, are elusive. Increasing evidence suggests that Plk1, a cell cycle regulator, is also involved in cellular events in addition to mitosis. To test whether Plk1 contributes to activation of the PI3K pathway, and thus aerobic glycolysis, we examined potential targets of Plk1 and identified PTEN as a Plk1 substrate. We hypothesize that Plk1 phosphorylation of PTEN leads to its inactivation, activation of the PI3K pathway, and the Warburg effect. Our data show that overexpression of Plk1 leads to activation of the PI3K pathway and enhanced aerobic glycolysis. In contrast, inhibition of Plk1 causes markedly reduced glucose metabolism in mice. Mechanistically, we show that Plk1 phosphorylation of PTEN and Nedd4-1, an E3 ubiquitin ligase of PTEN, results in PTEN inactivation. Finally, we show that Plk1 phosphorylation of PTEN promotes tumorigenesis in both its phosphatase-dependent and -independent pathways, revealing potentially new drug targets to arrest tumor cell growth. PMID:25047839

  3. Cross talk between miR-214 and PTEN attenuates glomerular hypertrophy under diabetic conditions.

    PubMed

    Wang, Xiaoxia; Shen, E; Wang, Yanzhe; Li, Junhui; Cheng, Dongsheng; Chen, Yuqiang; Gui, Dingkun; Wang, Niansong

    2016-01-01

    Glomerular mesangial cells (MCs) hypertrophy is one of the earliest pathological abnormalities in diabetic nephropathy (DN), which correlates with eventual glomerulosclerosis. This study aimed to investigate the therapeutic role of miRNA in diabetic glomerular MCs hypertrophy and synthesis of extracellular matrix (ECM). Microarray analysis revealed a significant up-regulation of miR-214 in the renal cortex of diabetic db/db mice, which was confirmed by real-time PCR of isolated glomeruli and primary cultured human MCs. In vitro studies showed that inhibition of miR-214 significantly reduced expression of α-SMA, SM22 and collagen IV, and partially restored phosphatase and tensin homolog (PTEN) protein level in high glucose-stimulated human MCs. Furthermore, we identified PTEN as the target of miR-214 by a luciferase assay in HEK293 cells. Moreover, overexpression of PTEN ameliorated miR-214-mediated diabetic MC hypertrophy while knockdown of PTEN mimicked the MC hypertrophy. In vivo study further confirmed that inhibition of miR-214 significantly decreased the expression of SM22, α-SMA and collagen IV, partially restored PTEN level, and attenuated albuminuria and mesangial expansion in db/db mice. In conclusion, cross talk between miR-214 and PTEN attenuated glomerular hypertrophy under diabetic conditions in vivo and in vitro. Therefore, miR-214 may represent a novel therapeutic target for DN. PMID:27549568

  4. Metformin inhibits inflammatory response via AMPK-PTEN pathway in vascular smooth muscle cells

    SciTech Connect

    Kim, Sun Ae; Choi, Hyoung Chul

    2012-09-07

    Highlights: Black-Right-Pointing-Pointer PTEN was induced by metformin and inhibited by compound C and AMPK siRNA. Black-Right-Pointing-Pointer Metformin suppressed TNF-{alpha}-induced COX-2 and iNOS mRNA expression. Black-Right-Pointing-Pointer Compound C and bpv (pic) increased iNOS and COX-2 protein expression. Black-Right-Pointing-Pointer NF-{kappa}B activation was restored by inhibiting AMPK and PTEN. Black-Right-Pointing-Pointer AMPK and PTEN regulated TNF-{alpha}-induced ROS production in VSMCs. -- Abstract: Atherosclerosis is a chronic inflammation of the coronary arteries. Vascular smooth muscle cells (VSMCs) stimulated by cytokines and chemokines accelerate the inflammatory response and migrate to the injured endothelium during the progression of atherosclerosis. Activation of AMP activated protein kinase (AMPK), a key sensor maintaining metabolic homeostasis, suppresses the inflammatory response. However, how AMPK regulates the inflammatory response is poorly understood. To identify the mechanism of this response, we focused on phosphatase and tensin homolog (PTEN), which is a negative regulator of inflammation. We investigated that activation of AMPK-induced PTEN expression and suppression of the inflammatory response through the AMPK-PTEN pathway in VSMCs. We treated with the well-known AMPK activator metformin to induce PTEN expression. PTEN was induced by metformin (2 mM) and inhibited by compound C (10 {mu}M) and AMPK siRNA. Tumor necrosis factor-alpha (TNF-{alpha}) was used to induce inflammation. The inflammatory response was confirmed by cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS) expression, and activation of nuclear factor (NF)-{kappa}B. Metformin suppressed COX-2 and iNOS mRNA and protein expression dose dependently. Treatment with compound C and bpv (pic) in the presence of metformin, iNOS and COX-2 protein expression increased. NF-{kappa}B activation decreased in response to metformin and was restored by inhibiting AMPK

  5. Ezrin-radixin-moesin-binding phosphoprotein-50 regulates EGF-induced AKT activation through interaction with EGFR and PTEN.

    PubMed

    Zheng, Junfang; Dai, Yuanping; Yang, Zhiyu; Yang, Longyan; Peng, Zhiqiang; Meng, Ran; Xiong, Ying; He, Junqi

    2016-01-01

    Dysregulated epidermal growth factor receptor (EGFR) signaling, especially EGFR/AKT signaling, plays important roles in tumorigenesis and progression, the study on intracellular regulation of this signaling pathway has great clinical significance. Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is an important antagonist of AKT activity. Its regulation of AKT activity can be enhanced by ezrin-radixin-moesin-binding phosphoprotein-50 (EBP50)-mediated PTEN/EBP50/platelet-derived growth factor receptor (PDGFR) complex. EBP50 was reported to bind to EGFR, and that it may also mediate the formation of PTEN/EGFR complex to regulate EGFR/AKT signaling. In this study, experiments were performed to verify the hypothesis. Results showed that PTEN co-immunoprecipitated with EGFR, demonstrating PTEN/EGFR complex can form in tissue. Further studies showed that EBP50 knockdown decreased the amount of PTEN/EGFR complex by GST pull-down assay, and EBP50 overexpression increased the amount of PTEN/EGFR complex in a dose-dependent manner. While PTEN mutant (V403A), which can not bind with EBP50, only slightly mediated the formation of PTEN/EGFR complex, confirming that EBP50 specifically mediated the formation of the PTEN/EGFR complex. Both PTEN (V403A) and EGFR (L1043/1063F) mutants can not bind with EBP50. The expression of PTEN (V403A) or EGFR (L1043/1063F) mutant in cells resulted in higher AKT activation level than their respective wild-types by EGF stimulation, indicating that EBP50-mediated PTEN/EGFR complex can effectively inhibit EGF-induced AKT activation. EGF stimulation of siEBP50 cells induced higher AKT activation level compared with control cells, further confirming EBP50-mediated PTEN/EGFR complex can more effectively inhibit EGF-induced AKT activation. These results demonstrated the PTEN/EGFR complex formed under the mediation of EBP50, revealing a novel mechanism for negative regulation of EGF-induced AKT pathway, which may be an important molecular

  6. Global DNA methylation and PTEN hypermethylation alterations in lung tissues from human silicosis

    PubMed Central

    Zhang, Xianan; Jia, Xiaowei; Mei, Liangying; Zheng, Min; Yu, Chen

    2016-01-01

    Background Silicosis is a respiratory disease caused by long-term silica dust exposure. Our previous study has demonstrated that silica mediates the activation of phosphatidylinositol 3-kinase (PI3K)/phosphatase and tensin homolog deleted on chromosome 10 (PTEN)/serine or threonine kinase (AKT)/mitogen-activated protein kinases (MAPK)/AP-1 pathway in human embryo lung fibroblasts (HELFs). The purpose of this study is to identify genome-wide aberrant DNA methylation profiling in lung tissues from silicosis patients. Methods We performed Illumina Human Methylation 450K Beadchip arrays to investigate the methylation alteration in formalin-fixed, paraffin-embedded (FFPE) lung specimens, immunohistochemistry to detect the level of c-Jun and PTEN proteins; methylation specific PCR (MS-PCR) to identify PTEN and c-Jun promoter methylation in HELFs. Results We found 86,770 CpG sites and 79,660 CpG sites significantly differed in methylation status in early-stage and advanced-stage compared with GEO normal lung methylation data. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed the methylated status of MAPK signaling pathway was considered changed. The number of PTEN and c-Jun CpG promoter methylated-sites were increased in advanced-stage. Early-stage showed the positive expression of c-Jun and PTEN protein and negative or mild expression in advanced-stage. PTEN promoter was no differentially methylated and c-Jun promoter differed at 12 and 24 h in HELFs. Conclusions Abnormal DNA methylation on genome-scale was implicated in silicosis, and PTEN promoter hypermethylation might be associated with decrease of PTEN protein. PMID:27621875

  7. Global DNA methylation and PTEN hypermethylation alterations in lung tissues from human silicosis

    PubMed Central

    Zhang, Xianan; Jia, Xiaowei; Mei, Liangying; Zheng, Min; Yu, Chen

    2016-01-01

    Background Silicosis is a respiratory disease caused by long-term silica dust exposure. Our previous study has demonstrated that silica mediates the activation of phosphatidylinositol 3-kinase (PI3K)/phosphatase and tensin homolog deleted on chromosome 10 (PTEN)/serine or threonine kinase (AKT)/mitogen-activated protein kinases (MAPK)/AP-1 pathway in human embryo lung fibroblasts (HELFs). The purpose of this study is to identify genome-wide aberrant DNA methylation profiling in lung tissues from silicosis patients. Methods We performed Illumina Human Methylation 450K Beadchip arrays to investigate the methylation alteration in formalin-fixed, paraffin-embedded (FFPE) lung specimens, immunohistochemistry to detect the level of c-Jun and PTEN proteins; methylation specific PCR (MS-PCR) to identify PTEN and c-Jun promoter methylation in HELFs. Results We found 86,770 CpG sites and 79,660 CpG sites significantly differed in methylation status in early-stage and advanced-stage compared with GEO normal lung methylation data. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed the methylated status of MAPK signaling pathway was considered changed. The number of PTEN and c-Jun CpG promoter methylated-sites were increased in advanced-stage. Early-stage showed the positive expression of c-Jun and PTEN protein and negative or mild expression in advanced-stage. PTEN promoter was no differentially methylated and c-Jun promoter differed at 12 and 24 h in HELFs. Conclusions Abnormal DNA methylation on genome-scale was implicated in silicosis, and PTEN promoter hypermethylation might be associated with decrease of PTEN protein.

  8. PTEN inhibition to facilitate intrinsic regenerative outgrowth of adult peripheral axons.

    PubMed

    Christie, Kimberly J; Webber, Christine A; Martinez, Jose A; Singh, Bhagat; Zochodne, Douglas W

    2010-07-01

    In vivo regeneration of peripheral neurons is constrained and rarely complete, and unfortunately patients with major nerve trunk transections experience only limited recovery. Intracellular inhibition of neuronal growth signals may be among these constraints. In this work, we investigated the role of PTEN (phosphatase and tensin homolog deleted on chromosome 10) during regeneration of peripheral neurons in adult Sprague Dawley rats. PTEN inhibits phosphoinositide 3-kinase (PI3-K)/Akt signaling, a common and central outgrowth and survival pathway downstream of neuronal growth factors. While PI3-K and Akt outgrowth signals were expressed and activated within adult peripheral neurons during regeneration, PTEN was similarly expressed and poised to inhibit their support. PTEN was expressed in neuron perikaryal cytoplasm, nuclei, regenerating axons, and Schwann cells. Adult sensory neurons in vitro responded to both graded pharmacological inhibition of PTEN and its mRNA knockdown using siRNA. Both approaches were associated with robust rises in the plasticity of neurite outgrowth that were independent of the mTOR (mammalian target of rapamycin) pathway. Importantly, this accelerated outgrowth was in addition to the increased outgrowth generated in neurons that had undergone a preconditioning lesion. Moreover, following severe nerve transection injuries, local pharmacological inhibition of PTEN or siRNA knockdown of PTEN at the injury site accelerated axon outgrowth in vivo. The findings indicated a remarkable impact on peripheral neuron plasticity through PTEN inhibition, even within a complex regenerative milieu. Overall, these findings identify a novel route to propagate intrinsic regeneration pathways within axons to benefit nerve repair.

  9. Convergent loss of PTEN leads to clinical resistance to a PI(3)Kα inhibitor.

    PubMed

    Juric, Dejan; Castel, Pau; Griffith, Malachi; Griffith, Obi L; Won, Helen H; Ellis, Haley; Ebbesen, Saya H; Ainscough, Benjamin J; Ramu, Avinash; Iyer, Gopa; Shah, Ronak H; Huynh, Tiffany; Mino-Kenudson, Mari; Sgroi, Dennis; Isakoff, Steven; Thabet, Ashraf; Elamine, Leila; Solit, David B; Lowe, Scott W; Quadt, Cornelia; Peters, Malte; Derti, Adnan; Schegel, Robert; Huang, Alan; Mardis, Elaine R; Berger, Michael F; Baselga, José; Scaltriti, Maurizio

    2015-02-12

    Broad and deep tumour genome sequencing has shed new light on tumour heterogeneity and provided important insights into the evolution of metastases arising from different clones. There is an additional layer of complexity, in that tumour evolution may be influenced by selective pressure provided by therapy, in a similar fashion to that occurring in infectious diseases. Here we studied tumour genomic evolution in a patient (index patient) with metastatic breast cancer bearing an activating PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha, PI(3)Kα) mutation. The patient was treated with the PI(3)Kα inhibitor BYL719, which achieved a lasting clinical response, but the patient eventually became resistant to this drug (emergence of lung metastases) and died shortly thereafter. A rapid autopsy was performed and material from a total of 14 metastatic sites was collected and sequenced. All metastatic lesions, when compared to the pre-treatment tumour, had a copy loss of PTEN (phosphatase and tensin homolog) and those lesions that became refractory to BYL719 had additional and different PTEN genetic alterations, resulting in the loss of PTEN expression. To put these results in context, we examined six other patients also treated with BYL719. Acquired bi-allelic loss of PTEN was found in one of these patients, whereas in two others PIK3CA mutations present in the primary tumour were no longer detected at the time of progression. To characterize our findings functionally, we examined the effects of PTEN knockdown in several preclinical models (both in cell lines intrinsically sensitive to BYL719 and in PTEN-null xenografts derived from our index patient), which we found resulted in resistance to BYL719, whereas simultaneous PI(3)K p110β blockade reverted this resistance phenotype. We conclude that parallel genetic evolution of separate metastatic sites with different PTEN genomic alterations leads to a convergent PTEN-null phenotype resistant

  10. Suppression of Akt1 phosphorylation by adenoviral transfer of the PTEN gene inhibits hypoxia-induced proliferation of rat pulmonary arterial smooth muscle cells

    SciTech Connect

    Luo, Chunxia; Yi, Bin; Bai, Li; Xia, Yongzhi; Wang, Guansong; Qian, Guisheng; Feng, Hua

    2010-07-02

    Recent findings identify the role of proliferation of pulmonary artery smooth muscle cells (PASMCs) in pulmonary vascular remodeling. Phosphoinositide 3 kinase (PI3K) and serine/threonine kinase (Akt) proteins are expressed in vascular smooth muscle cells. In addition, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has been identified as a negative regulator of cytokine signaling that inhibits the PI3K-Akt pathway. However, little is known about the role of PTEN/Akt signaling in hypoxia-associated vascular remodeling. In this study, we found that hypoxia-induced the expression of Akt1 mRNA and phosphorylated protein by at least twofold in rat PASMCs. Phospho-PTEN significantly decreased in the nuclei of PASMCs after hypoxic stimulation. After forcing over-expression of PTEN by adenovirus-mediated PTEN (Ad-PTEN) transfection, the expression of phospho-Akt1 was significantly suppressed in PASMCs at all time-points measured. Additionally, we showed here that hypoxia increased proliferation of PASMCs by nearly twofold and over-expression of PTEN significantly inhibited hypoxia-induced PASMCs proliferation. These findings suggest that phospho-PTEN loss in the nuclei of PASMCs under hypoxic conditions may be the major cause of aberrant activation of Akt1 and may, therefore, play an important role in hypoxia-associated pulmonary arterial remodeling. Finally, the fact that transfection with Ad-PTEN inhibits the phosphorylation of Akt1 in PASMCs suggests a potential therapeutic effect on hypoxia-associated pulmonary arterial remodeling.

  11. PTEN enhances G2/M arrest in etoposide-treated MCF‑7 cells through activation of the ATM pathway.

    PubMed

    Zhang, Ruopeng; Zhu, Li; Zhang, Lirong; Xu, Anli; Li, Zhengwei; Xu, Yijuan; He, Pei; Wu, Maoqing; Wei, Fengxiang; Wang, Chenhong

    2016-05-01

    As an effective tumor suppressor, phosphatase and tensin homolog (PTEN) has attracted the increased attention of scientists. Recent studies have shown that PTEN plays unique roles in the DNA damage response (DDR) and can interact with the Chk1 pathway. However, little is known about how PTEN contributes to DDR through the ATM-Chk2 pathway. It is well-known that etoposide induces G2/M arrest in a variety of cell lines, including MCF-7 cells. The DNA damage-induced G2/M arrest results from the activation of protein kinase ataxia telangiectasia mutated (ATM), followed by the activation of Chk2 that subsequently inactivates CDC25C, resulting in G2/M arrest. In the present study, we assessed the contribution of PTEN to the etoposide-induced G2/M cell cycle arrest. PTEN was knocked down in MCF-7 cells by specific shRNA, and the effects of PTEN on the ATM-Chk2 pathway were investigated through various approaches. The results showed that knockdown of PTEN strongly antagonized ATM activation in response to etoposide treatment, and thereby reduced the phosphorylation level of ATM substrates, including H2AX, P53 and Chk2. Furthermore, depletion of PTEN reduced the etoposide-induced phosphorylation of CDC25C and strikingly compromised etoposide-induced G2/M arrest in the MCF-7 cells. Altogether, we demonstrated that PTEN plays a unique role in etoposide-induced G2/M arrest by facilitating the activation of the ATM pathway, and PTEN was required for the proper activation of checkpoints in response to DNA damage in MCF-7 cells.

  12. PTEN and p16 genes as epigenetic biomarkers in oral squamous cell carcinoma (OSCC): a study on south Indian population.

    PubMed

    Sushma, P S; Jamil, Kaiser; Kumar, P Uday; Satyanarayana, U; Ramakrishna, M; Triveni, B

    2016-06-01

    Phosphatase and tensin homolog (PTEN) and p16INK4a (p16) genes are tumor suppressor genes, associated with epigenetic alterations. PTEN and p16 promoter hypermethylation is a major epigenetic silencing mechanism leading to cancer. The cooperation between PTEN and p16 in pathogenesis of cancers suggest that their combination might be considered as potential molecular marker for specific subgroups of patients. Hence, the present study aimed to investigate whether PTEN and p16 promoter methylations were involved in oral squamous cell carcinoma (OSCC) in south Indian subjects. DNA methylation quantitative analyses of the two candidate tumor suppressor genes PTEN and p16 were performed by methylation-specific polymerase chain reaction (MSP). Fifty OSCC biopsy samples and their corresponding non-malignant portions as controls were studied comparatively. The methylation status was correlated with the clinical manifestations. Twelve out of 50 patients (24 %) were found to be methylated for PTEN gene, whereas methylation of the p16 gene occurred in 19 out of 50 cases (38 %). A statistically significant result was obtained (P = <0.0001 and 0.017) for both PTEN and p16 genes. PTEN and p16 promoter methylation may be the main mechanism leading to the low expression of PTEN and p16 genes indicating the progress of tumor development. Our data suggest that a low PTEN and p16 expression due to methylation may contribute to the cancer progression and could be useful for prognosis of OSCC. Therefore, analysis of promoter methylation in such genes may provide a biomarker valuable for early detection of oral cancer.

  13. Coordinate activation of Shh and PI3K signaling in PTEN-deficient glioblastoma: new therapeutic opportunities.

    PubMed

    Filbin, Mariella Gruber; Dabral, Sukriti K; Pazyra-Murphy, Maria F; Ramkissoon, Shakti; Kung, Andrew L; Pak, Ekaterina; Chung, Jarom; Theisen, Matthew A; Sun, Yanping; Franchetti, Yoko; Sun, Yu; Shulman, David S; Redjal, Navid; Tabak, Barbara; Beroukhim, Rameen; Wang, Qi; Zhao, Jean; Dorsch, Marion; Buonamici, Silvia; Ligon, Keith L; Kelleher, Joseph F; Segal, Rosalind A

    2013-11-01

    In glioblastoma, phosphatidylinositol 3-kinase (PI3K) signaling is frequently activated by loss of the tumor suppressor phosphatase and tensin homolog (PTEN). However, it is not known whether inhibiting PI3K represents a selective and effective approach for treatment. We interrogated large databases and found that sonic hedgehog (SHH) signaling is activated in PTEN-deficient glioblastoma. We demonstrate that the SHH and PI3K pathways synergize to promote tumor growth and viability in human PTEN-deficient glioblastomas. A combination of PI3K and SHH signaling inhibitors not only suppressed the activation of both pathways but also abrogated S6 kinase (S6K) signaling. Accordingly, targeting both pathways simultaneously resulted in mitotic catastrophe and tumor apoptosis and markedly reduced the growth of PTEN-deficient glioblastomas in vitro and in vivo. The drugs tested here appear to be safe in humans; therefore, this combination may provide a new targeted treatment for glioblastoma. PMID:24076665

  14. The association between phosphatase and tensin homolog hypermethylation and patients with breast cancer, a meta-analysis and literature review.

    PubMed

    Lu, Yi-Min; Cheng, Feng; Teng, Li-Song

    2016-01-01

    The Phosphatase and tensin homolog (PTEN) protein is a negative regulator of the Akt pathway, leading to suppression of apoptois and increased cell survival. Its role as a tumor-suppressor gene has been adequately substantiated, and PTEN hypermethylation has been demonstrated in familial and sporadic cancers. However, the association and clinical significance between PTEN hypermethylation and breast cancer remains unclear. In this study, we systematically reviewed studies of PTEN hypermethylation and breast cancer and quantify the association between PTEN hypermethylation and breast cancer using meta-analysis methods. The pooled OR, 22.30, 95% confidential intervals, CI = 1.98-251.51, P = 0.01, which demonstrates that loss of PTEN expression by hypermethylation plays a critical role in the early tumorigenesis of ductal carcinoma in situ (DCIS). In addition, PTEN hypermethylation also is detected in invasive ductal carcinomas (IDCs) and is significantly higher than in normal controls, OR = 23.32, 95% CI = 10.43-52.13, P < 0.00001. Further analysis did not show significant correlation between PTEN hypermethylation and the progression of breast cancer, estrogen receptor (ER), progesterone receptor (PgR), as well as HER2 status. These results indicate the PTEN hypermethylation is significantly associated with both DCIS and IDCs. The detection of PTEN hypermethylation could be an early tumorigenesis marker for breast cancer patients. PMID:27620353

  15. The association between phosphatase and tensin homolog hypermethylation and patients with breast cancer, a meta-analysis and literature review

    PubMed Central

    Lu, Yi-Min; Cheng, Feng; Teng, Li-Song

    2016-01-01

    The Phosphatase and tensin homolog (PTEN) protein is a negative regulator of the Akt pathway, leading to suppression of apoptois and increased cell survival. Its role as a tumor-suppressor gene has been adequately substantiated, and PTEN hypermethylation has been demonstrated in familial and sporadic cancers. However, the association and clinical significance between PTEN hypermethylation and breast cancer remains unclear. In this study, we systematically reviewed studies of PTEN hypermethylation and breast cancer and quantify the association between PTEN hypermethylation and breast cancer using meta-analysis methods. The pooled OR, 22.30, 95% confidential intervals, CI = 1.98–251.51, P = 0.01, which demonstrates that loss of PTEN expression by hypermethylation plays a critical role in the early tumorigenesis of ductal carcinoma in situ (DCIS). In addition, PTEN hypermethylation also is detected in invasive ductal carcinomas (IDCs) and is significantly higher than in normal controls, OR = 23.32, 95% CI = 10.43–52.13, P < 0.00001. Further analysis did not show significant correlation between PTEN hypermethylation and the progression of breast cancer, estrogen receptor (ER), progesterone receptor (PgR), as well as HER2 status. These results indicate the PTEN hypermethylation is significantly associated with both DCIS and IDCs. The detection of PTEN hypermethylation could be an early tumorigenesis marker for breast cancer patients. PMID:27620353

  16. Overexpression of LRIG1 regulates PTEN via MAPK/MEK signaling pathway in esophageal squamous cell carcinoma

    PubMed Central

    Jiang, Xiaofang; Li, Huiwu

    2016-01-01

    The present study aimed to evaluate the role of leucine-rich repeats and immunoglobulin-like domain protein 1 (LRIG1) in the regulation of phosphatase and tensin homolog (PTEN) expression in esophageal carcinogenesis. LRIG1 was overexpressed in esophageal squamous cell carcinoma (ESCC) cell lines, and the effect of LRIG1 overexpression on the mRNA and protein expression levels of PTEN was evaluated by reverse transcription-quantitative polymerase chain reaction and western blotting. Furthermore, the effects of LRIG1 overexpression on the cell cycle distribution and apoptosis of ESCC cells were examined by flow cytometry. Various cell signaling pathway inhibitors were used to assess the effects of LRIG1 on downstream signaling in ESCC cell lines. In addition, the association between LRIG1 and PTEN expression was examined in 48 samples from patients with ESCC. LRIG1 overexpression was demonstrated to downregulate PTEN expression in ESCC cell lines, and promote their proliferation and inhibit apoptosis. In addition, LRIG1-mediated suppression of PTEN expression was inhibited by the U0126 inhibitor, which suggests that LRIG1 may inhibit the activation of PTEN signaling molecules by triggering the mitogen-activated protein kinase (MAPK)/MAPK kinase 1 (MEK) signaling pathway. In conclusion, the present study demonstrated that overexpression of LRIG1 significantly and adversely affected the survival of ESCC cells, and that the MAPK/MEK signaling pathway may be responsible for the repression of PTEN expression and function. PMID:27698691

  17. PTEN regulates angiogenesis through PI3K/Akt/VEGF signaling pathway in human pancreatic cancer cells.

    PubMed

    Ma, Jiachi; Sawai, Hirozumi; Ochi, Nobuo; Matsuo, Yoichi; Xu, Donghui; Yasuda, Akira; Takahashi, Hiroki; Wakasugi, Takehiro; Takeyama, Hiromitsu

    2009-11-01

    Phosphoinositide 3-kinase (PI3K) pathway exerts its effects through Akt, its downstream target molecule, and thereby regulates various cell functions including cell proliferation, cell transformation, apoptosis, tumor growth, and angiogenesis. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has been implicated in regulating cell survival signaling through the PI3K/Akt pathway. However, the mechanism by PI3K/PTEN signaling regulates angiogenesis and tumor growth in vivo remains to be elucidated. Vascular endothelial growth factor (VEGF) plays a pivotal role in tumor angiogenesis. The effect of PTEN on VEGF-mediated signal in pancreatic cancer is unknown. This study aimed to determine the effect of PTEN on both the expression of VEGF and angiogenesis. Toward that end, we used the siRNA knockdown method to specifically define the role of PTEN in the expression of VEGF and angiogenesis. We found that siRNA-mediated inhibition of PTEN gene expression in pancreatic cancer cells increase their VEGF secretion, up-modulated the proliferation, and migration of co-cultured vascular endothelial cell and enhanced tubule formation by HUVEC. In addition, PTEN modulated VEGF-mediated signaling and affected tumor angiogenesis through PI3K/Akt/VEGF/eNOS pathway.

  18. Targeted deletion of tumor suppressor PTEN augments neutrophil function and enhances host defense in neutropenia-associated pneumonia

    PubMed Central

    Li, Yitang; Jia, Yonghui; Pichavant, Muriel; Loison, Fabien; Sarraj, Bara; Kasorn, Anongnard; You, Jian; Robson, Bryanne E.; Umetsu, Dale T.; Mizgerd, Joseph P.; Ye, Keqiang

    2009-01-01

    Neutropenia and related infections are the most important dose-limiting toxicities in anticancer chemotherapy and radiotherapy. In this study, we explored a new strategy for augmenting host defense in neutropenia-related pneumonia. Phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3) signaling in neutrophils was elevated by depleting PTEN, a phosphatidylinositol 3′-phosphatase that hydrolyzes PtdIns(3,4,5)P3. In myeloid-specific PTEN knockout mice, significantly more neutrophils were recruited to the inflamed lungs during neutropenia-associated pneumonia. Using an adoptive transfer technique, we demonstrated that this enhancement could be caused directly by PTEN depletion in neutrophils. In addition, disruption of PTEN increased the recruitment of macrophages and elevated proinflammatory cytokines/chemokine levels in the inflamed lungs, which could also be responsible for the enhanced neutrophil recruitment. Depleting PTEN also significantly delayed apoptosis and enhanced the bacteria-killing capability of the recruited neutrophils. Finally, we provide direct evidence that enhancement of neutrophil function by elevating PtdIns(3,4,5)P3 signaling can alleviate pneumonia-associated lung damage and decrease pneumonia-elicited mortality. Collectively, these results not only provide insight into the mechanism of action of PTEN and PtdIns(3,4,5)P3 signaling pathway in modulating neutrophil function during lung infection and inflammation, but they also establish PTEN and related pathways as potential therapeutic targets for treating neutropenia-associated pneumonia. PMID:19286998

  19. Overexpression of LRIG1 regulates PTEN via MAPK/MEK signaling pathway in esophageal squamous cell carcinoma

    PubMed Central

    Jiang, Xiaofang; Li, Huiwu

    2016-01-01

    The present study aimed to evaluate the role of leucine-rich repeats and immunoglobulin-like domain protein 1 (LRIG1) in the regulation of phosphatase and tensin homolog (PTEN) expression in esophageal carcinogenesis. LRIG1 was overexpressed in esophageal squamous cell carcinoma (ESCC) cell lines, and the effect of LRIG1 overexpression on the mRNA and protein expression levels of PTEN was evaluated by reverse transcription-quantitative polymerase chain reaction and western blotting. Furthermore, the effects of LRIG1 overexpression on the cell cycle distribution and apoptosis of ESCC cells were examined by flow cytometry. Various cell signaling pathway inhibitors were used to assess the effects of LRIG1 on downstream signaling in ESCC cell lines. In addition, the association between LRIG1 and PTEN expression was examined in 48 samples from patients with ESCC. LRIG1 overexpression was demonstrated to downregulate PTEN expression in ESCC cell lines, and promote their proliferation and inhibit apoptosis. In addition, LRIG1-mediated suppression of PTEN expression was inhibited by the U0126 inhibitor, which suggests that LRIG1 may inhibit the activation of PTEN signaling molecules by triggering the mitogen-activated protein kinase (MAPK)/MAPK kinase 1 (MEK) signaling pathway. In conclusion, the present study demonstrated that overexpression of LRIG1 significantly and adversely affected the survival of ESCC cells, and that the MAPK/MEK signaling pathway may be responsible for the repression of PTEN expression and function.

  20. Roles of the RAF/MEK/ERK and PI3K/PTEN/AKT pathways in malignant transformation and drug resistance.

    PubMed

    McCubrey, James A; Steelman, Linda S; Abrams, Steven L; Lee, John T; Chang, Fumin; Bertrand, Fred E; Navolanic, Patrick M; Terrian, David M; Franklin, Richard A; D'Assoro, Antonio B; Salisbury, Jeffrey L; Mazzarino, Maria Clorinda; Stivala, Franca; Libra, Massimo

    2006-01-01

    doxorubicin and paclitaxel. Raf induced the expression of the drug pump Mdr-1 (a.k.a., Pgp) and the Bcl-2 anti-apoptotic protein. Raf did not appear to induce drug resistance by altering p53/p21Cip-1 expression, whose expression is often linked to regulation of cell cycle progression and drug resistance. Deregulation of the PI3K/PTEN/Akt pathway was associated with resistance to doxorubicin and 4-hydroxyl tamoxifen, a chemotherapeutic drug and estrogen receptor antagonist used in breast cancer therapy. In contrast to the drug-resistant breast cancer cells obtained after overexpression of activated Raf, cells expressing activated Akt displayed altered (decreased) levels of p53/p21Cip-1. Deregulated expression of the central phosphatase in the PI3K/PTEN/Akt pathway led to breast cancer drug resistance. Introduction of mutated forms of PTEN, which lacked lipid phosphatase activity, increased the resistance of the MCF-7 cells to doxorubicin, suggesting that these lipid phosphatase deficient PTEN mutants acted as dominant negative mutants to suppress wild-type PTEN activity. Finally, the PI3K/PTEN/Akt pathway appears to be more prominently involved in prostate cancer drug resistance than the Raf/MEK/ERK pathway. Some advanced prostate cancer cells express elevated levels of activated Akt which may suppress Raf activation. Introduction of activated forms of Akt increased the drug resistance of advanced prostate cancer cells. In contrast, introduction of activated forms of Raf did not increase the drug resistance of the prostate cancer cells. In contrast to the results observed in hematopoietic cells, Raf may normally promote differentiation in prostate cells which is suppressed in advanced prostate cancer due to increased expression of activated Akt arising from PTEN mutation. Thus in advanced prostate cancer it may be advantageous to induce Raf expression to promote differentiation, while in hematopoietic cancers it may be beneficial to inhibit Raf/MEK/ERK-induced proliferation

  1. Methods in the Study of PTEN Structure: X-Ray Crystallography and Hydrogen Deuterium Exchange Mass Spectrometry.

    PubMed

    Masson, Glenn R; Burke, John E; Williams, Roger L

    2016-01-01

    Despite its small size and deceptively simple domain organization, PTEN remains a challenging structural target due to its N- and C-terminal intrinsically disordered segments, and the conformational heterogeneity caused by phosphorylation of its C terminus. Using hydrogen/deuterium exchange mass spectrometry (HDX-MS), it is possible to probe the conformational dynamics of the disordered termini, and also to determine how PTEN binds to lipid membranes. Here, we describe how to purify recombinant, homogenously dephosphorylated PTEN from a eukaryotic system for subsequent investigation with HDX-MS or crystallography. PMID:27033079

  2. Effect of TIMP1 transfection on PTEN expression in human kidney proximal tubular cells.

    PubMed

    Chen, J X; Cai, G Y; Chen, X M; Liu, H; Chen, X; Peng, Y M; Liu, F Y; Li, Z; Shi, S Z

    2015-12-21

    To explore the role of metalloproteinase-1 (TIMP-1) tissue inhibitor in the mechanisms of kidney aging, we observed the effects of sense and antisense transfection of TIMP-1 and of metalloproteinase (MMP) inhibitors on phosphatase and tensin homolog (PTEN), vascular endothelial growth factor (VEGF), and Flk-1 expression in TIMP-1 transgenic human proximal tubular epithelial cells (HKCs). Transfected HKCs were co-incubated with 100 μM MMP-2 and MMP-9 inhibitor III for 24 h to affect enzyme inhibition. TIMP-1, MMP-2, MMP-9, PTEN, VEGF, and Flk-1 mRNA expression was detected by reverse transcription-polymerase chain reaction. PTEN, VEGF, and Flk-1 protein expression in cells of each experimental group was measured by indirect immunofluorescence. We found that PTEN expression was up-regulated (P < 0.05) in the sense TIMP-1-transfected group (P < 0.05) compared with the non-transfected and empty vector groups, and that expression of VEGF and Flk-1 was down-regulated (P < 0.05). In contrast, the antisense TIMP-1 transgenic group showed the opposite results (P < 0.05). No significant differences in expression of PTEN, VEGF, or Flk-1 were observed among the MMP- 2/MMP-9 inhibitor III, non-transfected, and empty vector groups (P > 0.05). These results suggest that in the progression of renal aging, high expression of TIMP-1 up-regulates PTEN expression through an MMP-independent pathway, and subsequently down-regulates the expression of VEGF and Flk-1, indicating that PTEN and TIMP-1 are involved in the aging-associated impairment of renal angiogenesis. Our study provides a theoretical basis for further exploration of the mechanism underlying TIMP- 1 participation in renal aging progression.

  3. Glandular epithelial AR inactivation enhances PTEN deletion-induced uterine pathology.

    PubMed

    Choi, Jaesung Peter; Zheng, Yu; Handelsman, David J; Simanainen, Ulla

    2016-05-01

    Phosphatase and tensin homolog (PTEN) deletion induces uterine pathology, whereas androgen actions via androgen receptor (AR) support uterine growth and therefore may modify uterine cancer risk. We hypothesized that the androgen actions mediated via uterine glandular epithelial AR could modify PTEN deletion-induced uterine pathology. To test our hypothesis, we developed uterine glandular epithelium-specific PTEN and/or AR knockout mouse models comparing the uterine pathology among wild-type (WT), glandular epithelium-specific AR inactivation (ugeARKO), PTEN deletion (ugePTENKO), and the combined PTEN and AR knockout (ugePTENARKO) female mice. The double knockout restricted to glandular epithelium showed that AR inactivation enhanced PTEN deletion-induced uterine pathology with development of intraepithelial neoplasia by 20 weeks of age. In ugePTENARKO, 6/10 (60%) developed intraepithelial neoplasia, whereas 3/10 (30%) developed only glandular hyperplasia in ugePTENKO uterus. No uterine pathology was observed in WT (n=8) and ugeARKO (n=7) uteri. Uterine weight was significantly (P=0.002) increased in ugePTENARKO (374±97 mg (mean±s.e.)) compared with WT (97±6 mg), ugeARKO (94±12 mg), and ugePTENKO (205±33 mg). Estrogen receptor alpha (ERα) and P-AKT expression was modified by uterine pathology but did not differ between ugePTENKO and ugePTENARKO, suggesting that its expressions are not directly affected by androgens. However, progesterone receptor (PR) expression was reduced in ugePTENARKO compared to ugePTENKO uterus, suggesting that PR expression could be regulated by glandular epithelial AR inactivation. In conclusion, glandular epithelial AR inactivation (with persistent stromal AR action) enhanced PTEN deletion-induced uterine pathology possibly by downregulating PR expression in the uterus.

  4. Phosphatase and tensin homolog is a differential diagnostic marker between nonalcoholic and alcoholic fatty liver disease

    PubMed Central

    Sanchez-Pareja, Andrea; Clément, Sophie; Peyrou, Marion; Spahr, Laurent; Negro, Francesco; Rubbia-Brandt, Laura; Foti, Michelangelo

    2016-01-01

    AIM: To investigate the protein expression of phosphatase and tensin homolog (PTEN) in human liver biopsies of patients with alcoholic and non-alcoholic liver disease. METHODS: PTEN protein expression was assessed by immunohistochemistry in formalin-fixed, paraffin-embedded liver sections of patients with non-alcoholic fatty liver disease (NAFLD) (n = 44) or alcoholic liver disease (ALD) (n = 25). Liver resections obtained from 3 healthy subjects candidate for partial liver donation served as controls. Histological evaluations were performed by two experienced pathologists, and diagnoses established based on international criteria. The intensity of the PTEN staining in nuclei was compared between steatotic and non-steatotic areas of each liver fragment analyzed. For each liver specimen, the antibody-stained sections were examined and scored blindly by three independent observers, who were unaware of the patients’ clinical history. RESULTS: In healthy individuals, PTEN immunostaining was intense in both the cytoplasm and nuclei of all hepatocytes. However, PTEN was strongly downregulated in both the nucleus and the cytoplasm of hepatocytes from steatotic areas in patients with NAFLD, independently of the disease stage. In contrast, no changes in PTEN protein expression were observed in patients with ALD, regardless of the presence of steatosis or the stage of the disease. The degree of PTEN downregulation in hepatocytes of patients with NAFLD correlated with the percentage of steatosis (r = 0.3061, P = 0.0459) and the BMI (r = 0.4268, P = 0.0043). Hovewer, in patients with ALD, PTEN expression was not correlated with the percentage of steatosis with or without obesity as a confounding factor (P = 0.5574). Finally, PTEN expression level in steatotic areas of ALD patients was significantly different from that seen in steatotic areas of NAFLD patients (P < 0.0001). CONCLUSION: PTEN protein expression is downregulated early in NAFLD, but not in ALD. PTEN

  5. Power of PTEN/AKT: Molecular switch between tumor suppressors and oncogenes

    PubMed Central

    XIE, YINGQIU; NAIZABEKOV, SANZHAR; CHEN, ZHANLIN; TOKAY, TURSONJAN

    2016-01-01

    An increasing amount of evidence has shown that tumor suppressors can become oncogenes, or vice versa, but the mechanism behind this is unclear. Recent findings have suggested that phosphatase and tensin homolog (PTEN) is one of the powerful switches for the conversion between tumor suppressors and oncogenes. PTEN regulates a number of cellular processes, including cell death and proliferation, through the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway. Furthermore, a number of studies have suggested that PTEN deletions may alter various functions of certain tumor suppressor and oncogenic proteins. The aim of the present review was to analyze specific cases driven by PTEN loss/AKT activation, including aberrant signaling pathways and novel drug targets for clinical application in personalized medicine. The findings illustrate how PTEN loss and/or AKT activation switches MDM2-dependent p53 downregulation, and induces conversion between oncogene and tumor suppressor in enhancer of zeste homolog 2, BTB domain-containing 7A, alternative reading frame 2, p27 and breast cancer 1, early onset, through multiple mechanisms. This review highlights the genetic basis of complex drug targets and provides insights into the rationale of precision cancer therapy. PMID:27347153

  6. FGFR and PTEN signaling interact during lens development to regulate cell survival.

    PubMed

    Chaffee, Blake R; Hoang, Thanh V; Leonard, Melissa R; Bruney, Devin G; Wagner, Brad D; Dowd, Joseph Richard; Leone, Gustavo; Ostrowski, Michael C; Robinson, Michael L

    2016-02-15

    Lens epithelial cells express many receptor tyrosine kinases (RTKs) that stimulate PI3K-AKT and RAS-RAF-MEK-ERK intracellular signaling pathways. These pathways ultimately activate the phosphorylation of key cellular transcription factors and other proteins that control proliferation, survival, metabolism, and differentiation in virtually all cells. Among RTKs in the lens, only stimulation of fibroblast growth factor receptors (FGFRs) elicits a lens epithelial cell to fiber cell differentiation response in mammals. Moreover, although the lens expresses three different Fgfr genes, the isolated removal of Fgfr2 at the lens placode stage inhibits both lens cell survival and fiber cell differentiation. Phosphatase and tensin homolog (PTEN), commonly known as a tumor suppressor, inhibits ERK and AKT activation and initiates both apoptotic pathways, and cell cycle arrest. Here, we show that the combined deletion of Fgfr2 and Pten rescues the cell death phenotype associated with Fgfr2 loss alone. Additionally, Pten removal increased AKT and ERK activation, above the levels of controls, in the presence or absence of Fgfr2. However, isolated deletion of Pten failed to stimulate ectopic fiber cell differentiation, and the combined deletion of Pten and Fgfr2 failed to restore differentiation-specific Aquaporin0 and DnaseIIβ expression in the lens fiber cells.

  7. JNK and PTEN cooperatively control the development of invasive adenocarcinoma of the prostate

    PubMed Central

    Hübner, Anette; Mulholland, David J.; Standen, Claire L.; Karasarides, Maria; Cavanagh-Kyros, Julie; Barrett, Tamera; Chi, Hongbo; Greiner, Dale L.; Tournier, Cathy; Sawyers, Charles L.; Flavell, Richard A.; Wu, Hong; Davis, Roger J.

    2012-01-01

    The c-Jun NH2-terminal kinase (JNK) signal transduction pathway is implicated in cancer, but the role of JNK in tumorigenesis is poorly understood. Here, we demonstrate that the JNK signaling pathway reduces the development of invasive adenocarcinoma in the phosphatase and tensin homolog (Pten) conditional deletion model of prostate cancer. Mice with JNK deficiency in the prostate epithelium (ΔJnk ΔPten mice) develop androgen-independent metastatic prostate cancer more rapidly than control (ΔPten) mice. Similarly, prevention of JNK activation in the prostate epithelium (ΔMkk4 ΔMkk7 ΔPten mice) causes rapid development of invasive adenocarcinoma. We found that JNK signaling defects cause an androgen-independent expansion of the immature progenitor cell population in the primary tumor. The JNK-deficient progenitor cells display increased proliferation and tumorigenic potential compared with progenitor cells from control prostate tumors. These data demonstrate that the JNK and PTEN signaling pathways can cooperate to regulate the progression of prostate neoplasia to invasive adenocarcinoma. PMID:22753496

  8. Conditional Inactivation of Pten with EGFR Overexpression in Schwann Cells Models Sporadic MPNST

    PubMed Central

    Keng, Vincent W.; Watson, Adrienne L.; Rahrmann, Eric P.; Li, Hua; Tschida, Barbara R.; Moriarity, Branden S.; Choi, Kwangmin; Rizvi, Tilat A.; Collins, Margaret H.; Wallace, Margaret R.; Ratner, Nancy; Largaespada, David A.

    2012-01-01

    The genetic mechanisms involved in the transformation from a benign neurofibroma to a malignant sarcoma in patients with neurofibromatosis-type-1- (NF1-)associated or sporadic malignant peripheral nerve sheath tumors (MPNSTs) remain unclear. It is hypothesized that many genetic changes are involved in transformation. Recently, it has been shown that both phosphatase and tensin homolog (PTEN) and epidermal growth factor receptor (EGFR) play important roles in the initiation of peripheral nerve sheath tumors (PNSTs). In human MPNSTs, PTEN expression is often reduced, while EGFR expression is often induced. We tested if these two genes cooperate in the evolution of PNSTs. Transgenic mice were generated carrying conditional floxed alleles of Pten, and EGFR was expressed under the control of the 2′,3′-cyclic nucleotide 3′phosphodiesterase (Cnp) promoter and a desert hedgehog (Dhh) regulatory element driving Cre recombinase transgenic mice (Dhh-Cre). Complete loss of Pten and EGFR overexpression in Schwann cells led to the development of high-grade PNSTs. In vitro experiments using immortalized human Schwann cells demonstrated that loss of PTEN and overexpression of EGFR cooperate to increase cellular proliferation and anchorage-independent colony formation. This mouse model can rapidly recapitulate PNST onset and progression to high-grade PNSTs, as seen in sporadic MPNST patients. PMID:23319880

  9. miR-17 inhibitor suppressed osteosarcoma tumor growth and metastasis via increasing PTEN expression

    SciTech Connect

    Gao, Yong; Luo, Ling-hui; Li, Shuai; Yang, Cao

    2014-02-07

    Highlights: • miR-17 was increased in OS tissues and cell lines. • Inhibition of miR-17 suppressed OS cell proliferation. • Inhibition of miR-17 suppressed OS cell migration and invasion. • PTEN was a target of miR-17. • miR-17 was negatively correlated with PTEN in OS tissues. - Abstract: MicroRNAs (miRNAs) play essential roles in cancer development and progression. Here, we investigated the role of miR-17 in the progression and metastasis of osteosarcoma (OS). miR-17 was frequently increased in OS tissues and cell lines. Inhibition of miR-17 in OS cell lines substantially suppressed cell proliferation, migration, and invasion. Phosphatase and tensin homolog (PTEN) was identified as a target of miR-17, and ectopic expression of miR-17 inhibited PTEN by direct binding to its 3′-untranslated region (3′-UTR). Expression of miR-17 was negatively correlated with PTEN in OS tissues. Together, these findings indicate that miR-17 acts as an oncogenic miRNA and may contribute to the progression and metastasis of OS, suggesting miR-17 as a potential novel diagnostic and therapeutic target of OS.

