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Tanim K, Holtzhausen A, Thapa A, Huelse JM, Graham DK, Earp HS. MERTK Inhibition as a Targeted Novel Cancer Therapy. Int J Mol Sci 2024; 25:7660. [PMID: 39062902 PMCID: PMC11277220 DOI: 10.3390/ijms25147660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 07/06/2024] [Accepted: 07/07/2024] [Indexed: 07/28/2024] Open
Abstract
In this issue honoring the contributions of Greg Lemke, the Earp and Graham lab teams discuss several threads in the discovery, action, signaling, and translational/clinical potential of MERTK, originally called c-mer, a member of the TYRO3, AXL, and MERTK (TAM) family of receptor tyrosine kinases. The 30-year history of the TAM RTK family began slowly as all three members were orphan RTKs without known ligands and/or functions when discovered by three distinct alternate molecular cloning strategies in the pre-genome sequencing era. The pace of understanding their physiologic and pathophysiologic roles has accelerated over the last decade. The activation of ligands bridging externalized phosphatidylserine (PtdSer) has placed these RTKs in a myriad of processes including neurodevelopment, cancer, and autoimmunity. The field is ripe for further advancement and this article hopefully sets the stage for further understanding and therapeutic intervention. Our review will focus on progress made through the collaborations of the Earp and Graham labs over the past 30 years.
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Affiliation(s)
- K.M. Tanim
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA; (K.M.T.); (A.T.); (J.M.H.)
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Alisha Holtzhausen
- Lineburger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
| | - Aashis Thapa
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA; (K.M.T.); (A.T.); (J.M.H.)
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Justus M. Huelse
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA; (K.M.T.); (A.T.); (J.M.H.)
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Douglas K. Graham
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA; (K.M.T.); (A.T.); (J.M.H.)
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - H. Shelton Earp
- Lineburger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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2
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Ubil E, Zahid KR. Structure and functions of Mer, an innate immune checkpoint. Front Immunol 2023; 14:1244170. [PMID: 37936688 PMCID: PMC10626544 DOI: 10.3389/fimmu.2023.1244170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/09/2023] [Indexed: 11/09/2023] Open
Abstract
Immunotherapy is a promising therapeutic tool that promotes the elimination of cancerous cells by a patient's own immune system. However, in the clinical setting, the number of cancer patients benefitting from immunotherapy is limited. Identification and targeting of other immune subsets, such as tumor-associated macrophages, and alternative immune checkpoints, like Mer, may further limit tumor progression and therapy resistance. In this review, we highlight the key roles of macrophage Mer signaling in immune suppression. We also summarize the role of pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes in tumor onset and progression and how Mer structure and activation can be targeted therapeutically to alter activation state. Preclinical and clinical studies focusing on Mer kinase inhibition have demonstrated the potential of targeting this innate immune checkpoint, leading to improved anti-tumor responses and patient outcomes.
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Affiliation(s)
- Eric Ubil
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, United States
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3
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Liu Y, Lan L, Li Y, Lu J, He L, Deng Y, Fei M, Lu JW, Shangguan F, Lu JP, Wang J, Wu L, Huang K, Lu B. N-glycosylation stabilizes MerTK and promotes hepatocellular carcinoma tumor growth. Redox Biol 2022; 54:102366. [PMID: 35728303 PMCID: PMC9214875 DOI: 10.1016/j.redox.2022.102366] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 11/25/2022] Open
Abstract
Despite the evidences of elevated expression of Mer tyrosine kinase (MerTK) in multiple human cancers, mechanisms underlying the oncogenic roles of MerTK in hepatocellular carcinoma (HCC) remains undefined. We explored the functional effects of MerTK and N-Glycosylated MerTK on HCC cell survival and tumor growth. Here, we show that MerTK ablation increases reactive oxygen species (ROS) production and promotes the switching from glycolytic metabolism to oxidative phosphorylation in HCC cells, thus suppressing HCC cell proliferation and tumor growth. MerTK is N-glycosylated in HCC cells at asparagine 294 and 454 that stabilizes MerTK to promote oncogenic transformation. Moreover, we observed that nuclear located non-glycosylated MerTK is indispensable for survival of HCC cells under stress. Pathologically, tissue microarray (TMA) data indicate that MerTK is a pivotal prognostic factor for HCC. Our data strongly support the roles of MerTK N-glycosylation in HCC tumorigenesis and suggesting N-glycosylation inhibition as a potential HCC therapeutic strategy. MerTK promotes the switching from oxidative phosphorylation to glycolytic metabolism in HCC cells. MerTK is N-glycosylated in HCC cells at asparagine 294 and 454 that stabilizes MerTK to promote HCC tumor growth. The nuclear located non-glycosylated MerTK is indispensable for survival of HCC cells under stress. MerTK is a pivotal prognostic factor for HCC and its N-glycosylation inhibition is a potential HCC therapeutic strategy.
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Affiliation(s)
- Yongzhang Liu
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Linhua Lan
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China; Key Laboratory of Diagnosis and Treatment of Severe Hepato-Pancreatic Diseases of Zhejiang Province, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Yujie Li
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China; Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China
| | - Jing Lu
- Department of Laboratory Medicine, The First People's Hospital of Jingzhou, The First Affiliated Hospital of Yangtze University, Jingzhou, Hubei, 434000, China
| | - Lipeng He
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China; Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China
| | - Yao Deng
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China; Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China
| | - Mingming Fei
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Jun-Wan Lu
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Fugen Shangguan
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China; Key Laboratory of Diagnosis and Treatment of Severe Hepato-Pancreatic Diseases of Zhejiang Province, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Ju-Ping Lu
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Jiaxin Wang
- Protein Quality Control and Diseases Laboratory, Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China; Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China
| | - Liang Wu
- Department of Pathology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Kate Huang
- Department of Pathology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Bin Lu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China; Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.
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Yan D, Earp HS, DeRyckere D, Graham DK. Targeting MERTK and AXL in EGFR Mutant Non-Small Cell Lung Cancer. Cancers (Basel) 2021; 13:5639. [PMID: 34830794 PMCID: PMC8616094 DOI: 10.3390/cancers13225639] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 12/20/2022] Open
Abstract
MERTK and AXL are members of the TAM family of receptor tyrosine kinases and are abnormally expressed in 69% and 93% of non-small cell lung cancers (NSCLCs), respectively. Expression of MERTK and/or AXL provides a survival advantage for NSCLC cells and correlates with lymph node metastasis, drug resistance, and disease progression in patients with NSCLC. The TAM receptors on host tumor infiltrating cells also play important roles in the immunosuppressive tumor microenvironment. Thus, MERTK and AXL are attractive biologic targets for NSCLC treatment. Here, we will review physiologic and oncologic roles for MERTK and AXL with an emphasis on the potential to target these kinases in NSCLCs with activating EGFR mutations.
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Affiliation(s)
- Dan Yan
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; (D.Y.); (D.D.)
| | - H. Shelton Earp
- UNC Lineberger Comprehensive Cancer Center, Department of Medicine, Chapel Hill, NC 27599, USA;
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Deborah DeRyckere
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; (D.Y.); (D.D.)
| | - Douglas K. Graham
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; (D.Y.); (D.D.)
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5
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Zhou L, Matsushima GK. Tyro3, Axl, Mertk receptor-mediated efferocytosis and immune regulation in the tumor environment. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 361:165-210. [PMID: 34074493 DOI: 10.1016/bs.ircmb.2021.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Three structurally related tyrosine receptor cell surface kinases, Tyro3, Axl, and Mertk (TAM) have been recognized to modulate immune function, tissue homeostasis, cardiovasculature, and cancer. The TAM receptor family appears to operate in adult mammals across multiple cell types, suggesting both widespread and specific regulation of cell functions and immune niches. TAM family members regulate tissue homeostasis by monitoring the presence of phosphatidylserine expressed on stressed or apoptotic cells. The detection of phosphatidylserine on apoptotic cells requires intermediary molecules that opsonize the dying cells and tether them to TAM receptors on phagocytes. This complex promotes the engulfment of apoptotic cells, also known as efferocytosis, that leads to the resolution of inflammation and tissue healing. The immune mechanisms dictating these processes appear to fall upon specific family members or may involve a complex of different receptors acting cooperatively to resolve and repair damaged tissues. Here, we focus on the role of TAM receptors in triggering efferocytosis and its consequences in the regulation of immune responses in the context of inflammation and cancer.
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Affiliation(s)
- Liwen Zhou
- UNC Neuroscience Center, University of North Carolina-CH, Chapel Hill, NC, United States
| | - Glenn K Matsushima
- UNC Neuroscience Center, University of North Carolina-CH, Chapel Hill, NC, United States; UNC Department of Microbiology & Immunology, University of North Carolina-CH, Chapel Hill, NC, United States; UNC Integrative Program for Biological & Genome Sciences, University of North Carolina-CH, Chapel Hill, NC, United States.
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Recent advancements in role of TAM receptors on efferocytosis, viral infection, autoimmunity, and tissue repair. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 357:1-19. [PMID: 33234241 DOI: 10.1016/bs.ircmb.2020.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Evolutionarily conserved highly regulated process of apoptosis has been a major physiological process throughout the entire evolutionary history of living beings that has impacted the process of evolution itself. One of the key features of this highly researched field of science is the process of phosphatidylserine (PS) externalization by the different membrane bound enzymes. The process is a result of series of biological events and is associated with various biological outcomes depending on the proper recognition of this ligand. In this review, we will briefly summarize the recent advancement in the field pertaining to the set of receptors, known as TAM (Tyro3, Axl and Mertk) receptors, for their influence in the recognition of various PS externalization events and mediation of pathological outcomes such as autoimmunity, cancer, and tissue repair.
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Crystal Structure of the Kinase Domain of MerTK in Complex with AZD7762 Provides Clues for Structure-Based Drug Development. Int J Mol Sci 2020; 21:ijms21217878. [PMID: 33114206 PMCID: PMC7660649 DOI: 10.3390/ijms21217878] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 12/17/2022] Open
Abstract
Aberrant tyrosine-protein kinase Mer (MerTK) expression triggers prosurvival signaling and contributes to cell survival, invasive motility, and chemoresistance in many kinds of cancers. In addition, recent reports suggested that MerTK could be a primary target for abnormal platelet aggregation. Consequently, MerTK inhibitors may promote cancer cell death, sensitize cells to chemotherapy, and act as new antiplatelet agents. We screened an inhouse chemical library to discover novel small-molecule MerTK inhibitors, and identified AZD7762, which is known as a checkpoint-kinase (Chk) inhibitor. The inhibition of MerTK by AZD7762 was validated using an in vitro homogeneous time-resolved fluorescence (HTRF) assay and through monitoring the decrease in phosphorylated MerTK in two lung cancer cell lines. We also determined the crystal structure of the MerTK:AZD7762 complex and revealed the binding mode of AZD7762 to MerTK. Structural information from the MerTK:AZD7762 complex and its comparison with other MerTK:inhibitor structures gave us new insights for optimizing the development of inhibitors targeting MerTK.
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Huelse J, Fridlyand D, Earp S, DeRyckere D, Graham DK. MERTK in cancer therapy: Targeting the receptor tyrosine kinase in tumor cells and the immune system. Pharmacol Ther 2020; 213:107577. [PMID: 32417270 PMCID: PMC9847360 DOI: 10.1016/j.pharmthera.2020.107577] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The receptor tyrosine kinase MERTK is aberrantly expressed in numerous human malignancies, and is a novel target in cancer therapeutics. Physiologic roles of MERTK include regulation of tissue homeostasis and repair, innate immune control, and platelet aggregation. However, aberrant expression in a wide range of liquid and solid malignancies promotes neoplasia via growth factor independence, cell cycle progression, proliferation and tumor growth, resistance to apoptosis, and promotion of tumor metastases. Additionally, MERTK signaling contributes to an immunosuppressive tumor microenvironment via induction of an anti-inflammatory cytokine profile and regulation of the PD-1 axis, as well as regulation of macrophage, myeloid-derived suppressor cell, natural killer cell and T cell functions. Various MERTK-directed therapies are in preclinical development, and clinical trials are underway. In this review we discuss MERTK inhibition as an emerging strategy for cancer therapy, focusing on MERTK expression and function in neoplasia and its role in mediating resistance to cytotoxic and targeted therapies as well as in suppressing anti-tumor immunity. Additionally, we review preclinical and clinical pharmacological strategies to target MERTK.
