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Garg R, Benedetti LG, Abera MB, Wang H, Abba M, Kazanietz MG. Protein kinase C and cancer: what we know and what we do not. Oncogene 2014; 33:5225-37. [PMID: 24336328 DOI: 10.1038/onc.2013.524] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/20/2013] [Accepted: 10/20/2013] [Indexed: 02/08/2023]
Abstract
Since their discovery in the late 1970s, protein kinase C (PKC) isozymes represent one of the most extensively studied signaling kinases. PKCs signal through multiple pathways and control the expression of genes relevant for cell cycle progression, tumorigenesis and metastatic dissemination. Despite the vast amount of information concerning the mechanisms that control PKC activation and function in cellular models, the relevance of individual PKC isozymes in the progression of human cancer is still a matter of controversy. Although the expression of PKC isozymes is altered in multiple cancer types, the causal relationship between such changes and the initiation and progression of the disease remains poorly defined. Animal models developed in the last years helped to better understand the involvement of individual PKCs in various cancer types and in the context of specific oncogenic alterations. Unraveling the enormous complexity in the mechanisms by which PKC isozymes have an impact on tumorigenesis and metastasis is key for reassessing their potential as pharmacological targets for cancer treatment.
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Affiliation(s)
- R Garg
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - L G Benedetti
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M B Abera
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - H Wang
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M Abba
- Centro de Investigaciones Inmunológicas Básicas y Aplicadas (CINIBA), Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - M G Kazanietz
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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2
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Abstract
Protein kinase C (PKC) is a family of phospholipid-dependent serine/threonine kinases, which can be further classified into three PKC isozymes subfamilies: conventional or classic, novel or nonclassic, and atypical. PKC isozymes are known to be involved in cell proliferation, survival, invasion, migration, apoptosis, angiogenesis, and drug resistance. Because of their key roles in cell signaling, PKC isozymes also have the potential to be promising therapeutic targets for several diseases, such as cardiovascular diseases, immune and inflammatory diseases, neurological diseases, metabolic disorders, and multiple types of cancer. This review primarily focuses on the activation, mechanism, and function of PKC isozymes during cancer development and progression.
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3
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Hong IK, Jeoung DI, Ha KS, Kim YM, Lee H. Tetraspanin CD151 stimulates adhesion-dependent activation of Ras, Rac, and Cdc42 by facilitating molecular association between β1 integrins and small GTPases. J Biol Chem 2012; 287:32027-39. [PMID: 22843693 DOI: 10.1074/jbc.m111.314443] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Tetraspanin CD151 associates with laminin-binding α(3)β(1)/α(6)β(1) integrins in epithelial cells and regulates adhesion-dependent signaling events. We found here that CD151 plays a role in recruiting Ras, Rac1, and Cdc42, but not Rho, to the cell membrane region, leading to the formation of α(3)β(1)/α(6)β(1) integrin-CD151-GTPases complexes. Furthermore, cell adhesion to laminin enhanced CD151 association with β(1) integrin and, thereby, increased complex formation between the β(1) family of integrins and small GTPases, Ras, Rac1, and Cdc42. Adhesion receptor complex-associated small GTPases were activated by CD151-β(1) integrin complex-stimulating adhesion events, such as α(3)β(1)/α(6)β(1) integrin-activating cell-to-laminin adhesion and homophilic CD151 interaction-generating cell-to-cell adhesion. Additionally, FAK and Src appeared to participate in this adhesion-dependent activation of small GTPases. However, engagement of laminin-binding integrins in CD151-deficient cells or CD151-specific siRNA-transfected cells did not activate these GTPases to the level of cells expressing CD151. Small GTPases activated by engagement of CD151-β(1) integrin complexes contributed to CD151-induced cell motility and MMP-9 expression in human melanoma cells. Importantly, among the four tetraspanin proteins that associate with β(1) integrin, only CD151 exhibited the ability to facilitate complex formation between the β(1) family of integrins and small GTPases and stimulate β(1) integrin-dependent activation of small GTPases. These results suggest that CD151 links α(3)β(1)/α(6)β(1) integrins to Ras, Rac1, and Cdc42 by promoting the formation of multimolecular complexes in the membrane, which leads to the up-regulation of adhesion-dependent small GTPase activation.
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Affiliation(s)
- In-Kee Hong
- Medical and Bio-Material Research Center, School of Medicine, Kangwon National University, Chunchon, Kangwon-do 200-701, Korea
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Moshkov IE, Novikova GV, Mur LAJ, Smith AR, Hall MA. Ethylene rapidly up-regulates the activities of both monomeric GTP-binding proteins and protein kinase(s) in epicotyls of pea. PLANT PHYSIOLOGY 2003; 131:1718-26. [PMID: 12692330 PMCID: PMC166927 DOI: 10.1104/pp.102.015057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2002] [Revised: 11/12/2002] [Accepted: 12/20/2002] [Indexed: 05/23/2023]
Abstract
It is demonstrated that, in etiolated pea (Pisum sativum) epicotyls, ethylene affects the activation of both monomeric GTP-binding proteins (monomeric G-proteins) and protein kinases. For monomeric G-proteins, the effect may be a rapid (2 min) and bimodal up-regulation, a transiently unimodal activation, or a transient down-regulation. Pretreatment with 1-methylcyclopropene abolishes the response to ethylene overall. Immunoprecipitation studies indicate that some of the monomeric G-proteins affected may be of the Rab class. Protein kinase activity is rapidly up-regulated by ethylene, the effect is inhibited by 1-methylcyclopropene, and the activation is bimodal. Immunoprecipitation indicates that the kinase(s) are of the MAP kinase ERK1 group. It is proposed that the data support the hypothesis that a transduction chain exists that is separate and antagonistic to that currently revealed by studies on Arabidopsis mutants.
