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Kirchenwitz M, Halfen J, von Peinen K, Prettin S, Kollasser J, Zur Lage S, Blankenfeldt W, Brakebusch C, Rottner K, Steffen A, Stradal TEB. RhoB promotes Salmonella survival by regulating autophagy. Eur J Cell Biol 2023; 102:151358. [PMID: 37703749 DOI: 10.1016/j.ejcb.2023.151358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 07/05/2023] [Accepted: 08/29/2023] [Indexed: 09/15/2023] Open
Abstract
Salmonella enterica serovar Typhimurium manipulates cellular Rho GTPases for host cell invasion by effector protein translocation via the Type III Secretion System (T3SS). The two Guanine nucleotide exchange (GEF) mimicking factors SopE and -E2 and the inositol phosphate phosphatase (PiPase) SopB activate the Rho GTPases Rac1, Cdc42 and RhoA, thereby mediating bacterial invasion. S. Typhimurium lacking these three effector proteins are largely invasion-defective. Type III secretion is crucial for both early and later phases of the intracellular life of S. Typhimurium. Here we investigated whether and how the small GTPase RhoB, known to localize on endomembrane vesicles and at the invasion site of S. Typhimurium, contributes to bacterial invasion and to subsequent steps relevant for S. Typhimurium lifestyle. We show that RhoB is significantly upregulated within hours of Salmonella infection. This effect depends on the presence of the bacterial effector SopB, but does not require its phosphatase activity. Our data reveal that SopB and RhoB bind to each other, and that RhoB localizes on early phagosomes of intracellular S. Typhimurium. Whereas both SopB and RhoB promote intracellular survival of Salmonella, RhoB is specifically required for Salmonella-induced upregulation of autophagy. Finally, in the absence of RhoB, vacuolar escape and cytosolic hyper-replication of S. Typhimurium is diminished. Our findings thus uncover a role for RhoB in Salmonella-induced autophagy, which supports intracellular survival of the bacterium and is promoted through a positive feedback loop by the Salmonella effector SopB.
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Affiliation(s)
- Marco Kirchenwitz
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Jessica Halfen
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Kristin von Peinen
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Silvia Prettin
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Jana Kollasser
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Susanne Zur Lage
- Department Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Wulf Blankenfeldt
- Department Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Cord Brakebusch
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
| | - Klemens Rottner
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany; Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Anika Steffen
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Theresia E B Stradal
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
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2
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Ju JA, Gilkes DM. RhoB: Team Oncogene or Team Tumor Suppressor? Genes (Basel) 2018; 9:E67. [PMID: 29385717 PMCID: PMC5852563 DOI: 10.3390/genes9020067] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 01/21/2018] [Accepted: 01/24/2018] [Indexed: 12/31/2022] Open
Abstract
Although Rho GTPases RhoA, RhoB, and RhoC share more than 85% amino acid sequence identity, they play very distinct roles in tumor progression. RhoA and RhoC have been suggested in many studies to contribute positively to tumor development, but the role of RhoB in cancer remains elusive. RhoB contains a unique C-terminal region that undergoes specific post-translational modifications affecting its localization and function. In contrast to RhoA and RhoC, RhoB not only localizes at the plasma membrane, but also on endosomes, multivesicular bodies and has even been identified in the nucleus. These unique features are what contribute to the diversity and potentially opposing functions of RhoB in the tumor microenvironment. Here, we discuss the dualistic role that RhoB plays as both an oncogene and tumor suppressor in the context of cancer development and progression.
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Affiliation(s)
- Julia A Ju
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Daniele M Gilkes
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
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3
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Arsic N, Ho-Pun-Cheung A, Evelyne C, Assenat E, Jarlier M, Anguille C, Colard M, Pezet M, Roux P, Gadea G. The p53 isoform delta133p53ß regulates cancer cell apoptosis in a RhoB-dependent manner. PLoS One 2017; 12:e0172125. [PMID: 28212429 PMCID: PMC5315499 DOI: 10.1371/journal.pone.0172125] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 01/31/2017] [Indexed: 11/18/2022] Open
Abstract
The TP53 gene plays essential roles in cancer. Conventionally, wild type (WT) p53 is thought to prevent cancer development and metastasis formation, while mutant p53 has transforming abilities. However, clinical studies failed to establish p53 mutation status as an unequivocal predictive or prognostic factor of cancer progression. The recent discovery of p53 isoforms that can differentially regulate cell cycle arrest and apoptosis suggests that their expression, rather than p53 mutations, could be a more clinically relevant biomarker in patients with cancer. In this study, we show that the p53 isoform delta133p53ß is involved in regulating the apoptotic response in colorectal cancer cell lines. We first demonstrate delta133p53ß association with the small GTPase RhoB, a well-described anti-apoptotic protein. We then show that, by inhibiting RhoB activity, delta133p53ß protects cells from camptothecin-induced apoptosis. Moreover, we found that high delta133p53 mRNA expression levels are correlated with higher risk of recurrence in a series of patients with locally advanced rectal cancer (n = 36). Our findings describe how a WT TP53 isoform can act as an oncogene and add a new layer to the already complex p53 signaling network.
