101
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Toonen JA, Anastasaki C, Smithson LJ, Gianino SM, Li K, Kesterson RA, Gutmann DH. NF1 germline mutation differentially dictates optic glioma formation and growth in neurofibromatosis-1. Hum Mol Genet 2016; 25:1703-13. [PMID: 26908603 PMCID: PMC4986327 DOI: 10.1093/hmg/ddw039] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 02/08/2016] [Indexed: 12/24/2022] Open
Abstract
Neurofibromatosis type 1 (NF1) is a common neurogenetic condition characterized by significant clinical heterogeneity. A major barrier to developing precision medicine approaches for NF1 is an incomplete understanding of the factors that underlie its inherent variability. To determine the impact of the germline NF1 gene mutation on the optic gliomas frequently encountered in children with NF1, we developed genetically engineered mice harboring two representative NF1-patient-derived Nf1 gene mutations (c.2542G>C;p.G848R and c.2041C>T;p.R681X). We found that each germline Nf1 gene mutation resulted in different levels of neurofibromin expression. Importantly, only R681X(CKO) but not G848R(CKO), mice develop optic gliomas with increased optic nerve volumes, glial fibrillary acid protein immunoreactivity, proliferation and retinal ganglion cell death, similar to Nf1 conditional knockout mice harboring a neomycin insertion (neo) as the germline Nf1 gene mutation. These differences in optic glioma phenotypes reflect both cell-autonomous and stromal effects of the germline Nf1 gene mutation. In this regard, primary astrocytes harboring the R681X germline Nf1 gene mutation exhibit increased basal astrocyte proliferation (BrdU incorporation) indistinguishable from neo(CKO) astrocytes, whereas astrocytes with the G848R mutation have lower levels of proliferation. Evidence for paracrine effects from the tumor microenvironment were revealed when R681X(CKO) mice were compared with conventional neo(CKO) mice. Relative to neo(CKO) mice, the optic gliomas from R681X(CKO) mice had more microglia infiltration and JNK(Thr183/Tyr185) activation, microglia-produced Ccl5, and glial AKT(Thr308) activation. Collectively, these studies establish that the germline Nf1 gene mutation is a major determinant of optic glioma development and growth through by both tumor cell-intrinsic and stromal effects.
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Affiliation(s)
- Joseph A Toonen
- Department of Neurology, Washington University School of Medicine, PO Box 8111, 660 S. Euclid Avenue, St. Louis, MO 63110, USA and
| | - Corina Anastasaki
- Department of Neurology, Washington University School of Medicine, PO Box 8111, 660 S. Euclid Avenue, St. Louis, MO 63110, USA and
| | - Laura J Smithson
- Department of Neurology, Washington University School of Medicine, PO Box 8111, 660 S. Euclid Avenue, St. Louis, MO 63110, USA and
| | - Scott M Gianino
- Department of Neurology, Washington University School of Medicine, PO Box 8111, 660 S. Euclid Avenue, St. Louis, MO 63110, USA and
| | - Kairong Li
- Department of Genetics, University of Alabama, Birmingham, AL 35233, USA
| | - Robert A Kesterson
- Department of Genetics, University of Alabama, Birmingham, AL 35233, USA
| | - David H Gutmann
- Department of Neurology, Washington University School of Medicine, PO Box 8111, 660 S. Euclid Avenue, St. Louis, MO 63110, USA and
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102
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Kim Y, Cha S, Seo T. Activation of the phosphatidylinositol 3-kinase/Akt pathway by viral interferon regulatory factor 2 of Kaposi's sarcoma-associated herpesvirus. Biochem Biophys Res Commun 2016; 470:650-656. [DOI: 10.1016/j.bbrc.2016.01.087] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 01/14/2016] [Indexed: 12/22/2022]
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103
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Chaisuparat R, Limpiwatana S, Kongpanitkul S, Yodsanga S, Jham BC. The Akt/mTOR pathway is activated in verrucous carcinoma of the oral cavity. J Oral Pathol Med 2016; 45:581-5. [DOI: 10.1111/jop.12422] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2015] [Indexed: 01/19/2023]
Affiliation(s)
- Risa Chaisuparat
- Department of Oral Pathology, Developing Research Unit of Prevention and Therapy of Oral Cancers and Neoplasms by Herbal Medicine; Faculty of Dentistry; Chulalongkorn University; Pathumwan Bangkok Thailand
| | | | | | - Somchai Yodsanga
- Department of Oral Pathology, Developing Research Unit of Prevention and Therapy of Oral Cancers and Neoplasms by Herbal Medicine; Faculty of Dentistry; Chulalongkorn University; Pathumwan Bangkok Thailand
| | - Bruno C. Jham
- College of Dental Medicine-Illinois; Midwestern University; Downers Grove IL USA
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104
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Zhong X, Zhao E, Tang C, Zhang W, Tan J, Dong Z, Ding HF, Cui H. Antibiotic drug tigecycline reduces neuroblastoma cells proliferation by inhibiting Akt activation in vitro and in vivo. Tumour Biol 2015; 37:7615-23. [PMID: 26687647 DOI: 10.1007/s13277-015-4613-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 12/07/2015] [Indexed: 12/20/2022] Open
Abstract
As the first member of glycylcycline bacteriostatic agents, tigecycline is approved as a novel expanded-spectrum antibiotic, which is clinically available. However, accumulating evidence indicated that tigecycline was provided with the potential application in cancer therapy. In this paper, tigecycline was shown to exert an anti-proliferative effect on neuroblastoma cell lines. Furthermore, it was found that tigecycline induced G1-phase cell cycle arrest instead of apoptosis by means of Akt pathway inhibition. In neuroblastoma cell lines, the Akt activator insulin-like growth factor-1 (hereafter referred to as IGF-1) reversed tigecycline-induced cell cycle arrest. Besides, tigecycline inhibited colony formation and suppressed neuroblastoma cells xenograft formation and growth. After tigecycline treatment in vivo, the Akt pathway inhibition was confirmed as well. Collectively, our data provided strong evidences that tigecycline inhibited neuroblastoma cells growth and proliferation through the Akt pathway inhibition in vitro and in vivo. In addition, these results were supported by previous studies concerning the application of tigecycline in human tumors treatment, suggesting that tigecycline might act as a potential candidate agent for neuroblastoma treatment.
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Affiliation(s)
- Xiaoxia Zhong
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Erhu Zhao
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Chunling Tang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Weibo Zhang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Juan Tan
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, People's Republic of China.,Institute of Pathology and Southwest Cancer Centre, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China
| | - Zhen Dong
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Han-Fei Ding
- Cancer Center, Medical College of Georgia, Georgia Regents University, Augusta, GA, 30912, USA
| | - Hongjuan Cui
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, People's Republic of China.
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105
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Chen C, Cao M, Zhu S, Wang C, Liang F, Yan L, Luo D. Discovery of a Novel Inhibitor of the Protein Tyrosine Phosphatase Shp2. Sci Rep 2015; 5:17626. [PMID: 26626996 PMCID: PMC4667271 DOI: 10.1038/srep17626] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 11/03/2015] [Indexed: 02/07/2023] Open
Abstract
Shp2 is a ubiquitously expressed protein tyrosine phosphatase (PTP) related to adult acute myelogenous leukemia and human solid tumors. In this report, we describe identification of a potent Shp2 inhibitor, Fumosorinone (Fumos) from entomogenous fungi, which shows selective inhibition of Shp2 over other tested PTPs. Using a surface plasmon resonance analysis, we further confirmed the physical interaction between Shp2 and Fumos. Fumos inhibits Shp2-dependent activation of the Ras/ERK signal pathway downstream of EGFR, and interrupts EGF-induced Gab1-Shp2 association. As expected, Fumos shows little effects on the Shp2-independent ERK1/2 activation induced by PMA or oncogenic Ras. Furthermore, Fumos down-regulates Src activation, inhibits phosphorylation of Paxillin and prevents tumor cell invasion. These results suggest that Fumos can inhibit Shp2-dependent cell signaling in human cells and has a potential for treatment of Shp2-associated diseases.
