Altered transcriptional activity of c-fos promoter plasmids in v-raf-transformed NIH 3T3 cells.

In cells transformed by v-raf, an oncogenic counterpart of the serine/threonine kinase Raf-1, regulatory elements of the c-fos promoter were active under conditions of cell growth or stimulation for which they were inactive in untransformed control cells. This suggests that v-raf transforms by deregulating transcription of early response genes.

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Kinase-deficient Pak1 mutants inhibit Ras transformation of Rat-1 fibroblasts.

Molecular and Cellular Biology ◽

10.1128/mcb.17.8.4454 ◽

1997 ◽

Vol 17 (8) ◽

pp. 4454-4464 ◽

Cited By ~ 151

Author(s):

Y Tang ◽

Z Chen ◽

D Ambrose ◽

J Liu ◽

J B Gibbs ◽

...

Keyword(s):

Cellular Transformation ◽

Mitogen Activated Protein Kinase ◽

3T3 Cells ◽

Serine Threonine Kinase ◽

Threonine Kinase ◽

Jun Kinase ◽

Ras Activation ◽

Mitogen Activated Protein ◽

Nih 3T3 ◽

Dependent Mechanism

Among the mechanisms by which the Ras oncogene induces cellular transformation, Ras activates the mitogen-activated protein kinase (MAPK or ERK) cascade and a related cascade leading to activation of Jun kinase (JNK or SAPK). JNK is additionally regulated by the Ras-related G proteins Rac and Cdc42. Ras also regulates the actin cytoskeleton through an incompletely elucidated Rac-dependent mechanism. A candidate for the physiological effector for both JNK and actin regulation by Rac and Cdc42 is the serine/threonine kinase Pak (p65pak). We show here that expression of a catalytically inactive mutant Pak, Pak1(R299), inhibits Ras transformation of Rat-1 fibroblasts but not of NIH 3T3 cells. Typically, 90 to 95% fewer transformed colonies were observed in cotransfection assays with Rat-1 cells. Pak1(R299) did not inhibit transformation by the Raf oncogene, indicating that inhibition was specific for Ras. Furthermore, Rat-1 cell lines expressing Pak1(R299) were highly resistant to Ras transformation, while cells expressing wild-type Pak1 were efficiently transformed by Ras. Pak1(L83,L86,R299), a mutant that fails to bind either Rac or Cdc42, also inhibited Ras transformation. Rac and Ras activation of JNK was inhibited by Pak1(R299) but not by Pak1(L83,L86,R299). Ras activation of ERK was inhibited by both Pak1(R299) and Pak1(L83,L86,R299), while neither mutant inhibited Raf activation of ERK. These results suggest that Pak1 interacts with components essential for Ras transformation and that inhibition can be uncoupled from JNK but not ERK signaling.

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Transactivation of Platelet-Derived Growth Factor Receptor α by the GTPase-Deficient Activated Mutant of Gα12

Molecular and Cellular Biology ◽

10.1128/mcb.26.1.50-62.2006 ◽

2006 ◽

Vol 26 (1) ◽

pp. 50-62 ◽

Cited By ~ 17

Author(s):

Rashmi N. Kumar ◽

Ji Hee Ha ◽

Rangasudhagar Radhakrishnan ◽

Danny N. Dhanasekaran

Keyword(s):