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Affiliation(s)
- Justus Huelse
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, Georgia
| | - Diana Fridlyand
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, Georgia
| | - Shelton Earp
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC
| | - Deborah DeRyckere
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, Georgia
| | - Douglas K. Graham
- Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, Georgia
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Huelse JM, Fridlyand DM, Earp S, DeRyckere D, Graham DK. MERTK in cancer therapy: Targeting the receptor tyrosine kinase in tumor cells and the immune system. Pharmacol Ther 2020. [PMID: 32417270 DOI: 10.1016/j.pharmthera.2020.107577107577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
The receptor tyrosine kinase MERTK is aberrantly expressed in numerous human malignancies, and is a novel target in cancer therapeutics. Physiologic roles of MERTK include regulation of tissue homeostasis and repair, innate immune control, and platelet aggregation. However, aberrant expression in a wide range of liquid and solid malignancies promotes neoplasia via growth factor independence, cell cycle progression, proliferation and tumor growth, resistance to apoptosis, and promotion of tumor metastases. Additionally, MERTK signaling contributes to an immunosuppressive tumor microenvironment via induction of an anti-inflammatory cytokine profile and regulation of the PD-1 axis, as well as regulation of macrophage, myeloid-derived suppressor cell, natural killer cell and T cell functions. Various MERTK-directed therapies are in preclinical development, and clinical trials are underway. In this review we discuss MERTK inhibition as an emerging strategy for cancer therapy, focusing on MERTK expression and function in neoplasia and its role in mediating resistance to cytotoxic and targeted therapies as well as in suppressing anti-tumor immunity. Additionally, we review preclinical and clinical pharmacological strategies to target MERTK.
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Affiliation(s)
- Justus M Huelse
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, GA, USA
| | - Diana M Fridlyand
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, GA, USA
| | - Shelton Earp
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Deborah DeRyckere
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, GA, USA
| | - Douglas K Graham
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, GA, USA.
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Morimoto M, Horikoshi Y, Nakaso K, Kurashiki T, Kitagawa Y, Hanaki T, Sakamoto T, Honjo S, Umekita Y, Fujiwara Y, Matsura T. Oncogenic role of TYRO3 receptor tyrosine kinase in the progression of pancreatic cancer. Cancer Lett 2019; 470:149-160. [PMID: 31765735 DOI: 10.1016/j.canlet.2019.11.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 11/15/2019] [Accepted: 11/18/2019] [Indexed: 01/01/2023]
Abstract
The expression and functions of TYRO3, a member of the TAM receptor tyrosine kinase family, in pancreatic cancer (PC) have not been specifically elucidated. In this study, we confirmed TYRO3 expression in five human PC cell lines (PANC-1, MIA PaCa-2, BxPC-3, AsPC-1, and PK-9) using Western blotting. TYRO3 silencing and overexpression studies have revealed that TYRO3 promotes cell proliferation and invasion in PC via phosphorylation of protein kinase B (Akt) and extracellular signal-regulated kinase (ERK). Using a mouse xenograft model, we showed that tumor growth was significantly suppressed in mice subcutaneously inoculated with TYRO3-knockdown PC cells compared with mice inoculated with control PC cells. Furthermore, TYRO3 expression was examined in PC tissues obtained from 106 patients who underwent pancreatic resection for invasive ductal carcinoma through immunohistochemical staining. TYRO3-positive patients had poor prognoses for overall survival and disease-specific survival compared with TYRO3-negative patients. Multivariate analysis revealed that TYRO3 expression is an independent prognostic factor for overall survival. Our study demonstrates the critical role of TYRO3 in PC progression through Akt and ERK activation and suggests TYRO3 as a novel promising target for therapeutic strategies against PC.
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Affiliation(s)
- Masaki Morimoto
- Division of Medical Biochemistry, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, 683-8503, Japan; Division of Surgical Oncology, Department of Surgery, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Yosuke Horikoshi
- Division of Medical Biochemistry, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, 683-8503, Japan
| | - Kazuhiro Nakaso
- Division of Medical Biochemistry, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, 683-8503, Japan
| | - Tatsuyuki Kurashiki
- Division of Medical Biochemistry, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, 683-8503, Japan; Division of Anesthesiology and Critical Care Medicine, Department of Surgery, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Yoshinori Kitagawa
- Division of Medical Biochemistry, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, 683-8503, Japan; Division of Anesthesiology and Critical Care Medicine, Department of Surgery, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Takehiko Hanaki
- Division of Surgical Oncology, Department of Surgery, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Teruhisa Sakamoto
- Division of Surgical Oncology, Department of Surgery, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Soichiro Honjo
- Division of Surgical Oncology, Department of Surgery, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Yoshihisa Umekita
- Division of Organ Pathology, Department of Pathology, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, 683-8503, Japan
| | - Yoshiyuki Fujiwara
- Division of Surgical Oncology, Department of Surgery, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Tatsuya Matsura
- Division of Medical Biochemistry, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, 683-8503, Japan.
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11
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McDaniel NK, Cummings CT, Iida M, Hülse J, Pearson HE, Vasileiadi E, Parker RE, Orbuch RA, Ondracek OJ, Welke NB, Kang GH, Davies KD, Wang X, Frye SV, Earp HS, Harari PM, Kimple RJ, DeRyckere D, Graham DK, Wheeler DL. MERTK Mediates Intrinsic and Adaptive Resistance to AXL-targeting Agents. Mol Cancer Ther 2018; 17:2297-2308. [PMID: 30093568 PMCID: PMC6215511 DOI: 10.1158/1535-7163.mct-17-1239] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 05/23/2018] [Accepted: 07/31/2018] [Indexed: 12/17/2022]
Abstract
The TAM (TYRO3, AXL, MERTK) family receptor tyrosine kinases (RTK) play an important role in promoting growth, survival, and metastatic spread of several tumor types. AXL and MERTK are overexpressed in head and neck squamous cell carcinoma (HNSCC), triple-negative breast cancer (TNBC), and non-small cell lung cancer (NSCLC), malignancies that are highly metastatic and lethal. AXL is the most well-characterized TAM receptor and mediates resistance to both conventional and targeted cancer therapies. AXL is highly expressed in aggressive tumor types, and patients with cancer are currently being enrolled in clinical trials testing AXL inhibitors. In this study, we analyzed the effects of AXL inhibition using a small-molecule AXL inhibitor, a monoclonal antibody (mAb), and siRNA in HNSCC, TNBC, and NSCLC preclinical models. Anti-AXL-targeting strategies had limited efficacy across these different models that, our data suggest, could be attributed to upregulation of MERTK. MERTK expression was increased in cell lines and patient-derived xenografts treated with AXL inhibitors and inhibition of MERTK sensitized HNSCC, TNBC, and NSCLC preclinical models to AXL inhibition. Dual targeting of AXL and MERTK led to a more potent blockade of downstream signaling, synergistic inhibition of tumor cell expansion in culture, and reduced tumor growth in vivo Furthermore, ectopic overexpression of MERTK in AXL inhibitor-sensitive models resulted in resistance to AXL-targeting strategies. These observations suggest that therapeutic strategies cotargeting both AXL and MERTK could be highly beneficial in a variety of tumor types where both receptors are expressed, leading to improved survival for patients with lethal malignancies. Mol Cancer Ther; 17(11); 2297-308. ©2018 AACR.
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Affiliation(s)
- Nellie K McDaniel
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Christopher T Cummings
- Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplantation, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Mari Iida
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Justus Hülse
- Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta and Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia
| | - Hannah E Pearson
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Eleana Vasileiadi
- Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta and Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia
| | - Rebecca E Parker
- Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta and Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia
| | - Rachel A Orbuch
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Olivia J Ondracek
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Noah B Welke
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Grace H Kang
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Kurtis D Davies
- Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplantation, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Xiaodong Wang
- Center for Integrative Chemical Biology and Drug Discovery and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Stephen V Frye
- Center for Integrative Chemical Biology and Drug Discovery and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Medicine, UNC Lineberger Comprehensive Cancer Center, Chapel Hill, North Carolina
| | - H Shelton Earp
- Department of Medicine, UNC Lineberger Comprehensive Cancer Center, Chapel Hill, North Carolina
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Paul M Harari
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Randall J Kimple
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Deborah DeRyckere
- Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta and Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia
| | - Douglas K Graham
- Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta and Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia.
| | - Deric L Wheeler
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
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Targeting the TAM Receptors in Leukemia. Cancers (Basel) 2016; 8:cancers8110101. [PMID: 27834816 PMCID: PMC5126761 DOI: 10.3390/cancers8110101] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/21/2016] [Accepted: 11/01/2016] [Indexed: 12/20/2022] Open
Abstract
Targeted inhibition of members of the TAM (TYRO-3, AXL, MERTK) family of receptor tyrosine kinases has recently been investigated as a novel strategy for treatment of hematologic malignancies. The physiologic functions of the TAM receptors in innate immune control, natural killer (NK) cell differentiation, efferocytosis, clearance of apoptotic debris, and hemostasis have previously been described and more recent data implicate TAM kinases as important regulators of erythropoiesis and megakaryopoiesis. The TAM receptors are aberrantly or ectopically expressed in many hematologic malignancies including acute myeloid leukemia, B- and T-cell acute lymphoblastic leukemia, chronic lymphocytic leukemia, and multiple myeloma. TAM receptors contribute to leukemic phenotypes through activation of pro-survival signaling pathways and interplay with other oncogenic proteins such as FLT3, LYN, and FGFR3. The TAM receptors also contribute to resistance to both cytotoxic chemotherapeutics and targeted agents, making them attractive therapeutic targets. A number of translational strategies for TAM inhibition are in development, including small molecule inhibitors, ligand traps, and monoclonal antibodies. Emerging areas of research include modulation of TAM receptors to enhance anti-tumor immunity, potential roles for TYRO-3 in leukemogenesis, and the function of the bone marrow microenvironment in mediating resistance to TAM inhibition.
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Kimani SG, Kumar S, Davra V, Chang YJ, Kasikara C, Geng K, Tsou WI, Wang S, Hoque M, Boháč A, Lewis-Antes A, De Lorenzo MS, Kotenko SV, Birge RB. Normalization of TAM post-receptor signaling reveals a cell invasive signature for Axl tyrosine kinase. Cell Commun Signal 2016; 14:19. [PMID: 27595981 PMCID: PMC5011882 DOI: 10.1186/s12964-016-0142-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/26/2016] [Indexed: 12/11/2022] Open
Abstract
Background Tyro3, Axl, and Mertk (TAMs) are a family of three conserved receptor tyrosine kinases that have pleiotropic roles in innate immunity and homeostasis and when overexpressed in cancer cells can drive tumorigenesis. Methods In the present study, we engineered EGFR/TAM chimeric receptors (EGFR/Tyro3, EGFR/Axl, and EGF/Mertk) with the goals to interrogate post-receptor functions of TAMs, and query whether TAMs have unique or overlapping post-receptor activation profiles. Stable expression of EGFR/TAMs in EGFR-deficient CHO cells afforded robust EGF inducible TAM receptor phosphorylation and activation of downstream signaling. Results Using a series of unbiased screening approaches, that include kinome-view analysis, phosphor-arrays, RNAseq/GSEA analysis, as well as cell biological and in vivo readouts, we provide evidence that each TAM has unique post-receptor signaling platforms and identify an intrinsic role for Axl that impinges on cell motility and invasion compared to Tyro3 and Mertk. Conclusion These studies demonstrate that TAM show unique post-receptor signatures that impinge on distinct gene expression profiles and tumorigenic outcomes. Electronic supplementary material The online version of this article (doi:10.1186/s12964-016-0142-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stanley G Kimani
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Sushil Kumar
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Viralkumar Davra
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Yun-Juan Chang
- Rutgers, Biomedical and Health Sciences, OIT/High Performance and Research Computing, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Canan Kasikara
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Ke Geng
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Wen-I Tsou
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Shenyan Wang
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Mainul Hoque
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Genomics Research Program, Rutgers- New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Andrej Boháč
- Department of Organic Chemistry, Comenius University in Bratislava, Faculty of Natural Sciences, Mlynská dolina, Ilkovičova 6, 842 15, Bratislava, Slovakia.,Biomagi, Ltd, Mamateyova 26, 851 04, Bratislava, Slovakia
| | - Anita Lewis-Antes
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Mariana S De Lorenzo
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Sergei V Kotenko
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA
| | - Raymond B Birge
- Rutgers, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, Rutgers- New Jersey Medical School, 205 South Orange Ave, Newark, NJ, 07103, USA.
