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Vaziri C, Faller DV. Repression of platelet-derived growth factor beta-receptor expression by mitogenic growth factors and transforming oncogenes in murine 3T3 fibroblasts. Mol Cell Biol 1995; 15:1244-53. [PMID: 7862118 PMCID: PMC230347 DOI: 10.1128/mcb.15.3.1244] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Platelet-derived growth factor BB (PDGF-BB) is an important extracellular factor for regulating the G0-S phase transition of murine BALB/c-3T3 fibroblasts. We have investigated the expression of the PDGF beta receptor (PDGF beta R) in these cells. We show that the state of growth arrest in G0, resulting from serum deprivation, is associated with increased expression of the PDGF beta R. When the growth-arrested fibroblasts are stimulated to reenter the cell cycle by the mitogenic action of serum or certain specific combinations of growth factors, PDGF beta R mRNA levels and cell surface PDGF-BB-binding sites are markedly downregualted. Oncogene-transformed 3T3 cell lines, which fail to undergo growth arrest following prolonged serum deprivation, express constitutively low levels of the PDGF beta R mRNA and possess greatly reduced numbers of cell surface PDGF receptors, as determined by PDGF-BB binding and Western blotting (immunoblotting). Nuclear runoff assays indicate the mechanism of repression of PDGF beta R expression to be, at least in large part, transcriptional. These data indicate that expression of the PDGF beta R is regulated in a growth state-dependent manner in fibroblasts and suggest that this may provide a means by which cells can modulate their responsiveness to the actions of PDGF.
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MESH Headings
- 3T3 Cells
- Animals
- Cell Cycle/drug effects
- Cell Division/drug effects
- Cell Line
- Cell Membrane/metabolism
- Cell Nucleus/drug effects
- Cell Nucleus/metabolism
- Cell Transformation, Neoplastic
- DNA Probes
- Dose-Response Relationship, Drug
- Fibroblast Growth Factor 2/pharmacology
- Fibroblasts/cytology
- Fibroblasts/drug effects
- Fibroblasts/metabolism
- Gene Expression/drug effects
- Genes, ras
- Genes, src
- Growth Substances/pharmacology
- Immunoblotting
- Kinetics
- Mice
- Mice, Inbred BALB C
- Oncogenes
- Platelet-Derived Growth Factor/pharmacology
- Proto-Oncogenes
- RNA, Messenger/analysis
- RNA, Messenger/biosynthesis
- Receptor, Platelet-Derived Growth Factor beta
- Receptors, Platelet-Derived Growth Factor/biosynthesis
- Recombinant Proteins/pharmacology
- Resting Phase, Cell Cycle
- Thymidine/metabolism
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Affiliation(s)
- C Vaziri
- Cancer Research Center, Boston University School of Medicine, Massachusetts 02118
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Tomáska L, Resnick RJ. Involvement of a phosphotyrosine protein phosphatase in the suppression of platelet-derived growth factor receptor autophosphorylation in ras-transformed cells. Biochem J 1993; 293 ( Pt 1):215-21. [PMID: 8328963 PMCID: PMC1134342 DOI: 10.1042/bj2930215] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The nature of the suppression of platelet-derived growth factor (PDGF) receptor autophosphorylation in ras-transformed NIH 3T3 fibroblasts was investigated. The PDGF receptor from ras-transformed cells that had been purified by wheatgerm-lectin affinity chromatography displayed normal PDGF-induced autophosphorylation, indicating that the receptor is not irreversibly modified. Various phosphotyrosine-protein-phosphatase inhibitors did not reverse the inhibition of PDGF-receptor kinase in crude membrane preparations from ras-transformed cells. However, treatment of intact ras-transformed cells both with 2 mM sodium orthovanadate and with 20 microM phenylarsine oxide restored PDGF-receptor tyrosine-kinase activity to a level similar to that observed in normal cells. Direct measurement of the phosphatase activities in crude cellular fractions revealed a 2.5-fold higher membrane-associated phosphotyrosine-protein-phosphatase activity in ras-transformed cells, whereas phosphoserine-protein-phosphatase activity remained unchanged between the cell lines. These data suggest that the suppression of the PDGF-receptor tyrosine-kinase activity in ras-transformed cells is mediated via an inhibitory component, distinct from the receptor, that may be positively regulated by the dephosphorylation of tyrosine residue(s).
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Affiliation(s)
- L Tomáska
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, NY 14853
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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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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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Depletion of c-myc with specific antisense sequences reverses the transformed phenotype in ras oncogene-transformed NIH 3T3 cells. Mol Cell Biol 1991. [PMID: 2046673 DOI: 10.1128/mcb.11.7.3699] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ras oncogene-transformed NIH 3T3 cells expressing glucocorticoid-inducible antisense c-myc cDNA transcripts at levels sufficient to deplete c-myc protein lost their transformed morphology and the ability to grow in soft agar; their ability to form tumors in nude mice was also impaired. These changes were dependent on the continuous expression of the antisense sequences. No major effects on plating efficiencies, growth rates in monolayer culture, or immortalization were observed in the revertant cells, indicating that the observed effects were not a toxic consequence of c-myc protein depletion. Transfection with the same vector expressing c-myc in the sense orientation or other control vectors had no effect on transformation. These results suggest that a certain minimum level of expression of c-myc is required for the maintenance of ras transformation in NIH 3T3 cells.
