1
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Cannon AC, Budagyan K, Uribe-Alvarez C, Kurimchak AM, Araiza-Olivera D, Cai KQ, Peri S, Zhou Y, Duncan JS, Chernoff J. Unique vulnerability of RAC1-mutant melanoma to combined inhibition of CDK9 and immune checkpoints. Oncogene 2024; 43:729-743. [PMID: 38243078 PMCID: PMC11157427 DOI: 10.1038/s41388-024-02947-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 01/06/2024] [Accepted: 01/09/2024] [Indexed: 01/21/2024]
Abstract
RAC1P29S is the third most prevalent hotspot mutation in sun-exposed melanoma. RAC1 alterations in cancer are correlated with poor prognosis, resistance to standard chemotherapy, and insensitivity to targeted inhibitors. Although RAC1P29S mutations in melanoma and RAC1 alterations in several other cancers are increasingly evident, the RAC1-driven biological mechanisms contributing to tumorigenesis remain unclear. Lack of rigorous signaling analysis has prevented identification of alternative therapeutic targets for RAC1P29S-harboring melanomas. To investigate the RAC1P29S-driven effect on downstream molecular signaling pathways, we generated an inducible RAC1P29S expression melanocytic cell line and performed RNA-sequencing (RNA-seq) coupled with multiplexed kinase inhibitor beads and mass spectrometry (MIBs/MS) to establish enriched pathways from the genomic to proteomic level. Our proteogenomic analysis identified CDK9 as a potential new and specific target in RAC1P29S-mutant melanoma cells. In vitro, CDK9 inhibition impeded the proliferation of in RAC1P29S-mutant melanoma cells and increased surface expression of PD-L1 and MHC Class I proteins. In vivo, combining CDK9 inhibition with anti-PD-1 immune checkpoint blockade significantly inhibited tumor growth only in melanomas that expressed the RAC1P29S mutation. Collectively, these results establish CDK9 as a novel target in RAC1-driven melanoma that can further sensitize the tumor to anti-PD-1 immunotherapy.
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Affiliation(s)
- Alexa C Cannon
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA, USA
- Drexel University College of Medicine, Philadelphia, PA, USA
| | - Konstantin Budagyan
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA, USA
- Drexel University College of Medicine, Philadelphia, PA, USA
| | - Cristina Uribe-Alvarez
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Alison M Kurimchak
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Daniela Araiza-Olivera
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Kathy Q Cai
- Histopathology Facility, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Suraj Peri
- Biostatistics-Bioinformatics, Fox Chase Cancer Center, Philadelphia, PA, USA
- Merck, Bioinformatics Oncology Discovery, Boston, MA, USA
| | - Yan Zhou
- Biostatistics-Bioinformatics, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - James S Duncan
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Jonathan Chernoff
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA, USA.
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2
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Cannon AC, Budagyan K, Uribe-Alvarez C, Kurimchak AM, Araiza-Olivera D, Cai KQ, Peri S, Zhou Y, Duncan JS, Chernoff J. Unique vulnerability of RAC1-mutant melanoma to combined inhibition of CDK9 and immune checkpoints. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.27.546707. [PMID: 37425776 PMCID: PMC10327161 DOI: 10.1101/2023.06.27.546707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
RAC1P29S is the third most prevalent hotspot mutation in sun-exposed melanoma. RAC1 alterations in cancer are correlated with poor prognosis, resistance to standard chemotherapy, and insensitivity to targeted inhibitors. Although RAC1P29S mutations in melanoma and RAC1 alterations in several other cancers are increasingly evident, the RAC1-driven biological mechanisms contributing to tumorigenesis remain unclear. Lack of rigorous signaling analysis has prevented identification of alternative therapeutic targets for RAC1P29S-harboring melanomas. To investigate the RAC1P29S-driven effect on downstream molecular signaling pathways, we generated an inducible RAC1P29S expression melanocytic cell line and performed RNA-sequencing (RNA-seq) coupled with multiplexed kinase inhibitor beads and mass spectrometry (MIBs/MS) to establish enriched pathways from the genomic to proteomic level. Our proteogenomic analysis identified CDK9 as a potential new and specific target in RAC1P29S-mutant melanoma cells. In vitro, CDK9 inhibition impeded the proliferation of in RAC1P29S-mutant melanoma cells and increased surface expression of PD-L1 and MHC Class I proteins. In vivo, combining CDK9 inhibition with anti-PD-1 immune checkpoint blockade significantly inhibited tumor growth only in melanomas that expressed the RAC1P29S mutation. Collectively, these results establish CDK9 as a novel target in RAC1-driven melanoma that can further sensitize the tumor to anti-PD-1 immunotherapy.
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Affiliation(s)
- Alexa C Cannon
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA
- Drexel University College of Medicine, Philadelphia, PA
| | - Konstantin Budagyan
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA
- Drexel University College of Medicine, Philadelphia, PA
| | - Cristina Uribe-Alvarez
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA
| | - Alison M Kurimchak
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA
| | - Daniela Araiza-Olivera
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA
| | - Kathy Q Cai
- Histopathology Facility, Fox Chase Cancer Center, Philadelphia, PA
| | - Suraj Peri
- Biostatistics-Bioinformatics, Fox Chase Cancer Center, Philadelphia, PA
- Current Affiliation: Merck, Bioinformatics Oncology Discovery, Boston, MA
| | - Yan Zhou
- Biostatistics-Bioinformatics, Fox Chase Cancer Center, Philadelphia, PA
| | - James S Duncan
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA
| | - Jonathan Chernoff
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, PA
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3
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Ravi LI, Tan TJ, Tan BH, Sugrue RJ. Virus-induced activation of the rac1 protein at the site of respiratory syncytial virus assembly is a requirement for virus particle assembly on infected cells. Virology 2021; 557:86-99. [PMID: 33677389 DOI: 10.1016/j.virol.2021.02.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/17/2020] [Accepted: 02/16/2021] [Indexed: 12/13/2022]
Abstract
The distributions of the rac1, rhoA and cdc42 proteins in respiratory syncytial virus (RSV) infected cells was examined. All three rhoGTPases were detected within inclusion bodies, and while the rhoA and rac1 proteins were associated with virus filaments, only the rac1 protein was localised throughout the virus filaments. RSV infection led to increased rac1 protein activation, and using the rac1 protein inhibitor NS23766 we provided evidence that the increased rac1 activation occurred at the site of RSV assembly and facilitated F-actin remodeling during virus morphogenesis. A non-infectious virus-like particle (VLP) assay showed that the RSV VLPs formed in lipid-raft microdomains containing the rac1 protein, together with F-actin and filamin-1 (cell proteins associated with virus filaments). This provided evidence that the virus envelope proteins are trafficked to membrane microdomains containing the rac1 protein. Collectively, these data provide evidence that the rac1 protein plays a direct role in the RSV assembly process.
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Affiliation(s)
- Laxmi Iyer Ravi
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Timothy J Tan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Boon Huan Tan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore; Defense Medical and Environment Research Institute, DSO National Laboratories, 27 Medical Drive, 117510, Singapore; Infection and Immunity, Lee Kong Chian School of Medicine, Nanyang Technological University, 11 Mandalay Road, Singapore, 308232, Singapore
| | - Richard J Sugrue
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.
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4
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Pickering KA, Gilroy K, Cassidy JW, Fey SK, Najumudeen AK, Zeiger LB, Vincent DF, Gay DM, Johansson J, Fordham RP, Miller B, Clark W, Hedley A, Unal EB, Kiel C, McGhee E, Machesky LM, Nixon C, Johnsson AE, Bain M, Strathdee D, van Hoof SR, Medema JP, Anderson KI, Brachmann SM, Stucke VM, Malliri A, Drysdale M, Turner M, Serrano L, Myant K, Campbell AD, Sansom OJ. A RAC-GEF network critical for early intestinal tumourigenesis. Nat Commun 2021; 12:56. [PMID: 33397922 PMCID: PMC7782582 DOI: 10.1038/s41467-020-20255-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/17/2020] [Indexed: 01/29/2023] Open
Abstract
RAC1 activity is critical for intestinal homeostasis, and is required for hyperproliferation driven by loss of the tumour suppressor gene Apc in the murine intestine. To avoid the impact of direct targeting upon homeostasis, we reasoned that indirect targeting of RAC1 via RAC-GEFs might be effective. Transcriptional profiling of Apc deficient intestinal tissue identified Vav3 and Tiam1 as key targets. Deletion of these indicated that while TIAM1 deficiency could suppress Apc-driven hyperproliferation, it had no impact upon tumourigenesis, while VAV3 deficiency had no effect. Intriguingly, deletion of either gene resulted in upregulation of Vav2, with subsequent targeting of all three (Vav2-/- Vav3-/- Tiam1-/-), profoundly suppressing hyperproliferation, tumourigenesis and RAC1 activity, without impacting normal homeostasis. Critically, the observed RAC-GEF dependency was negated by oncogenic KRAS mutation. Together, these data demonstrate that while targeting RAC-GEF molecules may have therapeutic impact at early stages, this benefit may be lost in late stage disease.
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Affiliation(s)
- K A Pickering
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - K Gilroy
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - J W Cassidy
- CRUK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 ORE, UK
| | - S K Fey
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow, G61 1QH, UK
| | - A K Najumudeen
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - L B Zeiger
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow, G61 1QH, UK
| | - D F Vincent
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - D M Gay
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - J Johansson
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - R P Fordham
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - B Miller
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - W Clark
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - A Hedley
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - E B Unal
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRC), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain
- Institute for Theoretical Biology, Humboldt Universität zu Berlin, Berlin, Germany
| | - C Kiel
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRC), Barcelona, Spain
| | - E McGhee
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - L M Machesky
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow, G61 1QH, UK
| | - C Nixon
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - A E Johnsson
- The Babraham Institute, Babraham Hall, Babraham, Cambridge, CB22 3AT, UK
| | - M Bain
- IBAHCM and School of Veterinary Medicine, 464 Bearsden Road, Bearsden, Glasgow, G61 1QH, UK
| | - D Strathdee
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - S R van Hoof
- Laboratory for Experimental Oncology and Radiobiology (LEXOR), Center for Experimental Molecular Medicine (CEMM) and Cancer Center Amsterdam, Academic Medical Center, Amsterdam, The Netherlands
- Oncode Institute, Academic Medical Center, Amsterdam, The Netherlands
| | - J P Medema
- Laboratory for Experimental Oncology and Radiobiology (LEXOR), Center for Experimental Molecular Medicine (CEMM) and Cancer Center Amsterdam, Academic Medical Center, Amsterdam, The Netherlands
- Oncode Institute, Academic Medical Center, Amsterdam, The Netherlands
| | - K I Anderson
- The Francis Crick Institute, Mill Hill Laboratory, London, NW7 1AA, UK
| | - S M Brachmann
- Novartis Institutes for BioMedical Research, Klybeckstrasse, 141, 4002, Basel, Switzerland
| | - V M Stucke
- Novartis Institutes for BioMedical Research, Klybeckstrasse, 141, 4002, Basel, Switzerland
| | - A Malliri
- CRUK Manchester Institute, 553 Wilmslow Road, Manchester, M20 4BX, UK
| | - M Drysdale
- Broad Institute, 415 Main St, Cambridge, MA, 02142, United States
| | - M Turner
- The Babraham Institute, Babraham Hall, Babraham, Cambridge, CB22 3AT, UK
| | - L Serrano
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRC), Barcelona, Spain
| | - K Myant
- Edinburgh Research Centre, The Institute of Genetics and Molecular Medicine, Crewe Road South, Edinburgh, EH4 2XR, UK.
| | - A D Campbell
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK.
| | - O J Sansom
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK.
- Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow, G61 1QH, UK.
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5
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Rahmati S, O'Rielly DD, Li Q, Codner D, Dohey A, Jenkins K, Jurisica I, Gladman DD, Chandran V, Rahman P. Rho-GTPase pathways may differentiate treatment response to TNF-alpha and IL-17A inhibitors in psoriatic arthritis. Sci Rep 2020; 10:21703. [PMID: 33303908 PMCID: PMC7728744 DOI: 10.1038/s41598-020-78866-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 12/01/2020] [Indexed: 12/14/2022] Open
Abstract
Biological therapies have dramatically improved the therapeutic landscape of psoriatic arthritis (PsA); however, 40–50% of patients are primary non-responders with response rates declining significantly with each successive biological therapy. Therefore, there is a pressing need to develop a coherent strategy for effective initial and subsequent selection of biologic agents. We interrogated 40 PsA patients initiating either tumour necrosis factor inhibitors (TNFi) or interleukin-17A inhibitors (17Ai) for active PsA. Patients achieving low disease activity according to the Disease Activity Index for PsA (DAPSA) at 3 months were classified as responders. Baseline and 3-month CD4+ transcript profiling were performed, and novel signaling pathways were identified using a multi-omics profiling and integrative computational analysis approach. Using transcriptomic data at initiation of therapy, we identified over 100 differentially expressed genes (DEGs) that differentiated IL-17Ai response from non-response and TNFi response from non-response. Integration of cell-type-specific DEGs with protein–protein interactions and further comprehensive pathway enrichment analysis revealed several pathways. Rho GTPase signaling pathway exhibited a strong signal specific to IL-17Ai response and the genes, RAC1 and ROCKs, are supported by results from prior research. Our detailed network and pathway analyses have identified the rewiring of Rho GTPase pathways as potential markers of response to IL17Ai but not TNFi. These results need further verification.
