1
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Johnson H, Narayan S, Sharma AK. Altering phosphorylation in cancer through PP2A modifiers. Cancer Cell Int 2024; 24:11. [PMID: 38184584 PMCID: PMC10770906 DOI: 10.1186/s12935-023-03193-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Accepted: 12/25/2023] [Indexed: 01/08/2024] Open
Abstract
Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase integral to the regulation of many cellular processes. Due to the deregulation of PP2A in cancer, many of these processes are turned toward promoting tumor progression. Considerable research has been undertaken to discover molecules capable of modulating PP2A activity in cancer. Because PP2A is capable of immense substrate specificity across many cellular processes, the therapeutic targeting of PP2A in cancer can be completed through either enzyme inhibitors or activators. PP2A modulators likewise tend to be effective in drug-resistant cancers and work synergistically with other known cancer therapeutics. In this review, we will discuss the patterns of PP2A deregulation in cancer, and its known downstream signaling pathways important for cancer regulation, along with many activators and inhibitors of PP2A known to inhibit cancer progression.
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Affiliation(s)
- Hannah Johnson
- Department of Pharmacology, Penn State Cancer Institute, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Satya Narayan
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL, 32610, USA
| | - Arun K Sharma
- Department of Pharmacology, Penn State Cancer Institute, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
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2
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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: 5] [Impact Index Per Article: 5.0] [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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3
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Hu B, Hao S, Miao Y, Deng Y, Wang J, Wan H, Zhang S, Ji N, Feng J. Inhibiting PP2A Upregulates B7-H3 Expression and Potentially Increases the Sensitivity of Malignant Meningiomas to Immunotherapy by Proteomics. Pathol Oncol Res 2022; 28:1610572. [PMID: 36203966 PMCID: PMC9530036 DOI: 10.3389/pore.2022.1610572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 09/02/2022] [Indexed: 12/03/2022]
Abstract
Malignant meningiomas have a high mortality rate and short survival time and currently have no effective treatment. In our study, proteomics analysis was performed to identify highly expressed proteins as therapeutic targets in malignant meningiomas. Cell Counting Kit-8 (CCK-8) assays were performed to verify the effect of LB-100 on the growth of malignant meningiomas. In addition, immunoblotting was used to verify the expression of B7-H3 and phosphorylation of STAT1 (Tyr701) in tissues and cells. Our results show that STAT1 and CD276 (B7-H3) regulated by PP2A were enriched in GO_IMMUNE_EFFECTOR_PROCESS and GO_REGULATION_OF_IMMUNE_SYSTEM_PROCESS. The immunotherapy target protein B7-H3 was confirmed to be upregulated in malignant meningiomas compared with meningothelial (p = 0.0001) and fibroblastic (p = 0.0046) meningiomas. In vitro, the PP2A inhibitor LB-100 suppressed the growth and invasion of malignant meningioma cells. Notably, the PP2A inhibitor LB-100 increased the phosphorylation of STAT1, thereby increasing the expression of the immune checkpoint protein B7-H3 in malignant meningioma cells in vitro. In conclusion, B7-H3 was found to be upregulated in malignant meningiomas. The PP2A inhibitor LB-100 increased the phosphorylation of STAT1 and B7-H3 expression, which could increase the sensitivity of malignant meningiomas to B7-H3 targeted immunotherapy.
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Affiliation(s)
- Boyi Hu
- Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
| | - Shuyu Hao
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yazhou Miao
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yuxuan Deng
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jing Wang
- Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
| | - Hong Wan
- Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
| | - Shaodong Zhang
- Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
| | - Nan Ji
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jie Feng
- Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
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Migliavacca J, Züllig B, Capdeville C, Grotzer MA, Baumgartner M. Cooperation of Striatin 3 and MAP4K4 promotes growth and tissue invasion. Commun Biol 2022; 5:795. [PMID: 35941177 PMCID: PMC9360036 DOI: 10.1038/s42003-022-03708-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 07/12/2022] [Indexed: 11/09/2022] Open
Abstract
MAP4K4 is associated with increased motility and reduced proliferation in tumor cells, but the regulation of this dichotomous functionality remained elusive. We find that MAP4K4 interacts with striatin 3 and 4 (STRN3/4) and that STRN3 and MAP4K4 exert opposing functions in Hippo signaling and clonal growth. However, depletion of either STRN3 or MAP4K4 in medulloblastoma cells reduces invasion, and loss of both proteins abrogates tumor cell growth in the cerebellar tissue. Mechanistically, STRN3 couples MAP4K4 to the protein phosphatase 2A, which inactivates growth repressing activities of MAP4K4. In parallel, STRN3 enables growth factor-induced PKCθ activation and direct phosphorylation of VASPS157 by MAP4K4, which both are necessary for efficient cell invasion. VASPS157 directed activity of MAP4K4 and STRN3 requires the CNH domain of MAP4K4, which mediates its interaction with striatins. Thus, STRN3 is a master regulator of MAP4K4 function, and disruption of its cooperation with MAP4K4 reactivates Hippo signaling and represses tissue invasion in medulloblastoma. Analysis of the MAP4K4-STRN3 cooperation in medulloblastoma reveals its opposing regulation of Hippo activation and tissue invasion in cancer.
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Affiliation(s)
- Jessica Migliavacca
- Pediatric Molecular Neuro-Oncology Research, Division of Oncology, Children's Research Center, University Children's Hospital Zürich, Zürich, Switzerland
| | - Buket Züllig
- Pediatric Molecular Neuro-Oncology Research, Division of Oncology, Children's Research Center, University Children's Hospital Zürich, Zürich, Switzerland
| | - Charles Capdeville
- Pediatric Molecular Neuro-Oncology Research, Division of Oncology, Children's Research Center, University Children's Hospital Zürich, Zürich, Switzerland
| | - Michael A Grotzer
- Division of Oncology, University Children's Hospital Zürich, Zürich, Switzerland
| | - Martin Baumgartner
- Pediatric Molecular Neuro-Oncology Research, Division of Oncology, Children's Research Center, University Children's Hospital Zürich, Zürich, Switzerland.
