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Powis G. Recent Advances in the Development of Anticancer Drugs that Act against Signalling Pathways. TUMORI JOURNAL 2018; 80:69-87. [PMID: 8016910 DOI: 10.1177/030089169408000201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cancer can be considered a disease of deranged intracellular signalling. The intracellular signalling pathways that mediate the effects of oncogenes on cell growth and transformation present attractive targets for the development of new classes of drugs for the prevention and treatment of cancer. This is a new approach to developing anticancer drugs and the potential, as well as some of the problems, inherent in the approach are discussed. Anticancer drugs that produce their effects by disrupting signalling pathways are already in clinical trial. Some properties of these drugs, as well as other inhibitors of signalling pathways under development as potential anticancer drugs, are reviewed.
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Affiliation(s)
- G Powis
- Arizona Cancer Center, University of Arizona Health Sciences Center, Tucson 85724
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2
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Podar K, Raab MS, Chauhan D, Anderson KC. The therapeutic role of targeting protein kinase C in solid and hematologic malignancies. Expert Opin Investig Drugs 2007; 16:1693-707. [PMID: 17922632 DOI: 10.1517/13543784.16.10.1693] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The protein kinase C (PKC) family, the most prominent target of tumor-promoting phorbol esters, is functionally linked to cell differentiation, growth, survival, migration and tumorigenesis and so mediates tumor cell proliferation, survival, multidrug resistance, invasion, metastasis and tumor angiogenesis. Therefore, targeting PKC isozymes may represent an attractive target for novel anticancer therapies. Recent preclinical and clinical studies using the macrocyclic bisindolylmaleimide enzastaurin or the N-benzylstaurosporine midostaurin demonstrate promising activity of PKC inhibitors in a variety of tumors, including diffuse large B-cell lymphoma, multiple myeloma and Waldenstroem's macroglobulinemia. However, our knowledge of PKCs in tumorigenesis is still only partial and each PKC isoform may contribute to tumorigenesis in a distinct way. Specifically, PKC isoforms have vastly different roles, which vary depending on expression levels of organ and tissue distribution, cell type, intracellular localization, protein-protein and lipid-protein interactions and the biologic environment. Although PKC activation generally positively affects tumor cell growth, motility, invasion and metastasis, recent reports show that many PKCs can also have negative effects. Therefore, it is necessary to further dissect the relative contribution of PKC isozymes in the development and progression of specific tumors in order to identify therapeutic opportunities, using either PKC inhibitors or PKC activators.
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Affiliation(s)
- Klaus Podar
- Dana-Farber Cancer Institute, Department of Medical Oncology, Jerome Lipper Multiple Myeloma Center, 44 Binney Street, Boston, MA 02115, USA.
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3
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Jensen HL. Herpes simplex virus type 1 morphogenesis and virus-cell interactions: significance of cytoskeleton and methodological aspects. APMIS 2006:7-55. [PMID: 16930175 DOI: 10.1111/j.1600-0463.2006.apm_v114_s119.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Abstract
Protein kinase C (PKC) is activated by diacylglycerol generated by receptor-mediated hydrolysis of membrane phospholipids to mediate signals for cell growth and plays as a target of tumor-promoting phorbol esters in malignant transformation. PKC is a family of enzymes and their expression profiles have been examined in the normal melanocytes and melanoma cells, and studies have been carried out on the functions of PKC isoforms in proliferation, transformation, and metastasis of melanoma cells. Here, we summarize current knowledge of the expression and possible roles of the PKC family in melanoma in comparison with those of normal melanocytes.
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Affiliation(s)
- Masahiro Oka
- Division of Dermatology, Department of Clinical Molecular Medicine, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan.
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5
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Soh JW, Weinstein IB. Roles of specific isoforms of protein kinase C in the transcriptional control of cyclin D1 and related genes. J Biol Chem 2003; 278:34709-16. [PMID: 12794082 DOI: 10.1074/jbc.m302016200] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Although protein kinase C (PKC) has been implicated in cell cycle progression, cell proliferation, and tumor promotion, the precise roles of specific isoforms in these processes is not clear. Therefore, we constructed and analyzed a series of expression vectors that encode hemagglutinin-tagged wild type (WT), constitutively active mutants (Delta NPS and CAT), and dominant negative mutants of PKCs alpha, beta 1, beta 2, gamma, delta, epsilon, eta, zeta, and iota. Cyclin D1 promoter reporter assays done in serum-starved NIH3T3 cells indicated that the constitutively active mutants of PKC-alpha and PKC-epsilon were the most potent activators of this reporter, whereas the constitutively active mutant of PKC-delta inhibited its activity. Transient transfection studies with a series of 5'-deleted cyclin D1 promoter constructs showed that the proximal 964-base region, which contains AP-1, SP1, and CRE enhancer elements, is required for activation of the cyclin D1 promoter by PKC-alpha. Deletion of the AP-1 enhancer element located at position -954 upstream from the initiation site abolished PKC-alpha-dependent activation of cyclin D1 expression. Deletion of the SP1 or CRE enhancer elements did not have any effect. A dominant negative mutant of c-Jun inhibited activation of the cyclin D1 promoter in a concentration-dependent manner, providing further evidence that AP-1 activity is required for activation of the cyclin D1 promoter by PKC-alpha and PKC-epsilon. The constitutively active mutants of PKC-alpha and PKC-epsilon also activated c-fos, c-jun, and cyclin E promoter activity. Furthermore, NIH3T3 cells that stably express the constitutively active mutants of PKC-alpha or PKC-epsilon displayed increased expression of endogenous cyclins D1 and E and faster growth rates. These results provide evidence that the activation of PKC-alpha or PKC-epsilon in mouse fibroblasts can play an important role in enhancing cell cycle progression and cell proliferation.
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Affiliation(s)
- Jae-Won Soh
- Department of Medicine and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York 10032, USA
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6
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Cruciani V, Husøy T, Mikalsen SO. Pharmacological evidence for system-dependent involvement of protein kinase C isoenzymes in phorbol ester-suppressed gap junctional communication. Exp Cell Res 2001; 268:150-61. [PMID: 11478841 DOI: 10.1006/excr.2001.5275] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several phorbol esters are potent activators of protein kinase C. They down-regulate gap junctional intercellular communication and induce phosphorylation of connexin43, but the sensitivity and extent of responses vary much between systems. We asked whether the total protein kinase C enzyme activity or the protein kinase C isoenzyme constitution was of importance for such variations. Some fibroblastic culture systems were compared. It was concluded that the total protein kinase C enzyme activity did not determine the sensitivity to phorbol esters. Furthermore, the use of isotype-specific inhibitors of protein kinase C indicated that protein kinase C alpha, delta, and epsilon may be involved to different extents in different fibroblastic systems in the response to phorbol esters.
