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He K, Xie CZ, Li Y, Chen ZZ, Xu SH, Huang SQ, Yang JG, Wei ZQ, Peng XD. Dopamine and cyclic adenosine monophosphate-regulated phosphoprotein with an apparent Mr of 32000 promotes colorectal cancer growth. World J Gastrointest Oncol 2023; 15:1936-1950. [DOI: 10.4251/wjgo.v15.i11.1936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/29/2023] [Accepted: 07/29/2023] [Indexed: 11/15/2023] Open
Abstract
BACKGROUND Dopamine and cyclic adenosine monophosphate (cAMP)-regulated phosphoprotein with an apparent Mr of 32000 (DARPP-32) is a protein that is involved in regulating dopamine and cAMP signaling pathways in the brain. However, recent studies have shown that DARPP-32 is also expressed in other tissues, including colorectal cancer (CRC), where its function is not well understood.
AIM To explore the effect of DARPP-32 on CRC progression.
METHODS The expression levels of DARPP-32 were assessed in CRC tissues using both quantitative polymerase chain reaction and immunohistochemistry assays. The proliferative capacity of CRC cell lines was evaluated with Cell Counting Kit-8 and 5-ethynyl-2’-deoxyuridine assays, while apoptosis was measured by flow cytometry. The migratory and invasive potential of CRC cell lines were determined using wound healing and transwell chamber assays. In vivo studies involved monitoring the growth rate of xenograft tumors. Finally, the underlying molecular mechanism of DARPP-32 was investigated through RNA-sequencing and western blot analyses.
RESULTS DARPP-32 was frequently upregulated in CRC and associated with abnormal clinicopathological features in CRC. Overexpression of DARPP-32 was shown to promote cancer cell proliferation, migration, and invasion and reduce apoptosis. DARPP-32 knockdown resulted in the opposite functional effects. Mechanistically, DARPP-32 may regulate the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway in order to carry out its biological function.
CONCLUSION DARPP-32 promotes CRC progression via the PI3K/AKT signaling pathway.
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Affiliation(s)
- Kuan He
- Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
| | - Chao-Zheng Xie
- Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
| | - Ya Li
- Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
| | - Zhen-Zhou Chen
- Gastrointestinal Surgery, The Third Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
| | - Shi-Hao Xu
- Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
| | - Si-Qi Huang
- Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
| | - Jian-Guo Yang
- Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
| | - Zheng-Qiang Wei
- Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
| | - Xu-Dong Peng
- Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400000, China
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2
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Nussinov R, Liu Y, Zhang W, Jang H. Protein conformational ensembles in function: roles and mechanisms. RSC Chem Biol 2023; 4:850-864. [PMID: 37920394 PMCID: PMC10619138 DOI: 10.1039/d3cb00114h] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 09/02/2023] [Indexed: 11/04/2023] Open
Abstract
The sequence-structure-function paradigm has dominated twentieth century molecular biology. The paradigm tacitly stipulated that for each sequence there exists a single, well-organized protein structure. Yet, to sustain cell life, function requires (i) that there be more than a single structure, (ii) that there be switching between the structures, and (iii) that the structures be incompletely organized. These fundamental tenets called for an updated sequence-conformational ensemble-function paradigm. The powerful energy landscape idea, which is the foundation of modernized molecular biology, imported the conformational ensemble framework from physics and chemistry. This framework embraces the recognition that proteins are dynamic and are always interconverting between conformational states with varying energies. The more stable the conformation the more populated it is. The changes in the populations of the states are required for cell life. As an example, in vivo, under physiological conditions, wild type kinases commonly populate their more stable "closed", inactive, conformations. However, there are minor populations of the "open", ligand-free states. Upon their stabilization, e.g., by high affinity interactions or mutations, their ensembles shift to occupy the active states. Here we discuss the role of conformational propensities in function. We provide multiple examples of diverse systems, including protein kinases, lipid kinases, and Ras GTPases, discuss diverse conformational mechanisms, and provide a broad outlook on protein ensembles in the cell. We propose that the number of molecules in the active state (inactive for repressors), determine protein function, and that the dynamic, relative conformational propensities, rather than the rigid structures, are the hallmark of cell life.
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Affiliation(s)
- Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research Frederick MD 21702 USA
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University Tel Aviv 69978 Israel
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
| | - Yonglan Liu
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
| | - Wengang Zhang
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research Frederick MD 21702 USA
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
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3
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Vogt PK, Hart JR, Yang S, Zhou Q, Yang D, Wang MW. Structural and mechanistic insights provided by single particle cryo-EM analysis of phosphoinositide 3-kinase (PI3Kα). Biochim Biophys Acta Rev Cancer 2023; 1878:188947. [PMID: 37394020 PMCID: PMC10530483 DOI: 10.1016/j.bbcan.2023.188947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/27/2023] [Accepted: 06/27/2023] [Indexed: 07/04/2023]
Abstract
Recent cryo-electron microscopic (cryo-EM) investigations have succeeded in the analysis of various structural conformations and functional states of PI3Kα, a dimer consisting of the catalytic subunit p110α and the regulatory subunit p85α of class IA of phosphoinositide 3-kinase. High resolution structures have been obtained of the unliganded and of BYL-719-bound PI3Kα. The latter provides information on excessively flexible domains of p85α that are then further analyzed with nanobodies and CXMS (chemical cross-linking, digestion and mass spectrometry). Analysis of p110α helical and kinase domain mutations reveals mutant-specific features that can be linked to the gain of function in enzymatic and signaling activities.
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Affiliation(s)
- Peter K Vogt
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America.
| | - Jonathan R Hart
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America
| | - Su Yang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America
| | - Qingtong Zhou
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Dehua Yang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ming-Wei Wang
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; Research Center for Deepsea Bioresources, Sanya 572025, China; Department of Chemistry, School of Science, The University of Tokyo, Tokyo 113-0033, Japan
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4
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Freitas de Sousa FJ, Nunes Azevedo FF, Santos de Oliveira FL, Vieira Carletti J, Freire VN, Zanatta G. Quantum biochemistry description of PI3Kα enzyme bound to selective inhibitors. J Biomol Struct Dyn 2023:1-11. [PMID: 37632299 DOI: 10.1080/07391102.2023.2251063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023]
Abstract
The PI3K class I is composed of four PI3K isoforms that serve as regulatory enzymes governing cellular metabolism, proliferation, and survival. The hyperactivation of PI3Kα is observed in various types of cancer and is linked to poor prognosis. Unfortunately, the development inhibitors selectively targeting one of the isoforms remains challenging, with only few agents in clinical use. The main difficulty arises from the high conservation among residues at the ATP-binding pocket across isoforms, which also serves as target pocket for inhibitors. In this work, molecular dynamics and quantum calculations were performed to investigate the molecular features guiding the binding of selective inhibitors, alpelisib and GDC-0326, into the ATP-binding pocket of PI3Kα. While molecular dynamics allowed crystallographic coordinates to relax, the interaction eergy between each amino acid residues and inhibitors was obtained by combining the Molecular Fractionation with Conjugated Caps scheme with Density Functional Theory calculations. In addition, the atomic charge of ligands in the bound and unbound (free) was calculated. Results indicated that the most relevant residues for the binding of alpelisib are Ile932, Glu859, Val851, Val850, Tyr836, Met922, Ile800, and Ile848, while the most important residues for the binding of GDC-0326 are Ile848, Ile800, Ile932, Gln859, Glu849, and Met922. In addition, residues Trp780, Ile800, Tyr836, Ile848, Gln859 Val850, Val851, Ile932 and Met922 are common hotspots for both inhibitors. Overall, the results from this work contribute to improving the understanding of the molecular mechanisms controlling selectivity and highlight important interactions to be considered during the rational design of new agents.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
| | | | | | | | | | - Geancarlo Zanatta
- Department of Biochemistry and Molecular Biology, Federal University of Ceará, Fortaleza, Brazil
- Department of Biophysics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
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Nussinov R, Tsai CJ, Jang H. A New View of Activating Mutations in Cancer. Cancer Res 2022; 82:4114-4123. [PMID: 36069825 PMCID: PMC9664134 DOI: 10.1158/0008-5472.can-22-2125] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/16/2022] [Accepted: 09/01/2022] [Indexed: 12/14/2022]
Abstract
A vast effort has been invested in the identification of driver mutations of cancer. However, recent studies and observations call into question whether the activating mutations or the signal strength are the major determinant of tumor development. The data argue that signal strength determines cell fate, not the mutation that initiated it. In addition to activating mutations, factors that can impact signaling strength include (i) homeostatic mechanisms that can block or enhance the signal, (ii) the types and locations of additional mutations, and (iii) the expression levels of specific isoforms of genes and regulators of proteins in the pathway. Because signal levels are largely decided by chromatin structure, they vary across cell types, states, and time windows. A strong activating mutation can be restricted by low expression, whereas a weaker mutation can be strengthened by high expression. Strong signals can be associated with cell proliferation, but too strong a signal may result in oncogene-induced senescence. Beyond cancer, moderate signal strength in embryonic neural cells may be associated with neurodevelopmental disorders, and moderate signals in aging may be associated with neurodegenerative diseases, like Alzheimer's disease. The challenge for improving patient outcomes therefore lies in determining signaling thresholds and predicting signal strength.
