1
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Jiang Y, Yuan Y, Qiao G, Deng Z, Liu Z, Zhang Y, Yu L, Lin H, Ma L, Zhang J. Paradoxical action of PP2A inhibition and its potential for therapeutic sensitization. J Cell Physiol 2024:e31413. [PMID: 39150149 DOI: 10.1002/jcp.31413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Revised: 07/19/2024] [Accepted: 08/07/2024] [Indexed: 08/17/2024]
Abstract
The protein phosphatase 2A (PP2A), a serine/threonine phosphatase, is recognized as a tumor suppressor involved in diverse cellular processes and essential for maintaining cell viability in vivo. However, endogenous inhibitors of PP2A such as cancerous inhibitor of PP2A (CIP2A) and endogenous nuclear protein inhibitor 2 of PP2A (SET) counteract the anticancer function of PP2A, promoting tumorigenesis, development, and drug resistance in tumors. Surprisingly though, contrary to conventional understanding, inhibition of the tumor suppressor gene PP2A with exogenous small molecule compounds can enhance the efficacy of cancer treatment and achieve superior tumor inhibition. Moreover, exogenous PP2A inhibitors resensitize cancers to treatment and provide novel therapeutic strategies for drug-resistant tumors, which warrant further investigation.
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Affiliation(s)
- Yue Jiang
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Ying Yuan
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Guanglei Qiao
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhoufeng Deng
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zimei Liu
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Yan Zhang
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Liping Yu
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Hongjian Lin
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Lijun Ma
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Jianjun Zhang
- Department of Oncology, Shanghai Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
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2
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Clark MC, Lu RO, Ho WS, Dias MH, Bernards R, Forman SJ. A combination of protein phosphatase 2A inhibition and checkpoint immunotherapy: a perfect storm. Mol Oncol 2024. [PMID: 38932511 DOI: 10.1002/1878-0261.13687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/06/2024] [Accepted: 06/04/2024] [Indexed: 06/28/2024] Open
Abstract
Immune checkpoint blockade has emerged as a potent new tool in the war on cancer. However, only a subset of cancer patients benefit from this therapeutic modality, sparking a search for combination therapies to increase the fraction of responding patients. We argue here that inhibition of protein phosphatase 2A (PP2A) is a promising approach to increase responses to immune checkpoint blockade and other therapies that rely on the presence of tumor-reactive T cells. Inhibition of PP2A increases neoantigen expression on tumor cells, activates the cGAS/STING pathway, suppresses regulatory T cells, and increases cytotoxic T cell activation. In preclinical models, inhibition of PP2A synergizes with immune checkpoint blockade and emerging evidence indicates that patients who have tumors with mutations in PP2A respond better to immune checkpoint blockade. Therefore, inhibition of PP2A activity may be an effective way to sensitize cancer cells to immune checkpoint blockade and cell-based therapies using tumor-reactive T cells.
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Affiliation(s)
- Mary C Clark
- Department of Hematology and Hematopoietic Cell Transplantation, City of Hope Medical Center, Duarte, CA, USA
- Department of Clinical and Translational Project Development, City of Hope Medical Center, Duarte, CA, USA
| | - Rongze Olivia Lu
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
- Helen Diller Comprehensive Cancer Center, University of California, San Francisco, CA, USA
| | - Winson S Ho
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
| | - Matheus Henrique Dias
- Division of Molecular Carcinogenesis, Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - René Bernards
- Division of Molecular Carcinogenesis, Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Stephen J Forman
- Department of Hematology and Hematopoietic Cell Transplantation, City of Hope Medical Center, Duarte, CA, USA
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3
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Dias MH, Liudkovska V, Montenegro Navarro J, Giebel L, Champagne J, Papagianni C, Bleijerveld OB, Velds A, Agami R, Bernards R, Cieśla M. The phosphatase inhibitor LB-100 creates neoantigens in colon cancer cells through perturbation of mRNA splicing. EMBO Rep 2024; 25:2220-2238. [PMID: 38600345 PMCID: PMC11094086 DOI: 10.1038/s44319-024-00128-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 03/15/2024] [Accepted: 03/20/2024] [Indexed: 04/12/2024] Open
Abstract
Perturbation of protein phosphorylation represents an attractive approach to cancer treatment. Besides kinase inhibitors, protein phosphatase inhibitors have been shown to have anti-cancer activity. A prime example is the small molecule LB-100, an inhibitor of protein phosphatases 2A/5 (PP2A/PP5), enzymes that affect cellular physiology. LB-100 has proven effective in pre-clinical models in combination with immunotherapy, but the molecular underpinnings of this synergy remain understood poorly. We report here a sensitivity of the mRNA splicing machinery to phosphorylation changes in response to LB-100 in colorectal adenocarcinoma. We observe enrichment for differentially phosphorylated sites within cancer-critical splicing nodes of U2 snRNP, SRSF and hnRNP proteins. Altered phosphorylation endows LB-100-treated colorectal adenocarcinoma cells with differential splicing patterns. In PP2A-inhibited cells, over 1000 events of exon skipping and intron retention affect regulators of genomic integrity. Finally, we show that LB-100-evoked alternative splicing leads to neoantigens that are presented by MHC class 1 at the cell surface. Our findings provide a potential explanation for the pre-clinical and clinical observations that LB-100 sensitizes cancer cells to immune checkpoint blockade.
