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James W. Towards Gene-Inhibition Therapy: A Review of Progress and Prospects in the Field of Antiviral Antisense Nucleic Acids and Ribozymes. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/095632029100200401] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Antisense RNA and its derivatives may provide the basis for highly selective gene inhibition therapies of virus infections. In this review, I concentrate on advances made in the study of antisense RNA and ribozymes during the last five years and their implications for the development of such therapies. It appears that antisense RNAs synthesized at realistic levels within the cell can be much more effective inhibitors than originally supposed. Looking at those experiments that enable comparisons to be made, it seems that inhibitory antisense RNAs are not those that are complementary to particular sites within mRNAs but those that are able to make stable duplexes with their targets, perhaps by virtue of their secondary structure and length. The inclusion of ribozyme sequences within antisense RNAs confers RNA-cleaving activity upon them in vitro and possibly in cells, thereby offering the possibility of markedly increasing their therapeutic potential. The varieties of natural ribozyme and their adaptation as artificial catalysts are reviewed. The implications of these developments for antiviral therapy are discussed.
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Affiliation(s)
- W. James
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, U.K
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2
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Gil GA, Bussolino DF, Portal MM, Alfonso Pecchio A, Renner ML, Borioli GA, Guido ME, Caputto BL. c-Fos activated phospholipid synthesis is required for neurite elongation in differentiating PC12 cells. Mol Biol Cell 2004; 15:1881-94. [PMID: 14767061 PMCID: PMC379284 DOI: 10.1091/mbc.e03-09-0705] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have previously shown that c-Fos activates phospholipid synthesis through a mechanism independent of its genomic AP-1 activity. Herein, using PC12 cells induced to differentiate by nerve growth factor, the genomic effect of c-Fos in initiating neurite outgrowth is shown as distinct from its nongenomic effect of activating phospholipid synthesis and sustaining neurite elongation. Blocking c-Fos expression inhibited differentiation, phospholipid synthesis activation, and neuritogenesis. In cells primed to grow, blocking c-Fos expression determined neurite retraction. However, transfected cells expressing c-Fos or c-Fos deletion mutants with capacity to activate phospholipid synthesis sustain neurite outgrowth and elongation in the absence of nerve growth factor. Results disclose a dual function of c-Fos: it first releases the genomic program for differentiation and then associates to the endoplasmic reticulum and activates phospholipid synthesis. Because phospholipids are key membrane components, we hypothesize this latter phenomenon as crucial to support membrane genesis demands required for cell growth and neurite elongation.
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Affiliation(s)
- Germán A Gil
- Centro de Investigaciones en Química Biológica de Córdoba (Consejo Nacional de Investigaciones Científicas y Técnicas), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina
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Zhao G, Nakano K, Chijiiwa K, Ueda J, Tanaka M. Inhibited activities in CCAAT/enhancer-binding protein, activating protein-1 and cyclins after hepatectomy in rats with thioacetamide-induced liver cirrhosis. Biochem Biophys Res Commun 2002; 292:474-81. [PMID: 11906187 DOI: 10.1006/bbrc.2002.6630] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Transcriptional activation of nuclear factor (NF)-kappaB, signal transducers and activators of transcription (STAT) 3, activating protein (AP)-1 and CCAAT/enhancer-binding protein (C/EBP) plays an important role in liver regeneration by modulating cell cycle regulators. The regeneration of cirrhotic liver after hepatectomy is inhibited despite intact expression of growth factors. To elucidate the mechanism involved, regeneration responses in growth factor receptors, transcription factors, and cell cycle regulators after two-thirds hepatectomy were compared between rats with thioacetamide-induced cirrhotic and normal liver. The expression of c-met and epidermal growth factor receptor analyzed by RT-PCR and immunohistochemistry did not differ between the two groups. The activities of C/EBP and AP-1 evaluated by electrophoretic mobility shift assay were significantly inhibited in the cirrhotic group compared with those in the control group, but not those of NF-kappaB and STAT3. The expression of cyclin-D1, -E, and -A assessed by Western blot analysis was significantly decreased in the cirrhotic group compared with the control group. The level in p21(Cip1) or p27(Kip1) did not differ between the two groups. The liver regeneration estimated by the rates of [(3)H]thymidine incorporation into DNA and staining of proliferating cell nuclear antigen was significantly lower in the cirrhotic rats than in the controls. In conclusion, downregulation of cyclin -D1, -E, and -A expression, which may be induced by impaired activities of C/EBP and AP-1, is responsible for the decreased regenerative capacity of cirrhotic liver after partial hepatectomy.
