1
|
Nadel G, Yao Z, Hacohen-Lev-Ran A, Wainstein E, Maik-Rachline G, Ziv T, Naor Z, Admon A, Seger R. Phosphorylation of PP2Ac by PKC is a key regulatory step in the PP2A-switch-dependent AKT dephosphorylation that leads to apoptosis. Cell Commun Signal 2024; 22:154. [PMID: 38419089 PMCID: PMC10900696 DOI: 10.1186/s12964-024-01536-7] [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: 07/17/2023] [Accepted: 02/17/2024] [Indexed: 03/02/2024] Open
Abstract
BACKGROUND Although GqPCR activation often leads to cell survival by activating the PI3K/AKT pathway, it was previously shown that in several cell types AKT activity is reduced and leads to JNK activation and apoptosis. The mechanism of AKT inactivation in these cells involves an IGBP1-coupled PP2Ac switch that induces the dephosphorylation and inactivation of both PI3K and AKT. However, the machinery involved in the initiation of PP2A switch is not known. METHODS We used phospho-mass spectrometry to identify the phosphorylation site of PP2Ac, and raised specific antibodies to follow the regulation of this phosphorylation. Other phosphorylations were monitored by commercial antibodies. In addition, we used coimmunoprecipitation and proximity ligation assays to follow protein-protein interactions. Apoptosis was detected by a TUNEL assay as well as PARP1 cleavage using SDS-PAGE and Western blotting. RESULTS We identified Ser24 as a phosphorylation site in PP2Ac. The phosphorylation is mediated mainly by classical PKCs (PKCα and PKCβ) but not by novel PKCs (PKCδ and PKCε). By replacing the phosphorylated residue with either unphosphorylatable or phosphomimetic residues (S24A and S24E), we found that this phosphorylation event is necessary and sufficient to mediate the PP2A switch, which ultimately induces AKT inactivation, and a robust JNK-dependent apoptosis. CONCLUSION Our results show that the PP2A switch is induced by PKC-mediated phosphorylation of Ser24-PP2Ac and that this phosphorylation leads to apoptosis upon GqPCR induction of various cells. We propose that this mechanism may provide an unexpected way to treat some cancer types or problems in the endocrine machinery.
Collapse
Affiliation(s)
- Guy Nadel
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Zhong Yao
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Avital Hacohen-Lev-Ran
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Ehud Wainstein
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Galia Maik-Rachline
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Ziv
- Smoler Proteomic Center, Technion-Israel Institute of Technology, Haifa, Israel
| | - Zvi Naor
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel
| | - Arie Admon
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Rony Seger
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel.
| |
Collapse
|
2
|
Huang W, Paul D, Calin GA, Bayraktar R. miR-142: A Master Regulator in Hematological Malignancies and Therapeutic Opportunities. Cells 2023; 13:84. [PMID: 38201290 PMCID: PMC10778542 DOI: 10.3390/cells13010084] [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: 09/25/2023] [Revised: 11/29/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
MicroRNAs (miRNAs) are a type of non-coding RNA whose dysregulation is frequently associated with the onset and progression of human cancers. miR-142, an ultra-conserved miRNA with both active -3p and -5p mature strands and wide-ranging physiological targets, has been the subject of countless studies over the years. Due to its preferential expression in hematopoietic cells, miR-142 has been found to be associated with numerous types of lymphomas and leukemias. This review elucidates the multifaceted role of miR-142 in human physiology, its influence on hematopoiesis and hematopoietic cells, and its intriguing involvement in exosome-mediated miR-142 transport. Moreover, we offer a comprehensive exploration of the genetic and molecular landscape of the miR-142 genomic locus, highlighting its mutations and dysregulation within hematological malignancies. Finally, we discuss potential avenues for harnessing the therapeutic potential of miR-142 in the context of hematological malignancies.
Collapse
Affiliation(s)
- Wilson Huang
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; (W.H.); (G.A.C.)
| | - Doru Paul
- Division of Hematology and Medical Oncology, Department of Medicine, Weill Cornell Medicine, New York, NY 10065, USA;
| | - George A. Calin
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; (W.H.); (G.A.C.)
- Center for RNA Interference and Non-Coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Department of Leukemia, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Recep Bayraktar
- Center for RNA Interference and Non-Coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| |
Collapse
|
3
|
Cao Y, Jiang J, Song X, Wang X, Huang F, Li Y, Tang L, Li M, Chen Z, Chen F, Wan H. Engrailed 2 triggers the activation of multiple phosphorylation-induced signaling pathways in both transcription-dependent and -independent manners. Biochem Biophys Res Commun 2023; 680:127-134. [PMID: 37738902 DOI: 10.1016/j.bbrc.2023.09.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 09/17/2023] [Indexed: 09/24/2023]
Abstract
Homeodomain (HD)-containing proteins are typically recognized as transcription factors. Engrailed 2 (EN2) is an HD-containing protein that is highly expressed in various types of cancers, however, the mechanism underlying the biological function of EN2 is not fully understood. Here, we report a transcription-independent function of EN2 in addition to its role as a transcription factor. EN2 expression leads to the activation of multiple signaling pathways mediated by phosphorylation cascades. A phosphoproteomic analysis revealed that the phosphorylation status of numerous protein sites was altered after EN2 is expressed. Notably, EN2 was shown to interact with a myriad of proteins implicated in phosphorylation signaling cascades, as determined by immunoprecipitation-mass spectrometry (IP-MS). We validated the interaction between EN2 and B55α, the regulatory subunit of the PP2A-B55α complex, and confirmed that the phosphatase activity of the complex was suppressed by EN2 binding. To target EN2-induced malignancy, two kinds of small molecules were utilized to inhibit the EN2-activated NF-κB and AKT signaling pathways. A clear synergistic effect was observed when the activation of the two pathways was simultaneously blocked. Collectively, the data show that EN2 functions in a transcription-independent manner in addition to its role as a transcription factor. This finding may have therapeutic implications in treating esophageal squamous cell carcinoma (ESCC).
Collapse
Affiliation(s)
- Yong Cao
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Jie Jiang
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Xueqin Song
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Xiaoyan Wang
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Fang Huang
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Yan Li
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Li Tang
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Mingying Li
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Zhuang Chen
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Feng Chen
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China
| | - Haisu Wan
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China; Luzhou Key Laboratory of Molecular Cancer, Luzhou, 646000, Sichuan, China; Metabolic Vascular Disease Key Laboratory of Sichuan Province, Luzhou, 646000, Sichuan, China.
| |
Collapse
|
4
|
Nadel G, Maik-Rachline G, Seger R. JNK Cascade-Induced Apoptosis-A Unique Role in GqPCR Signaling. Int J Mol Sci 2023; 24:13527. [PMID: 37686335 PMCID: PMC10487481 DOI: 10.3390/ijms241713527] [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: 07/27/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 09/10/2023] Open
Abstract
The response of cells to extracellular signals is mediated by a variety of intracellular signaling pathways that determine stimulus-dependent cell fates. One such pathway is the cJun-N-terminal Kinase (JNK) cascade, which is mainly involved in stress-related processes. The cascade transmits its signals via a sequential activation of protein kinases, organized into three to five tiers. Proper regulation is essential for securing a proper cell fate after stimulation, and the mechanisms that regulate this cascade may involve the following: (1) Activatory or inhibitory phosphorylations, which induce or abolish signal transmission. (2) Regulatory dephosphorylation by various phosphatases. (3) Scaffold proteins that bring distinct components of the cascade in close proximity to each other. (4) Dynamic change of subcellular localization of the cascade's components. (5) Degradation of some of the components. In this review, we cover these regulatory mechanisms and emphasize the mechanism by which the JNK cascade transmits apoptotic signals. We also describe the newly discovered PP2A switch, which is an important mechanism for JNK activation that induces apoptosis downstream of the Gq protein coupled receptors. Since the JNK cascade is involved in many cellular processes that determine cell fate, addressing its regulatory mechanisms might reveal new ways to treat JNK-dependent pathologies.
Collapse
Affiliation(s)
| | | | - Rony Seger
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot 7610001, Israel; (G.N.); (G.M.-R.)
| |
Collapse
|
5
|
Kashani E, Vassella E. Pleiotropy of PP2A Phosphatases in Cancer with a Focus on Glioblastoma IDH Wildtype. Cancers (Basel) 2022; 14:5227. [PMID: 36358647 PMCID: PMC9654311 DOI: 10.3390/cancers14215227] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/13/2022] [Accepted: 10/20/2022] [Indexed: 07/29/2023] Open
Abstract
Serine/Threonine protein phosphatase 2A (PP2A) is a heterotrimeric (or occasionally, heterodimeric) phosphatase with pleiotropic functions and ubiquitous expression. Despite the fact that they all contribute to protein dephosphorylation, multiple PP2A complexes exist which differ considerably by their subcellular localization and their substrate specificity, suggesting diverse PP2A functions. PP2A complex formation is tightly regulated by means of gene expression regulation by transcription factors, microRNAs, and post-translational modifications. Furthermore, a constant competition between PP2A regulatory subunits is taking place dynamically and depending on the spatiotemporal circumstance; many of the integral subunits can outcompete the rest, subjecting them to proteolysis. PP2A modulation is especially important in the context of brain tumors due to its ability to modulate distinct glioma-promoting signal transduction pathways, such as PI3K/Akt, Wnt, Ras, NF-κb, etc. Furthermore, PP2A is also implicated in DNA repair and survival pathways that are activated upon treatment of glioma cells with chemo-radiation. Depending on the cancer cell type, preclinical studies have shown some promise in utilising PP2A activator or PP2A inhibitors to overcome therapy resistance. This review has a special focus on "glioblastoma, IDH wild-type" (GBM) tumors, for which the therapy options have limited efficacy, and tumor relapse is inevitable.
Collapse
Affiliation(s)
- Elham Kashani
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Erik Vassella
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
| |
Collapse
|
6
|
Sun J, Yang M, Zhao W, Wang F, Yang L, Tan C, Hu T, Zhu H, Zhao G. Research progress on the relationship between the TOR signaling pathway regulator, epigenetics, and tumor development. Front Genet 2022; 13:1006936. [PMID: 36212146 PMCID: PMC9539685 DOI: 10.3389/fgene.2022.1006936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 08/31/2022] [Indexed: 11/16/2022] Open
Abstract
Almost all cellular activities depend on protein folding, signaling complex assembly/disassembly, and epigenetic regulation. One of the most important regulatory mechanisms responsible for controlling these cellular processes is dynamic protein phosphorylation/dephosphorylation. Alterations in phosphorylation networks have major consequences in the form of disorders, including cancer. Many signaling cascades, including the target of rapamycin (TOR) signaling, are important participants in the cell cycle, and dysregulation in their phosphorylation/dephosphorylation status has been linked to malignancies. As a TOR signaling regulator, protein phosphatase 2A (PP2A) is responsible for most of the phosphatase activities inside the cells. On the other hand, TOR signaling pathway regulator (TIPRL) is an essential PP2A inhibitory protein. Many other physiological roles have also been suggested for TIPRL, such as modulation of TOR pathways, apoptosis, and cell proliferation. It is also reported that TIPRL was increased in various carcinomas, including non-small-cell lung carcinoma (NSCLC) and hepatocellular carcinomas (HCC). Considering the function of PP2A as a tumor suppressor and also the effect of the TIPRL/PP2A axis on apoptosis and proliferation of cancer cells, this review aims to provide a complete view of the role of TIPRL in cancer development in addition to describing TIPRL/PP2A axis and its epigenetic regulation.
Collapse
Affiliation(s)
- Jiaen Sun
- School of Medicine, Ningbo University, Ningbo, Zhejiang, China
- Department of Thoracic Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
| | - Minglei Yang
- School of Medicine, Ningbo University, Ningbo, Zhejiang, China
- Department of Thoracic Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
| | - Weidi Zhao
- School of Medicine, Ningbo University, Ningbo, Zhejiang, China
- Department of Thoracic Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
| | - Fajiu Wang
- Department of Thoracic Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
| | - Liangwei Yang
- Department of Thoracic Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
| | - Chuntao Tan
- Department of Cardiac and Vascular Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
| | - Tianjun Hu
- Department of Thoracic Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
| | - Huangkai Zhu
- School of Medicine, Ningbo University, Ningbo, Zhejiang, China
- Department of Thoracic Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
- *Correspondence: Huangkai Zhu, ; Guofang Zhao,
| | - Guofang Zhao
- School of Medicine, Ningbo University, Ningbo, Zhejiang, China
- Department of Thoracic Surgery, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, China
- *Correspondence: Huangkai Zhu, ; Guofang Zhao,
| |
Collapse
|
7
|
Goswami S, Mani R, Nunes J, Chiang CL, Zapolnik K, Hu E, Frissora F, Mo X, Walker LA, Yan P, Bundschuh R, Beaver L, Devine R, Tsai YT, Ventura A, Xie Z, Chen M, Lapalombella R, Walker A, Mims A, Larkin K, Grieselhuber N, Bennett C, Phelps M, Hertlein E, Behbehani G, Vasu S, Byrd JC, Muthusamy N. PP2A is a therapeutically targetable driver of cell fate decisions via a c-Myc/p21 axis in human and murine acute myeloid leukemia. Blood 2022; 139:1340-1358. [PMID: 34788382 PMCID: PMC8900275 DOI: 10.1182/blood.2020010344] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 10/30/2021] [Indexed: 11/20/2022] Open
Abstract
Dysregulated cellular differentiation is a hallmark of acute leukemogenesis. Phosphatases are widely suppressed in cancers but have not been traditionally associated with differentiation. In this study, we found that the silencing of protein phosphatase 2A (PP2A) directly blocks differentiation in acute myeloid leukemia (AML). Gene expression and mass cytometric profiling revealed that PP2A activation modulates cell cycle and transcriptional regulators that program terminal myeloid differentiation. Using a novel pharmacological agent, OSU-2S, in parallel with genetic approaches, we discovered that PP2A enforced c-Myc and p21 dependent terminal differentiation, proliferation arrest, and apoptosis in AML. Finally, we demonstrated that PP2A activation decreased leukemia-initiating stem cells, increased leukemic blast maturation, and improved overall survival in murine Tet2-/-Flt3ITD/WT and human cell-line derived xenograft AML models in vivo. Our findings identify the PP2A/c-Myc/p21 axis as a critical regulator of the differentiation/proliferation switch in AML that can be therapeutically targeted in malignancies with dysregulated maturation fate.