  10. Oocyte-specific deletion of Pten in mice reveals a stage-specific function of PTEN/PI3K signaling in oocytes in controlling follicular activation.

    PubMed

    Jagarlamudi, Krishna; Liu, Lian; Adhikari, Deepak; Reddy, Pradeep; Idahl, Annika; Ottander, Ulrika; Lundin, Eva; Liu, Kui

    2009-07-09

    Immature ovarian primordial follicles are essential for maintenance of the reproductive lifespan of female mammals. Recently, it was found that overactivation of the phosphatidylinositol 3-kinase (PI3K) signaling in oocytes of primordial follicles by an oocyte-specific deletion of Pten (phosphatase and tensin homolog deleted on chromosome ten), the gene encoding PI3K negative regulator PTEN, results in premature activation of the entire pool of primordial follicles, indicating that activation of the PI3K pathway in oocytes is important for control of follicular activation. To investigate whether PI3K signaling in oocytes of primary and further developed follicles also plays a role at later stages in follicular development and ovulation, we conditionally deleted the Pten gene from oocytes of primary and further developed follicles by using transgenic mice expressing zona pellucida 3 (Zp3) promoter-mediated Cre recombinase. Our results show that Pten was efficiently deleted from oocytes of primary and further developed follicles, as indicated by the elevated phosphorylation of the major PI3K downstream component Akt. However, follicular development was not altered and oocyte maturation was also normal, which led to normal fertility with unaltered litter size in the mutant mice. Our data indicate that properly controlled PTEN/PI3K-Akt signaling in oocytes is essential for control of the development of primordial follicles whereas overactivation of PI3K signaling in oocytes does not appear to affect the development of growing follicles. This suggests that there is a stage-specific function of PTEN/PI3K signaling in mouse oocytes that controls follicular activation.

  11. Adenovirus-mediated co-expression of ING4 and PTEN cooperatively enhances their antitumor activity in human hepatocellular carcinoma cells.

    PubMed

    Rakshit, Nargis; Yang, Sijun; Zhou, Wei; Xu, Yi; Deng, Chenghui; Yang, Jiecheng; Yu, Huijun; Wei, Wenxiang

    2016-08-01

    Both inhibitor of growth 4 (ING4) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) are well known as tumor suppressors that are closely related to tumor occurrence and progression. It was reported that ING4 and PTEN showed synergistic antitumor activities in nasopharyngeal carcinoma cells. The two tumor suppressors demonstrated synergistic effect on growth inhibition and apoptosis activation. In this study, we investigated their therapeutic potential in hepatocellular carcinoma (HCC) cells. Recombinant adenoviruses co-expressing ING4 and PTEN (Ad-ING4-PTEN) were constructed, and the antitumor effect on SMMC-7721 and HepG2 HCC cells was evaluated. Ad-ING4-PTEN cooperatively inhibited cell growth, stimulated apoptosis, and suppressed invasion in both HCC cells, and regulated cell cycle in SMMC-7721. Further studies showed that the combination of ING4 and PTEN by Ad-ING4-PTEN cooperatively enhanced the alteration of the expression of cell cycle-related proteins (p53, p21, and cyclin D1) and apoptotic factors (Bad, Bcl-2, Bcl-XL, and Bax), which are involved in the regulation of cell cycle and the activation of apoptotic pathways, leading to the synergistic antitumor effect. These results indicate that the combination of ING4 and PTEN may provide an effective therapeutic strategy for HCC.

  12. PRL-3 promotes the peritoneal metastasis of gastric cancer through the PI3K/Akt signaling pathway by regulating PTEN.

    PubMed

    Xiong, Jianbo; Li, Zhengrong; Zhang, Yang; Li, Daojiang; Zhang, Guoyang; Luo, Xianshi; Jie, Zhigang; Liu, Yi; Cao, Yi; Le, Zhibiao; Tan, Shengxing; Zou, Wenyu; Gong, Peitao; Qiu, Lingyu; Li, Yuanyuan; Wang, Huan; Chen, Heping

    2016-10-01

    Peritoneal metastasis is the most frequent cause of death in patients with advanced gastric carcinoma (GC). The phosphatase of regenerating liver-3 (PRL-3) is recognized as an oncogene and plays an important role in GC peritoneal metastasis. However, the mechanism of how PRL-3 regulates GC invasion and metastasis is unknown. In the present study, we found that PRL-3 presented with high expression in GC with peritoneal metastasis, but phosphatase and tensin homologue (PTEN) was weakly expressed. The p-PTEN/PTEN ratio was also higher in GC with peritoneal metastasis than that in the normal gastric tissues. We also found the same phenomenon when comparing the gastric mucosa cell line with the GC cell lines. After constructing a wild-type and a mutant-type plasmid without enzyme activity and transfecting them into GC SGC7901 cells, we showed that only PRL-3 had enzyme activity to downregulate PTEN and cause PTEN phosphorylation. The results also showed that PRL-3 increased the expression levels of MMP-2/MMP-9 and promoted the migration and invasion of the SGC7901 cells. Knockdown of PRL-3 decreased the expression levels of MMP-2/MMP-9 significantly, which further inhibited the migration and invasion of the GC cells. PRL-3 also increased the expression ratio of p-Akt/Akt, which indicated that PRL-3 may mediate the PI3K/Akt pathway to promote GC metastasis. When we transfected the PTEN siRNA plasmid into the PRL-3 stable low expression GC cells, the expression of p-Akt, MMP-2 and MMP-9 was reversed. In conclusion, our results provide a bridge between PRL-3 and PTEN; PRL-3 decreased the expression of PTEN as well as increased the level of PTEN phosphorylation and inactivated it, consequently activating the PI3K/Akt signaling pathway, and upregulating MMP-2/MMP-9 expression to promote GC cell peritoneal metastasis.

  13. PRL-3 promotes the peritoneal metastasis of gastric cancer through the PI3K/Akt signaling pathway by regulating PTEN

    PubMed Central

    Xiong, Jianbo; Li, Zhengrong; Zhang, Yang; Li, Daojiang; Zhang, Guoyang; Luo, Xianshi; Jie, Zhigang; Liu, Yi; Cao, Yi; Le, Zhibiao; Tan, Shengxing; Zou, Wenyu; Gong, Peitao; Qiu, Lingyu; Li, Yuanyuan; Wang, Huan; Chen, Heping

    2016-01-01

    Peritoneal metastasis is the most frequent cause of death in patients with advanced gastric carcinoma (GC). The phosphatase of regenerating liver-3 (PRL-3) is recognized as an oncogene and plays an important role in GC peritoneal metastasis. However, the mechanism of how PRL-3 regulates GC invasion and metastasis is unknown. In the present study, we found that PRL-3 presented with high expression in GC with peritoneal metastasis, but phosphatase and tensin homologue (PTEN) was weakly expressed. The p-PTEN/PTEN ratio was also higher in GC with peritoneal metastasis than that in the normal gastric tissues. We also found the same phenomenon when comparing the gastric mucosa cell line with the GC cell lines. After constructing a wild-type and a mutant-type plasmid without enzyme activity and transfecting them into GC SGC7901 cells, we showed that only PRL-3 had enzyme activity to downregulate PTEN and cause PTEN phosphorylation. The results also showed that PRL-3 increased the expression levels of MMP-2/MMP-9 and promoted the migration and invasion of the SGC7901 cells. Knockdown of PRL-3 decreased the expression levels of MMP-2/MMP-9 significantly, which further inhibited the migration and invasion of the GC cells. PRL-3 also increased the expression ratio of p-Akt/Akt, which indicated that PRL-3 may mediate the PI3K/Akt pathway to promote GC metastasis. When we transfected the PTEN siRNA plasmid into the PRL-3 stable low expression GC cells, the expression of p-Akt, MMP-2 and MMP-9 was reversed. In conclusion, our results provide a bridge between PRL-3 and PTEN; PRL-3 decreased the expression of PTEN as well as increased the level of PTEN phosphorylation and inactivated it, consequently activating the PI3K/Akt signaling pathway, and upregulating MMP-2/MMP-9 expression to promote GC cell peritoneal metastasis. PMID:27572739

  14. Modeling self-organized spatio-temporal patterns of PIP3 and PTEN during spontaneous cell polarization

    NASA Astrophysics Data System (ADS)

    Knoch, Fabian; Tarantola, Marco; Bodenschatz, Eberhard; Rappel, Wouter-Jan

    2014-08-01

    During spontaneous cell polarization of Dictyostelium discoideum cells, phosphatidylinositol (3,4,5)-triphoshpate (PIP3) and PTEN (phosphatase tensin homolog) have been identified as key signaling molecules which govern the process of polarization in a self-organized manner. Recent experiments have quantified the spatio-temporal dynamics of these signaling components. Surprisingly, it was found that membrane-bound PTEN can be either in a high or low state, that PIP3 waves were initiated in areas lacking PTEN through an excitable mechanism, and that PIP3 was degraded even though the PTEN concentration remained low. Here we develop a reaction-diffusion model that aims to explain these experimental findings. Our model contains bistable dynamics for PTEN, excitable dynamics for PIP3, and postulates the existence of two species of PTEN with different dephosphorylation rates. We show that our model is able to produce results that are in good qualitative agreement with the experiments, suggesting that our reaction-diffusion model underlies the self-organized spatio-temporal patterns observed in experiments.

  15. PTEN/MMAC1/TEP1 suppresses the tumorigenicity and induces G1 cell cycle arrest in human glioblastoma cells

    PubMed Central

    Li, Da-Ming; Sun, Hong

    1998-01-01

    PTEN/MMAC1/TEP1 is a tumor suppressor that possesses intrinsic phosphatase activity. Deletions or mutations of its encoding gene are associated with a variety of human cancers. However, very little is known about the molecular mechanisms by which this important tumor suppressor regulates cell growth. Here, we show that PTEN expression potently suppressed the growth and tumorigenicity of human glioblastoma U87MG cells. The growth suppression activity of PTEN was mediated by its ability to block cell cycle progression in the G1 phase. Such an arrest correlated with a significant increase of the cell cycle kinase inhibitor p27KIP1 and a concomitant decrease in the activities of the G1 cyclin-dependent kinases. PTEN expression also led to the inhibition of Akt/protein kinase B, a serine-threonine kinase activated by the phosphatidylinositol 3-kinase (PI 3-kinase) signaling pathway. In addition, the effect of PTEN on p27KIP1 and the cell cycle can be mimicked by treatment of U87MG cells with LY294002, a selective inhibitor of PI 3-kinase. Taken together, our studies suggest that the PTEN tumor suppressor modulates G1 cell cycle progression through negatively regulating the PI 3-kinase/Akt signaling pathway, and one critical target of this signaling process is the cyclin-dependent kinase inhibitor p27KIP1. PMID:9860981

  16. Herpes simplex virus type 1 VP22-mediated intercellular delivery of PTEN increases the antitumor activity of PTEN in esophageal squamous cell carcinoma cells in vitro and in vivo.

    PubMed

    Yu, Xian; Li, Tingting; Xia, Yifan; Lei, Jun; Wang, Yan; Zhang, Lijuan

    2016-05-01

    In the past decade, studies have revealed that the phosphatase and tensin homolog (PTEN) protein, a tumor suppressor, comprises a potential biological marker and therapeutic target for esophageal squamous cell carcinoma (ESCC). As such, the delivery of the PTEN gene represents a powerful strategy for ESCC therapy. The tegument protein VP22 of herpes simplex virus type 1 (HSV-1) has been reported to act as a transporter of heterologous proteins across the host cell membrane, thereby enhancing the biological functions of these proteins. In the present study, the intercellular delivery and antitumor activity of the fusion protein PTEN-VP22 were examined in the esophageal squamous cell carcinoma cell line Eca109 both in vitro and in vivo. VP22-mediated PTEN intercellular delivery was confirmed in the Eca109 cells by western blot analysis and by quantitation of immunofluorescence. VP22 alone did not exert antiproliferative effects or induce cell cycle arrest, induction of apoptosis, blockage of the Akt and focal adhesion kinase (FAK) pathways, tumor growth inhibition, or antiangiogenic effects in Eca109 cells. However, compared with PTEN alone, PTEN-VP22 exerted significantly higher antiproliferative effects and induced cell cycle arrest at G1 stage, apoptosis and antiangiogenic effects in Eca109 cells. Together, our findings demonstrate that VP22 alone does not exert antitumor activity directly; however, this protein mediates the intercellular delivery of PTEN and thereby increases its intracellular concentration to achieve a therapeutic steady state, leading to an overall increase in the antitumor activity of PTEN. This study provides further experimental data to confirm the potential of VP22-based intercellular delivery strategies for enhancing the efficacy of gene therapy for cancer treatment.

  17. MicroRNA-21 Contributes to Liver Regeneration by Targeting PTEN

    PubMed Central

    Chen, Xiaoyu; Song, Meiyi; Chen, Wei; Dimitrova-Shumkovska, Jasmina; Zhao, Yingying; Cao, Yan; Song, Yang; Yang, Wenzhuo; Wang, Fei; Xiang, Yang; Yang, Changqing

    2016-01-01

    Background Multiple microRNAs (miRNAs, miRs), including miR-21, have been documented to be critical regulators of liver regeneration, but the mechanism underlying their roles in hepatocyte proliferation and cell cycle progression is still far from understood. Material/Methods miR-21 levels were determined using qRT-PCRs in mouse livers at 48 h after 70% partial hepatectomy (PH-48 h). Cell proliferation was determined by use of a cell-counting kit-8 (CCK-8), EdU incorporation staining, and flow cytometry. Phosphatase and tensin homolog (PTEN) expressions were determined using qRT-PCR and Western blot analysis. PTEN siRNA was used to perform the rescue experiment. Results A marked upregulation of miR-21 was observed in mouse livers at 48 h after 70% partial hepatectomy (PH-48 h) compared to 0 h after PH (PH-0 h). Overexpression of miR-21 was associated with increased proliferation and a rapid G1-to-S phase transition of the cell cycle in BNL CL.2 normal liver cells in vitro. In addition, we showed that PTEN expression was inversely correlated with miR-21 in BNL CL.2 cells and demonstrated that PTEN expression is lower in mouse livers at PH-48 h. Moreover, the presence of PTEN siRNA significantly abolished the suppressive effect of miR-21 inhibitor on hepatocyte proliferation. Conclusions miR-21 overexpression contributes to liver regeneration and hepatocyte proliferation by targeting PTEN. Upregulation of miR-21 might be a useful therapeutic strategy to promote liver regeneration. PMID:26744142

  18. PTEN regulates AMPA receptor-mediated cell viability in iPS-derived motor neurons.

    PubMed

    Yang, D-J; Wang, X-L; Ismail, A; Ashman, C J; Valori, C F; Wang, G; Gao, S; Higginbottom, A; Ince, P G; Azzouz, M; Xu, J; Shaw, P J; Ning, K

    2014-02-27

    Excitatory transmission in the brain is commonly mediated by the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors. In amyotrophic lateral sclerosis (ALS), AMPA receptors allow cytotoxic levels of calcium into neurons, contributing to motor neuron injury. We have previously shown that oculomotor neurons resistant to the disease process in ALS show reduced AMPA-mediated inward calcium currents compared with vulnerable spinal motor neurons. We have also shown that PTEN (phosphatase and tensin homolog deleted on chromosome 10) knockdown via siRNA promotes motor neuron survival in models of spinal muscular atrophy (SMA) and ALS. It has been reported that inhibition of PTEN attenuates the death of hippocampal neurons post injury by decreasing the effective translocation of the GluR2 subunit into the membrane. In addition, leptin can regulate AMPA receptor trafficking via PTEN inhibition. Thus, we speculate that manipulation of AMPA receptors by PTEN may represent a potential therapeutic strategy for neuroprotective intervention in ALS and other neurodegenerative disorders. To this end, the first step is to establish a fibroblast-iPS-motor neuron in vitro cell model to study AMPA receptor manipulation. Here we report that iPS-derived motor neurons from human fibroblasts express AMPA receptors. PTEN depletion decreases AMPA receptor expression and AMPA-mediated whole-cell currents, resulting in inhibition of AMPA-induced neuronal death in primary cultured and iPS-derived motor neurons. Taken together, our results imply that PTEN depletion may protect motor neurons by inhibition of excitatory transmission that represents a therapeutic strategy of potential benefit for the amelioration of excitotoxicity in ALS and other neurodegenerative disorders.

  19. PTEN gene mutations correlate to poor prognosis in glioma patients: a meta-analysis

    PubMed Central

    Han, Feng; Hu, Rong; Yang, Hua; Liu, Jian; Sui, Jianmei; Xiang, Xin; Wang, Fan; Chu, Liangzhao; Song, Shibin

    2016-01-01

    Background We conducted this meta-analysis based on eligible trials to investigate the relationship between phosphatase and tensin homolog (PTEN) genetic mutation and glioma patients’ survival. Methods PubMed, Web of Science, and EMBASE were searched for eligible studies regarding the relationship between PTEN genetic mutation and glioma patients’ survival. The primary outcome was the overall survival of glioma patient with or without PTEN genetic mutation, and second outcome was prognostic factors for the survival of glioma patient. A fixed-effects or random-effects model was used to pool the estimates according to the heterogeneity among the included studies. Results Nine cohort studies, involving 1,173 patients, were included in this meta-analysis. Pooled results suggested that glioma patients with PTEN genetic mutation had a significant shorter overall survival than those without PTEN genetic mutation (hazard ratio [HR] =2.23, 95% confidence interval [CI]: 1.35, 3.67; P=0.002). Furthermore, subgroup analysis indicated that this association was only observed in American patients (HR =2.19, 95% CI: 1.23, 3.89; P=0.008), but not in Chinese patients (HR =1.44, 95% CI: 0.29, 7.26; P=0.657). Histopathological grade (HR =1.42, 95% CI: 0.07, 28.41; P=0.818), age (HR =0.94, 95% CI: 0.43, 2.04; P=0.877), and sex (HR =1.28, 95% CI: 0.55, 2.98; P=0.564) were not significant prognostic factors for the survival of patients with glioma. Conclusion Current evidence indicates that PTEN genetic mutation is associated with poor prognosis in glioma patients. However, this finding is derived from data in observational studies, potentially subject to selection bias, and hence well conducted, high-quality randomized controlled trials are warranted. PMID:27366085

  20. Association of PTEN gene polymorphisms with liver cancer risk

    PubMed Central

    Li, Hong-Guang; Liu, Fang-Feng; Zhu, Hua-Qiang; Zhou, Xu; Lu, Jun; Chang, Hong; Hu, Jin-Hua

    2015-01-01

    Objective: To find out if there are any relationship between three single nucleotide polymorphisms (SNPs) of phosphatase and tensin homolog (PTEN) gene (rs1234213, rs1234220, and rs2299939) and the susceptibility of liver cancer. Methods: Genotypes of the three SNPs in the PTEN gene were achieved utilizing polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Comparison of genotypes and alleles distribution differences between the case and the control subjects was accomplished with χ2 test. The analysis of linkage disequilibrium (LD) and haplotypes of the three SNPs was performed using SHEsis software. We adopted odds ratios (ORs) with 95% confidence intervals (95% CIs) to show the relative risk of liver cancer. Results: TC genotype and C allele of rs1234220 polymorphism showed much more frequently in cases than in controls, reflecting that the TC genotype and the C allele may be linked to the increased risk of liver cancer (OR=2.225, 95% CI=1.178-4.204; OR=1.941, 95% CI=1.124-3.351). Rs2299939 polymorphism showed an opposite result that the GT genotype probably reduce the risk of liver cancer (OR=0.483, 95% CI=0.259-0.900). Statistical significance was not found in the distribution differences of the genotypes of rs1234213 between two groups. LD and haplotype analysis results of the three SNPs showed that the T-C-G haplotype frequency was much higher in cases than in healthy objects, which proved that the T-C-G haplotype might be a susceptibility haplotype for liver cancer (OR=3.750, 95% CI=1.396-10.077). Conclusions: PTEN gene polymorphisms might relate to liver cancer risk. PMID:26823866

  1. Analytic validation of a clinical-grade PTEN immunohistochemistry assay in prostate cancer by comparison with PTEN FISH.

    PubMed

    Lotan, Tamara L; Wei, Wei; Ludkovski, Olga; Morais, Carlos L; Guedes, Liana B; Jamaspishvili, Tamara; Lopez, Karen; Hawley, Sarah T; Feng, Ziding; Fazli, Ladan; Hurtado-Coll, Antonio; McKenney, Jesse K; Simko, Jeffrey; Carroll, Peter R; Gleave, Martin; Lin, Daniel W; Nelson, Peter S; Thompson, Ian M; True, Lawrence D; Brooks, James D; Lance, Raymond; Troyer, Dean; Squire, Jeremy A

    2016-08-01

    PTEN loss is a promising prognostic and predictive biomarker in prostate cancer. Because it occurs most commonly via PTEN gene deletion, we developed a clinical-grade, automated, and inexpensive immunohistochemical assay to detect PTEN loss. We studied the sensitivity and specificity of PTEN immunohistochemistry relative to four-color fluorescence in situ hybridization (FISH) for detection of PTEN gene deletion in a multi-institutional cohort of 731 primary prostate tumors. Intact PTEN immunostaining was 91% specific for the absence of PTEN gene deletion (549/602 tumors with two copies of the PTEN gene by FISH showed intact expression of PTEN by immunohistochemistry) and 97% sensitive for the presence of homozygous PTEN gene deletion (absent PTEN protein expression by immunohistochemistry in 65/67 tumors with homozygous deletion). PTEN immunohistochemistry was 65% sensitive for the presence of hemizygous PTEN gene deletion, with protein loss in 40/62 hemizygous tumors. We reviewed the 53 cases where immunohistochemistry showed PTEN protein loss and FISH showed two intact copies of the PTEN gene. On re-review, there was ambiguous immunohistochemistry loss in 6% (3/53) and failure to analyze the same tumor area by both methods in 34% (18/53). Of the remaining discordant cases, 41% (13/32) revealed hemizygous (n=8) or homozygous (n=5) PTEN gene deletion that was focal in most cases (11/13). The remaining 19 cases had two copies of the PTEN gene detected by FISH, representing truly discordant cases. Our automated PTEN immunohistochemistry assay is a sensitive method for detection of homozygous PTEN gene deletions. Immunohistochemistry screening is particularly useful to identify cases with heterogeneous PTEN gene deletion in a subset of tumor glands. Mutations, small insertions, or deletions and/or epigenetic or microRNA-mediated mechanisms may lead to PTEN protein loss in tumors with normal or hemizygous PTEN gene copy number.

  2. Simultaneous inactivation of Par-4 and PTEN in vivo leads to synergistic NF-κB activation and invasive prostate carcinoma

    PubMed Central

    Fernandez-Marcos, Pablo J.; Abu-Baker, Shadi; Joshi, Jayashree; Galvez, Anita; Castilla, Elias A.; Cañamero, Marta; Collado, Manuel; Saez, Carmen; Moreno-Bueno, Gema; Palacios, Jose; Leitges, Michael; Serrano, Manuel; Moscat, Jorge; Diaz-Meco, Maria T.

    2009-01-01

    Prostate cancer is one of the most common neoplasias in men. The tumor suppressor Par-4 is an important negative regulator of the canonical NF-κB pathway and is highly expressed in prostate. Here we show that Par-4 expression is lost in a high percentage of human prostate carcinomas, and this occurs in association with phosphatase and tensin homolog deleted from chromosome 10 (PTEN) loss. Par-4 null mice, similar to PTEN-heterozygous mice, only develop benign prostate lesions, but, importantly, concomitant Par-4 ablation and PTEN-heterozygosity lead to invasive prostate carcinoma in mice. This strong tumorigenic cooperation is anticipated in the preneoplastic prostate epithelium by an additive increase in Akt activation and a synergistic stimulation of NF-κB. These results establish the cooperation between Par-4 and PTEN as relevant for the development of prostate cancer and implicate the NF-κB pathway as a critical event in prostate tumorigenesis. PMID:19470463

  3. Adenovirus-mediated ING4/PTEN double tumor suppressor gene co-transfer modified by RGD enhances antitumor activity in human nasopharyngeal carcinoma cells.

    PubMed

    Wang, Yihong; Yang, Jicheng; Sheng, Weihua; Xie, Yufeng; Liu, Jisheng

    2015-03-01

    Inhibitor of growth-4 (ING4) is a member of the inhibitor of growth (ING) family and acts as a tumor suppressor protein. PTEN is a phosphatase and shows potent and extensive antitumor activity. In this study, we constructed an RGD-modified bicistronic ING4/PTEN adenovirus (Ad.RGD-ING4-PTEN) and comprehensively investigated its effects following modification of the CNE human nasopharyngeal carcinoma cell line both in vitro and in vivo. We demonstrated that Ad.RGD-ING4-PTEN enhanced growth inhibition and apoptosis. Furthermore, expression of P21, Bax and cleaved caspase-3 was upregulated, while that of Bcl-2 and survivin was downregulated in CNE cells and CNE xenografted tumors. Moreover, Ad.RGD-ING4-PTEN treatment additively downregulated CD34, VEGF and microvessel density in subcutaneously (s.c.) xenografted CNE cell tumors. The enhanced antitumor activity generated by Ad.RGD-ING4-PTEN was closely associated with activation of the intrinsic and extrinsic apoptotic pathways and additive inhibition of tumor angiogenesis both in vitro and in vivo. On the basis of this evidence, it is believed that cancer gene therapy combining two tumor suppressors such as ING4 and PTEN can be used to establish an effective and novel therapeutic strategy for nasopharyngeal carcinoma and other cancers.

  4. FAK mediates a compensatory survival signal parallel to PI3K-AKT in PTEN-null T-ALL cells.

    PubMed

    You, Dewen; Xin, Junping; Volk, Andrew; Wei, Wei; Schmidt, Rachel; Scurti, Gina; Nand, Sucha; Breuer, Eun-Kyoung; Kuo, Paul C; Breslin, Peter; Kini, Ameet R; Nishimura, Michael I; Zeleznik-Le, Nancy J; Zhang, Jiwang

    2015-03-31

    Mutations and inactivation of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) are observed in 15%-25% of cases of human T cell acute lymphoblastic leukemia (T-ALL). Pten deletion induces myeloproliferative disorders (MPDs), acute myeloid leukemia (AML), and/or T-ALL in mice. Previous studies attributed Pten-loss-related hematopoietic defects and leukemogenesis to excessive activation of phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling. Although inhibition of this signal dramatically suppresses the growth of PTEN-null T-ALL cells in vitro, treatment with inhibitors of this pathway does not cause a complete remission in vivo. Here, we report that focal adhesion kinase (Fak), a protein substrate of Pten, also contributes to T-ALL development in Pten-null mice. Inactivation of the FAK signaling pathway by either genetic or pharmacologic methods significantly sensitizes both murine and human PTEN-null T-ALL cells to PI3K/AKT/mTOR inhibition when cultured in vitro on feeder layer cells or a matrix and in vivo. PMID:25801032

  5. Hidden association of Cowden syndrome, PTEN mutation and meningioma frequency

    PubMed Central

    Yakubov, Eduard; Ghoochani, Ali; Buslei, Rolf; Buchfelder, Michael; Eyüpoglu, Ilker Y.; Savaskan, Nicolai

    2016-01-01

    Cowden syndrome (CS) is clinically presented by multiple hamartomas, often with mucocutaneous lesions, goiter, breast cancer and gastrointestinal polyps. CS is a genetic disorder of autosomal dominant inheritance and is one distinct syndrome of the phosphatase and tensin homolog on chromosome 10 (PTEN) hamartoma tumor spectrum. Noteworthy, PTEN germline mutations are related to a wide range of brain tumors. We performed a systematic analysis and review of the medical literature for Cowden syndrome and meningioma and additionally present the case of a 29-year- old CS patient diagnosed with multiple meningiomas. We found strong evidence for high incidence of brain tumors in CS patients. In particular meningiomas and gangliocytomas/Lhermitte-Duclos disease were often associated with 8% and 9% respectively in CS patients. Since aberrations in chromosome 10q are associated with meningiomas, it is likely that the underlying mutations in CS drive to a certain extent neoplastic meningioma growth. We propose to include meningiomas and brain tumors in the major criteria spectrum of CS-related disorders. This could warrant early diagnosis of brain lesions and close therapy, as well as better monitoring of patients with CS. PMID:27489861

  6. Cisplatin-induced caspase activation mediates PTEN cleavage in ovarian cancer cells: a potential mechanism of chemoresistance

    PubMed Central

    2013-01-01

    Background The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor protein is a central negative regulator of the PI3K/AKT signaling cascade and suppresses cell survival as well as cell proliferation. PTEN is found to be either inactivated or mutated in various human malignancies. In the present study, we have investigated the regulation of PTEN during cisplatin induced apoptosis in A2780, A270-CP (cisplatin resistant), OVCAR-3 and SKOV3 ovarian cancer cell lines. Methods Cells were treated with 10μM of cisplatin for 24h. Transcript and protein levels were analysed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blotting, respectively. Immunofluorescence microscopy was used to assess the intracellular localization of PTEN. Proteasome inhibitor and various caspases inhibitors were used to find the mechanism of PTEN degradation. Results PTEN protein levels were found to be decreased significantly in A2780 cells; however, there was no change in PTEN protein levels in A2780-CP, OVCAR-3 and SKOV3 cells with cisplatin treatment. The decrease in PTEN protein was accompanied with an increase in the levels of AKT phosphorylation (pAKT) in A2780 cells and a decrease of BCL-2. Cisplatin treatment induced the activation/cleavage of caspase-3, -6, -7, -8, -9 in all cell lines tested in this study except the resistant variant A2780-CP cells. In A2780 cells, restoration of PTEN levels was achieved upon pre-treatment with Z-DEVD-FMK (broad range caspases inhibitor) and not with MG132 (proteasome inhibitor) and by overexpression of BCL-2, suggesting that caspases and BCL-2 are involved in the decrease of PTEN protein levels in A2780 cells. Conclusion The decrease in pro-apoptotic PTEN protein levels and increase in survival factor pAKT in A2780 ovarian cancer cells suggest that cisplatin treatment could further exacerbate drug resistance in A2780 ovarian cancer cells. PMID:23663432

  7. Self-organized spatiotemporal patterns of PIP3 and PTEN during spontaneous cell polarization

    NASA Astrophysics Data System (ADS)

    Knoch, Fabian; Tarantola, Marco; Rappel, Wouter-Jan; Bodenschatz, Eberhard

    2014-03-01

    During spontaneous cell polarization of Dictyostelium discoideum cells, PIP3 (phosphatidylinositol (3,4,5)-triphoshpate) and PTEN (phosphatase tensin homolog) have been identified as key signaling molecules, which govern the process of polarization in a self-organized manner. Gerisch et al. have shown that randomly triggered excitable PIP3 waves regulate the anti-correlated PTEN concentration. Here we show that this requires a switch-like dynamics of the overall membrane bound PTEN concentration in combination with two species of PTEN differing in their dephosphorylation rates. A quantitative modeling with a coupled reaction-diffusion system shows excellent agreement with experimental results and predicts a ratio σ of dephosphorylation rates acting on PIP3 of σ ~ 80 - 100. Our quantitative analysis suggests that surface-attached cell membrane spanning PIP3 waves are necessary for resetting the global actin network. This is evidenced by the experimentally observed delay between polarization-cycles also quantitatively captured by our analysis. Max Planck Society and Center for Theoretical Biological Physics.

  8. Germline mutation of the PTEN gene in a Japanese patient with Cowden's disease.

    PubMed

    Kato, N; Kimura, K; Sugawara, H; Aoyagi, S; Ikeda, T; Horii, A

    2001-05-01

    Cowden's disease (CD) is an autosomal dominant disorder which confers a high susceptibility to diverse benign and malignant tumors. The PTEN (phosphatase and tensin homologue deleted in chromosome ten) gene has been identified as a tumor suppressor gene responsible for cancers of the endometrium, ovary, prostate, and glioblastomas. Recently, germline mutations of this gene were also found in patients with CD, and it is now recognized as a gene responsible for this disease. We identified a germline nonsense mutation at codon 130 in exon 5 of PTEN in a 56-year-old Japanese woman with CD. The patient had adenoid facies and mucocutaneous lesions including multiple facial papules, acral keratoses on neck and shoulders, palmoplantar keratoses, multiple oral papillomas, scrotal tongue, mucosal and cutaneous hemangiomas, and a sclerotic fibroma on the arm. She also had benign and malignant polypoid neoplasms throughout the entire digestive tract, including adenocarcinoma of the colon and submucosal lipomas of the rectum, as well as bilateral breast carcinomas, multinodular goiters, an ovarian cyst with a fibroma-like nodule, hepatic hemangiomas, and abdominal hernia. We searched CD cases with the same genotypic PTEN mutation as the present case and compared their phenotypes. Further studies will disclose a better understanding of the role of mutation in the PTEN gene in the course of tumorigenesis of both benign and malignant tumors developed in patients with CD.

  9. Nanotherapeutics of PTEN Inhibitor with Mesoporous Silica Nanocarrier Effective for Axonal Outgrowth of Adult Neurons.

    PubMed

    Kim, Min Soo; El-Fiqi, Ahmed; Kim, Jong-Wan; Ahn, Hong-Sun; Kim, Hyukmin; Son, Young-Jin; Kim, Hae-Won; Hyun, Jung Keun

    2016-07-27

    Development of therapeutic strategies such as effective drug delivery is an urgent and yet unmet need for repair of damaged nervous systems. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) regulates axonal regrowth of central and peripheral nervous systems; its inhibition, meanwhile, facilitates axonal outgrowth of injured neurons. Here we show that nanotherapeutics based on mesoporous silica nanoparticles loading PTEN-inhibitor bisperoxovanadium (BpV) are effective for delivery of drug molecules and consequent improvement of axonal outgrowth. Mesoporous nanocarriers loaded BpV drug at large amount (27 μg per 1 mg of carrier), and released sustainably over 10 d. Nanocarrier-BpV treatment of primary neurons from the dorsal root ganglions (DRGs) of rats and mice at various concentrations induced them to actively take up the nanocomplexes with an uptake efficiency as high as 85%. The nanocomplex-administered neurons exhibited significantly enhanced axonal outgrowth compared with those treated with free-BpV drug. The expression of a series of proteins involved in PTEN inhibition and downstream signaling was substantially up-/down-regulated by the nanocarrier-BpV system. Injection of the nanocarriers into neural tissues (DRG, brain cortex, and spinal cord), moreover, demonstrated successful integration into neurons, glial cells, oligodendrocytes, and macrophages, suggesting the possible nanotherapeutics applications in vivo. Together, PTEN-inhibitor delivery via mesoporous nanocarriers can be considered a promising strategy for stimulating axonal regeneration in central and peripheral nervous systems. PMID:27386893

  10. Missense mutation in the PTEN promoter of a patient with hemifacial hyperplasia

    PubMed Central

    Yamazaki, Kiyomi; Eng, Charis; Kuznetsov, Sergei A; Reinisch, John; Yamashita, Dennis-Duke; Walker, John; Cheung, Craig; Robey, Pamela G; Yen, Stephen L-K

    2015-01-01

    The cellular mechanisms involved in the asymmetric facial overgrowth syndrome, hemifacial hyperplasia (HFH), are not well understood. This study was conducted to compare primary cell cultures from hyperplastic and normal HFH bone for cellular and molecular differences. Primary cultures developed from biopsies of a patient with isolated HFH showed a twofold difference in cell size and cell number between hyperplastic and normal bone. Microarray data suggested a 40% suppression of PTEN (phosphatase-tensin homolog) transcripts. Sequencing of the PTEN gene and promoter identified novel C/G missense mutation (position −1053) in the regulatory region of the PTEN promoter. Western blots of downstream pathway components showed an increase in PKBa/Akt1 phosphorylation and TOR (target of rapamcyin) signal. Sirolimus, an inhibitor of TOR, when added to overgrowth cells reversed the cell size, cell number and total protein differences between hyperplastic and normal cells. In cases of facial overgrowth, which involve PTEN/Akt/TOR dysregulation, sirolimus could be used for limiting cell overgrowth. PMID:26229595

  11. Roles of PTEN with DNA Repair in Parkinson’s Disease

    PubMed Central

    Ogino, Mako; Ichimura, Mayuko; Nakano, Noriko; Minami, Akari; Kitagishi, Yasuko; Matsuda, Satoru

    2016-01-01

    Oxidative stress is considered to play key roles in aging and pathogenesis of many neurodegenerative diseases such as Parkinson’s disease, which could bring DNA damage by cells. The DNA damage may lead to the cell apoptosis, which could contribute to the degeneration of neuronal tissues. Recent evidence suggests that PTEN (phosphatase and tensin homolog on chromosome 10) may be involved in the pathophysiology of the neurodegenerative disorders. Since PTEN expression appears to be one dominant determinant of the neuronal cell death, PTEN should be a potential molecular target of novel therapeutic strategies against Parkinson’s disease. In addition, defects in DNA damage response and DNA repair are often associated with modulation of hormone signaling pathways. Especially, many observations imply a role for estrogen in a regulation of the DNA repair action. In the present review, we have attempted to summarize the function of DNA repair molecules at a viewpoint of the PTEN signaling pathway and the hormone related functional modulation of cells, providing a broad interpretation on the molecular mechanisms for treatment of Parkinson’s disease. Particular attention will be paid to the mechanisms proposed to explain the health effects of food ingredients against Parkinson’s disease related to reduce oxidative stress for an efficient therapeutic intervention. PMID:27314344

  12. MAF1 suppresses AKT‐mTOR signaling and liver cancer through activation of PTEN transcription

    PubMed Central

    Li, Yue; Tsang, Chi Kwan; Wang, Suihai; Li, Xiao‐Xing; Yang, Yang; Fu, Liwu; Huang, Wenlin; Li, Ming

    2016-01-01

    The phosphatidylinositol 3‐kinase/phosphatidylinositol 3,4,5‐trisphosphate 3‐phosphatase/protein kinase B/mammalian target of rapamycin (PI3K‐PTEN‐AKT‐mTOR) pathway is a central controller of cell growth and a key driver for human cancer. MAF1 is an mTOR downstream effector and transcriptional repressor of ribosomal and transfer RNA genes. MAF1 expression is markedly reduced in hepatocellular carcinomas, which is correlated with disease progression and poor prognosis. Consistently, MAF1 displays tumor‐suppressor activity toward in vitro and in vivo cancer models. Surprisingly, blocking the synthesis of ribosomal and transfer RNAs is insufficient to account for MAF1's tumor‐suppressor function. Instead, MAF1 down‐regulation paradoxically leads to activation of AKT‐mTOR signaling, which is mediated by decreased PTEN expression. MAF1 binds to the PTEN promoter, enhancing PTEN promoter acetylation and activity. Conclusion: In contrast to its canonical function as a transcriptional repressor, MAF1 can also act as a transcriptional activator for PTEN, which is important for MAF1's tumor‐suppressor function. These results have implications in disease staging, prognostic prediction, and AKT‐mTOR‐targeted therapy in liver cancer. (Hepatology 2016;63:1928‐1942) PMID:26910647

  13. Superoxide anion radicals induce IGF-1 resistance through concomitant activation of PTP1B and PTEN.

    PubMed

    Singh, Karmveer; Maity, Pallab; Krug, Linda; Meyer, Patrick; Treiber, Nicolai; Lucas, Tanja; Basu, Abhijit; Kochanek, Stefan; Wlaschek, Meinhard; Geiger, Hartmut; Scharffetter-Kochanek, Karin

    2015-01-01

    The evolutionarily conserved IGF-1 signalling pathway is associated with longevity, metabolism, tissue homeostasis, and cancer progression. Its regulation relies on the delicate balance between activating kinases and suppressing phosphatases and is still not very well understood. We report here that IGF-1 signalling in vitro and in a murine ageing model in vivo is suppressed in response to accumulation of superoxide anions (O2∙-) in mitochondria, either by chemical inhibition of complex I or by genetic silencing of O2∙--dismutating mitochondrial Sod2. The O2∙--dependent suppression of IGF-1 signalling resulted in decreased proliferation of murine dermal fibroblasts, affected translation initiation factors and suppressed the expression of α1(I), α1(III), and α2(I) collagen, the hallmarks of skin ageing. Enhanced O2∙- led to activation of the phosphatases PTP1B and PTEN, which via dephosphorylation of the IGF-1 receptor and phosphatidylinositol 3,4,5-triphosphate dampened IGF-1 signalling. Genetic and pharmacologic inhibition of PTP1B and PTEN abrogated O2∙--induced IGF-1 resistance and rescued the ageing skin phenotype. We thus identify previously unreported signature events with O2∙-, PTP1B, and PTEN as promising targets for drug development to prevent IGF-1 resistance-related pathologies. PMID:25520316

  14. Frequent loss of PTEN expression is linked to elevated phosphorylated Akt levels, but not associated with p27 and cyclin D1 expression, in primary epithelial ovarian carcinomas.

    PubMed

    Kurose, K; Zhou, X P; Araki, T; Cannistra, S A; Maher, E R; Eng, C

    2001-06-01

    PTEN (MMAC1/TEP1), a tumor suppressor gene on chromosome subband 10q23.3, is variably mutated and/or deleted in a variety of human cancers. Germline mutations in PTEN, which encode a dual-specificity phosphatase, have been implicated in at least two hamartoma tumor syndromes that exhibit some clinical overlap, Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome. Among several series of ovarian cancers, the frequency of loss of heterozygosity (LOH) of markers flanking and within PTEN, is approximately 30 to 50%, and the somatic intragenic PTEN mutation frequency is <10%. In this study, we screened primary adenocarcinomas of the ovary for LOH of polymorphic markers within and flanking the PTEN gene and for intragenic mutations of the PTEN gene and compared them to PTEN expression using immunohistochemistry. Furthermore, we sought to detect the expression of the presumed downstream targets of PTEN, such as P-Akt, p27, and cyclin D1 by immunohistochemistry. LOH at 10q23 was observed in 29 of 64 (45%) cases. Of the 117 samples, 6 somatic intragenic PTEN mutations, 1 germline mutation, and 1 novel polymorphism were found in 7 (6%) patients. Immunostaining of 49 ovarian cancer samples revealed that 13 (27%) were PTEN immunostain-negative, 25 (51%) had reduced staining, and the rest (22%) were PTEN expression-positive. Among the 44 informative tumors assessed for 10q23 LOH and PTEN immunostaining, there was an association between 10q23 LOH and decreased or absent staining (P = 0.0317). Of note, there were five (11%) tumors with neither mutation nor deletion that exhibited no PTEN expression and 10 (25%) others without mutation or deletion but had decreased PTEN expression. Among the 49 tumors available for immunohistochemistry, 28 (57%) showed P-Akt-positive staining, 24 (49%) had decreased p27 staining, and cyclin D1 was overexpressed in 35 (79%) cases. In general, P-Akt expression was inversely correlated with PTEN expression (P = 0.0083). These data suggest that

  15. PTEN loss compromises homologous recombination repair in astrocytes: implications for GBM therapy with temozolomide or PARP inhibitors

    PubMed Central

    McEllin, Brian; Camacho, Cristel V.; Mukherjee, Bipasha; Hahm, Brandon; Tomimatsu, Nozomi; Bachoo, Robert M.; Burma, Sandeep

    2010-01-01

    Glioblastoma multiforme (GBM) are lethal brain tumors that are highly resistant to therapy. The only meaningful improvement in therapeutic response came from use of the SN1-type alkylating agent, temozolomide, in combination with ionizing radiation (IR). However, no genetic markers that might predict a better response to DNA alkylating agents have been identified in GBMs, except for loss of O6-methylguanine-DNA methyltransferase (MGMT) via promoter methylation. In this study, using genetically defined primary murine astrocytes as well as human glioma lines, we show that loss of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) confers sensitivity to N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), a functional analog of temozolomide. We find that MNNG induces replication-associated DNA double-strand breaks (DSBs) that are inefficiently repaired in PTEN-deficient astrocytes and trigger apoptosis. Mechanistically, this is because PTEN-null astrocytes are compromised in homologous recombination (HR), which is important for the repair of replication-associated DSBs. Our results suggest that reduced levels of Rad51 paralogs in PTEN-null astrocytes might underlie the HR deficiency of these cells. Importantly, the HR deficiency of PTEN-null cells renders them sensitive to the poly(ADP-ribose) polymerase (PARP) inhibitor ABT-888 due to synthetic lethality. In sum, our results tentatively suggest that patients with PTEN-null GBMs (about 36%) may especially benefit from treatment with DNA alkylating agents such as temozolomide. Significantly, our results also provide a rational basis for treating the sub-group of patients who are PTEN deficient with PARP inhibitors in addition to the current treatment regimen of radiation and temozolomide. PMID:20530668

  16. Oocyte-specific deletion of Pten causes premature activation of the primordial follicle pool.

    PubMed

    Reddy, Pradeep; Liu, Lian; Adhikari, Deepak; Jagarlamudi, Krishna; Rajareddy, Singareddy; Shen, Yan; Du, Chun; Tang, Wenli; Hämäläinen, Tuula; Peng, Stanford L; Lan, Zi-Jian; Cooney, Austin J; Huhtaniemi, Ilpo; Liu, Kui

    2008-02-01

    In the mammalian ovary, progressive activation of primordial follicles from the dormant pool serves as the source of fertilizable ova. Menopause, or the end of female reproductive life, occurs when the primordial follicle pool is exhausted. However, the molecular mechanisms underlying follicle activation are poorly understood. We provide genetic evidence that in mice lacking PTEN (phosphatase and tensin homolog deleted on chromosome 10) in oocytes, a major negative regulator of phosphatidylinositol 3-kinase (PI3K), the entire primordial follicle pool becomes activated. Subsequently, all primordial follicles become depleted in early adulthood, causing premature ovarian failure (POF). Our results show that the mammalian oocyte serves as the headquarters of programming of follicle activation and that the oocyte PTEN-PI3K pathway governs follicle activation through control of initiation of oocyte growth.

  17. Vitamin A facilitates enteric nervous system precursor migration by reducing Pten accumulation

    PubMed Central

    Fu, Ming; Sato, Yoshiharu; Lyons-Warren, Ariel; Zhang, Bin; Kane, Maureen A.; Napoli, Joseph L.; Heuckeroth, Robert O.

    2010-01-01

    Hirschsprung disease is a serious disorder of enteric nervous system (ENS) development caused by the failure of ENS precursor migration into the distal bowel. We now demonstrate that retinoic acid (RA) is crucial for GDNF-induced ENS precursor migration, cell polarization and lamellipodia formation, and that vitamin A depletion causes distal bowel aganglionosis in serum retinol-binding-protein-deficient (Rbp4–/–) mice. Ret heterozygosity increases the incidence and severity of distal bowel aganglionosis induced by vitamin A deficiency in Rbp4–/– animals. Furthermore, RA reduces phosphatase and tensin homolog (Pten) accumulation in migrating cells, whereas Pten overexpression slows ENS precursor migration. Collectively, these data support the hypothesis that vitamin A deficiency is a non-genetic risk factor that increases Hirschsprung disease penetrance and expressivity, suggesting that some cases of Hirschsprung disease might be preventable by optimizing maternal nutrition. PMID:20110328

  18. Combination of PTEN and {gamma}-Ionizing Radiation Enhances Cell Death and G{sub 2}/M Arrest Through Regulation of AKT Activity and p21 Induction in Non-Small-Cell Lung Cancer Cells

    SciTech Connect

    Park, Jong Kuk; Jung, Hae-Yun; Park, Seon Ho; Kang, Seung Yi; Yi, Mi-Rang; Um, Hong Duck; Hong, Sung Hee

    2008-04-01

    Purpose: To identify the role of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) during {gamma}-ionizing radiation ({gamma}-IR) treatment for non-small-cell lung cancer cells. Methods and Materials: Wild-type PTEN or mutant forms of PTEN plasmids were transfected to construct stable transfectants of the NCI-H1299 non-small-cell lung cancer cell line. Combined effects of PTEN expression and IR treatment were tested using immunoblot, clonogenic, and cell-counting assays. Related signaling pathways were studied with immunoblot and kinase assays. Results: At steady state, stable transfectants showed almost the same proliferation rate but had different AKT phosphorylation patterns. When treated with {gamma}-IR, wild-type PTEN transfectants showed higher levels of cell death compared with mock vector or mutant transfectants, and showed increased G{sub 2}/M cell-cycle arrest accompanied by p21 induction and CDK1 inactivation. NCI-H1299 cells were treated with phosphosinositide-3 kinase (PI3K)/AKT pathway inhibitor (LY29002), resulting in reduced AKT phosphorylation levels. Treatment of NCI-H1299 cells with LY29002 and {gamma}-IR resulted in increased cell-cycle arrest and p21 induction. Endogenous wild-type PTEN-containing NCI-H460 cells were treated with PTEN-specific siRNA and then irradiated with {gamma}-IR: however reduced PTEN levels did not induce cell-cycle arrest or p21 expression. Conclusions: Taken together, these findings indicate that PTEN may modulate cell death or the cell cycle via AKT inactivation by PTEN and {gamma}-IR treatment. We also propose that a PTEN-PI3K/AKT-p21-CDK1 pathway could regulate cell death and the cell cycle by {gamma}-IR treatment.