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Affiliation(s)
- Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Cancer Innovation Laboratory, NCI, Frederick, Maryland
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Chung-Jung Tsai
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Cancer Innovation Laboratory, NCI, Frederick, Maryland
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Cancer Innovation Laboratory, NCI, Frederick, Maryland
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6
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Synthesis, in-silico, and in-vitro study of novel chloro methylquinazolinones as PI3K-δ inhibitors, cytotoxic agents. ARAB J CHEM 2022. [DOI: 10.1016/j.arabjc.2021.103614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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7
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Rascio F, Spadaccino F, Rocchetti MT, Castellano G, Stallone G, Netti GS, Ranieri E. The Pathogenic Role of PI3K/AKT Pathway in Cancer Onset and Drug Resistance: An Updated Review. Cancers (Basel) 2021; 13:3949. [PMID: 34439105 PMCID: PMC8394096 DOI: 10.3390/cancers13163949] [Citation(s) in RCA: 121] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 07/30/2021] [Indexed: 12/12/2022] Open
Abstract
The PI3K/AKT pathway is one of the most frequently over-activated intracellular pathways in several human cancers. This pathway, acting on different downstream target proteins, contributes to the carcinogenesis, proliferation, invasion, and metastasis of tumour cells. A multi-level impairment, involving mutation and genetic alteration, aberrant regulation of miRNAs sequences, and abnormal phosphorylation of cascade factors, has been found in multiple cancer types. The deregulation of this pathway counteracts common therapeutic strategies and contributes to multidrug resistance. In this review, we underline the involvement of this pathway in patho-physiological cell survival mechanisms, emphasizing its key role in the development of drug resistance. We also provide an overview of the potential inhibition strategies currently available.
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Affiliation(s)
- Federica Rascio
- Nephrology Dialysis and Transplantation Unit, Advanced Research Center on Kidney Aging (A.R.K.A.), Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy; (G.C.); (G.S.)
| | - Federica Spadaccino
- Clinical Pathology Unit, Advanced Research Center on Kidney Aging (A.R.K.A.), Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy; (F.S.); (G.S.N.); (E.R.)
| | - Maria Teresa Rocchetti
- Cell Biology Unit, Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy;
| | - Giuseppe Castellano
- Nephrology Dialysis and Transplantation Unit, Advanced Research Center on Kidney Aging (A.R.K.A.), Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy; (G.C.); (G.S.)
| | - Giovanni Stallone
- Nephrology Dialysis and Transplantation Unit, Advanced Research Center on Kidney Aging (A.R.K.A.), Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy; (G.C.); (G.S.)
| | - Giuseppe Stefano Netti
- Clinical Pathology Unit, Advanced Research Center on Kidney Aging (A.R.K.A.), Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy; (F.S.); (G.S.N.); (E.R.)
| | - Elena Ranieri
- Clinical Pathology Unit, Advanced Research Center on Kidney Aging (A.R.K.A.), Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy; (F.S.); (G.S.N.); (E.R.)
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8
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Roskoski R. Properties of FDA-approved small molecule phosphatidylinositol 3-kinase inhibitors prescribed for the treatment of malignancies. Pharmacol Res 2021; 168:105579. [PMID: 33774181 DOI: 10.1016/j.phrs.2021.105579] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 02/07/2023]
Abstract
The discovery of the phosphatidylinositol 3-kinase (PI 3-kinase) pathway was a major advance in understanding eukaryotic signal transduction. The high frequency of PI 3-kinase pathway mutations in many cancers stimulated the development of drugs targeting these oncogenic mutants. The PI 3-kinases are divided into three classes and Class I PI 3-kinases, which catalyze the phosphorylation of phosphatidylinositol-4,5-bisphosphate (PI-4,5-P2) to generate phosphatidylinositol-3,4,5-trisphosphate (PIP3), are the main subject of this review. The class I PI 3-kinases are made up of p110α, p110β, p110δ, and p110γ catalytic subunits. These catalytic subunits are constitutively bound to regulatory subunits (p85α, p85β, p55γ, p101, and p87 proteins). The p85/p55 regulatory subunits heterodimerize with p110α or p110δ thereby forming complexes that are regulated chiefly by receptor protein-tyrosine kinases. The p101 and p87 subunits heterodimerize with p110γ to form complexes that are regulated mainly by G protein-coupled receptors (GPCRs). Complexes containing the p110β subunit are activated by receptor protein-tyrosine kinases as well as GPCRs. Following the generation of PIP3, the AKT and mTOR protein-serine/threonine kinases are activated leading to cell growth, proliferation, and survival. Like protein kinases, the PI 3-kinase domains consist of a bilobed structure connected by a hinge-linker segment. ATP and most PI 3-kinase and protein kinase inhibitors form hydrogen bonds with hinge residues. The small and large lobes of PI 3-kinases and protein kinases have a very similar three-dimensional structure called the protein kinase fold. Both PI 3-kinases and eukaryotic protein kinases possess an activation segment that begins with a DFG triad (Asp-Phe-Gly); the activation segment of protein kinases usually ends with an APE (Ala-Pro-Glu) signature while that of PI 3-kinases ends with a PFxLT (Pro-Phe-Xxx-Leu-Thr) signature. Dormant PI 3-kinases have a collapsed activation loop and active PI 3-kinases have an extended activation loop. The distance between the α-carbon atom of the DFG-D residue at the beginning of the activation loop and that of the PFxLT-F residue at the end of the activation loop in dormant PI 3-kinases is about 13 Å; this distance in active PI 3-kinases is about 18 Å. The protein kinase catalytic loop has an HRD (His-Arg-Asp) signature while that of the PI 3-kinases reverses the order with a DRH triad. Alpelisib is an orally effective FDA-approved PI 3-kinase-α inhibitor used for the treatment of breast cancer. Copanlisib, duvelisib, idelalisib, and umbralisib are PI 3-kinase-δ inhibitors that are approved for the third-line treatment of follicular lymphomas and other hematological disorders. Copanlisib is also a potent inhibitor of PI 3-kinase-α. Of the five approved drugs, all are orally bioavailable except copanlisib. Idelalisib interacts with the active conformation of PI 3-kinase-δ and is classified as a type I inhibitor. Alpelisib and copanlisib interact with inactive PI 3-kinase-α and PI 3-kinase-γ, respectively, and are classified as a type I½ antagonists. Except for umbralisib with a molecular weight of 571.5, all five drugs conform to the Lipinski rule of five for oral effectiveness. Copanlisib, however, must be given intravenously. Alpelisib and copanlisib inhibit PI 3-kinase-α, which is involved in insulin signaling, and both drugs promote insulin-resistance and produce hyperglycemia. The five FDA-approved PI 3-kinase inhibitors produce significant on-target toxicities, more so than many approved protein kinase antagonists. The development of PI 3-kinase inhibitors with fewer toxicities is an important long-term therapeutic goal.
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Affiliation(s)
- Robert Roskoski
- Blue Ridge Institute for Medical Research, 3754 Brevard Road, Suite 116, Box 19, Horse Shoe, NC 28742-8814, United States.
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9
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Zhang M, Jang H, Nussinov R. PI3K Driver Mutations: A Biophysical Membrane-Centric Perspective. Cancer Res 2021; 81:237-247. [PMID: 33046444 PMCID: PMC7855922 DOI: 10.1158/0008-5472.can-20-0911] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/24/2020] [Accepted: 10/07/2020] [Indexed: 11/16/2022]
Abstract
Ras activates its effectors at the membrane. Active PI3Kα and its associated kinases/phosphatases assemble at membrane regions enriched in signaling lipids. In contrast, the Raf kinase domain extends into the cytoplasm and its assembly is away from the crowded membrane surface. Our structural membrane-centric outlook underscores the spatiotemporal principles of membrane and signaling lipids, which helps clarify PI3Kα activation. Here we focus on mechanisms of activation driven by PI3Kα driver mutations, spotlighting the PI3Kα double (multiple) activating mutations. Single mutations can be potent, but double mutations are stronger: their combination is specific, a single strong driver cannot fully activate PI3K, and two weak drivers may or may not do so. In contrast, two strong drivers may successfully activate PI3K, where one, for example, H1047R, modulates membrane interactions facilitating substrate binding at the active site (km) and the other, for example, E542K and E545K, reduces the transition state barrier (ka), releasing autoinhibition by nSH2. Although mostly unidentified, weak drivers are expected to be common, so we ask here how common double mutations are likely to be and why PI3Kα with double mutations responds effectively to inhibitors. We provide a structural view of hotspot and weak driver mutations in PI3Kα activation, explain their mechanisms, compare these with mechanisms of Raf activation, and point to targeting cell-specific, chromatin-accessible, and parallel (or redundant) pathways to thwart the expected emergence of drug resistance. Collectively, our biophysical outlook delineates activation and highlights the challenges of drug resistance.
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Affiliation(s)
- Mingzhen Zhang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, Maryland
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, Maryland
| | - Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, Maryland.
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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10
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Methot JL, Achab A, Christopher M, Zhou H, McGowan MA, Trotter BW, Fradera X, Lesburg CA, Goldenblatt P, Hill A, Chen D, Otte KM, Augustin M, Shah S, Katz JD. Optimization of Versatile Oxindoles as Selective PI3Kδ Inhibitors. ACS Med Chem Lett 2020; 11:2461-2469. [PMID: 33335668 DOI: 10.1021/acsmedchemlett.0c00441] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022] Open
Abstract
The 3,3-disubstituted oxindole moiety is a versatile and rigid three-dimensionally shaped scaffold. When engineered with a purine hinge-binding core, exceptionally selective PI3Kδ kinase inhibitors were discovered by exploiting small differences in isoform selectivity pockets. Crystal structures of early lead 2f bound to PI3Kδ and PI3Kα helped rationalize the high selectivity observed with 2f. By attenuating the lypophilicity and metabolic liabilities of an oxindole moiety, we improved the preclinical species PK and solubility and reduced adenosine uptake activity. The excellent potency and kinome selectivity of 7-azaoxindole 4d and spirooxindole 5d, together with a low plasma clearance and good half-life in rat and dog, supported a low once-daily predicted human dose.