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Cooper AE, Cho JH, Menges S, Masood S, Xie J, Yang J, Klassen H. Immunosuppressive Treatment Can Alter Visual Performance in the Royal College of Surgeons Rat. J Ocul Pharmacol Ther 2016; 32:296-303. [PMID: 27008099 PMCID: PMC6453503 DOI: 10.1089/jop.2015.0134] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/21/2016] [Indexed: 11/13/2022] Open
Abstract
PURPOSE Immunosuppression is frequently employed to enhance survival of xenografted human cells as part of translational proof-of-concept studies. However, the potential effects of this treatment are easily overlooked. METHODS As part of baseline testing in the dark-eyed variant of the dystrophic Royal College of Surgeons (RCS) rat, we documented the time course of retinal degenerative changes versus Long Evans controls using bright field retinal imaging, fluorescein angiography, and histology and examined the impact of immunosuppression on visual function. Rats received either no treatment or systemic immunosuppression with oral cyclosporine A and injectable dexamethasone and subsequently underwent functional evaluation by optomotor response testing and electroretinography (ERG) at multiple intervals from P45 to P180. RESULTS Immunosuppressed RCS animals demonstrated poorer performance on functional tests than age-matched untreated rats during the earlier stages of degeneration, including significantly lower spatial acuities on optomotor threshold testing and significantly lower b-wave amplitudes on scotopic and photopic ERGs. Retinal imaging documented the progression of degenerative changes in the RCS fundus and histologic evaluation of the RCS retina confirmed progressive thinning of the outer nuclear layer. CONCLUSIONS A standard regimen of cyclosporine A plus dexamethasone, administered to RCS rats, results in demonstrable systemic side effects and depressed scores on behavioral and electrophysiological testing at time points before P90. The source of the functional impairment was not identified. This finding has implications for the interpretation of data generated using this commonly used translational model.
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Affiliation(s)
- Ann E. Cooper
- William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, California
| | - Jang-Hyeon Cho
- Gavin Herbert Eye Institute, Stem Cell Research Center, University of California, Irvine, California
| | - Steven Menges
- Gavin Herbert Eye Institute, Stem Cell Research Center, University of California, Irvine, California
| | - Sahar Masood
- Gavin Herbert Eye Institute, Stem Cell Research Center, University of California, Irvine, California
| | - Jun Xie
- Gavin Herbert Eye Institute, Stem Cell Research Center, University of California, Irvine, California
| | - Jing Yang
- Gavin Herbert Eye Institute, Stem Cell Research Center, University of California, Irvine, California
| | - Henry Klassen
- Gavin Herbert Eye Institute, Stem Cell Research Center, University of California, Irvine, California
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15
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Mer receptor tyrosine kinase is frequently overexpressed in human non-small cell lung cancer, confirming resistance to erlotinib. Oncotarget 2016; 6:9206-19. [PMID: 25826078 PMCID: PMC4496212 DOI: 10.18632/oncotarget.3280] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 02/07/2015] [Indexed: 12/26/2022] Open
Abstract
Mer is a receptor tyrosine kinase (RTK) with oncogenic properties that is often overexpressed or activated in various malignancies. Using both immunohistochemistry and microarray analyses, we demonstrated that Mer was overexpressed in both tumoral and stromal compartments of about 70% of non-small cell lung cancer (NSCLC) samples relative to surrounding normal lung tissue. This was validated in freshly harvested NSCLC samples; however, no associations were found between Mer expression and patient features. Although Mer overexpression did not render normal lung epithelial cell tumorigenic in vivo, it promoted the in vitro cell proliferation, clonogenic colony formation and migration of normal lung epithelial cells as well as NSCLC cells primarily depending on MAPK and FAK signaling, respectively. Importantly, Mer overexpression induced resistance to erlotinib (EGFR inhibitor) in otherwise erlotinib-sensitive cells. Furthermore, Mer-specific inhibitor rendered erlotinib-resistant cells sensitive to erlotinib. We conclude that Mer enhances malignant phenotype and pharmacological inhibition of Mer overcomes resistance of NSCLC to EGFR-targeted agents.
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Abstract
Introduction The role of MerTK has not been assessed in gastric cancer (GC). The aim of this study was to identify a subgroup of GC patients with MerTK tumor overexpression, and to evaluate MerTK as a potential therapeutic target in this disease. Methods Protein and mRNA expression of MerTK were evaluated, and other various in vitro analyses including shRNA transfection, cell cycle anslysis, MTS assay and colony forming assay were carried out with GC cell lines and GC patient-derived cells (PDCs). Results shRNA-mediated knockdown of MerTK resulted in inhibition of cell growth, as well as increased cellular apoptosis in MerTK positive GC cells. Out of 192 GC patients, 16 (8.3%) patients showed strong protein expression and they had a significantly shorter overall survival compared to those with no MerTK expression. In 54 cases of GC PDCs, 4 cases (7.4%) showed mRNA overexpression, which was comparable to the protein expression rate. When we administered UNC1062, a novel MerTK-selective small molecular tyrosine kinase inhibitor, proliferation of MerTK overexpressing GC cells and PDCs were considerably inhibited. Conclusion MerTK may be involved in GC carcinogenesis, and it could be a potential novel therapeutic target in GC patients.
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17
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Graham DK, DeRyckere D, Davies KD, Earp HS. The TAM family: phosphatidylserine sensing receptor tyrosine kinases gone awry in cancer. Nat Rev Cancer 2014; 14:769-85. [PMID: 25568918 DOI: 10.1038/nrc3847] [Citation(s) in RCA: 514] [Impact Index Per Article: 51.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The TYRO3, AXL (also known as UFO) and MERTK (TAM) family of receptor tyrosine kinases (RTKs) are aberrantly expressed in multiple haematological and epithelial malignancies. Rather than functioning as oncogenic drivers, their induction in tumour cells predominately promotes survival, chemoresistance and motility. The unique mode of maximal activation of this RTK family requires an extracellular lipid–protein complex. For example, the protein ligand, growth arrest-specific protein 6 (GAS6), binds to phosphatidylserine (PtdSer) that is externalized on apoptotic cell membranes, which activates MERTK on macrophages. This triggers engulfment of apoptotic material and subsequent anti-inflammatory macrophage polarization. In tumours, autocrine and paracrine ligands and apoptotic cells are abundant, which provide a survival signal to the tumour cell and favour an anti-inflammatory, immunosuppressive microenvironment. Thus, TAM kinase inhibition could stimulate antitumour immunity, reduce tumour cell survival, enhance chemosensitivity and diminish metastatic potential.
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18
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Waizenegger JS, Ben-Batalla I, Weinhold N, Meissner T, Wroblewski M, Janning M, Riecken K, Binder M, Atanackovic D, Taipaleenmaeki H, Schewe D, Sawall S, Gensch V, Cubas-Cordova M, Seckinger A, Fiedler W, Hesse E, Kröger N, Fehse B, Hose D, Klein B, Raab MS, Pantel K, Bokemeyer C, Loges S. Role of Growth arrest-specific gene 6-Mer axis in multiple myeloma. Leukemia 2014; 29:696-704. [PMID: 25102945 DOI: 10.1038/leu.2014.236] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 07/11/2014] [Accepted: 07/28/2014] [Indexed: 11/09/2022]
Abstract
Multiple myeloma is a mostly incurable malignancy characterized by the expansion of a malignant plasma cell (PC) clone in the human bone marrow (BM). Myeloma cells closely interact with the BM stroma, which secretes soluble factors that foster myeloma progression and therapy resistance. Growth arrest-specific gene 6 (Gas6) is produced by BM-derived stroma cells and can promote malignancy. However, the role of Gas6 and its receptors Axl, Tyro3 and Mer (TAM receptors) in myeloma is unknown. We therefore investigated their expression in myeloma cell lines and in the BM of myeloma patients and healthy donors. Gas6 showed increased expression in sorted BMPCs of myeloma patients compared with healthy controls. The fraction of Mer(+) BMPCs was increased in myeloma patients in comparison with healthy controls whereas Axl and Tyro3 were not expressed by BMPCs in the majority of patients. Downregulation of Gas6 and Mer inhibited the proliferation of different myeloma cell lines, whereas knocking down Axl or Tyro3 had no effect. Inhibition of the Gas6 receptor Mer or therapeutic targeting of Gas6 by warfarin reduced myeloma burden and improved survival in a systemic model of myeloma. Thus, the Gas6-Mer axis represents a novel candidate for therapeutic intervention in this incurable malignancy.
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Affiliation(s)
- J S Waizenegger
- 1] Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany [2] Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - I Ben-Batalla
- 1] Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany [2] Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - N Weinhold
- Department of Internal Medicine V, Heidelberg University Hospital, Heidelberg, Germany
| | - T Meissner
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - M Wroblewski
- 1] Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany [2] Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Janning
- 1] Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany [2] Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - K Riecken
- Department of Stem Cell Transplantation, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Binder
- Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - D Atanackovic
- Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - H Taipaleenmaeki
- Heisenberg-Group for Molecular Skeletal Biology, Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - D Schewe
- Department of Pediatrics, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - S Sawall
- 1] Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany [2] Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - V Gensch
- 1] Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany [2] Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Cubas-Cordova
- 1] Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany [2] Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - A Seckinger
- Department of Internal Medicine V, Heidelberg University Hospital, Heidelberg, Germany
| | - W Fiedler
- Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - E Hesse
- Heisenberg-Group for Molecular Skeletal Biology, Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - N Kröger
- Department of Stem Cell Transplantation, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - B Fehse
- Department of Stem Cell Transplantation, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - D Hose
- Department of Internal Medicine V, Heidelberg University Hospital, Heidelberg, Germany
| | - B Klein
- Institute of Research in Biotherapy, University Hospital of Montpellier (CHU), Montpellier, France
| | - M S Raab
- Department of Internal Medicine V, Heidelberg University Hospital, Heidelberg, Germany
| | - K Pantel
- Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - C Bokemeyer
- Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - S Loges
- 1] Department of Hematology and Oncology, BMT with Section of Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany [2] Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Pierce AM, Keating AK. TAM receptor tyrosine kinases: expression, disease and oncogenesis in the central nervous system. Brain Res 2013; 1542:206-20. [PMID: 24184575 DOI: 10.1016/j.brainres.2013.10.049] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 10/18/2013] [Accepted: 10/24/2013] [Indexed: 01/10/2023]
Abstract
Receptor tyrosine kinases (RTKs) are cell surface proteins that tightly regulate a variety of downstream intra-cellular processes; ligand-receptor interactions result in cascades of signaling events leading to growth, proliferation, differentiation and migration. There are 58 described RTKs, which are further categorized into 20 different RTK families. When dysregulated or overexpressed, these RTKs are implicated in disordered growth, development, and oncogenesis. The TAM family of RTKs, consisting of Tyro3, Axl, and MerTK, is prominently expressed during the development and function of the central nervous system (CNS). Aberrant expression and dysregulated activation of TAM family members has been demonstrated in a variety of CNS-related disorders and diseases, including the most common but least treatable brain cancer in children and adults: glioblastoma multiforme.