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Affiliation(s)
- Igor E Moshkov
- Timiryazev Institute of Plant Physiology RAS, Botanicheskaya 35, Moscow 127276, Russia
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5
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Yan Z, Kim GY, Deng X, Friedman E. Transforming growth factor beta 1 induces proliferation in colon carcinoma cells by Ras-dependent, smad-independent down-regulation of p21cip1. J Biol Chem 2002; 277:9870-9. [PMID: 11784716 DOI: 10.1074/jbc.m107646200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Transforming growth factor beta1 (TGFbeta1) can act as a tumor suppressor or a tumor promoter depending on the characteristics of the malignant cell. We recently demonstrated that colon carcinoma cells transfected with oncogenic cellular K-rasV12, but not oncogenic cellular H-rasV12, switched from TGFbeta1-insensitive to TGFbeta1-growth-stimulated and also became more invasive (Yan, Z., Deng, X., and Friedman, E. (2001) J. Biol. Chem. 276, 1555-1563). We now demonstrate that TGFbeta1 growth stimulation of colon carcinoma cells is Ras-dependent and smad-independent. In U9 colon carcinoma cells, which are responsive to TGFbeta1 by growth stimulation, a truncating mutation at Gln-311 was found in the smad4 gene. Very little smad4 protein was detected in these cells. Loss of smad4 protein was confirmed by functional studies. In U9 cells co-transfected wild-type smad4, but not mutant smad4, mediated response of the 3TP-lux and pSBE promoter reporter constructs to TGFbeta1. Proliferation initiated by TGFbeta1 in U9 cells required Ras-mediated down-regulation of p21cip1 protein. Less p21cip1 was associated with cdk2 small middle dotcyclin complexes in TGFbeta1-treated U9 cells, and the cdk2 complexes had increased kinase activity. Elevation of p21cip1 levels diminished proliferative response to TGFbeta1. U9 cells expressing DN-N17ras neither proliferated in response to TGFbeta1 nor down-regulated the cdk inhibitor p21cip1, and TGFbeta1 activation of 3TP-lux in U9 cells was inhibited by DN-N17ras in a dose-dependent manner. TGFbeta1 also decreased p21cip1 levels and stimulated proliferation in SW480 cells, which express mutant K-Ras but no smad4 protein. TGFbeta1 did not activate or inhibit the p21cip1 promoter construct in U9 cells even in the presence of co-transfected smad4, or alter p21cip1 mRNA levels. Thus the decrease in p21cip1 levels was mediated by a TGFbeta-initiated Ras-dependent, but smad-independent post-transcriptional mechanism.
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Affiliation(s)
- Zhongfa Yan
- Pathology Department, Upstate Medical University, State University of New York, Syracuse, New York 13210, USA
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6
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Abstract
In a previous study, we prepared short-chain fatty acid (SCFA) mixtures mimicking the composition of the digested fibers from wheat bran, oat bran, pectin, and cellulose and tested the products on U4 cells, a cell-line model for normal colonocytes. These SCFA mixes induced the cyclin-dependent kinase (cdk) inhibitors p21 and p27, which bound to cdk2/cyclin E and cdk4/cyclin D1 complexes, blocking their kinase activity and arresting cell growth. SCFAs from digested fiber may control intestinal crypt height in vivo by inducing apoptosis in growth-arrested cells at the top of the crypt. In the present study, we report that SCFA mixes induced apoptosis of U4 cells and unexpectedly caused both a sustained activation of the stress-activated protein kinase c-jun N-terminal kinase 1 (JNK1) and downregulation of the tumor suppressor protein p53. JNK1 bound to p53, and the amount of JNK1-bound p53 accurately reflected the amount of total cellular p53. After activation by SCFAs, JNK1 phosphorylated its bound p53. This phosphorylation is likely to have converted p53 into an apoptotic target because p53 breakdown correlated with caspase-3 activity, was inhibited by a caspase-3 inhibitor in a dose-dependent manner, and was inhibited by transfection of dominant-negative JNK1. Because JNK1 activation was sustained in SCFA-treated U4 cells, JNK1 can bind, phosphorylate, and release p53 for proteolysis and then continue this cycle until many p53 molecules have been phosphorylated. Loss of p53 protein was likely due to proteolysis and not to transcriptional changes because a sixfold decrease in p53 protein occurred within 3-24 h of SCFA treatment, whereas p53 mRNA levels were downregulated as much only after 2-3 d. SCFA mixes targeted p53 and possibly other cellular proteins for degradation during apoptosis by causing a sustained activation of JNKs.
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Affiliation(s)
- J Wang
- Department of Pathology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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Novikova GV, Moshkov IE, Smith AR, Hall MA. The effect of ethylene on MAPKinase-like activity in Arabidopsis thaliana. FEBS Lett 2000; 474:29-32. [PMID: 10828445 DOI: 10.1016/s0014-5793(00)01565-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protein kinase activity was studied in cytosolic extracts from leaves of wild type Arabidopsis thaliana, the ethylene-insensitive mutant, etr1, and the constitutive triple-response mutant, ctr1. Treatment of wild type with ethylene resulted in increased myelin basic protein (MBP) phosphorylation. In etr1, constitutive protein kinase activity was lower than in wild type, but in ctr1, activity was enhanced. A protein of M(r) approximately 47 kDa associated with MBP-phosphorylating activity was detected using in gel protein kinase assays and phosphorylation of this protein was promoted by ethylene treatment in wild type while activity in the mutants reflected that of MBP phosphorylation. Both MAPKinase (ERK 1) and phosphotyrosine antibodies immunoprecipitated MBP-phosphorylating activity and detected a polypeptide band at M(r) approximately 47 kDa. Immunoprecipitated MBP-phosphorylating activity was again much lower in etr1 compared to wild type but much higher in ctr1. Antibodies to phosphorylated MAPKinase recognised proteins at approximately 47 kDa and the signal was upregulated in response to ethylene. The data obtained suggest that the detected protein(s) is a MAPKinase and provide further evidence confirming that a MAPKinase cascade(s) is involved in ethylene signal transduction.
