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Graner MW. Roles of Extracellular Vesicles in High-Grade Gliomas: Tiny Particles with Outsized Influence. Annu Rev Genomics Hum Genet 2019; 20:331-357. [PMID: 30978305 DOI: 10.1146/annurev-genom-083118-015324] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
High-grade gliomas, particularly glioblastomas (grade IV), are devastating diseases with dismal prognoses; afflicted patients seldom live longer than 15 months, and their quality of life suffers immensely. Our current standard-of-care therapy has remained essentially unchanged for almost 15 years, with little new therapeutic progress. We desperately need a better biologic understanding of these complicated tumors in a complicated organ. One area of rejuvenated study relates to extracellular vesicles (EVs)-membrane-enclosed nano- or microsized particles that originate from the endosomal system or are shed from the plasma membrane. EVs contribute to tumor heterogeneity (including the maintenance of glioma stem cells or their differentiation), the impacts of hypoxia (angiogenesis and coagulopathies), interactions amid the tumor microenvironment (concerning the survival of astrocytes, neurons, endothelial cells, blood vessels, the blood-brain barrier, and the ensuing inflammation), and influences on the immune system (both stimulatory and suppressive). This article reviews glioma EVs and the ways that EVs manifest themselves as autocrine, paracrine, and endocrine factors in proximal and distal intra- and intercellular communications. The reader should note that there is much controversy, and indeed confusion, in the field over the exact roles for EVs in many biological processes, and we will engage some of these difficulties herein.
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Affiliation(s)
- Michael W Graner
- Department of Neurosurgery, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado 80045, USA;
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Proteomic analyses of brain tumor cell lines amidst the unfolded protein response. Oncotarget 2018; 7:47831-47847. [PMID: 27323862 PMCID: PMC5216982 DOI: 10.18632/oncotarget.10032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 05/23/2016] [Indexed: 01/08/2023] Open
Abstract
Brain tumors such as high grade gliomas are among the deadliest forms of human cancers. The tumor environment is subject to a number of cellular stressors such as hypoxia and glucose deprivation. The persistence of the stressors activates the unfolded proteins response (UPR) and results in global alterations in transcriptional and translational activity of the cell. Although the UPR is known to effect tumorigenesis in some epithelial cancers, relatively little is known about the role of the UPR in brain tumors. Here, we evaluated the changes at the molecular level under homeostatic and stress conditions in two glioma cell lines of differing tumor grade. Using mass spectrometry analysis, we identified proteins unique to each condition (unstressed/stressed) and within each cell line (U87MG and UPN933). Comparing the two, we find differences between both the conditions and cell lines indicating a unique profile for each. Finally, we used our proteomic data to identify the predominant pathways within these cells under unstressed and stressed conditions. Numerous predominant pathways are the same in both cell lines, but there are differences in biological and molecular classifications of the identified proteins, including signaling mechanisms, following UPR induction; we see that relatively minimal proteomic alterations can lead to signaling changes that ultimately promote cell survival.
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Graner AN, Hellwinkel JE, Lencioni AM, Madsen HJ, Harland TA, Marchando P, Nguyen GJ, Wang M, Russell LM, Bemis LT, Anchordoquy TJ, Graner MW. HSP90 inhibitors in the context of heat shock and the unfolded protein response: effects on a primary canine pulmonary adenocarcinoma cell line. Int J Hyperthermia 2016; 33:303-317. [PMID: 27829290 DOI: 10.1080/02656736.2016.1256503] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Agents targeting HSP90 and GRP94 are seldom tested in stressed contexts such as heat shock (HS) or the unfolded protein response (UPR). Tumor stress often activates HSPs and the UPR as pro-survival mechanisms. This begs the question of stress effects on chemotherapeutic efficacy, particularly with drugs targeting chaperones such as HSP90 or GRP94. We tested the utility of several HSP90 inhibitors, including PU-H71 (targeting GRP94), on a primary canine lung cancer line under HS/UPR stress compared to control conditions. METHODS We cultured canine bronchoalveolar adenocarcinoma cells that showed high endogenous HSP90 and GRP94 expression; these levels substantially increased upon HS or UPR induction. We treated cells with HSP90 inhibitors 17-DMAG, 17-AAG or PU-H71 under standard conditions, HS or UPR. Cell viability/survival was assayed. Antibody arrays measured intracellular signalling and apoptosis profiles. RESULTS HS and UPR had varying effects on cells treated with different HSP90 inhibitors; in particular, HS and UPR promoted resistance to inhibitors in short-term assays, but combinations of UPR stress and PU-H571 showed potent cytotoxic activity in longer-term assays. Array data indicated altered signalling pathways, with apoptotic and pro-survival implications. UPR induction + dual targeting of HSP90 and GRP94 swayed the balance toward apoptosis. CONCLUSION Cellular stresses, endemic to tumors, or interventionally inducible, can deflect or enhance chemo-efficacy, particularly with chaperone-targeting drugs. Stress is likely not held accountable when testing new pharmacologics or assessing currently-used drugs. A better understanding of stress impacts on drug activities should be critical in improving therapeutic targeting and in discerning mechanisms of drug resistance.