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5
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STAT3 in medulloblastoma: a key transcriptional regulator and potential therapeutic target. Mol Biol Rep 2022; 49:10635-10652. [PMID: 35716286 DOI: 10.1007/s11033-022-07694-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/08/2022] [Indexed: 10/18/2022]
Abstract
Medulloblastoma is the most common malignant brain tumor of childhood accounting for about 60% of all pediatric embryonal tumors. Despite improvements in the overall survival rate, this tumor still lacks an efficient, reliable, and less toxic therapeutic approach. Characterization of the molecular mechanisms involved in medulloblastoma initiation and progression is a crucial step for the development of effective therapies. Signal transducer and activator of transcription 3 is a convergence point for several signaling cascades that are implicated in medulloblastoma tumorigenesis. Accumulated evidence has revealed the pivotal role of signal transducer and activator of transcription 3 in medulloblastoma pathogenesis such as proliferation, survival, angiogenesis, and immunosuppression as well as maintenance, drug resistance, and recurrence. In this review, we focus on the role of signal transducer and activator of transcription 3 in medulloblastoma tumorigenesis and discuss the recent advances of signal transducer and activator of transcription 3 inhibition as a promising developed strategy for medulloblastoma therapy.
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Mirzapoiazova T, Xiao G, Mambetsariev B, Nasser MW, Miaou E, Singhal SS, Srivastava S, Mambetsariev I, Nelson MS, Nam A, Behal A, Arvanitis L, Atri P, Muschen M, Tissot FLH, Miser J, Kovach JS, Sattler M, Batra SK, Kulkarni P, Salgia R. Protein Phosphatase 2A as a Therapeutic Target in Small Cell Lung Cancer. Mol Cancer Ther 2021; 20:1820-1835. [PMID: 34253596 PMCID: PMC8722383 DOI: 10.1158/1535-7163.mct-21-0013] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 04/22/2021] [Accepted: 07/07/2021] [Indexed: 01/09/2023]
Abstract
Protein phosphatase 2A (PP2A), a serine/threonine phosphatase involved in the regulation of apoptosis, proliferation, and DNA-damage response, is overexpressed in many cancers, including small cell lung cancer (SCLC). Here we report that LB100, a small molecule inhibitor of PP2A, when combined with platinum-based chemotherapy, synergistically elicited an antitumor response both in vitro and in vivo with no apparent toxicity. Using inductively coupled plasma mass spectrometry, we determined quantitatively that sensitization via LB100 was mediated by increased uptake of carboplatin in SCLC cells. Treatment with LB100 alone or in combination resulted in inhibition of cell viability in two-dimensional culture and three-dimensional spheroid models of SCLC, reduced glucose uptake, and attenuated mitochondrial and glycolytic ATP production. Combining LB100 with atezolizumab increased the capacity of T cells to infiltrate and kill tumor spheroids, and combining LB100 with carboplatin caused hyperphosphorylation of the DNA repair marker γH2AX and enhanced apoptosis while attenuating MET signaling and invasion through an endothelial cell monolayer. Taken together, these data highlight the translational potential of inhibiting PP2A with LB100 in combination with platinum-based chemotherapy and immunotherapy in SCLC.
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Affiliation(s)
- Tamara Mirzapoiazova
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Gang Xiao
- Department of Systems Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, California
- Institute of Immunology, Institute of Hematology, Zhejiang University School of Medicine, Zhejiang, China
| | - Bolot Mambetsariev
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Mohd W Nasser
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Emily Miaou
- The Isotoparium, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California
| | - Sharad S Singhal
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Saumya Srivastava
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Isa Mambetsariev
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Michael S Nelson
- The Light Microscopy and Digital Imaging Core, Beckman Research Institute, City of Hope, Duarte, California
| | - Arin Nam
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Amita Behal
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Leonidas Arvanitis
- Department of Pathology, City of Hope National Cancer Center, Duarte, California
| | - Pranita Atri
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Markus Muschen
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - François L H Tissot
- The Isotoparium, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California
| | - James Miser
- Department of Pediatrics, City of Hope National Medical Center, Duarte, California
| | - John S Kovach
- Lixte Biotechnology Holdings, Inc., East Setauket, New York
| | - Martin Sattler
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Surinder K Batra
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Ravi Salgia
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California.
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7
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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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8
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Otani Y, Sur H, Rachaiah G, Namagiri S, Chowdhury A, Lewis CT, Shimizu T, Gangaplara A, Wang X, Vézina A, Maric D, Jackson S, Yan Y, Zhengping Z, Ray-Chaudhury A, Kumar S, Ballester LY, Chittiboina P, Yoo JY, Heiss J, Kaur B, Kumar Banasavadi-Siddegowda Y. Inhibiting protein phosphatase 2A increases the antitumor effect of protein arginine methyltransferase 5 inhibition in models of glioblastoma. Neuro Oncol 2021; 23:1481-1493. [PMID: 33556161 DOI: 10.1093/neuonc/noab014] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Despite multi-model therapy of maximal surgical resection, radiation, chemotherapy, and tumor treating fields, the median survival of Glioblastoma (GBM) patients is less than 15 months. Protein Arginine Methyltransferase 5 (PRMT5) catalyzes the symmetric di-methylation of arginine residues and is overexpressed in GBM. Inhibition of PRMT5 causes senescence in stem-like GBM tumor cells. LB100, a first-in-class small molecular inhibitor of Protein Phosphatase 2A (PP2A) can sensitize therapy-resistant tumor cells. Here, we tested the anti-GBM effect of concurrent PRMT5 and PP2A inhibition. METHODS Patient-derived primary GBM neurospheres (GBMNS), transfected with PRMT5 target-specific siRNA were treated with LB100 and subjected to in vitro assays including PP2A activity and western blot. The intracranial mouse xenograft model was used to test the in vivo antitumor efficacy of combination treatment. RESULTS We found that PRMT5-depletion increased PP2A activity in GBMNS. LB100 treatment significantly reduced the viability of PRMT5-depleted GBMNS compared to PRMT5 intact GBMNS. LB100 enhanced G1 cell cycle arrest induced by PRMT5-depletion. Combination therapy also increased the expression of phospho-MLKL. Necrostatin-1 rescued PRMT5-depleted cells from the cytotoxic effects of LB100, indicating that necroptosis caused the enhanced cytotoxicity of combination therapy. In the in vivo mouse tumor xenograft model, LB100 treatment combined with transient depletion of PRMT5 significantly decreased tumor size and prolonged survival, while LB100 treatment alone had no survival benefit. CONCLUSION Overall, combined PRMT5 and PP2A inhibition had significantly greater antitumor effects than PRMT5 inhibition alone.