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Affiliation(s)
- Sara Rahmati
- Krembil Research Institute, UHN, 5-KD405, Krembil Discovery Tower, 60 Leonard Ave, Toronto, M5T 2S8, Canada.,Faculty of Medicine, Craig L Dobbin Genetics Research Centre, Memorial University, Suite 3M500, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada
| | - Darren D O'Rielly
- Faculty of Medicine, Craig L Dobbin Genetics Research Centre, Memorial University, Suite 3M500, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada
| | - Quan Li
- Krembil Research Institute, UHN, 5-KD405, Krembil Discovery Tower, 60 Leonard Ave, Toronto, M5T 2S8, Canada.,Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G1L7, Canada
| | - Dianne Codner
- Faculty of Medicine, Craig L Dobbin Genetics Research Centre, Memorial University, Suite 3M500, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada.,Faculty of Medicine, 5M202 Craig L Dobbin Genetics Research Centre, Memorial University, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada
| | - Amanda Dohey
- Faculty of Medicine, Craig L Dobbin Genetics Research Centre, Memorial University, Suite 3M500, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada.,Faculty of Medicine, 5M203 Craig L Dobbin Genetics Research Centre, Memorial University, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada
| | - Kari Jenkins
- Faculty of Medicine, Craig L Dobbin Genetics Research Centre, Memorial University, Suite 3M500, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada.,St. Clare's Mercy Hosptial, 154 LeMarchant Rd., St. John's, NL, A1C5B8, Canada
| | - Igor Jurisica
- Krembil Research Institute, UHN, 5-KD405, Krembil Discovery Tower, 60 Leonard Ave, Toronto, M5T 2S8, Canada.,University of Toronto, Toronto, Canada.,Data Science Discovery Centre for Chronic Diseases, Krembil Research Institute, Toronto Western Hospital, 60 Leonard Avenue, 5KD-407, Toronto, ON, M5T 0S8, Canada
| | - Dafna D Gladman
- Krembil Research Institute, UHN, 5-KD405, Krembil Discovery Tower, 60 Leonard Ave, Toronto, M5T 2S8, Canada.,University of Toronto, Toronto, Canada.,Toronto Western Hospital, 399 Bathurst Street, 1E410B, Toronto, M5T 2S8, Canada
| | - Vinod Chandran
- Krembil Research Institute, UHN, 5-KD405, Krembil Discovery Tower, 60 Leonard Ave, Toronto, M5T 2S8, Canada.,Faculty of Medicine, Craig L Dobbin Genetics Research Centre, Memorial University, Suite 3M500, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada.,University of Toronto, Toronto, Canada.,Toronto Western Hospital, 399 Bathurst Street, 1E416, Toronto, M5T 2S8, Canada
| | - Proton Rahman
- Faculty of Medicine, Craig L Dobbin Genetics Research Centre, Memorial University, Suite 3M500, 300 Prince Philip Drive, St. John's, NL, A1B3V6, Canada. .,St. Clare's Mercy Hosptial, 154 LeMarchant Rd., St. John's, NL, A1C5B8, Canada.
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6
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Hirata H, Dobrokhotov O, Sokabe M. Coordination between Cell Motility and Cell Cycle Progression in Keratinocyte Sheets via Cell-Cell Adhesion and Rac1. iScience 2020; 23:101729. [PMID: 33225242 PMCID: PMC7662878 DOI: 10.1016/j.isci.2020.101729] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/23/2020] [Accepted: 10/21/2020] [Indexed: 11/27/2022] Open
Abstract
Regulations of cell motility and proliferation are essential for epithelial development and homeostasis. However, it is not fully understood how these cellular activities are coordinated in epithelial collectives. In this study, we find that keratinocyte sheets exhibit time-dependent coordination of collective cell movement and cell cycle progression after seeding cells. Cell movement and cell cycle progression are coordinately promoted by Rac1 in the “early phase” (earlier than ∼30 h after seeding cells), which is not abrogated by increasing the initial cell density to a saturated level. The Rac1 activity is gradually attenuated in the “late phase” (later than ∼30 h after seeding cells), leading to arrests in cell motility and cell cycle. Intact adherens junctions are required for normal coordination between cell movement and cell cycle progression in both early and late phases. Our results unveil a novel basis for integrating motile and proliferative behaviors of epithelial collectives. Cell motility and cell cycle progression in keratinocyte sheets are temporally coordinated Rac1 promotes both cell motility and cell cycle progression in keratinocyte sheets Arrest of cell motility and cell cycle is associated with Rac1 deactivation Adherens junction is required for coordinating cell motility and cell cycle
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Affiliation(s)
- Hiroaki Hirata
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8550, Japan
| | - Oleg Dobrokhotov
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8550, Japan
| | - Masahiro Sokabe
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8550, Japan
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7
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Goka ET, Chaturvedi P, Lopez DTM, Lippman ME. Rac Signaling Drives Clear Cell Renal Carcinoma Tumor Growth by Priming the Tumor Microenvironment for an Angiogenic Switch. Mol Cancer Ther 2020; 19:1462-1473. [PMID: 32371578 DOI: 10.1158/1535-7163.mct-19-0762] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/11/2019] [Accepted: 04/23/2020] [Indexed: 12/24/2022]
Abstract
Clear cell renal cell carcinoma (ccRCC) remains a common cause of cancer mortality. Better understanding of ccRCC molecular drivers resulted in the development of antiangiogenic therapies that block the blood vessels that supply tumors with nutrients for growth and metastasis. Unfortunately, most ccRCC patients eventually become resistant to initial treatments, creating a need for alternative treatment options. We investigated the role of the small GTPase Rac1 in ccRCC. Analysis of ccRCC clinical samples indicates that Rac signaling drives disease progression and predicts patients with poorer outcomes. Investigation of Rac1 identifies multiple roles for Rac1 in the pathogenesis of ccRCC. Rac1 is overexpressed in RCC cell lines and drives proliferation and migratory/metastatic potential. Rac1 is also critical for endothelial cells to grow and form endothelial tubular networks potentiated by angiogenic factors. Importantly, Rac1 controls paracrine signaling of angiogenic factors including VEGF from renal carcinoma cells to surrounding blood vessels. A novel Rac1 inhibitor impaired the growth and migratory potential of both renal carcinoma cells and endothelial cells and reduced VEGF production by RCC cells, thereby limiting paracrine signaling both in vitro and in vivo Lastly, Rac1 was shown to be downstream of VEGF receptor (VEGFR) signaling and required for activation of MAPK signaling. In combination with VEGFR2 inhibitors, Rac inhibition provides enhanced suppression of angiogenesis. Therefore, targeting Rac in ccRCC has the potential to block the growth of tumor cells, endothelial cell recruitment, and paracrine signaling from tumor cells to other cells in the tumor microenvironment.
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Affiliation(s)
| | | | | | - Marc E Lippman
- Department of Oncology, Georgetown University, Washington, District of Columbia
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8
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Qiao W, Li D, Shi Q, Wang H, Wang H, Guo J. miR-224-5p protects dental pulp stem cells from apoptosis by targeting Rac1. Exp Ther Med 2019; 19:9-18. [PMID: 31897093 PMCID: PMC6923752 DOI: 10.3892/etm.2019.8213] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 07/12/2019] [Indexed: 12/27/2022] Open
Abstract
Dental pulp stem cells (DPSCs) are reported to be enriched in stem/progenitor cells, however to the best of our knowledge they have yet to be well documented and characterized. In the present study, in order to characterize DPSCs and the effect of microRNAs (miRs/miRNAs) on DPSC properties, a miRNA array was performed between dental periodontal ligament cells (DPLCs) and DPSCs. The results revealed that miR-224-5p (miR-224) was highly expressed in the DPSCs compared with that in the DPLCs. The transfection of DPSCs with an miR-224 inhibitor impaired cell viability. In addition, miR-224 inhibition significantly promoted cell apoptosis in DPSCscompared with the NC group. In silico analysis and a dual-luciferase reporter assay demonstrated that miR-224 targets the 3′-untranslated region of the Rac family small GTPase 1 (Rac1) gene. miR-224 downregulation resulted in the increased expression of Rac1 in DPSCs compared with DPLCs. Furthermore, miR-224 inhibition caused augmented mitogen-activated protein kinase 8, caspase-3, caspase-9 and Fas ligand expression in DPSC, which may be recovered by Rac1 silencing with transfection with short hairpin RNA-Rac1. Furthermore, Annexin V-fluorescein isothiocyanate/propidium iodide flow cytometry indicated that the silencing of Rac1 restored the pro-apoptotic DPSC cell number with miR-224 transfection. Therefore, the results of the present study suggested miR-224 in DPSC serves an important function in protecting cells against apoptosis by downregulating Rac1 expression, and also identified miR-224 as a novel miRNA in regulating the features of DPSC.
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Affiliation(s)
- Wenlan Qiao
- Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Department of Orthodontics, School of Stomatology, Shandong University, Jinan, Shandong 250012, P.R. China.,Department of Stomatology, Qilu Hospital, and Institute of Stomatology, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Dong Li
- Department of Cryomedicine Laboratory, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China
| | - Qing Shi
- Department of Cryomedicine Laboratory, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China
| | - Huanhuan Wang
- Department of Cryomedicine Laboratory, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China
| | - Hao Wang
- Department of Cryomedicine Laboratory, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China
| | - Jing Guo
- Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Department of Orthodontics, School of Stomatology, Shandong University, Jinan, Shandong 250012, P.R. China
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9
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Coordination between Rac1 and Rab Proteins: Functional Implications in Health and Disease. Cells 2019; 8:cells8050396. [PMID: 31035701 PMCID: PMC6562727 DOI: 10.3390/cells8050396] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 04/25/2019] [Accepted: 04/26/2019] [Indexed: 02/07/2023] Open
Abstract
The small GTPases of the Rho family regulate many aspects of actin dynamics, but are functionally connected to many other cellular processes. Rac1, a member of this family, besides its known function in the regulation of actin cytoskeleton, plays a key role in the production of reactive oxygen species, in gene transcription, in DNA repair, and also has been proven to have specific roles in neurons. This review focuses on the cooperation between Rac1 and Rab proteins, analyzing how the coordination between these GTPases impact on cells and how alterations of their functions lead to disease.
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10
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Durand-Onaylı V, Haslauer T, Härzschel A, Hartmann TN. Rac GTPases in Hematological Malignancies. Int J Mol Sci 2018; 19:ijms19124041. [PMID: 30558116 PMCID: PMC6321480 DOI: 10.3390/ijms19124041] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/22/2022] Open
Abstract
Emerging evidence suggests that crosstalk between hematologic tumor cells and the tumor microenvironment contributes to leukemia and lymphoma cell migration, survival, and proliferation. The supportive tumor cell-microenvironment interactions and the resulting cellular processes require adaptations and modulations of the cytoskeleton. The Rac subfamily of the Rho family GTPases includes key regulators of the cytoskeleton, with essential functions in both normal and transformed leukocytes. Rac proteins function downstream of receptor tyrosine kinases, chemokine receptors, and integrins, orchestrating a multitude of signals arising from the microenvironment. As such, it is not surprising that deregulation of Rac expression and activation plays a role in the development and progression of hematological malignancies. In this review, we will give an overview of the specific contribution of the deregulation of Rac GTPases in hematologic malignancies.