Collapse
Affiliation(s)
- Swagata Goswami
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Molecular, Cellular, and Developmental Biology Graduate Program, The Ohio State University, Columbus, OH
| | | | - Jessica Nunes
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Molecular, Cellular, and Developmental Biology Graduate Program, The Ohio State University, Columbus, OH
| | - Chi-Ling Chiang
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Kevan Zapolnik
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Eileen Hu
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Frank Frissora
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Xiaokui Mo
- Center for Biostatistics, The Ohio State University, Columbus, OH
| | - Logan A Walker
- Biophysics Graduate Program, University of Michigan, Ann Arbor, MI
| | - Pearlly Yan
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - Ralf Bundschuh
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH
- Department of Physics, The Ohio State University, Columbus, OH; and
| | - Larry Beaver
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Raymond Devine
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Yo-Ting Tsai
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Ann Ventura
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Zhiliang Xie
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Min Chen
- College of Pharmacy, The Ohio State University, Columbus, OH
| | - Rosa Lapalombella
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - Alison Walker
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - Alice Mims
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - Karilyn Larkin
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - Nicole Grieselhuber
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - Chad Bennett
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - Mitch Phelps
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- College of Pharmacy, The Ohio State University, Columbus, OH
| | - Erin Hertlein
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - Gregory Behbehani
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - Sumithira Vasu
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| | - John C Byrd
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
- College of Pharmacy, The Ohio State University, Columbus, OH
| | - Natarajan Muthusamy
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH
| |
Collapse
|
8
|
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.
Collapse
Affiliation(s)
- Samantha L Tinsley
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | | |
Collapse
|
9
|
Nadel G, Yao Z, Wainstein E, Cohen I, Ben-Ami I, Schajnovitz A, Maik-Rachline G, Naor Z, Horwitz BA, Seger R. GqPCR-stimulated dephosphorylation of AKT is induced by an IGBP1-mediated PP2A switch. Cell Commun Signal 2022; 20:5. [PMID: 34998390 PMCID: PMC8742922 DOI: 10.1186/s12964-021-00805-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/18/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND G protein-coupled receptors (GPCRs) usually regulate cellular processes via activation of intracellular signaling pathways. However, we have previously shown that in several cell lines, GqPCRs induce immediate inactivation of the AKT pathway, which leads to JNK-dependent apoptosis. This apoptosis-inducing AKT inactivation is essential for physiological functions of several GqPCRs, including those for PGF2α and GnRH. METHODS Here we used kinase activity assays of PI3K and followed phosphorylation state of proteins using specific antibodies. In addition, we used coimmunoprecipitation and proximity ligation assays to follow protein-protein interactions. Apoptosis was detected by TUNEL assay and PARP1 cleavage. RESULTS We identified the mechanism that allows the unique stimulated inactivation of AKT and show that the main regulator of this process is the phosphatase PP2A, operating with the non-canonical regulatory subunit IGBP1. In resting cells, an IGBP1-PP2Ac dimer binds to PI3K, dephosphorylates the inhibitory pSer608-p85 of PI3K and thus maintains its high basal activity. Upon GqPCR activation, the PP2Ac-IGBP1 dimer detaches from PI3K and thus allows the inhibitory dephosphorylation. At this stage, the free PP2Ac together with IGBP1 and PP2Aa binds to AKT, causing its dephosphorylation and inactivation. CONCLUSION Our results show a stimulated shift of PP2Ac from PI3K to AKT termed "PP2A switch" that represses the PI3K/AKT pathway, providing a unique mechanism of GPCR-stimulated dephosphorylation. Video Abstract.
Collapse
Affiliation(s)
- Guy Nadel
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Zhong Yao
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Ehud Wainstein
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Izel Cohen
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Ido Ben-Ami
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel.,IVF and Fertility Unit, Department of OB/GYN, Shaare Zedek Medical Center and The Hebrew University Medical School, Jerusalem, Israel
| | - Amir Schajnovitz
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Galia Maik-Rachline
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Zvi Naor
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel
| | - Benjamin A Horwitz
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel.,Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Rony Seger
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel.
| |
Collapse
|
10
|
PP2A-B55: substrates and regulators in the control of cellular functions. Oncogene 2022; 41:1-14. [PMID: 34686773 DOI: 10.1038/s41388-021-02068-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/29/2021] [Accepted: 10/06/2021] [Indexed: 12/17/2022]
Abstract
PP2A is a major serine/threonine phosphatase class involved in the regulation of cell signaling through the removal of protein phosphorylation. This class of phosphatases is comprised of different heterotrimeric complexes displaying distinct substrate specificities. The present review will focus on one specific heterocomplex, the phosphatase PP2A-B55. Herein, we will report the direct substrates of this phosphatase identified to date, and its impact on different cell signaling cascades. We will additionally describe its negative regulation by its inhibitors Arpp19 and ENSA and their upstream kinase Greatwall. Finally, we will describe the essential molecular features defining PP2A-B55 substrate specificity that confer the correct temporal pattern of substrate dephosphorylation. The main objective of this review is to provide the reader with a unique source compiling all the knowledge of this particular holoenzyme that has evolved as a key enzyme for cell homeostasis and cancer development.
Collapse
|
11
|
Hoff FW, Horton TM, Kornblau SM. Reverse phase protein arrays in acute leukemia: investigative and methodological challenges. Expert Rev Proteomics 2021; 18:1087-1097. [PMID: 34965151 DOI: 10.1080/14789450.2021.2020655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Acute leukemia results from a series of mutational events that alter cell growth and proliferation. Mutations result in protein changes that orchestrate growth alterations characteristic of leukemia. Proteomics is a methodology appropriate for study of protein changes found in leukemia. The high-throughput reverse phase protein array (RPPA) technology is particularly well-suited for the assessment of protein changes in samples derived from clinical trials. AREAS COVERED This review discusses the technical, methodological, and analytical issues related to the successful development of acute leukemia RPPAs. EXPERT COMMENTARY To obtain representative protein sample lysates, samples should be prepared from freshly collected blood or bone marrow material. Variables such as sample shipment, transit time, and holding temperature only have minimal effects on protein expression. CellSave preservation tubes are preferred for cells collected after exposure to chemotherapy, and incorporation of standardized guidelines for antibody validation is recommended. A more systematic biological approach to analyze protein expression is desired, searching for recurrent patterns of protein expression that allow classification of patients into risk groups, or groups of patients that may be treated similarly. Comparing RPPA protein analysis between cell lines and primary samples shows that cell lines are not representative of patient proteomic patterns.
Collapse
Affiliation(s)
- Fieke W Hoff
- Department of Internal Medicine, The University of Texas Southwestern Medical Center, TX, USA
| | - Terzah M Horton
- Department of Pediatrics, Texas Children's Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Steven M Kornblau
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| |
Collapse
|
12
|
Sergienko NM, Donner DG, Delbridge LMD, McMullen JR, Weeks KL. Protein phosphatase 2A in the healthy and failing heart: New insights and therapeutic opportunities. Cell Signal 2021; 91:110213. [PMID: 34902541 DOI: 10.1016/j.cellsig.2021.110213] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 12/02/2021] [Accepted: 12/07/2021] [Indexed: 02/06/2023]
Abstract
Protein phosphatases have emerged as critical regulators of phosphoprotein homeostasis in settings of health and disease. Protein phosphatase 2A (PP2A) encompasses a large subfamily of enzymes that remove phosphate groups from serine/threonine residues within phosphoproteins. The heterogeneity in PP2A structure, which arises from the grouping of different catalytic, scaffolding and regulatory subunit isoforms, creates distinct populations of catalytically active enzymes (i.e. holoenzymes) that localise to different parts of the cell. This structural complexity, combined with other regulatory mechanisms, such as interaction of PP2A heterotrimers with accessory proteins and post-translational modification of the catalytic and/or regulatory subunits, enables PP2A holoenzymes to target phosphoprotein substrates in a highly specific manner. In this review, we summarise the roles of PP2A in cardiac physiology and disease. PP2A modulates numerous processes that are vital for heart function including calcium handling, contractility, β-adrenergic signalling, metabolism and transcription. Dysregulation of PP2A has been observed in human cardiac disease settings, including heart failure and atrial fibrillation. Efforts are underway, particularly in the cancer field, to develop therapeutics targeting PP2A activity. The development of small molecule activators of PP2A (SMAPs) and other compounds that selectively target specific PP2A holoenzymes (e.g. PP2A/B56α and PP2A/B56ε) will improve understanding of the function of different PP2A species in the heart, and may lead to the development of therapeutics for normalising aberrant protein phosphorylation in settings of cardiac remodelling and dysfunction.
Collapse
Affiliation(s)
- Nicola M Sergienko
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Central Clinical School, Monash University, Clayton VIC 3800, Australia
| | - Daniel G Donner
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia
| | - Lea M D Delbridge
- Department of Anatomy and Physiology, The University of Melbourne, Parkville VIC 3010, Australia
| | - Julie R McMullen
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia; Department of Physiology and Department of Medicine Alfred Hospital, Monash University, Clayton VIC 3800, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora VIC 3086, Australia; Department of Diabetes, Central Clinical School, Monash University, Clayton VIC 3800, Australia.
| | - Kate L Weeks
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Department of Anatomy and Physiology, The University of Melbourne, Parkville VIC 3010, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia; Department of Diabetes, Central Clinical School, Monash University, Clayton VIC 3800, Australia.
| |
Collapse
|
13
|
Cancer stem cell phosphatases. Biochem J 2021; 478:2899-2920. [PMID: 34319405 DOI: 10.1042/bcj20210254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/05/2021] [Accepted: 07/07/2021] [Indexed: 12/15/2022]
Abstract
Cancer stem cells (CSCs) are involved in the initiation and progression of human malignancies by enabling cancer tissue self-renewal capacity and constituting the therapy-resistant population of tumor cells. However, despite the exhausting characterization of CSC genetics, epigenetics, and kinase signaling, eradication of CSCs remains an unattainable goal in most human malignancies. While phosphatases contribute equally with kinases to cellular phosphoregulation, our understanding of phosphatases in CSCs lags severely behind our knowledge about other CSC signaling mechanisms. Many cancer-relevant phosphatases have recently become druggable, indicating that further understanding of the CSC phosphatases might provide novel therapeutic opportunities. This review summarizes the current knowledge about fundamental, but yet poorly understood involvement of phosphatases in the regulation of major CSC signaling pathways. We also review the functional roles of phosphatases in CSC self-renewal, cancer progression, and therapy resistance; focusing particularly on hematological cancers and glioblastoma. We further discuss the small molecule targeting of CSC phosphatases and their therapeutic potential in cancer combination therapies.
Collapse
|
14
|
Goguet-Rubio P, Amin P, Awal S, Vigneron S, Charrasse S, Mechali F, Labbé JC, Lorca T, Castro A. PP2A-B55 Holoenzyme Regulation and Cancer. Biomolecules 2020; 10:biom10111586. [PMID: 33266510 PMCID: PMC7700614 DOI: 10.3390/biom10111586] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 01/05/2023] Open
Abstract
Protein phosphorylation is a post-translational modification essential for the control of the activity of most enzymes in the cell. This protein modification results from a fine-tuned balance between kinases and phosphatases. PP2A is one of the major serine/threonine phosphatases that is involved in the control of a myriad of different signaling cascades. This enzyme, often misregulated in cancer, is considered a tumor suppressor. In this review, we will focus on PP2A-B55, a particular holoenzyme of the family of the PP2A phosphatases whose specific role in cancer development and progression has only recently been highlighted. The discovery of the Greatwall (Gwl)/Arpp19-ENSA cascade, a new pathway specifically controlling PP2A-B55 activity, has been shown to be frequently altered in cancer. Herein, we will review the current knowledge about the mechanisms controlling the formation and the regulation of the activity of this phosphatase and its misregulation in cancer.