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Affiliation(s)
- Matheus H Dias
- Division of Molecular Carcinogenesis and Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | | | - Jasmine Montenegro Navarro
- Division of Oncogenomics and Oncode institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Lisanne Giebel
- Division of Oncogenomics and Oncode institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Julien Champagne
- Division of Oncogenomics and Oncode institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Chrysa Papagianni
- Division of Molecular Carcinogenesis and Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Onno B Bleijerveld
- Proteomics Facility, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Arno Velds
- Central Genomics Facility, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Reuven Agami
- Division of Oncogenomics and Oncode institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - René Bernards
- Division of Molecular Carcinogenesis and Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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4
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Qi Y, Li L, Wei Y, Ma F. PP2A as a potential therapeutic target for breast cancer: Current insights and future perspectives. Biomed Pharmacother 2024; 173:116398. [PMID: 38458011 DOI: 10.1016/j.biopha.2024.116398] [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: 12/16/2023] [Revised: 02/28/2024] [Accepted: 03/06/2024] [Indexed: 03/10/2024] Open
Abstract
Breast cancer has become the most prevalent malignancy worldwide; however, therapeutic efficacy is far from satisfactory. To alleviate the burden of this disease, it is imperative to discover novel mechanisms and treatment strategies. Protein phosphatase 2 A (PP2A) comprises a family of mammalian serine/threonine phosphatases that regulate many cellular processes. PP2A is dysregulated in several human diseases, including oncological pathologies, and plays a pivotal role in the initiation and progression of tumours. The role of PP2A as a tumour suppressor has been extensively studied, and its regulation can serve as a target for anticancer therapy. Recent studies have shown that PP2A is a tumour promotor. PP2A-mediated anticancer therapy may involve two opposing mechanisms: activation and inhibition. In general, the contradictory roles of PP2A should not be overlooked, and more work is needed to determine the molecular mechanism by which PP2A affects in tumours. In this review, the literature on the role of PP2A in tumours, especially in breast cancer, was analysed. This review describes relevant targets of breast cancer, such as cell cycle control, DNA damage responses, epidermal growth factor receptor, immune modulation and cell death resistance, which may lead to effective therapeutic strategies or influence drug development in breast cancer.
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Affiliation(s)
- Yalong Qi
- Department of Medical Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Chaoyang District, Pan jia yuan nan Road 17, Beijing 100021, China
| | - Lixi Li
- Department of Medical Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Chaoyang District, Pan jia yuan nan Road 17, Beijing 100021, China
| | - Yuhan Wei
- Department of Medical Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Chaoyang District, Pan jia yuan nan Road 17, Beijing 100021, China
| | - Fei Ma
- Department of Medical Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Chaoyang District, Pan jia yuan nan Road 17, Beijing 100021, China.
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5
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Elguindy M, Young JS, Mondal I, Lu RO, Ho WS. Glioma-Immune Cell Crosstalk in Tumor Progression. Cancers (Basel) 2024; 16:308. [PMID: 38254796 PMCID: PMC10813573 DOI: 10.3390/cancers16020308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 12/21/2023] [Accepted: 01/06/2024] [Indexed: 01/24/2024] Open
Abstract
Glioma progression is a complex process controlled by molecular factors that coordinate the crosstalk between tumor cells and components of the tumor microenvironment (TME). Among these, immune cells play a critical role in cancer survival and progression. The complex interplay between cancer cells and the immune TME influences the outcome of immunotherapy and other anti-cancer therapies. Here, we present an updated view of the pro- and anti-tumor activities of the main myeloid and lymphocyte cell populations in the glioma TME. We review the underlying mechanisms involved in crosstalk between cancer cells and immune cells that enable gliomas to evade the immune system and co-opt these cells for tumor growth. Lastly, we discuss the current and experimental therapeutic options being developed to revert the immunosuppressive activity of the glioma TME. Knowledge of the complex interplay that elapses between tumor and immune cells may help develop new combination treatments able to overcome tumor immune evasion mechanisms and enhance response to immunotherapies.