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Affiliation(s)
- V Cruciani
- Department of Environmental and Occupational Cancer, Institute for Cancer Research, The Norwegian Radium Hospital, N-0310 Oslo, Norway
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7
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Abstract
PKC isoenzymes were found to be involved in proliferation, antitumor drug resistance and apoptosis. Therefore, it has been tried to exploit PKC as a target for antitumor treatment. PKC alpha activity was found to be elevated, for example, in breast cancers and malignant gliomas, whereas it seems to be underexpressed in many colon cancers. So it can be expected that inhibition of PKC activity will not show similar antitumor activity in all tumors. In some tumors it seems to be essential to inhibit PKC to reduce growth. However, for inhibition of tumor proliferation it may be an advantage to induce apoptosis. In this case an activation of PKC delta should be achieved. The situation is complicated by the facts that bryostatin leads to the activation of PKC and later to a downmodulation and that the PKC inhibitors available to date are not specific for one PKC isoenzyme. For these reasons, PKC modulation led to many contradicting results. Despite these problems, PKC modulators such as miltefosine, bryostatin, safingol, CGP41251 and UCN-01 are used in the clinic or are in clinical evaluation. The question is whether PKC is the major or the only target of these compounds, because they also interfere with other targets. PKC may also be involved in apoptosis. Oncogenes and growth factors can induce cell proliferation and cell survival, however, they can also induce apoptosis, depending on the cell type or conditions in which the cells or grown. PKC participates in these signalling pathways and cross-talks. Induction of apoptosis is also dependent on many additional factors, such as p53, bcl-2, mdm2, etc. Therefore, there are also many contradicting results on PKC modulation of apoptosis. Similar controversial data have been reported about MDR1-mediated multidrug resistance. At present it seems that PKC inhibition alone without direct interaction with PGP will not lead to successful reversal of PGP-mediated drug efflux. One possibility to improve chemotherapy would be to combine established antitumor drugs with modulators of PKC. However, here also very contrasting results were obtained. Many indicate that inhibition, others, that activation of PKC enhances the antiproliferative activity of anticancer drugs. The problem is that the exact functions of the different PKC isoenzymes are not clear at present. So further investigations into the role of PKC isoenzymes in the complex and interacting signalling pathways are essential. It is a major challenge in the future to reveal whether modulation of PKC can be used for the improvement of cancer therapy.
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Affiliation(s)
- J Hofmann
- Institute of Medical Chemistry and Biochemistry, University of Innsbruck, A-6020 Innsbruck, Austria
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8
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Abstract
Drug resistance, to date, has primarily been attributed to increased drug export or detoxification mechanisms. Despite correlations between drug export and drug resistance, it is increasingly apparent that such mechanisms cannot fully account for chemoresistance in neoplasia. It is now widely accepted that chemotherapeutic drugs kill tumour cells by inducing apoptosis, a genetically regulated cell death programme. Evidence is emerging that the exploitation of survival pathways, which may have contributed to disease development in the first instance, may also be important in the development of the chemoresistance. This review discusses the components of and associations between multiple signalling cascades and their possible contribution to the development of neoplasia and the chemoresistant phenotype.
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Affiliation(s)
- D M O'Gorman
- Department of Biochemistry, University College Cork, Ireland
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9
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Jensen HL, Norrild B. The effects of cell passages on the cell morphology and the outcome of herpes simplex virus type 1 infection. J Virol Methods 2000; 84:139-52. [PMID: 10680963 DOI: 10.1016/s0166-0934(99)00129-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Because cell cultures are essential in biological research which involves the analysis of virus morphogenesis, this study focused on examining the significance of cell passages. Human embryonic lung fibroblasts (MRC-5) at passage (P) 27 were seeded twice a week to P 32, P 40, and P 48, when just at confluence and then infected with herpes simplex virus type 1 (HSV-1). The structure of the non-virus-infected (MOCK) and HSV-1 infected cells, the amount of cellular infectious virus particles and the capability to express HSV-1 glycoproteins C (gC-1) and D (gD-1) were investigated by phase-contrast and immunofluorescence light microscopy, immunogold cryosection EM, plaque assays, immunoblots, and total protein assays. Modified cell structure including fragmentation of tubulin fibers were visible in MOCK from P 38 onwards. The quantity of vimentin remained unchanged while actin accumulated and beta-tubulin decreased in HSV-1 infected late P cells compared to early P cultures. Cells of high P counts contained significantly fewer infectious virus particles, very likely of lower virulence, and their expression of gC-1 and gD-1 were concordantly reduced. These observations indicate that the number of cell P must be considered in order to reproduce results of cell biology and viral morphogenesis. The MRC-5 cells ought not to be passaged more than ten times beyond P 27 in the laboratory.
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Affiliation(s)
- H L Jensen
- The Protein Laboratory, Institute of Molecular Pathology, University of Copenhagen, The Panum Institute, Denmark
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10
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Slosberg ED, Klein MG, Yao Y, Han EK, Schieren I, Weinstein IB. The alpha isoform of protein kinase C mediates phorbol ester-induced growth inhibition and p21cip1 induction in HC11 mammary epithelial cells. Oncogene 1999; 18:6658-66. [PMID: 10597271 DOI: 10.1038/sj.onc.1203083] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To clarify the roles of specific isoforms of PKC in regulating growth and cell cycle progression of the HC11 mammary epithelial cell line, we investigated the effects of activating endogenous PKC isoforms with the phorbol ester tumor promoter TPA, and also the effects of TPA on genetically engineered cells containing increased levels of individual PKC isoforms. We found that TPA treatment of HC11 cells induced a transient cell cycle arrest in G0/G1. Western blot analyses of the TPA treated cells provided evidence that the endogenous PKC alpha present in these cells mediated these effects. Indeed, derivatives of the HC11 cell line that inducibly overexpress an exogenous PKC alpha or ectopic PKC beta 1 exhibited more marked growth inhibition by TPA than control cells. Immunohistochemical staining of cells following treatment with TPA revealed selective translocation of PKC alpha into the nucleus, whereas PKC beta 1 remained in the cytoplasm. The transient arrest of HC11 cells following treatment with TPA was associated with marked induction of both p21cip1 mRNA and protein. This induction was exaggerated in the derivatives that overexpressed either PKC alpha or PKC beta 1. Therefore, in mouse mammary epithelial cells activation of the endogenous PKC alpha can transiently arrest cells in G0/G1 which may be due, at least in part, to induction of the transcription of p21cip1.
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Affiliation(s)
- E D Slosberg
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY 10032, USA
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11
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Soh JW, Lee EH, Prywes R, Weinstein IB. Novel roles of specific isoforms of protein kinase C in activation of the c-fos serum response element. Mol Cell Biol 1999; 19:1313-24. [PMID: 9891065 PMCID: PMC116060 DOI: 10.1128/mcb.19.2.1313] [Citation(s) in RCA: 217] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/1998] [Accepted: 11/03/1998] [Indexed: 02/07/2023] Open
Abstract
Protein kinase C (PKC) is a multigene family of enzymes consisting of at least 11 isoforms. It has been implicated in the induction of c-fos and other immediate response genes by various mitogens. The serum response element (SRE) in the c-fos promoter is necessary and sufficient for induction of transcription of c-fos by serum, growth factors, and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). It forms a complex with the ternary complex factor (TCF) and with a dimer of the serum response factor (SRF). TCF is the target of several signal transduction pathways and SRF is the target of the rhoA pathway. In this study we generated dominant-negative and constitutively active mutants of PKC-alpha, PKC-delta, PKC-epsilon, and PKC-zeta to determine the roles of individual isoforms of PKC in activation of the SRE. Transient-transfection assays with NIH 3T3 cells, using an SRE-driven luciferase reporter plasmid, indicated that PKC-alpha and PKC-epsilon, but not PKC-delta or PKC-zeta, mediate SRE activation. TPA-induced activation of the SRE was partially inhibited by dominant negative c-Raf, ERK1, or ERK2, and constitutively active mutants of PKC-alpha and PKC-epsilon activated the transactivation domain of Elk-1. TPA-induced activation of the SRE was also partially inhibited by a dominant-negative MEKK1. Furthermore, TPA treatment of serum-starved NIH 3T3 cells led to phosphorylation of SEK1, and constitutively active mutants of PKC-alpha and PKC-epsilon activated the transactivation domain of c-Jun, a major substrate of JNK. Constitutively active mutants of PKC-alpha and PKC-epsilon could also induce a mutant c-fos promoter which lacks the TCF binding site, and they also induce transactivation activity of the SRF. Furthermore, rhoA-mediated SRE activation was blocked by dominant negative mutants of PKC-alpha or PKC-epsilon. Taken together, these findings indicate that PKC-alpha and PKC-epsilon can enhance the activities of at least three signaling pathways that converge on the SRE: c-Raf-MEK1-ERK-TCF, MEKK1-SEK1-JNK-TCF, and rhoA-SRF. Thus, specific isoforms of PKC may play a role in integrating networks of signal transduction pathways that control gene expression.
