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Li AX, Martin TA, Lane J, Jiang WG. Cellular Impacts of Striatins and the STRIPAK Complex and Their Roles in the Development and Metastasis in Clinical Cancers (Review). Cancers (Basel) 2023; 16:76. [PMID: 38201504 PMCID: PMC10777921 DOI: 10.3390/cancers16010076] [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: 11/23/2023] [Revised: 12/18/2023] [Accepted: 12/20/2023] [Indexed: 01/12/2024] Open
Abstract
Striatins (STRNs) are generally considered to be cytoplasmic proteins, with lower expression observed in the nucleus and at cell-cell contact regions. Together with protein phosphatase 2A (PP2A), STRNs form the core region of striatin-interacting phosphatase and kinase (STRIPAK) complexes through the coiled-coil region of STRN proteins, which is crucial for substrate recruitment. Over the past two decades, there has been an increasing amount of research into the biological and cellular functions of STRIPAK members. STRNs and the constituent members of the STRIPAK complex have been found to regulate several cellular functions, such as cell cycle control, cell growth, and motility. Dysregulation of these cellular events is associated with cancer development. Importantly, their roles in cancer cells and clinical cancers are becoming recognised, with several STRIPAK components found to have elevated expression in cancerous tissues compared to healthy tissues. These molecules exhibit significant diagnostic and prognostic value across different cancer types and in metastatic progression. The present review comprehensively summarises and discusses the current knowledge of STRNs and core STRIPAK members, in cancer malignancy, from both cellular and clinical perspectives.
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Affiliation(s)
| | - Tracey A. Martin
- Cardiff China Medical Research Collaborative, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK; (A.X.L.); (J.L.); (W.G.J.)
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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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Gao S, Shan L, Zhang M, Wang Y, Zhan X, Yin Y, Jiang Z, Tao X, Li X, Ye M, Liu Y. Inhibition of PP2A by LB100 sensitizes bladder cancer cells to chemotherapy by inducing p21 degradation. Cell Oncol 2022; 45:1203-1215. [PMID: 36136269 DOI: 10.1007/s13402-022-00710-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2022] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Bladder carcinoma (BLCA) is the most common urinary tract malignancy and exhibits a poor response to chemotherapy. Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase involved in a wide variety of regulatory cellular processes, including apoptosis and the DNA-damage response (DDR). LB100, a small molecule inhibitor of PP2A, has been shown to act as a chemo-sensitizer in multiple types of cancer. However, the anti-tumor effect and mode of action of LB100 in BLCA have yet to be identified. METHODS In vitro and in vivo experiments were performed to assess the anti-tumor effect of LB100 alone or in combination with gemcitabine. Mass spectrometry (MS)-based phosphoproteomics analysis was used to identify the downstream substrates of PP2A and to explore the mechanism underlying LB100-induced DNA damage and apoptosis. In addition, we established a chemo-resistant BLCA cell line (RT-112-R) by prolonged drug exposure and determined the effect of LB100 in enhancing genotoxicity in BLCA cell lines and xenograft mouse models. RESULTS We found that LB100 is sufficient to induce an anti-tumor response in BLCA cells by inducing DNA damage and apoptosis both in vitro and in vivo. Furthermore, we found that PP2A potentially dephosphorylates p-p21-ser130 to stabilize p21. Inhibition of PP2A by LB100 increased the level of p-p21-ser130, subsequently leading to a reduction in p21 level in a dose-dependent manner. In addition, we found that treatment of LB100 abrogated the G1/S cell cycle checkpoint, resulting in increased phosphorylation of γH2AX in BLCA cells. Moreover, LB100 enhanced genotoxicity in chemo-resistant BLCA cells by inducing DNA damage and apoptosis in vitro and in vivo. CONCLUSION Our findings indicate that PP2A may serve as a potential therapeutic target in BLCA through regulating p21 stability.