  19. Effect of Phosphatase and Tensin Homologue on Chromosome 10 on Angiotensin II-Mediated Proliferation, Collagen Synthesis, and Akt/P27 Signaling in Neonatal Rat Cardiac Fibroblasts

    PubMed Central

    Nie, Ling; Zhao, Jing-Hong; Wang, Jiang; Song, Rong

    2016-01-01

    Cardiac fibroblasts (CFs) play a key role in cardiac fibrosis by regulating the balance between extracellular matrix synthesis and breakdown. Although phosphatase and tensin homologue on chromosome 10 (PTEN) has been found to play an important role in cardiovascular disease, it is not clear whether PTEN is involved in functional regulation of CFs. In the present study, PTEN was overexpressed in neonatal rat CFs via recombinant adenovirus-mediated gene transfer. The effects of PTEN overexpression on cell-cycle progression and angiotensin II- (Ang II-) mediated regulation of collagen metabolism, synthesis of matrix metalloproteinases, and Akt/P27 signaling were investigated. Compared with uninfected cells and cells infected with green fluorescent protein-expressing adenovirus (Ad-GFP), cells infected with PTEN-expressing adenovirus (Ad-PTEN) significantly increased PTEN protein and mRNA levels in CFs (P < 0.05). The proportion of CFs in the G1/S cell-cycle phase was significantly higher for PTEN-overexpressing cells. In addition, Ad-PTEN decreased mRNA expression and the protein synthesis rate of collagen types I and III and antagonized Ang II-induced collagen synthesis. Overexpression of PTEN also decreased Ang II-induced matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-1 (TIMP-1) production as well as gelatinase activity. Moreover, Ad-PTEN decreased Akt expression and increased P27 expression independent of Ang II stimulation. These results suggest that PTEN could regulate its functional effects in neonatal rat CFs partially via the Akt/P27 signaling pathway. PMID:27747225

  20. Liver-Specific Deletion of Phosphatase and Tensin Homolog Deleted on Chromosome 10 Significantly Ameliorates Chronic EtOH-Induced Increases in Hepatocellular Damage

    PubMed Central

    Orlicky, David J.; McCullough, Rebecca L.; Jiang, Hua; Maclean, Kenneth N.; Mercer, Kelly E.; Stiles, Bangyan L.; Saba, Laura M.; Ronis, Martin J.; Petersen, Dennis R.

    2016-01-01

    Alcoholic liver disease is a significant contributor to global liver failure. In murine models, chronic ethanol consumption dysregulates PTEN/Akt signaling. Hepatospecific deletion of phosphatase and tensin homolog deleted on chromosome 10 (PTENLKO) mice possess constitutive activation of Akt(s) and increased de novo lipogenesis resulting in increased hepatocellular steatosis. This makes PTENLKO a viable model to examine the effects of ethanol in an environment of preexisting steatosis. The aim of this study was to determine the impact of chronic ethanol consumption and the absence of PTEN (PTENLKO) compared to Alb-Cre control mice (PTENf/f) on hepatocellular damage as evidenced by changes in lipid accumulation, protein carbonylation and alanine amino transferase (ALT). In the control PTENf/f animals, ethanol significantly increased ALT, liver triglycerides and steatosis. In contrast, chronic ethanol consumption in PTENLKO mice decreased hepatocellular damage when compared to PTENLKO pair-fed controls. Consumption of ethanol elevated protein carbonylation in PTENf/f animals but had no effect in PTENLKO animals. In PTENLKO mice, overall hepatic mRNA expression of genes that contribute to GSH homeostasis as well as reduced glutathione (GSH) and oxidized glutathione (GSSG) concentrations were significantly elevated compared to respective PTENf/f counterparts. These data indicate that during conditions of constitutive Akt activation and steatosis, increased GSH homeostasis assists in mitigation of ethanol-dependent induction of oxidative stress and hepatocellular damage. Furthermore, data herein suggest a divergence in EtOH-induced hepatocellular damage and increases in steatosis due to polyunsaturated fatty acids downstream of PTEN. PMID:27124661

  1. Liver-Specific Deletion of Phosphatase and Tensin Homolog Deleted on Chromosome 10 Significantly Ameliorates Chronic EtOH-Induced Increases in Hepatocellular Damage.

    PubMed

    Shearn, Colin T; Orlicky, David J; McCullough, Rebecca L; Jiang, Hua; Maclean, Kenneth N; Mercer, Kelly E; Stiles, Bangyan L; Saba, Laura M; Ronis, Martin J; Petersen, Dennis R

    2016-01-01

    Alcoholic liver disease is a significant contributor to global liver failure. In murine models, chronic ethanol consumption dysregulates PTEN/Akt signaling. Hepatospecific deletion of phosphatase and tensin homolog deleted on chromosome 10 (PTENLKO) mice possess constitutive activation of Akt(s) and increased de novo lipogenesis resulting in increased hepatocellular steatosis. This makes PTENLKO a viable model to examine the effects of ethanol in an environment of preexisting steatosis. The aim of this study was to determine the impact of chronic ethanol consumption and the absence of PTEN (PTENLKO) compared to Alb-Cre control mice (PTENf/f) on hepatocellular damage as evidenced by changes in lipid accumulation, protein carbonylation and alanine amino transferase (ALT). In the control PTENf/f animals, ethanol significantly increased ALT, liver triglycerides and steatosis. In contrast, chronic ethanol consumption in PTENLKO mice decreased hepatocellular damage when compared to PTENLKO pair-fed controls. Consumption of ethanol elevated protein carbonylation in PTENf/f animals but had no effect in PTENLKO animals. In PTENLKO mice, overall hepatic mRNA expression of genes that contribute to GSH homeostasis as well as reduced glutathione (GSH) and oxidized glutathione (GSSG) concentrations were significantly elevated compared to respective PTENf/f counterparts. These data indicate that during conditions of constitutive Akt activation and steatosis, increased GSH homeostasis assists in mitigation of ethanol-dependent induction of oxidative stress and hepatocellular damage. Furthermore, data herein suggest a divergence in EtOH-induced hepatocellular damage and increases in steatosis due to polyunsaturated fatty acids downstream of PTEN. PMID:27124661

  2. FOXO1/3 and PTEN Depletion in Granulosa Cells Promotes Ovarian Granulosa Cell Tumor Development.

    PubMed

    Liu, Zhilin; Ren, Yi A; Pangas, Stephanie A; Adams, Jaye; Zhou, Wei; Castrillon, Diego H; Wilhelm, Dagmar; Richards, JoAnne S

    2015-07-01

    The forkhead box (FOX), FOXO1 and FOXO3, transcription factors regulate multiple functions in mammalian cells. Selective inactivation of the Foxo1 and Foxo3 genes in murine ovarian granulosa cells severely impairs follicular development and apoptosis causing infertility, and as shown here, granulosa cell tumor (GCT) formation. Coordinate depletion of the tumor suppressor Pten gene in the Foxo1/3 strain enhanced the penetrance and onset of GCT formation. Immunostaining and Western blot analyses confirmed FOXO1 and phosphatase and tensin homolog (PTEN) depletion, maintenance of globin transcription factor (GATA) 4 and nuclear localization of FOXL2 and phosphorylated small mothers against decapentaplegic (SMAD) 2/3 in the tumor cells, recapitulating results we observed in human adult GCTs. Microarray and quantitative PCR analyses of mouse GCTs further confirmed expression of specific genes (Foxl2, Gata4, and Wnt4) controlling granulosa cell fate specification and proliferation, whereas others (Emx2, Nr0b1, Rspo1, and Wt1) were suppressed. Key genes (Amh, Bmp2, and Fshr) controlling follicle growth, apoptosis, and differentiation were also suppressed. Inhbb and Grem1 were selectively elevated, whereas reduction of Inha provided additional evidence that activin signaling and small mothers against decapentaplegic (SMAD) 2/3 phosphorylation impact GCT formation. Unexpectedly, markers of Sertoli/epithelial cells (SRY [sex determining region Y]-box 9/keratin 8) and alternatively activated macrophages (chitinase 3-like 3) were elevated in discrete subpopulations within the mouse GCTs, indicating that Foxo1/3/Pten depletion not only leads to GCTs but also to altered granulosa cell fate decisions and immune responses. Thus, analyses of the Foxo1/3/Pten mouse GCTs and human adult GCTs provide strong evidence that impaired functions of the FOXO1/3/PTEN pathways lead to dramatic changes in the molecular program within granulosa cells, chronic activin signaling in the presence of

  3. The RhoA-ROCK-PTEN pathway as a molecular switch for anchorage dependent cell behavior.

    PubMed

    Yang, Seungwon; Kim, Hyun-Man

    2012-04-01

    The proliferation of anchorage-dependent cells of mesenchymal origin requires the attachment of the cells to substrates. Thus, cells that are poorly attached to substrates exhibit retarded cell cycle progression or apoptotic death. A major disadvantage of most polymers used in tissue engineering is their hydrophobicity; hydrophobic surfaces do not allow cells to attach firmly and, therefore, do not allow normal proliferation rates. In this study, we investigated the molecular mechanism underlying the reduced proliferation rate of cells that are poorly attached to substrates. There was an inverse relationship between the activity of the small GTPase RhoA (RhoA) and the cell proliferation rate. RhoA activity correlated inversely with the strength of cell adhesion to the substrates. The high RhoA activity in the cells poorly attached to substrates caused an increase in the activity of Rho-associated kinase (ROCK), a well-known effector of RhoA that upregulated the activity of phosphatase and tensin homolog (PTEN). The resulting activated PTEN downregulated Akt activity, which is essential for cell proliferation. Thus, the cells that were poorly attached to substrates showed low levels of cell proliferation because the RhoA-ROCK-PTEN pathway was hyperactive. In addition, RhoA activity seemed to be related to focal adhesion kinase (FAK) activity. Weak FAK activity in these poorly attached cells failed to downregulate the high RhoA activity that restrained cell proliferation. Interestingly, reducing the expression of any component of the RhoA-ROCK-PTEN pathway rescued the proliferation rate without physico-chemical surface modifications. Based on these results, we suggest that the RhoA-ROCK-PTEN pathway acts as a molecular switch to control cell proliferation and determine anchorage dependence. In cells that are poorly attached to substrates, its inhibition is sufficient to restore cell proliferation without the need for physico-chemical modification of the material

  4. Pten Regulates Epithelial Cytodifferentiation during Prostate Development

    PubMed Central

    Lokody, Isabel B.; Francis, Jeffrey C.; Gardiner, Jennifer R.; Erler, Janine T.; Swain, Amanda

    2015-01-01

    Gene expression and functional studies have indicated that the molecular programmes involved in prostate development are also active in prostate cancer. PTEN has been implicated in human prostate cancer and is frequently mutated in this disease. Here, using the Nkx3.1:Cre mouse strain and a genetic deletion approach, we investigate the role of Pten specifically in the developing mouse prostate epithelia. In contrast to its role in other developing organs, this gene is dispensable for the initial developmental processes such as budding and branching. However, as cytodifferentiation progresses, abnormal luminal cells fill the ductal lumens together with augmented epithelial proliferation. This phenotype resembles the hyperplasia seen in postnatal Pten deletion models that develop neoplasia at later stages. Consistent with this, gene expression analysis showed a number of genes affected that are shared with Pten mutant prostate cancer models, including a decrease in androgen receptor regulated genes. In depth analysis of the phenotype of these mice during development revealed that loss of Pten leads to the precocious differentiation of epithelial cells towards a luminal cell fate. This study provides novel insight into the role of Pten in prostate development as part of the process of coordinating the differentiation and proliferation of cell types in time and space to form a functional organ. PMID:26076167

  5. The PTEN-regulating microRNA miR-26a is amplified in high-grade glioma and facilitates gliomagenesis in vivo

    PubMed Central

    Huse, Jason T.; Brennan, Cameron; Hambardzumyan, Dolores; Wee, Boyoung; Pena, John; Rouhanifard, Sara H.; Sohn-Lee, Cherin; le Sage, Carlos; Agami, Reuven; Tuschl, Thomas; Holland, Eric C.

    2009-01-01

    Activated oncogenic signaling is central to the development of nearly all forms of cancer, including the most common class of primary brain tumor, glioma. Research over the last two decades has revealed the particular importance of the Akt pathway, and its molecular antagonist PTEN (phosphatase and tensin homolog), in the process of gliomagenesis. Recent studies have also demonstrated that microRNAs (miRNAs) may be responsible for the modulation of cancer-implicated genes in tumors. Here we report the identification miR-26a as a direct regulator of PTEN expression. We also show that miR-26a is frequently amplified at the DNA level in human glioma, most often in association with monoallelic PTEN loss. Finally, we demonstrate that miR-26a-mediated PTEN repression in a murine glioma model both enhances de novo tumor formation and precludes loss of heterozygosity and the PTEN locus. Our results document a new epigenetic mechanism for PTEN regulation in glioma and further highlight dysregulation of Akt signaling as crucial to the development of these tumors. PMID:19487573

  6. The relevance of PTEN-AKT in relation to NOTCH1-directed treatment strategies in T-cell acute lymphoblastic leukemia.

    PubMed

    Mendes, Rui D; Canté-Barrett, Kirsten; Pieters, Rob; Meijerink, Jules P P

    2016-09-01

    The tumor suppressor phosphatase and tensin homolog (PTEN) negatively regulates phosphatidylinositol 3-kinase (PI3K)-AKT signaling and is often inactivated by mutations (including deletions) in a variety of cancer types, including T-cell acute lymphoblastic leukemia. Here we review mutation-associated mechanisms that inactivate PTEN together with other molecular mechanisms that activate AKT and contribute to T-cell leukemogenesis. In addition, we discuss how Pten mutations in mouse models affect the efficacy of gamma-secretase inhibitors to block NOTCH1 signaling through activation of AKT. Based on these models and on observations in primary diagnostic samples from patients with T-cell acute lymphoblastic leukemia, we speculate that PTEN-deficient cells employ an intrinsic homeostatic mechanism in which PI3K-AKT signaling is dampened over time. As a result of this reduced PI3K-AKT signaling, the level of AKT activation may be insufficient to compensate for NOTCH1 inhibition, resulting in responsiveness to gamma-secretase inhibitors. On the other hand, de novo acquired PTEN-inactivating events in NOTCH1-dependent leukemia could result in temporary, strong activation of PI3K-AKT signaling, increased glycolysis and glutaminolysis, and consequently gamma-secretase inhibitor resistance. Due to the central role of PTEN-AKT signaling and in the resistance to NOTCH1 inhibition, AKT inhibitors may be a promising addition to current treatment protocols for T-cell acute lymphoblastic leukemia. PMID:27582570

  7. The relevance of PTEN-AKT in relation to NOTCH1-directed treatment strategies in T-cell acute lymphoblastic leukemia

    PubMed Central

    Mendes, Rui D.; Canté-Barrett, Kirsten; Pieters, Rob; Meijerink, Jules P.P.

    2016-01-01

    The tumor suppressor phosphatase and tensin homolog (PTEN) negatively regulates phosphatidylinositol 3-kinase (PI3K)-AKT signaling and is often inactivated by mutations (including deletions) in a variety of cancer types, including T-cell acute lymphoblastic leukemia. Here we review mutation-associated mechanisms that inactivate PTEN together with other molecular mechanisms that activate AKT and contribute to T-cell leukemogenesis. In addition, we discuss how Pten mutations in mouse models affect the efficacy of gamma-secretase inhibitors to block NOTCH1 signaling through activation of AKT. Based on these models and on observations in primary diagnostic samples from patients with T-cell acute lymphoblastic leukemia, we speculate that PTEN-deficient cells employ an intrinsic homeostatic mechanism in which PI3K-AKT signaling is dampened over time. As a result of this reduced PI3K-AKT signaling, the level of AKT activation may be insufficient to compensate for NOTCH1 inhibition, resulting in responsiveness to gamma-secretase inhibitors. On the other hand, de novo acquired PTEN-inactivating events in NOTCH1-dependent leukemia could result in temporary, strong activation of PI3K-AKT signaling, increased glycolysis and glutaminolysis, and consequently gamma-secretase inhibitor resistance. Due to the central role of PTEN-AKT signaling and in the resistance to NOTCH1 inhibition, AKT inhibitors may be a promising addition to current treatment protocols for T-cell acute lymphoblastic leukemia. PMID:27582570

  8. Phosphatase and tensin homolog reconstruction and vascular endothelial growth factor knockdown synergistically inhibit the growth of glioblastoma.

    PubMed

    Chen, Hongbo; Shen, Xiaomeng; Guo, Caiping; Zhu, Huijun; Zhou, Lanzhen; Zhu, Yongqiang; Wang, Huixia; Zheng, Yi; Huang, Laiqiang

    2010-12-01

    Glioblastoma (GBM) is a highly malignant tumor with poor prognosis. Two hallmarks of this disease are a high expression of vascular endothelial growth factor (VEGF) and a depletion of the phosphatase and tensin homolog (PTEN). In the present study, combined gene therapy using wild-type PTEN reconstruction and VEGF siRNA was examined for its effectiveness in inhibiting tumor growth and tumorigenicity of PTEN-null GBM cells. In U251 GBM cells, PTEN restoration reduced proliferation, arrested the cell cycle at G0/G1 stage, and promoted apoptosis via inhibition of PIK/AKT signaling pathway. Unexpectedly, anchorage-dependent and -independent colony formation ability and the capacity for wound-healing migration of U251 cells with stable expression of VEGF siRNA were significantly inhibited, suggesting that VEGF also appeared to function as an autocrine growth factor in addition to its well-known pro-angiogenic paracrine function. Further, a combined treatment of PTEN restoration and VEGF siRNA had the best tumor suppression effect. In a xenograft study in null mice, both the restoration of PTEN and the expression of VEGF siRNA could significantly inhibit the growth of U251 GBMs, whereas tumor growth was entirely suppressed by a combination of the two treatments. Therefore, the combination of PTEN expression and VEGF knockdown represents an effective gene therapy strategy for malignant gliomas.

  9. Role of PTEN in TNFα induced insulin resistance

    SciTech Connect

    Bulger, David A.; Conley, Jermaine; Conner, Spencer H.; Majumdar, Gipsy; Solomon, Solomon S.

    2015-06-05

    Aims/hypothesis: PTEN may play a reversible role in TNFα induced insulin resistance, which has been linked to obesity-associated insulin resistance (IR). Methods: Western blots for PTEN and p-Akt were performed on H-411E liver cells incubated with insulin, TNFα, and in selected experiments VO-OHpic vanadium complex in the presence and absence of PTEN siRNA. Total PTEN was compared to β-actin loading control and p-Akt was compared to total Akt. Results: Western blot and Real Time RT-PCR experiments showed increased PTEN after TNFα treatment (p = 0.04); slightly decreased PTEN after insulin treatment; and slightly increased PTEN after insulin + TNFα treatment. PTEN siRNA markedly inhibited the TNFα-induced increase in PTEN (p < 0.01) without significantly changing the p-Akt levels. The vanadium complex, exhibiting insulin-like effects, also significantly prevented the TNFα-induced increase in PTEN. Combining insulin and VO-OHpic was additive, providing both proof of concept and insight into mechanism. Discussion: The PTEN increase due to TNFα treatment was reversible by both PTEN siRNA knockdown and VO-OHpic treatment. Thus, PTEN is identified as a potential new therapeutic target for reducing IR in Type 2 DM. - Highlights: • TNFα treatment induced a significant increase in PTEN in H-411E liver cells. • PTEN siRNA knockdown prevented this effect. • VO-OHpic (vanadium complex) treatment, like insulin, decreased PTEN protein levels. • Thus, PTEN is identified as a potential therapeutic target in DM Type 2.

  10. Role of PTEN in TNF Induced Insulin Resistance

    PubMed Central

    Bulger, David A; Conley, Jermaine; Conner, Spencer H; Majumdar, Gipsy; Solomon, Solomon S

    2015-01-01

    Aims/hypothesis PTEN may play a reversible role in TNFα induced insulin resistance, which has been linked to obesity-associated insulin resistance (IR). Methods Western blots for PTEN and p-Akt were performed on H-411E liver cells incubated with insulin, TNFα, and in selected experiments VO-OHpic vanadium complex in the presence and absence of PTEN siRNA. Total PTEN was compared to β-actin loading control and p-Akt was compared to total Akt. Results Western blot and Real Time RT-PCR experiments showed increased PTEN after TNFα treatment (p = 0.04); slightly decreased PTEN after insulin treatment; and slightly increased PTEN after insulin + TNFα treatment. PTEN siRNA markedly inhibited the TNFα-induced increase in PTEN (p < 0.01) without significantly changing the p-Akt levels. The vanadium complex, exhibiting insulin-like effects, also significantly prevented the TNFα-induced increase in PTEN. Combining insulin and VO-OHpic was additive, providing both proof of concept and insight into mechanism. Discussion The PTEN increase due to TNFα treatment was reversible by both PTEN siRNA knockdown and VO-OHpic treatment. Thus, PTEN is identified as a potential new therapeutic target for reducing IR in Type 2 DM. PMID:25918024

  11. MicroRNA-21 promotes phosphatase gene and protein kinase B/phosphatidylinositol 3-kinase expression in colorectal cancer

    PubMed Central

    Sheng, Wei-Zhong; Chen, Yu-Sheng; Tu, Chuan-Tao; He, Juan; Zhang, Bo; Gao, Wei-Dong

    2016-01-01

    AIM: To explore the regulatory mechanism of the target gene of microRNA-21 (miR-21), phosphatase gene (PTEN), and its downstream proteins, protein kinase B (AKT) and phosphatidylinositol 3-kinase (PI3K), in colorectal cancer (CRC) cells. METHODS: Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expression levels of miR-21 and PTEN in HCT116, HT29, Colo32 and SW480 CRC cell lines. Also, the expression levels of PTEN mRNA and its downstream proteins AKT and PI3K in HCT116 cells after downregulating miR-21 were investigated. RESULTS: Comparing the miR-21 expression in CRC cells, the expression levels of miR-21 were highest in HCT116 cells, and the expression levels of miR-21 were lowest in SW480 cells. In comparing miR-21 and PTEN expression in CRC cells, we found that the protein expression levels of miR-21 and PTEN were inversely correlated (P < 0.05); when miR-21 expression was reduced, mRNA expression levels of PTEN did not significantly change (P > 0.05), but the expression levels of its protein significantly increased (P < 0.05). In comparing the levels of PTEN protein and downstream AKT and PI3K in HCT116 cells after downregulation of miR-21 expression, the levels of AKT and PI3K protein expression significantly decreased (P < 0.05). CONCLUSION: PTEN is one of the direct target genes of miR-21. Thus, phosphatase gene and its downstream AKT and PI3K expression levels can be regulated by regulating the expression levels of miR-21, which in turn regulates the development of CRC. PMID:27350731

  12. Variable laterality of corticospinal tract axons that regenerate after spinal cord injury as a result of PTEN deletion or knock-down.

    PubMed

    Willenberg, Rafer; Zukor, Katherine; Liu, Kai; He, Zhigang; Steward, Oswald

    2016-09-01

    Corticospinal tract (CST) axons from one hemisphere normally extend and terminate predominantly in the contralateral spinal cord. We previously showed that deleting the gene phosphatase and tensin homolog (PTEN) in the sensorimotor cortex enables CST axons to regenerate after spinal cord injury and that some regenerating axons extend along the "wrong" side. Here, we characterize the degree of specificity of regrowth in terms of laterality. PTEN was selectively deleted via cortical adeno-associated virus (AAV)-Cre injections in neonatal PTEN-floxed mice. As adults, mice received dorsal hemisection injuries at T12 or complete crush injuries at T9. CST axons from one hemisphere were traced by unilateral biotinylated dextran amine (BDA) injections in PTEN-deleted mice with spinal cord injury and in noninjured PTEN-floxed mice that had not received AAV-Cre. In noninjured mice, 97.9 ± 0.7% of BDA-labeled axons in white matter and 88.5 ± 1.0% of BDA-labeled axons in gray matter were contralateral to the cortex of origin. In contrast, laterality of CST axons that extended past a lesion due to PTEN deletion varied across animals. In some cases, regenerated axons extended predominantly on the ipsilateral side; in other cases, axons extended predominantly contralaterally, and in others, axons were similar in numbers on both sides. Similar results were seen in analyses of cases from previous studies using short hairpin (sh)RNA-mediated PTEN knock-down. These results indicate that CST axons that extend past a lesion due to PTEN deletion or knock-down do not maintain the contralateral rule of the noninjured CST, highlighting one aspect of how the resultant circuitry from regenerating axons may differ from that of the uninjured CST. J. Comp. Neurol. 524:2654-2676, 2016. © 2016 Wiley Periodicals, Inc.

  13. PTEN permits acute increases in D3-phosphoinositide levels following TCR stimulation but inhibits distal signaling events by reducing the basal activity of Akt.

    PubMed

    Seminario, Maria-Cristina; Precht, Patricia; Bunnell, Stephen C; Warren, Sarah E; Morris, Christa M; Taub, Dennis; Wange, Ronald L

    2004-11-01

    Phosphoinositide 3-kinase (PI3K) is important in TCR signaling. PI3K generates phosphatidylinositol 3, 4, 5-trisphosphate (PI-3,4,5-P3), which regulates membrane localization and/or activity of multiple signaling proteins. PTEN (phosphatase and tensin homologue deleted on chromosome 10) opposes PI3K, reversing this reaction. Maintaining the balance between these two enzymes is important for normal T cell function. Here we use the PTEN-null Jurkat T cell line to address the role of PTEN in modulating proximal and distal TCR-signaling events. PTEN expression at levels that restored low basal Akt phosphorylation (an indicator of PI-3,4,5-P3 levels), but which were not themselves cytotoxic, had minimal effect on TCR-stimulated activation of phospholipase Cgamma1 and Ca2+ flux, but reduced the duration of extracellular signal-regulated kinase (Erk) activation. Distal signaling events, including nuclear factor of activated T cells (NFAT) activation, CD69 expression and IL-2 production, were all inhibited by PTEN expression. Notably, PTEN did not block TCR-stimulated PI-3,4,5-P3 accumulation. The effect of PTEN on distal TCR signaling events was strongly correlated with the loss of the constitutive Akt activation and glycogen synthase kinase-3 (GSK3) inhibition that is typical of Jurkat cells, and could be reversed by expression of activated Akt or pharmacologic inhibition of GSK3. These results suggest that PTEN acts in T cells primarily to control basal PI-3,4,5-P3 levels, rather than opposing PI3K acutely during TCR stimulation.

  14. Subtle variations in Pten dose determine cancer susceptibility.

    PubMed

    Alimonti, Andrea; Carracedo, Arkaitz; Clohessy, John G; Trotman, Lloyd C; Nardella, Caterina; Egia, Ainara; Salmena, Leonardo; Sampieri, Katia; Haveman, William J; Brogi, Edi; Richardson, Andrea L; Zhang, Jiangwen; Pandolfi, Pier Paolo

    2010-05-01

    Cancer susceptibility has been attributed to at least one heterozygous genetic alteration in a tumor suppressor gene (TSG). It has been hypothesized that subtle variations in TSG expression can promote cancer development. However, this hypothesis has not yet been definitively supported in vivo. Pten is a TSG frequently lost in human cancer and mutated in inherited cancer-predisposition syndromes. Here we analyze Pten hypermorphic mice (Pten(hy/+)), expressing 80% normal levels of Pten. Pten(hy/+) mice develop a spectrum of tumors, with breast tumors occurring at the highest penetrance. All breast tumors analyzed here retained two intact copies of Pten and maintained Pten levels above heterozygosity. Notably, subtle downregulation of Pten altered the steady-state biology of the mammary tissues and the expression profiles of genes involved in cancer cell proliferation. We present an alterative working model for cancer development in which subtle reductions in the dose of TSGs predispose to tumorigenesis in a tissue-specific manner.

  15. The Safe Use of a PTEN Inhibitor for the Activation of Dormant Mouse Primordial Follicles and Generation of Fertilizable Eggs

    PubMed Central

    Adhikari, Deepak; Gorre, Nagaraju; Risal, Sanjiv; Zhao, Zhiyi; Zhang, Hua; Shen, Yan; Liu, Kui

    2012-01-01

    Background Primordial ovarian follicles, which are often present in the ovaries of premature ovarian failure (POF) patients or are cryopreserved from the ovaries of young cancer patients who are undergoing gonadotoxic anticancer therapies, cannot be used to generate mature oocytes for in vitro fertilization (IVF). There has been very little success in triggering growth of primordial follicles to obtain fertilizable oocytes due to the poor understanding of the biology of primordial follicle activation. Methodology/Principal Findings We have recently reported that PTEN (phosphatase and tensin homolog deleted on chromosome ten) prevents primordial follicle activation in mice, and deletion of Pten from the oocytes of primordial follicles leads to follicular activation. Consequently, the PTEN inhibitor has been successfully used in vitro to activate primordial follicles in both mouse and human ovaries. These results suggest that PTEN inhibitors could be used in ovarian culture medium to trigger the activation of primordial follicle. To study the safety and efficacy of the use of such inhibitors, we activated primordial follicles from neonatal mouse ovaries by transient treatment with a PTEN inhibitor bpV(HOpic). These ovaries were then transplanted under the kidney capsules of recipient mice to generate mature oocytes. The mature oocytes were fertilized in vitro and progeny mice were obtained after embryo transfer. Results and Conclusions Long-term monitoring up to the second generation of progeny mice showed that the mice were reproductively active and were free from any overt signs or symptoms of chronic illnesses. Our results indicate that the use of PTEN inhibitors could be a safe and effective way of generating mature human oocytes for use in novel IVF techniques. PMID:22761722

  16. Altered PTEN, ATRX, CHGA, CHGB, and TP53 expression are associated with aggressive VHL-associated pancreatic neuroendocrine tumors.

    PubMed

    Weisbrod, Allison B; Zhang, Lisa; Jain, Meenu; Barak, Stephanie; Quezado, Martha M; Kebebew, Electron

    2013-06-01

    Von Hippel-Lindau (VHL) syndrome is an inherited cancer syndrome in which 8-17 % of germline mutation carriers develop pancreatic neuroendocrine tumors (PNETs). There is limited data on prognostic markers for PNETs other than Ki-67, which is included in the World Health Organization classification system. Recently, specific genes and pathways have been identified by whole exome sequencing which may be involved in the tumorigenesis of PNETs and may be markers of disease aggressiveness. The objective of this study was to identify molecular markers of aggressive disease in VHL-associated PNETs. The protein expression of eight genes (PTEN, CHGA, CHGB, ATRX, DAXX, CC-3, VEGF, and TP53) was analyzed in PNETs by immunohistochemistry and compared to clinical data, VHL genotype, functional imaging results, and pathologic findings. Subcellular distribution of phosphatase and tensin (PTEN), chromogranin A (CHGA), and alpha thalassemia/mental retardation syndrome X-linked (ATRX) were significantly different by WHO classifications (p ≤ 0.05). There was decreased PTEN nuclear to cytoplasmic ratio (p < 0.01) and decreased CHGA nuclear expression (p = 0.03) in malignant samples as compared to benign. Lower cytoplasmic chromogranin B (CHGB) expression (p = 0.03) was associated with malignant tumors and metastasis. Higher nuclear expression of PTEN was associated with VHL mutations in exon 3 (p = 0.04). Higher PTEN and CHGB expression was associated with higher FDG-PET avidity (p < 0.05). Cytoplasmic expression of CC-3 was associated with higher serum chromogranin A levels (ρ = 0.72, p = 0.02). Lastly, greater cytoplasmic expression of p53 was associated with metastasis. Our findings suggest that altered PTEN, ATRX, CHGA, and CHGB expression are associated with aggressive PNET phenotype in VHL and may serve as useful adjunct prognostic markers to Ki-67 in PNETs.

  17. Klf5 Deletion Promotes Pten Deletion–Initiated Luminal-Type Mouse Prostate Tumors through Multiple Oncogenic Signaling Pathways12

    PubMed Central

    Xing, Changsheng; Ci, Xinpei; Sun, Xiaodong; Fu, Xiaoying; Zhang, Zhiqian; Dong, Eric N.; Hao, Zhao-Zhe; Dong, Jin-Tang

    2014-01-01

    Krüppel-like factor 5 (KLF5) regulates multiple biologic processes. Its function in tumorigenesis appears contradictory though, showing both tumor suppressor and tumor promoting activities. In this study, we examined whether and how Klf5 functions in prostatic tumorigenesis using mice with prostate-specific deletion of Klf5 and phosphatase and tensin homolog (Pten), both of which are frequently inactivated in human prostate cancer. Histologic analysis demonstrated that when one Pten allele was deleted, which causes mouse prostatic intraepithelial neoplasia (mPIN), Klf5 deletion accelerated the emergence and progression of mPIN. When both Pten alleles were deleted, which causes prostate cancer, Klf5 deletion promoted tumor growth, increased cell proliferation, and caused more severe morphologic and molecular alterations. Homozygous deletion of Klf5 was more effective than hemizygous deletion. Unexpectedly, while Pten deletion alone expanded basal cell population in a tumor as reported, Klf5 deletion in the Pten-null background clearly reduced basal cell population while expanding luminal cell population. Global gene expression profiling, pathway analysis, and experimental validation indicate that multiple mechanisms could mediate the tumor-promoting effect of Klf5 deletion, including the up-regulation of epidermal growth factor and its downstream signaling molecules AKT and ERK and the inactivation of the p15 cell cycle inhibitor. KLF5 also appears to cooperate with several transcription factors, including CREB1, Sp1, Myc, ER and AR, to regulate gene expression. These findings validate the tumor suppressor function of KLF5. They also yield a mouse model that shares two common genetic alterations with human prostate cancer—mutation/deletion of Pten and deletion of Klf5. PMID:25425963

  18. Somatic mutation of PTEN in bladder carcinoma

    PubMed Central

    Aveyard, J S; Skilleter, A; Habuchi, T; Knowles, M A

    1999-01-01

    The tumour suppressor gene PTEN/MMAC1, which is mutated or homozygously deleted in glioma, breast and prostate cancer, is mapped to a region of 10q which shows loss of heterozygosity (LOH) in bladder cancer. We screened 123 bladder tumours for LOH in the region of PTEN. In 53 informative muscle invasive tumours (≥ pT2), allele loss was detected in 13 (24.5%) and allelic imbalance in four tumours (overall frequency 32%). LOH was found in four of 60 (6.6%) informative, non-invasive tumours (pTa/pT1). We screened 63 muscle invasive tumours for PTEN mutations by single-strand conformation polymorphism (SSCP) analysis and for homozygous deletion by duplex quantitative polymerase chain reaction (PCR). Two homozygous deletions were identified but no mutations. Of 15 bladder tumour cell lines analysed, three showed homozygous deletion of all or part of the PTEN gene, but none had mutations detectable by SSCP analysis. Our results indicate that PTEN is involved in the development of some bladder tumours. The low frequency of mutation of the retained allele in tumours with 10q23 LOH suggests that there may be another predominant mechanism of inactivation of the second allele, for example small intragenic deletions, that hemizygosity may be sufficient for phenotypic effect, or that there is another target gene at 10q23. © 1999 Cancer Research Campaign PMID:10360673

  19. PTEN methylation involved in benzene-induced hematotoxicity.

    PubMed

    Yang, Jing; Zuo, Xin; Bai, Wenlin; Niu, Piye; Tian, Lin; Gao, Ai

    2014-06-01

    It is well known that benzene is a hematotoxic carcinogen. PTEN promoter methylation is a representative example of transcriptional silencing of tumor suppressor genes. However, the effect of PTEN methylation on benzene-induced hematotoxicity has not yet been elucidated. In this study, the animal model of benzene hematotoxicity was successfully established. WBC significantly decreased in experimental groups (P < 0.01). Compared with the control group, the weight of rats increased slowly and even declined with increasing doses of benzene in the benzene-treated groups. An increase in the level of PTEN methylation was observed in the low dose group, and PTEN methylation level increased significantly in a dose-dependent manner. However, it was interesting that PTEN mRNA expression increased in the low dose group, but declined with increasing doses of benzene. The decrease of tumor suppressor function caused by PTEN methylation may be an important mechanism of benzene hematotoxicity. Furthermore, lymphoblast cell line F32 was incubated by benzene and then treated with 5-aza and TSA, alone or in combination. A dramatic decrease in the PTEN mRNA expression and a significant increase of PTEN methylation level in benzene-treated cells were also shown. PTEN mRNA expression was up regulated and PTEN methylation level was reduced by the epigenetic inhibitors, 5-aza and TSA. In conclusion, PTEN methylation is involved in benzene-induced hematotoxicity through suppressing PTEN mRNA expression.

  20. ALP (Alkaline Phosphatase) Test

    MedlinePlus

    ... known as: ALK PHOS; Alkp Formal name: Alkaline Phosphatase Related tests: AST ; ALT ; GGT ; Bilirubin ; Liver Panel ; Bone Markers ; Alkaline Phosphatase Isoenzymes; Bone Specific ALP All content on Lab ...

  1. IRS2 and PTEN are key molecules in controlling insulin sensitivity in podocytes.

    PubMed

    Santamaria, Beatriz; Marquez, Eva; Lay, Abigail; Carew, RoseaMarie M; González-Rodríguez, Águeda; Welsh, Gavin I; Ni, Lan; Hale, Lorna J; Ortiz, Alberto; Saleem, Moin A; Brazil, Derek P; Coward, Richard J; Valverde, Ángela M

    2015-12-01

    Insulin signaling to the glomerular podocyte is important for normal kidney function and is implicated in the pathogenesis of diabetic nephropathy (DN). This study determined the role of the insulin receptor substrate 2 (IRS2) in this system. Conditionally immortalized murine podocytes were generated from wild-type (WT) and insulin receptor substrate 2-deficient mice (Irs2(-/-)). Insulin signaling, glucose transport, cellular motility and cytoskeleton rearrangement were then analyzed. Within the glomerulus IRS2 is enriched in the podocyte and is preferentially phosphorylated by insulin in comparison to IRS1. Irs2(-/-) podocytes are significantly insulin resistant in respect to AKT signaling, insulin-stimulated GLUT4-mediated glucose uptake, filamentous actin (F-actin) cytoskeleton remodeling and cell motility. Mechanistically, we discovered that Irs2 deficiency causes insulin resistance through up-regulation of the phosphatase and tensin homolog (PTEN). Importantly, suppressing PTEN in Irs2(-/-) podocytes rescued insulin sensitivity. In conclusion, this study has identified for the first time IRS2 as a critical molecule for sensitizing the podocyte to insulin actions through its ability to modulate PTEN expression. This finding reveals two potential molecular targets in the podocyte for modulating insulin sensitivity and treating DN.

  2. The Membrane and Lipids as Integral Participants in Signal Transduction: Lipid Signal Transduction for the Non-Lipid Biochemist

    ERIC Educational Resources Information Center

    Eyster, Kathleen M.

    2007-01-01

    Reviews of signal transduction have often focused on the cascades of protein kinases and protein phosphatases and their cytoplasmic substrates that become activated in response to extracellular signals. Lipids, lipid kinases, and lipid phosphatases have not received the same amount of attention as proteins in studies of signal transduction.…

  3. Crystal Structure of Phosphatidylglycerophosphatase (PGPase), a Putative Membrane-Bound Lipid Phosphatase, Reveals a Novel Binuclear Metal Binding Site and Two Proton Wires

    SciTech Connect

    Kumaran,D.; Bonnano, J.; Burley, S.; Swaminathan, S.

    2006-01-01

    Phosphatidylglycerophosphatase (PGPase), an enzyme involved in lipid metabolism, catalyzes formation of phosphatidylglycerol from phosphatidylglycerophosphate. Phosphatidylglycerol is a multifunctional phospholipid, found in the biological membranes of many organisms. Here, we report the crystal structure of Listeria monocytogenes PGPase at 1.8 Angstroms resolution. PGPase, an all-helical molecule, forms a homotetramer. Each protomer contains an independent active site with two metal ions, Ca{sup 2+} and Mg{sup 2+}, forming a hetero-binuclear center located in a hydrophilic cavity near the surface of the molecule. The binuclear center, conserved ligands, metal-bound water molecules, and an Asp-His dyad form the active site. The catalytic mechanism of this enzyme is likely to proceed via binuclear metal activated nucleophilic water. The binuclear metal-binding active-site environment of this structure should provide insights into substrate binding and metal-dependent catalysis. A long channel with inter-linked linear water chains, termed 'proton wires', is observed at the tetramer interface. Comparison of similar water chain structures in photosynthetic reaction centers (RCs), Cytochrome f, gramicidin, and bacteriorhodopsin, suggests that PGPase may conduct protons via proton wires.

  4. Redox signaling via oxidative inactivation of PTEN modulates pressure-dependent myogenic tone in rat middle cerebral arteries.

    PubMed

    Gebremedhin, Debebe; Terashvili, Maia; Wickramasekera, Nadi; Zhang, David X; Rau, Nicole; Miura, Hiroto; Harder, David R

    2013-01-01

    The present study examined the level of generation of reactive oxygen species (ROS) and roles of inactivation of the phosphatase PTEN and the PI3K/Akt signaling pathway in response to an increase in intramural pressure-induced myogenic cerebral arterial constriction. Step increases in intraluminal pressure of cannulated cerebral arteries induced myogenic constriction and concomitant formation of superoxide (O2 (.-)) and its dismutation product hydrogen peroxide (H2O2) as determined by fluorescent HPLC analysis, microscopic analysis of intensity of dihydroethidium fluorescence and attenuation of pressure-induced myogenic constriction by pretreatment with the ROS scavenger 4,hydroxyl-2,2,6,6-tetramethylpiperidine1-oxyl (tempol) or Mito-tempol or MitoQ in the presence or absence of PEG-catalase. An increase in intraluminal pressure induced oxidation of PTEN and activation of Akt. Pharmacological inhibition of endogenous PTEN activity potentiated pressure-dependent myogenic constriction and caused a reduction in NPo of a 238 pS arterial KCa channel current and an increase in [Ca(2+)]i level in freshly isolated cerebral arterial muscle cells (CAMCs), responses that were attenuated by Inhibition of the PI3K/Akt pathway. These findings demonstrate an increase in intraluminal pressure induced increase in ROS production triggered redox-sensitive signaling mechanism emanating from the cross-talk between oxidative inactivation of PTEN and activation of the PI3K/Akt signaling pathway that involves in the regulation of pressure-dependent myogenic cerebral arterial constriction.

  5. Early Behavioral Abnormalities and Perinatal Alterations of PTEN/AKT Pathway in Valproic Acid Autism Model Mice.

    PubMed

    Yang, Eun-Jeong; Ahn, Sangzin; Lee, Kihwan; Mahmood, Usman; Kim, Hye-Sun

    2016-01-01

    Exposure to valproic acid (VPA) during pregnancy has been linked with increased incidence of autism, and has repeatedly been demonstrated as a useful autism mouse model. We examined the early behavioral and anatomical changes as well as molecular changes in mice prenatally exposed to VPA (VPA mice). In this study, we first showed that VPA mice showed developmental delays as assessed with self-righting, eye opening tests and impaired social recognition. In addition, we provide the first evidence that primary cultured neurons from VPA-treated embryos present an increase in dendritic spines, compared with those from control mice. Mutations in phosphatase and tensin homolog (PTEN) gene are also known to be associated with autism, and mice with PTEN knockout show autistic characteristics. Protein expression of PTEN was decreased and the ratio of p-AKT/AKT was increased in the cerebral cortex and the hippocampus, and a distinctive anatomical change in the CA1 region of the hippocampus was observed. Taken together, our study suggests that prenatal exposure to VPA induces developmental delays and neuroanatomical changes via the reduction of PTEN level and these changes were detectable in the early days of life.

  6. Early Behavioral Abnormalities and Perinatal Alterations of PTEN/AKT Pathway in Valproic Acid Autism Model Mice

    PubMed Central

    Yang, Eun-Jeong; Ahn, Sangzin; Lee, Kihwan; Mahmood, Usman; Kim, Hye-Sun

    2016-01-01

    Exposure to valproic acid (VPA) during pregnancy has been linked with increased incidence of autism, and has repeatedly been demonstrated as a useful autism mouse model. We examined the early behavioral and anatomical changes as well as molecular changes in mice prenatally exposed to VPA (VPA mice). In this study, we first showed that VPA mice showed developmental delays as assessed with self-righting, eye opening tests and impaired social recognition. In addition, we provide the first evidence that primary cultured neurons from VPA-treated embryos present an increase in dendritic spines, compared with those from control mice. Mutations in phosphatase and tensin homolog (PTEN) gene are also known to be associated with autism, and mice with PTEN knockout show autistic characteristics. Protein expression of PTEN was decreased and the ratio of p-AKT/AKT was increased in the cerebral cortex and the hippocampus, and a distinctive anatomical change in the CA1 region of the hippocampus was observed. Taken together, our study suggests that prenatal exposure to VPA induces developmental delays and neuroanatomical changes via the reduction of PTEN level and these changes were detectable in the early days of life. PMID:27071011

  7. MicroRNA-22 promotes cell survival upon UV radiation by repressing PTEN

    SciTech Connect

    Tan, Guangyun; Shi, Yuling; Wu, Zhao-Hui

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer miR-22 is induced in cells treated with UV radiation. Black-Right-Pointing-Pointer ATM is required for miR-22 induction in response to UV. Black-Right-Pointing-Pointer miR-22 targets 3 Prime -UTR of PTEN to repress its expression in UV-treated cells. Black-Right-Pointing-Pointer Upregulated miR-22 inhibits apoptosis in cells exposed to UV. -- Abstract: DNA damage response upon UV radiation involves a complex network of cellular events required for maintaining the homeostasis and restoring genomic stability of the cells. As a new class of players involved in DNA damage response, the regulation and function of microRNAs in response to UV remain poorly understood. Here we show that UV radiation induces a significant increase of miR-22 expression, which appears to be dependent on the activation of DNA damage responding kinase ATM (ataxia telangiectasia mutated). Increased miR-22 expression may result from enhanced miR-22 maturation in cells exposed to UV. We further found that tumor suppressor gene phosphatase and tensin homolog (PTEN) expression was inversely correlated with miR-22 induction and UV-induced PTEN repression was attenuated by overexpression of a miR-22 inhibitor. Moreover, increased miR-22 expression significantly inhibited the activation of caspase signaling cascade, leading to enhanced cell survival upon UV radiation. Collectively, these results indicate that miR-22 is an important player in the cellular stress response upon UV radiation, which may promote cell survival via the repression of PTEN expression.