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Affiliation(s)
- Chuan Chen
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of Education, Hebei University, Baoding, Hebei 071002, P.R. China
| | - Mengmeng Cao
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of Education, Hebei University, Baoding, Hebei 071002, P.R. China
| | - Siyu Zhu
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of Education, Hebei University, Baoding, Hebei 071002, P.R. China
| | - Cuicui Wang
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of Education, Hebei University, Baoding, Hebei 071002, P.R. China
| | - Fan Liang
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of Education, Hebei University, Baoding, Hebei 071002, P.R. China
| | - Leilei Yan
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of Education, Hebei University, Baoding, Hebei 071002, P.R. China
| | - Duqiang Luo
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of Education, Hebei University, Baoding, Hebei 071002, P.R. China
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106
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Nim TH, Luo L, White JK, Clément MV, Tucker-Kellogg L. Non-canonical Activation of Akt in Serum-Stimulated Fibroblasts, Revealed by Comparative Modeling of Pathway Dynamics. PLoS Comput Biol 2015; 11:e1004505. [PMID: 26554359 PMCID: PMC4640559 DOI: 10.1371/journal.pcbi.1004505] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/11/2015] [Indexed: 12/22/2022] Open
Abstract
The dynamic behaviors of signaling pathways can provide clues to pathway mechanisms. In cancer cells, excessive phosphorylation and activation of the Akt pathway is responsible for cell survival advantages. In normal cells, serum stimulation causes brief peaks of extremely high Akt phosphorylation before reaching a moderate steady-state. Previous modeling assumed this peak and decline behavior (i.e., “overshoot”) was due to receptor internalization. In this work, we modeled the dynamics of the overshoot as a tool for gaining insight into Akt pathway function. We built an ordinary differential equation (ODE) model describing pathway activation immediately upstream of Akt phosphorylation at Thr308 (Aktp308). The model was fit to experimental measurements of Aktp308, total Akt, and phosphatidylinositol (3,4,5)-trisphosphate (PIP3), from mouse embryonic fibroblasts with serum stimulation. The canonical Akt activation model (the null hypothesis) was unable to recapitulate the observed delay between the peak of PIP3 (at 2 minutes), and the peak of Aktp308 (at 30–60 minutes). From this we conclude that the peak and decline behavior of Aktp308 is not caused by PIP3 dynamics. Models for alternative hypotheses were constructed by allowing an arbitrary dynamic curve to perturb each of 5 steps of the pathway. All 5 of the alternative models could reproduce the observed delay. To distinguish among the alternatives, simulations suggested which species and timepoints would show strong differences. Time-series experiments with membrane fractionation and PI3K inhibition were performed, and incompatible hypotheses were excluded. We conclude that the peak and decline behavior of Aktp308 is caused by a non-canonical effect that retains Akt at the membrane, and not by receptor internalization. Furthermore, we provide a novel spline-based method for simulating the network implications of an unknown effect, and we demonstrate a process of hypothesis management for guiding efficient experiments. Influential pathways of cell signalling (such as PI3K/Akt) are routinely communicated using simple textbook-like diagrams that show only the most widely-accepted steps of the pathway. At the same time, there are countless other molecular influences relevant to each pathway, documented in the published literature, and more are being published every week. It should perhaps come as little surprise that during a routine observation of the Akt activation pathway, a simulation of the canonical model was mathematically incompatible with our observed dynamics. To progress beyond the standard, simplified model without testing an unreasonable number of molecular candidates individually, we employed computational modeling to analyze the dynamics of pathway activation. We asked when and where a non-canonical deviation could occur, relative to the canonical pathway. We used the timing of downstream activation to solve for the possible times of upstream initiation. By categorizing unknown effects by their dynamics, we were able to prune away implausible hypotheses using an efficient number of in vitro experiments. At the end we had a single plausible explanation for non-canonical Akt activation in our cells, and we confirmed experimentally that Akt is retained at the membrane after PIP3 is no longer present.
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Affiliation(s)
- Tri Hieu Nim
- Computational Systems Biology Programme, Singapore-MIT Alliance, Singapore
- Systems Biology Institute (SBI), Clayton, Victoria, Australia
- Australian Regenerative Medicine Institute and Faculty of IT, Monash University, Clayton, Victoria, Australia
| | - Le Luo
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Jacob K. White
- Computational Systems Biology Programme, Singapore-MIT Alliance, Singapore
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Marie-Véronique Clément
- Systems Biology Institute (SBI), Clayton, Victoria, Australia
- Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore
- * E-mail: (MVC); (LTK)
| | - Lisa Tucker-Kellogg
- Computational Systems Biology Programme, Singapore-MIT Alliance, Singapore
- Duke-NUS Graduate Medical School Singapore, National University of Singapore, Singapore
- * E-mail: (MVC); (LTK)
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107
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Abeyrathna P, Su Y. The critical role of Akt in cardiovascular function. Vascul Pharmacol 2015; 74:38-48. [PMID: 26025205 PMCID: PMC4659756 DOI: 10.1016/j.vph.2015.05.008] [Citation(s) in RCA: 281] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 05/07/2015] [Accepted: 05/16/2015] [Indexed: 12/30/2022]
Abstract
Akt kinase, a member of AGC kinases, is important in many cellular functions including proliferation, migration, cell growth and metabolism. There are three known Akt isoforms which play critical and diverse roles in the cardiovascular system. Akt activity is regulated by its upstream regulatory pathways at transcriptional and post-translational levels. Beta-catenin/Tcf-4, GLI1 and Stat-3 are some of few known transcriptional regulators of AKT gene. Threonine 308 and serine 473 are the two critical phosphorylation sites of Akt1. Translocation of Akt to the cell membrane facilitates PDK1 phosphorylation of the threonine site. The serine site is phosphorylated by mTORC2. Ack1, Src, PTK6, TBK1, IKBKE and IKKε are some of the non-canonical pathways which affect the Akt activity. Protein-protein interactions of Akt to actin and Hsp90 increase the Akt activity while Akt binding to other proteins such as CTMP and TRB3 reduces the Akt activity. The action of Akt on its downstream targets determines its function in cardiovascular processes such as cell survival, growth, proliferation, angiogenesis, vasorelaxation, and cell metabolism. Akt promotes cell survival via caspase-9, YAP, Bcl-2, and Bcl-x activities. Inhibition of FoxO proteins by Akt also increases cell survival by transcriptional mechanisms. Akt stimulates cell growth and proliferation through mTORC1. Akt also increases VEGF secretion and mediates eNOS phosphorylation, vasorelaxation and angiogenesis. Akt can increase cellular metabolism through its downstream targets GSK3 and GLUT4. The alterations of Akt signaling play an important role in many cardiovascular pathological processes such as atherosclerosis, cardiac hypertrophy, and vascular remodeling. Several Akt inhibitors have been developed and tested as anti-tumor agents. They could be potential novel therapeutics for the cardiovascular diseases.
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Affiliation(s)
- Prasanna Abeyrathna
- Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, USA
| | - Yunchao Su
- Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, USA.
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108
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Liko D, Hall MN. mTOR in health and in sickness. J Mol Med (Berl) 2015; 93:1061-73. [DOI: 10.1007/s00109-015-1326-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 07/14/2015] [Accepted: 07/22/2015] [Indexed: 01/12/2023]
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109
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Yunn NO, Koh A, Han S, Lim JH, Park S, Lee J, Kim E, Jang SK, Berggren PO, Ryu SH. Agonistic aptamer to the insulin receptor leads to biased signaling and functional selectivity through allosteric modulation. Nucleic Acids Res 2015; 43:7688-701. [PMID: 26245346 PMCID: PMC4652772 DOI: 10.1093/nar/gkv767] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 07/16/2015] [Indexed: 12/13/2022] Open
Abstract
Due to their high affinity and specificity, aptamers have been widely used as effective inhibitors in clinical applications. However, the ability to activate protein function through aptamer-protein interaction has not been well-elucidated. To investigate their potential as target-specific agonists, we used SELEX to generate aptamers to the insulin receptor (IR) and identified an agonistic aptamer named IR-A48 that specifically binds to IR, but not to IGF-1 receptor. Despite its capacity to stimulate IR autophosphorylation, similar to insulin, we found that IR-A48 not only binds to an allosteric site distinct from the insulin binding site, but also preferentially induces Y1150 phosphorylation in the IR kinase domain. Moreover, Y1150-biased phosphorylation induced by IR-A48 selectively activates specific signaling pathways downstream of IR. In contrast to insulin-mediated activation of IR, IR-A48 binding has little effect on the MAPK pathway and proliferation of cancer cells. Instead, AKT S473 phosphorylation is highly stimulated by IR-A48, resulting in increased glucose uptake both in vitro and in vivo. Here, we present IR-A48 as a biased agonist able to selectively induce the metabolic activity of IR through allosteric binding. Furthermore, our study also suggests that aptamers can be a promising tool for developing artificial biased agonists to targeted receptors.
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Affiliation(s)
- Na-Oh Yunn
- The School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - Ara Koh
- The Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - Seungmin Han
- The Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - Jong Hun Lim
- The POSTECH Aptamer Initiative Program, POSTECH Biotech Center, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - Sehoon Park
- The Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - Jiyoun Lee
- The Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - Eui Kim
- The Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - Sung Key Jang
- The School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 790-784, South Korea The Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, South Korea The Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - Per-Olof Berggren
- The Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, South Korea The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Sung Ho Ryu
- The School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 790-784, South Korea The Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, South Korea The Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, South Korea
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110
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Khan M, Maryam A, Qazi JI, Ma T. Targeting Apoptosis and Multiple Signaling Pathways with Icariside II in Cancer Cells. Int J Biol Sci 2015. [PMID: 26221076 PMCID: PMC4515820 DOI: 10.7150/ijbs.11595] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cancer is the second leading cause of deaths worldwide. Despite concerted efforts to improve the current therapies, the prognosis of cancer remains dismal. Highly selective or specific blocking of only one of the signaling pathways has been associated with limited or sporadic responses. Using targeted agents to inhibit multiple signaling pathways has emerged as a new paradigm for anticancer treatment. Icariside II, a flavonol glycoside, is one of the major components of Traditional Chinese Medicine Herba epimedii and possesses multiple biological and pharmacological properties including anti-inflammatory, anti-osteoporosis, anti-oxidant, anti-aging, and anticancer activities. Recently, the anticancer activity of Icariside II has been extensively investigated. Here, in this review, our aim is to give our perspective on the current status of Icariside II, and discuss its natural sources, anticancer activity, molecular targets and the mechanisms of action with specific emphasis on apoptosis pathways which may help the further design and conduct of preclinical and clinical trials. Icariside II has been found to induce apoptosis in various human cancer cell lines of different origin by targeting multiple signaling pathways including STAT3, PI3K/AKT, MAPK/ERK, COX-2/PGE2 and β-Catenin which are frequently deregulated in cancers, suggesting that this collective activity rather than just a single effect may play an important role in developing Icariside II into a potential lead compound for anticancer therapy. This review suggests that Icariside II provides a novel opportunity for treatment of cancers, but additional investigations and clinical trials are still required to fully understand the mechanism of therapeutic effects to further validate it in anti-tumor therapy.