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Affiliation(s)
- Arin N Graner
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA
| | - Justin E Hellwinkel
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA.,b School of Medicine , University of Colorado School of Medicine , Aurora , CO , USA
| | - Alex M Lencioni
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA.,c University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Helen J Madsen
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA.,b School of Medicine , University of Colorado School of Medicine , Aurora , CO , USA
| | - Tessa A Harland
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA.,b School of Medicine , University of Colorado School of Medicine , Aurora , CO , USA
| | - Paul Marchando
- d Department of Chemical and Biological Engineering , University of Colorado Boulder , Boulder , CO , USA
| | - Ger J Nguyen
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA
| | - Mary Wang
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA
| | - Laura M Russell
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA
| | - Lynne T Bemis
- e Department of Biomedical Sciences , University of Minnesota , Duluth , MN , USA
| | - Thomas J Anchordoquy
- f Skaggs School of Pharmacy and Pharmaceutical Sciences , University of Colorado Denver , Aurora , CO , USA
| | - Michael W Graner
- a Department of Neurosurgery , University of Colorado Denver , Aurora , CO , USA
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Abstract
Heat-shock protein 90 (HSP90) is a highly conserved molecular chaperone that plays prominent functional roles in nearly all aspects of cell biology. As a chaperone, it interacts with literally hundreds of "clients," many of which are important drivers, regulators, and promoters of cancer. Thus, HSP90 is a high-value target in the development of anticancer therapeutics. Despite its popularity, our overall knowledge of HSP90 in immune function has lagged behind its well-recognized tumor-supportive roles. The use of inhibitors of HSP90 as chemical biological probes has been invaluable in revealing important roles for the chaperone in multiple aspects of immune function. Given this critical link, we must now consider the question of how immune outcomes may be affected by the HSP90 inhibitors currently in clinical development for the treatment of cancer. This chapter will review some of the immunological aspects of HSP90 function in terms of its intracellular and extracellular roles in antigen presentation, immune effector cell tasks, and regulation of inflammatory processes. This review will further examine the value of HSP90 inhibitors within the context of cancer immunotherapy and will discuss how these drugs might be optimally utilized in combination with immune stimulatory approaches against cancer.
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The Dichotomy of Tumor Exosomes (TEX) in Cancer Immunity: Is It All in the ConTEXt? Vaccines (Basel) 2015; 3:1019-51. [PMID: 26694473 PMCID: PMC4693230 DOI: 10.3390/vaccines3041019] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 11/24/2015] [Accepted: 12/05/2015] [Indexed: 02/06/2023] Open
Abstract
Exosomes are virus-sized nanoparticles (30–130 nm) formed intracellularly as intravesicular bodies/intralumenal vesicles within maturing endosomes (“multivesicular bodies”, MVBs). If MVBs fuse with the cell’s plasma membrane, the interior vesicles may be released extracellularly, and are termed “exosomes”. The protein cargo of exosomes consists of cytosolic, membrane, and extracellular proteins, along with membrane-derived lipids, and an extraordinary variety of nucleic acids. As such, exosomes reflect the status and identity of the parent cell, and are considered as tiny cellular surrogates. Because of this closely entwined relationship between exosome content and the source/status of the parental cell, conceivably exosomes could be used as vaccines against various pathologies, as they contain antigens associated with a given disease, e.g., cancer. Tumor-derived exosomes (TEX) have been shown to be potent anticancer vaccines in animal models, driving antigen-specific T and B cell responses, but much recent literature concerning TEX strongly places the vesicles as powerfully immunosuppressive. This dichotomy suggests that the context in which the immune system encounters TEX is critical in determining immune stimulation versus immunosuppression. Here, we review literature on both sides of this immune coin, and suggest that it may be time to revisit the concept of TEX as anticancer vaccines in clinical settings.
