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Zheng CW, Zeng RJ, Xu LY, Li EM. Rho GTPases: Promising candidates for overcoming chemotherapeutic resistance. Cancer Lett 2020; 475:65-78. [PMID: 31981606 DOI: 10.1016/j.canlet.2020.01.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 01/17/2020] [Accepted: 01/17/2020] [Indexed: 02/06/2023]
Abstract
Despite therapeutic advances, resistance to chemotherapy remains a major challenge to patients with malignancies. Rho GTPases are essential for the development and progression of various diseases including cancer, and a vast number of studies have linked Rho GTPases to chemoresistance. Therefore, understanding the underlying mechanisms can expound the effects of Rho GTPases towards chemotherapeutic agents, and targeting Rho GTPases is a promising strategy to downregulate the chemo-protective pathways and overcome chemoresistance. Importantly, exceptions in certain biological conditions and interactions among the members of Rho GTPases should be noted. In this review, we focus on the role of Rho GTPases, particularly Rac1, in regulating chemoresistance and provide an overview of their related mechanisms and available inhibitors, which may offer novel options for future targeted cancer therapy.
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Affiliation(s)
- Chun-Wen Zheng
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, 515041, China; The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, 515041, China
| | - Rui-Jie Zeng
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, 515041, China; The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, 515041, China
| | - Li-Yan Xu
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, 515041, China; Institute of Oncologic Pathology, Shantou University Medical College, Shantou, 515041, China.
| | - En-Min Li
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, 515041, China; The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, 515041, China.
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Hazar-Rethinam M, de Long LM, Gannon OM, Boros S, Vargas AC, Dzienis M, Mukhopadhyay P, Saenz-Ponce N, Dantzic DDE, Simpson F, Saunders NA. RacGAP1 Is a Novel Downstream Effector of E2F7-Dependent Resistance to Doxorubicin and Is Prognostic for Overall Survival in Squamous Cell Carcinoma. Mol Cancer Ther 2015; 14:1939-50. [PMID: 26018753 DOI: 10.1158/1535-7163.mct-15-0076] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/15/2015] [Indexed: 11/16/2022]
Abstract
We have previously shown that E2F7 contributes to drug resistance in head and neck squamous cell carcinoma (HNSCC) cells. Considering that dysregulation of responses to chemotherapy-induced cytotoxicity is one of the major reasons for treatment failure in HNSCC, identifying the downstream effectors that regulate E2F7-dependent sensitivity to chemotherapeutic agents may have direct clinical impact. We used transcriptomic profiling to identify candidate pathways that contribute to E2F7-dependent resistance to doxorubicin. We then manipulated the expression of the candidate pathway using overexpression and knockdown in in vitro and in vivo models of SCC to demonstrate causality. In addition, we examined the expression of E2F7 and RacGAP1 in a custom tissue microarray (TMA) generated from HNSCC patient samples. Transcriptomic profiling identified RacGAP1 as a potential mediator of E2F7-dependent drug resistance. We validated E2F7-dependent upregulation of RacGAP1 in doxorubicin-insensitive SCC25 cells. Extending this, we found that selective upregulation of RacGAP1 induced doxorubicin resistance in previously sensitive KJDSV40. Similarly, stable knockdown of RacGAP1 in insensitive SCC25 cells induced sensitivity to doxorubicin in vitro and in vivo. RacGAP1 expression was validated in a TMA, and we showed that HNSCCs that overexpress RacGAP1 are associated with a poorer patient overall survival. Furthermore, E2F7-induced doxorubicin resistance was mediated via RacGAP1-dependent activation of AKT. Finally, we show that SCC cells deficient in RacGAP1 grow slower and are sensitized to the cytotoxic actions of doxorubicin in vivo. These findings identify RacGAP1 overexpression as a novel prognostic marker of survival and a potential target to sensitize SCC to doxorubicin.
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Affiliation(s)
- Mehlika Hazar-Rethinam
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Lilia Merida de Long
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Orla M Gannon
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Samuel Boros
- Department of Pathology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Ana Cristina Vargas
- Department of Pathology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Marcin Dzienis
- Department of Medical Oncology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Pamela Mukhopadhyay
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Natalia Saenz-Ponce
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Daniel D E Dantzic
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Fiona Simpson
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Nicholas A Saunders
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia.
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Ota T, Maeda M, Okamoto M, Tatsuka M. Positive regulation of Rho GTPase activity by RhoGDIs as a result of their direct interaction with GAPs. BMC SYSTEMS BIOLOGY 2015; 9:3. [PMID: 25628036 PMCID: PMC4312443 DOI: 10.1186/s12918-015-0143-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 01/13/2015] [Indexed: 11/25/2022]
Abstract
Background Rho GTPases function as molecular switches in many different signaling pathways and control a wide range of cellular processes. Rho GDP-dissociation inhibitors (RhoGDIs) regulate Rho GTPase signaling and can function as both negative and positive regulators. The role of RhoGDIs as negative regulators of Rho GTPase signaling has been extensively investigated; however, little is known about how RhoGDIs act as positive regulators. Furthermore, it is unclear how this opposing role of GDIs influences the Rho GTPase cycle. We constructed ordinary differential equation models of the Rho GTPase cycle in which RhoGDIs inhibit the regulatory activities of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) by interacting with them directly as well as by sequestering the Rho GTPases. Using this model, we analyzed the role of RhoGDIs in Rho GTPase signaling. Results The model constructed in this study showed that the functions of GEFs and GAPs are integrated into Rho GTPase signaling through the interactions of these regulators with GDIs, and that the negative role of GDIs is to suppress the overall Rho activity by inhibiting GEFs. Furthermore, the positive role of GDIs is to sustain Rho activation by inhibiting GAPs under certain conditions. The interconversion between transient and sustained Rho activation occurs mainly through changes in the affinities of GDIs to GAPs and the concentrations of GAPs. Conclusions RhoGDIs positively regulate Rho GTPase signaling primarily by interacting with GAPs and may participate in the switching between transient and sustained signals of the Rho GTPases. These findings enhance our understanding of the physiological roles of RhoGDIs and Rho GTPase signaling. Electronic supplementary material The online version of this article (doi:10.1186/s12918-015-0143-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Takahide Ota
- Division of Tumor Biology, Department of Life Science, Medical Research Institute, Kanazawa Medical University, Uchinada 920-0293, Ishikawa, Japan.