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Affiliation(s)
- Valerie Durand-Onaylı
- Department of Internal Medicine III with Hematology, Medical Oncology, Hemostaseology, Infectious Disease, Rheumatology, Oncologic Center, Salzburg Cancer Research Institute-Laboratory for Immunological and Molecular Cancer Research (SCRI-LIMCR), Paracelsus Medical University, Cancer Cluster Salzburg, 5020 Salzburg, Austria.
| | - Theresa Haslauer
- Department of Internal Medicine III with Hematology, Medical Oncology, Hemostaseology, Infectious Disease, Rheumatology, Oncologic Center, Salzburg Cancer Research Institute-Laboratory for Immunological and Molecular Cancer Research (SCRI-LIMCR), Paracelsus Medical University, Cancer Cluster Salzburg, 5020 Salzburg, Austria.
| | - Andrea Härzschel
- Department of Internal Medicine III with Hematology, Medical Oncology, Hemostaseology, Infectious Disease, Rheumatology, Oncologic Center, Salzburg Cancer Research Institute-Laboratory for Immunological and Molecular Cancer Research (SCRI-LIMCR), Paracelsus Medical University, Cancer Cluster Salzburg, 5020 Salzburg, Austria.
| | - Tanja Nicole Hartmann
- Department of Internal Medicine III with Hematology, Medical Oncology, Hemostaseology, Infectious Disease, Rheumatology, Oncologic Center, Salzburg Cancer Research Institute-Laboratory for Immunological and Molecular Cancer Research (SCRI-LIMCR), Paracelsus Medical University, Cancer Cluster Salzburg, 5020 Salzburg, Austria.
- Department of Hematology, Oncology and Stem Cell Transplantation, Faculty of Medicine and Medical Center, University of Freiburg, 79106 Freiburg, Germany.
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11
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Hall G, Lane BM, Khan K, Pediaditakis I, Xiao J, Wu G, Wang L, Kovalik ME, Chryst-Stangl M, Davis EE, Spurney RF, Gbadegesin RA. The Human FSGS-Causing ANLN R431C Mutation Induces Dysregulated PI3K/AKT/mTOR/Rac1 Signaling in Podocytes. J Am Soc Nephrol 2018; 29:2110-2122. [PMID: 30002222 PMCID: PMC6065096 DOI: 10.1681/asn.2017121338] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 05/31/2018] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND We previously reported that mutations in the anillin (ANLN) gene cause familial forms of FSGS. ANLN is an F-actin binding protein that modulates podocyte cell motility and interacts with the phosphoinositide 3-kinase (PI3K) pathway through the slit diaphragm adaptor protein CD2-associated protein (CD2AP). However, it is unclear how the ANLN mutations cause the FSGS phenotype. We hypothesized that the R431C mutation exerts its pathogenic effects by uncoupling ANLN from CD2AP. METHODS We conducted in vivo complementation assays in zebrafish to determine the effect of the previously identified missense ANLN variants, ANLNR431C and ANLNG618C during development. We also performed in vitro functional assays using human podocyte cell lines stably expressing wild-type ANLN (ANLNWT ) or ANLNR431C . RESULTS Experiments in anln-deficient zebrafish embryos showed a loss-of-function effect for each ANLN variant. In human podocyte lines, expression of ANLNR431C increased cell migration, proliferation, and apoptosis. Biochemical characterization of ANLNR431C -expressing podocytes revealed hyperactivation of the PI3K/AKT/mTOR/p70S6K/Rac1 signaling axis and activation of mTOR-driven endoplasmic reticulum stress in ANLNR431C -expressing podocytes. Inhibition of mTOR, GSK-3β, Rac1, or calcineurin ameliorated the effects of ANLNR431C . Additionally, inhibition of the calcineurin/NFAT pathway reduced the expression of endogenous ANLN and mTOR. CONCLUSIONS The ANLNR431C mutation causes multiple derangements in podocyte function through hyperactivation of PI3K/AKT/mTOR/p70S6K/Rac1 signaling. Our findings suggest that the benefits of calcineurin inhibition in FSGS may be due, in part, to the suppression of ANLN and mTOR. Moreover, these studies illustrate that rational therapeutic targets for familial FSGS can be identified through biochemical characterization of dysregulated podocyte phenotypes.
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Affiliation(s)
- Gentzon Hall
- Departments of Pediatrics and
- Duke Molecular Physiology Institute, Durham, North Carolina; and
- Medicine, Duke University School of Medicine, Durham, North Carolina
| | - Brandon M Lane
- Departments of Pediatrics and
- Duke Molecular Physiology Institute, Durham, North Carolina; and
| | - Kamal Khan
- Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | - Igor Pediaditakis
- Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | - Jianqiu Xiao
- Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | - Guanghong Wu
- Departments of Pediatrics and
- Medicine, Duke University School of Medicine, Durham, North Carolina
| | - Liming Wang
- Medicine, Duke University School of Medicine, Durham, North Carolina
| | - Maria E Kovalik
- Departments of Pediatrics and
- Duke Molecular Physiology Institute, Durham, North Carolina; and
- Medicine, Duke University School of Medicine, Durham, North Carolina
| | - Megan Chryst-Stangl
- Departments of Pediatrics and
- Duke Molecular Physiology Institute, Durham, North Carolina; and
| | - Erica E Davis
- Departments of Pediatrics and
- Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | - Robert F Spurney
- Medicine, Duke University School of Medicine, Durham, North Carolina
| | - Rasheed A Gbadegesin
- Departments of Pediatrics and
- Duke Molecular Physiology Institute, Durham, North Carolina; and
- Medicine, Duke University School of Medicine, Durham, North Carolina
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12
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Abstract
Rho GTPase activating protein 15 (ARHGAP15) is a recently identified GTPase activating protein which enhances intrinsic hydrolysis of GTP-bound Ras-related C3 botulinus toxin substrate (Rac1), resulting in inactivation of Rac1. Although a lot of studies have pointed out the pivotal roles of the Rac1 pathway in the progression of breast carcinomas, the clinical significance of ARHGAP15 has remained largely unknown in human breast carcinomas. Therefore, we immunolocalized ARHGAP15 in one hundred breast carcinoma tissues. ARHGAP15 immunoreactivity was frequently detected in the cytoplasm of carcinoma cells, and was positively correlated with that of Rac1 and androgen receptor labeling index. Furthermore, ARHGAP15 immunoreactivity was significantly correlated with decreased risk of recurrence and improved prognosis, and multivariate analyses demonstrated that ARHGAP15 immunoreactivity was an independent prognostic factor for both disease-free and breast-cancer-specific survival of the patients. In addition, exogenous overexpression of ARHGA15 suppressed cell proliferation and migration of MCF-7 cells and SK-BR-3 cells. On the other hand, ARHGAP15 mRNA was significantly induced by dihydrotestosterone. These findings suggest that ARHGAP15 is an androgen-induced gene and has anti-tumorigenic roles associated with the Rac1 pathway. ARHGAP15 immunoreactivity is therefore considered a potent prognostic factor in human breast carcinomas.
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13
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Arnst JL, Hein AL, Taylor MA, Palermo NY, Contreras JI, Sonawane YA, Wahl AO, Ouellette MM, Natarajan A, Yan Y. Discovery and characterization of small molecule Rac1 inhibitors. Oncotarget 2018; 8:34586-34600. [PMID: 28410221 PMCID: PMC5470993 DOI: 10.18632/oncotarget.16656] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 03/16/2017] [Indexed: 12/18/2022] Open
Abstract
Aberrant activation of Rho GTPase Rac1 has been observed in various tumor types, including pancreatic cancer. Rac1 activates multiple signaling pathways that lead to uncontrolled proliferation, invasion and metastasis. Thus, inhibition of Rac1 activity is a viable therapeutic strategy for proliferative disorders such as cancer. Here we identified small molecule inhibitors that target the nucleotide-binding site of Rac1 through in silico screening. Follow up in vitro studies demonstrated that two compounds blocked active Rac1 from binding to its effector PAK1. Fluorescence polarization studies indicate that these compounds target the nucleotide-binding site of Rac1. In cells, both compounds blocked Rac1 binding to its effector PAK1 following EGF-induced Rac1 activation in a dose-dependent manner, while showing no inhibition of the closely related Cdc42 and RhoA activity. Furthermore, functional studies indicate that both compounds reduced cell proliferation and migration in a dose-dependent manner in multiple pancreatic cancer cell lines. Additionally, the two compounds suppressed the clonogenic survival of pancreatic cancer cells, while they had no effect on the survival of normal pancreatic ductal cells. These compounds do not share the core structure of the known Rac1 inhibitors and could serve as additional lead compounds to target pancreatic cancers with high Rac1 activity.
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Affiliation(s)
- Jamie L Arnst
- Department of Radiation Oncology, University of Nebraska Medical Center Omaha, Nebraska, United States of America.,Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center Omaha, Nebraska, United States of America
| | - Ashley L Hein
- Department of Radiation Oncology, University of Nebraska Medical Center Omaha, Nebraska, United States of America
| | - Margaret A Taylor
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center Omaha, Nebraska, United States of America
| | - Nick Y Palermo
- Holland Computing Center University of Nebraska-Lincoln Omaha, Nebraska, United States of America
| | - Jacob I Contreras
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center Omaha, Nebraska, United States of America
| | - Yogesh A Sonawane
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center Omaha, Nebraska, United States of America
| | - Andrew O Wahl
- Department of Radiation Oncology, University of Nebraska Medical Center Omaha, Nebraska, United States of America
| | - Michel M Ouellette
- Department of Internal Medicine, University of Nebraska Medical Center Omaha, Nebraska, United States of America.,Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center Omaha, Nebraska, United States of America
| | - Amarnath Natarajan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center Omaha, Nebraska, United States of America.,Department of Pharmaceutical Sciences, University of Nebraska Medical Center Omaha, Nebraska, United States of America.,Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center Omaha, Nebraska, United States of America
| | - Ying Yan
- Department of Radiation Oncology, University of Nebraska Medical Center Omaha, Nebraska, United States of America.,Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center Omaha, Nebraska, United States of America
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14
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Yue X, Zhang C, Zhao Y, Liu J, Lin AW, Tan VM, Drake JM, Liu L, Boateng MN, Li J, Feng Z, Hu W. Gain-of-function mutant p53 activates small GTPase Rac1 through SUMOylation to promote tumor progression. Genes Dev 2017; 31:1641-1654. [PMID: 28947497 PMCID: PMC5647935 DOI: 10.1101/gad.301564.117] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 08/21/2017] [Indexed: 11/24/2022]
Abstract
Here, Yue et al. investigated the mechanisms underlying p53 gain-of-function (GOF) mutations and found that mutant p53 activates small GTPase Rac1 as a critical mechanism for mutant p53 GOF to promote tumor progression. Their findings provide insight into a new mechanism for Rac1 activation in tumors and show that activation of Rac1 is an unidentified and critical mechanism for mutant p53 GOF in tumorigenesis. Tumor suppressor p53 is frequently mutated in human cancer. Mutant p53 often promotes tumor progression through gain-of-function (GOF) mechanisms. However, the mechanisms underlying mutant p53 GOF are not well understood. In this study, we found that mutant p53 activates small GTPase Rac1 as a critical mechanism for mutant p53 GOF to promote tumor progression. Mechanistically, mutant p53 interacts with Rac1 and inhibits its interaction with SUMO-specific protease 1 (SENP1), which in turn inhibits SENP1-mediated de-SUMOylation of Rac1 to activate Rac1. Targeting Rac1 signaling by RNAi, expression of the dominant-negative Rac1 (Rac1 DN), or the specific Rac1 inhibitor NSC23766 greatly inhibits mutant p53 GOF in promoting tumor growth and metastasis. Furthermore, mutant p53 expression is associated with enhanced Rac1 activity in clinical tumor samples. These results uncover a new mechanism for Rac1 activation in tumors and, most importantly, reveal that activation of Rac1 is an unidentified and critical mechanism for mutant p53 GOF in tumorigenesis, which could be targeted for therapy in tumors containing mutant p53.
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Affiliation(s)
- Xuetian Yue
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Radiation Oncology, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Cen Zhang
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Radiation Oncology, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Yuhan Zhao
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Radiation Oncology, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Juan Liu
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Radiation Oncology, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Alan W Lin
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Victor M Tan
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Justin M Drake
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Lianxin Liu
- Key Laboratory of Hepatosplenic Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin 150086, China
| | - Michael N Boateng
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Radiation Oncology, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Jun Li
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Radiation Oncology, the State University of New Jersey, New Brunswick, New Jersey 08903, USA
| | - Zhaohui Feng
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Radiation Oncology, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, the State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Wenwei Hu
- Rutgers Cancer Institute of New Jersey, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Radiation Oncology, the State University of New Jersey, New Brunswick, New Jersey 08903, USA.,Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, the State University of New Jersey, Piscataway, New Jersey 08854, USA
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15
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Cabrera M, Echeverria E, Lenicov FR, Cardama G, Gonzalez N, Davio C, Fernández N, Menna PL. Pharmacological Rac1 inhibitors with selective apoptotic activity in human acute leukemic cell lines. Oncotarget 2017; 8:98509-98523. [PMID: 29228706 PMCID: PMC5716746 DOI: 10.18632/oncotarget.21533] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 07/18/2017] [Indexed: 01/01/2023] Open
Abstract
Rac1 GTPase has long been recognized as a critical regulatory protein in different cellular and molecular processes involved in cancer progression, including acute myeloid leukemia. Here we show the antitumoral activity of ZINC69391 and 1A-116, two chemically-related Rac1 pharmacological inhibitors, on a panel of four leukemic cell lines representing different levels of maturation. Importantly, we show that the main mechanism involved in the antitumoral effect triggered by the Rac1 inhibitors comprises the induction of the mitochondrial or intrinsic apoptotic pathway. Interestingly, Rac1 inhibition selectively induced apoptosis on patient-derived leukemia cells but not on normal mononuclear cells. These results show the potential therapeutic benefits of targeting Rac1 pathway in hematopoietic malignancies.