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11
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Quercetin Improving Lipid Metabolism by Regulating Lipid Metabolism Pathway of Ileum Mucosa in Broilers. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:8686248. [PMID: 33014279 PMCID: PMC7520004 DOI: 10.1155/2020/8686248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/28/2020] [Accepted: 08/29/2020] [Indexed: 02/06/2023]
Abstract
This study is aimed at evaluating the regulatory mechanism of quercetin on lipid metabolism in the ileum of broilers to better understand these pathways decreasing abdominal fat. 480 chickens were randomly divided into 4 groups (control, 0.02% quercetin, 0.04% quercetin, and 0.06% quercetin). Breast muscle, thigh muscle, and abdominal fat pad were removed and weighed at 42 d of age. Serum was obtained by centrifuging blood samples from the jugular vein (10 ml) to determine high-density lipoprotein (HDL), total cholesterol (TC), low-density lipoprotein (LDL), triglyceride (TG), leptin, and adiponectin using ELISA. About 5 g of the ileum was harvested and immediately frozen in liquid nitrogen for RNA-seq. Then, the confirmation of RNA-seq results by the Real-Time Quantitative PCR (RT-qPCR) method was evaluated using Pearson's correlation. Compared with control, abdominal fat percentage was significantly decreased with increasing quercetin supplementation, and the best result was obtained at 0.06% dietary quercetin supplementation (P < 0.01). Breast muscle percentage was significantly decreased at 0.02% quercetin (P < 0.01), and thigh muscle percentage tended to increase (P = 0.078). Meanwhile, 0.04% and 0.06% quercetin significantly decreased TG (P < 0.01), TC (P < 0.01), and LDL content (P < 0.05) in serum. Serum leptin and adiponectin contents were significantly increased by 0.04% and 0.06% dietary quercetin supplementation, compared with the control (P < 0.01). Analyses of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database were used to identify differently expressed genes and lipid metabolism pathways. Quercetin decreased abdominal fat percentage through regulating fat digestion and absorption, glycerophospholipid metabolism, AMPK signaling pathway, fatty acid degradation, and cholesterol metabolism.
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12
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Xu F, Na L, Li Y, Chen L. Roles of the PI3K/AKT/mTOR signalling pathways in neurodegenerative diseases and tumours. Cell Biosci 2020; 10:54. [PMID: 32266056 PMCID: PMC7110906 DOI: 10.1186/s13578-020-00416-0] [Citation(s) in RCA: 356] [Impact Index Per Article: 89.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 03/26/2020] [Indexed: 02/06/2023] Open
Abstract
The PI3 K/AKT/mTOR signalling pathway plays an important role in the regulation of signal transduction and biological processes such as cell proliferation, apoptosis, metabolism and angiogenesis. Compared with those of other signalling pathways, the components of the PI3K/AKT/mTOR signalling pathway are complicated. The regulatory mechanisms and biological functions of the PI3K/AKT/mTOR signalling pathway are important in many human diseases, including ischaemic brain injury, neurodegenerative diseases, and tumours. PI3K/AKT/mTOR signalling pathway inhibitors include single-component and dual inhibitors. Numerous PI3K inhibitors have exhibited good results in preclinical studies, and some have been clinically tested in haematologic malignancies and solid tumours. In this review, we briefly summarize the results of research on the PI3K/AKT/mTOR pathway and discuss the structural composition, activation, communication processes, regulatory mechanisms and biological functions of the PI3K/AKT/mTOR signalling pathway in the pathogenesis of neurodegenerative diseases and tumours.
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Affiliation(s)
- Fei Xu
- Department of Microbiology and Immunology, Shanghai University of Medicine & Health Sciences, 279 Zhouzhu Rd, Shanghai, 201318 China
- Collaborative Innovation Center of Shanghai University of Medicine & Health Sciences, Shanghai, 201318 China
| | - Lixin Na
- Collaborative Innovation Center of Shanghai University of Medicine & Health Sciences, Shanghai, 201318 China
- Department of Inspection and Quarantine, Shanghai University of Medicine & Health Sciences, Shanghai, 201318 China
| | - Yanfei Li
- Department of Inspection and Quarantine, Shanghai University of Medicine & Health Sciences, Shanghai, 201318 China
| | - Linjun Chen
- Department of Inspection and Quarantine, Shanghai University of Medicine & Health Sciences, Shanghai, 201318 China
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13
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Sharma J, Bhardwaj V, Purohit R. Structural Perturbations due to Mutation (H1047R) in Phosphoinositide-3-kinase (PI3Kα) and Its Involvement in Oncogenesis: An in Silico Insight. ACS OMEGA 2019; 4:15815-15823. [PMID: 31592171 PMCID: PMC6776984 DOI: 10.1021/acsomega.9b01439] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 07/23/2019] [Indexed: 05/03/2023]
Abstract
PI3Kα is a heterodimer protein consisting of two subunits (p110α and p85α) which promotes various signaling pathways. Oncogenic mutation in the catalytic subunit p110α of PI3Kα at the 1047 position in the kinase domain substitutes the histidine with arginine. This mutation brings about conformational transitions in the protein complex. These transitions expose the membrane binding region of PI3Kα, and then it independently binds to the cell membrane through its kinase domain without the involvement of the membrane-bound protein RAS. We observed notable changes between the protein complexes (p110α-p85α) of native and mutant structures at the atomic level using molecular dynamics simulations. Simulation results revealed formation of a less number of hydrogen bonds between the two subunits in the mutant protein complex which led the two subunits to move away from each other. This increase in distance between the subunits led to an expanded structure, thereby increasing the flexibility of the protein complex. Furthermore, a study of secondary structure elements and the electrostatic potential of the protein also gave a molecular insight into the change in interaction patterns of the protein with the plasma membrane. Our finding clearly indicates the role of mutation in oncogenesis and provides an insight into considering the structural aspects to handle this mutation.
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Affiliation(s)
- Jatin Sharma
- Structural Bioinformatics
Lab, CSIR-Institute of Himalayan Bioresource
Technology (CSIR-IHBT), Palampur, Himachal Pradesh 176061, India
- Biotechnology Division, CSIR-IHBT, Palampur, Himachal Pradesh 176061, India
| | - Vijay Bhardwaj
- Structural Bioinformatics
Lab, CSIR-Institute of Himalayan Bioresource
Technology (CSIR-IHBT), Palampur, Himachal Pradesh 176061, India
- Biotechnology Division, CSIR-IHBT, Palampur, Himachal Pradesh 176061, India
| | - Rituraj Purohit
- Structural Bioinformatics
Lab, CSIR-Institute of Himalayan Bioresource
Technology (CSIR-IHBT), Palampur, Himachal Pradesh 176061, India
- Biotechnology Division, CSIR-IHBT, Palampur, Himachal Pradesh 176061, India
- Academy of Scientific & Innovative Research (AcSIR), CSIR-IHBT Campus, Palampur, Himachal Pradesh 176061, India
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14
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Buchanan CM, Lee KL, Shepherd PR. For Better or Worse: The Potential for Dose Limiting the On-Target Toxicity of PI 3-Kinase Inhibitors. Biomolecules 2019; 9:biom9090402. [PMID: 31443495 PMCID: PMC6770514 DOI: 10.3390/biom9090402] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 08/15/2019] [Accepted: 08/21/2019] [Indexed: 02/07/2023] Open
Abstract
The hyper-activation of the phosphoinositide (PI) 3-kinase signaling pathway is a hallmark of many cancers and overgrowth syndromes, and as a result, there has been intense interest in the development of drugs that target the various isoforms of PI 3-kinase. Given the key role PI 3-kinases play in many normal cell functions, there is significant potential for the disruption of essential cellular functions by PI 3-kinase inhibitors in normal tissues; so-called on-target drug toxicity. It is, therefore, no surprise that progress within the clinical development of PI 3-kinase inhibitors as single-agent anti-cancer therapies has been slowed by the difficulty of identifying a therapeutic window. The aim of this review is to place the cellular, tissue and whole-body effects of PI 3-kinase inhibition in the context of understanding the potential for dose limiting on-target toxicities and to introduce possible strategies to overcome these.
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Affiliation(s)
- Christina M Buchanan
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Kate L Lee
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Peter R Shepherd
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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15
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Zhang S, Zhang W, Zeng X, Zhao W, Wang Z, Dong X, Jia Y, Shen J, Chen R, Lin X. Inhibition of Rac1 activity alleviates PM2.5-induced pulmonary inflammation via the AKT signaling pathway. Toxicol Lett 2019; 310:61-69. [DOI: 10.1016/j.toxlet.2019.04.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/05/2019] [Accepted: 04/11/2019] [Indexed: 01/09/2023]
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16
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Zhu J, Ke K, Xu L, Jin J. Theoretical studies on the selectivity mechanisms of PI3Kδ inhibition with marketed idelalisib and its derivatives by 3D-QSAR, molecular docking, and molecular dynamics simulation. J Mol Model 2019; 25:242. [DOI: 10.1007/s00894-019-4129-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 07/09/2019] [Indexed: 01/01/2023]
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17
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Duvelisib: A 2018 Novel FDA-Approved Small Molecule Inhibiting Phosphoinositide 3-Kinases. Pharmaceuticals (Basel) 2019; 12:ph12020069. [PMID: 31064155 PMCID: PMC6631818 DOI: 10.3390/ph12020069] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/01/2019] [Accepted: 05/04/2019] [Indexed: 12/13/2022] Open
Abstract
Duvelisib (Copiktra®) is a dual inhibitor of phosphoinositide 3-kinases (PI3Kδ and PI3Kγ). In 2018, duvelisib was first approved by the Food and Drug Administration (FDA) for the treatment of adult patients with relapsed or refractory chronic lymphocytic leukaemia (CLL)/ small lymphocytic lymphoma (SLL) after at least two prior therapies. Duvelisib has also been approved under accelerated track for relapsed or refractory follicular lymphoma (FL) after at least two prior systemic therapies. In this review, we provide a series of information about duvelisib, such as the development of clinical trials for LLC/SLL and FL and the steps used for its synthesis.