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Affiliation(s)
- Nikola Arsic
- CNRS, Centre de Recherche en Biologie cellulaire de Montpellier, Montpellier, France
- Université Montpellier, Montpellier, France
| | | | - Crapez Evelyne
- Translational Research Unit, Institut du Cancer de Montpellier, Montpellier, France
| | - Eric Assenat
- Department of Gastroenterology, Institut du Cancer de Montpellier, Montpellier, France
| | - Marta Jarlier
- Biostatistics Department, Institut du Cancer de Montpellier, Montpellier, France
| | - Christelle Anguille
- CNRS, Centre de Recherche en Biologie cellulaire de Montpellier, Montpellier, France
- Université Montpellier, Montpellier, France
| | - Manon Colard
- CNRS, Centre de Recherche en Biologie cellulaire de Montpellier, Montpellier, France
- Université Montpellier, Montpellier, France
| | - Mikaël Pezet
- CNRS, Centre de Recherche en Biologie cellulaire de Montpellier, Montpellier, France
- Université Montpellier, Montpellier, France
| | - Pierre Roux
- CNRS, Centre de Recherche en Biologie cellulaire de Montpellier, Montpellier, France
- Université Montpellier, Montpellier, France
- INSERM, Montpellier, France
| | - Gilles Gadea
- Université de la Réunion, Unité Mixte 134 Processus Infectieux en Milieu Insulaire Tropical, INSERM Unité 1187, CNRS Unité Mixte de Recherche 9192, IRD Unité Mixte de Recherche 249. Plateforme Technologique CYROI, Sainte Clotilde, France
- * E-mail:
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4
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Ferreira ACDS, de-Freitas-Junior JCM, Morgado-Díaz JA, Ridley AJ, Klumb CE. Dual inhibition of histone deacetylases and phosphoinositide 3-kinases: effects on Burkitt lymphoma cell growth and migration. J Leukoc Biol 2016; 99:569-78. [PMID: 26561567 DOI: 10.1189/jlb.2a0415-162r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 10/19/2015] [Indexed: 02/04/2023] Open
Abstract
Burkitt lymphoma is a highly aggressive non-Hodgkin lymphoma that is characterized by MYC deregulation. Recently, the PI3K pathway has emerged as a cooperative prosurvival mechanism in Burkitt lymphoma. Despite the highly successful results of treatment that use high-dose chemotherapy regimens in pediatric Burkitt lymphoma patients, the survival rate of pediatric patients with progressive or recurrent disease is low. PI3Ks are also known to regulate cell migration, and abnormal cell migration may contribute to cancer progression and dissemination in Burkitt lymphoma. Little is known about Burkitt lymphoma cell migration, but the cooperation between MYC and PI3K in Burkitt lymphoma pathogenesis suggests that a drug combination could be used to target the different steps involved in Burkitt lymphoma cell dissemination and disease progression. The aim of this study was to investigate the effects of the histone deacetylase inhibitor suberoylanilide hydroxamic acid combined with the PI3K inhibitor LY294002 on Burkitt lymphoma cell growth and migration. The combination enhanced the cell growth inhibition and cell-cycle arrest induced by the PI3K inhibitor or histone deacetylase inhibitor individually. Moreover, histone deacetylase inhibitor/PI3K inhibitor cotreatment suppressed Burkitt lymphoma cell migration and decreased cell polarization, Akt and ERK1/2 phosphorylation, and leads to RhoB induction. In summary, the histone deacetylase inhibitor/PI3Ki combination inhibits cell proliferation and migration via alterations in PI3K signaling and histone deacetylase activity, which is involved in the acetylation of α-tubulin and the regulation of RhoB expression.
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Affiliation(s)
- Ana Carolina dos Santos Ferreira
- *Programa de Pesquisa em Hemato-Oncologia Molecular, Laboratório de Hemato-oncologia Celular e Molecular, and Programa de Biologia Celular, Laboratório de Biologia Estrutural-Instituto Nacional de Câncer, Rio de Janeiro, Brazil; and Randall Division of Cell and Molecular Biophysics, King's College London, United Kingdom
| | - Julio Cesar Madureira de-Freitas-Junior
- *Programa de Pesquisa em Hemato-Oncologia Molecular, Laboratório de Hemato-oncologia Celular e Molecular, and Programa de Biologia Celular, Laboratório de Biologia Estrutural-Instituto Nacional de Câncer, Rio de Janeiro, Brazil; and Randall Division of Cell and Molecular Biophysics, King's College London, United Kingdom
| | - Jose Andres Morgado-Díaz
- *Programa de Pesquisa em Hemato-Oncologia Molecular, Laboratório de Hemato-oncologia Celular e Molecular, and Programa de Biologia Celular, Laboratório de Biologia Estrutural-Instituto Nacional de Câncer, Rio de Janeiro, Brazil; and Randall Division of Cell and Molecular Biophysics, King's College London, United Kingdom
| | - Anne J Ridley
- *Programa de Pesquisa em Hemato-Oncologia Molecular, Laboratório de Hemato-oncologia Celular e Molecular, and Programa de Biologia Celular, Laboratório de Biologia Estrutural-Instituto Nacional de Câncer, Rio de Janeiro, Brazil; and Randall Division of Cell and Molecular Biophysics, King's College London, United Kingdom
| | - Claudete Esteves Klumb
- *Programa de Pesquisa em Hemato-Oncologia Molecular, Laboratório de Hemato-oncologia Celular e Molecular, and Programa de Biologia Celular, Laboratório de Biologia Estrutural-Instituto Nacional de Câncer, Rio de Janeiro, Brazil; and Randall Division of Cell and Molecular Biophysics, King's College London, United Kingdom
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5
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Huang GX, Pan XY, Jin YD, Wang Y, Song XL, Wang CH, Li YD, Lu J. The mechanisms and significance of up-regulation of RhoB expression by hypoxia and glucocorticoid in rat lung and A549 cells. J Cell Mol Med 2016; 20:1276-86. [PMID: 26915688 PMCID: PMC4929294 DOI: 10.1111/jcmm.12809] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 01/14/2016] [Indexed: 12/31/2022] Open
Abstract
Small guanosine triphosphate (GTP)‐binding protein RhoB is an important stress sensor and contributes to the regulation of cytoskeletal organization, cell proliferation and survival. However, whether RhoB is involved in the hypoxic response and action of glucocorticoid (GC) is largely unknown. In this study, we investigated the effects of hypoxia or/and GC on the expression and activition of RhoB in the lung of rats and human A549 lung carcinoma cells, and further studied its mechanism and significance. We found that hypoxia and dexamethasone (Dex), a synethic GC, not only significantly increased the expression and activation of RhoB independently but also coregulated the expresion of RhoB in vitro and in vivo. Up‐regulation of RhoB by hypoxia was in part through stabilizing the RhoB mRNA and protein. Inhibiting hypoxia‐activated hypoxia‐inducible transcription factor‐1α (HIF‐1α), c‐Jun N‐terminal kinase (JNK) or extracellular signal‐regulated kinase (ERK) with their specific inhibitors significantly decreased hypoxia‐induced RhoB expression, indicating that HIF‐1α, JNK and ERK are involved in the up‐regulation of RhoB in hypoxia. Furthermore, we found that knockdown of RhoB expression by RhoB siRNA not only significantly reduced hypoxia‐enhanced cell migration and cell survival in hypoxia but also increased the sensitivity of cell to paclitaxel (PTX), a chemotherapeutic agent, and reduced Dex‐enhanced resistance to PTX‐chemotherapy in A549 cells. Taken together, the novel data revealed that hypoxia and Dex increased the expression and activation of RhoB, which is important for hypoxic adaptation and hypoxia‐accelerated progression of lung cancer cells. RhoB also enhanced the resistance of cell to PTX‐chemotherapy and mediated the pro‐survival effect of Dex.