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Affiliation(s)
- G V Novikova
- Institute of Biological Sciences, University of Wales, SY23 3DA, Aberystwyth, UK
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Umar S, Sellin JH, Morris AP. Murine colonic mucosa hyperproliferation. II. PKC-beta activation and cPKC-mediated cellular CFTR overexpression. Am J Physiol Gastrointest Liver Physiol 2000; 278:G765-74. [PMID: 10801269 DOI: 10.1152/ajpgi.2000.278.5.g765] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In the companion article (Umar S, Scott J, Sellin JH, Dubinsky WP, and Morris AP, Am J Physiol Gastrointest Liver Physiol 278: 753-764, 2000), we have shown that transmissible murine colonic hyperplasia (TMCH) increased cellular cystic fibrosis transmembrane conductance regulator (CFTR) mRNA and protein expression, relocalized CFTR within colonocytes, and enhanced mucosal cAMP-dependent Cl(-) secretion. We show here that these changes were dependent on elevated cellular levels of membrane-bound Ca(2+)- and diacylglycerol-sensitive protein kinase C (PKC) activity (12-fold), induced by selective (3- to 4-fold) rises in conventional PKC (cPKC) isoform expression and membrane translocation. Three cPKC isoforms were detected in isolated crypts: alpha, beta1, and beta2. cPKC-beta1 rises preceded and those of cPKC-alpha and cPKC-beta2 paralleled cellular hyperproliferation and its effects on CFTR expression and cAMP-dependent Cl(-) current secretion. Only cPKC-beta1 and cPKC-beta2 were membrane translocated during TMCH. Furthermore, only cPKC-beta1 trafficked to the nucleus, whereas cPKC-beta2 remained partitioned among cytosolic, membrane, and cytoskeletal subcellular fractions. Modest increases in novel PKC-epsilon (nPKC-epsilon) expression and subcellular membrane partitioning were recorded during TMCH, but no changes were seen for PKC-delta or -eta. No nPKC isoform nuclear partitioning was detected. The orally bioactive cPKC inhibitor Ro-32-0432 reversed both TMCH and elevated cellular CFTR mRNA levels, whereas a pharmacologically inert analog (Ro-31-6045) failed to inhibit either response. On the basis of these facts, we present a new hypothesis whereby PKC-dependent cellular proliferation promotes endogenous cellular CFTR levels. PKC-beta1 was identified as a candidate regulatory PKC isoform.
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Affiliation(s)
- S Umar
- Department of Integrative Biology, Pharmacology, and Physiology, Division of Gastroenterology, Hepatology, and Nutrition, The University of Texas Health Science Center at Houston, Medical School, Houston 77030, USA
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Hochegger K, Partik G, Schörkhuber M, Marian B. Protein-kinase-C iso-enzymes support DNA synthesis and cell survival in colorectal-tumor cells. Int J Cancer 1999; 83:650-6. [PMID: 10521802 DOI: 10.1002/(sici)1097-0215(19991126)83:5<650::aid-ijc14>3.0.co;2-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein-kinase-C signalling has been blocked in colorectal tumor cells by kinase inhibitors, by TPA down-regulation or by exposure to anti-sense oligonucleotides. This resulted in growth inhibition in all cell lines used. The kinase inhibitors H7 and calphostin induced apoptosis, demonstrated by the appearance of cells with characteristically condensed chromatin and the induction of stand-breaks in the DNA. A cell-death-inducing concentration of 15 microgram/ml H7 down-regulated the bcl-2 levels after 9 hr, while bak levels were not affected. Gö6976,-an inhibitor of Ca(++)-dependent PKC iso-enzymes, was not active in growth inhibition or induction of apoptosis. Analysis of DNA synthesis in inhibitor-treated cultures indicated that H7 caused strong inhibition in all cell lines, while the more specific inhibitor calphostin was effective only in VACO235 adenoma cells. When down-regulation by TPA or anti-sense oligonucleotides was used to block PKC, effects on cell numbers were smaller and delayed. However, induction of apoptosis was significantly increased in SW480 carcinoma cells 4 days after exposure to anti-epsilon and anti-zeta oligonucleotides in SW480 and T84 carcinoma cells. Apoptosis was preceeded by loss of PKC protein and of bcl-2 from day 1 after addition of the oligonucleotides. In VACO235 adenoma cells, no induction of apoptosis could be observed when anti-epsilon and anti-zeta oligonucleotides were used. On the other hand, the adenoma cells were more responsive to anti-alpha and anti-beta oligonucleotides, which strongly inhibited DNA-synthesis 3 days after addition to the culture medium. Our results indicate that the Ca(++)-dependent PKCs alpha and beta are involved in proliferation signals, while the Ca(++)-independent PKCs epsilon and zeta are involved in survival pathways of colorectal tumor cells.