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Affiliation(s)
- Maia Cabrera
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica (ININFA-UBA CONICET), Buenos Aires, Argentina
| | - Emiliana Echeverria
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica (ININFA-UBA CONICET), Buenos Aires, Argentina
| | - Federico Remes Lenicov
- Instituto de Investigaciones Biomédicas en Retrovirus y SIDA, Facultad de Medicina, (INBIRS-UBA-CONICET), Buenos Aires, Argentina
| | - Georgina Cardama
- Laboratorio de Oncología Molecular, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Nazareno Gonzalez
- Laboratorio de Oncología Molecular, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Carlos Davio
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica (ININFA-UBA CONICET), Buenos Aires, Argentina
| | - Natalia Fernández
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica (ININFA-UBA CONICET), Buenos Aires, Argentina
| | - Pablo Lorenzano Menna
- Laboratorio de Oncología Molecular, Universidad Nacional de Quilmes, Buenos Aires, Argentina
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16
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Hein AL, Post CM, Sheinin YM, Lakshmanan I, Natarajan A, Enke CA, Batra SK, Ouellette MM, Yan Y. RAC1 GTPase promotes the survival of breast cancer cells in response to hyper-fractionated radiation treatment. Oncogene 2016; 35:6319-6329. [PMID: 27181206 PMCID: PMC5112160 DOI: 10.1038/onc.2016.163] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 03/08/2016] [Accepted: 03/29/2016] [Indexed: 01/22/2023]
Abstract
Radiation therapy is a staple approach for cancer treatment, whereas radioresistance of cancer cells remains a substantial clinical problem. In response to ionizing radiation (IR) induced DNA-damage, cancer cells can sustain/activate pro-survival signaling pathways, leading to apoptotic resistance and induction of cell cycle checkpoint/DNA repair. Previous studies show that Rac1 GTPase is overexpressed/hyperactivated in breast cancer cells and is associated with poor prognosis. Studies from our laboratory reveal that Rac1 activity is necessary for G2/M checkpoint activation and cell survival in response to IR exposure of breast and pancreatic cancer cells. In the present study, we investigated the effect of Rac1 on the survival of breast cancer cells treated with hyper-fractionated radiation (HFR), which is used clinically for cancer treatment. Results in this report indicate that Rac1 protein expression is increased in the breast cancer cells that survived HFR compared to parental cells. Furthermore, this increase of Rac1 is associated with enhanced activities of ERK1/2 and NF-κB signaling pathways and increased levels of anti-apoptotic protein Bcl-xL and Mcl-1, which are downstream targets of ERK1/2 and NF-κB signaling pathways. Using Rac1 specific inhibitor and dominant negative mutant N17Rac1, here we demonstrate that Rac1 inhibition decreases the phosphorylation of ERK1/2 and IκBα, as well as the levels of Bcl-xL and Mcl-1 protein in the HFR-selected breast cancer cells. Moreover, inhibition of Rac1 using either small molecule inhibitor or dominant negative N17Rac1 abrogates clonogenic survival of HFR-selected breast cancer cells and decreases the level of intact PARP, which is indicative of apoptosis induction. Collectively, results in this report suggest that Rac1 signaling is essential for the survival of breast cancer cells subjected to HFR and implicate Rac1 in radioresistance of breast cancer cells. These studies also provide the basis to explore Rac1 as a therapeutic target for radioresistant breast cancer cells.
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Affiliation(s)
- A L Hein
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
| | - C M Post
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Y M Sheinin
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - I Lakshmanan
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - A Natarajan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA
| | - C A Enke
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
| | - S K Batra
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - M M Ouellette
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Y Yan
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA.,Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
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17
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Chen L, DeWispelaere A, Dastvan F, Osborne WRA, Blechner C, Windhorst S, Daum G. Smooth Muscle-Alpha Actin Inhibits Vascular Smooth Muscle Cell Proliferation and Migration by Inhibiting Rac1 Activity. PLoS One 2016; 11:e0155726. [PMID: 27176050 PMCID: PMC4866761 DOI: 10.1371/journal.pone.0155726] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 05/03/2016] [Indexed: 12/28/2022] Open
Abstract
Smooth muscle alpha-actin (SMA) is a marker for the contractile, non-proliferative phenotype of adult smooth muscle cells (SMCs). Upon arterial injury, expression of SMA and other structural proteins decreases and SMCs acquire a pro-migratory and proliferative phenotype. To what extent SMA regulates migration and proliferation of SMCs is unclear and putative signaling pathways involved remain to be elucidated. Here, we used lentiviral-mediated gene transfer and siRNA technology to manipulate expression of SMA in carotid mouse SMCs and studied effects of SMA. Overexpression of SMA results in decreased proliferation and migration and blunts serum-induced activation of the small GTPase Rac, but not RhoA. All inhibitory effects of SMA are rescued by expression of a constitutively active Rac1 mutant (V12rac1). Moreover, reduction of SMA expression by siRNA technology results in an increased activation of Rac. Taken together, this study identifies Rac1 as a downstream target for SMA to inhibit SMC proliferation and migration.
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Affiliation(s)
- Lihua Chen
- Department of Surgery and Center for Cardiovascular Biology, University of Washington, Seattle, WA, United States of America
| | - Allison DeWispelaere
- Department of Surgery and Center for Cardiovascular Biology, University of Washington, Seattle, WA, United States of America
| | - Frank Dastvan
- Department of Surgery and Center for Cardiovascular Biology, University of Washington, Seattle, WA, United States of America
| | - William R. A. Osborne
- Department of Pediatrics and Diabetes and Obesity Center of Excellence at the University of Washington, Seattle, WA, United States of America
| | - Christine Blechner
- Department of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Germany
| | - Sabine Windhorst
- Department of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Germany
| | - Guenter Daum
- Department of Surgery and Center for Cardiovascular Biology, University of Washington, Seattle, WA, United States of America
- * E-mail:
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18
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Bichsel KJ, Hammiller B, Trempus CS, Li Y, Hansen LA. The epidermal growth factor receptor decreases Stathmin 1 and triggers catagen entry in the mouse. Exp Dermatol 2016; 25:275-81. [PMID: 26661905 DOI: 10.1111/exd.12921] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2015] [Indexed: 12/29/2022]
Abstract
The epidermal growth factor receptor (EGFR) is necessary for normal involution of hair follicles after the growth phase of anagen, although the mechanisms through which it acts are not well understood. In this report, we used transcriptional profiling of microdissected hair follicles from mice with skin-targeted deletion of Egfr to investigate how EGFR activation triggers catagen. Immunofluorescence for phospho-EGFR in mouse skin revealed increased activation of EGFR in follicular keratinocytes at catagen onset. Consistent with other models of EGFR deficiency, mice with skin-targeted deletion of Egfr (Krt14-Cre(+) /Egfr(fl/fl) ) exhibited a delayed and asynchronous catagen entry. Transcriptional profiling at the time of normal catagen onset at post-natal day (P) 17 revealed increased expression of the mitotic regulator Rcc2 in hair follicles lacking EGFR. Rcc2 protein was strongly immunopositive in the nuclei of control follicular keratinocytes at P16 then rapidly decreased until it was undetectable between P18 and 21. In contrast, Rcc2 expression continued in Egfr mutant follicles throughout this period. Proliferation, measured by bromodeoxyuridine incorporation, was also significantly increased in Egfr mutant follicular keratinocytes compared to controls at P18-21. Similarly, Rcc2-regulated mitotic regulator Stathmin 1 was strikingly reduced in control but not Egfr mutant follicles between P17 and P19. Deletion of Stmn1, in turn, accelerated catagen entry associated with premature cessation of proliferation in the hair follicles. These data reveal EGFR suppression of mitotic regulators including Rcc2 and Stathmin 1 as a mechanism for catagen induction in mouse skin.
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Affiliation(s)
- Kyle J Bichsel
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, USA
| | - Brianna Hammiller
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, USA
| | - Carol S Trempus
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, USA
| | - Yanhua Li
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, USA
| | - Laura A Hansen
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, USA
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19
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Rho GTPases: Novel Players in the Regulation of the DNA Damage Response? Biomolecules 2015; 5:2417-34. [PMID: 26437439 PMCID: PMC4693241 DOI: 10.3390/biom5042417] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 09/02/2015] [Accepted: 09/09/2015] [Indexed: 12/26/2022] Open
Abstract
The Ras-related C3 botulinum toxin substrate 1 (Rac1) belongs to the family of Ras-homologous small GTPases. It is well characterized as a membrane-bound signal transducing molecule that is involved in the regulation of cell motility and adhesion as well as cell cycle progression, mitosis, cell death and gene expression. Rac1 also adjusts cellular responses to genotoxic stress by regulating the activity of stress kinases, including c-Jun-N-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38 kinases as well as related transcription factors. Apart from being found on the inner side of the outer cell membrane and in the cytosol, Rac1 has also been detected inside the nucleus. Different lines of evidence indicate that genotoxin-induced DNA damage is able to activate nuclear Rac1. The exact mechanisms involved and the biological consequences, however, are unclear. The data available so far indicate that Rac1 might integrate DNA damage independent and DNA damage dependent cellular stress responses following genotoxin treatment, thereby coordinating mechanisms of the DNA damage response (DDR) that are related to DNA repair, survival and cell death.
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20
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Inhibition of RAC1 GTPase sensitizes pancreatic cancer cells to γ-irradiation. Oncotarget 2015; 5:10251-70. [PMID: 25344910 PMCID: PMC4279370 DOI: 10.18632/oncotarget.2500] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 09/16/2014] [Indexed: 12/31/2022] Open
Abstract
Radiation therapy is a staple treatment for pancreatic cancer. However, owing to the intrinsic radioresistance of pancreatic cancer cells, radiation therapy often fails to increase survival of pancreatic cancer patients. Radiation impedes cancer cells by inducing DNA damage, which can activate cell cycle checkpoints. Normal cells possess both a G1 and G2 checkpoint. However, cancer cells are often defective in G1 checkpoint due to mutations/alterations in key regulators of this checkpoint. Accordingly, our results show that normal pancreatic ductal cells respond to ionizing radiation (IR) with activation of both checkpoints whereas pancreatic cancer cells respond to IR with G2/M arrest only. Overexpression/hyperactivation of Rac1 GTPase is detected in the majority of pancreatic cancers. Rac1 plays important roles in survival and Ras-mediated transformation. Here, we show that Rac1 also plays a critical role in the response of pancreatic cancer cells to IR. Inhibition of Rac1 using specific inhibitor and dominant negative Rac1 mutant not only abrogates IR-induced G2 checkpoint activation, but also increases radiosensitivity of pancreatic cancer cells through induction of apoptosis. These results implicate Rac1 signaling in the survival of pancreatic cancer cells following IR, raising the possibility that this pathway contributes to the intrinsic radioresistance of pancreatic cancer.
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Lo Vasco VR, Leopizzi M, Della Rocca C. Ezrin-related Phosphoinositide pathway modifies RhoA and Rac1 in human osteosarcoma cell lines. J Cell Commun Signal 2015; 9:55-62. [PMID: 25618778 DOI: 10.1007/s12079-015-0265-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Accepted: 01/16/2015] [Indexed: 11/24/2022] Open
Abstract
Selected Phosphoinositide-specific Phospholipase C (PI-PLC) enzymes occupy the convergence point of the broad range of pathways that promote Rho and Ras GTPase mediated signalling, which also regulate the activation of ezrin, a member of the ezrin-radixin-moesin (ERM) proteins family involved in the metastatic osteosarcoma spread. Previous studies described that in distinct human osteosarcoma cell lines ezrin networks the PI-PLC with complex interplay controlling the expression of the PLC genes, which codify for PI-PLC enzymes. In the present study, we analyzed the expression and the sub-cellular distribution of RhoA and Rac1 respectively after ezrin silencing and after PI-PLC ε silencing, in order to investigate whether ezrin-RhoGTPAses signalling might involve one or more specific PI-PLC isoforms in cultured 143B and Hs888 human osteosarcoma cell lines. In the present experiments, both ezrin and PLCE gene silencing had different effects upon RhoA and Rac1 expression and sub-cellular localization. Displacements of Ezrin and of RhoA localization were observed, probably playing functional roles.