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Affiliation(s)
- Gao-Xiang Huang
- Department of Pathophysiology, The Second Military Medical University, Shanghai, China
| | - Xiao-Yu Pan
- Department of Pathophysiology, The Second Military Medical University, Shanghai, China.,Department of Respiratory Medicine, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Yi-Duo Jin
- Department of Pathophysiology, The Second Military Medical University, Shanghai, China
| | - Yan Wang
- Department of Pathophysiology, The Second Military Medical University, Shanghai, China
| | - Xiao-Lian Song
- Department of Respiratory Medicine, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Chang-Hui Wang
- Department of Respiratory Medicine, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Yi-Dong Li
- Department of Pathophysiology, The Second Military Medical University, Shanghai, China
| | - Jian Lu
- Department of Pathophysiology, The Second Military Medical University, Shanghai, China
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6
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New synthetic aliphatic sulfonamido-quaternary ammonium salts as anticancer chemotherapeutic agents. Eur J Med Chem 2013; 69:670-7. [DOI: 10.1016/j.ejmech.2013.09.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/09/2013] [Accepted: 09/09/2013] [Indexed: 02/06/2023]
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7
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Kazerounian S, Gerald D, Huang M, Chin YR, Udayakumar D, Zheng N, O'Donnell RK, Perruzzi C, Mangiante L, Pourat J, Phung TL, Bravo-Nuevo A, Shechter S, McNamara S, Duhadaway JB, Kocher ON, Brown LF, Toker A, Prendergast GC, Benjamin LE. RhoB differentially controls Akt function in tumor cells and stromal endothelial cells during breast tumorigenesis. Cancer Res 2012; 73:50-61. [PMID: 23135917 DOI: 10.1158/0008-5472.can-11-3055] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tumors are composed of cancer cells but also a larger number of diverse stromal cells in the tumor microenvironment. Stromal cells provide essential supports to tumor pathophysiology but the distinct characteristics of their signaling networks are not usually considered in developing drugs to target tumors. This oversight potentially confounds proof-of-concept studies and increases drug development risks. Here, we show in established murine and human models of breast cancer how differential regulation of Akt by the small GTPase RhoB in cancer cells or stromal endothelial cells determines their dormancy versus outgrowth when angiogenesis becomes critical. In cancer cells in vitro or in vivo, RhoB functions as a tumor suppressor that restricts EGF receptor (EGFR) cell surface occupancy as well as Akt signaling. However, after activation of the angiogenic switch, RhoB functions as a tumor promoter by sustaining endothelial Akt signaling, growth, and survival of stromal endothelial cells that mediate tumor neoangiogenesis. Altogether, the positive impact of RhoB on angiogenesis and progression supercedes its negative impact in cancer cells themselves. Our findings elucidate the dominant positive role of RhoB in cancer. More generally, they illustrate how differential gene function effects on signaling pathways in the tumor stromal component can complicate the challenge of developing therapeutics to target cancer pathophysiology.
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Affiliation(s)
- Shiva Kazerounian
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
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8
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Structures, mechanisms and inhibitors of undecaprenyl diphosphate synthase: A cis-prenyltransferase for bacterial peptidoglycan biosynthesis. Bioorg Chem 2012; 43:51-7. [DOI: 10.1016/j.bioorg.2011.09.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/13/2011] [Accepted: 09/15/2011] [Indexed: 12/20/2022]
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9
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Chaterjee M, van Golen KL. Breast cancer stem cells survive periods of farnesyl-transferase inhibitor-induced dormancy by undergoing autophagy. BONE MARROW RESEARCH 2011; 2011:362938. [PMID: 22046561 PMCID: PMC3199942 DOI: 10.1155/2011/362938] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 05/18/2011] [Indexed: 01/16/2023]
Abstract
A cancer stem cell has been defined as a cell within a tumor that possesses the capacity to self-renew and to cause the heterogeneous lineages of cancer cells that comprise the tumor. These tumor-forming cells could hypothetically originate from stem, progenitor, or differentiated cells. Previously, we have shown that breast cancer cells with low metastatic potential can be induced into a reversible state of dormancy by farnesyl transferase inhibitors (FTIs). Dormancy was induced by changes in RhoA and RhoC GTPases. Specifically, RhoA was found to be hypoactivated while RhoC was hyperactivated. In the current study we demonstrate that these dormant cells also express certain known stem cell markers such as aldehyde dehydrogenase I (ALDHI) and cluster of differentiation 44 (CD44). We also show that autophagy markers Atg5, Atg12, and LC3-B are expressed in these dormant stem cell-like breast cancer cells. Inhibiting autophagy by inhibitor 3-methyladenine (3-MA) blocked the process of autophagy reversing the dormant phenotype. Further, we show that c-jun NH2 terminal kinase (JNK/SAPK) is upregulated in these dormant stem cell-like breast cancer cells and is responsible for increasing autophagy.
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Affiliation(s)
- Moumita Chaterjee
- The Laboratory of Cytoskeletal Physiology, Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
- The Center For Translational Cancer Research, University of Delaware, 320 Wolf Hall, Newark, DE 19716, USA
| | - Kenneth L. van Golen
- The Laboratory of Cytoskeletal Physiology, Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
- The Center For Translational Cancer Research, University of Delaware, 320 Wolf Hall, Newark, DE 19716, USA
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10
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Phosphorylation of RhoB by CK1 impedes actin stress fiber organization and epidermal growth factor receptor stabilization. Exp Cell Res 2008; 314:2811-21. [PMID: 18590726 DOI: 10.1016/j.yexcr.2008.06.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 06/10/2008] [Accepted: 06/11/2008] [Indexed: 11/21/2022]
Abstract
RhoB is a small GTPase implicated in cytoskeletal organization, EGF receptor trafficking and cell transformation. It is an immediate-early gene, regulated at many levels of its biosynthetic pathway. Herein we show that the serine/threonine protein kinase CK1 phosphorylates RhoB in vitro but not RhoA or RhoC. With the use of specific CK1 inhibitors, IC261 and D4476, we show that the kinase phosphorylates also RhoB in HeLa cells. Mass spectrometry analysis demonstrates that RhoB is monophosphorylated by CK1, in its C-terminal end, on serine 185. The substitution of Ser185 by Ala dramatically inhibited the phosphorylation of RhoB in cultured cells. Lastly we show that the inhibition of CK1 activates RhoB and promotes RhoB dependent actin fiber formation and EGF-R level. Our data provide the first demonstration of RhoB phosphorylation and indicate that this post-translational maturation would be a novel critical mechanism to control the RhoB functions.