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Abstract
Glioblastomas are devastating central nervous system tumors with abysmal prognoses. These tumors are often difficult to resect surgically, are highly invasive and proliferative, and are resistant to virtually all therapeutic attempts, making them universally lethal diseases. One key enabling feature of their tumor biology is the engagement of the unfolded protein response (UPR), a stress response originating in the endoplasmic reticulum (ER) designed to handle the pathologies of aggregating malfolded proteins in that organelle. Glioblastomas and other tumors have co-opted this stress response to allow their continued uncontrolled growth by enhanced protein production (maintained by chaperone-assisted protein folding) and lipid biosynthesis driven downstream of the UPR. These features can account for the extensive extracellular remodeling/invasiveness/angiogenesis and proliferative capacity, and ultimately result in tumor phenotypes of chemo- and radio-resistance. The UPR in general, and its chaperoning capacity in particular, are thus putative high-value targets for treatment intervention. Such therapeutic strategies, and potential problems with them, will be discussed and analyzed.
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Graner MW. The unfolded protein response in glioblastomas: passing the stress test. CNS Oncol 2015; 2:469-72. [PMID: 25054814 DOI: 10.2217/cns.13.50] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Michael W Graner
- University of Colorado School of Medicine, Anschutz Medical Campus, Department of Neurosurgery, Aurora, CO 80045, USA.
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Graner MW, Lillehei KO, Katsanis E. Endoplasmic reticulum chaperones and their roles in the immunogenicity of cancer vaccines. Front Oncol 2015; 4:379. [PMID: 25610811 PMCID: PMC4285071 DOI: 10.3389/fonc.2014.00379] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/17/2014] [Indexed: 11/25/2022] Open
Abstract
The endoplasmic reticulum (ER) is a major site of passage for proteins en route to other organelles, to the cell surface, and to the extracellular space. It is also the transport route for peptides generated in the cytosol by the proteasome into the ER for loading onto major histocompatibility complex class I (MHC I) molecules for eventual antigen presentation at the cell surface. Chaperones within the ER are critical for many of these processes; however, outside the ER certain of those chaperones may play important and direct roles in immune responses. In some cases, particular ER chaperones have been utilized as vaccines against tumors or infectious disease pathogens when purified from tumor tissue or recombinantly generated and loaded with antigen. In other cases, the cell surface location of ER chaperones has implications for immune responses as well as possible tumor resistance. We have produced heat-shock protein/chaperone protein-based cancer vaccines called “chaperone-rich cell lysate” (CRCL) that are conglomerates of chaperones enriched from solid tumors by an isoelectric focusing technique. These preparations have been effective against numerous murine tumors, as well as in a canine with an advanced lung carcinoma treated with autologous CRCL. We also published extensive proteomic analyses of CRCL prepared from human surgically resected tumor samples. Of note, these preparations contained at least 10 ER chaperones and a number of other residents, along with many other chaperones/heat-shock proteins. Gene ontology and network analyses utilizing these proteins essentially recapitulate the antigen presentation pathways and interconnections. In conjunction with our current knowledge of cell surface/extracellular ER chaperones, these data collectively suggest that a systems-level view may provide insight into the potent immune stimulatory activities of CRCL with an emphasis on the roles of ER components in those processes.
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Affiliation(s)
- Michael W Graner
- Department of Neurosurgery, Anschutz Medical Campus, University of Colorado School of Medicine , Aurora, CO , USA
| | - Kevin O Lillehei
- Department of Neurosurgery, Anschutz Medical Campus, University of Colorado School of Medicine , Aurora, CO , USA
| | - Emmanuel Katsanis
- Department of Pediatrics, The University of Arizona , Tucson, AZ , USA
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Abstract
Although advances in surgery, radiation therapy and stereotactic radiosurgery have significantly improved the treatment of meningiomas, there remains an important subset of patients who remain refractory to conventional therapy. Treatment with chemotherapeutic agents such as hydroxyurea and alpha-interferon has provided minimal benefit. In this review, the role of newly emerging novel therapies for meningiomas, with a focus on targeted molecular agents, will be discussed.