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Sklar MD, Thompson E, Welsh MJ, Liebert M, Harney J, Grossman HB, Smith M, Prochownik EV. Depletion of c-myc with specific antisense sequences reverses the transformed phenotype in ras oncogene-transformed NIH 3T3 cells. Mol Cell Biol 1991; 11:3699-710. [PMID: 2046673 PMCID: PMC361133 DOI: 10.1128/mcb.11.7.3699-3710.1991] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
ras oncogene-transformed NIH 3T3 cells expressing glucocorticoid-inducible antisense c-myc cDNA transcripts at levels sufficient to deplete c-myc protein lost their transformed morphology and the ability to grow in soft agar; their ability to form tumors in nude mice was also impaired. These changes were dependent on the continuous expression of the antisense sequences. No major effects on plating efficiencies, growth rates in monolayer culture, or immortalization were observed in the revertant cells, indicating that the observed effects were not a toxic consequence of c-myc protein depletion. Transfection with the same vector expressing c-myc in the sense orientation or other control vectors had no effect on transformation. These results suggest that a certain minimum level of expression of c-myc is required for the maintenance of ras transformation in NIH 3T3 cells.
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Affiliation(s)
- M D Sklar
- Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor 48109
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7
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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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Oncogene N-ras mediates selective inhibition of c-fos induction by nerve growth factor and basic fibroblast growth factor in a PC12 cell line. Mol Cell Biol 1990. [PMID: 2108319 DOI: 10.1128/mcb.10.4.1556] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A cell line was generated from U7 cells (a subline of PC12 rat pheochromocytoma cells) that contains a stably integrated transforming mouse N-ras (Lys-61) gene under the control of the long terminal repeat from mouse mammary tumor virus. Such cells, designated UR61, undergo neuronal differentiation upon exposure to nanomolar concentrations of dexamethasone, as a consequence of expression of the activated N-ras gene (I. Guerrero, A. Pellicer, and D.E. Burstein, Biochem, Biophys. Res. Commun. 150:1185-1192, 1988). Exposure of UR61 cells to either nerve growth factor (NGF) or basic fibroblast growth factor (bFGF) results in a marked induction of c-fos RNA, with kinetics paralleling those of NGF- or bFGF-induced expression of c-fos RNA in PC12 cells. Dexamethasone-induced expression of activated N-ras p21 results in blocking of c-fos RNA induction by NGF or bFGF in a time-dependent manner. Activated N-ras p21-mediated inhibition of c-fos RNA induction in UR61 cells is selective for NGF and bFGF and is not due to selective degradation of c-fos RNA. Normal and transforming N-ras can trans activate the chloramphenicol acetyltransferase gene linked to mouse c-fos regulatory sequences when transient expression assays are performed. Our observations suggest that N-ras p21 selectively interacts with pathways involved in induction of c-fos expression which initiate at the receptors for NGF and bFGF.
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Thomson TM, Green SH, Trotta RJ, Burstein DE, Pellicer A. Oncogene N-ras mediates selective inhibition of c-fos induction by nerve growth factor and basic fibroblast growth factor in a PC12 cell line. Mol Cell Biol 1990; 10:1556-63. [PMID: 2108319 PMCID: PMC362260 DOI: 10.1128/mcb.10.4.1556-1563.1990] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A cell line was generated from U7 cells (a subline of PC12 rat pheochromocytoma cells) that contains a stably integrated transforming mouse N-ras (Lys-61) gene under the control of the long terminal repeat from mouse mammary tumor virus. Such cells, designated UR61, undergo neuronal differentiation upon exposure to nanomolar concentrations of dexamethasone, as a consequence of expression of the activated N-ras gene (I. Guerrero, A. Pellicer, and D.E. Burstein, Biochem, Biophys. Res. Commun. 150:1185-1192, 1988). Exposure of UR61 cells to either nerve growth factor (NGF) or basic fibroblast growth factor (bFGF) results in a marked induction of c-fos RNA, with kinetics paralleling those of NGF- or bFGF-induced expression of c-fos RNA in PC12 cells. Dexamethasone-induced expression of activated N-ras p21 results in blocking of c-fos RNA induction by NGF or bFGF in a time-dependent manner. Activated N-ras p21-mediated inhibition of c-fos RNA induction in UR61 cells is selective for NGF and bFGF and is not due to selective degradation of c-fos RNA. Normal and transforming N-ras can trans activate the chloramphenicol acetyltransferase gene linked to mouse c-fos regulatory sequences when transient expression assays are performed. Our observations suggest that N-ras p21 selectively interacts with pathways involved in induction of c-fos expression which initiate at the receptors for NGF and bFGF.
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Affiliation(s)
- T M Thomson
- Department of Pathology, New York University Medical Center, New York 10016
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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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