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Affiliation(s)
- Angela M Pierce
- University of Colorado School of Medicine, Department of Pediatrics, 12800 E. 19th Avenue, P18-4105, MS 8302 Aurora, CO 80045, USA.
| | - Amy K Keating
- University of Colorado School of Medicine, Department of Pediatrics, 12800 E. 19th Avenue, P18-4105, MS 8302 Aurora, CO 80045, USA.
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Abstract
The TAM receptors--Tyro3, Axl, and Mer--comprise a unique family of receptor tyrosine kinases, in that as a group they play no essential role in embryonic development. Instead, they function as homeostatic regulators in adult tissues and organ systems that are subject to continuous challenge and renewal throughout life. Their regulatory roles are prominent in the mature immune, reproductive, hematopoietic, vascular, and nervous systems. The TAMs and their ligands--Gas6 and Protein S--are essential for the efficient phagocytosis of apoptotic cells and membranes in these tissues; and in the immune system, they act as pleiotropic inhibitors of the innate inflammatory response to pathogens. Deficiencies in TAM signaling are thought to contribute to chronic inflammatory and autoimmune disease in humans, and aberrantly elevated TAM signaling is strongly associated with cancer progression, metastasis, and resistance to targeted therapies.
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Affiliation(s)
- Greg Lemke
- Molecular Neurobiology Laboratory, Immunobiology and Microbial Pathogenesis Laboratory, The Salk Institute, La Jolla, California 92037
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Abstract
MERTK is a receptor tyrosine kinase of the TAM (Tyro3, Axl, MERTK) family, with a defined spectrum of normal expression. However, MERTK is overexpressed or ectopically expressed in a wide variety of cancers, including leukemia, non-small cell lung cancer, glioblastoma, melanoma, prostate cancer, breast cancer, colon cancer, gastric cancer, pituitary adenomas, and rhabdomyosarcomas, potentially resulting in the activation of several canonical oncogenic signaling pathways. These include the mitogen-activated protein kinase and phosphoinositide 3-kinase pathways, as well as regulation of signal transducer and activator of transcription family members, migration-associated proteins including the focal adhesion kinase and myosin light chain 2, and prosurvival proteins such as survivin and Bcl-2. Each has been implicated in MERTK physiologic and oncogenic functions. In neoplastic cells, these signaling events result in functional phenotypes such as decreased apoptosis, increased migration, chemoresistance, increased colony formation, and increased tumor formation in murine models. Conversely, MERTK inhibition by genetic or pharmacologic means can reverse these pro-oncogenic phenotypes. Multiple therapeutic approaches to MERTK inhibition are currently in development, including ligand "traps", a monoclonal antibody, and small-molecule tyrosine kinase inhibitors.
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Affiliation(s)
- Christopher T. Cummings
- Department of Pediatrics, Section of Hematology, Oncology and Bone Marrow Transplantation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Deborah DeRyckere
- Department of Pediatrics, Section of Hematology, Oncology and Bone Marrow Transplantation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - H. Shelton Earp
- UNC Lineberger Comprehensive Cancer Center, Departments of Medicine and Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Douglas K. Graham
- Department of Pediatrics, Section of Hematology, Oncology and Bone Marrow Transplantation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Corresponding Author: Douglas K. Graham, Department of Pediatrics, Section of Hematology, Oncology and Bone Marrow Transplantation, University of Colorado Anschutz Medical Campus, Mail Stop 8302, 12800 East 19th Avenue, P18-4400, Aurora, CO 80045 USA.
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Tworkoski KA, Platt JT, Bacchiocchi A, Bosenberg M, Boggon TJ, Stern DF. MERTK controls melanoma cell migration and survival and differentially regulates cell behavior relative to AXL. Pigment Cell Melanoma Res 2013; 26:527-41. [PMID: 23617806 DOI: 10.1111/pcmr.12110] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/12/2013] [Indexed: 11/28/2022]
Abstract
The receptor tyrosine kinase AXL regulates melanoma cell proliferation and migration. We now demonstrate that AXL and the related kinase MERTK are alternately expressed in melanoma and are associated with different transcriptional signatures. MERTK-positive melanoma cells are more proliferative and less migratory than AXL-positive melanoma cells and overexpression of AXL increases cell motility relative to MERTK. MERTK is expressed in up to 50% of melanoma cells and shRNA-mediated knockdown of MERTK reduces colony formation and cell migration in a CDC42-dependent fashion. Targeting MERTK also decreases cell survival and proliferation in an AKT-dependent manner. Finally, we identify a novel mutation in the kinase domain of MERTK, MERTK(P) (802S) , that increases the motility of melanoma cells relative to wild-type MERTK. Together, these data demonstrate that MERTK is a possible therapeutic target in melanoma, that AXL and MERTK are associated with differential cell behaviors, and that mutations in MERTK may contribute to melanoma pathogenesis.
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Affiliation(s)
- Kathryn A Tworkoski
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
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Lee-Sherick AB, Eisenman KM, Sather S, McGranahan A, Armistead PM, McGary CS, Hunsucker SA, Schlegel J, Martinson H, Cannon C, Keating AK, Earp HS, Liang X, DeRyckere D, Graham DK. Aberrant Mer receptor tyrosine kinase expression contributes to leukemogenesis in acute myeloid leukemia. Oncogene 2013; 32:5359-68. [PMID: 23474756 PMCID: PMC3898106 DOI: 10.1038/onc.2013.40] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 12/14/2012] [Accepted: 12/30/2012] [Indexed: 01/13/2023]
Abstract
Acute myeloid leukemia (AML) continues to be extremely difficult to treat successfully, and the unacceptably low overall survival rates mandate that we assess new potential therapies to ameliorate poor clinical response to conventional therapy. Abnormal tyrosine kinase activation in AML has been associated with poor prognosis and provides strategic targets for novel therapy development. We found that Mer receptor tyrosine kinase was over-expressed in a majority of pediatric (29/36, 80%) and adult (10/10, 100%) primary AML patient blasts at the time of diagnosis, and 100% of patient samples at the time of relapse. Mer was also found to be expressed in 12 of 14 AML cell lines (86%). In contrast, normal bone marrow myeloid precursors expressed little to no Mer. Following AML cell line stimulation with Gas6, a Mer ligand, we observed activation of prosurvival and proliferative signaling pathways, including phosphorylation of ERK1/2, p38, MSK1, CREB, ATF1, AKT and STAT6. To assess the phenotypic role of Mer in AML, two independent short-hairpin RNA (shRNA) constructs were used to decrease Mer expression in the AML cell lines Nomo-1 and Kasumi-1. Reduction of Mer protein levels significantly increased rates of myeloblast apoptosis two to threefold in response to serum starvation. Furthermore, myeloblasts with knocked-down Mer demonstrated decreased colony formation by 67-87%, relative to control cell lines (P<0.01). NOD-SCID-gamma mice transplanted with Nomo-1 myeloblasts with reduced levels of Mer had a significant prolongation in survival compared with mice transplanted with the parental or control cell lines (median survival 17 days in parental and control cell lines, versus 32-36 days in Mer knockdown cell lines, P<0.0001). These data suggest a role for Mer in acute myeloid leukemogenesis and indicate that targeted inhibition of Mer may be an effective therapeutic strategy in pediatric and adult AML.
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Affiliation(s)
- A B Lee-Sherick
- Department of Pediatrics, Division of Hematology, Oncology, and Bone Marrow Transplantation, Aurora, CO, USA
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Inhibition of MerTK increases chemosensitivity and decreases oncogenic potential in T-cell acute lymphoblastic leukemia. Blood Cancer J 2013; 3:e101. [PMID: 23353780 PMCID: PMC3556576 DOI: 10.1038/bcj.2012.46] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Pediatric leukemia survival rates have improved dramatically over the past decades. However, current treatment protocols are still largely ineffective in cases of relapsed leukemia and are associated with a significant rate of chronic health conditions. Thus, there is a continued need for new therapeutic options. Here, we show that mer receptor tyrosine kinase (MerTK) was abnormally expressed in approximately one half of pediatric T-cell leukemia patient samples and T-cell acute lymphoblastic leukemia (T-ALL) cell lines. Stimulation of MerTK by the ligand Gas6 led to activation of the prosurvival proteins Erk 1/2 and Stat5, and MerTK-dependent activation of the STAT pathway in leukemia represents a novel finding. Furthermore, inhibition of MerTK expression increased the sensitivity of T-ALL cells to treatment with chemotherapeutic agents and decreased the oncogenic potential of the Jurkat T-ALL cell line in a methylcellulose colony-forming assay. Lastly, inhibition of MerTK expression significantly increased median survival in a xenograft mouse model of leukemia (30.5 days vs 60 days, P<0.0001). These results suggest that inhibition of MerTK is a promising therapeutic strategy for the treatment of leukemia and may allow for dose reduction of currently used chemotherapeutics resulting in decreased rates of therapy-associated toxicities.
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Schmidt T, Ben-Batalla I, Schultze A, Loges S. Macrophage-tumor crosstalk: role of TAMR tyrosine kinase receptors and of their ligands. Cell Mol Life Sci 2012; 69:1391-414. [PMID: 22076650 PMCID: PMC11115155 DOI: 10.1007/s00018-011-0863-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2011] [Revised: 10/14/2011] [Accepted: 10/14/2011] [Indexed: 02/07/2023]
Abstract
Ample clinical and preclinical evidence indicates that macrophages interact with tumor cells as well as with virtually all populations of host cells present in the tumor microenvironment. This crosstalk can strongly promote malignancy, but also has in principle the potential to inhibit tumor growth. Thus, it is of the utmost importance to improve our understanding of the mechanisms driving the pro- and antimalignant behavior of tumor-associated macrophages (TAMs) in order to develop better anticancer therapies. In this review, we discuss the biological consequences of reciprocal interactions between TAMs, cancer cells, endothelial cells, fibroblasts and other leukocyte subfractions within tumors. It was recently elucidated that tumors specifically educate macrophages to secrete growth arrest-specific gene 6 (Gas6), the common ligand of the Tyro3, Axl, Mer receptor (TAMR) family. In turn, Gas6 fosters tumor growth by promoting cancer cell proliferation. Therefore, the Gas6-TAMR axis might represent a novel target for disrupting tumor-macrophage crosstalk. We summarize here what is known about TAMR and their ligands in (human) cancer biology. In order to shed more light on the role of macrophages in human cancer, we additionally provide an overview of what is currently known about the prognostic impact of TAMs in human cancer.