Growth Factor ◽

Cell Growth ◽

Signaling Pathway ◽

Growth Factor Receptor ◽

Platelet Derived Growth Factor ◽

Dominant Negative Mutant ◽

Dependent Manner ◽

3T3 Cells ◽

Nih 3T3 ◽

Nih 3T3 Cells

ABSTRACT The GTPase-deficient, activated mutant of Gα12 (Gα12Q229L, or Gα12QL) induces neoplastic growth and oncogenic transformation of NIH 3T3 cells. Using microarray analysis, we have previously identified a role for platelet-derived growth factor receptor α (PDGFRα) in Gα12-mediated cell growth (R. N. Kumar et al., Cell Biochem. Biophys. 41:63-73, 2004). In the present study, we report that Gα12QL stimulates the functional expression of PDGFRα and demonstrate that the expression of PDGFRα by Gα12QL is dependent on the small GTPase Rho. Our results indicate that it is cell type independent as the transient expression of Gα12QL or the activation of Gα12-coupled receptors stimulates the expression of PDGFRα in NIH 3T3 as well as in human astrocytoma 1321N1 cells. Furthermore, we demonstrate the presence of an autocrine loop involving PDGF-A and PDGFRα in Gα12QL-transformed cells. Analysis of the functional consequences of the Gα12-PDGFRα signaling axis indicates that Gα12 stimulates the phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway through PDGFR. In addition, we show that Gα12QL stimulates the phosphorylation of forkhead transcription factor FKHRL1 via AKT in a PDGFRα- and PI3K-dependent manner. Since AKT promotes cell growth by blocking the transcription of antiproliferative genes through the inhibitory phosphorylation of forkhead transcription factors, our results describe for the first time a PDGFRα-dependent signaling pathway involving PI3K-AKT-FKHRL1, regulated by Gα12QL in promoting cell growth. Consistent with this view, we demonstrate that the expression of a dominant negative mutant of PDGFRα attenuated Gα12-mediated neoplastic transformation of NIH 3T3 cells.

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Expression of a peptide inhibitor of protein phosphatase 1 increases phosphorylation and activity of CREB in NIH 3T3 fibroblasts.

Molecular and Cellular Biology ◽

10.1128/mcb.14.7.4398 ◽

1994 ◽

Vol 14 (7) ◽

pp. 4398-4407 ◽

Cited By ~ 85

Author(s):

A S Alberts ◽

M Montminy ◽

S Shenolikar ◽

J R Feramisco

Keyword(s):

Transcriptional Activity ◽

Expression Vector ◽

Active Form ◽

Simian Virus 40 ◽

T Antigen ◽

3T3 Cells ◽

Phosphorylation State ◽

Phosphorylated Creb ◽

Nih 3T3 ◽

Nih 3T3 Cells

We have examined the activity and phosphorylation state of the cyclic AMP (cAMP) response element binding factor (CREB) in intact NIH 3T3 cells following microinjection of expression plasmids encoding regulatory proteins of type 1 (PP1) and 2A (PP2A) serine/threonine-specific protein phosphatases. Changes in CREB phosphorylation in the injected cells were monitored by indirect immunofluorescence using an affinity-purified antiserum (Ab5322) which specifically recognizes CREB phosphorylated at Ser-133, and changes in transcriptional activity of CREB were monitored by expression of a reporter gene regulated by cAMP. cAMP-stimulated phosphorylation in NIH 3T3 cells is normally transient, and as expected, after stimulation of cells with cell-permeable cAMP analogs, the level of phosphorylated CREB was found to initially increase and then return to a basal level within 4 h. Microinjection of an expression vector encoding a constitutively active form of inhibitor 1 (I-1), a PP1-specific inhibitor, by itself resulted in an apparent increase in phosphorylated CREB in unstimulated cells. Moreover, injection of the I-1 vector resulted in the prolonged appearance of phosphorylated CREB in cells after cAMP stimulation. In contrast, injection of a plasmid encoding simian virus 40 small t antigen, which interacts with PP2A to inhibit its activity towards several phosphoprotein substrates, had no effect on the phosphorylation state of CREB in stimulated or unstimulated NIH 3T3 cells. Consistent with these results, injection of the I-1 expression vector activated expression from a coinjected CRE-lacZ reporter plasmid, indicating that the increased phosphorylation of CREB also activated its transcriptional activity. These results provide further evidence for a role of a PP1 as the primary protein (Ser/Thr) phosphatase regulating the dephosphorylation of Ser-133 and thereby limiting the transcriptional activity of CREB.