  8. PTEN regulates RPA1 and protects DNA replication forks.

    PubMed

    Wang, Guangxi; Li, Yang; Wang, Pan; Liang, Hui; Cui, Ming; Zhu, Minglu; Guo, Limei; Su, Qian; Sun, Yujie; McNutt, Michael A; Yin, Yuxin

    2015-11-01

    Tumor suppressor PTEN regulates cellular activities and controls genome stability through multiple mechanisms. In this study, we report that PTEN is necessary for the protection of DNA replication forks against replication stress. We show that deletion of PTEN leads to replication fork collapse and chromosomal instability upon fork stalling following nucleotide depletion induced by hydroxyurea. PTEN is physically associated with replication protein A 1 (RPA1) via the RPA1 C-terminal domain. STORM and iPOND reveal that PTEN is localized at replication sites and promotes RPA1 accumulation on replication forks. PTEN recruits the deubiquitinase OTUB1 to mediate RPA1 deubiquitination. RPA1 deletion confers a phenotype like that observed in PTEN knockout cells with stalling of replication forks. Expression of PTEN and RPA1 shows strong correlation in colorectal cancer. Heterozygous disruption of RPA1 promotes tumorigenesis in mice. These results demonstrate that PTEN is essential for DNA replication fork protection. We propose that RPA1 is a target of PTEN function in fork protection and that PTEN maintains genome stability through regulation of DNA replication.

  9. Relationship between expression and prognostic ability of PTEN, STAT3 and VEGF-C in colorectal cancer.

    PubMed

    Jin, Canhui; Wang, Aihong; Chen, Jianmin; Liu, Xiaomin; Wang, Gongping

    2012-10-01

    Expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), signal transducer and activator of transcription-3 (STAT3) and vascular endothelial growth factor-C (VEGF-C) and their relationship with clinico-pathological features and prognostic ability was determined using immunohistochemistry in 68 cases of colorectal cancer with follow-up data. Kaplan-Meier survival analysis was performed and the prognostic value was determined using univariate analysis. PTEN, STAT3 and VEGF-C expression was detected in 32.4, 60.3 and 63.2% of colorectal carcinoma cases and 90.0, 0 and 0% of normal colon samples, respectively. PTEN and STAT3 were correlated with pathological grade (p=0.011, p=0.001, respectively), but not with tumor size, lymph node metastasis or clinical stage. VEGF-C was correlated with lymph node metastasis (p=0.002), but not with tumor size, pathological grade or clinical stage. Expression of STAT3 and VEGF-C was negatively correlated with PTEN (r=-0.402, r=-0.320, respectively), whereas STAT3 and VEGF-C expression was positively correlated with PTEN (r=0.254). The 3- and 5-year survival rates of PTEN protein-positive patients (68.1 and 50.0%, respectively) were significantly higher than those of PTEN protein-negative patients (32.6 and 19.6%, respectively; p=0.008). The 3- and 5-year survival rates of STAT3-positive (29.3 and 17.1%, respectively) were significantly lower than those of STAT3-negative patients (66.7 and 48.1%, respectively; p=0.005). The 3- and 5-year survival rates of VEGF-C-positive patients (29.3 and 17.1%, respectively) were significantly lower than the rates of VEGF-C-negative patients (66.7 and 48.1%, respectively; p=0.003, p=0.004, respectively). Multivariate analysis revealed that VEGF-C expression was an independent prognostic factor. In conclusion, this study indicates that PTEN, STAT3 and VEGF-C expression are beneficial prognostic factors, which may aid in the accurate assessment of prognosis and guide clinical

  10. Profilin-PTEN interaction suppresses NF-κB activation via inhibition of IKK phosphorylation.

    PubMed

    Zaidi, Adeel H; Manna, Sunil K

    2016-04-01

    The molecular mechanism of Profilin for its tumour suppressor activity is still unknown. Nuclear transcription factor κB (NF-κB) is known to activate many target genes involved in cell proliferation. In the present study, we provide evidence that supports the involvement of Profilin in regulation of NF-κB, which might repress the tumorigenic response. Profilin overexpressing cells show low basal activity of IκBα kinase (IKK), high amounts of cytoplasmic inhibitory subunit of NF-κB (IκBα) and p65, and low nuclear NF-κB DNA binding activity. Co-localization and co-immunoprecipitation (Co-IP) studies suggest that Profilin interacts with a protein phosphatase, phosphatase and tension homologue (PTEN), and protects it from degradation. In turn, PTEN interacts physically and maintains a low phosphorylated state of the IKK complex and thereby suppresses NF-κB signalling. Thus, Profilin overexpressing cells show a decrease in NF-κB activation mediated by most of the inducers and potentiate cell death by repressing NF-κB-dependent genes involved in cell cycle progression. For the first time, we provide evidence, which suggests that Profilin increases tumour suppressor activity by regulating NF-κB. PMID:26787927

  11. Transforming growth factor-beta1 upregulation triggers pulmonary artery smooth muscle cell proliferation and apoptosis imbalance in rats with hypoxic pulmonary hypertension via the PTEN/AKT pathways.

    PubMed

    Liu, Yun; Cao, Yonggang; Sun, Shuyang; Zhu, Jinquan; Gao, Shan; Pang, Jie; Zhu, Daling; Sun, Zengxian

    2016-08-01

    Transforming growth factor-beta1 (TGFβ1) and Phosphatase and Tensin homolog deleted on chromosome ten (PTEN) are involved in the regulation of proliferation, differentiation, migration and apoptosis of various cell types. In previous studies, we have shown that TGFβ1 and PTEN play an important role in the progression of pulmonary vascular remodeling induced by pulmonary artery smooth muscle cells (PASMCs). However, the mechanisms involved in the activation of PASMCs between TGFβ1 and PTEN pathways remain unknown. We found that pulmonary vascular walls in hypoxic pulmonary arterial hypertension (PAH) rats were thicker than the vessels from normal rats in vivo. Substantially higher levels of TGFβ1 and significant loss of PTEN expression were observed in the lungs of PAH rats when compared with normoxia. Meanwhile, AKT, a downstream proliferative signaling protein of the PTEN antagonist PI3K, was markedly activated in the lungs of PAH rats. In vitro studies using PASMCs showed that TGFβ1 increased cell proliferation in PTEN-dependent manner. Moreover, we found that TGFβ1 enhanced cell survival, up-regulated the expression of Bcl-2 and procaspase-3, decreased the number of TUNEL-positive cells and caspase-3 expression in PASMCs under serum-deprived (SD) condition via PI3K/AKT pathway. The results further establish that TGFβ1 promoted PAH by decreasing PTEN expression and increasing PI3K/AKT activation in the lung. In conclusion, TGFβ1 mediated PTEN inactivation and resistance to apoptosis seems to be key mediators of lung vascular remodeling associated with PAH. These findings further clarify molecular mechanisms that support targeting PTEN/AKT signaling pathway to attenuate pathogenic derangements in PAH.

  12. Expression of Somatostatin Receptor Type 2A and PTEN in Neuroendocrine Neoplasms Is Associated with Tumor Grade but Not with Site of Origin.

    PubMed

    Wada, Hideo; Matsuda, Katsuya; Akazawa, Yuko; Yamaguchi, Yuka; Miura, Shiro; Ueki, Nozomi; Kinoshita, Akira; Yoshiura, Koh-Ichiro; Kondo, Hisayoshi; Ito, Masahiro; Nagayasu, Takeshi; Nakashima, Masahiro

    2016-09-01

    Neuroendocrine neoplasms (NENs) are derived from endocrine cells in various organs and share common morphological features. This study aimed to clarify whether NENs of different organs are comparable at the molecular pathologic level. We retrospectively collected 99 cases of NENs from gastro-entero-pancreatic, lung, and other organs and reclassified these according to identical criteria. Grade, site, and molecular expression profile including NE markers, Ki-67, p53, somatostatin receptor type 2A (SSTR2A), and phosphatase and tensin homolog (PTEN) were compared. PTEN immunoreactivity was also compared with genomic copy number by fluorescence in situ hybridization (FISH) and droplet digital polymerase chain reaction (ddPCR). No significant differences were observed in the immunoreactivities of NE markers, p53, SSTR2A, or PTEN expression in NENs between the different organ sites. PTEN and p53 functional inactivation along with the loss of membranous SSTR2A expression appeared to be commonly involved in high-grade NEN. FISH results were significantly correlated with the level of PTEN immunoreactivity and with the findings of ddPCR analyses. The demonstration that these tumors are comparable at the molecular level will likely contribute to the broadening of therapeutic options such as the use of somatostatin analogues and mTOR inhibitors against NENs regardless of the affected organ, whereas molecular characterization of tumor grade will be useful for determining treatment strategy. PMID:27256098

  13. The intracellular domain of L1CAM binds to casein kinase 2α and is neuroprotective via inhibition of the tumor suppressors PTEN and p53.

    PubMed

    Wang, Yan; Schachner, Melitta

    2015-06-01

    Cell adhesion molecule L1 promotes neuritogenesis and neuronal survival through triggering MAPK pathways. Based on the findings that L1 is associated with casein kinase 2 (CK2), and that deficiency in PTEN promotes neuritogenesis in vitro and regeneration after trauma, we examined the functional relationship between L1 and PTEN. In parallel, we investigated the tumor suppressor p53, which also regulates neuritogenesis. Here, we report that the intracellular domain of L1 binds to the subunit CK2α, and that knockdown of L1 leads to CK2 dephosphorylation and an increase in PTEN and p53 levels. Overexpression of L1, but not the L1 mutants L1 (S1181N, E1184V), which reduced binding between L1 and CK2, reduced expression levels of PTEN and p53 proteins, and enhanced levels of phosphorylated CK2α and mammalian target of rapamycin, which is a downstream effector of PTEN and p53. Treatment of neurons with a CK2 inhibitor or transfection with CK2α siRNA increased levels of PTEN and p53, and inhibited neuritogenesis. The combined observations indicate that L1 downregulates expression of PTEN and p53 via direct binding to CK2α. We suggest that L1 stimulates neuritogenesis by activating CK2α leading to decreased levels of PTEN and p53 via a novel, L1-triggered and CK2α-mediated signal transduction pathway. L1CAM (L1 cell adhesion molecule) is implicated in neural functions through the cognate src/MAP kinase signaling pathway. We now describe a novel signaling platform operating via the alpha subunit of casein kinase 2 which binds to the intracellular domain of L1. Knockdown of L1CAM leads to increased levels of tumor suppressor PTEN (phosphatase and tensin homolog) and p53, known to inhibit neuritogenesis in vitro and recovery from trauma in vivo. By activating this enzyme, L1CAM adds to its beneficial functions by decreasing the levels of PTEN and p53. PMID:25727698

  14. Protein kinase A-mediated phosphorylation of Pah1p phosphatidate phosphatase functions in conjunction with the Pho85p-Pho80p and Cdc28p-cyclin B kinases to regulate lipid synthesis in yeast.

    PubMed

    Su, Wen-Min; Han, Gil-Soo; Casciano, Jessica; Carman, George M

    2012-09-28

    Pah1p, which functions as phosphatidate phosphatase (PAP) in the yeast Saccharomyces cerevisiae, plays a crucial role in lipid homeostasis by controlling the relative proportions of its substrate phosphatidate and its product diacylglycerol. The diacylglycerol produced by PAP is used for the synthesis of triacylglycerol as well as for the synthesis of phospholipids via the Kennedy pathway. Pah1p is a highly phosphorylated protein in vivo and has been previously shown to be phosphorylated by the protein kinases Pho85p-Pho80p and Cdc28p-cyclin B. In this work, we showed that Pah1p was a bona fide substrate for protein kinase A, and we identified by mass spectrometry and mutagenesis that Ser-10, Ser-677, Ser-773, Ser-774, and Ser-788 were the target sites of phosphorylation. Protein kinase A-mediated phosphorylation of Pah1p inhibited its PAP activity by decreasing catalytic efficiency, and the inhibitory effect was primarily conferred by phosphorylation at Ser-10. Analysis of the S10A and S10D mutations (mimicking dephosphorylation and phosphorylation, respectively), alone or in combination with the seven alanine (7A) mutations of the sites phosphorylated by Pho85p-Pho80p and Cdc28p-cyclin B, indicated that phosphorylation at Ser-10 stabilized Pah1p abundance and inhibited its association with membranes, PAP activity, and triacylglycerol synthesis. The S10A mutation enhanced the physiological effects imparted by the 7A mutations, whereas the S10D mutations attenuated the effects of the 7A mutations. These data indicated that the protein kinase A-mediated phosphorylation of Ser-10 functions in conjunction with the phosphorylations mediated by Pho85p-Pho80p and Cdc28p-cyclin B and that phospho-Ser-10 should be dephosphorylated for proper PAP function.

  15. SLUG is a Direct Transcriptional Repressor of PTEN Tumor Suppressor

    PubMed Central

    Uygur, Berna; Abramo, Katrina; Leikina, Evgenia; Vary, Calvin; Liaw, Lucy; Wu, Wen-Shu

    2015-01-01

    BACGORUND PTEN/AKT signaling plays a key role in prostate cancer development and maintenance of prostate cancer stem cells. How other oncogenes or tumor suppressors interact with this pathway remain to be elucidated. SLUG is an zinc finger transcription factor of the Snail superfamily, and it promotes cancer metastasis and determines the mammary stem cell state. METHODS SLUG was overexpressed in cells by retroviral vector and knockdown of SLUG and PTEN was mediated by shRNAs-expressing lentiviruses. Expression level of SLUG and PTEN was examined by Western blot, RT-PCR, and qPCR analyses. PTEN promoter activity was measured by luciferase reporter assay. ChIP assay was used to measure the binding between SLUG and the PTEN promoter in vivo. RESULT We showed that overexpression of SLUG decreased expression of PTEN tumor repressor in prostate cancer cell lines 22RV1 and DU145; conversely, knockdown of SLUG expression elevated PTEN expresson at both protein and RNA level in these cells. We demonstrated that SLUG overexpression inhibits PTEN promoter activity through the proximal promoter region in prostate cancer cells. By ChIP assay, we confirmed that SLUG directly binds to the PTEN promoter region covering the E-box sites. We also showed that Slug deficiency leads to an increased expression of PTEN in mouse embryo fibroblasts and prostate tissues. Importantly, we found that overexpression of SLUG increases drug resistance of DU145 prostate cancer cell line and knockdown of SLUG by shRNA sensitizes DU145 cell line to chemotherapeutic drugs. We further demonstrated that PTEN knockdown converts drug sensitivity of DU145 cells expressing SLUG shRNA to anticancer drugs. CONCLUSION We provide compelling evidence showing that PTEN is a direct functional target of SLUG. Our findings offer new insight in the regulation of the PTEN/AKT pathway and provide a molecular basis for potential targeted therapies of prostate cancer PMID:25728608

  16. Methylseleninic Acid Superactivates p53-Senescence Cancer Progression Barrier in Prostate Lesions of Pten-Knockout Mouse.

    PubMed

    Wang, Lei; Guo, Xiaolan; Wang, Ji; Jiang, Cheng; Bosland, Maarten C; Lü, Junxuan; Deng, Yibin

    2016-01-01

    Monomethylated selenium (MM-Se) forms that are precursors of methylselenol, such as methylseleninic acid (MSeA), differ in metabolism and anticancer activities in preclinical cell and animal models from seleno-methionine that had failed to exert preventive efficacy against prostate cancer in North American men. Given that human prostate cancer arises from precancerous lesions such as high-grade prostatic intraepithelial neoplasia (HG-PIN), which frequently have lost phosphatase and tensin homolog (PTEN) tumor suppressor permitting phosphatidylinositol-3-OH kinase (PI3K)-protein kinase B (AKT) oncogenic signaling, we tested the efficacy of MSeA to inhibit HG-PIN progression in Pten prostate-specific knockout (KO) mice and assessed the mechanistic involvement of p53-mediated cellular senescence and of the androgen receptor (AR). We observed that short-term (4 weeks) oral MSeA treatment significantly increased expression of P53 and P21Cip1 proteins and senescence-associated-β-galactosidase staining, and reduced Ki67 cell proliferation index in Pten KO prostate epithelium. Long-term (25 weeks) MSeA administration significantly suppressed HG-PIN phenotype, tumor weight, and prevented emergence of invasive carcinoma in Pten KO mice. Mechanistically, the long-term MSeA treatment not only sustained P53-mediated senescence, but also markedly reduced AKT phosphorylation and AR abundance in the Pten KO prostate. Importantly, these cellular and molecular changes were not observed in the prostate of wild-type littermates which were similarly treated with MSeA. Because p53 signaling is likely to be intact in HG-PIN compared with advanced prostate cancer, the selective superactivation of p53-mediated senescence by MSeA suggests a new paradigm of cancer chemoprevention by strengthening a cancer progression barrier through induction of irreversible senescence with additional suppression of AR and AKT oncogenic signaling.

  17. MicroRNA-682-mediated downregulation of PTEN in intestinal epithelial cells ameliorates intestinal ischemia–reperfusion injury

    PubMed Central

    Liu, Z; Jiang, J; Yang, Q; Xiong, Y; Zou, D; Yang, C; Xu, J; Zhan, H

    2016-01-01

    Intestinal ischemia–reperfusion (I/R) injury causes inflammation and tissue damage and contributes to high morbidity and mortality, but the underlying mechanism remains elusive and effective therapies are still lacking. We report here a critical role of the microRNA 682 (miR-682) as a key regulator and therapeutic target in intestinal I/R injury. MiR-682 was markedly induced in intestinal epithelial cells (IECs) during intestinal ischemia in mice and in the human colonic epithelial cells during hypoxia, but was undetected rapidly after intestinal reperfusion in IEC of mice. MiR-682 induction during hypoxia was modulated by hypoxia-inducible factor-1α (HIF-1α). On lentivirus-mediated miR-682 overexpression in vivo during intestinal reperfusion or miR-682 mimic transfection in vitro during hypoxia, miR-682 decreased the expression of phosphatase and tensin homolog (PTEN) and subsequently activated nuclear translocation of nuclear factor kappa B (NF-κB) p65. Consequently, NF-κB activation by miR-682-mediated PTEN downregulation prevented reactive oxygen species (ROS) induction, inflammatory reaction, mitochondrial-mediated apoptosis and IEC apoptosis. The effect of miR-682-mediated PTEN/NF-κB pathway on IECs resulted in protection against intestinal I/R injury in mice. However, NF-κB chemical inhibitor reversed miR-682-mediated decreased PTEN expression, ROS induction, inflammation and IEC apoptosis. Collectively, these results identify a novel miR-682/PTEN/NF-κBp65 signaling pathway in IEC injury induced by I/R that could be targeted for therapy. PMID:27124584

  18. PTEN expression in PTEN-null leukaemic T cell lines leads to reduced proliferation via slowed cell cycle progression.

    PubMed

    Seminario, Maria-Cristina; Precht, Patricia; Wersto, Robert P; Gorospe, Myriam; Wange, Ronald L

    2003-11-01

    The balance of activities between the proto-oncogene phosphoinositide 3-kinase (PI3K) and the tumour suppressor gene PTEN has been shown to affect cellular growth and proliferation, as well as tumorigenesis. Previously, PTEN expression in the PTEN-null Jurkat T cell leukaemia line was shown to cause reduced proliferation without cell cycle arrest. Here, we further these investigations by determining the basis for this phenomenon. By BrdU pulse-chase and cell cycle arrest and release assays, we find that PTEN expression reduced proliferation by slowing progression through all phases of the cell cycle. This was associated with reduced levels of cyclins A, B1 and B2, cdk4, and cdc25A and increased p27KIP1 expression. Apoptosis played no role in the antiproliferative effect of PTEN, since only marginal increases in the rate of apoptosis were detected upon PTEN expression, and inhibitors of effector caspases did not restore proliferative capacity. Active Akt blocked the antiproliferative effects of PTEN, indicating that PTEN mediates its effects through conventional PI3K-linked signalling pathways. Similar results were obtained from a different PTEN-null leukaemia T cell line, CEM. Together, these results show that PTEN expression in leukaemic T cells leads to reduced proliferation via an apoptosis-independent mechanism involving slower passage through the cell cycle.

  19. Fish oil suppresses cell growth and metastatic potential by regulating PTEN and NF-κB signaling in colorectal cancer.

    PubMed

    Kansal, Shevali; Bhatnagar, Archana; Agnihotri, Navneet

    2014-01-01

    Homeostasis in eukaryotic tissues is tightly regulated by an intricate balance of the prosurvival and antisurvival signals. The tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10), a dual-specificity phosphatase, plays a functional role in cell cycle arrest and apoptosis. NF-κB and its downstream regulators (such as VEGF) play a central role in prevention of apoptosis, promotion of inflammation and tumor growth. Therefore, we thought to estimate the expression of PTEN, Poly-ADP-ribose polymerase (PARP), NF-κBp50, NF-κBp65 and VEGF to evaluate the effect of supplementation of fish oil on apoptotic and inflammatory signaling in colon carcinoma. Male wistar rats in Group I received purified diet while Group II and III received modified diet supplemented with FO∶CO(1∶1)&FO∶CO(2.5∶1) respectively. These were further subdivided into controls receiving ethylenediamine-tetra acetic-acid and treated groups received dimethylhydrazine-dihydrochloride (DMH)/week for 4 weeks. Animals sacrificed 48 hours after last injection constituted initiation phase and that sacrificed after 16 weeks constituted post-initiation phase. We have analysed expression of PTEN, NF-κBp50, NF-κBp65 by flowcytometer and nuclear localization of NF-κB by immunofluorescence. PARP and VEGF were assessed by immunohistochemistry. In the initiation phase, animals receiving DMH have shown increased % of apoptotic cells, PTEN, PARP, NF-κBp50, NF-κBp65 and VEGF however in post-initiation phase no significant alteration in apoptosis with decreased PTEN and increased PARP, NF-κBp50, NF-κBp65 and VEGF were observed as compared to control animals. On treatment with both ratios of fish oil in both the phases, augmentation in % of apoptotic cells, decreased PTEN, PARP, NF-κBp50, NF-κBp65 and VEGF were documented with respect to DMH treated animals with effect being more exerted with higher ration in post-initiation phase. Hence, fish oil activates apoptosis, diminishes

  20. Systemic elevation of PTEN induces a tumor suppressive metabolic state

    PubMed Central

    Garcia-Cao, Isabel; Song, Min Sup; Hobbs, Robin M.; Laurent, Gaelle; Giorgi, Carlotta; de Boer, Vincent C.J.; Anastasiou, Dimitrios; Ito, Keisuke; Sasaki, Atsuo T.; Rameh, Lucia; Carracedo, Arkaitz; Vander Heiden, Matthew G.; Cantley, Lewis C.; Pinton, Paolo; Haigis, Marcia C.; Pandolfi, Pier Paolo

    2012-01-01

    SUMMARY Decremental loss of PTEN results in cancer susceptibility and tumor progression. In turn this raises the possibility that PTEN elevation might be an attractive option for cancer prevention and therapy. We have generated several transgenic mouse lines with variably elevated PTEN expression levels, taking advantage of BAC (Bacterial Artificial Chromosome)-mediated transgenesis. Super-PTEN mutants are viable and show reduced body size due to decreased cell number, with no effect on cell size. Unexpectedly, PTEN elevation at the organism level results in healthy metabolism characterized by increased energy expenditure and reduced body fat accumulation. Cells derived from these mice show reduced glucose and glutamine uptake, increased mitochondrial oxidative phosphorylation, and are resistant to oncogenic transformation. Mechanistically we find that PTEN elevation orchestrates this metabolic switch by regulating PI3K-dependent and independent pathways, and negatively impacts two of the most pronounced metabolic features of tumor cells: glutaminolysis and the Warburg effect. PMID:22401813

  1. Deletion of PTEN produces autism-like behavioral deficits and alterations in synaptic proteins

    PubMed Central

    Lugo, Joaquin N.; Smith, Gregory D.; Arbuckle, Erin P.; White, Jessika; Holley, Andrew J.; Floruta, Crina M.; Ahmed, Nowrin; Gomez, Maribel C.; Okonkwo, Obi

    2014-01-01

    Many genes have been implicated in the underlying cause of autism but each gene accounts for only a small fraction of those diagnosed with autism. There is increasing evidence that activity-dependent changes in neuronal signaling could act as a convergent mechanism for many of the changes in synaptic proteins. One candidate signaling pathway that may have a critical role in autism is the PI3K/AKT/mTOR pathway. A major regulator of this pathway is the negative repressor phosphatase and tensin homolog (PTEN). In the current study we examined the behavioral and molecular consequences in mice with neuron subset-specific deletion of PTEN. The knockout (KO) mice showed deficits in social chamber and social partition test. KO mice demonstrated alterations in repetitive behavior, as measured in the marble burying test and hole-board test. They showed no changes in ultrasonic vocalizations emitted on postnatal day 10 or 12 compared to wildtype (WT) mice. They exhibited less anxiety in the elevated-plus maze test and were more active in the open field test compared to WT mice. In addition to the behavioral alterations, KO mice had elevation of phosphorylated AKT, phosphorylated S6, and an increase in S6K. KO mice had a decrease in mGluR but an increase in total and phosphorylated fragile X mental retardation protein. The disruptions in intracellular signaling may be why the KO mice had a decrease in the dendritic potassium channel Kv4.2 and a decrease in the synaptic scaffolding proteins PSD-95 and SAP102. These findings demonstrate that deletion of PTEN results in long-term alterations in social behavior, repetitive behavior, activity, and anxiety. In addition, deletion of PTEN significantly alters mGluR signaling and many synaptic proteins in the hippocampus. Our data demonstrates that deletion of PTEN can result in many of the behavioral features of autism and may provide insights into the regulation of intracellular signaling on synaptic proteins. PMID:24795561

  2. Deletion of PTEN produces autism-like behavioral deficits and alterations in synaptic proteins.

    PubMed

    Lugo, Joaquin N; Smith, Gregory D; Arbuckle, Erin P; White, Jessika; Holley, Andrew J; Floruta, Crina M; Ahmed, Nowrin; Gomez, Maribel C; Okonkwo, Obi

    2014-01-01

    Many genes have been implicated in the underlying cause of autism but each gene accounts for only a small fraction of those diagnosed with autism. There is increasing evidence that activity-dependent changes in neuronal signaling could act as a convergent mechanism for many of the changes in synaptic proteins. One candidate signaling pathway that may have a critical role in autism is the PI3K/AKT/mTOR pathway. A major regulator of this pathway is the negative repressor phosphatase and tensin homolog (PTEN). In the current study we examined the behavioral and molecular consequences in mice with neuron subset-specific deletion of PTEN. The knockout (KO) mice showed deficits in social chamber and social partition test. KO mice demonstrated alterations in repetitive behavior, as measured in the marble burying test and hole-board test. They showed no changes in ultrasonic vocalizations emitted on postnatal day 10 or 12 compared to wildtype (WT) mice. They exhibited less anxiety in the elevated-plus maze test and were more active in the open field test compared to WT mice. In addition to the behavioral alterations, KO mice had elevation of phosphorylated AKT, phosphorylated S6, and an increase in S6K. KO mice had a decrease in mGluR but an increase in total and phosphorylated fragile X mental retardation protein. The disruptions in intracellular signaling may be why the KO mice had a decrease in the dendritic potassium channel Kv4.2 and a decrease in the synaptic scaffolding proteins PSD-95 and SAP102. These findings demonstrate that deletion of PTEN results in long-term alterations in social behavior, repetitive behavior, activity, and anxiety. In addition, deletion of PTEN significantly alters mGluR signaling and many synaptic proteins in the hippocampus. Our data demonstrates that deletion of PTEN can result in many of the behavioral features of autism and may provide insights into the regulation of intracellular signaling on synaptic proteins.

  3. Ursolic acid induced anti-proliferation effects in rat primary vascular smooth muscle cells is associated with inhibition of microRNA-21 and subsequent PTEN/PI3K.

    PubMed

    Jiang, Qixiao; Han, Yantao; Gao, Hui; Tian, Rong; Li, Ping; Wang, Chunbo

    2016-06-15

    This study focused on the anti-proliferation effects of ursolic acid (UA) in rat primary vascular smooth muscle cells (VSMCs) and investigated underlying molecular mechanism of action. Rat primary VSMCs were pretreated with UA (10, 20 or 30μM) or amino guanidine (AG, 50μM) for 12h or with PI3K inhibitor LY294002 for 30min or with Akt inhibitor MK2206 for 24h, then 10% fetal bovine serum was used to induce proliferation. CCK-8 was used to assess cell proliferation. To explore the mechanism, cells were treated with UA (10, 20 or 30μM), LY294002 or MK2206, or transient transfected to inhibit miRNA-21 (miRNA-21) or to overexpress PTEN, then quantitative real-time PCR was used to assess the mRNA levels of miRNA-21 and phosphatase and tensin homolog (PTEN) for cells treated with UA or miRNA-21 inhibitor; western blotting was used to measure the protein levels of PTEN and PI3K. UA exerted significant anti-proliferation effects in rat primary VSMCs. Furthermore, UA inhibited the expression of miRNA-21 and subsequently enhanced the expression of PTEN. PTEN was found to inhibit the expression of PI3K. In conclusion, UA exerts anti-proliferation effects in rat primary VSMCs, which is associated with the inhibition of miRNA-21 expression and modulation of PTEN/PI3K signaling pathway.

  4. PTEN and NF1 inactivation in Schwann cells produces a severe phenotype in the peripheral nervous system that promotes the development and malignant progression of peripheral nerve sheath tumors

    PubMed Central

    Keng, Vincent W.; Rahrmann, Eric P.; Watson, Adrienne L.; Tschida, Barbara R.; Moertel, Christopher L.; Jessen, Walter J.; Rizvi, Tilat A.; Collins, Margaret H.; Ratner, Nancy; Largaespada, David A.

    2012-01-01

    The genetic evolution from a benign neurofibroma to a malignant sarcoma in patients with neurofibromatosis type 1 (NF1) syndrome remains unclear. Schwann cells and/or their precursor cells are believed to be the primary pathogenic cell in neurofibromas because they harbor biallelic neurofibromin 1 (NF1) gene mutations. However, the phosphatase and tensin homolog (Pten) and neurofibromatosis 1 (Nf1) genes recently were found to be co-mutated in high-grade peripheral nerve sheath tumors (PNSTs) in mice. In this study, we created transgenic mice that lack both Pten and Nf1 in Schwann cells and Schwann cell precursor cells in order to validate the role of these two genes in PNST formation in vivo. Haploinsufficiency or complete loss of Pten dramatically accelerated neurofibroma development and led to the development of higher-grade PNSTs in the context of Nf1 loss. Pten dosage, together with Nf1 loss, was sufficient for the progression from low-grade to high-grade PNSTs. Genetic analysis of human sporadic malignant pheripheral nerve sheath tumors (MPNSTs) also revealed down-regulation of PTEN expression, suggesting that Pten-regulated pathways are major tumor suppressive barriers to neurofibroma progression. Together, our findings establish a novel mouse model that can rapidly recapitulate the onset of human neurofibroma tumorigenesis and the progression to MPNSTs. PMID:22700876

  5. PTEN stabilizes TOP2A and regulates the DNA decatenation.

    PubMed

    Kang, Xi; Song, Chang; Du, Xiao; Zhang, Cong; Liu, Yu; Liang, Ling; He, Jinxue; Lamb, Kristy; Shen, Wen H; Yin, Yuxin

    2015-12-10

    PTEN is a powerful tumor suppressor that antagonizes the cytoplasmic PI3K-AKT pathway and suppresses cellular proliferation. PTEN also plays a role in the maintenance of genomic stability in the nucleus. Here we report that PTEN facilitates DNA decatenation and controls a decatenation checkpoint. Catenations of DNA formed during replication are decatenated by DNA topoisomerase II (TOP2), and this process is actively monitored by a decatenation checkpoint in G2 phase. We found that PTEN deficient cells form ultra-fine bridges (UFBs) during anaphase and these bridges are generated as a result of insufficient decatenation. We show that PTEN is physically associated with a decatenation enzyme TOP2A and that PTEN influences its stability through OTUD3 deubiquitinase. In the presence of PTEN, ubiquitination of TOP2A is inhibited by OTUD3. Deletion or deficiency of PTEN leads to down regulation of TOP2A, dysfunction of the decatenation checkpoint and incomplete DNA decatenation in G2 and M phases. We propose that PTEN controls DNA decatenation to maintain genomic stability and integrity.

  6. PTEN stabilizes TOP2A and regulates the DNA decatenation

    PubMed Central

    Kang, Xi; Song, Chang; Du, Xiao; Zhang, Cong; Liu, Yu; Liang, Ling; He, Jinxue; Lamb, Kristy; Shen, Wen H.; Yin, Yuxin

    2015-01-01

    PTEN is a powerful tumor suppressor that antagonizes the cytoplasmic PI3K-AKT pathway and suppresses cellular proliferation. PTEN also plays a role in the maintenance of genomic stability in the nucleus. Here we report that PTEN facilitates DNA decatenation and controls a decatenation checkpoint. Catenations of DNA formed during replication are decatenated by DNA topoisomerase II (TOP2), and this process is actively monitored by a decatenation checkpoint in G2 phase. We found that PTEN deficient cells form ultra-fine bridges (UFBs) during anaphase and these bridges are generated as a result of insufficient decatenation. We show that PTEN is physically associated with a decatenation enzyme TOP2A and that PTEN influences its stability through OTUD3 deubiquitinase. In the presence of PTEN, ubiquitination of TOP2A is inhibited by OTUD3. Deletion or deficiency of PTEN leads to down regulation of TOP2A, dysfunction of the decatenation checkpoint and incomplete DNA decatenation in G2 and M phases. We propose that PTEN controls DNA decatenation to maintain genomic stability and integrity. PMID:26657567

  7. Modeling the self-organized phosphatidylinositol lipid signaling system in chemotactic cells using quantitative image analysis.

    PubMed

    Shibata, Tatsuo; Nishikawa, Masatoshi; Matsuoka, Satomi; Ueda, Masahiro

    2012-11-01

    A key signaling event that is responsible for gradient sensing in eukaryotic cell chemotaxis is a phosphatidylinositol (PtdIns) lipid reaction system. The self-organization activity of this PtdIns lipid system induces an inherent polarity, even in the absence of an external chemoattractant gradient, by producing a localized PtdIns (3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)]-enriched domain on the membrane. Experimentally, we found that such a domain could exhibit two types of behavior: (1) it could be persistent and travel on the membrane, or (2) be stochastic and transient. Taking advantage of the simultaneous visualization of PtdIns(3,4,5)P(3) and the enzyme phosphatase and tensin homolog (PTEN), for which PtdIns(3,4,5)P(3) is a substrate, we statistically demonstrated the inter-dependence of their spatiotemporal dynamics. On the basis of this statistical analysis, we developed a theoretical model for the self-organization of PtdIns lipid signaling that can accurately reproduce both persistent and transient domain formation; these types of formations can be explained by the oscillatory and excitability properties of the system, respectively. PMID:22899720

  8. Conditional genetic deletion of PTEN after a spinal cord injury enhances regenerative growth of CST axons and motor function recovery in mice

    PubMed Central

    Danilov, Camelia A.; Steward, Oswald

    2015-01-01

    Previous studies indicate that conditional genetic deletion of phosphatase and tensin homolog (PTEN) in neonatal mice enhances the ability of axons to regenerate following spinal cord injury (SCI) in adults. Here, we assessed whether deleting PTEN in adult neurons post-SCI is also effective, and whether enhanced regenerative growth is accompanied by enhanced recovery of voluntary motor function. PTENloxP/loxP mice received moderate contusion injuries at cervical level 5 (C5). One group received unilateral injections of adeno-associated virus expressing CRE (AAV-CRE) into the sensorimotor cortex; controls received a vector expressing green fluorescent protein (AAV-GFP) or injuries only (no vector injections). Forelimb function was tested for 14 weeks post-SCI using a grip strength meter (GSM) and a hanging task. The corticospinal tract (CST) was traced by injecting mini-ruby BDA into the sensorimotor cortex. Forelimb gripping ability was severely impaired immediately post-SCI but recovered slowly over time. The extent of recovery was significantly greater in PTEN-deleted mice in comparison to either the AAV-GFP group or the injury only group. BDA tract tracing revealed significantly higher numbers of BDA-labeled axons in caudal segments in the PTEN-deleted group compared to control groups. In addition, in the PTEN-deleted group, there were exuberant collaterals extending from the main tract rostral to the lesion, into and around the scar tissue at the injury site. These results indicate that PTEN deletion in adult mice shortly post-SCI can enhance regenerative growth of CST axons and forelimb motor function recovery. PMID:25704959

  9. Short hairpin RNA against PTEN enhances regenerative growth of corticospinal tract axons after spinal cord injury.

    PubMed

    Zukor, Katherine; Belin, Stephane; Wang, Chen; Keelan, Nadia; Wang, Xuhua; He, Zhigang

    2013-09-25

    Developing approaches to promote the regeneration of descending supraspinal axons represents an ideal strategy for rebuilding neuronal circuits to improve functional recovery after spinal cord injury (SCI). Our previous studies demonstrated that genetic deletion of phosphatase and tensin homolog (PTEN) in mouse corticospinal neurons reactivates their regenerative capacity, resulting in significant regeneration of corticospinal tract (CST) axons after SCI. However, it is unknown whether nongenetic methods of suppressing PTEN have similar effects and how regenerating axons interact with the extrinsic environment. Herein, we show that suppressing PTEN expression with short-hairpin RNA (shRNA) promotes the regeneration of injured CST axons, and these axons form anatomical synapses in appropriate areas of the cord caudal to the lesion. Importantly, this model of increased CST regrowth enables the analysis of extrinsic regulators of CST regeneration in vivo. We find that regenerating axons avoid dense clusters of fibroblasts and macrophages in the lesion, suggesting that these cell types might be key inhibitors of axon regeneration. Furthermore, most regenerating axons cross the lesion in association with astrocytes, indicating that these cells might be important for providing a permissive bridge for axon regeneration. Lineage analysis reveals that these bridge-forming astrocytes are not derived from ependymal stem cells within the spinal cord, suggesting that they are more likely derived from a subset of mature astrocytes. Overall, this study reveals insights into the critical extrinsic and intrinsic regulators of axon regeneration and establishes shRNA as a viable means to manipulate these regulators and translate findings into other mammalian models.

  10. PTEN and NEDD4 in Human Breast Carcinoma.

    PubMed

    Chen, Yilun; van de Vijver, Marc J; Hibshoosh, Hanina; Parsons, Ramon; Saal, Lao H

    2016-01-01

    PTEN is an important tumor suppressor gene that antagonizes the oncogenic PI3K/AKT signaling pathway and has functions in the nucleus for maintaining genome integrity. Although PTEN inactivation by mutation is infrequent in breast cancer, transcript and protein levels are deficient in >25 % of cases. The E3 ubiquitin ligase NEDD4 (also known as NEDD4-1) has been reported to negatively regulate PTEN protein levels through poly-ubiquitination and proteolysis in carcinomas of the prostate, lung, and bladder, but its effect on PTEN in the breast has not been studied extensively. To investigate whether NEDD4 contributes to low PTEN levels in human breast cancer, we analyzed the expression of these proteins by immunohistochemistry across a large Swedish cohort of breast tumor specimens, and their transcript expression levels by microarrays. For both NEDD4 and PTEN, their transcript expression was significantly correlated to their protein expression. However, comparing NEDD4 expression to PTEN expression, either no association or a positive correlation was observed at the protein and transcript levels. This unexpected observation was further corroborated in two independent breast cancer cohorts from The Netherlands Cancer Institute and The Cancer Genome Atlas. Our results suggest that NEDD4 is not responsible for the frequent down-regulation of the PTEN protein in human breast carcinoma.

  11. NEDD4-1 and PTEN expression in keloid scarring.

    PubMed

    Sang, P F; Wang, H; Wang, M; Hu, C; Zhang, J S; Li, X J; Zhu, F

    2015-01-01

    Keloid scarring remains a major problem in plastic surgery. The aim of this study was to determine the expression of the PTEN tumor suppressor and NEDD4-1 genes in keloid tissue and explore their effect on the formation of such scarring. Twenty keloid patients were enrolled in the study and underwent surgical removal of keloid tissue. No patient had received chemotherapy and/or radiotherapy prior to treatment. PTEN and NEDD4-1 mRNA expression was detected by reverse transcription PCR, while PTEN protein expression was assessed using immunohistochemistry. Our results showed that levels of PTEN were significantly diminished in keloid samples (P < 0.05), whereas those of NEDD4-1 did not significantly differ between keloid tissue and normal skin (P > 0.05). Furthermore, we found that NEDD4-1 expression is high and inversely correlated with that of PTEN in keloids. Our results suggest that the PTEN/PI3K/AKT pathway may play an important role in keloid formation and reduces PTEN expression in such tissue. Finally, although NEDD4-1 has previously been identified as a factor in keloid susceptibility, and the protein for which it encodes is known to degrade PTEN by catalyzing its polyubiquitylation, the detailed mechanism behind its involvement in keloid formation needs to be further studied. PMID:26535660

  12. Phosphoinositide 5- and 3-phosphatase activities of a voltage-sensing phosphatase in living cells show identical voltage dependence.

    PubMed

    Keum, Dongil; Kruse, Martin; Kim, Dong-Il; Hille, Bertil; Suh, Byung-Chang

    2016-06-28

    Voltage-sensing phosphatases (VSPs) are homologs of phosphatase and tensin homolog (PTEN), a phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] 3-phosphatase. However, VSPs have a wider range of substrates, cleaving 3-phosphate from PI(3,4)P2 and probably PI(3,4,5)P3 as well as 5-phosphate from phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and PI(3,4,5)P3 in response to membrane depolarization. Recent proposals say these reactions have differing voltage dependence. Using Förster resonance energy transfer probes specific for different PIs in living cells with zebrafish VSP, we quantitate both voltage-dependent 5- and 3-phosphatase subreactions against endogenous substrates. These activities become apparent with different voltage thresholds, voltage sensitivities, and catalytic rates. As an analytical tool, we refine a kinetic model that includes the endogenous pools of phosphoinositides, endogenous phosphatase and kinase reactions connecting them, and four exogenous voltage-dependent 5- and 3-phosphatase subreactions of VSP. We show that apparent voltage threshold differences for seeing effects of the 5- and 3-phosphatase activities in cells are not due to different intrinsic voltage dependence of these reactions. Rather, the reactions have a common voltage dependence, and apparent differences arise only because each VSP subreaction has a different absolute catalytic rate that begins to surpass the respective endogenous enzyme activities at different voltages. For zebrafish VSP, our modeling revealed that 3-phosphatase activity against PI(3,4,5)P3 is 55-fold slower than 5-phosphatase activity against PI(4,5)P2; thus, PI(4,5)P2 generated more slowly from dephosphorylating PI(3,4,5)P3 might never accumulate. When 5-phosphatase activity was counteracted by coexpression of a phosphatidylinositol 4-phosphate 5-kinase, there was accumulation of PI(4,5)P2 in parallel to PI(3,4,5)P3 dephosphorylation

  13. A miR-335/COX-2/PTEN axis regulates the secretory phenotype of senescent cancer-associated fibroblasts

    PubMed Central

    Kabir, Tasnuva D.; Leigh, Ross J.; Tasena, Hataitip; Mellone, Massimiliano; Coletta, Ricardo D.; Parkinson, Eric K.; Prime, Stephen S.; Thomas, Gareth J.; Paterson, Ian C.; Zhou, Donghui; McCall, John; Speight, Paul M.; Lambert, Daniel W.

    2016-01-01

    Senescent cancer-associated fibroblasts (CAF) develop a senescence-associated secretory phenotype (SASP) that is believed to contribute to cancer progression. The mechanisms underlying SASP development are, however, poorly understood. Here we examined the functional role of microRNA in the development of the SASP in normal fibroblasts and CAF. We identified a microRNA, miR-335, up-regulated in the senescent normal fibroblasts and CAF and able to modulate the secretion of SASP factors and induce cancer cell motility in co-cultures, at least in part by suppressing the expression of phosphatase and tensin homologue (PTEN). Additionally, elevated levels of cyclo-oxygenase 2 (PTGS2; COX-2) and prostaglandin E2 (PGE2) secretion were observed in senescent fibroblasts, and inhibition of COX-2 by celecoxib reduced the expression of miR-335, restored PTEN expression and decreased the pro-tumourigenic effects of the SASP. Collectively these data demonstrate the existence of a novel miRNA/PTEN-regulated pathway modulating the inflammasome in senescent fibroblasts. PMID:27385366

  14. PTEN loss and HOXA10 expression are associated with ovarian endometrioid adenocarcinoma differentiation and progression.

    PubMed

    Tanwar, Pradeep S; Kaneko-Tarui, Tomoko; Lee, Ho-Joon; Zhang, Lihua; Teixeira, Jose M

    2013-04-01

    Epithelial ovarian cancer is a heterogeneous disease that is subdivided into five major histotypes but the mechanisms driving their differentiation are not clear. Mutations in adenomatous polyposis coli (APC) and β-catenin are commonly observed in the human ovarian endometrioid adenocarcinoma (OEA) patients. However, the mechanisms subsequent to APC deletion in ovarian tumorigenesis have not been well characterized. We have conditionally deleted APC in the murine ovarian surface epithelium (OSE) and showed that its loss leads to development of epithelial inclusion cysts. High-grade OEAs with tightly packed villoglandular histology were observed in older APC-deleted mice. Phosphatase and tensin homolog (PTEN) expression was elevated in the early lesions but lost after progression to the more advanced tumors. Knockdown of APC or expression of a gain-of-function β-catenin similarly induced human OSE cells to develop tumors with endometrioid histology in xenografts. Expression of HOXA10 was induced in both the advanced APC-deleted murine tumors and in the tumor xenografts of human OSE cells with knocked-down APC. These results show that reduced APC activity is sufficient to induce formation of epithelial inclusion cysts and support OEA development and suggest that induced HOXA10 expression and loss of PTEN are key mechanisms driving endometrioid histotype differentiation and progression.

  15. Hydrogen sulfide prevents Abeta-induced neuronal apoptosis by attenuating mitochondrial translocation of PTEN.

    PubMed

    Cui, Weigang; Zhang, Yinghua; Yang, Chenxi; Sun, Yiyuan; Zhang, Min; Wang, Songtao

    2016-06-14

    Neuronal cell apoptosis is an important pathological change in Alzheimer's disease (AD). Hydrogen sulfide (H(2)S) is known to be a novel gaseous signaling molecule and a cytoprotectant in many diseases including AD. However, the molecular mechanism of the antiapoptosis activity of H(2)S in AD is not yet fully understood. The aim of the present study is to evaluate the inhibitory effects of H(2)S on Abeta (Aβ)-induced apoptosis and the molecular mechanisms underlying primary neuron cells. Our results showed that sodium hydrosulfide (NaHS), a donor of H(2)S, significantly ameliorated Aβ-induced cell apoptosis. NaHS also reversed the Aβ-induced translocation of the phosphatase and tensin homologs deleted on chromosome 10 (PTEN) from the cytosol to the mitochondria. Furthermore, H(2)S increased the level of p-AKT/AKT significantly. Interestingly, the antiapoptosis effects of H(2)S were blocked down by specific PI3K/AKT inhibitor wortmannin. In conclusion, these data indicate that H(2)S inhibits Aβ-induced neuronal apoptosis by attenuating mitochondrial translocation of PTEN and that activation of PI3K/AKT signaling pathway plays a critical role in H(2)S-mediated neuronal protection. Our findings provide a novel route into the molecular mechanisms of neuronal apoptosis in AD.