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Affiliation(s)
- K Hochegger
- Institute of Tumor Biology/Cancer Research, University of Vienna, Vienna, Austria
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10
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Banfi C, Mussoni L, Risé P, Cattaneo MG, Vicentini L, Battaini F, Galli C, Tremoli E. Very low density lipoprotein-mediated signal transduction and plasminogen activator inhibitor type 1 in cultured HepG2 cells. Circ Res 1999; 85:208-17. [PMID: 10417403 DOI: 10.1161/01.res.85.2.208] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In normal subjects and in patients with cardiovascular disease, plasma triglycerides are positively correlated with plasminogen activator inhibitor type 1 (PAI-1) levels. Moreover, in vitro studies indicate that VLDLs induce PAI-1 synthesis in cultured cells, ie, endothelial and HepG2 cells. However, the signaling pathways involved in the effect of VLDL on PAI-1 synthesis have not yet been investigated. We report that VLDLs induce a signaling cascade that leads to an enhanced secretion of PAI-1 by HepG2 cells. In myo-[(3)H]inositol-labeled HepG2 cells, VLDL (100 microg/mL) caused a time-dependent increase in [(3)H]inositol phosphates, the temporal sequence being tris>bis>monophosphate. VLDL brought about a time-dependent stimulation of membrane-associated protein kinase C (PKC) activity and arachidonate release. Finally, VLDL stimulated mitogen-activated protein (MAP) kinase, and this effect was reduced by 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7), which suggests that PKC plays a pivotal role in MAP kinase phosphorylation. VLDL-induced PAI-1 secretion was completely prevented by U73122, a specific inhibitor of phosphatidylinositol-specific phospholipase C, by H7 or by PKC downregulation, and by mepacrine (all P<0.01 versus VLDL-treated cells). 3,4,5-Trimethoxybenzoic acid 8-(diethylamino)-octyl ester, which prevents Ca2+ release from intracellular stores, inhibited VLDL-induced PAI-1 secretion by 60% (P<0.05), and the MAP kinase/extracellular signal-regulated kinase kinase (MEK) inhibitor PD98059 completely suppressed both basal and VLDL-induced PAI-1 secretion. These data demonstrate that VLDL-induced PAI-1 biosynthesis results from a principal signaling pathway involving PKC-mediated MAP kinase activation.
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Affiliation(s)
- C Banfi
- Institute of Pharmacological Sciences, University of Milan, Italy
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11
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Abstract
MAP kinases help to mediate diverse processes ranging from transcription of protooncogenes to programmed cell death. More than a dozen mammalian MAP kinase family members have been discovered and include, among others, the well studied ERKs and several stress-sensitive enzymes. MAP kinases lie within protein kinase cascades. Each cascade consists of no fewer than three enzymes that are activated in series. Cascades convey information to effectors, coordinates incoming information from other signaling pathways, amplify signals, and allow for a variety of response patterns. Subcellular localization of enzymes in the cascades is an important aspect of their mechanisms of action and contributes to cell-type and ligand-specific responses. Recent findings on these properties of MAP kinase cascades are the major focus of this review.
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Affiliation(s)
- M H Cobb
- Department of Pharmacology, U.T. Southwestern Medical Center, Dallas, TX 75235-9041, USA
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12
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Murray NR, Davidson LA, Chapkin RS, Clay Gustafson W, Schattenberg DG, Fields AP. Overexpression of protein kinase C betaII induces colonic hyperproliferation and increased sensitivity to colon carcinogenesis. J Cell Biol 1999; 145:699-711. [PMID: 10330400 PMCID: PMC2133187 DOI: 10.1083/jcb.145.4.699] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/1999] [Indexed: 12/27/2022] Open
Abstract
Protein kinase C betaII (PKC betaII) has been implicated in proliferation of the intestinal epithelium. To investigate PKC betaII function in vivo, we generated transgenic mice that overexpress PKC betaII in the intestinal epithelium. Transgenic PKC betaII mice exhibit hyperproliferation of the colonic epithelium and an increased susceptibility to azoxymethane-induced aberrant crypt foci, preneoplastic lesions in the colon. Furthermore, transgenic PKC betaII mice exhibit elevated colonic beta-catenin levels and decreased glycogen synthase kinase 3beta activity, indicating that PKC betaII stimulates the Wnt/adenomatous polyposis coli (APC)/beta-catenin proliferative signaling pathway in vivo. These data demonstrate a direct role for PKC betaII in colonic epithelial cell proliferation and colon carcinogenesis, possibly through activation of the APC/beta-catenin signaling pathway.
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Affiliation(s)
- N R Murray
- Sealy Center for Oncology and Hematology, University of Texas Medical Branch, Galveston, Texas 77555-1048, USA
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13
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Ahmed W, Kucich U, Abrams W, Bashir M, Rosenbloom J, Segade F, Mecham R, Rosenbloom J. Signaling pathway by which TGF-beta1 increases expression of latent TGF-beta binding protein-2 at the transcriptional level. Connect Tissue Res 1998; 37:263-76. [PMID: 9862226 DOI: 10.3109/03008209809002444] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The cytokine transforming growth factor-beta has multiple effects on a wide variety of cell types. These effects include modulation of growth and regulation of gene transcription. In the present work, we demonstrate that TGF-beta1 increases transcription of the latent transforming growth factor-beta binding protein-2 ( LTBP-2) gene in cultured human fetal lung fibroblasts leading to a significant increase in LTBP-2 mRNA steady state level. The stability of LTBP-2 mRNA was not appreciably altered. A corresponding increase in production of LTBP-2 protein accompanied the increase in mRNA. Through the use of specific inhibitors, we demonstrate that a member of the Ras super family and a protein kinase C, probably of the atypical (non-diacylglycerol, non-Ca++ dependent) class are likely to be components in the signaling pathway. However, phospholipases, G proteins and extracellular-signal regulated kinases do not appear to be involved. These results combined with previous findings on elastin regulation by TGF-beta1 (Kucich et al. (1997). Am. J. Respir. Cell Mol. Biol., 17: 10-16) demonstrate that TGF-beta1 can coordinately increase the steady state levels of mRNAs encoding components of the elastic fiber, but through diverse mechanisms. In contrast to LTBP-2, increased elastin expression is achieved by message stabilization. Furthermore, the TGF-beta1 signaling pathways differ and while the pathway leading to increased LTBP-2 transcription shares components with those modulating transcription of other genes, it is unlikely to be precisely congruent with any other previously described one.