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Stimulation of cell growth and proliferation in NIH-3T3 cells by onion and garlic oils

Cell Biology and Toxicology ◽

10.1007/bf00121852 ◽

1986 ◽

Vol 2 (3) ◽

pp. 369-378 ◽

Cited By ~ 5

Author(s):

Judith T. Zelikoff ◽

Norman M. Atkins ◽

Sidney Belman

Keyword(s):

Cell Growth ◽

3T3 Cells ◽

Cell Growth And Proliferation ◽

Nih 3T3 ◽

Stimulation Of ◽

Nih 3T3 Cells

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Cyclic AMP Blocks Cell Growth through Raf-1-Dependent and Raf-1-Independent Mechanisms

Molecular and Cellular Biology ◽

10.1128/mcb.22.11.3717-3728.2002 ◽

2002 ◽

Vol 22 (11) ◽

pp. 3717-3728 ◽

Cited By ~ 55

Author(s):

Nicolas Dumaz ◽

Yvonne Light ◽

Richard Marais

Keyword(s):

Protein Kinase ◽

Cell Growth ◽

Cyclic Amp ◽

3T3 Cells ◽

Extracellular Signal ◽

Nih 3T3 ◽

Nih 3T3 Cells

ABSTRACT It is widely accepted that cyclic AMP (cAMP) can block cell growth by phosphorylating Raf-1 on serine 43 and inhibiting signaling to extracellular signal-regulated protein kinase. We show that the suppression of Raf-1 by cAMP is considerably more complex than previously reported. When cellular cAMP is elevated, Raf-1 is phosphorylated on three residues (S43, S233, and S259), which work independently to block Raf-1. Both Ras-dependent and Ras-independent processes are disrupted. However, when cAMP-insensitive versions of Raf-1 are expressed in NIH 3T3 cells, their growth is still strongly suppressed when cAMP is elevated. Thus, although Raf-1 appears to be an important cAMP target, other pathways are also targeted by cAMP, providing alternative mechanisms that lead to suppression of cell growth.

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Retinoids enhance lectin binding to gp130, a glycoprotein of NIH-3T3 cells: Correlation with cell growth and adhesion

Experimental Cell Research ◽

10.1016/0014-4827(91)90053-w ◽

1991 ◽

Vol 192 (2) ◽

pp. 366-372 ◽

Cited By ~ 9

Author(s):

Decheng Cai ◽

Mukta M. Webber ◽

Luigi M. De Luca

Keyword(s):

Cell Growth ◽

Lectin Binding ◽

3T3 Cells ◽

Nih 3T3 ◽

Nih 3T3 Cells

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The Serine/Threonine Kinase Pim-2 Is a Novel Anti-Apoptotic Mediator in Myeloma Cells.

Blood ◽

10.1182/blood.v110.11.243.243 ◽

2007 ◽

Vol 110 (11) ◽

pp. 243-243

Author(s):

Jin Asano ◽

Masahiro Abe ◽

Shiro Fujii ◽

Osamu Tanaka ◽

Ai Mihara ◽

...

Keyword(s):

