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Jiang Z, Zhang W, Sha G, Wang D, Tang D. Galectins Are Central Mediators of Immune Escape in Pancreatic Ductal Adenocarcinoma. Cancers (Basel) 2022; 14:cancers14225475. [PMID: 36428567 PMCID: PMC9688059 DOI: 10.3390/cancers14225475] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/02/2022] [Accepted: 11/07/2022] [Indexed: 11/09/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers and is highly immune tolerant. Although there is immune cell infiltration in PDAC tissues, most of the immune cells do not function properly and, therefore, the prognosis of PDAC is very poor. Galectins are carbohydrate-binding proteins that are intimately involved in the proliferation and metastasis of tumor cells and, in particular, play a crucial role in the immune evasion of tumor cells. Galectins induce abnormal functions and reduce numbers of tumor-associated macrophages (TAM), natural killer cells (NK), T cells and B cells. It further promotes fibrosis of tissues surrounding PDAC, enhances local cellular metabolism, and ultimately constructs tumor immune privileged areas to induce immune evasion behavior of tumor cells. Here, we summarize the respective mechanisms of action played by different Galectins in the process of immune escape from PDAC, focusing on the mechanism of action of Galectin-1. Galectins cause imbalance between tumor immunity and anti-tumor immunity by coordinating the function and number of immune cells, which leads to the development and progression of PDAC.
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Affiliation(s)
- Zhengting Jiang
- Clinical Medical College, Yangzhou University, Yangzhou 225000, China
| | - Wenjie Zhang
- Clinical Medical College, Yangzhou University, Yangzhou 225000, China
| | - Gengyu Sha
- Clinical Medical College, Yangzhou University, Yangzhou 225000, China
| | - Daorong Wang
- Clinical Medical College, Yangzhou University, Yangzhou 225000, China
- Department of General Surgery, Institute of General Surgery, Clinical Medical College, Yangzhou University, Northern Jiangsu People’s Hospital, Yangzhou 225000, China
| | - Dong Tang
- Clinical Medical College, Yangzhou University, Yangzhou 225000, China
- Department of General Surgery, Institute of General Surgery, Clinical Medical College, Yangzhou University, Northern Jiangsu People’s Hospital, Yangzhou 225000, China
- Correspondence: ; Tel.: +86-18952783556
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Hahn L, Meister S, Mannewitz M, Beyer S, Corradini S, Hasbargen U, Mahner S, Jeschke U, Kolben T, Burges A. Gal-2 Increases H3K4me3 and H3K9ac in Trophoblasts and Preeclampsia. Biomolecules 2022; 12:biom12050707. [PMID: 35625634 PMCID: PMC9139023 DOI: 10.3390/biom12050707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 12/10/2022] Open
Abstract
Preeclampsia (PE) is a severe pregnancy disorder with a pathophysiology not yet completely understood and without curative therapy. The histone modifications H3K4me3 and H3K9ac, as well as galectin-2 (Gal-2), are known to be decreased in PE. To gain a better understanding of the development of PE, the influence of Gal-2 on histone modification in trophoblasts and in syncytialisation was investigated. Immunohistochemical stains of 13 PE and 13 control placentas were correlated, followed by cell culture experiments. An analysis of H3K4me3 and H3K9ac was conducted, as well as cell fusion staining with E-cadherin and β-catenin—both after incubation with Gal-2. The expression of H3K4me3 and H3K9ac correlated significantly with the expression of Gal-2. Furthermore, we detected an increase in H3K4me3 and H3K9ac after the addition of Gal-2 to BeWo/HVT cells. Moreover, there was increased fusion of HVT cells after incubation with Gal-2. Gal-2 is associated with the histone modifications H3K4me3 and H3K9ac in trophoblasts. Furthermore, syncytialisation increased after incubation with Gal-2. Therefore, we postulate that Gal-2 stimulates syncytialisation, possibly mediated by H3K4me3 and H3K9ac. Since Gal-2, as well as H3K4me3 and H3K9ac, are decreased in PE, the induction of Gal-2 might be a promising therapeutic target.