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Affiliation(s)
- Thomas Schmidt
- Department of General, Visceral and Transplantation Surgery, University of Heidelberg, Heidelberg, Germany
| | - Isabel Ben-Batalla
- Department of Hematology and Oncology with Sections BMT and Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
- Institute of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Alexander Schultze
- Department of Hematology and Oncology with Sections BMT and Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
- Institute of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sonja Loges
- Department of Hematology and Oncology with Sections BMT and Pneumology, Hubertus Wald Tumorzentrum, University Comprehensive Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
- Institute of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Mer receptor tyrosine kinase promotes invasion and survival in glioblastoma multiforme. Oncogene 2012; 32:872-82. [PMID: 22469987 DOI: 10.1038/onc.2012.104] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The infiltration of glioma cells into adjacent tissue is one of the major obstacles in the therapeutic management of malignant brain tumours, in most cases precluding complete surgical resection. Consequently, malignant glioma patients almost invariably experience tumour recurrences. Within the brain, glioma cells migrate rapidly either amoeboidly or mesenchymally to invade surrounding structures, in dependence on the extracellular environment. In addition, radiotherapy, frequently applied as adjuvant therapeutic modality, may enhance tumour cell mobility. Here, we show that the receptor tyrosine kinase Mer (MerTK) is overexpressed in glioblastoma multiforme (GBM) and that this is accompanied with increased invasive potential. MerTK expression is maintained in primary GBM-derived tumour spheres under stem cell culture conditions but diminishes significantly in serum-containing cultures with concomitant downregulation of Nestin and Sox2. Depletion of MerTK disrupts the rounded morphology of glioma cells and decreases their invasive capacity. Furthermore, the expression and phosphorylation of myosin light chain 2 are strongly associated with MerTK activity, indicating that the effect of MerTK on glioma cell invasion is mediated by actomyosin contractility. Finally, DNA damage robustly triggers the upregulation and phosphorylation of MerTK, which protects cells from apoptosis. This effect is strongly impaired upon MerTK depletion or overexpression of an inactive MerTK mutant. Collectively, our data suggests that MerTK is a novel therapeutic target in the treatment of the malignant gliomas.
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Sandahl M, Hunter DM, Strunk KE, Earp HS, Cook RS. Epithelial cell-directed efferocytosis in the post-partum mammary gland is necessary for tissue homeostasis and future lactation. BMC DEVELOPMENTAL BIOLOGY 2010; 10:122. [PMID: 21192804 PMCID: PMC3022573 DOI: 10.1186/1471-213x-10-122] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 12/30/2010] [Indexed: 11/17/2022]
Abstract
Background Mammary glands harbor a profound burden of apoptotic cells (ACs) during post-lactational involution, but little is known regarding mechanisms by which ACs are cleared from the mammary gland, or consequences if this process is interrupted. We investigated AC clearance, also termed efferocytosis, during post-lactational remodeling, using mice deficient for MerTK, Axl, and Tyro3, three related receptor tyrosine kinases (RTKs) regulating macrophage-mediated efferocytosis in monocytes. MerTK expression, apoptosis and the accumulation of apoptotic debris were examined in histological sections of MerTK-deficient, Axl/Tyro3-deficient, and wild-type mammary glands harvested at specific time points during lactation and synchronized involution. The ability of primary mammary epithelial cells (MECs) to engulf ACs was assessed in culture. Transplant of MerTK-deficient mammary epithelium into cleared WT mammary fat pads was used to assess the contribution of WT mammary macrophages to post-lactational efferocytosis. Results ACs induced MerTK expression in MECs, resulting in elevated MerTK levels at the earliest stages of involution. Loss of MerTK resulted in AC accumulation in post-lactational MerTK-deficient mammary glands, but not in Axl and Tyro3-deficient mammary glands. Increased vascularization, fibrosis, and epithelial hyperproliferation were observed in MerTK-deficient mammary glands through at least 60 days post-weaning, due to failed efferocytosis after lactation, but did not manifest in nulliparous mice. WT host-derived macrophages failed to rescue efferocytosis in transplanted MerTK-deficient mammary epithelium. Conclusion Efferocytosis by MECs through MerTK is crucial for mammary gland homeostasis and function during the post-lactational period. Efferocytosis by MECs thus limits pathologic consequences associated with the apoptotic load following lactation.
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Affiliation(s)
- Melissa Sandahl
- UNC-Lineberger Comprehensive Cancer Center, 450 West Ave, Chapel Hill, North Carolina 27599, USA
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Moncho-Amor V, Ibañez de Cáceres I, Bandres E, Martínez-Poveda B, Orgaz JL, Sánchez-Pérez I, Zazo S, Rovira A, Albanell J, Jiménez B, Rojo F, Belda-Iniesta C, García-Foncillas J, Perona R. DUSP1/MKP1 promotes angiogenesis, invasion and metastasis in non-small-cell lung cancer. Oncogene 2010; 30:668-78. [PMID: 20890299 DOI: 10.1038/onc.2010.449] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
DUSP1/MKP1 is a dual-specific phosphatase that regulates MAPKs activity, with an increasingly recognized role in tumor biology. To understand more about the involvement of DUSP1 in lung cancer, we performed gene expression analyses of parental and DUSP1-interfered H460 non-small-cell lung cancer (NSCLC) cells. Downregulation of DUSP1 induced changes in the expression levels of genes involved in specific biological pathways, including angiogenesis, MAP kinase phosphatase activity, cell-cell signaling, growth factor and tyrosine-kinase receptor activity. Changes in the expression of some of these genes were due to modulation of c-Jun-N-terminal kinase and/or p38 activity by DUSP1. Complementary functional assays were performed to focus on the implication of DUSP1 in angiogenesis and metastasis. In H460 cells, interference of DUSP1 resulted in a diminished capacity to invade through Matrigel, to grow tumors in nude mice and also to induce metastasis through tail-vein injection. Furthermore, the angiogenic potential of H460 cells was also impaired, correlating with a decrease in VEGFC production and indicating that DUSP1 could be required to induce angiogenesis. Finally, we studied whether a similar relationship occurred in patients. In human NSCLC specimens, DUSP1 was mainly expressed in those tumor cells close to CD31 vascular structures and a statistically significant correlation was found between VEGFC and DUSP1 expression. Overall, these results provide evidence for a role of DUSP1 in angiogenesis, invasion and metastasis in NSCLC.
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Affiliation(s)
- V Moncho-Amor
- Instituto de Investigaciones Biomedicas CSIC/UAM, CIBER de Enfermedades Raras (CIBERER), IdiPAZ, Madrid, Spain
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Keating AK, Kim GK, Jones AE, Donson AM, Ware K, Mulcahy JM, Salzberg DB, Foreman NK, Liang X, Thorburn A, Graham DK. Inhibition of Mer and Axl receptor tyrosine kinases in astrocytoma cells leads to increased apoptosis and improved chemosensitivity. Mol Cancer Ther 2010; 9:1298-307. [PMID: 20423999 PMCID: PMC3138539 DOI: 10.1158/1535-7163.mct-09-0707] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Astrocytomas account for the majority of malignant brain tumors diagnosed in both adult and pediatric patients. The therapies available to treat these neoplasms are limited, and the prognosis associated with high-grade lesions is extremely poor. Mer (MerTK) and Axl receptor tyrosine kinases (RTK) are expressed at abnormally high levels in a variety of malignancies, and these receptors are known to activate strong antiapoptotic signaling pathways that promote oncogenesis. In this study, we found that Mer and Axl mRNA transcript and protein expression were elevated in astrocytic patient samples and cell lines. shRNA-mediated knockdown of Mer and Axl RTK expression led to an increase in apoptosis in astrocytoma cells. Apoptotic signaling pathways including Akt and extracellular signal-regulated kinase 1/2, which have been shown to be activated in resistant astrocytomas, were downregulated with Mer and Axl inhibition whereas poly(ADP-ribose) polymerase cleavage was increased. Furthermore, Mer and Axl shRNA knockdown led to a profound decrease of astrocytoma cell proliferation in soft agar and a significant increase in chemosensitivity in response to temozolomide, carboplatin, and vincristine treatment. Our results suggest Mer and Axl RTK inhibition as a novel method to improve apoptotic response and chemosensitivity in astrocytoma and provide support for these oncogenes as attractive biological targets for astrocytoma drug development.
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Affiliation(s)
- Amy K. Keating
- Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Grace K. Kim
- Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Ashley E. Jones
- Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Andrew M. Donson
- Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Kathryn Ware
- Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Jean M. Mulcahy
- Department of Pharmacology, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Dana B. Salzberg
- Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado, Phoenix Children’s Hospital, Phoenix, Arizona
| | - Nicholas K. Foreman
- Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Xiayuan Liang
- Department of Pathology, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Andrew Thorburn
- Department of Pharmacology, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Douglas K. Graham
- Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
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Mer receptor tyrosine kinase is a novel therapeutic target in pediatric B-cell acute lymphoblastic leukemia. Blood 2009; 114:2678-87. [PMID: 19643988 DOI: 10.1182/blood-2009-03-209247] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Acute lymphoblastic leukemia (ALL) is currently treated with an intense regimen of chemotherapy yielding cure rates near 80%. However, additional changes using available drugs are unlikely to provide significant improvement in survival. New therapies are warranted given the risk of severe therapy-associated toxicities including infertility, organ damage, and secondary malignancy. Here, we report ectopic expression of the receptor tyrosine kinase Mer in pediatric B-cell ALL. Inhibition of Mer prevented Erk 1/2 activation, increased the sensitivity of B-ALL cells to cytotoxic agents in vitro by promoting apoptosis, and delayed disease onset in a mouse model of leukemia. In addition, we discovered cross-talk between the Mer and mammalian target of rapamycin (mTOR) signaling pathways. Our results identify Mer as a novel therapeutic target in ALL and suggest that inhibitors of Mer will interact synergistically with currently used therapies. This strategy may allow for dose reduction resulting in decreased toxicity and increased survival rates. Mer is aberrantly expressed in numerous other malignancies suggesting that this approach may have broad applications.
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Anwar A, Keating AK, Joung D, Sather S, Kim GK, Sawczyn KK, Brandão L, Henson PM, Graham DK. Mer tyrosine kinase (MerTK) promotes macrophage survival following exposure to oxidative stress. J Leukoc Biol 2009; 86:73-9. [PMID: 19386698 DOI: 10.1189/jlb.0608334] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The MerTK plays several important roles in normal macrophage physiology, including regulation of cytokine secretion and clearance of apoptotic cells. Mer signaling in other cell types, including malignant cells that ectopically overexpress the RTK, leads to downstream prosurvival pathway activation. We explored the hypothesis that Mer has a prosurvival role in macrophages exposed to oxidative stress. H(2)O(2) treatment of peritoneal exudate murine macrophages and J774 cells rapidly stimulated Mer phosphorylation in a concentration-dependent manner. Mer phosphorylation was dependent on the ligand Gas6, as treatment with warfarin or MerFc (a fusion protein of the extracellular domain of Mer and the Fc portion of human Ig), inhibitors of Gas6 activity, blocked H(2)O(2)-mediated activation of Mer. Antiapoptotic signals including pAkt and pErk 1/2 were increased dramatically (threefold and 4.5-fold, respectively) in WT Mer-positive macrophages compared with Mer KO macrophages stimulated with H(2)O(2). In a consistent manner, Mer expression led to decreased cleavage of proapoptotic indicators PARP and Caspase-3. Furthermore, Mer provided up to twofold enhanced cellular survival to primary macrophages exposed to H(2)O(2). These data represent the first report of Mer activation in response to oxidative stress and demonstrate the ability of Mer RTK to promote macrophage survival in disease states that involve an oxidative stress environment.
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Affiliation(s)
- Adil Anwar
- Department of Pediatrics, University of Colorado Denver, Aurora, CO 80045, USA
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Curtis JL, Todt JC, Hu B, Osterholzer JJ, Freeman CM. Tyro3 receptor tyrosine kinases in the heterogeneity of apoptotic cell uptake. Front Biosci (Landmark Ed) 2009; 14:2631-46. [PMID: 19273223 DOI: 10.2741/3401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mononuclear phagocytes comprise a mobile, broadly dispersed and highly adaptable system that lies at the very epicenter of host defense against pathogens and the interplay of the innate and adaptive arms of immunity. Understanding the molecular mechanisms that control the response of mononuclear phagocytes to apoptotic cells and the anti-inflammatory consequences of that response is an important goal with implications for multiple areas of biomedical sciences. This review details current understanding of the heterogeneity of apoptotic cell uptake by different members of the mononuclear phagocyte family in humans and mice. It also recounts the unique role of the Tyro3 family of receptor tyrosine kinases, best characterized for Mertk, in the signal transduction leading both to apoptotic cell ingestion and the anti-inflammatory effects that result.