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Affiliation(s)
- V R Lo Vasco
- Organi di Senso Department, Policlinico Umberto I, Faculty of Medicine and Dentistry, Sapienza University, viale del Policlinico 155, 00185, Rome, Italy,
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Bopp A, Wartlick F, Henninger C, Schwarz M, Kaina B, Fritz G. Rac1 promotes diethylnitrosamine (DEN)-induced formation of liver tumors. Carcinogenesis 2015; 36:378-89. [PMID: 25556150 DOI: 10.1093/carcin/bgu323] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
To elucidate the function of the Ras-homologous GTPase Rac1 in hepatocarcinogenesis induced by diethylnitrosamine (DEN), mice lacking hepatic Rac1 expression were treated with DEN and compared to the wild-type (WT). Rac1 knock-out (KO) mice were found to have a lower tumor yield as compared to Rac1 proficient mice. The small-sized tumors formed in the absence of Rac1 lack an activated Ras/Raf/mitogen-activated protein kinase pathway, as indicated by the absence of p-ERK expression. Apparently, Rac1 is required for Ras-driven oncogenic pathways. Moreover, tumors in Rac1 deficient mice were glutamine synthase (GS) negative. They displayed a high number of p-H3-positive and cyclinB1 expressing cells, pointing to a defect in mitotic progression. To elucidate the influence of Rac1 on mechanisms of tumor initiation, acute DEN-induced hepatic stress responses were monitored. Rac1 deficiency caused fairly complex, partially time-dependent, alterations in both basal and/or DEN-induced messenger RNA (mRNA) and protein levels of susceptibility-related genes. Basal protein expression of DNA repair factors Brca1 and DNA repair protein RAD51 homolog (Rad51) and the cell cycle regulatory factor p27 was enhanced in the absence of Rac1. Following DEN treatment, p21 mRNA and protein expression was stimulated independent of the Rac1 status. Lack of Rac1 increased mechanisms of the DNA damage response (DDR), as shown by elevated protein levels of p-ATR, p-p53 and γH2AX 24h after DEN treatment. The data show that Rac1 is essential for DEN-stimulated hepatocarcinogenesis. We hypothesize that it promotes tumor initiation by counteracting the elimination of initiated cells and, moreover, alleviates the outgrowth of transformed cells. Hence, pharmacological targeting of Rac1 could be suitable for chemoprevention.
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Affiliation(s)
- Anita Bopp
- Institute of Toxicology, Heinrich Heine University Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany
| | - Friedrich Wartlick
- Institute of Toxicology, Heinrich Heine University Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany
| | - Christian Henninger
- Institute of Toxicology, Heinrich Heine University Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany
| | - Michael Schwarz
- Institute of Pharmacology and Toxicology, University Tübingen, Wilhelmstrasse 76, D-72074 Tübingen, Germany
| | - Bernd Kaina
- Institute of Toxicology, University Medical Center Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany and
| | - Gerhard Fritz
- Institute of Toxicology, Heinrich Heine University Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany,
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Kim EG, Shin EY. Nuclear Rac1 regulates the bFGF-induced neurite outgrowth in PC12 cells. BMB Rep 2014; 46:617-22. [PMID: 24195795 PMCID: PMC4133861 DOI: 10.5483/bmbrep.2013.46.12.114] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 06/13/2013] [Accepted: 07/02/2013] [Indexed: 01/05/2023] Open
Abstract
Rac1 plays a key role in neurite outgrowth via reorganization of the actin cytoskeleton. The molecular mechanisms underlying Rac1-mediated actin dynamics in the cytosol and plasma membrane have been intensively studied, but the nuclear function of Rac1 in neurite outgrowth has not yet been addressed. Using subcellular fractionation and immunocytochemistry, we sought to explore the role of nuclear Rac1 in neurite outgrowth. bFGF, a strong agonist for neurite outgrowth in PC12 cells, stimulated the nuclear accumulation of an active form of Rac1. Rac1-PBR (Q) mutant, in which six basic residues in the polybasic region at the C-terminus were replaced by glutamine, didn’t accumulate in the nucleus. In comparison with control cells, cells expressing this mutant form of Rac1 displayed a marked defect in extending neurites that was concomitant with reduced expression of MAP2 and MEK-1. These results suggest that Rac1 translocation to the nucleus functionally correlates with bFGF-induced neurite outgrowth. [BMB Reports 2013; 46(12): 617-622]
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Affiliation(s)
| | - Eun-Young Shin
- Department of Biochemistry, College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju 361-763, Korea
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Orgaz JL, Herraiz C, Sanz-Moreno V. Rho GTPases modulate malignant transformation of tumor cells. Small GTPases 2014; 5:e29019. [PMID: 25036871 DOI: 10.4161/sgtp.29019] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Rho GTPases are involved in the acquisition of all the hallmarks of cancer, which comprise 6 biological capabilities acquired during the development of human tumors. The hallmarks include proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis programs, as defined by Hanahan and Weinberg. (1) Controlling these hallmarks are genome instability and inflammation. Emerging hallmarks are reprogramming of energy metabolism and evading immune destruction. To give a different view to the readers, we will not be focusing on invasion, metastasis, or cytoskeletal remodeling, but we will review here how Rho GTPases contribute to other hallmarks of cancer with a special emphasis on malignant transformation.
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Affiliation(s)
- Jose L Orgaz
- Randall Division of Cell and Molecular Biophysics; New Hunt's House; Guy's Campus; King's College London; London, UK
| | - Cecilia Herraiz
- Randall Division of Cell and Molecular Biophysics; New Hunt's House; Guy's Campus; King's College London; London, UK
| | - Victoria Sanz-Moreno
- Randall Division of Cell and Molecular Biophysics; New Hunt's House; Guy's Campus; King's College London; London, UK
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Lopez-Haber C, Kazanietz MG. Cucurbitacin I inhibits Rac1 activation in breast cancer cells by a reactive oxygen species-mediated mechanism and independently of Janus tyrosine kinase 2 and P-Rex1. Mol Pharmacol 2013; 83:1141-54. [PMID: 23478800 DOI: 10.1124/mol.112.084293] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The small GTPase Rac1 has been widely implicated in mammary tumorigenesis and metastasis. Previous studies established that stimulation of ErbB receptors in breast cancer cells activates Rac1 and enhances motility via the Rac-guanine nucleotide exchange factor P-Rex1. As the Janus tyrosine kinase 2 (Jak2)/signal transducer and activator of transcription 3 (Stat3) pathway has been shown to be functionally associated with ErbB receptors, we asked if this pathway could mediate P-Rex1/Rac1 activation in response to ErbB ligands. Here we found that the anticancer agent cucurbitacin I, a Jak2 inhibitor, reduced the activation of Rac1 and motility in response to the ErbB3 ligand heregulin in breast cancer cells. However, Rac1 activation was not affected by Jak2 or Stat3 RNA interference, suggesting that the effect of cucurbitacin I occurs through a Jak2-independent mechanism. Cucurbitacin I also failed to affect the activation of P-Rex1 by heregulin. Subsequent analysis revealed that cucurbitacin I strongly activates RhoA and the Rho effector Rho kinase (ROCK) in breast cancer cells and induces the formation of stress fibers. Interestingly, disruption of the RhoA-ROCK pathway prevented the inhibitory effect of cucurbitacin I on Rac1 activation by heregulin. Lastly, we found that RhoA activation by cucurbitacin I is mediated by reactive oxygen species (ROS). The ROS scavenger N-acetyl L-cysteine and the mitochondrial antioxidant Mito-TEMPO rescued the inhibitory effect of cucurbitacin I on Rac1 activation. In conclusion, these results indicate that ErbB-driven Rac1 activation in breast cancer cells proceeds independently of the Jak2 pathway. Moreover, they established that the inhibitory effect of cucurbitacin I on Rac1 activity involves the alteration of the balance between Rho and Rac.
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Affiliation(s)
- Cynthia Lopez-Haber
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6160, USA
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Matayoshi S, Chiba S, Lin Y, Arakaki K, Matsumoto H, Nakanishi T, Suzuki M, Kato S. Lysophosphatidic acid receptor 4 signaling potentially modulates malignant behavior in human head and neck squamous cell carcinoma cells. Int J Oncol 2013; 42:1560-8. [PMID: 23467751 PMCID: PMC3661186 DOI: 10.3892/ijo.2013.1849] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/08/2013] [Indexed: 12/13/2022] Open
Abstract
Head and neck squamous cell carcinoma (HNSCC) is the sixth most common non-skin cancer worldwide. Despite improvement in therapeutic strategies, the prognosis of advanced HNSCC remains poor. The extacellular lipid mediators known as lysophosphatidic acids (LPAs) have been implicated in tumorigenesis of HNSCC. LPAs activate G-protein-coupled receptors not only in the endothelial differentiation gene (Edg) family (LPA1, LPA2, LPA3) but also in the phylogenetically distant non-Edg family (LPA4, LPA5, LPA6). The distinct roles of these receptor isoforms in HNSCC tumorigenesis have not been clarified. In the present study, we investigated the effect of ectopic expression of LPA4 in SQ-20B, an HNSCC cell line, expressing a trivial level of endogenous LPA4. LPA (18:1) stimulated proliferation of SQ-20B cells, but did not affect proliferation of HEp-2, an SCC cell line expressing higher levels of LPA4, comparable to those of with LPA1. LPA-stimulated proliferation of SQ-20B cells was attenuated by Ki16425 and Rac1 inhibitor, but not by Y-27632. Infection with doxycycline-regulatable adenovirus vector expressing green fluorescent protein-tagged LPA4 (AdvLPA4G) abolished LPA-stimulated proliferation in SQ-20B cells with the accumulation of G2/M-phasic cells. Ectopic LPA4 induction further downregulated proliferation of Ki16425-treated SQ-20B cells, of which downregulation was partially recovered by LPA. Ectopic LPA4 induction also downregulated proliferation of Rac1 inhibitor-treated SQ-20B cells, however, LPA no longer recovered it. Finally, LPA-induced cell motility was suppressed by ectopic LPA4 expression as well as by Ki16425, Rac1 inhibitor or Y-27632. Our data suggest that LPA4 signaling potentially modulates malignant behavior of SQ-20B cells. LPA signaling, which is mediated by both Edg and non-Edg receptors, may be a determinant of malignant behavior of HNSCC and could therefore be a promising therapeutic target.
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Affiliation(s)
- Sen Matayoshi
- Department of Pathology and Cell Biology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa 903-0215, Japan
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Küçük C, Hu X, Iqbal J, Gaulard P, Klinkebiel D, Cornish A, Dave BJ, Chan WC. HACE1 is a tumor suppressor gene candidate in natural killer cell neoplasms. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 182:49-55. [PMID: 23142381 DOI: 10.1016/j.ajpath.2012.09.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 08/29/2012] [Accepted: 09/25/2012] [Indexed: 12/31/2022]
Abstract
HACE1 is an E3 ubiquitin ligase located in 6q21, the genomic region frequently deleted in natural killer (NK) cell malignancies. Here, we report HACE1 as a candidate tumor suppressor gene silenced through a combination of deletion and cytosine phosphate guanine island hypermethylation. We detected deletion of HACE1 in malignant NK cell lines (6 of 9, 67%) and primary biopsies (5 of 15, 33%) by quantitative PCR, with most of the specimen showing cytosine phosphate guanine island hypermethylation in the remaining allele, leading to low mRNA transcription. The ectopic expression of HACE1 in an HACE1-null NK cell line led to apoptosis and G2/M cell cycle arrest. Moreover, HACE1 expression was up-regulated in IL-2-activated normal NK cells and NK cells cocultured with an engineered NK cell target, K562 Clone 9.mbIL21, suggesting its role in the regulation of NK cell homeostasis. In conclusion, HACE1 is another potent tumor suppressor gene located within the 6q21 region, and loss of function of multiple tumor suppressor genes within 6q21 may be a critical determinant of NK cell lymphomagenesis.