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Affiliation(s)
- J W Soh
- Department of Biochemistry & Molecular Biophysics, College of Physicians & Surgeons, Columbia University, New York, New York 10032, USA
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12
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Cacace AM, Ueffing M, Han EK, Marmè D, Weinstein IB. Overexpression of PKCepsilon in R6 fibroblasts causes increased production of active TGFbeta. J Cell Physiol 1998; 175:314-22. [PMID: 9572476 DOI: 10.1002/(sici)1097-4652(199806)175:3<314::aid-jcp9>3.0.co;2-r] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In previous studies, our laboratory demonstrated that Rat 6 (R6) fibroblasts which stably overproduce high levels of PKCepsilon display abnormalities in growth control that are characteristic of malignant transformation (Cacace et al., 1993, Oncogene, 8:2095-2104). The R6-PKCepsilon overproducing cell lines also exhibited a decreased growth factor requirement. The present study demonstrates that conditioned medium (CM) from two individual clones, R6-PKCepsilon 10 and 30, stimulates DNA synthesis in control R6-C1 cells. Maximal DNA synthesis and morphologic transformation was achieved in control cells when they were treated with medium from R6-PKCepsilon cells grown in the presence of TPA (TPA-CM). Size fractionation of the TPA-CM from PKCepsilon 30 cells revealed that this activity is due to a factor(s) that has an apparent molecular weight in the range of 10-30 kD and is heat and acid stable. This factor, like TGFbeta1, stimulated anchorage-independent growth of NRK cells. Western blot analysis (under nonreducing conditions) of the TPA-CM from R6-PKCepsilon 30 and R6-PKCepsilon 10 cells revealed the presence of the 25 kD active forms of TGFbeta2 and 3. These active forms of TGFbeta were not found in the CM of control R6 cells, or R6 cells that overexpress PKCalpha or PKCbeta1. The addition of a pan-specific TGFbeta antibody to NRK cells treated with the 10-30 kD fraction of TPA-CM from PKCepsilon 30 cells blocked the ability of this material to stimulate thymidine incorporation. Taken together, these studies suggest that the oncogenic activity of PKCepsilon in R6 cells is due, at least in part, to its ability to induce production of the active forms of TGFbeta2 and 3.
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Affiliation(s)
- A M Cacace
- Department of Pharmacology and Herbert Irving Comprehensive Cancer Center, Columbia Presbyterian Medical Center, Columbia University, New York, New York 10032, USA
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13
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Cho Y, Tighe AP, Talmage DA. Retinoic acid induced growth arrest of human breast carcinoma cells requires protein kinase C alpha expression and activity. J Cell Physiol 1997; 172:306-13. [PMID: 9284950 DOI: 10.1002/(sici)1097-4652(199709)172:3<306::aid-jcp4>3.0.co;2-s] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Retinoic acid inhibits proliferation of hormone-dependent, but not hormone-independent breast cancer cells. Retinoic acid-induced changes in cellular proliferation and differentiation are associated with disturbances in growth factor signaling and frequently with changes in protein kinase C expression. PKC delta, epsilon, and zeta are expressed in both hormone-dependent (T-47D) and hormone-independent (MDA-MB-231) cell lines. Retinoic acid arrested T-47D proliferation, induced PKC alpha expression and concomitantly repressed PKC zeta expression. The changes in PKC alpha and PKC zeta reflect retinoic acid-induced changes in mRNA. In contrast, retinoic acid had no effect on growth, or PKC expression in MDA-MB-231 cells. Growth arrest and the induction of PKC alpha, but not the reduction in PKC zeta, resulted from selective activation of RAR alpha. In total, these results support an important role for PKC alpha in mediating the anti-proliferative action of retinoids on human breast carcinoma cells.
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MESH Headings
- Benzoates/pharmacology
- Blotting, Northern
- Blotting, Western
- Breast Neoplasms/enzymology
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Cell Division/drug effects
- Dose-Response Relationship, Drug
- Gene Expression Regulation, Enzymologic
- Humans
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Neoplasms, Hormone-Dependent/enzymology
- Neoplasms, Hormone-Dependent/genetics
- Neoplasms, Hormone-Dependent/pathology
- Protein Kinase C/genetics
- Protein Kinase C/metabolism
- Protein Kinase C-alpha
- Protein Kinase C-delta
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Retinoic Acid/metabolism
- Retinoic Acid Receptor alpha
- Retinoids/pharmacology
- Tetrahydronaphthalenes/pharmacology
- Tretinoin/pharmacology
- Tumor Cells, Cultured
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Affiliation(s)
- Y Cho
- Institute of Human Nutrition, Columbia University, New York, New York 10032, USA
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14
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Harrington EO, Löffler J, Nelson PR, Kent KC, Simons M, Ware JA. Enhancement of migration by protein kinase Calpha and inhibition of proliferation and cell cycle progression by protein kinase Cdelta in capillary endothelial cells. J Biol Chem 1997; 272:7390-7. [PMID: 9054439 DOI: 10.1074/jbc.272.11.7390] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Activation of protein kinase C (PKC) induces angiogenesis, migration, and proliferation of endothelial cells (EC), but can also prevent growth factor-induced EC proliferation. To determine whether these disparate effects are mediated by substrates of individual PKC isoenzymes, PKCalpha and PKCdelta were overexpressed in rat microvascular EC. Basal and stimulated migration were enhanced in PKCalpha EC compared with either PKCdelta or control EC. Serum-induced growth of PKCdelta EC was decreased, while that of PKCalpha cells was similar to control EC. Phorbol ester markedly inhibited PKCdelta EC growth but enhanced growth of PKCalpha and control EC. To determine possible causes for this altered proliferation, the effect of PKCdelta on adhesion, mitogen-activated protein kinase activity, and cell cycle progression was measured. Adherence of PKCdelta EC to vitronectin was significantly enhanced. Serum-induced extracellular signal-regulated kinase-2 activity was increased equally in both PKCalpha and PKCdelta EC above that of control, while extracellular signal-regulated kinase-1 activity was similar in all EC. Cell cycle analysis suggested that PKCdelta EC entered S phase inappropriately and were delayed in passage through S phase. Thus, PKCalpha may mediate some proangiogenic effects of PKC activation; conversely, PKCdelta may direct antiangiogenic aspects of overall PKC activation, including slowing of the cell cycle progression.
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Affiliation(s)
- E O Harrington
- Department of Medicine, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA
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15
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Ways DK, Kukoly CA, deVente J, Hooker JL, Bryant WO, Posekany KJ, Fletcher DJ, Cook PP, Parker PJ. MCF-7 breast cancer cells transfected with protein kinase C-alpha exhibit altered expression of other protein kinase C isoforms and display a more aggressive neoplastic phenotype. J Clin Invest 1995; 95:1906-15. [PMID: 7706498 PMCID: PMC295735 DOI: 10.1172/jci117872] [Citation(s) in RCA: 207] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Increased protein kinase C (PKC) activity in malignant breast tissue and positive correlations between PKC activity and expression of a more aggressive phenotype in breast cancer cell lines suggest a role for this signal transduction pathway in the pathogenesis and/or progression of breast cancer. To examine the role of PKC in the progression of breast cancer, human MCF-7 breast cancer cells were transfected with PKC-alpha, and a group of heterogenous cells stably overexpressing PKC-alpha were isolated (MCF-7-PKC-alpha). MCF-7-PKC-alpha cells expressed fivefold higher levels of PKC-alpha as compared to parental or vector-transfected MCF-7 cells. MCF-7-PKC-alpha cells also displayed a substantial increase in endogenous expression of PKC-beta and decreases in expression of the novel delta- and eta-PKC isoforms. MCF-7-PKC-alpha cells displayed an enhanced proliferative rate, anchorage-independent growth, dramatic morphologic alterations including loss of an epithelioid appearance, and increased tumorigenicity in nude mice. MCF-7-PKC-alpha cells exhibited a significant reduction in estrogen receptor expression and decreases in estrogen-dependent gene expression. These findings suggest that the PKC pathway may modulate progression of breast cancer to a more aggressive neoplastic process.