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18
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Methot JL, Zhou H, Kattar SD, McGowan MA, Wilson K, Garcia Y, Deng Y, Altman M, Fradera X, Lesburg C, Fischmann T, Li C, Alves S, Shah S, Fernandez R, Goldenblatt P, Hill A, Shaffer L, Chen D, Tong V, McLeod RL, Yu H, Bass A, Kemper R, Gatto NT, LaFranco-Scheuch L, Trotter BW, Guzi T, Katz JD. Structure Overhaul Affords a Potent Purine PI3Kδ Inhibitor with Improved Tolerability. J Med Chem 2019; 62:4370-4382. [DOI: 10.1021/acs.jmedchem.8b01818] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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19
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Zhang M, Jang H, Nussinov R. The mechanism of PI3Kα activation at the atomic level. Chem Sci 2019; 10:3671-3680. [PMID: 30996962 PMCID: PMC6430085 DOI: 10.1039/c8sc04498h] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 02/19/2019] [Indexed: 12/19/2022] Open
Abstract
PI3K lipid kinases phosphorylate PIP2 to PIP3 in the PI3K/Akt/mTOR pathway to regulate cellular processes. They are frequently mutated in cancer. Here we determine the PI3Kα activation mechanism at the atomic level. Unlike protein kinases where the substrate abuts the ATP, crystal structures indicate that in PI3Kα, the distance between the γ phosphate of the ATP and the PIP2 lipid substrate is over 6 Å, much too far for the phosphoryl transfer, raising the question of how catalysis is executed. PI3Kα has two subunits, the catalytic p110α and the regulatory p85α. Our simulations show that release of the autoinhibition exerted by the nSH2 domain of the p85α triggers significant conformational change in p110α, leading to the exposure of the kinase domain for membrane interaction. Structural rearrangement in the C-lobe of the kinase domain reduces the distance between the ATP γ-phosphate and the substrate, offering an explanation as to how phosphoryl transfer is executed. An alternative mechanism may involve ATP relocation. This mechanism not only explains how oncogenic mutations promote PI3Kα activation by facilitating nSH2 release, or nSH2-release-induced, allosteric motions; it also offers an innovative, PI3K isoform-specific drug discovery principle. Rather than competing with nanomolar range ATP in the ATP-binding pocket and contending with ATP pocket conservation and massive binding targets, this mechanism suggests blocking the PI3Kα sequence-specific cavity between the ATP-binding pocket and the substrate binding site. Targeting isoform-specific residues in the cavity may prevent PIP2 phosphorylation.
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Affiliation(s)
- Mingzhen Zhang
- Computational Structural Biology Section , Basic Science Program , Frederick National Laboratory for Cancer Research , Frederick , MD 21702 , USA .
| | - Hyunbum Jang
- Computational Structural Biology Section , Basic Science Program , Frederick National Laboratory for Cancer Research , Frederick , MD 21702 , USA .
| | - Ruth Nussinov
- Computational Structural Biology Section , Basic Science Program , Frederick National Laboratory for Cancer Research , Frederick , MD 21702 , USA . .,Department of Human Molecular Genetics and Biochemistry , Sackler School of Medicine , Tel Aviv University , Tel Aviv 69978 , Israel
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20
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Zhang M, Li Z, Wang G, Jang H, Sacks DB, Zhang J, Gaponenko V, Nussinov R. Calmodulin (CaM) Activates PI3Kα by Targeting the "Soft" CaM-Binding Motifs in Both the nSH2 and cSH2 Domains of p85α. J Phys Chem B 2018; 122:11137-11146. [PMID: 30047727 PMCID: PMC6422767 DOI: 10.1021/acs.jpcb.8b05982] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PI3Kα is a key lipid kinase in the PI3K/Akt pathway. Its frequent oncogenic mutations make it a primary drug target. Calmodulin (CaM) activates PI3Kα independently of extracellular signals, indicating a significant role in oncogenic PI3Kα activation. Here, we reveal the atomic-scale structures of CaM in complexes with the nSH2 and cSH2 domains of the regulatory p85α subunit of PI3Kα, and illustrate how CaM activates PI3Kα by targeting the "soft 1-5-10" CaM-binding motifs in both nSH2 and cSH2 domains. Experiment observed CaM binding cSH2 first, followed by nSH2 binding hours later. CaM typically prefers binding helical peptides. Here we observe that, unlike in cSH2, the CaM-binding motif in nSH2 populates a mixed β-sheet/α-helix/random coil structure. The population shift from a β-sheet toward CaM's favored α-helical conformation explains why the nSH2 domain needs a longer time for CaM binding in the experiments. The "soft" CaM-binding motifs in both nSH2 and cSH2 domains establish strong CaM-PI3Kα interactions, collectively facilitating PI3Kα activation. This work uncovers the structural basis for CaM-driven PI3Kα activation.
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Affiliation(s)
- Mingzhen Zhang
- Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research Sponsored by the National Cancer Institute, Frederick, Maryland 21702, United States
| | - Zhigang Li
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Guanqiao Wang
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025, China
| | - Hyunbum Jang
- Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research Sponsored by the National Cancer Institute, Frederick, Maryland 21702, United States
| | - David B. Sacks
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Jian Zhang
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025, China
| | - Vadim Gaponenko
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Ruth Nussinov
- Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research Sponsored by the National Cancer Institute, Frederick, Maryland 21702, United States
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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21
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Wang J, Gong GQ, Zhou Y, Lee WJ, Buchanan CM, Denny WA, Rewcastle GW, Kendall JD, Dickson JMJ, Flanagan JU, Shepherd PR, Yang DH, Wang MW. High-throughput screening campaigns against a PI3Kα isoform bearing the H1047R mutation identified potential inhibitors with novel scaffolds. Acta Pharmacol Sin 2018; 39:1816-1822. [PMID: 29991713 DOI: 10.1038/s41401-018-0057-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 05/30/2018] [Indexed: 12/30/2022] Open
Abstract
The phosphatidylinositol 3-kinase (PI3K) pathway is involved in many cellular functions including cell growth, metabolism, and transformation. Hyperactivation of this pathway contributes to tumorigenesis, therefore, PI3K is a major target for anticancer drug discovery. Since the PI3Kα isoform is implicated mostly in cancer, we conducted a high-throughput screening (HTS) campaign using a 3-step PI3K homogenous time-resolved fluorescence assay against this isoform bearing the H1047R mutation. A total of 288,000 synthetic and natural product-derived compounds were screened and of which, we identified 124 initial hits that were further selected by considering the predicted binding mode, relationship to known pan-assay interference compounds and previous descriptions as a lipid kinase inhibitor. A total of 24 compounds were then tested for concentration-dependent responses. These hit compounds provide novel scaffolds that can potentially be optimized to create novel PI3K inhibitors.
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22
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Liang X, Li F, Chen C, Jiang Z, Wang A, Liu X, Ge J, Hu Z, Yu K, Wang W, Zou F, Liu Q, Wang B, Wang L, Zhang S, Wang Y, Liu Q, Liu J. Discovery of (S)-2-amino-N-(5-(6-chloro-5-(3-methylphenylsulfonamido)pyridin-3-yl)-4-methylthiazol-2-yl)-3-methylbutanamide (CHMFL-PI3KD-317) as a potent and selective phosphoinositide 3-kinase delta (PI3Kδ) inhibitor. Eur J Med Chem 2018; 156:831-846. [DOI: 10.1016/j.ejmech.2018.07.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/05/2018] [Accepted: 07/15/2018] [Indexed: 01/02/2023]
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23
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Malek E, Driscoll JJ. High throughput chemical library screening identifies a novel p110-δ inhibitor that potentiates the anti-myeloma effect of bortezomib. Oncotarget 2018; 7:38523-38538. [PMID: 27229530 PMCID: PMC5122408 DOI: 10.18632/oncotarget.9568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 05/04/2016] [Indexed: 12/31/2022] Open
Abstract
Multiple myeloma (MM) remains an incurable plasma cell malignancy and drug resistance persists as the major cause of treatment failure leading to fatal outcomes. The phosphatidyl-inositol-3-kinase (PI3K) pathway is constitutively hyperactivated in MM to promote disease progression and drug resistance. While inhibiting PI3K induces apoptosis in MM and is predicted to increase tumor susceptibility to anticancer therapy, early-generation pan-PI3K inhibitors display poor clinical efficacy as well as intolerable side effects. Here, we found that PI3K activity is significantly upregulated in MM cell lines and patient tumor cells resistant to bortezomib and that the majority of PI3K activity in MM cells is dependent upon the p110-δ isoform. Genetic or pharmacologic inhibition of p110-δ substantially reduced myeloma viability and enhanced cellular sensitivity to bortezomib. Chemical library screens then identified a novel compound, DT97, that potently inhibited p110-δ kinase activity and induced apoptosis in MM cells. DT97 was evaluated in the NCI-60 panel of human cancer cell types and anticancer activity was greatest against MM, leukemia and lymphoma cells. Co-treatment with DT97 and bortezomib synergistically induced apoptosis in MM patient cells and overcame bortezomib-resistance. Although bone marrow stromal cells (BMSCs) promote MM growth, the pro-survival effects of BMSCs were significantly reduced by DT97 treatment. Co-treatment with bortezomib and DT97 reduced the growth of myeloma xenotransplants in murine models and prolonged host survival. Taken together, the results provide the basis for further clinical evaluation of p110-δ inhibitors, as monotherapy or in synergistic combinations, for the benefit of MM patients.