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11
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Baldwin RM, Parolin DAE, Lorimer IAJ. Regulation of glioblastoma cell invasion by PKC iota and RhoB. Oncogene 2008; 27:3587-95. [PMID: 18212741 DOI: 10.1038/sj.onc.1211027] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Glioblastoma multiforme is the most aggressive form of primary brain tumor and remains largely incurable, in large part, due to its highly invasive nature. The phosphoinositide (PI) 3-kinase pathway is often constitutively active in these tumors due to activating mutations in the epidermal growth factor receptor, or deletion/loss of function of the tumor suppressor PTEN. Protein kinase C type iota (PKC iota), a member of the atypical protein kinase C family, is activated by the PI 3-kinase pathway and is an important downstream mediator. Here, we have assessed the role of PKC iota in glioblastoma cell invasion. Depletion of PKC iota with RNA interference caused an increase in actin stress fibers and a decrease in cell motility and invasion. Gene expression microarray analysis of U87MG cells showed that PKC iota repressed expression of mRNA for RhoB, which has previously been shown to have a role in actin stress fiber formation. Western blot analysis showed that both PKC iota depletion and pharmacological inhibition of PKC iota caused an increase in the protein levels of RhoB, as did inhibition of PI 3-kinase. Expression of RhoB from a constitutive promoter caused changes in actin stress fibers and cell invasion that were similar to those seen with PKC iota depletion. These data show that PKC iota, activated as a consequence of aberrant upstream PI 3-kinase signaling, mediates glioblastoma cell motility and invasion, and that repression of RhoB is key downstream event in PKC iota signaling leading to enhanced cell motility. In addition, constitutive expression of RhoB repressed PKC iota activity, as assessed by its phosphorylation status on Thr555. PKC iota and RhoB are, therefore, mutually antagonistic, potentially creating a sensitive switch between invasive and non-invasive phenotypes.
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Affiliation(s)
- R M Baldwin
- Ottawa Health Research Institute, Ottawa, Ontario, Canada
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12
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Abstract
Farnesyl transferase inhibitors (FTIs) are anticancer agents that were designed to block the post-translational attachment of the prenyl moiety to C-terminal cysteine residue of Ras and thus inactivate it. Because Ras plays an important role in tumour progression and the ras mutation is one of the most frequent aberrations in cancer, FTIs have been expected to exert excellent therapeutic activities. Phase I and II clinical trials confirmed relevant antitumour activity and low toxicity; however, no improvement in overall survival has been reported in Phase III trials. The exact mechanism of action of this class of agents is currently unknown. Increasing lines of evidence indicate that the cytotoxic actions of FTIs are not due to the inhibition of Ras proteins exclusively, but to the modulation of other targets, including RhoB, the centromere-binding proteins and other proteins that have not yet been identified. This review describes the pharmacological and clinical data as well as mechanisms of action of FTIs, especially lonafarnib (SCH-66336), a non-peptidomimetic inhibitor that has shown anticancer activity.
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Affiliation(s)
- Floriana Morgillo
- M. D. Anderson Cancer Center, Department of Thoracic/Head & Neck Medical Oncology, Houston, TX, USA
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13
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Sato N, Fukui T, Taniguchi T, Yokoyama T, Kondo M, Nagasaka T, Goto Y, Gao W, Ueda Y, Yokoi K, Minna JD, Osada H, Kondo Y, Sekido Y. RhoB is frequently downregulated in non-small-cell lung cancer and resides in the 2p24 homozygous deletion region of a lung cancer cell line. Int J Cancer 2006; 120:543-51. [PMID: 17096327 DOI: 10.1002/ijc.22328] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Identification of a homozygous deletion in cancer cells provides strong evidence for the location of a tumor suppressor gene (TSG). We analyzed the 2p24 homozygous deletion of a non-small-cell lung cancer (NSCLC) cell line, NCI-H2882, and found that the deletion size was 3.7 Mbp. Since RhoB, which has been suggested to be a candidate TSG, was located in this region, we analyzed RhoB for alterations in NSCLC. Although we found no mutations in 48 cell lines including 20 NSCLCs, a loss of heterozygosity (LOH) analysis in 128 primary NSCLCs showed that 25 of 62 informative samples had LOH at the RhoB locus. Northern blot analysis of 28 cell lines (including 15 NSCLCs) indicated that RhoB expression was downregulated in 27. We analyzed RhoB expression in 112 primary NSCLCs with immunohistochemistry and found no or a weak RhoB expression in 33 (42%) of 78 adenocarcinomas, whereas we found it in 29 (94%) of 31 squamous cell carcinomas. No or a weak expression of RhoB was more frequently observed in poorly- or moderately-differentiated adenocarcinomas than in well-differentiated ones (p = 0.0014). Furthermore, no or a weak expression of RhoB indicated a tendency to poor patient prognosis. Although hypermethylation was not found at the promoter region, the RhoB expression in NSCLC cell lines was induced by histone deacetylase inhibition, suggesting that RhoB downregulation may be due to histone modification. The present study demonstrates that RhoB expression is frequently downregulated in NSCLCs by multiple mechanisms, suggesting that RhoB is a candidate TSG for NSCLC.