Collapse
|
15
|
Qiu Z, Fa P, Liu T, Prasad CB, Ma S, Hong Z, Chan ER, Wang H, Li Z, He K, Wang QE, Williams TM, Yan C, Sizemore ST, Narla G, Zhang J. A Genome-Wide Pooled shRNA Screen Identifies PPP2R2A as a Predictive Biomarker for the Response to ATR and CHK1 Inhibitors. Cancer Res 2020; 80:3305-3318. [PMID: 32522823 PMCID: PMC7518641 DOI: 10.1158/0008-5472.can-20-0057] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 04/17/2020] [Accepted: 06/04/2020] [Indexed: 01/18/2023]
Abstract
There is currently a lack of precise predictive biomarkers for patient selection in clinical trials of inhibitors targeting replication stress (RS) response proteins ATR and CHK1. The objective of this study was to identify novel predictive biomarkers for the response to these agents in treating non-small cell lung cancer (NSCLC). A genome-wide loss-of-function screen revealed that tumor suppressor PPP2R2A, a B regulatory subunit of protein phosphatase 2 (PP2A), determines sensitivity to CHK1 inhibition. A synthetic lethal interaction between PPP2R2A deficiency and ATR or CHK1 inhibition was observed in NSCLC in vitro and in vivo and was independent of p53 status. ATR and CHK1 inhibition resulted in significantly increased levels of RS and altered replication dynamics, particularly in PPP2R2A-deficient NSCLC cells. Mechanistically, PPP2R2A negatively regulated translation of oncogene c-Myc protein. c-Myc activity was required for PPP2R2A deficiency-induced alterations of replication initiation/RS and sensitivity to ATR/CHK1 inhibitors. We conclude that PPP2R2A deficiency elevates RS by upregulating c-Myc activity, rendering cells reliant on the ATR/CHK1 axis for survival. Our studies show a novel synthetic lethal interaction and identify PPP2R2A as a potential new predictive biomarker for patient stratification in the clinical use of ATR and CHK1 inhibitors. SIGNIFICANCE: This study reveals new approaches to specifically target PPP2R2A-deficient lung cancer cells and provides a novel biomarker that will significantly improve treatment outcome with ATR and CHK1 inhibitors.
Collapse
MESH Headings
- Animals
- Ataxia Telangiectasia Mutated Proteins/antagonists & inhibitors
- Biomarkers, Tumor/deficiency
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Non-Small-Cell Lung/chemistry
- Carcinoma, Non-Small-Cell Lung/drug therapy
- Carcinoma, Non-Small-Cell Lung/genetics
- Carcinoma, Non-Small-Cell Lung/metabolism
- Cell Line, Tumor
- Checkpoint Kinase 1/antagonists & inhibitors
- DNA Damage
- DNA Replication
- Drug Resistance, Neoplasm
- Female
- Gene Knockdown Techniques
- Genes, p53
- Genome-Wide Association Study
- Heterografts
- Humans
- Lung Neoplasms/chemistry
- Lung Neoplasms/drug therapy
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Male
- Mice
- Mice, Nude
- Protein Phosphatase 2/deficiency
- Protein Phosphatase 2/genetics
- Protein Phosphatase 2/metabolism
- Proto-Oncogene Proteins c-myc/metabolism
- RNA, Small Interfering
Collapse
Affiliation(s)
- Zhaojun Qiu
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Pengyan Fa
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Tao Liu
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Chandra B Prasad
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Shanhuai Ma
- University of Rochester, Rochester, New York
| | - Zhipeng Hong
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Ernest R Chan
- Institute for Computational Biology, Case Western Reserve University, Cleveland, Ohio
| | - Hongbing Wang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland
| | - Zaibo Li
- Department of Pathology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Kai He
- Department of Internal Medicine, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Qi-En Wang
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Terence M Williams
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Chunhong Yan
- Georgia Cancer Center, Augusta University, Augusta, Georgia
| | - Steven T Sizemore
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio
| | - Goutham Narla
- Department of Medicine, University of Michigan, Ann Arbor, Michigan
| | - Junran Zhang
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio.
| |
Collapse
|
16
|
Panicker N, Coutman M, Lawlor-O’Neill C, Kahl RGS, Roselli S, Verrills NM. Ppp2r2a Knockout Mice Reveal That Protein Phosphatase 2A Regulatory Subunit, PP2A-B55α, Is an Essential Regulator of Neuronal and Epidermal Embryonic Development. Front Cell Dev Biol 2020; 8:358. [PMID: 32582689 PMCID: PMC7290052 DOI: 10.3389/fcell.2020.00358] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/22/2020] [Indexed: 12/13/2022] Open
Abstract
The serine/threonine protein phosphatase 2A (PP2A) is a master regulator of the complex cellular signaling that occurs during all stages of mammalian development. PP2A is composed of a catalytic, a structural, and regulatory subunit, for which there are multiple isoforms. The association of specific regulatory subunits determines substrate specificity and localization of phosphatase activity, however, the precise role of each regulatory subunit in development is not known. Here we report the generation of the first knockout mouse for the Ppp2r2a gene, encoding the PP2A-B55α regulatory subunit, using CRISPR/Cas9. Heterozygous animals developed and grew as normal, however, homozygous knockout mice were not viable. Analysis of embryos at different developmental stages found a normal Mendelian ratio of Ppp2r2a-/- embryos at embryonic day (E) 10.5 (25%), but reduced Ppp2r2a-/- embryos at E14.5 (18%), and further reduced at E18.5 (10%). No live Ppp2r2a-/- pups were observed at birth. Ppp2r2a-/- embryos were significantly smaller than wild-type or heterozygous littermates and displayed a variety of neural defects such as exencephaly, spina bifida, and cranial vault collapse, as well as syndactyly and severe epidermal defects; all processes driven by growth and differentiation of the ectoderm. Ppp2r2a-/- embryos had incomplete epidermal barrier acquisition, associated with thin, poorly differentiated stratified epithelium with weak attachment to the underlying dermis. The basal keratinocytes in Ppp2r2a-/- embryos were highly disorganized, with reduced immunolabeling of integrins and basement membrane proteins, suggesting impaired focal adhesion and hemidesmosome assembly. The spinous and granular layers were thinner in the Ppp2r2a-/- embryos, with aberrant expression of adherens and tight junction associated proteins. The overlying stratum corneum was either absent or incomplete. Thus PP2A-B55α is an essential regulator of epidermal stratification, and is essential for ectodermal development during embryogenesis.
Collapse
Affiliation(s)
- Nikita Panicker
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, Priority Research Centre for Cancer Research, Innovation and Translation, University of Newcastle, Callaghan, NSW, Australia
- Hunter Cancer Research Alliance, Hunter Medical Research Institute, New Lambton, NSW, Australia
| | - Melody Coutman
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, Priority Research Centre for Cancer Research, Innovation and Translation, University of Newcastle, Callaghan, NSW, Australia
- Hunter Cancer Research Alliance, Hunter Medical Research Institute, New Lambton, NSW, Australia
| | - Charley Lawlor-O’Neill
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, Priority Research Centre for Cancer Research, Innovation and Translation, University of Newcastle, Callaghan, NSW, Australia
- Hunter Cancer Research Alliance, Hunter Medical Research Institute, New Lambton, NSW, Australia
| | - Richard G. S. Kahl
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, Priority Research Centre for Cancer Research, Innovation and Translation, University of Newcastle, Callaghan, NSW, Australia
- Hunter Cancer Research Alliance, Hunter Medical Research Institute, New Lambton, NSW, Australia
| | - Séverine Roselli
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, Priority Research Centre for Cancer Research, Innovation and Translation, University of Newcastle, Callaghan, NSW, Australia
- Hunter Cancer Research Alliance, Hunter Medical Research Institute, New Lambton, NSW, Australia
| | - Nicole M. Verrills
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, Priority Research Centre for Cancer Research, Innovation and Translation, University of Newcastle, Callaghan, NSW, Australia
- Hunter Cancer Research Alliance, Hunter Medical Research Institute, New Lambton, NSW, Australia
| |
Collapse
|
17
|
Zhang Y, Yuan T, Su Z, Wang X, Wang Y, Ni Y, Zuo Y, Gu H. Reduced methylation of PP2Ac promotes ethanol-induced lipid accumulation through FOXO1 phosphorylation in vitro and in vivo. Toxicol Lett 2020; 331:65-74. [PMID: 32492475 DOI: 10.1016/j.toxlet.2020.05.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 04/21/2020] [Accepted: 05/28/2020] [Indexed: 12/12/2022]
Abstract
Although disturbance of the methionine cycle and sequent decrease in hepatic methylation capacity are known to be important factors in the development of alcoholic liver injury, the underlying mechanisms are not fully understood. Here, we investigated the importance of the methylation of protein phosphatase 2A (PP2A) in alcoholic liver disease (ALD). We found that the severity of ethanol-induced liver injury and the extent of demethylation of PP2A catalytic C subunit (PP2Ac) were reduced after treatment with betaine, a methyl donor involved in the methionine-homocysteine cycle. These results suggest that PP2Ac methylation is decreased due to a broad decrease in hepatic methylation capacity after exposure to ethanol. Moreover, we found that the reduction in PP2Ac methylation led to increased degradation of the regulatory Bα subunit, thus promoting the phosphorylation and nuclear exclusion of Forkhead box O1 (FOXO1) and reducing FOXO1 transcriptional activity. Ultimately, the reduced activity of FOXO1 led to increased expression of TXNIP, which caused hepatic lipid accumulation. Our findings suggest that the reduction of PP2A methylation, a result of decrease hepatic methylation capacity, played an important role in ethanol-induced lipid accumulation via down-regulation of PP2A/Bα and FOXO1 phosphorylation.
Collapse
Affiliation(s)
- Yali Zhang
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China.
| | - Tianli Yuan
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| | - Zhangyao Su
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| | - Xi Wang
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| | - Yilun Wang
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| | - Yao Ni
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| | - Yue Zuo
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| | - Haohao Gu
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China
| |
Collapse
|
18
|
The Role of MYC and PP2A in the Initiation and Progression of Myeloid Leukemias. Cells 2020; 9:cells9030544. [PMID: 32110991 PMCID: PMC7140463 DOI: 10.3390/cells9030544] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/23/2020] [Accepted: 02/24/2020] [Indexed: 12/18/2022] Open
Abstract
The MYC transcription factor is one of the best characterized PP2A substrates. Deregulation of the MYC oncogene, along with inactivation of PP2A, are two frequent events in cancer. Both proteins are essential regulators of cell proliferation, apoptosis, and differentiation, and they, directly and indirectly, regulate each other’s activity. Studies in cancer suggest that targeting the MYC/PP2A network is an achievable strategy for the clinic. Here, we focus on and discuss the role of MYC and PP2A in myeloid leukemias.
Collapse
|
19
|
Wu YL, Lin YY, Sun D. Novel regulation of PKC-induced inflammation by Akt and protein phosphatase 2A in ovarian granulosa cells. CHINESE J PHYSIOL 2020; 63:179-186. [DOI: 10.4103/cjp.cjp_44_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
|
20
|
Mudgapalli N, Nallasamy P, Chava H, Chava S, Pathania AS, Gunda V, Gorantla S, Pandey MK, Gupta SC, Challagundla KB. The role of exosomes and MYC in therapy resistance of acute myeloid leukemia: Challenges and opportunities. Mol Aspects Med 2019; 70:21-32. [PMID: 31623866 DOI: 10.1016/j.mam.2019.10.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 09/27/2019] [Accepted: 10/06/2019] [Indexed: 12/12/2022]
Abstract
Acute myeloid leukemia (AML) is caused by abnormal production of white blood cells, red blood cells or platelets. The leukemia cells communicate with their microenvironment through nano-vesicle exosomes that are 30-100 nm in diameter. These nano-vesicles are released from body fluids upon fusion of an endocytic compartment with the cell membrane. Exosomes function as cargo to deliver signaling molecules to distant cells. This allows cross-talk between hematopoietic cells and other distant target cell environments. Exosomes support leukemia growth by acting as messengers between tumor cells and the microenvironment as well as inducing oncogenic factors such as c-Myc. Exosomes have also been used as biomarkers in the clinical diagnosis of leukemia. Glycogen synthase kinase-3 (GSK-3) and protein phosphatase 2A (PP2A) are two crucial signaling molecules involved in the AML pathogenesis and MYC stability. GSK-3 is a serine/threonine protein kinase that coordinates with over 40 different proteins during physiological/pathological conditions in blood cells. The dysregulation in GSK-3 has been reported during hematological malignancies. GSK-3 acts as a tumor suppressor by targeting c-MYC, MCL-1 and β-catenin. Conversely, GSK-3 can also act as tumor promoter in some instances. The pharmacological modulators of GSK-3 such as ABT-869, 6-Bromoindirubin-3'-oxime (BIO), GS-87 and LY2090314 have shown promise in the treatment of hematological malignancy. PP2A is a heterotrimeric serine/threonine phosphatase involved in the regulation of hematological malignancy. PP2A-activating drugs (PADs) can effectively antagonize leukemogenesis. The discovery of exosomes, kinase inhibitors and phosphatase activators have provided new hope to the leukemia patients. This review discusses the role of exosomes, GSK-3 and PP2A in the pathogenesis of leukemia. We provide evidence from both preclinical and clinical studies.