Bone Marrow ◽

Cell Growth ◽

Stromal Cells ◽

Osteoblast Differentiation ◽

Family Members ◽

Bone Marrow Microenvironment ◽

Serine Threonine Kinase ◽

Growth And Survival ◽

Threonine Kinase ◽

Cell Growth And Survival

Abstract Myeloma (MM) cells stimulate bone resorption by enhancing osteoclast (OC) formation and suppress bone formation by inhibiting osteoblast differentiation, leading to destructive bone lesions. In these lesions, OCs and stromal cells with defective osteoblast differentiation create a microenvironment suitable for myeloma cell growth and survival (a MM niche) to protect MM cells from various apoptotic insults. IL-6 and the TNF family members BAFF and APRIL have been demonstrated to be among predominant anti-apoptotic cytokines for MM cells elaborated by the bone marrow microenvironment in MM. The serine/threonine kinase Pim-2 is a novel apoptotic inhibitor which is transcriptionally up-regulated to promote survival of hematopoietic cells in response to environmental growth factors and cytokines. Up-regulation of Pim-2 expression has also been observed in various malignancies including MM. However, the roles for Pim-2 in growth and survival of MM cells are largely unknown. In the present study we therefore investigated the regulatory mechanism for Pim-2 expression in MM cells and the impact of Pim-2 on MM cell growth and survival with special reference to the interaction between MM cells and bone marrow components. Pim-2 protein is constitutively overexpressed in the absence of IL-6 in IL-6-dependent INA-6 as well as IL-6-independent RPMI8226 and U266 MM cell lines. Addition of IL-6, BAFF and TNFalpha up-regulated Pim-2 protein expression in INA-6 and RPMI8226 cells. A JAK/STAT3 inhibitor, cucurbitacin I, suppresses Pim-2 expression induced by IL-6, indicating Pim-2 as a downstream target of a JAK/STAT3 pathway. Stromal cells and OCs are regarded as a predominant cell type in MM bone marrow microenvironment to produce IL-6 and the TNF family members BAFF and APRIL, respectively. Co-cultures with stromal cells as well as OCs enhanced Pim-2 expression in INA-6 cells, suggesting up-regulation of Pim-2 in MM cells by surrounding cells in the bone marrow. In order to clarify the roles for Pim-2 in growth and survival of MM cells we next looked at the effects of Pim-2 siRNA. Suppression of Pim-2 expression by Pim-2 siRNA partly reduced the proliferation of INA-6 cells stimulated by IL-6 as well as the co-cultures with stromal cells or OCs. Pim-2 silencing also enhanced the cytotoxic effects of dexamethason on MM cells. Interestingly, further addition of rapamycin, an inhibitor of mammalian target of rapamycin (mTOR), induces cell death in concert with Pim-2 silencing in INA-6 cells, suggesting a cooperative roles for PI3K/Akt and Pim-2-mediated pathways in growth and survival of MM cells. Furthermore, Pim-2 silencing induced the cleavage of caspase9 but not caspase8; enforced expression of Pim-2 phosphorylated the BH3 only protein Bad; Pim-2 silencing suppressed phosphorylation of Bad by IL-6. Thus, Pim-2 appears to activate the intrinsic pathway of apoptotic machinery involving Bad phosphorylation. Taken together, our results suggest that Pim-2 is an important prosurvival mediator in MM cells, and that up-regulation of its expression in MM cells by bone marrow components may at least in part contribute to resistance to spontaneous and drug-induced apoptosis in MM cells. Therefore, Pim-2 may become a target for novel therapeutic strategies against MM.

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Expression of a peptide inhibitor of protein phosphatase 1 increases phosphorylation and activity of CREB in NIH 3T3 fibroblasts

Molecular and Cellular Biology ◽

10.1128/mcb.14.7.4398-4407.1994 ◽

1994 ◽

Vol 14 (7) ◽

pp. 4398-4407

Author(s):

A S Alberts ◽

M Montminy ◽

S Shenolikar ◽

J R Feramisco

Keyword(s):

Transcriptional Activity ◽

Expression Vector ◽

Active Form ◽

Simian Virus 40 ◽

T Antigen ◽

3T3 Cells ◽

Phosphorylation State ◽

Phosphorylated Creb ◽

Nih 3T3 ◽

Nih 3T3 Cells

We have examined the activity and phosphorylation state of the cyclic AMP (cAMP) response element binding factor (CREB) in intact NIH 3T3 cells following microinjection of expression plasmids encoding regulatory proteins of type 1 (PP1) and 2A (PP2A) serine/threonine-specific protein phosphatases. Changes in CREB phosphorylation in the injected cells were monitored by indirect immunofluorescence using an affinity-purified antiserum (Ab5322) which specifically recognizes CREB phosphorylated at Ser-133, and changes in transcriptional activity of CREB were monitored by expression of a reporter gene regulated by cAMP. cAMP-stimulated phosphorylation in NIH 3T3 cells is normally transient, and as expected, after stimulation of cells with cell-permeable cAMP analogs, the level of phosphorylated CREB was found to initially increase and then return to a basal level within 4 h. Microinjection of an expression vector encoding a constitutively active form of inhibitor 1 (I-1), a PP1-specific inhibitor, by itself resulted in an apparent increase in phosphorylated CREB in unstimulated cells. Moreover, injection of the I-1 vector resulted in the prolonged appearance of phosphorylated CREB in cells after cAMP stimulation. In contrast, injection of a plasmid encoding simian virus 40 small t antigen, which interacts with PP2A to inhibit its activity towards several phosphoprotein substrates, had no effect on the phosphorylation state of CREB in stimulated or unstimulated NIH 3T3 cells. Consistent with these results, injection of the I-1 expression vector activated expression from a coinjected CRE-lacZ reporter plasmid, indicating that the increased phosphorylation of CREB also activated its transcriptional activity. These results provide further evidence for a role of a PP1 as the primary protein (Ser/Thr) phosphatase regulating the dephosphorylation of Ser-133 and thereby limiting the transcriptional activity of CREB.