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MESH Headings
- Aged
- Blotting, Northern
- Carcinoma, Non-Small-Cell Lung/genetics
- Carcinoma, Non-Small-Cell Lung/metabolism
- Carcinoma, Non-Small-Cell Lung/pathology
- Cell Line, Tumor
- Chromosome Deletion
- Chromosome Mapping
- Chromosomes, Human, Pair 2/genetics
- DNA Methylation
- Down-Regulation/drug effects
- Down-Regulation/genetics
- Female
- Gene Expression Regulation, Neoplastic/drug effects
- Gene Expression Regulation, Neoplastic/genetics
- Histone Deacetylase Inhibitors
- Humans
- Hydroxamic Acids/pharmacology
- Immunohistochemistry
- Kaplan-Meier Estimate
- Loss of Heterozygosity
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Lung Neoplasms/pathology
- Male
- Microsatellite Repeats
- Middle Aged
- Prognosis
- Promoter Regions, Genetic/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- rhoB GTP-Binding Protein/genetics
- rhoB GTP-Binding Protein/metabolism
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Affiliation(s)
- Naohito Sato
- Division of Molecular Oncology, Aichi Cancer Center Research Institute, Nagoya, Japan
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14
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Cheng JQ, Lindsley CW, Cheng GZ, Yang H, Nicosia SV. The Akt/PKB pathway: molecular target for cancer drug discovery. Oncogene 2005; 24:7482-92. [PMID: 16288295 DOI: 10.1038/sj.onc.1209088] [Citation(s) in RCA: 396] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The serine/threonine kinase Akt/PKB pathway presents an exciting new target for molecular therapeutics, as it functions as a cardinal nodal point for transducing extracellular (growth factor and insulin) and intracellular (receptor tyrosine kinases, Ras and Src) oncogenic signals. In addition, alterations of the Akt pathway have been detected in a number of human malignancies. Ectopic expression of Akt, especially constitutively activated Akt, is sufficient to induce oncogenic transformation of cells and tumor formation in transgenic mice as well as chemoresistance. Akt has a wide range of downstream targets that regulate tumor-associated cell processes such as cell growth, cell cycle progression, survival, migration, epithelial-mesenchymal transition and angiogenesis. Blockage of Akt signaling results in apoptosis and growth inhibition of tumor cells with elevated Akt. The observed dependence of certain tumors on Akt signaling for survival and growth has wide implications for cancer therapy, offering the potential for preferential tumor cell killing. In the last several years, through combinatorial chemistry, high-throughput and virtual screening, and traditional medicinal chemistry, a number of inhibitors of the Akt pathway have been identified. This review focuses on ongoing translational efforts to therapeutically target the Akt pathway.
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Affiliation(s)
- Jin Q Cheng
- Department of Pathology, H Lee Moffitt Cancer Center and Research Institute, University of South Florida College of Medicine, Tampa, 33612, USA.
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15
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Huang M, Kamasani U, Prendergast GC. RhoB facilitates c-Myc turnover by supporting efficient nuclear accumulation of GSK-3. Oncogene 2005; 25:1281-9. [PMID: 16247449 DOI: 10.1038/sj.onc.1209174] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The small GTPase RhoB suppresses cancer in part by limiting cell proliferation. However, the mechanisms it uses to achieve this are poorly understood. Recent studies link RhoB to trafficking of Akt, which through its regulation of glycogen synthase kinase-3 (GSK-3) has an important role in controlling the stability of the c-Myc oncoprotein. c-Myc stabilization may be a root feature of human tumorigenesis as it phenocopies an essential contribution of SV40 small T antigen in human cell transformation. In this study we show that RhoB directs efficient turnover of c-Myc in established or transformed mouse fibroblasts and that the attenuation of RhoB which occurs commonly in human cancer is a sufficient cause to elevate c-Myc levels. Increased levels of c-Myc elicited by RhoB deletion increased the proliferation of nullizygous cells, whereas restoring RhoB in null cells decreased the stability of c-Myc and restrained cell proliferation. Mechanistic analyses indicated that RhoB facilitated nuclear accumulation of GSK-3 and GSK-3-mediated phosphorylation of c-Myc T58, the critical site for ubiquitination and degradation of c-Myc. RhoB deletion restricted nuclear localization of GSK-3, reduced T58 phosphorylation, and stabilized c-Myc. These effects were not associated with changes in phosphorylation or localization of Akt, however, differences were observed in phosphorylation and localization of the GSK-3 regulatory Akt-related kinase, serum- and glucocorticoid-inducible protein kinase (SGK). The ability of RhoB to support GSK-3-dependent turnover of c-Myc offers a mechanism by which RhoB acts to limit the proliferation of neoplastically transformed cells.
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Affiliation(s)
- M Huang
- Lankenau Institute for Medical Research, Wynnewood, PA 19096, USA
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16
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Milia J, Teyssier F, Dalenc F, Ader I, Delmas C, Pradines A, Lajoie-Mazenc I, Baron R, Bonnet J, Cohen-Jonathan E, Favre G, Toulas C. Farnesylated RhoB inhibits radiation-induced mitotic cell death and controls radiation-induced centrosome overduplication. Cell Death Differ 2005; 12:492-501. [PMID: 15776002 DOI: 10.1038/sj.cdd.4401586] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Our previous results demonstrated that expressing the GTPase ras homolog gene family, member B (RhoB) in radiosensitive NIH3T3 cells increases their survival following 2 Gy irradiation (SF2). We have first demonstrated here that RhoB expression inhibits radiation-induced mitotic cell death. RhoB is present in both a farnesylated and a geranylgeranylated form in vivo. By expressing RhoB mutants encoding for farnesylated (RhoB-F cells), geranylgeranylated or the CAAX deleted form of RhoB, we have then shown that only RhoB-F expression was able to increase the SF2 value by reducing the sensitivity of these cells to radiation-induced mitotic cell death. Moreover, RhoB-F cells showed an increased G2 arrest and an inhibition of centrosome overduplication following irradiation mediated by the Rho-kinase, strongly suggesting that RhoB-F may control centrosome overduplication during the G2 arrest after irradiation. Overall, our results for the first time clearly implicate farnesylated RhoB as a crucial protein in mediating cellular resistance to radiation-induced nonapoptotic cell death.