  16. MicroRNA-93 inhibits ischemia-reperfusion induced cardiomyocyte apoptosis by targeting PTEN

    PubMed Central

    Ke, Zun-Ping; Xu, Peng; Shi, Yan; Gao, Ai-Mei

    2016-01-01

    MicroRNAs have been implicated in some biological and pathological processes, including the myocardial ischemia/reperfusion (I/R) injury. Recent findings demonstrated that miR-93 might provide a potential cardioprotective effect on ischemic heart disease. This study was to investigate the role of miR-93 in I/R-induced cardiomyocyte injury and the potential mechanism. In this study, we found that hypoxia/reoxygenation (H/R) dramatically increased LDH release, MDA contents, ROS generation, and endoplasmic reticulum stress (ERS)-mediated cardiomyocyte apoptosis, which were attenuated by co-transfection with miR-93 mimic. Phosphatase and tensin homolog (PTEN) was identified as the target gene of miR-93. Furthermore, miR-93 mimic significantly increased p-Akt levels under H/R, which was partially released by LY294002. In addtion, Ad-miR-93 also attenuated myocardial I/R injury in vivo, manifested by reduced LDH and CK levels, infarct area and cell apoptosis. Taken together, our findings indicates that miR-93 could protect against I/R-induced cardiomyocyte apoptosis by inhibiting PI3K/AKT/PTEN signaling. PMID:27119510

  17. Role of phosphatase of regenerating liver 1 (PRL1) in spermatogenesis

    PubMed Central

    Bai, Yunpeng; Zhou, Hong-Ming; Zhang, Lujuan; Dong, Yuanshu; Zeng, Qi; Shou, Weinian; Zhang, Zhong-Yin

    2016-01-01

    The PRL phosphatases are oncogenic when overexpressed but their in vivo biological function is less well understood. Previous gene deletion study revealed a role for PRL2 in spermatogenesis. We report here the first knockout mice lacking PRL1, the most related homolog of PRL2. We found that loss of PRL1 does not affect spermatogenesis and reproductive ability of male mice, likely due to functional compensation by the relatively higher expression of PRL2 in the testes. However, PRL1−/−/PRL2+/− male mice show testicular atrophy phenotype similar to PRL2−/− mice. More strikingly, deletion of one PRL1 allele in PRL2−/− male mice causes complete infertility. Mechanistically, the total level of PRL1 and PRL2 is negatively correlated with the PTEN protein level in the testis and PRL1+/−/PRL2−/− mice have the highest level of PTEN, leading to attenuated Akt activation and increased germ cell apoptosis, effectively halting spermatozoa production. These results provide the first evidence that in addition to PRL2, PRL1 is also required for spermatogenesis by downregulating PTEN and promoting Akt signaling. The ability of the PRLs to suppress PTEN expression underscores the biochemical basis for their oncogenic potential. PMID:27666520

  18. TBX2 represses PTEN in rhabdomyosarcoma and skeletal muscle

    PubMed Central

    Zhu, Bo; Zhang, Meiling; Williams, Elizabeth M.; Keller, Charles; Mansoor, Atiya; Davie, Judith K.

    2015-01-01

    Rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma in children that shares many features of developing skeletal muscle. TBX2, a T-box family member, is highly up regulated in tumor cells of both major RMS subtypes where it functions as an oncogene. TBX2 is a repressor that is often over expressed in cancer cells and functions in bypassing cell growth control, including the repression of the cell cycle regulators p14 and p21. We have found that TBX2 directly represses the tumor suppressor PTEN in both RMS and normal muscle. Exogenous expression of TBX2 in normal muscle cells down regulates PTEN, and depletion or interference with TBX2 in RMS cells up regulates PTEN. Human RMS tumors show high levels of TBX2 and correspondingly low levels of PTEN. The expression of PTEN in clinical RMS samples is relatively uncharacterized and we establish that suppression of PTEN is a frequent event in both subtypes of RMS. TBX2 represses PTEN by directly binding to the promoter and recruiting the histone deacetylase, HDAC1. RMS cells have high levels of activated AKT due to the deregulation of PI3K signaling, and depletion or interference with TBX2, which up regulates PTEN, results in a reduction of phospho-AKT. We have also found that the highly related T-box family member TBX3 does not repress PTEN in the muscle lineage. This work suggests that TBX2 is a central component of the PTEN/PI3K/AKT signaling pathway deregulation in RMS cells and that targeting TBX2 in RMS tumors may offer a novel therapeutic approach for RMS. PMID:26686089

  19. IGF1-induced AKT phosphorylation and cell proliferation are suppressed with the increase in PTEN during luteinization in human granulosa cells.

    PubMed

    Goto, Maki; Iwase, Akira; Harata, Toko; Takigawa, Sachiko; Suzuki, Kyosuke; Manabe, Shuichi; Kikkawa, Fumitaka

    2009-05-01

    Granulosa cells proliferate and then undergo differentiation; an inverse relationship between these processes is observed during terminal follicular growth. During terminal follicular growth and initial luteinization, there is a necessary transition of granulosa cells to a less proliferative and highly steroidogenic form in response to LH. Although the expression of several molecules has been reported to be up-regulated by LH, proliferation/differentiation transition is not fully understood. Here, we show that the expression of a tumor suppressor, phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was induced with human chorionic gonadotropin (hCG) treatment in human luteinized granulosa cells. Pretreatment with hCG attenuated insulin-like growth factor (IGF)-1-induced phosphorylation of AKT and cell proliferation, not phosphorylation of ERK1/2. Moreover, suppression of hCG-induced PTEN expression with siRNA increased AKT phosphorylation and cell proliferation in response to IGF1. We also demonstrate that a PI3K inhibitor, LY294002, not a MEK inhibitor, PD98059, inhibited IGF1-induced cell proliferation. In conclusion, PTEN induced to express by hCG in luteinized granulosa cells that inactivates AKT, not ERK, and attenuates IGF1-induced cell proliferation. PTEN expression may be a trigger for proliferation/differentiation transition in human granulosa cells.

  20. Short-Term PTEN Inhibition Improves In Vitro Activation of Primordial Follicles, Preserves Follicular Viability, and Restores AMH Levels in Cryopreserved Ovarian Tissue From Cancer Patients

    PubMed Central

    Novella-Maestre, Edurne; Herraiz, Sonia; Rodríguez-Iglesias, Beatriz; Díaz-García, César; Pellicer, Antonio

    2015-01-01

    Introduction In vitro activation and growth of primordial dormant follicles to produce fertilizable oocytes would provide a useful instrument for fertility preservation. The employment of Phosphatase and TENsin homolog (PTEN) inhibitors, in combination with Protein kinase B (Akt) stimulating molecules, has been previously employed to increase follicular activation through the stimulation of the PTEN-Akt pathway. Methods We aim to establish improved in vitro activation also for cancer patients whose ovarian tissue has already been cryopreserved. Fresh and previously cryopreserved human ovarian cortex were exposed to short-term, low-concentration and ovary-specific treatment with only a PTEN inhibitor. Results Our in vitro activation protocol enhances the activation mechanisms of primordial follicles in both fresh and cryopreserved samples, and enlarges growing populations without inducing apoptosis in either follicles or the surrounding stroma. Treatment augments estradiol secretion and restores the expression levels of the previously diminished Anti-Müllerian hormone by means of cryopreservation procedures. Genomic modulation of the relative expression of PTEN pathway genes was found in treated samples. Conclusion The in vitro activation protocol offers new alternatives for patients with cryopreserved tissue as it increases the pool of viable activated follicles available for in vitro growth procedures. The combination of ovarian tissue cryopreservation and in vitro activation of primordial follicles, the main ovarian reserve component, will be a major advancement in fertility preservation. PMID:26024525

  1. PTEN Contributes to Profound PI3K/Akt Signaling Pathway Deregulation in Dystrophin-Deficient Dog Muscle

    PubMed Central

    Feron, Marie; Guevel, Laetitia; Rouger, Karl; Dubreil, Laurence; Arnaud, Marie-Claire; Ledevin, Mireille; Megeney, Lynn A.; Cherel, Yan; Sakanyan, Vehary

    2009-01-01

    Duchenne muscular dystrophy is the most common and severe form of muscular dystrophy, and although the genetic basis of this disease is well defined, the overall mechanisms that define its pathogenesis remain obscure. Alterations in individual signaling pathways have been described, but little information is available regarding their putative implications in Duchenne muscular dystrophy pathogenesis. Here, we studied the status of various major signaling pathways in the Golden Retriever muscular dystrophy dog that specifically reproduces the full spectrum of human pathology. Using antibody arrays, we found that Akt1, glycogen synthase kinase-3β (GSK3β), 70-kDa ribosomal protein S6 kinase (p70S6K), extracellular signal-regulated kinases 1/2, and p38δ and p38γ kinases all exhibited decreased phosphorylation in muscle from a 4-month-old animal with Golden Retriever muscular dystrophy, revealing a deep alteration of the phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase pathways. Immunohistochemistry analysis revealed the presence of muscle fibers exhibiting a cytosolic accumulation of Akt1, GSK3β, and phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase (PTEN), an enzyme counteracting PI3K-mediated Akt activation. Enzymatic assays established that these alterations in phosphorylation and expression levels were associated with decreased Akt and increased GSK3β and PTEN activities. PTEN/GSK3β-positive fibers were also observed in muscle sections from 3- and 36-month-old animals, indicating long-term PI3K/Akt pathway alteration. Collectively, our data suggest that increased PTEN expression and activity play a central role in PI3K/Akt/GSK3β and p70S6K pathway modulation, which could exacerbate the consequences of dystrophin deficiency. PMID:19264909

  2. Extracellular phosphatases of Chlamydomonas reinhardi and their regulation.

    PubMed

    Patni, N J; Dhawale, S W; Aaronson, S

    1977-04-01

    Chlamydomonas reinhardi, cultured under normal growth conditions, secreted significant amounts of protein and carbohydrates but not lipids or nucleic acids. A fivefold increase in light intensity led to a tenfold increase in secreted protein and carbohydrate. Among the proteins secreted was acid phosphatase with a pH optimum at 4.8 like the enzyme in the cells. Phosphorus depleted algae grown on minimal orthophosphate contained and secreted both acid and alkaline phosphatase. The pH optimum of the intracellular alkaline phosphatase was 9.2. When phosphorus-depleted cells were grown with increasing orthophosphate, intra- and extracellular alkaline phosphatase was almost completely repressed and intra- and extracellular acid phosphatase was partially repressed. Extracellular acid and alkaline phosphatase increased with the age of the culture. Electrophoresis indicated only one acid and one alkaline phosphatase in phosphorus-satisfied and phosphorus-depleted cells. Chlamydomonas cells suspended in an inorganic salt solution secreted only acid phosphatase; the absence of any extr-cellular cytoplasmic marker enzyme indicated that there was little, if any, autolysis to account for the extracellular acid enzyme. Phosphorus-depleted cells were able to grow on organic phosphates as the sole source of orthophosphate. Ribose-5-phosphate was the best for cell multiplication, and its utility was shown to be due to the cell's ability to use the ribose as well as the orthophosphatase for cell multiplication.

  3. PTEN inhibitor bisperoxovanadium protects oligodendrocytes and myelin and prevents neuronal atrophy in adult rats following cervical hemicontusive spinal cord injury

    PubMed Central

    Walker, Chandler L.; Xu, Xiao-Ming

    2014-01-01

    Cervical spinal cord injury (SCI) damages axons and motor neurons responsible for ipsilateral forelimb function and causes demyelination and oligodendrocyte death. Inhibition of the phosphatase and tensin homologue, PTEN, promotes neural cell survival, neuroprotection and regeneration in vivo and in vitro. PTEN inhibition can also promote oligodendrocyte-mediated myelination of axons in vitro likely through Akt activation. We recently demonstrated that acute treatment with phosphatase PTEN inhibitor, bisperoxovanadium (bpV)-pic reduced tissue damage, neuron death, and promoted functional recovery after cervical hemi-contusion SCI. Evidence suggests bpV can promote myelin stability; however, bpV effects on myelination and oligodendrocytes in contusive SCI models are unclear. We hypothesized that bpV could increase myelin around the injury site through sparing or remyelination, and that bpV treatment may promote increased numbers of oligodendrocytes. Using histological and immunofluorescence labeling, we found that bpV treatment promoted significant spared white matter (30%; p < 0.01) and Luxol Fast Blue (LFB)+ myelin area rostral (Veh: 0.56 ± 0.01 vs. bpV: 0.64 ± 0.02; p < 0.05) and at the epicenter (Veh: 0.4175 ± 0.03 vs. bpV: 0.5400 ± 0.03; p < 0.05). VLF oligodendrocytes were also significantly greater with bpV therapy (109 ± 5.3 vs. Veh: 77 ± 2.7/mm2; p < 0.01). In addition, bpV increased mean motor neuron soma area versus vehicle-treatment (1.0 ± 0.02 vs. Veh: 0.77 ± 0.02) relative to Sham neuron size. This study provides key insight into additional cell and tissue effects that could contribute to bpV-mediated functional recovery observed after contusive cervical SCI. PMID:24582904

  4. Expression of Phosphatase and Tensin Homologue, phospho-Akt, and p53 in Acral Benign and Malignant Melanocytic Neoplasms (Benign Nevi, Dysplastic Nevi, and Acral Melanomas)

    PubMed Central

    Lyu, So Min; Wu, Ju Yeon; Byun, Ji Yeon; Choi, Hae Young; Park, Sang Hee

    2016-01-01

    Background The role of the phosphatidylinositol-3 kinase signaling pathway in the development of acral melanoma has recently gained evidence. Phosphatase and tensin homologue (PTEN), one of the key molecules in the pathway, acts as a tumor suppressor through either an Akt-dependent or Akt-independent pathway. Akt accelerates degradation of p53. Objective We assessed the expression of PTEN, phospho-Akt (p-Akt), and p53 by immunohistochemistry in benign acral nevi, acral dysplastic nevi, and acral melanomas in the radial growth phase and with a vertical growth component. Methods Ten specimens in each group were included. Paraffin-embedded specimens were immunostained with antibodies for PTEN, p-Akt, and p53. We scored both the staining intensity and the proportion of positive cells. The final score was calculated by multiplying the intensity score by the proportion score. Results All specimens of benign acral nevi except one showed some degree of PTEN-negative cells. The numbers of p-Akt and p53-positive cells were higher in acral dysplastic nevi and melanoma than in benign nevi. P-Akt scores were 1.7, 1.8, 2.6, and 4.4, and p53 scores were 2.0, 2.1, 3.8, and 4.1 in each group. PTEN and p-Akt scores in advanced acral melanoma were higher than in the other neoplasms. Conclusion The expression of PTEN was decreased and the expression of p-Akt was increased in acral melanoma, especially in advanced cases. The PTEN-induced pathway appears to affect the late stage of melanomagenesis. Altered expression of p-Akt is thought to be due to secondary changes following the loss of PTEN. PMID:27746632

  5. Unrestrained mammalian target of rapamycin complexes 1 and 2 increase expression of phosphatase and tensin homolog deleted on chromosome 10 to regulate phosphorylation of Akt kinase.

    PubMed

    Das, Falguni; Ghosh-Choudhury, Nandini; Dey, Nirmalya; Mandal, Chandi Charan; Mahimainathan, Lenin; Kasinath, Balakuntalam S; Abboud, Hanna E; Choudhury, Goutam Ghosh

    2012-02-01

    Tuberous sclerosis complex 2 (TSC2) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) function to block growth factor-induced mammalian target of rapamycin (mTOR) signaling and are mutated in autosomal dominant hamartoma syndromes. mTOR binds to a spectrum of common and different proteins to form TOR complex 1 (TORC1) and TORC2, which regulate cell growth, division, and metabolism. TSC2 deficiency induces constitutive activation of mTOR, leading to a state of insulin resistance due to a negative feedback regulation, resulting in reduced Akt phosphorylation. We have recently described an alternative mechanism showing that in TSC2 deficiency, enhanced PTEN expression contributes to reduced Akt phosphorylation. To explore the mechanism of PTEN regulation, we used rapamycin and constitutively active mTOR to show that TORC1 increases the expression of PTEN mRNA and protein. We found that in TSC2(-/-) mouse embryonic fibroblasts expression of a kinase-dead mutant of mTOR, which inhibits both TORC1 and TORC2, decreases the expression of PTEN via transcriptional mechanism. Furthermore, kinase-dead mTOR increased and decreased phosphorylation of Akt at catalytic loop site Thr-308 and hydrophobic motif site Ser-473, respectively. Moreover, inhibition of deregulated TORC1 in TSC2-null mouse embryonic fibroblasts or in 293 cells by down-regulation of raptor decreased the levels of the transcription factor Hif1α and blocked PTEN expression, resulting in enhanced phosphorylation of Akt at Thr-308 and Ser-473. Finally, knockdown of rictor or mSin1 attenuated the expression of Hif1α, which decreased transcription of PTEN. These results unravel a previously unrecognized cell-autonomous function of TORC1 and TORC2 in the up-regulation of PTEN, which prevents phosphorylation of Akt and may shield against the development of malignancy in TSC patients. PMID:22184110

  6. Networks of protein kinases and phosphatases in the individual phases of contextual fear conditioning in the C57BL/6J mouse.

    PubMed

    Mucic, Goran; Sase, Sunetra; Stork, Oliver; Lubec, Gert; Li, Lin

    2015-03-01

    Although protein kinases and phosphatases have been reported to be involved in fear memory, information about these signalling molecules in the individual phases of contextual fear conditioning (cFC) is limited. C57BL/6J mice were tested in cFC, sacrificed and hippocampi were used for screening of approximately 800 protein kinases and phosphatases by protein microarrays with subsequent Western blot confirmation of threefold higher or lower hippocampal levels as compared to foot shock controls. Immunoblotting of the protein kinases and phosphatases screened out was carried out by Western blotting. A network of protein kinases and phosphatases was generated (STRING 9.1). Animals learned the task in the paradigm and protein kinase and phosphatase levels were determined in the individual phases acquisition, consolidation and retrieval and compared to foot shock controls. Protein kinases discoidin containing receptor 2 (DDR2), mitogen activated protein kinase kinase kinase 7 (TAK1), protein phosphatases dual specificity protein phosphatase (PTEN) and protein phosphatase 2a (PP2A) were modulated in the individual phases of cFC. Phosphatidyl-inositol-3,4,5-triphosphate 3-phosphatase and phosphatidylinositol-3 kinase (PI3K) that is interacting with PTEN were modulated as well. Freezing time was correlating with PP2A levels in the retrieval phase of cFC. The abovementioned protein kinases, phosphatases and inositol-signalling enzymes were not reported so far in cFC and the results are relevant for interpretation of previous and design of future studies in cFC or fear memory. Protein phosphatase PP2A was, however, the only signalling compound tested that was directly linked to retrieval in the cFC. PMID:25461266

  7. First Polish Cowden syndrome patient with confirmed PTEN gene mutation.

    PubMed

    Podralska, Marta; Nowakowska, Dorota; Steffen, Jan; Cichy, Wojciech; Slomski, Ryszard; Plawski, Andrzej

    2010-03-01

    Cowden syndrome is a rare hereditary disease. Incidence of the disease is conditioned by occurrence of mutations in the PTEN gene. The disease has a frequency of 1/120,000 newborn and it predisposes to the occurrence of hamartoma polyps in the gastrointestinal tract, skin tumours, as well as tumours of the breast, ovary and thyroid. Here we describe the case of a Polish patient diagnosed with Cowden syndrome with an identified mutation in the PTEN gene. The disease course of the patient is described and discussed along with other cases of carriers of substitution 68T>A in the PTEN gene.

  8. KRAS and BRAF Mutations and PTEN Expression Do Not Predict Efficacy of Cetuximab-Based Chemoradiotherapy in Locally Advanced Rectal Cancer

    SciTech Connect

    Erben, Philipp; Stroebel, Philipp; Horisberger, Karoline; Popa, Juliana; Bohn, Beatrice; Hanfstein, Benjamin; Kaehler, Georg; Kienle, Peter; Post, Stefan; Wenz, Frederik; Hochhaus, Andreas

    2011-11-15

    Purpose: Mutations in KRAS and BRAF genes as well as the loss of expression of phosphatase and tensin homolog (PTEN) (deleted on chromosome 10) are associated with impaired activity of antibodies directed against epidermal growth factor receptor in patients with metastatic colorectal cancer. The predictive and prognostic value of the KRAS and BRAF point mutations as well as PTEN expression in patients with locally advanced rectal cancer (LARC) treated with cetuximab-based neoadjuvant chemoradiotherapy is unknown. Methods and Materials: We have conducted phase I and II trials of the combination of weekly administration of cetuximab and irinotecan and daily doses of capecitabine in conjunction with radiotherapy (45 Gy plus 5.4 Gy) in patients with LARC (stage uT3/4 or uN+). The status of KRAS and BRAF mutations was determined with direct sequencing, and PTEN expression status was determined with immunohistochemistry testing of diagnostic tumor biopsies. Tumor regression was evaluated by using standardized regression grading, and disease-free survival (DFS) was calculated according to the Kaplan-Meier method. Results: A total of 57 patients were available for analyses. A total of 31.6% of patients carried mutations in the KRAS genes. No BRAF mutations were found, while the loss of PTEN expression was observed in 9.6% of patients. Six patients achieved complete remission, and the 3-year DFS rate was 73%. No correlation was seen between tumor regression or DFS rate and a single marker or a combination of all markers. Conclusions: In the present series, no BRAF mutation was detected. The presence of KRAS mutations and loss of PTEN expression were not associated with impaired response to cetuximab-based chemoradiotherapy and 3-year DFS.

  9. Qualitative and Quantitative In Vitro Analysis of Phosphatidylinositol Phosphatase Substrate Specificity.

    PubMed

    Ip, Laura Ren Huey; Gewinner, Christina Anja

    2016-01-01

    Phosphoinositides compromise a family of eight membrane lipids which play important roles in many cellular signaling pathways. Signaling through phosphoinositides has been shown in a variety of cellular functions such cell proliferation, cell growth, apoptosis, and vesicle trafficking. Phospholipid phosphatases regulate cell signaling by modifying the concentration of phosphoinositides and their dephosphorylated products. To understand the role of individual lipid phosphatases in phosphoinositide turnover and functional signaling, it is crucial to determine the substrate specificity of the lipid phosphatase of interest. In this chapter we describe how the substrate specificity of an individual lipid phosphatase can be qualitatively and quantitatively measured in an in vitro radiometric assay. In addition, we specify the different expression systems and purification methods required to produce the necessary yield and functionality in order to further characterize these enzymes. The outstanding versatility and sensitivity of this assay system are yet unmatched and are therefore currently considered the standard of the field.

  10. PTEN dosage is essential for neurofibroma development and malignant transformation.

    PubMed

    Gregorian, Caroline; Nakashima, Jonathan; Dry, Sarah M; Nghiemphu, P Leia; Smith, Kate Barzan; Ao, Yan; Dang, Julie; Lawson, Gregory; Mellinghoff, Ingo K; Mischel, Paul S; Phelps, Michael; Parada, Luis F; Liu, Xin; Sofroniew, Michael V; Eilber, Fritz C; Wu, Hong

    2009-11-17

    Patients with neurofibromatosis type 1 (NF1) carry approximately a 10% lifetime risk of developing a malignant peripheral nerve sheath tumor (MPNST). Although the molecular mechanisms underlying NF1 to MPNST malignant transformation remain unclear, alterations of both the RAS/RAF/MAPK and PI3K/AKT/mTOR signaling pathways have been implicated. In a series of genetically engineered murine models, we perturbed RAS/RAF/MAPK or/and PTEN/PI3K/AKT pathway, individually or simultaneously, via conditional activation of K-ras oncogene or deletion of Nf1 or Pten tumor suppressor genes. Only K-Ras activation in combination with a single Pten allele deletion led to 100% penetrable development of NF lesions and subsequent progression to MPNST. Importantly, loss or decrease in PTEN expression was found in all murine MPNSTs and a majority of human NF1-associated MPNST lesions, suggesting that PTEN dosage and its controlled signaling pathways are critical for transformation of NFs to MPNST. Using noninvasive in vivo PET-CT imaging, we demonstrated that FDG can be used to identify the malignant transformation in both murine and human MPNSTs. Our data suggest that combined inhibition of RAS/RAF/MAPK and PTEN/PI3K/AKT pathways may be beneficial for patients with MPNST. PMID:19846776

  11. PTEN dosage is essential for neurofibroma development and malignant transformation.

    PubMed

    Gregorian, Caroline; Nakashima, Jonathan; Dry, Sarah M; Nghiemphu, P Leia; Smith, Kate Barzan; Ao, Yan; Dang, Julie; Lawson, Gregory; Mellinghoff, Ingo K; Mischel, Paul S; Phelps, Michael; Parada, Luis F; Liu, Xin; Sofroniew, Michael V; Eilber, Fritz C; Wu, Hong

    2009-11-17

    Patients with neurofibromatosis type 1 (NF1) carry approximately a 10% lifetime risk of developing a malignant peripheral nerve sheath tumor (MPNST). Although the molecular mechanisms underlying NF1 to MPNST malignant transformation remain unclear, alterations of both the RAS/RAF/MAPK and PI3K/AKT/mTOR signaling pathways have been implicated. In a series of genetically engineered murine models, we perturbed RAS/RAF/MAPK or/and PTEN/PI3K/AKT pathway, individually or simultaneously, via conditional activation of K-ras oncogene or deletion of Nf1 or Pten tumor suppressor genes. Only K-Ras activation in combination with a single Pten allele deletion led to 100% penetrable development of NF lesions and subsequent progression to MPNST. Importantly, loss or decrease in PTEN expression was found in all murine MPNSTs and a majority of human NF1-associated MPNST lesions, suggesting that PTEN dosage and its controlled signaling pathways are critical for transformation of NFs to MPNST. Using noninvasive in vivo PET-CT imaging, we demonstrated that FDG can be used to identify the malignant transformation in both murine and human MPNSTs. Our data suggest that combined inhibition of RAS/RAF/MAPK and PTEN/PI3K/AKT pathways may be beneficial for patients with MPNST.

  12. Subtle variations in Pten dose determine cancer susceptibility

    PubMed Central

    Alimonti, Andrea; Carracedo, Arkaitz; Clohessy, John G; Trotman, Lloyd C; Nardella, Caterina; Egia, Ainara; Salmena, Leonardo; Sampieri, Katia; Haveman, William J; Brogi, Edi; Richardson, Andrea L; Zhang, Jiangwen; Pandolfi, Pier Paolo

    2010-01-01

    Cancer susceptibility has been attributed to at least one heterozygous genetic alteration in a tumor suppressor gene (TSG)1. It has been hypothesized that subtle variations in TSG expression can promote cancer development2,3. However, this hypothesis has not yet been definitively supported in vivo. PTEN is a TSG frequently lost in human cancer and mutated in inherited cancer-predisposition syndromes4. Here, we analyze Pten hypermorphic mice (Ptenhy/+), expressing 80% normal levels of Pten. Ptenhy/+ mice develop a spectrum of tumors, with breast tumors occurring at the highest penetrance. All breast tumors analyzed here retained two intact copies of Pten and maintained Pten levels above heterozygosis. Notably, subtle downregulation of Pten altered the steady-state biology of the mammary tissues and the expression profiles of genes involved in cancer cell proliferation. We present an alterative working model for cancer development in which subtle reductions in the dose of TSGs predispose to tumorigenesis in a tissue-specific manner. PMID:20400965

  13. miR-148a-3p overexpression contributes to glomerular cell proliferation by targeting PTEN in lupus nephritis.

    PubMed

    Qingjuan, Liu; Xiaojuan, Feng; Wei, Zhang; Chao, Wu; Pengpeng, Kang; Hongbo, Li; Sanbing, Zhang; Jun, Hao; Min, Yang; Shuxia, Liu

    2016-03-15

    The objective of this study was to investigate the role of miR-148a-3p in lupus nephritis (LN) based on data from previous studies and a microRNA assay. We evaluated the miR-148a-3p expression level in LN renal tissues and blood serum to determine its clinicopathological significance and effect on glomerular cell proliferation. Then, we collected renal glomeruli from LN mice and determined the miR-148a-3p, proliferating cell nuclear antigen (PCNA), and PCNA/Thy1 expression. We performed functional analyses of miR-148a-3p in vitro and in vivo. We also investigated the target gene of miR-148a-3p in LN. The results showed that miR-148a-3p expression levels were significantly higher not only in glomeruli but also in the blood serum during LN and increased in the glomeruli of LN mice and that at the same time there was positive correlation between miR-148a-3p and PCNA expression of glomruli. Overexpression of miR-148a-3p accelerated cell proliferation and PCNA expression, while a miR-148a-3p inhibitor inhibited cell proliferation via the Akt/cyclin D1 pathway. Furthermore, miR-148a-3p overexpression reduced the phosphatase and tensin homology deleted on chromosome ten (PTEN) expression level, while miR-148a-3p silencing increased its expression in high-mobility group box 1 (HMGB1)-induced mouse mesangial cells (MMCs). Luciferase assays demonstrated that miR-148a-3p could directly bind to the PTEN 3'-UTR. PTEN overexpression inhibited MMC proliferation considerably, resembling the results observed during miR-148a-3p inhibition. Reducing miR-148a-3p expression upregulated PTEN in the glomeruli and improved renal function in LN mice. Thus miR-148a-3p may promote proliferation and contribute to LN progression by targeting PTEN.

  14. GRP78 as a regulator of liver steatosis and cancer progression mediated by loss of the tumor suppressor PTEN.

    PubMed

    Chen, W-T; Zhu, G; Pfaffenbach, K; Kanel, G; Stiles, B; Lee, A S

    2014-10-16

    Glucose-regulated protein 78 (GRP78), a molecular chaperone widely elevated in human cancers, is critical for endoplasmic reticulum (ER) protein folding, stress signaling and PI3K/AKT activation. Genetic knockout models of GRP78 revealed that GRP78 maintains homeostasis of metabolic organs, including liver, pancreas and adipose tissues. Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) are the most common liver cancers. There is a lack of effective therapeutics for HCC and CC, highlighting the need to further understand liver tumorigenic mechanisms. PTEN (phosphatase and tenson homolog deleted on chromosome 10), a tumor suppressor that antagonizes the PI3K/AKT pathway, is inactivated in a wide range of tumors, including 40-50% of human liver cancers. To elucidate the role of GRP78 in liver cancer, we created a mouse model with biallelic liver-specific deletion of Pten and Grp78 mediated by Albumin-Cre-recombinase (cP(f/f)78(f/f)). Interestingly, in contrast to PTEN, deletion of GRP78 was progressive but incomplete. At 3 months, cP(f/f)78(f/f) livers showed hepatomegaly, activation of lipogenic genes, exacerbated steatosis and liver injury, implying that GRP78 protects the liver against PTEN-null-mediated pathogenesis. Furthermore, in response to liver injury, we observed increased proliferation and expansion of bile duct and liver progenitor cells in cP(f/f)78(f/f) livers. Strikingly, bile duct cells in cP(f/f)78(f/f) livers maintained wild-type (WT) GRP78 level, whereas adjacent areas showed GRP78 reduction. Analysis of signaling pathways revealed selective JNK activation, β-catenin downregulation, along with PDGFRα upregulation, which was unique to cP(f/f)78(f/f) livers at 6 months. Development of both HCC and CC was accelerated and was evident in cP(f/f)78(f/f) livers at 8-9 months, coinciding with intense GRP78 expression in the cancer lesions, and GRP78 expression in adjacent normal areas reverted back to the WT level. In contrast, c78(f/f) livers

  15. Regulation of synthase phosphatase and phosphorylase phosphatase in rat liver.

    PubMed

    Tan, A W; Nuttall, F Q

    1976-08-12

    Using substrates purified from liver, the apparent Km values of synthase phosphatase ([UDPglucose--glycogen glucosyltransferase-D]phosphohydrolase, EC 3.1.3.42) and phosphorylase phosphatase (phosphorylase a phosphohydrolase, EC 3.1.3.17) were found to be 0.7 and 60 units/ml respectively. The maximal velocity of phosphorylase phosphatase was more than a 100 times that of synthase phosphatase. In adrenalectomized, fasted animals there was a complete loss of synthase phosphatase but only a slight decrease in phosphorylase phosphatase when activity was measured using endogenous substrates in a concentrated liver extract. When assayed under optimal conditions with purified substrates, both activities were present but had decreased to very low levels. Mixing experiments indicated that synthase D present in the extract of adrenalectomized fasted animals was altered such that it was no longer a substrate for synthase phosphatase from normal rats. Phosphorylase a substrate on the other hand was unaltered and readily converted. When glucose was given in vivo, no change in percent of synthase in the I form was seen in adrenalectomized rats but the percent of phosphorylase in the a form was reduced. Precipitation of protein from an extract of normal fed rats with ethanol produced a large activation of phosphorylase phosphatase activity with no corresponding increase in synthase phosphatase activity. Despite the low phosphorylase phosphatase present in extracts of adrenalectomized fasted animals, ethanol precipitation increased activity to the same high level as obtained in the normal fed rats. Synthase phosphatase and phosphorylase phosphatase activities were also decreased in normal fasted, diabetic fed and fasted, and adrenalectomized fed rats. Both enzymes recovered in the same manner temporally after oral glucose administration to adrenalectomized, fasted rats. These results suggest an integrated regulatory mechanism for the two phosphatase.

  16. Screening for germline phosphatase and tensin homolog-mutations in suspected Cowden syndrome and Cowden syndrome-like families among uterine cancer patients

    PubMed Central

    TZORTZATOS, GERASIMOS; ARAVIDIS, CHRISTOS; LINDBLOM, ANNIKA; MINTS, MIRIAM; THAM, EMMA

    2015-01-01

    Cowden syndrome (CS) is an autosomal dominant disorder characterized by multiple hamartomas in the breast, thyroid and endometrium, with a prevalence of 1 per 250,000. Females with CS have a 21–28% lifetime risk of developing uterine cancer. Germline mutations in the phosphatase and tensin homolog (PTEN) gene, a tumor suppressor gene, are responsible for 30–80% of CS cases. PTEN is a nine-exon gene, located on chromosome 10q23.3, which encodes the 403 amino acid PTEN protein. It negatively regulates the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway, affecting various cellular processes and signaling pathways. The present study examined whether PTEN mutations are present in CS-like families with uterine cancer (UC). UC patients underwent surgery at Karolinska University Hospital, Stockholm, Sweden (2008–2012). Pedigrees were analyzed and 54 unrelated CS-like families were identified. CS-like families were defined as having at least one occurrence of uterine cancer and one of breast cancer, as well as at least one additional Cowden-associated tumor (uterine, breast, thyroid, colon or kidney cancer) in the same individual or in first-degree relatives. Genomic DNA was amplified using polymerase chain reaction, and DNA sequencing analysis of all nine exons of the PTEN gene was conducted. No germline PTEN mutations or polymorphisms were identified. Germline PTEN mutations are rare in CS-like families with uterine cancer, therefore, genetic screening must be restricted to patients that meet the strict National Comprehensive Cancer Network criteria. Gynecologists must be aware of the CS criteria and identify potential cases of CS in females where uterine cancer is the sentinel cancer. PMID:25789042

  17. Nrf2 Enhances Cholangiocyte Expansion in Pten-Deficient Livers

    PubMed Central

    Taguchi, Keiko; Hirano, Ikuo; Itoh, Tohru; Tanaka, Minoru; Miyajima, Atsushi; Suzuki, Akira

    2014-01-01

    Keap1-Nrf2 system plays a central role in the stress response. While Keap1 ubiquitinates Nrf2 for degradation under unstressed conditions, this Keap1 activity is abrogated in response to oxidative or electrophilic stresses, leading to Nrf2 stabilization and coordinated activation of cytoprotective genes. We recently found that nuclear accumulation of Nrf2 is significantly increased by simultaneous deletion of Pten and Keap1, resulting in the stronger activation of Nrf2 target genes. To clarify the impact of the cross talk between the Keap1-Nrf2 and Pten–phosphatidylinositide 3-kinase–Akt pathways on the liver pathophysiology, in this study we have conducted closer analysis of liver-specific Pten::Keap1 double-mutant mice (Pten::Keap1-Alb mice). The Pten::Keap1-Alb mice were lethal by 1 month after birth and displayed severe hepatomegaly with abnormal expansion of ductal structures comprising cholangiocytes in a Nrf2-dependent manner. Long-term observation of Pten::Keap1-Alb::Nrf2+/− mice revealed that the Nrf2-heterozygous mice survived beyond 1 month but developed polycystic liver fibrosis by 6 months. Gsk3 directing the Keap1-independent degradation of Nrf2 was heavily phosphorylated and consequently inactivated by the double deletion of Pten and Keap1 genes. Thus, liver-specific disruption of Keap1 and Pten augments Nrf2 activity through inactivation of Keap1-dependent and -independent degradation of Nrf2 and establishes the Nrf2-dependent molecular network promoting the hepatomegaly and cholangiocyte expansion. PMID:24379438

  18. PTEN regulates EG5 to control spindle architecture and chromosome congression during mitosis.

    PubMed

    He, Jinxue; Zhang, Zhong; Ouyang, Meng; Yang, Fan; Hao, Hongbo; Lamb, Kristy L; Yang, Jingyi; Yin, Yuxin; Shen, Wen H

    2016-01-01

    Architectural integrity of the mitotic spindle is required for efficient chromosome congression and accurate chromosome segregation to ensure mitotic fidelity. Tumour suppressor PTEN has multiple functions in maintaining genome stability. Here we report an essential role of PTEN in mitosis through regulation of the mitotic kinesin motor EG5 for proper spindle architecture and chromosome congression. PTEN depletion results in chromosome misalignment in metaphase, often leading to catastrophic mitotic failure. In addition, metaphase cells lacking PTEN exhibit defects of spindle geometry, manifested prominently by shorter spindles. PTEN is associated and co-localized with EG5 during mitosis. PTEN deficiency induces aberrant EG5 phosphorylation and abrogates EG5 recruitment to the mitotic spindle apparatus, leading to spindle disorganization. These data demonstrate the functional interplay between PTEN and EG5 in controlling mitotic spindle structure and chromosome behaviour during mitosis. We propose that PTEN functions to equilibrate mitotic phosphorylation for proper spindle formation and faithful genomic transmission. PMID:27492783

  19. PTEN regulates EG5 to control spindle architecture and chromosome congression during mitosis

    PubMed Central

    He, Jinxue; Zhang, Zhong; Ouyang, Meng; Yang, Fan; Hao, Hongbo; Lamb, Kristy L.; Yang, Jingyi; Yin, Yuxin; Shen, Wen H.

    2016-01-01

    Architectural integrity of the mitotic spindle is required for efficient chromosome congression and accurate chromosome segregation to ensure mitotic fidelity. Tumour suppressor PTEN has multiple functions in maintaining genome stability. Here we report an essential role of PTEN in mitosis through regulation of the mitotic kinesin motor EG5 for proper spindle architecture and chromosome congression. PTEN depletion results in chromosome misalignment in metaphase, often leading to catastrophic mitotic failure. In addition, metaphase cells lacking PTEN exhibit defects of spindle geometry, manifested prominently by shorter spindles. PTEN is associated and co-localized with EG5 during mitosis. PTEN deficiency induces aberrant EG5 phosphorylation and abrogates EG5 recruitment to the mitotic spindle apparatus, leading to spindle disorganization. These data demonstrate the functional interplay between PTEN and EG5 in controlling mitotic spindle structure and chromosome behaviour during mitosis. We propose that PTEN functions to equilibrate mitotic phosphorylation for proper spindle formation and faithful genomic transmission. PMID:27492783

  20. PTEN regulates EG5 to control spindle architecture and chromosome congression during mitosis.

    PubMed

    He, Jinxue; Zhang, Zhong; Ouyang, Meng; Yang, Fan; Hao, Hongbo; Lamb, Kristy L; Yang, Jingyi; Yin, Yuxin; Shen, Wen H

    2016-08-05

    Architectural integrity of the mitotic spindle is required for efficient chromosome congression and accurate chromosome segregation to ensure mitotic fidelity. Tumour suppressor PTEN has multiple functions in maintaining genome stability. Here we report an essential role of PTEN in mitosis through regulation of the mitotic kinesin motor EG5 for proper spindle architecture and chromosome congression. PTEN depletion results in chromosome misalignment in metaphase, often leading to catastrophic mitotic failure. In addition, metaphase cells lacking PTEN exhibit defects of spindle geometry, manifested prominently by shorter spindles. PTEN is associated and co-localized with EG5 during mitosis. PTEN deficiency induces aberrant EG5 phosphorylation and abrogates EG5 recruitment to the mitotic spindle apparatus, leading to spindle disorganization. These data demonstrate the functional interplay between PTEN and EG5 in controlling mitotic spindle structure and chromosome behaviour during mitosis. We propose that PTEN functions to equilibrate mitotic phosphorylation for proper spindle formation and faithful genomic transmission.

  1. Identification of PTEN mutations in metastatic melanoma specimens

    PubMed Central

    Celebi, J. T.; Shendrik, I.; Silvers, D.; Peacocke, M.

    2000-01-01

    CONTEXT—PTEN, a tumour suppressor gene located on chromosome 10q23, develops somatic mutations in various tumours and tumour cell lines including brain, endometrium, prostate, breast, kidney, thyroid, liver, and melanoma.
OBJECTIVES—To investigate the mutational profile of this gene further, as well as its role in tumour progression in melanoma.
DESIGN, SETTINGS—We examined 21 metastatic melanoma samples for 10q23 allelic losses and PTEN sequence alterations. Additionally, we screened these samples for mutations in CDKN2A, a gene in which alterations are well documented in primary melanoma as well as in the germline of familial melanoma.
RESULTS—Loss of heterozygosity (LOH) at 10q23 was observed in 33% (7/21) of the samples tested. We identified four sequence alterations in PTEN (19%) and two in CDKN2A (9.5%). Of interest, only one case showed mutations in both genes.
CONCLUSIONS—These data support the notion that PTEN alterations occur in some metastatic melanomas, and that mutation of this gene plays a role in the progression of some forms of melanoma.


Keywords: PTEN; CDKN2A; melanoma PMID:10978354

  2. A novel pharmacological strategy by PTEN inhibition for improving metabolic resuscitation and survival after mouse cardiac arrest.

    PubMed

    Li, Jing; Wang, Huashan; Zhong, Qiang; Zhu, Xiangdong; Chen, Sy-Jou; Qian, Yuanyu; Costakis, Jim; Bunney, Gabrielle; Beiser, David G; Leff, Alan R; Lewandowski, E Douglas; ÓDonnell, J Michael; Vanden Hoek, Terry L

    2015-06-01

    Sudden cardiac arrest (SCA) is a leading cause of death in the United States. Despite return of spontaneous circulation, patients die due to post-SCA syndrome that includes myocardial dysfunction, brain injury, impaired metabolism, and inflammation. No medications improve SCA survival. Our prior work suggests that optimal Akt activation is critical for cooling protection and SCA recovery. Here, we investigate a small inhibitor of PTEN, an Akt-related phosphatase present in heart and brain, as a potential therapy in improving cardiac and neurological recovery after SCA. Anesthetized adult female wild-type C57BL/6 mice were randomized to pretreatment of VO-OHpic (VO) 30 min before SCA or vehicle control. Mice underwent 8 min of KCl-induced asystolic arrest followed by CPR. Resuscitated animals were hemodynamically monitored for 2 h and observed for 72 h. Outcomes included heart pressure-volume loops, energetics (phosphocreatine and ATP from (31)P NMR), protein phosphorylation of Akt, GSK3β, pyruvate dehydrogenase (PDH) and phospholamban, circulating inflammatory cytokines, plasma lactate, and glucose as measures of systemic metabolic recovery. VO reduced deterioration of left ventricular maximum pressure, maximum rate of change in the left ventricular pressure, and Petco2 and improved 72 h neurological intact survival (50% vs. 10%; P < 0.05). It reduced plasma lactate, glucose, IL-1β, and Pre-B cell colony enhancing factor, while increasing IL-10. VO increased phosphorylation of Akt and GSK3β in both heart and brain, and cardiac phospholamban phosphorylation while reducing p-PDH. Moreover, VO improved cardiac bioenergetic recovery. We concluded that pharmacologic PTEN inhibition enhances Akt activation, improving metabolic, cardiovascular, and neurologic recovery with increased survival after SCA. PTEN inhibitors may be a novel pharmacologic strategy for treating SCA. PMID:25795713

  3. A novel pharmacological strategy by PTEN inhibition for improving metabolic resuscitation and survival after mouse cardiac arrest

    PubMed Central

    Li, Jing; Wang, Huashan; Zhong, Qiang; Zhu, Xiangdong; Chen, Sy-Jou; Qian, Yuanyu; Costakis, Jim; Bunney, Gabrielle; Beiser, David G.; Leff, Alan R.; Lewandowski, E. Douglas; ÓDonnell, J. Michael

    2015-01-01

    Sudden cardiac arrest (SCA) is a leading cause of death in the United States. Despite return of spontaneous circulation, patients die due to post-SCA syndrome that includes myocardial dysfunction, brain injury, impaired metabolism, and inflammation. No medications improve SCA survival. Our prior work suggests that optimal Akt activation is critical for cooling protection and SCA recovery. Here, we investigate a small inhibitor of PTEN, an Akt-related phosphatase present in heart and brain, as a potential therapy in improving cardiac and neurological recovery after SCA. Anesthetized adult female wild-type C57BL/6 mice were randomized to pretreatment of VO-OHpic (VO) 30 min before SCA or vehicle control. Mice underwent 8 min of KCl-induced asystolic arrest followed by CPR. Resuscitated animals were hemodynamically monitored for 2 h and observed for 72 h. Outcomes included heart pressure-volume loops, energetics (phosphocreatine and ATP from 31P NMR), protein phosphorylation of Akt, GSK3β, pyruvate dehydrogenase (PDH) and phospholamban, circulating inflammatory cytokines, plasma lactate, and glucose as measures of systemic metabolic recovery. VO reduced deterioration of left ventricular maximum pressure, maximum rate of change in the left ventricular pressure, and Petco2 and improved 72 h neurological intact survival (50% vs. 10%; P < 0.05). It reduced plasma lactate, glucose, IL-1β, and Pre-B cell colony enhancing factor, while increasing IL-10. VO increased phosphorylation of Akt and GSK3β in both heart and brain, and cardiac phospholamban phosphorylation while reducing p-PDH. Moreover, VO improved cardiac bioenergetic recovery. We concluded that pharmacologic PTEN inhibition enhances Akt activation, improving metabolic, cardiovascular, and neurologic recovery with increased survival after SCA. PTEN inhibitors may be a novel pharmacologic strategy for treating SCA. PMID:25795713

  4. Mechanisms underlying PTEN regulation of vascular endothelial growth factor and angiogenesis.

    PubMed

    Gomez-Manzano, Candelaria; Fueyo, Juan; Jiang, Hong; Glass, Tricia L; Lee, Ho-Young; Hu, Min; Liu, Juinn-Lin; Jasti, Sushma L; Liu, Ta-Jen; Conrad, Charles A; Yung, W K Alfred

    2003-01-01

    Inactivation of the tumor suppressor gene PTEN and overexpression of VEGF are two of the most common events observed in high-grade malignant gliomas. The purpose of this study was to determine whether PTEN controls VEGF expression in gliomas under normoxic conditions. Transfer of PTEN to human glioma cells resulted in the transduction of a functional PTEN protein as evidenced by the upregulation of p27 and modification of the phosphorylation status of Akt. Under normoxic conditions, enzyme-linked immunosorbent assay and Northern blot analyses showed downregulation of VEGF in PTEN-treated cells. Moreover, conditioned media from PTEN-treated glioma cells significantly diminished the ability of endothelial cells to grow and migrate. Western blot assays demonstrated that, in a normoxic environment, PTEN downregulates HIF-1 alpha. Finally, promoter activity assays showed that the VEGF promoter region containing the HIF-1alpha binding site is necessary and sufficient for PTEN-mediated downregulation of VEGF. Experiments with PI3-K inhibitors and kinase assays suggested that PI3-K is mediating the effect of PTEN on VEGF, and not the p42/p48 or p38 MAP kinases. These results indicate that restoration of PTEN function in gliomas may induce therapeutic effect by downregulating VEGF. Furthermore, this close functional relationship between PTEN and VEGF suggests that a better understanding of the transduction signal regulated by PTEN might enhance the knowledge of the cause and physiology of vascular and inflammatory diseases.