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Affiliation(s)
- W Ahmed
- Department of Anatomy and Histology, University of Pennsylvania School of Dental Medicine, Philadelphia 19104, USA
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14
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Lim S, Lee HY, Lee H. Inhibition of colonization and cell-matrix adhesion after nm23-H1 transfection of human prostate carcinoma cells. Cancer Lett 1998; 133:143-9. [PMID: 10072163 DOI: 10.1016/s0304-3835(98)00219-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A human gene, nm23-H1, has been known as a metastasis suppressor in many tumor cells. The cellular mechanisms by which the nm23-H1 protein may directly or indirectly modulate the metastatic phenotype are not yet known. In this study the phenotypic effect of transfection of nm23-H1 cDNA into the human DU 145 prostate carcinoma cell line was examined. Despite similar growth rates, the nm23-H1-transfected lines displayed decreased colonization in soft agar and adhesion to extracellular matrix components when compared with the control transfected line. The results suggest that the nm23-H1 gene product suppresses the metastatic potential of prostate carcinoma cells by inhibiting their ability in anchorage-independent growth and extracellular matrix adhesion.
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Affiliation(s)
- S Lim
- Division of Life Sciences, Kangwon National University, Chunchon, South Korea
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15
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Schörkhuber M, Richter M, Dutter A, Sontag G, Marian B. Effect of anthraquinone-laxatives on the proliferation and urokinase secretion of normal, premalignant and malignant colonic epithelial cells. Eur J Cancer 1998; 34:1091-8. [PMID: 9849460 DOI: 10.1016/s0959-8049(98)00037-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Even though 1,8-dihydroxyanthraquinone (DHA)-laxatives have been implicated in colon carcinogenesis, the available information is still inconclusive. The aim of this study was to demonstrate the effect of the DHA-laxatives, danthrone, rhein, aloe-emodin and sennidine, on colorectal tumour cells. In SW480 carcinoma cultures, dose-dependent induction of urokinase secretion into the medium was the predominant effect. Simultaneously, cell numbers were decreased by DHA-aglycones, but not by sennoside or the biphenylic laxative bisacodyl. DNA synthesis was not similarly reduced: 0.4-4 microM danthrone and sennidine even stimulated 5-bromo-2'-desoxyuridine (BrdU) uptake into DNA. When uptake was normalised to cell number, danthrone and sennidine doubled BrdU uptake/10(6) cells, 18 microM rhein and 0.7 microM aloe-emodin induced increases of 37 and 50%, respectively. This may at least partially be due to selective resistance of S-phase cells to DHA-caused cell loss. In VACO235 adenoma cells, sennidine and aloe-emodin did not affect urokinase secretion, but stimulated growth. Both cell numbers and DNA synthesis were increased. In contrast to SW480 carcinoma cells, VACO235 cells were also sensitive to sennoside and bisacodyl. No effects of DHA were observed in normal colorectal epithelial cells. The biological effects were preceeded by specific phosphorylation of cellular proteins with molecular weights of 110, 78, 63, 57 kDa, indicating the specific induction of a cellular signalling cascade by the laxatives.
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Affiliation(s)
- M Schörkhuber
- Institute of Tumour Biology--Cancer Research, University of Vienna, Austria
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16
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Yan Z, Chen M, Perucho M, Friedman E. Oncogenic Ki-ras but not oncogenic Ha-ras blocks integrin beta1-chain maturation in colon epithelial cells. J Biol Chem 1997; 272:30928-36. [PMID: 9388239 DOI: 10.1074/jbc.272.49.30928] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Human colorectal tumors commonly contain mutations in Ki-ras but rarely, if ever, in Ha-ras. The selectivity for Ki-ras mutations in this tumor was explored using the HD6-4 colon epithelial cell line which contains no ras mutations. After adhesion to an extracellular matrix, HD6-4 cells polarize into columnar goblet cells with distinct apical and basal regions. Stable HD6-4 transfectants were made with mini-gene constructs of the oncogenic cellular Ki-ras4BG12V gene, the oncogenic Ha-rasG12V gene, or mini-gene constructs of wild-type Ki-ras4B as a control. Ki-ras mutations, but not Ha-ras mutations, disrupted colon epithelial cell apicobasal polarity and adhesion to collagen I and laminin. Three Ha-ras transfectants and three Ki-ras transfectants exhibited Ras proteins expressing the Val-12 mutation by Western blotting with pan-rasG12V antibody. Only wild-type Ki-ras transfectant cells and oncogenic Ha-ras transfectant cells synthesized the mature, fully glycosylated forms of beta1 integrin. Instead of the mature integrin beta1-chain, a faster migrating beta1-chain intermediate was detected on the cell surface and in the cytoplasm of the oncogenic Ki-ras transfectants. Expression of the oncogenic Ki-ras gene caused the altered beta1 integrin maturation because phosphorothiolated antisense oligonucleotides to Ki-ras reduced expression of both the mutant Ki-Ras protein and the aberrant integrin beta1-chain and increased expression of the mature integrin beta1-chain. Altered glycosylation generated the new beta1 integrin form since integrin core beta1-chain proteins of the same molecular weight were yielded in Ki-ras, Ha-ras, and control transfectants after removal of sugar residues with endoglycosidase F or following tunicamycin treatment to inhibit glycosylation. The selective effect of oncogenic Ki-ras on beta1 integrin glycosylation was not due to selective activation of mitogen-activated protein kinases because both mutated Ki- and Ha-ras genes activated this pathway and increased cell proliferation. Since blocking the glycosylation of integrin beta1-chain inhibited the adherence, polarization, and subsequent differentiation of colon epithelial cells, the selective effects of the oncogenic cellular Ki-ras gene on integrin beta1-chain glycosylation may account, at least in part, for the selection of Ki-ras mutations in human colon tumors.