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Affiliation(s)
- Jeffrey L Curtis
- Pulmonary and Critical Care Medicine, Department of Veterans Affairs Healthsystem and University of Michigan Health System, Ann Arbor, MI 48105, USA.
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Huang X, Finerty P, Walker JR, Butler-Cole C, Vedadi M, Schapira M, Parker SA, Turk BE, Thompson DA, Dhe-Paganon S. Structural insights into the inhibited states of the Mer receptor tyrosine kinase. J Struct Biol 2008; 165:88-96. [PMID: 19028587 PMCID: PMC2686088 DOI: 10.1016/j.jsb.2008.10.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2008] [Revised: 10/19/2008] [Accepted: 10/20/2008] [Indexed: 01/12/2023]
Abstract
The mammalian ortholog of the retroviral oncogene v-Eyk, and a receptor tyrosine kinase upstream of antiapoptotic and transforming signals, Mer (MerTK) is a mediator of the phagocytic process, being involved in retinal and immune cell clearance and platelet aggregation. Mer knockout mice are viable and are protected from epinephrine-induced pulmonary thromboembolism and ferric chloride-induced thrombosis. Mer overexpression, on the other hand, is associated with numerous carcinomas. Although Mer adaptor proteins and signaling pathways have been identified, it remains unclear how Mer initiates phagocytosis. When bound to its nucleotide cofactor, the high-resolution structure of Mer shows an autoinhibited αC-Glu-out conformation with insertion of an activation loop residue into the active site. Mer complexed with compound-52 (C52: 2-(2-hydroxyethylamino)-6-(3-chloroanilino)-9-isopropylpurine), a ligand identified from a focused library, retains its DFG-Asp-in and αC-Glu-out conformation, but acquires other conformational changes. The αC helix and DFGL region is closer to the hinge region and the ethanolamine moiety of C52 binds in the groove formed between Leu593 and Val601 of the P-loop, causing a compression of the active site pocket. These conformational states reveal the mechanisms of autoinhibition, the pathophysiological basis of disease-causing mutations, and a platform for the development of chemical probes.
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Affiliation(s)
- Xudong Huang
- Structural Genomics Consortium, University of Toronto, Toronto, Ont., Canada
- Department of Physiology, University of Toronto, Toronto, Ont., Canada
| | - Patrick Finerty
- Structural Genomics Consortium, University of Toronto, Toronto, Ont., Canada
| | - John R. Walker
- Structural Genomics Consortium, University of Toronto, Toronto, Ont., Canada
| | | | - Masoud Vedadi
- Structural Genomics Consortium, University of Toronto, Toronto, Ont., Canada
| | - Matthieu Schapira
- Structural Genomics Consortium, University of Toronto, Toronto, Ont., Canada
- Department of Pharmacology, University of Toronto, Toronto, Ont., Canada
| | - Sirlester A. Parker
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Benjamin E. Turk
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Debra A. Thompson
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, W.K. Kellogg Eye Center, Ann Arbor, MI 48105-0714, USA
- Department of Biological Chemistry, University of Michigan Medical School, W.K. Kellogg Eye Center, Ann Arbor, MI 48105-0714, USA
| | - Sirano Dhe-Paganon
- Structural Genomics Consortium, University of Toronto, Toronto, Ont., Canada
- Department of Physiology, University of Toronto, Toronto, Ont., Canada
- Corresponding author. Address: Banting & Best Institute, University of Toronto, 100 College Street, Room 511, Toronto, Ont., Canada M5G 1L5. Fax: +1 416 946 0588.
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Linger RMA, Keating AK, Earp HS, Graham DK. TAM receptor tyrosine kinases: biologic functions, signaling, and potential therapeutic targeting in human cancer. Adv Cancer Res 2008; 100:35-83. [PMID: 18620092 DOI: 10.1016/s0065-230x(08)00002-x] [Citation(s) in RCA: 539] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Tyro-3, Axl, and Mer constitute the TAM family of receptor tyrosine kinases (RTKs) characterized by a conserved sequence within the kinase domain and adhesion molecule-like extracellular domains. This small family of RTKs regulates an intriguing mix of processes, including cell proliferation/survival, cell adhesion and migration, blood clot stabilization, and regulation of inflammatory cytokine release. Genetic or experimental alteration of TAM receptor function can contribute to a number of disease states, including coagulopathy, autoimmune disease, retinitis pigmentosa, and cancer. In this chapter, we first provide a comprehensive review of the structure, regulation, biologic functions, and downstream signaling pathways of these receptors. In addition, we discuss recent evidence which suggests a role for TAM receptors in oncogenic mechanisms as family members are overexpressed in a spectrum of human cancers and have prognostic significance in some. Possible strategies for targeted inhibition of the TAM family in the treatment of human cancer are described. Further research will be necessary to evaluate the full clinical implications of TAM family expression and activation in cancer.
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Affiliation(s)
- Rachel M A Linger
- Department of Pediatrics, University of Colorado at Denver and Health Sciences Center, Aurora, CO, USA
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Shao WH, Eisenberg RA, Cohen PL. The Mer receptor tyrosine kinase is required for the loss of B cell tolerance in the chronic graft-versus-host disease model of systemic lupus erythematosus. THE JOURNAL OF IMMUNOLOGY 2008; 180:7728-35. [PMID: 18490777 DOI: 10.4049/jimmunol.180.11.7728] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The Mer receptor tyrosine kinase mediates apoptotic cell phagocytosis and modulates macrophage cytokine production. Mer(-/-) mice have defective clearance of apoptotic debris and develop a systemic lupus erythematosus-like autoimmune syndrome. It was surprising then that B6-Mer(-/-) recipients of bm12 spleen cells failed to develop anti-dsDNA and anti-chromatin autoantibodies, whereas B6 hosts produced the expected autoimmune chronic graft-vs-host (cGVH) reaction. The lack of autoantibody formation in cGVH was not due to the failure of Mer-deficient hosts to provoke alloreactivity, because Mer(-/-) spleen cells were recognized by bm12 T cells in MLR. Cell transfer experiments in Rag-knockout mice indicated that the lack of autoantibody production in Mer(-/-) cGVH disease hosts was due to an intrinsic B cell defect. This defect did not cause a global inability to produce autoantibodies, because in vivo exposure to LPS stimulated production of autoantibodies in both B6 and Mer(-/-) mice. We further observed that wild-type B6 B cells up-regulated Mer upon activation in cGVH, and that B cells from mice lacking Mer showed a decreased up-regulation of activation-associated cell surface markers. These findings indicate that Mer serves an important role in the activation of self-reactive B cells in systemic autoimmunity.
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Affiliation(s)
- Wen-Hai Shao
- Department of Medicine, Division of Rheumatology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Tibrewal N, Wu Y, D'mello V, Akakura R, George TC, Varnum B, Birge RB. Autophosphorylation docking site Tyr-867 in Mer receptor tyrosine kinase allows for dissociation of multiple signaling pathways for phagocytosis of apoptotic cells and down-modulation of lipopolysaccharide-inducible NF-kappaB transcriptional activation. J Biol Chem 2007; 283:3618-3627. [PMID: 18039660 DOI: 10.1074/jbc.m706906200] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Efficient clearance of apoptotic cells is essential for tissue homeostasis, allowing for cellular turnover without inflammatory consequences. The Mer (Nyk and c-Eyk) receptor tyrosine kinase (Mertk) is involved in two aspects of apoptotic cell clearance by acting as a receptor for Gas6, a gamma-carboxylated phosphatidylserine-binding protein that bridges apoptotic and viable cells. First, Mertk acts in a bona fide engulfment pathway in concert with alphavbeta5 integrin by regulating cytoskeletal assemblages, and second, it acts as a negative regulator for inflammation by down-modulating pro-inflammatory signals mediated from bacterial lipopolysaccharide-Toll-like receptor 4 (TLR4) signaling, and hence recapitulating anti-inflammatory immune modulation by apoptotic cells. Here we describe Mertk post-receptor events that govern phagocytosis and cytoskeletal signaling are principally mediated by autophosphorylation site Tyr-867. Using the Mertk Y867F mutant and pharmacological inhibitors, we show that Tyr-867 is required for phosphatidylinositol 3-kinase and phospholipase Cgamma2 activation; their activation in turn elicits protein kinase C-dependent signals that act on the actin cytoskeleton. Although Mertk(Y867F) blocked the tyrosine phosphorylation of FAK on Tyr-861 and p130(cas) and also abrogated the phagocytosis of apoptotic cells, this mutant did not suppress lipopolysaccharide-inducible NF-kappaB transcription, nor was NF-kappaB activation dependent on the protein kinase C inhibitor, calphostin C. Finally, unlike the cytoskeletal events associated with Tyr-867 autophosphorylation, the trans-inhibition of NF-kappaB occurred in a postnuclear-dependent fashion independent of cytosolic IkappaB phosphorylation and p65/RelA sequestration. Taken together, these data suggest that Mertk has distinct and separable effects for phagocytosis and for resolving inflammation, providing a molecular rationale for how immune licensing and inflammation can be dissociated from phagocytosis in a single phagocytic receptor.
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Affiliation(s)
- Nitu Tibrewal
- Department of Biochemistry & Molecular Biology, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark New Jersey 07103
| | - Yi Wu
- Department of Biochemistry & Molecular Biology, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark New Jersey 07103
| | - Veera D'mello
- Department of Biochemistry & Molecular Biology, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark New Jersey 07103
| | - Reiko Akakura
- Department of Biochemistry & Molecular Biology, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark New Jersey 07103
| | | | - Brian Varnum
- Inflammation Department, Amgen Pharmaceuticals, Amgen, Inc., Thousand Oaks, California 91320
| | - Raymond B Birge
- Department of Biochemistry & Molecular Biology, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark New Jersey 07103.
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Hafizi S, Dahlbäck B. Gas6 and protein S. Vitamin K-dependent ligands for the Axl receptor tyrosine kinase subfamily. FEBS J 2006; 273:5231-44. [PMID: 17064312 DOI: 10.1111/j.1742-4658.2006.05529.x] [Citation(s) in RCA: 257] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gas6 and protein S are two homologous secreted proteins that depend on vitamin K for their execution of a range of biological functions. A discrete subset of these functions is mediated through their binding to and activation of the receptor tyrosine kinases Axl, Sky and Mer. Furthermore, a hallmark of the Gas6-Axl system is the unique ability of Gas6 and protein S to tether their non receptor-binding regions to the negatively charged membranes of apoptotic cells. Numerous studies have shown the Gas6-Axl system to regulate cell survival, proliferation, migration, adhesion and phagocytosis. Consequently, altered activity/expression of its components has been detected in a variety of pathologies such as cancer and vascular, autoimmune and kidney disorders. Moreover, Axl overactivation can equally occur without ligand binding, which has implications for tumorigenesis. Further knowledge of this exquisite ligand-receptor system and the circumstances of its activation should provide the basis for development of novel therapies for the above diseases.
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Affiliation(s)
- Sassan Hafizi
- Lund University, Department of Laboratory Medicine, Section for Clinical Chemistry, Wallenberg Laboratory, University Hospital Malmö, Sweden.