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Affiliation(s)
- Muhammad Khan
- 1. College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning 116044, P.R. China
| | - Amara Maryam
- 1. College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning 116044, P.R. China
| | - Javed Iqbal Qazi
- 2. Department of Zoology, University of the Punjab, Quaid-e-Azam Campus, Lahore 54590, Pakistan
| | - Tonghui Ma
- 1. College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning 116044, P.R. China
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111
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Cailliau K, Lescuyer A, Burnol AF, Cuesta-Marbán Á, Widmann C, Browaeys-Poly E. RasGAP Shields Akt from Deactivating Phosphatases in Fibroblast Growth Factor Signaling but Loses This Ability Once Cleaved by Caspase-3. J Biol Chem 2015; 290:19653-65. [PMID: 26109071 DOI: 10.1074/jbc.m115.644633] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Indexed: 11/06/2022] Open
Abstract
Fibroblast growth factor receptors (FGFRs) are involved in proliferative and differentiation physiological responses. Deregulation of FGFR-mediated signaling involving the Ras/PI3K/Akt and the Ras/Raf/ERK MAPK pathways is causally involved in the development of several cancers. The caspase-3/p120 RasGAP module is a stress sensor switch. Under mild stress conditions, RasGAP is cleaved by caspase-3 at position 455. The resulting N-terminal fragment, called fragment N, stimulates anti-death signaling. When caspase-3 activity further increases, fragment N is cleaved at position 157. This generates a fragment, called N2, that no longer protects cells. Here, we investigated in Xenopus oocytes the impact of RasGAP and its fragments on FGF1-mediated signaling during G2/M cell cycle transition. RasGAP used its N-terminal Src homology 2 domain to bind FGFR once stimulated by FGF1, and this was necessary for the recruitment of Akt to the FGFR complex. Fragment N, which did not associate with the FGFR complex, favored FGF1-induced ERK stimulation, leading to accelerated G2/M transition. In contrast, fragment N2 bound the FGFR, and this inhibited mTORC2-dependent Akt Ser-473 phosphorylation and ERK2 phosphorylation but not phosphorylation of Akt on Thr-308. This also blocked cell cycle progression. Inhibition of Akt Ser-473 phosphorylation and entry into G2/M was relieved by PHLPP phosphatase inhibition. Hence, full-length RasGAP favors Akt activity by shielding it from deactivating phosphatases. This shielding was abrogated by fragment N2. These results highlight the role played by RasGAP in FGFR signaling and how graded stress intensities, by generating different RasGAP fragments, can positively or negatively impact this signaling.
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Affiliation(s)
- Katia Cailliau
- From the Université de Lille 1, Sciences et Technologies, Team Signal Division Regulation, CNRS UMR 8576, SN3, 59655 Villeneuve d'Ascq Cedex, France,
| | - Arlette Lescuyer
- From the Université de Lille 1, Sciences et Technologies, Team Signal Division Regulation, CNRS UMR 8576, SN3, 59655 Villeneuve d'Ascq Cedex, France
| | - Anne-Françoise Burnol
- INSERM, U1016, Institut Cochin, Paris, France, CNRS UMR8104, Institut Cochin, 22 rue Méchain, 75014 Paris, France, the Université Paris Descartes, Sorbonne Paris Cité, 24 Rue du Faubourg Saint Jacques, 75014 Paris, France, and
| | - Álvaro Cuesta-Marbán
- the Department of Physiology, Université de Lausanne, Rue du Bugnon 7, 1005 Lausanne, Switzerland
| | - Christian Widmann
- the Department of Physiology, Université de Lausanne, Rue du Bugnon 7, 1005 Lausanne, Switzerland
| | - Edith Browaeys-Poly
- From the Université de Lille 1, Sciences et Technologies, Team Signal Division Regulation, CNRS UMR 8576, SN3, 59655 Villeneuve d'Ascq Cedex, France
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112
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Abstract
Aberrant activation of fundamental cellular processes, such as proliferation, migration and survival, underlies the development of numerous human pathophysiologies, including cancer. One of the most frequently hyperactivated pathways in cancer is the phosphoinositide 3-kinase (PI3K)/Akt signalling cascade. Three isoforms of the serine/threonine protein kinase Akt (Akt1, Akt2 and Akt3) function to regulate cell survival, growth, proliferation and metabolism. Strikingly, non-redundant and even opposing functions of Akt isoforms in the regulation of phenotypes associated with malignancy in humans have been described. However, the mechanisms by which Akt isoform-specificity is conferred are largely unknown. In the present review, we highlight recent findings that have contributed to our understanding of the complexity of Akt isoform-specific signalling and discussed potential mechanisms by which this isoform-specificity is conferred. An understanding of the mechanisms of Akt isoform-specificity has important implications for the development of isoform-specific Akt inhibitors and will be critical to finding novel targets to treat disease.
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113
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Proline-rich AKT substrate of 40-kDa (PRAS40) in the pathophysiology of cancer. Biochem Biophys Res Commun 2015; 463:161-6. [PMID: 26003731 DOI: 10.1016/j.bbrc.2015.05.041] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 05/07/2015] [Indexed: 12/18/2022]
Abstract
Dysregulation of PI3K-AKT-mTOR pathway has been reported in various pathologies, such as cancer and insulin resistance. The proline-rich AKT substrate of 40-kDa (PRAS40), also known as AKT substrate 1 (AKT1S1), lies at the crossroads of these cascades and inhibits the activity of the mTOR complex 1 (mTORC1) kinase. This review discusses the role of PRAS40 and possible feedback mechanisms, and alterations in AKT/PRAS40/mTOR signaling that have been implicated in the pathogenesis of tumor progression. Additionally, we probed new datasets extracted from Oncomine, a cancer microarray database containing datasets derived from patient samples, to further understand the role of PRAS40 (AKT1S1). These data strongly supports the hypothesis that PRAS40 may serve as a potential therapeutic target for various cancers.
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Dobashi Y, Tsubochi H, Matsubara H, Inoue J, Inazawa J, Endo S, Ooi A. Diverse involvement of isoforms and gene aberrations of Akt in human lung carcinomas. Cancer Sci 2015; 106:772-781. [PMID: 25855050 PMCID: PMC4471790 DOI: 10.1111/cas.12669] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/30/2015] [Accepted: 04/02/2015] [Indexed: 01/14/2023] Open
Abstract
Emerging evidence confirms a central role of Akt in cancer. To evaluate the relative contribution of deregulated Akt and their clinicopathological significance in lung carcinomas, overexpression, activation of Akt and AKT gene increases were investigated. Immunohistochemical staining for 108 cases revealed overexpression of total Akt, Akt1, Akt2 and Akt3 in 61.1, 47.2, 40.7 and 23.1%, respectively, and phosphorylated Akt in 42.6% of cases. Expression of total Akt, Akt2 and Akt3 were frequently observed in small cell carcinoma, but phosphorylated Akt and Akt1 were more frequently observed in squamous cell carcinoma. FISH analysis to evaluate gene increases of AKT1-3 revealed amplification of AKT1 in 4.2% and AKT1 increase by polysomy of chromosome 14 in 27.3% of cases. For AKT2, amplification was observed in 3.2% and polysomy of chromosome 19 in 26.3% of cases. AKT3 increase was observed in 40.0% of cases only by polysomy of chromosome 1. Although “FISH-positive” AKT1 and AKT2 gene increases (amplification/high-level polysomy) were found exclusively in the cases overexpressing total Akt, Akt1 or Akt2, respectively, AKT3 increase was irrelevant of Akt3 expression. Statistically, expressions of Akt2, p-Akt and cytoplasmic-p-Akt were correlated with lymph node metastasis (P = 0.0479, P = 0.0371 and P = 0.0310, respectively). Although AKT1 and AKT2 gene increase showed positive correlation with, or trend towards a positive correlation with tumor size (P = 0.0430, P = 0.0590, respectively), AKT3 did not. In conclusion, Akt isoforms are differentially involved in the pathological phenotype of lung carcinoma in a diverse manner. Because abnormality of Akt1/AKT1 and Akt2/AKT2 correlated with clinicopathological profiles, Akt1/2-specific targeting may open a novel therapeutic window for the group showing Akt deregulation.
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Affiliation(s)
- Yoh Dobashi
- Department of Pathology, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Hiroyoshi Tsubochi
- Department of Thoracic Surgery, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Hirochika Matsubara
- Second Department of Surgery, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Jun Inoue
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo, Japan.,Bioresource Research Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Johji Inazawa
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo, Japan.,Bioresource Research Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shunsuke Endo
- Department of Thoracic Surgery, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Akishi Ooi
- Department of Molecular and Cellular Pathology, Kanazawa University School of Medicine, Ishikawa, Japan
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Yip PY. Phosphatidylinositol 3-kinase-AKT-mammalian target of rapamycin (PI3K-Akt-mTOR) signaling pathway in non-small cell lung cancer. Transl Lung Cancer Res 2015; 4:165-76. [PMID: 25870799 DOI: 10.3978/j.issn.2218-6751.2015.01.04] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 12/30/2014] [Indexed: 12/13/2022]
Abstract
Non-small cell lung cancer (NSCLC) is a devastating disease with poor prognosis. Systemic chemotherapy has been the mainstay of treatment in advanced disease for many decades. Personalized targeted therapy such as epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) and crizotinib has significantly changed the treatment paradigm in NSCLC. The future success of development of molecular targeted therapy relies on the understanding of signal transduction pathways. The PI3K-Akt-mTOR pathway is commonly deregulated in human malignancy including NSCLC. Therefore, this pathway is a target for many therapeutic developments. This review will provide an overview of PI3K-Akt-mTOR signaling pathway, genetic alterations activating the pathway and clinical therapeutic development of pathway inhibitors.