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Affiliation(s)
| | | | | | | | - Winson S. Ho
- Department of Neurological Surgery, University of California, San Francisco, CA 94143, USA
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6
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Feng Y, Massarelli E, Forman E, Kovach JS, Salgia R, Synold TW. An LC-MS/MS method for simultaneous determination of LB-100 and its active metabolite, endothall, in human plasma. Bioanalysis 2023; 15:1095-1107. [PMID: 37584370 PMCID: PMC10505989 DOI: 10.4155/bio-2023-0078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 07/13/2023] [Indexed: 08/17/2023] Open
Abstract
We have developed and validated a novel LC-MS/MS method for the simultaneous quantification of LB-100 and its active metabolite, endothall, in human plasma following solid-phase extraction. LB-105 and endothall-D6 were used as internal standards. Chromatographic separation was achieved on a Hypercarb™ column using 5 mM (NH4)2CO3 and 30:70 (v/v) 100 mM (NH4)2CO3:acetonitrile as mobile phases. Detection was performed via positive electrospray ionization mode with multiple reaction monitoring. The assay exhibited linearity in the concentration range of 2.5-500 ng/ml for both analytes. Intra- and inter-assay precision and accuracy were within ±11%. LB-100 and endothall recoveries were 78.7 and 86.7%, respectively. The validated LC-MS/MS method enabled the accurate measurement of LB-100 and endothall in patient samples from an ongoing clinical trial (NCT04560972).
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Affiliation(s)
- Ye Feng
- Department of Medical Oncology & Therapeutics Research, City of Hope, 1500 East Duarte Rd, Duarte, CA 91010, USA
| | - Erminia Massarelli
- Department of Medical Oncology & Therapeutics Research, City of Hope, 1500 East Duarte Rd, Duarte, CA 91010, USA
| | - Eric Forman
- LIXTE Biotechnology, Inc. 680 E Colorado Blvd, Suite 180, Pasadena, CA 91101, USA
| | - John S Kovach
- LIXTE Biotechnology, Inc. 680 E Colorado Blvd, Suite 180, Pasadena, CA 91101, USA
| | - Ravi Salgia
- Department of Medical Oncology & Therapeutics Research, City of Hope, 1500 East Duarte Rd, Duarte, CA 91010, USA
| | - Timothy W Synold
- Department of Medical Oncology & Therapeutics Research, City of Hope, 1500 East Duarte Rd, Duarte, CA 91010, USA
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7
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Yu H, Zaveri S, Sattar Z, Schaible M, Perez Gandara B, Uddin A, McGarvey LR, Ohlmeyer M, Geraghty P. Protein Phosphatase 2A as a Therapeutic Target in Pulmonary Diseases. MEDICINA (KAUNAS, LITHUANIA) 2023; 59:1552. [PMID: 37763671 PMCID: PMC10535831 DOI: 10.3390/medicina59091552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/22/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023]
Abstract
New disease targets and medicinal chemistry approaches are urgently needed to develop novel therapeutic strategies for treating pulmonary diseases. Emerging evidence suggests that reduced activity of protein phosphatase 2A (PP2A), a complex heterotrimeric enzyme that regulates dephosphorylation of serine and threonine residues from many proteins, is observed in multiple pulmonary diseases, including lung cancer, smoke-induced chronic obstructive pulmonary disease, alpha-1 antitrypsin deficiency, asthma, and idiopathic pulmonary fibrosis. Loss of PP2A responses is linked to many mechanisms associated with disease progressions, such as senescence, proliferation, inflammation, corticosteroid resistance, enhanced protease responses, and mRNA stability. Therefore, chemical restoration of PP2A may represent a novel treatment for these diseases. This review outlines the potential impact of reduced PP2A activity in pulmonary diseases, endogenous and exogenous inhibitors of PP2A, details the possible PP2A-dependent mechanisms observed in these conditions, and outlines potential therapeutic strategies for treatment. Substantial medicinal chemistry efforts are underway to develop therapeutics targeting PP2A activity. The development of specific activators of PP2A that selectively target PP2A holoenzymes could improve our understanding of the function of PP2A in pulmonary diseases. This may lead to the development of therapeutics for restoring normal PP2A responses within the lung.
