c‐Jun kinase mediates expression of VEGF induced at transcriptional level by Rac1 and Cdc42Hs but not by RhoA

Saníger, M. Luisa; Oya, Ricardo; Macías, David; Domínguez, Jorge N.; Aránega, Amelia; Luque, Francisco

doi:10.1002/jcb.20801

Cited by 5 publications

(6 citation statements)

References 38 publications

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“…Rac1 and Cdc42 have also been implicated in hypoxic-induction of VEGF expression through regulation of p53 and VHL protein levels, as well as HIF1, and JNK activation [20,21,34]. In agreement with these studies, we find that both Rac1 and Cdc42 play a role in hypoxia-induced VEGF expression in HRas V12 -transformed fibroblasts.…”

Section: Discussionsupporting

confidence: 90%

“…However, recent data from our laboratory indicate that reduction of Sp1 expression in HRas V12 -transformed human fibroblasts does not affect expression of VEGF [35]. Saniger et al [34] recently reported that activation of either Rac1 or Cdc42 can induce transcription of VEGF through activation of JNK, which results in increased transcription of the VEGF gene product. Although multiple Rac1 and Cdc42 independent pathways affecting HIF1 transcriptional networks exist [36], it is possible that in HRas V12 -transformed human fibroblasts, Rac1 may play a partial role in stabilizing HIF1 and/or activating JNK, which then modulates secretion of VEGF protein.…”

Section: Discussionmentioning

confidence: 96%

“…Therefore, it is tempting to postulate that in this instance, Cdc42 mediates one of multiple signalling pathways downstream of Rac1, that when inactivated, partially disrupts VEGF secretion. Ras-induced VEGF expression is regulated by multiple mechanisms, including increased transcription, translation and mRNA stabilization [20,27,32-34]. For example, it has been shown that activation of ERK1/2, through the Raf-mediated Ras pathway, increases the activity of HIF1 and Sp1 transcription factors [20,33].…”

Section: Discussionmentioning

confidence: 99%

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Rac1 and Cdc42 are regulators of HRasV12-transformation and angiogenic factors in human fibroblasts

et al. 2010

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BackgroundThe activities of Rac1 and Cdc42 are essential for HRas-induced transformation of rodent fibroblasts. What is more, expression of constitutively activated mutants of Rac1 and/or Cdc42 is sufficient for their malignant transformation. The role for these two Rho GTPases in HRas-mediated transformation of human fibroblasts has not been studied. Here we evaluated the contribution of Rac1 and Cdc42 to maintaining HRas-induced transformation of human fibroblasts, and determined the ability of constitutively activated mutants of Rac1 or Cdc42 to induce malignant transformation of a human fibroblast cell strain.MethodsUnder the control of a tetracycline regulatable promoter, dominant negative mutants of Rac1 and Cdc42 were expressed in a human HRas-transformed, tumor derived fibroblast cell line. These cells were used to determine the roles of Rac1 and/or Cdc42 proteins in maintaining HRas-induced transformed phenotypes. Similarly, constitutively active mutants were expressed in a non-transformed human fibroblast cell strain to evaluate their potential to induce malignant transformation. Affymetrix GeneChip arrays were used for transcriptome analyses, and observed expression differences were subsequently validated using protein assays.ResultsExpression of dominant negative Rac1 and/or Cdc42 significantly altered transformed phenotypes of HRas malignantly transformed human fibroblasts. In contrast, expression of constitutively active mutants of Rac1 or Cdc42 was not sufficient to induce malignant transformation. Microarray analysis revealed that the expression of 29 genes was dependent on Rac1 and Cdc42, many of which are known to play a role in cancer. The dependence of two such genes, uPA and VEGF was further validated in both normoxic and hypoxic conditions.Conclusion(s)The results presented here indicate that expression of both Rac1 and Cdc42 is necessary for maintaining several transformed phenotypes in oncogenic HRas transformed human cells, including their ability to form tumors in athymic mice. Our data also indicate that expression of either activated Rac1 or Cdc42 alone is not sufficient for malignant transformation of human fibroblasts, although each is required for specific transformed phenotypes. Furthermore, our study elucidates that the expression of several highly significant cancer related genes require the activities of Rac1 and/or Cdc42 which may also play a critical role in cellular transformation.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

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Rac1 and Cdc42 are regulators of HRasV12-transformation and angiogenic factors in human fibroblasts

et al. 2010

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“…However, down-regulation of Spry2 in PH3MT cells enhanced stress fiber formation, a process that is consistent with loss of Rac1 activity (data not shown). In addition, Rac1 contributes to vascular endothelial growth factor and urokinase-type plasminogen activator secretion in PH3MT cells, 4 as well as in other Ras-transformed cells (46,47). Down-regulation of Spry2 in PH3MT cells resulted in a decrease in the amount of vascular endothelial growth factor and urokinase-type plasminogen activator secreted by these cells (data not shown).…”

Section: Discussionmentioning

confidence: 92%

Sprouty 2 Regulates DNA Damage-induced Apoptosis in Ras-transformed Human Fibroblasts