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Affiliation(s)
- Patrick Y Wen
- Center for Neuro-Oncology Dana-Farber/Brigham and Women's Cancer Center, and Division of Neuro-Oncology, Department of Neurology, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Marshall D, Mitchell DA, Graner MW, Bigner DD. Immunotherapy of brain tumors. HANDBOOK OF CLINICAL NEUROLOGY 2012; 104:309-30. [PMID: 22230450 DOI: 10.1016/b978-0-444-52138-5.00020-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Wen PY, Quant E, Drappatz J, Beroukhim R, Norden AD. Medical therapies for meningiomas. J Neurooncol 2010; 99:365-78. [PMID: 20820875 DOI: 10.1007/s11060-010-0349-8] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 08/06/2010] [Indexed: 12/31/2022]
Abstract
Meningiomas are the most common primary brain tumor in adults. Although the majority of these tumors can be effectively treated with surgery and radiation therapy, an important subset of patients have inoperable tumors, or develop recurrent disease after surgery and radiotherapy, and require some form of medical therapy. There are increasing numbers of studies evaluating various medical therapies but the results remain disappointing. Chemotherapies and hormonal therapies have been generally ineffective, although somatostatin analogues may have therapeutic potential. There is also increasing interest in targeted molecular therapies. Agents inhibiting platelet derived growth factor receptors and epidermal growth factor receptors have shown little efficacy, but molecular agents inhibiting vascular endothelial growth factor receptors appear to have some promise. As with other tumors, advances in the medical therapies for meningiomas will require improved understanding of the molecular pathogenesis of these tumors, more predictive preclinical models, and efficient mechanisms for conducting clinical trials, given the small population of eligible patients.
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Affiliation(s)
- Patrick Y Wen
- Center for Neuro-Oncology, Department of Medical Oncology, Dana-Farber/Brigham and Women's Cancer Center, Boston, MA 02115, USA.
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Abstract
Glioblastoma multiforme is the most common primary central nervous system tumor. The prognosis for these malignant brain tumors is poor, with a median survival of 14 months and a 5-year survival rate below 2%. Development of novel treatments is essential to improving survival and quality of life for these patients. Endogenous heat shock proteins have been implicated in mediation of both adaptive and innate immunity, and there is a rising interest in the use of this safe and multifaceted heat shock protein vaccine therapy as a promising treatment for human cancers, including glioblastoma multiforme.
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Affiliation(s)
- Isaac Yang
- Department of Neurological Surgery, University of California at San Francisco, 505 Parnassus Avenue, Room M779, Campus 0112, San Francisco, CA 94143, USA.
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The heat shock response and chaperones/heat shock proteins in brain tumors: surface expression, release, and possible immune consequences. J Neurosci 2007; 27:11214-27. [PMID: 17942716 DOI: 10.1523/jneurosci.3588-07.2007] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The heat shock response is a highly conserved "stress response" mechanism used by cells to protect themselves from potentially damaging insults. It often involves the upregulated expression of chaperone and heat shock proteins (HSPs) to prevent damage and aggregation at the proteome level. Like most cancers, brain tumor cells often overexpress chaperones/HSPs, probably because of the stressful atmosphere in which tumors reside, but also because of the benefits of HSP cytoprotection. However, the cellular dynamics and localization of HSPs in either stressed or unstressed conditions has not been studied extensively in brain tumor cells. We have examined the changes in HSP expression and in cell surface/extracellular localization of selected brain tumor cell lines under heat shock or normal environments. We herein report that brain tumor cell lines have considerable heat shock responses or already high constitutive HSP levels; that those cells express various HSPs, chaperones, and at least one cochaperone on their cell surfaces; and that HSPs may be released into the extracellular environment, possibly as exosome vesicular content. In studies with a murine astrocytoma cell line, heat shock dramatically reduces tumorigenicity, possibly by an immune mechanism. Additional evidence indicative of an HSP-driven immune response comes from immunization studies using tumor-derived chaperone protein vaccines, which lead to antigen-specific immune responses and reduced tumor burden in treated mice. The heat shock response and HSPs in brain tumor cells may represent an area of vulnerability in our attempts to treat these recalcitrant and deadly tumors.
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Abstract
✓ Although advances in surgery, radiation therapy, and stereotactic radiosurgery have significantly improved the treatment of meningiomas, there remains an important subset of patients whose tumors are refractory to conventional therapy. Treatment with traditional chemotherapeutic agents has provided minimal benefit. In this review, the role of targeted molecular therapies for recurrent or progressive meningiomas is discussed.
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