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Affiliation(s)
- Po Yee Yip
- 1 Department of Medical Oncology, Chris O'Brien Lifehouse, Camperdown, NSW, Australia ; 2 Department of Medical Oncology, Macarthur Cancer Therapy Centre, Campbelltown, NSW, Australia
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Chen MZ, Hudson CA, Vincent EE, de Berker DAR, May MT, Hers I, Dayan CM, Andrews RC, Tavaré JM. Bariatric surgery in morbidly obese insulin resistant humans normalises insulin signalling but not insulin-stimulated glucose disposal. PLoS One 2015; 10:e0120084. [PMID: 25876175 PMCID: PMC4395354 DOI: 10.1371/journal.pone.0120084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 01/19/2015] [Indexed: 01/14/2023] Open
Abstract
Aims Weight-loss after bariatric surgery improves insulin sensitivity, but the underlying molecular mechanism is not clear. To ascertain the effect of bariatric surgery on insulin signalling, we examined glucose disposal and Akt activation in morbidly obese volunteers before and after Roux-en-Y gastric bypass surgery (RYGB), and compared this to lean volunteers. Materials and Methods The hyperinsulinaemic euglycaemic clamp, at five infusion rates, was used to determine glucose disposal rates (GDR) in eight morbidly obese (body mass index, BMI=47.3±2.2 kg/m2) patients, before and after RYGB, and in eight lean volunteers (BMI=20.7±0.7 kg/m2). Biopsies of brachioradialis muscle, taken at fasting and insulin concentrations that induced half-maximal (GDR50) and maximal (GDR100) GDR in each subject, were used to examine the phosphorylation of Akt-Thr308, Akt-473, and pras40, in vivo biomarkers for Akt activity. Results Pre-operatively, insulin-stimulated GDR was lower in the obese compared to the lean individuals (P<0.001). Weight-loss of 29.9±4 kg after surgery significantly improved GDR50 (P=0.004) but not GDR100 (P=0.3). These subjects still remained significantly more insulin resistant than the lean individuals (p<0.001). Weight loss increased insulin-stimulated skeletal muscle Akt-Thr308 and Akt-Ser473 phosphorylation, P=0.02 and P=0.03 respectively (MANCOVA), and Akt activity towards the substrate PRAS40 (P=0.003, MANCOVA), and in contrast to GDR, were fully normalised after the surgery (obese vs lean, P=0.6, P=0.35, P=0.46, respectively). Conclusions Our data show that although Akt activity substantially improved after surgery, it did not lead to a full restoration of insulin-stimulated glucose disposal. This suggests that a major defect downstream of, or parallel to, Akt signalling remains after significant weight-loss.
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Affiliation(s)
- Mimi Z. Chen
- School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Claire A. Hudson
- School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Emma E. Vincent
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | | | - Margaret T. May
- School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom
| | - Ingeborg Hers
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Colin M. Dayan
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff, United Kingdom
| | - Robert C. Andrews
- School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
- * E-mail:
| | - Jeremy M. Tavaré
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
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Robbins HL, Hague A. The PI3K/Akt Pathway in Tumors of Endocrine Tissues. Front Endocrinol (Lausanne) 2015; 6:188. [PMID: 26793165 PMCID: PMC4707207 DOI: 10.3389/fendo.2015.00188] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/07/2015] [Indexed: 12/29/2022] Open
Abstract
The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a key driver in carcinogenesis. Defects in this pathway in human cancer syndromes such as Cowden's disease and Multiple Endocrine Neoplasia result in tumors of endocrine tissues, highlighting its importance in these cancer types. This review explores the growing evidence from multiple animal and in vitro models and from analysis of human tumors for the involvement of this pathway in the following: thyroid carcinoma subtypes, parathyroid carcinoma, pituitary tumors, adrenocortical carcinoma, phaeochromocytoma, neuroblastoma, and gastroenteropancreatic neuroendocrine tumors. While data are not always consistent, immunohistochemistry performed on human tumor tissue has been used alongside other techniques to demonstrate Akt overactivation. We review active Akt as a potential prognostic marker and the PI3K pathway as a therapeutic target in endocrine neoplasia.
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Affiliation(s)
- Helen Louise Robbins
- Department of General Surgery, University Hospital Coventry and Warwickshire, Coventry, UK
| | - Angela Hague
- School of Oral and Dental Sciences, School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
- *Correspondence: Angela Hague,
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Glycogen synthase kinase 3 protein kinase activity is frequently elevated in human non-small cell lung carcinoma and supports tumour cell proliferation. PLoS One 2014; 9:e114725. [PMID: 25486534 PMCID: PMC4259366 DOI: 10.1371/journal.pone.0114725] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 11/13/2014] [Indexed: 11/19/2022] Open
Abstract
Background Glycogen synthase kinase 3 (GSK3) is a central regulator of cellular metabolism, development and growth. GSK3 activity was thought to oppose tumourigenesis, yet recent studies indicate that it may support tumour growth in some cancer types including in non-small cell lung carcinoma (NSCLC). We examined the undefined role of GSK3 protein kinase activity in tissue from human NSCLC. Methods The expression and protein kinase activity of GSK3 was determined in 29 fresh frozen samples of human NSCLC and patient-matched normal lung tissue by quantitative immunoassay and western blotting for the phosphorylation of three distinct GSK3 substrates in situ (glycogen synthase, RelA and CRMP-2). The proliferation and sensitivity to the small-molecule GSK3 inhibitor; CHIR99021, of NSCLC cell lines (Hcc193, H1975, PC9 and A549) and non-neoplastic type II pneumocytes was further assessed in adherent culture. Results Expression and protein kinase activity of GSK3 was elevated in 41% of human NSCLC samples when compared to patient-matched control tissue. Phosphorylation of GSK3α/β at the inhibitory S21/9 residue was a poor biomarker for activity in tumour samples. The GSK3 inhibitor, CHIR99021 dose-dependently reduced the proliferation of three NSCLC cell lines yet was ineffective against type II pneumocytes. Conclusion NSCLC tumours with elevated GSK3 protein kinase activity may have evolved dependence on the kinase for sustained growth. Our results provide further important rationale for exploring the use of GSK3 inhibitors in treating NSCLC.
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Schelch K, Hoda MA, Klikovits T, Münzker J, Ghanim B, Wagner C, Garay T, Laszlo V, Setinek U, Dome B, Filipits M, Pirker C, Heffeter P, Selzer E, Tovari J, Torok S, Kenessey I, Holzmann K, Grasl-Kraupp B, Marian B, Klepetko W, Berger W, Hegedus B, Grusch M. Fibroblast Growth Factor Receptor Inhibition Is Active against Mesothelioma and Synergizes with Radio- and Chemotherapy. Am J Respir Crit Care Med 2014; 190:763-72. [DOI: 10.1164/rccm.201404-0658oc] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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120
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Ribeiro M, Rosenstock TR, Oliveira AM, Oliveira CR, Rego AC. Insulin and IGF-1 improve mitochondrial function in a PI-3K/Akt-dependent manner and reduce mitochondrial generation of reactive oxygen species in Huntington's disease knock-in striatal cells. Free Radic Biol Med 2014; 74:129-44. [PMID: 24992836 DOI: 10.1016/j.freeradbiomed.2014.06.023] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 06/01/2014] [Accepted: 06/21/2014] [Indexed: 12/17/2022]
Abstract
Oxidative stress and mitochondrial dysfunction have been described in Huntington's disease, a disorder caused by expression of mutant huntingtin (mHtt). IGF-1 was previously shown to protect HD cells, whereas insulin prevented neuronal oxidative stress. In this work we analyzed the role of insulin and IGF-1 in striatal cells derived from HD knock-in mice on mitochondrial production of reactive oxygen species (ROS) and related antioxidant and signaling pathways influencing mitochondrial function. Insulin and IGF-1 decreased mitochondrial ROS induced by mHtt and normalized mitochondrial SOD activity, without affecting intracellular glutathione levels. IGF-1 and insulin promoted Akt phosphorylation without changing the nuclear levels of phosphorylated Nrf2 or Nrf2/ARE activity. Insulin and IGF-1 treatment also decreased mitochondrial Drp1 phosphorylation, suggesting reduced mitochondrial fragmentation, and ameliorated mitochondrial function in HD cells in a PI-3K/Akt-dependent manner. This was accompanied by increased total and phosphorylated Akt, Tfam, and mitochondrial-encoded cytochrome c oxidase II, as well as Tom20 and Tom40 in mitochondria of insulin- and IGF-1-treated mutant striatal cells. Concomitantly, insulin/IGF-1-treated mutant cells showed reduced apoptotic features. Hence, insulin and IGF-1 improve mitochondrial function and reduce mitochondrial ROS caused by mHtt by activating the PI-3K/Akt signaling pathway, in a process independent of Nrf2 transcriptional activity, but involving enhanced mitochondrial levels of Akt and mitochondrial-encoded complex IV subunit.
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Affiliation(s)
- Márcio Ribeiro
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Tatiana R Rosenstock
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Ana M Oliveira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Catarina R Oliveira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - A Cristina Rego
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
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Dennis MD, Coleman CS, Berg A, Jefferson LS, Kimball SR. REDD1 enhances protein phosphatase 2A-mediated dephosphorylation of Akt to repress mTORC1 signaling. Sci Signal 2014; 7:ra68. [PMID: 25056877 DOI: 10.1126/scisignal.2005103] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The protein kinase mTOR (mechanistic target of rapamycin) in complex 1 (mTORC1) promotes cell growth and proliferation in response to anabolic stimuli, including growth factors and nutrients. Growth factors activate mTORC1 by stimulating the kinase Akt, which phosphorylates and inhibits the tuberous sclerosis complex [TSC; which is composed of TSC1, TSC2, and TBC1D7 (Tre2-Bub2-Cdc16 domain family member 7)], thereby stimulating the mTORC1 activator Rheb (Ras homolog enriched in brain). We identified the mechanism through which REDD1 (regulated in DNA damage and development 1) represses the mTORC1 signaling pathway. We found that REDD1 promoted the protein phosphatase 2A (PP2A)-dependent dephosphorylation of Akt on Thr(308) but not on Ser(473). Consistent with previous studies showing that phosphorylation of Akt on Thr(308), but not on Ser(473), is necessary for phosphorylation of TSC2, we observed a REDD1-dependent reduction in the phosphorylation of TSC2 and subsequently in the activation state of Rheb. REDD1 and PP2A coimmunoprecipitated with Akt from wild-type but not REDD1 knockout mouse embryonic fibroblasts, suggesting that REDD1 may act as a targeting protein for the catalytic subunit of PP2A. Furthermore, binding to both Akt and PP2A was essential for REDD1 to repress signaling to mTORC1. Overall, the results demonstrate that REDD1 acts not only as a repressor of mTORC1 but also as a constant modulator of the phosphorylation of Akt in response to growth factors and nutrients.