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Affiliation(s)
- J Milia
- INSERM U563, CPTP, Département d'Innovation Thérapeutique et d'Oncologie Moléculaire, Institut Claudius Regaud, 20-24 rue du Pont St Pierre, 31052 Toulouse Cedex, France
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17
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Mazières J, Tillement V, Allal C, Clanet C, Bobin L, Chen Z, Sebti SM, Favre G, Pradines A. Geranylgeranylated, but not farnesylated, RhoB suppresses Ras transformation of NIH-3T3 cells. Exp Cell Res 2005; 304:354-64. [PMID: 15748883 DOI: 10.1016/j.yexcr.2004.10.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Revised: 10/19/2004] [Accepted: 10/25/2004] [Indexed: 10/26/2022]
Abstract
RhoB is a low molecular weight GTPase that is both farnesylated (RhoB-F) and geranylgeranylated (RhoB-GG) in cells. Based on data from rodent cell models, it has been suggested that RhoB displays differential effects on cell transformation, according to the nature of its prenylation. To test directly this hypothesis, we generated GTPase-deficient RhoB mutants that are exclusively either farnesylated or geranylgeranylated. We show that in Ras-transformed murine NIH-3T3 cells, RhoB-F enhances, whereas RhoB-GG and RhoB (F/GG) suppresses anchorage-dependent and -independent cell growth as well as tumor growth in nude mice. We then demonstrate that Ras constitutive activation of the tumor survival pathways Akt and NF-kappa B are blocked by RhoB-GG, but not by RhoB-F, providing further support for the opposing role of RhoB-F and RhoB-GG in Ras malignant transformation in NIH-3T3 cells. In addition, both RhoB (F/GG) and RhoB-GG induce apoptosis in Ras-transformed NIH-3T3 cells whereas RhoB-F has no effect. Our data demonstrate that RhoB-F and RhoB-GG which differ only by a 5-carbon isoprene behave differently in rodent cells highlighting the important role of prenyl groups in protein function and emphasize the potency of RhoB to regulate negatively the oncogenic signal.
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Affiliation(s)
- Julien Mazières
- Département Innovation Thérapeutique et Oncologie Moléculaire, Centre de Physiopathologie Toulouse Purpan INSERM U563, Institut Claudius Regaud, 20-24 rue du Pont Saint-Pierre, 31052 Toulouse cedex, France
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18
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Abstract
Protein farnesylation is a lipid posttranslational modification required for the cancer-causing activity of proteins such as the GTPase Ras. Although farnesyltransferase inhibitors (FTIs) are in clinical trials, their mechanism of action and the role of protein farnesylation in normal physiology are ill understood. In this issue of Cancer Cell, two articles shed light on these important issues. Protein farnesylation was found to be essential for early embryogenesis, dispensable for adult homeostasis, and critical for progression but not initiation of tumorigenesis. Furthermore, Rab geranylgeranyltransferase was identified as a target for some FTIs. This minireview discusses the implications of these findings on normal physiology, malignant transformation, and cancer therapy.
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Affiliation(s)
- Saïd M Sebti
- Drug Discovery Program, H. Lee Moffitt Cancer Center & Research Institute, Department of Interdisciplinary Oncology, University of South Florida College of Medicine, Tampa, Florida 33612, USA.
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19
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Ueda H, Morishita R, Narumiya S, Kato K, Asano T. Galphaq/11 signaling induces apoptosis through two pathways involving reduction of Akt phosphorylation and activation of RhoA in HeLa cells. Exp Cell Res 2004; 298:207-17. [PMID: 15242775 DOI: 10.1016/j.yexcr.2004.04.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2003] [Revised: 04/07/2004] [Indexed: 12/31/2022]
Abstract
We have previously reported that expression of the constitutively active mutant of Galpha11 or stimulation of m1 muscarinic acetylcholine receptor induced proteolytic activation of Rho-associated kinase (ROCK-I) by caspase and apoptosis in HeLa cells. In this study, we investigate the molecular mechanisms of Galphaq/11-induced apoptosis in m1 muscarinic acetylcholine receptor-expressing HeLa cells. Overexpression of Bcl-2 inhibited carbachol-induced ROCK-I cleavage, indicating a mitochondrial apoptotic pathway. Overexpression of the constitutively active mutant of Akt that delivers an anti-apoptotic survival signal had a similar influence. Insulin, a major survival factor in many cells, strongly increased phosphorylation of Akt, which was completely blocked by carbachol. This latter effect was partially inhibited by treatment with the tyrosine phosphatase inhibitors, orthovanadate and pervanadate. In parallel with these observations, carbachol attenuated insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1, an effect eliminated by orthovanadate. On the other hand, carbachol induced rapid stimulation of endogenous RhoA, and expression of a constitutively active mutant of RhoA increased ROCK-I cleavage. Orthovanadate and the dominant negative mutant of RhoA partially, and their combination completely, inhibited carbachol-induced ROCK-I cleavage and apoptosis. These results demonstrate that Gq/11 signaling induces apoptosis by reducing insulin-stimulated Akt phosphorylation through tyrosine dephosphorylation and activating RhoA in HeLa cells.
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Affiliation(s)
- Hiroshi Ueda
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kamiya-cho, Kasugai, 480-0392, Japan
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20
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Abstract
The importance of the Rho-GTPases in cancer progression, particularly in the area of metastasis, is becoming increasingly evident. This review will provide an overview of the role of the Rho-regulatory proteins in breast cancer metastatis.
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Affiliation(s)
- Min Lin
- Department of Internal Medicine, The University of Michigan Comprehensive Cancer Center, Ann Arbor, MI 48109-0948, USA
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Running MP, Lavy M, Sternberg H, Galichet A, Gruissem W, Hake S, Ori N, Yalovsky S. Enlarged meristems and delayed growth in plp mutants result from lack of CaaX prenyltransferases. Proc Natl Acad Sci U S A 2004; 101:7815-20. [PMID: 15128936 PMCID: PMC419689 DOI: 10.1073/pnas.0402385101] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Indexed: 11/18/2022] Open
Abstract
Meristems require a myriad of intercellular signaling pathways for coordination of cell division within and between functional zones and clonal cell layers. This control of cell division ensures a constant availability of stem cells throughout the life span of the meristem while limiting overproliferation of meristematic cells and maintaining the meristem structure. We have undertaken a genetic screen to identify additional components of meristem signaling pathways. We identified pluripetala (plp) mutants based on their dramatically larger meristems and increased floral organ number. PLURIPETALA encodes the alpha-subunit shared between protein farnesyltransferase and protein geranylgeranyltransferase-I. plp mutants also have altered abscisic acid responses and overall much slower growth rate. plp is epistatic to mutations in the beta-subunit of farnesyltransferase and shows a synergistic interaction with clavata3 mutants. plp mutants lead to insights into the mechanism of meristem homeostasis and provide a unique in vivo system for studying the functional role of prenylation in eukaryotes.