Collapse
Affiliation(s)
- Nithya Mudgapalli
- Department of Biochemistry and Molecular Biology, The Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
; UNMC Summer Undergraduate Research Program, University of Nebraska Medical Center, Omaha, NE, USA
| | - Palanisamy Nallasamy
- Department of Biochemistry and Molecular Biology, The Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Haritha Chava
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Srinivas Chava
- Department of Biochemistry and Molecular Biology, The Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Anup S Pathania
- Department of Biochemistry and Molecular Biology, The Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Venugopal Gunda
- Pediatric Oncology Laboratory, Child Health Research Institute, University of Nebraska Medical Center, Omaha, NE, USA
| | - Santhi Gorantla
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Manoj K Pandey
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, USA
| | - Subash C Gupta
- Laboratory for Translational Cancer Research, Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi, 221 005, India
| | - Kishore B Challagundla
- Department of Biochemistry and Molecular Biology, The Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
.
| |
Collapse
|
21
|
Ruvolo PP, Hu CW, Qiu Y, Ruvolo VR, Go RL, Hubner SE, Coombes KR, Andreeff M, Qutub AA, Kornblau SM. LGALS3 is connected to CD74 in a previously unknown protein network that is associated with poor survival in patients with AML. EBioMedicine 2019; 44:126-137. [PMID: 31105032 PMCID: PMC6604360 DOI: 10.1016/j.ebiom.2019.05.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 02/06/2023] Open
Abstract
Background Galectin 3 (LGALS3) gene expression is associated with poor survival in acute myeloid leukemia (AML) but the prognostic impact of LGALS3 protein expression in AML is unknown. LGALS3 supports diverse survival pathways including RAS mediated cascades, protein expression and stability of anti-apoptotic BCL2 family members, and activation of proliferative pathways including those mediated by beta Catenin. CD74 is a positive regulator of CD44 and CXCR4 signaling and this molecule may be critical for AML stem cell function. At present, the role of LGALS3 and CD74 in AML is unclear. In this study, we examine protein expression of LGALS3 and CD74 by reverse phase protein analysis (RPPA) and identify new protein networks associated with these molecules. In addition, we determine prognostic potential of LGALS3, CD74, and their protein networks for clinical correlates in AML patients. Methods RPPA was used to determine relative expression of LGALS3, CD74, and 229 other proteins in 231 fresh AML patient samples and 205 samples were from patients who were treated and evaluable for outcome. Pearson correlation analysis was performed to identify proteins associated with LGALS3 and CD74. Progeny clustering was performed to generate protein networks. String analysis was performed to determine protein:protein interactions in networks and to perform gene ontology analysis. Kaplan-Meir method was used to generate survival curves. Findings LGALS3 is highest in monocytic AML patients and those with elevated LGALS3 had significantly shorter remission duration compared to patients with lower LGALS3 levels (median 21.9 vs 51.3 weeks, p = 0.016). Pearson correlation of LGALS3 with 230 other proteins identifies a distinct set of 37 proteins positively correlated with LGALS3 expression levels with a high representation of proteins involved in AKT and ERK signaling pathways. Thirty-one proteins were negatively correlated with LGALS3 including an AKT phosphatase. Pearson correlation of proteins associated with CD74 identified 12 proteins negatively correlated with CD74 and 16 proteins that are positively correlated with CD74. CD74 network revealed strong association with CD44 signaling and a high representation of apoptosis regulators. Progeny clustering was used to build protein networks based on LGALS3 and CD74 associated proteins. A strong relationship of the LGALS3 network with the CD74 network was identified. For AML patients with both the LGALS3 and CD74 protein cluster active, median overall survival was only 24.3 weeks, median remission duration was 17.8 weeks, and no patient survived beyond one year. Interpretation The findings from this study identify for the first time protein networks associated with LGALS3 and CD74 in AML. Each network features unique pathway characteristics. The data also suggest that the LGALS3 network and the CD74 network each support AML cell survival and the two networks may cooperate in a novel high risk AML population. Fund Leukemia Lymphoma Society provided funds to SMK for RPPA study of AML patient population. Texas Leukemia provided funds to PPR and SMK to study CD74 and LGALS3 expression in AML patients using RPPA. No payment was involved in the production of this manuscript.
Collapse
Affiliation(s)
- Peter P Ruvolo
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Division of Molecular Hematology and Therapy, University of Texas MD Anderson Cancer Center, Houston, TX, USA.
| | - Chenyue W Hu
- Department of Biomechanical Engineering, University Texas San Antonio, San Antonio, TX, USA
| | - Yihua Qiu
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Division of Molecular Hematology and Therapy, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Vivian R Ruvolo
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Division of Molecular Hematology and Therapy, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Robin L Go
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Division of Molecular Hematology and Therapy, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Stefan E Hubner
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Division of Molecular Hematology and Therapy, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Kevin R Coombes
- Departments of Biomedical Informatics, The Ohio State University, USA
| | - Michael Andreeff
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Division of Molecular Hematology and Therapy, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Amina A Qutub
- Department of Biomechanical Engineering, University Texas San Antonio, San Antonio, TX, USA
| | - Steven M Kornblau
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Division of Molecular Hematology and Therapy, University of Texas MD Anderson Cancer Center, Houston, TX, USA.
| |
Collapse
|
22
|
Han P, Lei Y, Li D, Liu J, Yan W, Tian D. Ten years of research on the role of BVES/ POPDC1 in human disease: a review. Onco Targets Ther 2019; 12:1279-1291. [PMID: 30863095 PMCID: PMC6388986 DOI: 10.2147/ott.s192364] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Since the blood vessel epicardial substance or Popeye domain-containing protein 1 (BVES/POPDC1) was first identified in the developing heart by two independent laboratories in 1999, an increasing number of studies have investigated the structure, function, and related diseases of BVES/POPDC1. During the first 10 years following the discovery of BVES/POPDC1, studies focused mainly on its structure, expression patterns, and functions. Based on these studies, further investigations conducted over the previous decade examined the role of BVES/POPDC1 in human diseases, such as colitis, heart diseases, and human cancers. This review provides an overview of the structure and expression of BVES/POPDC1, mainly focusing on its potential role and mechanism through which it is involved in human cancers.
Collapse
Affiliation(s)
- Ping Han
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China, ;
| | - Yu Lei
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China, ;
| | - Dongxiao Li
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China, ;
| | - Jingmei Liu
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China, ;
| | - Wei Yan
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China, ;
| | - Dean Tian
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China, ;
| |
Collapse
|
23
|
Raman D, Pervaiz S. Redox inhibition of protein phosphatase PP2A: Potential implications in oncogenesis and its progression. Redox Biol 2019; 27:101105. [PMID: 30686777 PMCID: PMC6859563 DOI: 10.1016/j.redox.2019.101105] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/04/2019] [Accepted: 01/09/2019] [Indexed: 01/17/2023] Open
Abstract
Cellular processes are dictated by the active signaling of proteins relaying messages to regulate cell proliferation, apoptosis, signal transduction and cell communications. An intricate web of protein kinases and phosphatases are critical to the proper transmission of signals across such cascades. By governing 30–50% of all protein dephosphorylation in the cell, with prominent substrate proteins being key regulators of signaling cascades, the phosphatase PP2A has emerged as a celebrated player in various developmental and tumorigenic pathways, thereby posing as an attractive target for therapeutic intervention in various pathologies wherein its activity is deregulated. This review is mainly focused on refreshing our understanding of the structural and functional complexity that cocoons the PP2A phosphatase, and its expression in cancers. Additionally, we focus on its physiological regulation as well as into recent advents and strategies that have shown promise in countering the deregulation of the phosphatase through its targeted reactivation. Finally, we dwell upon one of the key regulators of PP2A in cancer cells-cellular redox status-its multifarious nature, and its integration into the reactome of PP2A, highlighting some of the significant impacts that ROS can inflict on the structural modifications and functional aspect of PP2A.
Collapse
Affiliation(s)
- Deepika Raman
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Shazib Pervaiz
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Medical Science Cluster Cancer Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; National University Cancer Institute, National University Health System, Singapore, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.
| |
Collapse
|
24
|
Role of protein phosphatases in the cancer microenvironment. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:144-152. [DOI: 10.1016/j.bbamcr.2018.07.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/29/2018] [Accepted: 07/11/2018] [Indexed: 12/15/2022]
|
25
|
Ruvolo PP, Ruvolo VR, Burks JK, Qiu Y, Wang RY, Shpall EJ, Mirandola L, Hail N, Zeng Z, McQueen T, Daver N, Post SM, Chiriva-Internati M, Kornblau SM, Andreeff M. Role of MSC-derived galectin 3 in the AML microenvironment. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2018; 1865:959-969. [PMID: 29655803 PMCID: PMC5936474 DOI: 10.1016/j.bbamcr.2018.04.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 04/09/2018] [Accepted: 04/10/2018] [Indexed: 12/16/2022]
Abstract
In acute myeloid leukemia (AML), high Galectin 3 (LGALS3) expression is associated with poor prognosis. The role of LGALS3 derived from mesenchymal stromal cells (MSC) in the AML microenvironment is unclear; however, we have recently found high LGALS3 expression in MSC derived from AML patients is associated with relapse. In this study, we used reverse phase protein analysis (RPPA) to correlate LGALS3 expression in AML MSC with 119 other proteins including variants of these proteins such as phosphorylated forms or cleaved forms to identify biologically relevant pathways. RPPA revealed that LGALS3 protein was positively correlated with expression of thirteen proteins including MYC, phosphorylated beta-Catenin (p-CTNNB1), and AKT2 and negatively correlated with expression of six proteins including integrin beta 3 (ITGB3). String analysis revealed that proteins positively correlated with LGALS3 showed strong interconnectivity. Consistent with the RPPA results, LGALS3 suppression by shRNA in MSC resulted in decreased MYC and AKT expression while ITGB3 was induced. In co-culture, the ability of AML cell to adhere to MSC LGALS3 shRNA transductants was reduced compared to AML cell adhesion to MSC control shRNA transductants. Finally, use of novel specific LGALS3 inhibitor CBP.001 in co-culture of AML cells with MSC reduced viable leukemia cell populations with induced apoptosis and augmented the chemotherapeutic effect of AraC. In summary, the current study demonstrates that MSC-derived LGALS3 may be critical for important biological pathways for MSC homeostasis and for regulating AML cell localization and survival in the leukemia microenvironmental niche.
Collapse
Affiliation(s)
- Peter P Ruvolo
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States.
| | - Vivian R Ruvolo
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Jared K Burks
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - YiHua Qiu
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Rui-Yu Wang
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Elizabeth J Shpall
- Department of Stem Cell Transplantation, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | | | - Numsen Hail
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Zhihong Zeng
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Teresa McQueen
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Naval Daver
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Sean M Post
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Maurizio Chiriva-Internati
- Kiromic Biopharma, Houston, TX, United States; Department of Lymphoma and Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Steven M Kornblau
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Michael Andreeff
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX, United States; Section of Molecular Hematology, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| |
Collapse
|
26
|
Hoff FW, Hu CW, Qutub AA, de Bont ESJM, Horton TM, Kornblau SM. Shining a light on cell signaling in leukemia through proteomics: relevance for the clinic. Expert Rev Proteomics 2018; 15:613-622. [PMID: 29898608 PMCID: PMC6444923 DOI: 10.1080/14789450.2018.1487781] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
INTRODUCTION Although cure rates for acute leukemia have steadily improved over the past decades, leukemia remains a deadly disease. Enhanced risk stratification and new therapies are needed to improve outcome. Extensive genetic analyses have identified many mutations that contribute to the development of leukemia. However, most mutations occur infrequently and most gene alterations have been difficult to target. Most patients have more than one driver mutation in combination with secondary mutations, that result in a leukemic transformation via the alteration of proteins. The proteomics of acute leukemia could more directly identify proteins to facilitate risk stratification, predict chemoresistance and aid selection of therapy. Areas covered: This review discusses aberrantly expressed proteins identified by mass spectrometry and reverse phase protein arrays and their relationship to survival. In addition, we will discuss proteins in the context of functionally related protein groups. Expert commentary: Proteomics is a powerful tool to analyze protein abundance and functional alterations simultaneously for large numbers of patients. In the forthcoming years, validation of tools to quickly assess protein levels to enable routine rapid profiling of proteins with differential abundance and functional activation may be used as adjuncts to aid in therapy selection and to provide additional prognostic insights.
Collapse
Affiliation(s)
- Fieke W. Hoff
- Department of Pediatric Oncology/Hematology, Beatrix Children’s Hospital, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Chenyue W. Hu
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Amina A. Qutub
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Eveline S. J. M. de Bont
- Department of Pediatric Oncology/Hematology, Beatrix Children’s Hospital, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Terzah M. Horton
- Department of Pediatrics, Baylor College of Medicine, Texas Children’s Cancer Center, Houston, TX, USA
- Co-senior author
| | - Steven M. Kornblau
- Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
- Co-senior author
| |
Collapse
|
27
|
Koutsioumpa M, Chen HW, O'Brien N, Koinis F, Mahurkar-Joshi S, Vorvis C, Soroosh A, Luo T, Issakhanian S, Pantuck AJ, Georgoulias V, Iliopoulos D, Slamon DJ, Drakaki A. MKAD-21 Suppresses the Oncogenic Activity of the miR-21/PPP2R2A/ERK Molecular Network in Bladder Cancer. Mol Cancer Ther 2018; 17:1430-1440. [PMID: 29703843 DOI: 10.1158/1535-7163.mct-17-1049] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 02/20/2018] [Accepted: 04/16/2018] [Indexed: 11/16/2022]
Abstract
Bladder cancer represents a disease associated with significant morbidity and mortality. MiR-21 has been found to have oncogenic activity in multiple cancers, including bladder cancer, whereas inhibition of its expression suppresses tumor growth. Here, we examine the molecular network regulated by miR-21 in bladder cancer and evaluate the effects of i.v. and i.p. administration of a novel miR-21 chemical inhibitor in vivo LNA miR-21 reduced the oncogenic potential of bladder cancer cells, whereas the MKAD-21 chemically modified antisense oligo against miR-21 dose-dependently blocked xenograft growth. I.v. administration of LNA miR-21 was more effective in suppressing tumor growth than was i.p. administration. Integration of computational and transcriptomic analyses in a panel of 28 bladder cancer lines revealed a 15-gene signature that correlates with miR-21 levels. Protein Phosphatase 2 Regulatory Subunit Balpha (PPP2R2A) was one of these 15 genes and was experimentally validated as a novel miR-21 direct target gene. Gene network and molecular analyses showed that PPP2R2A is a potent negative regulator of the ERK pathway activation and bladder cancer cell proliferation. Importantly, we show that PPP2R2A acts as a mediator of miR-21-induced oncogenic effects in bladder cancer. Integrative analysis of human bladder cancer tumors and a large panel of human bladder cancer cell lines revealed a novel 15-gene signature that correlates with miR-21 levels. Importantly, we provide evidence that PPP2R2A represents a new miR-21 direct target and regulator of the ERK pathway and bladder cancer cell growth. Furthermore, i.v. administration of the MKAD-21 inhibitor effectively suppressed tumor growth through regulation of the PPP2R2A-ERK network in mice. Mol Cancer Ther; 17(7); 1430-40. ©2018 AACR.