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Affiliation(s)
- Howard Yu
- Department of Medicine, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue, Brooklyn, NY 11203, USA; (H.Y.); (S.Z.); (Z.S.); (M.S.); (B.P.G.); (A.U.); (L.R.M.)
| | - Sahil Zaveri
- Department of Medicine, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue, Brooklyn, NY 11203, USA; (H.Y.); (S.Z.); (Z.S.); (M.S.); (B.P.G.); (A.U.); (L.R.M.)
| | - Zeeshan Sattar
- Department of Medicine, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue, Brooklyn, NY 11203, USA; (H.Y.); (S.Z.); (Z.S.); (M.S.); (B.P.G.); (A.U.); (L.R.M.)
| | - Michael Schaible
- Department of Medicine, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue, Brooklyn, NY 11203, USA; (H.Y.); (S.Z.); (Z.S.); (M.S.); (B.P.G.); (A.U.); (L.R.M.)
| | - Brais Perez Gandara
- Department of Medicine, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue, Brooklyn, NY 11203, USA; (H.Y.); (S.Z.); (Z.S.); (M.S.); (B.P.G.); (A.U.); (L.R.M.)
| | - Anwar Uddin
- Department of Medicine, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue, Brooklyn, NY 11203, USA; (H.Y.); (S.Z.); (Z.S.); (M.S.); (B.P.G.); (A.U.); (L.R.M.)
| | - Lucas R. McGarvey
- Department of Medicine, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue, Brooklyn, NY 11203, USA; (H.Y.); (S.Z.); (Z.S.); (M.S.); (B.P.G.); (A.U.); (L.R.M.)
| | | | - Patrick Geraghty
- Department of Medicine, State University of New York Downstate Health Sciences University, 450 Clarkson Avenue, Brooklyn, NY 11203, USA; (H.Y.); (S.Z.); (Z.S.); (M.S.); (B.P.G.); (A.U.); (L.R.M.)
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8
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Mondal I, Das O, Sun R, Gao J, Yu B, Diaz A, Behnan J, Dubey A, Meng Z, Eskandar E, Xu B, Lu RO, Ho WS. PP2Ac Deficiency Enhances Tumor Immunogenicity by Activating STING-Type I Interferon Signaling in Glioblastoma. Cancer Res 2023; 83:2527-2542. [PMID: 37219874 PMCID: PMC10525036 DOI: 10.1158/0008-5472.can-22-3382] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 03/31/2023] [Accepted: 05/19/2023] [Indexed: 05/24/2023]
Abstract
Glioblastoma (GBM) is an immunologically "cold" tumor that does not respond to current immunotherapy. Here, we demonstrate a fundamental role for the α-isoform of the catalytic subunit of protein phosphatase-2A (PP2Ac) in regulating glioma immunogenicity. Genetic ablation of PP2Ac in glioma cells enhanced double-stranded DNA (dsDNA) production and cGAS-type I IFN signaling, MHC-I expression, and tumor mutational burden. In coculture experiments, PP2Ac deficiency in glioma cells promoted dendritic cell (DC) cross-presentation and clonal expansion of CD8+ T cells. In vivo, PP2Ac depletion sensitized tumors to immune-checkpoint blockade and radiotherapy treatment. Single-cell analysis demonstrated that PP2Ac deficiency increased CD8+ T-cell, natural killer cell, and DC accumulation and reduced immunosuppressive tumor-associated macrophages. Furthermore, loss of PP2Ac increased IFN signaling in myeloid and tumor cells and reduced expression of a tumor gene signature associated with worse patient survival in The Cancer Genome Atlas. Collectively, this study establishes a novel role for PP2Ac in inhibiting dsDNA-cGAS-STING signaling to suppress antitumor immunity in glioma. SIGNIFICANCE PP2Ac deficiency promotes cGAS-STING signaling in glioma to induce a tumor-suppressive immune microenvironment, highlighting PP2Ac as a potential therapeutic target to enhance tumor immunogenicity and improve response to immunotherapy.