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Affiliation(s)
- Mark P Running
- U.S. Department of Agriculture-Agricultural Research Service Plant Gene Expression Center, Albany, CA 94710, USA
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22
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Mazieres J, Antonia T, Daste G, Muro-Cacho C, Berchery D, Tillement V, Pradines A, Sebti S, Favre G. Loss of RhoB Expression in Human Lung Cancer Progression. Clin Cancer Res 2004; 10:2742-50. [PMID: 15102679 DOI: 10.1158/1078-0432.ccr-03-0149] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE RhoB is a low molecular weight GTPase belonging to the Ras protein superfamily. Whereas most Rho proteins have been shown to have a positive role in proliferation and malignant transformation, the specific role of RhoB appears more divergent. We reported previously that RhoB inhibits cell proliferation in various human cancer cells. Here, we studied the specific role played by RhoB in human lung cancer. EXPERIMENTAL DESIGN We analyzed the expression of RhoB protein by immunostaining in human lung tissues ranging from normal to invasive carcinoma from different histological types in two large independent studies of, respectively, 94 and 45 samples. We then studied the cellular effect of RhoB overexpression in a model of lung cancer (A549, adenocarcinoma) and tumorigenicity in nude mice. RESULTS We showed in both studies that RhoB protein was expressed in normal lung and decreased dramatically through lung cancer progression (P < 0.01). Interestingly, RhoB expression was lost in 96% of invasive tumors and reduced by 86% in poorly differentiated tumors compared with the nonneoplastic epithelium. Moreover, the loss of expression of RhoB correlated significantly with tumor stage and proliferative index, whereas no correlation was found between RhoB and p53 or Bcl-2 expression. We then showed that ectopic expression of RhoB in lung cancer cell line A549 suppressed cell proliferation, anchorage-independent growth, and xenograft tumor growth in nude mice. CONCLUSIONS RhoB loss of expression occurs very frequently in lung carcinogenesis, reinforcing its putative tumor suppressive activity, and raising the value of its potential use in cancer therapy.
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Affiliation(s)
- Julien Mazieres
- Institut National de la Santé et de la Recherche Médicale U563, Department of Therapeutic Innovation and Molecular Oncology. Claudius Regaud Institute, Toulouse, France
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23
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Affiliation(s)
- Saïd M Sebti
- Drug Discovery Program, H. Lee Moffitt Cancer Center & Research Institute, Department of Oncology, University of South Florida College of Medicine, Tampa, FL 33612, USA
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24
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Adini I, Rabinovitz I, Sun JF, Prendergast GC, Benjamin LE. RhoB controls Akt trafficking and stage-specific survival of endothelial cells during vascular development. Genes Dev 2003; 17:2721-32. [PMID: 14597666 PMCID: PMC280621 DOI: 10.1101/gad.1134603] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Blood vessel formation is a complex morphological process that is only beginning to be understood at the molecular level. In this study, we demonstrate a novel and critical role for the small GTPase, RhoB, in vascular development. RhoB null mice have retarded vascular development in the retina characterized by altered sprout morphology. Moreover, pharmaceutical means to deplete RhoB in neonatal rats is associated with apoptosis in the sprouting endothelial cells of newly forming vessels. Similarly, acute depletion of RhoB by antisense or dominant-negative strategies in primary endothelial cell culture models led to apoptosis and failures in tube formation. We identified a novel link between RhoB and the Akt survival signaling pathway to explain these changes. Confocal microscopy revealed that RhoB is highly localized to the nuclear margin with a small percentage found inside the nucleus. Similarly, total Akt is throughout the cell but has increased accumulation at the nuclear margin, and active phosphorylated Akt is found primarily inside the nucleoplasm, where it partially colocalizes with the RhoB therein. We show that this colocalization is functionally relevant, because when RhoB was depleted, Akt was excluded from the nucleus and total cellular Akt protein was decreased in a proteosome-dependent manner. Because the function of RhoB in vivo appears to only be rate limiting for endothelial cell sprouting, we propose that RhoB has a novel stage-specific function to regulate endothelial cell survival during vascular development. RhoB may offer a therapeutic target in diseases such as cancer, diabetic retinopathy, and macular degeneration, where the disruption of sprouting angiogenesis would be desirable.
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Affiliation(s)
- Irit Adini
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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25
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Wang S, Yan-Neale Y, Fischer D, Zeremski M, Cai R, Zhu J, Asselbergs F, Hampton G, Cohen D. Histone deacetylase 1 represses the small GTPase RhoB expression in human nonsmall lung carcinoma cell line. Oncogene 2003; 22:6204-13. [PMID: 13679859 DOI: 10.1038/sj.onc.1206653] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The dynamic balance between histone acetylation and deacetylation plays a significant role in the regulation of gene transcription. Much of our current understanding of this transcriptional control comes from the use of HDAC inhibitors such as trapoxin A (TPX), which leads to hyperacetylated histone, alters local chromatin architecture and transcription and results in tumor cell death. In this study, we treated tumor cells with TPX and HDAC1 antisense oligonucleotides, and analysed the transcriptional consequences of HDAC inhibition. Among other genes, the small GTPase RhoB was found to be significantly upregulated by TPX and repressed by HDAC1. The induction of RhoB by HDAC inhibition was mediated by an inverted CCAAT box in the RhoB promoter. Interestingly, measurement of RhoB transcription in approximately 130 tumor-derived cell lines revealed low expression in almost all of these samples, in contrast to RhoA and RhoC. Accumulating evidence indicates that the small GTPase Rho proteins are involved in a variety of important processes in cancer, including cell transformation, survival, invasion, metastasis and angiogenesis. This study for the first time demonstrates a link between HDAC inhibition and RhoB expression and provides an important insight into the mechanisms of HDAC-mediated transcriptional control and the potential therapeutic benefit of HDAC inhibition.