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Sather S, Kenyon KD, Lefkowitz JB, Liang X, Varnum BC, Henson PM, Graham DK. A soluble form of the Mer receptor tyrosine kinase inhibits macrophage clearance of apoptotic cells and platelet aggregation. Blood 2006; 109:1026-33. [PMID: 17047157 PMCID: PMC1785151 DOI: 10.1182/blood-2006-05-021634] [Citation(s) in RCA: 245] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Membrane-bound receptors generate soluble ligand-binding domains either by proteolytic cleavage of the extracellular domain or alternative mRNA splicing yielding a secreted protein. Mertk (Mer) is in a receptor tyrosine kinase family with Axl and Tyro-3, and all 3 receptors share the Gas6 ligand. Mer regulates macrophage activation, promotes apoptotic cell engulfment, and supports platelet aggregation and clot stability in vivo. We have found that the membrane-bound Mer protein is cleaved in the extracellular domain via a metalloproteinase. The cleavage results in the production of a soluble Mer protein released in a constitutive manner from cultured cells. Significant amounts of the soluble Mer protein were also detected in human plasma, suggesting its physiologic relevance. Cleavage of Mer was enhanced by treatment with LPS and PMA and was specifically inhibited by a tumor necrosis factor alpha-converting enzyme metalloproteinase inhibitor. As a decoy receptor for Gas6, soluble Mer prevented Gas6-mediated stimulation of membrane-bound Mer. The inhibition of Gas6 activity by soluble Mer led to defective macrophage-mediated engulfment of apoptotic cells. Furthermore, soluble Mer decreased platelet aggregation in vitro and prevented fatal collagen/epinephrine-induced thromboembolism in mice, suggesting a potential therapeutic use for soluble Mer in the treatment of clotting disorders.
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Affiliation(s)
- Susan Sather
- Department of Pediatrics, University of Colorado at Denver, and Health Sciences Center, Aurora, CO 80045, USA
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Graham DK, Salzberg DB, Kurtzberg J, Sather S, Matsushima GK, Keating AK, Liang X, Lovell MA, Williams SA, Dawson TL, Schell MJ, Anwar AA, Snodgrass HR, Earp HS. Ectopic expression of the proto-oncogene Mer in pediatric T-cell acute lymphoblastic leukemia. Clin Cancer Res 2006; 12:2662-9. [PMID: 16675557 DOI: 10.1158/1078-0432.ccr-05-2208] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The Mer receptor tyrosine kinase, cloned from a B-lymphoblastoid library, is the mammalian orthologue of the chicken retroviral oncogene v-eyk and sends antiapoptotic and transforming signals when activated. To determine if Mer expression is ectopic in T-cell acute lymphoblastic leukemia (ALL) and potentially important in leukemogenesis, we analyzed Mer expression in normal human thymocytes and lymphocytes and in pediatric ALL patient samples. EXPERIMENTAL DESIGN Reverse transcription-PCR, flow cytometry, and immunohistochemistry were used to determine expression of Mer in sorted human thymocyte populations, lymphocytes, and lymphocytes activated by phytohemagglutinin or phorbol 12-myristate 13-acetate/ionophore. Mer expression in 34 T-cell ALL (T-ALL) patient samples was evaluated by reverse transcription-PCR, and Mer protein expression in a separate cohort of 16 patient samples was assayed by flow cytometry and Western blot. RESULTS Mer expression was absent in normal thymocytes or lymphocytes, and in T cells activated with phytohemagglutinin or phorbol 12-myristate 13-acetate/ionophore. In contrast, Jurkat cells and T-ALL patient samples expressed unique 180 to 185 kDa Mer protein glycoforms. Substantial Mer RNA levels were principally observed in a subset of T-ALL patient samples that expressed B220 (P = 0.004) but lacked surface expression of CD3 (P = 0.02) and CD4 (P = 0.006), a phenotypic profile consistent with immature lymphoblasts. In addition, 8 of 16 T-ALL patient samples had Mer protein detected by flow cytometry and Western blot. CONCLUSIONS Transforming Mer signals may contribute to T-cell leukemogenesis, and abnormal Mer expression may be a novel therapeutic target in pediatric ALL therapy.
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Affiliation(s)
- Douglas K Graham
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, Colorado, USA.
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40
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Keating AK, Salzberg DB, Sather S, Liang X, Nickoloff S, Anwar A, Deryckere D, Hill K, Joung D, Sawczyn KK, Park J, Curran-Everett D, McGavran L, Meltesen L, Gore L, Johnson GL, Graham DK. Lymphoblastic leukemia/lymphoma in mice overexpressing the Mer (MerTK) receptor tyrosine kinase. Oncogene 2006; 25:6092-100. [PMID: 16652142 DOI: 10.1038/sj.onc.1209633] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mer (MerTK) is a receptor tyrosine kinase important in platelet aggregation, as well as macrophage cytokine secretion and clearance of apoptotic cells. Mer is not normally expressed in thymocytes or lymphocytes; however, ectopic Mer RNA transcript and protein expression is found in a subset of acute lymphoblastic leukemia cell lines and patient samples, suggesting a role in leukemogenesis. To investigate the oncogenic potential of Mer in vivo, we created a transgenic mouse line (Mer(Tg)) that expresses Mer in the hematopoietic lineage under control of the Vav promoter. Ectopic expression and activation of the transgenic Mer protein was demonstrated in lymphocytes and thymocytes of the Mer(Tg) mice. At 12-24 months of age, greater than 55% of the Mer(Tg) mice, compared to 12% of the wild type, developed adenopathy, hepatosplenomegaly, and circulating lymphoblasts. Histopathological analysis and flow cytometry were consistent with T-cell lymphoblastic leukemia/lymphoma. Mer may contribute to leukemogenesis by activation of Akt and ERK1/2 anti-apoptotic signals, which were upregulated in Mer(Tg) mice. Additionally, a significant survival advantage was noted in Mer(Tg) lymphocytes compared to wild-type lymphocytes after dexamethasone treatment. These data suggest that Mer plays a cooperative role in leukemogenesis and may be an effective target for biologically based leukemia/lymphoma therapy.
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Affiliation(s)
- A K Keating
- Department of Pediatrics, University of Colorado at Denver and Health Sciences Center, Denver, CO 80045, USA
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Wu YM, Robinson DR, Kung HJ. Signal Pathways in Up-regulation of Chemokines by Tyrosine Kinase MER/NYK in Prostate Cancer Cells. Cancer Res 2004; 64:7311-20. [PMID: 15492251 DOI: 10.1158/0008-5472.can-04-0972] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The AXL/UFO family of tyrosine kinases is characterized by a common N-CAM (neural adhesion molecule)-related extracellular domain and a common ligand, GAS6 (growth arrest-specific protein 6). Family members are prone to transcriptional regulation and carry out diverse functions including the regulation of cell adhesion, migration, phagocytosis, and survival. In this report, we describe a new role of MER/N-CAM-related kinase (NYK), a member of the AXL family of kinases, in the up-regulation of chemokines in prostate cancer cells. We show that NYK has elevated expression in a subset of tumor specimens and prostate cancer cell lines. Activation of NYK in the prostate cancer cell line DU145 does not cause a mitogenic effect; instead, it causes a differentiation phenotype. Microarray analysis revealed that NYK is a strong inducer of endocrine factors including interleukin (IL)-8 and several other angiogenic CXC chemokines as well as bone morphogenic factors. The dramatic increase of IL-8 expression is seen at both transcriptional and posttranscriptional levels. The downstream signals engaged by NYK were characterized, and those responsible for the up-regulation of IL-8 transcription were defined. In contrast to IL-1alpha, NYK-induced up-regulation of IL-8 in DU145 depends on the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase/Jun/Fos pathway, but not phosphoinositide 3'-kinase/nuclear factor-kappaB. These data define a new function of the AXL family of kinases and suggest a potential role of NYK in prostate cancer progression.
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Affiliation(s)
- Yi-Mi Wu
- University of California at Davis, University of California Davis Cancer Center, Sacramento, California, USA
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42
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Todt JC, Hu B, Curtis JL. The receptor tyrosine kinase MerTK activates phospholipase C gamma2 during recognition of apoptotic thymocytes by murine macrophages. J Leukoc Biol 2004; 75:705-13. [PMID: 14704368 PMCID: PMC2441598 DOI: 10.1189/jlb.0903439] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Apoptotic leukocytes must be cleared efficiently by macrophages (Mø). Apoptotic cell phagocytosis by Mø requires the receptor tyrosine kinase (RTK) MerTK (also known as c-Mer and Tyro12), the phosphatidylserine receptor (PS-R), and the classical protein kinase C (PKC) isoform betaII, which translocates to Mø membrane and cytoskeletal fractions in a PS-R-dependent manner. How these molecules cooperate to induce phagocytosis is unknown. As the phosphatidylinositol-specific phospholipase (PI-PLC) gamma2 is downstream of RTKs in some cell types and can activate classical PKCs, we hypothesized that MerTK signals via PLC gamma2. To test this hypothesis, we examined the interaction of MerTK and PLC gamma2 in resident, murine peritoneal (P)Mø and in the murine Mø cell line J774A.1 (J774) following exposure to apoptotic thymocytes. We found that as with PMø, J774 phagocytosis of apoptotic thymocytes was inhibited by antibody against MerTK. Western blotting and immunoprecipitation showed that exposure to apoptotic cells produced three time-dependent changes in PMø and J774: tyrosine phosphorylation of MerTK; association of PLC gamma2 with MerTK; and tyrosine phosphorylation of PLC gamma2. Cross-linking MerTK using antibody also induced phosphorylation of PLC gamma2 and its association with MerTK. A PI-PLC appears to be required for phagocytosis of apoptotic cells, as the PI-PLC inhibitor Et-18-OCH3 and the PLC inhibitor U73122, but not the inactive control U73343, blocked phagocytosis without impairing adhesion. On apoptotic cell adhesion to Mø, MerTK signals at least in part via PLC gamma2.
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Affiliation(s)
- Jill C. Todt
- Division of Pulmonary & Critical Care Medicine, Department of Internal Medicine, University of Michigan Health Care System, Ann Arbor, MI, USA
| | - Bin Hu
- Division of Pulmonary & Critical Care Medicine, Department of Internal Medicine, University of Michigan Health Care System, Ann Arbor, MI, USA
| | - Jeffrey L. Curtis
- Division of Pulmonary & Critical Care Medicine, Department of Internal Medicine, University of Michigan Health Care System, Ann Arbor, MI, USA
- Comprehensive Cancer Center, University of Michigan Health Care System, Ann Arbor, MI, USA
- Graduate Program in Immunology, University of Michigan Health Care System, Ann Arbor, MI, USA
- Pulmonary & Critical Care Medicine Section, Medical Service, Department of Veterans Affairs Care System, Ann Arbor, MI, USA
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43
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Mahajan NP, Earp HS. An SH2 domain-dependent, phosphotyrosine-independent interaction between Vav1 and the Mer receptor tyrosine kinase: a mechanism for localizing guanine nucleotide-exchange factor action. J Biol Chem 2003; 278:42596-603. [PMID: 12920122 DOI: 10.1074/jbc.m305817200] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mer belongs to the Mer/Axl/Tyro3 receptor tyrosine kinase family, which regulates immune homeostasis in part by triggering monocyte ingestion of apoptotic cells. Mutations in Mer can also cause retinitis pigmentosa, again due to defective phagocytosis of apoptotic material. Although, some functional aspects of Mer have been deciphered, how receptor activation lead to the physiological consequences is not understood. By using yeast two-hybrid assays, we identified the carboxyl-terminal region of the guanine nucleotide-exchange factor (GEF) Vav1 as a Mer-binding partner. Unlike similar (related) receptors, Mer interacted with Vav1 constitutively and independently of phosphotyrosine, yet the site of binding localized to the Vav1 SH2 domain. Mer activation resulted in tyrosine phosphorylation of Vav1 and release from Mer, whereas Vav1 was neither phosphorylated nor released from kinase-dead Mer. Mutation of the Vav1 SH2 domain phosphotyrosine coordinating Arg-696 did not alter Mer/Vav1 constitutive binding or Vav1 tyrosine phosphorylation but did retard Vav1 release from autophosphorylated Mer. Ligand-dependent activation of Mer in human monocytes led to Vav1 release and stimulated GDP replacement by GTP on RhoA family members. This unusual constitutive, SH2 domain-dependent, but phosphotyrosine-independent, interaction and its regulated local release and subsequent activation of Rac1, Cdc42, and RhoA may explain how Mer coordinates precise cytoskeletal changes governing the ingestion of apoptotic material by macrophages and pigmented retinal epithelial cells.