  5. Anti-angiogenic action of PPARγ ligand in human umbilical vein endothelial cells is mediated by PTEN upregulation and VEGFR-2 downregulation.

    PubMed

    Kim, Ki Young; Ahn, Jin Hee; Cheon, Hyae Gyeong

    2011-12-01

    Peroxisome proliferator-activated receptor γ (PPARγ) activation has anti-angiogenic and apoptotic effects in endothelial cells. Here, we investigated the mechanisms of the anti-angiogenic action of a novel PPARγ ligand, KR-62980. KR-62980 inhibited in vitro basal tube formation and in vivo neovascularization in mice induced by Matrigel containing vascular endothelial growth factor (VEGF(165), 5 ng/ml). VEGF(165)-induced cell proliferation and chemotactic migration in human umbilical vein endothelial cells (HUVECs) were also suppressed by KR-62980, in a mechanism accompanied by apoptotic cell death. KR-62980 downregulated the VEGF(165)-induced VEGFR-2 expression but increased the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression in parallel with reduced phosphorylation of extracellular signal-related kinase 1/2 (ERK1/2), PI3K p85α, and p38 MAPK. The knockdown of PTEN expression abolished KR-62980-suppressed cell proliferation and angiogenesis. All of the effects of KR-62980 disappeared with pretreatment of bisphenol A diaglycidyl ether (BADGE), a PPARγ antagonist. In summary, KR-62980 inhibited VEGF(165)-induced angiogenesis in HUVECs by PPARγ-mediated dual mechanisms: VEGFR-2 downregulation and PTEN upregulation.

  6. Up-regulation of miR-26a promotes neurite outgrowth and ameliorates apoptosis by inhibiting PTEN in bupivacaine injured mouse dorsal root ganglia.

    PubMed

    Cui, Changlei; Xu, Gong; Qiu, Jinpeng; Fan, Xiushuang

    2015-08-01

    Local anesthetic of bupivacaine may inhibit neurite outgrowth and induce apoptosis in mouse dorsal root ganglia (DRG) neurons. In this work, we intended to investigate the functional role of microRNA 26a (miR-26a) in regulating bupivacaine-induced nerve injury in DRG neurons. DRG neurons were extracted from C57BL/6 mice and cultured in vitro. Bupivacaine was applied in vitro and it induced apoptosis, inhibited neurite growth, and significantly down-regulated miR-26a gene in DRG neurons. MiR-26a mimic was then used to up-regulate miR-26a expression in DRG neurons. We found that miR-26a up-regulation promoted neurite outgrowth and reduced apoptosis in bupivacaine-injured DRG neurons. Luciferase assay and Western blot confirmed that Phosphatase and tensin homolog (PTEN) was down-stream target of miR-26a in DRG neurons. Ectopic PTEN up-regulation was then able to reverse the protective effect of miR-26a overexpression on bupivacaine-induced nerve injury in DRG neurons. Overall, this work demonstrated that miR-26a had a functional role in regulating bupivacaine-induced nerve injury in DRG neurons. Up-regulating miR-26a to suppress PTEN signaling pathway may be an effective method to protect local anesthetic-induced nerve injury in spinal cord.

  7. Anti-cancer effect of ursolic acid activates apoptosis through ROCK/PTEN mediated mitochondrial translocation of cofilin-1 in prostate cancer

    PubMed Central

    Gai, Wen-Tao; Yu, Da-Peng; Wang, Xin-Sheng; Wang, Pei-Tao

    2016-01-01

    Ursolic acid is a type of pentacyclic triterpene compound with multiple pharmacological activities including cancer resistance, protection from liver injury, antisepsis, anti-inflammation and antiviral activity. The present study aimed to investigate the anticancer effect of ursolic acid. Ursolic acid activates cell apoptosis and its pro-apoptotic mechanism remains to be fully elucidated. Cell Counting kit-8 assays, flow cytometric analysis and analysis of caspase-3 and caspase-9 activity were used to estimate the anticancer effect of ursolic acid on DU145 prostate cancer cells. The protein expression of cytochrome c, rho-associated protein kinase (ROCK), phosphatase and tensin homolog (PTEN) and cofilin-1 were examined using western blot analysis. In the present study, ursolic acid significantly suppressed cell growth and induced apoptosis, as well as increasing caspase-3 and caspase-9 activities of DU145 cells. Furthermore, cytoplasmic and mitochondrial cytochrome c protein expression was significantly activated and suppressed, respectively, by ursolic acid. Ursolic acid significantly suppressed the ROCK/PTEN signaling pathway and inhibited cofilin-1 protein expression in DU145 cells. The results of the present study indicate that the anticancer effect of ursolic acid activates cell apoptosis through ROCK/PTEN mediated mitochondrial translocation of cofilin-1 in prostate cancer.

  8. Tanshinone IIA inhibits apoptosis in the myocardium by inducing microRNA-152-3p expression and thereby downregulating PTEN

    PubMed Central

    Zhang, Zhen; Li, Yumei; Sheng, Chuqiao; Yang, Chunfeng; Chen, Liping; Sun, Jinghui

    2016-01-01

    Progressive loss of cardiac myocytes through apoptosis contributes to heart failure (HF). In this study, we tested whether tanshinone IIA, one of the most abundant constituents of the root of Salvia miltiorrhiza, protects rat myocardium-derived H9C2 cells against apoptosis. Treatment of H9C2 cells with tanshinone IIA inhibited angiotensin II-induced apoptosis by downregulating the expression of PTEN (phosphatase and tensin homolog), a tumor suppressor that plays a critical role in apoptosis. Furthermore, tanshinone IIA was found to inhibit PTEN expression by upregulating the microRNA miR-152-3p, a potential PTEN regulator that is highly conserved in both rat and human. Notably, the antiapoptotic effect of tanshinone IIA was partially reversed when H9C2 cells were transfected with an inhibitor of miR-152-3p. Collectively, our findings reveal a previously unrecognized mechanism underlying the cardioprotective role of tanshinone IIA, and further suggest that tanshinone IIA could represent a promising drug candidate for HF therapy. PMID:27508033

  9. Mitochondria-related miR-141-3p contributes to mitochondrial dysfunction in HFD-induced obesity by inhibiting PTEN.

    PubMed

    Ji, Juan; Qin, Yufeng; Ren, Jing; Lu, Chuncheng; Wang, Rong; Dai, Xiuliang; Zhou, Ran; Huang, Zhenyao; Xu, Miaofei; Chen, Minjian; Wu, Wei; Song, Ling; Shen, Hongbing; Hu, Zhibin; Miao, Dengshun; Xia, Yankai; Wang, Xinru

    2015-11-09

    Mitochondria-related microRNAs (miRNAs) have recently emerged as key regulators of cell metabolism and can modulate mitochondrial fusion and division. In order to investigate the roles of mitochondria-related miRNAs played in obesity, we conducted comprehensive molecular analysis in vitro and in vivo. Based on high-fat-diet (HFD) induced obese mice, we found that hepatic mitochondrial function was markedly altered. Subsequently, we evaluated the expression levels of selected mitochondria-related miRNAs and found that miR-141-3p was up-regulated strikingly in HFD mice. To further verify the role of miR-141-3p in obesity, we carried out gain-and-loss-of-function study in human HepG2 cells. We found that miR-141-3p could modulate ATP production and induce oxidative stress. Through luciferase report gene assay, we identified that phosphatase and tensin homolog (PTEN) was a target of miR-141-3p. Inhibiting PTEN could alter the mitochondrial function, too. Our study suggested that mitochondria-related miR-141-3p induced mitochondrial dysfunction by inhibiting PTEN.

  10. Resveratrol induces cell cycle arrest in human gastric cancer MGC803 cells via the PTEN-regulated PI3K/Akt signaling pathway.

    PubMed

    Jing, Xiaoping; Cheng, Weiwei; Wang, Shiying; Li, Pin; He, Li

    2016-01-01

    Resveratrol is a polyphenolic compound that is extracted from Polygonum cuspidatum and is used in traditional Chinese medicine. Previous data have shown that resveratrol inhibits the growth of human gastric cancer. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and trypan blue assays showed that resveratrol significantly decreased the survival rate of MGC803 cells in a concentration- and time-dependent manner. Our flow cytometric analysis showed that resveratrol treatment arrested the cells at the G0/G1 phase of the cell cycle. Furthermore, western blotting demonstrated that resveratrol decreased the protein expression of phospho-glycogen synthase kinase 3β (p-GSK3β), cyclin D1, phospho-phosphatase and tensin homologue (p-PTEN), phospho-phosphatidylinositol 3'-OH kinase (p-PI3K), and phospho-protein kinase B (p-PKB/Akt). We also found that resveratrol inhibited the progression of the cell cycle in MGC803 cells by repressing p-PI3K and p-Akt expression. Meanwhile, resveratrol did not decrease the phosphorylation level of Akt when the PTEN gene expression was knocked down by an siRNA in the MGC803 cells. Taken together, these results suggest that resveratrol induced cell cycle arrest in human gastric cancer MGC803 cells by regulating the PTEN/PI3K/Akt signaling pathway.

  11. Anti-cancer effect of ursolic acid activates apoptosis through ROCK/PTEN mediated mitochondrial translocation of cofilin-1 in prostate cancer

    PubMed Central

    Gai, Wen-Tao; Yu, Da-Peng; Wang, Xin-Sheng; Wang, Pei-Tao

    2016-01-01

    Ursolic acid is a type of pentacyclic triterpene compound with multiple pharmacological activities including cancer resistance, protection from liver injury, antisepsis, anti-inflammation and antiviral activity. The present study aimed to investigate the anticancer effect of ursolic acid. Ursolic acid activates cell apoptosis and its pro-apoptotic mechanism remains to be fully elucidated. Cell Counting kit-8 assays, flow cytometric analysis and analysis of caspase-3 and caspase-9 activity were used to estimate the anticancer effect of ursolic acid on DU145 prostate cancer cells. The protein expression of cytochrome c, rho-associated protein kinase (ROCK), phosphatase and tensin homolog (PTEN) and cofilin-1 were examined using western blot analysis. In the present study, ursolic acid significantly suppressed cell growth and induced apoptosis, as well as increasing caspase-3 and caspase-9 activities of DU145 cells. Furthermore, cytoplasmic and mitochondrial cytochrome c protein expression was significantly activated and suppressed, respectively, by ursolic acid. Ursolic acid significantly suppressed the ROCK/PTEN signaling pathway and inhibited cofilin-1 protein expression in DU145 cells. The results of the present study indicate that the anticancer effect of ursolic acid activates cell apoptosis through ROCK/PTEN mediated mitochondrial translocation of cofilin-1 in prostate cancer. PMID:27698874

  12. Resveratrol induces cell cycle arrest in human gastric cancer MGC803 cells via the PTEN-regulated PI3K/Akt signaling pathway.

    PubMed

    Jing, Xiaoping; Cheng, Weiwei; Wang, Shiying; Li, Pin; He, Li

    2016-01-01

    Resveratrol is a polyphenolic compound that is extracted from Polygonum cuspidatum and is used in traditional Chinese medicine. Previous data have shown that resveratrol inhibits the growth of human gastric cancer. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and trypan blue assays showed that resveratrol significantly decreased the survival rate of MGC803 cells in a concentration- and time-dependent manner. Our flow cytometric analysis showed that resveratrol treatment arrested the cells at the G0/G1 phase of the cell cycle. Furthermore, western blotting demonstrated that resveratrol decreased the protein expression of phospho-glycogen synthase kinase 3β (p-GSK3β), cyclin D1, phospho-phosphatase and tensin homologue (p-PTEN), phospho-phosphatidylinositol 3'-OH kinase (p-PI3K), and phospho-protein kinase B (p-PKB/Akt). We also found that resveratrol inhibited the progression of the cell cycle in MGC803 cells by repressing p-PI3K and p-Akt expression. Meanwhile, resveratrol did not decrease the phosphorylation level of Akt when the PTEN gene expression was knocked down by an siRNA in the MGC803 cells. Taken together, these results suggest that resveratrol induced cell cycle arrest in human gastric cancer MGC803 cells by regulating the PTEN/PI3K/Akt signaling pathway. PMID:26530632

  13. Tanshinone IIA inhibits apoptosis in the myocardium by inducing microRNA-152-3p expression and thereby downregulating PTEN.

    PubMed

    Zhang, Zhen; Li, Yumei; Sheng, Chuqiao; Yang, Chunfeng; Chen, Liping; Sun, Jinghui

    2016-01-01

    Progressive loss of cardiac myocytes through apoptosis contributes to heart failure (HF). In this study, we tested whether tanshinone IIA, one of the most abundant constituents of the root of Salvia miltiorrhiza, protects rat myocardium-derived H9C2 cells against apoptosis. Treatment of H9C2 cells with tanshinone IIA inhibited angiotensin II-induced apoptosis by downregulating the expression of PTEN (phosphatase and tensin homolog), a tumor suppressor that plays a critical role in apoptosis. Furthermore, tanshinone IIA was found to inhibit PTEN expression by upregulating the microRNA miR-152-3p, a potential PTEN regulator that is highly conserved in both rat and human. Notably, the antiapoptotic effect of tanshinone IIA was partially reversed when H9C2 cells were transfected with an inhibitor of miR-152-3p. Collectively, our findings reveal a previously unrecognized mechanism underlying the cardioprotective role of tanshinone IIA, and further suggest that tanshinone IIA could represent a promising drug candidate for HF therapy. PMID:27508033

  14. MiR-26a enhances metastasis potential of lung cancer cells via AKT pathway by targeting PTEN.

    PubMed

    Liu, Boning; Wu, Xiang; Liu, Bin; Wang, Changli; Liu, Yunde; Zhou, Qinghua; Xu, Ke

    2012-11-01

    Lung cancer is the leading cause of cancer related death, 90% of lung cancer patients die of metastasis. Many microRNAs (miRNAs) are deregulated in cancer. They are involved in tumorigenesis and function as oncogenes or tumor suppressor genes. Recent studies show that miRNAs may be responsible for tumor metastasis. Several functional studies show that miR-26a plays an important role in carcinogenesis; however, none of these studies is related to tumor metastasis. In the present study, we investigated the effect of miR-26a on metastasis potential of lung cancer cells. Our data showed that miR-26a expression level was higher in lymph node metastasis tumor tissues than in primary tumor tissues. Ectopic expression of miR-26a dramatically enhanced lung cancer cell migration and invasion abilities. Metastasis-related genes matrix metallopeptidase 2 (MMP-2), vascular endothelial growth factor (VEGF), Twist and β-catenin were upregulated. Phosphatase and tensin homolog (PTEN) was a direct target of miR-26a. Further mechanistic study revealed that miR-26a increased AKT phosphorylation and nuclear factor kappa B (NFκB) transcriptional activation. Our study demonstrated that miR-26a enhanced lung cancer cell metastasis potential via modulation of metastasis-related gene expression, and activation of AKT pathway by PTEN suppression, suggesting that miR-26a might be a potential therapeutic candidate in patients with metastatic lung cancer.

  15. MicroRNA-616 promotes the migration, invasion and epithelial-mesenchymal transition of HCC by targeting PTEN.

    PubMed

    Zhang, Di; Zhou, Peihua; Wang, Wei; Wang, Xiaolong; Li, Junhui; Sun, Xuejun; Zhang, Li

    2016-01-01

    MicroRNAs, which can post-transcriptionally regulate gene expression by binding to the 3'-untranslated regions of the mRNAs, have been found to be the critical regulators of the development and progression of hepatocellular carcinoma (HCC). The present study demonstrated for the first time that microRNA-616 (miR-616) was markedly upregulated in HCC tissues, and was associated with the recurrence and metastasis of HCC. Elevated level of miR-616 was correlated with adverse clinicopathological features and poor prognosis of HCC patients. Gain- and loss-of-function studies revealed that miR-616 could potentiate the migration, invasion and the epithelial-mesenchymal transtion (EMT) phenotype of HCC cells. Phosphatase and tensin homolog (PTEN), the predicted target of miR-616 by bioinformatics analysis, was confirmed as a direct downstream target of miR-616 through western blotting, luciferase reporter and immunohistochemical assays. Furthermore, we demonstrated that miR-616 exerted the promoting effects on EMT and metastatic ability of HCC cells through suppressing PTEN expression. Based on these results, we conclude that miR-616 is a promising prognostic biomarker of HCC and targeting miR-616 may be a potential option to prevent the progression of HCC.

  16. MicroRNA-205-5p is upregulated in myelodysplastic syndromes and induces cell proliferation via PTEN suppression.

    PubMed

    Jang, Sook Jin; Choi, In-Sun; Park, Geon; Moon, Dae-Soo; Choi, Ji-Seon; Nam, Myung-Hyun; Yoon, Soo-Young; Choi, Cheol Hee; Kang, Seong-Ho

    2016-08-01

    Micro (mi)RNA dysregulation is implicated in the development of myelodysplastic syndrome (MDS). Chromosomal abnormalities on 1q are frequently detected in Korean patients with MDS; however, how these are related to disease development is unknown. The present study compared the expression profiles of miRNAs encoded by chromosome 1q between 65 MDS patients and 11 controls. We found that miR-205-5p levels were 12.5 fold higher in the former (P=0.001). miR-205-5p level was increased in 44.7% of patients when an arbitrary 2(-ΔCt) cut-off value of 1.25 was used. miR-205-5p expression data were used to generate a receiver operating characteristic (ROC) curve for miR-205-5p, for which the area under the curve (AUC) was 0.825 (95% confidence interval: 0.710-0.941; P=0.001). Moreover, transfection with a miR-205-5p mimic induced cell proliferation by inhibiting the expression of the tumor suppressor protein phosphatase and tensin homolog (PTEN). Our findings suggest that miR-205-5p upregulation contributes to MDS by suppressing PTEN and that miR-205-5p thus acts as an oncogene in hematopoietic cells. PMID:27379838

  17. PTEN overexpression improves cisplatin-resistance of human ovarian cancer cells through upregulating KRT10 expression

    SciTech Connect

    Wu, Huijuan; Wang, Ke; Liu, Wenxin; Hao, Quan

    2014-02-07

    Highlights: • Overexpression of PTEN enhanced the sensitivity of C13K cells to cisplatin. • KRT10 is a downstream molecule of PTEN involved in the resistance-reversing effect. • Overexpression of KRT10 enhanced the chemosensitivity of C13K cells to cisplatin. - Abstract: Multi-drug resistance (MDR) is a common cause of the failure of chemotherapy in ovarian cancer. PTEN, a tumor suppressor gene, has been demonstrated to be able to reverse cisplatin-resistance in ovarian cancer cell line C13K. However, the downstream molecules of PTEN involved in the resistance-reversing effect have not been completely clarified. Therefore, we screened the downstream molecules of PTEN and studied their interactions in C13K ovarian cancer cells using a 3D culture model. Firstly, we constructed an ovarian cancer cell line stably expressing PTEN, C13K/PTEN. MTT assay showed that overexpression of PTEN enhanced the sensitivity of C13K cells to cisplatin, but not to paclitaxel. Then we examined the differently expressed proteins that interacted with PTEN in C13K/PTEN cells with or without cisplatin treatment by co-immunoprecipitation. KRT10 was identified as a differently expressed protein in cisplatin-treated C13K/PTEN cells. Further study confirmed that cisplatin could induce upregulation of KRT10 mRNA and protein in C13K/PTEN cells and there was a directly interaction between KRT10 and PTEN. Forced expression of KRT10 in C13K cells also enhanced cisplatin-induced proliferation inhibition and apoptosis of C13K cells. In addition, KRT10 siRNA blocked cisplatin-induced proliferation inhibition of C13K/PTEN cells. In conclusion, our data demonstrate that KRT10 is a downstream molecule of PTEN which improves cisplatin-resistance of ovarian cancer and forced KRT10 overexpression may also act as a therapeutic method for overcoming MDR in ovarian cancer.

  18. Simvastatin reverses cardiomyocyte hypertrophy via the upregulation of phosphatase and tensin homolog expression

    PubMed Central

    CHEN, YONG-QING; ZHAO, LIAN-YOU; ZHANG, WEI-ZE; LI, TAO

    2015-01-01

    The aim of the present study was to investigate the effects of simvastatin on the protein kinase B (PKB) signaling pathway and the expression of phosphatase and tensin homolog (PTEN). The effects of simvastatin were analyzed by administering the drug orally to male spontaneously hypertensive rats (SHRs) at a dose of 10 mg/kg/day, while the control animals received an equal volume of saline. The systolic pressure (mmHg) of the rat tail artery was measured prior to the initiation of the experiment, and once a week until the end of the experiment. At the end of the experiment, the animals were euthanized and the hearts were removed. The left ventricular and interventricular septum were weighed, after which the left ventricular mass/body mass ratio was calculated. In addition, cardiomyocytes isolated from Sprague Dawley rats were cultured with 15% fetal bovine serum to induce hypertrophy, following which the cells were treated with different doses of simvastatin. The in vitro effects were assessed by measuring the surface area of the cardiomyocytes, while the rate of protein synthesis was measured using a 3H-leucine incorporation assay and western blot analyses. Simvastatin was demonstrated to inhibit cardiomyocyte hypertrophy in the in vivo and in vitro experiments. Notably, simvastatin increased PTEN expression and inhibited PKB expression in the SHR model, as well as in the cardiomyocytes in culture. In addition, the use of PTEN antisense oligodeoxynucleotides was revealed to inhibit the effects of simvastatin on cardiomyocytes. Therefore, these results indicated that simvastatin was able to reverse cardiomyocyte hypertrophy in vivo and in vitro, possibly by increasing the expression of PTEN. PMID:26622396

  19. Identification of the miR-106b∼25 MicroRNA Cluster as a Proto-Oncogenic PTEN-Targeting Intron That Cooperates with Its Host Gene MCM7 in Transformation

    PubMed Central

    Poliseno, Laura; Salmena, Leonardo; Riccardi, Luisa; Fornari, Alessandro; Song, Min Sup; Hobbs, Robin M.; Sportoletti, Paolo; Varmeh, Shorheh; Egia, Ainara; Fedele, Giuseppe; Rameh, Lucia; Loda, Massimo; Pandolfi, Pier Paolo

    2010-01-01

    PTEN (phosphatase and tensin homolog deleted on chromosome 10) is a tumor suppressor that antagonizes signaling through the phosphatidylinositol-3-kinase–Akt pathway. We have demonstrated that subtle decreases in PTEN abundance can have critical consequences for tumorigenesis. Here, we used a computational approach to identify miR-22, miR-25, and miR-302 as three PTEN-targeting microRNA (miRNA) families found within nine genomic loci. We showed that miR-22 and the miR-106b∼25 cluster are aberrantly overexpressed in human prostate cancer, correlate with abundance of the miRNA processing enzyme DICER, and potentiate cellular transformation both in vitro and in vivo. We demonstrated that the intronic miR-106b∼25 cluster cooperates with its host gene MCM7 in cellular transformation both in vitro and in vivo, so that the concomitant overexpression of MCM7 and the miRNA cluster triggers prostatic intraepithelial neoplasia in transgenic mice. Therefore, the MCM7 gene locus delivers two simultaneous oncogenic insults when amplified or overexpressed in human cancer. Thus, we have uncovered a proto-oncogenic miRNA-dependent network for PTEN regulation and defined the MCM7 locus as a critical factor in initiating prostate tumorigenesis. PMID:20388916

  20. Inactivation of Rac1 reduces Trastuzumab resistance in PTEN deficient and insulin-like growth factor I receptor overexpressing human breast cancer SKBR3 cells.

    PubMed

    Zhao, Yong; Wang, Zhishan; Jiang, Yiguo; Yang, Chengfeng

    2011-12-26

    Drug resistance remains to be a big challenge in applying anti-HER2 monoclonal antibody Trastuzumab for treating breast cancer with HER2 overexpression. Amplification of insulin-like growth factor I receptor (IGF-IR) and deletion of tumor suppressor phosphatase and tensin homolog (PTEN) are implicated in Trastuzumab resistance, however, the underlying mechanisms have not been clearly defined. Activation of Rac1, a member of Rho GTPase family, is capable of causing cytoskeleton reorganization, regulating gene expression and promoting cell proliferation. To investigate the mechanism of Trastuzumab resistance, PTEN knockdown and IGF-IR overexpressing stable cell lines were generated in HER2 overexpression human breast cancer SKBR3 cells. Rac1 was highly activated in PTEN deficient and IGF-IR overexpressing Trastuzumab-resistant cells in a HER2-independent manner. Inactivation of Rac1 by using a Rac1 inhibitor NSC23766 or siRNA knocking down the expression of Tiam1, a guanine nucleotide exchange factor for Rac, significantly reduced Trastuzumab resistance in SKBR3 cells. Inhibition of Rac1 had no effect on the levels of phosphor-HER2 and phosphor-Akt, but significantly decreased the levels of cyclin D1 in Trastuzumab-resistant cells. Inhibition of Akt with an Akt inhibitor also significantly reduced Trastuzumab resistance. However, simultaneous inhibition of both Rac1 and Akt resulted in a significantly more decrease of Trastuzumab resistance than inactivation of Rac1 or Akt alone. These results suggest that Rac1 activation is critically involved in Trastuzumab resistance caused by PTEN deletion or IGF-IR overexpression. Simultaneous inhibition of Rac1 and Akt may represent a promising strategy in reducing Trastuzumab resistance in HER2 overexpression breast cancer.

  1. A pseudogene long noncoding RNA network regulates PTEN transcription and translation in human cells

    PubMed Central

    Johnsson, Per; Ackley, Amanda; Vidarsdottir, Linda; Lui, Weng-Onn; Corcoran, Martin; Grandér, Dan; Morris, Kevin V.

    2013-01-01

    PTEN is a tumor suppressor gene that has been shown to be under the regulatory control of a PTEN pseudogene expressed noncoding RNA, PTENpg1. Here, we characterize a previously unidentified PTENpg1 encoded antisense RNA (asRNA), which regulates PTEN transcription and PTEN mRNA stability. We find two PTENpg1 asRNA isoforms, alpha and beta. The alpha isoform functions in trans, localizes to the PTEN promoter, and epigenetically modulates PTEN transcription by the recruitment of DNMT3a and EZH2. In contrast, the beta isoform interacts with PTENpg1 through an RNA:RNA pairing interaction, which affects PTEN protein output via changes of PTENpg1 stability and microRNA sponge activity. Disruption of this asRNA-regulated network induces cell cycle arrest and sensitizes cells to doxorubicin, suggesting a biological function for the respective PTENpg1 expressed asRNAs. PMID:23435381

  2. Conformational Stability and Catalytic Activity of PTEN Variants Linked to Cancers and Autism Spectrum Disorders

    PubMed Central

    Johnston, Sean B.; Raines, Ronald T.

    2015-01-01

    Phosphoinositides are membrane components that play critical regulatory roles in mammalian cells. The enzyme PTEN, which catalyzes the dephosphorylation of the phosphoinositide PIP3, is damaged in most sporadic tumors. Mutations in the PTEN gene have also been linked to autism spectrum disorders and other forms of delayed development. Here, human PTEN is shown to be on the cusp of unfolding under physiological conditions. Variants of human PTEN linked to somatic cancers and disorders on the autism spectrum are shown to be impaired in their conformational stability, catalytic activity, or both. Those variants linked only to autism have higher activity than those linked to cancers. PTEN-L, which is a secreted trans-active isoform, has greater conformational stability than does the wild-type enzyme. These data indicate that PTEN is a fragile enzyme cast in a crucial role in cellular metabolism, and suggest that PTEN-L is a repository for a critical catalytic activity. PMID:25647146

  3. Cell Surface Area and Membrane Folding in Glioblastoma Cell Lines Differing in PTEN and p53 Status

    PubMed Central

    Höring, Marcus; Westerling, Katherine; Fiedler, Vanessa; Katzer, Astrid; Krohne, Georg; Flentje, Michael; Djuzenova, Cholpon S.

    2014-01-01

    Glioblastoma multiforme (GBM) is characterized by rapid growth, invasion and resistance to chemo−/radiotherapy. The complex cell surface morphology with abundant membrane folds, microvilli, filopodia and other membrane extensions is believed to contribute to the highly invasive behavior and therapy resistance of GBM cells. The present study addresses the mechanisms leading to the excessive cell membrane area in five GBM lines differing in mutational status for PTEN and p53. In addition to scanning electron microscopy (SEM), the membrane area and folding were quantified by dielectric measurements of membrane capacitance using the single-cell electrorotation (ROT) technique. The osmotic stability and volume regulation of GBM cells were analyzed by video microscopy. The expression of PTEN, p53, mTOR and several other marker proteins involved in cell growth and membrane synthesis were examined by Western blotting. The combined SEM, ROT and osmotic data provided independent lines of evidence for a large variability in membrane area and folding among tested GBM lines. Thus, DK-MG cells (wild type p53 and wild type PTEN) exhibited the lowest degree of membrane folding, probed by the area-specific capacitance Cm = 1.9 µF/cm2. In contrast, cell lines carrying mutations in both p53 and PTEN (U373-MG and SNB19) showed the highest Cm values of 3.7–4.0 µF/cm2, which corroborate well with their heavily villated cell surface revealed by SEM. Since PTEN and p53 are well-known inhibitors of mTOR, the increased membrane area/folding in mutant GBM lines may be related to the enhanced protein and lipid synthesis due to a deregulation of the mTOR-dependent downstream signaling pathway. Given that membrane folds and extensions are implicated in tumor cell motility and metastasis, the dielectric approach presented here provides a rapid and simple tool for screening the biophysical cell properties in studies on targeting chemo- or radiotherapeutically the migration and invasion

  4. The mechanism involved in the loss of PTEN expression in NSCLC tumor cells

    SciTech Connect

    Li, Gang; Zhao, Jingfeng; Peng, Xianjing; Liang, Jian; Deng, Xin; Chen, Yuxiang

    2012-02-17

    Highlights: Black-Right-Pointing-Pointer Radiation stimulates PTEN reexpression in NSCLC independent of p53 activation. Black-Right-Pointing-Pointer PTEN reexpression is mediated by miR-29b overexpression. Black-Right-Pointing-Pointer miR-29b regulates Dnmts expression in NSCLC tumor cells. Black-Right-Pointing-Pointer Target therapy could be established by overexpressing miR-29b expression. -- Abstract: Loss of PTEN expression is observed in most non-small cell lung cancers (NSCLC). However, the mechanism by which PTEN expression is regulated in NSCLC has not been fully elucidated. In this study, we investigated the role of DNA methyltransferases (Dnmts), microRNA-29b (miR-29b), and anti-miR-29b inhibitor in PTEN promoter methylation and PTEN gene expression in H358 NSCLC cells in vitro and in vivo. PTEN mRNA was measured by RT-PCR. PTEN and Dnmts protein levels were measured by Western blot. miR-29b expression was detected by Northern blot. A xenograft H358 tumor mouse model was established by subcutaneously inoculating H358 cells into the right hind limbs of nude mice. We found that radiation induced cell apoptosis and hypomethylation in PTEN promoter, PTEN and miR-29b expression, and downregulation of Dnmt1, 3a and 3b expression in H358 tumor cells. The effect of radiation on gene expression and apoptosis was blocked by anti-miR-29b inhibitor. In the xenograft H358 tumor model, anti-miR-29b inhibitor reversed radiation-induced tumor growth delay, PTEN reexpression and downregulation of Dnmts expression. Our study suggested that miR-29b is an upstream molecule of PTEN. miR-29b regulates PTEN gene expression through downregulating Dnmts expression and subsequently induces hypomethylation in PTEN promoter. Targeting therapy could be established in NSCLC by upregulating miR-29b expression.

  5. MicroRNA-382 induced by HIF-1α is an angiogenic miR targeting the tumor suppressor phosphatase and tensin homolog.

    PubMed

    Seok, Jin-Kyung; Lee, Sun Hee; Kim, Min Jung; Lee, You-Mie

    2014-07-01

    Recent studies have revealed that microRNAs (miRs) play important roles in the regulation of angiogenesis. In this study, we have characterized miR-382 upregulation by hypoxia and the functional relevance of miR-382 in tumor angiogenesis. miRs induced by hypoxia in MKN1 human gastric cancer cells were investigated using miRNA microarrays. We selected miR-382 and found that the expression of miR-382 was regulated by HIF-1α. Conditioned media (CM) from MKN1 cells transfected with a miR-382 inhibitor (antagomiR-382) under hypoxic conditions significantly decreased vascular endothelial cell (EC) proliferation, migration and tube formation. Algorithmic programs (Target Scan, miRanda and cbio) predicted that phosphatase and tensin homolog (PTEN) is a target gene of miR-382. Deletion of miR382-binding sequences in the PTEN mRNA 3'-untranslated region (UTR) diminished the luciferase reporter activity. Subsequent study showed that the overexpression of miR-382 or antagomiR-382 down- or upregulated PTEN and its downstream target AKT/mTOR signaling pathway, indicating that PTEN is a functional target gene of miR-382. In addition, PTEN inhibited miR-382-induced in vitro and in vivo angiogenesis as well as VEGF secretion, and the inhibition of miR-382 expression reduced xenograft tumor growth and microvessel density in tumors. Taken together, these results suggest that miR-382 induced by hypoxia promotes angiogenesis and acts as an angiogenic oncogene by repressing PTEN.

  6. Association of PTEN mutation with HPV-negative adenocarcinoma of the uterine cervix.

    PubMed

    Minaguchi, Takeo; Yoshikawa, Hiroyuki; Nakagawa, Shunsuke; Yasugi, Toshiharu; Yano, Tetsu; Iwase, Haruko; Mizutani, Katsumi; Shiromizu, Kenji; Ohmi, Kazuo; Watanabe, Yoh; Noda, Kiichiro; Nishiu, Mieko; Nakamura, Yusuke; Taketani, Yuji

    2004-07-01

    Serous, mucinous, endometrioid, and clear cell adenocarcinomas arise from reproductive organs of mullerian origin. Although the mutation of PTEN, a tumor suppressor, is known to be involved in tumorigenesis of endometrioid adenocarcinomas of the endometrium and ovary, the role of PTEN alteration in endometrioid adenocarcinoma of the cervix remains to be investigated. To elucidate the molecular pathogenesis of cervical adenocarcinoma and adenosquamous carcinoma, and in particular to examine the potential role of PTEN mutation in endometrioid-type cancer of the cervix, we analyzed 32 cervical adeno- or adenosquamous carcinomas (8 endometrioid adenocarcinomas, 14 mucinous adenocarcinomas and 10 adenosquamous carcinomas) for PTEN mutations and HPV infections. PTEN mutation was detected in 2 of 8 (25.0%) endometrioid cases, 2 of 14 (14.3%) mucinous cases, and none of 10 (0%) adenosquamous cases. HPV DNA was detected in 11 out of 18 (61.1%) PTEN wild-type adenocarcinomas and 8 out of 10 (80.0%) adenosquamous carcinomas. Among 11 HPV-negative adenocarcinomas, 40.0% (2/5) endometrioid cases and 33.3% (2/6) mucinous cases were shown to be PTEN mutated, while no cases (0/21) were PTEN-mutant in the remainder (i.e. adenosquamous carcinomas and HPV-positive adenocarcinomas). The current observations suggest that PTEN mutation is frequently detected in HPV-negative adenocarcinomas of the cervix and the most prevalent occurrence of PTEN mutation in endometrioid subtype is keeping with endometrial and ovarian carcinomas.

  7. Structural Genomics of Protein Phosphatases

    SciTech Connect

    Almo,S.; Bonanno, J.; Sauder, J.; Emtage, S.; Dilorenzo, T.; Malashkevich, V.; Wasserman, S.; Swaminathan, S.; Eswaramoorthy, S.; et al

    2007-01-01

    The New York SGX Research Center for Structural Genomics (NYSGXRC) of the NIGMS Protein Structure Initiative (PSI) has applied its high-throughput X-ray crystallographic structure determination platform to systematic studies of all human protein phosphatases and protein phosphatases from biomedically-relevant pathogens. To date, the NYSGXRC has determined structures of 21 distinct protein phosphatases: 14 from human, 2 from mouse, 2 from the pathogen Toxoplasma gondii, 1 from Trypanosoma brucei, the parasite responsible for African sleeping sickness, and 2 from the principal mosquito vector of malaria in Africa, Anopheles gambiae. These structures provide insights into both normal and pathophysiologic processes, including transcriptional regulation, regulation of major signaling pathways, neural development, and type 1 diabetes. In conjunction with the contributions of other international structural genomics consortia, these efforts promise to provide an unprecedented database and materials repository for structure-guided experimental and computational discovery of inhibitors for all classes of protein phosphatases.

  8. Trastuzumab induced in vivo tissue remodelling associated in vitro with inhibition of the active forms of AKT and PTEN and RhoB induction in an ovarian carcinoma model

    PubMed Central

    Delord, J-P; Quideau, S; Rochaix, P; Caselles, O; Couderc, B; Hennebelle, I; Courbon, F; Canal, P; Allal, B C

    2010-01-01

    Background: The incidence of ovarian cancer has been increasing worldwide and it is currently the leading cause of death from gynaecological malignancy. Unlike breast cancer, the prognostic role of the human epidermal growth factor receptor-2 (HER-2) in ovarian carcinoma remains controversial. Methods: The aim of this preclinical study was to further characterise the biological, molecular and cellular effects of trastuzumab (Herceptin) using NIH-OVCAR-3 and derived cell lines both in vitro and in vivo. Results: In vitro assessments have shown that trastuzumab treatment inhibited total and phosphorylated HER-2. This was associated with inhibition of the phosphorylated form of phosphatase and tensin homologue (PTEN), mitogen-activated protein kinase and AKT, and the total level of p27kip. Inhibition of PTEN is associated with phosphorylated MEK1/2 upregulation, suggesting a specific inhibition of the protein phosphatase function of PTEN. Moreover, trastuzumab induced the upregulation of RhoB. These molecular modifications promote inhibition of cell migration and potentially restoration of tumour cell contact inhibition. RhoB induction in NIH-OVCAR-3 control cell lines mimics the molecular and cellular trastuzumab long-time exposition effects. RhoB inhibition in NIH-OVCAR-3 long-time exposed to trastuzumab cell line reverses the cellular and molecular effects observed in this model. In vivo examinations have shown that these changes are also associated with the restoration of structural, morphological and normal functions of the peritoneum of an ovarian carcinoma mouse model. Conclusion: These results provide an indication of the mechanisms underlying the anti-tumour activity of trastuzumab that strongly implicate RhoB in an ovarian carcinoma model that does not show HER-2 amplification or overexpression. These findings highlight that trastuzumab effects involve a possible cross-talk between RhoB and PTEN in the early stages of tumour re-growth in a model of

  9. Glucose-6-phosphatase deficiency

    PubMed Central

    2011-01-01

    Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea). Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty), generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma) and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency). GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia) which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib). Mutations in the genes G6PC (17q21) and SLC37A4 (11q23) respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most commonly confirmed

  10. Neuronal RARβ Signaling Modulates PTEN Activity Directly in Neurons and via Exosome Transfer in Astrocytes to Prevent Glial Scar Formation and Induce Spinal Cord Regeneration

    PubMed Central

    Goncalves, Maria B.; Malmqvist, Tony; Clarke, Earl; Hubens, Chantal J.; Grist, John; Hobbs, Carl; Trigo, Diogo; Risling, Mårten; Angeria, Maria; Damberg, Peter; Carlstedt, Thomas P.

    2015-01-01

    Failure of axonal regeneration in the central nervous system (CNS) is mainly attributed to a lack of intrinsic neuronal growth programs and an inhibitory environment from a glial scar. Phosphatase and tensin homolog (PTEN) is a major negative regulator of neuronal regeneration and, as such, inhibiting its activity has been considered a therapeutic target for spinal cord (SC) injuries (SCIs). Using a novel model of rat cervical avulsion, we show that treatment with a retinoic acid receptor β (RARβ) agonist results in locomotor and sensory recovery. Axonal regeneration from the severed roots into the SC could be seen by biotinylated dextran amine labeling. Light micrographs of the dorsal root entry zone show the peripheral nervous system (PNS)–CNS transition of regrown axons. RARβ agonist treatment also resulted in the absence of scar formation. Mechanism studies revealed that, in RARβ-agonist-treated neurons, PTEN activity is decreased by cytoplasmic phosphorylation and increased secretion in exosomes. These are taken up by astrocytes, resulting in hampered proliferation and causing them to arrange in a normal-appearing scaffold around the regenerating axons. Attribution of the glial modulation to neuronal PTEN in exosomes was demonstrated by the use of an exosome inhibitor in vivo and PTEN siRNA in vitro assays. The dual effect of RARβ signaling, both neuronal and neuronal–glial, results in axonal regeneration into the SC after dorsal root neurotmesis. Targeting this pathway may open new avenues for the treatment of SCIs. SIGNIFICANCE STATEMENT Spinal cord injuries (SCIs) often result in permanent damage in the adult due to the very limited capacity of axonal regeneration. Intrinsic neuronal programs and the formation of a glial scar are the main obstacles. Here, we identify a single target, neuronal retinoic acid receptor β (RARβ), which modulates these two aspects of the postinjury physiological response. Activation of RARβ in the neuron inactivates

  11. Defective PTEN regulation contributes to B cell hyperresponsiveness in systemic lupus erythematosus.

    PubMed

    Wu, Xiang-ni; Ye, Yan-xia; Niu, Jing-wen; Li, Yang; Li, Xin; You, Xin; Chen, Hua; Zhao, Li-dan; Zeng, Xiao-feng; Zhang, Feng-chun; Tang, Fu-lin; He, Wei; Cao, Xue-tao; Zhang, Xuan; Lipsky, Peter E

    2014-07-23

    PTEN regulates normal signaling through the B cell receptor (BCR). In systemic lupus erythematosus (SLE), enhanced BCR signaling contributes to increased B cell activity, but the role of PTEN in human SLE has remained unclear. We performed fluorescence-activated cell sorting analysis in B cells from SLE patients and found that all SLE B cell subsets, except for memory B cells, showed decreased expression of PTEN compared with B cells from healthy controls. Moreover, the level of PTEN expression was inversely correlated with disease activity. We then explored the mechanisms governing PTEN regulation in SLE B cells. Notably, in normal but not SLE B cells, interleukin-21 (IL-21) induced PTEN expression and suppressed Akt phosphorylation induced by anti-immunoglobulin M and CD40L stimulation. However, this deficit was not primarily at the signaling or the transcriptional level, because IL-21-induced STAT3 (signal transducer and activator of transcription 3) phosphorylation was intact and IL-21 up-regulated PTEN mRNA in SLE B cells. Therefore, we examined the expression of candidate microRNAs (miRs) that could regulate PTEN: SLE B cells were found to express increased levels of miR-7, miR-21, and miR-22. These miRs down-regulated the expression of PTEN, and IL-21 stimulation increased the expression of miR-7 and miR-22 in both normal and SLE B cells. Indeed, a miR-7 antagomir corrected PTEN-related abnormalities in SLE B cells in a manner dependent on PTEN. Therefore, defective miR-7 regulation of PTEN contributes to B cell hyperresponsiveness in SLE and could be a new target of therapeutic intervention.

  12. Igf2 ligand dependency of Pten(+/-) developmental and tumour phenotypes in the mouse.

    PubMed

    Church, D N; Phillips, B R; Stuckey, D J; Barnes, D J; Buffa, F M; Manek, S; Clarke, K; Harris, A L; Carter, E J; Hassan, A B

    2012-08-01

    The tumour suppressor PTEN is a key negative regulator of the PI3K-Akt pathway, and is frequently either reduced or lost in human tumours. Murine genetic studies have confirmed that reduction of Pten promotes tumourigenesis in multiple organs, and demonstrated dependency of tumour development on the activation of downstream components such as Akt. Insulin-like growth factors (IGFs) act via IGF1R to activate the PI3K-Akt pathway, and are commonly upregulated in cancer. A context-dependent interplay between IGFs and PTEN exists in normal tissue and tumours; increased IGF2 ligand supply induces Pten expression creating an autoregulatory negative feedback loop, whereas complete loss of PTEN may either cooperate with IGF overexpression in tumour promotion, or result in desensitisation to IGF ligand. However, it remains unknown whether neoplasia associated with Pten loss is dependent on upstream IGF ligand supply in vivo. We evaluated this by generation of Pten(+/-) mice with differing allelic dosage of Igf2, an imprinted gene encoding the potent embryonic and tumour growth factor Igf2. We show that biallelic Igf2 supply potentiates a previously unreported Pten(+/-) placental phenotype and results in strain-dependent cardiac hyperplasia and neonatal lethality. Importantly, we also show that the effects of Pten loss in vivo are modified by Igf2 supply, as lack of Igf2 results in extended survival and delayed tumour development while biallelic supply is associated with reduced lifespan and accelerated neoplasia in females. Furthermore, we demonstrate that reduction of PTEN protein to heterozygote levels in human MCF7 cells is associated with increased proliferation in response to IGF2, and does not result in desensitisation to IGF2 signalling. These data indicate that the effects of Pten loss at heterozygote levels commonly observed in human tumours are modified by Igf2 ligand, and emphasise the importance of the evaluation of upstream pathways in tumours with Pten loss

  13. Adenovirus mediated homozygous endometrial epithelial Pten deletion results in aggressive endometrial carcinoma

    SciTech Connect

    Joshi, Ayesha; Ellenson, Lora Hedrick

    2011-07-01

    Pten is the most frequently mutated gene in uterine endometriod carcinoma (UEC) and its precursor complex atypical hyperplasia (CAH). Because the mutation frequency is similar in CAH and UEC, Pten mutations are thought to occur relatively early in endometrial tumorigenesis. Previous work from our laboratory using the Pten{sup +/-} mouse model has demonstrated somatic inactivation of the wild type allele of Pten in both CAH and UEC. In the present study, we injected adenoviruses expressing Cre into the uterine lumen of adult Pten floxed mice in an attempt to somatically delete both alleles of Pten specifically in the endometrium. Our results demonstrate that biallelic inactivation of Pten results in an increased incidence of carcinoma as compared to the Pten{sup +/-} mouse model. In addition, the carcinomas were more aggressive with extension beyond the uterus into adjacent tissues and were associated with decreased expression of nuclear ER{alpha} as compared to associated CAH. Primary cultures of epithelial and stromal cells were prepared from uteri of Pten floxed mice and Pten was deleted in vitro using Cre expressing adenovirus. Pten deletion was evident in both the epithelial and stromal cells and the treatment of the primary cultures with estrogen had different effects on Akt activation as well as Cyclin D3 expression in the two purified components. This study demonstrates that somatic biallelic inactivation of Pten in endometrial epithelium in vivo results in an increased incidence and aggressiveness of endometrial carcinoma compared to mice carrying a germline deletion of one allele and provides an important in vivo and in vitro model system for understanding the genetic underpinnings of endometrial carcinoma.