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Affiliation(s)
- Michael D Dennis
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Catherine S Coleman
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Arthur Berg
- Division of Biostatistics and Bioinformatics, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Leonard S Jefferson
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA.
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Lundholm L, Hååg P, Juntti T, Lewensohn R, Viktorsson K. Phosphoprotein analysis reveals MEK inhibition as a way to target non-small cell lung cancer tumor initiating cells. Int J Radiat Biol 2014; 90:718-26. [DOI: 10.3109/09553002.2014.905725] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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123
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Essential role of PH domain and leucine-rich repeat protein phosphatase 2 in Nrf2 suppression via modulation of Akt/GSK3β/Fyn kinase axis during oxidative hepatocellular toxicity. Cell Death Dis 2014; 5:e1153. [PMID: 24675471 PMCID: PMC3973230 DOI: 10.1038/cddis.2014.118] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 02/21/2014] [Accepted: 02/21/2014] [Indexed: 12/30/2022]
Abstract
Instances of sustained oxidative activity have been shown to involve dysregulation of Nrf2-mediated transcriptional induction; however, mechanisms warranting Nrf2-repression remain unclear. In this study, using primary rat hepatocytes, we have attempted to identify factors that may negatively influence Nrf2 survival pathway. Though studies indicate a conspicuous association between Akt and Nrf2, a confirmatory link between the two is unaddressed. On inhibiting PI3K/Akt pathway, we observed compromised activities of antioxidant and detoxification enzymes culminating in oxidative cytotoxicity. This was accompanied by reduced nuclear retention of Nrf2 and its ARE binding affinity, increased Nrf2 ubiquitination and concurrent decline in its downstream targets. Moreover, Akt inhibition enhanced nuclear translocation as well as phosphorylation of Fyn kinase, an enzyme linked to Nrf2 degradation, by relieving GSK3β from phosphorylation-mediated repression. The involvement of Akt and Fyn kinase in influencing Nrf2 signaling was further confirmed in oxidatively stressed hepatocytes by using tert-butyl hydroperoxide (tBHP). tBHP-induced decrease in Nrf2 levels was associated with enhanced Fyn kinase phosphorylation, Fyn kinase nuclear translocation and decreased levels of phosphorylated GSK3β(Ser9) in a time-dependent manner. Interestingly, tBHP induced site-specific deactivation of Akt as only Akt(Ser473) phosphorylation was observed to be affected. Further, protein expression as well as nuclear localization of PHLPP2, a phosphatase specific for Akt(Ser473), was found to be significantly enhanced in tBHP-stressed hepatocytes. Silencing of PHLPP2 not only resulted in considerable restoration of Nrf2 signaling, enhanced Nrf2-ARE binding and reduced Nrf2 ubiquitination but also significantly suppressed tBHP-induced ROS generation and alterations in mitochondrial permeability. We infer that cellular PHLPP2 levels may aggravate oxidative toxicity by suppressing Nrf2/ARE transcriptional regulation via Akt(Se473)/GSK3β/Fyn kinase axis. The study indicates that PHLPP2 could serve as a new target for developing strategies to manage pathological conditions exacerbated due to oxidative stress.
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Islam MR, Jones SJ, Macluskey M, Ellis IR. Is there a pAkt between VEGF and oral cancer cell migration? Cell Signal 2014; 26:1294-302. [PMID: 24561239 DOI: 10.1016/j.cellsig.2014.02.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/31/2014] [Accepted: 02/13/2014] [Indexed: 11/24/2022]
Abstract
The PI3K-Akt signalling pathway is a well-established driver of cancer progression. One key process promoted by Akt phosphorylation is tumour cell motility; however the mechanism of VEGF-induced Akt phosphorylation leading to motility remains poorly understood. Previously, we have shown that Akt phosphorylation induced by different factors causes both stimulation and inhibition of motility in different cell types. However, differential phosphorylation of Akt at T308 and S473 residues by VEGF and its role in head and neck cancer cell motility and progression is unknown. The cell lines investigated in this study exhibited a change in phosphorylation of Akt in response to VEGF. However, in terms of motility, VEGF stimulated oral cancer and its associated cell lines, but not normal keratinocytes or oral mucosal fibroblasts. The addition of a PI3 kinase and mTOR inhibitor, inhibited the phosphorylation of Akt and also effectively blocked VEGF-induced oral cancer cell motility, whereas only the PI3 kinase inhibitor blocked oral cancer associated fibroblast cell motility. This study therefore discloses that two different mechanisms of Akt phosphorylation control the motility potential of different cell lines. Akt phosphorylated at both residues controls oral cancer cell motility. Furthermore, immunohistochemical analysis of VEGF positive human head and neck tumour tissues showed a significant increase in Akt phosphorylation at the T308 residue, suggesting that pAkt T308 may be associated with tumour progression in vivo.
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Affiliation(s)
- Mohammad R Islam
- Unit of Cell & Molecular Biology, The Dental School, University of Dundee, Dundee DD1 4HN, UK
| | - Sarah J Jones
- Unit of Cell & Molecular Biology, The Dental School, University of Dundee, Dundee DD1 4HN, UK
| | - Michaelina Macluskey
- Department of Oral Surgery and Medicine, The Dental School, University of Dundee, Dundee DD1 4HN, UK
| | - Ian R Ellis
- Unit of Cell & Molecular Biology, The Dental School, University of Dundee, Dundee DD1 4HN, UK.
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Yip PY, Cooper WA, Kohonen-Corish MRJ, Lin BPC, McCaughan BC, Boyer MJ, Kench JG, Horvath LG. Phosphorylated Akt expression is a prognostic marker in early-stage non-small cell lung cancer. J Clin Pathol 2013; 67:333-40. [PMID: 24265323 DOI: 10.1136/jclinpath-2013-201870] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
AIMS To determine the prognostic significance of pAkt expression in order to identify high-risk stage IB patients with non-small cell lung cancer (NSCLC) in an exploratory study. METHODS We identified 471 consecutive patients with stage IB primary NSCLC according to the American Joint Commission on Cancer 6th edition tumour-node-metastasis (TNM) staging system, who underwent surgical resection between 1990 and 2008. Patients who received neoadjuvant or adjuvant treatments were excluded. Pathology reports were reviewed, and pathological characteristics were extracted. Expression of phosphorylated Akt (pAkt) in both cytoplasmic and nuclear locations was assessed by immunohistochemistry, and clinicopathological factors were analysed against 10-year overall survival using Kaplan-Meier and Cox proportional hazards model. RESULTS 455 (96.6%) cancers were adequate for pAkt immunohistochemical analysis. The prevalence of pAkt expression in the cytoplasm and nucleus of the cancers was 60.7% and 43.7%, respectively. Patients whose cancers expressed higher levels of cytoplasmic pAkt had a trend towards longer overall survival than those with lower levels (p=0.06). Conversely, patients whose cancers expressed higher levels of nuclear pAkt had a poorer prognosis than those with lower levels of expression (p=0.02). Combined low cytoplasmic/high nuclear expression of pAkt was an independent predictor of overall survival (HR=2.86 (95% CI 1.35 to 6.04); p=0.006) when modelled with age (HR=1.05 (95% CI 1.03 to 1.07); p<0.001), extent of operation (HR=2.11 (95% CI 1.48 to 3.01); p<0.001), visceral pleural invasion (HR=1.63 (95% CI 1.24 to 2.15); p<0.001), gender, tumour size, histopathological type and grade (p>0.05). CONCLUSIONS Level of expression of pAkt in the cytoplasm and nucleus is an independent prognostic factor that may help to select patients with high-risk disease.
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Affiliation(s)
- P Y Yip
- Department of Medical Oncology, Sydney Cancer Centre, Royal Prince Alfred Hospital, , Sydney, New South Wales, Australia
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Lane A, Segura-Cabrera A, Komurov K. A comparative survey of functional footprints of EGFR pathway mutations in human cancers. Oncogene 2013; 33:5078-89. [PMID: 24166508 DOI: 10.1038/onc.2013.452] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 09/13/2013] [Accepted: 09/20/2013] [Indexed: 12/19/2022]
Abstract
Genes functioning in epidermal growth factor receptor (EGFR) signaling pathways are among the most frequently activated oncogenes in human cancers. We have conducted a comparative analysis of functional footprints (that is, effect on signaling and transcriptional landscapes in cells) associated with oncogenic and tumor suppressor mutations in EGFR pathway genes in human cancers. We have found that mutations in the EGFR pathway differentially have an impact on signaling and metabolic pathways in cancer cells in a mutation- and tissue-selective manner. For example, although signaling and metabolic profiles of breast tumors with PIK3CA or AKT1 mutations are, as expected, highly similar, they display markedly different, sometimes even opposite, profiles to those with ERBB2 or EGFR amplifications. On the other hand, although low-grade gliomas and glioblastomas, both brain cancers, driven by EGFR amplifications are highly functionally similar, their functional footprints are significantly different from lung and breast tumors driven by EGFR or ERBB2. Overall, these observations argue that, contrary to expectations, the mechanisms of tumorigenicity associated with mutations in different genes along the same pathway, or in the same gene across different tissues, may be highly different. We present evidence that oncogenic functional footprints in cancer cell lines have significantly diverged from those in tumor tissues, which potentially explains the discrepancy of our findings with the current knowledge. Nevertheless, our analyses reveal a common inflammatory response signature in EGFR-driven human cancers of different tissue origins. Our results may have implications in the design of therapeutic strategies in cancers driven by these oncogenes.