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Affiliation(s)
- Gang Zhao
- Department of Surgery and Oncology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Shimamura T, Hsu TC, Colburn NH, Bejcek BE. Activation of NF-kappaB is required for PDGF-B chain to transform NIH3T3 cells. Exp Cell Res 2002; 274:157-67. [PMID: 11855867 DOI: 10.1006/excr.2001.5449] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Elucidating the secondary signaling molecules that are necessary for platelet-derived growth factor (PDGF) to stimulate tumor development will be crucial to the understanding and treatment of a variety of cancers. Several lines of evidence have indicated that the transcription factor NF-kappaB plays a central role in transformation induced by Ha-ras and Bcr-abl, but nothing is known concerning its role in transformation by PDGF. Here we demonstrate that transcription from a promoter containing NF-kappaB binding sequences as well as the DNA binding activity of NF-kappaB were increased in PDGF-B-chain-transformed mouse fibroblast cells. Focus formation of PDGF-B-chain-transformed mouse fibroblasts was suppressed by treatment with acetylsalicylic acid (ASA) and salicylic acid, which are known inhibitors of NF-kappaB activation, but other nonsteroidal anti-inflammatory drugs that do not have an effect on NF-kappaB activity did not affect focus formation in these cells. Furthermore, expression of a dominant negative mutant of IkappaBalpha, pMEIkappaBalpha67CJ, and a dominant negative mutant of p65, p65DeltaC, resulted in decreased focus formation and NF-kappaB activity. Therefore, the transcription factor NF-kappaB plays a vital role in PDGF-B chain transformation of mouse fibroblast cells, and the NF-kappaB activity is sensitive to treatment with ASA.
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Affiliation(s)
- Takeshi Shimamura
- Department of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008, USA
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Gao C, Jokerst R, Gondipalli P, Cai SR, Kennedy S, Flye MW, Ponder KP. Lipopolysaccharide potentiates the effect of hepatocyte growth factor on hepatocyte replication in rats by augmenting AP-1 activity. Hepatology 1999; 30:1405-16. [PMID: 10573519 DOI: 10.1002/hep.510300602] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
The liver regenerates by replication of differentiated hepatocytes after damage or removal of part of the liver. Although several growth factors and signaling pathways are activated during regeneration, it is unclear as to which of these are essential for hepatocyte replication. We show here that low- (1 mg/kg) and high- (10 mg/kg) dose hepatocyte growth factor (HGF) induced replication of 2.1% and 11.1% of hepatocytes in rats, respectively. Lipopolysaccharide (LPS), an inducer of the acute phase response, augmented hepatocyte replication in response to low- and high-dose HGF by 4- and 2-fold, respectively. HGF alone induced moderate levels of c-Jun-N-terminal kinase (JNK) and p44/p42 mitogen-activated protein kinase (MAPK), resulting in moderate levels of AP-1-DNA binding activity. The combination of LPS + HGF increased JNK and AP-1-DNA binding activity more than levels seen with LPS or HGF alone. The activation of Stat3 that was observed after administration of LPS + HGF, but not HGF alone, could contribute to increased transcription of AP-1 components. Because phosphorylation of the c-Jun component of AP-1 by JNK increases its ability to activate transcription, the AP-1 in hepatocytes from animals treated with LPS + HGF may be more active than in rats treated with LPS or HGF alone. LPS may contribute to hepatocyte replication by potentiating the effect of HGF on the activation of both AP-1-DNA binding and transcriptional activity.
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Affiliation(s)
- C Gao
- Departments of Internal Medicine and Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
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Affiliation(s)
- C R Bachier
- South Texas Cancer Institute, San Antonio 78229, USA
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Affiliation(s)
- M Piechaczyk
- Institut de Génétique Moléculaire de Montpellier, UMR 9942, CNRS, BP5051, France
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9
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Saijo Y, Perlaky L, Valdez BC, Busch RK, Henning D, Zhang WW, Busch H. The effect of antisense p120 construct on p120 expression and cell proliferation in human breast cancer MCF-7 cells. Cancer Lett 1993; 68:95-104. [PMID: 8443798 DOI: 10.1016/0304-3835(93)90134-u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Malignant transformation of NIH3T3 cells was observed by transfection with the pSVX vector containing a sense human p120 cDNA construct (pSVX120). Subsequent transfection of these transformed cells with a dexamethasone inducible antisense p120 construct (pMSG021) markedly reduced the expression of human p120 and the growth rate of these transformed cells (Perklaky et al., Cancer Res., (1992) 52, 428-436). In the present study, a human breast cancer cell line (MCF-7) which expresses the p120 protein was transfected by electroporation with a pSVX plasmid-construct containing the antisense p120 cDNA (pSVX021). Clones containing the pSVX021 construct were selected and analyzed for expression of p120 mRNA, protein and growth characteristics. The expression of the p120 protein was inhibited by 44% in the antisense-transfected MCF-7pSVX021 cells; a 56% inhibition of cell-growth and a reduced colony formation in soft agarose were also observed. The growth of MCF-7 cells transfected with the p120 antisense construct was reduced by 93% in nude mice.