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Affiliation(s)
- D K Ways
- Department of Medicine, East Carolina University School of Medicine, Greenville, North Carolina 27858, USA
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16
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Kielbassa K, Müller HJ, Meyer HE, Marks F, Gschwendt M. Protein kinase C delta-specific phosphorylation of the elongation factor eEF-alpha and an eEF-1 alpha peptide at threonine 431. J Biol Chem 1995; 270:6156-62. [PMID: 7890750 DOI: 10.1074/jbc.270.11.6156] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Two cytosolic proteins of murine epidermis or porcine spleen with molecular masses of 37 kDa (p37) and 50 kDa (p50) are differentially phosphorylated in vitro by the purified protein kinase C (PKC) isoenzymes alpha, beta, gamma (cPKC) and PKC delta. p37, identified as annexin I, is preferentially phosphorylated by cPKC, whereas p50, identified as elongation factor eEF-1 alpha, is phosphorylated with much greater efficacy by PKC delta than by cPKC. Using the recombinant PKC isoenzymes alpha, beta, gamma, delta, epsilon, eta, and zeta, we could show that purified eEF-1 alpha is indeed a specific substrate of PKC delta. It is not significantly phosphorylated by PKC epsilon, -eta, and -zeta and only slightly by PKC alpha, -beta, and -gamma. PKC delta phosphorylates eEF-1 alpha at Thr-431 (based on the murine amino acid sequence). The peptide RFAVRDMRQTVAVGVIKAVDKK with a sequence corresponding to that of 422-443 from murine eEF-1 alpha and containing Thr-431 is an absolutely specific substrate for the delta-type of PKC. The single basic amino acid close to Thr-431 (Arg-429) is essential for recognition of the peptide as a substrate by PKC delta and for the selectivity of this recognition. Substitution of Arg-429 by alanine abolishes the ability of PKC delta to phosphorylate the peptide, and insertion of additional basic amino acids in the vicinity of Thr-431 causes a complete loss of selectivity.
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Abstract
It has recently become clear that cyclin-dependent kinase (cdk) complex regulates the cell cycle by phosphorylating Rb protein, a tumor suppressor protein. It is likely that this complex is a target of various growth factors and anti-growth factors (UV, TGF-beta etc.) in keratinocyte (KC). It has also been suggested that abnormalities in the cell cycle regulating mechanism such as increased activity of cyclin-cdk due to mutation of p53, a tumor suppressor gene, and overexpression of cyclin D may be concerned with carcinogenesis of KC. Thus, recent studies indicate that the cyclin-cdk complex is a common target of proliferation and carcinogenesis in KC.
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Affiliation(s)
- S Inohara
- Department of Dermatology, Hyogo College of Medicine, Nishinomiya, Japan
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18
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Borner C, Ueffing M, Jaken S, Parker PJ, Weinstein IB. Two closely related isoforms of protein kinase C produce reciprocal effects on the growth of rat fibroblasts. Possible molecular mechanisms. J Biol Chem 1995; 270:78-86. [PMID: 7814423 DOI: 10.1074/jbc.270.1.78] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We have previously reported that two closely related protein kinase C (PKC) isoforms, PKC alpha and PKC beta I, had divergent effects on the growth and transformation of the same parental R6 rat embryo fibroblast cell line (Housey, G. M., Johnson, M. D., Hsiao, W.-L. W. O'Brian, C. A., Murphey, J. P., Kirschmeier, P., and Weinstein, I. B. (1988) Cell 52, 343-354; Borner, C., Filipuzzi, I., Weinstein, I. B., and Imber, R. (1991) Nature 353, 78-80). Whereas cells that overexpress PKC beta I lost anchorage dependence, grew to higher saturation densities, and generated small tumors when injected into nude mice, none of these properties were seen with cells that overexpress PKC alpha. In fact, the latter cells grew even slower and to lower saturation densities as compared to control cells. Here we investigate possible molecular mechanisms underlying the reciprocal effects of PKC alpha and PKC beta I. Overexpression of both isoforms enhanced 12-O-tetradecanoyl phorbol-13 acetate-induced expression of the growth regulatory genes c-jun, c-myc, and collagenase and enhanced feedback inhibition of epidermal growth factor receptor binding and cellular levels of diacylglycerol. However, the cells overexpressing PKC beta I differed from those overexpressing PKC alpha by displaying a decreased requirement for growth factors and by the production of a mitogenic factor. Thus, the basis for enhanced growth and transformation of cells overexpressing PKC beta I may be the establishment of an autocrine growth factor loop. These findings may be relevant to the roles of specific isoforms of PKC in carcinogenesis and tumor growth.
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Affiliation(s)
- C Borner
- Columbia-Presbyterian Center, Columbia University, New York, New York 10032
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19
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Affiliation(s)
- P A Philip
- Division of Hematology and Oncology, Harper Hospital, Detroit, MI 48201, USA
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20
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Abstract
Protein kinase C (PKC) is a family of closely related lipid-dependent and diacyglycerol-activated isoenzymes known to play an important role in the signal transduction pathways involved in hormone release, mitogenesis and tumor promotion. Reversible activation of PKC by the second messengers diacylglycerol and calcium is an established model for the short term regulation of PKC in the immediate events of signal transduction. PKC can also be modulated long term by changes in the levels of activators or inhibitors for a prolonged period or by changes in the levels of functional PKC isoenzymes in the cell during development or in response to hormones and/or differentiation factors. Indeed, studies have indicated that the sustained activation or inhibition of PKC activity in vivo may play a critical role in regulation of long term cellular events such as proliferation, differentiation and tumorigenesis. In addition, these regulatory events are important in colon cancer, where a decrease in PKC activators and activity suggests PKC acts as an anti-oncogene, in breast cancer, where an increase in PKC activity suggests an oncogenic role for PKC, and in multidrug resistance (MDR) and metastasis where an increase in PKC activity correlates with increased resistance and metastatic potential. These studies highlight the importance and significance of regulation of PKC activity in vivo.