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Affiliation(s)
- Z Yan
- State University of New York Health Science Center, Department of Pathology, Syracuse, New York 13210, USA
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17
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Deeg MA, Bowen RF, Oram JF, Bierman EL. High density lipoproteins stimulate mitogen-activated protein kinases in human skin fibroblasts. Arterioscler Thromb Vasc Biol 1997; 17:1667-74. [PMID: 9327761 DOI: 10.1161/01.atv.17.9.1667] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Protein kinase C (PKC) seems to play an important role in many of HDL effects on cells, including removal of excess cholesterol. HDL removes cholesterol by at least two mechanisms. One mechanism involves desorption/diffusion of cholesterol from the plasma membrane onto the acceptor particle, whereas the second is mediated by apolipoproteins and may involve intracellular translocation of cholesterol to the plasma membrane for subsequent efflux. In this report, we examined the possibility that mitogen-activated protein (MAP) kinase is one of the downstream events from HDL activation of PKC. Using a gel kinase assay with myelin basic protein incorporated into the gel, HDL (50 micrograms protein/mL) stimulated multiple kinases of 42, 50, 52, 58, and 60 kDa. The 42-kDa protein kinase, corresponding to the unresolved MAP kinases ERK1 and ERK2 based on immunoblotting, was activated over 2-fold by HDL. HDL activated all identified kinases in a concentration- and time-dependent manner, which became maximal within 5 to 10 minutes and remained activated for at least 60 minutes. HDL activation of MAP kinase seems to be partially mediated by PKC, because down-regulation of PKC and known PKC inhibitors inhibited the HDL effect by 40 to 50%. Free apolipoproteins A-I (10 micrograms/mL) and A-II (10 micrograms/mL) had no significant effect on MAP kinase activation. Moreover, modifying HDL with trypsin or tetranitromethane, which abolishes apolipoprotein-mediated cholesterol efflux, had no effect on HDL activation of MAP kinase. These results suggest that HDL activates MAP kinase via multiple signal transduction pathways that are likely involved in an HDL effect unrelated to apolipoprotein-mediated cholesterol translocation and efflux.
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Affiliation(s)
- M A Deeg
- Department of Medicine, University of Washington, Seattle 98195-6426, USA
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18
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Kucich U, Rosenbloom JC, Abrams WR, Bashir MM, Rosenbloom J. Stabilization of elastin mRNA by TGF-beta: initial characterization of signaling pathway. Am J Respir Cell Mol Biol 1997; 17:10-6. [PMID: 9224204 DOI: 10.1165/ajrcmb.17.1.2816] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The cytokine transforming growth factor-beta (TGF-beta) has multiple effects on a wide variety of cell types. These effects include modulation of growth and regulation of gene transcription. In a few instances, TGF-beta has also been shown to regulate gene expression posttranscriptionally by altering message stability, but the pathway by which this activity is executed remains largely unknown. In the present work, we demonstrate that TGF-beta 1 has no effect on transcription of the elastin gene in cultured human fetal lung fibroblasts, but does stabilize elastin messenger RNA (mRNA), leading to a dramatic increase in the steady-state level of elastin mRNA. A corresponding increase in production of tropoelastin accompanies the increase in elastin mRNA. Through the use of specific inhibitors, we demonstrate that phosphatidylcholine (PC)-specific phospholipase C (PLC) and protein kinase C (PKC) are involved in mediating the elastin message stabilization. In contrast, G proteins and extracellularly regulated kinases do not appear to be involved. These results suggest that although the TGF-beta signaling pathway leading to message stabilization shares components with that modulating transcription, the message-stabilization pathway also contains diverse other elements.
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Affiliation(s)
- U Kucich
- Department of Anatomy and Histology, University of Pennsylvania School of Dental Medicine, Philadelphia 19104, USA
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19
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Abe J, Kusuhara M, Ulevitch RJ, Berk BC, Lee JD. Big mitogen-activated protein kinase 1 (BMK1) is a redox-sensitive kinase. J Biol Chem 1996; 271:16586-90. [PMID: 8663194 DOI: 10.1074/jbc.271.28.16586] [Citation(s) in RCA: 323] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Mitogen-activated protein (MAP) kinases are a multigene family activated by many extracellular stimuli. There are three groups of MAP kinases based on their dual phosphorylation motifs, TEY, TPY, and TGY, which are termed extracellular signal-regulated protein kinases (ERK1/2), c-Jun N-terminal kinases, and p38, respectively. A new MAP kinase family member termed Big MAP kinase 1 (BMK1) or ERK5 was recently cloned. BMK1 has a TEY sequence similar to ERK1/2 but has unique COOH-terminal and loop-12 domains. To define BMK1 regulation, its activation in cultured rat vascular smooth muscle cells was characterized. Angiotensin II, phorbol ester, platelet-derived growth factor, and tumor necrosis factor-alpha were the strongest stimuli for ERK1/2 but were weak activators of BMK1. In contrast, H2O2 caused concentration-dependent activation of BMK1 but not ERK1/2. Sorbitol activated both BMK1 and ERK1/2. BMK1 activation by H2O2 was calcium-dependent and appeared ubiquitous as shown by stimulation in human skin fibroblasts, human vascular smooth muscle cells, and human umbilical vein endothelial cells. These findings demonstrate that activation of BMK1 is different from ERK1/2 and suggest an important role for BMK1 as a redox-sensitive kinase.