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Affiliation(s)
- Shaowen Wang
- Department of Functional Genomics, Novartis Pharmaceutical Corporation, East Hanover, Summit, NJ 07901, USA
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26
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Zeng PY, Rane N, Du W, Chintapalli J, Prendergast GC. Role for RhoB and PRK in the suppression of epithelial cell transformation by farnesyltransferase inhibitors. Oncogene 2003; 22:1124-34. [PMID: 12606940 DOI: 10.1038/sj.onc.1206181] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Recent genetic investigations have established that RhoB gain-of-function is sufficient to mediate the antitransforming effects of farnesyltransferase inhibitors (FTIs) in H-Ras-transformed fibroblast systems. In this study, we addressed the breadth and mechanism of RhoB action in epithelial cells transformed by oncoproteins which are themselves insensitive to FTI inactivation. Rat intestinal epithelial (RIE) cells transformed by activated K-Ras or Rac1 were highly sensitive to FTI-induced actin reorganization and growth inhibition, despite the inability of FTI to block prenylation of either K-Ras or Rac1. Ectopic expression of the geranylgeranylated RhoB isoform elicited in cells by FTI treatment phenocopied these effects. Analysis of RhoB effector domain mutants pointed to a role for PRK, a Rho effector kinase implicated in the physiological function of RhoB in intracellular receptor trafficking, and these findings were supported further by experiments in a fibroblast system. We propose that FTIs recruit the antioncogenic RhoB protein in the guise of RhoB-GG to interfere with signaling by pro-oncogenic Rho proteins, possibly by sequestering common exchange factors or effectors such as PRK that are important for cell transformation.
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MESH Headings
- Actin Cytoskeleton/drug effects
- Actin Cytoskeleton/ultrastructure
- Actins/analysis
- Alkyl and Aryl Transferases/antagonists & inhibitors
- Animals
- Bacterial Proteins/physiology
- Cell Division/drug effects
- Cell Line, Transformed/drug effects
- Cell Line, Transformed/enzymology
- Cell Line, Transformed/ultrastructure
- Cell Transformation, Neoplastic/drug effects
- Cell Transformation, Neoplastic/metabolism
- Cells, Cultured/drug effects
- Cells, Cultured/enzymology
- Cells, Cultured/ultrastructure
- DNA-Binding Proteins/physiology
- Enzyme Inhibitors/pharmacology
- Epithelial Cells/drug effects
- Epithelial Cells/enzymology
- Epithelial Cells/ultrastructure
- Escherichia coli Proteins
- Farnesyltranstransferase
- Fibroblasts/drug effects
- Fibroblasts/enzymology
- Fibroblasts/ultrastructure
- Genes, ras
- Intestinal Mucosa/cytology
- Methionine/analogs & derivatives
- Methionine/pharmacology
- Models, Biological
- Protein Isoforms/physiology
- Protein Kinase C/physiology
- Protein Prenylation/drug effects
- Protein Processing, Post-Translational/drug effects
- Rats
- Signal Transduction
- rac1 GTP-Binding Protein/physiology
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27
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Smalley KSM, Eisen TG. Farnesyl thiosalicylic acid inhibits the growth of melanoma cells through a combination of cytostatic and pro-apoptotic effects. Int J Cancer 2002; 98:514-22. [PMID: 11920610 DOI: 10.1002/ijc.10213] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Novel classes of drug that interfere with the signalling of the small G-protein Ras, the so-called Ras antagonists, are showing much promise as novel anti-cancer agents. In this study, we demonstrate that the novel Ras antagonist farnesylthiosalicylic acid (FTS) inhibits the growth of Colo 853 melanoma cells through a combination of cytostatic and pro-apoptotic effects. Furthermore, these phenomena are seen under conditions of cell attachment and in the presence of serum. Treatment of Colo 853 cells with FTS led to time-dependent inhibition of constitutive Akt, retinoblastoma protein (pRB) and ERK activity, with a concurrent loss of Akt expression. Inhibition of Akt and ERK activity induces apoptosis in other human cancer cell lines. Here it is demonstrated that inhibition of Akt, or ERK and Akt in combination, leads to cell cycle arrest but not apoptosis in melanoma cells. FTS treatment was also found to upregulate activity of the stress-activated p38 MAP kinase. Inhibition of p38 MAP kinase, using the selective inhibitor SB 203580, followed by FTS treatment, significantly increased the proportion of apoptotic cells after 72 hr, possibly suggesting a modulatory role for p38 MAP kinase in FTS-induced melanoma cell apoptosis.
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Abstract
Farnesyltransferase (FT) inhibitors (FTIs) are among the first wave of signal transduction inhibitors to be clinically tested for antitumour properties. FTIs were designed to attack Ras oncoproteins, the function of which depends upon post-translational modification by farnesyl isoprenoid. Extensive preclinical studies have demonstrated that FTIs compromise neoplastic transformation and tumour growth. In preclinical models, FTIs display limited effects on normal cell physiology and in Phase I human trials FTIs have been largely well tolerated. Exactly how FTIs selectively target cancer cells has emerged as an important question, one which has become more pressing with the somewhat disappointing results from initial Phase II efficacy trials. Although FTI development was predicated on Ras inhibition, it has become clear that the drugs' antineoplastic properties are based to a large degree on altering the prenylation and function of proteins other than Ras. One key candidate that has emerged is RhoB, an endosomal protein that has been implicated in selective growth inhibition and apoptosis in neoplastic cells. On the basis of mechanistic studies and other recent developments, we propose that FTIs may be useful to treat a unique spectrum of diseases including not only inflammatory breast cancer and melanoma but also non-neoplastic diseases such as diabetic retinopathy and macular degeneration.
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Affiliation(s)
- G C Prendergast
- Cancer Research Group, Glenolden Laboratory, DuPont Pharmaceuticals Company, Glenolden, PA 19036, USA.
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29
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Abstract
RhoB is a small GTPase that regulates actin organization and vesicle transport. It is required for signalling apoptosis in transformed cells that are exposed to farnesyltransferase inhibitors, DNA-damaging agents or taxol. Genetic analysis in mice indicates that RhoB is dispensable for normal cell physiology, but that it has a suppressor or negative modifier function in stress-associated processes, including cancer.
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Affiliation(s)
- G C Prendergast
- The DuPont Pharmaceuticals Company, Glenolden Laboratory, Pennsylvania 19004, USA.
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