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Affiliation(s)
- Can Küçük
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-3135, USA
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Nakanome A, Brydun A, Matsumoto M, Ota K, Funayama R, Nakayama K, Ono M, Shiga K, Kobayashi T, Igarashi K. Bach1 is critical for the transformation of mouse embryonic fibroblasts by RasV12 and maintains ERK signaling. Oncogene 2012; 32:3231-45. [DOI: 10.1038/onc.2012.336] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Revised: 06/07/2012] [Accepted: 06/20/2012] [Indexed: 12/23/2022]
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Gastonguay A, Berg T, Hauser AD, Schuld N, Lorimer E, Williams CL. The role of Rac1 in the regulation of NF-κB activity, cell proliferation, and cell migration in non-small cell lung carcinoma. Cancer Biol Ther 2012; 13:647-56. [PMID: 22549160 DOI: 10.4161/cbt.20082] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The small GTPase Rac1 regulates many cellular processes, including cytoskeletal reorganization, cell migration, proliferation, and survival. Additionally, Rac1 plays a major role in activating NF-κB-mediated transcription. Both Rac1 and NF-κB regulate many properties of the malignant phenotype, including anchorage-independent proliferation and survival, metastasis, and angiogenesis. Despite these findings, the roles of Rac1and NF-κB in non-small cell lung carcinoma, a leading cause of cancer deaths, have not been thoroughly investigated. Here, we compared the effects of Rac1 siRNA to that of the Rac1 inhibitor NSC23766 on multiple features of the NSCLC malignant phenotype, including NF-κB activity. We show that the siRNA-mediated silencing of Rac1 in lung cancer cells results in decreased cell proliferation and migration. The decrease in proliferation was observed in both anchorage-dependent and anchorage-independent assays. Furthermore, cells with decreased Rac1 expression have a slowed progression through the G 1 phase of the cell cycle. These effects induced by Rac1 siRNA correlated with a decrease in NF-κB transcriptional activity. Additionally, inhibition of NF-κB signaling with BAY 11-7082 inhibited proliferation; indicating that the loss of cell proliferation and migration induced by the silencing of Rac1 expression may be attributed in part to loss of NF-κB activity. Interestingly, treatment with the Rac1 inhibitor NSC23766 strongly inhibits cell proliferation, cell cycle progression, and NF-κB activity in lung cancer cells, to an even greater extent than the inhibition induced by Rac1 siRNA. These findings indicate that Rac1 plays an important role in lung cancer cell proliferation and migration, most likely through its ability to promote NF-κB activity, and highlight Rac1 pathways as therapeutic targets for the treatment of lung cancer.
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Affiliation(s)
- Adam Gastonguay
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA
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30
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Yan Y, Greer PM, Cao PT, Kolb RH, Cowan KH. RAC1 GTPase plays an important role in γ-irradiation induced G2/M checkpoint activation. Breast Cancer Res 2012; 14:R60. [PMID: 22494620 PMCID: PMC3446395 DOI: 10.1186/bcr3164] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 12/25/2011] [Accepted: 04/11/2012] [Indexed: 01/06/2023] Open
Abstract
Introduction In response to gamma-irradiation (IR)-induced double-strand DNA breaks, cells undergo cell-cycle arrest, allowing time for DNA repair before reentering the cell cycle. G2/M checkpoint activation involves activation of ataxia telangiectasia mutated (ATM)/ATM- and rad3-related (ATR) kinases and inhibition of Cdc25 phosphatases, resulting in inhibition of Cdc2 kinase and subsequent G2/M cell-cycle arrest. Previous studies from our laboratory showed that the G2/M checkpoint activation after IR exposure of MCF-7 breast cancer cells is dependent on the activation of extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) signaling. In the present studies, we investigated the role of Ras-related C3 botulinum toxin substrate 1 (Rac1) guanosine triphosphatase (GTPase) in IR-induced G2/M checkpoint response and ERK1/2 activation, as well as in cell survival after IR. Methods With Rac1-specific inhibitor, dominant negative mutant Rac1 (N17Rac1) and specific small interfering RNA, the effect of Rac1 on IR-induced G2/M checkpoint response and ERK1/2 activation was examined in human breast cancer cells. In addition, the effect of Rac1 on cell survival after irradiation was assessed by using Rac1-specific inhibitor. Results IR exposure of MCF-7 breast cancer cells was associated with a marked activation of Rac1 GTPase. Furthermore, inhibition of Rac1 by using specific inhibitor, dominant-negative Rac1 mutant, or specific siRNA resulted in attenuation of IR-induced G2/M arrest and concomitant diminution of IR-induced activation of ATM, ATR, Chk1, and Chk2 kinases, as well as phosphorylation of Cdc2-Tyr15. Moreover, Rac1 inhibition or decreased Rac1 expression also abrogated IR-induced phosphorylation of mitogen-activated protein kinase kinase 1 and 2 (MEK1/2) and ERK1/2. Ultimately, inhibition of Rac1 markedly increased cellular sensitivity to IR exposure, which involves induction of apoptosis. Conclusion Studies in this report suggest that Rac1 GTPase plays an essential role in the activation of IR-induced ERK1/2 signaling and subsequent G2/M checkpoint response. Furthermore, results also support a role for Rac1 in promoting cell survival after irradiation treatment.
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Affiliation(s)
- Ying Yan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE, USA.
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Lindsay CR, Lawn S, Campbell AD, Faller WJ, Rambow F, Mort RL, Timpson P, Li A, Cammareri P, Ridgway RA, Morton JP, Doyle B, Hegarty S, Rafferty M, Murphy IG, McDermott EW, Sheahan K, Pedone K, Finn AJ, Groben PA, Thomas NE, Hao H, Carson C, Norman JC, Machesky LM, Gallagher WM, Jackson IJ, Van Kempen L, Beermann F, Der C, Larue L, Welch HC, Ozanne BW, Sansom OJ. P-Rex1 is required for efficient melanoblast migration and melanoma metastasis. Nat Commun 2011; 2:555. [PMID: 22109529 PMCID: PMC3400057 DOI: 10.1038/ncomms1560] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 10/20/2011] [Indexed: 12/15/2022] Open
Abstract
Metastases are the major cause of death from melanoma, a skin cancer that has the fastest rising incidence of any malignancy in the Western world. Molecular pathways that drive melanoblast migration in development are believed to underpin the movement and ultimately the metastasis of melanoma. Here we show that mice lacking P-Rex1, a Rac-specific Rho GTPase guanine nucleotide exchange factor, have a melanoblast migration defect during development evidenced by a white belly. Moreover, these P-Rex1(-/-) mice are resistant to metastasis when crossed to a murine model of melanoma. Mechanistically, this is associated with P-Rex1 driving invasion in a Rac-dependent manner. P-Rex1 is elevated in the majority of human melanoma cell lines and tumour tissue. We conclude that P-Rex1 has an important role in melanoblast migration and cancer progression to metastasis in mice and humans.
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Affiliation(s)
| | - Samuel Lawn
- The Beatson Institute for Cancer Research, Glasgow, UK, G61 1BD
| | | | | | - Florian Rambow
- Centre de Recherche, U1021 INSERM, Institut Curie, Paris, France
| | | | - Paul Timpson
- The Beatson Institute for Cancer Research, Glasgow, UK, G61 1BD
| | - Ang Li
- The Beatson Institute for Cancer Research, Glasgow, UK, G61 1BD
| | | | | | | | - Brendan Doyle
- The Beatson Institute for Cancer Research, Glasgow, UK, G61 1BD
| | - Shauna Hegarty
- School of Medicine Dentistry & Biomedical Science, Queen’s University, Belfast, UK
| | - Mairin Rafferty
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College, Dublin 4, Ireland
| | - Ian G. Murphy
- Department of Surgery, St. Vincent's University Hospital, Dublin, Ireland
| | - Enda W. McDermott
- Department of Surgery, St. Vincent's University Hospital, Dublin, Ireland
| | - Kieran Sheahan
- Department of Surgery, St. Vincent's University Hospital, Dublin, Ireland
| | - Katherine Pedone
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, USA
| | - Alexander J. Finn
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, USA
| | - Pamela A. Groben
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, USA
| | - Nancy E. Thomas
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, USA
| | - Honglin Hao
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, USA
| | - Craig Carson
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, USA
| | - Jim C Norman
- The Beatson Institute for Cancer Research, Glasgow, UK, G61 1BD
| | | | - William M. Gallagher
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College, Dublin 4, Ireland
| | | | - Leon Van Kempen
- McGill University/Jewish General Hospital, Dept of Pathology, Montreal, Quebec, Canada, H3A 2B4
| | | | - Channing Der
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, USA
| | - Lionel Larue
- Centre de Recherche, U1021 INSERM, Institut Curie, Paris, France
| | | | - Brad W. Ozanne
- The Beatson Institute for Cancer Research, Glasgow, UK, G61 1BD
| | - Owen J. Sansom
- The Beatson Institute for Cancer Research, Glasgow, UK, G61 1BD
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Mack NA, Whalley HJ, Castillo-Lluva S, Malliri A. The diverse roles of Rac signaling in tumorigenesis. Cell Cycle 2011; 10:1571-81. [PMID: 21478669 PMCID: PMC3127158 DOI: 10.4161/cc.10.10.15612] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 03/24/2011] [Indexed: 01/20/2023] Open
Abstract
Rac is a member of the Rho family of small GTPases, which act as molecular switches to control a wide array of cellular functions. In particular, Rac signaling has been implicated in the control of cell-cell adhesions, cell-matrix adhesions, cell migration, cell cycle progression and cellular transformation. As a result of its functional diversity, Rac signaling can influence several aspects of tumorigenesis. Consistent with this, in vivo evidence that Rac signaling contributes to tumorigenesis is continuously emerging. Additionally, our understanding of the mechanisms by which Rac signaling is regulated is rapidly expanding and consequently adds to the complexity of how Rac signaling could be modulated during tumorigenesis. Here we review the numerous biological functions and regulatory mechanisms of Rac signaling and discuss how they could influence the different stages of tumorigenesis.
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Gabunia K, Jain S, England RN, Autieri MV. Anti-inflammatory cytokine interleukin-19 inhibits smooth muscle cell migration and activation of cytoskeletal regulators of VSMC motility. Am J Physiol Cell Physiol 2011; 300:C896-906. [PMID: 21209363 DOI: 10.1152/ajpcell.00439.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Vascular smooth muscle cell (VSMC) migration is an important cellular event in multiple vascular diseases, including atherosclerosis, restenosis, and transplant vasculopathy. Little is known regarding the effects of anti-inflammatory interleukins on VSMC migration. This study tested the hypothesis that an anti-inflammatory Th2 interleukin, interleukin-19 (IL-19), could decrease VSMC motility. IL-19 significantly decreased platelet-derived growth factor (PDGF)-stimulated VSMC chemotaxis in Boyden chambers and migration in scratch wound assays. IL-19 significantly decreased VSMC spreading in response to PDGF. To determine the molecular mechanism(s) for these cellular effects, we examined the effect of IL-19 on activation of proteins that regulate VSMC cytoskeletal dynamics and locomotion. IL-19 decreased PDGF-driven activation of several cytoskeletal regulatory proteins that play an important role in smooth muscle cell motility, including heat shock protein-27 (HSP27), myosin light chain (MLC), and cofilin. IL-19 decreased PDGF activation of the Rac1 and RhoA GTPases, important integrators of migratory signals. IL-19 was unable to inhibit VSMC migration nor was able to inhibit activation of cytoskeletal regulatory proteins in VSMC transduced with a constitutively active Rac1 mutant (RacV14), suggesting that IL-19 inhibits events proximal to Rac1 activation. Together, these data are the first to indicate that IL-19 can have important inhibitory effects on VSMC motility and activation of cytoskeletal regulatory proteins. This has important implications for the use of anti-inflammatory cytokines in the treatment of vascular occlusive disease.
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Affiliation(s)
- Khatuna Gabunia
- Dept. of Physiology, Independence Blue Cross Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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Carter BJ, Anklesaria P, Choi S, Engelhardt JF. Redox modifier genes and pathways in amyotrophic lateral sclerosis. Antioxid Redox Signal 2009; 11:1569-86. [PMID: 19187001 PMCID: PMC2842588 DOI: 10.1089/ars.2008.2414] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Enhanced redox-stress caused by neuroinflammation, mitochondria, and NADPH oxidases has been hypothesized to play critical roles in disease progression of amyotrophic lateral sclerosis (ALS). However, distinguishing whether the redox-stress observed in ALS is due to a primary defect in cellular reactive oxygen species metabolism/catabolism, or is a secondary consequence of neuroinflammation, has been difficult and the issue remains a matter of debate. Emerging evidence suggests that defects in genes that regulate NADPH oxidases may account for at least some forms of ALS. NADPH oxidases are key signaling complexes that influence cellular responses to growth factors and cytokines. In this context, NADPH oxidase-derived reactive oxygen species exert spatial control over the redox-dependent activation of certain pro-inflammatory receptors. Understanding the biology of how NADPH oxidases control cell signaling may help to clarify how genetic determinants of ALS lead to dysregulated pro-inflammatory signaling. This review provides a framework for understanding endosomal signaling through NADPH oxidases and potential mechanisms whereby gene defects in various forms of ALS may influence this cellular process and lead to motor neuron degeneration. Lastly, this review discusses past and current efforts to treat ALS using antioxidant therapies, as well as the limitations and advantages of each of these approaches.