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Affiliation(s)
- A Lane
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - A Segura-Cabrera
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - K Komurov
- 1] Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA [2] Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA [3] Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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Nawa M, Matsuoka M. KCTD20, a relative of BTBD10, is a positive regulator of Akt. BMC BIOCHEMISTRY 2013; 14:27. [PMID: 24156551 PMCID: PMC3827329 DOI: 10.1186/1471-2091-14-27] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 10/22/2013] [Indexed: 12/13/2022]
Abstract
Background BTBD10 binds to Akt and protein phosphatase 2A (PP2A) and inhibits the PP2A-mediated dephosphorylation of Akt, thereby keeping Akt activated. Previous studies have suggested that BTBD10 plays an important role in preventing motor neuronal death and accelerating the growth of pancreatic beta cells. Because levels of BTBD10 expression are much lower in many non-nervous tissues than nervous tissues, there may be a relative of BTBD10 that has BTBD10-like function in non-neuronal cells. Results A 419-amino-acid BTBD10-like protein, named KCTD20 (potassium channel tetramerization protein domain containing 20), was to found to bind to all Akt isoforms and PP2A. Overexpression of KCTD20 increased Akt phosphorylation at Thr308, as BTBD10 did, which suggests that KCTD20 as well as BTBD10 positively regulates the function of Akt. KCTD20 was ubiquitously expressed in non-nervous as well as nervous tissues. Conclusions KCTD20 is a positive regulator of Akt and may play an important role in regulating the death and growth of some non-nervous and nervous cells.
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Affiliation(s)
| | - Masaaki Matsuoka
- Department of Pharmacology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8042, Japan.
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Abstract
Cell adhesion-mediated drug resistance contributes to minimal residual disease and relapse in hematological malignancies. Here, we show that adhesion of Jurkat T-acute lymphoblastic leukemia cells to substrates engaging α4β1-integrin or α5β1-integrin promotes chemoresistance to doxorubicin-induced apoptosis. Reconstituted expression of α4δ, a truncated α4-integrin with KXGFFKR as the cytoplasmic motif, in α4-deficient cells promoted chemoresistance to doxorubicin in a manner independent of α4-mediated adhesion. The adhesion-independent chemoresistance did not require β1-integrin as the heterodimeric pair, since expression of Tacδ, a monomeric nonintegrin transmembrane protein fused to the juxtamembrane KXGFFKR, was sufficient to reproduce the phenomenon. The requirement for integrin-mediated adhesion in stimulation of Akt phosphorylation and activation was bypassed for cells expressing α4δ and Tacδ. Cells expressing α4δ and Tacδ exhibited a high influx of extracellular Ca(2+), and inhibition of Ca(2+) channels with verapamil attenuated the adhesion-independent chemoresistance. Tacδ cells also exhibited greater rates of drug efflux. α4δ and Tacδ interacted with the Ca(2+)-binding protein calreticulin, in a manner dependent on the KXGFFKR motif. Adhesion-mediated engagement of α4-integrins promoted an increased calreticulin-α4 association and greater influx of extracellular Ca(2+) than in nonadherent cells. The α-integrin KXGFFKR motif is involved in adhesion-mediated control of chemoresistance in T cells.
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129
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Wang Y, Liu W, He X, Zhou F. Parkinson's Disease-Associated Dj-1 Mutations Increase Abnormal Phosphorylation of Tau Protein through Akt/Gsk-3β Pathways. J Mol Neurosci 2013; 51:911-8. [DOI: 10.1007/s12031-013-0099-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 08/12/2013] [Indexed: 10/26/2022]
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130
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Vincent EE, Elder DJE, Curwen J, Kilgour E, Hers I, Tavaré JM. Targeting non-small cell lung cancer cells by dual inhibition of the insulin receptor and the insulin-like growth factor-1 receptor. PLoS One 2013; 8:e66963. [PMID: 23826179 PMCID: PMC3691253 DOI: 10.1371/journal.pone.0066963] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 05/14/2013] [Indexed: 11/18/2022] Open
Abstract
Phase III trials of the anti-insulin-like growth factor-1 receptor (IGF1R) antibody figitumumab in non-small cell lung cancer (NSCLC) patients have been discontinued owing to lack of survival benefit. We investigated whether inhibition of the highly homologous insulin receptor (IR) in addition to the IGF1R would be more effective than inhibition of the IGF1R alone at preventing the proliferation of NSCLC cells. Signalling through IGF1R and IR in the NSCLC cell lines A549 and Hcc193 was stimulated by a combination of IGF1, IGF2 and insulin. It was inhibited by antibodies that block ligand binding, αIR3 (IGF1R) and IR47-9 (IR), and by the ATP-competitive small molecule tyrosine kinase inhibitors AZ12253801 and NVPAWD742 which inhibit both IGF1R and IR tyrosine kinases. The effect of inhibitors was determined by an anchorage-independent proliferation assay and by analysis of Akt phosphorylation. In Hcc193 cells the reduction in cell proliferation and Akt phosphorylation due to anti-IGF1R antibody was enhanced by antibody-mediated inhibition of the IR whereas in A549 cells, with a relatively low IR:IGF1R expression ratio, it was not. In each cell line proliferation and Akt phosphorylation were more effectively inhibited by AZ12253801 and NVPAWD742 than by combined αIR3 and IR47-9. When the IGF1R alone is inhibited, unencumbered signalling through the IR can contribute to continued NSCLC cell proliferation. We conclude that small molecule inhibitors targeting both the IR and IGF1R more effectively reduce NSCLC cell proliferation in a manner independent of the IR:IGF1R expression ratio, providing a therapeutic rationale for the treatment of this disease.
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Affiliation(s)
- Emma E. Vincent
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Douglas J. E. Elder
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Jon Curwen
- CIRA Discovery, AstraZeneca, Alderley Park, Macclesfield, United Kingdom
| | - Elaine Kilgour
- CIRA Discovery, AstraZeneca, Alderley Park, Macclesfield, United Kingdom
| | - Ingeborg Hers
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Jeremy M. Tavaré
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, United Kingdom
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131
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Vadlakonda L, Dash A, Pasupuleti M, Anil Kumar K, Reddanna P. The Paradox of Akt-mTOR Interactions. Front Oncol 2013; 3:165. [PMID: 23802099 PMCID: PMC3687210 DOI: 10.3389/fonc.2013.00165] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 06/07/2013] [Indexed: 12/20/2022] Open
Abstract
The serine threonine protein kinase, Akt, is at the central hub of signaling pathways that regulates cell growth, differentiation, and survival. The reciprocal relation that exists between the two activating phosphorylation sites of Akt, T308 and S473, and the two mTOR complexes, C1 and C2, forms the central controlling hub that regulates these cellular functions. In our previous review “PI3Kinase (PI3K)-AKT-mTOR and Wnt signaling pathways in cell cycle” we discussed the reciprocal relation between mTORC1 and C2 complexes in regulating cell metabolism and cell cycle progression in cancer cells. We present in this article, a hypothesis that activation of Akt-T308 phosphorylation in the presence of high ATP:AMP ratio promotes the stability of its phosphorylations and activates mTORC1 and the energy consuming biosynthetic processes. Depletion of energy leads to inactivation of mTORC1, activation of AMPK, FoxO, and promotes constitution of mTORC2 that leads to phosphorylation of Akt S473. Akt can also be activated independent of PI3K; this appears to have an advantage under situations like dietary restrictions, where insulin/insulin growth factor signaling could be a casualty.
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132
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Gao Z, Chen W, Zhang X, Cai P, Fang X, Xu Q, Sun Y, Gu Y. Icotinib, a potent and specific EGFR tyrosine kinase inhibitor, inhibits growth of squamous cell carcinoma cell line A431 through negatively regulating AKT signaling. Biomed Pharmacother 2013; 67:351-6. [DOI: 10.1016/j.biopha.2013.03.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 03/10/2013] [Indexed: 12/21/2022] Open
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Chiu TT, Sun Y, Koshkina A, Klip A. Rac-1 superactivation triggers insulin-independent glucose transporter 4 (GLUT4) translocation that bypasses signaling defects exerted by c-Jun N-terminal kinase (JNK)- and ceramide-induced insulin resistance. J Biol Chem 2013; 288:17520-31. [PMID: 23640896 DOI: 10.1074/jbc.m113.467647] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Insulin activates a cascade of signaling molecules, including Rac-1, Akt, and AS160, to promote the net gain of glucose transporter 4 (GLUT4) at the plasma membrane of muscle cells. Interestingly, constitutively active Rac-1 expression results in a hormone-independent increase in surface GLUT4; however, the molecular mechanism and significance behind this effect remain unresolved. Using L6 myoblasts stably expressing myc-tagged GLUT4, we found that overexpression of constitutively active but not wild-type Rac-1 sufficed to drive GLUT4 translocation to the membrane of comparable magnitude with that elicited by insulin. Stimulation of endogenous Rac-1 by Tiam1 overexpression elicited a similar hormone-independent gain in surface GLUT4. This effect on GLUT4 traffic could also be reproduced by acutely activating a Rac-1 construct via rapamycin-mediated heterodimerization. Strategies triggering Rac-1 "superactivation" (i.e. to levels above those attained by insulin alone) produced a modest gain in plasma membrane phosphatidylinositol 3,4,5-trisphosphate, moderate Akt activation, and substantial AS160 phosphorylation, which translated into GLUT4 translocation and negated the requirement for IRS-1. This unique signaling capacity exerted by Rac-1 superactivation bypassed the defects imposed by JNK- and ceramide-induced insulin resistance and allowed full and partial restoration of the GLUT4 translocation response, respectively. We propose that potent elevation of Rac-1 activation alone suffices to drive insulin-independent GLUT4 translocation in muscle cells, and such a strategy might be exploited to bypass signaling defects during insulin resistance.