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Affiliation(s)
- Laura Hahn
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
- Correspondence: ; Tel.: +49-89-440073800
| | - Sarah Meister
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
| | - Mareike Mannewitz
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
| | - Susanne Beyer
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
| | - Stefanie Corradini
- Department of Radiation Oncology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany;
| | - Uwe Hasbargen
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
| | - Sven Mahner
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
| | - Udo Jeschke
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
- Department of Gynecology and Obsterics, University Hospital Augsburg, 86156 Augsburg, Germany
| | - Thomas Kolben
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
| | - Alexander Burges
- Department of Obsterics and Gynecology, University Hospital, Ludwig-Maximilians-Universität Munich, Marchioninistr. 15, 81337 Munich, Germany; (S.M.); (M.M.); (S.B.); (U.H.); (S.M.); (U.J.); (T.K.); (A.B.)
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3
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Mormino A, Cocozza G, Fontemaggi G, Valente S, Esposito V, Santoro A, Bernardini G, Santoni A, Fazi F, Mai A, Limatola C, Garofalo S. Histone-deacetylase 8 drives the immune response and the growth of glioma. Glia 2021; 69:2682-2698. [PMID: 34310727 PMCID: PMC8457175 DOI: 10.1002/glia.24065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 06/17/2021] [Accepted: 07/13/2021] [Indexed: 12/18/2022]
Abstract
Many epigenetic modifications occur in glioma, in particular the histone-deacetylase class proteins play a pivotal role in glioma development, driving the proliferation rate and the invasiveness of tumor cells, and modulating the tumor microenvironment. In this study, we evaluated the role of the histone deacetylase HDAC8 in the regulation of the immune response in glioma and tumor growth. We found that inhibition of HDAC8 by the specific inhibitor PCI-34051 reduces tumor volume in glioma mouse models. We reported that HDAC8 modulates the viability and the migration of human and murine glioma cells. Interestingly, HDAC8 inhibition increases the acetylation of alpha-tubulin, suggesting this epigenetic modification controls glioma migration. Furthermore, we identify HDAC8 as a key molecule that supports a poorly immunogenic tumor microenvironment, modulating microglial phenotype and regulating the gene transcription of NKG2D ligands that trigger the Natural Killer cell-mediated cytotoxicity of tumor cells. Altogether, these results identify HDAC8 as a key actor in glioma growth and tumor microenvironment, and pave the way to a better knowledge of the molecular mechanisms of immune escape in glioma.
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Affiliation(s)
| | | | - Giulia Fontemaggi
- Oncogenomic and Epigenetic Unit“Regina Elena” National Cancer Institute – IFORomeItaly
| | - Sergio Valente
- Department of Drug Chemistry and TechnologiesSapienza UniversityRomeItaly
| | - Vincenzo Esposito
- IRCCS NeuromedPozzilliItaly
- Department of Neurology and PsychiatrySapienza UniversityRomeItaly
| | - Antonio Santoro
- Department of Neurology and PsychiatrySapienza UniversityRomeItaly
| | - Giovanni Bernardini
- Department of Molecular Medicine, Laboratory Affiliated to Istituto Pasteur ItaliaSapienza UniversityRomeItaly
| | | | - Francesco Fazi
- Department of Anatomical, Histological, Forensic & Orthopaedic Sciences, Section of Histology and Medical Embryology, Laboratory Affiliated to Istituto Pasteur ItaliaSapienza UniversityRomeItaly
| | - Antonello Mai
- Department of Drug Chemistry and TechnologiesSapienza UniversityRomeItaly
| | - Cristina Limatola
- IRCCS NeuromedPozzilliItaly
- Department of Physiology and Pharmacology, Laboratory Affiliated to Istituto Pasteur ItaliaSapienza UniversityRomeItaly
| | - Stefano Garofalo
- Department of Physiology and PharmacologySapienza UniversityRomeItaly
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Cifaldi L, Locatelli F, Marasco E, Moretta L, Pistoia V. Boosting Natural Killer Cell-Based Immunotherapy with Anticancer Drugs: a Perspective. Trends Mol Med 2017; 23:1156-1175. [PMID: 29133133 DOI: 10.1016/j.molmed.2017.10.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 12/27/2022]
Abstract
Natural killer (NK) cells efficiently recognize and kill tumor cells through several mechanisms including the expression of ligands for NK cell-activating receptors on target cells. Different clinical trials indicate that NK cell-based immunotherapy represents a promising antitumor treatment. However, tumors develop immune-evasion strategies, including downregulation of ligands for NK cell-activating receptors, that can negatively affect antitumor activity of NK cells, which either reside endogenously, or are adoptively transferred. Thus, restoration of the expression of NK cell-activating ligands on tumor cells represents a strategic therapeutic goal. As discussed here, various anticancer drugs can fulfill this task via different mechanisms. We envision that the combination of selected chemotherapeutic agents with NK cell adoptive transfer may represent a novel strategy for cancer immunotherapy.