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Affiliation(s)
- Isha Mondal
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
| | - Oishika Das
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
| | - Raymond Sun
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
| | - Jian Gao
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
| | - Bohyeon Yu
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
| | - Aaron Diaz
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
| | - Jinan Behnan
- The Leo M. Davidoff Department of Neurological Surgery, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
- Dominick Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Abhishek Dubey
- The Leo M. Davidoff Department of Neurological Surgery, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
- Dominick Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Zhipeng Meng
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Emad Eskandar
- The Leo M. Davidoff Department of Neurological Surgery, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
- Dominick Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Beisi Xu
- Center for Applied Bioinformatics, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Rongze Olivia Lu
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
- Helen Diller Comprehensive Cancer Center, University of California, San Francisco, CA, USA
| | - Winson S. Ho
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
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9
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Ho WS, Mondal I, Xu B, Das O, Sun R, Chiou P, Cai X, Tahmasebinia F, McFadden E, Wu CYJ, Wu Z, Matsui W, Lim M, Meng Z, Lu RO. PP2Ac/STRN4 negatively regulates STING-type I IFN signaling in tumor-associated macrophages. J Clin Invest 2023; 133:e162139. [PMID: 36757811 PMCID: PMC10014107 DOI: 10.1172/jci162139] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 02/02/2023] [Indexed: 02/10/2023] Open
Abstract
Stimulator of IFN genes type I (STING-Type I) IFN signaling in myeloid cells plays a critical role in effective antitumor immune responses, but STING agonists as monotherapy have shown limited efficacy in clinical trials. The mechanisms that downregulate STING signaling are not fully understood. Here, we report that protein phosphatase 2A (PP2A), with its specific B regulatory subunit Striatin 4 (STRN4), negatively regulated STING-Type I IFN in macrophages. Mice with macrophage PP2A deficiency exhibited reduced tumor progression. The tumor microenvironment showed decreased immunosuppressive and increased IFN-activated macrophages and CD8+ T cells. Mechanistically, we demonstrated that Hippo kinase MST1/2 was required for STING activation. STING agonists induced dissociation of PP2A from MST1/2 in normal macrophages, but not in tumor conditioned macrophages. Furthermore, our data showed that STRN4 mediated PP2A binding to and dephosphorylation of Hippo kinase MST1/2, resulting in stabilization of YAP/TAZ to antagonize STING activation. In human patients with glioblastoma (GBM), YAP/TAZ was highly expressed in tumor-associated macrophages but not in nontumor macrophages. We also demonstrated that PP2A/STRN4 deficiency in macrophages reduced YAP/TAZ expression and sensitized tumor-conditioned macrophages to STING stimulation. In summary, we demonstrated that PP2A/STRN4-YAP/TAZ has, in our opinion, been an unappreciated mechanism that mediates immunosuppression in tumor-associated macrophages, and targeting the PP2A/STRN4-YAP/TAZ axis can sensitize tumors to immunotherapy.
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Affiliation(s)
- Winson S. Ho
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, Texas, USA
| | - Isha Mondal
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, Texas, USA
| | - Beisi Xu
- Center for Applied Bioinformatics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Oishika Das
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, Texas, USA
| | - Raymond Sun
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, Texas, USA
| | - Pochin Chiou
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, Texas, USA
| | - Xiaomin Cai
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Foozhan Tahmasebinia
- Department of Biological Sciences, Southern Methodist University, Dallas, Texas, USA
| | - Elizabeth McFadden
- Department of Molecular Sciences, University of Texas at Austin, Austin, Texas, USA
| | - Caren Yu-Ju Wu
- Department of Neurosurgery, Stanford University, Stanford, California, USA
| | - Zhihao Wu
- Department of Biological Sciences, Southern Methodist University, Dallas, Texas, USA
| | - William Matsui
- Department of Oncology, Dell Medical School, The University of Texas at Austin, Austin, Texas, USA
| | - Michael Lim
- Department of Neurosurgery, Stanford University, Stanford, California, USA
| | - Zhipeng Meng
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Rongze Olivia Lu
- Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, Texas, USA
- Helen Diller Comprehensive Cancer Center, UCSF, San Francisco, California, USA
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10
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Targeting protein phosphatases in cancer immunotherapy and autoimmune disorders. Nat Rev Drug Discov 2023; 22:273-294. [PMID: 36693907 PMCID: PMC9872771 DOI: 10.1038/s41573-022-00618-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2022] [Indexed: 01/25/2023]
Abstract
Protein phosphatases act as key regulators of multiple important cellular processes and are attractive therapeutic targets for various diseases. Although extensive effort has been dedicated to phosphatase-targeted drug discovery, early expeditions for competitive phosphatase inhibitors were plagued by druggability issues, leading to the stigmatization of phosphatases as difficult targets. Despite challenges, persistent efforts have led to the identification of several drug-like, non-competitive modulators of some of these enzymes - including SH2 domain-containing protein tyrosine phosphatase 2, protein tyrosine phosphatase 1B, vascular endothelial protein tyrosine phosphatase and protein phosphatase 1 - reigniting interest in therapeutic targeting of phosphatases. Here, we discuss recent progress in phosphatase drug discovery, with emphasis on the development of selective modulators that exhibit biological activity. The roles and regulation of protein phosphatases in immune cells and their potential as powerful targets for immuno-oncology and autoimmunity indications are assessed.