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Affiliation(s)
- Yoshihiro Otani
- Department of Neurosurgery, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Hannah Sur
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | | | - Sriya Namagiri
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Ashis Chowdhury
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Cole T Lewis
- Department of Neurosurgery, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Toshihiko Shimizu
- Department of Neurosurgery, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Arunakumar Gangaplara
- Cellular and Molecular Therapeutics Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Xiang Wang
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Amélie Vézina
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, NINDS, NIH, Bethesda, MD, USA
| | - Sadhana Jackson
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Yuanqing Yan
- Department of Neurosurgery, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Zhuang Zhengping
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.,Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Abhik Ray-Chaudhury
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Sachin Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - Leomar Y Ballester
- Department of Pathology and Laboratory Medicine and Department of Neurosurgery, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Prashant Chittiboina
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Ji Young Yoo
- Department of Neurosurgery, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - John Heiss
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Balveen Kaur
- Department of Neurosurgery, University of Texas Health Science Center at Houston, Houston, TX, USA
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9
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Lei X, Ma N, Du L, Liang Y, Zhang P, Han Y, Qu B. PP2A and tumor radiotherapy. Hereditas 2020; 157:36. [PMID: 32847617 PMCID: PMC7450598 DOI: 10.1186/s41065-020-00149-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/13/2020] [Indexed: 02/07/2023] Open
Abstract
Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase that serves as a key regulator of cellular physiology in the context of apoptosis, mitosis, and DNA damage responses. Canonically, PP2A functions as a tumor suppressor gene. However, recent evidence suggests that inhibiting PP2A activity in tumor cells may represent a viable approach to enhancing tumor sensitivity to chemoradiotherapy as such inhibition can cause cells to enter a disordered mitotic state that renders them more susceptible to cell death. Indeed, there is evidence that inhibiting PP2A can slow tumor growth following radiotherapy in a range of cancer types including ovarian cancer, liver cancer, malignant glioma, pancreatic cancer, and nasopharyngeal carcinoma. In the present review, we discuss current understanding of the role of PP2A in tumor radiotherapy and the potential mechanisms whereby it may influence this process.
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Affiliation(s)
- Xiao Lei
- The First Medical Center of Chinese PLA General Hospital, Department of Radiation Oncology, Beijing, P. R. China
| | - Na Ma
- The First Medical Center of Chinese PLA General Hospital, Department of Radiation Oncology, Beijing, P. R. China
| | - Lehui Du
- The First Medical Center of Chinese PLA General Hospital, Department of Radiation Oncology, Beijing, P. R. China
| | - Yanjie Liang
- The First Medical Center of Chinese PLA General Hospital, Department of Radiation Oncology, Beijing, P. R. China
| | - Pei Zhang
- The First Medical Center of Chinese PLA General Hospital, Department of Radiation Oncology, Beijing, P. R. China
| | - Yanan Han
- The First Medical Center of Chinese PLA General Hospital, Department of Radiation Oncology, Beijing, P. R. China
| | - Baolin Qu
- The First Medical Center of Chinese PLA General Hospital, Department of Radiation Oncology, Beijing, P. R. China.
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10
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Maggio D, Ho WS, Breese R, Walbridge S, Wang H, Cui J, Heiss JD, Gilbert MR, Kovach JS, Lu RO, Zhuang Z. Inhibition of protein phosphatase-2A with LB-100 enhances antitumor immunity against glioblastoma. J Neurooncol 2020; 148:231-244. [PMID: 32342332 DOI: 10.1007/s11060-020-03517-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 04/23/2020] [Indexed: 12/13/2022]
Abstract
PURPOSE Glioblastoma (GBM) carries a dismal prognosis despite standard multimodal treatment with surgery, chemotherapy and radiation. Immune checkpoint inhibitors, such as PD1 blockade, for treatment of GBM failed to show clinical benefit. Rational combination strategies to overcome resistance of GBM to checkpoint monotherapy are needed to extend the promise of immunotherapy to GBM management. Emerging evidence suggests that protein phosphatase 2A (PP2A) plays a critical role in the signal transduction pathways of both adaptive and innate immune cells and that inhibition of PP2A could enhance cancer immunity. We investigated the use of a PP2A inhibitor, LB-100, to enhance antitumor efficacy of PD1 blockade in a syngeneic glioma model. METHODS C57BL/6 mice were implanted with murine glioma cell line GL261-luc or GL261-WT and randomized into 4 treatment arms: (i) control, (ii) LB-100, (iii) PD1 blockade and (iv) combination. Survival was assessed and detailed profiling of tumor infiltrating leukocytes was performed. RESULTS Dual PP2A and PD1 blockade significantly improved survival compared with monotherapy alone. Combination therapy resulted in complete regression of tumors in about 25% of mice. This effect was dependent on CD4 and CD8 T cells and cured mice established antigen-specific secondary protective immunity. Analysis of tumor lymphocytes demonstrated enhanced CD8 infiltration and effector function. CONCLUSION This is the first preclinical investigation of the effect of combining PP2A inhibition with PD1 blockade for GBM. This novel combination provided effective tumor immunotherapy and long-term survival in our animal GBM model.
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Affiliation(s)
- Dominic Maggio
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Winson S Ho
- Department of Neurosurgery, Dell Medical School, University of Texas at Austin, Austin, TX, 78701, USA.
- University of Texas at Austin, 1601 Trinity St, Bldg. B HDB 3.214, Austin, TX, 78701, USA.
| | - Rebecca Breese
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Stuart Walbridge
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Herui Wang
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jing Cui
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - John D Heiss
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Mark R Gilbert
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - John S Kovach
- Lixte Biotechnology Holdings, Inc., East Setauket, NY, 11733, USA
| | - Rongze O Lu
- Department of Neurosurgery, Dell Medical School, University of Texas at Austin, Austin, TX, 78701, USA.
- University of Texas at Austin, 1601 Trinity St, Bldg. B HDB 3.216, Austin, TX, 78701, USA.
| | - Zhengping Zhuang
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
- National Institutes of Health, BLDG 35, Rm 2B203, Bethesda, MD, 20892, USA.