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Affiliation(s)
- Tim Ting Chiu
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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Vadlakonda L, Pasupuleti M, Pallu R. Role of PI3K-AKT-mTOR and Wnt Signaling Pathways in Transition of G1-S Phase of Cell Cycle in Cancer Cells. Front Oncol 2013; 3:85. [PMID: 23596569 PMCID: PMC3624606 DOI: 10.3389/fonc.2013.00085] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/31/2013] [Indexed: 01/09/2023] Open
Abstract
The PI3K-Akt pathway together with one of its downstream targets, the mechanistic target of rapamycin (mTOR; also known as the mammalian target of rapamycin) is a highly deregulated pathway in cancers. mTOR exists in two complexes, mTORC1 and mTORC2. Akt phosphorylated at T308 inhibits TSC1/2 complex to activate mTORC1; mTORC2 is recognized as the kinase phosphorylating Akt at S473. Inhibition of autophagy by mTORC1 was shown to rescue disheveled (Dvl) leading to activation of Wnt pathway. Cyclin D1 and the c-Myc are activated by the Wnt signaling. Cyclin D1 is a key player in initiation of cell cycle. c-Myc triggers metabolic reprograming in G1 phase of cell cycle, which also activates the transcription factors like FoxO and p53 that play key roles in promoting the progression of cell cycle. While the role of p53 in cancer cell metabolism in arresting glycolysis and inhibition of pentose phosphate pathway has come to be recognized, there are confusions in the literature on the role of FoxO and that of rictor. FoxO was shown to be the transcription factor of rictor, in addition to the cell cycle inhibitors like p21. Rictor has dual roles; inhibition of c-Myc and constitution of mTORC2, both of which are key factors in the exit of G1-S phase and entry into G2 phase of cell cycle. A model is presented in this article, which suggests that the PI3K-Akt-mTOR and Wnt pathways converge and regulate the progression of cell cycle through G0-G1-S-phases and reprogram the metabolism in cancer cells. This model is different from the conventional method of looking at individual pathways triggering the cell cycle.
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135
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Site-specific activation of AKT protects cells from death induced by glucose deprivation. Oncogene 2013; 33:745-55. [PMID: 23396361 DOI: 10.1038/onc.2013.2] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 12/11/2012] [Indexed: 12/14/2022]
Abstract
The serine/threonine kinase AKT is a key mediator of cancer cell survival. We demonstrate that transient glucose deprivation modestly induces AKT phosphorylation at both Thr308 and Ser473. In contrast, prolonged glucose deprivation induces selective AKTThr308 phosphorylation and phosphorylation of a distinct subset of AKT downstream targets leading to cell survival under metabolic stress. Glucose-deprivation-induced AKTThr308 phosphorylation is dependent on PDK1 and PI3K but not EGF receptor or IGF1R. Prolonged glucose deprivation induces the formation of a complex of AKT, PDK1 and the GRP78 chaperone protein, directing phosphorylation of AKTThr308 but not AKTSer473. Our results reveal a novel mechanism of AKT activation under prolonged glucose deprivation that protects cells from metabolic stress. The selective activation of AKTThr308 phosphorylation that occurs during prolonged nutrient deprivation may provide an unexpected opportunity for the development and implementation of drugs targeting cell metabolism and aberrant AKT signaling.
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136
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Natarajan R, Trivedi-Vyas D, Wairkar YP. Tuberous sclerosis complex regulates Drosophila neuromuscular junction growth via the TORC2/Akt pathway. Hum Mol Genet 2013; 22:2010-23. [PMID: 23393158 DOI: 10.1093/hmg/ddt053] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Mutations in the tuberous sclerosis complex (TSC) are associated with various forms of neurodevelopmental disorders, including autism and epilepsy. The heterodimeric TSC complex, consisting of Tsc1 and Tsc2 proteins, regulates the activity of the TOR (target of rapamycin) complex via Rheb, a small GTPase. TOR, an atypical serine/threonine kinase, forms two distinct complexes TORC1 and TORC2. Raptor and Rictor serve as specific functional components of TORC1 and TORC2, respectively. Previous studies have identified Tsc1 as a regulator of hippocampal neuronal morphology and function via the TOR pathway, but it is unclear whether this is mediated via TORC1 or TORC2. In a genetic screen for aberrant synaptic growth at the neuromuscular junctions (NMJs) in Drosophila, we identified that Tsc2 mutants showed increased synaptic growth. Increased synaptic growth was also observed in rictor mutants, while raptor knockdown did not phenocopy the TSC mutant phenotype, suggesting that a novel role exists for TORC2 in regulating synapse growth. Furthermore, Tsc2 mutants showed a dramatic decrease in the levels of phosphorylated Akt, and interestingly, Akt mutants phenocopied Tsc2 mutants, leading to the hypothesis that Tsc2 and Akt might work via the same genetic pathway to regulate synapse growth. Indeed, transheterozygous analysis of Tsc2 and Akt mutants confirmed this hypothesis. Finally, our data also suggest that while overexpression of rheb results in aberrant synaptic overgrowth, the overgrowth might be independent of TORC2. Thus, we propose that at the Drosophila NMJ, TSC regulates synaptic growth via the TORC2-Akt pathway.
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Affiliation(s)
- Rajalaxmi Natarajan
- Department of Neurology, and George and Cynthia Mitchell Center for Neurodegenerative Diseases, University ofTexas Medical Branch, 301 University Blvd., Galveston, TX 77555, USA
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137
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Spears M, Cunningham CA, Taylor KJ, Mallon EA, Thomas JSJ, Kerr GR, Jack WJL, Kunkler IH, Cameron DA, Chetty U, Bartlett JMS. Authors' Reply. J Pathol 2013; 229:e2-3. [DOI: 10.1002/path.4144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 09/24/2012] [Accepted: 10/17/2012] [Indexed: 11/09/2022]
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138
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Fang Z, Grütter C, Rauh D. Strategies for the selective regulation of kinases with allosteric modulators: exploiting exclusive structural features. ACS Chem Biol 2013; 8:58-70. [PMID: 23249378 DOI: 10.1021/cb300663j] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The modulation of kinase function has become an important goal in modern drug discovery and chemical biology research. In cancer-targeted therapies, kinase inhibitors have been experiencing an upsurge, which can be measured by the increasing number of kinase inhibitors approved by the FDA in recent years. However, lack of efficacy, limited selectivity, and the emergence of acquired drug resistance still represent major bottlenecks in the clinic and challenge inhibitor development. Most known kinase inhibitors target the active kinase and are ATP competitive. A second class of small organic molecules, which address remote sites of the kinase and stabilize enzymatically inactive conformations, is rapidly moving to the forefront of kinase inhibitor research. Such allosteric modulators bind to sites that are less conserved across the kinome and only accessible upon conformational changes. These molecules are therefore thought to provide various advantages such as higher selectivity and extended drug target residence times. This review highlights various strategies that have been developed to utilizing exclusive structural features of kinases and thereby modulating their activity allosterically.
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Affiliation(s)
- Zhizhou Fang
- Technische Universität Dortmund, Fakultät
Chemie − Chemische Biologie, Otto-Hahn-Strasse
6, D-44227 Dortmund, Germany
| | - Christian Grütter
- Technische Universität Dortmund, Fakultät
Chemie − Chemische Biologie, Otto-Hahn-Strasse
6, D-44227 Dortmund, Germany
| | - Daniel Rauh
- Technische Universität Dortmund, Fakultät
Chemie − Chemische Biologie, Otto-Hahn-Strasse
6, D-44227 Dortmund, Germany
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139
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Seal S, Chatterjee P, Bhattacharya S, Pal D, Dasgupta S, Kundu R, Mukherjee S, Bhattacharya S, Bhuyan M, Bhattacharyya PR, Baishya G, Barua NC, Baruah PK, Rao PG, Bhattacharya S. Vapor of volatile oils from Litsea cubeba seed induces apoptosis and causes cell cycle arrest in lung cancer cells. PLoS One 2012; 7:e47014. [PMID: 23091605 PMCID: PMC3473030 DOI: 10.1371/journal.pone.0047014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 09/11/2012] [Indexed: 01/05/2023] Open
Abstract
Non-small cell lung carcinoma (NSCLC) is a major killer in cancer related human death. Its therapeutic intervention requires superior efficient molecule(s) as it often becomes resistant to present chemotherapy options. Here we report that vapor of volatile oil compounds obtained from Litsea cubeba seeds killed human NSCLC cells, A549, through the induction of apoptosis and cell cycle arrest. Vapor generated from the combined oils (VCO) deactivated Akt, a key player in cancer cell survival and proliferation. Interestingly VCO dephosphorylated Akt at both Ser(473) and Thr(308); through the suppression of mTOR and pPDK1 respectively. As a consequence of this, diminished phosphorylation of Bad occurred along with the decreased Bcl-xL expression. This subsequently enhanced Bax levels permitting the release of mitochondrial cytochrome c into the cytosol which concomitantly activated caspase 9 and caspase 3 resulting apoptotic cell death. Impairment of Akt activation by VCO also deactivated Mdm2 that effected overexpression of p53 which in turn upregulated p21 expression. This causes enhanced p21 binding to cyclin D1 that halted G1 to S phase progression. Taken together, VCO produces two prong effects on lung cancer cells, it induces apoptosis and blocked cancer cell proliferation, both occurred due to the deactivation of Akt. In addition, it has another crucial advantage: VCO could be directly delivered to lung cancer tissue through inhalation.