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Affiliation(s)
- G C Blobe
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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21
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Ali S, Becker MW, Davis MG, Dorn GW. Dissociation of vasoconstrictor-stimulated basic fibroblast growth factor expression from hypertrophic growth in cultured vascular smooth muscle cells. Relevant roles of protein kinase C. Circ Res 1994; 75:836-43. [PMID: 7923629 DOI: 10.1161/01.res.75.5.836] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Thromboxane A2 (TXA2) and angiotensin II (Ang II) stimulate vascular smooth muscle hypertrophy by upregulating endogenous synthesis of basic fibroblast growth factor (bFGF). Because mitogenic phorbol esters can also stimulate bFGF formation, we investigated the role of protein kinase C (PKC) in vascular smooth muscle cell (VSMC) bFGF formation and hypertrophy. Preliminary characterization of PKC isoform expression in VSMC by use of polymerase chain reaction identified PKC alpha, delta, epsilon, and zeta. Western analysis confirmed the presence of these isoforms in cultured VSMC lines and demonstrated downregulation of PKC alpha, delta, and epsilon by phorbol 12-myristate 13-acetate (PMA) but not TXA2 or Ang II. PKC activation with 100 nmol/L PMA stimulated VSMC mitogenesis measured as incorporation of [3H]leucine and [3H]thymidine and increased cell number. Like TXA2 and Ang II, PMA increased endogenous VSMC bFGF in a time-dependent manner, whereas an inactive phorbol ester had no such effect. Addition of an antisense oligodeoxynucleotide against bFGF prevented PMA-stimulated bFGF expression and inhibited PMA-stimulated growth, suggesting that bFGF synthesis is necessary for VSMC growth stimulated by PMA. To clarify the role of PKC in vasoconstrictor-stimulated VSMC production of bFGF and hypertrophy, PKC was down-regulated by prolonged exposure to PMA or was inhibited with calphostin C or staurosporine before the addition of TXA2 or Ang II. PKC inhibition prevented TXA2-stimulated and Ang II--stimulated VSMC hypertrophy without attenuating the observed increase in bFGF expression. Furthermore, PKC inhibition with calphostin C inhibited VSMC mitogenesis stimulated by exogenous bFGF.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Ali
- Department of Internal Medicine, University of Cincinnati, OH 45267-0542
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22
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Xiao H, Goldthwait DA, Mapstone T. The identification of four protein kinase C isoforms in human glioblastoma cell lines: PKC alpha, gamma, epsilon, and zeta. J Neurosurg 1994; 81:734-40. [PMID: 7931620 DOI: 10.3171/jns.1994.81.5.0734] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Levels of protein kinase C (PKC) isoforms in eight human glioblastoma cell lines and two normal human glial cell cultures were determined. Earlier studies identified PKC-alpha and PKC-gamma in these cell lines but PKC-beta was not present. In this study, PKC-epsilon and PKC-zeta are demonstrated immunologically in these cell lines and also in two normal human glial cell cultures. Protein kinase C-delta was not present. When levels of the four isoforms in the tumor cells were compared to levels in the normal cells, no increase was observed in PKC-alpha or PKC-gamma, but PKC-epsilon was elevated three to 30 times in six of the eight tumors, and PKC-zeta was elevated approximately two times in all of the tumors. Incubation of cell line A172 with phorbol ester for 6 hours resulted in a 48-fold maximum increase in the nuclear PKC-epsilon and a sevenfold increase in the plasma membrane fraction with no change in the cytoplasmic fraction. A similar incubation for 4 hours produced a 0.5- to onefold increase of PKC-zeta in cytoplasmic, nuclear, and plasma membrane fractions. Other researchers have shown that overexpression of PKC-epsilon in fibroblasts results in tumorigenesis, and that blocking PKC-zeta function inhibits deoxyribonucleic acid synthesis. These data suggest that alteration in the expression of PKC-epsilon and PKC-zeta could be a factor in the conversion of normal glial cells to glioblastomas.
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Affiliation(s)
- H Xiao
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio
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23
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Affiliation(s)
- H Haller
- Franz Volhard Clinic, Max Delbrück Center for Molecular Medicine, Rudolf Virchow University Hospitals, Free University of Berlin, Germany
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24
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Lévy L, Alvaro V, Dubray C, Joubert D. Ca(2+)-dependent protein kinase C isoforms in rat pituitary hyperplasia: effect of in vivo treatment with quinagolide. Eur J Pharmacol 1994; 268:327-34. [PMID: 7528679 DOI: 10.1016/0922-4106(94)90057-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Ca(2+)-dependent protein kinase C (PKC) activity, diacylglycerol levels and PKC alpha, beta I, beta II and gamma expression were analyzed in the pituitary of female rats treated with estradiol alone (2 months) or in combination with quinagolide in the second month. Polymerase chain reaction (PCR) and Western blot analysis revealed the presence of PKC alpha, beta I and beta II isoenzymes in the rat pituitary gland but not of PKC gamma isoenzymes. Increases in pituitary weight and plasma prolactin levels induced by estradiol were associated with an increase in diacylglycerol pituitary content (1.55 +/- 0.06 versus 1.12 +/- 0.17 nmol diacylglycerol/mg protein in controls, P < 0.01). Cotreatment with quinagolide reversed these effects. Changes in PKC activity were accompanied by parallel changes in PKC alpha and beta I expressions. Estradiol treatment increased the expression of these isoforms whereas cotreatment with quinagolide antagonized these effects. PKC beta II expression was not affected. In conclusion, Ca(2+)-dependent PKC activity and protein expression are increased in hyperplastic pituitary cells, suggesting the involvement of this class of PKCs in the rat pituitary cell proliferation and/or hormonal secretion. This is further assessed by the fact that the dopamine receptor agonist treatment decreases activity and expression of these PKCs in parallel with the decrease in hormonal secretion and cell proliferation.
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Affiliation(s)
- L Lévy
- Centre CNRS-INSERM de Pharmacologie-Endocrinologie, Montpellier, France
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25
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Gschwendt M, Kielbassa K, Kittstein W, Marks F. Tyrosine phosphorylation and stimulation of protein kinase C delta from porcine spleen by src in vitro. Dependence on the activated state of protein kinase C delta. FEBS Lett 1994; 347:85-9. [PMID: 7516899 DOI: 10.1016/0014-5793(94)00514-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Native protein kinase C delta from porcine spleen is phosphorylated in vitro by the tyrosine kinase src and to a much smaller extent by fyn. The tyrosine phosphorylation of PKC delta is restricted to the activated state of the enzyme, i.e. it occurs only in the presence of an activator, such as TPA or bryostatin. Upon phosphorylation at tyrosine, the apparent molecular weight of PKC delta increases by 6 kDa. Phosphorylation by src induces a stimulation of PKC delta activity apparently exhibiting some substrate selectivity. Other PKC isoenzymes, such as cPKC (alpha, beta, gamma), are not phosphorylated by src or only to a very small extent. This phosphorylation is not dependent on TPA and does not cause an increase in activity and molecular weight of the enzyme.
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26
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Cuadrado A, Issing W, Fleming TP, Molloy CJ. Uneven distribution of protein kinase C-alpha and -beta isozymes in human sarcomas and carcinomas. J Cell Physiol 1994; 159:434-40. [PMID: 8188761 DOI: 10.1002/jcp.1041590307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Protein kinase C (PKC) represents a family of structurally related Ser/Tre kinases which are involved in mitogenic signalling and may contribute to human neoplasia. To address this issue, the messenger RNA and protein levels of PKC isoenzymes alpha and beta were analyzed in several human sarcoma- and carcinoma-derived cell lines. Carcinomas contained low or undetectable levels of either PKC-alpha or PKC-beta. Sarcomas exhibited similar or increased PKC expression compared to human diploid fibroblasts. Moreover, sarcoma cell lines expressing one PKC isoform did not contain detectable levels of the other. When PKC was depleted from the tumor cells, we observed that the PKC overexpressing sarcomas had reduced their malignant properties as determined by their ability to grow in semisolid medium. In addition, epidermal growth factor-stimulated and erbB2-transformed fibroblasts exhibited enhanced cell growth in the absence of PKC. We propose a model for the effect of PKC as a negative regulator of proliferation in epithelial cells and a growth promoter in fibroblasts.