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Affiliation(s)
- Loredana Cifaldi
- Department of Pediatric Haematology/Oncology, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy.
| | - Franco Locatelli
- Department of Pediatric Haematology/Oncology, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy; Department of Pediatric Sciences, University of Pavia, Pavia, Italy
| | - Emiliano Marasco
- Department of Rheumatology, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Lorenzo Moretta
- Immunology Research Area, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Vito Pistoia
- Immunology Research Area, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
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Shiraishi K, Mimura K, Kua LF, Koh V, Siang LK, Nakajima S, Fujii H, Shabbir A, Yong WP, So J, Takenoshita S, Kono K. Inhibition of MMP activity can restore NKG2D ligand expression in gastric cancer, leading to improved NK cell susceptibility. J Gastroenterol 2016; 51:1101-1111. [PMID: 27002316 DOI: 10.1007/s00535-016-1197-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 03/14/2016] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND METHODS Natural killer (NK) cells can react with tumor cells through the balance of inhibitory and stimulatory signals between NK cell surface receptors and their ligands, such as MHC class I chain-related A (MICA), MHC class I chain-related B (MICB), and several UL16-binding proteins (ULBPs). In the present study, we evaluated the relationship between NKG2D ligand expression and matrix metalloproteinase (MMP) activity in in vitro culture systems of a panel of gastric cancer cell lines (n = 10) and clinical samples (n = 102). RESULTS First, the surface expression of NK group 2 member D (NKG2D) ligands (MICA, MICB, ULBP-2, and ULBP-3) on tumor cells was markedly downregulated on in vitro culture, in parallel to the upregulation of MMPs analyzed by gelatin zymography and gene expression microarray, whereas the transcript levels of NKG2D ligands remained unchanged on in vitro culture. Second, MMP-specific inhibitors could restore the downregulated expression of NKG2D ligands and functionally improve susceptibilities to NK cells in vitro. Third, the production of soluble NKG2D ligands was increased on in vitro culture and was inhibited by MMP-specific inhibitors. Finally, there was a significant inverse correlation between MMP-9 expression and NKG2D ligand expression as analyzed by immunohistochemistry in clinical tumor samples. CONCLUSION The present study is a comprehensive study demonstrating that upregulation of MMP activity can induce a downregulation of expression of NKG2D ligands in gastric cancer cells, leading to lower-level susceptibility to NK cells.
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Affiliation(s)
- Kensuke Shiraishi
- Department of Surgery, National University of Singapore, Singapore, Singapore
| | - Kousaku Mimura
- Department of Surgery, National University of Singapore, Singapore, Singapore
| | - Ley-Fang Kua
- Department of Hematology-Oncology, National University of Singapore, Singapore, Singapore
| | - Vivien Koh
- Department of Hematology-Oncology, National University of Singapore, Singapore, Singapore
| | - Lim Kee Siang
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Shotaro Nakajima
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Hideki Fujii
- First Department of Surgery, University of Yamanashi, Kofu, Japan
| | - Asim Shabbir
- Department of Surgery, National University of Singapore, Singapore, Singapore
| | - Wei-Peng Yong
- Department of Hematology-Oncology, National University of Singapore, Singapore, Singapore
| | - Jimmy So
- Department of Surgery, National University of Singapore, Singapore, Singapore
| | - Seiichi Takenoshita
- Department of Advanced Cancer Immunotherapy, Fukushima Medical University, 1 Hikarigaoka, Fukushima City, 960-1295, Japan
| | - Koji Kono
- Department of Surgery, National University of Singapore, Singapore, Singapore. .,Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore. .,Department of Advanced Cancer Immunotherapy, Fukushima Medical University, 1 Hikarigaoka, Fukushima City, 960-1295, Japan. .,Department of Organ Regulatory Surgery, Fukushima Medical University, 1 Hikarigaoka, Fukushima City, 960-1295, Japan.