  14. Ursolic Acid Attenuates Diabetic Mesangial Cell Injury through the Up-Regulation of Autophagy via miRNA-21/PTEN/Akt/mTOR Suppression

    PubMed Central

    Lu, Xinxing; Fan, Qiuling; Xu, Li; Li, Lin; Yue, Yuan; Xu, Yanyan; Su, Yan; Zhang, Dongcheng; Wang, Lining

    2015-01-01

    Objective To investigate the effect of ursolic acid on autophagy mediated through the miRNA-21-targeted phosphoinositide 3 kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway in rat mesangial cells cultured under high glucose (HG) conditions. Methods Rat glomerular mesangial cells were cultured under normal glucose, HG, HG with the PI3K inhibitor LY294002 or HG with ursolic acid conditions. Cell proliferation and hypertrophy were assayed using an MTT assay and the ratio of total protein to cell number, respectively. The miRNA-21 expression was detected using RT-qPCR. The expression of phosphatase and tensin homolog (PTEN)/AKT/mTOR signaling signatures, autophagy-associated protein and collagen I was detected by western blotting and RT-qPCR. Autophagosomes were observed using electron microscopy. Results Compared with mesangial cells cultured under normal glucose conditions, the cells exposed to HG showed up-regulated miRNA-21 expression, down-regulated PTEN protein and mRNA expression, up-regulated p85PI3K, pAkt, pmTOR, p62/SQSTMI, and collagen I expression and down-regulated LC3II expression. Ursolic acid and LY294002 inhibited HG-induced mesangial cell hypertrophy and proliferation, down-regulated p85PI3K, pAkt, pmTOR, p62/SQSTMI, and collagen I expression and up-regulated LC3II expression. However, LY294002 did not affect the expression of miRNA-21 and PTEN. Ursolic acid down-regulated miRNA-21 expression and up-regulated PTEN protein and mRNA expression. Conclusions Ursolic acid inhibits the glucose-induced up-regulation of mesangial cell miRNA-21 expression, up-regulates PTEN expression, inhibits the activation of PI3K/Akt/mTOR signaling pathway, and enhances autophagy to reduce the accumulation of the extracellular matrix and ameliorate cell hypertrophy and proliferation. PMID:25689721

  15. Selective inhibition of PTEN preserves ischaemic post-conditioning cardioprotection in STZ-induced Type 1 diabetic rats: role of the PI3K/Akt and JAK2/STAT3 pathways.

    PubMed

    Xue, Rui; Lei, Shaoqing; Xia, Zhong-yuan; Wu, Yang; Meng, Qingtao; Zhan, Liying; Su, Wating; Liu, Huimin; Xu, Jinjin; Liu, Zhenzhen; Zhou, Bin; Xia, Zhengyuan

    2016-03-01

    Patients with diabetes are vulnerable to MI/R (myocardial ischaemia/reperfusion) injury, but are not responsive to IPostC (ischaemic post-conditioning) which activates PI3K (phosphoinositide 3-kinase)/Akt (also known as PKB or protein kinase B) and JAK2 (Janus kinase 2)/STAT3 (signal transducer and activator of transcription 3) pathways to confer cardioprotection. We hypothesized that increased cardiac PTEN (phosphatase and tensin homologue deleted on chromosome 10), a major negative regulator of PI3K/Akt, is responsible for the loss of diabetic heart sensitivity to IPostC cardioprotecton. In STZ (streptozotocin)-induced Type 1 diabetic rats subjected to MI/R (30 min coronary occlusion and 120 min reperfusion), the post-ischaemic myocardial infarct size, CK-MB (creatine kinase-MB) and 15-F2t-isoprostane release, as well as cardiac PTEN expression were significantly higher than those in non-diabetic controls, concomitant with more severe cardiac dysfunction and lower cardiac Akt, STAT3 and GSK-3β (glycogen synthase kinase 3β) phosphorylation. IPostC significantly attenuated post-ischaemic infarct size, decreased PTEN expression and further increased Akt, STAT3 and GSK-3β phosphorylation in non-diabetic, but not in diabetic rats. Application of the PTEN inhibitor BpV (bisperoxovanadium) (1.0 mg/kg) restored IPostC cardioprotection in diabetic rats. HPostC (hypoxic post-conditioning) in combination with PTEN gene knockdown, but not HPostC alone, significantly reduced H/R (hypoxia/reoxygenation) injury in cardiac H9c2 cells exposed to high glucose as was evident from reduced apoptotic cell death and JC-1 monomer in cells, accompanied by increased phosphorylation of Akt, STAT3 and GSK-3β. PTEN inhibition/gene knockdown mediated restoration of IPostC/HPostC cardioprotection was completely reversed by the PI3K inhibitor wortmannin, and partially reversed by the JAK2 inhibitor AG490. Increased cardiac PTEN, by impairing PI3K/Akt and JAK2/STAT3 pathways, is a major

  16. Pten Cell Autonomously Modulates the Hematopoietic Stem Cell Response to Inflammatory Cytokines.

    PubMed

    Porter, Shaina N; Cluster, Andrew S; Signer, Robert A J; Voigtmann, Jenna; Monlish, Darlene A; Schuettpelz, Laura G; Magee, Jeffrey A

    2016-06-14

    Pten negatively regulates the phosphatidylinositol 3-kinase (PI3K) pathway and is required to maintain quiescent adult hematopoietic stem cells (HSCs). Pten has been proposed to regulate HSCs cell autonomously and non-cell autonomously, but the relative importance of each mechanism has not been directly tested. Furthermore, the cytokines that activate the PI3K pathway upstream of Pten are not well defined. We sought to clarify whether Pten cell autonomously or non-cell autonomously regulates HSC mobilization. We also tested whether Pten deficiency affects the HSC response to granulocyte colony-stimulating factor (G-CSF) and interferon-α (IFNα) since these cytokines induce HSC mobilization or proliferation, respectively. We show that Pten regulates HSC mobilization and expansion in the spleen primarily via cell-autonomous mechanisms. Pten-deficient HSCs do not require G-CSF to mobilize, although they are hyper-sensitized to even low doses of exogenous G-CSF. Pten-deficient HSCs are similarly sensitized to IFNα. Pten therefore modulates the HSC response to inflammatory cytokines.

  17. PTEN is required to maintain luminal epithelial homeostasis and integrity in the adult mammary gland.

    PubMed

    Shore, Amy N; Chang, Chi-Hsuan; Kwon, Oh-Joon; Weston, Matthew C; Zhang, Mei; Xin, Li; Rosen, Jeffrey M

    2016-01-01

    In the mammary gland, PTEN loss in luminal and basal epithelial cells results in differentiation defects and enhanced proliferation, leading to the formation of tumors with basal epithelial characteristics. In breast cancer, PTEN loss is associated with a hormone receptor-negative, basal-like subtype that is thought to originate in a luminal epithelial cell. Here, we show that luminal-specific PTEN loss results in distinct effects on epithelial homeostasis and mammary tumor formation. Luminal PTEN loss increased proliferation of hormone receptor-negative cells, thereby decreasing the percentage of hormone receptor-positive cells. Moreover, luminal PTEN loss led to misoriented cell divisions and mislocalization of cells to the intraluminal space of mammary ducts. Despite their elevated levels of activated AKT, Pten-null intraluminal cells showed increased levels of apoptosis. One year after Pten deletion, the ducts had cleared and no palpable mammary tumors were detected. These data establish PTEN as a critical regulator of luminal epithelial homeostasis and integrity in the adult mammary gland, and further show that luminal PTEN loss alone is not sufficient to promote the progression of mammary tumorigenesis.

  18. Pten Cell Autonomously Modulates the Hematopoietic Stem Cell Response to Inflammatory Cytokines.

    PubMed

    Porter, Shaina N; Cluster, Andrew S; Signer, Robert A J; Voigtmann, Jenna; Monlish, Darlene A; Schuettpelz, Laura G; Magee, Jeffrey A

    2016-06-14

    Pten negatively regulates the phosphatidylinositol 3-kinase (PI3K) pathway and is required to maintain quiescent adult hematopoietic stem cells (HSCs). Pten has been proposed to regulate HSCs cell autonomously and non-cell autonomously, but the relative importance of each mechanism has not been directly tested. Furthermore, the cytokines that activate the PI3K pathway upstream of Pten are not well defined. We sought to clarify whether Pten cell autonomously or non-cell autonomously regulates HSC mobilization. We also tested whether Pten deficiency affects the HSC response to granulocyte colony-stimulating factor (G-CSF) and interferon-α (IFNα) since these cytokines induce HSC mobilization or proliferation, respectively. We show that Pten regulates HSC mobilization and expansion in the spleen primarily via cell-autonomous mechanisms. Pten-deficient HSCs do not require G-CSF to mobilize, although they are hyper-sensitized to even low doses of exogenous G-CSF. Pten-deficient HSCs are similarly sensitized to IFNα. Pten therefore modulates the HSC response to inflammatory cytokines. PMID:27185281

  19. PTEN is required to maintain luminal epithelial homeostasis and integrity in the adult mammary gland.

    PubMed

    Shore, Amy N; Chang, Chi-Hsuan; Kwon, Oh-Joon; Weston, Matthew C; Zhang, Mei; Xin, Li; Rosen, Jeffrey M

    2016-01-01

    In the mammary gland, PTEN loss in luminal and basal epithelial cells results in differentiation defects and enhanced proliferation, leading to the formation of tumors with basal epithelial characteristics. In breast cancer, PTEN loss is associated with a hormone receptor-negative, basal-like subtype that is thought to originate in a luminal epithelial cell. Here, we show that luminal-specific PTEN loss results in distinct effects on epithelial homeostasis and mammary tumor formation. Luminal PTEN loss increased proliferation of hormone receptor-negative cells, thereby decreasing the percentage of hormone receptor-positive cells. Moreover, luminal PTEN loss led to misoriented cell divisions and mislocalization of cells to the intraluminal space of mammary ducts. Despite their elevated levels of activated AKT, Pten-null intraluminal cells showed increased levels of apoptosis. One year after Pten deletion, the ducts had cleared and no palpable mammary tumors were detected. These data establish PTEN as a critical regulator of luminal epithelial homeostasis and integrity in the adult mammary gland, and further show that luminal PTEN loss alone is not sufficient to promote the progression of mammary tumorigenesis. PMID:26526198

  20. PTEN Deletion Enhances the Regenerative Ability of Adult Corticospinal Neurons

    PubMed Central

    Liu, Kai; Lu, Yi; Lee, Jae K.; Samara, Ramsey; Willenberg, Rafer; Sears-Kraxberger, Ilse; Tedeschi, Andrea; Park, Kevin Kyungsuk; Jin, Duo; Cai, Bin; Xu, Bengang; Connolly, Lauren; Steward, Oswald; Zheng, Binhai; He, Zhigang

    2010-01-01

    Despite the essential role of the corticospinal tract (CST) in controlling voluntary movements, successful regeneration of large numbers of injured CST axons beyond a spinal cord lesion has never been achieved. Here we demonstrate a critical involvement of PTEN/mTOR in controlling the regenerative capacity of mouse corticospinal neurons. Upon the completion of development, the regrowth potential of CST axons lost and this is accompanied by a down-regulation of mTOR activity in corticospinal neurons. Axonal injury further diminishes neuronal mTOR activity in these neurons. Forced up-regulation of mTOR activity in corticospinal neurons by conditional deletion of PTEN, a negative regulator of mTOR, enhances compensatory sprouting of uninjured CST axons and even more strikingly, enables successful regeneration of a cohort of injured CST axons past a spinal cord lesion. Furthermore, these regenerating CST axons possess the ability to reform synapses in spinal segments distal to the injury. Thus, modulating neuronal intrinsic PTEN/mTOR activity represents a potential therapeutic strategy for promoting axon regeneration and functional repair after adult spinal cord injury. PMID:20694004

  1. Timing of the loss of Pten protein determines disease severity in a mouse model of myeloid malignancy

    PubMed Central

    Yan, Yan; Webster, Cody; Shao, Lijian; Lensing, Shelly Y.; Ni, Hongyu; Feng, Wei; Colorado, Natalia; Pathak, Rupak; Xiang, Zhifu; Hauer-Jensen, Martin; Li, Shaoguang; Zhou, Daohong; Emanuel, Peter D.

    2016-01-01

    Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric mixed myelodysplastic/myeloproliferative neoplasm (MDS/MPN). JMML leukemogenesis is linked to a hyperactivated RAS pathway, with driver mutations in the KRAS, NRAS, NF1, PTPN11, or CBL genes. Previous murine models demonstrated how those genes contributed to the selective hypersensitivity of JMML cells to granulocyte macrophage–colony-stimulating factor (GM-CSF), a unifying characteristic in the disease. However, it is unclear what causes the early death in children with JMML, because transformation to acute leukemia is rare. Here, we demonstrate that loss of Pten (phosphatase and tensin homolog) protein at postnatal day 8 in mice harboring Nf1 haploinsufficiency results in an aggressive MPN with death at a murine prepubertal age of 20 to 35 days (equivalent to an early juvenile age in JMML patients). The death in the mice was due to organ infiltration with monocytes/macrophages. There were elevated activities of protein kinase B (Akt) and mitogen-activated protein kinase (MAPK) in cells at physiological concentrations of GM-CSF. These were more pronounced in mice with Nf1 haploinsufficiency than in littermates with wild-type Nf1, but this model is insufficient to cause cells to be GM-CSF hypersensitive. This new model represents a murine MPN model with features of a pediatric unclassifiable mixed MDS/MPN and mimics many clinical manifestations of JMML in terms of age of onset, aggressiveness, and organ infiltration with monocytes/macrophages. Our data suggest that the timing of the loss of PTEN protein plays a critical role in determining the disease severity in myeloid malignancies. This model may be useful for studying the pathogenesis of pediatric diseases with alterations in the Ras pathway. PMID:26764354

  2. Down-regulation of PTEN by HCV core protein through activating nuclear factor-κB

    PubMed Central

    Zhang, Yong; Li, Rong-Qing; Feng, Xu-Dong; Zhang, Yan-Hua; Wang, Li

    2014-01-01

    The hepatitis C virus (HCV) core protein is an important causative agent in HCV related hepatocellular carcinoma (HCC). Tumor suppressor gene PTEN appears to act in the liver at the crossroad of processes controlling cell proliferation. In this study we investigated the effect of the HCV core protein on the PTEN pathway in hepatocarcinogenesis. The HCV core was transfected stably into HepG2 cell. The effect of HCV core on cell proliferation and viability were detected by 3-(4, 5)-dimethylthiahiazo-(-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) assay, clonogenic survival assay and Fluorescence Activating Cell Sorter (FACS) analysis. The expressions of PTEN were detected by real time RT-PCR and/or Western blot analysis, also the mechanism of down-regulation of PTEN was explored by western blot, luciferase assay and RNA interference. We found the HCV core promoted cell proliferation, survival and G2/M phase accumulation. It downregulated PTEN at mRNA and protein level and activated PTEN downstream gene Akt accompanied with NF-κB activation. Furthermore, the inhibition of HCV core by its specific shRNAs decreased the effect of growth promotion and G2/M phase arrest, inhibited the expression of nuclear p65 and increased PTEN expression. The activity of PTEN was restored when treated with NF-κB inhibitor PDTC. By luciferase assay we found that NF-κB inhibited PTEN promoter transcription activity directly in HCV core cells, while PDTC was contrary. Our study suggests that HCV proteins could modulate PTEN by activating NF-κB. Furthermore strategies designed to restore the expression of PTEN may be promising therapies for preventing HCV dependent hepatocarcinogenesis. PMID:25550771

  3. Silymarin inhibits cervical cancer cell through an increase of phosphatase and tensin homolog.

    PubMed

    Yu, Hann-Chin; Chen, Li-Jen; Cheng, Kai-Chun; Li, Ying-Xiao; Yeh, Ching-Hua; Cheng, Juei-Tang

    2012-05-01

    Silymarin is an active constituent contained in the seeds of the milk thistle plant and is widely used as a hepatic protection agent due to its antioxidant-like activity. In the present study we evaluated the potential action of silymarin against cervical cancer and investigated its mechanism of action. Treatment of cervical cancer cells (C-33A) with silymarin resulted in a significant decrease in cell viability. Silymarin induced apoptosis through the modulation of Bcl-2 family proteins and activation of caspase 3. Silymarin also inhibited the phosphorylation of Akt with an increase in expression of phosphatase and tensin homolog (PTEN). We also observed that silymarin suppressed C-33A cell invasion and wound-healing migration in a concentration-dependent manner. Western-blot analysis showed that silymarin significantly inhibited the expression of matrix metalloproteinase-9 (MMP-9) in C-33A cells. Furthermore, we applied siRNA to lower the PTEN gene, which diminished the anticancer actions of silymarin. Taken together, these results show that silymarin has the potential to suppress the survival, migration and invasion of C-33A cancer cells; thus, it could be developed as a promising agent for the treatment of cervical cancer in the future.

  4. Comprehensive protein tyrosine phosphatase mRNA profiling identifies new regulators in the progression of glioma.

    PubMed

    Bourgonje, Annika M; Verrijp, Kiek; Schepens, Jan T G; Navis, Anna C; Piepers, Jolanda A F; Palmen, Chantal B C; van den Eijnden, Monique; Hooft van Huijsduijnen, Rob; Wesseling, Pieter; Leenders, William P J; Hendriks, Wiljan J A J

    2016-01-01

    The infiltrative behavior of diffuse gliomas severely reduces therapeutic potential of surgical resection and radiotherapy, and urges for the identification of new drug-targets affecting glioma growth and migration. To address the potential role of protein tyrosine phosphatases (PTPs), we performed mRNA expression profiling for 91 of the 109 known human PTP genes on a series of clinical diffuse glioma samples of different grades and compared our findings with in silico knowledge from REMBRANDT and TCGA databases. Overall PTP family expression levels appeared independent of characteristic genetic aberrations associated with lower grade or high grade gliomas. Notably, seven PTP genes (DUSP26, MTMR4, PTEN, PTPRM, PTPRN2, PTPRT and PTPRZ1) were differentially expressed between grade II-III gliomas and (grade IV) glioblastomas. For DUSP26, PTEN, PTPRM and PTPRT, lower expression levels correlated with poor prognosis, and overexpression of DUSP26 or PTPRT in E98 glioblastoma cells reduced tumorigenicity. Our study represents the first in-depth analysis of PTP family expression in diffuse glioma subtypes and warrants further investigations into PTP-dependent signaling events as new entry points for improved therapy. PMID:27586084

  5. miR‑205 suppresses cell proliferation, invasion, and metastasis via regulation of the PTEN/AKT pathway in renal cell carcinoma.

    PubMed

    Wang, Huiqiang; Chen, Bin; Duan, Bo; Zheng, Jiaxin; Wu, Xinyi

    2016-10-01

    The present study aimed to determine the importance of microRNA‑205 (miR‑205) in the proliferation, apoptosis, invasion and metastasis of renal cell carcinoma (RCC) cells and the underlying molecular mechanisms. Reverse transcription‑polymerase chain reaction was used to quantify the expression levels of miR‑205 in RCC tissue, normal tissue adjacent to carcinoma, RCC cells and normal renal cells. It was determined that the expression levels of miR‑205 in RCC tissue and cells were reduced compared with those in normal tissue and renal cells. miR‑205 mimics and the negative control were prepared and transfected into RCC cells. Cell viability and apoptosis were investigated using methyl thiazolyl tetrazolium assay and Annexin V‑fluorescein isothiocyanate/propidium iodide staining, respectively. Cell migration and invasion were evaluated with Transwell assays. The protein expression levels of E2F transcription factor 1 (E2F1), B‑cell lymphoma‑2 (Bcl‑2), E‑cadherin, vimentin, phosphatase and tensin homolog (PTEN) and phosphorylated AKT serine/threonine kinase 1 (p‑AKT) were determined with western blot analysis. It was revealed that miR‑205 promoted the apoptosis of RCC cells and suppressed their proliferation, metastasis and invasion compared with the negative control. The expression levels of E2F1, Bcl‑2, vimentin and p‑AKT were downregulated compared with the negative control. The expression levels of E‑cadherin and PTEN were upregulated in the cells transfected with miR‑205 mimics compared with the negative control group. Therefore, it was concluded that miR‑205 suppressed cell proliferation, invasion, and metastasis in RCC cells via regulation of the PTEN/AKT signaling pathway. The present study may contribute to future miRNA‑based RCC therapy. PMID:27498834

  6. PTEN overexpression attenuates angiogenic processes of endothelial cells by blockade of endothelin-1/endothelin B receptor signaling.

    PubMed

    Kuo, Hsiao-Mei; Lin, Chun-Yao; Lam, Hing-Chung; Lin, Pey-Ru; Chan, Hoi-Hung; Tseng, Jui-Cheng; Sun, Cheuk-Kwan; Hsu, Te-Fa; Wu, Chia-Ching; Yang, Chao-Yuh; Hsu, Ching-Mei; Tai, Ming-Hong

    2012-04-01

    Arteriovenous (AV) graft is frequently used as vascular access in hemodialysis patients. However, clotting or thrombosis of AV grafts often occurs and requires surgical removal. At present, the molecular pathogenesis underlying thrombosis of AV graft is not clear. The PTEN/Akt signaling has been implicated in the pathogenesis of vascular diseases. In this study, elevated PTEN expression and concomitant Akt inactivation was observed in endothelium of atherosclerotic brachial arteries from hemodialysis patients. To investigate whether PTEN upregulation affects endothelial function, adenovirus-mediated PTEN (Ad-PTEN) overexpression was performed in aorta rings and cultured endothelial cells. It was found that PTEN overexpression potently inhibited the microvessel sprouting in aorta rings and the angiogenic activities of endothelial cells including migration and tube formation. On the contrary, PTEN knockdown by RNA interference promoted the endothelial migration and reversed the Ad-PTEN-induced inhibition of endothelial migration. Expression analysis showed that PTEN overexpression attenuated the expression of endothelin-1 (ET-1) and endothelin B receptor (ETBR) in endothelial cells at transcriptional levels. However, exogenous ET-1 supply only partially reversed the PTEN-induced inhibition of migration and tube formation. This was delineated due to that PTEN overexpression also perturbed endothelial nitric oxide synthase (eNOS) activation and vascular endothelial growth factor (VEGF) release. In summary, PTEN upregulation induces endothelial dysfunction by attenuating the availability and signaling of multiple angiogenic pathways in endothelial cells, thereby may contribute to thrombosis of AV graft.

  7. PTEN deficiency reprogrammes human neural stem cells towards a glioblastoma stem cell-like phenotype.

    PubMed

    Duan, Shunlei; Yuan, Guohong; Liu, Xiaomeng; Ren, Ruotong; Li, Jingyi; Zhang, Weizhou; Wu, Jun; Xu, Xiuling; Fu, Lina; Li, Ying; Yang, Jiping; Zhang, Weiqi; Bai, Ruijun; Yi, Fei; Suzuki, Keiichiro; Gao, Hua; Esteban, Concepcion Rodriguez; Zhang, Chuanbao; Izpisua Belmonte, Juan Carlos; Chen, Zhiguo; Wang, Xiaomin; Jiang, Tao; Qu, Jing; Tang, Fuchou; Liu, Guang-Hui

    2015-01-01

    PTEN is a tumour suppressor frequently mutated in many types of cancers. Here we show that targeted disruption of PTEN leads to neoplastic transformation of human neural stem cells (NSCs), but not mesenchymal stem cells. PTEN-deficient NSCs display neoplasm-associated metabolic and gene expression profiles and generate intracranial tumours in immunodeficient mice. PTEN is localized to the nucleus in NSCs, binds to the PAX7 promoter through association with cAMP responsive element binding protein 1 (CREB)/CREB binding protein (CBP) and inhibits PAX7 transcription. PTEN deficiency leads to the upregulation of PAX7, which in turn promotes oncogenic transformation of NSCs and instates 'aggressiveness' in human glioblastoma stem cells. In a large clinical database, we find increased PAX7 levels in PTEN-deficient glioblastoma. Furthermore, we identify that mitomycin C selectively triggers apoptosis in NSCs with PTEN deficiency. Together, we uncover a potential mechanism of how PTEN safeguards NSCs, and establish a cellular platform to identify factors involved in NSC transformation, potentially permitting personalized treatment of glioblastoma. PMID:26632666

  8. Soy peptide lunasin induces pten-mediated apoptosis in human breast cancer cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The tumor suppressor PTEN inhibits the AKT signaling pathway whose unrestrained activity underlies many human malignancies. Previously we showed that dietary intake of soy protein isolate (SPI) enhanced PTEN expression in mammary tissue of rats with lower NMU-induced mammary tumor incidence relative...

  9. Efficacy of targeted AKT inhibition in genetically engineered mouse models of PTEN-deficient prostate cancer.

    PubMed

    De Velasco, Marco A; Kura, Yurie; Yoshikawa, Kazuhiro; Nishio, Kazuto; Davies, Barry R; Uemura, Hirotsugu

    2016-03-29

    The PI3K/AKT pathway is frequently altered in advanced human prostate cancer mainly through the loss of functional PTEN, and presents as potential target for personalized therapy. Our aim was to determine the therapeutic potential of the pan-AKT inhibitor, AZD5363, in PTEN-deficient prostate cancer. Here we used a genetically engineered mouse (GEM) model of PTEN-deficient prostate cancer to evaluate the in vivo pharmacodynamic and antitumor activity of AZD5363 in castration-naïve and castration-resistant prostate cancer. An additional GEM model, based on the concomitant inactivation of PTEN and Trp53 (P53), was established as an aggressive model of advanced prostate cancer and was used to further evaluate clinically relevant endpoints after treatment with AZD5363. In vivo pharmacodynamic studies demonstrated that AZD5363 effectively inhibited downstream targets of AKT. AZD5363 monotherapy significantly reduced growth of tumors in castration-naïve and castration-resistant models of PTEN-deficient prostate cancer. More importantly, AZD5363 significantly delayed tumor growth and improved overall survival and progression-free survival in PTEN/P53 double knockout mice. Our findings demonstrate that AZD5363 is effective against GEM models of PTEN-deficient prostate cancer and provide lines of evidence to support further investigation into the development of treatment strategies targeting AKT for the treatment of PTEN-deficient prostate cancer.

  10. Systematic analysis of the PTEN 5' leader identifies a major AUU initiated proteoform.

    PubMed

    Tzani, Ioanna; Ivanov, Ivaylo P; Andreev, Dmitri E; Dmitriev, Ruslan I; Dean, Kellie A; Baranov, Pavel V; Atkins, John F; Loughran, Gary

    2016-05-01

    Abundant evidence for translation within the 5' leaders of many human genes is rapidly emerging, especially, because of the advent of ribosome profiling. In most cases, it is believed that the act of translation rather than the encoded peptide is important. However, the wealth of available sequencing data in recent years allows phylogenetic detection of sequences within 5' leaders that have emerged under coding constraint and therefore allow for the prediction of functional 5' leader translation. Using this approach, we previously predicted a CUG-initiated, 173 amino acid N-terminal extension to the human tumour suppressor PTEN. Here, a systematic experimental analysis of translation events in the PTEN 5' leader identifies at least two additional non-AUG-initiated PTEN proteoforms that are expressed in most human cell lines tested. The most abundant extended PTEN proteoform initiates at a conserved AUU codon and extends the canonical AUG-initiated PTEN by 146 amino acids. All N-terminally extended PTEN proteoforms tested retain the ability to downregulate the PI3K pathway. We also provide evidence for the translation of two conserved AUG-initiated upstream open reading frames within the PTEN 5' leader that control the ratio of PTEN proteoforms.

  11. Apoptotic effects of signal transduction inhibitors on human tumor cells with different PTEN expression.

    PubMed

    Pfeiler, Georg; Horn, Felicitas; Lattrich, Claus; Klappenberger, Stefanie; Ortmann, Olaf; Treeck, Oliver

    2007-11-01

    An important mechanism of antitumoral targeted therapies is the induction of apoptosis in tumor cells. Tamoxifen and trastuzumab (Herceptin), respectively, are able to trigger apoptosis in human breast cancer cells. But, frequently altered apoptotic signal cascades, for instance through PTEN mutations, help tumor cells to escape antitumoral therapy. We studied to what extent the apoptotic effect of signal-transduction inhibitors is dependent on PTEN expression. PTEN expression was analysed by Western blot analysis in tumor cell lines of the breast (BT-474, MCF-7, MDA-MB-231), ovary (BG-1, SK-OV-3) and endometrium (Ishikawa, HEC-1A). Apoptotic effects of tamoxifen, trastuzumab, ZD1839 (Iressa) and different mitogen-activated protein kinase (MAP) inhibitors were measured after 24 h of treatment. Cellular apoptosis was determined by the detection of cytoplasmic histone-DNA complexes. The tested tumor cell lines exhibited a different PTEN expression, ranging from a high expression (ovarian cancer cell line BG-1 and BT-474 breast cancer cells) to a total absence of PTEN expression (endometrial Ishikawa cells). The apoptotic effect of receptor-targeting drugs (tamoxifen, trastuzumab, ZD1839) was dependent both on receptor expression and PTEN expression. When cells were treated with MAPK inhibitors, no correlation between PTEN expression and the apoptosis rate was observed. Our data underline the importance of PTEN expression regarding the induction of apoptosis through various targeted therapies.

  12. Loss of Pten promotes angiogenesis and enhanced vegfaa expression in zebrafish.

    PubMed

    Choorapoikayil, Suma; Weijts, Bart; Kers, Rianne; de Bruin, Alain; den Hertog, Jeroen

    2013-09-01

    Angiogenesis, the emergence of vessels from an existing vascular network, is pathologically associated with tumor progression and is of great interest for therapeutic intervention. PTEN is a frequently mutated tumor suppressor and has been linked to the progression of many types of tumors, including hemangiosarcomas in zebrafish. Here, we report that mutant zebrafish embryos lacking functional Pten exhibit enhanced angiogenesis, accompanied by elevated levels of phosphorylated Akt (pAkt). Inhibition of phosphoinositide 3-kinase (PI3K) by LY294002 treatment and application of sunitinib, a widely used anti-angiogenic compound, suppressed enhanced angiogenesis in Pten mutants. Vegfaa has a crucial role in angiogenesis and vegfaa expression was upregulated in embryos lacking functional Pten. Interestingly, vegfaa expression was also upregulated in hemangiosarcomas from haploinsufficient adult zebrafish Pten mutants. Elevated vegfaa expression in mutant embryos lacking functional Pten was suppressed by LY294002. Surprisingly, sunitinib treatment dramatically enhanced vegfaa expression in Pten mutant embryos, which might account for tumor relapse in human patients who are treated with sunitinib. Combined treatment with suboptimal concentrations of sunitinib and LY294002 rescued enhanced angiogenesis in pten mutant embryos without the dramatic increase in vegfaa expression, suggesting a new approach for therapeutic intervention in VEGFR-signaling-dependent tumors.

  13. Systematic analysis of the PTEN 5′ leader identifies a major AUU initiated proteoform

    PubMed Central

    Tzani, Ioanna; Ivanov, Ivaylo P.; Andreev, Dmitri E.; Dmitriev, Ruslan I.; Dean, Kellie A.; Baranov, Pavel V.; Atkins, John F.; Loughran, Gary

    2016-01-01

    Abundant evidence for translation within the 5′ leaders of many human genes is rapidly emerging, especially, because of the advent of ribosome profiling. In most cases, it is believed that the act of translation rather than the encoded peptide is important. However, the wealth of available sequencing data in recent years allows phylogenetic detection of sequences within 5′ leaders that have emerged under coding constraint and therefore allow for the prediction of functional 5′ leader translation. Using this approach, we previously predicted a CUG-initiated, 173 amino acid N-terminal extension to the human tumour suppressor PTEN. Here, a systematic experimental analysis of translation events in the PTEN 5′ leader identifies at least two additional non-AUG-initiated PTEN proteoforms that are expressed in most human cell lines tested. The most abundant extended PTEN proteoform initiates at a conserved AUU codon and extends the canonical AUG-initiated PTEN by 146 amino acids. All N-terminally extended PTEN proteoforms tested retain the ability to downregulate the PI3K pathway. We also provide evidence for the translation of two conserved AUG-initiated upstream open reading frames within the PTEN 5′ leader that control the ratio of PTEN proteoforms. PMID:27249819

  14. PTEN deficiency reprogrammes human neural stem cells towards a glioblastoma stem cell-like phenotype.

    PubMed

    Duan, Shunlei; Yuan, Guohong; Liu, Xiaomeng; Ren, Ruotong; Li, Jingyi; Zhang, Weizhou; Wu, Jun; Xu, Xiuling; Fu, Lina; Li, Ying; Yang, Jiping; Zhang, Weiqi; Bai, Ruijun; Yi, Fei; Suzuki, Keiichiro; Gao, Hua; Esteban, Concepcion Rodriguez; Zhang, Chuanbao; Izpisua Belmonte, Juan Carlos; Chen, Zhiguo; Wang, Xiaomin; Jiang, Tao; Qu, Jing; Tang, Fuchou; Liu, Guang-Hui

    2015-12-03

    PTEN is a tumour suppressor frequently mutated in many types of cancers. Here we show that targeted disruption of PTEN leads to neoplastic transformation of human neural stem cells (NSCs), but not mesenchymal stem cells. PTEN-deficient NSCs display neoplasm-associated metabolic and gene expression profiles and generate intracranial tumours in immunodeficient mice. PTEN is localized to the nucleus in NSCs, binds to the PAX7 promoter through association with cAMP responsive element binding protein 1 (CREB)/CREB binding protein (CBP) and inhibits PAX7 transcription. PTEN deficiency leads to the upregulation of PAX7, which in turn promotes oncogenic transformation of NSCs and instates 'aggressiveness' in human glioblastoma stem cells. In a large clinical database, we find increased PAX7 levels in PTEN-deficient glioblastoma. Furthermore, we identify that mitomycin C selectively triggers apoptosis in NSCs with PTEN deficiency. Together, we uncover a potential mechanism of how PTEN safeguards NSCs, and establish a cellular platform to identify factors involved in NSC transformation, potentially permitting personalized treatment of glioblastoma.

  15. Decrease in PTEN and increase in Akt expression and neuron size in aged rat spinal cord

    PubMed Central

    Rodrigues De Amorim, Miguel Augusto; Garcia-Segura, Luis Miguel; Goya, Rodolfo Gustavo; Portiansky, Enrique Leo

    2010-01-01

    PTEN is a tumor suppressor gene known to play an important role in the regulation of cell size. In this study we compared PTEN expression in the spinal cord of young (5 mo.) versus aged (32 mo.) female rats and correlated them with alterations in neuron size and morphology in the same animals. Total and phosphorylated PTEN (pPTEN) as well as its downstream target phosphorylated Akt (pAkt) were assessed by western blotting. Spinal cord neurons were morphometrically characterized. Total PTEN, pPTEN and total Akt expression were significantly higher in young rats than in aged animals. Expression of pAkt was stronger in aged animals. A significant increase in neuronal size was observed in large motoneurons of aged as compared with young rats. Our data show that in the spinal cord of rats, neuronal PTEN expression diminishes with advanced age while neuronal size increases. These results suggest that in the spinal cord, an age-related reduction in PTEN and increase of pAkt expression may be involved in the progressive enlargement of neurons. PMID:20347952

  16. Efficacy of targeted AKT inhibition in genetically engineered mouse models of PTEN-deficient prostate cancer

    PubMed Central

    De Velasco, Marco A.; Kura, Yurie; Yoshikawa, Kazuhiro; Nishio, Kazuto; Davies, Barry R.; Uemura, Hirotsugu

    2016-01-01

    The PI3K/AKT pathway is frequently altered in advanced human prostate cancer mainly through the loss of functional PTEN, and presents as potential target for personalized therapy. Our aim was to determine the therapeutic potential of the pan-AKT inhibitor, AZD5363, in PTEN-deficient prostate cancer. Here we used a genetically engineered mouse (GEM) model of PTEN-deficient prostate cancer to evaluate the in vivo pharmacodynamic and antitumor activity of AZD5363 in castration-naïve and castration-resistant prostate cancer. An additional GEM model, based on the concomitant inactivation of PTEN and Trp53 (P53), was established as an aggressive model of advanced prostate cancer and was used to further evaluate clinically relevant endpoints after treatment with AZD5363. In vivo pharmacodynamic studies demonstrated that AZD5363 effectively inhibited downstream targets of AKT. AZD5363 monotherapy significantly reduced growth of tumors in castration-naïve and castration-resistant models of PTEN-deficient prostate cancer. More importantly, AZD5363 significantly delayed tumor growth and improved overall survival and progression-free survival in PTEN/P53 double knockout mice. Our findings demonstrate that AZD5363 is effective against GEM models of PTEN-deficient prostate cancer and provide lines of evidence to support further investigation into the development of treatment strategies targeting AKT for the treatment of PTEN-deficient prostate cancer. PMID:26910118

  17. Conjugated linoleic acids attenuate FSH- and IGF1-stimulated cell proliferation; IGF1, GATA4, and aromatase expression; and estradiol-17β production in buffalo granulosa cells involving PPARγ, PTEN, and PI3K/Akt.

    PubMed

    Sharma, Isha; Singh, Dheer

    2012-09-01

    Conjugated linoleic acid (CLA) has drawn much interest in last two decades in the area ranging from anticancer activity to obesity. A number of research papers have been published recently with regard to CLA's additional biological functions as reproductive benefits. However, not much is known how this mixture of isomeric compounds mediates its beneficial effects particularly on fertility. In this study, we demonstrated the cross talk between downstream signaling of CLA and important hormone regulators of endocrine system, i.e. FSH and IGF1, on buffalo granulosa cell function (proliferation and steroidogenesis). Experiments were performed in primary serum-free buffalo granulosa cell culture, where cells were incubated with CLA in combination with FSH (25 ng/ml) and IGF1 (50  ng/ml). Results showed that 10 μM CLA inhibits FSH- and IGF1-induced granulosa cell proliferation; aromatase, GATA4, and IGF1 mRNA; and estradiol-17β production. Western blot analysis of total cell lysates revealed that CLA intervenes the IGF1 signaling by decreasing p-Akt. In addition, CLA was found to upregulate peroxisome proliferator-activated receptor-gamma (PPARG) and phosphatase and tensin homolog (PTEN) level in granulosa cells. Further study using PPARG- and PTEN-specific inhibitors supports the potential role of CLA in granulosa cell proliferation and steroidogenesis involving PPARG, PTEN, and PI3K/Akt pathway.

  18. Tumor-suppressor NFκB2 p100 interacts with ERK2 and stabilizes PTEN mRNA via inhibition of miR-494.

    PubMed

    Wang, Y; Xu, J; Gao, G; Li, J; Huang, H; Jin, H; Zhu, J; Che, X; Huang, C

    2016-08-01

    Emerging evidence from The Cancer Genome Atlas has revealed that nuclear factor κB2 (nfκb2) gene encoding p100 is genetically deleted or mutated in human cancers, implicating NFκB2 as a potential tumor suppressor. However, the molecular mechanism underlying the antitumorigenic action of p100 remains poorly understood. Here we report that p100 inhibits cancer cell anchorage-independent growth, a hallmark of cellular malignancy, by stabilizing the tumor-suppressor phosphatase and tensin homolog (PTEN) mRNA via a mechanism that is independent of p100's inhibitory role in NFκB activation. We further demonstrate that the regulatory effect of p100 on PTEN expression is mediated by its downregulation of miR-494 as a result of the inactivation of extracellular signal-regulated kinase 2 (ERK2), in turn leading to inhibition of c-Jun/activator protein-1-dependent transcriptional activity. Furthermore, we identify that p100 specifically interacts with non-phosphorylated ERK2 and prevents ERK2 phosphorylation and nuclear translocation. Moreover, the death domain at C-terminal of p100 is identified as being crucial and sufficient for its interaction with ERK2. Taken together, our findings provide novel mechanistic insights into the understanding of the tumor-suppressive role for NFκB2 p100. PMID:26686085

  19. PTEN/PI3K/Akt/VEGF signaling and the cross talk to KRIT1, CCM2, and PDCD10 proteins in cerebral cavernous malformations.

    PubMed

    Kar, Souvik; Samii, Amir; Bertalanffy, Helmut

    2015-04-01

    Cerebral cavernous malformations (CCM) are common vascular malformation of the brain and are associated with abnormal angiogenesis. Although the exact etiology and the underlying molecular mechanism are still under investigation, recent advances in the identification of the mutations in three genes and their interactions with different signaling pathways have shed light on our understanding of CCM pathogenesis. The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is known to play a major role in angiogenesis. Studies have shown that the phosphatase and tensin homologue deleted on chromosome ten (PTEN), a tumor suppressor, is an antagonist regulator of the PI3K/Akt pathway and mediates angiogenesis by activating vascular endothelial growth factor (VEGF) expression. Here, we provide an update literature review on the current knowledge of the PTEN/PI3K/Akt/VEGF signaling in angiogenesis, more importantly in CCM pathogenesis. In addition to reviewing the current literatures, this article will also focus on the structural domain of the three CCM proteins and their interacting partners. Understanding the biology of these proteins with respect to their signaling counterpart will help to guide future research towards new therapeutic targets applicable for CCM treatment.

  20. Administration of a PTEN inhibitor BPV(pic) attenuates early brain injury via modulating AMPA receptor subunits after subarachnoid hemorrhage in rats.

    PubMed

    Chen, Yujie; Luo, Chunxia; Zhao, Mingyue; Li, Qiang; Hu, Rong; Zhang, John H; Liu, Zhi; Feng, Hua

    2015-02-19

    The aim of this study was to investigate whether the phosphatase and tensin homolog deleted on chromosome ten (PTEN) inhibitor dipotassium bisperoxo(pyridine-2-carboxyl) oxovanadate (BPV(pic)) attenuates early brain injury by modulating α-amino-3-hydroxy-5-methyl-4-isoxa-zolep-propionate (AMPA) receptor subunits after subarachnoid hemorrhage (SAH). A standard intravascular perforation model was used to produce the experimental SAH in Sprague-Dawley rats. BPV(pic) treatment (0.2mg/kg) was evaluated for effects on neurological score, brain water content, Evans blue extravasation, hippocampal neuronal death and AMPA receptor subunits alterations after SAH. We found that BPV(pic) is effective in attenuating BBB disruption, lowering edema, reducing hippocampal neural death and improving neurological outcomes. In addition, the AMPA receptor subunit GluR1 protein expression at cytomembrane was downregulated, whereas the expression of GluR2 and GluR3 was upregulated after BPV(pic) treatment. Our results suggest that PTEN inhibited by BPV(pic) plays a neuroprotective role in SAH pathophysiology, possibly by alterations in glutamate AMPA receptor subunits.

  1. Pten loss promotes MAPK pathway dependency in HER2/neu breast carcinomas

    PubMed Central

    Ebbesen, Saya H.; Scaltriti, Maurizio; Bialucha, Carl U.; Morse, Natasha; Kastenhuber, Edward R.; Wen, Hannah Y.; Dow, Lukas E.; Baselga, José; Lowe, Scott W.

    2016-01-01

    Loss of the tumor suppressor gene PTEN is implicated in breast cancer progression and resistance to targeted therapies, and is thought to promote tumorigenesis by activating PI3K signaling. In a transgenic model of breast cancer, Pten suppression using a tetracycline-regulatable short hairpin (sh)RNA cooperates with human epidermal growth factor receptor 2 (HER2/neu), leading to aggressive and metastatic disease with elevated signaling through PI3K and, surprisingly, the mitogen-activated protein kinase (MAPK) pathway. Restoring Pten function is sufficient to down-regulate both PI3K and MAPK signaling and triggers dramatic tumor regression. Pharmacologic inhibition of MAPK signaling produces similar effects to Pten restoration, suggesting that the MAPK pathway contributes to the maintenance of advanced breast cancers harboring Pten loss. PMID:26929372

  2. An inducible knockout mouse to model the cell-autonomous role of PTEN in initiating endometrial, prostate and thyroid neoplasias

    PubMed Central

    Mirantes, Cristina; Eritja, Núria; Dosil, Maria Alba; Santacana, Maria; Pallares, Judit; Gatius, Sónia; Bergadà, Laura; Maiques, Oscar; Matias-Guiu, Xavier; Dolcet, Xavier

    2013-01-01

    SUMMARY PTEN is one of the most frequently mutated tumor suppressor genes in human cancers. The role of PTEN in carcinogenesis has been validated by knockout mouse models. PTEN heterozygous mice develop neoplasms in multiple organs. Unfortunately, the embryonic lethality of biallelic excision of PTEN has inhibited the study of complete PTEN deletion in the development and progression of cancer. By crossing PTEN conditional knockout mice with transgenic mice expressing a tamoxifen-inducible Cre-ERT under the control of a chicken actin promoter, we have generated a tamoxifen-inducible mouse model that allows temporal control of PTEN deletion. Interestingly, administration of a single dose of tamoxifen resulted in PTEN deletion mainly in epithelial cells, but not in stromal, mesenchymal or hematopoietic cells. Using the mT/mG double-fluorescent Cre reporter mice, we demonstrate that epithelial-specific PTEN excision was caused by differential Cre activity among tissues and cells types. Tamoxifen-induced deletion of PTEN resulted in extremely rapid and consistent formation of endometrial in situ adenocarcinoma, prostate intraepithelial neoplasia and thyroid hyperplasia. We also analyzed the role of PTEN ablation in other epithelial cells, such as the tubular cells of the kidney, hepatocytes, colonic epithelial cells or bronchiolar epithelium, but those tissues did not exhibit neoplastic growth. Finally, to validate this model as a tool to assay the efficacy of anti-tumor drugs in PTEN deficiency, we administered the mTOR inhibitor everolimus to mice with induced PTEN deletion. Everolimus dramatically reduced the progression of endometrial proliferations and significantly reduced thyroid hyperplasia. This model could be a valuable tool to study the cell-autonomous mechanisms involved in PTEN-loss-induced carcinogenesis and provides a good platform to study the effect of anti-neoplastic drugs on PTEN-negative tumors. PMID:23471917

  3. PTEN Inhibition Improves Muscle Regeneration in Mice Fed a High-Fat Diet

    PubMed Central

    Hu, Zhaoyong; Wang, Huiling; Lee, In Hee; Modi, Swati; Wang, Xiaonan; Du, Jie; Mitch, William E.