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Affiliation(s)
- Ehsan Malek
- Case Western Reserve University School of Medicine, Cleveland, OH, USA.,Division of Hematology and Oncology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - James J Driscoll
- Division of Hematology and Oncology, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,The Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,University of Cincinnati Cancer Institute, Cincinnati, OH, USA
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24
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Falasca M, Hamilton JR, Selvadurai M, Sundaram K, Adamska A, Thompson PE. Class II Phosphoinositide 3-Kinases as Novel Drug Targets. J Med Chem 2016; 60:47-65. [DOI: 10.1021/acs.jmedchem.6b00963] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Marco Falasca
- Metabolic
Signalling Group, School of Biomedical Sciences, CHIRI Biosciences, Curtin University, Perth, Western Australia 6845, Australia
| | - Justin R. Hamilton
- Australian
Centre for Blood Diseases and Department of Clinical Haematology, Monash University, 99 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Maria Selvadurai
- Australian
Centre for Blood Diseases and Department of Clinical Haematology, Monash University, 99 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Krithika Sundaram
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Aleksandra Adamska
- Metabolic
Signalling Group, School of Biomedical Sciences, CHIRI Biosciences, Curtin University, Perth, Western Australia 6845, Australia
| | - Philip E. Thompson
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia
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25
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Guo JL, Liu YY, Pei YZ. Synthesis and biological evaluation of 3-(piperidin-4-yl)isoxazolo[4,5-d]pyrimidine derivatives as novel PI3Kδ inhibitors. CHINESE CHEM LETT 2015. [DOI: 10.1016/j.cclet.2015.05.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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26
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Dong SH, Tang W, Lukk T, Yu Y, Nair SK, van der Donk WA. The enterococcal cytolysin synthetase has an unanticipated lipid kinase fold. eLife 2015; 4. [PMID: 26226635 PMCID: PMC4550811 DOI: 10.7554/elife.07607] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 07/29/2015] [Indexed: 11/13/2022] Open
Abstract
The enterococcal cytolysin is a virulence factor consisting of two post-translationally modified peptides that synergistically kill human immune cells. Both peptides are made by CylM, a member of the LanM lanthipeptide synthetases. CylM catalyzes seven dehydrations of Ser and Thr residues and three cyclization reactions during the biosynthesis of the cytolysin large subunit. We present here the 2.2 Å resolution structure of CylM, the first structural information on a LanM. Unexpectedly, the structure reveals that the dehydratase domain of CylM resembles the catalytic core of eukaryotic lipid kinases, despite the absence of clear sequence homology. The kinase and phosphate elimination active sites that affect net dehydration are immediately adjacent to each other. Characterization of mutants provided insights into the mechanism of the dehydration process. The structure is also of interest because of the interactions of human homologs of lanthipeptide cyclases with kinases such as mammalian target of rapamycin.
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Affiliation(s)
- Shi-Hui Dong
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Weixin Tang
- Roger Adams Laboratory, Department of Chemistry, Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Tiit Lukk
- Cornell High Energy Synchrotron Source, Ithaca, United States
| | - Yi Yu
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Satish K Nair
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Wilfred A van der Donk
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, United States
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27
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Exploring the isoform selectivity of TGX-221 related pyrido[1,2-a]pyrimidinone-based Class IA PI 3-kinase inhibitors: Synthesis, biological evaluation and molecular modelling. Bioorg Med Chem 2015; 23:3796-808. [DOI: 10.1016/j.bmc.2015.03.073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 03/26/2015] [Accepted: 03/28/2015] [Indexed: 01/24/2023]
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28
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Abstract
Rac and PI3Ks are intracellular signal transducers able to regulate multiple signaling pathways fundamental for cell behavior. PI3Ks are lipid kinases that produce phosphorylated lipids which, in turn, transduce extracellular cues within the cell, while Rac is a small G protein that impacts on actin organization. Compelling evidence indicates that in multiple circumstances the 2 signaling pathways appear intermingled. For instance, phosphorylated lipids produced by PI3Ks recruit and activate GEF and GAP proteins, key modulators of Rac function. Conversely, PI3Ks interact with activated Rac, leading to Rac signaling amplification. This review summarizes the molecular mechanisms underlying the cross-talk between Rac and PI3K signaling in 2 different processes, cell migration and ROS production.
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Affiliation(s)
- Carlo C Campa
- a Molecular Biotechnology Center; Department of Molecular Biotechnology and Health Sciences; University of Torino ; Torino , Italy
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29
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Mountford SJ, Zheng Z, Sundaram K, Jennings IG, Hamilton JR, Thompson PE. Class II but Not Second Class-Prospects for the Development of Class II PI3K Inhibitors. ACS Med Chem Lett 2015; 6:3-6. [PMID: 25589915 DOI: 10.1021/ml500354e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Class II PI3 kinases are emerging from the shadows of their Class I cousins. The data emerging from PIK3C2 genetic modification studies and from siRNA knockdown suggest important roles in physiology and pathology. With some well-studied Class I isoform inhibitors showing strong Class II activity and a wealth of crystallographic information available, the structural similarity of these isoforms to Class I provides both the opportunity and the challenge in design of selective pharmacological inhibitors.
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Affiliation(s)
- Simon J. Mountford
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Zhaohua Zheng
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia
- Australian
Centre for Blood Diseases and Department of Clinical Haematology,
L6, Monash University, 89 Commerical Road, Prahran, Victoria 3181, Australia
| | - Krithika Sundaram
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Ian G. Jennings
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Justin R. Hamilton
- Australian
Centre for Blood Diseases and Department of Clinical Haematology,
L6, Monash University, 89 Commerical Road, Prahran, Victoria 3181, Australia
| | - Philip E. Thompson
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia
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30
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Gkeka P, Evangelidis T, Pavlaki M, Lazani V, Christoforidis S, Agianian B, Cournia Z. Investigating the structure and dynamics of the PIK3CA wild-type and H1047R oncogenic mutant. PLoS Comput Biol 2014; 10:e1003895. [PMID: 25340423 PMCID: PMC4207468 DOI: 10.1371/journal.pcbi.1003895] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 09/08/2014] [Indexed: 12/19/2022] Open
Abstract
The PIK3CA gene is one of the most frequently mutated oncogenes in human cancers. It encodes p110α, the catalytic subunit of phosphatidylinositol 3-kinase alpha (PI3Kα), which activates signaling cascades leading to cell proliferation, survival, and cell growth. The most frequent mutation in PIK3CA is H1047R, which results in enzymatic overactivation. Understanding how the H1047R mutation causes the enhanced activity of the protein in atomic detail is central to developing mutant-specific therapeutics for cancer. To this end, Surface Plasmon Resonance (SPR) experiments and Molecular Dynamics (MD) simulations were carried out for both wild-type (WT) and H1047R mutant proteins. An expanded positive charge distribution on the membrane binding regions of the mutant with respect to the WT protein is observed through MD simulations, which justifies the increased ability of the mutated protein variant to bind to membranes rich in anionic lipids in our SPR experiments. Our results further support an auto-inhibitory role of the C-terminal tail in the WT protein, which is abolished in the mutant protein due to loss of crucial intermolecular interactions. Moreover, Functional Mode Analysis reveals that the H1047R mutation alters the twisting motion of the N-lobe of the kinase domain with respect to the C-lobe and shifts the position of the conserved P-loop residues in the vicinity of the active site. These findings demonstrate the dynamical and structural differences of the two proteins in atomic detail and propose a mechanism of overactivation for the mutant protein. The results may be further utilized for the design of mutant-specific PI3Kα inhibitors that exploit the altered mutant conformation. The PI3Kα protein is involved in cellular processes such as cell growth, division, and formation of new blood vessels (angiogenesis) that aid cancer cell survival. In certain types of cancer cells, PI3Kα is found to be altered compared to healthy cells. These PI3Kα alterations, called mutations, are found in 27% of breast cancer patients, 24% of endometrial cancer patients, and 15% of colon cancer patients. PI3Kα mutations cause the protein to become overactivated and may contribute to tumor growth. The most common PI3Kα amino acid mutation is a histidine changed to an arginine: H1047R. Understanding how the H1047R mutation overactivates PI3Kα is central to developing therapeutics for cancer patients who bear PI3Kα mutations. To this end, we performed simulations and experiments of the mutated and physiological proteins to explain why the mutant protein becomes overactivated. Our results indicate structural and dynamical differences between the mutant and physiological proteins that may affect the PI3Kα function. Based on these differences, we propose a mechanism that highlights the series of events that lead to the mutant H1047R PI3Kα overactivation. This study provides insights into developing mutant-specific PI3Kα inhibitors that exploit the altered conformation of the mutant with respect to the physiological protein.