Collapse
Affiliation(s)
- Marina Koutsioumpa
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Hsiao-Wang Chen
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Neil O'Brien
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Filippos Koinis
- Laboratory of Tumor Cell Biology and Department of Medical Oncology, School of Medicine, University of Crete, Heraklion, Greece
| | - Swapna Mahurkar-Joshi
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Christina Vorvis
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Artin Soroosh
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Tong Luo
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Shawnt Issakhanian
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Allan J Pantuck
- Department of Urology, Institute of Urologic Oncology, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Vassilis Georgoulias
- Laboratory of Tumor Cell Biology and Department of Medical Oncology, School of Medicine, University of Crete, Heraklion, Greece
| | - Dimitrios Iliopoulos
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Dennis J Slamon
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Alexandra Drakaki
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California.
- Department of Urology, Institute of Urologic Oncology, David Geffen School of Medicine, UCLA, Los Angeles, California
| |
Collapse
|
28
|
Zou Q, Xiao X, Liang Y, Peng L, Guo Z, Li W, Yu W. miR-19a-mediated downregulation of RhoB inhibits the dephosphorylation of AKT1 and induces osteosarcoma cell metastasis. Cancer Lett 2018; 428:147-159. [PMID: 29702193 DOI: 10.1016/j.canlet.2018.04.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 04/18/2018] [Accepted: 04/18/2018] [Indexed: 12/30/2022]
Abstract
Osteosarcoma is a primary malignancy that develops in bone, along with serious recurrence and metastasis. As an isoform of Rho family GTPases, RhoB could suppress cell proliferation, invasion, and anti-angiogenesis. But it is not clear how RhoB involves in tumor metastasis. Here we found that expression of RhoB was decreased in osteosarcoma primary samples and cell lines. Ectopic expression of RhoB restrains the migration of osteosarcoma cells in vitro and in vivo, and induces osteosarcoma cell apopotsis. Further study showed that overexpression of RhoB could increase the proportion of B55 in PP2A complex and enhance the dephosphorylation of AKT1 by interacting with B55. Moreover, we demonstrated that miR-19a, which exhibits abnormal expression in highly metastatic osteosarcoma cell lines, could inhibit the expression of RhoB and promote the lung metastasis of osteosarcoma cells in vivo. Our results indicate that miR-19a-mediated RhoB is a critical regulator for the dephosphorylation of AKT1 in osteosarcoma cells. It may have a possible strategy on suppressing osteosarcoma metastasis by miR-19a inhibitory oligonucleotides. The miR-19a/RhoB/AKT1 network may help us to better understand the mechanism of osteosarcoma metastasis.
Collapse
Affiliation(s)
- Qingping Zou
- Laboratory of RNA Epigenetics, Institute of Biomedical Sciences & Shanghai Public Health Clinical Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Department of Biochemistry and Molecular Biology, Shanghai Medical College, MOE Key Laboratory of Metabolism and Molecular Medicine, Department of Molecular Biology, Fudan University, Shanghai, 200032, China; Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Xin Xiao
- Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, 710032, China
| | - Ying Liang
- Laboratory of RNA Epigenetics, Institute of Biomedical Sciences & Shanghai Public Health Clinical Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Department of Biochemistry and Molecular Biology, Shanghai Medical College, MOE Key Laboratory of Metabolism and Molecular Medicine, Department of Molecular Biology, Fudan University, Shanghai, 200032, China; Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Lina Peng
- Laboratory of RNA Epigenetics, Institute of Biomedical Sciences & Shanghai Public Health Clinical Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Department of Biochemistry and Molecular Biology, Shanghai Medical College, MOE Key Laboratory of Metabolism and Molecular Medicine, Department of Molecular Biology, Fudan University, Shanghai, 200032, China; Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Zheng Guo
- Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, 710032, China.
| | - Wei Li
- Laboratory of RNA Epigenetics, Institute of Biomedical Sciences & Shanghai Public Health Clinical Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Department of Biochemistry and Molecular Biology, Shanghai Medical College, MOE Key Laboratory of Metabolism and Molecular Medicine, Department of Molecular Biology, Fudan University, Shanghai, 200032, China.
| | - Wenqiang Yu
- Laboratory of RNA Epigenetics, Institute of Biomedical Sciences & Shanghai Public Health Clinical Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Department of Biochemistry and Molecular Biology, Shanghai Medical College, MOE Key Laboratory of Metabolism and Molecular Medicine, Department of Molecular Biology, Fudan University, Shanghai, 200032, China; Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China.
| |
Collapse
|
29
|
Shouse G, de Necochea-Campion R, Mirshahidi S, Liu X, Chen CS. Novel B55α-PP2A mutations in AML promote AKT T308 phosphorylation and sensitivity to AKT inhibitor-induced growth arrest. Oncotarget 2018; 7:61081-61092. [PMID: 27531894 PMCID: PMC5308637 DOI: 10.18632/oncotarget.11209] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 07/27/2016] [Indexed: 01/10/2023] Open
Abstract
Activation of the Protein Kinase B (PKB), or AKT pathway has been shown to correlate with acute myeloid leukemia (AML) prognosis. B55α-Protein Phosphatase 2A (PP2A) has been shown to dephosphorylate AKT at Thr-308 rendering it inactive. In fact, low expression of the PP2A regulatory subunit B55α was associated with activated phospho-AKT and correlated with inferior outcomes in AML. Despite this fact, no studies have specifically demonstrated a mechanism whereby B55α expression is regulated in AML. In this study, we demonstrate novel loss of function mutations in the PPP2R2A gene identified in leukemic blasts from three AML patients. These mutations eliminate B55α protein expression thereby allowing constitutive AKT activation. In addition, leukemic blasts with PPP2R2A gene mutation were more sensitive to treatment with the AKT inhibitor MK2206, but less responsive to the PP2A activator FTY720. Using leukemia cell lines, we further demonstrate that B55α expression correlates with AKT Thr-308 phosphorylation and predicts responsiveness to AKT inhibition and PP2A activation. Together our data illustrate the importance of the B55α-PP2A-AKT pathway in leukemogenesis. Screening for disruptions in this pathway at initial AML diagnosis may predict response to targeted therapies against AKT and PP2A.
Collapse
Affiliation(s)
- Geoffrey Shouse
- Division of Hematology/Oncology, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Rosalia de Necochea-Campion
- Loma Linda University Cancer Center, Biospecimen Laboratory, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Saied Mirshahidi
- Loma Linda University Cancer Center, Biospecimen Laboratory, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Xuan Liu
- Department of Biochemistry, University of California, Riverside, Riverside, CA, USA
| | - Chien-Shing Chen
- Division of Hematology/Oncology, Loma Linda University School of Medicine, Loma Linda, CA, USA.,Loma Linda University Cancer Center, Biospecimen Laboratory, Loma Linda University School of Medicine, Loma Linda, CA, USA
| |
Collapse
|
30
|
Kornblau SM, Ruvolo PP, Wang RY, Battula VL, Shpall EJ, Ruvolo VR, McQueen T, Qui Y, Zeng Z, Pierce S, Jacamo R, Yoo SY, Le PM, Sun J, Hail N, Konopleva M, Andreeff M. Distinct protein signatures of acute myeloid leukemia bone marrow-derived stromal cells are prognostic for patient survival. Haematologica 2018; 103:810-821. [PMID: 29545342 PMCID: PMC5927978 DOI: 10.3324/haematol.2017.172429] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 02/01/2018] [Indexed: 02/06/2023] Open
Abstract
Mesenchymal stromal cells (MSC) support acute myeloid leukemia (AML) cell survival in the bone marrow (BM) microenvironment. Protein expression profiles of AML-derived MSC are unknown. Reverse phase protein array analysis was performed to compare expression of 151 proteins from AML-MSC (n=106) with MSC from healthy donors (n=71). Protein expression differed significantly between the two groups with 19 proteins over-expressed in leukemia stromal cells and 9 over-expressed in normal stromal cells. Unbiased hierarchical clustering analysis of the samples using these 28 proteins revealed three protein constellations whose variation in expression defined four MSC protein expression signatures: Class 1, Class 2, Class 3, and Class 4. These cell populations appear to have clinical relevance. Specifically, patients with Class 3 cells have longer survival and remission duration compared to other groups. Comparison of leukemia MSC at first diagnosis with those obtained at salvage (i.e. relapse/refractory) showed differential expression of 9 proteins reflecting a shift toward osteogenic differentiation. Leukemia MSC are more senescent compared to their normal counterparts, possibly due to the overexpressed p53/p21 axis as confirmed by high β-galactosidase staining. In addition, overexpression of BCL-XL in leukemia MSC might give survival advantage under conditions of senescence or stress and overexpressed galectin-3 exerts profound immunosuppression. Together, our findings suggest that the identification of specific populations of MSC in AML patients may be an important determinant of therapeutic response.
Collapse
Affiliation(s)
- Steven M Kornblau
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Peter P Ruvolo
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Rui-Yu Wang
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - V Lokesh Battula
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Elizabeth J Shpall
- Department of Stem Cell Transplantation, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Vivian R Ruvolo
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Teresa McQueen
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - YiHua Qui
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Zhihong Zeng
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Sherry Pierce
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Rodrigo Jacamo
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Suk-Young Yoo
- Bioinformatics and Computational Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Phuong M Le
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Jeffrey Sun
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Numsen Hail
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Marina Konopleva
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| | - Michael Andreeff
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX, USA
| |
Collapse
|
31
|
Smith AM, Dun MD, Lee EM, Harrison C, Kahl R, Flanagan H, Panicker N, Mashkani B, Don AS, Morris J, Toop H, Lock RB, Powell JA, Thomas D, Guthridge MA, Moore A, Ashman LK, Skelding KA, Enjeti A, Verrills NM. Activation of protein phosphatase 2A in FLT3+ acute myeloid leukemia cells enhances the cytotoxicity of FLT3 tyrosine kinase inhibitors. Oncotarget 2018; 7:47465-47478. [PMID: 27329844 PMCID: PMC5216954 DOI: 10.18632/oncotarget.10167] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 06/06/2016] [Indexed: 11/25/2022] Open
Abstract
Constitutive activation of the receptor tyrosine kinase Fms-like tyrosine kinase 3 (FLT3), via co-expression of its ligand or by genetic mutation, is common in acute myeloid leukemia (AML). In this study we show that FLT3 activation inhibits the activity of the tumor suppressor, protein phosphatase 2A (PP2A). Using BaF3 cells transduced with wildtype or mutant FLT3, we show that FLT3-induced PP2A inhibition sensitizes cells to the pharmacological PP2A activators, FTY720 and AAL(S). FTY720 and AAL(S) induced cell death and inhibited colony formation of FLT3 activated cells. Furthermore, PP2A activators reduced the phosphorylation of ERK and AKT, downstream targets shared by both FLT3 and PP2A, in FLT3/ITD+ BaF3 and MV4-11 cell lines. PP2A activity was lower in primary human bone marrow derived AML blasts compared to normal bone marrow, with blasts from FLT3-ITD patients displaying lower PP2A activity than WT-FLT3 blasts. Reduced PP2A activity was associated with hyperphosphorylation of the PP2A catalytic subunit, and reduced expression of PP2A structural and regulatory subunits. AML patient blasts were also sensitive to cell death induced by FTY720 and AAL(S), but these compounds had minimal effect on normal CD34+ bone marrow derived monocytes. Finally, PP2A activating compounds displayed synergistic effects when used in combination with tyrosine kinase inhibitors in FLT3-ITD+ cells. A combination of Sorafenib and FTY720 was also synergistic in the presence of a protective stromal microenvironment. Thus combining a PP2A activating compound and a FLT3 inhibitor may be a novel therapeutic approach for treating AML.