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Affiliation(s)
- Nupam P Mahajan
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 7599-7295, USA
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The growth arrest-specific gene product Gas6 promotes the survival of human oligodendrocytes via a phosphatidylinositol 3-kinase-dependent pathway. J Neurosci 2003. [PMID: 12764109 DOI: 10.1523/jneurosci.23-10-04208.2003] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Microarray analysis revealed that transcripts for the Axl and Mer receptor tyrosine kinases are expressed at high levels in O4+-immunopanned oligodendrocytes isolated from second trimester human fetal spinal cord. In humans the sole known ligand for the Axl/Rse/Mer kinases is growth arrest-specific gene 6 (Gas6), which in the CNS is secreted by neurons and endothelial cells. We hypothesized that Gas6 is a survival factor for oligodendrocytes and receptor activation signals downstream to the phosphatidylinositol 3 (PI3)-kinase/Akt pathway to increase cell survival in the absence of cell proliferation. To test this hypothesis, we grew enriched human oligodendrocytes for 6 d on a monolayer of NIH3T3 cells stably expressing Gas6. CNP+ oligodendrocytes on Gas6-secreting 3T3 cells had more primary processes and arborizations than those plated solely on 3T3 cells. Also, a twofold increase in CNP+ and MBP+ oligodendrocytes was observed when they were plated on the Gas6-secreting cells. The effect was abolished in the presence of Axl-Fc but remained unchanged in the presence of the irrelevant receptor fusion molecule TrkA-Fc. A significant decrease in CNP+/TUNEL+ oligodendrocytes was observed when recombinant human Gas6 (rhGas6) was administered to oligodendrocytes plated on poly-L-lysine, supporting a role for Gas6 signaling in oligodendrocyte survival during a period of active myelination in human fetal spinal cord development. PI3-kinase inhibitors blocked the anti-apoptotic effect of rhGas6, whereas a MEK/ERK inhibitor had no effect. Thus Gas6 sustains human fetal oligodendrocyte viability by receptor activation and downstream signaling via the PI3-kinase/Akt pathway.
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45
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Shankar SL, O'Guin K, Cammer M, McMorris FA, Stitt TN, Basch RS, Varnum B, Shafit-Zagardo B. The growth arrest-specific gene product Gas6 promotes the survival of human oligodendrocytes via a phosphatidylinositol 3-kinase-dependent pathway. J Neurosci 2003; 23:4208-18. [PMID: 12764109 PMCID: PMC6741089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023] Open
Abstract
Microarray analysis revealed that transcripts for the Axl and Mer receptor tyrosine kinases are expressed at high levels in O4+-immunopanned oligodendrocytes isolated from second trimester human fetal spinal cord. In humans the sole known ligand for the Axl/Rse/Mer kinases is growth arrest-specific gene 6 (Gas6), which in the CNS is secreted by neurons and endothelial cells. We hypothesized that Gas6 is a survival factor for oligodendrocytes and receptor activation signals downstream to the phosphatidylinositol 3 (PI3)-kinase/Akt pathway to increase cell survival in the absence of cell proliferation. To test this hypothesis, we grew enriched human oligodendrocytes for 6 d on a monolayer of NIH3T3 cells stably expressing Gas6. CNP+ oligodendrocytes on Gas6-secreting 3T3 cells had more primary processes and arborizations than those plated solely on 3T3 cells. Also, a twofold increase in CNP+ and MBP+ oligodendrocytes was observed when they were plated on the Gas6-secreting cells. The effect was abolished in the presence of Axl-Fc but remained unchanged in the presence of the irrelevant receptor fusion molecule TrkA-Fc. A significant decrease in CNP+/TUNEL+ oligodendrocytes was observed when recombinant human Gas6 (rhGas6) was administered to oligodendrocytes plated on poly-L-lysine, supporting a role for Gas6 signaling in oligodendrocyte survival during a period of active myelination in human fetal spinal cord development. PI3-kinase inhibitors blocked the anti-apoptotic effect of rhGas6, whereas a MEK/ERK inhibitor had no effect. Thus Gas6 sustains human fetal oligodendrocyte viability by receptor activation and downstream signaling via the PI3-kinase/Akt pathway.
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Affiliation(s)
- Sai Latha Shankar
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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46
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Guttridge KL, Luft JC, Dawson TL, Kozlowska E, Mahajan NP, Varnum B, Earp HS. Mer receptor tyrosine kinase signaling: prevention of apoptosis and alteration of cytoskeletal architecture without stimulation or proliferation. J Biol Chem 2002; 277:24057-66. [PMID: 11929866 DOI: 10.1074/jbc.m112086200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mer is a member of the Axl/Mer/Tyro3 receptor tyrosine kinase family, a family whose physiological function is not well defined. We constructed a Mer chimera using the epidermal growth factor receptor (EGFR) extracellular and transmembrane domains and the Mer cytoplasmic domain. Stable transfection of the Mer chimera into interleukin 3 (IL-3)-dependent murine 32D cells resulted in ligand-activable surface receptor that tyrosine autophosphorylated, stimulated intracellular signaling, and dramatically reduced apoptosis initiated by IL-3 withdrawal. However, unlike multiple other ectopically expressed receptor tyrosine kinases including full-length EGFR or an EGFR/Axl chimera, the Mer chimera did not stimulate proliferation. Moreover, and in contrast to EGFR, Mer chimera activation induced adherence and cell flattening in the normally suspension-growing 32D cells. The Mer chimera signal also blocked IL-3-dependent proliferation leading to G(1)/S arrest, dephosphorylation of retinoblastoma protein, and elongation of cellular processes. Unlike other agonists that lead to a slow (4-8 days) ligand-dependent differentiation of 32D cells, the combined Mer and IL-3 signal resulted in differentiated morphology and growth cessation in the first 24 h. Thus the Mer chimera blocks apoptosis without stimulating growth and produces cytoskeletal alterations; this outcome is clearly separable from the proliferative signal produced by most receptor tyrosine kinases.
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Affiliation(s)
- Katherine L Guttridge
- Lineberger Comprehensive Cancer Center, Department of Medicine and Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA
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47
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Weier HU, Zitzelsberger HF, Hsieh HB, Sun MV, Wong M, Lersch RA, Yaswen P, Smida J, Kuschnick C, Clark OH. Monitoring signal transduction in cancer: tyrosine kinase gene expression profiling. J Histochem Cytochem 2001; 49:673-4. [PMID: 11304810 DOI: 10.1177/002215540104900519] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abnormal expression of tyrosine kinase (TK) genes is common in tumors, in which it is believed to alter cell growth and response to external stimuli such as growth factors and hormones. Although the etiology and pathogenesis of carcinomas of the thyroid or breast remain unclear, there is evidence that the expression of TK genes, such as receptor tyrosine kinases, or mitogen-activated protein kinases, is dysregulated in these tumors, and that overexpression of particular TK genes due to gene amplification, changes in gene regulation, or structural alterations leads to oncogenic transformation of epithelial cells. We developed a rapid scheme to measure semiquantitatively the expression levels of 50-100 TK genes. Our assay is based on RT-PCR with mixed based primers that anneal to conserved regions in the catalytic domain of TK genes to generate gene-specific fragments. PCR products are then labeled by random priming and hybridized to DNA microarrays carrying known TK gene targets. Inclusion of differently labeled fragments from reference or normal cells allows identification of TK genes that show altered expression levels during malignant transformation or tumor progression. Examples demonstrate how this innovative assay might help to define new markers for tumor progression and potential targets for disease intervention. (J Histochem Cytochem 49:673-674, 2001)
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Affiliation(s)
- H U Weier
- Life Sciences Division, E.O. Lawrence Berkeley National Laboratory, University of California, 1 Cyclotron Road, MS 74-157, Berkeley, CA 94720, USA.
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48
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Evenäs P, Dahlbäck B, García de Frutos P. The first laminin G-type domain in the SHBG-like region of protein S contains residues essential for activation of the receptor tyrosine kinase sky. Biol Chem 2000; 381:199-209. [PMID: 10782991 DOI: 10.1515/bc.2000.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Vitamin K-dependent protein S and the product of growth-arrest-specific gene 6 (Gas6) both possess the ability to phosphorylate members of the Axl/Sky subfamily of receptor tyrosine kinases. However, Gas6 appears to be the bona fide ligand for these receptors in man, as human protein S has been demonstrated to activate murine Sky but not the human orthologue. In contrast, bovine protein S is able to stimulate human Sky despite its high degree of sequence identity with human protein S. The domain organisations of protein S and Gas6 are virtually identical and the C-terminal SHBG-like region, containing two globular (G) domains, has been shown to play a crucial role in the receptor stimulation. In order to further localise the area responsible for the interaction, a number of protein chimeras were used to stimulate human Sky. Each chimera had one part of the human protein S SHBG-like region replaced by the corresponding part of bovine protein S or human Gas6. We found that human protein S may indeed activate human Sky but only above physiological plasma concentrations. The human-bovine protein S chimeras provided new information implying that the first G domain contains critical residues for the interaction with the Sky receptor. Moreover, these residues do not seem to be clustered but rather to be distributed at various positions in the first G domain.
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Affiliation(s)
- P Evenäs
- Department of Clinical Chemistry, Lund University, University Hospital, Malmö, Sweden
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49
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Prieto AL, Weber JL, Lai C. Expression of the receptor protein-tyrosine kinases Tyro-3, Axl, and Mer in the developing rat central nervous system. J Comp Neurol 2000. [DOI: 10.1002/1096-9861(20000918)425:2<295::aid-cne11>3.0.co;2-g] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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50
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Goruppi S, Ruaro E, Varnum B, Schneider C. Gas6-mediated survival in NIH3T3 cells activates stress signalling cascade and is independent of Ras. Oncogene 1999; 18:4224-36. [PMID: 10435635 DOI: 10.1038/sj.onc.1202788] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Gas6 is a growth factor membrane of the vitamin K-dependent family of proteins which is preferentially expressed in quiescent cells. Gas6 was identified as the ligand for Axl tyrosine kinase receptor family. Consistent with this, Gas6 was previously reported to induce cell cycle re-entry of serum-starved NIH3T3 cells and to prevent cell death after complete growth factor withdrawal, the survival effect being uncoupled from Gas6-induced mitogenesis. We have previously demonstrated that both Gas6 mitogenic and survival effects are mediated by Src and the phosphatidylinositol3-OH kinase (PI3K). Here we report that Ras is required for Gas6 mitogenesis but is dispensable for its survival effect. Gas6-induced survival requires the activity of the small GTPases of the Rho family, Rac and Rho, together with the downstream kinase Pak. Overexpression of the respective dominant negative constructs abrogates Gas6-mediated survival functions. Addition of Gas6 to serum starved cells results in the activation of AKT/PKB and in the phosphorylation of the Bcl-2 family member, Bad. By ectopic expression of a catalytically inactive form of AKT/PKB, we demonstrate that AKT/PKB is necessary for Gas6-mediated survival functions. We further show evidence that Gas6 stimulation of serum starved NIH3T3 cells results in a transient ERK, JNK/SAPK and p38 MAPK activation. Blocking ERK activation did not influence Gas6-induced survival, suggesting that such pathway is not involved in Gas6 protection from cell death. On the contrary we found that the late constitutive increase of p38 MAPK activity associated with cell death was downregulated in Gas6-treated NIH3T3 cells thus suggesting that Gas6 might promote survival by interfering with this pathway. Taken together the evidence here provided identity elements involved in Gas6 signalling more specifically elucidating the pathway responsible for Gas6-induced cell survival under conditions that do not allow cell proliferation.
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Affiliation(s)
- S Goruppi
- L.N.C.I.B. Laboratorio Nazionale Consorzio Interuniversitario Biotecnologie AREA Science Park, Trieste, Italy
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