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Lyberopoulou A, Mylonis I, Papachristos G, Sagris D, Kalousi A, Befani C, Liakos P, Simos G, Georgatsou E. MgcRacGAP, a cytoskeleton regulator, inhibits HIF-1 transcriptional activity by blocking its dimerization. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1378-87. [PMID: 23458834 DOI: 10.1016/j.bbamcr.2013.02.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 02/19/2013] [Accepted: 02/21/2013] [Indexed: 01/22/2023]
Abstract
Hypoxia inducible factor-1 (HIF-1), a dimeric transcription factor of the bHLH-PAS family, is comprised of HIF-1α, which is inducible by hypoxia and ARNT or HIF-1β, which is constitutively expressed. HIF-1 is involved in cellular homeostasis under hypoxia, in development and in several diseases affected by oxygen availability, particularly cancer. Since its expression is positively correlated with poor outcome prognosis for cancer patients, HIF-1 is a target for pharmaceutical therapy. We have previously shown that male germ cell Rac GTPase activating protein (MgcRacGAP), a regulator of Rho proteins which are principally involved in cytoskeletal organization, binds to HIF-1α and inhibits its transcriptional activity. In this work, we have explored the mechanism of the MgcRacGAP-mediated HIF-1 inactivation. We show that the Myo domain of MgcRacGAP, which is both necessary and sufficient for HIF-1 repression, binds to the PAS-B domain of HIF-1α. Furthermore MgcRacGAP competes with ARNT for binding to the HIF-1α PAS-B domain, as shown by in vitro binding pull down assays. In mammalian cells, ARNT overexpression can overcome the MgcRacGAP-mediated inhibition and MgcRacGAP binding to HIF-1α in vivo inhibits its dimerization with ARNT. We additionally present results indicating that MgcRacGAP binding to HIF-1α is specific, since it does not affect the transcriptional activity of HIF-2, a close evolutionary relative of HIF-1 also involved in hypoxia regulation and cancer. Our results reveal a new mechanism for HIF-1 transcriptional activity regulation, suggest a novel hypoxia-cytoskeleton link and provide new tools for selective HIF-1 inhibition.
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Raptis L, Arulanandam R, Geletu M, Turkson J. The R(h)oads to Stat3: Stat3 activation by the Rho GTPases. Exp Cell Res 2011; 317:1787-95. [PMID: 21619876 DOI: 10.1016/j.yexcr.2011.05.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 05/09/2011] [Accepted: 05/10/2011] [Indexed: 02/09/2023]
Abstract
The signal transducer and activator of transcription-3 (Stat3) is a member of the STAT family of cytoplasmic transcription factors. Overactivation of Stat3 is detected with high frequency in human cancer and is considered a molecular abnormality that supports the tumor phenotype. Despite concerted investigative efforts, the molecular mechanisms leading to the aberrant Stat3 activation and Stat3-mediated transformation and tumorigenesis are still not clearly defined. Recent evidence reveals a crosstalk close relationship between Stat3 signaling and members of the Rho family of small GTPases, including Rac1, Cdc42 and RhoA. Specifically, Rac1, acting in a complex with the MgcRacGAP (male germ cell RacGAP), promotes tyrosine phosphorylation of Stat3 by the IL6-receptor family/Jak kinase complex, as well as its translocation to the nucleus. Studies have further revealed that the mutational activation of Rac1 and Cdc42 results in Stat3 activation, which occurs in part through the upregulation of IL6 family cytokines that in turn stimulates Stat3 through the Jak kinases. Interestingly, evidence also shows that the engagement of cadherins, cell to cell adhesion molecules, specifically induces a striking increase in Rac1 and Cdc42 protein levels and activity, which in turn results in Stat3 activation. In this review we integrate recent findings clarifying the role of the Rho family GTPases in Stat3 activation in the context of malignant progression.
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Affiliation(s)
- Leda Raptis
- Department of Microbiology and Immunology and Pathology, Queen's University, Kingston, Ontario, Canada.
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Gregory SL, Lorensuhewa N, Saint R. Signalling through the RhoGEF Pebble in Drosophila. IUBMB Life 2010; 62:290-5. [PMID: 20175154 DOI: 10.1002/iub.310] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Small GTPase pathways of the Ras superfamily are implicated in a wide range of signalling processes in animal cells. Small GTPases control pathways by acting as molecular switches. They are converted from an inactive GDP-bound form to an active GTP-bound form by GTP exchange factors (GEFs). The spatial and temporal regulation of GEFs is a major component of the regulation of small GTPases. Here we review the role of the Drosophila RhoGEF, Pebble (the Drosophila ortholog of mammalian ECT2). We discuss its roles in cytokinesis and cell migration, highlighting the diversity with which Rho family signalling pathways operate in biological systems.
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Affiliation(s)
- Stephen L Gregory
- School of Molecular and Biomedical Sciences, The University of Adelaide, Adelaide, South Australia, Australia
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