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11
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Kauko O, Imanishi SY, Kulesskiy E, Yetukuri L, Laajala TD, Sharma M, Pavic K, Aakula A, Rupp C, Jumppanen M, Haapaniemi P, Ruan L, Yadav B, Suni V, Varila T, Corthals GL, Reimand J, Wennerberg K, Aittokallio T, Westermarck J. Phosphoproteome and drug-response effects mediated by the three protein phosphatase 2A inhibitor proteins CIP2A, SET, and PME-1. J Biol Chem 2020; 295:4194-4211. [PMID: 32071079 PMCID: PMC7105317 DOI: 10.1074/jbc.ra119.011265] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 02/03/2020] [Indexed: 12/15/2022] Open
Abstract
Protein phosphatase 2A (PP2A) critically regulates cell signaling and is a human tumor suppressor. PP2A complexes are modulated by proteins such as cancerous inhibitor of protein phosphatase 2A (CIP2A), protein phosphatase methylesterase 1 (PME-1), and SET nuclear proto-oncogene (SET) that often are deregulated in cancers. However, how they impact cellular phosphorylation and how redundant they are in cellular regulation is poorly understood. Here, we conducted a systematic phosphoproteomics screen for phosphotargets modulated by siRNA-mediated depletion of CIP2A, PME-1, and SET (to reactivate PP2A) or the scaffolding A-subunit of PP2A (PPP2R1A) (to inhibit PP2A) in HeLa cells. We identified PP2A-modulated targets in diverse cellular pathways, including kinase signaling, cytoskeleton, RNA splicing, DNA repair, and nuclear lamina. The results indicate nonredundancy among CIP2A, PME-1, and SET in phosphotarget regulation. Notably, PP2A inhibition or reactivation affected largely distinct phosphopeptides, introducing a concept of nonoverlapping phosphatase inhibition- and activation-responsive sites (PIRS and PARS, respectively). This phenomenon is explained by the PPP2R1A inhibition impacting primarily dephosphorylated threonines, whereas PP2A reactivation results in dephosphorylation of clustered and acidophilic sites. Using comprehensive drug-sensitivity screening in PP2A-modulated cells to evaluate the functional impact of PP2A across diverse cellular pathways targeted by these drugs, we found that consistent with global phosphoproteome effects, PP2A modulations broadly affect responses to more than 200 drugs inhibiting a broad spectrum of cancer-relevant targets. These findings advance our understanding of the phosphoproteins, pharmacological responses, and cellular processes regulated by PP2A modulation and may enable the development of combination therapies.
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Affiliation(s)
- Otto Kauko
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland; Institute of Biomedicine, University of Turku, 20500 Turku, Finland; TuBS and TuDMM Doctoral Programmes, University of Turku, 20500 Turku, Finland
| | - Susumu Y Imanishi
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Evgeny Kulesskiy
- Institute for Molecular Medicine Finland FIMM, University of Helsinki, Tukholmankatu 8, Helsinki, Finland
| | - Laxman Yetukuri
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Teemu Daniel Laajala
- Institute for Molecular Medicine Finland FIMM, University of Helsinki, Tukholmankatu 8, Helsinki, Finland; Department of Mathematics and Statistics, University of Turku, 20500 Turku, Finland
| | - Mukund Sharma
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland; Institute of Biomedicine, University of Turku, 20500 Turku, Finland; TuBS and TuDMM Doctoral Programmes, University of Turku, 20500 Turku, Finland
| | - Karolina Pavic
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Anna Aakula
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Christian Rupp
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Mikael Jumppanen
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Pekka Haapaniemi
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Luyao Ruan
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Bhagwan Yadav
- Institute for Molecular Medicine Finland FIMM, University of Helsinki, Tukholmankatu 8, Helsinki, Finland
| | - Veronika Suni
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Taru Varila
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Garry L Corthals
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland
| | - Jüri Reimand
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Krister Wennerberg
- Institute for Molecular Medicine Finland FIMM, University of Helsinki, Tukholmankatu 8, Helsinki, Finland
| | - Tero Aittokallio
- Institute for Molecular Medicine Finland FIMM, University of Helsinki, Tukholmankatu 8, Helsinki, Finland; Department of Mathematics and Statistics, University of Turku, 20500 Turku, Finland
| | - Jukka Westermarck
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20500 Turku, Finland; Institute of Biomedicine, University of Turku, 20500 Turku, Finland.
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12
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CITK Loss Inhibits Growth of Group 3 and Group 4 Medulloblastoma Cells and Sensitizes Them to DNA-Damaging Agents. Cancers (Basel) 2020; 12:cancers12030542. [PMID: 32111106 PMCID: PMC7139701 DOI: 10.3390/cancers12030542] [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: 02/10/2020] [Revised: 02/15/2020] [Accepted: 02/23/2020] [Indexed: 02/06/2023] Open
Abstract
Medulloblastoma (MB) is the most common malignant brain tumor in children, and it is classified into four biological subgroups: WNT, Sonic Hedgehog (SHH), Group 3 and Group 4. The current treatment is surgery, followed by irradiation and chemotherapy. Unfortunately, these therapies are only partially effective. Citron kinase protein (CITK) has been proposed as a promising target for SHH MB, whose inactivation leads to DNA damage and apoptosis. D283 and D341 cell lines (Group 3/Group 4 MB) were silenced with established siRNA sequences against CITK, to assess the direct effects of its loss. Next, D283, D341, ONS-76 and DAOY cells were treated with ionizing radiation (IR) or cisplatin in combination with CITK knockdown. CITK depletion impaired proliferation and induced cytokinesis failure and apoptosis of G3/G4 MB cell lines. Furthermore, CITK knockdown produced an accumulation of DNA damage, with reduced RAD51 nuclear levels. Association of IR or cisplatin with CITK depletion strongly impaired the growth potential of all tested MB cells. These results indicate that CITK inactivation could prevent the expansion of G3/G4 MB and increase their sensitivity to DNA-damaging agents, by impairing homologous recombination. We suggest that CITK inhibition could be broadly associated with IR and adjuvant therapy in MB treatment.
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13
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Elgenaidi IS, Spiers JP. Regulation of the phosphoprotein phosphatase 2A system and its modulation during oxidative stress: A potential therapeutic target? Pharmacol Ther 2019; 198:68-89. [PMID: 30797822 DOI: 10.1016/j.pharmthera.2019.02.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 02/15/2019] [Indexed: 02/06/2023]
Abstract
Phosphoprotein phosphatases are of growing interest in the pathophysiology of many diseases and are often the neglected partner of protein kinases. One family member, PP2A, accounts for dephosphorylation of ~55-70% of all serine/threonine phosphosites. Interestingly, dysregulation of kinase signalling is a hallmark of many diseases in which an increase in oxidative stress is also noted. With this in mind, we assess the evidence to support oxidative stress-mediated regulation of the PP2A system In this article, we first present an overview of the PP2A system before providing an analysis of the regulation of PP2A by endogenous inhibitors, post translational modification, and miRNA. Next, a detailed critique of data implicating reactive oxygen species, ischaemia, ischaemia-reperfusion, and hypoxia in regulating the PP2A holoenzyme and associated regulators is presented. Finally, the pharmacological targeting of PP2A, its endogenous inhibitors, and enzymes responsible for its post-translational modification are covered. There is extensive evidence that oxidative stress modulates multiple components of the PP2A system, however, most of the data pertains to the catalytic subunit of PP2A. Irrespective of the underlying aetiology, free radical-mediated attenuation of PP2A activity is an emerging theme. However, in many instances, a dichotomy exists, which requires clarification and mechanistic insight. Nevertheless, this raises the possibility that pharmacological activation of PP2A, either through small molecule activators of PP2A or CIP2A/SET antagonists may be beneficial in modulating the cellular response to oxidative stress. A better understanding of which, will have wide ranging implications for cancer, heart disease and inflammatory conditions.