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Affiliation(s)
- Soma Seal
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
| | - Priyajit Chatterjee
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
| | - Sushmita Bhattacharya
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
| | - Durba Pal
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
| | - Suman Dasgupta
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
- CSIR-North East Institute of Science and Technology, Jorhat, Assam, India
| | - Rakesh Kundu
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
| | - Sandip Mukherjee
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
| | - Shelley Bhattacharya
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
| | - Mantu Bhuyan
- CSIR-North East Institute of Science and Technology, Jorhat, Assam, India
| | | | - Gakul Baishya
- CSIR-North East Institute of Science and Technology, Jorhat, Assam, India
| | - Nabin C. Barua
- CSIR-North East Institute of Science and Technology, Jorhat, Assam, India
| | - Pranab K. Baruah
- CSIR-North East Institute of Science and Technology, Jorhat, Assam, India
| | - Paruchuri G. Rao
- CSIR-North East Institute of Science and Technology, Jorhat, Assam, India
| | - Samir Bhattacharya
- Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati University, Santiniketan, West Bengal, India
- CSIR-North East Institute of Science and Technology, Jorhat, Assam, India
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Acquaviva J, Smith DL, Sang J, Friedland JC, He S, Sequeira M, Zhang C, Wada Y, Proia DA. Targeting KRAS-mutant non-small cell lung cancer with the Hsp90 inhibitor ganetespib. Mol Cancer Ther 2012; 11:2633-43. [PMID: 23012248 DOI: 10.1158/1535-7163.mct-12-0615] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mutant KRAS is a feature of more than 25% of non-small cell lung cancers (NSCLC) and represents one of the most prevalent oncogenic drivers in this disease. NSCLC tumors with oncogenic KRAS respond poorly to current therapies, necessitating the pursuit of new treatment strategies. Targeted inhibition of the molecular chaperone Hsp90 results in the coordinated blockade of multiple oncogenic signaling pathways in tumor cells and has thus emerged as an attractive avenue for therapeutic intervention in human malignancies. Here, we examined the activity of ganetespib, a small-molecule inhibitor of Hsp90 currently in clinical trials for NSCLCs in a panel of lung cancer cell lines harboring a diverse spectrum of KRAS mutations. In vitro, ganetespib was potently cytotoxic in all lines, with concomitant destabilization of KRAS signaling effectors. Combinations of low-dose ganetespib with MEK or PI3K/mTOR inhibitors resulted in superior cytotoxic activity than single agents alone in a subset of mutant KRAS cells, and the antitumor efficacy of ganetespib was potentiated by cotreatment with the PI3K/mTOR inhibitor BEZ235 in A549 xenografts in vivo. At the molecular level, ganetespib suppressed activating feedback signaling loops that occurred in response to MEK and PI3K/mTOR inhibition, although this activity was not the sole determinant of combinatorial benefit. In addition, ganetespib sensitized mutant KRAS NSCLC cells to standard-of-care chemotherapeutics of the antimitotic, topoisomerase inhibitor, and alkylating agent classes. Taken together, these data underscore the promise of ganetespib as a single-agent or combination treatment in KRAS-driven lung tumors.
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141
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Li W, Song R, Fang X, Wang L, Chen W, Tang P, Yu B, Sun Y, Xu Q. SBF-1, a synthetic steroidal glycoside, inhibits melanoma growth and metastasis through blocking interaction between PDK1 and AKT3. Biochem Pharmacol 2012; 84:172-81. [DOI: 10.1016/j.bcp.2012.04.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 04/05/2012] [Accepted: 04/06/2012] [Indexed: 12/30/2022]
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142
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Flierl U, Fraccarollo D, Lausenmeyer E, Rosenstock T, Schulz C, Massberg S, Bauersachs J, Schäfer A. Fractalkine activates a signal transduction pathway similar to P2Y12 and is associated with impaired clopidogrel responsiveness. Arterioscler Thromb Vasc Biol 2012; 32:1832-40. [PMID: 22652599 DOI: 10.1161/atvbaha.112.250720] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Fractalkine (FKN) activates a G(αi) protein-coupled signaling pathway similar to the one activated by ADP via P2Y(12), which is the drug target of clopidogrel. FKN levels are increased under several disease conditions associated with impaired clopidogrel responsiveness. METHODS AND RESULTS Blood samples were obtained from healthy volunteers and from 40 patients under chronic clopidogrel treatment. FKN reduced prostaglandin E1-induced vasodilator-stimulated phosphoprotein phosphorylation by ≈ 25% (P<0.01) at least partially mimicking the effect of ADP via P2Y(12). In vitro, FKN increased platelet reactivity index in clopidogrel-treated patients indicating potential activation of downstream targets of P2Y(12). When stratifying patients by their FKN levels, patients within the highest quartile of FKN (2042 ± 25 pg/mL) had the weakest response to clopidogrel (platelet reactivity index, 68 ± 4%), and patients within the lowest quartile (479 ± 50 pg/mL) had the strongest response (platelet reactivity index, 48 ± 7%; P=0.0106). FKN by itself induced phosphoinositide 3-kinase activation leading to Akt phosphorylation at Ser(473) (P<0.01 versus basal). CONCLUSIONS In addition to desensitizing platelets to prostaglandin E1 via G(αi), FKN induces phosphoinositide 3-kinase-dependent Akt phosphorylation via a G(βγ) protein similar to ADP signaling through P2Y(12). FKN increased the platelet ADP response in clopidogrel-treated patients. Once released from an atherosclerotic lesion, this mechanism could contribute locally to impaired clopidogrel responsiveness at the vulnerable plaque.
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Affiliation(s)
- Ulrike Flierl
- Klinik für Kardiologie und Angiologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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143
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Durgadoss L, Nidadavolu P, Valli RK, Saeed U, Mishra M, Seth P, Ravindranath V. Redox modification of Akt mediated by the dopaminergic neurotoxin MPTP, in mouse midbrain, leads to down‐regulation of pAkt. FASEB J 2011; 26:1473-83. [DOI: 10.1096/fj.11-194100] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Lalitha Durgadoss
- Division of Molecular and Cellular NeurosciencesNational Brain Research CentreNainwal ModeManesarIndia
| | - Prakash Nidadavolu
- Division of Molecular and Cellular NeurosciencesNational Brain Research CentreNainwal ModeManesarIndia
- Centre for NeuroscienceIndian Institute of ScienceBangaloreIndia
| | - Rupanagudi Khader Valli
- Division of Molecular and Cellular NeurosciencesNational Brain Research CentreNainwal ModeManesarIndia
| | - Uzma Saeed
- Division of Molecular and Cellular NeurosciencesNational Brain Research CentreNainwal ModeManesarIndia
| | - Mamata Mishra
- Division of Molecular and Cellular NeurosciencesNational Brain Research CentreNainwal ModeManesarIndia
| | - Pankaj Seth
- Division of Molecular and Cellular NeurosciencesNational Brain Research CentreNainwal ModeManesarIndia
| | - Vijayalakshmi Ravindranath
- Division of Molecular and Cellular NeurosciencesNational Brain Research CentreNainwal ModeManesarIndia
- Centre for NeuroscienceIndian Institute of ScienceBangaloreIndia
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144
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Activation of phosphatidylinositol 3-kinase/Akt signaling by EGF downregulates membranous E-cadherin and β-catenin and enhances invasion in nasopharyngeal carcinoma cells. Cancer Lett 2011; 318:162-72. [PMID: 22182447 DOI: 10.1016/j.canlet.2011.12.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 11/26/2011] [Accepted: 12/07/2011] [Indexed: 10/14/2022]
Abstract
Dysregulation of E-cadherin and β-catenin function in cell-cell adhesion is common in nasopharyngeal carcinoma (NPC) and correlates with metastatic disease. In this study, we examined the role of EGF-activated phosphatidylinositol 3-kinase (PI3K)-Akt signaling in E-cadherin and β-catenin regulation. We found that reduced membranous E-cadherin and β-catenin expression was positively correlated with Akt phosphorylation in NPC tissues. EGF treatment disrupted cell-cell adhesion and resulted in mesenchymal morphological features in NPC cell lines (TW01, TW04, and TW06). Western blot analysis showed that the E-cadherin protein level was partially reduced in TW04 cells only and the β-catenin levels were not considerably affected upon EGF treatment. In contrast, quantitative real-time RT-PCR showed that the E-cadherin, but not β-catenin, mRNA levels were markedly reduced by EGF in all cell lines. Immunofluorescent staining revealed that E-cadherin and β-catenin appeared to be markedly reduced on the cell surface and more localized in the cytoplasm. Inhibition of PI3K by LY294002 did not abolish the EGF-induced downregulation of E-cadherin protein or mRNA in TW04 cells but moderately increased the β-catenin protein level in TW01 cells and mRNA level in TW06 cells. However, LY294002 substantially restored or increased cell surface E-cadherin and β-catenin in all EGF-treated cell lines, in concordance with the inhibition of cell morphological changes. Moreover, LY294002 significantly blocked EGF-driven cell invasion, correlating with the elevation of membranous E-cadherin and β-catenin levels. In conclusion, EGF-induced epithelial-to-mesenchymal transition may not be only dependent on downregulation of E-cadherin protein/mRNA but also on mislocalization of E-cadherin and β-catenin. The mechanisms involved may be related, at least in part, to the PI3K-Akt pathway.
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Hers I, Vincent EE, Tavaré JM. Akt signalling in health and disease. Cell Signal 2011; 23:1515-27. [PMID: 21620960 DOI: 10.1016/j.cellsig.2011.05.004] [Citation(s) in RCA: 1078] [Impact Index Per Article: 82.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 05/09/2011] [Indexed: 11/25/2022]
Abstract
Akt (also known as protein kinase B or PKB) comprises three closely related isoforms Akt1, Akt2 and Akt3 (or PKBα/β/γ respectively). We have a very good understanding of the mechanisms by which Akt isoforms are activated by growth factors and other extracellular stimuli as well as by oncogenic mutations in key upstream regulatory proteins including Ras, PI3-kinase subunits and PTEN. There are also an ever increasing number of Akt substrates being identified that play a role in the regulation of the diverse array of biological effects of activated Akt; this includes the regulation of cell proliferation, survival and metabolism. Dysregulation of Akt leads to diseases of major unmet medical need such as cancer, diabetes, cardiovascular and neurological diseases. As a result there has been substantial investment in the development of small molecular Akt inhibitors that act competitively with ATP or phospholipid binding, or allosterically. In this review we will briefly discuss our current understanding of how Akt isoforms are regulated, the substrate proteins they phosphorylate and how this integrates with the role of Akt in disease. We will furthermore discuss the types of Akt inhibitors that have been developed and are in clinical trials for human cancer, as well as speculate on potential on-target toxicities, such as disturbances of heart and vascular function, metabolism, memory and mood, which should be monitored very carefully during clinical trial.
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Affiliation(s)
- Ingeborg Hers
- School of Physiology and Pharmacology, University of Bristol, UK
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