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Affiliation(s)
- Paraskevi Gkeka
- Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | | | - Maria Pavlaki
- Department of Molecular Biology and Genetics, Democritus University of Thrace, Alexandroupolis, Greece
| | - Vasiliki Lazani
- Department of Biomedical Research, Institute of Molecular Biology and Biotechnology-Foundation for Research and Technology (IMBB-BR/FORTH), Ioannina, Greece
| | - Savvas Christoforidis
- Department of Biomedical Research, Institute of Molecular Biology and Biotechnology-Foundation for Research and Technology (IMBB-BR/FORTH), Ioannina, Greece
- Department of Medicine, University of Ioannina, Ioannina, Greece
| | - Bogos Agianian
- Department of Molecular Biology and Genetics, Democritus University of Thrace, Alexandroupolis, Greece
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, Athens, Greece
- * E-mail:
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31
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The structural basis for mTOR function. Semin Cell Dev Biol 2014; 36:91-101. [PMID: 25289568 DOI: 10.1016/j.semcdb.2014.09.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 09/10/2014] [Accepted: 09/12/2014] [Indexed: 01/22/2023]
Abstract
The phosphoinositide 3-kinase (PI3K) related protein kinases (PIKKs) are a family of protein kinases with a diverse range of vital cellular functions. Recent high-resolution crystal structures of the protein kinase mTOR suggest general architectural principles that are likely to be common to all of the PIKKs. Furthermore, the structures make clear the close relationship of the PIKKs to the PI3Ks. However, the structures also make clear the unique features of mTOR that enable its substrate specificity. The active site is deeply recessed and flanked by structural elements unique to the PIKKs, namely, the FRB domain, the LST8 binding element, and a C-terminal stretch of helices known as the FATC domain. The FRB has a conserved element in it that is part of a bipartite substrate recognition mechanism that is probably characteristic of all of the PIKKs. The FRB also binds the mTOR inhibitor rapamycin that has been referred to as an allosteric inhibitor, implying that this inhibitor is actually a competitive inhibitor of the protein substrate. This bipartite substrate-binding site also helps clarify how rapamycin can result in substrate-specific inhibition.
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32
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Zhang D, Iyer LM, Burroughs AM, Aravind L. Resilience of biochemical activity in protein domains in the face of structural divergence. Curr Opin Struct Biol 2014; 26:92-103. [PMID: 24952217 DOI: 10.1016/j.sbi.2014.05.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 05/20/2014] [Indexed: 01/07/2023]
Abstract
Recent studies point to the prevalence of the evolutionary phenomenon of drastic structural transformation of protein domains while continuing to preserve their basic biochemical function. These transformations span a wide spectrum, including simple domains incorporated into larger structural scaffolds, changes in the structural core, major active site shifts, topological rewiring and extensive structural transmogrifications. Proteins from biological conflict systems, such as toxin-antitoxin, restriction-modification, CRISPR/Cas, polymorphic toxin and secondary metabolism systems commonly display such transformations. These include endoDNases, metal-independent RNases, deaminases, ADP ribosyltransferases, immunity proteins, kinases and E1-like enzymes. In eukaryotes such transformations are seen in domains involved in chromatin-related peptide recognition and protein/DNA-modification. Intense selective pressures from 'arms-race'-like situations in conflict and macromolecular modification systems could favor drastic structural divergence while preserving function.
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Affiliation(s)
- Dapeng Zhang
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Lakshminarayan M Iyer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - A Maxwell Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
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33
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Shen HJ, Sun YH, Zhang SJ, Jiang JX, Dong XW, Jia YL, Shen J, Guan Y, Zhang LH, Li FF, Lin XX, Wu XM, Xie QM, Yan XF. Cigarette smoke-induced alveolar epithelial-mesenchymal transition is mediated by Rac1 activation. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1840:1838-49. [PMID: 24508121 DOI: 10.1016/j.bbagen.2014.01.033] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 01/13/2014] [Accepted: 01/28/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Epithelial-mesenchymal transition (EMT) is the major pathophysiological process in lung fibrosis observed in chronic obstructive pulmonary disease (COPD) and lung cancer. Smoking is a risk factor for developing EMT, yet the mechanism remains largely unknown. In this study, we investigated the role of Rac1 in cigarette smoke (CS) induced EMT. METHODS EMT was induced in mice and pulmonary epithelial cells by exposure of CS and cigarette smoke extract (CSE) respectively. RESULTS Treatment of pulmonary epithelial cells with CSE elevated Rac1 expression associated with increased TGF-β1 release. Blocking TGF-β pathway restrained CSE-induced changes in EMT-related markers. Pharmacological inhibition or knockdown of Rac1 decreased the CSE exposure induced TGF-β1 release and ameliorated CSE-induced EMT. In CS-exposed mice, pharmacological inhibition of Rac1 reduced TGF-β1 release and prevented aberrations in expression of EMT markers, suggesting that Rac1 is a critical signaling molecule for induction of CS-stimulated EMT. Furthermore, Rac1 inhibition or knockdown abrogated CSE-induced Smad2 and Akt (PKB, protein kinase B) activation in pulmonary epithelial cells. Inhibition of Smad2, PI3K (phosphatidylinositol 3-kinase) or Akt suppressed CSE-induced changes in epithelial and mesenchymal marker expression. CONCLUSIONS AND GENERAL SIGNIFICANCE Altogether, these data suggest that CS initiates EMT through Rac1/Smad2 and Rac1/PI3K/Akt signaling pathway. Our data provide new insights into the fundamental basis of EMT and suggest a possible new course of therapy for COPD and lung cancer.
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Affiliation(s)
- Hui-juan Shen
- The Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou 310009, China; Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Yan-hong Sun
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Shui-juan Zhang
- Pharmacy College of Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Jun-xia Jiang
- The Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou 310009, China; Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Xin-wei Dong
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Yong-liang Jia
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Jian Shen
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Yan Guan
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Lin-hui Zhang
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Fen-fen Li
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Xi-xi Lin
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Xi-mei Wu
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China
| | - Qiang-min Xie
- Zhejiang Respiratory Drugs Research Laboratory of State Food and Drug Administration of China, Medical College of Zhejiang University, Hangzhou 310058, China; Laboratory Animal Center of Zhejiang University, Hangzhou 310058, China.
| | - Xiao-feng Yan
- The Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou 310009, China.
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34
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Castillo JJ, Iyengar M, Kuritzky B, Bishop KD. Isotype-specific inhibition of the phosphatidylinositol-3-kinase pathway in hematologic malignancies. Onco Targets Ther 2014; 7:333-42. [PMID: 24591840 PMCID: PMC3937185 DOI: 10.2147/ott.s34641] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In the last decade, the advent of biological targeted therapies has revolutionized the management of several types of cancer, especially in the realm of hematologic malignancies. One of these pathways, and the center of this review, is the phosphatidylinositol-3-kinase (PI3K) pathway. The PI3K pathway seems to play an important role in the pathogenesis and survival advantage in hematologic malignancies, such as leukemia, lymphoma, and myeloma. The objectives of the present review, hence, are to describe the current knowledge on the PI3K pathway and its isoforms, and to summarize preclinical and clinical studies using PI3K inhibitors, focusing on the advances made in hematologic malignancies.
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Affiliation(s)
- Jorge J Castillo
- Division of Hematologic Malignancies, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Meera Iyengar
- Division of Hematology and Oncology, Rhode Island Hospital, Providence, RI, USA
| | - Benjamin Kuritzky
- Division of Hematology and Oncology, Rhode Island Hospital, Providence, RI, USA
| | - Kenneth D Bishop
- Division of Hematology and Oncology, Rhode Island Hospital, Providence, RI, USA
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35
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Shymanets A, Prajwal, Bucher K, Beer-Hammer S, Harteneck C, Nürnberg B. p87 and p101 subunits are distinct regulators determining class IB phosphoinositide 3-kinase (PI3K) specificity. J Biol Chem 2013; 288:31059-68. [PMID: 24014027 DOI: 10.1074/jbc.m113.508234] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Class IB phosphoinositide 3-kinase γ (PI3Kγ) comprises a single catalytic p110γ subunit, which binds to two non-catalytic subunits, p87 or p101, and controls a plethora of fundamental cellular responses. The non-catalytic subunits are assumed to be redundant adaptors for Gβγ enabling G-protein-coupled receptor-mediated regulation of PI3Kγ. Growing experimental data provide contradictory evidence. To elucidate the roles of the non-catalytic subunits in determining the specificity of PI3Kγ, we tested the impact of p87 and p101 in heterodimeric p87-p110γ and p101-p110γ complexes on the modulation of PI3Kγ activity in vitro and in living cells. RT-PCR, biochemical, and imaging data provide four lines of evidence: (i) specific expression patterns of p87 and p101, (ii) up-regulation of p101, providing the basis to consider p87 as a protein forming a constitutively and p101 as a protein forming an inducibly expressed PI3Kγ, (iii) differences in basal and stimulated enzymatic activities, and (iv) differences in complex stability, all indicating apparent diversity within class IB PI3Kγ. In conclusion, expression and activities of PI3Kγ are modified differently by p87 and p101 in vitro and in living cells, arguing for specific regulatory roles of the non-catalytic subunits in the differentiation of PI3Kγ signaling pathways.
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Affiliation(s)
- Aliaksei Shymanets
- From the Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics and Interfaculty Centre of Pharmacogenomics and Pharmaceutical Research, University of Tübingen, 72074 Tübingen, Germany
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36
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Wang F, Chen Y. Pharmacophore models generation by catalyst and phase consensus-based virtual screening protocol against PI3Kα inhibitors. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2012.751592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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37
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Yardley DA. Combining mTOR Inhibitors with Chemotherapy and Other Targeted Therapies in Advanced Breast Cancer: Rationale, Clinical Experience, and Future Directions. Breast Cancer (Auckl) 2013; 7:7-22. [PMID: 23492649 PMCID: PMC3579426 DOI: 10.4137/bcbcr.s10071] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Improvements in survival of patients with breast cancer have been attributed to the development of agents that target key components of dysregulated pathways involved in oncogenesis and progression of breast cancer. Aberrant mammalian target of rapamycin (mTOR) activation has been implicated in oncogenesis, angiogenesis, and the development of estrogen independence and resistance to chemotherapy in breast tumors. Several mTOR inhibitors (sirolimus, everolimus, temsirolimus, and ridaforolimus) have demonstrated antitumor activity in breast cancer cells. Combining mTOR inhibitors with endocrine therapies has demonstrated clinical antitumor activity in patients with metastatic breast cancer. In addition, mTOR inhibitor combinations with various targeted biologic agents or cytotoxic chemotherapeutic agents are being examined in more than 40 clinical trials with some early promising results. Combination therapies targeting multiple components of these central signaling pathways may be an optimal treatment strategy for patients with advanced breast cancer.