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Affiliation(s)
- I S Elgenaidi
- Department of Pharmacology and Therapeutics, Trinity College Dublin, Ireland
| | - J P Spiers
- Department of Pharmacology and Therapeutics, Trinity College Dublin, Ireland.
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14
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D'Arcy BM, Swingle MR, Papke CM, Abney KA, Bouska ES, Prakash A, Honkanen RE. The Antitumor Drug LB-100 Is a Catalytic Inhibitor of Protein Phosphatase 2A (PPP2CA) and 5 (PPP5C) Coordinating with the Active-Site Catalytic Metals in PPP5C. Mol Cancer Ther 2019; 18:556-566. [PMID: 30679389 DOI: 10.1158/1535-7163.mct-17-1143] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 03/20/2018] [Accepted: 01/11/2019] [Indexed: 12/28/2022]
Abstract
LB-100 is an experimental cancer therapeutic with cytotoxic activity against cancer cells in culture and antitumor activity in animals. The first phase I trial (NCT01837667) evaluating LB-100 recently concluded that safety and efficacy parameters are favorable for further clinical testing. Although LB-100 is widely reported as a specific inhibitor of serine/threonine phosphatase 2A (PP2AC/PPP2CA:PPP2CB), we could find no experimental evidence in the published literature demonstrating the specific engagement of LB-100 with PP2A in vitro, in cultured cells, or in animals. Rather, the premise for LB-100 targeting PP2AC is derived from studies that measure phosphate released from a phosphopeptide (K-R-pT-I-R-R) or inferred from the ability of LB-100 to mimic activity previously reported to result from the inhibition of PP2AC by other means. PP2AC and PPP5C share a common catalytic mechanism. Here, we demonstrate that the phosphopeptide used to ascribe LB-100 specificity for PP2A is also a substrate for PPP5C. Inhibition assays using purified enzymes demonstrate that LB-100 is a catalytic inhibitor of both PP2AC and PPP5C. The structure of PPP5C cocrystallized with LB-100 was solved to a resolution of 1.65Å, revealing that the 7-oxabicyclo[2.2.1]heptane-2,3-dicarbonyl moiety coordinates with the metal ions and key residues that are conserved in both PP2AC and PPP5C. Cell-based studies revealed some known actions of LB-100 are mimicked by the genetic disruption of PPP5C These data demonstrate that LB-100 is a catalytic inhibitor of both PP2AC and PPP5C and suggest that the observed antitumor activity might be due to an additive effect achieved by suppressing both PP2A and PPP5C.
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Affiliation(s)
- Brandon M D'Arcy
- USA Mitchell Cancer Institute, Mobile, Alabama.,Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama
| | - Mark R Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama
| | - Cinta M Papke
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama
| | - Kevin A Abney
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama
| | - Erin S Bouska
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama
| | - Aishwarya Prakash
- USA Mitchell Cancer Institute, Mobile, Alabama. .,Department of Pharmacology, University of South Alabama, Mobile, Alabama
| | - Richard E Honkanen
- USA Mitchell Cancer Institute, Mobile, Alabama. .,Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama
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15
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Liu X, Chen Y, Li Y, Petersen RB, Huang K. Targeting mitosis exit: A brake for cancer cell proliferation. Biochim Biophys Acta Rev Cancer 2019; 1871:179-191. [PMID: 30611728 DOI: 10.1016/j.bbcan.2018.12.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/03/2018] [Accepted: 12/03/2018] [Indexed: 12/16/2022]
Abstract
The transition from mitosis to interphase, referred to as mitotic exit, is a critical mitotic process which involves activation and inactivation of multiple mitotic kinases and counteracting protein phosphatases. Loss of mitotic exit checkpoints is a common feature of cancer cells, leading to mitotic dysregulation and confers cancer cells with oncogenic characteristics, such as aberrant proliferation and microtubule-targeting agent (MTA) resistance. Since MTA resistance results from cancer cells prematurely exiting mitosis (mitotic slippage), blocking mitotic exit is believed to be a promising anticancer strategy. Moreover, based on this theory, simultaneous inhibition of mitotic exit and additional cell cycle phases would likely achieve synergistic antitumor effects. In this review, we divide the molecular regulators of mitotic exit into four categories based on their different regulatory functions: 1) the anaphase-promoting complex/cyclosome (APC/C, a ubiquitin ligase), 2) cyclin B, 3) mitotic kinases and phosphatases, 4) kinesins and microtubule-binding proteins. We also review the regulators of mitotic exit and propose prospective anticancer strategies targeting mitotic exit, including their strengths and possible challenges to their use.
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Affiliation(s)
- Xinran Liu
- Tongji School of Pharmacy, Huazhong University of Science & Technology, Wuhan, Hubei 430030, China
| | - Yuchen Chen
- Tongji School of Pharmacy, Huazhong University of Science & Technology, Wuhan, Hubei 430030, China
| | - Yangkai Li
- Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
| | - Robert B Petersen
- Foundational Sciences, Central Michigan University College of Medicine, Mt. Pleasant, MI 48858, USA
| | - Kun Huang
- Tongji School of Pharmacy, Huazhong University of Science & Technology, Wuhan, Hubei 430030, China.