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11
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The Pivotal Role of Protein Phosphatase 2A (PP2A) in Brain Tumors. Int J Mol Sci 2022; 23:ijms232415717. [PMID: 36555359 PMCID: PMC9779694 DOI: 10.3390/ijms232415717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/09/2022] [Accepted: 12/10/2022] [Indexed: 12/14/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a highly complex heterotrimeric Ser/Thr phosphatase that regulates many cellular processes. PP2A is dysregulated in several human diseases, including oncological pathology; interestingly, PP2A appears to be essential for controlling cell growth and may be involved in cancer development. The role of PP2A as a tumor suppressor has been extensively studied and reviewed. To leverage the potential clinical utility of combination PP2A inhibition and radiotherapy treatment, it is vital that novel highly specific PP2A inhibitors be developed. In this review, the existing literature on the role of PP2A in brain tumors, especially in gliomas and glioblastoma (GBM), was analyzed. Interestingly, the review focused on the role of PP2A inhibitors, focusing on CIP2A inhibition, as CIP2A participated in tumor cell growth by stimulating cell-renewal survival, cellular proliferation, evasion of senescence and inhibition of apoptosis. This review suggested CIP2A inhibition as a promising strategy in oncology target therapy.
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Ronk H, Rosenblum JS, Kung T, Zhuang Z. Targeting PP2A for cancer therapeutic modulation. Cancer Biol Med 2022; 19:1428-1439. [PMID: 36342229 PMCID: PMC9630519 DOI: 10.20892/j.issn.2095-3941.2022.0330] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 08/26/2022] [Indexed: 09/12/2023] Open
Abstract
Protein phosphatases play essential roles as negative regulators of kinases and signaling cascades involved in cytoskeletal organization. Protein phosphatase 2A (PP2A) is highly conserved and is the predominant serine/threonine phosphatase in the nervous system, constituting more than 70% of all neuronal phosphatases. PP2A is involved in diverse regulatory functions, including cell cycle progression, apoptosis, and DNA repair. Although PP2A has historically been identified as a tumor suppressor, inhibition of PP2A has paradoxically demonstrated potential as a therapeutic target for various cancers. LB100, a water-soluble, small-molecule competitive inhibitor of PP2A, has shown particular promise as a chemo- and radio-sensitizing agent. Preclinical success has led to a profusion of clinical trials on LB100 adjuvant therapies, including a phase I trial in extensive-stage small-cell lung cancer, a phase I/II trial in myelodysplastic syndrome, a phase II trial in recurrent glioblastoma, and a completed phase I trial assessing the safety of LB100 and docetaxel in various relapsed solid tumors. Herein, we review the development of LB100, the role of PP2A in cancer biology, and recent advances in targeting PP2A inhibition in immunotherapy.
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Affiliation(s)
- Halle Ronk
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jared S. Rosenblum
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Timothy Kung
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zhengping Zhuang
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Norcantharidin liposome emulsion hybrid delivery system enhances PD-1/PD-L1 immunotherapy by agonizing the non-canonical NF-κB pathway. Int J Pharm 2022; 628:122361. [DOI: 10.1016/j.ijpharm.2022.122361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/17/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022]
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Kashani E, Vassella E. Pleiotropy of PP2A Phosphatases in Cancer with a Focus on Glioblastoma IDH Wildtype. Cancers (Basel) 2022; 14:5227. [PMID: 36358647 PMCID: PMC9654311 DOI: 10.3390/cancers14215227] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/13/2022] [Accepted: 10/20/2022] [Indexed: 07/29/2023] Open
Abstract
Serine/Threonine protein phosphatase 2A (PP2A) is a heterotrimeric (or occasionally, heterodimeric) phosphatase with pleiotropic functions and ubiquitous expression. Despite the fact that they all contribute to protein dephosphorylation, multiple PP2A complexes exist which differ considerably by their subcellular localization and their substrate specificity, suggesting diverse PP2A functions. PP2A complex formation is tightly regulated by means of gene expression regulation by transcription factors, microRNAs, and post-translational modifications. Furthermore, a constant competition between PP2A regulatory subunits is taking place dynamically and depending on the spatiotemporal circumstance; many of the integral subunits can outcompete the rest, subjecting them to proteolysis. PP2A modulation is especially important in the context of brain tumors due to its ability to modulate distinct glioma-promoting signal transduction pathways, such as PI3K/Akt, Wnt, Ras, NF-κb, etc. Furthermore, PP2A is also implicated in DNA repair and survival pathways that are activated upon treatment of glioma cells with chemo-radiation. Depending on the cancer cell type, preclinical studies have shown some promise in utilising PP2A activator or PP2A inhibitors to overcome therapy resistance. This review has a special focus on "glioblastoma, IDH wild-type" (GBM) tumors, for which the therapy options have limited efficacy, and tumor relapse is inevitable.