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35
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Gieni RS, Hendzel MJ. Actin dynamics and functions in the interphase nucleus: moving toward an understanding of nuclear polymeric actin. Biochem Cell Biol 2009; 87:283-306. [PMID: 19234542 DOI: 10.1139/o08-133] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Actin exists as a dynamic equilibrium of monomers and polymers within the nucleus of living cells. It is utilized by the cell for many aspects of gene regulation, including mRNA processing, chromatin remodelling, and global gene expression. Polymeric actin is now specifically linked to transcription by RNA polymerase I, II, and III. An active process, requiring both actin polymers and myosin, appears to drive RNA polymerase I transcription, and is also implicated in long-range chromatin movement. This type of mechanism brings activated genes from separate chromosomal territories together, and then participates in their compartmentalization near nuclear speckles. Nuclear speckle formation requires polymeric actin, and factors promoting polymerization, such as profilin and PIP2, are concentrated there. A review of the literature shows that a functional population of G-actin cycles between the cytoplasm and the nucleoplasm. Its nuclear concentration is dependent on the cytoplasmic G-actin pool, as well as on the activity of import and export mechanisms and the availability of interactions that sequester it within the nucleus. The N-WASP-Arp2/3 actin polymer-nucleating mechanism functions in the nucleus, and its mediators, including NCK, PIP2, and Rac1, can be found in the nucleoplasm, where they likely influence the kinetics of polymer formation. The actin polymer species produced are tightly regulated, and may take on conformations not easily recognized by phalloidin. Many of the factors that cleave F-actin in the cytoplasm are present at high levels in the nucleoplasm, and are also likely to affect actin dynamics there. The absolute and relative G-actin content in the nucleoplasm and the cytoplasm of a cell contains information about the homeostatic state of that cell. We propose that the cycling of G-actin between the nucleus and cytoplasm represents a signal transduction mechanism that can function through both extremes of global cellular G-actin content. MAL signalling within the serum response factor pathway, when G-actin levels are low, represents a well-studied example of actin functioning in signal transduction. The translocation of NCK into the nucleus, along with G-actin, during dissolution of the cytoskeleton in response to DNA damage represents another instance of a unique signalling mechanism operating when G-actin levels are high.
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Affiliation(s)
- Randall S Gieni
- Cross Cancer Institute and Department of Oncology, Faculty of Medicine, University of Alberta, Edmonton, ABT6G1Z2, Canada
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36
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Caino MC, Meshki J, Kazanietz MG. Hallmarks for senescence in carcinogenesis: novel signaling players. Apoptosis 2009; 14:392-408. [DOI: 10.1007/s10495-009-0316-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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37
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38
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Monteiro HP, Arai RJ, Travassos LR. Protein tyrosine phosphorylation and protein tyrosine nitration in redox signaling. Antioxid Redox Signal 2008; 10:843-89. [PMID: 18220476 DOI: 10.1089/ars.2007.1853] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Reversible phosphorylation of protein tyrosine residues by polypeptide growth factor-receptor protein tyrosine kinases is implicated in the control of fundamental cellular processes including the cell cycle, cell adhesion, and cell survival, as well as cell proliferation and differentiation. During the last decade, it has become apparent that receptor protein tyrosine kinases and the signaling pathways they activate belong to a large signaling network. Such a network can be regulated by various extracellular cues, which include cell adhesion, agonists of G protein-coupled receptors, and oxidants. It is well documented that signaling initiated by receptor protein tyrosine kinases is directly dependent on the intracellular production of oxidants, including reactive oxygen and nitrogen species. Accumulated evidence indicates that the intracellular redox environment plays a major role in the mechanisms underlying the actions of growth factors. Oxidation of cysteine thiols and nitration of tyrosine residues on signaling proteins are described as posttranslational modifications that regulate, positively or negatively, protein tyrosine phosphorylation (PTP). Early observations described the inhibition of PTP activities by oxidants, resulting in increased levels of proteins phosphorylated on tyrosine. Therefore, a redox circuitry involving the increasing production of intracellular oxidants associated with growth-factor stimulation/cell adhesion, oxidative reversible inhibition of protein tyrosine phosphatases, and the activation of protein tyrosine kinases can be delineated.
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Affiliation(s)
- Hugo P Monteiro
- Department of Biochemistry/Molecular Biology and CINTERGEN, Universidade Federal de São Paulo, São Paulo, Brazil.
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39
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Harraz MM, Marden JJ, Zhou W, Zhang Y, Williams A, Sharov VS, Nelson K, Luo M, Paulson H, Schöneich C, Engelhardt JF. SOD1 mutations disrupt redox-sensitive Rac regulation of NADPH oxidase in a familial ALS model. J Clin Invest 2008; 118:659-70. [PMID: 18219391 DOI: 10.1172/jci34060] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 11/28/2007] [Indexed: 11/17/2022] Open
Abstract
Neurodegeneration in familial amyotrophic lateral sclerosis (ALS) is associated with enhanced redox stress caused by dominant mutations in superoxide dismutase-1 (SOD1). SOD1 is a cytosolic enzyme that facilitates the conversion of superoxide (O(2)(*-)) to H(2)O(2). Here we demonstrate that SOD1 is not just a catabolic enzyme, but can also directly regulate NADPH oxidase-dependent (Nox-dependent) O(2)(*-) production by binding Rac1 and inhibiting its GTPase activity. Oxidation of Rac1 by H(2)O(2) uncoupled SOD1 binding in a reversible fashion, producing a self-regulating redox sensor for Nox-derived O(2)(*-) production. This process of redox-sensitive uncoupling of SOD1 from Rac1 was defective in SOD1 ALS mutants, leading to enhanced Rac1/Nox activation in transgenic mouse tissues and cell lines expressing ALS SOD1 mutants. Glial cell toxicity associated with expression of SOD1 mutants in culture was significantly attenuated by treatment with the Nox inhibitor apocynin. Treatment of ALS mice with apocynin also significantly increased their average life span. This redox sensor mechanism may explain the gain-of-function seen with certain SOD1 mutations associated with ALS and defines new therapeutic targets.
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Affiliation(s)
- Maged M Harraz
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA
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40
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Jin S, Ray RM, Johnson LR. Rac1 mediates intestinal epithelial cell apoptosis via JNK. Am J Physiol Gastrointest Liver Physiol 2006; 291:G1137-47. [PMID: 16798728 DOI: 10.1152/ajpgi.00031.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Apoptosis plays a key role in the maintenance of a constant cell number and a low incidence of cancer in the mucosa of the intestine. Although the small GTPase Rac1 has been established as an important regulator of migration of intestinal epithelial cells, whether Rac1 is also involved in apoptosis is unclear. The present study tested the hypothesis that Rac1 mediates TNF-alpha-induced apoptosis in IEC-6 cells. Rac1 is activated during TNF-alpha-induced apoptosis as judged by the level of GTP-Rac1, the level of microsomal membrane-associated Rac1, and lamellipodia formation. Although expression of constitutively active Rac1 does not increase apoptosis in the basal condition, inhibition of Rac1 either by NSC-23766 (Rac1 inhibitor) or expression of dominant negative Rac1 protects cells from TNF-alpha-induced apoptosis by inhibiting caspase-3, -8, and -9 activities. Inhibition of Rac1 before the administration of apoptotic stimuli significantly prevents TNF-alpha-induced activation of JNK1/2, the key proapoptotic regulator in IEC-6 cells. Inhibition of Rac1 does not modulate TNF-alpha-induced ERK1/2 and Akt activation. Inhibition of ERK1/2 and Akt activity by U-0126 and LY-294002, respectively, increased TNF-alpha-induced apoptosis. However, inhibition of Rac1 significantly decreased apoptosis in the presence of ERK1/2 and Akt inhibitors, similar to the effect observed with NSC-23766 alone in response to TNF-alpha. Thus, Rac1 inhibition protects cells independently of ERK1/2 and Akt activation during TNF-alpha-induced apoptosis. Although p38 MAPK is activated in response to TNF-alpha, inhibition of p38 MAPK did not decrease apoptosis. Rac1 inhibition did not alter p38 MAPK activity. Thus, these results indicate that Rac1 mediates apoptosis via JNK and plays a key role in proapoptotic pathways in intestinal epithelial cells.
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Affiliation(s)
- Shi Jin
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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41
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Abstract
Members of the Rho family of small GTPases are crucial regulators of biological responses in eukaryotic cells, including cytoskeletal dynamics, cell motility and cell cycle progression. In the present review, we summarize our current understanding of the role of Rho proteins in cell cycle control, highlighting the contribution of specific members of the Rho family and their downstream targets to the regulation of key elements from the core cell cycle machinery, mostly involved in the G1/S transition.
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Affiliation(s)
- Priam Villalonga
- Ludwig Institute for Cancer Research and Department of Biochemistry and Molecular Biology, University College London, London, UK
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42
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Vallim MA, Nichols CB, Fernandes L, Cramer KL, Alspaugh JA. A Rac homolog functions downstream of Ras1 to control hyphal differentiation and high-temperature growth in the pathogenic fungus Cryptococcus neoformans. EUKARYOTIC CELL 2005; 4:1066-78. [PMID: 15947199 PMCID: PMC1151989 DOI: 10.1128/ec.4.6.1066-1078.2005] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The Cryptococcus neoformans Ras1 protein serves as a central regulator for several signaling pathways. Ras1 controls the induction of the mating pheromone response cascade as well as a distinct signaling pathway that allows this pathogenic fungus to grow at human physiological temperature. To characterize elements of the Ras1-dependent high-temperature growth pathway, we performed a multicopy suppressor screen, identifying genes whose overexpression allows the ras1 mutant to grow at 37 degrees C. Using this genetic technique, we identified a C. neoformans gene encoding a Rac homolog that suppresses multiple ras1 mutant phenotypes. Deletion of the RAC1 gene does not affect high-temperature growth. However, a rac1 mutant strain demonstrates a profound defect in haploid filamentation as well as attenuated mating. In a yeast two-hybrid assay, Rac1 physically interacts with the PAK kinase Ste20, which similarly regulates hyphal formation in this fungus. Similar to Rac1, overexpression of the STE20alpha gene also restores high-temperature growth to the ras1 mutant. These results support a model in which the small G protein Rac1 acts downstream of Ras proteins and coordinately with Ste20 to control high-temperature growth and cellular differentiation in this human fungal pathogen.
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Affiliation(s)
- Marcelo A Vallim
- Department of Medicine, Duke University Medical Center (DUMC) 3355, Durham, NC 27710, USA
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43
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Autieri MV, Chen X. The ability of AIF-1 to activate human vascular smooth muscle cells is lost by mutations in the EF-hand calcium-binding region. Exp Cell Res 2005; 307:204-11. [PMID: 15922740 DOI: 10.1016/j.yexcr.2005.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Revised: 02/28/2005] [Accepted: 03/01/2005] [Indexed: 12/01/2022]
Abstract
Allograft Inflammatory Factor-1 (AIF-1) is a cytoplasmic calcium-binding protein expressed in vascular smooth muscle cells (VSMC) in response to injury or cytokine stimulation. AIF-1 contains a partially conserved EF-hand calcium-binding domain, and participates in VSMC activation by activation of Rac1 and induction of Granulocyte-Colony Stimulating Factor (G-CSF) expression; however, the mechanism whereby AIF-1 mediates these effects is presently uncharacterized. To determine if calcium binding plays a functional role in AIF-1 activity, a single site-specific mutation was made in the EF-hand calcium-binding domain to abrogate binding of calcium (AIF-1DeltaA), which was confirmed by calcium overlay. Functionally, similar to wild-type AIF-1, AIF-1DeltaA was able to polymerize F-actin in vitro. However, in contrast to wild-type AIF-1, over-expression of AIF-1DeltaA was unable to increase migration or proliferation of primary human VSMC. Further, it was unable to activate Rac1, or induce G-CSF expression to the degree as wild-type AIF-1. Taken together, modification of the wild-type EF-hand domain and native calcium-binding activity results in a loss of AIF-1 function. We conclude that appropriate calcium-binding potential is critical in AIF-1-mediated effects on VSMC pathophysiology, and that AIF-1 activity is mediated by Rac1 activation and G-CSF expression.
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Affiliation(s)
- Michael V Autieri
- Department of Physiology, Cardiovascular Research Center, Temple University School of Medicine, Room 810, MRB 3420 N. Broad Street, Philadelphia PA 19140, USA.
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44
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Matos P, Jordan P. Expression of Rac1b stimulates NF-kappaB-mediated cell survival and G1/S progression. Exp Cell Res 2005; 305:292-9. [PMID: 15817154 DOI: 10.1016/j.yexcr.2004.12.029] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Revised: 12/10/2004] [Accepted: 12/16/2004] [Indexed: 10/25/2022]
Abstract
The small GTPase Rac1 can stimulate various signaling pathways following a tightly controlled GDP-GTP exchange. A splicing variant designated Rac1b was found to exist predominantly in the active GTP-bound state but the functional consequences of its expression remain unknown. Here we used mouse fibroblasts as a model to assess the signaling properties of Rac1b. We show that, in contrast to Rac1, expression of wild-type Rac1b is sufficient to stimulate cyclin D1 accumulation and G1/S progression in these cells. Moreover, expression of wild-type Rac1b, but not of wild-type Rac1, dramatically increased cell survival in the presence of only minimal growth stimuli. Both cellular responses were blocked by the NF-kappaB super-repressor IkappaBalpha(A32A36). Active Rac1b induced the phosphorylation and membrane translocation of IkappaBalpha, a prerequisite for the activation of NF-kappaB. These data demonstrate that Rac1b is a highly active Rac1 variant that stimulates cell cycle progression and cell survival in pathways involving NF-kappaB.