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16
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Liu L, Wang H, Cui J, Zhang Q, Zhang W, Xu W, Lu H, Liu S, Shen S, Fang F, Li L, Yang W, Zhuang Z, Li J. Inhibition of Protein Phosphatase 2A Sensitizes Mucoepidermoid Carcinoma to Chemotherapy via the PI3K-AKT Pathway in Response to Insulin Stimulus. Cell Physiol Biochem 2018; 50:317-331. [PMID: 30282066 DOI: 10.1159/000494008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 09/25/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND/AIMS Protein phosphatase 2A (PP2A) is a ubiquitous serine/threonine phosphatase that mediates cell cycle regulation and metabolism. Mounting evidence has indicated that PP2A inhibition exhibits considerable anticancer potency in multiple types of human cancers. However, the efficacy of PP2A inhibition remains unexplored in mucoepidermoid carcinoma (MEC), especially in locally advanced and metastatic cases with limited systemic treatment. In this study, we demonstrated the therapeutic potency of LB100 in mucoepidermoid carcinoma. METHODS In this study, the expression of PP2A was evaluated using immunohistochemical (IHC) staining. The effects associated with LB100 alone and in combination with cisplatin for the treatment of mucoepidermoid carcinoma were investigated both in vitro, regarding metabolism, proliferation, and migration, and in vivo in a mucoepidermoid carcinoma xenograft model. In addition, with LB100 treatment and in response to an insulin stimulus, the expression levels and phosphorylation levels of targets in the PI3K-AKT pathway were determined using western blot analysis and immunoblotting. RESULTS The expression of protein phosphatase 2A was significantly upregulated in the clinical specimens of high-grade MECs compared with those of low-/medium-grade MECs and normal controls. In this article, we report that a small molecule PP2A inhibitor, LB100, decreased cellular viability and glycolytic activity and induced G2/M cell cycle arrest. Importantly, LB100 enhanced the efficacy of cisplatin in mucoepidermoid carcinoma cells both in vitro and in vivo. PP2A inhibition by LB100 increased the phosphorylation of insulin receptor substrate 1(IRS-1) on serine residues, downregulated the expression of phosphatidylinositol 3-kinase (PI3K) p110 alpha subunit and dephosphorylated AKT at Ser473 and Thr308 in mucoepidermoid carcinoma cells in response to insulin stimulus. CONCLUSION These results highlight the translational potential of PP2A inhibition to synergize with cisplatin in mucoepidermoid carcinoma treatment.
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Affiliation(s)
- Limin Liu
- Department of Oral Pathology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, National Clinical Research Center for Oral Diseases, Shanghai, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China.,Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Herui Wang
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jing Cui
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Qi Zhang
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Wei Zhang
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Wanlin Xu
- Department of Oral Pathology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, National Clinical Research Center for Oral Diseases, Shanghai, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
| | - Hao Lu
- Department of Oral Pathology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, National Clinical Research Center for Oral Diseases, Shanghai, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
| | - Shengwen Liu
- Department of Oral Pathology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, National Clinical Research Center for Oral Diseases, Shanghai, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
| | - Shukun Shen
- Department of Oral Pathology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, National Clinical Research Center for Oral Diseases, Shanghai, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
| | | | - Lei Li
- Department of Oral Pathology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, National Clinical Research Center for Oral Diseases, Shanghai, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
| | - Wenjun Yang
- Department of Oral Pathology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, National Clinical Research Center for Oral Diseases, Shanghai, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
| | - Zhengping Zhuang
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jiang Li
- Department of Oral Pathology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, National Clinical Research Center for Oral Diseases, Shanghai, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
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17
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Mazhar S, Taylor SE, Sangodkar J, Narla G. Targeting PP2A in cancer: Combination therapies. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:51-63. [PMID: 30401535 DOI: 10.1016/j.bbamcr.2018.08.020] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/21/2018] [Accepted: 08/28/2018] [Indexed: 12/12/2022]
Abstract
The serine/threonine phosphatase PP2A regulates a vast portion of the phosphoproteome including pathways involved in apoptosis, proliferation and DNA damage response and PP2A inactivation is a vital step in malignant transformation. Many groups have explored the therapeutic venue of combining PP2A reactivation with kinase inhibition to counteract the very changes in tumor suppressors and oncogenes that lead to cancer development. Conversely, inhibition of PP2A to complement chemotherapy and radiation-induced cancer cell death is also an area of active investigation. Here we review the studies that utilize PP2A targeted agents as combination therapy in cancer. A potential role for PP2A in tumor immunity is also highlighted.
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Affiliation(s)
- Sahar Mazhar
- Department of Pathology, Case Western Reserve University, Cleveland, OH, USA
| | - Sarah E Taylor
- Department of Pathology, Case Western Reserve University, Cleveland, OH, USA
| | - Jaya Sangodkar
- Division of Genetic Medicine, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Goutham Narla
- Division of Genetic Medicine, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.
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18
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Zhang H, Li H, Liu Z, Ge A, Guo E, Liu S, Chen Z. Triptolide inhibits the proliferation and migration of medulloblastoma Daoy cells by upregulation of microRNA-138. J Cell Biochem 2018; 119:9866-9877. [PMID: 30156009 DOI: 10.1002/jcb.27307] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 06/26/2018] [Indexed: 12/25/2022]
Abstract
Medulloblastoma is a primitive neuroectodermal-derived brain tumor and the most common malignant brain tumor in children. Triptolide (TPL) is the major active component extracted from Tripterygium wilfordii Hook F. This study aimed to explore the effects of TPL on medulloblastoma cell proliferation, migration, and apoptosis, as well as the underlying possible molecular mechanism. Viability, proliferation, and apoptosis of Daoy cells were measured using cell counting kit-8 assay, 5-bromo-2'-deoxyuridine incorporation assay, and Guava Nexin assay, respectively. Cell migration was detected using two-chamber transwell assay and wound healing assay. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to determine the relative expression of microRNA-138 (miR-138) in Daoy cells. Cell transfection was used to change the expression of miR-138 in cells. Western blot analysis was used to analyze the expression of key factors involved in cell apoptosis, cell migration, the phosphatidylinositol 3-kinase (PI3K)/protein kinase 3 (AKT) pathway, and the Notch pathway in Daoy cells. We found that TPL significantly inhibited the viability, proliferation, and migration of Daoy cells but promoted Daoy cell apoptosis. The expression levels of matrix metalloproteinases (MMP)-2 and MMP-9 after TPL treatment were decreased. The expression of miR-138 in Daoy cells after TPL treatment was increased. Suppression of miR-138 obviously reversed the TPL-induced Daoy cell proliferation, migration inhibition, and cell apoptosis enhancement, as well as the inactivation of the PI3K/AKT and Notch pathways. Cyclin-dependent kinase 6 (CDK6) was a direct target gene of miR-138, which might be involved in the antitumor effects of TPL on Daoy cells. In conclusion, our study verified that TPL exerted anticancer effects on medulloblastoma cells possibly via upregulating miR-138 and inactivating the PI3K/AKT and Notch pathways.