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6
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Uhlenbrock F, van Andel E, Andresen L, Skov S. A conserved WW domain-like motif regulates invariant chain-dependent cell-surface transport of the NKG2D ligand ULBP2. Mol Immunol 2015; 66:418-27. [PMID: 25983110 DOI: 10.1016/j.molimm.2015.04.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 04/16/2015] [Accepted: 04/22/2015] [Indexed: 11/16/2022]
Abstract
Malignant cells expressing NKG2D ligands on their cell surface can be directly sensed and killed by NKG2D-bearing lymphocytes. To ensure this immune recognition, accumulating evidence suggests that NKG2D ligands are trafficed via alternative pathways to the cell surface. We have previously shown that the NKG2D ligand ULBP2 traffics over an invariant chain (Ii)-dependent pathway to the cell surface. This study set out to elucidate how Ii regulates ULBP2 cell-surface transport: We discovered conserved tryptophan (Trp) residues in the primary protein sequence of ULBP1-6 but not in the related MICA/B. Substitution of Trp to alanine resulted in cell-surface inhibition of ULBP2 in different cancer cell lines. Moreover, the mutated ULBP2 constructs were retained and not degraded inside the cell, indicating a crucial role of this conserved Trp-motif in trafficking. Finally, overexpression of Ii increased surface expression of wt ULBP2 while Trp-mutants could not be expressed, proposing that this Trp-motif is required for an Ii-dependent cell-surface transport of ULBP2. Aberrant soluble ULBP2 is immunosuppressive. Thus, targeting a distinct protein module on the ULBP2 sequence could counteract this abnormal expression of ULBP2.
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Affiliation(s)
- Franziska Uhlenbrock
- Laboratory of Immunology, Section for Experimental Animal Models, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, DK-1870 Frederiksberg, Denmark.
| | - Esther van Andel
- Laboratory of Immunology, Section for Experimental Animal Models, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, DK-1870 Frederiksberg, Denmark
| | - Lars Andresen
- Laboratory of Immunology, Section for Experimental Animal Models, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, DK-1870 Frederiksberg, Denmark
| | - Søren Skov
- Laboratory of Immunology, Section for Experimental Animal Models, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, DK-1870 Frederiksberg, Denmark.
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Hagemann-Jensen M, Uhlenbrock F, Kehlet S, Andresen L, Gabel-Jensen C, Ellgaard L, Gammelgaard B, Skov S. The selenium metabolite methylselenol regulates the expression of ligands that trigger immune activation through the lymphocyte receptor NKG2D. J Biol Chem 2014; 289:31576-90. [PMID: 25258323 DOI: 10.1074/jbc.m114.591537] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
For decades, selenium research has been focused on the identification of active metabolites, which are crucial for selenium chemoprevention of cancer. In this context, the metabolite methylselenol (CH3SeH) is known for its action to selectively kill transformed cells through mechanisms that include increased formation of reactive oxygen species, induction of DNA damage, triggering of apoptosis, and inhibition of angiogenesis. Here we reveal that CH3SeH modulates the cell surface expression of NKG2D ligands. The expression of NKG2D ligands is induced by stress-associated pathways that occur early during malignant transformation and enable the recognition and elimination of tumors by activating the lymphocyte receptor NKG2D. CH3SeH regulated NKG2D ligands both on the transcriptional and the posttranscriptional levels. CH3SeH induced the transcription of MHC class I polypeptide-related sequence MICA/B and ULBP2 mRNA. However, the induction of cell surface expression was restricted to the ligands MICA/B. Remarkably, our studies showed that CH3SeH inhibited ULBP2 surface transport through inhibition of the autophagic transport pathway. Finally, we identified extracellular calcium as being essential for CH3SeH regulation of NKG2D ligands. A balanced cell surface expression of NKG2D ligands is considered to be an innate barrier against tumor development. Therefore, our work indicates that the application of selenium compounds that are metabolized to CH3SeH could improve NKG2D-based immune therapy.