    2010-01-01

    OBJECTIVE Mechanisms impairing wound healing in diabetes are poorly understood. To identify mechanisms, we induced insulin resistance by chronically feeding mice a high-fat diet (HFD). We also examined the regulation of phosphatidylinositol 3,4,5-trisphosphate (PIP3) during muscle regeneration because augmented IGF-1 signaling can improve muscle regeneration. RESEARCH DESIGN AND METHODS Muscle regeneration was induced by cardiotoxin injury, and we evaluated satellite cell activation and muscle maturation in HFD-fed mice. We also measured PIP3 and the enzymes regulating its level, IRS-1–associated phosphatidylinositol 3-kinase (PI3K) and PTEN. Using primary cultures of muscle, we examined how fatty acids affect PTEN expression and how PTEN knockout influences muscle growth. Mice with muscle-specific PTEN knockout were used to examine how the HFD changes muscle regeneration. RESULTS The HFD raised circulating fatty acids and impaired the growth of regenerating myofibers while delaying myofiber maturation and increasing collagen deposition. These changes were independent of impaired proliferation of muscle progenitor or satellite cells but were principally related to increased expression of PTEN, which reduced PIP3 in muscle. In cultured muscle cells, palmitate directly stimulated PTEN expression and reduced cell growth. Knocking out PTEN restored cell growth. In mice, muscle-specific PTEN knockout improved the defects in muscle repair induced by HFD. CONCLUSIONS Insulin resistance impairs muscle regeneration by preventing myofiber maturation. The mechanism involves fatty acid–stimulated PTEN expression, which lowers muscle PIP3. If similar pathways occur in diabetic patients, therapeutic strategies directed at improving the repair of damaged muscle could include suppression of PTEN activity. PMID:20200318

  4. Microenvironment-induced PTEN loss by exosomal microRNA primes brain metastasis outgrowth.

    PubMed

    Zhang, Lin; Zhang, Siyuan; Yao, Jun; Lowery, Frank J; Zhang, Qingling; Huang, Wen-Chien; Li, Ping; Li, Min; Wang, Xiao; Zhang, Chenyu; Wang, Hai; Ellis, Kenneth; Cheerathodi, Mujeeburahiman; McCarty, Joseph H; Palmieri, Diane; Saunus, Jodi; Lakhani, Sunil; Huang, Suyun; Sahin, Aysegul A; Aldape, Kenneth D; Steeg, Patricia S; Yu, Dihua

    2015-11-01

    The development of life-threatening cancer metastases at distant organs requires disseminated tumour cells' adaptation to, and co-evolution with, the drastically different microenvironments of metastatic sites. Cancer cells of common origin manifest distinct gene expression patterns after metastasizing to different organs. Clearly, the dynamic interaction between metastatic tumour cells and extrinsic signals at individual metastatic organ sites critically effects the subsequent metastatic outgrowth. Yet, it is unclear when and how disseminated tumour cells acquire the essential traits from the microenvironment of metastatic organs that prime their subsequent outgrowth. Here we show that both human and mouse tumour cells with normal expression of PTEN, an important tumour suppressor, lose PTEN expression after dissemination to the brain, but not to other organs. The PTEN level in PTEN-loss brain metastatic tumour cells is restored after leaving the brain microenvironment. This brain microenvironment-dependent, reversible PTEN messenger RNA and protein downregulation is epigenetically regulated by microRNAs from brain astrocytes. Mechanistically, astrocyte-derived exosomes mediate an intercellular transfer of PTEN-targeting microRNAs to metastatic tumour cells, while astrocyte-specific depletion of PTEN-targeting microRNAs or blockade of astrocyte exosome secretion rescues the PTEN loss and suppresses brain metastasis in vivo. Furthermore, this adaptive PTEN loss in brain metastatic tumour cells leads to an increased secretion of the chemokine CCL2, which recruits IBA1-expressing myeloid cells that reciprocally enhance the outgrowth of brain metastatic tumour cells via enhanced proliferation and reduced apoptosis. Our findings demonstrate a remarkable plasticity of PTEN expression in metastatic tumour cells in response to different organ microenvironments, underpinning an essential role of co-evolution between the metastatic cells and their microenvironment during

  5. Characterization of the phosphatidylinositol-glycan membrane anchor of human placental alkaline phosphatase

    SciTech Connect

    Howard, A.D.; Berger, J.; Gerber, L.; Familletti, P.; Udenfriend, S.

    1987-09-01

    Placental alkaline phosphatase (orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1) is a member of a diverse group of membrane proteins whose attachment to the lipid bilayer is mediated by a phosphatidylinositol-glycan. To investigate structural aspects of the glycolipid anchor, cultured WISH cells were used because, they produce the enzyme in abundant quantities. When cell suspensions were incubated with purified phosphatidylinositol-specific phospholipase C, most of the placental alkaline phosphatase was released from membranes in a hydrophilic form. On incubation of the cells with (/sup 14/C)ethanolamine, (/sup 14/C)myristic acid, or myo(/sup 3/H)inositol, each was incorporated into the phosphatase near the carboxyl terminus, showing that these components, which are found in other phosphatidylinositol membrane-linked proteins, are also present in placental alkaline phosphatase.

  6. MicroRNA-20b (miR-20b) Promotes the Proliferation, Migration, Invasion, and Tumorigenicity in Esophageal Cancer Cells via the Regulation of Phosphatase and Tensin Homologue Expression

    PubMed Central

    Xiao, Bin

    2016-01-01

    Increasing evidence has indicated that many microRNAs participate in the development and progression of esophageal cancer and gene expression regulation. MicroRNA-20b (miR-20b) has been reported to be aberrantly expressed in various cancers, but its exact role in esophageal cancer cells remains unclear so far. Therefore, we detected the levels of miR-20b in esophageal tumor tissues and their adjacent normal tissues, and various esophageal cancer cell lines by qRT-PCR. We also explored the effects of miR-20b on cell proliferation, migration, invasion and tumorigenicity of esophageal carcinoma cells through transfection with miR-20b mimics or inhibitor to upregulate or downregulate miR-20b expression in the esophageal cancer cells Eca-109 and KYSE-150, respectively. Additionally, the 3'-untranslated region (3'-UTR) of phosphatase and tensin homologue (PTEN) binding with miR-20b was analyzed by dual-luciferase reporter assays. The results indicated that miR-20b expression level in esophageal tumor tissues was significantly increased compared with their neighboring normal tissues, but its expression was inverse with PTEN protein expression. Luciferase assays confirmed that the 3'-UTR of PTEN was a target of miR-20b in esophageal cancer cells. MiR-20b upregulation promoted cell proliferation, migration, invasiveness, and tumor growth, and decreased apoptosis, and reduced PTEN protein level but not mRNA expression in Eca-109 cells. Conversely, downregulation of miR-20b suppressed these processes in KYSE-150 cells, and enhanced PTEN protein expression. These data indicate that miR-20b plays important roles in tumorigenesis of esophageal cancer possibly via regulation of PTEN expression, and it may be a potential therapeutic target for esophageal cancer treatment. PMID:27701465

  7. Concomitant Inhibition of PI3Kβ and BRAF or MEK in PTEN-Deficient/BRAF-Mutant Melanoma Treatment: Preclinical Assessment of SAR260301 Oral PI3Kβ-Selective Inhibitor.

    PubMed

    Bonnevaux, Hélène; Lemaitre, Olivier; Vincent, Loic; Levit, Mikhail N; Windenberger, Fanny; Halley, Frank; Delorme, Cécile; Lengauer, Christoph; Garcia-Echeverria, Carlos; Virone-Oddos, Angela

    2016-07-01

    Class IA PI3K pathway activation resulting from PTEN deficiency has been associated with lack of sensitivity of melanoma to BRAF kinase inhibitors. Although previous studies have shown synergistic activity when pan-PI3K inhibitors were combined with MAPK inhibitors in the treatment of melanoma exhibiting concurrent genetic abnormalities, overlapping adverse events in patients limit optimal dosing and clinical application. With the aim of specifically targeting PTEN-deficient cancers and minimizing the potential for on-target toxicity when inhibiting multiple PI3K isoforms, we developed a program to discover PI3Kβ-selective kinase inhibitors and identified SAR260301 as a potent PI3Kβ-selective, orally available compound, which is now in clinical development. Herein, we provide a detailed biological characterization of SAR260301, and show that this compound has outstanding biochemical and cellular selectivity for the PI3Kβ isoform versus the α, δ, and γ isoforms and a large panel of protein and lipid kinases. We demonstrate that SAR260301 blocks PI3K pathway signaling preferentially in PTEN-deficient human tumor models, and has synergistic antitumor activity when combined with vemurafenib (BRAF inhibitor) or selumetinib (MEK inhibitor) in PTEN-deficient/BRAF-mutated human melanoma tumor models. Combination treatments were very well tolerated, suggesting the potential for a superior safety profile at optimal dosing using selective compounds to inhibit multiple signaling pathways. Together, these experiments provide a preclinical proof-of-concept for safely combining inhibitors of PI3Kβ and BRAF or MEK kinase modulators to improve antitumor activity in PTEN-deficient/BRAF-mutant melanoma, and support the evaluation of SAR260301-based combinations in clinical studies. Mol Cancer Ther; 15(7); 1460-71. ©2016 AACR. PMID:27196754

  8. Effect of fructose and 3,5-diiodothyronine (3,5-T(2)) on lipid accumulation and insulin signalling in non-alcoholic fatty liver disease (NAFLD)-like rat primary hepatocytes.

    PubMed

    Gnocchi, D; Massimi, M; Alisi, A; Incerpi, S; Bruscalupi, G

    2014-05-01

    Non-alcoholic fatty liver disease (NAFLD) is nowadays considered as one of the most serious pathological conditions affecting the liver. NAFLD is supposed to be initiated by the accumulation of lipids in the liver, which finally results in an impaired hepatic insulin signalling. Many researchers have recently focused their attention on the role played by fructose as a NAFLD-triggering agent, because of the increased diffusion of fructose-sweetened food. However, epidemiological data do not permit to evaluate the role of fructose per se, because these foods are often associated with elevated energy intake and unhealthy lifestyle. In the present work, we analysed the effects of fructose on the accumulation of lipids and insulin signalling in rat primary hepatocytes. Moreover, we investigated the effect of the thyroid hormone metabolite, devoid of thyrotoxic effects, 3,5-diiodothyronine (3,5-T2) over the same parameters. To evaluate the effect on insulin signalling we took into consideration three key proteins, such as p85 subunit of phosphatidylinositol 3-kinase (PI3K), phosphatase and tensin homolog (PTEN), and Akt. Our results show that fructose in vitro, in the range of physiological concentrations, was not able to stimulate either lipid accumulation or to impair insulin signalling in our NAFLD-like rat primary hepatocytes. Our data thus support the idea that fructose per se may exert detrimental effects mainly triggering systemic effects, rather than directly affecting isolated hepatocytes. Moreover, we demonstrated that 3,5-T2, at physiological levels, reduces lipid content and triggers phosphorylation of Akt in an insulin receptor-independent manner, revealing new interesting properties as a biologically active molecule.

  9. Fine-Tuning of PI3K/AKT Signalling by the Tumour Suppressor PTEN Is Required for Maintenance of Flight Muscle Function and Mitochondrial Integrity in Ageing Adult Drosophila melanogaster

    PubMed Central

    Mensah, Lawrence B.; Davison, Claire; Fan, Shih-Jung; Morris, John F.; Goberdhan, Deborah C. I.; Wilson, Clive

    2015-01-01

    Insulin/insulin-like growth factor signalling (IIS), acting primarily through the PI3-kinase (PI3K)/AKT kinase signalling cassette, plays key evolutionarily conserved regulatory roles in nutrient homeostasis, growth, ageing and longevity. The dysfunction of this pathway has been linked to several age-related human diseases including cancer, Type 2 diabetes and neurodegenerative disorders. However, it remains unclear whether minor defects in IIS can independently induce the age-dependent functional decline in cells that accompany some of these diseases or whether IIS alters the sensitivity to other aberrant signalling. We identified a novel hypomorphic allele of PI3K’s direct antagonist, Phosphatase and tensin homologue on chromosome 10 (Pten), in the fruit fly, Drosophila melanogaster. Adults carrying combinations of this allele, Pten5, combined with strong loss-of-function Pten mutations exhibit subtle or no increase in mass, but are highly susceptible to a wide range of stresses. They also exhibit dramatic upregulation of the oxidative stress response gene, GstD1, and a progressive loss of motor function that ultimately leads to defects in climbing and flight ability. The latter phenotype is associated with mitochondrial disruption in indirect flight muscles, although overall muscle structure appears to be maintained. We show that the phenotype is partially rescued by muscle-specific expression of the Bcl-2 homologue Buffy, which in flies, maintains mitochondrial integrity, modulates energy homeostasis and suppresses cell death. The flightless phenotype is also suppressed by mutations in downstream IIS signalling components, including those in the mechanistic Target of Rapamycin Complex 1 (mTORC1) pathway, suggesting that elevated IIS is responsible for functional decline in flight muscle. Our data demonstrate that IIS levels must be precisely regulated by Pten in adults to maintain the function of the highly metabolically active indirect flight muscles

  10. PTEN enhances the sensitivity of human hepatocellular carcinoma cells to sorafenib.

    PubMed

    Ruan, Zhi-Ping; Xu, Rui; Lv, Yi; Tian, Tao; Wang, Wen-Juan; Guo, Hui; Nan, Ke-Jun

    2012-01-01

    Hepatocellular carcinoma (HCC) is a complex and heterogeneous tumor with several genomic alterations and ranks as the third highest cause of cancer-related death globally. The unresectable or metastatic HCC has very poor prognosis. Although multikinase inhibitor sorafenib can increase the survival of patients with advanced HCC, it is becoming apparent that combination therapies are critical to overcome the complex genomic aberrations in HCC. PTEN, as one of the most commonly inactivated genes in HCC, exerts a wide range of antitumor effects. In this study, we found that PTEN was downregulated in HCC tissues, especially in those tissues with extrahepatic metastasis. And negative PTEN expression cases showed increased proliferation activity. Overexpression of PTEN significantly reduced the proliferation of tumor cells HepG2. In addition, HepG2 cells transfected with PTEN were more sensitive to sorafenib in terms of its ability to inhibit proliferation and to induce apoptosis. Moreover, overexpression of PTEN decreased phosphorylation of MEK, a key downstream effector of RAF/MEK/ERK cascade, and levels of cyclin D1, antiapoptotic Bcl-2, and VEGF. These observations indicated that combination therapies with sorafenib and PTEN overexpression have potential to further improve therapeutic options for HCC.

  11. Mice Lacking Pten in Osteoblasts Have Improved Intramembranous and Late Endochondral Fracture Healing

    PubMed Central

    Burgers, Travis A.; Hoffmann, Martin F.; Collins, Caitlyn J.; Zahatnansky, Juraj; Alvarado, Martin A.; Morris, Michael R.; Sietsema, Debra L.; Mason, James J.; Jones, Clifford B.; Ploeg, Heidi L.; Williams, Bart O.

    2013-01-01

    The failure of an osseous fracture to heal (development of a non-union) is a common and debilitating clinical problem. Mice lacking the tumor suppressor Pten in osteoblasts have dramatic and progressive increases in bone volume and density throughout life. Since fracture healing is a recapitulation of bone development, we investigated the process of fracture healing in mice lacking Pten in osteoblasts (Ocn-cretg/+;Ptenflox/flox). Mid-diaphyseal femoral fractures induced in wild-type and Ocn-cretg/+;Ptenflox/flox mice were studied via micro-computed tomography (µCT) scans, biomechanical testing, histological and histomorphometric analysis, and protein expression analysis. Ocn-cretg/+;Ptenflox/flox mice had significantly stiffer and stronger intact bones relative to controls in all cohorts. They also had significantly stiffer healing bones at day 28 post-fracture (PF) and significantly stronger healing bones at days 14, 21, and 28 PF. At day 7 PF, the proximal and distal ends of the Pten mutant calluses were more ossified. By day 28 PF, Pten mutants had larger and more mineralized calluses. Pten mutants had improved intramembranous bone formation during healing originating from the periosteum. They also had improved endochondral bone formation later in the healing process, after mature osteoblasts are present in the callus. Our results indicate that the inhibition of Pten can improve fracture healing and that the local or short-term use of commercially available Pten-inhibiting agents may have clinical application for enhancing fracture healing. PMID:23675511

  12. PTEN deficiency mediates a reciprocal response to IGF-1 and mTOR inhibition

    PubMed Central

    Patel, Mukund; Gomez, Nicholas C.; McFadden, Andrew W.; Moats-Staats, Billie M.; Wu, Sam; Rojas, Andres; Sapp, Travis; Simon, Jeremy M.; Smith, Scott V.; Kaiser-Rogers, Kathleen; Davis, Ian J.

    2014-01-01

    Recent evidence implicates the insulin-like growth factor (IGF) pathway in development of Ewing Sarcoma, a highly malignant bone and soft tissue tumor that primarily affects children and young adults. Despite promising results from preclinical studies of therapies that target this pathway, early phase clinical trials have shown that a significant fraction of patients do not benefit, suggesting that cellular factors determine tumor sensitivity. Using FAIRE-seq, a chromosomal deletion of the PTEN locus in a Ewing sarcoma cell line was identified. In primary tumors PTEN deficiency was observed in a large subset of cases, although not mediated by large chromosomal deletions. PTEN loss resulted in hyper-activation of the AKT signaling pathway. PTEN rescue led to decreased proliferation, inhibition of colony formation, and increased apoptosis. Strikingly, PTEN loss decreased sensitivity to IGF-1R inhibitors but increased responsiveness to temsirolimus, a potent mTOR inhibitor, as marked by induction of autophagy. These results suggest that PTEN is lost in a significant fraction of primary tumors and this deficiency may have therapeutic consequences by concurrently attenuating responsiveness to IGF-1R inhibition while increasing activity of mTOR inhibitors. The identification of PTEN status in the tumors of patients with recurrent disease could help guide the selection of therapies. PMID:24994750

  13. Endogenous S-sulfhydration of PTEN helps protect against modification by nitric oxide

    SciTech Connect

    Ohno, Kazuki; Okuda, Kosaku; Uehara, Takashi

    2015-01-02

    Highlights: • PTEN is S-sulfhydrated endogenously in SH-SY5Y human neuroblastoma cells. • Preventing this modification by knocking down CBS renders PTEN sensitive to NO. • pAkt levels are increased significantly in CBS siRNA-transfected cells. • H{sub 2}S functions as an endogenous regulator of PTEN in neuronal cells. - Abstract: Hydrogen sulfide (H{sub 2}S) is a gaseous regulatory factor produced by several enzymes, and plays a pivotal role in processes such as proliferation or vasodilation. Recent reports demonstrated the physiological and pathophysiological functions of H{sub 2}S in neurons. PTEN is a target of nitric oxide (NO) or hydrogen peroxide, and the oxidative modification of cysteine (Cys) residue(s) attenuates its enzymatic activity. In the present study, we assessed the effect of H{sub 2}S on the direct modification of PTEN and the resulting downstream signaling. A modified biotin switch assay in SH-SY5Y human neuroblastoma cells revealed that PTEN is S-sulfhydrated endogenously. Subsequently, site-directed mutagenesis demonstrated that both Cys71 and Cys124 in PTEN are targets for S-sulfhydration. Further, the knockdown of cystathionine β-synthetase (CBS) using siRNA decreased this modification in a manner that was correlated to amount of H{sub 2}S. PTEN was more sensitive to NO under these conditions. These results suggest that the endogenous S-sulfhydration of PTEN via CBS/H{sub 2}S plays a role in preventing the S-nitrosylation that would inhibition its enzymatic activity under physiological conditions.

  14. Role of phosphatase activity of soluble epoxide hydrolase in regulating simvastatin-activated endothelial nitric oxide synthase

    PubMed Central

    Hou, Hsin-Han; Liao, Yi-Jen; Hsiao, Sheng-Huang; Shyue, Song-Kun; Lee, Tzong-Shyuan

    2015-01-01

    Soluble epoxide hydrolase (sEH) has C-terminal epoxide hydrolase and N-terminal lipid phosphatase activity. Its hydrolase activity is associated with endothelial nitric oxide synthase (eNOS) dysfunction. However, little is known about the role of sEH phosphatase in regulating eNOS activity. Simvastatin, a clinical lipid-lowering drug, also has a pleiotropic effect on eNOS activation. However, whether sEH phosphatase is involved in simvastatin-activated eNOS activity remains elusive. We investigated the role of sEH phosphatase activity in simvastatin-mediated activation of eNOS in endothelial cells (ECs). Simvastain increased the phosphatase activity of sEH, which was diminished by pharmacological inhibitors of sEH phosphatase. In addition, pharmacological inhibition of sEH phosphatase or overexpressing the inactive phosphatase domain of sEH enhanced simvastatin-induced NO bioavailability, tube formation and phosphorylation of eNOS, Akt, and AMP-activated protein kinase (AMPK). In contrast, overexpressing the phosphatase domain of sEH limited the simvastatin-increased NO biosynthesis and eNOS phosphorylation at Ser1179. Simvastatin evoked epidermal growth factor receptor–c-Src–increased Tyr phosphorylation of sEH and formation of an sEH–Akt–AMPK–eNOS complex, which was abolished by the c-Src kinase inhibitor PP1 or c-Src dominant-negative mutant K298M. These findings suggest that sEH phosphatase activity negatively regulates simvastatin-activated eNOS by impeding the Akt–AMPK–eNOS signaling cascade. PMID:26304753

  15. Role of phosphatase activity of soluble epoxide hydrolase in regulating simvastatin-activated endothelial nitric oxide synthase.

    PubMed

    Hou, Hsin-Han; Liao, Yi-Jen; Hsiao, Sheng-Huang; Shyue, Song-Kun; Lee, Tzong-Shyuan

    2015-08-25

    Soluble epoxide hydrolase (sEH) has C-terminal epoxide hydrolase and N-terminal lipid phosphatase activity. Its hydrolase activity is associated with endothelial nitric oxide synthase (eNOS) dysfunction. However, little is known about the role of sEH phosphatase in regulating eNOS activity. Simvastatin, a clinical lipid-lowering drug, also has a pleiotropic effect on eNOS activation. However, whether sEH phosphatase is involved in simvastatin-activated eNOS activity remains elusive. We investigated the role of sEH phosphatase activity in simvastatin-mediated activation of eNOS in endothelial cells (ECs). Simvastain increased the phosphatase activity of sEH, which was diminished by pharmacological inhibitors of sEH phosphatase. In addition, pharmacological inhibition of sEH phosphatase or overexpressing the inactive phosphatase domain of sEH enhanced simvastatin-induced NO bioavailability, tube formation and phosphorylation of eNOS, Akt, and AMP-activated protein kinase (AMPK). In contrast, overexpressing the phosphatase domain of sEH limited the simvastatin-increased NO biosynthesis and eNOS phosphorylation at Ser1179. Simvastatin evoked epidermal growth factor receptor-c-Src-increased Tyr phosphorylation of sEH and formation of an sEH-Akt-AMPK-eNOS complex, which was abolished by the c-Src kinase inhibitor PP1 or c-Src dominant-negative mutant K298M. These findings suggest that sEH phosphatase activity negatively regulates simvastatin-activated eNOS by impeding the Akt-AMPK-eNOS signaling cascade.

  16. MicroRNA-21 accelerates hepatocyte proliferation in vitro via PI3K/Akt signaling by targeting PTEN

    SciTech Connect

    Yan-nan, Bai; Zhao-yan, Yu; Li-xi, Luo; Jiang, Yi; Qing-jie, Xia

    2014-01-17

    Highlights: •miRNAs-expression patterns of primary hepatocytes under proliferative status. •miR-21 expression level peaked at 12 h after stimulated by EGF. •miR-21 drive rapid S phase entry of primary hepatocytes. •PI3K/Akt signaling was modulated via targeting PTEN by miR-21. -- Abstract: MicroRNAs (miRNAs) are involved in controlling hepatocyte proliferation during liver regeneration. In this study, we established the miRNAs-expression patterns of primary hepatocytes in vitro under stimulation of epidermal growth factor (EGF), and found that microRNA-21 (miR-21) was appreciably up-regulated and peaked at 12 h. In addition, we further presented evidences indicating that miR-21 promotes primary hepatocyte proliferation through in vitro transfecting with miR-21 mimics or inhibitor. We further demonstrated that phosphatidylinositol 3′-OH kinase (PI3K)/Akt signaling was altered accordingly, it is, by targeting phosphatase and tensin homologue deleted on chromosome 10, PI3K/Akt signaling is activated by miR-21 to accelerate hepatocyte rapid S-phase entry and proliferation in vitro.

  17. Restoration of skilled locomotion by sprouting corticospinal axons induced by co-deletion of PTEN and SOCS3

    PubMed Central

    Jin, Duo; Liu, Yuanyuan; Sun, Fang; Wang, Xuhua; Liu, Xuefeng; He, Zhigang

    2015-01-01

    The limited rewiring of the corticospinal tract (CST) only partially compensates the lost functions after stroke, brain trauma and spinal cord injury. Therefore it is important to develop new therapies to enhance the compensatory circuitry mediated by spared CST axons. Here by using a unilateral pyramidotomy model, we find that deletion of cortical suppressor of cytokine signaling 3 (SOCS3), a negative regulator of cytokine-activated pathway, promotes sprouting of uninjured CST axons to the denervated spinal cord. A likely trigger of such sprouting is ciliary neurotrophic factor (CNTF) expressed in local spinal neurons. Such sprouting can be further enhanced by deletion of phosphatase and tensin homolog (PTEN), a mechanistic target of rapamycin (mTOR) negative regulator, resulting in significant recovery of skilled locomotion. Ablation of the corticospinal neurons with sprouting axons abolishes the improved behavioural performance. Furthermore, by optogenetics-based specific CST stimulation, we show a direct limb motor control by sprouting CST axons, providing direct evidence for the reformation of a functional circuit. PMID:26598325

  18. Loss of tumour suppressor PTEN expression in renal injury initiates SMAD3- and p53-dependent fibrotic responses.

    PubMed

    Samarakoon, Rohan; Helo, Sevann; Dobberfuhl, Amy D; Khakoo, Nidah S; Falke, Lucas; Overstreet, Jessica M; Goldschmeding, Roel; Higgins, Paul J

    2015-08-01

    Deregulation of the tumour suppressor PTEN occurs in lung and skin fibrosis and diabetic and ischaemic renal injury. However, the potential role of PTEN and associated mechanisms in the progression of kidney fibrosis is unknown. Tubular and interstitial PTEN expression was dramatically decreased in several models of renal injury, including aristolochic acid nephropathy (AAN), streptozotocin (STZ)-mediated injury and ureteral unilateral obstruction (UUO), correlating with Akt, p53 and SMAD3 activation and fibrosis. Stable silencing of PTEN in HK-2 human tubular epithelial cells induced dedifferentiation and CTGF, PAI-1, vimentin, α-SMA and fibronectin expression, compared to HK-2 cells expressing control shRNA. Furthermore, PTEN knockdown stimulated Akt, SMAD3 and p53(Ser15) phosphorylation, with an accompanying decrease in population density and an increase in epithelial G1 cell cycle arrest. SMAD3 or p53 gene silencing or pharmacological blockade partially suppressed fibrotic gene expression and relieved growth inhibition orchestrated by deficiency or inhibition of PTEN. Similarly, shRNA suppression of PAI-1 rescued the PTEN loss-associated epithelial proliferative arrest. Moreover, TGFβ1-initiated fibrotic gene expression is further enhanced by PTEN depletion. Combined TGFβ1 treatment and PTEN silencing potentiated epithelial cell death via p53-dependent pathways. Thus, PTEN loss initiates tubular dysfunction via SMAD3- and p53-mediated fibrotic gene induction, with accompanying PAI-1-dependent proliferative arrest, and cooperates with TGFβ1 to induce the expression of profibrotic genes and tubular apoptosis.

  19. Hepatic Src Homology Phosphatase 2 Regulates Energy Balance in Mice

    PubMed Central

    Nagata, Naoto; Matsuo, Kosuke; Bettaieb, Ahmed; Bakke, Jesse; Matsuo, Izumi; Graham, James; Xi, Yannan; Liu, Siming; Tomilov, Alexey; Tomilova, Natalia; Gray, Susan; Jung, Dae Young; Ramsey, Jon J.; Kim, Jason K.; Cortopassi, Gino; Havel, Peter J.

    2012-01-01

    The Src homology 2 domain-containing protein-tyrosine phosphatase Src homology phosphatase 2 (Shp2) is a negative regulator of hepatic insulin action in mice fed regular chow. To investigate the role of hepatic Shp2 in lipid metabolism and energy balance, we determined the metabolic effects of its deletion in mice challenged with a high-fat diet (HFD). We analyzed body mass, lipid metabolism, insulin sensitivity, and glucose tolerance in liver-specific Shp2-deficient mice (referred to herein as LSHKO) and control mice fed HFD. Hepatic Shp2 protein expression is regulated by nutritional status, increasing in mice fed HFD and decreasing during fasting. LSHKO mice gained less weight and exhibited increased energy expenditure compared with control mice. In addition, hepatic Shp2 deficiency led to decreased liver steatosis, enhanced insulin-induced suppression of hepatic glucose production, and impeded the development of insulin resistance after high-fat feeding. At the molecular level, LSHKO exhibited decreased hepatic endoplasmic reticulum stress and inflammation compared with control mice. In addition, tyrosine and serine phosphorylation of total and mitochondrial signal transducer and activator of transcription 3 were enhanced in LSHKO compared with control mice. In line with this observation and the increased energy expenditure of LSHKO, oxygen consumption rate was higher in liver mitochondria of LSHKO compared with controls. Collectively, these studies identify hepatic Shp2 as a novel regulator of systemic energy balance under conditions of high-fat feeding. PMID:22619361

  20. PTEN and PI3K/AKT in non-small-cell lung cancer.

    PubMed

    Pérez-Ramírez, Cristina; Cañadas-Garre, Marisa; Molina, Miguel Ángel; Faus-Dáder, María José; Calleja-Hernández, Miguel Ángel

    2015-11-01

    Non-small-cell lung cancer (NSCLC) is the leading cause of cancer deaths worldwide. In the last years, the identification of activating EGFR mutations, conferring increased sensitivity and disease response to tyrosine kinase inhibitors, has changed the prospect of NSCLC patients. The PTEN/PI3K/AKT pathway regulates multiple cellular functions, including cell growth, differentiation, proliferation, survival, motility, invasion and intracellular trafficking. Alterations in this pathway, mainly PTEN inactivation, have been associated with resistance to EGFR-tyrosine kinase inhibitor therapy and lower survival in NSCLC patients. In this review, we will briefly discuss the main PTEN/PI3K/AKT pathway alterations found in NSCLC, as well as the cell processes regulated by PTEN/PI3K/AKT leading to tumorigenesis.

  1. [Phosphoprotein phosphatase nonspecifically hydrolyzes CoA].

    PubMed

    Reziapkin, V I; Moiseenok, A G

    1988-01-01

    CoA hydrolysis was studied by a homogenous phosphoprotein phosphatase (EC 3.1 3.16) preparation from bovine spleen nuclei at pH 5.8. Phosphoprotein phosphatase catalyzed hydrolysis of the CoA 3'-phosphoester bond to form dephospho-CoA and Pi. The Km value for phosphoprotein phosphatase with CoA as substrate was 3.7 mM, the specific activity - 0.26 mmol Pi.min-1.mg-1. Phosphoprotein phosphatase did not essentially catalyze the calcium pantothenate hydrolysis (not more than 2% as compared with the CoA hydrolysis rate). PMID:2849829

  2. Protein phosphatases in pancreatic islets

    PubMed Central

    Ortsäter, Henrik; Grankvist, Nina; Honkanen, Richard E.; Sjöholm1, Åke

    2014-01-01

    The prevalence of diabetes is increasing rapidly world-wide. A cardinal feature of most forms of diabetes is the lack of insulin-producing capability, due to the loss of insulin-producing β-cells, impaired glucose-sensitive insulin secretion from the β-cell, or a combination thereof, the reasons for which largely remain elusive. Reversible phosphorylation is an important and versatile mechanism for regulating the biological activity of many intracellular proteins, which, in turn, controls a variety of cellular functions. For instance, significant changes in protein kinase activities and in protein phosphorylation patterns occur subsequent to stimulation of insulin release by glucose. Therefore, the molecular mechanisms regulating phosphorylation of proteins involved in the insulin secretory process by the β-cell have been extensively investigated. However, far less is known about the role and regulation of protein dephosphorylation by various protein phosphatases. Herein we review extant data implicating serine/threonine and tyrosine phosphatases in various aspects of healthy and diabetic islet biology, ranging from control of hormonal stimulus-secretion coupling to mitogenesis and apoptosis. PMID:24681827

  3. SAHA-induced loss of tumor suppressor Pten gene promotes thyroid carcinogenesis in a mouse model.

    PubMed

    Zhu, Xuguang; Kim, Dong Wook; Zhao, Li; Willingham, Mark C; Cheng, Sheue-Yann

    2016-07-01

    Thyroid cancer is on the rise. Novel approaches are needed to improve the outcome of patients with recurrent and advanced metastatic thyroid cancers. FDA approval of suberoylanilide hydroxamic acid (SAHA; vorinostat), an inhibitor of histone deacetylase, for the treatment of hematological malignancies led to the clinical trials of vorinostat for advanced thyroid cancer. However, patients were resistant to vorinostat treatment. To understand the molecular basis of resistance, we tested the efficacy of SAHA in two mouse models of metastatic follicular thyroid cancer: Thrb(PV/PV) and Thrb(PV/PV)Pten(+/-) mice. In both, thyroid cancer is driven by overactivation of PI3K-AKT signaling. However, the latter exhibit more aggressive cancer progression due to haplodeficiency of the tumor suppressor, the Pten gene. SAHA had no effects on thyroid cancer progression in Thrb(PV/PV) mice, indicative of resistance to SAHA. Unexpectedly, thyroid cancer progressed in SAHA-treated Thrb(PV/PV)Pten(+/-) mice with accelerated occurrence of vascular invasion, anaplastic foci, and lung metastasis. Molecular analyses showed further activated PI3K-AKT in thyroid tumors of SAHA-treated Thrb(PV/PV)Pten(+/-) mice, resulting in the activated effectors, p-Rb, CDK6, p21(Cip1), p-cSrc, ezrin, and matrix metalloproteinases, to increase proliferation and invasion of tumor cells. Single-molecule DNA analysis indicated that the wild-type allele of the Pten gene was progressively lost, whereas carcinogenesis progressed in SAHA-treated Thrb(PV/PV)Pten(+/-) mice. Thus, this study has uncovered a novel mechanism by which SAHA-induced loss of the tumor suppressor Pten gene to promote thyroid cancer progression. Effectors downstream of the Pten loss-induced signaling may be potential targets to overcome resistance of thyroid cancer to SAHA.

  4. Germline disruption of Pten localization causes enhanced sex-dependent social motivation and increased glial production

    PubMed Central

    Tilot, Amanda K.; Gaugler, Mary K.; Yu, Qi; Romigh, Todd; Yu, Wanfeng; Miller, Robert H.; Frazier, Thomas W.; Eng, Charis

    2014-01-01

    PTEN Hamartoma Tumor Syndrome (PHTS) is an autosomal-dominant genetic condition underlying a subset of autism spectrum disorder (ASD) with macrocephaly. Caused by germline mutations in PTEN, PHTS also causes increased risks of multiple cancers via dysregulation of the PI3K and MAPK signaling pathways. Conditional knockout models have shown that neural Pten regulates social behavior, proliferation and cell size. Although much is known about how the intracellular localization of PTEN regulates signaling in cancer cell lines, we know little of how PTEN localization influences normal brain physiology and behavior. To address this, we generated a germline knock-in mouse model of cytoplasm-predominant Pten and characterized its behavioral and cellular phenotypes. The homozygous Ptenm3m4 mice have decreased total Pten levels including a specific drop in nuclear Pten and exhibit region-specific increases in brain weight. The Ptenm3m4 model displays sex-specific increases in social motivation, poor balance and normal recognition memory—a profile reminiscent of some individuals with high functioning ASD. The cytoplasm-predominant protein caused cellular hypertrophy limited to the soma and led to increased NG2 cell proliferation and accumulation of glia. The animals also exhibit significant astrogliosis and microglial activation, indicating a neuroinflammatory phenotype. At the signaling level, Ptenm3m4 mice show brain region-specific differences in Akt activation. These results demonstrate that differing alterations to the same autism-linked gene can cause distinct behavioral profiles. The Ptenm3m4 model is the first murine model of inappropriately elevated social motivation in the context of normal cognition and may expand the range of autism-related behaviors replicated in animal models. PMID:24470394

  5. PTENα, a PTEN isoform translated through alternative initiation, regulates mitochondrial function and energy metabolism.

    PubMed

    Liang, Hui; He, Shiming; Yang, Jingyi; Jia, Xinying; Wang, Pan; Chen, Xi; Zhang, Zhong; Zou, Xiajuan; McNutt, Michael A; Shen, Wen Hong; Yin, Yuxin

    2014-05-01

    PTEN is one of the most frequently mutated genes in human cancer. It is known that PTEN has a wide range of biological functions beyond tumor suppression. Here, we report that PTENα, an N-terminally extended form of PTEN, functions in mitochondrial metabolism. Translation of PTENα is initiated from a CUG codon upstream of and in-frame with the coding region of canonical PTEN. Eukaryotic translation initiation factor 2A (eIF2A) controls PTENα translation, which requires a CUG-centered palindromic motif. We show that PTENα induces cytochrome c oxidase activity and ATP production in mitochondria. TALEN-mediated somatic deletion of PTENα impairs mitochondrial respiratory chain function. PTENα interacts with canonical PTEN to increase PINK1 protein levels and promote energy production. Our studies demonstrate the importance of eIF2A-mediated alternative translation for generation of protein diversity in eukaryotic systems and provide insights into the mechanism by which the PTEN family is involved in multiple cellular processes.

  6. PTEN deletion from adult-generated dentate granule cells disrupts granule cell mossy fiber axon structure.

    PubMed

    LaSarge, Candi L; Santos, Victor R; Danzer, Steve C

    2015-03-01

    Dysregulation of the mTOR-signaling pathway is implicated in the development of temporal lobe epilepsy. In mice, deletion of PTEN from hippocampal dentate granule cells leads to mTOR hyperactivation and promotes the rapid onset of spontaneous seizures. The mechanism by which these abnormal cells initiate epileptogenesis, however, is unclear. PTEN-knockout granule cells develop abnormally, exhibiting morphological features indicative of increased excitatory input. If these cells are directly responsible for seizure genesis, it follows that they should also possess increased output. To test this prediction, dentate granule cell axon morphology was quantified in control and PTEN-knockout mice. Unexpectedly, PTEN deletion increased giant mossy fiber bouton spacing along the axon length, suggesting reduced innervation of CA3. Increased width of the mossy fiber axon pathway in stratum lucidum, however, which likely reflects an unusual increase in mossy fiber axon collateralization in this region, offsets the reduction in boutons per axon length. These morphological changes predict a net increase in granule cell innervation of CA3. Increased diameter of axons from PTEN-knockout cells would further enhance granule cell communication with CA3. Altogether, these findings suggest that amplified information flow through the hippocampal circuit contributes to seizure occurrence in the PTEN-knockout mouse model of temporal lobe epilepsy.

  7. PTEN deletion from adult-generated dentate granule cells disrupts granule cell mossy fiber axon structure

    PubMed Central

    LaSarge, Candi L.; Santos, Victor R; Danzer, Steve C.

    2015-01-01

    Dysregulation of the mTOR-signaling pathway is implicated in the development of temporal lobe epilepsy. In mice, deletion of PTEN from hippocampal dentate granule cells leads to mTOR hyperactivation and promotes the rapid onset of spontaneous seizures. The mechanism by which these abnormal cells initiate epileptogenesis, however, is unclear. PTEN-knockout granule cells develop abnormally, exhibiting morphological features indicative of increased excitatory input. If these cells are directly responsible for seizure genesis, it follows that they should also possess increased output. To test this prediction, dentate granule cell axon morphology was quantified in control and PTEN-knockout mice. Unexpectedly, PTEN deletion increased giant mossy fiber bouton spacing along the axon length, suggesting reduced innervation of CA3. Increased width of the mossy fiber axon pathway in stratum lucidum, however, which likely reflects an unusual increase in mossy fiber axon collateralization in this region, offset the reduction in boutons per axon length. These morphological changes predicts a net increase in granule cell >> CA3 innervation. Increased diameter of axons from PTEN-knockout cells would further enhance granule cell >> CA3 communication. Altogether, these findings suggest that amplified information flow through the hippocampal circuit contributes to seizure occurrence in the PTEN-knockout mouse model of temporal lobe epilepsy. PMID:25600212

  8. Pten deletion in adult neural stem/progenitor cells enhances constitutive neurogenesis.

    PubMed

    Gregorian, Caroline; Nakashima, Jonathan; Le Belle, Janel; Ohab, John; Kim, Rachel; Liu, Annie; Smith, Kate Barzan; Groszer, Matthias; Garcia, A Denise; Sofroniew, Michael V; Carmichael, S Thomas; Kornblum, Harley I; Liu, Xin; Wu, Hong

    2009-02-11

    Here we show that conditional deletion of Pten in a subpopulation of adult neural stem cells in the subependymal zone (SEZ) leads to persistently enhanced neural stem cell self-renewal without sign of exhaustion. These Pten null SEZ-born neural stem cells and progenies can follow the endogenous migration, differentiation, and integration pathways and contribute to constitutive neurogenesis in the olfactory bulb. As a result, Pten deleted animals have increased olfactory bulb mass and enhanced olfactory function. Pten null cells in the olfactory bulb can establish normal connections with peripheral olfactory epithelium and help olfactory bulb recovery from acute damage. Following a focal stroke, Pten null progenitors give rise to greater numbers of neuroblasts that migrate to peri-infarct cortex. However, in contrast to the olfactory bulb, no significant long-term survival and integration can be observed, indicating that additional factors are necessary for long-term survival of newly born neurons after stroke. These data suggest that manipulating PTEN-controlled signaling pathways may be a useful step in facilitating endogenous neural stem/progenitor expansion for the treatment of disorders or lesions in regions associated with constitutive neurogenesis. PMID:19211894

  9. PTENα is a PTEN isoform Translated through Alternative Initiation and Regulates Mitochondrial Function

    PubMed Central

    Liang, Hui; He, Shiming; Yang, Jingyi; Jia, Xinying; Wang, Pan; Chen, Xi; Zhang, Zhong; Zou, Xiajuan; McNutt, Michael A.; Shen, Wen Hong; Yin, Yuxin

    2014-01-01

    Summary PTEN is one of the most frequently mutated genes in human cancer. It is known that PTEN has a wide range of biological functions beyond tumor suppression. Here we report that PTENα, an N-terminally extended form of PTEN, functions in metabolism. Translation of PTENα is initiated from a CUG codon upstream of and in-frame with the coding region of canonical PTEN. Eukaryotic translation initiation factor 2A (eIF2A) controls PTENα translation and a CUG-centered palindromic motif is required in this process. PTENα induces cytochrome c oxidase activity and ATP production in mitochondria. TALEN-mediated somatic deletion of PTENα impairs mitochondrial respiratory chain function. We show that PTENα interacts with canonical PTEN to increase PINK1 and promote energy production. These data provide insights into the mechanism by which the PTEN family is involved in multiple cellular processes. Our studies suggest that mammalian cells can use alternate translation initiation mechanisms to generate protein isoforms. PMID:24768297

  10. mTOR Signaling Feedback Modulates Mammary Epithelial Differentiation and Restrains Invasion Downstream of PTEN Loss

    PubMed Central

    Ghosh, Susmita; Varela, Lidenys; Sood, Akshay; Park, Ben Ho; Lotan, Tamara L.

    2013-01-01

    Oncogenic signaling pathways are tightly regulated by negative feedback circuits and relief of these circuits represents a common mechanism of tumor drug resistance. Although the significance of these feedback pathways for signal transduction is evident, their relevance for cellular differentiation and morphogenesis in a genetically-defined context is unclear. In this study, we used isogenic benign mammary organotypic cultures to interrogate the role of mTOR-mediated negative feedback in the specific setting of PTEN inactivation. We found that mTOR signaling promoted basal-like differentiation and repressed nuclear hormone receptor expression after short-term PTEN loss in murine cell cultures analyzed ex vivo. Unexpectedly, we found that PTEN inactivation inhibited growth factor-induced epithelial invasion, and that downstream mTOR-mediated signaling feedback was both necessary and sufficient for this effect. Mechanistically, using isogenic MCF10A cells with and without somaticPTEN deletion, we showed that mTOR inhibition promoted EGF-mediated epithelial invasion by de-repressing upstream EGFR, SRC and PI3K signaling. In addition to offering new signal transduction insights, these results bring to light a number of important and potentially clinically relevant cellular consequences of mTOR inhibition in the specific context of PTEN loss, including modulation of hormone and growth factor responsiveness and promotion of epithelial invasion. Our findings prompt future investigations of the possibility that mTOR inhibitor therapy may not only be ineffective but even deleterious in tumors with PTEN loss. PMID:23774212

  11. Dormant Intestinal Stem Cells are Regulated by PTEN and Nutritional Status

    PubMed Central

    Richmond, Camilla A.; Shah, Manasvi S.; Deary, Luke T.; Trotier, Danny C.; Thomas, Horatio; Ambruzs, Dana M.; Jiang, Lijie; Whiles, Bristol B.; Rickner, Hannah D.; Montgomery, Robert K.; Tovaglieri, Alessio; Carlone, Diana L.; Breault, David T.

    2015-01-01

    The cellular and molecular mechanisms underlying adaptive changes to physiological stress within the intestinal epithelium remain poorly understood. Here, we show that PTEN, a negative regulator of the PI3K→AKT→mTORC1 signaling pathway, is an important regulator of dormant intestinal stem cells (dISCs). Acute nutrient deprivation leads to transient PTEN phosphorylation within d-ISCs and a corresponding increase in their number. This release of PTEN inhibition renders d-ISCs functionally poised to contribute to the regenerative response during re-feeding via cell-autonomous activation of the PI3K→AKT→mTORC1 pathway. Consistent with its role in mediating cell survival, PTEN is required for d-ISC maintenance at baseline, and intestines lacking PTEN have diminished regenerative capacity following irradiation. Our results highlight a PTEN-dependent mechanism for d-ISC maintenance and further demonstrate the role of d-ISCs in the intestinal response to stress. PMID:26686631

  12. Pten deletion in adult neural stem/progenitor cells enhances constitutive neurogenesis.

    PubMed

    Gregorian, Caroline; Nakashima, Jonathan; Le Belle, Janel; Ohab, John; Kim, Rachel; Liu, Annie; Smith, Kate Barzan; Groszer, Matthias; Garcia, A Denise; Sofroniew, Michael V; Carmichael, S Thomas; Kornblum, Harley I; Liu, Xin; Wu, Hong

    2009-02-11

    Here we show that conditional deletion of Pten in a subpopulation of adult neural stem cells in the subependymal zone (SEZ) leads to persistently enhanced neural stem cell self-renewal without sign of exhaustion. These Pten null SEZ-born neural stem cells and progenies can follow the endogenous migration, differentiation, and integration pathways and contribute to constitutive neurogenesis in the olfactory bulb. As a result, Pten deleted animals have increased olfactory bulb mass and enhanced olfactory function. Pten null cells in the olfactory bulb can establish normal connections with peripheral olfactory epithelium and help olfactory bulb recovery from acute damage. Following a focal stroke, Pten null progenitors give rise to greater numbers of neuroblasts that migrate to peri-infarct cortex. However, in contrast to the olfactory bulb, no significant long-term survival and integration can be observed, indicating that additional factors are necessary for long-term survival of newly born neurons after stroke. These data suggest that manipulating PTEN-controlled signaling pathways may be a useful step in facilitating endogenous neural stem/progenitor expansion for the treatment of disorders or lesions in regions associated with constitutive neurogenesis.

  13. Novel germline mutations in the PTEN tumour suppressor gene found in women with multiple cancers

    PubMed Central

    De Vivo, I.; Gertig, D.; Nagase, S.; Hankinson, S.; O'Brien, R.; Speizer, F.; Parsons, R.; Hunter, D.

    2000-01-01

    Germline mutations in PTEN can predispose people to Cowden syndrome (CS) and Bannayan-Ruvalcaba-Riley (BRR) syndrome, rare, autosomal dominantly inherited neoplastic disorders. To determine whether germline mutations in PTEN contribute to genetic predisposition to multiple primary tumours within the general population, we conducted a nested case-control study, among 32 826 members of the prospective Nurses' Health Study cohort; cases were women with more than one primary tumour at different anatomical sites. We screened all nine exons of PTEN and flanking intronic splice sites for all 103 eligible cases using SSCP and sequencing. We observed two novel germline heterozygous missense mutations in exon 5 in five of the cases; three were V119L and two were V158L. Neither mutation was observed in 115 controls free of diagnosed cancer (p=0.02). Both mutants showed partial tumour suppressor activity when compared to wild type PTEN when transfected into a PTEN null breast cancer cell line. The phenotype was cell line specific suggesting that genetic background affects growth suppression activity of the mutants. These data provide evidence that germline mutations in