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Affiliation(s)
- Elham Kashani
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Erik Vassella
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
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Zhao S, Xu B, Ma W, Chen H, Jiang C, Cai J, Meng X. DNA Damage Repair in Brain Tumor Immunotherapy. Front Immunol 2022; 12:829268. [PMID: 35095931 PMCID: PMC8792754 DOI: 10.3389/fimmu.2021.829268] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 12/22/2021] [Indexed: 12/01/2022] Open
Abstract
With the gradual understanding of tumor development, many tumor therapies have been invented and applied in clinical work, and immunotherapy has been widely concerned as an emerging hot topic in the last decade. It is worth noting that immunotherapy is nowadays applied under too harsh conditions, and many tumors are defined as “cold tumors” that are not sensitive to immunotherapy, and brain tumors are typical of them. However, there is much evidence that suggests a link between DNA damage repair mechanisms and immunotherapy. This may be a breakthrough for the application of immunotherapy in brain tumors. Therefore, in this review, first, we will describe the common pathways of DNA damage repair. Second, we will focus on immunotherapy and analyze the mechanisms of DNA damage repair involved in the immune process. Third, we will review biomarkers that have been or may be used to evaluate immunotherapy for brain tumors, such as TAMs, RPA, and other molecules that may provide a precursor assessment for the rational implementation of immunotherapy for brain tumors. Finally, we will discuss the rational combination of immunotherapy with other therapeutic approaches that have an impact on the DNA damage repair process in order to open new pathways for the application of immunotherapy in brain tumors, to maximize the effect of immunotherapy on DNA damage repair mechanisms, and to provide ideas and guidance for immunotherapy in brain tumors.
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Affiliation(s)
- Shihong Zhao
- Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Boya Xu
- Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Wenbin Ma
- Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Hao Chen
- Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Chuanlu Jiang
- Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Jinquan Cai
- Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Xiangqi Meng
- Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
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Ai X, Yan J, Pogwizd SM. Serine-threonine protein phosphatase regulation of Cx43 dephosphorylation in arrhythmogenic disorders. Cell Signal 2021; 86:110070. [PMID: 34217833 PMCID: PMC8963383 DOI: 10.1016/j.cellsig.2021.110070] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 06/11/2021] [Accepted: 06/29/2021] [Indexed: 12/11/2022]
Abstract
Regulation of cell-to-cell communication in the heart by the gap junction protein Connexin43 (Cx43) involves modulation of Cx43 phosphorylation state by protein kinases, and dephosphorylation by protein phosphatases. Dephosphorylation of Cx43 has been associated with impaired intercellular coupling and enhanced arrhythmogenesis in various pathologic states. While there has been extensive study of the protein kinases acting on Cx43, there has been limited studies of the protein phosphatases that may underlie Cx43 dephosphorylation. The focus of this review is to introduce serine-threonine protein phosphatase regulation of Cx43 phosphorylation state and cell-to-cell communication, and its impact on arrhythmogenesis in the setting of chronic heart failure and myocardial ischemia, as well as on atrial fibrillation. We also discuss the therapeutic potential of modulating protein phosphatases to treat arrhythmias in these clinical settings.
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Affiliation(s)
- Xun Ai
- Department of Physiology & Biophysics, Rush University, Chicago, IL, United States of America
| | - Jiajie Yan
- Department of Physiology & Biophysics, Rush University, Chicago, IL, United States of America
| | - Steven M Pogwizd
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States of America.