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Affiliation(s)
- Song Gao
- Department of Oncology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Liping Shan
- Department of Urology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Mo Zhang
- Department of Urology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Yan Wang
- (CAS) Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, China Academy of Sciences, Dalian, 116023, China
| | - Xi Zhan
- (CAS) Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, China Academy of Sciences, Dalian, 116023, China
| | - Yalei Yin
- (CAS) Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, China Academy of Sciences, Dalian, 116023, China
| | - Zhonghao Jiang
- Department of Hepatobiliary and Splenic Surgery, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Xinyi Tao
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, 110004, China.,Innovative Research Center for Integrated Cancer Omics, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Xinyu Li
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, 110004, China. .,Innovative Research Center for Integrated Cancer Omics, Shengjing Hospital of China Medical University, Shenyang, 110004, China.
| | - Mingliang Ye
- (CAS) Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, China Academy of Sciences, Dalian, 116023, China.
| | - Yang Liu
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, 110004, China. .,Innovative Research Center for Integrated Cancer Omics, Shengjing Hospital of China Medical University, Shenyang, 110004, China.
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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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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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Lv L, Huang RH, Li J, Xu J, Gao W. Impact of NSCLC metabolic remodeling on immunotherapy effectiveness. Biomark Res 2022; 10:66. [PMID: 36038935 PMCID: PMC9425942 DOI: 10.1186/s40364-022-00412-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/12/2022] [Indexed: 11/10/2022] Open
Abstract
It is known that metabolic reprogramming (MR) contributes to tumorigenesis through the activation of processes that support survival of cells, proliferation, and grow in the tumor microenvironment. In order to keep the tumor proliferating at a high rate, metabolic pathways must be upregulated, and tumor metabolism must be adapted to meet this requirement. Additionally, immune cells engage in metabolic remodeling to maintain body and self-health. With the advent of immunotherapy, the fate of individuals suffering from non-small cell lung cancer (NSCLC) has been transformed dramatically. MR may have a profound influence on their prognosis. The aim of this review is to summarize current research advancements in metabolic reprogramming and their impact on immunotherapy in NSCLC. Moreover, we talk about promising approaches targeting and manipulating metabolic pathways to improve cancer immunotherapy’s effectiveness in NSCLC.
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Affiliation(s)
- Lulu Lv
- Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, 210029, China
| | - Ruo Han Huang
- Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, 210029, China
| | - Jiale Li
- Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, 210029, China
| | - Jing Xu
- Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, 210029, China.
| | - Wen Gao
- Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, 210029, China.
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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 LD, Atri P, Muschen M, Tissot FLH, Miser J, Kovach JS, Sattler M, Batra SK, Kulkarni P, Salgia R. Correction: Protein Phosphatase 2A as a Therapeutic Target in Small Cell Lung Cancer. Mol Cancer Ther 2022; 21:700. [PMID: 35373301 PMCID: PMC10996841 DOI: 10.1158/1535-7163.mct-22-0104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Tinsley SL, Allen-Petersen BL. PP2A and cancer epigenetics: a therapeutic opportunity waiting to happen. NAR Cancer 2022; 4:zcac002. [PMID: 35118387 PMCID: PMC8807117 DOI: 10.1093/narcan/zcac002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 12/08/2021] [Accepted: 01/10/2022] [Indexed: 12/13/2022] Open
Abstract
The epigenetic state of chromatin is altered by regulators which influence gene expression in response to environmental stimuli. While several post-translational modifications contribute to chromatin accessibility and transcriptional programs, our understanding of the role that specific phosphorylation sites play is limited. In cancer, kinases and phosphatases are commonly deregulated resulting in increased oncogenic signaling and loss of epigenetic regulation. Aberrant epigenetic states are known to promote cellular plasticity and the development of therapeutic resistance in many cancer types, highlighting the importance of these mechanisms to cancer cell phenotypes. Protein Phosphatase 2A (PP2A) is a heterotrimeric holoenzyme that targets a diverse array of cellular proteins. The composition of the PP2A complex influences its cellular targets and activity. For this reason, PP2A can be tumor suppressive or oncogenic depending on cellular context. Understanding the nuances of PP2A regulation and its effect on epigenetic alterations can lead to new therapeutic avenues that afford more specificity and contribute to the growth of personalized medicine in the oncology field. In this review, we summarize the known PP2A-regulated substrates and potential phosphorylation sites that contribute to cancer cell epigenetics and possible strategies to therapeutically leverage this phosphatase to suppress tumor growth.
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Affiliation(s)
- Samantha L Tinsley
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
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Sibley CD, Schneekloth JS. Heterobifunctional molecules tackle targeted protein dephosphorylation. Trends Pharmacol Sci 2022; 43:263-265. [DOI: 10.1016/j.tips.2022.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/13/2022] [Accepted: 01/14/2022] [Indexed: 11/30/2022]
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