Lito¹,

Mets

Appledorn

et al. 2009

Journal of Biological Chemistry

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We have reported that expression of Sprouty 2 (Spry2) is necessary for tumor formation by HRas V12 -transformed fibroblasts. We now report on the role of Spry2 in the inhibition of UV 254 nm radiation-induced apoptosis in HRas V12 -transformed human fibroblasts. Silencing Spry2 in this context resulted in increased apoptosis, associated with decreased Akt activation and decreased phosphorylation of HDM2 at Ser-166, which has been shown to stabilize HDM2. As a consequence, when cells with silenced Spry2 were UV-irradiated, they exhibited diminished levels of HDM2 and elevated levels of p53. In agreement with these findings, overexpression of Spry2 in the parental non-transformed fibroblasts led to increased Akt activation and to the stabilization of HDM2. It also led to diminished expression of p53 and decreased apoptosis following UV irradiation. Silencing Spry2 in HRas-transformed cells decreased Rac1 activation, but independent expression of Spry2 in the non-transformed parental cells had no effect on Rac1, suggesting a specific involvement in the activation of Rac1 by Ras. Silencing Spry2 in HRas V12 -transformed cells resulted in diminished interaction between HRas and Tiam1, a Rac1-specific nucleotide exchange factor. Expression of constitutively active Rac1 in cells with silenced Spry2 partly reversed the effect of Spry2 down-regulation. Furthermore, loss of Spry2 expression in HRas V12 -transformed cells augmented the cytotoxicity of the DNA-damaging, chemotherapeutic agent cisplatin, a process that was also reversed by active Rac1. Together, these data show that Spry2 inhibits apoptosis in response to DNA damage by regulating Akt, HDM2, and p53, by a process mediated partly by Rac1.Ras is an important regulator of cellular proliferation and survival (1). In appropriate cellular contexts, oncogenic activation of Ras inhibits apoptosis in response to DNA damage caused by UV irradiation or by chemotherapeutic agents, such as cisplatin (2, 3). This effect is mediated by phosphatidyl-inositol-3-kinase (PI3K) 3 and Rac1 (4). PI3K activates several effector proteins, including the serine/threonine kinase Akt, which controls survival proteins, such as the human homolog of the murine double mutant 2 (HDM2) (5-7). Rac1, a member of the Rho family of GTPases, plays an important role in the transformation of fibroblasts by Ras. Although Rac1 is mainly involved in the regulation of migration, adhesion, and cell division, a number of studies also implicate Rac1 in the regulation of apoptosis (8, 9).Apoptosis in response to DNA damage is under the immediate control of HDM2 and p53 (10). Under physiological conditions, transcription factor p53 is maintained at a low level by the ubiquitin-protein isopeptide ligase (E3) HDM2, which ubiquitinates p53 and targets it for proteasomal degradation. p53 is activated in response to cellular stresses that induce DNA damage. Then, the ubiquitination of p53 by HDM2 is abolished, and p53 translocates to the nucleus, where it induces the transcriptional activation of genes that media...

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“…Cdc42 activation has been reported in response to VEGF stimulation (61) and is activated during endothelial cell haptotaxis on type I collagen (47). Interestingly, activation of Cdc42 can induce VEGF promoter activity via a c-Jun-dependent mechanism (44), and we have shown previously that c-Jun is necessary for MMP-2 mRNA expression following VEGF stimulation (24). Together, these results suggest that VEGF can induce both rapid and sustained production activation of MMP-2 through upregulation of Cdc42 activity.…”

Section: Discussionmentioning

confidence: 96%

Cdc42 and RhoA have opposing roles in regulating membrane type 1-matrix metalloproteinase localization and matrix metalloproteinase-2 activation

Ispanovic¹,

Serio²,

Haas³

2008

American Journal of Physiology-Cell Physiology

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Proteolysis of the basement membrane and interstitial matrix occurs early in the angiogenic process and requires matrix metalloproteinase (MMP) activity. Skeletal muscle microvascular endothelial cells exhibit robust actin stress fibers, low levels of membrane type 1 (MT1)-MMP expression, and minimal MMP-2 activation. Depolymerization of the actin cytoskeleton increases MT1-MMP expression and MMP-2 activation. Rho family GTPases are regulators of actin cytoskeleton dynamics, and their activity can be modulated in response to angiogenic stimuli such as vascular endothelial growth factor (VEGF). Therefore, we investigated their roles in MMP-2 and MT1-MMP production. Endothelial cells treated with H1152 [an inhibitor of Rho kinase (ROCK)] induced stress fiber depolymerization and an increase in cortical actin. Both MMP-2 and MT1-MMP mRNA increased, which translated into greater MMP-2 protein production and activation. ROCK inhibition rapidly increased cell surface localization of MT1-MMP and increased PI3K activity, which was required for MMP-2 activation. Constitutively active Cdc42 increased cortical actin polymerization, phosphatidylinositol 3-kinase activity, MT1-MMP cell surface localization, and MMP-2 activation similarly to inhibition of ROCK. Activation of Cdc42 was sufficient to decrease RhoA activity. Capillary sprout formation in a three-dimensional collagen matrix was increased in cultures treated with RhoAN19 or Cdc42QL and, conversely, decreased in cultures treated with dominant negative Cdc42N17. VEGF stimulation also induced activation of Cdc42 while inhibiting RhoA activity. Furthermore, VEGF-dependent activation of MMP-2 was reduced by inhibition of Cdc42. These results suggest that Cdc42 and RhoA have opposing roles in regulating cell surface localization of MT1-MMP and MMP-2 activation.

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c‐Jun kinase mediates expression of VEGF induced at transcriptional level by Rac1 and Cdc42Hs but not by RhoA

Cited by 5 publications

References 38 publications

Rac1 and Cdc42 are regulators of HRasV12-transformation and angiogenic factors in human fibroblasts

Rac1 and Cdc42 are regulators of HRasV12-transformation and angiogenic factors in human fibroblasts

Sprouty 2 Regulates DNA Damage-induced Apoptosis in Ras-transformed Human Fibroblasts

Cdc42 and RhoA have opposing roles in regulating membrane type 1-matrix metalloproteinase localization and matrix metalloproteinase-2 activation

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