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Affiliation(s)
- Paulo Matos
- Centro de Genética Humana, Instituto Nacional de Saúde Dr. Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal
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45
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Yang C, Liu Y, Leskow FC, Weaver VM, Kazanietz MG. Rac-GAP-dependent inhibition of breast cancer cell proliferation by {beta}2-chimerin. J Biol Chem 2005; 280:24363-70. [PMID: 15863513 DOI: 10.1074/jbc.m411629200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
beta2-Chimerin is a member of the "non-protein kinase C" intracellular receptors for the second messenger diacylglycerol and the phorbol esters that is yet poorly characterized, particularly in the context of signaling pathways involved in proliferation and cancer progression. beta2-Chimerin possesses a C-terminal Rac-GAP (GTPase-activating protein) domain that accelerates the hydrolysis of GTP from the Rac GTPase, leading to its inactivation. We found that beta2-chimerin messenger levels are significantly down-regulated in human breast cancer cell lines as well as in breast tumors. Adenoviral delivery of beta2-chimerin into MCF-7 breast cancer cells leads to inhibition of proliferation and G(1) cell cycle arrest. Mechanistic studies show that the effect involves the reduction in Rac-GTP levels, cyclin D1 expression, and retinoblastoma dephosphorylation. Studies using the mutated forms of beta2-chimerin revealed that these effects were entirely dependent on its C-terminal GAP domain and Rac-GAP activity. Moreover, MCF-7 cells stably expressing active Rac (V12Rac1) but not RhoA (V14RhoA) were insensitive to beta2-chimerin-induced inhibition of proliferation and cell cycle progression. The modulation of G(1)/S progression by beta2-chimerin not only implies an essential role for Rac in breast cancer cell proliferation but also raises the intriguing possibility that diacylglycerol-regulated non-protein kinase C pathways can negatively impact proliferation mechanisms controlled by Rho GTPases.
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Affiliation(s)
- Chengfeng Yang
- Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6160, USA
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46
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Patil S, Bunderson M, Wilham J, Black SM. Important role for Rac1 in regulating reactive oxygen species generation and pulmonary arterial smooth muscle cell growth. Am J Physiol Lung Cell Mol Physiol 2004; 287:L1314-22. [PMID: 15377495 DOI: 10.1152/ajplung.00383.2003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vascular NADPH oxidases have been shown to be a major source of reactive oxygen species (ROS). Recent studies have also implicated ROS in the proliferation of vascular smooth muscle cells. However, the components required for activation of the NADPH oxidase complex have not been clearly elucidated. Here we demonstrate that ROS generation in ovine pulmonary arterial smooth muscle cells (PASMCs) requires the activation of Rac1, implicating this protein as an important subunit of the NADPH oxidase complex. Our results, using a geranylgeranyl transferase inhibitor (GGTI-287), demonstrated a dose-dependent inhibition of Rac1 activity and ROS production. This was associated with an inhibition of PASMC proliferation with an arrest at G2/M. The inhibition of Rac1 by GGTI-287 led us to more specifically target Rac1 to investigate its role in the generation of ROS and cellular proliferation. To accomplish this, we utilized a dominant negative Rac1 (N17Rac1) and a constitutively active Rac1 (V12Rac1). These two forms of Rac1 were transiently expressed in PASMCs using adenovirus-mediated gene transfer. N17Rac1 expression resulted in decreased cellular Rac1 activity, whereas V12Rac1 infection showed increased activity. Compared with controls, the V12Rac1-expressing cells had higher levels of ROS production and increased proliferation, whereas the N17Rac1-expressing cells had decreased ROS generation and proliferation and cell cycle arrest at G2/M. However, the inhibition of cell growth produced by N17Rac1 overexpression could be overcome if cells were co-incubated with the Cu,Zn superoxide dismutase inhibitor DETC. These results indicate the importance of Rac1 in ROS generation and proliferation of vascular smooth muscle cells.
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Affiliation(s)
- Sandip Patil
- Department of Pediatrics, Northwestern University, Chicago, Illinois 60611, USA
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47
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Sakata Y, Xiang F, Chen Z, Kiriyama Y, Kamei CN, Simon DI, Chin MT. Transcription Factor CHF1/Hey2 Regulates Neointimal Formation In Vivo and Vascular Smooth Muscle Proliferation and Migration In Vitro. Arterioscler Thromb Vasc Biol 2004; 24:2069-74. [PMID: 15345511 DOI: 10.1161/01.atv.0000143936.77094.a4] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Objective—
To determine the role of the cardiovascular-restricted, hairy-related bHLH transcription factor, CHF1/Hey2, in the biological response to vascular injury.
Methods and Results—
We investigated the response of CHF1/Hey2-deficient mice to vascular injury in vivo and the response of primary cultured vascular smooth muscle cells (VSMCs) from these mice to growth factors in vitro. Neointima formation after arterial wire injury is decreased in knockout (KO) compared with wild-type (WT) mice (0.025±0.011 mm
2
in WT [n=13]) versus 0.016±0.008 mm
2
in KO (n=12;
P
<0.05) and is accompanied by reduced cellular proliferation. CHF1/Hey2-deficient VSMCs proliferate slowly compared with WT VSMCs and also show decreased migration in response to platelet-derived growth factor (PDGF) (62.6±10.3 CPF versus 37.2±13.5 CPF;
P
<0.01) and heparin-binding epidermal growth factor-like growth factor (HB-EGF) (27.4±7.7 CPF versus 6.4±3.7 CPF,
P
<0.05). Furthermore, lamellipodia formation and membrane ruffling induced by these chemoattractants are diminished in KO VSMCs, which is correlated with decreased activation of the small GTPase Rac1. Although total Rac1 protein was not changed in KO VSMCs, the level of the Rac guanine exchange factor (GEF), Sos1, was decreased.
Conclusions—
CHF1/Hey2 is an important regulator of vascular smooth muscle cell (VSMC) accumulation during vascular remodeling and responsiveness to growth factors in vitro.
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MESH Headings
- Animals
- Basic Helix-Loop-Helix Transcription Factors
- Cell Movement/physiology
- Cell Proliferation
- Cells, Cultured
- Chemotaxis/physiology
- Cytoskeleton/metabolism
- Enzyme Activation/physiology
- Femoral Artery/chemistry
- Femoral Artery/metabolism
- Femoral Artery/pathology
- Femoral Artery/surgery
- Heparin-binding EGF-like Growth Factor
- Intercellular Signaling Peptides and Proteins
- Mice
- Mice, Inbred C57BL
- Mice, Inbred Strains
- Mice, Knockout
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Mutation/genetics
- Mutation/physiology
- Myocytes, Smooth Muscle/chemistry
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/pathology
- Neovascularization, Pathologic/pathology
- Platelet-Derived Growth Factor/metabolism
- Receptors, Cell Surface/metabolism
- Repressor Proteins/genetics
- Repressor Proteins/physiology
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transcription Factors/physiology
- Tunica Intima/growth & development
- Tunica Intima/pathology
- rac1 GTP-Binding Protein/metabolism
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Affiliation(s)
- Yasuhiko Sakata
- Vascular Medicine Research, Brigham and Women's Hospital, Cambridge, Mass 02139, USA
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48
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Cai J, Weiss ML, Rao MS. In search of "stemness". Exp Hematol 2004; 32:585-98. [PMID: 15246154 PMCID: PMC3279197 DOI: 10.1016/j.exphem.2004.03.013] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2004] [Revised: 03/22/2004] [Accepted: 03/25/2004] [Indexed: 01/02/2023]
Abstract
Stem cells have been identified and characterized in a variety of tissues. In this review we examine possible shared properties of stem cells. We suggest that irrespective of their lineal origin, stem cells have to respond in similar ways to regulate self-renewal and differentiation and it is likely that cell-cycle control, asymmetry/differentiation controls, cellular protective and DNA repair mechanisms, and associated apoptosis/senescence signaling pathways all might be expected to be more highly regulated in stem cells, likely by similar mechanisms. We review the literature to suggest a set of candidate stemness genes that may serve as universal stem cell markers. While we predict many similarities, we also predict that differences will exist between stem cell populations and that when transdifferentiation is considered genes expected to be both similar and different need to be examined.
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Affiliation(s)
- Jingli Cai
- Gerontology Research Center, Stem Cell Biology Unit/Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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49
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Uhlenbrock K, Eberth A, Herbrand U, Daryab N, Stege P, Meier F, Friedl P, Collard JG, Ahmadian MR. The RacGEF Tiam1 inhibits migration and invasion of metastatic melanoma via a novel adhesive mechanism. J Cell Sci 2004; 117:4863-71. [PMID: 15340013 DOI: 10.1242/jcs.01367] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rho-like GTPases such as RhoA, Rac1 and Cdc42 are key regulators of actin-dependent cell functions including cell morphology, adhesion and migration. Tiam1 (T lymphoma invasion and metastasis 1), a guanine nucleotide exchange factor that activates Rac, is an important regulator of cell shape and invasiveness in epithelial cells and fibroblasts. Overexpression of Tiam1 in metastatic melanoma cells converted the constitutive mesenchymal phenotype into an epithelial-like phenotype. This included the induction of stringent cell-cell contacts mediated by the Ig-like receptor ALCAM (activated leukocyte cell adhesion molecule) and actin redistribution to cell-cell junctions. This phenotypic switch was dependent on increased Rac but not Rho activity, and on the redistribution and adhesive function of ALCAM, whereas cadherins were not involved. Although cell proliferation was significantly enhanced, the gain of cell-cell junctions strongly counteracted cell motility and invasion as shown for two- and three-dimensional collagen assays as well as invasion into human skin reconstructs. The reverse transition from mesenchymal invasive to a resident epithelial-like phenotype implicates a role for Tiam1/Rac signaling in the control of cell-cell contacts through a novel ALCAM-mediated mechanism.
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Affiliation(s)
- Katharina Uhlenbrock
- Department of Structural Biology, Max-Planck-Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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50
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Shafer SH, Williams CL. Elevated Rac1 activity changes the M3 muscarinic acetylcholine receptor-mediated inhibition of proliferation to induction of cell death. Mol Pharmacol 2004; 65:1080-91. [PMID: 15102936 DOI: 10.1124/mol.65.5.1080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although muscarinic acetylcholine receptors (mAChRs) regulate proliferation in many cell types, the signaling pathways involved are unclear. The participation of the small GTPases Rac1 and RhoA in M(3) mAChR-mediated inhibition of proliferation was investigated by activating M(3) mAChRs stably transfected in Chinese hamster ovary cells stably coexpressing hemagglutinin (HA)-tagged wild-type or mutant Rac1 or RhoA proteins. Activation of M(3) mAChRs activates both Rac1 and RhoA and inhibits cell proliferation in all cell lines tested. mAChR-mediated inhibition of proliferation is diminished in cells expressing dominant-negative HA-Rac1(Asn17) (m3DNRac) but is enhanced in cells expressing HA-Rac1 (m3WTRac) or constitutively active HA-Rac(Val12) (m3CARac). The activation of mAChRs in m3WTRac and m3CARac cells also induces apoptosis. Expression of wild-type or mutant RhoA proteins does not alter mAChR-mediated inhibition of proliferation. mAChR-induced inhibition of proliferation is abrogated in all cell lines when Galpha(q/11) signaling is terminated by transient expression of the COOH-terminal fragment of phospholipase C (PLC-beta1ct), the NH(2)-terminal fragment of G protein-coupled receptor kinase, or the regulator of G protein signaling 2. Pretreatment of all cells expressing wild-type or mutant Rac1 proteins with edelfosine, a phosphatidylinositol-specific PLC inhibitor, or Go 6976, which inhibits conventional protein kinase C (PKC) isoforms, diminishes the M(3) mAChR's ability to inhibit proliferation. Our results identify Galpha(q/11), PLC, and PKC as participants in the M(3) mAChR-mediated inhibition of cell proliferation. These findings indicate that in the context of high Rac1 activity, but not RhoA activity, M(3) mAChR-mediated activation of these participants triggers cell death.
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Affiliation(s)
- Shulamith H Shafer
- Molecular Pharmacology Laboratory, One Guthrie Square, Sayre, PA 18840, USA
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