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Affiliation(s)
- J Abe
- Department of Medicine, Cardiology Division, University of Washington, Seattle, Washington 98195, USA
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20
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Abstract
In a prior study, we have shown that stable transfection of expression plasmids for protein kinases C beta 1 (PKC beta 1) or PKC beta 2 into differentiated colon cancer cells led to elevated levels of PKC beta 1 or PKC beta 2 protein and PKC beta kinase activities in the transfectants, without altering PKC alpha levels. PKC gamma is not found in these cells, so the major modulation was in PKC beta. PKC beta transfectant cells exhibited blocked differentiation, increased growth rate in athymic mice, and restoration of the basic fibroblast growth factor response pathway. In this study, we have extended the analysis of these PKC beta transfectants to the mitogen-activated protein kinase ERK3. Analysis of cell lysates on the mitogen-activated protein kinase substrate myelin basic protein by in gel kinase assay showed increased activity at 63 kDa, the size of ERK3, in each of two PKC beta 1 and each of two PKC beta 2 transfectants compared with the vector control transfectant. ERK3 was expressed at equal abundance in PKC beta 1, PKC beta 2, and control transfectant cells as demonstrated by Western blotting and by immunoprecipitation with anti-ERK3 monoclonal antibody. However, a > 10-fold increase in ERK3 activity in each PKC beta transfectant was shown by immunoprecipitation with anti-ERK3 monoclonal antibody followed by either immune complex kinase assay or by in gel kinase assay. Thus, while overexpression of transfected PKC beta does not lead to overexpression of ERK3, it does lead to constitutive activation of ERK3. A causal link between PKC beta overexpression and ERK3 activation was established because 12-O-tetradecanoylphorbol-13-acetate treatment down-regulated both PKC and ERK3 activities in both PKC beta 1 transfectants. ERK3 activity was found in nuclear and membrane fractions in each PKC beta transfectant, in contrast to controls, perhaps accounting for constitutive activation of ERK3 in cells with elevated levels of PKC beta 1 or PKC beta 2.
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Affiliation(s)
- S Sauma
- Laboratory of Gastrointestinal Tumor Biology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
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21
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English JM, Vanderbilt CA, Xu S, Marcus S, Cobb MH. Isolation of MEK5 and differential expression of alternatively spliced forms. J Biol Chem 1995; 270:28897-902. [PMID: 7499418 DOI: 10.1074/jbc.270.48.28897] [Citation(s) in RCA: 190] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The prototype mitogen-activated protein (MAP) kinase module is a three-kinase cascade consisting of the MAP kinase, extracellular signal-regulated protein kinase (ERK) 1 or ERK2, the MAP/ERK kinase (MEK) MEK1 or MEK2, and the MEK kinase, Raf-1 or B-Raf. This and other MAP kinase modules are thought to be critical signal transducers in major cellular events including proliferation, differentiation, and stress responses. To identify novel mammalian MAP kinase modules, polymerase chain reaction was used to isolate a new MEK family member, MEK5, from the rat. MEK5 is more closely related to MEK1 and MEK2 than to the other known mammalian MEKs, MKK3 and MKK4. MEK5 is thought to lie in an uncharacterized MAP kinase pathway, because MEK5 does not phosphorylate the ERK/MAP kinase family members ERK1, ERK2, ERK3, JNK/SAPK, or p38/HOG1, nor will Raf-1, c-Mos, or MEKK1 highly phosphorylate it. Alternative splicing results in a 50-kDa alpha and a 40-kDa beta isoform of MEK5. MEK5 beta is ubiquitously distributed and primarily cytosolic. MEK5 alpha is expressed most highly in liver and brain and is particulate. The 23 amino acids encoded by the 5' exon in the larger alpha isoform are similar to a sequence found in certain proteins believed to associate with the actin cytoskeleton; this alternatively spliced modular domain may lead to the differential subcellular localization of MEK5 alpha.
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Affiliation(s)
- J M English
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041, USA
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22
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Bhat NR, Zhang P, Hogan EL. Thrombin activates mitogen-activated protein kinase in primary astrocyte cultures. J Cell Physiol 1995; 165:417-24. [PMID: 7593220 DOI: 10.1002/jcp.1041650223] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Thrombin is known to evoke numerous inflammatory and proliferative responses in a wide variety of its target cells. Recent studies have demonstrated morphoregulatory and mitogenic effects of thrombin on astroglial cells (astrocytes). The present study deals with thrombin-induced activation of mitogen-activated protein (MAP) kinase in primary cultures of rat astrocytes. Treatment of serum-starved astrocytes with thrombin resulted in a rapid activation of tyrosine (Tyr) phosphorylation of a set of proteins including a prominent one with a molecular mass of 42 kDa (p42). The identity of p42 with MAP kinase was confirmed by MAP kinase-immunoreactivity of isolated [i.e., immunoprecipitated with anti-phosphotyrosine (PY) antibodies] p42 and by increased myelin basic protein (MBP) kinase activity present in MAP kinase immunoprecipitates of thrombin-treated cultures. Pertussis toxin (PTX) pretreatment failed to inhibit thrombin stimulation of p42 phosphorylation, indicating the lack of involvement of PTX sensitive G proteins in the mechanism of activation of MAP kinase by thrombin. Chronic exposure of cultures to phorbol 12-myristate 13-acetate to down-regulate PKC resulted in an attenuation of thrombin-induced p42 Tyr phosphorylation, although H-7, a known PKC inhibitor, failed to block thrombin effect. However, staurosporine, a nonspecific protein kinase inhibitor, prevented the activation of p42 phosphorylation. It is concluded that thrombin induces MAP kinase activation in astrocytes by a mechanism involving a staurosporine-sensitive pathway.