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Affiliation(s)
- A Cuadrado
- Department of Cell Biology and Genetics, University of Alcalá de Henares, Madrid, Spain
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27
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Fitzer-Attas C, Eldar H, Eisenbach L, Livneh E. The expression of PDGF-alpha but not PDGF-beta receptors is suppressed in Swiss/3T3 fibroblasts over-expressing protein kinase C-alpha. FEBS Lett 1994; 342:165-70. [PMID: 8143871 DOI: 10.1016/0014-5793(94)80493-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The generation and characterization of Swiss/3T3 cells which stably over-express protein kinase C (PKC)-alpha were previously described by us. In these cells over-expression of PKC-alpha reduced the expression of epidermal growth factor (EGF) receptor molecules [(1990) J. Biol. Chem. 265, 13290-13296]. Here we show that the expression of PDGF-alpha receptors, but not PDGF-beta receptors, was specifically decreased in these cells. Not only were the levels of PDGF-alpha receptor mRNA transcript and protein significantly diminished in the PKC-alpha over-producing cells, but their ability to respond to short- and long-term growth factor signals was appropriately compromised. This was reflected in a reduced tyrosine autophosphorylation signal in response to PDGF-AA, as well as in decreased growth rates of PKC-alpha over-expressing cells when supplied with external PDGF-AA. A similar decrease in PDGF-alpha receptors was also demonstrated in parental Swiss/3T3 cells treated with phorbol esters. Our studies imply that PKC-alpha is involved in a cellular mechanism suppressing the expression of PDGF-alpha receptors in Swiss/3T3 cells. Hence, activation of PKC-alpha or alterations in its cellular levels may affect, in turn, the expression of a specific set of cell surface receptors and their responses to external growth factors.
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Affiliation(s)
- C Fitzer-Attas
- Department of Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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28
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Abstract
Intracellular signalling pathways mediating the effects of oncogenes on cell growth and transformation offer novel targets for the development of anticancer drugs. With this approach, it may be sufficient to target a component of the signalling pathway activated by the oncogene rather than the oncogene product itself. In this review, the abilities of some antiproliferative drugs to inhibit signalling targets are considered. There are some anticancer drugs already in clinical trial that may act by inhibiting signalling targets, as well as drugs in preclinical development. Some problems that may be encountered in developing this new class of anticancer drugs are discussed.
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Affiliation(s)
- G Powis
- Arizona Cancer Center, University of Arizona Health Sciences Center, Tucson 85724
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29
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Goodnight J, Mischak H, Mushinski JF. Selective involvement of protein kinase C isozymes in differentiation and neoplastic transformation. Adv Cancer Res 1994; 64:159-209. [PMID: 7879658 DOI: 10.1016/s0065-230x(08)60838-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- J Goodnight
- Laboratory of Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
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30
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Li W, Mischak H, Yu J, Wang L, Mushinski J, Heidaran M, Pierce J. Tyrosine phosphorylation of protein kinase C-delta in response to its activation. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)41948-x] [Citation(s) in RCA: 136] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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31
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Kochs G, Hummel R, Meyer D, Hug H, Marmé D, Sarre TF. Activation and substrate specificity of the human protein kinase C alpha and zeta isoenzymes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 216:597-606. [PMID: 8375396 DOI: 10.1111/j.1432-1033.1993.tb18179.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Protein kinase C (PKC), a class of serine/threonine kinases activated by Ca2+ and/or phospholipids, is involved in a variety of cellular processes such as proliferation, differentiation and secretion. Nine members of the PKC gene family are known; these are differentially expressed in eukaryotic cells and can be divided into two sub-groups: the Ca(2+)-dependent (classical) PKC isoenzymes alpha, beta I, beta II and gamma, and the Ca(2+)-independent neoPKC isoenzymes delta, epsilon, zeta, eta and theta. A detailed biochemical characterisation of these PKC isoenzymes is one prerequisite for the elucidation of their distinct roles within cellular signal transduction. In this study, we report the cloning of a human PKC-zeta cDNA, its expression in recombinant baculovirus-infected insect cells and the partial purification of the PKC-zeta isoenzyme. In comparison to highly purified human PKC alpha, a representative of the classical PKC subgroup, purified PKC zeta was characterised with respect to activator requirement, substrate specificity, proteolytic activation and sensitivity towards PKC inhibitors. In contrast to PKC alpha, PKC zeta exhibits a constitutive kinase activity which is independent of Ca2+, phosphatidylserine and diacylglycerol. Arachidonic acid alone or a combination of gamma-linolenic acid and phosphatidylserine slightly enhance PKC zeta activity. In the presence of the classical PKC activators phosphatidylserine/diacylglycerol, PKC alpha phosphorylates a PKC-alpha pseudosubstrate-derived peptide, an epidermal-growth-factor-receptor-derived peptide, histone III-S and myelin basic protein to an equal extent, whilst PKC zeta phosphorylates only the PKC-alpha-derived peptide. However, arachidonic acid greatly diminishes PKC-alpha activity towards the epidermal-growth-factor-receptor-derived peptide, histone III-S and myelin basic protein, but enhances PKC-zeta activity towards the PKC-alpha-derived peptide. These results indicate a possible modulation of substrate specificity of these two PKC isoenzymes by (the binding of) different activators (to their regulatory domains). In the case of PKC zeta, this finding is strengthened by the fact that the epidermal growth factor receptor-derived peptide, which is not a substrate for the holoenzyme, is significantly phosphorylated by a protein fragment generated by limited proteolysis and comprising only the kinase domain. Furthermore, PKC zeta, in contrast to PKC alpha, is insensitive to PKC inhibitors known to interfere either with the regulatory or the catalytic domain and cannot be activated by phorbol ester treatment of NIH 3T3 cells or insect cells, overexpressing the respective PKC isoenzyme. The potential implications of these findings on the mechanism(s) of activation and the substrate specificity of PKC zeta are discussed.
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Affiliation(s)
- G Kochs
- University of Freiburg, Institute of Molecular Cell Biology, Germany
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32
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Abstract
Many investigators have embarked upon the search for novel cellular targets for the treatment of cancer. A popular therapeutic strategy is to intervene with the components of cellular signalling systems that are altered during malignancy. The molecular heterogeneity of the protein kinase C (PKC) family and their functional divergence make them attractive targets for anticancer drug development. PKC can also influence the sensitivity of tumor tissue to conventional cytotoxic drugs. As discussed in this review, a complete understanding of the PKC signal transduction pathway is obligatory for the selective destruction of tumor tissue by exploiting PKC as either a target or a modulator of cancer chemotherapeutic agents.
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Affiliation(s)
- A Basu
- Department of Pharmacology, University of Pittsburgh School of Medicine, PA 15261
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33
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Protein kinase C isotypes in human erythroleukemia (K562) cell proliferation and differentiation. Evidence that beta II protein kinase C is required for proliferation. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)82331-6] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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34
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Filipuzzi I, Fabbro D, Imber R. Unphosphorylated alpha-PKC exhibits phorbol ester binding but lacks protein kinase activity in vitro. J Cell Biochem 1993; 52:78-83. [PMID: 8320277 DOI: 10.1002/jcb.240520111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Expression of the alpha-isoform of protein kinase C (alpha-PKC) in E. coli yielded the unphosphorylated 74 kD precursor molecule. This precursor form exhibited phospholipid- and calcium-dependent phorbol ester binding but lacked, in contrast to the phosphorylated enzyme, protein kinase activity. In addition, the precursor molecule was found to interact with both threonine and an ATP analogon, which demonstrates that phosphorylation of alpha-PKC is not required for binding of substrates, cofactors, or activators. These results, therefore, suggest that posttranslational phosphorylation of alpha-PKC is not needed for the formation of a functional enzyme-substrate complex but is necessary for the catalytic transfer of phosphate residues from ATP to protein substrates.