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Bryant JP, Levy A, Heiss J, Banasavadi-Siddegowda YK. Review of PP2A Tumor Biology and Antitumor Effects of PP2A Inhibitor LB100 in the Nervous System. Cancers (Basel) 2021; 13:cancers13123087. [PMID: 34205611 PMCID: PMC8235527 DOI: 10.3390/cancers13123087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Central and peripheral nervous system tumors represent a heterogenous group of neoplasms which often demonstrate resistance to treatment. Given that these tumors are often refractory to conventional therapy, novel pharmaceutical regimens are needed for successfully treating this pathology. One such therapeutic is the serine/threonine phosphatase inhibitor, LB100. LB100 is a water-soluble competitive protein phosphtase inhibitor that has demonstrated antitumor effects in preclinical and clinical trials. In this review, we aim to summarize current evidence demonstrating the efficacy of LB100 as an inhibitor of nervous system tumors. Furthermore, we review the involvement of the well-studied phosphatase, protein phosphatase 2A, in oncogenic cell signaling pathways, neurophysiology, and neurodevelopment. Abstract Protein phosphatase 2A (PP2A) is a ubiquitous serine/threonine phosphatase implicated in a wide variety of regulatory cellular functions. PP2A is abundant in the mammalian nervous system, and dysregulation of its cellular functions is associated with myriad neurodegenerative disorders. Additionally, PP2A has oncologic implications, recently garnering attention and emerging as a therapeutic target because of the antitumor effects of a potent PP2A inhibitor, LB100. LB100 abrogation of PP2A is believed to exert its inhibitory effects on tumor progression through cellular chemo- and radiosensitization to adjuvant agents. An updated and unifying review of PP2A biology and inhibition with LB100 as a therapeutic strategy for targeting cancers of the nervous system is needed, as other reviews have mainly covered broader applications of LB100. In this review, we discuss the role of PP2A in normal cells and tumor cells of the nervous system. Furthermore, we summarize current evidence regarding the therapeutic potential of LB100 for treating solid tumors of the nervous system.
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Affiliation(s)
- Jean-Paul Bryant
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (J.-P.B.); (J.H.)
| | - Adam Levy
- Miller School of Medicine, University of Miami, Miami, FL 33136, USA;
| | - John Heiss
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (J.-P.B.); (J.H.)
| | - Yeshavanth Kumar Banasavadi-Siddegowda
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (J.-P.B.); (J.H.)
- Correspondence: ; Tel.: +1-301-451-0970
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Wouters R, Bevers S, Riva M, De Smet F, Coosemans A. Immunocompetent Mouse Models in the Search for Effective Immunotherapy in Glioblastoma. Cancers (Basel) 2020; 13:E19. [PMID: 33374542 PMCID: PMC7793150 DOI: 10.3390/cancers13010019] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/19/2020] [Accepted: 12/20/2020] [Indexed: 12/12/2022] Open
Abstract
Glioblastoma (GBM) is the most aggressive intrinsic brain tumor in adults. Despite maximal therapy consisting of surgery and radio/chemotherapy, GBM remains largely incurable with a median survival of less than 15 months. GBM has a strong immunosuppressive nature with a multitude of tumor and microenvironment (TME) derived factors that prohibit an effective immune response. To date, all clinical trials failed to provide lasting clinical efficacy, despite the relatively high success rates of preclinical studies to show effectivity of immunotherapy. Various factors may explain this discrepancy, including the inability of a single mouse model to fully recapitulate the complexity and heterogeneity of GBM. It is therefore critical to understand the features and limitations of each model, which should probably be combined to grab the full spectrum of the disease. In this review, we summarize the available knowledge concerning immune composition, stem cell characteristics and response to standard-of-care and immunotherapeutics for the most commonly available immunocompetent mouse models of GBM.
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Affiliation(s)
- Roxanne Wouters
- Laboratory of Tumor Immunology and Immunotherapy, Department of Oncology, Leuven Cancer Institute, KU Leuven, 3000 Leuven, Belgium; (R.W.); (S.B.); (M.R.)
- Oncoinvent, A.S., 0484 Oslo, Norway
| | - Sien Bevers
- Laboratory of Tumor Immunology and Immunotherapy, Department of Oncology, Leuven Cancer Institute, KU Leuven, 3000 Leuven, Belgium; (R.W.); (S.B.); (M.R.)
- The Laboratory for Precision Cancer Medicine, Translational Cell and Tissue Research Unit, Department of Imaging and Pathology, KU Leuven, 3000 Leuven, Belgium;
| | - Matteo Riva
- Laboratory of Tumor Immunology and Immunotherapy, Department of Oncology, Leuven Cancer Institute, KU Leuven, 3000 Leuven, Belgium; (R.W.); (S.B.); (M.R.)
- Department of Neurosurgery, Mont-Godinne Hospital, UCL Namur, 5530 Yvoir, Belgium
| | - Frederik De Smet
- The Laboratory for Precision Cancer Medicine, Translational Cell and Tissue Research Unit, Department of Imaging and Pathology, KU Leuven, 3000 Leuven, Belgium;
| | - An Coosemans
- Laboratory of Tumor Immunology and Immunotherapy, Department of Oncology, Leuven Cancer Institute, KU Leuven, 3000 Leuven, Belgium; (R.W.); (S.B.); (M.R.)
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