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Affiliation(s)
- N R Bhat
- Department of Neurology, Medical University of South Carolina, Charleston 29425, USA
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23
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Ramesh G, Levine AE. Pro-transforming growth factor-alpha processing in human colon carcinoma cells: role of protein kinase C. Int J Cancer 1995; 62:492-7. [PMID: 7635577 DOI: 10.1002/ijc.2910620422] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The human colon cancer cell lines HCT 116 (poorly differentiated) and GEO (well differentiated) express the mitogenic peptide transforming growth factor alpha (TGF-alpha). The secretion of TGF-alpha was enhanced by phorbol 12-myristate 13-acetate (PMA), indicating the possible role of protein kinase C (PKC) in the formation of mature TGF-alpha. Cells were metabolically labeled with 35S-cysteine and the formation of the mature 6 kDa TGF-alpha polypeptide from the 17 kDa pro-TGF-alpha precursor was determined. The conversion of pro-TGF-alpha was complete in 2-4 hr with the HCT 116 cells showing faster kinetics of TGF-alpha formation than GEO cells. HCT 116 cells secreted more TGF-alpha than GEO cells and the rate and extent of formation of TGF-alpha was enhanced by PMA in both cell lines. The expression of several PKC isozymes by HCT 116 and GEO cells was examined by immunoblotting. The expression of all isozymes examined was higher in HCT 116 cells compared with GEO cells. Calphostin C, an inhibitor of PKC, reduced the enzyme activity and significantly inhibited the PMA-induced secretion of TGF-alpha by both cell lines. Two agonists of PKC that act on specific PKC isozymes, thymeleatoxin and 12-deoxyphorbol 13-phenylacetate 20-acetate (dPPA), stimulated the release of TGF-alpha into the medium to the same extent as PMA. Since dPPA has been reported to stimulate PKC-beta 1 specifically, our results suggest a potential role for PKC-beta in the processing of pro-TGF-alpha by these 2 human colon carcinoma cell lines.
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Affiliation(s)
- G Ramesh
- Department of Basic Sciences, University of Texas-Houston 77225, USA
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24
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Affiliation(s)
- M H Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041, USA
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25
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Geppert TD, Whitehurst CE, Thompson P, Beutler B. Lipopolysaccharide Signals Activation of Tumor Necrosis Factor Biosynthesis Through the Ras/Raf-1/MEK/MAPK Pathway. Mol Med 1994. [DOI: 10.1007/bf03403535] [Citation(s) in RCA: 173] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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26
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Two different signal transduction pathways can be activated by transforming growth factor beta 1 in epithelial cells. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)36823-0] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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27
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Kariya K, Karns L, Simpson P. An enhancer core element mediates stimulation of the rat beta-myosin heavy chain promoter by an alpha 1-adrenergic agonist and activated beta-protein kinase C in hypertrophy of cardiac myocytes. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)41927-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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28
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Kahl-Rainer P, Marian B. Retinoids inhibit protein kinase C-dependent transduction of 1,2-diglyceride signals in human colonic tumor cells. Nutr Cancer 1994; 21:157-68. [PMID: 8058526 DOI: 10.1080/01635589409514313] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1,2-Diglycerides with long-chain fatty acid residues related to nutritional fat (LCDGs) specifically affect growth and urokinase secretion in human colonic tumor cells, but not in normal mucosa. This allows them to advance and enhance carcinogenesis in the colon and rectum. SW480 colon carcinoma cells are LCDG sensitive in the same way as primary colonic tumor cells and have therefore been used as a model system to study the mechanism of LCDG action and to search for inhibitors of tumor development in the colon. Using this model system, we have shown that the effects of LCDGs are transmitted by protein kinase C and abolished by downregulation of the enzyme. Retinol, retinoic acid, and beta-carotene in nanomolar concentrations inhibit LCDG-induced growth and urokinase secretion and block stimulation of protein kinase C. Although retinol and retinoic acid at higher concentrations also display stimulatory activity, beta-carotene does not. At 100 nM, a concentration that can easily be reached in the plasma of humans, beta-carotene reduces LCDG-induced urokinase secretion about 50%. Inasmuch as beta-carotene does not have side effects due to intrinsic activities and storage effects, beta-carotene and foods rich in carotenes could be useful in the prevention of colorectal cancer.
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Affiliation(s)
- P Kahl-Rainer
- Institute for Tumor Biology-Cancer Research, University of Vienna, Austria
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29
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Robbins DJ, Zhen E, Cheng M, Xu S, Ebert D, Cobb MH. MAP kinases ERK1 and ERK2: pleiotropic enzymes in a ubiquitous signaling network. Adv Cancer Res 1994; 63:93-116. [PMID: 8036991 DOI: 10.1016/s0065-230x(08)60399-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- D J Robbins
- University of Texas Southwestern Medical Center, Department of Pharmacology, Dallas 75235
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30
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Signal transduction through extracellular signal-regulated kinase-like pp57 blocked in differentiated colon carcinoma cells having low levels of c-src kinase. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53079-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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