Collapse
Affiliation(s)
- Amanda M Smith
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia.,Current address: The University of Queensland Diamantina Institute, Woolloongabba, Queensland, Australia
| | - Matthew D Dun
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Erwin M Lee
- Children's Cancer Institute Australia for Medical Research, Lowy Cancer Research Centre, UNSW, Sydney, New South Wales, Australia
| | - Celeste Harrison
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Richard Kahl
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Hayley Flanagan
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Nikita Panicker
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Baratali Mashkani
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia.,Current address: Department of Medical Biochemistry, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Anthony S Don
- Prince of Wales Clinical School, University of New South Wales, Sydney, New South Wales, Australia
| | - Jonathan Morris
- School of Chemistry, University of New South Wales, Sydney, New South Wales, Australia
| | - Hamish Toop
- School of Chemistry, University of New South Wales, Sydney, New South Wales, Australia
| | - Richard B Lock
- Children's Cancer Institute Australia for Medical Research, Lowy Cancer Research Centre, UNSW, Sydney, New South Wales, Australia
| | - Jason A Powell
- Centre for Cancer Biology, SA Pathology, Adelaide, South Australia, Australia
| | - Daniel Thomas
- Centre for Cancer Biology, SA Pathology, Adelaide, South Australia, Australia.,Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Mark A Guthridge
- Department Clinical Haematology, Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria, Australia
| | - Andrew Moore
- Translational Research Institute, The University of Queensland Diamantina Institute, Woolloongabba, Queensland, Australia
| | - Leonie K Ashman
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Kathryn A Skelding
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Anoop Enjeti
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia.,Calvary Mater Hospital, Newcastle, New South Wales, Australia
| | - Nicole M Verrills
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| |
Collapse
|
32
|
Tsuchiya Y, Osaki K, Kanamoto M, Nakao Y, Takahashi E, Higuchi T, Kamata H. Distinct B subunits of PP2A regulate the NF-κB signalling pathway through dephosphorylation of IKKβ, IκBα and RelA. FEBS Lett 2017; 591:4083-4094. [PMID: 29139553 PMCID: PMC5767752 DOI: 10.1002/1873-3468.12912] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/04/2017] [Accepted: 10/25/2017] [Indexed: 12/23/2022]
Abstract
PP2A is composed of a scaffolding subunit (A), a catalytic subunit (C) and a regulatory subunit (B) that is classified into four families including B, B′, B′′ and B′′′/striatin. Here, we found that a distinct PP2A complex regulates NF‐κB signalling by dephosphorylation of IKKβ, IκBα and RelA/p65. The PP2A core enzyme AC dimer and the holoenzyme AB′′′C trimer dephosphorylate IKKβ, IκBα and RelA, whereas the ABC trimer dephosphorylates IκBα but not IKKβ and RelA in cells. In contrast, AB′C and AB′′C trimers have little effect on dephosphorylation of these signalling proteins. These results suggest that different forms of PP2A regulate NF‐κB pathway signalling through multiple steps each in a different manner, thereby finely tuning NF‐κB‐ and IKKβ‐mediated cellular responses.
Collapse
Affiliation(s)
- Yoshihiro Tsuchiya
- Laboratory of Biomedical Chemistry, Department of Molecular Medical Science, Graduate School of Biomedical Science, Hiroshima University, Japan
| | - Keiko Osaki
- Laboratory of Biomedical Chemistry, Department of Molecular Medical Science, Graduate School of Biomedical Science, Hiroshima University, Japan
| | - Mayu Kanamoto
- Laboratory of Biomedical Chemistry, Department of Molecular Medical Science, Graduate School of Biomedical Science, Hiroshima University, Japan
| | - Yuki Nakao
- Laboratory of Biomedical Chemistry, Department of Molecular Medical Science, Graduate School of Biomedical Science, Hiroshima University, Japan
| | - Ena Takahashi
- Laboratory of Biomedical Chemistry, Department of Molecular Medical Science, Graduate School of Biomedical Science, Hiroshima University, Japan
| | - Toru Higuchi
- Laboratory of Biomedical Chemistry, Department of Molecular Medical Science, Graduate School of Biomedical Science, Hiroshima University, Japan
| | - Hideaki Kamata
- Laboratory of Biomedical Chemistry, Department of Molecular Medical Science, Graduate School of Biomedical Science, Hiroshima University, Japan
| |
Collapse
|
33
|
Protein kinase B: emerging mechanisms of isoform-specific regulation of cellular signaling in cancer. Anticancer Drugs 2017; 28:569-580. [PMID: 28379898 DOI: 10.1097/cad.0000000000000496] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The serine/threonine protein kinase B (PKB), also known as Akt, is one of the multifaceted kinases in the human kinome, existing in three isoforms. PKB plays a vital role in phosphoinositide 3-kinase (PI3K)-mediated oncogenesis in various malignancies and is one of the attractive targets for cancer drug discovery. Recent studies have shown that the functional significance of an individual isoform of PKB is not redundant in cancer. It has been found that PKB isoforms play distinct roles in the regulation of cellular invasion and migration during tumorigenesis. PKB activation plays a central role during epithelial-mesenchymal transition, a cellular program required for the cancer cell invasion and migration. However, the differential behavior of each PKB isoform has been shown in the regulation of epithelial-mesenchymal transition. Recent studies have suggested that PKBα (Akt1) plays a conflicting role in tumorigenesis by acting either as a pro-oncogenic factor by suppressing the apoptotic machinery or by restricting tumor invasion. PKBβ (Akt2) promotes cell migration and invasion and similarly PKBγ (Akt3) has been reported to promote tumor migration. As PKB is known for its pro-oncogenic properties, it needs to be unraveled how three isoforms of PKB compensate during tumor progression. In this review, we attempted to sum up how different isoforms of PKB play a role in cancer progression, metastasis, and drug resistance.
Collapse
|
34
|
Wiredja DD, Ayati M, Mazhar S, Sangodkar J, Maxwell S, Schlatzer D, Narla G, Koyutürk M, Chance MR. Phosphoproteomics Profiling of Nonsmall Cell Lung Cancer Cells Treated with a Novel Phosphatase Activator. Proteomics 2017; 17. [PMID: 28961369 DOI: 10.1002/pmic.201700214] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/07/2017] [Indexed: 01/17/2023]
Abstract
Activation of protein phosphatase 2A (PP2A) is a promising anticancer therapeutic strategy, as this tumor suppressor has the ability to coordinately downregulate multiple pathways involved in the regulation of cellular growth and proliferation. In order to understand the systems-level perturbations mediated by PP2A activation, we carried out mass spectrometry-based phosphoproteomic analysis of two KRAS mutated non-small cell lung cancer (NSCLC) cell lines (A549 and H358) treated with a novel small molecule activator of PP2A (SMAP). Overall, this permitted quantification of differential signaling across over 1600 phosphoproteins and 3000 phosphosites. Kinase activity assessment and pathway enrichment implicate collective downregulation of RAS and cell cycle kinases in the case of both cell lines upon PP2A activation. However, the effects on RAS-related signaling are attenuated for A549 compared to H358, while the effects on cell cycle-related kinases are noticeably more prominent in A549. Network-based analyses and validation experiments confirm these detailed differences in signaling. These studies reveal the power of phosphoproteomics studies, coupled to computational systems biology, to elucidate global patterns of phosphatase activation and understand the variations in response to PP2A activation across genetically similar NSCLC cell lines.
Collapse
Affiliation(s)
- Danica D Wiredja
- Center for Proteomics and Bioinformatics, Department of Nutrition, Case Western Reserve University, Cleveland, OH, USA
| | - Marzieh Ayati
- Department of Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, OH, USA
| | - Sahar Mazhar
- Department of Pathology, Case Western Reserve University,, Cleveland, OH, USA
| | - Jaya Sangodkar
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, NY, USA
| | - Sean Maxwell
- Center for Proteomics and Bioinformatics, Department of Nutrition, Case Western Reserve University, Cleveland, OH, USA
| | - Daniela Schlatzer
- Center for Proteomics and Bioinformatics, Department of Nutrition, Case Western Reserve University, Cleveland, OH, USA
| | - Goutham Narla
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
| | - Mehmet Koyutürk
- Department of Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, OH, USA
| | - Mark R Chance
- Center for Proteomics and Bioinformatics, Department of Nutrition, Case Western Reserve University, Cleveland, OH, USA.,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
| |
Collapse
|
35
|
Meeusen B, Janssens V. Tumor suppressive protein phosphatases in human cancer: Emerging targets for therapeutic intervention and tumor stratification. Int J Biochem Cell Biol 2017; 96:98-134. [PMID: 29031806 DOI: 10.1016/j.biocel.2017.10.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 02/06/2023]
Abstract
Aberrant protein phosphorylation is one of the hallmarks of cancer cells, and in many cases a prerequisite to sustain tumor development and progression. Like protein kinases, protein phosphatases are key regulators of cell signaling. However, their contribution to aberrant signaling in cancer cells is overall less well appreciated, and therefore, their clinical potential remains largely unexploited. In this review, we provide an overview of tumor suppressive protein phosphatases in human cancer. Along their mechanisms of inactivation in defined cancer contexts, we give an overview of their functional roles in diverse signaling pathways that contribute to their tumor suppressive abilities. Finally, we discuss their emerging roles as predictive or prognostic markers, their potential as synthetic lethality targets, and the current feasibility of their reactivation with pharmacologic compounds as promising new cancer therapies. We conclude that their inclusion in clinical practice has obvious potential to significantly improve therapeutic outcome in various ways, and should now definitely be pushed forward.
Collapse
Affiliation(s)
- Bob Meeusen
- Laboratory of Protein Phosphorylation & Proteomics, Dept. of Cellular & Molecular Medicine, Faculty of Medicine, KU Leuven & Leuven Cancer Institute (LKI), KU Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation & Proteomics, Dept. of Cellular & Molecular Medicine, Faculty of Medicine, KU Leuven & Leuven Cancer Institute (LKI), KU Leuven, Belgium.
| |
Collapse
|
36
|
Calvayrac O, Pradines A, Favre G. RHOB expression controls the activity of serine/threonine protein phosphatase PP2A to modulate mesenchymal phenotype and invasion in non-small cell lung cancers. Small GTPases 2016; 9:339-344. [PMID: 27676292 DOI: 10.1080/21541248.2016.1234429] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Metastatic dissemination is the cause of death in the vast majority of cancers, including lung cancers. In order to metastasize, tumor cells must undergo a well-known series of changes, however the molecular details of how they manage to overcome the barriers at each stage remain incomplete. One critical step is acquiring the ability to migrate through the extracellular matrix. Loss of expression of the RAS-related small GTPase RHOB is a common feature of lung cancer progression, and we recently reported that this induces an epithelial-to-mesenchymal transition (EMT) that is dependent on SLUG overexpression and E-Cadherin inhibition and is characterized by 3-dimensional cell shape reorganization and the increased invasiveness of bronchial cells. RHOB loss was found to induce AKT1 activation, which in turn activates RAC1 through its GEF TRIO. Further investigation of this pathway revealed that RHOB interacts with and positively regulates PP2A, one of the major cellular serine-threonine phosphatases, by recruiting its regulatory subunit B55. Here we discuss the role of this newly discovered RHOB/PP2A/AKT1/RAC1 pathway in relation to mesenchymal migration and invasion in lung cancer.
Collapse
Affiliation(s)
- Olivier Calvayrac
- a Inserm, Center de Recherche en Cancérologie de Toulouse, CRCT UMR-1037 , Toulouse , France.,b Université Paul Sabatier , Toulouse , France
| | - Anne Pradines
- a Inserm, Center de Recherche en Cancérologie de Toulouse, CRCT UMR-1037 , Toulouse , France.,b Université Paul Sabatier , Toulouse , France.,c Institut Claudius Regaud, IUCT-Oncopole, Laboratoire de Biologie Médicale Oncologique , Toulouse , France
| | - Gilles Favre
- a Inserm, Center de Recherche en Cancérologie de Toulouse, CRCT UMR-1037 , Toulouse , France.,b Université Paul Sabatier , Toulouse , France.,c Institut Claudius Regaud, IUCT-Oncopole, Laboratoire de Biologie Médicale Oncologique , Toulouse , France
| |
Collapse
|
37
|
The broken "Off" switch in cancer signaling: PP2A as a regulator of tumorigenesis, drug resistance, and immune surveillance. BBA CLINICAL 2016; 6:87-99. [PMID: 27556014 PMCID: PMC4986044 DOI: 10.1016/j.bbacli.2016.08.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/01/2016] [Accepted: 08/02/2016] [Indexed: 12/31/2022]
Abstract
Aberrant activation of signal transduction pathways can transform a normal cell to a malignant one and can impart survival properties that render cancer cells resistant to therapy. A diverse set of cascades have been implicated in various cancers including those mediated by serine/threonine kinases such RAS, PI3K/AKT, and PKC. Signal transduction is a dynamic process involving both "On" and "Off" switches. Activating mutations of RAS or PI3K can be viewed as the switch being stuck in the "On" position resulting in continued signaling by a survival and/or proliferation pathway. On the other hand, inactivation of protein phosphatases such as the PP2A family can be seen as the defective "Off" switch that similarly can activate these pathways. A problem for therapeutic targeting of PP2A is that the enzyme is a hetero-trimer and thus drug targeting involves complex structures. More importantly, since PP2A isoforms generally act as tumor suppressors one would want to activate these enzymes rather than suppress them. The elucidation of the role of cellular inhibitors like SET and CIP2A in cancer suggests that targeting these proteins can have therapeutic efficacy by mechanisms involving PP2A activation. Furthermore, drugs such as FTY-720 can activate PP2A isoforms directly. This review will cover the current state of knowledge of PP2A role as a tumor suppressor in cancer cells and as a mediator of processes that can impact drug resistance and immune surveillance.