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38
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Comerford I, Litchfield W, Kara E, McColl SR. PI3Kγ drives priming and survival of autoreactive CD4(+) T cells during experimental autoimmune encephalomyelitis. PLoS One 2012; 7:e45095. [PMID: 23028778 PMCID: PMC3441529 DOI: 10.1371/journal.pone.0045095] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 08/17/2012] [Indexed: 11/20/2022] Open
Abstract
The class IB phosphoinositide 3-kinase gamma enzyme complex (PI3Kγ) functions in multiple signaling pathways involved in leukocyte activation and migration, making it an attractive target in complex human inflammatory diseases including MS. Here, using pik3cg−/− mice and a selective PI3Kγ inhibitor, we show that PI3Kγ promotes development of experimental autoimmune encephalomyelitis (EAE). In pik3cg−/− mice, EAE is markedly suppressed and fewer leukocytes including CD4+ and CD8+ T cells, granulocytes and mononuclear phagocytes infiltrate the CNS. CD4+ T cell priming in secondary lymphoid organs is reduced in pik3cg−/− mice following immunisation. This is attributable to defects in DC migration concomitant with a failure of full T cell activation following TCR ligation in the absence of p110γ. Together, this results in suppressed autoreactive T cell responses in pik3cg−/− mice, with more CD4+ T cells undergoing apoptosis and fewer cytokine-producing Th1 and Th17 cells in lymphoid organs and the CNS. When administered from onset of EAE, the orally active PI3Kγ inhibitor AS605240 caused inhibition and reversal of clinical disease, and demyelination and cellular pathology in the CNS was reduced. These results strongly suggest that inhibitors of PI3Kγ may be useful therapeutics for MS.
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MESH Headings
- Administration, Oral
- Animals
- Apoptosis/drug effects
- Apoptosis/immunology
- CD4-Positive T-Lymphocytes/drug effects
- CD4-Positive T-Lymphocytes/enzymology
- CD4-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/drug effects
- CD8-Positive T-Lymphocytes/immunology
- Cell Movement/drug effects
- Cell Movement/immunology
- Cell Survival/drug effects
- Cell Survival/immunology
- Central Nervous System/drug effects
- Central Nervous System/immunology
- Central Nervous System/pathology
- Class Ib Phosphatidylinositol 3-Kinase/deficiency
- Class Ib Phosphatidylinositol 3-Kinase/metabolism
- Cross-Priming/drug effects
- Cross-Priming/immunology
- Cytokines/biosynthesis
- Dendritic Cells/drug effects
- Dendritic Cells/enzymology
- Dendritic Cells/immunology
- Dendritic Cells/pathology
- Encephalomyelitis, Autoimmune, Experimental/enzymology
- Encephalomyelitis, Autoimmune, Experimental/etiology
- Encephalomyelitis, Autoimmune, Experimental/immunology
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Female
- Gene Deletion
- Humans
- Mice
- Mice, Inbred C57BL
- Protein Kinase Inhibitors/administration & dosage
- Protein Kinase Inhibitors/pharmacology
- Quinoxalines/administration & dosage
- Quinoxalines/pharmacology
- Signal Transduction/drug effects
- Signal Transduction/immunology
- Th1 Cells/drug effects
- Th1 Cells/immunology
- Th17 Cells/drug effects
- Th17 Cells/immunology
- Thiazolidinediones/administration & dosage
- Thiazolidinediones/pharmacology
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Affiliation(s)
- Iain Comerford
- Chemokine Biology Laboratory, the School of Molecular & Biomedical Science, the University of Adelaide, Adelaide, South Australia, Australia.
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39
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Murray JM, Sweeney ZK, Chan BK, Balazs M, Bradley E, Castanedo G, Chabot C, Chantry D, Flagella M, Goldstein DM, Kondru R, Lesnick J, Li J, Lucas MC, Nonomiya J, Pang J, Price S, Salphati L, Safina B, Savy PPA, Seward EM, Ultsch M, Sutherlin DP. Potent and highly selective benzimidazole inhibitors of PI3-kinase delta. J Med Chem 2012; 55:7686-95. [PMID: 22877085 DOI: 10.1021/jm300717c] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inhibition of PI3Kδ is considered to be an attractive mechanism for the treatment of inflammatory diseases and leukocyte malignancies. Using a structure-based design approach, we have identified a series of potent and selective benzimidazole-based inhibitors of PI3Kδ. These inhibitors do not occupy the selectivity pocket between Trp760 and Met752 that is induced by other families of PI3Kδ inhibitors. Instead, the selectivity of the compounds for inhibition of PI3Kδ relative to other PI3K isoforms appears to be due primarily to the strong interactions these inhibitors are able to make with Trp760 in the PI3Kδ binding pocket. The pharmacokinetic properties and the ability of compound 5 to inhibit the function of B-cells in vivo are described.
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Affiliation(s)
- Jeremy M Murray
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
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40
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Kang BN, Ha SG, Ge XN, Reza Hosseinkhani M, Bahaie NS, Greenberg Y, Blumenthal MN, Puri KD, Rao SP, Sriramarao P. The p110δ subunit of PI3K regulates bone marrow-derived eosinophil trafficking and airway eosinophilia in allergen-challenged mice. Am J Physiol Lung Cell Mol Physiol 2012; 302:L1179-91. [PMID: 22427531 DOI: 10.1152/ajplung.00005.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Trafficking and recruitment of eosinophils during allergic airway inflammation is mediated by the phosphatidylinositol 3-kinase (PI3K) family of signaling molecules. The role played by the p110δ subunit of PI3K (PI3K p110δ) in regulating eosinophil trafficking and recruitment was investigated using a selective pharmacological inhibitor (IC87114). Treatment with the PI3K p110δ inhibitor significantly reduced murine bone marrow-derived eosinophil (BM-Eos) adhesion to VCAM-1 as well as ICAM-1 and inhibited activation-induced changes in cell morphology associated with reduced Mac-1 expression and aberrant cell surface localization/distribution of Mac-1 and α4. Infused BM-Eos demonstrated significantly decreased rolling and adhesion in inflamed cremaster muscle microvessels of mice treated with IC87114 compared with vehicle-treated mice. Furthermore, inhibition of PI3K p110δ significantly attenuated eotaxin-1-induced BM-Eos migration and prevented eotaxin-1-induced changes in the cytoskeleton and cell morphology. Knockdown of PI3K p110δ with siRNA in BM-Eos resulted in reduced rolling, adhesion, and migration, as well as inhibition of activation-induced changes in cell morphology, validating its role in regulating trafficking and migration. Finally, in a mouse model of cockroach antigen-induced allergic airway inflammation, oral administration of the PI3K p110δ inhibitor significantly inhibited airway eosinophil recruitment, resulting in attenuation of airway hyperresponsiveness in response to methacholine, reduced mucus secretion, and expression of proinflammatory molecules (found in inflammatory zone-1 and intelectin-1). Overall, these findings indicate the important role played by PI3K p110δ in mediating BM-Eos trafficking and migration by regulating adhesion molecule expression and localization/distribution as well as promoting changes in cell morphology that favor recruitment during inflammation.
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Affiliation(s)
- Bit Na Kang
- Laboratory of Allergic Diseases and Inflammation, Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, 55108, USA
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41
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The p101 subunit of PI3Kγ restores activation by Gβ mutants deficient in stimulating p110γ. Biochem J 2012; 441:851-8. [DOI: 10.1042/bj20111664] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
G-protein-regulated PI3Kγ (phosphoinositide 3-kinase γ) plays a crucial role in inflammatory and allergic processes. PI3Kγ, a dimeric protein formed by the non-catalytic p101 and catalytic p110γ subunits, is stimulated by receptor-released Gβγ complexes. We have demonstrated previously that Gβγ stimulates both monomeric p110γ and dimeric p110γ/p101 lipid kinase activity in vitro. In order to identify the Gβ residues responsible for the Gβγ–PI3Kγ interaction, we examined Gβ1 mutants for their ability to stimulate lipid and protein kinase activities and to recruit PI3Kγ to lipid vesicles. Our findings revealed different interaction profiles of Gβ residues interacting with p110γ or p110γ/p101. Moreover, p101 was able to rescue the stimulatory activity of Gβ1 mutants incapable of modulating monomeric p110γ. In addition to the known adaptor function of p101, in the present paper we show a novel regulatory role of p101 in the activation of PI3Kγ.
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42
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Ghigo A, Morello F, Perino A, Damilano F, Hirsch E. Specific PI3K isoform modulation in heart failure: lessons from transgenic mice. Curr Heart Fail Rep 2011; 8:168-75. [PMID: 21519914 DOI: 10.1007/s11897-011-0059-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cardiac pathophysiology heavily relies on receptor-mediated signal transduction, and pharmacologic control of such biological processes has proven successful in preventing and treating multiple heart diseases. Recent progress in the study of receptor-mediated signal transduction events in the heart highlighted the role of a family of lipid kinases known as phosphoinositide 3-kinases (PI3Ks). These enzymes are involved downstream different receptors in the production of a lipid second messenger molecule (namely phosphatidylinositol (3,4,5)-trisphosphate [PIP(3)]), which mediates a large number of biological responses critical for the heart, including cardiomyocyte growth, survival, and contractility as well as cardiovascular inflammation. This review focuses on the recent advances in the understanding of PI3K function in cardiac pathophysiology obtained by studying mouse mutants for different PI3K genes and by validating the effects of PI3K pharmacologic inhibition in preclinical models of critical cardiac diseases like heart failure.