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Affiliation(s)
- Y Saijo
- Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030
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Prins J, de Vries EG, Mulder NH. Antisense of oligonucleotides and the inhibition of oncogene expression. Clin Oncol (R Coll Radiol) 1993; 5:245-52. [PMID: 8398922 DOI: 10.1016/s0936-6555(05)80238-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Inhibition of oncogenes represents a new strategy that might lead to a better understanding of the different steps involved in tumorigenesis and also to the development of new therapeutic approaches. Attempts have been made to interfere with gene expression by in situ generation of mRNA from recombinant vectors (antisense RNA) or by the exogenous introduction of synthetic oligonucleotides (antisense oligonucleotides). Antisense oligonucleotides can inhibit the expression of specific genes by blocking the translation after hybridization with the target mRNAs--the antisense strategy. Antisense oligonucleotides can also be targeted to specific sequences of the DNA double helix. This causes inhibition of transcription--the antigene strategy. Regulatory sequences involved in controlling the transcription of oncogenes are used as targets for this type of 'antigene' oligonucleotide. Both strategies can be applied to control the oncogene expression of tumour cells in tissue culture, as exemplified in this review by myc antisense oligonucleotides. Recently the antisense strategy is moving into the area of clinical trials, aimed at curing chronic myelogenous leukaemia by ex vivo bone marrow purging. However, many difficulties have still to be overcome before the application of antisense oligonucleotides can be evaluated in the treatment of cancer.
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Affiliation(s)
- J Prins
- Department of Internal Medicine, University Hospital Groningen, The Netherlands
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11
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Abstract
The c-fos proto-oncogene has been implicated as a central regulatory component of the nuclear response to mitogens and other extracellular stimuli. Embryonic stem cells targeted at the c-fos locus have been used to generate chimeric mice that have transmitted the mutated allele through the germline. Homozygous mutants show reduced placental and fetal weights and significant loss of viability at birth. Approximately 40% of the homozygous mutants survive and grow at normal rates until severe osteopetrosis, characterized by foreshortening of the long bones, ossification of the marrow space, and absence of tooth eruption, begins to develop at approximately 11 days. Among other abnormalities, these mice show delayed or absent gametogenesis, lymphopenia, and altered behavior. Despite these defects, many live as long as their wild-type or heterozygous littermates (currently 7 months). These data indicate that c-fos is not required for the growth of most cell types but is involved in the development and function of several distinct tissues.
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Affiliation(s)
- R S Johnson
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115
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Belt PB, van Oosterwijk MF, Odijk H, Hoeijmakers JH, Backendorf C. Induction of a mutant phenotype in human repair proficient cells after overexpression of a mutated human DNA repair gene. Nucleic Acids Res 1991; 19:5633-7. [PMID: 1945841 PMCID: PMC328968 DOI: 10.1093/nar/19.20.5633] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Antisense and mutated cDNA of the human excision repair gene ERCC-1 were overexpressed in repair proficient HeLa cells by means of an Epstein-Barr-virus derived cDNA expression vector. Whereas antisense RNA did not influence the survival of the transfected cells, a mutated cDNA generating an ERCC-1 protein with two extra amino acids in a conserved region of its C-terminal part resulted in a significant sensitization of the HeLa transfectants to mitomycin C-induced damage. These results suggest that overexpression of the mutated ERCC-1 protein interferes with proper functioning of the excision repair pathway in repair proficient cells and is compatible with a model in which the mutated ERCC-1 protein competes with the wild-type polypeptide for a specific step in the repair process or for occupation of a site in a repair complex. Apparently, this effect is more pronounced for mitomycin C induced crosslink repair than for UV-induced DNA damage.