Collapse
|
38
|
Liu H, Gu Y, Wang H, Yin J, Zheng G, Zhang Z, Lu M, Wang C, He Z. Overexpression of PP2A inhibitor SET oncoprotein is associated with tumor progression and poor prognosis in human non-small cell lung cancer. Oncotarget 2016; 6:14913-25. [PMID: 25945834 PMCID: PMC4558125 DOI: 10.18632/oncotarget.3818] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 03/29/2015] [Indexed: 01/09/2023] Open
Abstract
SET oncoprotein is an endogenous inhibitor of protein phosphatase 2A (PP2A), and SET-mediated PP2A inhibition is an important regulatory mechanism for promoting cancer initiation and progression of several types of human leukemia disease. However, its potential relevance in solid tumors as non-small cell lung cancer (NSCLC) remains mostly unknown. In this study, we showed that SET was evidently overexpressed in human NSCLC cell lines and NSCLC tissues. Clinicopathologic analysis showed that SET expression was significantly correlated with clinical stage (p < 0.001), and lymph node metastasis (p < 0.05). Kaplan-Meier analysis revealed that patients with high SET expression had poorer overall survival rates than those with low SET expression. Moreover, knockdown of SET in NSCLC cells resulted in attenuated proliferative and invasive abilities. The biological effect of SET on proliferation and invasion was mediated by the inhibition of the PP2A, which in turn, activation of AKT and ERK, increased the expression of cyclin D1 and MMP9, and decreased the expression of p27. Furthermore, we observed that restoration of PP2A using SET antagonist FTY720 impaired proliferative and invasive potential in vitro, as well as inhibited tumor growth in vivo of NSCLC cells. Taken together, SET oncoprotein plays an important role in NSCLC progression, which could serve as a potential prognosis marker and a novel therapeutic target for NSCLC patients.
Collapse
Affiliation(s)
- Hao Liu
- Cancer Hospital and Cancer Research Institute, Guangzhou Medical University, Guangzhou, PR China
| | - Yixue Gu
- Cancer Hospital and Cancer Research Institute, Guangzhou Medical University, Guangzhou, PR China
| | - Hongsheng Wang
- Department of Microbial and Biochemical Pharmacy, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, PR China
| | - Jiang Yin
- Cancer Hospital and Cancer Research Institute, Guangzhou Medical University, Guangzhou, PR China
| | - Guopei Zheng
- Cancer Hospital and Cancer Research Institute, Guangzhou Medical University, Guangzhou, PR China
| | - Zhijie Zhang
- Cancer Hospital and Cancer Research Institute, Guangzhou Medical University, Guangzhou, PR China
| | - Minyin Lu
- Cancer Hospital and Cancer Research Institute, Guangzhou Medical University, Guangzhou, PR China
| | - Chenkun Wang
- Cancer Hospital and Cancer Research Institute, Guangzhou Medical University, Guangzhou, PR China
| | - Zhimin He
- Cancer Hospital and Cancer Research Institute, Guangzhou Medical University, Guangzhou, PR China
| |
Collapse
|
39
|
Arriazu E, Pippa R, Odero MD. Protein Phosphatase 2A as a Therapeutic Target in Acute Myeloid Leukemia. Front Oncol 2016; 6:78. [PMID: 27092295 PMCID: PMC4822158 DOI: 10.3389/fonc.2016.00078] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/21/2016] [Indexed: 12/31/2022] Open
Abstract
Acute myeloid leukemia (AML) is a heterogeneous malignant disorder of hematopoietic progenitor cells in which several genetic and epigenetic aberrations have been described. Despite progressive advances in our understanding of the molecular biology of this disease, the outcome for most patients is poor. It is, therefore, necessary to develop more effective treatment strategies. Genetic aberrations affecting kinases have been widely studied in AML; however, the role of phosphatases remains underexplored. Inactivation of the tumor-suppressor protein phosphatase 2A (PP2A) is frequent in AML patients, making it a promising target for therapy. There are several PP2A inactivating mechanisms reported in this disease. Deregulation or specific post-translational modifications of PP2A subunits have been identified as a cause of PP2A malfunction, which lead to deregulation of proliferation or apoptosis pathways, depending on the subunit affected. Likewise, overexpression of either SET or cancerous inhibitor of protein phosphatase 2A, endogenous inhibitors of PP2A, is a recurrent event in AML that impairs PP2A activity, contributing to leukemogenesis progression. Interestingly, the anticancer activity of several PP2A-activating drugs (PADs) depends on interaction/sequestration of SET. Preclinical studies show that pharmacological restoration of PP2A activity by PADs effectively antagonizes leukemogenesis, and that these drugs have synergistic cytotoxic effects with conventional chemotherapy and kinase inhibitors, opening new possibilities for personalized treatment in AML patients, especially in cases with SET-dependent inactivation of PP2A. Here, we review the role of PP2A as a druggable tumor suppressor in AML.
Collapse
Affiliation(s)
- Elena Arriazu
- Hematology/Oncology Program, Center for Applied Medical Research (CIMA), University of Navarra , Pamplona , Spain
| | - Raffaella Pippa
- Centre for Gene Regulation and Expression, University of Dundee , Dundee , UK
| | - María D Odero
- Hematology/Oncology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain; Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| |
Collapse
|
40
|
Sangodkar J, Farrington C, McClinch K, Galsky MD, Kastrinsky DB, Narla G. All roads lead to PP2A: exploiting the therapeutic potential of this phosphatase. FEBS J 2016; 283:1004-24. [PMID: 26507691 PMCID: PMC4803620 DOI: 10.1111/febs.13573] [Citation(s) in RCA: 230] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 09/29/2015] [Accepted: 10/21/2015] [Indexed: 12/22/2022]
Abstract
Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase involved in the regulation of many cellular processes. A confirmed tumor suppressor protein, PP2A is genetically altered or functionally inactivated in many cancers highlighting a need for its therapeutic reactivation. In this review we discuss recent literature on PP2A: the elucidation of its structure and the functions of its subunits, and the identification of molecular lesions and post-translational modifications leading to its dysregulation in cancer. A final section will discuss the proteins and small molecules that modulate PP2A and how these might be used to target dysregulated forms of PP2A to treat cancers and other diseases.
Collapse
Affiliation(s)
- Jaya Sangodkar
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mt. Sinai, New York, NY, USA
| | - Caroline Farrington
- Department of Medicine and Institute for Transformative Molecular Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Kimberly McClinch
- Department of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Matthew D. Galsky
- Department of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - David B. Kastrinsky
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Goutham Narla
- Department of Medicine and Institute for Transformative Molecular Medicine, Case Western Reserve University, Cleveland, OH, USA
| |
Collapse
|
41
|
Liu T, Fang Y, Zhang H, Deng M, Gao B, Niu N, Yu J, Lee S, Kim J, Qin B, Xie F, Evans D, Wang L, Lou W, Lou Z. HEATR1 Negatively Regulates Akt to Help Sensitize Pancreatic Cancer Cells to Chemotherapy. Cancer Res 2015; 76:572-81. [PMID: 26676747 DOI: 10.1158/0008-5472.can-15-0671] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 10/11/2015] [Indexed: 01/06/2023]
Abstract
Elucidating mechanisms of chemoresistance is critical to improve cancer therapy, especially for the treatment of pancreatic ductal adenocarcinoma (PDAC). Genome-wide association studies have suggested the less studied gene HEAT repeat-containing protein 1 (HEATR1) as a possible determinant of cellular sensitivity to different chemotherapeutic drugs. In this study, we assessed this hypothesized link in PDAC, where HEATR1 expression is downregulated significantly. HEATR1 silencing in PDAC cells increased resistance to gemcitabine and other chemotherapeutics, where this effect was associated with increased AKT kinase phosphorylation at the Thr308 regulatory site. Mechanistically, HEATR1 enhanced cell responsiveness to gemcitabine by acting as a scaffold to facilitate interactions between AKT and the protein phosphatase PP2A, thereby promoting Thr308 dephosphorylation. Consistent with these findings, treatment with the AKT inhibitor triciribine sensitized HEATR1-depleted PDAC cells to gemcitabine, suggesting that this therapeutic combination may overcome gemcitabine resistance in patients with low HEATR1 expression. Clinically, we found that HEATR1 downregulation in PDAC patients was associated with increased AKT phosphorylation, poor response to tumor resection plus gemcitabine standard-of-care treatment, and shorter overall survival. Collectively, our findings establish HEATR1 as a novel regulator of AKT and a candidate predictive and prognostic indicator of drug responsiveness and outcome in PDAC patients.
Collapse
Affiliation(s)
- Tongzheng Liu
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - Yuan Fang
- Department of Pancreatic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Haoxing Zhang
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota. School of Life Sciences, Southwest University, Chongqing, China
| | - Min Deng
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - Bowen Gao
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - Nifang Niu
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - Jia Yu
- School of Life Sciences, Southwest University, Chongqing, China
| | - SeungBaek Lee
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - JungJin Kim
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - Bo Qin
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - Fang Xie
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - Debra Evans
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - Liewei Wang
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - Wenhui Lou
- Department of Pancreatic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China.
| | - Zhenkun Lou
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, Minnesota.
| |
Collapse
|
42
|
Ruvolo PP, Qiu Y, Coombes KR, Zhang N, Neeley ES, Ruvolo VR, Hail N, Borthakur G, Konopleva M, Andreeff M, Kornblau SM. Phosphorylation of GSK3α/β correlates with activation of AKT and is prognostic for poor overall survival in acute myeloid leukemia patients. BBA CLINICAL 2015; 4:59-68. [PMID: 26674329 PMCID: PMC4661707 DOI: 10.1016/j.bbacli.2015.07.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/07/2015] [Accepted: 07/10/2015] [Indexed: 12/18/2022]
Abstract
Background Acute myeloid leukemia (AML) patients with highly active AKT tend to do poorly. Cell cycle arrest and apoptosis are tightly regulated by AKT via phosphorylation of GSK3α and β isoforms which inactivates these kinases. In the current study we examine the prognostic role of AKT mediated GSK3 phosphorylation in AML. Methods We analyzed GSK3α/β phosphorylation by reverse phase protein analysis (RPPA) in a cohort of 511 acute myeloid leukemia (AML) patients. Levels of phosphorylated GSK3 were correlated with patient characteristics including survival and with expression of other proteins important in AML cell survival. Results High levels of p-GSK3α/β correlated with adverse overall survival and a lower incidence of complete remission duration in patients with intermediate cytogenetics, but not in those with unfavorable cytogenetics. Intermediate cytogenetic patients with FLT3 mutation also fared better respectively when p-GSK3α/β levels were lower. Phosphorylated GSK3α/β expression was compared and contrasted with that of 229 related cell cycle arrest and/or apoptosis proteins. Consistent with p-GSK3α/β as an indicator of AKT activation, RPPA revealed that p-GSK3α/β positively correlated with phosphorylation of AKT, BAD, and P70S6K, and negatively correlated with β-catenin and FOXO3A. PKCδ also positively correlated with p-GSK3α/β expression, suggesting crosstalk between the AKT and PKC signaling pathways in AML cells. Conclusions These findings suggest that AKT-mediated phosphorylation of GSK3α/β may be beneficial to AML cell survival, and hence detrimental to the overall survival of AML patients. Intrinsically, p-GSK3α/β may serve as an important adverse prognostic factor for a subset of AML patients. Phospho-GSK3 is prognostic for poor survival in a subset of AML patients. Phospho-GSK3 is a biomarker for active AKT in AML. AKT is a PKCδ kinase in AML cells.
Collapse
Affiliation(s)
- Peter P. Ruvolo
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
- Corresponding authors at: Department of Leukemia, Unit 448, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, United States.
| | - YiHua Qiu
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Kevin R. Coombes
- Bioinformatics and Computational Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States
- Department of Biomedical Informatics, Ohio State University Medical Center, Columbus, OH 43210, United States
| | - Nianxiang Zhang
- Bioinformatics and Computational Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States
| | - E. Shannon Neeley
- Department of Statistics, Brigham Young University, Provo, UT, United States
| | - Vivian R. Ruvolo
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Numsen Hail
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Gautam Borthakur
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Marina Konopleva
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Michael Andreeff
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Steven M. Kornblau
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
- Corresponding authors at: Department of Leukemia, Unit 448, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, United States.
| |
Collapse
|
43
|
RhoB loss induces Rac1-dependent mesenchymal cell invasion in lung cells through PP2A inhibition. Oncogene 2015; 35:1760-9. [DOI: 10.1038/onc.2015.240] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 05/12/2015] [Accepted: 05/22/2015] [Indexed: 12/13/2022]
|
44
|
Beca F, Pereira M, Cameselle-Teijeiro JF, Martins D, Schmitt F. Altered PPP2R2A and Cyclin D1 expression defines a subgroup of aggressive luminal-like breast cancer. BMC Cancer 2015; 15:285. [PMID: 25879784 PMCID: PMC4409761 DOI: 10.1186/s12885-015-1266-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/25/2015] [Indexed: 11/30/2022] Open
Abstract
Background PPP2R2A deletions were recently linked to a subgroup of luminal breast carcinoma (BC) that exhibits poor survival. This subgroup also exhibited amplification of a chromosome region containing the Cyclin D1 coding gene, CCND1. Therefore, we aimed to investigate whether a combination of PPP2R2A (B55α) and Cyclin D1 expression statuses evaluated by immunohistochemistry (IHC) could define a subgroup of luminal BC that exhibits poor survival. Methods First we conducted a retrospective cohort study using sequencing data from The Cancer Genome Atlas initiative to correlate PPP2R2A copy number alteration (CNA) status with its expression level and the corresponding overall survival (OS). Next, also using a retrospective cohort study design, we evaluated the PPP2R2A (B55α) expression levels by IHC in a total of 807 BC patients from two independent cohorts (discovery cohort n = 349 and validation cohort n = 458). Cyclin D1 expression was also evaluated, and the PPP2R2A (B55α)-/low/Cyclin D1high phenotype was evaluated as a predictor of disease-free survival (DFS) and OS in luminal-like BC patients. Results Deletions in the PPP2R2A gene strongly correlate with lower mRNA expression and poorer OS. PPP2R2A (B55α)-/low carcinomas have significantly shorter DFS and OS. Furthermore, in univariate analysis, the PPP2R2A (B55α)-/low/Cyclin D1high phenotype is significantly associated with poorer DFS and OS. In a multivariate analysis, the PPP2R2A (B55α)-/low/Cyclin D1high phenotype is significantly associated with poor DFS, thus defining a group of luminal-like BC with higher risk of relapse. Conclusion We demonstrate that BCs harboring PPP2R2A deletions are associated with worse OS. Moreover, this is the first study to demonstrate that the combination of altered PPP2R2A (B55α) and high Cyclin D1 expression by IHC defines a subgroup of luminal-like BC patients with a high risk of relapse and death. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1266-1) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Francisco Beca
- IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, Rua Dr, Roberto Frias, s/n, 4200-465 Porto, Porto, Portugal. .,Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA, 02215-5450, USA.