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Affiliation(s)
| | | | - Stephanie Kehlet
- From the Laboratory of Immunology, Department of Veterinary Disease Biology
| | - Lars Andresen
- From the Laboratory of Immunology, Department of Veterinary Disease Biology
| | | | - Lars Ellgaard
- Department of Biology, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Copenhagen, Denmark
| | | | - Søren Skov
- From the Laboratory of Immunology, Department of Veterinary Disease Biology,
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Uhlenbrock F, Hagemann-Jensen M, Kehlet S, Andresen L, Pastorekova S, Skov S. The NKG2D ligand ULBP2 is specifically regulated through an invariant chain-dependent endosomal pathway. THE JOURNAL OF IMMUNOLOGY 2014; 193:1654-65. [PMID: 25024379 DOI: 10.4049/jimmunol.1303275] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Soluble ULBP2 is a marker for poor prognosis in several types of cancer. In this study we demonstrate that both soluble and cell surface-bound ULBP2 is transported via a so far unrecognized endosomal pathway. ULBP2 surface expression, but not MICA/B, could specifically be targeted and retained by affecting endosomal/lysosomal integrity and protein kinase C activity. The invariant chain was further essential for endosomal transport of ULBP2. This novel pathway was identified through screening experiments by which methylselenic acid was found to possess notable NKG2D ligand regulatory properties. The protein kinase C inhibitor methylselenic acid induced MICA/B surface expression but dominantly blocked ULBP2 surface transport. Remarkably, by targeting this novel pathway we could specifically block the production of soluble ULBP2 from different, primary melanomas. Our findings strongly suggest that the endosomal transport pathway constitutes a novel therapeutic target for ULBP2-producing tumors.
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Affiliation(s)
- Franziska Uhlenbrock
- Section for Experimental Animal Models, Laboratory of Immunology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark; and
| | - Michael Hagemann-Jensen
- Section for Experimental Animal Models, Laboratory of Immunology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark; and
| | - Stephanie Kehlet
- Section for Experimental Animal Models, Laboratory of Immunology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark; and
| | - Lars Andresen
- Section for Experimental Animal Models, Laboratory of Immunology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark; and
| | - Silvia Pastorekova
- Department of Molecular Medicine, Institute of Virology, Slovak Academy of Sciences, 845 05 Bratislava, Slovak Republic
| | - Søren Skov
- Section for Experimental Animal Models, Laboratory of Immunology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark; and
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Chitadze G, Bhat J, Lettau M, Janssen O, Kabelitz D. Generation of soluble NKG2D ligands: proteolytic cleavage, exosome secretion and functional implications. Scand J Immunol 2013; 78:120-9. [PMID: 23679194 DOI: 10.1111/sji.12072] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 05/14/2013] [Indexed: 12/23/2022]
Abstract
The activating natural killer group 2 member D (NKG2D) receptor is expressed on NK cells, cytotoxic T cells and additional T cell subsets. Ligands for human NKG2D comprise two groups of MHC class I-related molecules, the MHC class I chain-related proteins A and B (MICA/B) and 6 UL16-binding proteins (ULBP1-6). While NKG2D ligands are absent from most normal cells, expression is induced upon stress and malignant transformation. In fact, most solid tumours and leukaemia/lymphomas constitutively express at least one NKG2D ligand and thereby are susceptible to NKG2D-dependent immunosurveillance. However, soluble NKG2D ligands are released from tumour cells and can down-modulate NKG2D activation as a means of tumour immune escape. In some tumour entities, levels of soluble NKG2D ligands in the serum correlate with tumour progression. NKG2D ligands can be proteolytically shed from the cell surface or liberated from the membrane by phospholipase C in the case of glycosylphosphatidylinositol (GPI)-anchored molecules. Moreover, NKG2D ligands can be secreted in exosomal microvesicles together with other tumour-derived molecules. Depending on the specific tumour/immune cell setting, these various forms of soluble and/or exosome-bound NKG2D ligands can exert multiple effects on NKG2D/NKG2D ligand interactions. In this review, we focus on the role of various proteases in the shedding of human NKG2D ligands from tumour cells and discuss the not completely unanimous reported functional implications of soluble and exosome-secreted NKG2D ligands for immunosurveillance.
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Affiliation(s)
- G Chitadze
- Institute of Immunology, University of Kiel, Kiel, Germany
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