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Affiliation(s)
- P B Belt
- Department of Biochemistry, Gorlaeus Laboratories, Leiden University, The Netherlands
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13
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Lloyd A, Yancheva N, Wasylyk B. Transformation suppressor activity of a Jun transcription factor lacking its activation domain. Nature 1991; 352:635-8. [PMID: 1907719 DOI: 10.1038/352635a0] [Citation(s) in RCA: 152] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The oncoprotein c-Jun is thought to be a mediator of ras transformation as both its synthesis and activity as a transcription factor are stimulated by ras expression. But c-Jun co-operates with ras in transformation assays, suggesting that they act along different pathways (reviewed in ref. 4). Here we show by means of a dominant-negative mutated transcription factor that c-Jun potentially in conjunction with other factors that interact with it is necessary for transformation by ras. The mutant Jun lacks an activation domain and blocks stimulation of transcription by several oncoproteins, including Ras, v-Src, polyoma middle T, c-Jun and c-Fos, as well as by the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). The inhibition is specific for motifs that bind Jun: activation of an NF-kappa B/Rel motif is not affected. This Jun mutant acts as an anti-oncogene in ras-transformed cells, generating non-transformed revertants that have acquired anchorage and density-dependent growth, as well as reduced tumorigenicity in vivo. Mutants of other transcription factors designed to inhibit transformation will enable us to study their role in signal transduction.
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Affiliation(s)
- A Lloyd
- LGME-CNRS, U184-INSERM, Institut de Chimie Biologique, Faculté de Medecine, Strasbourg, France
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14
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Holt JT. Cutting the chain of command: specific inhibitors of transcription. ANTISENSE RESEARCH AND DEVELOPMENT 1991; 1:365-9. [PMID: 1821658 DOI: 10.1089/ard.1991.1.365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cell growth and differentiation are regulated (at least in part) by changes in gene transcription. The cloning and characterization of transcription factors has revealed that these factors coordinately regulate the transcription of specific genetic programs; for example, a number of phorbol ester-induced genes are activated by binding of the transcription factors Fos and Jun to specific DNA sequences. Clearly, inhibition of either the production or function of specific transcription factors would alter complete genetic programs, changing the expression of a great number of genes (analogous to cutting the chain of military command and affecting an entire brigade or division). Our laboratory and others have employed genetic methods to specifically inhibit transcription by two distinct methods: (1) antisense inhibition of the production of transcription factors; and (2) introduction of target DNA sequences to "soak up"or quench transcription factors. In this report, we present data showing that serum-stimulated induction of the c-fos gene may be reduced more than 90% by introduction of target DNA sequences containing the serum response element (SRE); identical amounts of mutant SRE sequences have no effect on gene induction. These studies demonstrate that specific inhibitors of transcription can have significant effects on cellular gene expression. The challenge is to modulate transcriptional programs without deleterious effects on normal cells.
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Affiliation(s)
- J T Holt
- Department of Cell Biology, Vanderbilt University, Nashville, Tennessee
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Munir MI, Rossiter BJ, Caskey CT. Antisense RNA production in transgenic mice. SOMATIC CELL AND MOLECULAR GENETICS 1990; 16:383-94. [PMID: 2218725 DOI: 10.1007/bf01232466] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
There are many reports of antisense inhibition of gene expression in cultured cells. We have generated four strains of transgenic mice expressing antisense hypoxanthine guanine phosphoribosyltransferase (HPRT) RNA in brain, or heart and liver, or all three organs. In the brain of one strain, the level of antisense RNA in the different brain regions roughly correlates with the degree of inhibition of the native HPRT mRNA in those same regions. Despite this decrease of up to 60% of endogenous HPRT mRNA, no reproducible reduction in HPRT activity has been observed. Possible reasons for the differences between the effectiveness of antisense inhibition in cultured cells and transgenic animals are discussed.