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Affiliation(s)
- I Filipuzzi
- Department of Gynecology and Obstetrics, University Hospital Basel, Switzerland
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35
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Kochs G, Hummel R, Fiebich B, Sarre TF, Marmé D, Hug H. Activation of purified human protein kinase C alpha and beta I isoenzymes in vitro by Ca2+, phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate. Biochem J 1993; 291 ( Pt 2):627-33. [PMID: 8387275 PMCID: PMC1132570 DOI: 10.1042/bj2910627] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The increasing number of eukaryotic protein kinase C (PKC) isoenzymes which have been described has raised great interest in potential differences in the cellular expression, the mode of activation and the substrate specificity of these isoenzymes. The last two aspects have mostly been studied with isoenzymes purified from rat or bovine brain or from recombinant-baculovirus-infected insect cells. In this study, we have expressed the human PKC isoenzymes alpha and beta I in recombinant-baculovirus-infected insect cells. The isoenzymes were purified to homogeneity by a four-step procedure which included a reversible Ca(2+)-dependent association/dissociation to and from the endogenous membranes of the lysed insect cells. Characterization of the purified enzymes with respect to ATP requirement and substrate specificity, using the epidermal-growth-factor receptor peptide and histone III-S respectively, revealed no isoenzyme-specific differences. Activation by trypsin or Ca2+ and a variety of different phospholipids and phosphoinositides (in a mixed-micellar assay) gave the following results. Proteolytic cleavage of the PKC isoenzymes by trypsin generated fully activated phospholipid-independent PKC beta I, whereas PKC alpha reached only 50% of the activity obtained in the presence of phospholipids. PKC alpha and beta I showed no difference in their dependence on Ca2+, diacylglycerol (DAG) and phosphatidylserine (PS). Replacement of either DAG or PS by phosphatidylglycerol, cardiolipin, phosphatidylcholine and several phosphoinositides revealed that PtdIns(4,5)P2 can act as a PKC activator similar to DAG, whereas PtdIns can substitute for PS as a cofactor of activation. Thus, at least for the PKC isoenzymes alpha and beta I, a combination of PtdIns and PtdIns(4,5)P2 can fully replace PS and DAG in vitro as the classical activators of PKC.
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Affiliation(s)
- G Kochs
- University of Freiburg, Institute of Molecular Cell Biology, Germany
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36
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Affiliation(s)
- H Hug
- Institute of Molecular Cell Biology, University of Freiburg, Federal Republic of Germany
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37
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Ware JA, Heistad DD. Seminars in medicine of the Beth Israel Hospital, Boston. Platelet-endothelium interactions. N Engl J Med 1993; 328:628-35. [PMID: 8429855 DOI: 10.1056/nejm199303043280907] [Citation(s) in RCA: 198] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- J A Ware
- Department of Medicine, Beth Israel Hospital, Harvard Medical School, Boston, MA 02215
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38
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Overexpression of protein kinase C-delta and -epsilon in NIH 3T3 cells induces opposite effects on growth, morphology, anchorage dependence, and tumorigenicity. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53223-3] [Citation(s) in RCA: 406] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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39
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Clemens MJ, Trayner I, Menaya J. The role of protein kinase C isoenzymes in the regulation of cell proliferation and differentiation. J Cell Sci 1992; 103 ( Pt 4):881-7. [PMID: 1487501 DOI: 10.1242/jcs.103.4.881] [Citation(s) in RCA: 177] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- M J Clemens
- Department of Cellular and Molecular Sciences, St George's Hospital Medical School, London, UK
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40
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Watanabe T, Ono Y, Taniyama Y, Hazama K, Igarashi K, Ogita K, Kikkawa U, Nishizuka Y. Cell division arrest induced by phorbol ester in CHO cells overexpressing protein kinase C-delta subspecies. Proc Natl Acad Sci U S A 1992; 89:10159-63. [PMID: 1438205 PMCID: PMC50297 DOI: 10.1073/pnas.89.21.10159] [Citation(s) in RCA: 242] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Several lines of CHO cells stably overexpressing protein kinase C (PKC) subspecies to various extents were established by the DNA-mediated transfer. Upon treatment with phorbol 12-myristate 13-acetate, the growth of the cells expressing the PKC-delta subspecies was markedly inhibited, whereas cell lines expressing PKC-alpha, PKC-beta II, and PKC-zeta subspecies were not significantly affected. Flow cytometric analysis indicated that all cell lines overexpressing PKC-delta subspecies accumulated in G2/M phase in response to phorbol 12-myristate 13-acetate. In these arrested cells, dikaryons were predominant, implying that phorbol ester-induced inhibition of cell division is specific to telophase. These results suggest PKC-delta subspecies may play a role in the normal cell cycle progression.
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Affiliation(s)
- T Watanabe
- Biology Laboratories, Research and Development Division, Takeda Chemical Industries, Osaka, Japan
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41
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Eldar H, Livneh E. Phosphorylation of p90 and p52 in response to phorbol-esters in Swiss/3T3 cells overexpressing protein kinase C-alpha. Mol Biol Cell 1992; 3:1049-56. [PMID: 1421577 PMCID: PMC275665 DOI: 10.1091/mbc.3.9.1049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Cell lines stably overexpressing protein kinase C (PKC)-alpha were previously described by us. These cell lines were generated by the introduction of the full length cDNA coding for PKC-alpha into Swiss/3T3 cells. Here we show that activation of PKC-alpha by phorbol-esters induced in these cells specific phosphorylation of two cellular proteins p90 and p52. Phosphorylation of p80 (MARCKS protein), previously identified as a substrate for PKC, was also enhanced. Phosphorylated p90 and p52 proteins were associated with particulate membrane-enriched fractions and were extractable with the use of nonionic detergents. Time course analysis of phorbol-ester induced phosphorylation of p90 and p52 revealed maximal stimulation of phosphorylation after 15-30 min. Phosphamino acid analysis showed that phosphorylation of p90 and p52 occurred mainly on serine residues. Phosphorylation of p52 was also on threonine residues. Whereas, phorbol ester activation induced phosphorylation of both p90 and p52, the mitogens platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) enhanced phosphorylation of p90, but not p52. Thus, our studies showed the involvement of PKC-alpha in the regulation of p90 and p52 phosphorylation and provided direct evidence for the role of PKC-alpha in cellular signaling by PDGF and FGF. Moreover, the fact that phosphorylation of p52 was specific to phorbol ester activation may suggest its involvement in tumor promotion. Characterization of p90 and p52 will enable us to reveal the phosphorylation cascade activated downstream to PKC-alpha and to determine their role in mitogenic signaling and tumor promotion.
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Affiliation(s)
- H Eldar
- Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel
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42
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Abstract
Rat 6 fibroblasts that overproduce protein kinase C beta 1 (R6-PKC3 cells) are hypersensitive to complete transformation by the T24 H-ras oncogene; yet T24 H-ras-transformed R6-PKC3 cells are killed when exposed to 12-O-tetradecanoylphorbol-13-acetate (TPA) (W.-L. W. Hsiao, G. M. Housey, M. D. Johnson, and I. B. Weinstein, Mol. Cell. Biol. 9:2641-2647, 1989). Treatment of an R6-PKC3 subclone that harbors a T24 H-ras gene under the control of an inducible mouse metallothionein I promoter with ZnSO4 and TPA is extremely cytocidal. This procedure was used to isolate rare revertants that are resistant to this toxicity. Two revertant lines, R-1a and ER-1-2, continue to express very high levels of protein kinase C enzyme activity but, unlike the parental cells, do not grow in soft agar. Furthermore, these revertants are resistant to the induction of anchorage-independent growth by the v-src, v-H-ras, v-raf, and, in the case of the R-1a line, v-fos oncogenes. Both revertant lines, however, retain the ability to undergo morphological alterations when either treated with TPA or infected with a v-H-ras virus, thus dissociating anchorage independence from morphological transformation. The revertant phenotype of both R-1a and ER-1-2 cells is dominant over the transformed phenotype in somatic cell hybridizations. Interestingly, the revertant lines no longer induce the metallothionein I-T24 H-ras construct or the endogenous metallothionein I and II genes in response to three distinct agents: ZnSO4, TPA, and dexamethasone. The reduction in activity of metallothionein promoters seen in these revertants may reflect defects in signal transduction pathways that control the expression of genes mediating specific effects of protein kinase C and certain oncogenes in cell transformation.