| | - Miguel Pereira
- Division of Surgical Oncology, Department of Surgery, Massachusetts General Hospital Cancer Center, 55 Fruit St, Boston, MA, 02114, USA.
| | | | - Diana Martins
- IBMC - Instituto de Biologia Molecular e Celular da Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal.
| | - Fernando Schmitt
- Department of Pathology and Medicine, Laboratorie National de Sante 1, Rue Louis Reche, L-3555, Dudelange, Luxembourg.
| |
Collapse
|
45
|
Kiely M, Kiely PA. PP2A: The Wolf in Sheep's Clothing? Cancers (Basel) 2015; 7:648-69. [PMID: 25867001 PMCID: PMC4491676 DOI: 10.3390/cancers7020648] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/16/2015] [Accepted: 03/23/2015] [Indexed: 12/21/2022] Open
Abstract
Protein Phosphatase 2A (PP2A) is a major serine/threonine phosphatase in cells. It consists of a catalytic subunit (C), a structural subunit (A), and a regulatory/variable B-type subunit. PP2A has a critical role to play in homeostasis where its predominant function is as a phosphatase that regulates the major cell signaling pathways in cells. Changes in the assembly, activity and substrate specificity of the PP2A holoenzyme have a direct role in disease and are a major contributor to the maintenance of the transformed phenotype in cancer. We have learned a lot about how PP2A functions from specific mutations that disrupt the core assembly of PP2A and from viral proteins that target PP2A and inhibit its effect as a phosphatase. This prompted various studies revealing that restoration of PP2A activity benefits some cancer patients. However, our understanding of the mechanism of action of this is limited because of the complex nature of PP2A holoenzyme assembly and because it acts through a wide variety of signaling pathways. Information on PP2A is also conflicting as there are situations whereby inactivation of PP2A induces apoptosis in many cancer cells. In this review we discuss this relationship and we also address many of the pertinent and topical questions that relate to novel therapeutic strategies aimed at altering PP2A activity.
Collapse
Affiliation(s)
- Maeve Kiely
- Department of Life Sciences, and Materials and Surface Science Institute, University of Limerick, Limerick 78666, Ireland.
| | - Patrick A Kiely
- Department of Life Sciences, and Materials and Surface Science Institute, University of Limerick, Limerick 78666, Ireland.
- Stokes Institute, University of Limerick 78666, Limerick, Ireland.
| |
Collapse
|
46
|
Ruvolo PP. The Interplay between PP2A and microRNAs in Leukemia. Front Oncol 2015; 5:43. [PMID: 25750899 PMCID: PMC4335100 DOI: 10.3389/fonc.2015.00043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 02/05/2015] [Indexed: 12/19/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase family whose members have been implicated in tumor suppression in many cancer models. In many cancers, loss of PP2A activity has been associated with tumorigenesis and drug resistance. Loss of PP2A results in failure to turn off survival signaling cascades that drive drug resistance such as those regulated by protein kinase B. PP2A is responsible for modulating function and controlling expression of tumor suppressors such as p53 and oncogenes such as BCL2 and MYC. Thus, PP2A has diverse functions regulating cell survival. The importance of microRNAs (miRs) is emerging in cancer biology. A role for miR regulation of PP2A is not well understood; however, recent studies suggest a number of clinically significant miRs such as miR-155 and miR-19 may include PP2A targets. We have recently found that a PP2A B subunit (B55α) can regulate a number of miRs in acute myeloid leukemia cells. The identification of a miR/PP2A axis represents a novel regulatory pathway in cellular homeostasis. The ability of miRs to suppress specific PP2A targets and for PP2A to control such miRs can add an extra level of control in signaling that could be used as a rheostat for many signaling cascades that maintain cellular homeostasis. As such, loss of PP2A or expression of miRs relevant for PP2A function could promote tumorigenesis or at least result in drug resistance. In this review, we will cover the current state of miR regulation of PP2A with a focus on leukemia. We will also briefly discuss what is known of PP2A regulation of miR expression.
Collapse
Affiliation(s)
- Peter P Ruvolo
- Department of Leukemia, University of Texas MD Anderson Cancer Center , Houston, TX , USA
| |
Collapse
|
47
|
Haesen D, Sents W, Lemaire K, Hoorne Y, Janssens V. The Basic Biology of PP2A in Hematologic Cells and Malignancies. Front Oncol 2014; 4:347. [PMID: 25566494 PMCID: PMC4263090 DOI: 10.3389/fonc.2014.00347] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 11/20/2014] [Indexed: 12/30/2022] Open
Abstract
Reversible protein phosphorylation plays a crucial role in regulating cell signaling. In normal cells, phosphoregulation is tightly controlled by a network of protein kinases counterbalanced by several protein phosphatases. Deregulation of this delicate balance is widely recognized as a central mechanism by which cells escape external and internal self-limiting signals, eventually resulting in malignant transformation. A large fraction of hematologic malignancies is characterized by constitutive or unrestrained activation of oncogenic kinases. This is in part achieved by activating mutations, chromosomal rearrangements, or constitutive activation of upstream kinase regulators, in part by inactivation of their anti-oncogenic phosphatase counterparts. Protein phosphatase 2A (PP2A) represents a large family of cellular serine/threonine phosphatases with suspected tumor suppressive functions. In this review, we highlight our current knowledge about the complex structure and biology of these phosphatases in hematologic cells, thereby providing the rationale behind their diverse signaling functions. Eventually, this basic knowledge is a key to truly understand the tumor suppressive role of PP2A in leukemogenesis and to allow further rational development of therapeutic strategies targeting PP2A.
Collapse
Affiliation(s)
- Dorien Haesen
- Laboratory of Protein Phosphorylation and Proteomics, Department Cellular and Molecular Medicine, University of Leuven , Leuven , Belgium
| | - Ward Sents
- Laboratory of Protein Phosphorylation and Proteomics, Department Cellular and Molecular Medicine, University of Leuven , Leuven , Belgium
| | - Katleen Lemaire
- Gene Expression Unit, Department Cellular and Molecular Medicine, University of Leuven , Leuven , Belgium
| | - Yana Hoorne
- Laboratory of Protein Phosphorylation and Proteomics, Department Cellular and Molecular Medicine, University of Leuven , Leuven , Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation and Proteomics, Department Cellular and Molecular Medicine, University of Leuven , Leuven , Belgium
| |
Collapse
|
48
|
Nifoussi SK, Ratcliffe NR, Ornstein DL, Kasof G, Strack S, Craig RW. Inhibition of protein phosphatase 2A (PP2A) prevents Mcl-1 protein dephosphorylation at the Thr-163/Ser-159 phosphodegron, dramatically reducing expression in Mcl-1-amplified lymphoma cells. J Biol Chem 2014; 289:21950-9. [PMID: 24939844 DOI: 10.1074/jbc.m114.587873] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Abundant, sustained expression of prosurvival Mcl-1 is an important determinant of viability and drug resistance in cancer cells. The Mcl-1 protein contains PEST sequences (enriched in proline, glutamic acid, serine, and threonine) and is normally subject to rapid turnover via multiple different pathways. One of these pathways involves a phosphodegron in the PEST region, where Thr-163 phosphorylation primes for Ser-159 phosphorylation by glycogen synthase kinase-3. Turnover via this phosphodegron-targeted pathway is reduced in Mcl-1-overexpressing BL41-3 Burkitt lymphoma and other cancer cells; turnover is further slowed in the presence of phorbol ester-induced ERK activation, resulting in Mcl-1 stabilization and an exacerbation of chemoresistance. The present studies focused on Mcl-1 dephosphorylation, which was also found to profoundly influence turnover. Exposure of BL41-3 cells to an inhibitor of protein phosphatase 2A (PP2A), okadaic acid, resulted in a rapid increase in phosphorylation at Thr-163 and Ser-159, along with a precipitous decrease in Mcl-1 expression. The decline in Mcl-1 expression preceded the appearance of cell death markers and was not slowed in the presence of phorbol ester. Upon exposure to calyculin A, which also potently inhibits PP2A, versus tautomycin, which does not, only the former increased Thr-163/Ser-159 phosphorylation and decreased Mcl-1 expression. Mcl-1 co-immunoprecipitated with PP2A upon transfection into CHO cells, and PP2A/Aα knockdown recapitulated the increase in Mcl-1 phosphorylation and decrease in expression. In sum, inhibition of PP2A prevents Mcl-1 dephosphorylation and results in rapid loss of this prosurvival protein in chemoresistant cancer cells.
Collapse
Affiliation(s)
- Shanna K Nifoussi
- From the Departments of Pharmacology and Toxicology and the Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766
| | - Nora R Ratcliffe
- Pathology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, the Veterans Affairs Medical Center, White River Junction, Vermont 05001
| | - Deborah L Ornstein
- Pathology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Gary Kasof
- Cell Signaling Technology, Danvers, Massachusetts 01923, and
| | - Stefan Strack
- Department of Pharmacology, The University of Iowa, Iowa City, Iowa 52242
| | - Ruth W Craig
- From the Departments of Pharmacology and Toxicology and the Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766,
| |
Collapse
|
49
|
The protein phosphatase 2A regulatory subunit B55α is a modulator of signaling and microRNA expression in acute myeloid leukemia cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1969-77. [PMID: 24858343 DOI: 10.1016/j.bbamcr.2014.05.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 01/22/2023]
Abstract
We recently discovered that the protein phosphatase 2A (PP2A) B55α subunit (PPP2R2A) is under-expressed in primary blast cells and is unfavorable for remission duration in AML patients. In this study, reverse phase protein analysis (RPPA) of 230 proteins in 511 AML patient samples revealed a strong correlation of B55α with a number of proteins including MYC, PKC α, and SRC. B55α suppression in OCI-AML3 cells by shRNA demonstrated that the B subunit is a PKCα phosphatase. B55α does not target SRC, but rather the kinase suppresses protein expression of the B subunit. Finally, the correlation between B55α and MYC levels reflected a complex stoichiometric competition between B subunits. Loss of B55α in OCI-AML3 cells did not change global PP2A activity and the only isoform that is induced is the one containing B56α. In cells containing B55α shRNA, MYC was suppressed with concomitant induction of the competing B subunit B56α (PPP2R5A). A recent study determined that FTY-720, a drug whose action involves the activation of PP2A, resulted in the induction of B55α In AML cells, and a reduction of the B subunit rendered these cells resistant to FTY-720. Finally, reduction of the B subunit resulted in an increase in the expression of miR-191-5p and a suppression of miR-142-3p. B55α regulation of these miRs was intriguing as high levels of miR-191 portend poor survival in AML, and miR-142-3p is mutated in 2% of AML patient samples. In summary, the suppression of B55α activates signaling pathways that could support leukemia cell survival.
Collapse
|
50
|
Liu Q, Turner KM, Alfred Yung WK, Chen K, Zhang W. Role of AKT signaling in DNA repair and clinical response to cancer therapy. Neuro Oncol 2014; 16:1313-23. [PMID: 24811392 DOI: 10.1093/neuonc/nou058] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Effective cancer treatment has been limited by the emergence of resistant cancer cells. The results of many studies indicate that AKT activation plays an important role in the acquisition of resistance to anticancer therapy. AKT is a critical effector serine/threonine kinase in the receptor tyrosine kinase/phosphatase and tensin homolog/phospho-inositide 3-kinase pathway and controls a myriad of cellular functions. Activation of AKT not only supports tumor growth and progression but also contributes to tumor-cell evasion of the cytotoxic effects of cancer therapy through many avenues including the promotion of anti-apoptosis, proliferation, and migration and regulation of the cell cycle. Accumulating evidence has implicated AKT as a direct participant in the DNA damage response and repair induced by commonly used genotoxic agents. In this review, we discuss the molecular mechanisms by which genotoxic agents activate AKT and therefore contribute to resistance to cancer therapeutics, with particular emphasis on DNA repair.
Collapse
Affiliation(s)
- Qun Liu
- Department of Neuro-Oncology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (Q.L.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (K.M.T., W.Z.); Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (W.K.A.Y.); Department of Epidemiology and Biostatistics, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (K.C.)
| | - Kristen M Turner
- Department of Neuro-Oncology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (Q.L.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (K.M.T., W.Z.); Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (W.K.A.Y.); Department of Epidemiology and Biostatistics, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (K.C.)
| | - W K Alfred Yung
- Department of Neuro-Oncology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (Q.L.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (K.M.T., W.Z.); Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (W.K.A.Y.); Department of Epidemiology and Biostatistics, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (K.C.)
| | - Kexin Chen
- Department of Neuro-Oncology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (Q.L.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (K.M.T., W.Z.); Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (W.K.A.Y.); Department of Epidemiology and Biostatistics, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (K.C.)
| | - Wei Zhang
- Department of Neuro-Oncology, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (Q.L.); Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (K.M.T., W.Z.); Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (W.K.A.Y.); Department of Epidemiology and Biostatistics, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China (K.C.)
| |
Collapse
|