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Affiliation(s)
- Haifang Zhang
- Department of Pediatrics, Jining No. 1 People's Hospital, Jining, Shandong, China
| | - Hui Li
- Department of Pediatrics, Jining No. 1 People's Hospital, Jining, Shandong, China
| | - Zhenguo Liu
- Department of Pediatrics, Jining No. 1 People's Hospital, Jining, Shandong, China
| | - Ang Ge
- Department of Pediatrics, Jining No. 1 People's Hospital, Jining, Shandong, China
| | - Enyu Guo
- Department of Pediatrics, Jining No. 1 People's Hospital, Jining, Shandong, China
| | - Shuxia Liu
- Department of Pediatrics, Jining No. 1 People's Hospital, Jining, Shandong, China
| | - Zhiping Chen
- Department of Pediatrics, Jining No. 1 People's Hospital, Jining, Shandong, China
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19
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Lin ZP, Zhu YL, Ratner ES. Targeting Cyclin-Dependent Kinases for Treatment of Gynecologic Cancers. Front Oncol 2018; 8:303. [PMID: 30135856 PMCID: PMC6092490 DOI: 10.3389/fonc.2018.00303] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/19/2018] [Indexed: 02/01/2023] Open
Abstract
Ovarian, uterine/endometrial, and cervical cancers are major gynecologic malignancies estimated to cause nearly 30,000 deaths in 2018 in US. Defective cell cycle regulation is the hallmark of cancers underpinning the development and progression of the disease. Normal cell cycle is driven by the coordinated and sequential rise and fall of cyclin-dependent kinases (CDK) activity. The transition of cell cycle phases is governed by the respective checkpoints that prevent the entry into the next phase until cellular or genetic defects are repaired. Checkpoint activation is achieved by p53- and ATM/ATR-mediated inactivation of CDKs in response to DNA damage. Therefore, an aberrant increase in CDK activity and/or defects in checkpoint activation lead to unrestricted cell cycle phase transition and uncontrolled proliferation that give rise to cancers and perpetuate malignant progression. Given that CDK activity is also required for homologous recombination (HR) repair, pharmacological inhibition of CDKs can be exploited as a synthetic lethal approach to augment the therapeutic efficacy of PARP inhibitors and other DNA damaging modalities for the treatment of gynecologic cancers. Here, we overview the basic of cell cycle and discuss the mechanistic studies that establish the intimate link between CDKs and HR repair. In addition, we present the perspective of preclinical and clinical development in small molecule inhibitors of CDKs and CDK-associated protein targets, as well as their potential use in combination with hormonal therapy, PARP inhibitors, chemotherapy, and radiation to improve treatment outcomes.
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Affiliation(s)
- Z Ping Lin
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, United States
| | - Yong-Lian Zhu
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, United States
| | - Elena S Ratner
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, United States
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Pharmacologic inhibition of protein phosphatase-2A achieves durable immune-mediated antitumor activity when combined with PD-1 blockade. Nat Commun 2018; 9:2126. [PMID: 29844427 PMCID: PMC5974350 DOI: 10.1038/s41467-018-04425-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 04/26/2018] [Indexed: 12/16/2022] Open
Abstract
Mounting evidence suggests that inhibition of protein phosphatase-2A (PP2A), a serine/threonine phosphatase, could enhance anticancer immunity. However, drugs targeting PP2A are not currently available. Here, we report that a PP2A inhibitor, LB-100, when combined with anti-PD-1 (aPD-1) blockade can synergistically elicit a durable immune-mediated antitumor response in a murine CT26 colon cancer model. This effect is T-cell dependent, leading to regression of a significant proportion of tumors. Analysis of tumor lymphocytes demonstrates enhanced effector T-cell and reduced suppressive regulatory T-cell infiltration. Clearance of tumor establishes antigen-specific secondary protective immunity. A synergistic effect of LB-100 and aPD-1 blockade is also observed in B16 melanoma model. In addition, LB-100 activates the mTORC1 signaling pathway resulting in decreased differentiation of naive CD4 cells into regulatory T cells. There is also increased expression of Th1 and decreased expression of Th2 cytokines. These data highlight the translational potential of PP2A inhibition in combination with checkpoint inhibition.
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Hanawa S, Mitsuhashi A, Shozu M. Antitumor effects of metformin via indirect inhibition of protein phosphatase 2A in patients with endometrial cancer. PLoS One 2018; 13:e0192759. [PMID: 29444159 PMCID: PMC5812621 DOI: 10.1371/journal.pone.0192759] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 11/20/2017] [Indexed: 01/22/2023] Open
Abstract
Objective Metformin, an antidiabetic drug, inhibits the endometrial cancer cell growth in vivo by improving the insulin resistance; however, its mechanism of action is not completely understood. Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase associated with insulin resistance and type 2 diabetes, and its inhibition restores the insulin resistance. This study investigated the antitumor effect of metformin on endometrial cancer with a focus on PP2A. Methods Metformin (1,500–2,250 mg/day) was preoperatively administered to patients with endometrial cancer for 4 to 6 weeks. Expression of the PP2A regulatory subunits, 4 (PPP2R4) and B (PP2A-B), was evaluated using real-time polymerase chain reaction (RT–PCR) and immunohistochemistry (IHC) using paired specimens obtained before and after metformin treatment. The effect of PPP2R4 inhibition with small interfering RNA was evaluated in the endometrial cancer cell lines HEC265 and HEC1B. P values of < .05 were considered statistically significant. Results Preoperative metformin treatment significantly reduced the expression of PP2A-B, as determined using IHC, and the mRNA expression of PPP2R4, as determined using RT–PCR, in the patients with endometrial cancer. However, metformin could not directly alter the PPP2R4 mRNA levels in the endometrial cancer cell lines in vitro. PPP2R4 knockdown reduced the proliferation and induced the apoptosis by activating caspases 3/7 in HEC265 and HEC1B cells. Conclusions Downregulation of the PP2A-B subunit, including PPP2R4, is an important indirect target of metformin. Inhibition of PP2A may be an option for the treatment of endometrial cancer patients with insulin resistance. Trial registration This trial is registered with UMIN-CTR (number UMIN000004852).