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Affiliation(s)
- Alessandra Ghigo
- Molecular Biotechnology Center, University of Torino, Via Nizza 52, 10126, Torino, Italy
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43
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D'Abramo M, Rabal O, Oyarzabal J, Gervasio FL. Conformational Selection versus Induced Fit in Kinases: The Case of PI3K-γ. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201103264] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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44
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D'Abramo M, Rabal O, Oyarzabal J, Gervasio FL. Conformational Selection versus Induced Fit in Kinases: The Case of PI3K-γ. Angew Chem Int Ed Engl 2011; 51:642-6. [DOI: 10.1002/anie.201103264] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 10/19/2011] [Indexed: 11/09/2022]
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45
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Vadas O, Burke JE, Zhang X, Berndt A, Williams RL. Structural basis for activation and inhibition of class I phosphoinositide 3-kinases. Sci Signal 2011; 4:re2. [PMID: 22009150 DOI: 10.1126/scisignal.2002165] [Citation(s) in RCA: 212] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Phosphoinositide 3-kinases (PI3Ks) are implicated in a broad spectrum of cellular activities, such as growth, proliferation, differentiation, migration, and metabolism. Activation of class I PI3Ks by mutation or overexpression correlates with the development and maintenance of various human cancers. These PI3Ks are heterodimers, and the activity of the catalytic subunits is tightly controlled by the associated regulatory subunits. Although the same p85 regulatory subunits associate with all class IA PI3Ks, the functional outcome depends on the isotype of the catalytic subunit. New PI3K partners that affect the signaling by the PI3K heterodimers have been uncovered, including phosphate and tensin homolog (PTEN), cyclic adenosine monophosphate-dependent protein kinase (PKA), and nonstructural protein 1. Interactions with PI3K regulators modulate the intrinsic membrane affinity and either the rate of phosphoryl transfer or product release. Crystal structures for the class I and class III PI3Ks in complexes with associated regulators and inhibitors have contributed to developing isoform-specific inhibitors and have shed light on the numerous regulatory mechanisms controlling PI3K activation and inhibition.
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Affiliation(s)
- Oscar Vadas
- Laboratory of Molecular Biology, Medical Research Council, Hills Road, Cambridge CB20QH, UK.
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Charrier JD, Durrant SJ, Golec JMC, Kay DP, Knegtel RMA, MacCormick S, Mortimore M, O'Donnell ME, Pinder JL, Reaper PM, Rutherford AP, Wang PSH, Young SC, Pollard JR. Discovery of potent and selective inhibitors of ataxia telangiectasia mutated and Rad3 related (ATR) protein kinase as potential anticancer agents. J Med Chem 2011; 54:2320-30. [PMID: 21413798 DOI: 10.1021/jm101488z] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
DNA-damaging agents are among the most frequently used anticancer drugs. However, they provide only modest benefit in most cancers. This may be attributed to a genome maintenance network, the DNA damage response (DDR), that recognizes and repairs damaged DNA. ATR is a major regulator of the DDR and an attractive anticancer target. Herein, we describe the discovery of a series of aminopyrazines with potent and selective ATR inhibition. Compound 45 inhibits ATR with a K(i) of 6 nM, shows >600-fold selectivity over related kinases ATM or DNA-PK, and blocks ATR signaling in cells with an IC(50) of 0.42 μM. Using this compound, we show that ATR inhibition markedly enhances death induced by DNA-damaging agents in certain cancers but not normal cells. This differential response between cancer and normal cells highlights the great potential for ATR inhibition as a novel mechanism to dramatically increase the efficacy of many established drugs and ionizing radiation.
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Affiliation(s)
- Jean-Damien Charrier
- Chemistry Department, Vertex Pharmaceuticals (Europe) Ltd., 88 Milton Park, Abingdon, Oxfordshire OX14 4RY, United Kingdom
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Markworth JF, Cameron-Smith D. Prostaglandin F2α stimulates PI3K/ERK/mTOR signaling and skeletal myotube hypertrophy. Am J Physiol Cell Physiol 2010; 300:C671-82. [PMID: 21191105 DOI: 10.1152/ajpcell.00549.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Cyclooxygenase (COX) enzymes mediate the synthesis of proinflammatory prostaglandin (PG) species from cellular arachidonic acid. COX/PGs have been implicated in skeletal muscle growth/regeneration; however, the mechanisms by which PGs influence skeletal muscle adaptation are poorly understood. The present study aimed to investigate PGF(2α) signaling and its role in skeletal myotube hypertrophy. PGF(2α) or the FP receptor agonist fluprostenol increased C2C12 myotube diameter. This effect was abolished by the FP receptor antagonist AL8810 and mammalian target of rapamycin (mTOR) inhibition. PGF(2α) stimulated time- and dose-dependent increases in the phosphorylation of extracellular receptor kinase (ERK)1/2 (Thr202/Tyr204), p70S6 kinase (p70S6K) (Thr389 and Thr421/Ser424), and eukaryotic initiation factor 4G (eIF4G) (Ser1108) without influencing Akt (Ser473). Pretreatment with the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 and the ERK inhibitor PD98059 blocked F prostanoid receptor signaling responses, whereas rapamycin blocked heightened p70S6K/eIF4G phosphorylation without influencing ERK1/2 phosphorylation. These data suggest that activation of the F prostanoid receptor is coupled to C2C12 myotube growth and intracellular signaling via a PI3K/ERK/mTOR-dependent pathway.
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Affiliation(s)
- James F Markworth
- School of Exercise and Nutrition Sciences, Deakin Univ., 221 Burwood Highway, Burwood, Victoria 3125, Australia
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Carter H, Samayoa J, Hruban RH, Karchin R. Prioritization of driver mutations in pancreatic cancer using cancer-specific high-throughput annotation of somatic mutations (CHASM). Cancer Biol Ther 2010; 10:582-7. [PMID: 20581473 DOI: 10.4161/cbt.10.6.12537] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Over 20,000 genes were recently sequenced in a series of 24 pancreatic cancers. We applied CHASM (Cancer-specific High-throughput Annotation of Somatic Mutations) to 963 of the missense somatic missense mutations discovered in these 24 cancers. CHASM identified putative driver mutations (false discovery rate ≤0.3) in three known pancreatic cancer driver genes (P53, SMAD4, CDKN2A). An additional 15 genes with putative driver mutations include genes coding for kinases (PIK3CG, DGKA, STK33, TTK and PRKCG), for cell cycle related proteins (NEK8), and for proteins involved in cell adhesion (CMAS, PCDHB2). These and other mutations identified by CHASM point to potential "driver genes" in pancreatic cancer that should be prioritized for additional follow-up.
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Affiliation(s)
- Hannah Carter
- Department of Biomedical Engineering and Institute for Computational Medicine, The Sol Goldman Pancreatic Cancer Research Center, Johns Hopkins Kimmel Cancer Center, Baltimore, MD, USA
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Dhalla NS, Müller AL. Protein Kinases as Drug Development Targets for Heart Disease Therapy. Pharmaceuticals (Basel) 2010; 3:2111-2145. [PMID: 27713345 PMCID: PMC4036665 DOI: 10.3390/ph3072111] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 06/03/2010] [Accepted: 06/23/2010] [Indexed: 02/07/2023] Open
Abstract
Protein kinases are intimately integrated in different signal transduction pathways for the regulation of cardiac function in both health and disease. Protein kinase A (PKA), Ca²⁺-calmodulin-dependent protein kinase (CaMK), protein kinase C (PKC), phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) are not only involved in the control of subcellular activities for maintaining cardiac function, but also participate in the development of cardiac dysfunction in cardiac hypertrophy, diabetic cardiomyopathy, myocardial infarction, and heart failure. Although all these kinases serve as signal transducing proteins by phosphorylating different sites in cardiomyocytes, some of their effects are cardioprotective whereas others are detrimental. Such opposing effects of each signal transduction pathway seem to depend upon the duration and intensity of stimulus as well as the type of kinase isoform for each kinase. In view of the fact that most of these kinases are activated in heart disease and their inhibition has been shown to improve cardiac function, it is suggested that these kinases form excellent targets for drug development for therapy of heart disease.
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Affiliation(s)
- Naranjan S Dhalla
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada.
| | - Alison L Müller
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada.
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The p110 delta structure: mechanisms for selectivity and potency of new PI(3)K inhibitors. Nat Chem Biol 2010; 6:117-24. [PMID: 20081827 PMCID: PMC2880452 DOI: 10.1038/nchembio.293] [Citation(s) in RCA: 226] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 11/30/2009] [Indexed: 12/13/2022]
Abstract
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Deregulation of the phosphoinositide 3-kinase (PI3K) pathway has been implicated in numerous pathologies like cancer, diabetes, thrombosis, rheumatoid arthritis and asthma. Recently, small molecule and ATP-competitive PI3K inhibitors with a wide range of selectivities have entered clinical development. In order to understand mechanisms underlying isoform selectivity of these inhibitors, we developed a novel expression strategy that enabled us to determine the first crystal structure of the catalytic subunit of the class IA PI3K p110δ. Structures of this enzyme in complex with a broad panel of isoform- and pan-selective class I PI3K inhibitors reveal that selectivity towards p110δ can be achieved by exploiting its conformational flexibility and the sequence diversity of active-site residues that do not contact ATP. We have used these observations to rationalize and synthesize highly selective inhibitors for p110δ with greatly improved potencies.
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