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Affiliation(s)
- M I Munir
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030
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Antisense-fos RNA causes partial reversion of the transformed phenotypes induced by the c-Ha-ras oncogene. Mol Cell Biol 1990. [PMID: 1690847 DOI: 10.1128/mcb.10.4.1545] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several lines of evidence have suggested that c-fos may act downstream from c-Ha-ras in a growth-regulatory signal transduction pathway. We used antisense RNA to inhibit c-fos gene expression and investigated the effects of diminished c-fos expression on the phenotypes induced by the EJ c-Ha-ras oncogene in NIH 3T3 cells. Immunofluorescent staining demonstrated that the antisense RNA caused a marked reduction in the amount of c-fos protein expressed following serum stimulation. EJ cells containing antisense-fos RNA continued to overexpress ras and remained capable of proliferating in vitro. However, the antisense-fos RNA caused a partial reversion of the major transformed phenotypes of EJ cells, including a restoration of both density-dependent growth arrest and the ability to be rendered quiescent by serum deprivation, a reversion to a flat morphology, inhibition of anchorage-independent growth, and inhibition of tumorigenicity in nude mice. Our results indicate that inhibition of c-fos expression, to a level still supporting in vitro proliferation, prevents the transforming effects of the ras oncogene; they thus provide additional evidence for the participation of c-fos in ras-regulated signal transduction pathways.
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Ledwith BJ, Manam S, Kraynak AR, Nichols WW, Bradley MO. Antisense-fos RNA causes partial reversion of the transformed phenotypes induced by the c-Ha-ras oncogene. Mol Cell Biol 1990; 10:1545-55. [PMID: 1690847 PMCID: PMC362259 DOI: 10.1128/mcb.10.4.1545-1555.1990] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Several lines of evidence have suggested that c-fos may act downstream from c-Ha-ras in a growth-regulatory signal transduction pathway. We used antisense RNA to inhibit c-fos gene expression and investigated the effects of diminished c-fos expression on the phenotypes induced by the EJ c-Ha-ras oncogene in NIH 3T3 cells. Immunofluorescent staining demonstrated that the antisense RNA caused a marked reduction in the amount of c-fos protein expressed following serum stimulation. EJ cells containing antisense-fos RNA continued to overexpress ras and remained capable of proliferating in vitro. However, the antisense-fos RNA caused a partial reversion of the major transformed phenotypes of EJ cells, including a restoration of both density-dependent growth arrest and the ability to be rendered quiescent by serum deprivation, a reversion to a flat morphology, inhibition of anchorage-independent growth, and inhibition of tumorigenicity in nude mice. Our results indicate that inhibition of c-fos expression, to a level still supporting in vitro proliferation, prevents the transforming effects of the ras oncogene; they thus provide additional evidence for the participation of c-fos in ras-regulated signal transduction pathways.
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MESH Headings
- Animals
- Blotting, Southern
- Cell Division
- Cell Line
- Cell Transformation, Neoplastic
- Cells, Cultured
- DNA Replication
- DNA, Neoplasm/genetics
- Dexamethasone/pharmacology
- Female
- Gene Expression Regulation, Neoplastic
- Genes, ras
- Humans
- Kinetics
- Mice
- Mice, Nude
- Neoplasm Transplantation
- Phenotype
- Protein-Tyrosine Kinases/genetics
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins c-fos
- Proto-Oncogenes
- RNA/genetics
- RNA, Antisense
- RNA, Messenger/antagonists & inhibitors
- Transfection
- Transplantation, Heterologous
- Urinary Bladder Neoplasms/genetics
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Affiliation(s)
- B J Ledwith
- Merck Sharp & Dohme Research Laboratories, West Point, Pennsylvania 19486
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Edwards SA, Rundell AY, Adamson ED. Expression of c-fos antisense RNA inhibits the differentiation of F9 cells to parietal endoderm. Dev Biol 1988; 129:91-102. [PMID: 2457527 DOI: 10.1016/0012-1606(88)90164-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
To test the putative role of c-fos in F9 differentiation, we have attempted to inhibit c-fos expression in these cells using an SV40-based expression vector (pSVneo-sof) that programs expression of c-fos antisense (sof) sequences as a 3' extension of a neo mRNA transcript. Of six G418-resistant clones isolated in transfection experiments, five expressed neo-sof transcripts. Two clones synthesized polyadenylated mRNA of the expected size (3.8 kb), two were smaller than expected, and one was larger. Two clones that expressed reduced levels of c-fos protein were inhibited in the induction of laminin, type IV collagen, and proteoglycan-19 RNA transcripts measured after 4 days of differentiation induction with RA and dibutyryl cyclic AMP. Also inhibited was the induction of the differentiation markers, TROMA-1 and TROMA-3. Antisense-expressing cells were not inhibited in the differentiation pathway to visceral endoderm since the alpha-fetoprotein gene was activated normally. We conclude that c-fos antisense expression inhibits some aspects of differentiation in F9 cells.
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Affiliation(s)
- S A Edwards
- Cancer Research Center, La Jolla Cancer Research Foundation, California 92037
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