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Affiliation(s)
- Shinsuke Hanawa
- Department of Reproductive Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Akira Mitsuhashi
- Department of Reproductive Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
- * E-mail:
| | - Makio Shozu
- Department of Reproductive Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
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LB-100, a novel Protein Phosphatase 2A (PP2A) inhibitor, sensitizes malignant meningioma cells to the therapeutic effects of radiation. Cancer Lett 2017; 415:217-226. [PMID: 29199006 DOI: 10.1016/j.canlet.2017.11.035] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/24/2017] [Accepted: 11/27/2017] [Indexed: 02/07/2023]
Abstract
Atypical and anaplastic meningiomas (AAM) represent 20% of all meningiomas. They are associated with poor outcomes due to their tendency to recur. While surgery and radiation (RT) are first line therapy, no effective systemic medical treatment has been identified. Protein phosphatase 2A (PP2A) is a ubiquitously expressed serine/threonine phosphatase involved in cell cycle regulation and DNA repair. Here, we examined radiosensitizing effects of LB-100, a novel inhibitor of PP2A against AAM as a novel treatment strategy. Three human-derived immortalized meningioma cell lines, IOMM-LEE, GAR, and CH-157, were used to investigate the radio-sensitizing potential of LB-100 in AAM. Survival fraction by clonogenic assay, immunofluorescence, cell cycle analysis and protein expression were evaluated in vitro. The antitumor effects of combining LB-100 with RT were verified in vivo by using intracranial orthotopic xenograft mouse model. Pharmacologic PP2A inhibition with LB-100 prior to RT enhanced the radiosensitivity of meningioma cells and reduced survival fraction in clonogenic assays. LB-100 increased DNA double-strand breakage (measured by γ-H2AX), mitotic catastrophe cell death, and G2/M cell cycle arrest in irradiated meningioma cells. Also, LB-100 decreased activation of STAT3 and expression of its downstream proteins. In vivo, LB-100 and RT combined treatment prolonged the survival of mice with xenografts compared to RT alone. Taken together, these results provide convincing preclinical data to support the use of LB-100 as a radiosensitizing agent for treatment of malignant meningioma. Its potential for clinical application deserves further investigation.
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Therapeutic targeting of PP2A. Int J Biochem Cell Biol 2017; 96:182-193. [PMID: 29107183 DOI: 10.1016/j.biocel.2017.10.008] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 10/13/2017] [Accepted: 10/16/2017] [Indexed: 12/19/2022]
Abstract
Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase that regulates many cellular processes. Given the central role of PP2A in regulating diverse biological functions and its dysregulation in many diseases, including cancer, PP2A directed therapeutics have become of great interest. The main approaches leveraged thus far can be categorized as follows: 1) inhibiting endogenous inhibitors of PP2A, 2) targeted disruption of post translational modifications on PP2A subunits, or 3) direct targeting of PP2A. Additional insight into the structural, molecular, and biological framework driving the efficacy of these therapeutic strategies will provide a foundation for the refinement and development of novel and clinically tractable PP2A targeted therapies.
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Chung V, Mansfield AS, Braiteh F, Richards D, Durivage H, Ungerleider RS, Johnson F, Kovach JS. Safety, Tolerability, and Preliminary Activity of LB-100, an Inhibitor of Protein Phosphatase 2A, in Patients with Relapsed Solid Tumors: An Open-Label, Dose Escalation, First-in-Human, Phase I Trial. Clin Cancer Res 2016; 23:3277-3284. [PMID: 28039265 DOI: 10.1158/1078-0432.ccr-16-2299] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Revised: 11/30/2016] [Accepted: 12/05/2016] [Indexed: 11/16/2022]
Abstract
Purpose: To determine the MTD and to assess the safety, tolerability, and potential activity of LB-100, a first-in-class small-molecule inhibitor of protein phosphatase 2A (PP2A) in adult patients with progressive solid tumors.Experimental Design: LB-100 was administered intravenously daily for 3 days in 21-day cycles in a 3 + 3 dose escalation design.Results: There were 29 patient entries over 7 dose escalations. One patient stopped treatment after one dose because of an acute infection and was reenrolled after recovery; each course was analyzed as a separate patient entry. Two patients had dose-limiting toxicity (reversible increases in serum creatinine or calculated serum creatinine clearance) at the 3.1 mg/m2 level. Probable or possible study drug-related grade 3 adverse events occurred in 6 (20.7%) patients [anemia (n = 2), decreased creatinine clearance, dyspnea, hyponatremia, and lymphopenia]. Ten (50%) of 20 response-evaluable patients had stable disease for four or more cycles. One patient with pancreatic adenocarcinoma had a partial response noted after 10 cycles, which was maintained for five additional cycles. The other patients achieving stable disease had one of the following: fibrosarcoma, chondrosarcoma, thymoma, atypical carcinoid of lung, or ovarian, testicular, breast (n = 2), and prostate cancer. The recommended phase II dose of LB-100 is 2.33 mg/m2 daily for 3 days every 3 weeks.Conclusions: The safety, tolerability, preliminary evidence of antitumor activity, and novel mechanism of action of LB-100 support its continued development alone and in combination with other therapies. Clin Cancer Res; 23(13); 3277-84. ©2016 AACR.
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Affiliation(s)
| | | | - Fadi Braiteh
- Comprehensive Cancer Centers of Nevada, Las Vegas, Nevada.,US Oncology Research, The Woodlands, Texas
| | - Donald Richards
- US Oncology Research, The Woodlands, Texas.,Texas Oncology, Tyler, Texas
| | | | | | | | - John S Kovach
- Lixte Biotechnology Holdings, Inc., East Setauket, New York.
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Albumin nanoparticles for glutathione-responsive release of cisplatin: New opportunities for medulloblastoma. Int J Pharm 2016; 517:168-174. [PMID: 27956195 DOI: 10.1016/j.ijpharm.2016.12.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/06/2016] [Accepted: 12/08/2016] [Indexed: 11/21/2022]
Abstract
Redox-responsive nanoparticles were synthesized by desolvation of bovine serum albumin followed by disulfide-bond crosslinking with N, N'-Bis (acryloyl) cystamine. Dynamic light scattering and transmission electron microscopy studies revealed spherical nanoparticles (mean diameter: 83nm, polydispersity index: 0.3) that were glutathione-responsive. Confocal microscopy revealed rapid, efficient internalization of the nanoparticles by Daoy medulloblastoma cells and healthy controls (HaCaT keratinocytes). Cisplatin-loaded nanoparticles with drug:carrier ratios of 5%, 10%, and 20% were tested in both cell lines. The formulation with the highest drug:carrier ratio reduced Daoy and HaCaT cell viability with IC50 values of 6.19 and 11.17μgmL-1, respectively. The differential cytotoxicity reflects the cancer cells' higher glutathione content, which triggers more extensive disruption of the disulfide bond-mediated intra-particle cross-links, decreasing particle stability and increasing their cisplatin release. These findings support continuing efforts to improve the safety and efficacy of antineoplastic drug therapy for pediatric brain tumors using selective nanoparticle-based drug delivery systems.
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