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43
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Gescher A. Towards selective pharmacological modulation of protein kinase C--opportunities for the development of novel antineoplastic agents. Br J Cancer 1992; 66:10-9. [PMID: 1637658 PMCID: PMC1977896 DOI: 10.1038/bjc.1992.209] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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44
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Krauss RS, Guadagno SN, Weinstein IB. Novel revertants of H-ras oncogene-transformed R6-PKC3 cells. Mol Cell Biol 1992; 12:3117-29. [PMID: 1535685 PMCID: PMC364526 DOI: 10.1128/mcb.12.7.3117-3129.1992] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rat 6 fibroblasts that overproduce protein kinase C beta 1 (R6-PKC3 cells) are hypersensitive to complete transformation by the T24 H-ras oncogene; yet T24 H-ras-transformed R6-PKC3 cells are killed when exposed to 12-O-tetradecanoylphorbol-13-acetate (TPA) (W.-L. W. Hsiao, G. M. Housey, M. D. Johnson, and I. B. Weinstein, Mol. Cell. Biol. 9:2641-2647, 1989). Treatment of an R6-PKC3 subclone that harbors a T24 H-ras gene under the control of an inducible mouse metallothionein I promoter with ZnSO4 and TPA is extremely cytocidal. This procedure was used to isolate rare revertants that are resistant to this toxicity. Two revertant lines, R-1a and ER-1-2, continue to express very high levels of protein kinase C enzyme activity but, unlike the parental cells, do not grow in soft agar. Furthermore, these revertants are resistant to the induction of anchorage-independent growth by the v-src, v-H-ras, v-raf, and, in the case of the R-1a line, v-fos oncogenes. Both revertant lines, however, retain the ability to undergo morphological alterations when either treated with TPA or infected with a v-H-ras virus, thus dissociating anchorage independence from morphological transformation. The revertant phenotype of both R-1a and ER-1-2 cells is dominant over the transformed phenotype in somatic cell hybridizations. Interestingly, the revertant lines no longer induce the metallothionein I-T24 H-ras construct or the endogenous metallothionein I and II genes in response to three distinct agents: ZnSO4, TPA, and dexamethasone. The reduction in activity of metallothionein promoters seen in these revertants may reflect defects in signal transduction pathways that control the expression of genes mediating specific effects of protein kinase C and certain oncogenes in cell transformation.
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Affiliation(s)
- R S Krauss
- Institute of Cancer Research, Columbia University College of Physicians and Surgeons, New York, New York 10032
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45
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Hanania N, Lezenes JR, Castagna M. Tumorigenicity-associated expression of protein kinase C isoforms in rhabdomyosarcoma-derived cells. FEBS Lett 1992; 303:15-8. [PMID: 1592108 DOI: 10.1016/0014-5793(92)80467-u] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cell sublines were derived from Ni-induced rat rhabdomyosarcoma which differed in their degree of tumorigenicity. We compared the expression of protein kinase C isoforms alpha, beta, gamma and epsilon in three sublines developing tumors in syngeneic rats (Sy+) and in two sublines devoid of tumorigenicity in these animals (Sy-), with that of normal skeletal muscle. Northern and Western blotting experiments showed that PKC alpha was dramatically overexpressed in Sy- cells whereas it was underexpressed in Sy+ cells. Southern blot analysis provided evidence for a 3-fold increase of PKC alpha-related DNA fragments in Sy- cells. Steady-state levels of the PKC epsilon-related transcript were also markedly decreased in Sy+ cells. However, the expression of PKC beta-related RNA was increased in these cells. Our data support the concept that the differential expression of the PKC isoforms may play a critical role in determining the neoplastic phenotype.
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Affiliation(s)
- N Hanania
- Groupe de laboratoires de l'IRSC, Villejuif, France
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46
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Kelleher D, Long A. Development and characterization of a protein kinase C beta-isozyme-deficient T-cell line. FEBS Lett 1992; 301:310-4. [PMID: 1577171 DOI: 10.1016/0014-5793(92)80264-h] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In the human T-cell lymphoma line, HuT 78, proliferation and phorbol ester-induced growth arrest and differentiation were inhibited by the protein kinase C (PKC) inhibitor, staurosporine. By contrast, an alternative PKC inhibitor, H-7, inhibited proliferation but not phorbol ester-induced growth arrest. The cell line was found to contain both alpha and beta isoforms of PKC by Western blot techniques. A cell line, K-4, was cloned from HuT 78 in the presence of H-7 and this clone was found to be positive for PKC-alpha only. PKC-beta did not return on cultivation in the absence of H-7. Proliferation of K-4 was insensitive to inhibition with both H-7 and staurosporine. However, phorbol ester-induced growth arrest remained staurosporine sensitive. Phorbol-stimulated IL-2 secretion was minimal in the PKC-beta-deficient cell line. These data suggest that PKC-beta may be a regulatory enzyme for proliferation and stimulated interleukin-2 secretion in HuT 78 cells. Heterogeneity of responses to PKC activation may reflect the use of different isozymes in different intracellular pathways. The K-4 cell line should provide a useful tool in the dissection of involvement of PKC isozymes in cellular function.
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Affiliation(s)
- D Kelleher
- Department of Clinical Medicine, Trinity College Dublin, Ireland
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47
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Altered regulation of a major substrate of protein kinase C in rat 6 fibroblasts overproducing PKC beta I. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)45936-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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48
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Abstract
Protein kinase C (PKC), an enzyme involved in signal transduction, responds to diacyl glycerol and also to phorbol ester, a ligand analogous to diacyl glycerol. We have studied the expression of the major isoforms (alpha, beta I, beta II, and gamma) in eight human glioblastoma cell lines. In all eight lines, PKC-alpha mRNA and protein were expressed. In none of the eight did a probe for PKC-beta I and -beta II mRNA give positive results nor were Western blots for PKC-beta II positive. The half-life for PKC alpha mRNA was approximately 16 h and levels of the mRNA were increased slightly following addition of phorbol myristate acetate (PMA) or transforming growth factor-beta (TGF beta). PKC-gamma was present in most of the glioblastomas. In cell line A172, 82% of the PKC-alpha was present in the cytosol with the remainder evenly divided between plasma membrane and nucleus. Thirty minutes after addition of PMA, 33% of the total original protein was in the plasma membrane and 48% in the nuclear fraction. By 21 h, no PKC-alpha was recovered from any fraction. PKC-gamma was also down-regulated in the presence of PMA, but there was no evidence for translocation to the plasma membrane or nuclear fraction. In a more detailed study, translocation of PKC-alpha in the presence of PMA was complete by 10 min, and a major decrease in the PKC translocated to the plasma-membrane fraction occurred some time between 2 and 4 h after PMA addition, while a major decrease in the translocated nuclear fraction occurred some time after 6 h. cAMP alone had no effect on the PKC alpha protein level or distribution, nor did it alter the translocation and down-regulation due to PMA exposure. In these studies the level of PKC-alpha mRNA in tumors was similar to that in normal glial cells.
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Affiliation(s)
- A Misra-Press
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
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