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Multiple Myeloma Cells Survival and Proliferation Rely on High Levels and Activity of the Serine-Threonine Kinase CK2.

Blood ◽

10.1182/blood.v104.11.643.643 ◽

2004 ◽

Vol 104 (11) ◽

pp. 643-643 ◽

Cited By ~ 1

Author(s):

Francesco A. Piazza ◽

Maria Ruzzene ◽

Giovanni Di Maira ◽

Enrico Brunetta ◽

Luca Bonanni ◽

...

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Transcriptional Activity ◽

Kinase Activity ◽

Serine Threonine Kinase ◽

Cycle Progression ◽

Threonine Kinase ◽

Protein Levels ◽

Tnf Α ◽

Ck2 Inhibitors

Abstract Survival and proliferation of Multiple Myeloma plasma cells (MMPCs) depend on the activation of signaling pathways through the interaction with the surrounding bone marrow microenvironment. CK2 is a ubiquitous cellular serine-threonine kinase, whose involvement in oncogenic transformation, apoptosis and cell cycle progression has recently become matter of intense research. Due to its connection with signaling molecules pivotal for plasma cell (PCs) survival, such as those implicated in the TNF-α/NF-κB, IGF1/PI3K/AKT and Wnt/β-catenin pathways, CK2 is likely to play a central role in MM biology. We investigated CK2 function in MMPCs survival and cell cycle progression, in the modulation of the sensitivity to chemotherapeutics and in the regulation of the I-κB/NF-κB dependent pathway. We first analysed the CK2 protein levels and specific kinase activity in MMPCs. Different cell lines and highly purified CD138+ PCs from 5 patients were used. We observed higher protein levels of the CK2 catalytic subunit αin the neoplastic MMPCs than in controls (resting peripheral blood and splenic B lymphocytes). Moreover, also the total CK2-dependent kinase activity was found significantly increased in MMPCs. We also assessed the levels and pattern of total protein phosphorylation by radioactive phosphate incorporation assay. We found that MMPCs share a similar pattern of phoshorylated proteins. The degree of phosphorylation of some of these proteins was significantly reduced in the presence of specific CK2 inhibitors. Next, using a panel of highly specific CK2 inhibitors, we studied the effects of hampering CK2 function in MMPCs. A dose-dependent cytotoxic effect was observed after the treatment with such compounds that was associated with the activation of both the extrinsic and intrinsic caspase-dependent pathways, the release from mitochondria of cytochrome c and smac/diablo and cell cycle arrest in G2-M. A possible role for CK2 inhibition in sensitising MMPCs to melphalan-induced apoptosis was also investigated. Indeed, CK2 blockade lowered the threshold of sensitivity of MMPCs to the cytotoxic effect of melphalan. We then looked at the consequences of CK2 blockade on the NF-κB dependent signaling cascade. Basal and TNF-α-dependent I-κB-αdegradation, as well as NF-κB transcriptional activity upon TNF-αstimulation, were partially impaired by CK2 blockade in MMPCs. Finally, we detected association between the endogenous αcatalytic subunit of CK2 and the NF-κB p50/p105 member by confocal microscopy and co-immunoprecipitation. Altogether, our data suggest a pivotal role for CK2 in controlling survival, proliferation and sensitivity to chemotherapeutics of MMPCs and implicate this kinase in the regulation of the NF-κB pathway in MM through the modulation of I-κB protein levels and NF-κB transcriptional activity. This latter effect is possibly exerted through physical association of CK2 with NF-κB transcription factors. Our findings also suggest that CK2 inhibition could be exploited as a novel therapeutic approach for MM.

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